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Sample records for carbide coated fibers

  1. Interface coatings for Carbon and Silicon Carbide Fibers in Silicon Carbide Matrixes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Interface coatings for fiber-reinforced composites are an enabling technology for high temperature ceramic matrix composites. Because of their availability and...

  2. Silicon Carbide/Boron Nitride Dual In-Line Coating of Silicon Carbide Fiber Tows Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project will demonstrate monolayer and dual layer coating of SiC fiber by leveraging Laser Chemical Vapor Deposition techniques developed by Free...

  3. Microstructural Study of Titanium Carbide Coating on Cemented Carbide

    DEFF Research Database (Denmark)

    Vuorinen, S.; Horsewell, Andy

    1982-01-01

    Titanium carbide coating layers on cemented carbide substrates have been investigated by transmission electron microscopy. Microstructural variations within the typically 5µm thick chemical vapour deposited TiC coatings were found to vary with deposit thickness such that a layer structure could...

  4. Silicon carbide fibers and articles including same

    Science.gov (United States)

    Garnier, John E; Griffith, George W

    2015-01-27

    Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500.degree. C. to approximately 2000.degree. C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01.times.10.sup.2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

  5. Methods for producing silicon carbide fibers

    Science.gov (United States)

    Garnier, John E.; Griffith, George W.

    2016-03-01

    Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500.degree. C. to approximately 2000.degree. C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01.times.10.sup.2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

  6. Producing Silicon Carbide/Silicon Nitride Fibers

    Science.gov (United States)

    1986-01-01

    Manufacturing process makes CxSiyNz fibers. Precursor fibers spun from extruding machine charged with polycarbosilazane resin. When pyrolyzed, resin converted to cross-linked mixture of silicon carbide and silicon nitride, still in fiber form. CxSiyNz fibers promising substitutes for carbon fibers in high-strength, low-weight composites where high electrical conductivity unwanted.

  7. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    Science.gov (United States)

    Corman, Gregory Scot; Luthra, Krishan Lal

    1999-01-01

    A fiber-reinforced silicon--silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon--silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  8. Development of tungsten carbide-cobalt coatings

    Science.gov (United States)

    Fitzsimmons, Mark

    1999-09-01

    The discovery of WC, and the development of cemented carbides (WC-Co and WC-TiC-Co) have spawned advancements in higher speed machining of steel. The development of chemically vapor deposited (CVD) coatings has allowed even greater speeds to be realized. The production of titanium components, well known for their high specific strength, low density, corrosion resistance, and elevated temperature properties, would greatly benefit from a similar development allowing high speed machining processes. Currently, no known tool material exists that can effectively machine titanium at high speeds due to insufficient high temperature strength and/or chemical resistance. To address this problem an investigation into the development of a composite tool material combining toughness, high temperature strength and chemical resistance was pursued. Cemented carbide (WC-Co) is currently the most chemically resistant and commercially used tool material for machining Ti. The concept of applying a WC-Co coating on a high temperature deformation resistant substrate material was investigated. Two approaches, namely (i) laminated and (ii) co-deposited coatings, were chosen to chemically vapor deposit WC-Co. Thermodynamic and kinetic calculations were performed to aid in the development of CVD processes for deposition of WC and Co. The systems investigated were WF6-CH4-H2 and WCl6-CH4-H 2 for WC deposition and CoCl2-H2 for Co deposition. In the case of laminated structures the goal was to deposit nanometer scale alternating layers of WC and Co. However, development of a laminated structure led to the discovery that porosity always occurred in the Co layers at the WC/Co interface. Mass balance calculations, SEM, EDS, XRD, and metallographic analyses aided in determining that the porosity was due to the Kirkendall effect. It was observed that the diffusion of Co was enhanced by higher concentrations of soluble C in the Co layers. Effective diffusion barriers, such as TiC, were found to help

  9. Rapid Fabrication of Carbide Matrix/Carbon Fiber Composites

    Science.gov (United States)

    Williams, Brian E.; Bernander, Robert E.

    2007-01-01

    Composites of zirconium carbide matrix material reinforced with carbon fibers can be fabricated relatively rapidly in a process that includes a melt infiltration step. Heretofore, these and other ceramic matrix composites have been made in a chemical vapor infiltration (CVI) process that takes months. The finished products of the CVI process are highly porous and cannot withstand temperatures above 3,000 F (approx.1,600 C). In contrast, the melt-infiltration-based process takes only a few days, and the composite products are more nearly fully dense and have withstood temperatures as high as 4,350 F (approx.2,400 C) in a highly oxidizing thrust chamber environment. Moreover, because the melt- infiltration-based process takes much less time, the finished products are expected to cost much less. Fabrication begins with the preparation of a carbon fiber preform that, typically, is of the size and shape of a part to be fabricated. By use of low-temperature ultraviolet-enhanced chemical vapor deposition, the carbon fibers in the preform are coated with one or more interfacial material(s), which could include oxides. The interfacial material helps to protect the fibers against chemical attack during the remainder of the fabrication process and against oxidation during subsequent use; it also enables slippage between the fibers and the matrix material, thereby helping to deflect cracks and distribute loads. Once the fibers have been coated with the interfacial material, the fiber preform is further infiltrated with a controlled amount of additional carbon, which serves as a reactant for the formation of the carbide matrix material. The next step is melt infiltration. The preform is exposed to molten zirconium, which wicks into the preform, drawn by capillary action. The molten metal fills most of the interstices of the preform and reacts with the added carbon to form the zirconium carbide matrix material. The zirconium does not react with the underlying fibers because they

  10. Stress in tungsten carbide-diamond like carbon multilayer coatings

    NARCIS (Netherlands)

    Pujada, B.R.; Tichelaar, F.D.; Janssen, G.C.A.M.

    2007-01-01

    Tungsten carbide-diamond like carbon (WC-DLC) multilayer coatings have been prepared by sputter deposition from a tungsten-carbide target and periodic switching on and off of the reactive acetylene gas flow. The stress in the resulting WC-DLC multilayers has been studied by substrate curvature.

  11. Ultrathin fiber poly-3-hydroxybutyrate, modified by silicon carbide nanoparticles

    Science.gov (United States)

    Olkhov, A. A.; Krutikova, A. A.; Goldshtrakh, M. A.; Staroverova, O. V.; Iordanskii, A. L.; Ischenko, A. A.

    2016-11-01

    The article presents the results of studies the composite fibrous material based on poly-3-hydroxybutyrate (PHB) and nano-size silicon carbide obtained by the electrospinning method. Size distribution of the silicon carbide nanoparticles in the fiber was estimated by X-ray diffraction technique. It is shown that immobilization of the SiC nanoparticles to the PHB fibers contributes to obtaining essentially smaller diameter of fibers, high physical-mechanical characteristics and increasing resistance to degradation in comparison with the fibers of PHB.

  12. Tribological Characteristics of Tungsten Carbide Reinforced Arc Sprayed Coatings using Different Carbide Grain Size Fractions

    Directory of Open Access Journals (Sweden)

    W. Tillmann

    2017-06-01

    Full Text Available Tungsten carbide reinforced coatings play an important role in the field of surface engineering to protect stressed surfaces against wear. For thermally sprayed coatings, it is already shown that the tribological properties get mainly determined by the carbide grain size fraction. Within the scope of this study, the tribological characteristics of iron based WC-W2C reinforced arc sprayed coatings deposited using cored wires consisting of different carbide grain size fractions were examined. Microstructural characteristics of the produced coatings were scrutinized using electron microscopy and x-ray diffraction analyses. Ball-on-disk test as well as Taber Abraser and dry sand rubber wheel test were employed to analyze both the dry sliding and the abrasive wear behavior. It was shown that a reduced carbide grain size fraction as filling leads to an enhanced wear resistance against sliding. In terms of the Taber Abraser test, it is also demonstrated that a fine carbide grain size fraction results in an improved wear resistant against abrasion. As opposed to that, a poorer wear resistance was found within the dry sand rubber wheel tests. The findings show that the operating mechanisms for both abrasion tests affect the stressed surface in a different way, leading either to microcutting or microploughing.

  13. Surface coating metrology of carbides of cutting tools

    Science.gov (United States)

    Parfenov, V. D.; Basova, G. D.

    2017-10-01

    The coatings were studied by their main sign of the micrometric thickness by means of coating destruction and electron microscopical study of cleavage surfaces. Shock stress ruptures of heated carbides of cutting tools were performed. The discovery of the coating technology and creation of the coating structure for nonuniform and nonequilibrium conditions of the cutting process were dealt with. Multifracture microdestruction of nitride coatings, caused by complex external influences, was analysed to reveal the mechanism of interaction of elementary failures. Positive results were obtained in the form of improving the strength and wear resistance of the product, crack resistance increasing.

  14. Feasibility of Electrochemical Deposition of Nickel/Silicon Carbide Fibers Composites over Nickel Superalloys

    Science.gov (United States)

    Ambrosio, E. P.; Abdul Karim, M. R.; Pavese, M.; Biamino, S.; Badini, C.; Fino, P.

    2017-05-01

    Nickel superalloys are typical materials used for the hot parts of engines in aircraft and space vehicles. They are very important in this field as they offer high-temperature mechanical strength together with a good resistance to oxidation and corrosion. Due to high-temperature buckling phenomena, reinforcement of the nickel superalloy might be needed to increase stiffness. For this reason, it was thought to investigate the possibility of producing composite materials that might improve properties of the metal at high temperature. The composite material was produced by using electrochemical deposition method in which a composite with nickel matrix and long silicon carbide fibers was deposited over the nickel superalloy. The substrate was Inconel 718, and monofilament continuous silicon carbide fibers were chosen as reinforcement. Chemical compatibility was studied between Inconel 718 and the reinforcing fibers, with fibers both in an uncoated condition, and coated with carbon or carbon/titanium diboride. Both theoretical calculations and experiments were conducted, which suggested the use of a carbon coating over the fibers and a buffer layer of nickel to avoid unwanted reactions between the substrate and silicon carbide. Deposition was then performed, and this demonstrated the practical feasibility of the process. Yield strength was measured to detect the onset of interface debonding between the substrate and the composite layer.

  15. Method of fabricating silicon carbide coatings on graphite surfaces

    Science.gov (United States)

    Varacalle, D.J. Jr.; Herman, H.; Burchell, T.D.

    1994-07-26

    The vacuum plasma spray process produces well-bonded, dense, stress-free coatings for a variety of materials on a wide range of substrates. The process is used in many industries to provide for the excellent wear, corrosion resistance, and high temperature behavior of the fabricated coatings. In this application, silicon metal is deposited on graphite. This invention discloses the optimum processing parameters for as-sprayed coating qualities. The method also discloses the effect of thermal cycling on silicon samples in an inert helium atmosphere at about 1,600 C which transforms the coating to silicon carbide. 3 figs.

  16. Growth stress in tungsten carbide-diamond-like carbon coatings

    NARCIS (Netherlands)

    Pujada, B.R.; Tichelaar, F.D.; Arnoldbik, W.M.; Sloof, W.G.; Janssen, G.C.A.M.

    2009-01-01

    Growth stress in tungsten carbide-diamond-like carbon coatings, sputter deposited in a reactive argon/acetylene plasma, has been studied as a function of the acetylene partial pressure. Stress and microstructure have been investigated by wafer curvature and transmission electron microscopy (TEM)

  17. Continuous method of producing silicon carbide fibers

    Science.gov (United States)

    Barnard, Thomas Duncan (Inventor); Nguyen, Kimmai Thi (Inventor); Rabe, James Alan (Inventor)

    1999-01-01

    This invention pertains to a method for production of polycrystalline ceramic fibers from silicon oxycarbide (SiCO) ceramic fibers wherein the method comprises heating an amorphous ceramic fiber containing silicon and carbon in an inert environment comprising a boron oxide and carbon monoxide at a temperature sufficient to convert the amorphous ceramic fiber to a polycrystalline ceramic fiber. By having carbon monoxide present during the heating of the ceramic fiber, it is possible to achieve higher production rates on a continuous process.

  18. Highly permeable and mechanically robust silicon carbide hollow fiber membranes

    NARCIS (Netherlands)

    de Wit, Patrick; Kappert, Emiel; Lohaus, T.; Wessling, Matthias; Nijmeijer, Arian; Benes, Nieck Edwin

    2015-01-01

    Silicon carbide (SiC) membranes have shown large potential for applications in water treatment. Being able to make these membranes in a hollow fiber geometry allows for higher surface-to-volume ratios. In this study, we present a thermal treatment procedure that is tuned to produce porous silicon

  19. Coating Carbon Fibers With Platinum

    Science.gov (United States)

    Effinger, Michael R.; Duncan, Peter; Coupland, Duncan; Rigali, Mark J.

    2007-01-01

    A process for coating carbon fibers with platinum has been developed. The process may also be adaptable to coating carbon fibers with other noble and refractory metals, including rhenium and iridium. The coated carbon fibers would be used as ingredients of matrix/fiber composite materials that would resist oxidation at high temperatures. The metal coats would contribute to oxidation resistance by keeping atmospheric oxygen away from fibers when cracks form in the matrices. Other processes that have been used to coat carbon fibers with metals have significant disadvantages: Metal-vapor deposition processes yield coats that are nonuniform along both the lengths and the circumferences of the fibers. The electrical resistivities of carbon fibers are too high to be compatible with electrolytic processes. Metal/organic vapor deposition entails the use of expensive starting materials, it may be necessary to use a furnace, and the starting materials and/or materials generated in the process may be hazardous. The present process does not have these disadvantages. It yields uniform, nonporous coats and is relatively inexpensive. The process can be summarized as one of pretreatment followed by electroless deposition. The process consists of the following steps: The surfaces of the fiber are activated by deposition of palladium crystallites from a solution. The surface-activated fibers are immersed in a solution that contains platinum. A reducing agent is used to supply electrons to effect a chemical reduction in situ. The chemical reduction displaces the platinum from the solution. The displaced platinum becomes deposited on the fibers. Each platinum atom that has been deposited acts as a catalytic site for the deposition of another platinum atom. Hence, the deposition process can also be characterized as autocatalytic. The thickness of the deposited metal can be tailored via the duration of immersion and the chemical activity of the solution.

  20. Protective infrared antireflection coating based on sputtered germanium carbide

    Science.gov (United States)

    Gibson, Des; Waddell, Ewan; Placido, Frank

    2011-09-01

    This paper describes optical, durablility and environmental performance of a germanium carbide based durable antireflection coating. The coating has been demonstrated on germanium and zinc selenide infra-red material however is applicable to other materials such as zinc sulphide. The material is deposited using a novel reactive closed field magnetron sputtering technique, offering significant advantages over conventional evaporation processes for germanium carbide such as plasma enhanced chemical vapour deposition. The sputtering process is "cold", making it suitable for use on a wide range of substrates. Moreover, the drum format provide more efficient loading for high throughput production. The use of the closed field and unbalanced magnetrons creates a magnetic confinement that extends the electron mean free path leading to high ion current densities. The combination of high current densities with ion energies in the range ~30eV creates optimum thin film growth conditions. As a result the films are dense, spectrally stable, supersmooth and low stress. Films incorporate low hydrogen content resulting in minimal C-H absorption bands within critical infra-red passbands such as 3 to 5um and 8 to 12um. Tuning of germanium carbide (Ge(1-x)Cx) film refractive index from pure germanium (refractive index 4) to pure germanium carbide (refractive index 1.8) will be demonstrated. Use of film grading to achieve single and dual band anti-reflection performance will be shown. Environmental and durability levels are shown to be suitable for use in harsh external environments.

  1. Study of high resistance inorganic coatings on graphite fibers. [for graphite-epoxy composite materials

    Science.gov (United States)

    Galasso, F. S.; Veltri, R. D.; Scola, D. A.

    1979-01-01

    Coatings made of boron, silicon carbide, silica, and silica-like materials were studied to determine their ability to increase resistance of graphite fibers. The most promising results were attained by chemical vapor depositing silicon carbide on graphite fiber followed by oxidation, and drawing graphite fiber through ethyl silicate followed by appropriate heat treatments. In the silicon carbide coating studies, no degradation of the graphite fibers was observed and resistance values as high as three orders of magnitude higher than that of the uncoated fiber was attained. The strength of a composite fabricated from the coated fiber had a strength which compared favorably with those of composites prepared from uncoated fiber. For the silica-like coated fiber prepared by drawing the graphite fiber through an ethyl silicate solution followed by heating, coated fiber resistances about an order of magnitude greater than that of the uncoated fiber were attained. Composites prepared using these fibers had flexural strengths comparable with those prepared using uncoated fibers, but the shear strengths were lower.

  2. Synthesis of silicon carbide fibers from polycarbosilane by electrospinning method

    Science.gov (United States)

    Yue, Yuan

    Silicon carbide (SiC) is widely used in many fields due to its unique properties. Bulk SiC normally has a flexural strength of 500 -- 550 MPa, a Vickers hardness of ~27 GPa, a Young's modulus of 380 -- 430 GPa, and a thermal conductivity of approximately 120 W/mK. SiC fibers are of great interest since they are the good candidates for reinforcing ceramic matrix composites (CMCs) because of the weavability and high temperature strength of about two to three GPa at about 1000 °C. Silicon carbide fibers have been synthesized from polycarbosilane (PCS) with ~25 μm diameter using the melt-spinning method, followed by the curing and pyrolysis. In order to fabricate SiC fibers with small diameters, electrospinning method has been studied. The electrospinning technique is notable in that the fiber diameters can be controlled over a scale of nanometers to micrometers by controlling the processing parameters. However, there have only been limited studies of synthesis of silicon carbide fibers from polycarbosilane by electrospinning method. Moreover, there is no previous report for tensile strength testing of SiC fibers synthesized by electrospinning. The main objectives of this thesis are to study these problems. In this study, SiC fibers were obtained from polycarbosilane solutions using electrospinning method. In these solutions, dimethylformamide (DMF) and xylene were used as the solvents. The spinnability of the solutions was studied at different polycarbosilane concentrations, as were the ratios between DMF and xylene. The influence of electrospinning parameters such as voltage, flow rate and volume ratio of solvent on fiber diameter were studied. It was found that a minimal DMF content was ii required for the solutions to be spinnable for each PCS concentration. However, DMF content could not exceed 40% of the solvent volume, otherwise PCS could not be dissolved. The fiber diameters increased with increasing flow rate, and slightly decreased with increasing applied

  3. Processes and applications of silicon carbide nanocomposite fibers

    Science.gov (United States)

    Shin, D. G.; Cho, K. Y.; Jin, E. J.; Riu, D. H.

    2011-10-01

    Various types of SiC such as nanowires, thin films, foam, and continuous fibers have been developed since the early 1980s, and their applications have been expanded into several new applications, such as for gas-fueled radiation heater, diesel particulate filter (DPF), ceramic fiber separators and catalyst/catalyst supports include for the military, aerospace, automobile and electronics industries. For these new applications, high specific surface area is demanded and it has been tried by reducing the diameter of SiC fiber. Furthermore, functional nanocomposites show potentials in various harsh environmental applications. In this study, silicon carbide fiber was prepared through electrospinning of the polycarbosilane (PCS) with optimum molecular weight distribution which was synthesized by new method adopting solid acid catalyst such as ZSM-5 and γ-Al2O3. Functional elements such as aluminum, titanium, tungsten and palladium easily doped in the precursor fiber and remained in the SiC fiber after pyrolysis. The uniform SiC fibers were produced at the condition of spinning voltage over 20 kV from the PCS solution as the concentration of 1.3 g/ml in DMF/Toluene (3:7) and pyrolysis at 1200°C. Pyrolyzed products were processed into several interesting applications such as thermal batteries, hydrogen sensors and gas filters.

  4. ELABORATION OF AN EPOXY COATING REINFORCED WITH ZIRCONIUM CARBIDE NANOSTRUCTURES

    Directory of Open Access Journals (Sweden)

    Lucia G. Díaz-Barriga

    2013-12-01

    Full Text Available This work shows the preparation of a transparent epoxy coating reinforced with 200 PPM of zirconium carbide nanostructures. The nanostructures of ZrC were prepared by mechanosynthesis. The additive characteristics analyzed by X-ray diffraction (XRD and scanning electron microscopy (SEM were presented. Epoxy coating adhesion on a steel plate was analyzed using MEB. Thermogravimetric analysis (TGA was performed to the reinforced paints between 20-700 °C. The reinforced enamel was compared with an enamel without nanostructures. There is not vaporization of reinforced enamel at a 95 y 100 °C with ZrC particles size of 10 µm y 120 nm respectively. The final enamel degradation is slower when there is a 14% by weight of the residue and 426 °C with 120nm diameter particles.

  5. Coating parameters of zirconium carbide on advanced TRISO fuels

    Science.gov (United States)

    Dulude, Michael C.

    The feasibility of using very high temperature reactors (VHTR) as part of the next generation of nuclear reactors greatly depends on the tri-structural isotropic (TRISO) fuel particles reliability to retain both gaseous and metallic fission products created in irradiated UO2. Most research devoted to TRISO fuel particles has focused on the characteristics and retention ability of silicon carbide as the main barrier against metallic fission products. This work investigates the deposition parameters necessary to create advanced TRISO particles consisting of the standard SiC TRISO coatings with an additional layer of ZrC applied directly to the UO2 fuel kernel. The additional ZrC layer will act as an oxygen getter to prevent failure mechanisms experienced in TRISO particles. Two failure mechanisms that are of the most concern are the over pressurization of the particles and kernel migration within the TRISO particles. In this study successful ZrC coatings were created and the deposition characteristics were analyzed via optical and SEM microscopy techniques. The ZrC layer was confirmed through XRD analysis. This investigation also reduced U3O8 microspheres to UO2 in an argon atmosphere. The oxygen to metal ratio from the reduced U3O8 was back calculated from oxidation analysis performed with a TGA machine. Once consistent repeatability is shown with coating surrogate zirconia kernels, advanced TRISO coatings will be deposited on the UO2 fuel kernels.

  6. Microstructures and Wear Performance of PTAW Deposited Ni-Based Coatings with Spherical Tungsten Carbide

    Directory of Open Access Journals (Sweden)

    Dewei Deng

    2015-10-01

    Full Text Available The Ni-based coatings with different content of spherical tungsten carbide were deposited by plasma transfer arc welding (PTAW method on 304 austenitic stainless steel sheets in this study. The microstructure and wear property of spherical tungsten carbide particle reinforced composite coatings were investigated by means of optical microscope, scanning electron microscope (SEM, X-ray diffraction (XRD, electron probe microanalysis (EPMA and sliding wear test. It is shown that the fraction of spherical tungsten carbides has an important influence on microstructure of Ni-based overlay. The Ni40 overlay consists of γ-Ni dendrites with interdendritic Ni-based eutectics, borides and carbides improving the wear resistance. In the case of composite coatings with different content of tungsten carbide, many new phases are observed, such as Ni2W4C and NiW. In addition, there are a large number of irregular structures in composite coatings, such as acicular structure and irregular stripe organization. The results of sliding wear test indicate that the mass loss of coatings is influenced by the content of tungsten carbide. The mass loss decreases with the increase of tungsten carbide fraction. At high load, the abrasive resistance of composite coating with 60 wt. % tungsten carbide is improved about 50-fold compared to that of Ni40 overlay.

  7. Time-Dependent Stress Rupture Strength Degradation of Hi-Nicalon Fiber-Reinforced Silicon Carbide Composites at Intermediate Temperatures

    Science.gov (United States)

    Sullivan, Roy M.

    2016-01-01

    The stress rupture strength of silicon carbide fiber-reinforced silicon carbide composites with a boron nitride fiber coating decreases with time within the intermediate temperature range of 700 to 950 degree Celsius. Various theories have been proposed to explain the cause of the time-dependent stress rupture strength. The objective of this paper is to investigate the relative significance of the various theories for the time-dependent strength of silicon carbide fiber-reinforced silicon carbide composites. This is achieved through the development of a numerically based progressive failure analysis routine and through the application of the routine to simulate the composite stress rupture tests. The progressive failure routine is a time-marching routine with an iterative loop between a probability of fiber survival equation and a force equilibrium equation within each time step. Failure of the composite is assumed to initiate near a matrix crack and the progression of fiber failures occurs by global load sharing. The probability of survival equation is derived from consideration of the strength of ceramic fibers with randomly occurring and slow growing flaws as well as the mechanical interaction between the fibers and matrix near a matrix crack. The force equilibrium equation follows from the global load sharing presumption. The results of progressive failure analyses of the composite tests suggest that the relationship between time and stress-rupture strength is attributed almost entirely to the slow flaw growth within the fibers. Although other mechanisms may be present, they appear to have only a minor influence on the observed time-dependent behavior.

  8. High surface area silicon carbide-coated carbon aerogel

    Science.gov (United States)

    Worsley, Marcus A; Kuntz, Joshua D; Baumann, Theodore F; Satcher, Jr, Joe H

    2014-01-14

    A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust. Carbon aerogels can be coated with sol-gel silica and the silica can be converted to silicone carbide, improved the thermal stability of the carbon aerogel.

  9. Deposition of tantalum carbide coatings on graphite by laser interactions

    Science.gov (United States)

    Veligdan, James; Branch, D.; Vanier, P. E.; Barietta, R. E.

    1994-01-01

    Graphite surfaces can be hardened and protected from erosion by hydrogen at high temperatures by refractory metal carbide coatings, which are usually prepared by chemical vapor deposition (CVD) or chemical vapor reaction (CVR) methods. These techniques rely on heating the substrate to a temperature where a volatile metal halide decomposes and reacts with either a hydrocarbon gas or with carbon from the substrate. For CVR techniques, deposition temperatures must be in excess of 2000 C in order to achieve favorable deposition kinetics. In an effort to lower the bulk substrate deposition temperature, the use of laser interactions with both the substrate and the metal halide deposition gas has been employed. Initial testing involved the use of a CO2 laser to heat the surface of a graphite substrate and a KrF excimer laser to accomplish a photodecomposition of TaCl5 gas near the substrate. The results of preliminary experiments using these techniques are described.

  10. Characterization of Tungsten Carbide coatings deposited on AISI 1020 steel

    Science.gov (United States)

    Santos, A.; Gonzalez, C.; Ramirez, Z. Y.

    2017-01-01

    In order to determine the variation in the mechanical properties of AISI 1020 standardized steel, heat treated by a quenching and tempering process and with a Tungsten Carbide coating, was performed a microstructural and chemical characterization of the coating material through electron microscopy scanning and X-ray energy dispersive spectroscopy. The steel received a heat treatment of quenching performed by heating to 850°C, followed by cooling in water and tempering at a temperature of 450°C with air cooling. Tests of a) microhardness with a Wilson-Wolpert Tukon 2100B micro durometer and b) resistance to adhesive and abrasive wear following the ASTM G99-05 “Standard test method for wear testing with a pin-on-disk machine” and ASTM G65-04 “standard test method for measuring abrasion using dry sand and rubber Wheel” standards respectively. The results show that the microhardness of the steel do not vary with the load used to perform the test; in addition, the heat treatment of quenching and tempering improves by 5.5% the property while the coating increase it by 124.2%. Regarding the abrasive wear resistance, it is observed that the amount of material lost increases linearly with the distance covered. It was determined that the heat treatment decreased on average by 17.5% the volume of released material during the tests while the coating recued it by 66.7%. The amount volume of material lost during the adhesive wear tests increases linearly with the distance covered while the heat treatment decreased on average by 10.5% the volume of released material during the trial and the coating reduced it by 66.5%.

  11. Effect of bond coat and preheat on the microstructure, hardness, and porosity of flame sprayed tungsten carbide coatings

    Science.gov (United States)

    Winarto, Winarto; Sofyan, Nofrijon; Rooscote, Didi

    2017-06-01

    Thermally sprayed coatings are used to improve the surface properties of tool steel materials. Bond coatings are commonly used as intermediate layers deposited on steel substrates (i.e. H13 tool steel) before the top coat is applied in order to enhance a number of critical performance criteria including adhesion of a barrier coating, limiting atomic migration of the base metal, and corrosion resistance. This paper presents the experimental results regarding the effect of nickel bond coat and preheats temperatures (i.e. 200°C, 300°C and 400°C) on microstructure, hardness, and porosity of tungsten carbide coatings sprayed by flame thermal coating. Micro-hardness, porosity and microstructure of tungsten carbide coatings are evaluated by using micro-hardness testing, optical microscopy, scanning electron microscopy, and X-ray diffraction. The results show that nickel bond coatings reduce the susceptibility of micro crack formation at the bonding area interfaces. The percentage of porosity level on the tungsten carbide coatings with nickel bond coat decreases from 5.36 % to 2.78% with the increase of preheat temperature of the steel substrate of H13 from 200°C to 400°C. The optimum hardness of tungsten carbide coatings is 1717 HVN in average resulted from the preheat temperature of 300°C.

  12. Fiber Effects on Minicomposite Mechanical Properties for Several Silicon Carbide Fiber: Chemically Vapor-Infiltrated Silicon Carbide Matrix Systems

    Science.gov (United States)

    Morscher, Gregory N.; Martinez-Fernandez, Julian

    1999-01-01

    Several different types of SiC fiber tows were coated with BN and composited using chemically vapor-infiltrated SiC to form single-tow minicomposites. The types of SiC fiber included Nicalon(sup TM), Hi-Nicalon(sup TM), and the new Sylramic(sup TM) polycrystalline SiC fiber. The interfacial shear stresses were determined from unload-reload tensile hysteresis-loop tests. The ultimate stress and strain properties also were determined for the minicomposites. The ultimate strengths of the newer Hi-Nicalon and Sylramic fibers were superior to that of Nicalon minicomposites with similar fiber volume fractions. The Sylramic minicomposites had the lowest strain to failure and highest interfacial shear strength, respectively, because of the high modulus of the fiber and the rough surface of this fiber type. The apparent interfacial shear strength increased as the stress increased for the Sylramic minicomposites, which also was attributed to the surface roughness of this fiber.

  13. Diesel Exhaust After-Treatment by Silicon Carbide Fiber Filter

    Directory of Open Access Journals (Sweden)

    Kazuhiro Yamamoto

    2014-04-01

    Full Text Available To reduce particulate matter (PM in diesel exhaust gas, a diesel particulate filter (DPF has been developed. The thermal durability of existing platinum catalyst-supported DPFs is inadequate. We are focusing on a non-catalytic after-treatment of silicon carbide (SiC fibers with highly thermal durability. In this study, we simulated the processes of soot deposition and oxidation. Results show that even in exhaust gas without soot, a complex flow pattern is observed. The porosity of the filter is not constant along the flow direction, and the pressure gradient varies. The friction factor is slightly larger than the predicted value by the empirical equation in uniform porous media flow. Since the soot deposition occurs inside the filter, the depth filtration by SiC fibers was confirmed. In addition, the effects of filter temperature and oxygen concentration are clearly revealed. That is, comparing the oxidation at 700 °C, the deposited soot amount at 1200 and 1400 °C is decreased by 60% and 92%, respectively. Raising the oxygen concentration from 10% to 20% increases the oxidation efficiency from 42% to 64%. Although more work is needed over a wide range of operating conditions, a combination of these two parameters is important to achieve the non-catalytic exhaust after-treatment.

  14. Methods for Producing High-Performance Silicon Carbide Fibers, Architectural Preforms, and High-Temperature Composite Structures

    Science.gov (United States)

    DiCarlo, James A. (Inventor); Yun, Hee-Mann (Inventor)

    2014-01-01

    Methods are disclosed for producing architectural preforms and high-temperature composite structures containing high-strength ceramic fibers with reduced preforming stresses within each fiber, with an in-situ grown coating on each fiber surface, with reduced boron within the bulk of each fiber, and with improved tensile creep and rupture resistance properties tier each fiber. The methods include the steps of preparing an original sample of a preform formed from a pre-selected high-strength silicon carbide ceramic fiber type, placing the original sample in a processing furnace under a pre-selected preforming stress state and thermally treating the sample in the processing furnace at a pre-selected processing temperature and hold time in a processing gas having a pre-selected composition, pressure, and flow rate. For the high-temperature composite structures, the method includes additional steps of depositing a thin interphase coating on the surface of each fiber and forming a ceramic or carbon-based matrix within the sample.

  15. MUTUAL SOLUBILITY ОF CARBIDES WITHIN MULTICOMPONENT DIFFUSIVE COATINGS ОN HARD ALLOYS

    Directory of Open Access Journals (Sweden)

    A. A. Shmatov

    2008-01-01

    Full Text Available An optimization of powder mixtures has been performed with respect to wear resistance of  diffusive carbide coatings on hard alloy Т15К6 (79% WC, 15% TiC and 6% Co for four three-component systems, viz. Cr–Ti–V, Cr–V–Mo, Cr–Ti–Mo and Cr–V–Nb,. The «composition-properties» diagrams have been plotted using the obtained mathematical models. Optimum three-component diffusive saturation of a hard alloy using carbide-forming elements permits to increase its service life by the factor of 2.2–3.1 as compared with one-component saturation. This significant improvement of wear resistance of three-component diffusive carbide coatings is due to formation of heterogeneous microstructure containing complex alloyed carbides of IV-VI-group metals with 2–30% mutually soluble one- or two- saturating elements. 

  16. Preparation of tantalum carbide films by reaction of electrolytic carbon coating with the tantalum substrate

    OpenAIRE

    Massot, Laurent; Chamelot, Pierre; Taxil, Pierre

    2006-01-01

    This article demonstrates that coatings of tantalum carbide can be obtained by electrodeposition of carbon in molten fluorides on a tantalum substrate as an alternative to the CVD process. The structural characteristics of the carbon deposited by the electrolytic route lead to a high reactivity of this element towards a tantalum cathode to produce tantalum carbide. Mutual reactivity was shown to be enhanced if tantalum plate is replaced by an electrodeposited layer of tantalum, where th...

  17. Prior Surface Integrity Assessment of Coated and Uncoated Carbide Inserts Using Atomic Force Microscopy

    OpenAIRE

    Abdulla Almazrouee; Ayman Alaskari; Samy Oraby

    2011-01-01

    Coated carbide inserts are considered vital components in machining processes and advanced functional surface integrity of inserts and their coating are decisive factors for tool life. Atomic Force Microscopy (AFM) implementation has gained acceptance over a wide spectrum of research and science applications. When used in a proper systematic manner, the AFM features can be a valuable tool for assessment of tool surface integrity. The aim of this paper is to assess the integrity of coated and ...

  18. Wear and corrosion behaviour of tungsten carbide based coatings with different metallic binder

    Science.gov (United States)

    Kamdi, Z.; Apandi, M. N. M.; Ibrahim, M. D.

    2017-12-01

    Tungsten carbide based coating has been well known as wear and corrosion resistance materials. However, less study is done on comparing the coating with different binder. Thus, in this work the wear and corrosion behaviour of high velocity oxy-fuel (HVOF) coatings, namely (i) tungsten carbide cobalt and (ii) tungsten carbide nickel will be evaluated. Both coatings were characterised using X-ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). The wear behaviour has been examined using the modified grinder machine by weight loss measurement. Two types of abrasive have been used that include 3 g by weight alumina and silica. While for the corrosion behaviour, it is monitored by three electrodes of electrochemical test and immersion test for 30 days in an acidic environment. The electrolyte used was 0.5 M sulphuric acids (H2SO4). It was found that the cobalt binder shows higher wear resistance compares to the nickel binder for both slurry types. The harder alumina compared to silica results in higher wear rate with removal of carbide and binder is about the same rate. For silica abrasive, due to slightly lower hardness compared to the carbide, the wear is dominated by binder removal followed by carbide detachment. For corrosion, the nickel binder shows four times higher wear resistance compared to the cobalt binder as expected due to its natural behaviour. These finding demonstrate that the selection of coating to be used in different application in this case, wear and corrosion shall be chosen carefully to maximize the usage of the coating.

  19. Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor

    Science.gov (United States)

    Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

    2001-01-01

    A process for producing polycrystalline silicon carbide by heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

  20. Investigations on Wear Mechanisms of PVD Coatings on Carbides and Sialons

    Directory of Open Access Journals (Sweden)

    Staszuk M.

    2017-12-01

    Full Text Available The paper presents the results on the wear resistance of PVD coatings on cutting inserts made from sintered carbide and sialon ceramics. The exploitative properties of coatings in technological cutting trials were defined in the paper, which also examined the adhesion of coatings to the substrate, the thickness of the coating, and the microhardness. As a result, it was found that isomorphic coating with AlN-h phase of covalent interatomic bonds exhibits much better adhesion to the sialon substrate than isomorphic coating with titanium nitride TiN. These coatings assure the high wear resistance of the coated tools, and the high adhesion combined with the high microhardness and fine-grained structure assure an increase in the exploitative life of the coated tools. In the case of coatings on substrate made from sintered carbide, there was a significant influence on the properties of the tools coated with them as concerns the existence of the diffusion zone between the substrate and the coating.

  1. Low Cost Fabrication of Silicon Carbide Based Ceramics and Fiber Reinforced Composites

    Science.gov (United States)

    Singh, M.; Levine, S. R.

    1995-01-01

    A low cost processing technique called reaction forming for the fabrication of near-net and complex shaped components of silicon carbide based ceramics and composites is presented. This process consists of the production of a microporous carbon preform and subsequent infiltration with liquid silicon or silicon-refractory metal alloys. The microporous preforms are made by the pyrolysis of a polymerized resin mixture with very good control of pore volume and pore size thereby yielding materials with tailorable microstructure and composition. Mechanical properties (elastic modulus, flexural strength, and fracture toughness) of reaction-formed silicon carbide ceramics are presented. This processing approach is suitable for various kinds of reinforcements such as whiskers, particulates, fibers (tows, weaves, and filaments), and 3-D architectures. This approach has also been used to fabricate continuous silicon carbide fiber reinforced ceramic composites (CFCC's) with silicon carbide based matrices. Strong and tough composites with tailorable matrix microstructure and composition have been obtained. Microstructure and thermomechanical properties of a silicon carbide (SCS-6) fiber reinforced reaction-formed silicon carbide matrix composites are discussed.

  2. Microstructural, Chemical and Mechanical Characterization of Polymer-Derived Hi-Nicalon Fibers with Surface Coatings

    Science.gov (United States)

    Bansal, Narottam P.; Chen, Yuan L.

    1998-01-01

    Room temperature tensile strengths of as-received Hi-Nicalon fibers and those having BN/SiC, p-BN/SiC, and p-B(Si)N/SiC surface coatings, deposited by chemical vapor deposition, were measured using an average fiber diameter of 13.5 microns. The Weibull statistical parameters were determined for each fiber. The average tensile strength of uncoated Hi-Nicalon on was 3.19 +/- 0.73 GPa with a Weibull modulus of 5.41. Strength of fibers coated with BN/SiC did not change. However, coat with p-BN/SiC and p-B(Si)N/SiC surface layers showed strength loss of approx. 10 and 35 percent, respectively, compared with as-received fibers. The elemental compositions of the fibers and the coatings were analyzed using scanning Auger microprobe and energy dispersive x-ray spectroscopy. The BN coating was contaminated with a large concentration of carbon and some oxygen. In contrast, p-BN, p-B(Si)N, and SiC coatings did not show any contamination. Microstructural analyses of the fibers and the coatings were done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction. Hi-Nicalon fiber consists of the P-SIC nanocrystals ranging in size from 1 to 30 nm embedded in an amorphous matrix. TEM analysis of the BN coating revealed four distinct layers with turbostatic structure. The p-BN layer was turbostratic and showed considerable preferred orientation. The p-B(Si)N was glassy and the silicon and boron were uniformly distributed. The silicon carbide coating was polycrystalline with a columnar structure along the growth direction. The p-B(Si)N/SiC coatings were more uniform, less defective and of better quality than the BN/SiC or the p-BN/SiC coatings.

  3. Prior Surface Integrity Assessment of Coated and Uncoated Carbide Inserts Using Atomic Force Microscopy

    Directory of Open Access Journals (Sweden)

    Abdulla Almazrouee

    2011-04-01

    Full Text Available Coated carbide inserts are considered vital components in machining processes and advanced functional surface integrity of inserts and their coating are decisive factors for tool life. Atomic Force Microscopy (AFM implementation has gained acceptance over a wide spectrum of research and science applications. When used in a proper systematic manner, the AFM features can be a valuable tool for assessment of tool surface integrity. The aim of this paper is to assess the integrity of coated and uncoated carbide inserts using AFM analytical parameters. Surface morphology of as-received coated and uncoated carbide inserts is examined, analyzed, and characterized through the determination of the appropriate scanning setting, the suitable data type imaging techniques and the most representative data analysis parameters using the MultiMode AFM microscope in contact mode. The results indicate that it is preferable to start with a wider scan size in order to get more accurate interpretation of surface topography. Results are found credible to support the idea that AFM can be used efficiently in detecting flaws and defects of coated and uncoated carbide inserts using specific features such as “Roughness” and “Section” parameters. A recommended strategy is provided for surface examination procedures of cutting inserts using various AFM controlling parameters.

  4. Prior Surface Integrity Assessment of Coated and Uncoated Carbide Inserts Using Atomic Force Microscopy.

    Science.gov (United States)

    Oraby, Samy; Alaskari, Ayman; Almazrouee, Abdulla

    2011-04-06

    Coated carbide inserts are considered vital components in machining processes and advanced functional surface integrity of inserts and their coating are decisive factors for tool life. Atomic Force Microscopy (AFM) implementation has gained acceptance over a wide spectrum of research and science applications. When used in a proper systematic manner, the AFM features can be a valuable tool for assessment of tool surface integrity. The aim of this paper is to assess the integrity of coated and uncoated carbide inserts using AFM analytical parameters. Surface morphology of as-received coated and uncoated carbide inserts is examined, analyzed, and characterized through the determination of the appropriate scanning setting, the suitable data type imaging techniques and the most representative data analysis parameters using the MultiMode AFM microscope in contact mode. The results indicate that it is preferable to start with a wider scan size in order to get more accurate interpretation of surface topography. Results are found credible to support the idea that AFM can be used efficiently in detecting flaws and defects of coated and uncoated carbide inserts using specific features such as "Roughness" and "Section" parameters. A recommended strategy is provided for surface examination procedures of cutting inserts using various AFM controlling parameters.

  5. Method of accurate thickness measurement of boron carbide coating on copper foil

    Energy Technology Data Exchange (ETDEWEB)

    Lacy, Jeffrey L.; Regmi, Murari

    2017-11-07

    A method is disclosed of measuring the thickness of a thin coating on a substrate comprising dissolving the coating and substrate in a reagent and using the post-dissolution concentration of the coating in the reagent to calculate an effective thickness of the coating. The preferred method includes measuring non-conducting films on flexible and rough substrates, but other kinds of thin films can be measure by matching a reliable film-substrate dissolution technique. One preferred method includes determining the thickness of Boron Carbide films deposited on copper foil. The preferred method uses a standard technique known as inductively coupled plasma optical emission spectroscopy (ICPOES) to measure boron concentration in a liquid sample prepared by dissolving boron carbide films and the Copper substrates, preferably using a chemical etch known as ceric ammonium nitrate (CAN). Measured boron concentration values can then be calculated.

  6. Adhesion of CVD coatings on new cemeted carbides

    OpenAIRE

    Bojestig, Eric

    2016-01-01

    Steel turning inserts cemented carbides have a binder phase consisting of cobalt (Co). However, in recent years a study from the United States National Toxicity Program (NTP) found that cobalt powder is carcinogenic upon inhalation. The European Union's REACH have therefore also classified cobalt powder as carcinogenic upon inhalation. The worldwide search to find a replacement has therefore lately intensified. It is important that the alternative binder phase has no negative effects on the p...

  7. Demonstration of nitric oxide on asbestos and silicon carbide fibers with a new ultraviolet spectrophotometric assay.

    Science.gov (United States)

    Leanderson, P; Lagesson, V; Tagesson, C

    1997-09-01

    Nitric oxide (NO) has a number of important functions in biological systems and may play a role in the toxicity of mineral fibers. We investigated whether NO might be present on the surface of mineral fibers and if crocidolite could adsorb NO from NO gas or cigarette smoke. NO was determined with a new gas chromatography-ultraviolet spectrophotometric technique after thermal desorption from the fiber surface and injection in a gas flow cell. NO was found in different amounts on chrysotile B, crocidolite, amosite, and silicon carbide whiskers. There was a strong correlation between the amount of NO and the specific surface area of these fibers (r = 0.98). NO could not be demonstrated on rockwool fibers [man-made vitreous fiber(s) (MMVF)21 and MMVF22] or silicon nitride whiskers. NO on crocidolite, amosite, and silicon carbide whiskers was readily desorbed from the fibers at increased temperature, while NO on chrysotile B seemed to be more firmly adsorbed to the fiber and required a longer period of time to be desorbed. The amount of NO bound to crocidolite increased from 34 micrograms/g fiber to 85 and 474 micrograms/g after exposing the fibers to cigarette smoke and NO gas, respectively. These findings indicate that a) NO adsorbs to fiber surfaces, b) some fibers adsorb more NO than others, c) some fibers adsorb NO more strongly than others, and d) the amounts of NO on fibers may be increased after exposure of the fiber to cigarette smoke or other sources of NO. The biological significance of NO on mineral fibers remains to be investigated.

  8. Demonstration of nitric oxide on asbestos and silicon carbide fibers with a new ultraviolet spectrophotometric assay.

    Science.gov (United States)

    Leanderson, P; Lagesson, V; Tagesson, C

    1997-01-01

    Nitric oxide (NO) has a number of important functions in biological systems and may play a role in the toxicity of mineral fibers. We investigated whether NO might be present on the surface of mineral fibers and if crocidolite could adsorb NO from NO gas or cigarette smoke. NO was determined with a new gas chromatography-ultraviolet spectrophotometric technique after thermal desorption from the fiber surface and injection in a gas flow cell. NO was found in different amounts on chrysotile B, crocidolite, amosite, and silicon carbide whiskers. There was a strong correlation between the amount of NO and the specific surface area of these fibers (r = 0.98). NO could not be demonstrated on rockwool fibers [man-made vitreous fiber(s) (MMVF)21 and MMVF22] or silicon nitride whiskers. NO on crocidolite, amosite, and silicon carbide whiskers was readily desorbed from the fibers at increased temperature, while NO on chrysotile B seemed to be more firmly adsorbed to the fiber and required a longer period of time to be desorbed. The amount of NO bound to crocidolite increased from 34 micrograms/g fiber to 85 and 474 micrograms/g after exposing the fibers to cigarette smoke and NO gas, respectively. These findings indicate that a) NO adsorbs to fiber surfaces, b) some fibers adsorb more NO than others, c) some fibers adsorb NO more strongly than others, and d) the amounts of NO on fibers may be increased after exposure of the fiber to cigarette smoke or other sources of NO. The biological significance of NO on mineral fibers remains to be investigated. Images Figure 3. PMID:9400696

  9. Characterization on C/SiC Ceramic Matrix Composites with Novel Fiber Coatings

    Science.gov (United States)

    Petko, Jeanne; Kiser, J. Douglas; McCue, Terry; Verrilli, Michael

    2002-01-01

    Ceramic Matrix Composites (CMCs) are attractive candidate materials in the aerospace industry due to their high specific strength, low density and higher temperature capabilities. The National Aeronautics and Space Administration (NASA) is pursuing the use of CMC components in advanced Reusable Launch Vehicle (RLV) propulsion applications. Carbon fiber-reinforced silicon carbide (C/SiC) is the primary material of interest for a variety of RLV propulsion applications. These composites offer high- strength carbon fibers and a high modulus, oxidation-resistant matrix. For comparison, two types of carbon fibers were processed with novel types of interface coatings (multilayer and pseudoporous). For RLV propulsion applications, environmental durability will be critical. The coatings show promise of protecting the carbon fibers from the oxidizing environment. The strengths and microstructures of these composite materials are presented.

  10. The effect of neutron irradiation on silicon carbide fibers

    Energy Technology Data Exchange (ETDEWEB)

    Newsome, G.A. [Lockheed Martin Corp., Schenectady, NY (United States)

    1997-01-01

    Nine types of SiC fiber have been exposed to neutron radiation in the Advanced Test Reactor at 250 C for various lengths of time ranging from 83 to 128 days. The effects of these exposures have been initially determined using scanning electron microscopy. The fibers tested were Nicalon{trademark} CG, Tyranno, Hi-Nicalon{trademark}, Dow Corning SiC, Carborundum SiC, Textron SCS-6, polymethysilane (PMS) derived SiC from the University of Michigan, and two types of MER SiC fiber. This covers a range of fibers from widely used commercial fibers to developmental fibers. Consistent with previous radiation experiments, Nicalon fiber was severely degraded by the neutron irradiation. Similarly, Tyranno suffered severe degradation. The more advanced fibers which approach the composition and properties of SiC performed well under irradiation. Of these, the Carborundum SiC fiber appeared to perform the best. The Hi-Nicalon and Dow Corning Fibers exhibited good general stability, but also appear to have some surface roughening. The MER fibers and the Textron SCS-6 fibers both had carbon cores which adversely influenced the overall stability of the fibers.

  11. Composition optimization of self-lubricating chromium carbide-based composite coatings for use to 760 deg C

    Science.gov (United States)

    Dellacorte, C.; Sliney, H. E.

    1986-01-01

    This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a ternary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760 C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.

  12. Composition optimization of self-lubricating chromium-carbide-based composite coatings for use to 760 C

    Science.gov (United States)

    Dellacorte, Chris; Sliney, Harold E.

    1987-01-01

    This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a ternary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760 C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.

  13. HVOF and HVAF Coatings of Agglomerated Tungsten Carbide-Cobalt Powders for Water Droplet Erosion Application

    Science.gov (United States)

    Tarasi, F.; Mahdipoor, M. S.; Dolatabadi, A.; Medraj, M.; Moreau, C.

    2016-12-01

    Water droplet erosion (WDE) is a phenomenon caused by impingement of water droplets of several hundred microns to a few millimeters diameter at velocities of hundreds of meters per second on the edges and surfaces of the parts used in such services. The solution to this problem is sought especially for the moving compressor blades in gas turbines and those operating at the low-pressure end of steam turbines. Thermal-sprayed tungsten carbide-based coatings have been the focus of many studies and are industrially accepted for a multitude of wear and erosion resistance applications. In the present work, the microstructure, phase analysis and mechanical properties (micro-hardness and fracture toughness) of WC-Co coatings are studied in relation with their influence on the WDE resistance of such coatings. The coatings are deposited by high-velocity oxygen fuel (HVOF) and high-velocity air fuel (HVAF) processes. The agglomerated tungsten carbide-cobalt powders were in either sintered or non-sintered conditions. The WDE tests were performed using 0.4 mm water droplets at 300 m/s impact velocity. The study shows promising results for this cermet as WDE-resistant coating when the coating can reach its optimum quality using the right thermal spray process and parameters.

  14. Structure and characteristics of chromium steel coatings alloyed with boron carbide

    Science.gov (United States)

    Eremin, E. N.; Losev, A. S.; Borodikhin, S. A.; Matalasova, A. E.; Ponomarev, I. A.; Ivlev, K. E.

    2018-01-01

    This study explores the problems arising from the increase of wear resistance on the coatings of details of a wide range of applications, obtained by surfacing the Fe - Cr system with flux-cored wires. It has shown that insignificant wear resistance of such steel under conditions of metal friction against another metal is due to their relatively low hardness and the absence of strengthening phases. It also shows the effect of boron carbide on the structure and the characteristics of chromium steel obtained by the surfacing process. It was established that the use of high-chromium flux-cored wires alloyed with boron carbide aids the production of a deposited metal of a composite type, with a dispersed hardening based on chromium carboboride. The deposited metal with such structure has a high wear resistance and the hardness of 55 … 58 HRC and can be used for surfacing cladding the hardening, corrosion-resistant coatings.

  15. Microstructure and tribology behaviors of in-situ WC/Fe carbide coating fabricated by plasma transferred arc metallurgic reaction

    Science.gov (United States)

    Yuan, Youlu; Li, Zhuguo

    2017-11-01

    In order to improve the dry sliding tribology properties of mild steel compound, the in-situ WC carbide coatings with 18, 32, 54 vol% WC were successfully synthesized using plasma transferred arc metallurgic reaction (PTAMR) with alloy powders W, C and Fe-30Ni. The composition, microstructure and microhardness of the carbide coatings were characterized. It was found that the carbide coating consisted of WC, M6C and γ phases, carbides distribute gradually from the coating bottom to top, the in-situ WC crystal grows into triangle prism structure with high hardness and good toughness. Dry sliding tribology behaviors were studied on block-on-wheel dry sliding wear tester with load 300 N, sliding speed 0.836 m/s and distance 500 m. Results show that the friction coefficient diagrams contain three stages, variation of friction coefficient increase with the content of WC, friction temperature increase with the sliding distance, increasing the content of WC can directly increase the antiwear property of WC/Fe carbide coating. The main wear mechanisms of in-situ WC/Fe carbide coating are adhesive, oxidation, micro-cutting and ploughing wear.

  16. Mullite coatings for corrosion protection of silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Mulpuri, R.; Sarin, V.K. [Boston Univ., MA (United States)

    1995-08-01

    SiC based ceramics have been identified as the leading candidate materials for elevated temperature applications in harsh oxidation/corrosion environments. It has been established that a protective coating can be effectively used to avoid problems with excessive oxidation and hot corrosion. However, to date, no coating configuration has been developed that can satisfy the stringent requirements imposed by such applications. Chemical Vapor Deposited (CVD) mullite coatings due to their desirable properties of toughness, corrosion resistance, and a good coefficient of thermal expansion match with SiC are being investigated as a potential candidate. Since mullite has never been successfully grown via CVD, the thermodynamics and kinetics of its formation were initially established and used as a guideline in determining the initial process conditions. Process optimization was carried out using an iterative process of theoretical analysis and experimental work coupled with characterization and testing. The results of theoretical analysis and the CVD formation characteristics of mullite are presented.

  17. Interactions between the glass fiber coating and oxidized carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ku-Herrera, J.J., E-mail: jesuskuh@live.com.mx [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburná de Hidalgo. C.P., 97200 Mérida, Yucatán (Mexico); Avilés, F., E-mail: faviles@cicy.mx [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburná de Hidalgo. C.P., 97200 Mérida, Yucatán (Mexico); Nistal, A. [Instituto de Cerámica y Vidrio (ICV-CSIC), Kelsen 5, 28049 Madrid (Spain); Cauich-Rodríguez, J.V. [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburná de Hidalgo. C.P., 97200 Mérida, Yucatán (Mexico); Rubio, F.; Rubio, J. [Instituto de Cerámica y Vidrio (ICV-CSIC), Kelsen 5, 28049 Madrid (Spain); Bartolo-Pérez, P. [Departamento de Física Aplicada, Cinvestav, Unidad Mérida, C.P., 97310 Mérida, Yucatán (Mexico)

    2015-03-01

    Graphical abstract: - Highlights: • Oxidized multiwall carbon nanotubes (MWCNTs) were deposited onto E-glass fibers. • The role of the fiber coating on the deposition of MWCNTs on the fibers is studied. • A rather homogeneous deposition of MWCNTs is achieved if the coating is maintained. • Multiple oxygen-containing groups were found in the analysis of the fiber coating. • Evidence of chemical interaction between MWCNTs and the fiber coating was found. - Abstract: Chemically oxidized multiwall carbon nanotubes (MWCNTs) were deposited onto commercial E-glass fibers using a dipping procedure assisted by ultrasonic dispersion. In order to investigate the role of the fiber coating (known as “sizing”), MWCNTs were deposited on the surface of as-received E-glass fibers preserving the proprietary coating as well as onto glass fibers which had the coating deliberately removed. Scanning electron microscopy and Raman spectroscopy were used to assess the distribution of MWCNTs onto the fibers. A rather homogeneous coverage with high density of MWCNTs onto the glass fibers is achieved when the fiber coating is maintained. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) analyses of the chemical composition of the glass fiber coating suggest that such coating is a complex mixture with multiple oxygen-containing functional groups such as hydroxyl, carbonyl and epoxy. FTIR and XPS of MWCNTs over the glass fibers and of a mixture of MWCNTs and fiber coating provided evidence that the hydroxyl and carboxyl groups of the oxidized MWCNTs react with the oxygen-containing functional groups of the glass fiber coating, forming hydrogen bonding and through epoxy ring opening. Hydrogen bonding and ester formation between the functional groups of the MWCNTs and the silane contained in the coating are also possible.

  18. Carbon nanotube and graphene nanoribbon-coated conductive Kevlar fibers.

    Science.gov (United States)

    Xiang, Changsheng; Lu, Wei; Zhu, Yu; Sun, Zhengzong; Yan, Zheng; Hwang, Chi-Chau; Tour, James M

    2012-01-01

    Conductive carbon material-coated Kevlar fibers were fabricated through layer-by-layer spray coating. Polyurethane was used as the interlayer between the Kevlar fiber and carbon materials to bind the carbon materials to the Kevlar fiber. Strongly adhering single-walled carbon nanotube coatings yielded a durable conductivity of 65 S/cm without significant mechanical degradation. In addition, the properties remained stable after bending or water washing cycles. The coated fibers were analyzed using scanning electron microcopy and a knot test. The as-produced fiber had a knot efficiency of 23%, which is more than four times higher than that of carbon fibers. The spray-coating of graphene nanoribbons onto Kevlar fibers was also investigated. These flexible coated-Kevlar fibers have the potential to be used for conductive wires in wearable electronics and battery-heated armors. © 2011 American Chemical Society

  19. Field assisted sintering of refractory carbide ceramics and fiber reinforced ceramic matrix composites

    Science.gov (United States)

    Gephart, Sean

    The sintering behaviors of silicon carbide (SiC) and boron carbide (B4C) based materials were investigated using an emerging sintering technology known as field assisted sintering technology (FAST), also known as spark plasma sintering (SPS) and pulse electric current sintering (PECS). Sintering by FAST utilizes high density electric current, uniaxial pressure, and relatively high heating rate compared to conventional sintering techniques. This effort investigated issues of scaling from laboratory FAST system (25 ton capacity) to industrial FAST system (250 ton capacity), as well as exploring the difference in sintering behavior of single phase B4C and SiC using FAST and conventional sintering techniques including hot-pressing (HP) and pressure-less sintering (PL). Materials were analyzed for mechanical and bulk properties, including characterization of density, hardness, fracture toughness, fracture (bend) strength, elastic modulus and microstructure. A parallel investigation was conducted in the development of ceramic matrix composites (CMC) using SiC powder impregnation of fiber compacts followed by FAST sintering. The FAST technique was used to sinter several B4C and SiC materials to near theoretical density. Preliminary efforts established optimized sintering temperatures using the smaller 25 ton laboratory unit, targeting a sample size of 40 mm diameter and 8 mm thickness. Then the same B4C and SiC materials were sintered by the larger 250 ton industrial FAST system, a HP system, and PL sintering system with a targeted dense material geometry of 4 x 4 x 0.315 inches3 (101.6 x 101.6 x 8 mm3). The resulting samples were studied to determine if the sintering dynamics and/or the resulting material properties were influenced by the sintering technique employed. This study determined that FAST sintered ceramic materials resulted in consistently higher averaged values for mechanical properties as well as smaller grain size when compared to conventionally sintered

  20. Mechanical Behavior and Sliding Wear Studies on Iron Aluminide Coatings Reinforced with Titanium Carbide

    Directory of Open Access Journals (Sweden)

    Mahdi Amiriyan

    2017-05-01

    Full Text Available Wear-resistant iron aluminide-based composites were coated on steel substrates with the High-Velocity Oxy-Fuel (HVOF technique using ball milled Fe3Al and TiC powders as feedstock. The phase composition, microstructure, microhardness, elastic modulus and dry sliding wear performance of unreinforced Fe3Al and Fe3Al–TiC composite coatings (reinforced with 30 and 50 vol. % TiC particles were evaluated in order to reveal the relationship between the mechanical and tribological behaviors. Compared to the unreinforced coatings, the composite coating with 30 vol. % TiC particles exhibited much greater hardness and higher elastic modulus. The increase of the elastic modulus of the composite coatings did not result in deterioration of sliding wear behavior. The addition of 50 vol. % TiC resulted in a further increase in hardness, however, both composite coatings showed the same elastic modulus. The fractured cross sectional surface of the unreinforced coating showed a weakly bonded microstructure promoting delamination in wear tests, whereas the composite fractured surface showed strong mechanical bonding between the matrix and carbide particles, leading to better cohesion. The Fe3Al–TiC coatings showed almost three orders of magnitude higher wear resistance under the dry sliding wear test compared to the unreinforced coatings.

  1. High-temperature sapphire optical sensor fiber coatings

    Science.gov (United States)

    Desu, Seshu B.; Claus, Richard O.; Raheem, Ruby; Murphy, Kent A.

    1990-10-01

    Advanced coal-fired power generation systems, such as pressurized fluidized-bed combustors and integrated gasifier-combined cycles, may provide cost effective future alternatives for power generation, improve our utilization of coal resources, and decrease our dependence upon oil and gas. When coal is burned or converted to combustible gas to produce energy, mineral matter and chemical compounds are released as solid and gaseous contaminants. The control of contaminants is mandatory to prevent pollution as well as degradation of equipment in advanced power generation. To eliminate the need for expensive heat recovery equipment and to avoid efficiency losses it is desirable to develop a technology capable of cleaning the hot gas. For this technology the removal of particle contaminants is of major concern. Several prototype high temperature particle filters have been developed, including ceramic candle filters, ceramic bag filters, and ceramic cross-flow (CXF) filters. Ceramic candle filters are rigid, tubular filters typically made by bonding silicon carbide or alumina-silica grains with clay bonding materials and perhaps including alumina-silica fibers. Ceramic bag filters are flexible and are made from long ceramic fibers such as alumina-silica. CXF filters are rigid filters made of stacks of individual lamina through which the dirty and clean gases flow in cross-wise directions. CXF filters are advantageous for hot gas cleanup applications since they offer a large effective filter surface per unit volume. The relatively small size of the filters allows the pressurized vessel containing them to be small, thus reducing potential equipment costs. CXF filters have shown promise but have experienced degradation at normal operational high temperatures (close to 1173K) and high pressures (up to 24 bars). Observed degradation modes include delamination of the individual tile layers, cracking at either the tile-torid interface or at the mounting flange, or plugging of

  2. Neutron irradiation effects on high Nicalon silicon carbide fibers

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, M.C.; Steiner, D.; Snead, L.L. [Oak Ridge National Laboratory, TN (United States)

    1996-10-01

    The effects of neutron irradiation on the mechanical properties and microstructure of SiC and SiC-based fibers is a current focal point for the development of radiation damage resistant SiC/SiC composites. This report discusses the radiation effects on the Nippon Carbon Hi-Nicalon{trademark} fiber system and also discusses an erratum on earlier results published by the authors on this material. The radiation matrix currently under study is also summarized.

  3. Preceramic Polymers for Use as Fiber Coatings

    Science.gov (United States)

    Heimann, P. J.; Hurwitz, F. I.; Wheeler, D.; Eldridge, J.; Baranwal, R.; Dickerson, R.

    1996-01-01

    Polymeric precursors to Si-C-O, SI-B-N and Si-C were evaluated for use as ceramic interfaces in ceramic matrix composites. Use of the preceramic polymers allows for easy dip coating of fibers from dilute solutions of a polymer, which are then pyrolyzed to obtain the ceramic. SCS-0 fibers (Textron Specialty Materials, Lowell, MA) were coated with polymers from three systems: polysilsesquioxanes, polyborosilazanes and polycarbosilanes. The polysilsesquioxane systems were shown to produce either silicon oxycarbide or silicon oxynitride, depending on the pyrolysis conditions, and demonstrated some promise in an RBSN (reaction-bonded silicon nitride) matrix model system. Polyborosilazanes were shown, in studies of bulk polymers, to give rise to oxidation resistant Si-B-N ceramics which remain amorphous to temperatures of 1600 C, and should therefore provide a low modulus interface. Polycarbosilanes produce amorphous carbon-rich Si-C materials which have demonstrated oxidation resistance.

  4. Binder for Carbon-Fiber Coating

    Science.gov (United States)

    Dowler, W. L.; Ramohalli, K. N.; Yen, S. P. S.; Mueller, W. A.; Harper, J.

    1984-01-01

    Insoluble, even coating formed by soaking in polyacrylic acid. Carbon fiber material prepared by soaking in solution of 20 percent polyacrylic acid in water. Material blotted and dried at 120 degrees C for at least 2 hours. Dried material reacted with boiling aqueous solution of calcium acetate. Treated material removed from boiling solution, blotted, dried at 120 degrees C, washed with distilled water, and dried again.

  5. Simulation and experimental study of CVD process for low temperature nanocrystalline silicon carbide coating

    Energy Technology Data Exchange (ETDEWEB)

    Kaushal, Amit; Prakash, Jyoti, E-mail: jprakash@barc.gov.in; Dasgupta, Kinshuk; Chakravartty, Jayanta K.

    2016-07-15

    Highlights: • Parametric simulation was carried out for specially designed CVD reactor. • Effect of fluid velocity, heat flow and concentration were studied in CVD reactor. • Coating study carried out using low temperature and environmental safe CVD process. • Dense and uniform nanocrystalline SiC film was coated on zircaloy substrate. - Abstract: There is a huge requirement for development of a coating technique in nuclear industry, which is environmentally safe, economical and applicable to large scale components. In this view, simulation of gas-phase behavior in specially designed CVD reactor was carried out using computational tool, COMSOL. There were two important zones in CVD reactor first one is precursor vaporization zone and second one is coating zone. Optimized parameters for coating were derived from the simulation of gas phase dynamics in both zone of CVD reactor. The overall effect of fluid velocity, heat flow and concentration profile showed that Re = 54 is the optimum reaction condition for uniform coating in CVD system. In CVD coating experiments a synthesized halogen free, non-toxic and non-corrosive silicon carbide precursor was used. Uniform coating of SiC was obtained on zircaloy substrate at 900 °C using as synthesized organosilicon precursor. The X-ray diffraction and scanning electron microscopy analysis show that dense nano crystalline SiC film was deposited on zircaloy substrate.

  6. High-speed deposition of titanium carbide coatings by laser-assisted metal–organic CVD

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yansheng [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Tu, Rong, E-mail: turong@whut.edu.cn [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Goto, Takashi [Institute for Materials Research, Tohoku University, Aoba-ku, 2-1-1 Katahira, Sendai 980-8577 (Japan)

    2013-08-01

    Graphical abstract: - Highlights: • A semiconductor laser was first used to prepare wide-area LCVD-TiC{sub x} coatings. • The effect of laser power for the deposition of TiC{sub x} coatings was discussed. • TiC{sub x} coatings showed a columnar cross section and a dense surface texture. • TiC{sub x} coatings had a 1–4 order lower laser density than those of previous reports. • This study gives the possibility of LCVD applying on the preparation of TiC{sub x} coating. - Abstract: A semiconductor laser-assisted chemical vapor deposition (LCVD) of titanium carbide (TiC{sub x}) coatings on Al{sub 2}O{sub 3} substrate using tetrakis (diethylamido) titanium (TDEAT) and C{sub 2}H{sub 2} as source materials were investigated. The influences of laser power (P{sub L}) and pre-heating temperature (T{sub pre}) on the microstructure and deposition rate of TiC{sub x} coatings were examined. Single phase of TiC{sub x} coatings were obtained at P{sub L} = 100–200 W. TiC{sub x} coatings had a cauliflower-like surface and columnar cross section. TiC{sub x} coatings in the present study had the highest R{sub dep} (54 μm/h) at a relative low T{sub dep} than those of conventional CVD-TiC{sub x} coatings. The highest volume deposition rate (V{sub dep}) of TiC{sub x} coatings was about 4.7 × 10{sup −12} m{sup 3} s{sup −1}, which had 3–10{sup 5} times larger deposition area and 1–4 order lower laser density than those of previous LCVD using CO{sub 2}, Nd:YAG and argon ion laser.

  7. Recent Advances in the Deposition of Diamond Coatings on Co-Cemented Tungsten Carbides

    Directory of Open Access Journals (Sweden)

    R. Polini

    2012-01-01

    Full Text Available Co-cemented tungsten carbides, namely, hard metals are largely used to manufacture high wear resistant components in several manufacturing segments. Coating hard metals with superhard materials like diamond is of utmost interest as it can further extend their useful lifespan. The deposition of diamond coatings onto WC-Co can be extremely complicated as a result of poor adhesion. This can be essentially ascribed to (i the mismatch in thermal expansion coefficients between diamond and WC-Co, at the typical high temperatures inside the chemical vapour deposition (CVD chamber, generates large residual stresses at the interface; (ii the role of surface Co inside the WC-Co matrix during diamond CVD, which promotes carbon dissolution and diffusion. The present investigation reviews the techniques by which Co-cemented tungsten carbides can be treated to make them prone to receive diamond coatings by CVD. Further, it proposes interesting ecofriendly and sustainable alternatives to further improve the diamond deposition process as well as the overall performance of the coated hard metals.

  8. X-Ray photoelectron spectroscopy study of radiofrequency-sputtered titanium, carbide, molybdenum carbide, and titanium boride coatings and their friction properties

    Science.gov (United States)

    Brainard, W. A.; Wheeler, D. R.

    1977-01-01

    Radiofrequency sputtered coatings of titanium carbide, molybdenum carbide and titanium boride were tested as wear resistant coatings on stainless steel in a pin on disk apparatus. X-ray photoelectron spectroscopy (XPS) was used to analyze the sputtered films with regard to both bulk and interface composition in order to obtain maximum film performance. Significant improvements in friction behavior were obtained when properly biased films were deposited on deliberately preoxidized substrates. XPS depth profile data showed thick graded interfaces for bias deposited films even when adherence was poor. The addition of 10 percent hydrogen to the sputtering gas produced coatings with thin poorly adherent interfaces. Results suggest that some of the common practices in the field of sputtering may be detrimental to achieving maximum adherence and optimum composition for these refractory compounds.

  9. Surface modification and characterization of aramid fibers with hybrid coating

    Science.gov (United States)

    Chen, Jianrui; Zhu, Yaofeng; Ni, Qingqing; Fu, Yaqin; Fu, Xiang

    2014-12-01

    Aramid fibers were modified through solution dip-coating and interfacial in situ polymerization using a newly synthesized SiO2/shape memory polyurethane (SiO2/SMPU) hybrid. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that the synthesized SiO2/SMPU hybrid successfully coated the fiber surface. The surface morphology of the aramid fibers and the single fiber tensile strength and interfacial shear strength (IFSS) of the composites were determined. The IFSS of the fiber coated with the hybrid improved by 45%, which benefited from a special "pizza-like" structure on the fiber surface.

  10. In Vitro Biocompatibility of Si Alloyed Multi-Principal Element Carbide Coatings.

    Directory of Open Access Journals (Sweden)

    Alina Vladescu

    Full Text Available In the current study, we have examined the possibility to improve the biocompatibility of the (TiZrNbTaHfC through replacement of either Ti or Ta by Si. The coatings were deposited on Si and 316L stainless steel substrates by magnetron sputtering in an Ar+CH4 mixed atmosphere and were examined for elemental composition, chemical bonds, surface topography, surface electrical charge and biocompatible characteristics. The net surface charge was evaluated at nano and macroscopic scale by measuring the electrical potential and work function, respectively. The biocompatible tests comprised determination of cell viability and cell attachment to the coated surface. The deposited coatings had C/(metal+Si ratios close to unity, while a mixture of metallic carbide, free-carbon and oxidized species formed on the film surface. The coatings' surfaces were smooth and no influence of surface roughness on electrical charge or biocompatibility was found. The biocompatible characteristics correlated well with the electrical potential/work function, suggesting a significant role of surface charge in improving biocompatibility, particularly cell attachment to coating's surface. Replacement of either Ti or Ta by Si in the (TiZrNbTaHfC coating led to an enhanced surface electrical charge, as well as to superior biocompatible properties, with best results for the (TiZrNbSiHfC coating.

  11. Chemical vapor deposited fiber coatings and chemical vapor infiltrated ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Kmetz, M.A.

    1992-01-01

    Conventional Chemical Vapor Deposition (CVD) and Organometallic Chemical Vapor Deposition (MOCVD) were employed to deposit a series of interfacial coatings on SiC and carbon yarn. Molybdenum, tungsten and chromium hexacarbonyls were utilized as precursors in a low temperature (350[degrees]C) MOCVD process to coat SiC yarn with Mo, W and Cr oxycarbides. Annealing studies performed on the MoOC and WOC coated SiC yarns in N[sub 2] to 1,000[degrees]C establish that further decomposition of the oxycarbides occurred, culminating in the formation of the metals. These metals were then found to react with Si to form Mo and W disilicide coatings. In the Cr system, heating in N[sub 2] above 800[degrees]C resulted in the formation of a mixture of carbides and oxides. Convention CVD was also employed to coat SiC and carbon yarn with C, Bn and a new interface designated BC (a carbon-boron alloy). The coated tows were then infiltrated with SiC, TiO[sub 2], SiO[sub 2] and B[sub 4]C by a chemical vapor infiltration process. The B-C coatings were found to provide advantageous interfacial properties over carbon and BN coatings in several different composite systems. The effectiveness of these different coatings to act as a chemically inert barrier layer and their relationship to the degree of interfacial debonding on the mechanical properties of the composites were examined. The effects of thermal stability and strength of the coated fibers and composites were also determined for several difference atmospheres. In addition, a new method for determining the tensile strength of the as-received and coated yarns was also developed. The coated fibers and composites were further characterized by AES, SEM, XPS, IR and X-ray diffraction analysis.

  12. Design and simulation of thermal residual stresses of coatings on WC-Co cemented carbide cutting tool substrate

    Energy Technology Data Exchange (ETDEWEB)

    Li, Anhai; Zhao, Jun; Zang, Jian; Zheng, Wei [Key Laboratory of High Efficiency and Clean Mechanical Manufacture of MOE, School of Mechanical EngineeringShandong University, Jinan (China)

    2016-08-15

    Large thermal residual stresses in coatings during the coating deposition process may easily lead to coating delamination of coated carbide tools in machining. In order to reduce the possibility of coating delamination during the tool failure process, a theoretical method was proposed and a numerical method was constructed for the coating design of WC-Co cemented carbide cutting tools. The thermal residual stresses of multi-layered coatings were analytically modeled based on equivalent parameters of coating properties, and the stress distribution of coatings are simulated by Finite element method (FEM). The theoretically calculated results and the FEM simulated results were verified and in good agreement with the experimental test results. The effects of coating thickness, tool substrate, coating type and interlayer were investigated by the proposed geometric and FEM model. Based on the evaluations of matchability of tool substrate and tool coatings, the basic principles of tool coating design were proposed. This provides theoretical basis for the selection and design of coatings of cutting tools in high-speed machining.

  13. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    Science.gov (United States)

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Surface modification and characterization of aramid fibers with hybrid coating

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jianrui; Zhu, Yaofeng; Ni, Qingqing; Fu, Yaqin, E-mail: fyq01@zstu.edu.cn; Fu, Xiang

    2014-12-01

    Graphical abstract: - Highlights: • Aramid fibers modification sizing synthesized by sol–gel in the absence of water. • The strength and interfacial adhesion property of modified fibers were improved. • Modified fibers show a special surface structure. • The mechanism explains the function of structure. - Abstract: Aramid fibers were modified through solution dip-coating and interfacial in situ polymerization using a newly synthesized SiO{sub 2}/shape memory polyurethane (SiO{sub 2}/SMPU) hybrid. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that the synthesized SiO{sub 2}/SMPU hybrid successfully coated the fiber surface. The surface morphology of the aramid fibers and the single fiber tensile strength and interfacial shear strength (IFSS) of the composites were determined. The IFSS of the fiber coated with the hybrid improved by 45%, which benefited from a special “pizza-like” structure on the fiber surface.

  15. Laboratory analysis of dental sections made with commercial tungsten carbide burs coated with HFCVD diamond

    Energy Technology Data Exchange (ETDEWEB)

    Maass, F [Departamento de Fisica, Universidad de Antofagasta, Av. Angamos 601, Antofagasta (Chile); Aguilera, Y [Departamento de Ingenieria Industrial, Universidad de Antofagasta, Av. Angamos 601, Antofagasta (Chile); Avaria, J [Departamento de OdontologIa, Universidad de Antofagasta, Av. Angamos 601, Antofagasta (Chile)], E-mail: fdmaass@uantof.cl

    2008-11-01

    The objective of this study was to determine the cutting power of diamond burs obtained by the HFCVD deposition process. Diamond was deposited on the active part of each of a series of 10 commonly used Tungsten Carbide (WC) commercial burs. The quality of the section was compared with sections made by commonly used commercial burs, employing fresh human molars and a standard device [1]. Both burs and sections were analysed by using SEM and EDX techniques. The quality and tension of the deposited diamond coatings were analyzed by Raman Spectroscopy. The optimal thickness of the diamond coating which provided the best durability and finish of the sections was determined by comparative observations of results.

  16. Near-field radiative heat transfer between metamaterials coated with silicon carbide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Soumyadipta, E-mail: soumya.005@gmail.com; Yang, Yue; Wang, Liping, E-mail: liping.wang@asu.edu [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287 (United States)

    2015-01-19

    In this letter, we study the near-field radiative heat transfer between two metamaterial substrates coated with silicon carbide (SiC) thin films. It is known that metamaterials can enhance the near-field heat transfer over ordinary materials due to excitation of magnetic plasmons associated with s polarization, while strong surface phonon polariton exists for SiC. By careful tuning of the optical properties of metamaterial, it is possible to excite electrical and magnetic resonances for the metamaterial and surface phonon polaritons for SiC at different spectral regions, resulting in the enhanced heat transfer. The effect of the SiC film thickness at different vacuum gaps is investigated. Results obtained from this study will be beneficial for application of thin film coatings for energy harvesting.

  17. Effect of metallic coating on the properties of copper-silicon carbide composites

    Science.gov (United States)

    Chmielewski, M.; Pietrzak, K.; Teodorczyk, M.; Nosewicz, S.; Jarząbek, D.; Zybała, R.; Bazarnik, P.; Lewandowska, M.; Strojny-Nędza, A.

    2017-11-01

    In the presented paper a coating of SiC particles with a metallic layer was used to prepare copper matrix composite materials. The role of the layer was to protect the silicon carbide from decomposition and dissolution of silicon in the copper matrix during the sintering process. The SiC particles were covered by chromium, tungsten and titanium using Plasma Vapour Deposition method. After powder mixing of components, the final densification process via Spark Plasma Sintering (SPS) method at temperature 950 °C was provided. The almost fully dense materials were obtained (>97.5%). The microstructure of obtained composites was studied using scanning electron microscopy as well as transmission electron microscopy. The microstructural analysis of composites confirmed that regardless of the type of deposited material, there is no evidence for decomposition process of silicon carbide in copper. In order to measure the strength of the interface between ceramic particles and the metal matrix, the micro tensile tests have been performed. Furthermore, thermal diffusivity was measured with the use of the laser pulse technique. In the context of performed studies, the tungsten coating seems to be the most promising solution for heat sink application. Compared to pure composites without metallic layer, Cu-SiC with W coating indicate the higher tensile strength and thermal diffusitivy, irrespective of an amount of SiC reinforcement. The improvement of the composite properties is related to advantageous condition of Cu-SiC interface characterized by well homogenity and low porosity, as well as individual properties of the tungsten coating material.

  18. Carbide Coatings for Nickel Alloys, Graphite and Carbon/Carbon Composites to be used in Fluoride Salt Valves

    Energy Technology Data Exchange (ETDEWEB)

    Nagle, Denis [Johns Hopkins Univ., Baltimore, MD (United States); Zhang, Dajie [Johns Hopkins Univ., Baltimore, MD (United States)

    2015-10-22

    The focus of this research was concerned with developing materials technology that supports the evolution of Generation IV Advanced High Temperature Reactor (AHTR) concepts. Specifically, we investigate refractory carbide coatings for 1) nickel alloys, and 2) commercial carbon-carbon composites (CCCs). Numerous compelling reasons have driven us to focus on carbon and carbide materials. First, unlike metals, the strength and modulus of CCCs increase with rising temperature. Secondly, graphite and carbon composites have been proven effective for resisting highly corrosive fluoride melts such as molten cryolite [Na₃AlF₆] at ~1000°C in aluminum reduction cells. Thirdly, graphite and carbide materials exhibit extraordinary radiation damage tolerance and stability up to 2000°C. Finally, carbides are thermodynamically more stable in liquid fluoride salt than the corresponding metals (i.e. Cr and Zr) found in nickel based alloys.

  19. Micromagnetic Simulation of Fibers and Coatings on Textiles

    Science.gov (United States)

    Ehrmann, Andrea; Blachowicz, Tomasz

    2015-10-01

    Simulations of mechanical or comfort properties of fibers, yarns and textile fabrics have been developed for a long time. In the course of increasing interest in smart textiles, models for conductive fabrics have also been developed. The magnetic properties of fibers or magnetic coatings, however, are almost exclusively being examined experimentally. This article thus describes different possibilities of micromagnetically modeling magnetic fibers or coatings. It gives an overview of calculation times for different dimensions of magnetic materials, indicating the limits due to available computer performance and shows the influence of these dimensions on the simulated magnetic properties for magnetic coatings on fibers and fabrics.

  20. Enhancement in Tribological and Mechanical Properties of Cemented Tungsten Carbide Substrates using CVD-diamond Coatings

    Directory of Open Access Journals (Sweden)

    K.A. Najar

    2017-03-01

    Full Text Available An experimental investigation has been carried out to study the influence on the performance characteristics of a cutting tool material notably known as cemented tungsten carbide (WC-Co. A comparison has been documented between nanocrystalline diamond (NCD and microcrystalline diamond (MCD coatings deposited on two cemented tungsten carbide (WC-Co substrates with the architectures of WC-Co/NCD and WC-Co/MCD, using hot filament chemical vapor deposition (HFCVD technique. In the present work, the friction characteristics were studied using ball-on-disc type linear reciprocating micro-tribometer, under the application of 1–10 N normal loads, when sliding against smooth alumina (Al2O3 ceramic ball for the total duration of 20 min, under dry sliding condition. Nanoindentation tests were also conducted using Berkovich nanoindenter for the purpose of measurement of hardness and elastic modulus values. However, the average value of friction coefficient (COF corresponding to MCD and NCD coatings decrease from ~0.37–0.32 and ~0.30–0.27, respectively when the load is increased from 1–10 N. However, for conventional WC-Co substrate the average COF increases from ~0.60–0.75, under the same input operating conditions. The wear tracks formed on the surfaces of NCD, MCD and WC-Co, after sliding were characterised using Raman spectroscopy and scanning electron microscopy (SEM techniques. Therefore, the results will serve breakthrough information for the designer to design the cutting tool or mechanical component using this novel coating procedure.

  1. Au ion irradiation of various silicon carbide fiber-reinforced SiC matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Chaâbane, Nihed, E-mail: nihed.chaabane@cea.fr [CEA, INSTN/UEPTN, F-91191 Gif-sur-Yvette (France); Flem, Marion Le [CEA, DEN/DMN/SRMA, F-91191 Gif-sur-Yvette (France); Tanguy, Morgane [CEA, INSTN/UEPTN, F-91191 Gif-sur-Yvette (France); Urvoy, Stéphane [CEA, DEN/DMN/SRMA, F-91191 Gif-sur-Yvette (France); Sandt, Christophe; Dumas, Paul [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex (France); Serruys, Yves [CEA, DEN/DMN/SRMP, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France)

    2013-08-15

    Silicon carbide fiber-reinforced SiC matrix composites are promising candidates as fuel cladding for several concepts of Generation IV reactors and as structural materials for fusion reactors. The composites used in this study were composed of a SiC matrix obtained by chemical vapor infiltration associated with various fiber types (Tyranno Type-S, Tyranno SA Grade-3 and Hi-Nicalon Type-S) and with a PyC layer as the interphase. 12 MeV Au ions were used for irradiation up to 0.05 and 1 displacement per atom (dpa) fluences at room temperature and 800 °C. Analysis of both microstructure and composition of composites were performed by scanning electron microscopy (SEM), electron probe microanalysis and Raman spectroscopy. At room temperature and low fluence, Raman spectroscopy results showed that irradiation induces a disordered/distorted state into fibers and matrix. With increasing fluence, a total amorphization of these constituents occurs. The increase in the irradiation temperature leads to a damage recovery and partial recrystallization of samples. Image analysis performed from SEM micrographs highlights no significant change in fiber diameter and shape. However, SEM analysis suggests a longitudinal shrinkage of Tyranno Type-S fibers for the composite irradiated at 1 dpa at room temperature and 800 °C. These results are in complete agreement with conclusions from neutron irradiations suggesting an appropriate relevance of irradiations with 12 MeV Au.

  2. Influence of substrate microstructure and surface finish on cracking and delamination response of TiN-coated cemented carbides

    OpenAIRE

    Yang, Jing; Odén, Magnus; Johansson-Joesaar, Mats P.; Llanes, L.

    2016-01-01

    The cracking and delamination of TiN-coated hardmetals (WC-Co cemented carbides) when subjected to Brale indentation were studied. Experimental variables were substrate microstructure related to low (6 wt% Co) and medium (13 wt% Co) binder content, and surface finishes associated with grinding and polishing stages before film deposition. Brale indentation tests were conducted on both coated and uncoated hardmetals. Emphasis has been placed on assessing substrate microstructure and subsurface ...

  3. Influence of Oxidation Behavior of Feedstock on Microstructure and Ablation Resistance of Plasma-Sprayed Zirconium Carbide Coating

    Science.gov (United States)

    Hu, Cui; Ge, Xuelian; Niu, Yaran; Li, Hong; Huang, Liping; Zheng, Xuebin; Sun, Jinliang

    2015-10-01

    Plasma spray is one of the suitable technologies to deposit carbide coatings with high melting point, such as ZrC. However, in the spray processes performed under atmosphere, oxidation of the carbide powder is inevitable. To investigate the influence of the oxidation behavior of feedstock on microstructure and ablation resistance of the deposited coating, ZrC coatings were prepared by atmospheric and vacuum plasma spray (APS and VPS) technologies, respectively. SiC-coated graphite was applied as the substrate. The obtained results showed that the oxidation of ZrC powder in APS process resulted in the formation of ZrO and Zr2O phases. Pores and cracks were more likely to be formed in the as-sprayed APS-ZrC coating. The VPS-ZrC coating without oxides possessed denser microstructure, higher thermal diffusivity, and lower coefficients of thermal expansion as compared with the APS-ZrC coating. A dense ZrO2 layer would be formed on the surface of the VPS-ZrC-coated sample during the ablation process and the substrate can be protected sufficiently after being ablated in high temperature plasma jet. However, the ZrO2 layer, formed by oxidation of the APS-ZrC coating having loose structure, was easy to be washed away by the shearing action of the plasma jet.

  4. The CVD coating of fibers for composite materials

    Science.gov (United States)

    Alam, M. Khairul; Jain, Sulekh C.

    1990-11-01

    Among the new composite materials, fiber-reinforced metal-matrix composites and ceramic-matrix composites have been given special attention for their potential uses in a variety of fields. A successful fabrication process for a fiber-reinforced composite requires that the fiber be protected, usually by a coating, during fabrication and service. The chemical vapor deposition process is a key technology for fiber coating. A survey of the current fiber coating programs seems to show that current process design in the industry is based on trial-and-error methods. New coating processes are, therefore, developed primarily by experimentation and prior experience. Ultimately, it is hoped that analytical and numerical process simulation will be used to reduce the need for costly trial-and-error process development.

  5. Performance of PVD-Coated Carbide Tools When Turning Inconel 718 in Dry Machining

    Directory of Open Access Journals (Sweden)

    Gusri Akhyar Ibrahim

    2011-01-01

    Full Text Available Inconel 718 has found its niche in many industries, owing to its unique properties such as high oxidation resistance and corrosion resistance even at very high temperatures. Coated carbide tool with hard layer of PVD TiAlN is used to turn Inconel 718. Taguchi method with the orthogonal array L9 is applied in this experiment with the parameter cutting speed of 60–80 m/min, feed rate of 0.2–0.3 mm/rev, and depth of cut of 0.3–0.5 mm. The results show that depth of cut is a significant influence to the tool life. Cutting speed of 60 m/min, feed rate of 0.2 mm/rev, and depth of cut of 0.3 mm are the optimum parameters. The flank wear, crater wear, notch wear, and nose wear are the wear mechanisms on the carbide tool. Through the SEM, abrasion, attrition, and adhesion are the wear mechanisms which can be seen on the cutting tool.

  6. Effect of CVD-diamond coatings on the tribological performance of cemented tungsten carbide substrates

    Directory of Open Access Journals (Sweden)

    Kaleem Ahmad Najar

    2016-06-01

    Full Text Available A comparison has been documented between nanocrystalline diamond (NCD and microcrystalline diamond (MCD coatings deposited on cemented tungsten carbide (WC-Co substrates with architectures of WC-Co/NCD & WC-Co/MCD, using hot filament chemical vapor deposition (HFCVD technique. In the present work, the frictional characteristics were studied using ball-on-disc type linear reciprocating micro-tribometer, under the application of 1–10N normal loads, when sliding against smooth alumina (Al2O3 ceramic ball for the total duration of 15min, under dry sliding conditions. Nanoindentation tests were also conducted using Berkovich nanoindenter for the purpose of measurement of hardness and elastic modulus values. The average coefficients of friction of MCD and NCD coatings decrease from 0.37 – 0.32 and 0.3 – 0.27 respectively, when the load is increased from 1–10N. However, for conventional WC-Co substrate the average coefficient of friction increases from 0.60–0.75, under the same input operating conditions. The wear tracks formed on the surfaces of CVD-diamond coatings and WC-Co substrate, after friction measurement were characterised using Raman spectroscopy and scanning electron microscopy (SEM techniques. However, the compositional analysis for the formation of tribo-layer observed on the wear tracks of CVD-diamond coatings was confirmed using energy dispersive spectroscopy (EDS technique. Therefore, maintaining an appropriate level of normal load and using appropriate type of diamond coating, friction may be kept to some lower value to improve mechanical processes.

  7. Oxidation-resistant interfacial coatings for continuous fiber ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Besmann, T.M.; Bleier, A. [Oak Ridge National Lab., TN (United States); Shanmugham, S.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-08-01

    Continuous fiber ceramic composites mechanical behavior are influenced by the bonding characteristics between the fiber and the matrix. Finite modeling studies suggest that a low-modulus interfacial coating material will be effective in reducing the residual thermal stresses that are generated upon cooling from processing temperatures. Nicalon{trademark}/SiC composites with carbon, alumina and mullite interfacial coatings were fabricated with the SiC matrix deposited using a forced-flow, thermal gradient chemical vapor infiltration process. Composites with mullite interfacial coatings exhibited considerable fiber pull-out even after oxidation and have potential as a composite system.

  8. Metal matrix coated fiber composites and the methods of manufacturing such composites

    Science.gov (United States)

    Weeks, Jr., Joseph K.; Gensse, Chantal

    1993-01-01

    A fiber coating which allows ceramic or metal fibers to be wetted by molten metals is disclosed. The coating inhibits degradation of the physical properties caused by chemical reaction between the fiber and the coating itself or between the fiber and the metal matrix. The fiber coating preferably includes at least a wetting layer, and in some applications, a wetting layer and a barrier layer between the fiber and the wetting layer. The wetting layer promotes fiber wetting by the metal matrix. The barrier layer inhibits fiber degradation. The fiber coating permits the fibers to be infiltrated with the metal matrix resulting in composites having unique properties not obtainable in pure materials.

  9. An experimental study of flank wear in the end milling of AISI 316 stainless steel with coated carbide inserts

    Science.gov (United States)

    Odedeyi, P. B.; Abou-El-Hossein, K.; Liman, M.

    2017-05-01

    Stainless steel 316 is a difficult-to-machine iron-based alloys that contain minimum of about 12% of chromium commonly used in marine and aerospace industry. This paper presents an experimental study of the tool wear propagation variations in the end milling of stainless steel 316 with coated carbide inserts. The milling tests were conducted at three different cutting speeds while feed rate and depth of cut were at (0.02, 0.06 and 01) mm/rev and (1, 2 and 3) mm, respectively. The cutting tool used was TiAlN-PVD-multi-layered coated carbides. The effects of cutting speed, cutting tool coating top layer and workpiece material were investigated on the tool life. The results showed that cutting speed significantly affected the machined flank wears values. With increasing cutting speed, the flank wear values decreased. The experimental results showed that significant flank wear was the major and predominant failure mode affecting the tool life.

  10. Characterization of C/SiC Ceramic Matrix Composites (CMCs) with Novel Interface Fiber Coatings

    Science.gov (United States)

    Petko, Jeanne F.; Kiser, J. Douglas; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Ceramic Matrix Composites (CMCs) are attractive candidate aerospace materials due to their high specific strength, low density and high temperature capabilities. The National Aeronautics and Space Administration (NASA) is pursuing the use of CMC components in advanced Reusable Launch Vehicle (RLV) propulsion applications. Carbon fiber-reinforced silicon carbide (C/SiC) is the primary material of interest for a variety of RLV propulsion applications. These composites consist of high-strength carbon fibers and a high modulus, oxidation resistant matrix. For RLV propulsion applications, environmental durability will be critical. Two types of carbon fibers were processed with both standard (pyrolytic carbon) and novel (multilayer and pseudoporous) types of interface coatings as part of a study investigating various combinations of constituents. The benefit of protecting the composites with a surface sealant was also investigated. The strengths, durability in oxidizing environments, and microstructures of these developmental composite materials are presented. The novel interface coatings and the surface sealant show promise for protecting the carbon fibers from the oxidizing environment.

  11. Mechanical and Tribological Properties of PVD-Coated Cemented Carbide as Evaluated by a New Multipass Scratch-Testing Method

    Directory of Open Access Journals (Sweden)

    M. Fallqvist

    2012-01-01

    Full Text Available A new test method based on multipass scratch testing has been developed for evaluating the mechanical and tribological properties of thin, hard coatings. The proposed test method uses a pin-on-disc tribometer and during testing a Rockwell C diamond stylus is used as the “pin” and loaded against the rotating coated sample. The influence of normal load on the number of cycles to coating damage is investigated and the resulting coating damage mechanisms are evaluated by posttest scanning electron microscopy. The present study presents the test method by evaluating the performance of Ti0.86Si0.14N, Ti0.34Al0.66N, and (Al0.7Cr0.32O3 coatings deposited by cathodic arc evaporation on cemented carbide inserts. The results show that the test method is quick, simple, and reproducible and can preferably be used to obtain relevant data concerning the fatigue, wear, chipping, and spalling characteristics of different coating-substrate composites. The test method can be used as a virtually nondestructive test and, for example, be used to evaluate the fatigue and wear resistance as well as the cohesive and adhesive interfacial strength of coated cemented carbide inserts prior to cutting tests.

  12. Chemical vapour deposition diamond coating on tungsten carbide dental cutting tools

    Science.gov (United States)

    Sein, H.; Ahmed, W.; Rego, C. A.; Jones, A. N.; Amar, M.; Jackson, M.; Polini, R.

    2003-10-01

    Diamond coatings on Co cemented tungsten carbide (WC-Co) hard metal tools are widely used for cutting non-ferrous metals. It is difficult to deposit diamond onto cutting tools, which generally have a complex geometry, using a single step growth process. This paper focuses on the deposition of polycrystalline diamond films onto dental tools, which possess 3D complex or cylindrical shape, employing a novel single step chemical vapour deposition (CVD) growth process. The diamond deposition is carried out in a hot filament chemical vapour deposition (HFCVD) reactor with a modified filament arrangement. The filament is mounted vertically with the drill held concentrically in between the filament coils, as opposed to the commonly used horizontal arrangement. This is a simple and inexpensive filament arrangement. In addition, the problems associated with adhesion of diamond films on WC-Co substrates are amplified in dental tools due to the very sharp edges and unpredictable cutting forces. The presence of Co, used as a binder in hard metals, generally causes poor adhesion. The amount of metallic Co on the surface can be reduced using a two step pre-treatment employing Murakami etching followed by an acid treatment. Diamond films are examined in terms of their growth rate, morphology, adhesion and cutting efficiency. We found that in the diamond coated dental tool the wear rate was reduced by a factor of three as compared to the uncoated tool.

  13. Experimental evaluation of coated carbide insert on alloy of steel materials during high speed turning process

    Directory of Open Access Journals (Sweden)

    S. A. Lawal

    2017-06-01

    Full Text Available The present study investigated the effect of coated carbide turning inserts on the surface roughness of AISI 304L austenitic stainless steel, AISI 316L austenitic stainless steel and AISI 1020 low carbon steel workpiece materials. The three steel grade materials were dry-turned using aluminium oxide (Al2O3 duratomic coated inserts at cutting speeds ranging from 1500 – 2000 rpm (229 – 314 m/min, feed rates of 0.25 – 0.75 mm/rev and depth of cut kept constant at 0.5 mm. Surface roughness values at different cutting conditions were measured and analysed. Chips formed at different cutting parameters were collected, classified according to ISO 3685 standards for chip classification and their surface morphology were analysed using optical microscopy. It was observed that feed rate had the greatest influence on surface roughness for the three workpiece materials. Surface finish deteriorated as feed rate increased. The chips formed were generally of the continuous type with built-up-edges.

  14. THE EVALUATION OF TOOL WEAR IN THE MACHINING AISI 1050 STEEL HARDENED UP TO 53 HRC WITH COATED CARBIDE TOOL

    Directory of Open Access Journals (Sweden)

    Ali Rıza MOTORCU

    2006-03-01

    Full Text Available In this study, the machining of AISI 1050 steel which is hardened up to 53 HRC is carried out with two carbide tool materials (three layer coated carbide of TP100 containing Ti (C, N/Al2O3/TiN and (multi layer coated carbide of TP1000 containing Ti (C, N/Al2O3/ Ti (C, N/TiN. Cutting tests are performed with constant depth of cut and feed rate under dry cutting conditions. The flank wear is examined using an optical microscope. Tool life curves and Taylor Tool Life Equation constants (n, C are obtained via the flank wear data at various cutting speeds. The test results show that tools' performance is adversely affected by increasing cutting speed due to increased temperatures and stress generated at the cutting edges during machining. Flank wear and chipping/fracture of the tool edges are identified the major failure modes at the cutting conditions. TP1000 multilayer coated inserts give longer tool life than those of TP100 three layer coated inserts.

  15. Smart Cellulose Fibers Coated with Carbon Nanotube Networks

    Directory of Open Access Journals (Sweden)

    Haisong Qi

    2014-11-01

    Full Text Available Smart multi-walled carbon nanotube (MWCNT-coated cellulose fibers with a unique sensing ability were manufactured by a simple dip coating process. The formation of electrically-conducting MWCNT networks on cellulose mono- and multi-filament fiber surfaces was confirmed by electrical resistance measurements and visualized by scanning electron microscopy. The interaction between MWCNT networks and cellulose fiber was investigated by Raman spectroscopy. The piezoresistivity of these fibers for strain sensing was investigated. The MWCNT-coated cellulose fibers exhibited a unique linear strain-dependent electrical resistance change up to 18% strain, with good reversibility and repeatability. In addition, the sensing behavior of these fibers to volatile molecules (including vapors of methanol, ethanol, acetone, chloroform and tetrahydrofuran was investigated. The results revealed a rapid response, high sensitivity and good reproducibility for these chemical vapors. Besides, they showed good selectivity to different vapors. It is suggested that the intrinsic physical and chemical features of cellulose fiber, well-formed MWCNT networks and favorable MWCNT-cellulose interaction caused the unique and excellent sensing ability of the MWCNT-coated cellulose fibers, which have the potential to be used as smart materials.

  16. Optical Fiber Sensors Based on Nanoparticle-Embedded Coatings

    Directory of Open Access Journals (Sweden)

    Aitor Urrutia

    2015-01-01

    Full Text Available The use of nanoparticles (NPs in scientific applications has attracted the attention of many researchers in the last few years. The use of NPs can help researchers to tune the physical characteristics of the sensing coating (thickness, roughness, specific area, refractive index, etc. leading to enhanced sensors with response time or sensitivity better than traditional sensing coatings. Additionally, NPs also offer other special properties that depend on their nanometric size, and this is also a source of new sensing applications. This review focuses on the current status of research in the use of NPs within coatings in optical fiber sensing. Most used sensing principles in fiber optics are briefly described and classified into several groups: absorbance-based sensors, interferometric sensors, fluorescence-based sensors, fiber grating sensors, and resonance-based sensors, among others. For each sensor group, specific examples of the utilization of NP-embedded coatings in their sensing structure are reported.

  17. Polymer Coating of Carbon Nanotube Fibers for Electric Microcables.

    Science.gov (United States)

    Alvarez, Noe T; Ochmann, Timothy; Kienzle, Nicholas; Ruff, Brad; Haase, Mark R; Hopkins, Tracy; Pixley, Sarah; Mast, David; Schulz, Mark J; Shanov, Vesselin

    2014-11-04

    Carbon nanotubes (CNTs) are considered the most promising candidates to replace Cu and Al in a large number of electrical, mechanical and thermal applications. Although most CNT industrial applications require macro and micro size CNT fiber assemblies, several techniques to make conducting CNT fibers, threads, yarns and ropes have been reported to this day, and improvement of their electrical and mechanical conductivity continues. Some electrical applications of these CNT conducting fibers require an insulating layer for electrical insulation and protection against mechanical tearing. Ideally, a flexible insulator such as hydrogenated nitrile butadiene rubber (HNBR) on the CNT fiber can allow fabrication of CNT coils that can be assembled into lightweight, corrosion resistant electrical motors and transformers. HNBR is a largely used commercial polymer that unlike other cable-coating polymers such as polyvinyl chloride (PVC), it provides unique continuous and uniform coating on the CNT fibers. The polymer coated/insulated CNT fibers have a 26.54 μm average diameter-which is approximately four times the diameter of a red blood cell-is produced by a simple dip-coating process. Our results confirm that HNBR in solution creates a few microns uniform insulation and mechanical protection over a CNT fiber that is used as the electrically conducting core.

  18. Polymer Coating of Carbon Nanotube Fibers for Electric Microcables

    Directory of Open Access Journals (Sweden)

    Noe T. Alvarez

    2014-11-01

    Full Text Available Carbon nanotubes (CNTs are considered the most promising candidates to replace Cu and Al in a large number of electrical, mechanical and thermal applications. Although most CNT industrial applications require macro and micro size CNT fiber assemblies, several techniques to make conducting CNT fibers, threads, yarns and ropes have been reported to this day, and improvement of their electrical and mechanical conductivity continues. Some electrical applications of these CNT conducting fibers require an insulating layer for electrical insulation and protection against mechanical tearing. Ideally, a flexible insulator such as hydrogenated nitrile butadiene rubber (HNBR on the CNT fiber can allow fabrication of CNT coils that can be assembled into lightweight, corrosion resistant electrical motors and transformers. HNBR is a largely used commercial polymer that unlike other cable-coating polymers such as polyvinyl chloride (PVC, it provides unique continuous and uniform coating on the CNT fibers. The polymer coated/insulated CNT fibers have a 26.54 μm average diameter—which is approximately four times the diameter of a red blood cell—is produced by a simple dip-coating process. Our results confirm that HNBR in solution creates a few microns uniform insulation and mechanical protection over a CNT fiber that is used as the electrically conducting core.

  19. Corrosion Resistance of Nanosized Silicon Carbide-Rich Composite Coatings Produced by Noble Gas Ion Mixing.

    Science.gov (United States)

    Racz, A S; Kerner, Z; Nemeth, A; Panjan, P; Peter, L; Sulyok, A; Vertesy, G; Zolnai, Z; Menyhard, M

    2017-12-27

    Ion beam mixing has been used to produce a silicon carbide (SiC)-rich nanolayer for protective coating. Different C/Si/C/Si/C/Si(substrate) multilayer structures (with individual layer thicknesses falling in the range of 10-20 nm) have been irradiated by Ar+ and Xe+ ions at room temperature in the energy and fluence ranges of 40-120 keV and 1-6 × 1016 ion/cm2, respectively. The effects of ion irradiation, including the in-depth distribution of the SiC produced, was determined by Auger electron spectroscopy depth profiling. The thickness of the SiC-rich region was only some nanometers, and it could be tailored by changing the layer structure and the ion irradiation conditions. The corrosion resistance of the layers was investigated by potentiodynamic electrochemical test in 4 M KOH solution. The measured corrosion resistance of the SiC-rich layers was orders of magnitude better than that of pure silicon, and a correlation was found between the corrosion current density and the effective areal density of the SiC.

  20. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    Energy Technology Data Exchange (ETDEWEB)

    Amir, N., E-mail: norlailiamir@petronas.com.my; Othman, W. M. S. W., E-mail: wamosa@gmail.com; Ahmad, F., E-mail: faizahmad@petronas.com.my [Mechanical Engineering Department, Universiti Teknologi PETRONAS Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2015-07-22

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

  1. Easy and safe coated optical fiber direct connection without handling bare optical fiber

    Science.gov (United States)

    Saito, Kotaro; Kihara, Mitsuru; Shimizu, Tomoya; Kurashima, Toshio

    2015-06-01

    We propose a novel field installable splicing technique for the direct connection of 250 μm diameter coated optical fiber that does not require bare optical fiber to be handled. Our proposed technique can realize a low insertion loss over a wide field installation temperature range of -10-40 °C. The keys to coated optical fiber direct connection are a cleaving technique and a technique for removing coated optical fiber. As the cleaving technique, we employed a method where the fiber is stretched and then a blade is pushed perpendicularly against the stretched fiber. As a result we confirmed that fiber endfaces cleaved at -10-40 °C were all mirror endfaces. With the removal technique, the coating is removed inside the connecting component by incorporating a circular cone shaped coating removal part. A mechanical splice based on these techniques successfully achieved a low insertion loss of less than 0.11 dB and a return loss of more than 50 dB at -10, 20, and 40 °C. In addition, the temperature cycle characteristics were stable over a wide temperature range of -40-75 °C.

  2. Study of PVD AlCrN Coating for Reducing Carbide Cutting Tool Deterioration in the Machining of Titanium Alloys.

    Science.gov (United States)

    Cadena, Natalia L; Cue-Sampedro, Rodrigo; Siller, Héctor R; Arizmendi-Morquecho, Ana M; Rivera-Solorio, Carlos I; Di-Nardo, Santiago

    2013-05-24

    The manufacture of medical and aerospace components made of titanium alloys and other difficult-to-cut materials requires the parallel development of high performance cutting tools coated with materials capable of enhanced tribological and resistance properties. In this matter, a thin nanocomposite film made out of AlCrN (aluminum-chromium-nitride) was studied in this research, showing experimental work in the deposition process and its characterization. A heat-treated monolayer coating, competitive with other coatings in the machining of titanium alloys, was analyzed. Different analysis and characterizations were performed on the manufactured coating by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDXS), and X-ray diffraction (XRD). Furthermore, the mechanical behavior of the coating was evaluated through hardness test and tribology with pin-on-disk to quantify friction coefficient and wear rate. Finally, machinability tests using coated tungsten carbide cutting tools were executed in order to determine its performance through wear resistance, which is a key issue of cutting tools in high-end cutting at elevated temperatures. It was demonstrated that the specimen (with lower friction coefficient than previous research) is more efficient in machinability tests in Ti6Al4V alloys. Furthermore, the heat-treated monolayer coating presented better performance in comparison with a conventional monolayer of AlCrN coating.

  3. Study of PVD AlCrN Coating for Reducing Carbide Cutting Tool Deterioration in the Machining of Titanium Alloys

    Science.gov (United States)

    Cadena, Natalia L.; Cue-Sampedro, Rodrigo; Siller, Héctor R.; Arizmendi-Morquecho, Ana M.; Rivera-Solorio, Carlos I.; Di-Nardo, Santiago

    2013-01-01

    The manufacture of medical and aerospace components made of titanium alloys and other difficult-to-cut materials requires the parallel development of high performance cutting tools coated with materials capable of enhanced tribological and resistance properties. In this matter, a thin nanocomposite film made out of AlCrN (aluminum–chromium–nitride) was studied in this research, showing experimental work in the deposition process and its characterization. A heat-treated monolayer coating, competitive with other coatings in the machining of titanium alloys, was analyzed. Different analysis and characterizations were performed on the manufactured coating by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDXS), and X-ray diffraction (XRD). Furthermore, the mechanical behavior of the coating was evaluated through hardness test and tribology with pin-on-disk to quantify friction coefficient and wear rate. Finally, machinability tests using coated tungsten carbide cutting tools were executed in order to determine its performance through wear resistance, which is a key issue of cutting tools in high-end cutting at elevated temperatures. It was demonstrated that the specimen (with lower friction coefficient than previous research) is more efficient in machinability tests in Ti6Al4V alloys. Furthermore, the heat-treated monolayer coating presented better performance in comparison with a conventional monolayer of AlCrN coating. PMID:28809266

  4. Simulation of magnetic coatings on textile fibers

    Science.gov (United States)

    Blachowicz, T.; Ehrmann, A.

    2016-08-01

    While the properties of conductive fibres and coatings on textiles can easily be measured and calculated, magnetic coatings of fibres, yarns and fabrics still lack descriptions of their physical properties. Since magnetic textiles can be used for a variety of applications, from magnetic filters to invisible water-marks to magnetic coils and sensors, simulations would be supportive to understand and utilize their properties. The article gives an overview of different coatings on textile fibres, varying the magnetic materials as well as the fibre composition, giving rise to the interactions between neighbouring coated fibres. In this way, it is possible to understand the strong shape anisotropy which must be taken into account when the magnetic properties of textiles are to be tailored. Additionally, the differences between several possible magnetic coating materials become visible. This study can help adjusting the magnetic properties of textile fabrics to a desired application.

  5. Effect of Carbide Dissolution on Chlorine Induced High Temperature Corrosion of HVOF and HVAF Sprayed Cr3C2-NiCrMoNb Coatings

    Science.gov (United States)

    Fantozzi, D.; Matikainen, V.; Uusitalo, M.; Koivuluoto, H.; Vuoristo, P.

    2018-01-01

    Highly corrosion- and wear-resistant thermally sprayed chromium carbide (Cr3C2)-based cermet coatings are nowadays a potential highly durable solution to allow traditional fluidized bed combustors (FBC) to be operated with ecological waste and biomass fuels. However, the heat input of thermal spray causes carbide dissolution in the metal binder. This results in the formation of carbon saturated metastable phases, which can affect the behavior of the materials during exposure. This study analyses the effect of carbide dissolution in the metal matrix of Cr3C2-50NiCrMoNb coatings and its effect on chlorine-induced high-temperature corrosion. Four coatings were thermally sprayed with HVAF and HVOF techniques in order to obtain microstructures with increasing amount of carbide dissolution in the metal matrix. The coatings were heat-treated in an inert argon atmosphere to induce secondary carbide precipitation. As-sprayed and heat-treated self-standing coatings were covered with KCl, and their corrosion resistance was investigated with thermogravimetric analysis (TGA) and ordinary high-temperature corrosion test at 550 °C for 4 and 72 h, respectively. High carbon dissolution in the metal matrix appeared to be detrimental against chlorine-induced high-temperature corrosion. The microstructural changes induced by the heat treatment hindered the corrosion onset in the coatings.

  6. Electrospun Nanofiber Coating of Fiber Materials: A Composite Toughening Approach

    Science.gov (United States)

    Kohlman, Lee W.; Roberts, Gary D.

    2012-01-01

    Textile-based composites could significantly benefit from local toughening using nanofiber coatings. Nanofibers, thermoplastic or otherwise, can be applied to the surface of the fiber tow bundle, achieving toughening of the fiber tow contact surfaces, resulting in tougher and more damage-resistant/tolerant composite structures. The same technique could also be applied to other technologies such as tape laying, fiber placement, or filament winding operations. Other modifications to the composite properties such as thermal and electrical conductivity could be made through selection of appropriate nanofiber material. Control of the needle electric potential, precursor solution, ambient temperature, ambient humidity, airflow, etc., are used to vary the diameter and nanofiber coating morphology as needed. This method produces a product with a toughening agent applied to the fiber tow or other continuous composite precursor material where it is needed (at interfaces and boundaries) without interfering with other composite processing characteristics.

  7. Deposition of titanium coating on SiC fiber by chemical vapor deposition with Ti-I{sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xian, E-mail: luo_shenfan@hotmail.com; Wu, Shuai; Yang, Yan-qing; Jin, Na; Liu, Shuai; Huang, Bin

    2017-06-01

    Highlights: • The transformation paths of (Ti + I{sub 2}) powder to Ti coating is: Ti + I{sub 2} → (TiI{sub 2}, TiI{sub 3}) → Ti. • Uniform coating was obtained on SiC fiber, but it contained Si and C elements. • Deposition rate of the coating increased with the increase of temperature. • Deposition thickness increased with time and achieved the maximum at 90 min. - Abstract: Titanium coating was prepared on SiC fiber using titanium-iodine (Ti-I{sub 2}) mixture by hot-wall chemical vapor deposition. Thermodynamic analysis and experimental observation were carried out in this work. The thermodynamic analysis of the reactions in the Ti-I{sub 2} system indicates that Ti and I{sub 2} raw powder materials transform to titanium coating as follows: Ti + I{sub 2} → (TiI{sub 2}, TiI{sub 3}), and (TiI{sub 2}, TiI{sub 3}) → Ti. In theory, the conversions of TiI{sub 3} and TiI{sub 2} reach the maximum when Ti:I{sub 2} is 1:1.5, while in actual experiment that reached the maximum when Ti:I{sub 2} was 1:2, as there existed the waste of I{sub 2} due to sublimation. Typical deposited coating is relatively flat and uniform. However, as SiC is prone to react with Ti at high temperatures, the obtained coating contained some Si and C elements except for Ti. So the coating was not a pure Ti coating but contained some carbides and silicides. Deposition rate of the coating increased with the increase of temperature. The deposited thickness increased with the increase of heat preservation time, and achieved the maximum thickness at 90 min.

  8. Can silicon carbide serve as a saturable absorber for passive mode-locked fiber lasers?

    Science.gov (United States)

    Cheng, Chih-Hsien; Lin, Yung-Hsiang; Chen, Ting-Hui; Chen, Hsiang-Yu; Chi, Yu-Chieh; Lee, Chao-Kuei; Leeb, Chao-Kuei; Wu, Chih-I; Wua, Chih-I; Lin, Gong-Ru

    2015-11-12

    The study presents a novel demonstration of a passively mode-locked erbium-doped fiber laser (EDFL) that is based on a silicon carbide (SixC1-x) saturable absorber. When the C/Si composition ratio is increased to 1.83, the SixC1-x film transforms from two-photon absorption to nonlinear saturable absorption, and the corresponding value reaches -3.9 × 10(-6) cm/W. The Si-rich SixC1-x film cannot mode lock the EDFL because it induced high intracavity loss through two-photon absorption. Even when a stoichiometric SiC is used, the EDFL is mode locked, similar to an EDFL operating under weak nonlinear-polarization-rotation condition. A C-rich SixC1-x film containing sp(2)-orbital C-C bonds with a linear absorbance of 0.172 and nonlinear absorbance of 0.04 at a 181 MW/cm(2) saturation intensity demonstrates nonlinear transmittance. The C-rich SixC1-x saturable absorber successfully generates a short mode-locked EDFL pulse of 470 fs. The fluctuation of the pulse-train envelope dropps considerably from 11.6% to 0.8% when a strong saturable-absorption-induced self-amplitude modulation process occurs in the C-rich SixC1-x film.

  9. Deposition of titanium coating on SiC fiber by chemical vapor deposition with Ti-I2 system

    Science.gov (United States)

    Luo, Xian; Wu, Shuai; Yang, Yan-qing; Jin, Na; Liu, Shuai; Huang, Bin

    2017-06-01

    Titanium coating was prepared on SiC fiber using titanium-iodine (Ti-I2) mixture by hot-wall chemical vapor deposition. Thermodynamic analysis and experimental observation were carried out in this work. The thermodynamic analysis of the reactions in the Ti-I2 system indicates that Ti and I2 raw powder materials transform to titanium coating as follows: Ti + I2 → (TiI2, TiI3), and (TiI2, TiI3) → Ti. In theory, the conversions of TiI3 and TiI2 reach the maximum when Ti:I2 is 1:1.5, while in actual experiment that reached the maximum when Ti:I2 was 1:2, as there existed the waste of I2 due to sublimation. Typical deposited coating is relatively flat and uniform. However, as SiC is prone to react with Ti at high temperatures, the obtained coating contained some Si and C elements except for Ti. So the coating was not a pure Ti coating but contained some carbides and silicides. Deposition rate of the coating increased with the increase of temperature. The deposited thickness increased with the increase of heat preservation time, and achieved the maximum thickness at 90 min.

  10. Ultraviolet-Diode Pump Solid State Laser Removal of Titanium Aluminium Nitride Coating from Tungsten Carbide Substrate

    Science.gov (United States)

    See, Tian Long; Chantzis, Dimitrios; Royer, Raphael; Metsios, Ioannis; Antar, Mohammad; Marimuthu, Sundar

    2017-09-01

    This paper presents an investigation on the titanium aluminium nitride (TiAlN) coating removal from tungsten carbide (WC-Co) substrate using a diode pump solid state (DPSS) ultraviolet (UV) laser with maximum average power of 90 W, wavelength of 355 nm and pulse width of 50 ns. The TiAlN coating of 1.5 μm thickness is removed from the WC-Co substrate with laser fluence of 2.71 J/cm2 at 285.6 number of pulses (NOP) and with NOP of 117.6 at 3.38 J/cm2 fluence. Titanium oxide formation was observed on the ablated surface due to the re-deposition of ablated titanium residue and also attributed to the high temperature observed during the laser ablation process. Crack width of around 0.2 μm was observed over both TiAlN coating and WC-Co substrate. The crack depth ranging from 1 to 10 μm was observed and is related to the thickness of the melted carbide. The crack formation is a result of the thermal induced stresses caused by the laser beam interaction with the material as well as the higher thermal conductivity of cobalt compared to WC. Two cleaning regions are observed and is a consequence of the Gaussian distribution of the laser beam energy. The surface roughness of the ablated WC-Co increased with increasing laser fluence and NOP.

  11. Effect of silica coating on flexural strength of fiber posts

    NARCIS (Netherlands)

    Valandro, LF; Ozcan, M; de Melo, RM; Galhano, GAP; Baldissara, P; Scotti, R; Bottino, MA

    2006-01-01

    Purpose: Fiber-reinforced composite (FRC) posts can be air-abraded to obtain good attachment to the resin cement. This study tested the effect of silica coating on the flexural strength of carbon, opaque, and translucent quartz FRC posts. Materials and Methods: Six experimental groups of FRC posts

  12. Ceramic fiber reinforced filter

    Science.gov (United States)

    Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  13. Plasma Spraying and Characterization of Tungsten Carbide-Cobalt Coatings by the Water-Stabilized System WSP

    Directory of Open Access Journals (Sweden)

    Pavel Ctibor

    2009-01-01

    Full Text Available Tungsten carbide-cobalt powders (WC-17wt% Co were plasma sprayed by a water-stabilized system WSP. Experiments with variable feeding distances and spray distances were carried out. Thinner coatings were deposited on carbon steel substrates and thicker coatings on stainless steel substrates to compare different cooling conditions. Basic characterization of coatings was done by XRD, SEM, and light microscopy plus image analysis. Microhardness was measured on polished cross-sections. The main focus of investigation was resistance against wear in dry as well as wet conditions. The appropriate tests were performed with set-ups based on ASTM G65 and G75, respectively. The influence of spray parameters onto coating wear performance was observed. The results of mechanical tests were discussed in connection with changes of phase composition and with the quality of the coating's microstructure. The results show that for obtaining the best possible WC-17Co coating with WSP process, from the viewpoint of wear resistance, the desired parameters combination is long feeding distance combined with short spray distance.

  14. Enhanced Acoustic Sensitivity in Polymeric Coated Fiber Bragg Grating

    Directory of Open Access Journals (Sweden)

    Andrea CUSANO

    2007-08-01

    Full Text Available In this work, a new fiber optic hydrophone based on the intensity modulation of the laser light in FBG (Fiber Bragg Grating under the influence of the sound pressure is experimental proved. In order to increase the sensitivity, FBGs have been coated with proper materials characterized by elastic modulus much lower than the fiber one. The minimum detectable acoustic pressure has been found to be of the order of ~10Pa in the investigated frequency range, with excellent performances in terms of linear response and wide dynamic range. The experimental analysis also reveals that, by a proper design of the coating features, sensor bandwidth and sensitivity can be tailored for specific applications.

  15. Biocatalytic material comprising multilayer enzyme coated fiber

    Science.gov (United States)

    Kim, Jungbae [Richland, WA; Kwak, Ja Hun [Richland, WA; Grate, Jay W [West Richland, WA

    2009-11-03

    The present invention relates generally to high stability, high activity biocatalytic materials and processes for using the same. The materials comprise enzyme aggregate coatings having high biocatalytic activity and stability useful in heterogeneous environment. These new materials provide a new biocatalytic immobilized enzyme system with applications in bioconversion, bioremediation, biosensors, and biofuel cells.

  16. Deposition of multicomponent chromium carbide coatings using a non-conventional source of chromium and silicon with micro-additions of boron

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Ruiz, Jesus Eduardo, E-mail: jesus.gonzalez@biomat.uh.cu [Biomaterials Center, University of Havana (Cuba); Rodriguez Cristo, Alejandro [Mechanical Plants Company, Road of the Sub-Plan, Farm La Cana, Santa Clara, Villa Clara (Cuba); Ramos, Adrian Paz [Department of Chemistry, Universite de Montreal, Quebec (Canada); Quintana Puchol, Rafael [Welding Research Center, Central University Marta Abreu of Las Villas, Villa Clara (Cuba)

    2017-01-15

    The chromium carbide coatings are widely used in the mechanical industry due to its corrosion resistance and mechanical properties. In this work, we evaluated a new source of chromium and silicon with micro-additions of boron on the deposition of multi-component coatings of chromium carbides in W108 steel. The coatings were obtained by the pack cementation method, using a simultaneous deposition at 1000 deg for 4 hours. The coatings were analyzed by X-ray diffraction, X-ray energy dispersive spectroscopy, optical microscopy, microhardness test method and pin-on-disc wear test. It was found that the coatings formed on W108 steel were mainly constituted by (Cr,Fe){sub 23}C{sub 6} , (Cr,Fe){sub 7} C{sub 3} , Cr{sub 5-x}Si{sub 3-x} C{sub x+z}, Cr{sub 3} B{sub 0,44}C{sub 1,4} and (or) Cr{sub 7} BC{sub 4} . The carbide layers showed thicknesses between 14 and 15 μm and maximum values of microhardness between 15.8 and 18.8 GPa. Also, the micro-additions of boron to the mixtures showed statistically significant influence on the thickness, microhardness and abrasive wear resistance of the carbide coatings. (author)

  17. Microstructural and Mechanical Study of Inconel 625 – Tungsten Carbide Composite Coatings Obtained by Powder Laser Cladding

    Directory of Open Access Journals (Sweden)

    Huebner J.

    2017-06-01

    Full Text Available This study focuses on the investigation of fine (~0.54 μm tungsten carbide particles effect on structural and mechanical properties of laser cladded Inconel 625-WC composite. Three powder mixtures with different Inconel 625 – WC weight ratio (10, 20 and 30 weight % of WC were prepared. Coatings were made using following process parameters: laser beam diameter ø ≈ 500 μm, powder feeder rotation speed – 7 m/min, scanning velocity – 10 m/min, laser power – 220 W changed to 320 W, distance between tracks – 1 mm changed to 0.8 mm. Microstructure and hardness were investigated. Coatings produced by laser cladding were crack and pore free, chemically and structurally homogenous. High cooling rate during cladding process resulted in fine microstructure of material. Hardness improved with addition of WC from 396.3 ±10.5 HV for pure Inconel 625, to 469.9 ±24.9 HV for 30 weight % of WC. Tungsten carbide dissolved in Inconel 625 which allowed formation of intergranular eutectic that contains TCP phases.

  18. Ceramic Fiber Coatings Development and Demonstration

    Science.gov (United States)

    1993-05-28

    within the accuracy of the data, the activity of Si02 in spodumene is equal to that of pure Si02 and (2) the key reaction for assessing the...compatibility of spodumene and boron nitride is 2/3BN(s) + Si02 (s) - Si0(g) + i/3B2 03 (s or 1) + 1/3N2 (g) (7) Calculated equilibrium partial pressures at...concern. Therefore, boron nitride and spodumene are considered to be compatible up to 1600K. Boron Nitride Coating/Cordierite (MAS) Matrix Our

  19. Use of microhardness as a simple means of estimating relative wear resistance of carbide thermal spray coatings: Part 2. wear resistance of cemented carbide coatings

    Science.gov (United States)

    Factor, Michael; Roman, Itzhak

    2002-12-01

    A selection of WC-Co and Cr3C2-25%NiCr coatings produced by plasma spray and high velocity oxygen fuel (HVOF) deposition techniques were subjected to various wear tests designed to simulate abrasion, cavitation, sliding, and particle erosion type wear mechanisms. All of the coatings were at least 200 µm thick and were deposited onto stainless steel substrates. In Part 1 of this contribution, the microstructures of the coatings were characterized and their mechanical properties were assessed using microindentation procedures. In this second part of the article, the behavior of the coatings when subjected to the various wear tests is reported and the utility of microhardness testing as an indication of relative wear resistance is discussed. It is shown that correctly performed, appropriate microhardness measurements are a good indication of abrasion resistance and sliding wear resistance, and also correlate well with cavitation resistance in Cr3C2-NiCr. The measurements were less useful for predicting erosion resistance for both Cr3C2-NiCr and WC-Co, however, and for abrasion resistance when WC-Co was ground against SiC. Here the contribution of micromechanisms involving fracturing and brittle failure is greater than that indicated by the coating microhardness, which is essentially a measurement of resistance to plastic deformation under equilibrium conditions.

  20. Experimental investigation on flank wear and tool life, cost analysis and mathematical model in turning hardened steel using coated carbide inserts

    Directory of Open Access Journals (Sweden)

    Ashok Kumar Sahoo

    2013-10-01

    Full Text Available Turning hardened component with PCBN and ceramic inserts have been extensively used recently and replaces traditional grinding operation. The use of inexpensive multilayer coated carbide insert in hard turning is lacking and hence there is a need to investigate the potential and applicability of such tools in turning hardened steels. An attempt has been made in this paper to have a study on turning hardened AISI 4340 steel (47 ± 1 HRC using coated carbide inserts (TiN/TiCN/Al2O3/ZrCN under dry environment. The aim is to assess the tool life of inserts and evolution of flank wear with successive machining time. From experimental investigations, the gradual growth of flank wear for multilayer coated insert indicates steady machining without any premature tool failure by chipping or fracturing. Abrasion is found to be the dominant wear mechanisms in hard turning. Tool life of multilayer coated carbide inserts has been found to be 31 minute and machining cost per part is Rs.3.64 only under parametric conditions chosen i.e. v = 90 m/min, f = 0.05 mm/rev and d = 0.5 mm. The mathematical model shows high determination coefficient, R2 (99% and fits the actual data well. The predicted flank wear has been found to lie very close to the experimental value at 95% confidence level. This shows the potential and effectiveness of multilayer coated carbide insert used in hard turning applications.

  1. Robot based deposition of WC-Co HVOF coatings on HSS cutting tools as a substitution for solid cemented carbide cutting tools

    Science.gov (United States)

    Tillmann, W.; Schaak, C.; Biermann, D.; Aßmuth, R.; Goeke, S.

    2017-03-01

    Cemented carbide (hard metal) cutting tools are the first choice to machine hard materials or to conduct high performance cutting processes. Main advantages of cemented carbide cutting tools are their high wear resistance (hardness) and good high temperature strength. In contrast, cemented carbide cutting tools are characterized by a low toughness and generate higher production costs, especially due to limited resources. Usually, cemented carbide cutting tools are produced by means of powder metallurgical processes. Compared to conventional manufacturing routes, these processes are more expensive and only a limited number of geometries can be realized. Furthermore, post-processing and preparing the cutting edges in order to achieve high performance tools is often required. In the present paper, an alternative method to substitute solid cemented carbide cutting tools is presented. Cutting tools made of conventional high speed steels (HSS) were coated with thick WC-Co (88/12) layers by means of thermal spraying (HVOF). The challenge is to obtain a dense, homogenous, and near-net-shape coating on the flanks and the cutting edge. For this purpose, different coating strategies were realized using an industrial robot. The coating properties were subsequently investigated. After this initial step, the surfaces of the cutting tools were ground and selected cutting edges were prepared by means of wet abrasive jet machining to achieve a smooth and round micro shape. Machining tests were conducted with these coated, ground and prepared cutting tools. The occurring wear phenomena were analyzed and compared to conventional HSS cutting tools. Overall, the results of the experiments proved that the coating withstands mechanical stresses during machining. In the conducted experiments, the coated cutting tools showed less wear than conventional HSS cutting tools. With respect to the initial wear resistance, additional benefits can be obtained by preparing the cutting edge by means

  2. Engineered Polymer Composites Through Electrospun Nanofiber Coating of Fiber Tows

    Science.gov (United States)

    Kohlman, Lee W.; Bakis, Charles; Williams, Tiffany S.; Johnston, James C.; Kuczmarski, Maria A.; Roberts, Gary D.

    2014-01-01

    Composite materials offer significant weight savings in many aerospace applications. The toughness of the interface of fibers crossing at different angles often determines failure of composite components. A method for toughening the interface in fabric and filament wound components using directly electrospun thermoplastic nanofiber on carbon fiber tow is presented. The method was first demonstrated with limited trials, and then was scaled up to a continuous lab scale process. Filament wound tubes were fabricated and tested using unmodified baseline towpreg material and nanofiber coated towpreg.

  3. Microstructural, phase evolution and corrosion properties of silicon carbide reinforced pulse electrodeposited nickel–tungsten composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Swarnima; Sribalaji, M. [Materials Science and Engineering, Indian Institute of Technology Patna, Navin Government Polytechnic Campus, Patliputra Colony, Patna, Bihar 800013 (India); Wasekar, Nitin P.; Joshi, Srikant; Sundararajan, G. [International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI) Hyderabad, Balapur P.O., Hyderabad, Andhra Pradesh 500005 (India); Singh, Raghuvir [CSIR-National Metallurgical Laboratory, Jamshedpur, Jharkhand 831007 (India); Keshri, Anup Kumar, E-mail: anup@iitp.ac.in [Materials Science and Engineering, Indian Institute of Technology Patna, Navin Government Polytechnic Campus, Patliputra Colony, Patna, Bihar 800013 (India)

    2016-02-28

    Graphical abstract: - Highlights: • Pulse electrodeposited Ni–W–SiC coating has been synthesized successfully. • Dome to turtle like structure has been observed on addition of SiC in Ni–W coating. • Formation of W(Ni) solid solution was observed on adding 5 g/l SiC in Ni–W coating. • Corrosion resistance improved for Ni–W–5 g/l SiC coating. • Texture formation and continuous barrier layer enhanced the corrosion resistance. - Abstract: Silicon carbide (SiC) reinforced nickel–tungsten (Ni–W) coatings were successfully fabricated on steel substrate by pulse electrodeposition method (PED) and the amount of SiC was varied as 0 g/l, 2 g/l, and 5 g/l in Ni–W coating. Effect of subsequent addition of SiC on microstructures, phases and on corrosion property of the coating was investigated. Field emission scanning electron microscopy (FE-SEM) image of the surface morphology of the coating showed the transformation from the dome like structure to turtle shell like structure. X-ray diffraction (XRD) of Ni–W–5 g/l SiC showed the disappearance of (220) plane of Ni(W), peak splitting in major peak of Ni(W) and formation of distinct peak of W(Ni) solid solution. Absence of (220) plane, peak splitting and presence of W(Ni) solid solution was explained by the high resolution transmission electron microscopy (HR-TEM) images. Tafel polarization plot was used to study the corrosion property of the coatings in 0.5 M NaCl solution. Ni–W–5 g/l SiC coating was showed higher corrosion resistance (i.e. ∼21% increase in corrosion potential, E{sub corr}) compared to Ni–W coating. Two simultaneous phenomena have been identified for the enhanced corrosion resistance of Ni–W–5 g/l SiC coating. (a) Presence of crystallographic texture (b) formation of continuous double barrier layer of NiWO{sub 4} and SiO{sub 2}.

  4. Continuous fiber reinforced mesh bond coat for environmental barrier coating system

    Science.gov (United States)

    Zhang, James; Das, Rupak; Roberts III, Herbert Chidsey; Delvaux, John McConnell

    2017-09-26

    A gas turbine blade may have a bond coat applied to its surface. A porous substrate may be applied to the bond layer and one or more protective layers may be applied to the bond layer such that the fiber mesh is embedded between the bond layer and the protective layer to prevent creep.

  5. Nanodiamond-polymer composite fibers and coatings.

    Science.gov (United States)

    Behler, Kristopher D; Stravato, Antonella; Mochalin, Vadym; Korneva, Guzeliya; Yushin, Gleb; Gogotsi, Yury

    2009-02-24

    While nanocrystalline diamond is quickly becoming one of the most widely studied nanomaterials, achieving a large fraction of diamond nanoparticles in a polymer coating has been an unresolved problem. In this work, polymer nano- and microfibers containing high loadings of 5 nm diamond particles (up to 80 wt % in polyacrylonitrile and 40% in polyamide 11) have been demonstrated using electrospun nanofibers as a delivery vehicle. The electrospun nanofibers with a high load of nanodiamond in the polymers were fused into thin transparent films, which had high mechanical properties; an improvement of 4 times for the Young's modulus and 2 times for the hardness was observed already at 20% nanodiamond in polyamide 11. These films can provide UV protection and scratch resistance to a variety of surfaces, especially in applications where a combination of mechanical, thermal, and dielectric properties is required.

  6. Antibody Immobilization on Conductive Polymer Coated Nonwoven Fibers for Biosensors

    OpenAIRE

    McGraw, Shannon K.; Anderson, Michael J.; Alocilja, Evangelyn C.; Marek, Patrick J.; Kris J. SENECAL; Andre G. SENECAL

    2011-01-01

    This work is being performed to develop rapid and novel electrochemical biosensors for foodborne pathogen detection. This research focuses on electrotextile platforms to perform both capture and sensing functions in a single component. The biosensor uses nonwoven fiber membranes coated with conductive polymer and functionalized with antibodies for biological capture. This study examines three methods for antibody immobilization: passive adsorption, glutaraldehyde cross-linking, and EDC/Sulfo-...

  7. Textile fibers coated with carbon nanotubes for smart clothing applications

    Science.gov (United States)

    Lepak, Sandra; Lalek, Bartłomiej; Janczak, Daniel; Dybowska-Sarapuk, Łucja; Krzemiński, Jakub; Jakubowska, Małgorzata; Łekawa-Raus, Agnieszka

    2017-08-01

    Carbon nanomaterials: graphene, fullerenes and in particular carbon nanotubes (CNTs) are extremely interesting and extraordinary materials. It is mostly thanks to theirs unusual electrical and mechanical properties. Carbon nanotubes are increasingly examined to enable its usage in many fields of science and technology. It has been reported that there is a high possibility to use CNTs in electronics, optics, material engineering, biology or medicine. However, this material still interests and inspire scientists around the world and the list of different CNTs applications is constantly expanding. In this paper we are presenting a study on the possibility of application carbon nanotubes as a textile fiber coating for smart clothing applications. Various suspensions and pastes containing CNTs have been prepared as a possible coating onto textile fibers. Different application techniques have also been tested. Those techniques included painting with nanotube suspension, spray coating of suspensions and immersion. Following textile fibers were subject to tests: cotton, silk, polyester, polyamide and wool. Obtained composites materials were then characterized electrically by measuring the electrical resistance.

  8. Coated carbide drill performance under soluble coconut oil lubricant and nanoparticle enhanced MQL in drilling AISI P20

    Science.gov (United States)

    Jamil, N. A. M.; Azmi, A. I.; Fairuz, M. A.

    2016-02-01

    This research experimentally investigates the performance of a TiAlN coated carbide drill bit in drilling AISI P20 through two different kinds of lubricants, namely; soluble coconut oil (SCO) and nanoparticle-enhanced coconut oil (NECO) under minimum quantity lubrication system. The tool life and tool wear mechanism were studied using various cutting speeds of 50, 100 and 150 m/min with a constant feed of 0.01 mm/rev. Since the flank wear land was not regular along the cutting edge, the average flank wear (VB) was measured at several points using image analysis software. The drills were inspected using a scanning electron microscope to further elucidate the wear mechanism. The result indicates that drilling with the nanoparticle- enhanced lubricant was better in resisting the wear and improving the drill life to some extent

  9. Laser cladding of Inconel 625-based composite coatings reinforced by porous chromium carbide particles

    Science.gov (United States)

    Janicki, Damian

    2017-09-01

    Inconel 625/Cr3C2 composite coatings were produced via a laser cladding process using Cr3C2 reinforcing particles presenting an open porosity of about 60%. A laser cladding system used consisted of a direct diode laser with a rectangular beam spot and the top-hat beam profile, and an off-axis powder injection nozzle. The microstructural characteristics of the coatings was investigated with the use of scanning electron microscopy and X-ray diffraction. A complete infiltration of the porous structure of Cr3C2 reinforcing particles and low degree of their dissolution have been achieved in a very narrow range of processing parameters. Crack-free composite coatings having a uniform distribution of the Cr3C2 particles and their fraction up to 36 vol% were produced. Comparative erosion tests between the Inconel 625/Cr3C2 composite coatings and the metallic Inconel 625 coatings were performed following the ASTM G 76 standard test method. It was found that the composite coatings have a significantly higher erosion resistance to that of metallic coatings for both 30° and 90° impingement angles. Additionally, the erosion performances of composite coatings were similar for both the normal and oblique impact conditions. The erosive wear behaviour of composite coatings is discussed and related to the unique microstructure of these coatings.

  10. Carbon Fiber Reinforced/Silicon Carbide Turbine Blisk Testing in the SIMPLEX Turbopump

    Science.gov (United States)

    Genge, Gary G.; Marsh, Matthew W.

    1999-01-01

    A program designed to implement a ceramic matrix composite integrally bladed disk (blisk) into rocket engine style turbomachinery has successfully completed testing. The Marshall Space Flight Center (MSFC) program, utilizing the MSFC turbomachinery design, analysis, and testing capabilities along with materials development capabilities from both Glenn Research Center (GRC) and MSFC, has tested two carbon fiber reinforced silicon carbide blisks in the Simplex Turbopump at MSFC's Test Stand 500. One blisk contained a polar woven fiber preform, while the second blisk tested utilized a quasi-isotropic preform. Vhile earlier papers have chronicled the program's design, material testing, and torque testing efforts, this paper focuses on the testing of the blisks in the Simplex turbopump. Emphasis will be placed on the actual condition of the blisks before and after the testing test program design methodology, and conclusions that can be drawn from the test data and blisk final conditions. The program performed three separate test series. The first series was needed to validate that the Simplex turbopump was correctly re-built following a major incident to the turbopump. The turbopump had two major differences from the original design. The most obvious difference was the sleeve required throughout the bore of the main housing. The second major difference was modifications to the pump diffuser to improve performance. Several areas were burnt during the incident and were either repaired by weld repair (pump inlet housing) or simply smoothed out (turbine nozzle discharge). The test series was designed to weed out any turbopump design and manufacturing flaws or fatigue issues prior to putting the C/SiC blisks into it. The second and third series were the C/SiC blisk test series. The primary goal of these series was to expose the blisks to as much fatigue causing dynamic stress as possible to examine the material's capability. Initially, the test plan was to put equal time on

  11. Mechanical Properties and Corrosion Resistance of HVOF Sprayed Coatings Using Nanostructured Carbide Powders

    Directory of Open Access Journals (Sweden)

    Żórawski W.

    2016-12-01

    Full Text Available Nanostructured and composite WC-12Co coatings were prepared by means of the supersonic spray process (HVOF. The microstructure and composition of WC-12Co nanostructured powder were analyzed by scanning electron microscope (SEM and transmission electron microscope (TEM. Investigations revealed nano grains of WC with the size in the range of 50-500 nm. The nanostructured sprayed coating was analysed by SEM and phase composition was investigated by X-ray diffractometer (XRD. A denser coating structure with higher hardness was observed compared to conventional coating with a small amount of W2C, WC1−x, W and some amorphous phase. Young’s modulus and hardness were determined by depth sensing indentation in HVOF sprayed WC-12Co nanostructured coatings. Results were compared to conventional coatings and the relevance of the nanostructure was analyzed. An indentation size effect was observed on the polished surface and cross-section of both coatings. Data provided by indentation tests at maximum load allow to estimate hardness and elastic modulus. Enhanced nanomechanical properties of conventional coating in comparison to nanostructured one were observed. Nanostructured coatings WC-12Co (N revealed significantly better corrosion resistance.

  12. Antibody Immobilization on Conductive Polymer Coated Nonwoven Fibers for Biosensors

    Directory of Open Access Journals (Sweden)

    Shannon K. MCGRAW

    2011-12-01

    Full Text Available This work is being performed to develop rapid and novel electrochemical biosensors for foodborne pathogen detection. This research focuses on electrotextile platforms to perform both capture and sensing functions in a single component. The biosensor uses nonwoven fiber membranes coated with conductive polymer and functionalized with antibodies for biological capture. This study examines three methods for antibody immobilization: passive adsorption, glutaraldehyde cross-linking, and EDC/Sulfo-NHS cross-linking. Antibodies are immobilized onto the conductive fiber surfaces for the specific capture of a target pathogen. The immobilization and capture capabilities of each method are analyzed through the use of two different fluorescent reporters: FITC and PicoGreen DNA stain. Fluorescence is measured using a fluorescent plate reader and then imaged using a fluorescent microscope. The effect of a blocking agent on specificity is also evaluated. It is found that glutaraldehyde with blocking is the best immobilization method with PicoGreen being the best fluorescent reporter.

  13. Formation and antifouling properties of amphiphilic coatings on polypropylene fibers.

    Science.gov (United States)

    Goli, Kiran K; Rojas, Orlando J; Genzer, Jan

    2012-11-12

    We describe the formation of amphiphilic polymeric assemblies via a three-step functionalization process applied to polypropylene (PP) nonwovens and to reference hydrophobic self-assembled n-octadecyltrichlorosilane (ODTS) monolayer surfaces. In the first step, denatured proteins (lysozyme or fibrinogen) are adsorbed onto the hydrophobic PP or the ODTS surfaces, followed by cross-linking with glutaraldehyde in the presence of sodium borohydride (NaBH(4)). The hydroxyl and amine functional groups of the proteins permit the attachment of initiator molecules, from which poly (2-hydroxyethyl methacrylate) (PHEMA) polymer grafts are grown directly through "grafting from" atom transfer radical polymerization. The terminal hydroxyls of HEMA's pendent groups are modified with fluorinating moieties of different chain lengths, resulting in amphiphilic brushes. A palette of analytical tools, including ellipsometry, contact angle goniometry, Fourier transform infrared spectroscopy in the attenuated total reflection mode, and X-ray photoelectron spectroscopy is employed to determine the changes in physicochemical properties of the functionalized surfaces after each modification step. Antifouling properties of the resultant amphiphilic coatings on PP are analyzed by following the adsorption of fluorescein isothiocyanate-labeled bovine serum albumin as a model fouling protein. Our results suggest that amphiphilic coatings suppress significantly adsorption of proteins as compared with PP fibers or PP surfaces coated with PHEMA brushes. The type of fluorinated chain grafted to PHEMA allows modulation of the surface composition of the topmost layer of the amphiphilic coating and its antifouling capability.

  14. Investigation on the formation of tungsten carbide in tungsten-containing diamond like carbon coatings

    NARCIS (Netherlands)

    Strondl, C.; Carvalho, N.M.; Hosson, J.Th.M. De; Kolk, G.J. van der

    2003-01-01

    A series of tungsten-containing diamond-like carbon (Me-DLC) coatings have been produced by unbalanced magnetron sputtering using a Hauzer HTC-1000 production PVD system. Sputtering from WC targets has been used to form W-C:H coatings. The metal to carbon ratio has been varied to study changes in

  15. ELECTRICAL FURNACE FOR PRODUCING CARBIDE COATINGS USING THE THERMOREACTIVE DEPOSITION/DIFFUSION TECHNIQUE

    Directory of Open Access Journals (Sweden)

    FABIO CASTILLEJO

    2011-01-01

    the presence of VC and NbC, and as MEB results clearly show, the formation of regular thickness coatings. The results obtained allow for assessing that the designed and built furnace fulfills the requirements of the TRD technique for obtaining different types of hard coatings.

  16. The wear of the carbide cutting tools coated with TiN during the milling of Inconel 738

    Science.gov (United States)

    Sebhi, A.; Douib, N.

    2017-02-01

    The machining of superalloy parts still an area not very clear in mechanical manufacturing. It is found to be used in particular areas such as gas turbine, rocket engine, space ships, nuclear reactors, and pumps. The machining of Inconel 738 superalloy has been studied in this context, with the aim to understand the wear behavior with carbide inserts coated with TiN and in order to optimize the cutting parameters before starting the production. The wear behavior of the inserts during the machining process of a very tough austenitic superalloy is unclear, and requires a series of well determined tests. The life of the insert under high stress such as pressure, cutting speed, high temperature, in a hostile zone and in contact with a very tough and harder material is determined. The generated process of wear is very complex, because it is followed by physico-chemical phenomenon appearing on the contact surfaces between the active part of the tool and workpiece.The lifetime of machine tools often depends on the tribological characteristics of the material couples (cutting tool / material to be machined). It has been shown that the most influential parameter is the coating, then comes the sliding speed. A relationship between the wear VB and the roughness Ra is proposed to collect information on the cutting edge and the quality of the tool by measuring the roughness. For wear measurement, an indirect method is used in coupling a Touptek photonics camera to capture and Ttoupview analysis software.

  17. A Comparative Study of Natural Fiber and Glass Fiber Fabrics Properties with Metal or Oxide Coatings

    Science.gov (United States)

    Lusis, Andrej; Pentjuss, Evalds; Bajars, Gunars; Sidorovicha, Uljana; Strazds, Guntis

    2015-03-01

    Rapidly growing global demand for technical textiles industries is stimulated to develop new materials based on hybrid materials (yarns, fabrics) made from natural and glass fibres. The influence of moisture on the electrical properties of metal and metal oxide coated bast (flax, hemp) fibre and glass fibre fabrics are studied by electrical impedance spectroscopy and thermogravimetry. The bast fibre and glass fiber fabrics are characterized with electrical sheet resistance. The method for description of electrical sheet resistance of the metal and metal oxide coated technical textile is discussed. The method can be used by designers to estimate the influence of moisture on technical data of new metal coated hybrid technical textile materials and products.

  18. New graphene fiber coating for volatile organic compounds analysis.

    Science.gov (United States)

    Zhang, GuoJuan; Guo, XiaoXi; Wang, ShuLing; Wang, XueLan; Zhou, YanPing; Xu, Hui

    2014-10-15

    In the work, a novel graphene-based solid phase microextraction-gas chromatography/mass spectrometry method was developed for the analysis of trace amount of volatile organic compounds in human exhaled breath vapor. The graphene fiber coating was prepared by a one-step hydrothermal reduction reaction. The fiber with porous and wrinkled structure exhibited excellent extraction efficiency toward eight studied volatile organic compounds (two n-alkanes, five n-aldehydes and one aromatic compound). Meanwhile, remarkable thermal and mechanical stability, long lifespan and low cost were also obtained for the fiber. Under the optimal conditions, the developed method provided low limits of detection (1.0-4.5ngL(-1)), satisfactory reproducibility (3.8-13.8%) and acceptable recoveries (93-122%). The method was applied successfully to the analysis of breath samples of lung cancer patients and healthy individuals. The unique advantage of this approach includes simple setup, non-invasive analysis, cost-efficient and sufficient sensitivity. The proposed method supply us a new possibility to monitor volatile organic compounds in human exhaled breath samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Removing nickel from nickel-coated carbon fibers

    Science.gov (United States)

    Hardianto, A.; Hertleer, C.; De Mey, G.; Van Langenhove, L.

    2017-10-01

    Conductive fibers/yarns are one of the most important materials for smart textiles because of their electrically conductive functionality combined with flexibility and light weight. They can be applied in many fields such as the medical sector, electronics, sensors and even as thermoelectric generators. Temperature sensors, for example, can be made using the thermocouple or thermopile principle which usually uses two different metal wires that can produce a temperature-dependent voltage. However, if metal wires are inserted into a textile structure, they will decrease the flexibility properties of the textile product. Nickel-coated Carbon Fiber (NiCF), a conductive textile yarn, has a potential use as a textile-based thermopile if we can create an alternating region of carbon and nickel along the fiber which in turn it can be used for substituting the metallic thermopile. The idea was to remove nickel from NiCF in order to obtain a yarn that contains alternating zones of carbon and nickel. Due to no literature reporting on how to remove nickel from NiCF, in this paper we investigated some chemicals to remove nickel from NiCF.

  20. The effects of applying silicon carbide coating on core reactivity of pebble-bed HTR in water ingress accident

    Energy Technology Data Exchange (ETDEWEB)

    Zuhair, S.; Setiadipura, Topan [National Nuclear Energy Agency of Indonesia, Serpong Tagerang Selatan (Indonesia). Center for Nuclear Reactor Technology and Safety; Su' ud, Zaki [Bandung Institute of Technology (Indonesia). Dept. of Physics

    2017-03-15

    Graphite is used as the moderator, fuel barrier material, and core structure in High Temperature Reactors (HTRs). However, despite its good thermal and mechanical properties below the radiation and high temperatures, it cannot avoid corrosion as a consequence of an accident of water/air ingress. Degradation of graphite as a main HTR material and the formation of dangerous CO gas is a serious problem in HTR safety. One of the several steps that can be adopted to avoid or prevent the corrosion of graphite by the water/air ingress is the application of a thin layer of silicon carbide (SiC) on the surface of the fuel element. This study investigates the effect of applying SiC coating on the fuel surfaces of pebble-bed HTR in water ingress accident from the reactivity points of view. A series of reactivity calculations were done with the Monte Carlo transport code MCNPX and continuous energy nuclear data library ENDF/B-VII at temperature of 1200 K. Three options of UO{sub 2}, PuO{sub 2}, and ThO{sub 2}/UO{sub 2} fuel kernel were considered to obtain the inter comparison of the core reactivity of pebble-bed HTR in conditions of water/air ingress accident. The calculation results indicated that the UO{sub 2}-fueled pebble-bed HTR reactivity was slightly reduced and relatively more decreased when the thickness of the SiC coating increased. The reactivity characteristic of ThO{sub 2}/UO{sub 2}-fueled pebble-bed HTR showed a similar trend to that of UO{sub 2}, but did not show reactivity peak caused by water ingress. In contrast with UO{sub 2}- and ThO{sub 2}-fueled pebble-bed HTR, although the reactivity of PuO{sub 2}-fueled pebble-bed HTR was the lowest, its characteristics showed a very high reactivity peak (0.33 Δk/k) and this introduction of positive reactivity is difficult to control. SiC coating on the surface of the plutonium fuel pebble has no significant impact. From the comparison between reactivity characteristics of uranium, thorium and plutonium cores with 0

  1. Effect of Coating on the Strain Transfer of Optical Fiber Sensors

    Directory of Open Access Journals (Sweden)

    Chih-Ying Huang

    2011-07-01

    Full Text Available Optical fiber strain sensors with light weight, small dimensions and immunity to electromagnetic interference are widely used in structural health monitoring devices. As a sensor, it is expected that the strains between the optical fiber and host structure are the same. However, due to the shear deformation of the protective coating, the optical fiber strain is different from that of host structure. To improve the measurement accuracy, the strain measured by the optical fiber needs to be modified to reflect the influence of the coating. In this investigation, a theoretical model of the strain transferred from the host material to the optical fiber is developed to evaluate the interaction between the host material and coating. The theoretical predictions are validated with a numerical analysis using the finite element method. Experimental tests are performed to reveal the differential strains between the optical fiber strain sensor and test specimen. The Mach-Zehnder interferometric type fiber-optic sensor is adopted to measure the strain. Experimental results show that the strain measured at the optical fiber is lower than the true strain in the test specimen. The percentage of strain in the test specimen actually transferred to the optical fiber is dependent on the bonded length of the optical fiber and the protective coating. The general trend of the strain transformation obtained from both experimental tests and theoretical predictions shows that the longer the bonded length and the stiffer the coating the more strain is transferred to the optical fiber.

  2. Effect of coating on the strain transfer of optical fiber sensors.

    Science.gov (United States)

    Her, Shiuh-Chuan; Huang, Chih-Ying

    2011-01-01

    Optical fiber strain sensors with light weight, small dimensions and immunity to electromagnetic interference are widely used in structural health monitoring devices. As a sensor, it is expected that the strains between the optical fiber and host structure are the same. However, due to the shear deformation of the protective coating, the optical fiber strain is different from that of host structure. To improve the measurement accuracy, the strain measured by the optical fiber needs to be modified to reflect the influence of the coating. In this investigation, a theoretical model of the strain transferred from the host material to the optical fiber is developed to evaluate the interaction between the host material and coating. The theoretical predictions are validated with a numerical analysis using the finite element method. Experimental tests are performed to reveal the differential strains between the optical fiber strain sensor and test specimen. The Mach-Zehnder interferometric type fiber-optic sensor is adopted to measure the strain. Experimental results show that the strain measured at the optical fiber is lower than the true strain in the test specimen. The percentage of strain in the test specimen actually transferred to the optical fiber is dependent on the bonded length of the optical fiber and the protective coating. The general trend of the strain transformation obtained from both experimental tests and theoretical predictions shows that the longer the bonded length and the stiffer the coating the more strain is transferred to the optical fiber.

  3. Studies on Mechanical Behaviour of Aluminium/Nickel Coated Silicon Carbide Reinforced Functionally Graded Composite

    Directory of Open Access Journals (Sweden)

    A. Mohandas

    2017-06-01

    Full Text Available The aim of the work is to fabricate functionally graded aluminium (Al-Si6Cu/ nickel coated SiC metal matrix composite using centrifugal casting route. SiC particles (53-80 µm were coated with nickel using electroless coating technique to enhance the wettability with aluminium matrix. Several attempts were made to coat nickel on SiC by varying the process temperature (65 °C, 75 °C, and 85 °C to obtain a uniform coating. Silicon particles coated with nickel were characterised using EDS enabled Field Emission Scanning Electron Microscope and it was found that the maximum nickel coating on SiC occurred at a process temperature of 75°C. This nickel coated SiC particles were used as the reinforcement for the manufacture of functionally graded metal matrix composite and a cast specimen of dimensions 150×90×15 mm was obtained. To ensure the graded properties in the fabricated composites, microstructure (at a distance of 1, 7 and 14 mm and hardness (at a distance of 1, 3, 7, 10 and 14 mm from outer periphery taken in the radial direction was analysed using Zeiss Axiovert metallurgical microscope and Vickers micro hardness tester respectively. The microstructure reveals presence of more SiC particles at the outer periphery compared to inner periphery and the hardness test shows that the hardness also decreased from outer periphery (90 HV to inner periphery (78 HV.Tensile strength of specimen from outer zone (1-7mm and inner zone (8-14 mm of casting was also tested and found out a value of 153.3 Mpa and 123.3 Mpa for the outer zone and inner zone respectively. An important observation made was that the outer periphery of casting was particle rich and the inner periphery was particle deficient because of centrifugal force and variation in density between aluminium matrix and reinforcement. Functionally graded Al/SiC metal matrix composite could be extensively used in automotive industry especially in the manufacture of liners and brake drums.

  4. Absorbing Property of Multi-layered Short Carbon Fiber Absorbing Coating

    OpenAIRE

    Liu, Zhaohui; Tao, Rui; Ban, Guodong; Luo, Ping

    2017-01-01

    The radar absorbing coating was prepared with short carbon fiber asabsorbent and waterborne polyurethane (WPU) as matrix resin. The coating’s absorbing property was tested with vectornetwork analyzer, using aramid honeycomb as air layer which was matched withcarbon fiber coating. The results demonstrate that the single-layered carbonfiber absorbing coating presented relatively poor absorbing property when thelayer was thin, and the performance was slightly improved after the matched airlayer ...

  5. Improved coating for silica fiber based ceramic Reusable Surface Insulation (CRSI)

    Science.gov (United States)

    Ormiston, T. J.

    1974-01-01

    A series of coatings was developed for the space shuttle type silica fiber insulation system and characterized for optical and physical properties. Reentry simulation tests were run using a radiant panel and also using a hypersonic plasma arc. The coatings produced had improved physical and optical properties as well as greater reuse capability over the GE version of the JSC-0042 coating.

  6. Room-temperature aqueous plasma electrolyzing Al2O3 nano-coating on carbon fiber

    Science.gov (United States)

    Zhang, Yuping; Meng, Yang; Shen, Yonghua; Chen, Weiwei; Cheng, Huanwu; Wang, Lu

    2017-10-01

    A novel room-temperature aqueous plasma electrolysis technique has been developed in order to prepared Al2O3 nano-coating on each fiber within a carbon fiber bundle. The microstructure and formation mechanism of the Al2O3 nano-coating were systematically investigated. The oxidation resistance and tensile strength of the Al2O3-coated carbon fiber was measured at elevated temperatures. It showed that the dense Al2O3 nano-coating was relatively uniformly deposited with 80-120 nm in thickness. The Al2O3 nano-coating effectively protected the carbon fiber, evidenced by the slower oxidation rate and significant increase of the burn-out temperature from 800 °C to 950 °C. Although the bare carbon fiber remained ∼25 wt.% after oxidation at 700 °C for 20 min, a full destruction was observed, evidenced by the ∼0 GPa of the tensile strength, compared to ∼1.3 GPa of the Al2O3-coated carbon fiber due to the effective protection from the Al2O3 nano-coating. The formation mechanism of the Al2O3 nano-coating on carbon fiber was schematically established mainly based on the physic-chemical effect in the cathodic plasma arc zone.

  7. Adhesion of Y2O3-Al2O3-SiO2 coatings to typical aerospace substrates

    Energy Technology Data Exchange (ETDEWEB)

    Marraco-Borderas, C.; Nistal, A.; Garcia, E.; Sainz, M.A.; Martin de la Escalera, F.; Essa, Y.; Miranzo, P.

    2016-07-01

    High performance lightweight materials are required in the aerospace industry. Silicon carbide, carbon fiber reinforced carbon and slicon carbide composites comply with those requirements but they suffer from oxidation at the high temperature of the service conditions. One of the more effective approaches to prevent this problem is the use of protecting ceramic coatings, where the good adhesion between substrates and coatings are paramount to guarantee the optimal protection performance. In the present work, the adhesion between those substrates and glass coatings of the Y2O3-Al2O3-SiO2 system processed by oxyacetylene flame spraying is analyzed. Increasing load scratch tests are employed for determining the failure type, maximum load and their relation with the elastic and mechanical properties of the coatings. The results points to the good adhesion of the coatings to silicon carbide and carbon fibre reinforced silicon carbide while the carbon fiber reinforced carbon is not a suitable material to be coated. (Author)

  8. Stress transfer in microdroplet tensile test: PVC-coated and uncoated Kevlar-29 single fiber

    Science.gov (United States)

    Zhenkun, Lei; Quan, Wang; Yilan, Kang; Wei, Qiu; Xuemin, Pan

    2010-11-01

    The single fiber/microdroplet tensile test is applied for evaluating the interfacial mechanics between a fiber and a resin substrate. It is used to investigate the influence of a polymer coating on a Kevlar-29 fiber surface, specifically the stress transfer between the fiber and epoxy resin in a microdroplet. Unlike usual tests, this new test ensures a symmetrical axial stress on the embedded fiber and reduces the stress singularity that appears at the embedded fiber entry. Using a homemade loading device, symmetrical tensile tests are performed on a Kevlar-29 fiber with or without polyvinylchloride (PVC) coating, the surface of which is in contact with two epoxy resin microdroplets during curing. Raman spectra on the embedded fiber are recorded by micro-Raman Spectroscopy under different strain levels. Then they are transformed to the distributions of fiber axis stress based on the relationship between stress and Raman shift. The Raman results reveal that the fiber axial stresses increase with the applied loads, and the antisymmetric interfacial shear stresses, obtained by a straightforward balance of shear-to-axial forces argument, lead to the appearance of shear stress concentrations at a distance to the embedded fiber entry. The load is transferred from the outer fiber to the embedded fiber in the epoxy microdroplet. As is observed by scanning electronic microscopy (SEM), the existence of a flexible polymer coating on the fiber surface reduces the stress transfer efficiency.

  9. Carbon nanotube-coated solid-phase microextraction metal fiber based on sol-gel technique.

    Science.gov (United States)

    Jiang, Ruifen; Zhu, Fang; Luan, Tiangang; Tong, Yexiang; Liu, Hong; Ouyang, Gangfeng; Pawliszyn, Janusz

    2009-05-29

    A novel carbon nanotube (CNT)-coated solid-phase microextraction fiber was prepared based on sol-gel technique. Commonly used fragile fused silica fiber was replaced with stainless steel wire, which made the fiber unbreakable. An approach was also proposed for batch producing, and good reproducibilities for fiber to fiber and between fibers were achieved. Experiments showed that the sol-gel-CNT fiber exhibited high thermal stability to resist 350 degrees C and excellent solvent durability in methanol and acetonitrile. Compared to commercial polydimethylsiloxane (PDMS) fiber, the sol-gel-CNT fiber represented significantly improved extraction efficiencies for both polar (phenols) and non-polar (benzene, toluene, ethylbenzene, and o-xylene) compounds. Meanwhile, no replacement effect, low carry-over and wide linear range demonstrated that the newly prepared sol-gel-CNT coating has liquid properties, which allow a relatively easy quantification procedure. Moreover, the characterization of the sol-gel-CNT coating was also evaluated with McReynold probe solutes. The results showed that the coating has better affinity for all the five types of solutes compared to commercial 7microm PDMS fiber, which suggested that the coating has the potential to be developed as GC stationary phase.

  10. Effect of cutting parameters on sustainable machining performance of coated carbide tool in dry turning process of stainless steel 316

    Science.gov (United States)

    Bagaber, Salem A.; Yusoff, Ahmed Razlan

    2017-04-01

    The manufacturing industry aims to produce many products of high quality with relatively less cost and time. Different cutting parameters affect the machining performance of surface roughness, cutting force, and material removal rate. Nevertheless, a few studies reported on the effects of sustainable factors such as power consumed, cycle time during machining, and tool life on the dry turning of AISI 316. The present study aims to evaluate the machining performance of coated carbide in the machining of hard steel AISI 316 under the dry turning process. The influence of cutting parameters of cutting speed, feed rate, and depth of cut with their five (5) levels is established by a central composite design. Highly significant parameters were determined by analysis of variance (ANOVA), and the main effects of power consumed and time during machining, surface roughness, and tool wear were observed. Results showed that the cutting speed was proportional to power consumption and tool wear. Meanwhile, insignificant to surface roughness, feed rate most significantly affected surface roughness and power consumption followed by depth of cut.

  11. On the melt infiltration of copper coated silicon carbide with an aluminium alloy

    Science.gov (United States)

    Asthana, R.; Rohatgi, P. K.

    1992-01-01

    Pressure-assisted infiltration of porous compacts of Cu coated and uncoated single crystals of platelet shaped alpha (hexagonal) SiC was used to study infiltration dynamics and particulate wettability with a 2014 Al alloy. The infiltration lengths were measured for a range of experimental variables which included infiltration pressure, infiltration time, and SiC size. A threshold pressure (P(th)) for flow initiation through compacts was identified from an analysis of infiltration data; P(th) decreased while penetration lengths increased with increasing SiC size (more fundamentally, due to changes in interparticle pore size) and with increasing infiltration times. Cu coated SiC led to lower P(th) and 60-80 percent larger penetration lengths compared to uncoated SiC under identical processing conditions.

  12. Effect of Particle and Carbide Grain Sizes on a HVOAF WC-Co-Cr Coating for the Future Application on Internal Surfaces: Microstructure and Wear

    Science.gov (United States)

    Pulsford, J.; Kamnis, S.; Murray, J.; Bai, M.; Hussain, T.

    2018-01-01

    The use of nanoscale WC grain or finer feedstock particles is a possible method of improving the performance of WC-Co-Cr coatings. Finer powders are being pursued for the development of coating internal surfaces, as less thermal energy is required to melt the finer powder compared to coarse powders, permitting spraying at smaller standoff distances. Three WC-10Co-4Cr coatings, with two different powder particle sizes and two different carbide grain sizes, were sprayed using a high velocity oxy-air fuel (HVOAF) thermal spray system developed by Castolin Eutectic-Monitor Coatings Ltd., UK. Powder and coating microstructures were characterized using XRD and SEM. Fracture toughness and dry sliding wear performance at three loads were investigated using a ball-on-disk tribometer with a WC-Co counterbody. It was found that the finer powder produced the coating with the highest microhardness, but its fracture toughness was reduced due to increased decarburization compared to the other powders. The sprayed nanostructured powder had the lowest microhardness and fracture toughness of all materials tested. Unlubricated sliding wear testing at the lowest load showed the nanostructured coating performed best; however, at the highest load this coating showed the highest specific wear rates with the other two powders performing to a similar, better standard.

  13. Surface Layer States of Worn Uncoated and TiN-Coated WC/Co-Cemented Carbide Cutting Tools after Dry Plain Turning of Carbon Steel

    Directory of Open Access Journals (Sweden)

    Johannes Kümmel

    2013-01-01

    Full Text Available Analyzing wear mechanisms and developments of surface layers in WC/Co-cemented carbide cutting inserts is of great importance for metal-cutting manufacturing. By knowing relevant processes within the surface layers of cutting tools during machining the choice of machining parameters can be influenced to get less wear and high tool life of the cutting tool. Tool wear obviously influences tool life and surface integrity of the workpiece (residual stresses, surface quality, work hardening, etc., so the choice of optimised process parameters is of great relevance. Vapour-deposited coatings on WC/Co-cemented carbide cutting inserts are known to improve machining performance and tool life, but the mechanisms behind these improvements are not fully understood. The interaction between commercial TiN-coated and uncoated WC/Co-cemented carbide cutting inserts and a normalised SAE 1045 steel workpiece was investigated during a dry plain turning operation with constant material removal under varied machining parameters. Tool wear was assessed by light-optical microscopy, scanning electron microscopy (SEM, and EDX analysis. The state of surface layer was investigated by metallographic sectioning. Microstructural changes and material transfer due to tribological processes in the cutting zone were examined by SEM and EDX analyses.

  14. Tribological and Wear Performance of Carbide Tools with TiB2 PVD Coating under Varying Machining Conditions of TiAl6V4 Aerospace Alloy

    Directory of Open Access Journals (Sweden)

    Jose Mario Paiva

    2017-11-01

    Full Text Available Tribological phenomena and tool wear mechanisms during machining of hard-to-cut TiAl6V4 aerospace alloy have been investigated in detail. Since cutting tool wear is directly affected by tribological phenomena occurring between the surfaces of the workpiece and the cutting tool, the performance of the cutting tool is strongly associated with the conditions of the machining process. The present work shows the effect of different machining conditions on the tribological and wear performance of TiB2-coated cutting tools compared to uncoated carbide tools. FEM modeling of the temperature profile on the friction surface was performed for wet machining conditions under varying cutting parameters. Comprehensive characterization of the TiB2 coated vs. uncoated cutting tool wear performance was made using optical 3D imaging, SEM/EDX and XPS methods respectively. The results obtained were linked to the FEM modeling. The studies carried out show that during machining of the TiAl6V4 alloy, the efficiency of the TiB2 coating application for carbide cutting tools strongly depends on cutting conditions. The TiB2 coating is very efficient under roughing at low speeds (with strong buildup edge formation. In contrast, it shows similar wear performance to the uncoated tool under finishing operations at higher cutting speeds when cratering wear predominates.

  15. Preparation and characterization of porous carbon material-coated solid-phase microextraction metal fibers.

    Science.gov (United States)

    Zhu, Fang; Guo, Jiaming; Zeng, Feng; Fu, Ruowen; Wu, Dingcai; Luan, Tiangang; Tong, Yexiang; Lu, Tongbu; Ouyang, Gangfeng

    2010-12-10

    Two kinds of porous carbon materials, including carbon aerogels (CAs), wormhole-like mesoporous carbons (WMCs), were synthesized and used as the coatings of solid-phase microextraction (SPME) fibers. By using stainless steel wire as the supporting core, six types of fibers were prepared with sol-gel method, direct coating method and direct coating plus sol-gel method. Headspace SPME experiments indicated that the extraction efficiencies of the CA fibers are better than those of the WMC fibers, although the surface area of WMCs is much higher than that of CAs. The sol-gel-CA fiber (CA-A) exhibited excellent extraction properties for non-polar compounds (BTEX, benzene, toluene, ethylbenzene, o-xylene), while direct-coated CA fiber (CA-B) presented the best performance in extracting polar compounds (phenols). The two CA fibers showed wide linear ranges, low detection limits (0.008-0.047μgL(-1) for BTEX, 0.15-5.7μgL(-1) for phenols) and good repeatabilities (RSDs less than 4.6% for BTEX, and less than 9.5% for phenols) and satisfying reproducibilities between fibers (RSDs less than 5.2% for BTEX, and less than 9.9% for phenols). These fibers were successfully used for the analysis of water samples from the Pearl River, which demonstrated the applicability of the home-made CA fibers. Copyright © 2010 Elsevier B.V. All rights reserved.

  16. Nanoparticle coated optical fibers for single microbubble generation

    Science.gov (United States)

    Pimentel-Domínguez, Reinher; Hernández-Cordero, Juan

    2011-09-01

    The study of bubbles and bubbly flows is important in various fields such as physics, chemistry, medicine, geophysics, and even the food industry. A wide variety of mechanical and acoustic techniques have been reported for bubble generation. Although a single bubble may be generated with these techniques, controlling the size and the mean lifetime of the bubble remains a difficult task. Most of the optical methods for generation of microbubbles involve high-power pulsed laser sources focused in absorbing media such as liquids or particle solutions. With these techniques, single micron-sized bubbles can be generated with typical mean lifetimes ranging from nano to microseconds. The main problem with these bubbles is their abrupt implosion: this produces a shock wave that can potentially produce damages on the surroundings. These effects have to be carefully controlled in biological applications and in laser surgery, but thus far, not many options are available to effectively control micron-size bubble growth. In this paper, we present a new technique to generate microbubbles in non-absorbing liquids. In contrast to previous reports, the proposed technique uses low-power and a CW radiation from a laser diode. The laser light is guided through an optical fiber whose output end has been coated with nanostructures. Upon immersing the tip of the fiber in ethanol or water, micron-size bubbles can be readily generated. With this technique, bubble growth can be controlled through adjustments on the laser power. We have obtained micron-sized bubbles with mean lifetimes in the range of seconds. Furthermore, the generated bubbles do not implode, as verified with a high-speed camera and flow visualization techniques.

  17. Low-Cost Innovative Hi-Temp Fiber Coating Process for Advanced Ceramic Matrix Composites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — MATECH GSM (MG) proposes 1) to demonstrate a low-cost innovative Hi-Temp Si-doped in-situ BN fiber coating process for advanced ceramic matrix composites in order to...

  18. Coating based Fiber Bragg Grating humidity sensor array

    NARCIS (Netherlands)

    Cheng, L.K.; Boersma, A.; Jansen, T.H.

    2012-01-01

    A coating based FBG humidity sensor is developed for distributed humidity sensing. The sensitivity of the coated FBG is optimized by varying the chemical composition and the thickness of the coating. A sensitivity of ~2 pm/%RH and a rapid response are demonstrated. The composition of the coating can

  19. Preparation of silicon carbide/carbon fiber composites through high-temperature spark plasma sintering

    Directory of Open Access Journals (Sweden)

    Ehsan Ghasali

    2017-12-01

    Full Text Available This study discusses the potentials of spark plasma sintering (SPS integrated with high temperature process that can enable sintering of SiC/Cf composites without any sintering aids. The random distribution of carbon fibers was obtained through mixing composite components in ethanol by using a shaker mill for 10 min. The corresponding sintering process was carried out at 1900 and 2200 °C with 50 MPa pressure applied at maximum temperature. The results showed that 89 ± 0.9 and 97 ± 0.8% of the theoretical density can be obtained for sintering temperatures of 1900 and 2200 °C, respectively. The densification curves were plotted to monitor sintering behavior with punch displacement changes. The appropriate bonding between SiC particles and carbon fibers was detected using FE-SEM for sample which was sintered at 2200 °C. The clear maximum in hardness (2992 ± 33 Vickers, bending strength (427 ± 26 MPa and fracture toughness (4.2 ± 0.3 MPa m1/2 were identified for sample sintered at 2200 °C. XRD investigations supposed that SiC and carbon were the only crystalline phases in both sintered samples.

  20. Highly controlled coating of strontium-doped hydroxyapatite on electrospun poly(ɛ-caprolactone) fibers.

    Science.gov (United States)

    Weng, Lin; Teusink, Matthew J; Shuler, Franklin D; Parecki, Vivi; Xie, Jingwei

    2017-05-01

    Electrospun fibers show great potential as scaffolds for bone tissue engineering due to their architectural biomimicry to the extracellular matrix (ECM). Cation substitution of strontium for calcium in hydroxyapatite (HAp) positively influences the mechanism of bone remodeling including enhancing bone regeneration and reducing bone resorption. The objective of this study was to attach strontium-doped HAp (SrHAp) to electrospun poly(ɛ-caprolactone) (PCL) fibers for creation of novel composite scaffolds that can not only mimic the architecture and composition of ECM but also affect bone remodeling favorably. We demonstrated for the first time the highly controlled SrHAp coatings on electrospun PCL fibers. We showed the reproducible manufacturing of composite fiber scaffolds with controllable thickness, composition, and morphology of SrHAp coatings. We further showed that the released strontium and calcium cations from coatings could reach effective concentrations within 1 day and endure more than 28 days. Additionally, the Young's modulus of the SrHAp-coated PCL fibers was up to around six times higher than that of raw fibers dependent on the coating thickness and composition. Together, this novel class of composite fiber scaffolds may hold great promise for bone regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 753-763, 2017. © 2016 Wiley Periodicals, Inc.

  1. Corrosion Protection Performance of Polyester-Melamine Coating with Natural Wood Fiber Using EIS Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shin, PyongHwa; Shon, MinYoung [Pukyong National University, Busan (Korea, Republic of); Jo, DuHwan [POSCO, Gwangyang (Korea, Republic of)

    2016-04-15

    In the present study, polyester-melamine coating systems with natural wood fiber (NWF) were prepared and the effects of NWF on the corrosion protectiveness of the polyester-melamine coating were examined using EIS analysis. From the results, higher average surface roughness was observed with increase of NWF content. Water diffusivity and water uptake into the polyester-melamine coatings with NWF were much higher than that into the pure polyester-melamine coating. The decrease in the impedance modulus |Z| was associated with the localized corrosion on carbon steel, confirming that corrosion protection of the polyester-melamine coatings with NWF well agrees with its water transport behavior.

  2. Microstructure And Properties Of WC-Co HVAF Coatings Obtained From Standard, Superfine And Modified By Sub-Micrometric Carbide Powders

    Directory of Open Access Journals (Sweden)

    Myalska H.

    2015-06-01

    Full Text Available In this paper, microstructure and some properties of various coatings based on WC-Co obtained by the High Velocity Air Fuel technique are discussed. Initially, two WC-Co 83-17 powders of standard and superfine size were examined as a feedstock for a coatings deposition on a steel substrate. A standard Amperit 526.074 powder and an Inframat superfine powder were applied. Then three different sub-micrometric powders, WC, Cr3C2 and TiC were applied to modify the microstructure of WC-Co (Amperit 526.074. The aim of the investigations was to compare the microstructure and basic properties of coatings deposited from different components. The influence of sub-micrometric additions on mechanical properties of basic coatings was analyzed. Microstructure characterization of powders by using SEM and characterization of their technological properties as well, are presented. For all manufactured coatings obtained by a High Velocity Air Fuel method, the microhardness, porosity, adhesion to a substrate, and fracture toughness were determined. An improvement in WC-Co coating properties, as a result of sub-micrometric carbides addition, was revealed.

  3. Urea route to coat inorganic nanowires, carbon fibers and nanotubes by boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Gomathi, A.; Ramya Harika, M. [Chemistry and Physics of Materials Unit, DST Unit on Nanoscience and CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India); Rao, C.N.R. [Chemistry and Physics of Materials Unit, DST Unit on Nanoscience and CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India)], E-mail: cnrrao@jncasr.ac.in

    2008-03-15

    A simple route involving urea as the nitrogen source has been employed to carry out boron nitride coating on carbon fibers, multi-walled carbon nanotubes and inorganic nanowires. The process involves heating the carbon fibers and nanotubes or inorganic nanowires in a mixture of H{sub 3}BO{sub 3} and urea, followed by a heat treatment at 1000 deg. C in a N{sub 2} atmosphere. We have been able to characterize the BN coating by transmission electron microscopy as well as X-ray photoelectron spectroscopy. The urea decomposition route affords a simple method to coat boron nitride on one-dimensional nanostructures.

  4. Preparation and application of a coated-fiber needle extraction device.

    Science.gov (United States)

    Lou, Dawei; Chen, Huijun; Wang, Xiyue; Lian, Lili; Zhu, Bo; Yang, Qiaoling; Guo, Tingxiu; Li, Qiuying; Wang, Runnan; Guo, Xiaoyang

    2016-10-01

    In this study, a needle-trap device with fibers coated with a molecularly imprinted polymer was developed for separation. A number of heat-resistant Zylon filaments were longitudinally packed into a glass capillary, followed by coating with a molecularly imprinted polymer. Then, the molecularly imprinted polymer coating was copolymerized and anchored onto the surface of the fibers. The bundle of synthetic fibers coated with the molecularly imprinted polymer was packed into a 21G stainless-steel needle and served as an extraction medium. The coated-fiber needle extraction device was used to extract volatile organic compounds from paints and gasoline effectively. Subsequently, the extracted volatile organic compounds were analyzed by gas chromatography. Calibration curves of gaseous benzene, toluene, ethylbenzene, and o-xylene in the concentration range of 1-250 μg/L were obtained to evaluate the method, acceptable linearity was attended with correlation coefficients above 0.998. The limit of detection of benzene, toluene, ethylbenzene, and o-xylene was 11-20 ng/L using the coated-fiber needle-trap device. The relative standard deviation of needle-to-needle repeatability was less than 8% with an extraction time of 20 min. The loss rates after storage for 3 and 7 days at room temperature were less than 30%. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Microstructure and abrasive wear properties of M(Cr,Fe7C3 carbides reinforced high-chromium carbon coating produced by gas tungsten arc welding (GTAW process

    Directory of Open Access Journals (Sweden)

    Soner BUYTOZ

    2010-01-01

    Full Text Available In the present study, high-chromium ferrochromium carbon hypereutectic alloy powder was coated on AISI 4340 steel by the gas tungsten arc welding (GTAW process. The coating layers were analyzed by optical microscopy, X-ray diffraction (XRD, field-emission scanning electron microscopy (FE-SEM, X-ray energy-dispersive spectroscopy (EDS. Depending on the gas tungsten arc welding pa-rameters, either hypoeutectic or hypereutectic microstructures were produced. Wear tests of the coatings were carried out on a pin-on-disc apparatus as function of contact load. Wear rates of the all coating layers were decreased as a function of the loading. The improvement of abrasive wear resistance of the coating layer could be attributed to the high hardness of the hypereutectic M7C3 carbides in the microstruc-ture. As a result, the microstructure of surface layers, hardness and abrasive wear behaviours showed different characteristics due to the gas tungsten arc welding parameters.

  6. Thermal analysis of silicon carbide coating on a nickel based superalloy substrate and thickness measurement of top layers by lock-in infrared thermography

    Energy Technology Data Exchange (ETDEWEB)

    Ranjit, Shrestha; Kim, Won Tae [Kongju National University, Cheonan (Korea, Republic of)

    2017-04-15

    In this paper, we investigate the capacity of the lock-in infrared thermography technique for the evaluation of non-uniform top layers of a silicon carbide coating with a nickel based superalloy sample. The method utilized a multilayer heat transfer model to analyze the surface temperature response. The modelling of the sample was done in ANSYS. The sample consists of three layers, namely, the metal substrate, bond coat and top coat. A sinusoidal heating at different excitation frequencies was imposed upon the top layer of the sample according to the experimental procedures. The thermal response of the excited surface was recorded, and the phase angle image was computed by Fourier transform using the image processing software, MATLAB and Thermofit Pro. The correlation between the coating thickness and phase angle was established for each excitation frequency. The most appropriate excitation frequency was found to be 0.05 Hz. The method demonstrated potential in the evaluation of coating thickness and it was successfully applied to measure the non-uniform top layers ranging from 0.05 mm to 1 mm with an accuracy of 0.000002 mm to 0.045 mm.

  7. Innovative coating of nanostructured vanadium carbide on the F/M cladding tube inner surface for mitigating the fuel cladding chemical interactions

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yong [Univ. of Florida, Gainesville, FL (United States); Phillpot, Simon [Univ. of Florida, Gainesville, FL (United States)

    2017-11-29

    500 oC, respectively. The coating layer contains both carbon and vanadium elements as quantified by WED, and the phases mainly consist of a mixture of V2C and VC, which was confirmed using X-ray diffraction patterns. In addition, the ratio between V and C varies with processing temperature, and it was observed that a higher temperature promotes the carbon adsorption and increases thickness of the coating. With optimized deposition conditions, we can apply the coating technique toward the actual T91 cladding materials, and provide the possibilities for the real application in sodium-cooled fast reactors (SFRs). Diffusion couple experiments were performed at both 550 oC and 690 oC, which corresponds to normal and aggressive operating temperatures, respectively. The results show that vanadium carbide coating with wider thickness (8 µm) and lower carbon concentration (27 at.%) reduced the width of the inter diffusion region, indicating that vanadium carbide coating can mitigate FCCI effectively. In specific, inter-diffusion between Fe and Ce was prohibited over most area, but Ce diffusion occurred toward the coating and the Fe substrate through thinner coating layer, which needs further optimization in terms of uniform coating thickness. Overall, it is concluded that this coating process can be successfully applied onto the inner surface of HT9 cladding tubes and the FCCI can be effectively mitigated if not totally eliminated.

  8. Improvement of Interaction in a Composite Structure by Using a Sol-Gel Functional Coating on Carbon Fibers.

    Science.gov (United States)

    Szczurek, Anna; Barcikowski, Michał; Leluk, Karol; Babiarczuk, Bartosz; Kaleta, Jerzy; Krzak, Justyna

    2017-08-25

    The modification of carbon fibers for improving adhesion between fibers and an epoxy resin in composite materials has become the focus of attention. In this work the carbon fiber coating process has been devised in a way preventing the stiffening and clumping of fibers. To improve interactions between coated fibers and a resin in composites, four types of silica coatings with different organic functional groups (3-aminopropyl-coating 1, 3-mercaptopropyl-coating 2, 2-(3,4-epoxycyclohexyl) ethyl-coating 3, methyl-coating 4) were obtained. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to distinguish the changes of a carbon fibers surface after coating deposition. The thickness of the obtained coatings, including the diversity of thickness, was determined by transmission electron microscopy (TEM). The increase in surface free energy (SFE) of modified fibers, including the distinction between the polar and dispersive parts, was examined by wettability measurements using a tensometric test. The developed coating preparation process allowed to cover fibers separately with nanoscale silica layers, which changed their morphology. The introduction of organic functional groups resulted in surface free energy changes, especially an increase in specific polar surface energy components.

  9. Protective coating and hyperthermal atomic oxygen texturing of optical fibers used for blood glucose monitoring

    Science.gov (United States)

    Banks, Bruce A. (Inventor)

    2008-01-01

    Disclosed is a method of producing cones and pillars on polymethylmethacralate (PMMA) optical fibers for glucose monitoring. The method, in one embodiment, consists of using electron beam evaporation to deposit a non-contiguous thin film of aluminum on the distal ends of the PMMA fibers. The partial coverage of aluminum on the fibers is randomly, but rather uniformly distributed across the end of the optical fibers. After the aluminum deposition, the ends of the fibers are then exposed to hyperthermal atomic oxygen, which oxidizes the areas that are not protected by aluminum. The resulting PMMA fibers have a greatly increased surface area and the cones or pillars are sufficiently close together that the cellular components in blood are excluded from passing into the valleys between the cones and pillars. The optical fibers are then coated with appropriated surface chemistry so that they can optically sense the glucose level in the blood sample than that with conventional glucose monitoring.

  10. Fabrication and Characterization of Conductive Conjugated Polymer-Coated Antheraea mylitta Silk Fibroin Fibers for Biomedical Applications.

    Science.gov (United States)

    Gh, Darshan; Kong, Dexu; Gautrot, Julien; Vootla, Shyam Kumar

    2017-07-01

    Conductive polymers are interesting materials for a number of biological and medical applications requiring electrical stimulation of cells or tissues. Highly conductive polymers (polypyrrole and polyaniline)/Antheraea mylitta silk fibroin coated fibers are fabricated successfully by in situ polymerization without any modification of the native silk fibroin. Coated fibers characterized by scanning electron microscopy confirm the silk fiber surface is covered by conductive polymers. Thermogravimetric analysis reveals preserved thermal stability of silk fiber after coating process. X-ray diffraction of degummed fiber diffraction peaks at around 2θ = 20.4 and 16.5 confirms the preservation of the β-sheet structure typical of degummed silk II fibers. This phenomenon implies that both polypyrrole and polyaniline chains form interactions with peptide linkages in degummed fiber macromolecules, without significantly disrupting protein assembly. Fourier transform infrared spectroscopy of coated fibers indicates hydrogen bonding and electrostatic interactions exist between silk fibroin macromolecules and conductive polymers. Resulting fibers display good conductive properties compared to corresponding conjugated polymers. In vitro analysis (live/dead assay) of the behavior of human immortalized keratinocytes (HaCaTs) on coated fibers demonstrates improved cell-adhesive properties and viability after polymers coating. Hence, polypyrrole- and polyaniline-coated A. mylitta silk fibers are suitable for application in cell culture and for tissue engineering, where electrical conduction properties are required. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Coating of carbon nanotube fibers: variation of tensile properties, failure behavior and adhesion strength

    Science.gov (United States)

    Mäder, Edith; Liu, Jian-Wen; Hiller, Janett; Lu, Weibang; Li, Qingwen; Zhandarov, Serge; Chou, Tsu-Wei

    2015-07-01

    An experimental study of the tensile properties of CNT fibers and their interphasial behavior in epoxy matrices is reported. One of the most promising applications of CNT fibers is their use as reinforcement in multifunctional composites. For this purpose, an increase of the tensile strength of the CNT fibers in unidirectional composites as well as strong interfacial adhesion strength is desirable. However, the mechanical performance of the CNT fiber composites manufactured so far is comparable to that of commercial fiber composites. The interfacial properties of CNT fiber/polymer composites have rarely been investigated and provided CNT fiber/epoxy interfacial shear strength of 14.4 MPa studied by the microbond test. In order to improve the mechanical performance of the CNT fibers, an epoxy compatible coating with nano-dispersed aqueous based polymeric film formers and low viscous epoxy resin, respectively, was applied. For impregnation of high homogeneity, low molecular weight epoxy film formers and polyurethane film formers were used. The aqueous based epoxy film formers were not crosslinked and able to interdiffuse with the matrix resin after impregnation. Due to good wetting of the individual CNT fibers by the film formers, the degree of activation of the fibers was improved leading to increased tensile strength and Young’s modulus. Cyclic tensile loading and simultaneous determination of electric resistance enabled to characterize the fiber’s durability in terms of elastic recovery and hysteresis. The pull-out tests and SEM study reveal different interfacial failure mechanisms in CNT fiber/epoxy systems for untreated and film former treated fibers, on the one hand, and epoxy resin treated ones, on the other hand. The epoxy resin penetrated between the CNT bundles in the reference or film former coated fiber, forming a relatively thick CNT/epoxy composite layer and thus shifting the fracture zone within the fiber. In contrast to this, shear sliding along

  12. Coating of carbon nanotube fibers: variation of tensile properties, failure behavior and adhesion strength

    Directory of Open Access Journals (Sweden)

    Edith eMäder

    2015-07-01

    Full Text Available An experimental study of the tensile properties of CNT fibers and their interphasial behavior in epoxy matrices is reported. One of the most promising applications of CNT fibers is their use as reinforcement in multifunctional composites. For this purpose, an increase of the tensile strength of the CNT fibers in unidirectional composites as well as strong interfacial adhesion strength is desirable. However, the mechanical performance of the CNT fiber composites manufactured so far is comparable to that of commercial fiber composites. The interfacial properties of CNT fiber/polymer composites have rarely been investigated and provided CNT fiber/epoxy interfacial shear strength of 14.4 MPa studied by the microbond test.In order to improve the mechanical performance of the CNT fibers, an epoxy compatible coating with nano-dispersed aqueous based polymeric film formers and low viscous epoxy resin, respectively, was applied. For impregnation of high homogeneity, low molecular weight epoxy film formers and polyurethane film formers were used. The aqueous based epoxy film formers were not crosslinked and able to interdiffuse with the matrix resin after impregnation. Due to good wetting of the individual CNT fibers by the film formers, the degree of activation of the fibers was improved leading to increased tensile strength and Young’s modulus. Cyclic tensile loading and simultaneous determination of electric resistance enabled to characterize the fiber’s durability in terms of elastic recovery and hysteresis.The pull-out tests and SEM study reveal different interfacial failure mechanisms in CNT fiber/epoxy systems for untreated and film former treated fibers, on the one hand, and epoxy resin treated ones, on the other hand. The epoxy resin penetrated between the CNT bundles in the reference or film former coated fiber, forming a relatively thick CNT/epoxy composite layer and thus shifting the fracture zone within the fiber. In contrast to this

  13. Femtosecond laser direct-write of optofluidics in polymer-coated optical fiber

    Science.gov (United States)

    Joseph, Kevin A. J.; Haque, Moez; Ho, Stephen; Aitchison, J. Stewart; Herman, Peter R.

    2017-03-01

    Multifunctional lab in fiber technology seeks to translate the accomplishments of optofluidic, lab on chip devices into silica fibers. a robust, flexible, and ubiquitous optical communication platform that can underpin the `Internet of Things' with distributed sensors, or enable lab on chip functions deep inside our bodies. Femtosecond lasers have driven significant advances in three-dimensional processing, enabling optical circuits, microfluidics, and micro-mechanical structures to be formed around the core of the fiber. However, such processing typically requires the stripping and recoating of the polymer buffer or jacket, increasing processing time and mechanically weakening the device. This paper reports on a comprehensive assessment of laser damage in urethane-acrylate-coated fiber. The results show a sufficient processing window is available for femtosecond laser processing of the fiber without damaging the polymer jacket. The fiber core, cladding, and buffer could be simultaneously processed without removal of the buffer jacket. Three-dimensional lab in fiber devices were successfully fabricated by distortion-free immersionlens focusing, presenting fiber-cladding optical circuits and progress towards chemically-etched channels, microfluidic cavities, and MEMS structure inside buffer-coated fiber.

  14. Preparation and evaluation of graphene-coated solid-phase microextraction fiber

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jinmei; Zou Jing; Zeng Jingbin; Song Xinhong; Ji Jiaojiao; Wang Yiru [Department of Chemistry and the Key Laboratory of Analytical Sciences of the Ministry of Education, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Ha, Jaeho [Food Analysis Center, Korea Food Research Institute, San 46-1, Baekhyun, Bundang, Seongnam, Gyonggi Province 463-746 (Korea, Republic of); Chen Xi, E-mail: xichen@xmu.edu.cn [Department of Chemistry and the Key Laboratory of Analytical Sciences of the Ministry of Education, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005 (China)

    2010-09-23

    In this paper, a novel graphene (G) based solid-phase microextraction (SPME) fiber was firstly prepared by immobilizing the synthesized G on stainless steel wire as coating. The new fiber possessed a homogeneous, porous and wrinkled surface and showed excellent thermal (over 330 {sup o}C), chemical and mechanical stability, and long lifespan (over 250 extractions). The SPME performance of the G-coated fiber was evaluated in detail through extraction of six pyrethroid pesticides. Although the thickness of G-coated fiber was only 6-8 {mu}m, its extraction efficiencies were higher than those of two commercial fibers (PDMS, 100 {mu}m; PDMS/DVB, 65 {mu}m). This high extraction efficiency may be mainly attributed to huge delocalized {pi}-electron system of G, which shows strong {pi}-stacking interaction with pyrethroid pesticide. The G-coated fiber was applied in the gas chromatographic determination of six pyrethroids, and their limits of detection were found to be ranged from 3.69 to 69.4 ng L{sup -1}. The reproducibility for each single fiber was evaluated and the relative standard deviations (RSDs) were calculated to be in the range from 1.9% to 6.5%. The repeatability of fiber-to-fiber and batch-to-batch was 4.3-9.2% and 4.1-9.9%. The method developed was successfully applied to three pond water samples, and the recoveries were 83-110% at a spiking of 1 {mu}g L{sup -1}.

  15. Effects of thickness and external refractive index in coated tilted fiber Bragg gratings

    Science.gov (United States)

    Paladino, D.; Pilla, P.; Cutolo, A.; Campopiano, S.; Giordano, M.; Cusano, A.; Caucheteur, C.; Mégret, P.

    2007-07-01

    In this work, an experimental analysis on the spectral effects induced by depositing a uniform high refractive index (HRI) thin coating on weakly tilted fiber Bragg gratings (TFBGs) is carried out. First, two weakly TFBGs presenting different tilt angles were fabricated. Successively, by using dip-coating technique, two different coating thicknesses were deposited on each of them. The transmission spectra of the obtained structures were collected as the surrounding refractive index (SRI) changed in the range 1÷1.47. The coated gratings present some differences in their spectral evolution, that can be opportunely exploited. The coated configuration could improve some aspects of previous demodulation techniques exploited in the case of bare TFBGs. Moreover, an important effect of HRI coatings is to enhance the SRI sensitivity of the spectral position of the dips corresponding to cladding modes coupling, leading to a different interrogation method for sensing applications.

  16. High-temperature separation with polymer-coated fiber in packed capillary gas chromatography.

    Science.gov (United States)

    Saito, Yoshihiro; Ogawa, Mitsuhiro; Imaizumi, Motohiro; Ban, Kazuhiro; Abe, Akira; Takeichi, Tsutomu; Wada, Hiroo; Jinno, Kiyokatsu

    2005-06-01

    High-temperature gas chromatographic separation of several synthetic polymer mixtures with Dexsil-coated fiber-packed columns was studied. A bundle of heat-resistant filaments, Zylon, was longitudinally packed into a short metal capillary, followed by the conventional coating process with Dexsil 300 material. Prior to the packing process the metal capillary was deactivated by the formation of a silica layer. The typical size of the resulting column was 0.3-mm i.d., 0.5-mm o.d., 1-m length, and packed with about 170 filaments of the Dexsil-coated Zylon. The column temperature could be elevated up to 450 degrees C owing to the good thermal stability of the fiber, Dexsil coating, and metal capillary; furthermore, this allowed the separation of low-volatile compounds to be studied.

  17. Dynamic Response of Tapered Optical Multimode Fiber Coated with Carbon Nanotubes for Ethanol Sensing Application

    Directory of Open Access Journals (Sweden)

    Arafat Shabaneh

    2015-05-01

    Full Text Available Ethanol is a highly combustible chemical universally designed for biomedical applications. In this paper, optical sensing performance of tapered multimode fiber tip coated with carbon nanotube (CNT thin film towards aqueous ethanol with different concentrations is investigated. The tapered optical multimode fiber tip is coated with CNT using drop-casting technique and is annealed at 70 °C to enhance the binding of the nanomaterial to the silica fiber tip. The optical fiber tip and the CNT sensing layer are micro-characterized using FESEM and Raman spectroscopy techniques. When the developed sensor was exposed to different concentrations of ethanol (5% to 80%, the sensor reflectance reduced proportionally. The developed sensors showed high sensitivity, repeatability and fast responses (<55 s towards ethanol.

  18. Superhydrophobic conductive textiles with antibacterial property by coating fibers with silver nanoparticles

    Science.gov (United States)

    Xue, Chao-Hua; Chen, Jia; Yin, Wei; Jia, Shun-Tian; Ma, Jian-Zhong

    2012-01-01

    Silver nanoparticles (Ag NPs) were produced on cotton fibers by reduction of [Ag(NH3)2]+ complex with glucose. Further modification of the fibers coated by Ag NPs with hexadecyltrimethoxysilane led to superhydrophobic cotton textiles. Scanning electron microscopy images of the textiles showed that the treated fibers were covered with uniform Ag NPs, which generate a dual-size roughness on the textiles favouring the formation of superhydrophobic surfaces, and the Ag NPs formed dense coating around the fibers rendering the intrinsic insulating cotton textiles conductive. Antibacterial test showed that the as-fabricated textiles had high antibacterial activity against the gram-negative bacteria, Escherichia coli. These multifunctional textiles might find applications in biomedical electronic devices.

  19. “Electrochemical” growth of ZnO coating on carbon fiber

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Junfeng, E-mail: majunfeng01@sina.cn [School of Renewable Energy, North China Electric Power University, Beijing 102206 (China); Fu, Wenfeng [School of Renewable Energy, North China Electric Power University, Beijing 102206 (China); School of Materials Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050080 (China); Meng, Yongqiang [School of Materials Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050080 (China); Yu, Zhiqiang; Cai, Shan; Niu, Bingbing [School of Renewable Energy, North China Electric Power University, Beijing 102206 (China)

    2016-03-01

    A good quality of ZnO coating was successfully fabricated on carbon fiber at ambient temperature and pressure by a modified electrochemical method (“electrochemical” growth), where a carbon fiber was used as both a heating source and substrate, and ethanol solution of zinc acetate dihydrate as an electrolyte. The composition, microstructure and morphology, and photoluminescence property of the as-synthesized ZnO coating were characterized by XRD, Raman spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, and photoluminescence spectra technologies, respectively. A possible formation mechanism was initially proposed even though more detailed study will be needed. A variety of ZnO coatings with different morphologies can be easily prepared within several tens seconds through this approach, e.g. homogeneous and dense particle shape, mesoporous structure, and Y-shape split ribbon. Our results show that the “electrochemical” growth processes obvious advantages, and it can be expected to extend to the fabrication of other oxide coatings. - Highlights: • ZnO coating was fabricated on carbon fiber by an “electrochemical” growth. • The process proceeded at ambient temperature and pressure within several tens sec. • The particle morphology in ZnO coatings depended on processing parameters.

  20. Influence of carbon nanotubes coatings onto carbon fiber by oxidative treatments combined with electrophoretic deposition on interfacial properties of carbon fiber composite

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Chao; Jiang, Jianjun, E-mail: jianjun@nwpu.edu.cn; Liu, Fa; Fang, Liangchao; Wang, Junbiao; Li, Dejia; Wu, Jianjun

    2015-12-01

    Graphical abstract: Carbon nanotube/carbon fiber hybrid fiber was proposed by the treatment with hydrogen peroxide and concentrated nitric acid combined with electrophoretic deposition process. - Highlights: • Carbon nanotube coated carbon fiber was prepared by two methods. • Uniform and dense CNTs network formed by oxidative treatments combined with EPD. • Pretreatment of the CF is beneficial to EPD of CNTs on carbon fiber surface. • CNTs enhanced the surface activity and wettability of carbon fibers. • CNTs have contributed to the interfacial properties of composite. - Abstract: To improve the interfacial performance of carbon fiber (CF) and epoxy resin, carbon nanotubes (CNTs) coatings were utilized to achieve this purpose through coating onto CF by the treatment with hydrogen peroxide and concentrated nitric acid combined with electrophoretic deposition (EPD) process. The influence of electrophoretically deposited CNTs coatings on the surface properties of CFs were investigated by Fourier transform infrared spectrometer, atomic force microscopy, scanning electron microscopy and dynamic contact angle analysis. The results indicated that the deposition of carbon nanotubes introduced some polar groups to carbon fiber surfaces, enhanced surface roughness and changed surface morphologies of carbon fibers. Surface wettability of carbon fibers may be significantly improved by increasing surface free energy of the fibers due to the deposition of CNTs. The thickness and density of the coatings increases with the introduction of pretreatment of the CF during the EPD process. Short beam shear test was performed to examine the effect of carbon fiber functionalization on mechanical properties of the carbon fiber/epoxy resin composites. The interfacial adhesion of CNTs/CF reinforced epoxy composites showed obvious enhancement of interlaminar shear strength by 60.2% and scanning electron microscope photographs showed that the failure mode of composites was changed

  1. Polymer Coating of Carbon Nanotube Fibers for Electric Microcables

    National Research Council Canada - National Science Library

    Alvarez, Noe; Ochmann, Timothy; Kienzle, Nicholas; Ruff, Brad; Haase, Mark; Hopkins, Tracy; Pixley, Sarah; Mast, David; Schulz, Mark; Shanov, Vesselin

    2014-01-01

    .... Ideally, a flexible insulator such as hydrogenated nitrile butadiene rubber (HNBR) on the CNT fiber can allow fabrication of CNT coils that can be assembled into lightweight, corrosion resistant...

  2. Magnetic Field Measurements Based on Terfenol Coated Photonic Crystal Fibers

    Science.gov (United States)

    Quintero, Sully M. M.; Martelli, Cicero; Braga, Arthur M. B.; Valente, Luiz C. G.; Kato, Carla C.

    2011-01-01

    A magnetic field sensor based on the integration of a high birefringence photonic crystal fiber and a composite material made of Terfenol particles and an epoxy resin is proposed. An in-fiber modal interferometer is assembled by evenly exciting both eigenemodes of the HiBi fiber. Changes in the cavity length as well as the effective refractive index are induced by exposing the sensor head to magnetic fields. The magnetic field sensor has a sensitivity of 0.006 (nm/mT) over a range from 0 to 300 mT with a resolution about ±1 mT. A fiber Bragg grating magnetic field sensor is also fabricated and employed to characterize the response of Terfenol composite to the magnetic field. PMID:22247655

  3. Magnetic Field Measurements Based on Terfenol Coated Photonic Crystal Fibers

    Directory of Open Access Journals (Sweden)

    Carla C. Kato

    2011-11-01

    Full Text Available A magnetic field sensor based on the integration of a high birefringence photonic crystal fiber and a composite material made of Terfenol particles and an epoxy resin is proposed. An in-fiber modal interferometer is assembled by evenly exciting both eigenemodes of the HiBi fiber. Changes in the cavity length as well as the effective refractive index are induced by exposing the sensor head to magnetic fields. The magnetic field sensor has a sensitivity of 0.006 (nm/mT over a range from 0 to 300 mT with a resolution about ±1 mT. A fiber Bragg grating magnetic field sensor is also fabricated and employed to characterize the response of Terfenol composite to the magnetic field.

  4. Effect of Environment on Stress-Rupture Behavior of a Carbon Fiber-Reinforced Silicon Carbide (C/SiC) Ceramic Matrix Composite

    Science.gov (United States)

    Verrilli, Michael J.; Opila, Elizabeth J.; Calomino, Anthony; Kiser, J. Douglas

    2002-01-01

    Stress-rupture tests were conducted in air, vacuum, and steam-containing environments to identify the failure modes and degradation mechanisms of a carbon fiber-reinforced silicon carbide (C/SiC) composite at two temperatures, 600 and 1200 C. Stress-rupture lives in air and steam containing environments (50 - 80% steam with argon) are similar for a composite stress of 69 MPa at 1200 C. Lives of specimens tested in a 20% steam/argon environment were about twice as long. For tests conducted at 600 C, composite life in 20% steam/argon was 20 times longer than life in air. Thermogravimetric analysis of the carbon fibers was conducted under similar conditions to the stress-rupture tests. The oxidation rate of the fibers in the various environments correlated with the composite stress-rupture lives. Examination of the failed specimens indicated that oxidation of the carbon fibers was the primary damage mode for specimens tested in air and steam environments at both temperatures.

  5. Fibers coated with molecularly imprinted polymers for solid-phase microextraction

    NARCIS (Netherlands)

    Koster, E.H M; Crescenzi, C; den Hoedt, W; Ensing, K; de Jong, G.J.

    2001-01-01

    The simplicity and flexibility of solid-phase microextraction have been combined with the selectivity of molecularly imprinted polymers (MIPs), Silica fibers were coated reproducible with a 75-mum layer of methacrylate polymer either nonimprinted or imprinted with clenbuterol to compare their

  6. Fire performance of fiber board coated with nano kaolin-clay film

    Science.gov (United States)

    Zhijia Liu; John F. Hunt; Zhiyong Cai

    2013-01-01

    Fiberboard is a common interior material used both in China and the United States of America. The increase in demand for interior materials has raised concerns regarding combustibility of the materials. The pyrolysis characteristics of fiber, phenolic resin (PF), and nano kaolin-clay (NK) were investigated using thermogravimetry. The fire performances of samples coated...

  7. Effects of Coating and Diametric Load on Fiber Bragg Gratings as Cryogenic Temperature Sensors

    Science.gov (United States)

    Wu, meng-Chou; Pater, Ruth H.; DeHaven, Stanton L.

    2008-01-01

    Cryogenic temperature sensing was demonstrated using pressurized fiber Bragg gratings (PFBGs) with polymer coating of various thicknesses. The PFBG was obtained by applying a small diametric load to a regular fiber Bragg grating (FBG). The Bragg wavelengths of FBGs and PFBG were measured at temperatures from 295 K to 4.2 K. The temperature sensitivities of the FBGs were increased by the polymer coating. A physical model was developed to relate the Bragg wavelength shifts to the thermal expansion coefficients, Young's moduli, and thicknesses of the coating polymers. When a diametric load of no more than 15 N was applied to a FBG, a pressure-induced transition occurred at 200 K during the cooling cycle. The pressure induced transition yielded PFBG temperature sensitivities three times greater than conventional FBGs for temperatures ranging from 80 to 200 K, and ten times greater than conventional fibers for temperatures below 80 K. PFBGs were found to produce an increased Bragg wavelength shift of 2.2 nm compared to conventional FBGs over the temperature range of 4.2 to 300 K. This effect was independent of coating thickness and attributed to the change of the fiber thermo-optic coefficient.

  8. Advanced fiber information systems seed coat neps baseline response from diverse mediums

    Science.gov (United States)

    An extensive literature search has revealed that no papers have been published regarding selectivity calculation of the AFIS seed coat neps (SCN) determination over interfering material in cotton. A prerequisite to selectivity measurements is to identify suitable fiber medium(s) that give baseline ...

  9. YBCO Coated Conductor with an Integrated Optical Fiber Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sathyamurthy, Srivatsan [American Superconductor Corporation, Devens, MA (United States); Rupich, Marty [American Superconductor Corporation, Devens, MA (United States); Schwartz, Justin [North Carolina State Univ., Raleigh, NC (United States)

    2016-03-31

    The primary objectives of the Phase I Project was to develop a proof-of-principle for a concept of integrating an optical fiber sensor into the laminated 2G wire, there by producing a functionalized 2G wire with self-monitoring capabilities

  10. Double-layer optical fiber coating analysis in MHD flow of an elastico-viscous fluid using wet-on-wet coating process

    Science.gov (United States)

    Khan, Zeeshan; Islam, Saeed; Shah, Rehan Ali; Khan, Muhammad Altaf; Bonyah, Ebenezer; Jan, Bilal; Khan, Aurangzeb

    Modern optical fibers require a double-layer coating on the glass fiber in order to provide protection from signal attenuation and mechanical damage. The most important plastic resins used in wires and optical fibers are plastic polyvinyl chloride (PVC) and low and high density polyethylene (LDPE/HDPE), nylon and Polysulfone. One of the most important things which affect the final product after processing is the design of the coating die. In the present study, double-layer optical fiber coating is performed using melt polymer satisfying Oldroyd 8-constant fluid model in a pressure type die with the effect of magneto-hydrodynamic (MHD). Wet-on-wet coating process is applied for double-layer optical fiber coating. The coating process in the coating die is modeled as a simple two-layer Couette flow of two immiscible fluids in an annulus with an assigned pressure gradient. Based on the assumptions of fully developed laminar and MHD flow, the Oldroyd 8-constant model of non-Newtonian fluid of two immiscible resin layers is modeled. The governing nonlinear equations are solved analytically by the new technique of Optimal Homotopy Asymptotic Method (OHAM). The convergence of the series solution is established. The results are also verified by the Adomian Decomposition Method (ADM). The effect of important parameters such as magnetic parameter Mi , the dilatant constant α , the Pseodoplastic constant β , the radii ratio δ , the pressure gradient Ω , the speed of fiber optics V , and the viscosity ratio κ on the velocity profiles, thickness of coated fiber optics, volume flow rate, and shear stress on the fiber optics are investigated. At the end the result of the present work is also compared with the experimental results already available in the literature by taking non-Newtonian parameters tends to zero.

  11. Synthesis of silicon carbide coating on diamond by microwave heating of diamond and silicon powder: A heteroepitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Leparoux, S. [Empa, Department of Materials Technology, Feuerwerkerstrasse 39, CH-3602 Thun (Switzerland)], E-mail: susanne.leparoux@empa.ch; Diot, C. [Consultant, allee de Mozart 10, F-92300 Chatillon (France); Dubach, A. [Empa, Department of Materials Technology, Feuerwerkerstrasse 39, CH-3602 Thun (Switzerland); Vaucher, S. [Empa, Department of Materials Technology, Feuerwerkerstrasse 39, CH-3602 Thun (Switzerland)

    2007-10-15

    When a powder mixture of diamond and silicon is heated by microwaves, heteroepitaxial growth of SiC is observed on the (1 1 1) as well as on the (1 0 0) faces of the diamond. The SiC over-layer was characterized by X-ray diffraction and scanning electron microscopy. High-resolution scanning electron microscopy shows the presence of triangular silicon carbide on the (1 1 1) faces of diamond while prismatic crystals are found on the (1 0 0) faces. The crystal growth seems to be favored in the plane parallel to the face (1 1 1)

  12. Flexible fiber-reinforced composites with improved interfacial adhesion by mussel-inspired polydopamine and poly(methyl methacrylate) coating.

    Science.gov (United States)

    Yi, Mi; Sun, Hongyang; Zhang, Hongcheng; Deng, Xuliang; Cai, Qing; Yang, Xiaoping

    2016-01-01

    To obtain a kind of light-curable fiber-reinforced composite for dental restoration, an excellent interfacial adhesion between the fiber and the acrylate resin matrix is quite essential. Herein, surface modification on glass fibers were carried out by coating them with poly(methyl methacrylate) (PMMA), polydopamine (PDA), or both. The PMMA or PDA coating was performed by soaking fibers in PMMA/acetone solution or dopamine aqueous solution. PDA/PMMA co-coated glass fibers were obtained by further soaking PDA-coated fibers in PMMA/acetone solution. These modified fibers were impregnated with bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) (5:5, w/w) dental resin at a volume fraction of 75%, using unmodified fibers as reference. Light-cured specimens were submitted to evaluations including flexural properties, morphological observation, dynamic mechanical thermal analysis (DMTA) and pull-out test. In comparison with unmodified glass fibers, all the modified glass fibers showed enhancements in flexural strength and modulus of Bis-GMA/TEGDMA resin composites. Results of DMTA and pull-out tests confirmed that surface modification had significantly improved the interfacial adhesion between the glass fiber and the resin matrix. Particularly, the PDA/PMMA co-coated glass fibers displayed the most efficient reinforcement and the strongest interfacial adhesion due to the synergetic effects of PDA and PMMA. It indicated that co-coating method was a promising approach in modifying the interfacial compatibility between inorganic glass fiber and organic resin matrix. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Explanation of the Wear Behaviour of NCD Coated Carbide Tools Facilitated by Appropriate Methods for Assessing the Coating Adhesion Deterioration at Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    K.-D. Bouzakis

    2015-09-01

    Full Text Available The determination of the temperature dependent interface fatigue strength of Nano-Crystalline Diamond (NCD coatings facilitates a thorough understanding of the NCD coated cutting tools wear mechanisms. In the present paper, the fatigue strength of the interface region between a NCD film and its hardmetal substrate was investigated by inclined impact tests at various temperatures. Depending upon the impact load and the applied temperature, after a certain number of impacts, damages in the film-substrate interface develop, resulting in coating detachment and lifting. These effects were attributed among others to the release of highly compressive residual stresses in the NCD coating structure. The attained inclined impact test’s results contributed to the explanation of the wear-evolution of NCD-coated tools with diverse film-substrate adhesion qualities. The related milling experiments using as work material AA 7075 T6 verified the dominant effect of the film adhesion on the NCD coated tool life.

  14. The effect of fiber coating thickness on the interfacial properties of a continuous fiber ceramic matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Lara-Curzio, E.; Ferber, M.K.; Lowden, R.A.

    1994-09-01

    The interfacial properties (coefficient of friction, residual clamping stress, residual axial stress, and debond stress) of a continuous fiber ceramic composite were determined by means of single-fiber push-out tests. The composite consisted of Nicalon{trademark} fibers, that had been coated prior to matrix infiltration with carbon layers ranging in thickness from 0.03 to 1.2 {mu}m, and a SiC matrix. It was found that the effective interfacial frictional stress decreased as the thickness of the carbon layer increased, from 24.6 {plus_minus} 9.9 MPa for a thickness of 0.03 Jim to 5.8 {plus_minus} 1.4 MPa for a thickness of 1.25 {mu}m. It was also found that both the coefficient of friction and the residual clamping stress decreased as the thickness of the carbon layer increased. These results are explained in terms of the state of residual stresses in this composite and the role of the fiber surface topography during fiber sliding.

  15. Biobased silver nanocolloid coating on silk fibers for prevention of post-surgical wound infections.

    Science.gov (United States)

    Dhas, Sindhu Priya; Anbarasan, Suruthi; Mukherjee, Amitava; Chandrasekaran, Natarajan

    2015-01-01

    Bombyx mori silk fibers are an important biomaterial and are used in surgical sutures due to their remarkable biocompatibility. The major drawback to the application of biomaterials is the risk of bacterial invasion, leading to clinical complications. We have developed an easy and cost-effective method for fabrication of antibacterial silk fibers loaded with silver nanoparticles (AgNPs) by an in situ and ex situ process using an aqueous extract of Rhizophora apiculata leaf. Scanning electron microscopy revealed that well dispersed nanoparticles impregnated the silk fibers both in situ and ex situ. The crystalline nature of the AgNPs in the silk fibers was demonstrated by X-ray diffraction. The thermal and mechanical properties of the silk fibers were enhanced after they were impregnated with AgNPs. The silver-coated silk fibers fabricated by the in situ and ex situ method exhibited more than 90% inhibition against Pseudomonas aeruginosa and Staphylococcus aureus. Silk fibers doped with AgNPs were found to be biocompatible with 3T3 fibroblasts. The results obtained represent an important advance towards the clinical application of biocompatible AgNP-loaded silk fibers for prevention of surgical wound infections.

  16. Tri-bore PVDF hollow fibers with a super-hydrophobic coating for membrane distillation

    KAUST Repository

    Lu, Kang-Jia

    2016-04-26

    Membranes with good mechanical strength, high vapor flux and outstanding anti-wetting properties are essential for membrane distillation (MD) applications. In this work, porous polyvinylidene fluoride (PVDF) tri-bore hollow fiber membranes with super-hydrophobicity are developed to achieve these desired properties. The tri-bore hollow fiber offers better mechanical strength than the conventional single-bore fiber. To improve its anti-wetting properties, Teflon® AF 2400 is coated on the membrane surface. The effects of coating on membrane morphology, performance and anti-wetting properties have been thoroughly investigated. With an optimal coating condition (0.025 wt% of Teflon® AF 2400, 30 s), a super-hydrophobic surface with a contact angle of 151o is achieved. The resultant membrane shows an increase of 109% in liquid entry pressure (LEP) with a slight sacrifice of 21% in flux. Long term direct contact MD tests have confirmed that the Teflon® AF 2400 coated membrane has enhanced stability with an average flux of 21 kg m-2 h-1 and rejection of 99.99% at 60 °° C for desalination application.

  17. High resolution fiber optic surface plasmon resonance sensors with single-sided gold coatings.

    Science.gov (United States)

    Feng, Dingyi; Zhou, Wenjun; Qiao, Xueguang; Albert, Jacques

    2016-07-25

    The surface plasmon resonance (SPR) performance of gold coated tilted fiber Bragg gratings (TFBG) at near infrared wavelengths is evaluated as a function of the angle between the tilt plane orientation and the direction of single- and double-sided, nominally 50 nm-thick gold metal depositions. Scanning electron microscope images show that the coating are highly non-uniform around the fiber circumference, varying between near zero and 50 nm. In spite of these variations, the experimental results show that the spectral signature of the TFBG-SPR sensors is similar to that of simulations based on perfectly uniform coatings, provided that the depositions are suitably oriented along the tilt plane direction. Furthermore, it is shown that even a (properly oriented) single-sided coating (over only half of the fiber circumference) is sufficient to provide a theoretically perfect SPR response with a bandwidth under 5 nm, and 90% attenuation. Finally, using a pair of adjacent TFBG resonances within the SPR response envelope, a power detection scheme is used to demonstrate a limit of detection of 3 × 10-6 refractive index units.

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

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, H.; Curtin, W.A. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)

    1996-08-01

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

  19. Coating of carbon fiber-reinforced polyetheretherketone implants with titanium to improve bone apposition.

    Science.gov (United States)

    Devine, Declan M; Hahn, Joachim; Richards, R Geoffery; Gruner, Heiko; Wieling, Ronald; Pearce, Simon G

    2013-05-01

    Carbon fiber-reinforced polyetheretherketone (CF/PEEK) is a thermoplastic composite biomaterial exhibiting properties suitable for load-bearing orthopedic implants. However, the hydrophobic surface of CF/PEEK implants induces the deposition of a peri-implant fibrous tissue capsule preventing bone apposition. However, if bone apposition was improved, the use of CF/PEEK in orthopedics could be increased as it has many advantages compared with metallic implants. In this study, CF/PEEK screws were coated with titanium (Ti) using two different techniques, namely vacuum plasma spraying (VPS) and physical vapor deposition (PVD) with uncoated screws as controls. These coatings were characterized and implanted in a loaded sheep tibia model. In the characterization of the screw surfaces using microscopy techniques, the uncoated screws were seen to have an irregular surface. The PVD coating appeared smooth and consistent, whereas the VPS coating appeared to be a rough coating with some inhomogeneities, which did not cover the entire surface area. Nevertheless, in the ex vivo analysis the VPS-coated screws had a screw removal torque which was statistically greater than uncoated and PVD-coated screws (p ≤ 0.002 for both comparisons). Additionally, the VPS-coated screws had a statistically higher bone contact area than the uncoated screws (p = 0.006), whereas no statistical difference was detected between VPS and PVD coating types (p = 0.11). Thereby illustrating that Ti coating of CF/PEEK screws significantly improve bone apposition and removal torque compared with uncoated CF/PEEK screws. Copyright © 2012 Wiley Periodicals, Inc.

  20. Disposable Polydimethylsiloxane (PDMS-Coated Fused Silica Optical Fibers for Sampling Pheromones of Moths.

    Directory of Open Access Journals (Sweden)

    Rik Lievers

    Full Text Available In the past decades, the sex pheromone composition in female moths has been analyzed by different methods, ranging from volatile collections to gland extractions, which all have some disadvantage: volatile collections can generally only be conducted on (small groups of females to detect the minor pheromone compounds, whereas gland extractions are destructive. Direct-contact SPME overcomes some of these disadvantages, but is expensive, the SPME fiber coating can be damaged due to repeated usage, and samples need to be analyzed relatively quickly after sampling. In this study, we assessed the suitability of cheap and disposable fused silica optical fibers coated with 100 μm polydimethylsiloxane (PDMS by sampling the pheromone of two noctuid moths, Heliothis virescens and Heliothis subflexa. By rubbing the disposable PDMS fibers over the pheromone glands of females that had called for at least 15 minutes and subsequently extracting the PDMS fibers in hexane, we collected all known pheromone compounds, and we found a strong positive correlation for most pheromone compounds between the disposable PDMS fiber rubs and the corresponding gland extracts of the same females. When comparing this method to volatile collections and the corresponding gland extracts, we generally found comparable percentages between the three techniques, with some differences that likely stem from the chemical properties of the individual pheromone compounds. Hexane extraction of cheap, disposable, PDMS coated fused silica optical fibers allows for sampling large quantities of individual females in a short time, eliminates the need for immediate sample analysis, and enables to use the same sample for multiple chemical analyses.

  1. Osseointegration is improved by coating titanium implants with a nanostructured thin film with titanium carbide and titanium oxides clustered around graphitic carbon.

    Science.gov (United States)

    Veronesi, Francesca; Giavaresi, Gianluca; Fini, Milena; Longo, Giovanni; Ioannidu, Caterina Alexandra; Scotto d'Abusco, Anna; Superti, Fabiana; Panzini, Gianluca; Misiano, Carlo; Palattella, Alberto; Selleri, Paolo; Di Girolamo, Nicola; Garbarino, Viola; Politi, Laura; Scandurra, Roberto

    2017-01-01

    Titanium implants coated with a 500nm nanostructured layer, deposited by the Ion Plating Plasma Assisted (IPPA) technology, composed of 60% graphitic carbon, 25% titanium oxides and 15% titanium carbide were implanted into rabbit femurs whilst into the controlateral femurs uncoated titanium implants were inserted as control. At four time points the animals were injected with calcein green, xylenol orange, oxytetracycline and alizarin. After 2, 4 and 8weeks femurs were removed and processed for histology and static and dynamic histomorphometry for undecalcified bone processing into methylmethacrylate, sectioned, thinned, polished and stained with Toluidine blue and Fast green. The overall bone-implant contacts rate (percentage of bone-implant contacts/weeks) of the TiC coated implant was 1.6 fold than that of the uncoated titanium implant. The histomorphometric analyses confirmed the histological evaluations. More precisely, higher Mineral Apposition Rate (MAR, μm/day) (p<0.005) and Bone Formation Rate (BFR, μm 2 /μm/day) (p<0.0005) as well as Bone Implant Contact (Bic) and Bone Ingrowth values (p<0.0005) were observed for the TiC coated implants compared to uncoated implants. In conclusion the hard nanostructured TiC layer protects the bulk titanium implant against the harsh conditions of biological tissues and in the same time, stimulating adhesion, proliferation and activity of osteoblasts, induces a better bone-implant contacts of the implant compared to the uncoated titanium implant. Copyright © 2016. Published by Elsevier B.V.

  2. Highly sensitive fiber optic Fabry-Perot geophone with graphene coated PMMA membrane

    Science.gov (United States)

    Yu, C. B.; Wu, Y.; Wu, F.; Li, C.; Zhou, J. H.; Rao, Y. J.; Chen, Y. F.

    2017-04-01

    A highly sensitive fiber-optic Fabry-Perot interferometric geophone (FFPG) with graphene coated PMMA membrane is proposed and demonstrated, where the graphene coating is used for enhancement of the mechanical strength of the membrane. It is found that the sensitivity of the FFPG is much higher than that of the conventional electrical geophone. Such a novel all-optical geophone with low cost, high sensitivity, electromagnetic interference immunity, easy fabrication and robust structure would have great potential for use in oil/gas exploration and seismic wave detection.

  3. Non-Lubricated Diamond-Coated Bearings Reinforced by Carbon Fibers to Work in Lunar Dust Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase I, we made prototype sliding bearings from functionally-graded, diamond-coated carbon-fiber reinforced composite. In dry-sliding experiments, the friction...

  4. Copper nanowire coated carbon fibers as efficient substrates for detecting designer drugs using SERS.

    Science.gov (United States)

    Halouzka, Vladimir; Halouzkova, Barbora; Jirovsky, David; Hemzal, Dusan; Ondra, Peter; Siranidi, Eirini; Kontos, Athanassios G; Falaras, Polycarpos; Hrbac, Jan

    2017-04-01

    Miniature Surface Enhanced Raman Scattering (SERS) sensors were fabricated by coating the carbon fiber microelectrodes with copper nanowires. The coating procedure, based on anodizing the copper wire in ultrapure water followed by cathodic deposition of the anode-derived material onto carbon fiber electrodes, provides a "clean" copper nanowire network. The developed miniature (10µm in diameter and 2mm in length) and nanoscopically rough SERS substrates are applicable in drug sensing, as shown by the detection and resolving of a range of seized designer drugs in trace amounts (microliter volumes of 10 -10 -10 -12 M solutions). The copper nanowire modified carbon microfiber substrates could also find further applications in biomedical and environmental sensing. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. MEH-PPV film thickness influenced fluorescent quenching of tip-coated plastic optical fiber sensors

    Science.gov (United States)

    Yusufu, A. M.; Noor, A. S. M.; Tamchek, N.; Abidin, Z. Z.

    2017-12-01

    The performance of plastic optical fiber sensors in detecting nitro aromatic explosives 1,4-dinitrobenzene (DNB) have been investigated by fluorescence spectroscopy and analyzed by using fluorescence quenching technique. The plastic optical fiber utilized is 90 degrees cut tip and dip-coated with conjugated polymer MEH-PPV poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] thin films for detection conjugants. The thicknesses of the MEH-PPV coating were varied to improvise the sensitivity whilst slowly reducing the fluorescence intensity. It was shown that fluorescence intensity from thinner film decreased by (82% in 40 s) in the presence of DNB signifying an improvement of 28% reduction with time 13 s less than that of the thicker film.

  6. Optical Fiber Relative Humidity Sensor Based on a FBG with a Di-Ureasil Coating

    Directory of Open Access Journals (Sweden)

    Sandra F. H. Correia

    2012-06-01

    Full Text Available In this work we proposed a relative humidity (RH sensor based on a Bragg grating written in an optical fiber, associated with a coating of organo-silica hybrid material prepared by the sol-gel method. The organo-silica-based coating has a strong adhesion to the optical fiber and its expansion is reversibly affected by the change in the RH values (15.0–95.0% of the surrounding environment, allowing an increased sensitivity (22.2 pm/%RH and durability due to the presence of a siliceous-based inorganic component. The developed sensor was tested in a real structure health monitoring essay, in which the RH inside two concrete blocks with different porosity values was measured over 1 year. The results demonstrated the potential of the proposed optical sensor in the monitoring of civil engineering structures.

  7. Optical fiber relative humidity sensor based on a FBG with a di-ureasil coating.

    Science.gov (United States)

    Correia, Sandra F H; Antunes, Paulo; Pecoraro, Edison; Lima, Patrícia P; Varum, Humberto; Carlos, Luis D; Ferreira, Rute A S; André, Paulo S

    2012-01-01

    In this work we proposed a relative humidity (RH) sensor based on a Bragg grating written in an optical fiber, associated with a coating of organo-silica hybrid material prepared by the sol-gel method. The organo-silica-based coating has a strong adhesion to the optical fiber and its expansion is reversibly affected by the change in the RH values (15.0-95.0%) of the surrounding environment, allowing an increased sensitivity (22.2 pm/%RH) and durability due to the presence of a siliceous-based inorganic component. The developed sensor was tested in a real structure health monitoring essay, in which the RH inside two concrete blocks with different porosity values was measured over 1 year. The results demonstrated the potential of the proposed optical sensor in the monitoring of civil engineering structures.

  8. A study of lubrication, processing conditions, and material combinations that affect the wear of micro-textured-carbide coated cobalt-chromium-molybdenum alloy surfaces used for artificial joints implants

    Science.gov (United States)

    Ettienne-Modeste, Geriel A.

    Total joint replacement remains one of the most successful treatments for arthritis. The most common materials used for artificial joints are metals (e.g., cobalt-chrome alloys or titanium alloys), which articulate against ultra-high molecular weight polyethylene. Wear related failures of artificial joints may be reduced with the use of novel micro-textured carbide surfaces. The micro-textured carbide surfaces were deposited on a CoCrMo alloy using microwave plasma-assisted chemical vapor deposition. Wear tests were conducted to determine wear mechanisms and properties of the micro-textured surfaces. The research presented in this thesis addresses: (1) rheolgoical behavior of bovine calf serum with and without antibacterial agents to determine whether they can be used as appropriate models for synovial fluid, (2) the wear behavior of the micro-textured CoCrMo surface system, and (3) the mechanical and material properties of the micro-textured CoCrMo alloy surface relevant to wear performance. The rheological studies showed that the apparent viscosity of bovine calf serum increased with an increase in concentration before and after the serum was used for wear testing. The wear analysis showed that the processing conditions (2hr deposition vs. 4hr deposition times) affected the wear properties. The 2hr carbide-on-carbide lubricated in 50% BCS produced the lowest wear factor and rate for the five wear couple systems containing the carbide disk or plate material. Greater wear was produced in serum without penicillin/streptomycin (P/S) compared to the serum containing P/S. A greater carbide coating thickness 10 (micrometers) was produced during the 4hr deposition time than for the 2hr deposition (˜3mum). The nano-hardness value was higher than the micro-hardness for both the 4hr and 2hr carbide surfaces. The micro-hardness results of the worn carbide surfaces showed that an increase in BCS concentration from 0% to 100% increased the micro-hardness (HV) for carbide

  9. Preliminary examination of a CCD camera with a scintillator coated fiber optic plate for neutron imaging

    Science.gov (United States)

    Matsubayashi, Masahito; Soyama, Kazuhiko

    2004-08-01

    A charge coupled device (CCD) camera with a scintillator coated fiber optic plate (FOP) was examined for neutron imaging. The FOP coupling and the lens coupling in terms of efficient optical coupling with a CCD, and 6LiF:ZnS(Ag) and Gd 2O 2S(Tb) in terms of light emission efficiency and spatial resolution were discussed. The spatial resolution for each imaging system was obtained as edge spread functions or observations of modulation transfer function charts.

  10. Study on the Preparation of a High-Efficiency Carbon Fiber Dissipating Coating

    Directory of Open Access Journals (Sweden)

    Jing Li

    2017-07-01

    Full Text Available The working temperature of electronic components directly determines their service life and stability. In order to ensure normal operation of electronic components, cooling the coating is one of the best ways to solve the problem. Based on an acrylic amino-resin system, a dissipating coating was prepared with carbon fiber (CF as the main thermal conductive filler. The influence of the CF content on the thermal conductivity was determined by the single factor method. The surface structure was observed by scanning electron microscopy (SEM. The results show: With the increase of the CF mass fraction, both the heat dispersion and heat conduction coefficient of the coating tend to increase at first and then decrease, and the heat dissipation effect is optimum when the CF mass fraction is 12.3 wt %. At this point, the coating shows an excellent comprehensive performance, such as 1st level adhesion, H grade hardness, and thermal conductivity of 1.61 W/m·K. Furthermore, this paper explored the radiating mechanism of coating in which CF produces a coating which forms a heat “channel” for rapid heat conduction. When the optimal value is exceeded, the cooling effect is reduced because of the accumulation and the anisotropy of CF.

  11. Medicated Janus fibers fabricated using a Teflon-coated side-by-side spinneret.

    Science.gov (United States)

    Yu, Deng-Guang; Yang, Chen; Jin, Miao; Williams, Gareth R; Zou, Hua; Wang, Xia; Bligh, S W Annie

    2016-02-01

    A family of medicated Janus fibers that provides highly tunable biphasic drug release was fabricated using a side-by-side electrospinning process employing a Teflon-coated parallel spinneret. The coated spinneret facilitated the formation of a Janus Taylor cone and in turn high quality integrated Janus structures, which could not be reliably obtained without the Teflon coating. The fibers prepared had one side consisting of polyvinylpyrrolidone (PVP) K60 and ketoprofen, and the other of ethyl cellulose (EC) and ketoprofen. To modulate and tune drug release, PVP K10 was doped into the EC side in some cases. The fibers were linear and had flat morphologies with an indent in the center. They provide biphasic drug release, with the PVP K60 side dissolving very rapidly to deliver a loading dose of the active ingredient, and the EC side resulting in sustained release of the remaining ketoprofen. The addition of PVP K10 to the EC side was able to accelerate the second stage of release; variation in the dopant amount permitted the release rate and extent this phase to be precisely tuned. These results offer the potential to rationally design systems with highly controllable drug release profiles, which can complement natural biological rhythms and deliver maximum therapeutic effects. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Microstructured gradient-index antireflective coating fabricated on a fiber tip with direct laser writing.

    Science.gov (United States)

    Kowalczyk, Maciej; Haberko, Jakub; Wasylczyk, Piotr

    2014-05-19

    We present a simple broadband gradient-index antireflective coating, fabricated directly on a single mode telecom fiber tip. A regular array of hemi-ellipsoidal protrusions significantly reduce the Fresnel reflection from the glass-air interface. The parameters of the structure were optimized with numerical simulation for the best performance at and around 1550 nm and the coating was fabricated with Direct Laser Writing. The measured reflectance decreased by a factor of 30 at 1550 nm and was below 0.28% for the 100 nm spectral band around the central wavelength. Compared to quarter wavelength antireflective coatings the demonstrated approach offers significantly reduced technological challenges, in particular processing of a single optical material with low sensitivity to imperfections in the fabrication process.

  13. A selectively coated photonic crystal fiber based surface plasmon resonance sensor

    DEFF Research Database (Denmark)

    Yu, X; Zhang, Y.; Pan, S.S.

    2010-01-01

    We propose a novel design for a photonic crystal fiber based surface plasmonic resonance sensor. The sensor consists of selectively metal-coated air holes containing analyte channels, which enhance the phase matching between the plasmonic mode and the core-guided mode. Good refractive index...... sensitivity as high as 5500 nm/RIU (refractive index unit) can be achieved in the proposed structure. Compared with the entirely coated structure, the selectively coated sensor design demonstrates narrower resonance spectral width. Moreover, the greater resonance depth can improve the sensing performance...... in terms of signal to noise ratio (SNR). The improvements in spectral width and SNR can both contribute to a better detection limit for this refractive index sensor....

  14. Laminated composite based on polyester geotextile fibers and polyurethane resin for coating wood structures

    Directory of Open Access Journals (Sweden)

    Yuri Andrey Olivato Assagra

    2013-01-01

    Full Text Available New environmental laws have restricted the use of hardwood trees in overhead power lines structures, such as, poles and cross-arms, leading companies to seek alternative materials. Reforested wood coated with polymeric resin has been proposed as an environmental friendly solution, with improved electrical properties and protection against external agents, e.g. moisture, ultraviolet radiation and fungi. However, the single thin layer of resin, normally applied on such structures reveal to be inefficient, due to be easily damage during handling. In this paper, we present a composite coating, based on geotextile fibers and polyurethane resin that is suitable for wooden structures. Results obtained from two different tree species (from managed and reforested areas coated with the composite reveal that the additional layer not only provided a stronger adhesion between wood and ccoating layer but also a further improvement in the electrical properties and better protection against abrasion and moisture.

  15. Thermal performance of glass fiber reinforced intumescent fire retardant coating for structural applications

    Science.gov (United States)

    Ahmad, Faiz; Ullah, Sami; Aziz, Hammad; Omar, Nor Sharifah

    2015-07-01

    The results of influence of glass fiber addition into the basic intumescent coating formulation towards the enhancement of its thermal insulation properties are presented. The intumescent coatings were formulated from expandable graphite, ammonium polyphosphate, melamine, boric acid, bisphenol A epoxy resin BE-188, polyamide amine H-2310 hardener and fiberglass (FG) of length 3.0 mm. Eight intumescent formulations were developed and the samples were tested for their fire performance by burning them at 450°C, 650°C and 850°C in the furnace for two hours. The effects of each fire test at different temperatures; low and high temperature were evaluated. Scanning Electron Microscope, X-Ray Diffraction technique and Thermo Gravimetric Analysis were conducted on the samples to study the morphology, the chemical components of char and the residual weight of the coatings. The formulation, FG08 containing 7.0 wt% glass fiber provided better results with enhanced thermal insulation properties of the coatings.

  16. Wear Behavior of Fiber Laser Textured TiN Coatings in a Heavy Loaded Sliding Regime

    Directory of Open Access Journals (Sweden)

    Daniele Ugues

    2012-11-01

    Full Text Available In heavy loaded mating components, such as sliders and sliding bearings, guaranteeing the efficiency of lubricant films for long times during severe service conditions is very complicated. In this work, the benefits deriving from the use of fiber laser sources for surface texturing of very thin TiN coatings in severe wear working conditions were demonstrated. Evaluations of the laser textured dimples shape, geometry and density are given. Wear performance of the fiber laser textured surfaces was evaluated in discontinuous oil lubricated conditions with a flat contact. High normal load and low sliding speed were applied. Comparison tests were also performed on commercial TiN and WC/C coatings. In terms of average wear volume and maximum wear depth, Laser Surface Texturing of TiN provided respectively a 70% and a 45% reduction if compared to plain TiN. If compared to WC/C the wear resistance gains were lower but LST TiN maintained such benefits for longer wear runs. SEM analysis also revealed that the laser interaction provided a localized thermal cracking to the TiN coating. However, the sliding action caused very limited and localized coating fragmentation or delamination.

  17. Thermal performance of glass fiber reinforced intumescent fire retardant coating for structural applications

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Ullah, Sami; Aziz, Hammad, E-mail: engr.hammad.aziz03@gmail.com; Omar, Nor Sharifah [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Tronoh 31750 Perak (Malaysia)

    2015-07-22

    The results of influence of glass fiber addition into the basic intumescent coating formulation towards the enhancement of its thermal insulation properties are presented. The intumescent coatings were formulated from expandable graphite, ammonium polyphosphate, melamine, boric acid, bisphenol A epoxy resin BE-188, polyamide amine H-2310 hardener and fiberglass (FG) of length 3.0 mm. Eight intumescent formulations were developed and the samples were tested for their fire performance by burning them at 450°C, 650°C and 850°C in the furnace for two hours. The effects of each fire test at different temperatures; low and high temperature were evaluated. Scanning Electron Microscope, X-Ray Diffraction technique and Thermo Gravimetric Analysis were conducted on the samples to study the morphology, the chemical components of char and the residual weight of the coatings. The formulation, FG08 containing 7.0 wt% glass fiber provided better results with enhanced thermal insulation properties of the coatings.

  18. Polypyrrole/hexagonally ordered silica nanocomposite as a novel fiber coating for solid-phase microextraction

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad Bagher, E-mail: mbgholivand@yahoo.com [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Abolghasemi, Mir Mahdi [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Faculty of Chemistry, University of Maragheh, Maragheh (Iran, Islamic Republic of); Fattahpour, Peyman [Department of organic Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of)

    2011-10-17

    Highlights: {yields} The polypyrrole/SBA15) nanocomposite was used as a novel coating for SPME fiber. {yields} The proposed fiber was used for the extraction of polycyclic aromatic hydrocarbons. {yields} The proposed SPME fiber is thermal stable, and it has a low limit of detection. {yields} The SPME fiber was applied in polluted river water and wastewater samples. - Abstract: A highly porous fiber coated polypyrrole/hexagonally ordered silica (PPy/SBA15) materials were prepared for solid-phase microextraction (SPME). The PPy/SBA15 nanocomposite was synthesized by an in situ polymerization technique. The resulting material was characterized by the scanning electron microscopy, thermogravimetric analysis and differential thermal analysis. The prepared nanomaterial was immobilized onto a stainless steel wire for fabrication of the SPME fiber. The fiber was evaluated for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions in combination with gas chromatography-mass spectrometry (GC-MS). A one at-the-time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, ionic strength, stirring rate, desorption time and desorption temperature. In optimum conditions (extraction temperature 70 deg. C, extraction time 20 min, ionic strength 20% (W V{sup -1}), stirring rate 500 rpm, desorption temperature 270 deg. C, desorption time 5 min) the repeatability for one fiber (n = 3), expressed as relative standard deviation (R.S.D. %), was between 5.0% and 9.3% for the tested compounds. The quantitation limit for the studied compounds were between 13.3 and 66.6 pg mL{sup -1}. The life span and stability of the PPy/SBA15 fiber are good, and it can be used more than 50 times at 260 deg. C without any significant change in sorption properties. The developed method offers the advantage of being simple to use, with shorter analysis times, lower cost of equipment, thermal

  19. Electrically-controlled near-field radiative thermal modulator made of graphene-coated silicon carbide plates

    Science.gov (United States)

    Yang, Yue; Wang, Liping

    2017-08-01

    In this work, we propose a hybrid near-field radiative thermal modulator made of two graphene-covered silicon carbide (SiC) plates separated by a nanometer vacuum gap. The near-field photon tunneling between the emitter and receiver is modulated by changing graphene chemical potentials with symmetrically or asymmetrically applied voltage biases. The radiative heat flux calculated from fluctuational electrodynamics significantly varies with graphene chemical potentials due to tunable near-field coupling strength between graphene plasmons across the vacuum gap. Thermal modulation and switching, which are the key functionalities required for a thermal modulator, are theoretically realized and analyzed. Newly introduced quantities of the modulation factor, the sensitivity factor and switching factor are studied quite extensively in a large parameter range for both graphene chemical potential and vacuum gap distance. This opto-electronic device with faster operating mode, which is in principle only limited by electronics and not by the thermal inertia, will facilitate the practical application of active thermal management, thermal circuits, and thermal computing with photon-based near-field thermal transport.

  20. Hard coating of ultrananocrystalline diamond/nonhydrogenated amorphous carbon composite films on cemented tungsten carbide by coaxial arc plasma deposition

    Science.gov (United States)

    Naragino, Hiroshi; Egiza, Mohamed; Tominaga, Aki; Murasawa, Koki; Gonda, Hidenobu; Sakurai, Masatoshi; Yoshitake, Tsuyoshi

    2016-08-01

    Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite (UNCD/a-C) films were deposited on cemented carbide containing Co by coaxial arc plasma deposition. With decreasing substrate temperature, the hardness was enhanced accompanied by an enhancement in the sp3/(sp2 + sp3). Energy-dispersive X-ray and secondary ion mass spectrometry spectroscopic measurements exhibited that the diffusion of Co atoms from the substrates into the films hardly occurs. The film deposited at room temperature exhibited the maximum hardness of 51.3 GPa and Young's modulus of 520.2 GPa, which evidently indicates that graphitization induced by Co in the WC substrates, and thermal deformation from sp3 to sp2 bonding are suppressed. The hard UNCD/a-C films can be deposited at a thickness of approximately 3 μm, which is an order larger than that of comparably hard a-C films. The internal compressive stress of the 51.3-GPa film is 4.5 GPa, which is evidently smaller than that of comparably hard a-C films. This is a reason for the thick deposition. The presence of a large number of grain boundaries in the film, which is a structural specific to UNCD/a-C films, might play a role in releasing the internal stress of the films.

  1. Design of a polarized filtering photonic-crystal fiber with gold-coated air holes.

    Science.gov (United States)

    Wang, Guangyao; Li, Shuguang; An, Guowen; Wang, Xinyu; Zhao, Yunyan; Zhang, Wan

    2015-10-20

    A novel design of a gold-coated photonic-crystal fiber (PCF) is studied by using the finite element method. The cross-section structure of the PCF is composed of a square lattice of air holes in which two air holes are gold coated, and the air-hole layout is modified. The resonance strength and the impact of structural parameters of the PCF on the polarization filter characteristics are studied. Numerical results show that the resonance strength and wavelengths are different in two polarized directions. The resonance strengths that we obtain can reach a value of 720 dB/cm at the wavelength of 1.31 μm. When the fiber length is 400 μm, the crosstalk can reach a value of 247.2 dB at the wavelength of 1.31 μm, which can be applied in many polarization filter devices. And when the length of fiber is longer than 200 μm, the crosstalk is better than 20 dB with wavelength ranges from 1.2 to 2 μm. Meanwhile, we can realize the filtering effect with a very short fiber.

  2. A simple gold-coated microstructure fiber polarization filter in two communication windows

    Science.gov (United States)

    Feng, Xinxing; Li, Shuguang; Du, Huijing; Zhang, Yinan; Liu, Qiang

    2018-03-01

    A polarization filter is designed at two communication windows of 1310 and 1550 nm based on microstructured optical fiber. The model has four large diameter air holes and two gold-coated air holes. The influence of the geometrical parameters of the photonic crystal fiber on the performance of the polarization filter is analyzed by the finite element method. The numerical simulation shows that when the fiber length is 300 μm, the corresponding extinction ratio is 209.7 dB and 179.8 dB, the bandwidth of extinction ratio (ER) better than 20 dB is 150 nm and 350 nm at the communication wavelength of 1310 nm and 1550 nm.

  3. A new composite material-low-carbon Stellite alloy reinforced with nickel-coated carbon fibers

    National Research Council Canada - National Science Library

    Khoddamzadeh, A; Liu, R; Liang, M; Yang, Q

    2014-01-01

    .... The focus of this research is on obviating the problems related to the presence of carbides in Stellite alloys by substituting carbides as the main strengthening agent in Stellite alloys with nickel...

  4. Optimizing the fabrication of aluminum-coated fiber probes and their application to optical near-field lithography

    DEFF Research Database (Denmark)

    Madsen, S; Holme, NCR; Ramanujam, PS

    1998-01-01

    We report on routine fabrication of fiber probes suitable for metal coating. We have investigated how aperture sizes ranging from 75 to 300 nm can be produced using an appropriate set of pulling parameters in a combined heating/pulling process. The quality of the metal coating has been investigat...

  5. Analyzing freely dissolved concentrations of cationic surfactant utilizing ion-exchange capability of polyacrylate coated solid-phase microextraction fibers

    NARCIS (Netherlands)

    Chen, Y.|info:eu-repo/dai/nl/322994179; Droge, S.T.J.|info:eu-repo/dai/nl/304834017; Hermens, J.L.M.|info:eu-repo/dai/nl/069681384

    2012-01-01

    A 7-μm polyacrylate (PA) coated fiber was successfully employed to determine freely dissolved concentrations of cationic surfactants by solid-phase microextraction (SPME) and utilizing the capability of the PA-coating to sorb organic cations via ion-exchange at carboxylic groups. Measured

  6. Structure-property relations for silicon nitride matrix composites reinforced with pyrolytic carbon pre-coated Hi-Nicalon fibers

    NARCIS (Netherlands)

    Kooi, B.J.; Hosson, J.Th.M. De; Olivier, C.; Veyret, J.B.

    1999-01-01

    Si3N4 matrix composites reinforced with pyrolytic carbon pre-coated Hi-Nicalon (SiC) fibers, were studied using tensile testing and transmission electron microscopy. Three types of samples were evaluated all with a nominal coating thickness of 200 nm. The composites were densified by hot pressing at

  7. Investigating the Possibility to Reduce the Residual Stress Level in 2.5D Cutting Using Titanium Coated Carbide Ball End Mill

    Directory of Open Access Journals (Sweden)

    N. Masmiati

    2014-01-01

    Full Text Available End milling is a multipoint cutting process in which material is removed from a workpiece by a rotating tool. It is widely used in cutting 2.5D profiles such as point-to-point, contouring, and pocketing operations. 2.5D machining possesses the capability to translate in all 3 axes but can perform the cutting operation in only 2 of the 3 axes at a time. This study focuses on optimizing the cutting parameters, such as machined surface inclinationangle, axial depth of cut, spindle speed, and feed rate for better surface integrity, namely, microhardness, residual stress, and microstructure in 2.5D cutting utilizing a titanium-coated carbide ball end mill. An optimization method known as Taguchi optimization, which includes planning, conducting, and analyzing results of matrix experiments, was used in order to achieve the best cutting parameter level. Data analysis was conducted using signal-to-noise (S/N and target performance measurement (TPM response analysis and analysis of variance (Pareto ANOVA. The optimum condition results obtained through analysis show improvements in microhardness of about 0.7%, residual stress in the feed direction of about 18.6%, and residual stress in the cutting direction of about 15.4%.

  8. Modeling and optimization of surface roughness and productivity thru RSM in face milling of AISI 1040 steel using coated carbide inserts

    Directory of Open Access Journals (Sweden)

    Mohamed Fnides

    2017-03-01

    Full Text Available The aim of this study is to evaluate the impact of factors such as cutting speed, feed rate, and depth of cut on surface roughness and Material Removed Rate (MRR when machining in dry face milling AISI 1040 steel with coated carbide inserts GC1030 using the response surface methodology (RSM. For this purpose, a number of machining experiments based on statistical three-factor and three-level factorial experiment designs, completed (L27 with a statistical analysis of variance (ANOVA, were performed in order to develop mathematical models and to identify the significant factors of these technological parameters. Multi-objective optimization procedure for minimizing Ra, Ry and Rz and maximizing MRR using desirability approach has been also implementented. The current study was also carried out to investigate the tool life of the inserts. The models found the relationship between the cutting parameters (Vc, fz and ap and the studied technological parameters. It has been found that the cutting speed was the most affecting surface roughness which is due to the geometry of the insert which has a scraping edge and enables to obtain low roughness even at important feed rate, followed by the feed rate and the depth of cut at the end. The optimal combination of cutting parameters were cutting speed of 314 m/min, feed rate of 0.16 mm/tooth and depth of cut of 0.6 mm with a composite desirability of 0.924.

  9. Deposition of mullite and mullite-like coatings on silicon carbide by dual-source metal plasma immersion. Topical report, October 1995--September 1996

    Energy Technology Data Exchange (ETDEWEB)

    Brown, I.G.; Monteiro, O.R. [Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    Mullite and mullite-like coatings on silicon carbide have been produced by a Metal Plasma Immersion Ion Implantation and Deposition (Mepiiid) technique based on two cathodic vacuum arc sources and concurrent pulse biasing of the substrate in an oxygen atmosphere. The deposition was carried out at oxygen partial pressures of between 0.66 and 3.33 Pa. The Al:Si ratio in the films varied from 1:1 to 8:1 and was controlled by varying the pulse duration of the separate plasma guns. High bias voltage was used early in the deposition process in order to produce atomic mixing at the film-substrate interface, while lower bias voltage was used later in the deposition; low ion energy allows control of the physical properties of the film as well as faster deposition rates. The as-deposited films were amorphous, and crystalline mullite was formed by subsequent annealing at 1,100 C for 2 hours in air. Strong adhesion between the mullite and the SiC was achieved, in some cases exceeding the 70 MPa instrumental limit of the pull-tester.

  10. A novel silver-coated solid-phase microextraction metal fiber based on electroless plating technique.

    Science.gov (United States)

    Feng, Juanjuan; Sun, Min; Li, Jubai; Liu, Xia; Jiang, Shengxiang

    2011-09-09

    A novel silver-coated solid-phase microextraction fiber was prepared based on electroless plating technique. Good extraction performance of the fiber for model compounds including phthalate esters (dibutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate and diallyl phthalate) and polycyclic aromatic hydrocarbons (naphthalene, fluorene, phenanthrene, fluoranthene) in aqueous solution was obtained. Under the optimized conditions (extraction temperature, extraction time, ionic strength and desorption temperature), the proposed SPME-GC method showed wide linear ranges with correlation coefficients (R(2)) ranging from 0.9745 to 0.9984. The limits of detection were at the range of 0.02 to 0.1 μg L(-1). Single fiber repeatability and fiber-to-fiber reproducibility as well as stability to acid, alkali and high temperature were studied and the results were all satisfactory. The method was applied successfully to the aqueous extracts of disposable paper cup and instant noodle barrel. Several kinds of analytes were detected and quantified. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Molecular imprinted polymer-coated optical fiber sensor for the identification of low molecular weight molecules.

    Science.gov (United States)

    Lépinay, Sandrine; Ianoul, Anatoli; Albert, Jacques

    2014-10-01

    A biomimetic optical probe for detecting low molecular weight molecules (maltol, 3-hydroxy-2-methyl-4H-pyran-4-one, molecular weight of 126.11 g/mol), was designed, fabricated, and characterized. The sensor couples a molecular imprinted polymer (MIP) and the Bragg grating refractometry technology into an optical fiber. The probe is fabricated first by inscribing tilted grating planes in the core of the fiber, and then by photopolymerization to immobilize a maltol imprinted MIP on the fiber cladding surface over the Bragg grating. The sensor response to the presence of maltol in different media is obtained by spectral interrogation of the fiber transmission signal. The results showed that the limit of detection of the sensor reached 1 ng/mL in pure water with a sensitivity of 6.3 × 10(8)pm/M. The selectivity of the sensor against other compounds and its reusability were also studied experimentally. Finally, the unambiguous detection of concentrations as little as 10nM of maltol in complex media (real food samples) by the MIP-coated tilted fiber Bragg grating sensor was demonstrated. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Fabrication of water-repellent cellulose fiber coated with magnetic nanoparticles under supercritical carbon dioxide

    Science.gov (United States)

    Xu, Shengjie; Shen, Danping; Wu, Peiyi

    2013-04-01

    Hematite nanoparticle-coated magnetic composite fiber was prepared in supercritical carbon dioxide (scCO2). With the help of scCO2, cellulose did not need to be dissolved and regenerated and it could be in any form (e.g., cotton wool, filter paper, textile, etc.). The penetrating and swelling effect of scCO2, the slowing reaction rate of weak alkalis, and the template effect of cellulose fibers were discovered to be the key factors for the fabrication of ordered cellulose/Fe2O3 composite fibers. The structures of the composite fibers as well as the layers of Fe2O3 particles were characterized by means of scanning/transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman investigation. It was found that α-Fe2O3 granules which ranged from 30 to 85 nm with average diameter around 55 nm would be generated on the surface of cellulose fibers via potassium acetate, while irregular square prisms (ranged from 200 to 600 nm) which were composed of smaller nanoparticles ( 10 nm) would be fabricated via urea. And, the obtained composite was highly water repellent with superparamagnetic or ferromagnetic properties.

  13. Towards seamlessly-integrated textile electronics: methods to coat fabrics and fibers with conducting polymers for electronic applications.

    Science.gov (United States)

    Allison, Linden; Hoxie, Steven; Andrew, Trisha L

    2017-06-29

    Traditional textile materials can be transformed into functional electronic components upon being dyed or coated with films of intrinsically conducting polymers, such as poly(aniline), poly(pyrrole) and poly(3,4-ethylenedioxythiophene). A variety of textile electronic devices are built from the conductive fibers and fabrics thus obtained, including: physiochemical sensors, thermoelectric fibers/fabrics, heated garments, artificial muscles and textile supercapacitors. In all these cases, electrical performance and device ruggedness is determined by the morphology of the conducting polymer active layer on the fiber or fabric substrate. Tremendous variation in active layer morphology can be observed with different coating or dyeing conditions. Here, we summarize various methods used to create fiber- and fabric-based devices and highlight the influence of the coating method on active layer morphology and device stability.

  14. Microstructure and Tensile Properties of BN/SiC Coated Hi-Nicalon, and Sylramic SiC Fiber Preforms

    Science.gov (United States)

    Bhatt, Ramakrishna T.; Chen, Yuan L.; Morscher, Gregory N.

    2001-01-01

    Batch to batch and within batch variations, and the influence of fiber architecture on room temperature physical and tensile properties of BN/SiC coated Hi-Nicalon and Sylramic SiC fiber preform specimens were determined. The three fiber architectures studied were plain weave (PW), 5-harness satin (5HS) and 8-harness satin (8HS) Results indicate that the physical properties vary up to 10 percent within a batch, and up to 20 percent between batches of preforms. Load-reload (Hysteresis) and acoustic emission methods were used to analyze damage accumulation occurring during tensile loading. Early acoustic emission activity, before observable hysteretic behavior, indicates that the damage starts with the formation of nonbridged tunnel cracks. These cracks then propagate and intersect the load bearing "0" fibers giving rise to hysteretic behavior, For the Hi-Nicalon preform specimens, the onset of "0" bundle cracking stress and strain appeared to be independent of the fiber architecture. Also, the "0" fiber bundle cracking strain remained nearly the same for the preform specimens of both fiber types. Transmission Electron Microscope (TEM) analysis indicates that the Chemical Vapor Infiltration (CVI) Boron Nitride (BN) interface coating is mostly amorphous and contains carbon and oxygen impurities, and the CVI SiC coating is crystalline. No reaction exists between the CVI BN and SiC coating.

  15. Relative Humidity Sensor Based on No-Core Fiber Coated by Agarose-Gel Film

    Directory of Open Access Journals (Sweden)

    Wei Xu

    2017-10-01

    Full Text Available A relative humidity (RH sensor based on single-mode–no-core–single-mode fiber (SNCS structure is proposed and experimentally demonstrated. The agarose gel is coated on the no-core fiber (NCF as the cladding, and multimode interference (MMI occurs in the SNCS structure. The transmission spectrum of the sensor is modulated at different ambient relative humidities due to the tunable refractive index property of the agarose gel film. The relative humidity can be measured by the wavelength shift and intensity variation of the dip in the transmission spectra. The humidity response of the sensors, coated with different concentrations and coating numbers of the agarose solution, were experimentally investigated. The wavelength and intensity sensitivity is obtained as −149 pm/%RH and −0.075 dB/%RH in the range of 30% RH to 75% RH, respectively. The rise and fall time is tested to be 4.8 s and 7.1 s, respectively. The proposed sensor has a great potential in real-time RH monitoring.

  16. Relative Humidity Sensor Based on No-Core Fiber Coated by Agarose-Gel Film.

    Science.gov (United States)

    Xu, Wei; Shi, Jia; Yang, Xianchao; Xu, Degang; Rong, Feng; Zhao, Junfa; Yao, Jianquan

    2017-10-16

    A relative humidity (RH) sensor based on single-mode-no-core-single-mode fiber (SNCS) structure is proposed and experimentally demonstrated. The agarose gel is coated on the no-core fiber (NCF) as the cladding, and multimode interference (MMI) occurs in the SNCS structure. The transmission spectrum of the sensor is modulated at different ambient relative humidities due to the tunable refractive index property of the agarose gel film. The relative humidity can be measured by the wavelength shift and intensity variation of the dip in the transmission spectra. The humidity response of the sensors, coated with different concentrations and coating numbers of the agarose solution, were experimentally investigated. The wavelength and intensity sensitivity is obtained as -149 pm/%RH and -0.075 dB/%RH in the range of 30% RH to 75% RH, respectively. The rise and fall time is tested to be 4.8 s and 7.1 s, respectively. The proposed sensor has a great potential in real-time RH monitoring.

  17. CO2 sensing at room temperature using carbon nanotubes coated core fiber Bragg grating.

    Science.gov (United States)

    Shivananju, B N; Yamdagni, S; Fazuldeen, R; Sarin Kumar, A K; Hegde, G M; Varma, M M; Asokan, S

    2013-06-01

    The sensing of carbon dioxide (CO2) at room temperature, which has potential applications in environmental monitoring, healthcare, mining, biotechnology, food industry, etc., is a challenge for the scientific community due to the relative inertness of CO2. Here, we propose a novel gas sensor based on clad-etched Fiber Bragg Grating (FBG) with polyallylamine-amino-carbon nanotube coated on the surface of the core for detecting the concentrations of CO2 gas at room temperature, in ppm levels over a wide range (1000 ppm-4000 ppm). The limit of detection observed in polyallylamine-amino-carbon nanotube coated core-FBG has been found to be about 75 ppm. In this approach, when CO2 gas molecules interact with the polyallylamine-amino-carbon nanotube coated FBG, the effective refractive index of the fiber core changes, resulting in a shift in Bragg wavelength. The experimental data show a linear response of Bragg wavelength shift for increase in concentration of CO2 gas. Besides being reproducible and repeatable, the technique is fast, compact, and highly sensitive.

  18. Use of Lignin Fibers to Improve Mechanical Properties of Coated Wood

    Directory of Open Access Journals (Sweden)

    Falak O. Abass

    2013-05-01

    Full Text Available In this research, a new method for the production of the blend consists of polyester resin as a matrix-binder at fixed weigh and different weighs of epoxy resin that can be used to coat wood is developed. Several experiments are performed under different conditions to identify the most favorable operating conditions for the preparation of blend (polyester/epoxy resins. Optimum conditions, namely, mixing speed, mixing time, heating temperature and heating time are investigated and found experimentally as 500rpm, 5min, 750C and 6hr respectively. In addition, solid palms wastes (lignin as reinforcement fibers is employed in order to improve the mechanical properties: impact strength, bending deflection and bending distortion of coated wood. The optimum ratio of prepared blend is characterized by the mechanical (impact and bending tests of the untreated samples occurred at a ratio of polyester/epoxy resins of 0.91w/w. It showed the best bonding force and physical interaction between two resins. The impact strength of the treated samples with one and two layers of prepared lignin fibers are higher than that of the untreated sample, while the bending distortion and bending deflection of treated samples are lower than that of the untreated sample. Experimental results showed that the treated sample with biofibers (lignin led to enhancement in the mechanical properties of coated wood.

  19. Improving Mechanical Properties of Thermoset Biocomposites by Fiber Coating or Organic Oil Addition

    Directory of Open Access Journals (Sweden)

    Truc T. Ngo

    2015-01-01

    Full Text Available Two different thermoset biocomposite systems are experimented in this study with the hope to improve their mechanical properties. Fiberglass and hemp, in form of fabrics, are used to reinforce the thermoset polymer matrix, which includes a traditional epoxy resin and a linseed oil-based bioresin (UVL. The fiber/polymer matrix interface is modified using two different approaches: adding a plant-based oil (pine or linseed to the polymer matrix or coating the fibers with 3-(aminopropyltriethoxysilane (APTES prior to integrating them into the polymer matrix. Epoxy resin is cured using an amine-based initiator, whereas UVL resin is cured under ultraviolet light. Results show that hemp fibers with APTES prime coat used in either epoxy or UVL matrix exhibit some potential improvements in the composite’s mechanical properties including tensile strength, modulus of elasticity, and ductility. It is also found that adding oil to the epoxy matrix reinforced with fiberglass mostly improves the material’s modulus of elasticity while maintaining its tensile strength and ductility. However, adding oil to the epoxy matrix reinforced with hemp doubles the material’s ductility while slightly reducing its tensile strength and modulus of elasticity.

  20. Design optimization of gold-coated fiber tips with embedded plasmonic slot nano-resonators

    Science.gov (United States)

    Petropoulou, Afroditi; Zervas, Michalis N.; Riziotis, Christos

    2017-05-01

    Nanostructures of dimensions around the operating wavelength of light can support optical resonances enhancing the incident light by orders of magnitude and concentrating it in the nanoscale. Their integration to optical fiber tips with thin metallic claddings, forming plasmonic slot nanoresonators (PSNRs), provides ease of light coupling from the fiber’s core modes to the slot and a robust platform which can find many applications in nano-optics and sensing. Guiding and modal properties of metal-coated optical fiber tips with embedded PSNRs are investigated through finite element method (FEM) simulations towards the identification of their optimization parameters. It was found that the placement of a PSNR at the cut-off radius of a metal-coated fiber tip, where the group velocity tends to zero, leads to considerable intensity enhancement of the field confined beyond the diffraction limit. Maximum intensity enhancement of optimally placed PSNRs at different radii shows a linear dependence between excitation wavelength and radius, making it feasible to engineer the proper radius for a specific wavelength for maximum enhancement.

  1. Chitosan coated carbon fiber microelectrode for selective in vivo detection of neurotransmitters in live zebrafish embryos

    Energy Technology Data Exchange (ETDEWEB)

    Ozel, Rifat Emrah [Department of Chemistry and Biomolecular Science, 8 Clarkson Ave, Potsdam, NY 136995810 (United States); Wallace, Kenneth N. [Department of Biology, Clarkson University, Potsdam, NY 136995810 (United States); Andreescu, Silvana, E-mail: eandrees@clarkson.edu [Department of Chemistry and Biomolecular Science, 8 Clarkson Ave, Potsdam, NY 136995810 (United States)

    2011-06-10

    Graphical abstract: Chitosan coated fiber electrodes are sensitive to serotonin detection while rejecting physiological levels of ascorbic acid interferences. - Abstract: We report the development of a chitosan modified carbon fiber microelectrode for in vivo detection of serotonin. We find that chitosan has the ability to reject physiological levels of ascorbic acid interferences and facilitate selective and sensitive detection of in vivo levels of serotonin, a common catecholamine neurotransmitter. Presence of chitosan on the microelectrode surface was investigated using scanning electron microscopy (SEM) and cyclic voltammetry (CV). The electrode was characterized using differential pulse voltammetry (DPV). A detection limit of 1.6 nM serotonin with a sensitivity of 5.12 nA/{mu}M, a linear range from 2 to 100 nM and a reproducibility of 6.5% for n = 6 electrodes were obtained. Chitosan modified microelectrodes selectively measure serotonin in presence of physiological levels of ascorbic acid. In vivo measurements were performed to measure concentration of serotonin in the live embryonic zebrafish intestine. The sensor quantifies in vivo intestinal levels of serotonin while successfully rejecting ascorbic acid interferences. We demonstrate that chitosan can be used as an effective coating to reject ascorbic acid interferences at carbon fiber microelectrodes, as an alternative to Nafion, and that chitosan modified microelectrodes are reliable tools for in vivo monitoring of changes in neurotransmitter levels.

  2. A New Hydrogen Sensor Based on SNS Fiber Interferometer with Pd/WO3 Coating

    Directory of Open Access Journals (Sweden)

    Jinxin Shao

    2017-09-01

    Full Text Available This paper presents a new hydrogen sensor based on a single mode–no core–single mode (SNS fiber interferometer structure. The surface of the no core fiber (NCF was coated by Pd/WO3 film to detect the variation of hydrogen concentration. If the hydrogen concentration changes, the refractive index of the Pd/WO3 film as well as the boundary condition for light propagating in the NCF will all be changed, which will then cause a shift into the resonant wavelength of interferometer. Therefore, the hydrogen concentration can be deduced by measuring the shift of the resonant wavelength. Experimental results demonstrated that this proposed sensor had a high detection sensitivity of 1.26857 nm/%, with good linearity and high accuracy (maximum 0.0055% hydrogen volume error. Besides, it also possessed the advantages of simple structure, low cost, good stability, and repeatability.

  3. A graphite-coated carbon fiber epoxy composite bipolar plate for polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Yu, Ha Na; Lim, Jun Woo; Suh, Jung Do; Lee, Dai Gil

    A PEMFC (polymer electrolyte membrane fuel cell or proton exchange membrane fuel cell) stack is composed of GDLs (gas diffusion layers), MEAs (membrane electrode assemblies), and bipolar plates. One of the important functions of bipolar plates is to collect and conduct the current from cell to cell, which requires low electrical bulk and interfacial resistances. For a carbon fiber epoxy composite bipolar plate, the interfacial resistance is usually much larger than the bulk resistance due to the resin-rich layer on the composite surface. In this study, a thin graphite layer is coated on the carbon/epoxy composite bipolar plate to decrease the interfacial contact resistance between the bipolar plate and the GDL. The total electrical resistance in the through-thickness direction of the bipolar plate is measured with respect to the thickness of the graphite coating layer, and the ratio of the bulk resistance to the interfacial contact resistance is estimated using the measured data. From the experiment, it is found that the graphite coating on the carbon/epoxy composite bipolar plate has 10% and 4% of the total electrical and interfacial contact resistances of the conventional carbon/epoxy composite bipolar plate, respectively, when the graphite coating thickness is 50 μm.

  4. Compliment Graphene Oxide Coating on Silk Fiber Surface via Electrostatic Force for Capacitive Humidity Sensor Applications.

    Science.gov (United States)

    Han, Kook In; Kim, Seungdu; Lee, In Gyu; Kim, Jong Pil; Kim, Jung-Ha; Hong, Suck Won; Cho, Byung Jin; Hwang, Wan Sik

    2017-02-19

    Cylindrical silk fiber (SF) was coated with Graphene oxide (GO) for capacitive humidity sensor applications. Negatively charged GO in the solution was attracted to the positively charged SF surface via electrostatic force without any help from adhesive intermediates. The magnitude of the positively charged SF surface was controlled through the static electricity charges created on the SF surface. The GO coating ability on the SF improved as the SF's positive charge increased. The GO-coated SFs at various conditions were characterized using an optical microscope, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and LCR meter. Unlike the intact SF, the GO-coated SF showed clear response-recovery behavior and well-behaved repeatability when it was exposed to 20% relative humidity (RH) and 90% RH alternatively in a capacitive mode. This approach allows humidity sensors to take advantage of GO's excellent sensing properties and SF's flexibility, expediting the production of flexible, low power consumption devices at relatively low costs.

  5. Preliminary examination of a CCD camera with a scintillator coated fiber optic plate for neutron imaging

    Energy Technology Data Exchange (ETDEWEB)

    Matsubayashi, Masahito E-mail: matsu3@popsvr.tokai.jaeri.go.jp; Soyama, Kazuhiko

    2004-08-21

    A charge coupled device (CCD) camera with a scintillator coated fiber optic plate (FOP) was examined for neutron imaging. The FOP coupling and the lens coupling in terms of efficient optical coupling with a CCD, and {sup 6}LiF:ZnS(Ag) and Gd{sub 2}O{sub 2}S(Tb) in terms of light emission efficiency and spatial resolution were discussed. The spatial resolution for each imaging system was obtained as edge spread functions or observations of modulation transfer function charts.

  6. Detection of organophosphorous pesticides in soil samples with multiwalled carbon nanotubes coating SPME fiber.

    Science.gov (United States)

    Feng, Xilan; Li, Ying; Jing, Ruijun; Jiang, Xiaoying; Tian, Mengkui

    2014-12-01

    A headspace solid phase microextraction (HS-SPME) technique using stainless steel fiber coated with 20 μm multi-walled carbon nanotubes (MWCNTs) and gas chromatography with thermionic specific detector (GC-TSD) was developed to determine organophosphorous pesticides (OPPs) in soil. Parameters affecting the extraction efficiency such as extraction time and temperature, ionic strength, the volume of water added to the soil, sample solution volume to headspace volume ratio, desorption time, and desorption temperature were investigated and optimized. Compared to commercial polydimethylsiloxane (PDMS, 7 μm) fiber, the PDMS fiber was better to be corrected as phorate, whereas the MWCNTs fiber gave slightly better results for methyl parathion, chlorpyrifos and parathion. The optimized SPME method was applied to analyze OPPs in spiked soil samples. The limits of detection (LODs, S/N = 3) for the four pesticides were <0.216 ng g(-1), and their calibration curves were all linear (r (2) ≥ 0.9908) in the range from 1 to 200 ng g(-1). The precision (RSD, n = 6) for peak areas was 6.5 %-8.8 %. The recovery of the OPPs spiked real soil samples at 50 and 150 ng g(-1) ranged from 89.7 % to 102.9 % and 94.3 % to 118.1 %, respectively.

  7. Magnetoconductivity and electrical transport of polyaniline coated ternary carbide Ti0.9Al0.1C

    Science.gov (United States)

    Mukherjee, P. S.; Gupta, K.; Rana, D.; Meikap, A. K.

    2017-11-01

    In this paper, we report the mechanism of electrical transport properties of polyaniline coated Ti0.9Al0.1C prepared by chemical route. Samples are characterized by X-ray diffraction technique and morphology has been observed by field emission scanning electron microscope. Semiconducting behavior is obtained for the samples and this behavior has been analyzed by different existing models. Out of different models the Mott's variable range hopping is the most suitable for analyzing the dc conductivity at lower temperatures. Correlated barrier hopping type of charge transfer process is followed in alternating current conductivity. We observe a transformation from negative to positive dc and ac magnetoconductivity by incorporating Ti0.9Al0.1C in polyaniline. Dielectric properties and impedance analysis are described by Maxwell-Wagner capacitor model. We determine different parameters like localization length, hopping distance, density of states from the analysis of the experimental data. The theory regarding magnetic field dependent ac conductivity is insufficient. This result will be a significant hint for a new theoretical challenge.

  8. Facile modification of multi-walled carbon nanotubes-polymeric ionic liquids-coated solid-phase microextraction fibers by on-fiber anion exchange.

    Science.gov (United States)

    Feng, Juanjuan; Sun, Min; Bu, Yanan; Luo, Chuannan

    2015-05-08

    In situ anion exchange has been proved to be an efficient method for facile modification of polymeric ionic liquids (PILs)-based stationary phases. In this work, an on-fiber anion exchange process was utilized to tune the extraction performance of a multi-walled carbon nanotubes (MWCNTs)-poly(1-vinyl-3-octylimidazolium bromide) (poly(VOIm(+)Br(-)))-coated solid-phase microextraction (SPME) fiber. MWCNTs were first coated onto the stainless steel wire through a layer-by-layer fabrication method and then the PILs were coated onto the MWCNTs physically. Anion of the MWCNTs-poly(VOIm(+)Br(-)) fiber was changed into bis(triflroromethanesulfonyl)imide (NTf2(-)) and 2-naphthalene-sulfonate (NapSO3(-)) by on-fiber anion exchange. Coupled to gas chromatography, the MWCNTs-poly(VOIm(+)Br(-)) fiber showed acceptable extraction efficiency for hydrophilic and hydrogen-bonding-donating alcohols, with limits of detection (LODs) in the range of 0.005-0.05μgmL(-1); after the anion exchange with NTf2(-), the obtained MWCNTs-poly(VOIm(+)NTf2(-)) fiber brought wide linear ranges for hydrophobic n-alkanes with correlation coefficient (R) ranging from 0.994 to 0.997; aromatic property of the fiber was enhanced by aromatic NapSO3(-) anions to get sufficient extraction capacity for phthalate esters and halogenated aromatic hydrocarbons. The MWCNTs-poly(VOIm(+)NapSO3(-)) fiber was finally applied to determine several halogenated aromatic hydrocarbons in groundwater of industrial park. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Reduced graphene oxide coated optical fiber for methanol and ethanol vapor detection at room temperature

    Science.gov (United States)

    Kavinkumar, T.; Sastikumar, D.; Manivannan, S.

    2014-10-01

    Successful isolation of single layer of graphene from graphite by mechanical exfoliation method, attracted a great attention due to its unique structural, optical, mechanical and electronic properties. This makes the graphene as a promising material in many possible applications such as energy-storage, sensing, electronic, optical devices and polymer composite materials. High quality of reduced graphene oxide (rGO) material was prepared by chemical reduction method at 100°C. The structural and optical properties of the rGO sheets were characterized by FT-IR, micro Raman, powder XRD and UV-vis-NIR techniques. FT-IR reveals the absence of oxygen functional groups on rGO due to the reduction process. Powder XRD shows the broad peak at 2θ=24.3° corresponding to interlayer spacing 3.66Å which is smaller than the graphene oxide (GO). UV-vis-NIR of rGO displays the absorption peak at 271 nm indicates the reduction of GO and the restoration of C=C bonds in the rGO sheets. The cladding removed and rGO coated poly-methyl methacrylate (PMMA) optical fiber is used for methanol and ethanol vapors detection in the concentration ranging from 0 to 500 ppm at room temperature. The spectral characteristics along with output intensity modulation of cladding removed and rGO coated fiber optic sensor reveal the potential of methanol and ethanol vapor sensing properties.

  10. Diamond-coated fiber Bragg grating through the hot filament chemical vapor process for chemical durability improvement.

    Science.gov (United States)

    Alberto, Nélia; José Kalinowski, Hypolito; Neto, Victor; Nogueira, Rogério

    2017-02-20

    In recent years, the coating of fiber Bragg gratings (FBGs) with a specific material has opened up the possibility to broaden the limits of applicability of this technology. Diamond has a set of properties that makes it an attractive candidate to protect the optical fiber against chemically harsh environments, whose sensing is also a great challenge. One of the most used techniques to obtain these coatings is through the hot filament chemical vapor deposition (HFCVD); in this process, the temperature reaches, typically, around 850°C-900°C. In this work, the regeneration of a seed FBG during its coating with a nanocrystalline diamond thin film through the HFCVD process is presented. Simultaneously, the thermal monitoring of the process was also performed using the same grating. The resistance test in a corrosive medium reveals an improvement on the durability of the sensing properties of the diamond-coated FBG compared with an uncoated FBG, foreseeing a vast range of applications.

  11. Carbon fiber CVD coating by carbon nanostructured for space materials protection against atomic oxygen

    Science.gov (United States)

    Pastore, Roberto; Bueno Morles, Ramon; Micheli, Davide

    2016-07-01

    adhesion and durability in the environment. Though these coatings are efficient in protecting polymer composites, their application imposes severe constraints. Their thermal expansion coefficients may differ markedly from those of polymer composite substrates: as a result, cracks develop in the coatings on thermal cycling and AO can penetrate through them to the substrate. In addition to the technicalities of forming an effective barrier, such factors as cost, convenience of application and ease of repair are important considerations in the selection of a coating for a particular application. The latter issues drive the aerospace research toward the development of novel light composite materials, like the so called polymer nanocomposites, which are materials with a polymer matrix and a filler with at least one dimension less than 100 nanometers. Current interest in nanocomposites has been generated and maintained because nanoparticle-filled polymers exhibit unique combinations of properties not achievable with traditional composites. These combinations of properties can be achieved because of the small size of the fillers, the large surface area the fillers provide, and in many cases the unique properties of the fillers themselves. In particular, the carbon fiber-based polymeric composite materials are the basic point of interest: the aim of the present study is to find new solution to produce carbon fiber-based composites with even more upgraded performances. One intriguing strategy to tackle such an issue has been picked out in the coupling between the carbon fibers and the carbon nanostructures. That for two main reasons: first, carbon nanostructures have shown fancy potentialities for any kind of technological applications since their discovery, second, the chemical affinity between fiber and nanostructure (made of the same element) should be a likely route to approach the typical problems due to thermo-mechanical compatibility. This work is joined in such framework

  12. Introduction of a coiled solid-phase microextraction fiber based on a coating of animal bone waste for chromatographic analysis.

    Science.gov (United States)

    Razmi, Habib; Farrokhzadeh, Samaneh

    2017-04-01

    We attempt to introduce animal bone waste as a coating material with an organic-inorganic structure for the fabrication of a coiled solid-phase microextraction fiber for the first time. The coiled fiber was simply prepared with the use of copper wire and coated with bone waste suspension through the dip-coating method. The bone waste coating was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. It was applied as new type of solid-phase microextraction fiber for preconcentration of polycyclic aromatic hydrocarbons before determination by high-performance liquid chromatography with UV detection. A wide linear range 0.01-99.0 μg/L and limits of detection in the range 3.0-11.1 ng/L were obtained at optimized conditions. The bone waste coated coiled solid-phase microextraction fiber has promise in sample preparation techniques because it is cost effective, available, stable in aqueous and organic solutions, environmentally friendly, and easy to fabricate and operate. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Study on the effect of carbon nanotube coating on the refractive index sensing sensitivity of fiber modal interferometer

    Science.gov (United States)

    Zhang, Ya-nan; Xie, Wen-ge; Wang, Jianzhang; Wang, Pengzhao

    2018-01-01

    Refractive index sensing of liquid is important in the domain of chemistry and biology. Fiber optical sensors provide an excellent way to measure the refractive index due to their feasible integration to other fiber optics components, high sensitivity, small size, and distributed sensing. However, conventional optical sensors have different shortages. To find a practical way to measure the refractive index of liquid, this paper intended to combine Carbon Nanotube (CNT) with non-core fiber (NCF) to prepare a kind of modal interferometer sensor and to explore the effect of CNT coating on refractive index sensing properties of the modal interferometer. Firstly, a structure of single mode non-core single mode (SNS) fiber with a CNT film coating was proposed and simulated. The simulation results showed that the CNT coating could improve the refractive index sensitivity of the interferometer sensor. Then in the experiment part, the CNT solution was fabricated and deposited onto the NCF, and a refractive index sensing system was built to examine the property of the CNT-coated SNS interferometer sensor. During the experiment, the influence factors of sensitivity were summarized by testing the sensing performance under different conditions, and it was demonstrated that the CNT coating could improve the contrast of the interference spectrum, and also had the possibility to increase the refractive index sensitivity of the interferometer sensor.

  14. An Experimental Thermally Deposited Coating for Improved Bonding to Glass-fiber Posts.

    Science.gov (United States)

    Reis, Giselle Rodrigues; Silva, Fernanda Pereira; Oliveira-Ogliari, Aline; Faria-E-Silva, André Luis; Moraes, Rafael R; Novais, Veridiana Resende; Menezes, Murilo de Sousa

    To determine whether an experimental thermally deposited siloxane-methacrylate coating for use in industrial scale applications would improve the bond strength of resin-based materials to glass fiber posts (GFPs) without affecting their mechanical properties. An experimental 5% (w/v) solution of methacryloxypropyltrimethoxysilane was prepared. Two types of GFPs (Exacto, Angelus; White Post DC, FGM) were divided into the following groups: S: silane; SA: silane and adhesive; HS: 35% H₂O₂ and silane; HSA: 35% H₂O₂, silane and adhesive; Exp: siloxane-methacrylate coating (Si-O) via post immersion in experimental solution followed by heating; Exp-S: silane after Si-O treatment; Exp-A: adhesive after Si-O treatment; and Exp-SA: silane and adhesive after Si-O treatment. The posts were positioned in a mold to allow insertion of a dual-curing resin core, serially sectioned into beams, and subjected to microtensile bond strength (μTSB) testing. The three-point bending test and SEM/EDX analysis were used to assess the mechanical and surface properties of untreated GFPs that were etched with H₂O₂ or treated with Si-O. Surface treatments affected the μTSB only for the Exacto GFPs. The highest μTBS (MPa) was observed in Exp-S and Exp-SA groups, whereas H₂O₂ etching resulted in intermediate values. The mechanical properties were not affected by surface treatments. Exacto GFPs had significantly higher flexural strength (σf) and flexural modulus (Ef) than did the White Post DC GFPs, but the latter were significantly stiffer (S) than Exacto, regardless of the surface treatment tested. H₂O₂ promoted morphological changes in post surfaces. The experimental treatment promoted deposition of Si onto the post surface, improving bond strengths of Exacto posts. The proposed novel coating technique is a viable procedure for fiber post manufacturers to improve the μTSB of resin-based materials.

  15. Evanescent wave absorption sensor based on tapered multimode fiber coated with monolayer graphene film

    Science.gov (United States)

    Qiu, Hengwei; Gao, Saisai; Chen, Peixi; Li, Zhen; Liu, Xiaoyun; Zhang, Chao; Xu, Yuanyuan; Jiang, Shouzhen; Yang, Cheng; Huo, Yanyan; Yue, Weiwei

    2016-05-01

    An evanescent wave absorption (EWA) sensor based on tapered multimode fiber (TMMF) coated with monolayer graphene film for the detection of double-stranded DNA (DS-DNA) is investigated in this work. The TMMF is a silica multimode fiber (nominally at 62.5 μm), which was tapered to symmetric taper with waist diameters of ~30 μm and total length of ~3 mm. Monolayer graphene film was grown on a copper foil via chemical vapor deposition (CVD) technology and transferred onto skinless tapered fiber core via dry transfer technology. All the components of the sensor are coupled together by fusion splicer in order to eliminate the external disturbance. DS-DNA is created by the assembly of two relatively complemented oligonucleotides. The measurements are obtained by using a spectrometer in the optical wavelength range of 400-900 nm. With the increase of DS-DNA concentration, the output light intensity (OPLI) arisen an obvious attenuation. Importantly, the absorbance (A) and the DS-DNA concentrations shown a reasonable linear variation in a wide range of 5-400 μM. Through a series of comparison, the accuracy of TMMF sensor with graphene (G-TMMF) is much better than that without graphene (TMMF), which can be attributed to the molecular enrichment of graphene by π-π stacking.

  16. Characteristics of strain transfer and the reflected spectrum of a metal-coated fiber Bragg grating sensor

    Science.gov (United States)

    Kim, Sang-Woo

    2017-09-01

    Previous researchers have simulated strain transfer and spectrum of normal fiber Bragg grating (FBG) sensors with a polymer coating bonded on the structure. They only considered the shear stress in a polymer coating for the simulation. However, for metal-coated FBG sensors, not only shear stress but also axial stress in the metal coating should be reflected into the calculation because its axial stiffness is no longer negligible. Thus, the author investigated the strain transfer and reflected spectra of metal-coated FBG sensors by considering both shear stress and axial stress. The strain transfer analysis involved evaluating the strain profiles along the sensor by plotting an analytical solution, and validating the evaluated profiles with the results obtained by a finite element analysis (FEA). The solution was also verified by the experiments that used aluminum-coated FBG sensors bonded on a carbon fiber reinforced polymer (CFRP) composite specimen. A transfer-matrix (T-matrix) formulation and coupled mode theory were used to simulate the reflected spectra of metal-coated FBG sensors for the evaluated strain profile. In addition, the effect of mechanical and geometric parameters of the sensor was examined. The findings revealed that the strain transfer characteristics and reflected spectra deteriorated with increases in the thickness and Young's modulus of the metal coating due to the consideration of axial stress. It is the opposite results for the normal FBG sensor with a polymer coating. Furthermore, the results also indicated that the decrease in bonding thickness resulted in improved strain transfer and signal characteristics. Moreover, a bonding length of 14 mm was suitable in suppressing an asymmetric shape of the reflected spectrum and in achieving an accurate measurement. The results of the parametric study are expected to contribute to improve the measurement accuracy of metal-coated FBG sensors in actual applications. The analytical methodology can be

  17. Microstructural and strength stability of CVD SiC fibers in argon environment

    Science.gov (United States)

    Bhatt, Ramakrishna T.; Hull, David R.

    1991-01-01

    The room temperature tensile strength and microstructure of three types of commercially available chemically vapor deposited silicon carbide fibers were measured after 1, 10, and 100 hour heat treatments under argon pressures of 0.1 to 310 MPa at temperatures to 2100 C. Two types of fiber had carbon-rich surface coatings and the other contained no coating. All three fiber types showed strength degradation beyond 1400 C. Time and temperature of exposure had greater influence on strength degradation than argon pressure. Recrystallization and growth of near stoichiometric SiC grains appears to be the dominant mechanism for the strength degradation.

  18. Microstructural and strength stability of CVD SiC fibers in argon environments

    Science.gov (United States)

    Bhatt, Ramakrishna T.; Hull, David R.

    1991-01-01

    The room temperature tensile strength and microstructure of three types of commercially available chemically vapor deposited silicon carbide fibers were measured after 1, 10, and 100 hour heat treatments under argon pressures of 0.1 to 310 MPa at temperatures to 2100 C. Two types of fiber had carbon-rich surface coatings and the other contained no coating. All three fiber types showed strength degradation beyond 1400 C. Time and temperature of exposure had greater influence on strength degradation than argon pressure. Recrystallization and growth of near stoichiometric SiC grains appears to be the dominant mechanism for the strength degradation.

  19. Partitioning behavior of aromatic components in jet fuel into diverse membrane-coated fibers.

    Science.gov (United States)

    Baynes, Ronald E; Xia, Xin-Rui; Barlow, Beth M; Riviere, Jim E

    2007-11-01

    Jet fuel components are known to partition into skin and produce occupational irritant contact dermatitis (OICD) and potentially adverse systemic effects. The purpose of this study was to determine how jet fuel components partition (1) from solvent mixtures into diverse membrane-coated fibers (MCFs) and (2) from biological media into MCFs to predict tissue distribution. Three diverse MCFs, polydimethylsiloxane (PDMS, lipophilic), polyacrylate (PA, polarizable), and carbowax (CAR, polar), were selected to simulate the physicochemical properties of skin in vivo. Following an appropriate equilibrium time between the MCF and dosing solutions, the MCF was injected directly into a gas chromatograph/mass spectrometer (GC-MS) to quantify the amount that partitioned into the membrane. Three vehicles (water, 50% ethanol-water, and albumin-containing media solution) were studied for selected jet fuel components. The more hydrophobic the component, the greater was the partitioning into the membranes across all MCF types, especially from water. The presence of ethanol as a surrogate solvent resulted in significantly reduced partitioning into the MCFs with discernible differences across the three fibers based on their chemistries. The presence of a plasma substitute (media) also reduced partitioning into the MCF, with the CAR MCF system being better correlated to the predicted partitioning of aromatic components into skin. This study demonstrated that a single or multiple set of MCF fibers may be used as a surrogate for octanol/water systems and skin to assess partitioning behavior of nine aromatic components frequently formulated with jet fuels. These diverse inert fibers were able to assess solute partitioning from a blood substitute such as media into a membrane possessing physicochemical properties similar to human skin. This information may be incorporated into physiologically based pharmacokinetic (PBPK) models to provide a more accurate assessment of tissue dosimetry of

  20. All fiber-optic ultra-sensitive temperature sensor using few-layer MoS2 coated D-shaped fiber

    Science.gov (United States)

    Mohanraj, J.; Velmurugan, V.; Sathiyan, S.; Sivabalan, S.

    2018-01-01

    We experimentally demonstrate a novel all fiber-optic temperature sensor using Molybdenum disulfide (MoS2) nanosheets coated D-shaped fiber (DSF). The DSF exhibits a strong evanescent field interaction with the MoS2 nanosheets which in turn has good optical absorption that results in very high sensitivity. In addition, a few layer MoS2 exhibit high thermal conductivity and therefore highly suitable for temperature sensing. The proposed all fiber temperature sensor was investigated in the temperature range of 26 °C - 83 °C and achieved a maximum optical output power variation of 7 dB. Further, the experimental results show an ultrahigh sensitivity of 0.1211 dB/∘C, a linear correlation coefficient of 99.6 % and a better precision of 0.04 °C. Therefore, the proposed fiber-optic sensor is capable of measuring dynamic temperatures in a harsh environment.

  1. Graphene oxide decorated with silver nanoparticles as a coating on a stainless-steel fiber for solid-phase microextraction.

    Science.gov (United States)

    Wang, Licheng; Hou, Xiudan; Li, Jubai; Liu, Shujuan; Guo, Yong

    2015-07-01

    A novel graphene oxide decorated with silver nanoparticles coating on a stainless-steel fiber for solid-phase microextraction was prepared. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to characterize the coating surface and showed that silver nanoparticles were dispersed on the wrinkled graphene oxide surface. Coupled to gas chromatography with flame ionization detection, the extraction abilities of the fiber for polycyclic aromatic hydrocarbons were examined in the headspace solid-phase microextraction mode. The extraction parameters including adsorption time, adsorption temperature, salt concentration, desorption time and desorption temperature were investigated. Under the optimized condition, wide linearity with low limits of detection from 2 to 10 ng/L was obtained. The relative standard deviations for single-fiber repeatability and fiber-to-fiber reproducibility were less than 10.6 and 17.5%, respectively. The enrichment factors were from 1712.5 to 4503.7, showing the fiber has good extraction abilities. Moreover, the fiber exhibited a good stability and could be reused for more than 120 times. The established method was also applied for determination of polycyclic aromatic hydrocarbons in two real water samples and the recoveries of analytes ranged from 84.4-116.3% with relative standard deviations less than 16.2%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A metal organic framework-polyaniline nanocomposite as a fiber coating for solid phase microextraction.

    Science.gov (United States)

    Bagheri, Habib; Javanmardi, Hasan; Abbasi, Alireza; Banihashemi, Solmaz

    2016-01-29

    A metal organic framework-polyaniline (MOF/PANI) nanocomposite was electrodeposited on a stainless steel wire and used as a solid phase microextraction (SPME) fiber coating. The electropolymerization process was carried out under a constant deposition potential and applied to the corresponding aqueous electrolyte containing aniline and MOF particles. The employment of MOFs with their large and small cages and 3-D structures in synthesizing a nanocomposite was assumed to be efficient constitutes to induce more non-smooth and porous structures, approved by scanning electron microscopy (SEM) images. Three different MOFs were incorporated to synthesize the desired nanocomposites and the preliminary experiments showed that all of them, particularly the one containing MOF2, have higher extraction performances in compared with PANI. The applicability of the new fiber coating was examined by headspace-solid phase microextraction (HS-SPME) of some chlorobenzenes (CBs) from aqueous samples. Influencing parameters on the synthesize and extraction processes including the electrodeposition voltage and its duration time, the weight ratio of PANI and MOF, the ionic strength, desorption temperature and time, and extraction time and temperature were optimized. The developed method was validated by analyzing the spiked distilled water and gas chromatography-mass spectrometry (GC-MS). Under optimum condition, the relative standard deviation (RSD%) values for a double distilled water spiked with the selected CBs at 20ngL(-1) were 5-8% (n=3) and the detection limits were below 0.2ngL(-1). The linear dynamic range (LDR) of the method was in the concentration range of 0.5-1000ngL(-1) (R(2)>0.9994). The fiber-to-fiber reproducibility was found to be in the range of 4-7%. Eventually, various real-water samples were analyzed by the MOF/PANI-based HS-SPME and GC-MS and the relative recovery values were found to be in the range of 92-98%. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Deposition characteristics of titanium coating deposited on SiC fiber by cold-wall chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xian, E-mail: luo_shenfan@hotmail.com; Wu, Shuai; Yang, Yan-qing; Jin, Na; Liu, Shuai; Huang, Bin

    2016-12-01

    The deposition characteristics of titanium coating on SiC fiber using TiCl{sub 4}-H{sub 2}-Ar gas mixture in a cold-wall chemical vapor deposition were studied by the combination of thermodynamic analysis and experimental studies. The thermodynamic analysis of the reactions in the TiCl{sub 4}-H{sub 2}-Ar system indicates that TiCl{sub 4} transforms to titanium as the following paths: TiCl{sub 4} → TiCl{sub 3} → Ti, or TiCl{sub 4} → TiCl{sub 3} → TiCl{sub 2} → Ti. The experimental results show that typical deposited coating contains two distinct layers: a TiC reaction layer close to SiC fiber and titanium coating which has an atomic percentage of titanium more than 70% and that of carbon lower than 30%. The results illustrate that a carbon diffusion barrier coating needs to be deposited if pure titanium is to be prepared. The deposition rate increases with the increase of temperature, but higher temperature has a negative effect on the surface uniformity of titanium coating. In addition, appropriate argon gas flow rate has a positive effect on smoothing the surface morphology of the coating. - Highlights: • Both thermodynamic analysis and experimental studies were adopted in this work. • The transformation paths of TiCl{sub 4} to Ti is: TiCl{sub 4} → TiCl{sub 3} → Ti, or TiCl{sub 4} → TiCl{sub 3} → TiCl{sub 2} → Ti. • Typical deposited Ti coating on SiC fiber contained two distinct layers. • Deposition temperature is important on deposition rate and morphologies. • Appropriate argon gas flow rate has a positive effect on smoothing of the coating.

  4. Creep Behavior of Oxide/Oxide Composites with Monazite Fiber Coating at 1100 deg C in Air and in Steam Environments

    Science.gov (United States)

    2008-09-01

    for oxygen to enter the composite and attack the fibers. Some SiC/SiC composites use a pyrolytic carbon fiber coating to allow fiber/matrix interface...Fig. 3.5. Waterjet machining uses a computer-controlled nozzle that sprays water mixed with garnet particles at high pressures to precision-cut various

  5. The Evolution of Interfacial Sliding Stresses During Cyclic Push-in Testing of C- and BN-Coated Hi-Nicalon Fiber-Reinforced CMCs

    Science.gov (United States)

    Eldridge, J. I.; Bansal, N. P.; Bhatt, R. T.

    1998-01-01

    Interfacial debond cracks and fiber/matrix sliding stresses in ceramic matrix composites (CMCs) can evolve under cyclic fatigue conditions as well as with changes in the environment, strongly affecting the crack growth behavior, and therefore, the useful service lifetime of the composite. In this study, room temperature cyclic fiber push-in testing was applied to monitor the evolution of frictional sliding stresses and fiber sliding distances with continued cycling in both C- and BN-coated Hi-Nicalon SiC fiber-reinforced CMCs. A SiC matrix composite reinforced with C-coated Hi-Nical on fibers as well as barium strontium aluminosilicate (BSAS) matrix composites reinforced with BN-coated (four different deposition processes compared) Hi-Nicalon fibers were examined. For failure at a C interface, test results indicated progressive increases in fiber sliding distances during cycling in room air but not in nitrogen. These results suggest the presence of moisture will promote crack growth when interfacial failure occurs at a C interface. While short-term testing environmental effects were not apparent for failure at the BN interfaces, long-term exposure of partially debonded BN-coated fibers to humid air resulted in large increases in fiber sliding distances and decreases in interfacial sliding stresses for all the BN coatings, presumably due to moisture attack. A wide variation was observed in debond and frictional sliding stresses among the different BN coatings.

  6. Tilted Fiber Bragg Grating Sensor with Graphene Oxide Coating for Humidity Sensing.

    Science.gov (United States)

    Chiu, Yung-Da; Wu, Chao-Wei; Chiang, Chia-Chin

    2017-09-15

    In this study, we propose a tilted fiber Bragg grating (TFBG) humidity sensor fabricated using the phase mask method to produce a TFBG that was then etched with five different diameters of 20, 35, 50, 55 and 60 μm, after which piezoelectric inkjet technology was used to coat the grating with graphene oxide. According to the experimental results, the diameter of 20 μm yielded the best sensitivity. In addition, the experimental results showed that the wavelength sensitivity was -0.01 nm/%RH and the linearity was 0.996. Furthermore, the measurement results showed that when the relative humidity was increased, the refractive index of the sensor was decreased, meaning that the TFBG cladding mode spectrum wavelength was shifted. Therefore, the proposed graphene oxide film TFBG humidity sensor has good potential to be an effective relative humidity monitor.

  7. Bromothymol blue coated fiber optic Fabry-Perot interferometer for ammonia gas sensor

    Science.gov (United States)

    Pawar, Dnyandeo; Mane, S. A.; Kale, S. N.

    2017-04-01

    A single mode fiber is used in this study, in a Y-coupler mode; the mirror tip of which is coated with bromothymol blue (BTB), homogeneously mixed in polyvinyl alcohol (PVA) matrix. The setup operated at 1550 nm, and was used to sense extremely small quantities of ammonia gas, at room temperature. The sensor is able to detect ammonia in the range of 1.5 ppm to 150 ppm; with observed sensitivity in terms of wavelength shift of 0.7 nm. The sensor showed excellent reversibility with fast response and recovery time of the order of few seconds. The possible interaction of dye with ammonia was studied and compared with chloroform.

  8. Growth and Characterization of Carbon Nanofibers on Fe/C-Fiber Textiles Coated by Deposition-Precipitation and Dip-Coating.

    Science.gov (United States)

    Lee, Sang-Won; Lee, Chang-Seop

    2015-09-01

    This research was conducted to synthesize carbon nanofibers on C-fiber textiles, by thermal chemical vapor deposition (CVD) using Fe catalyst. The substrate, which was a carbon textile consisting of non-woven carbon fibers and attached graphite particles, was oxidized by nitric acid, before the deposition process. Hydroxyl groups were created on the C-fiber textile, due to the oxidization step. Fe(III) hydroxide was subsequently deposited on the oxidized surface of the C-fiber textile. To deposit ferric particles, two different methods were tested: (i) deposition-precipitation, and (ii) dip-coating. For the experiments using both types of catalyst deposition, the weight ratio of Fe to C-fiber textile was also varied. Ferric particles were reduced to iron after deposition, by using H2/N2 gas, and carbon nanofibers (CNFs) were grown by flowing ethylene gas. Properties of carbon nanofibers created like this were analyzed through Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), N2-sorption (BET), X-ray Diffraction (XRD), X-ray Photoelectron Spectoscopy (XPS), Thermal analysis (TG/DTA), and Raman spectroscopy. In the case of the deposition-precipitation method, the results show that the diameter of carbon nanofibers grew up to 40-60 nm and 30-55 nm, at which the weight ratios of Fe catalyst to C-fiber textiles were 1:30 and 1:70, respectively. When Fe particles were deposited by the dip-coating method, the diameter of carbon nanofibers grew up to 40-60 nm and 25-30 nm, for the ratios of Fe catalyst to C-fiber textiles of 1:10 and 1:30, respectively.

  9. Photocatalytic sterilization of TiO{sub 2} films coated on Al fiber

    Energy Technology Data Exchange (ETDEWEB)

    Luo Li [Department of Environmental Technology and Urban Planning, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Miao Lei [Japan Fine Ceramics Centre, Mutsuno, Atsuta-ku, Nagoya 456-8577 (Japan)], E-mail: littlemiaomiao@gmail.com; Tanemura, Sakae [Japan Fine Ceramics Centre, Mutsuno, Atsuta-ku, Nagoya 456-8577 (Japan); Tanemura, Masaki [Department of Environmental Technology and Urban Planning, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2008-02-25

    Photocatalytic TiO{sub 2} films were coated on Al fiber by sol-gel dip-coating method, and then annealed. The crystal structure and morphology of the films were performed by XRD, TEM and SEM. Photocatalytic sterilization of the films was investigated in O{sub 2} atmosphere through purifying the aqueous solution with facultative aerobe (Bacillus cereus), aerobe (Pseudomonas aeruginosa) and anaerobe (Staphylococcus aureus, Enterococcus faecalis and Escherichia coli). In the presence of O{sub 2}, it benefits to generate O{sub 2}{center_dot}{sup -} and {center_dot}OH at the first stage of the photocatalytic reaction, while the excess O{sub 2} restrains the anaerobe from reproducing and accelerates the reproducing for the aerobe at the second stage of reaction. As a result, it was found that the crystal of TiO{sub 2} films is anatase phase and the films have excellent sterilization effect against facultative aerobe and anaerobe. Nevertheless, it only decreased the bioactivity against aerobe in a short time.

  10. Preparation of graphene-coated solid-phase microextraction fiber and its application on organochlorine pesticides determination.

    Science.gov (United States)

    Ke, Yuanyuan; Zhu, Fang; Zeng, Feng; Luan, Tiangang; Su, Chengyong; Ouyang, Gangfeng

    2013-07-26

    The coating material determines the sensitivity and selectivity of solid-phase microextraction (SPME). Graphene is predicted to have remarkable properties, such as high thermal conductivity, superior mechanical properties, excellent electronic transport properties and good extraction ability. In this work we immobilized the graphene onto a stainless steel wire to obtain a novel SPME coating based on sol-gel technique. The new fiber possessed a homogeneous, porous surface and showed excellent thermal and solvent stability. Under the optimized conditions, its extraction efficiencies for seven organochlorine pesticides (OCPs) were higher than those of two commercial fibers (PDMS, 85μm; PDMS/DVB, 65μm). Using the self-made sol-gel-graphene SPME fiber, the limits of detections for seven OCPs were found to be ranged from 0.19ngL(-1) (o,p-DDT) to 18.3ngL(-1) (heptachlor). The repeatabilities for each single fiber were evaluated and the relative standard deviations (RSDs) ranged from 4.7% to 10.6%. The reproducibilities of fiber-to-fiber were 2.3-13.6%. The developed method was successfully applied to the determination of OCPs in rainwater. Hexachlorobenzene (62.7ng/L), trans-chlordance (79.6ng/L) and p,p-DDT (9.30ng/L) were detected. The relative recoveries ranged from 77.7% to 120%. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. High heat flux testing of mm thick tungsten coatings on carbon-fiber composites for the JT-60SA tokamak

    Science.gov (United States)

    Fukumoto, M.; Greuner, H.; Böswirth, B.; Elgeti, S.; Maier, H.; Neu, R.; Nakano, T.; Kuroki, N.; Noumi, K.; Takabatake, T.; Yoshida, N.

    2017-12-01

    High heat flux tests have been performed on 0.4 mm thick W coatings produced by vacuum plasma spraying on carbon-fiber composites (CFCs) for the future actively cooled W-coated CFC divertor target in JT-60SA. The surface temperature of the W coating increased up to 2000 °C at 15 MW m‑2 for 5 s. No severe morphological changes, for example, melting, cracking and delamination were observed although recrystallization and grain growth were found in the W coating. Cyclic loading at 15 MW m‑2 for 3 s with 50 cycles and additional 50 cycles with longer pulse length of 4 s produced again no severe morphological changes. Heat transfer analysis of the W-coated CFC sample during the high heat flux test showed that thermal resistance between W coatings and CFCs was negligibly low. This analysis also showed that the surface temperature of the 1 mm thick W coating on the actively cooled CFC monoblock divertor target in JT-60SA will be higher than the recrystallization temperature, 1200 °C, at the steady state heat flux of 15 MW m‑2. Therefore, a reduction of armor thickness of the future actively cooled W-coated CFC monoblock divertor target in JT-60SA could be necessary to decrease the surface temperature to less than the recrystallization temperature.

  12. Method for Forming Fiber Reinforced Composite Bodies with Graded Composition and Stress Zones

    Science.gov (United States)

    Singh, Mrityunjay (Inventor); Levine, Stanley R. (Inventor); Smialek, James A. (Inventor)

    1999-01-01

    A near-net, complex shaped ceramic fiber reinforced silicon carbide based composite bodies with graded compositions and stress zones is disclosed. To provide the composite a fiber preform is first fabricated and an interphase is applied by chemical vapor infiltration, sol-gel or polymer processes. This first body is further infiltrated with a polymer mixture containing carbon, and/or silicon carbide, and additional oxide, carbide, or nitride phases forming a second body. One side of the second body is spray coated or infiltrated with slurries containing high thermal expansion and oxidation resistant. crack sealant phases and the other side of this second body is coated with low expansion phase materials to form a third body. This third body consisting of porous carbonaceous matrix surrounding the previously applied interphase materials, is then infiltrated with molten silicon or molten silicon-refractory metal alloys to form a fourth body. The resulting fourth body comprises dense composites consisting of fibers with the desired interphase which are surrounded by silicon carbide and other second phases materials at the outer and inner surfaces comprising material of silicon, germanium, refractory metal suicides, borides, carbides, oxides, and combinations thereof The resulting composite fourth body has different compositional patterns from one side to the other.

  13. Insulation Materials Comprising Fibers Having a Partially Cured Polymer Coating Thereon, Articles Including Such Insulation Materials, and Methods of Forming Such Materials and Articles

    Science.gov (United States)

    Morgan, Richard E. (Inventor); Meeks, Craig L. (Inventor)

    2017-01-01

    Insulation materials have a coating of a partially cured polymer on a plurality of fibers, and the plurality of coated fibers in a cross-linked polymeric matrix. Insulation may be formed by applying a preceramic polymer to a plurality of fibers, heating the preceramic polymer to form a partially cured polymer over at least portions of the plurality of fibers, disposing the plurality of fibers in a polymeric material, and curing the polymeric material. A rocket motor may be formed by disposing a plurality of coated fibers in an insulation precursor, curing the insulation precursor to form an insulation material without sintering the partially cured polymer, and providing an energetic material over the polymeric material. An article includes an insulation material over at least one surface.

  14. Durability of fiber post-to-composite bonds achieved by physical vapor deposition and tribochemical silica coating.

    Science.gov (United States)

    Rathke, Andreas; Frehse, Henry; Muche, Rainer; Haller, Bernd

    2014-12-01

    To evaluate post-to-composite bonds in terms of their durability, achieved either by physical vapor deposition (PVD) or tribochemical silica coating (TSC) compared to coupling strategies for fiber posts at chairside. Thirty uncoated fiber posts (DT Light) each were either left untreated (control) or silanized with a one-bottle (Monobond Plus) or a two-bottle (Clearfil SE Bond/Porcelain Bond Activator) silane at the chairside. Thirty coated fiber posts each had already been silica coated and silanized by the manufacturer using PVD (DT Light SL) or TSC (DentinPost Coated) deposition techniques. Surface analysis was carried out by profilometry and x-ray microanalysis. All the posts were surrounded by 2-mm-thick disks of a dual-curing composite resin (MultiCore Flow). After water storage for 24 h at 37°C, the specimens in each group were randomly divided into three subgroups (n=10) and subjected to 0, 1500, and 20,000 thermocycles (5°C to 55°C) prior to push-out testing. Failure modes were evaluated by optical and scanning electron microscopy. The statistical significance was determined with two-way ANOVA, the Student-Newman-Keuls test, and Fisher's exact test. The conditioned posts had significantly higher interfacial bond strengths than the control posts after thermocycling (p0.05). Coatings deposited by TSC reached the highest bond values (pdelamination (pcomposite. PVD and TSC techniques enhanced the bond durability of fiber posts. TSC led to a superior post-tocomposite bond, probably based on more effective micromechanical adhesion due to the higher surface roughness.

  15. Osteogenesis of human adipose-derived stem cells on poly(dopamine)-coated electrospun poly(lactic acid) fiber mats

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chi-Chang, E-mail: chichang31@thu.edu.tw; Fu, Shu-Juan

    2016-01-01

    Electrospinning is a versatile technique to generate large quantities of micro- or nano-fibers from a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized electrospun nano-fibers and use a mussel-inspired surface coating to regulate adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared poly(lactic acid) (PLA) fibers coated with polydopamine (PDA). The morphology, chemical composition, and surface properties of PDA/PLA were characterized by SEM and XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. Increased focal adhesion kinase (FAK) and collagen I levels and enhanced cell attachment and cell cycle progression were observed upon an increase in PDA content. In addition, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on a pure PLA mat. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenesis differentiation. Our results demonstrate that the bio-inspired coating synthetic degradable PLA polymer can be used as a simple technique to render the surfaces of synthetic biodegradable fibers, thus enabling them to direct the specific responses of hADSCs. - Highlights: • A simple method of preparing electrospun poly(lactic acid) nanofibers coated with polydopamine • Enhanced adhesion and proliferation of hADSCs on a PDA/PLA mat • Increased focal adhesion kinase (FAK), collagen I levels, cell attachment and cell cycle progression with a high PDA content • Up-regulation of the Ang-1 and vWF proteins associated with angiogenesis differentiation of hADSCs is observed. • A promising method for bio-inspired surface modification on organic fiber substrates using PDA.

  16. Fiber

    Science.gov (United States)

    ... fiber you get from the food. Fiber-rich foods offer health benefits when eaten raw or cooked. Alternative Names Diet - fiber; Roughage; Bulk; Constipation - fiber Patient Instructions Constipation - ...

  17. Fabrication of novel nanoporous array anodic alumina solid-phase microextraction fiber coating and its potential application for headspace sampling of biological volatile organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhuomin [School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Wang Qingtang [Key Laboratory of Analysis and Detection for Food Safety of Ministry of Education, College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou, Fujian 350002 (China); Li Gongke, E-mail: cesgkl@mail.sysu.edu.cn [School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2012-05-21

    Highlights: Black-Right-Pointing-Pointer Nanoporous array anodic alumina (NAAA) SPME coating was originally prepared. Black-Right-Pointing-Pointer NAAA SPME coating achieved excellent enrichment capability and selectivity for VOCs. Black-Right-Pointing-Pointer NAAA SPME coating can be applied for the headspace sampling of biological VOCs. - Abstract: In the study, nanoporous array anodic alumina (NAAA) prepared by a simple, rapid and stable two-step anodic oxidization method was introduced as a novel solid-phase microextraction (SPME) fiber coating. The regular nanoporous array structure and chemical composition of NAAA SPME fiber coating was characterized and validated by scanning electron microscopy and energy dispersive spectroscopy, respectively. Compared with the commercial polydimethylsiloxane (PDMS) SPME fiber coating, NAAA SPME fiber coating achieved the higher enrichment capability (1.7-4.7 folds) for the mixed standards of volatile organic compounds (VOCs). The selectivity for volatile alcohols by NAAA SPME fiber coating demonstrated an increasing trend with the increasing polarity of alcohols caused by the gradually shortening carbon chains from 1-undecanol to 1-heptanol or the isomerization of carbon chains of some typical volatile alcohols including 2-ethyl hexanol, 1-octanol, 2-phenylethanol, 1-phenylethanol, 5-undecanol, 2-undecanol and 1-undecanol. Finally, NAAA SPME fiber coating was originally applied for the analysis of biological VOCs of Bailan flower, stinkbug and orange peel samples coupled with gas chromatography-mass spectrometry (GC-MS) detection. Thirty, twenty-seven and forty-four VOCs of Bailan flower, stinkbug and orange peel samples were sampled and identified, respectively. Moreover, the contents of trace 1-octanol and nonanal of real orange peel samples were quantified for the further method validation with satisfactory recoveries of 106.5 and 120.5%, respectively. This work proposed a sensitive, rapid, reliable and convenient

  18. Design of a novel photonic crystal fiber filter based on gold-coated and elliptical air holes

    Science.gov (United States)

    Zhao, Yunyan; Li, Shuguang; Liu, Qiang; Wang, Xinyu

    2017-11-01

    In recent years, photonic crystal fibers have played an important role in the field of optical communications, and the addition of metal materials to photonic crystal fibers have offered new ways to improve the transmission characteristics of optical fibers. We design a new type of gold-coated photonic crystal filter, which utilizes the surface plasmon resonance effect, and study it by using the finite element method. In this paper, we optimise the structure parameters and analyze the numerical results. The numerical results show that the thickness of metal layer and the air holes near the fiber core strongly affect the performance of the polarization filter. For the operating wavelength of 1550 nm, the loss in the y-polarization direction can be as high as 906.9 dB/cm, which is much larger than the x-polarization direction. When the fiber length is longer than 100 μm, the crosstalk in the wavelength range from 1.4 μm to 1.9 μm is greater than 20 dB. The proposed optical fiber can find application as an optical fiber polarization filter.

  19. Flexible nanocrystal-coated glass fibers for high-performance thermoelectric energy harvesting.

    Science.gov (United States)

    Liang, Daxin; Yang, Haoran; Finefrock, Scott W; Wu, Yue

    2012-04-11

    Recent efforts on the development of nanostructured thermoelectric materials from nanowires (Boukai, A. I.; et al. Nature 2008, 451, (7175), 168-171; Hochbaum, A. I.; et al. Nature 2008, 451, (7175), 163-167) and nanocrystals (Kim, W.; et al. Phys. Rev. Lett. 2006, 96, (4), 045901; Poudel, B.; et al. Science 2008, 320, (5876), 634-638; Scheele, M.; et al. Adv. Funct. Mater. 2009, 19, (21), 3476-3483; Wang, R. Y.; et al. Nano Lett. 2008, 8, (8), 2283-2288) show the comparable or superior performance to the bulk crystals possessing the same chemical compositions because of the dramatically reduced thermal conductivity due to phonon scattering at nanoscale surface and interface. Up to date, the majority of the thermoelectric devices made from these inorganic nanostructures are fabricated into rigid configuration. The explorations of truly flexible composite-based flexible thermoelectric devices (See, K. C.; et al. Nano Lett. 2010, 10, (11), 4664-4667) have thus far achieved much less progress, which in principle could significantly benefit the conversion of waste heat into electricity or the solid-state cooling by applying the devices to any kind of objects with any kind of shapes. Here we report an example using a scalable solution-phase deposition method to coat thermoelectric nanocrystals onto the surface of flexible glass fibers. Our investigation of the thermoelectric properties yields high performance comparable to the state of the art from the bulk crystals and proof-of-concept demonstration also suggests the potential of wrapping the thermoelectric fibers on the industrial pipes to improve the energy efficiency. © 2012 American Chemical Society

  20. Two-photon excited fluorescence from a pseudoisocyanine-attached gold-coated tip via a thin tapered fiber under a weak continuous wave excitation.

    Science.gov (United States)

    Ren, Fang; Takashima, Hideaki; Tanaka, Yoshito; Fujiwara, Hideki; Sasaki, Keiji

    2013-11-18

    A simple tapered fiber based photonic-plasmonic hybrid nanostructure composed of a thin tapered fiber and a pseudoisocyanine (PIC)-attached Au-coated tip was demonstrated. Using this simple hybrid nanostructure, we succeeded in observing two-photon excited fluorescence from the PIC dye molecules under a weak continuous wave excitation condition. From the results of the tip-fiber distance dependence and excitation polarization dependence, we found that using a thin tapered fiber and an Au-coated tip realized efficient coupling of the incident light (~95%) and LSP excitation at the Au-coated tip, suggesting the possibility of efficiently inducing two-photon excited fluorescence from the PIC dye molecules attached on the Au-coated tip. This simple photonic-plasmonic hybrid system is one of the promising tools for single photon sources, highly efficient plasmonic sensors, and integrated nonlinear plasmonic devices.

  1. Au-coated ZnO nanorods on stainless steel fiber for self-cleaning solid phase microextraction-surface enhanced Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bo; Shi, Yu-e; Cui, Jingcheng; Liu, Zhen; Zhang, Xiaoli; Zhan, Jinhua, E-mail: jhzhan@sdu.edu.cn

    2016-06-07

    Solid phase microextraction-surface enhanced Raman spectroscopy (SPME–SERS), combining the pretreatment and determination functions, has been successfully used in environmental analysis. In this work, Au-coated ZnO nanorods were fabricated on stainless steel fiber as a self-cleaning SERS-active SPME fiber. The ZnO nanorods grown on stainless steel fiber were prepared via a simple hydrothermal approach. Then the obtained nanostructures were decorated with Au nanoparticles through ion-sputtering at room temperature. The obtained SERS-active SPME fiber is a reproducible sensitivity sensor. Taking p-aminothiophenol as the probe molecule, the RSD value of the SERS-active SPME fiber was 8.9%, indicating the fiber owned good uniformity. The qualitative and quantitative detection of crystal violet and malachite green was also achieved. The log–log plot of SERS intensity to crystal violet and malachite green concentration showed a good linear relationship. Meanwhile, this SERS-active SPME fiber can achieve self-cleaning owning to the excellent photocatalytic performance of ZnO nanorods. Crystal violet was still successfully detected even after five cycles, which indicated the high reproducibility of this SERS-active SPME fiber. - Graphical abstract: Au-coated ZnO NRs on stainless steel fiber were used as SERS-active SPME fiber with good extraction effect, high SERS sensitivity. Self-cleaning function of the fiber was achieved based on the photocatalytic degradation property of ZnO nanorods by UV irradiation. - Highlights: • Au-coated ZnO nanorods on stainless steel fiber as a SERS-active SPME fiber was fabricated. • The SERS-active SPME fiber can directly extract and detect the crystal violet and malachite green. • The SERS-active SPME fiber owns good extraction effect, and high SERS sensitivity. • Self-cleaning property of the fiber were achieved based on the photocatalytic degradation property of ZnO.

  2. Photonic crystal fiber interferometric pH sensor based on polyvinyl alcohol/polyacrylic acid hydrogel coating.

    Science.gov (United States)

    Hu, Pengbing; Dong, Xinyong; Wong, Wei Chang; Chen, Li Han; Ni, Kai; Chan, Chi Chiu

    2015-04-01

    We present a simple photonic crystal fiber interferometer (PCFI) that operates in reflection mode for pH measurement. The sensor is made by coating polyvinyl alcohol/polyacrylic acid (PVA/PAA) hydrogel onto the surface of the PCFI, constructed by splicing a stub of PCF at the distal end of a single-mode fiber with its free end airhole collapsed. The experimental results demonstrate a high average sensitivity of 0.9 nm/pH unit for the 11 wt.% PVA/PAA coated sensor in the pH range from 2.5 to 6.5. The sensor also displays high repeatability and stability and low cross-sensitivity to temperature. Fast, reversible rise and fall times of 12 s and 18 s, respectively, are achieved for the sensor time response.

  3. Ultraviolet photoinitiated on-fiber copolymerization of ionic liquid sorbent coatings for headspace and direct immersion solid-phase microextraction.

    Science.gov (United States)

    Ho, Tien D; Yu, Honglian; Cole, William T S; Anderson, Jared L

    2012-11-06

    A high-throughput method for the production of solid-phase microextraction (SPME) sorbent coatings via ultraviolet (UV) photoinitiated copolymerization of ionic liquid (IL) monomers on a fused silica support is described. The copolymerization of monocationic and dicationic IL cross-linkers was performed "on-fiber" using UV initiated free radical polymerization. Mixtures composed of various amounts of the IL cross-linker, UV initiator (DAROCUR 1173), and IL monomer were dip-coated onto an etched and derivatized fused silica support and placed in a high-capacity UV reactor. The method requires no organic dispersive solvent and is much more rapid compared to traditional methods in which polymeric ionic liquid (PIL) sorbent coatings are prepared by 2,2'-azobis(2-methylpropionitrile) (AIBN)-initiated polymerization. Two ionic liquid-based cross-linkers, namely, 1,8-di (3-vinylimidazolium) octane dibromide ([(VIM)(2)C(8)] 2[Br]) and 1,12-di (3-vinylimidazolium) dodecane dibromide ([(VIM)(2)C(12)] 2[Br]), were copolymerized with an ionic liquid monomer, 1-vinyl-3-hexylimidazolium chloride ([VHIM][Cl]), to produce polar cross-linked PIL-based SPME sorbent coatings. The cross-linking and immobilization of these coatings make them particularly applicable in direct immersion SPME. The coatings were applied in the extraction of polar analytes, including alcohols, aldehydes, and esters, from aqueous solutions using headspace and direct immersion SPME gas chromatography mass spectrometry (GC/MS). Compared to linear PIL-based sorbent coatings containing the same anions, the cross-linked PIL-based coatings exhibited higher thermal stability and lower bleed, making them ideal for GC/MS. Recovery experiments were performed in deionized, well, and river water. The structural integrity of the sorbent coatings, as well as their analytical precision, was not diminished after 90 extractions from complex samples using headspace and direct immersion SPME.

  4. Interfacial microstructure and mechanical properties of Cf/AZ91D composites with TiO2and PyC fiber coatings.

    Science.gov (United States)

    Li, Shaolin; Qi, Lehua; Zhang, Ting; Ju, Luyan; Li, Hejun

    2017-10-01

    In spite of the effectiveness of the fiber coatings on interface modification of carbon fiber reinforced magnesium matrix composites, the cost and exclusive equipment for the coatings preparation are usually ignored during research work. In this paper, pyrolytic carbon (PyC) and TiO 2 were coated on carbon fiber surface to study the effects of fiber coatings on interfacial microstructure and mechanical properties of carbon fiber reinforced AZ91D composites (C f /AZ91D composites). It was indicated that both the two coatings could modify the interface and improve the mechanical properties of the composites. The ultimate tensile strength of the TiO 2 -C f /AZ91D and the PyC-C f /AZ91D composite were 333MPa and 400MPa, which were improved by 41.7% and 70.2% respectively, compared with the untreated-C f /AZ91D composite. The microstructure observation revealed that the strengthening of the composites relied on fiber integrity and moderate interfacial bonding. MgO nano-particles were generated at the interface due to the reaction of TiO 2 with Mg in the TiO 2 -C f /AZ91D composite. The volume expansion resulting from the reaction let to disordered intergranular films and crystal defects at the interface. The fibers were protected and the interfacial reaction was restrained by PyC coating in the PyC-C f /AZ91D composite. The principle to select the coating of fiber was proposed by comparing the effectiveness and cost of the coatings. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Clinical investigation into the observation that silicon carbide coating on cobalt chromium stents leads to early differentiating functional endothelial layer, increased safety and DES-like recurrent stenosis rates: results of the PRO-Heal Registry (PRO-Kinetic enhancing rapid in-stent endothelialisation).

    Science.gov (United States)

    Dahm, Johannes B; Willems, Tine; Wolpers, Hans Georg; Nordbeck, Hans; Becker, Jürgen; Ruppert, Jörg

    2009-01-01

    Recurrent stenosis and stent thrombosis are still major concerns after drug eluting stent placement which inhibits not only the restenostic process but endothelialisation as well. In contrast, through accelerating rapid endothelialisation and development of an earlier functional endothelial layer, passive coatings have shown encouraging results. The objective of the present study was to investigate the clinical outcome and rate of recurrent stenosis of silicon carbide passive coated cobalt chromium stents (PROKinetic Coronary Stent with PROBIO coating, Biotronik AG, Switzerland) on restenosis after percutaneous coronary intervention. Percutaneous coronary stent deployment was carried out in 161 lesions in 145 consecutive patients. The primary combined endpoint was the rate of target-lesion revascularisation (TLR) and late lumen loss; the secondary endpoints were the procedural success and the major adverse cardiac events at 6-months follow-up. Out of 145 patients, 141 were successfully amenable to a silicon carbide coated stent (PRO-Kinetic, Biotronik AG, Switzerland) implantation (97.2% procedural success). At follow-up, the late loss was 0.75 +/- 0.71 mm. (in-stent) respectively 0.79 +/- 0.72 mm (in-segment), TLR was 4.9% and MACE was 5.6%. By augmenting rapid endothelialisation and development of an earlier functional endothelial layer, silicon carbide (PROBIO) as a passive coating on cobalt chromium stents has shown encouraging results relative to success rates, clinical outcome, TLR and late-loss in a cohort of patients with extended coronary artery disease.

  6. Fiber-reinforced resin coating for endocrown preparations: a technical report.

    Science.gov (United States)

    Rocca, G T; Rizcalla, N; Krejci, I

    2013-01-01

    Coronal rehabilitation of endodontically treated posterior teeth is still a controversial issue. Although the use of classical crowns supported by radicular metal posts remains widespread in dentistry, their invasiveness has been largely criticized. New materials and therapeutic options based entirely on adhesion are available nowadays, from direct composite resins to indirect endocrowns. They allow for a more conservative, faster, and less expensive dental treatment. However, the absence of a metal or high-strength ceramic substructure as in full-crown restorations can expose this kind of restoration to a higher risk of irreversible fracture in case of crack propagation. The aim of this case report is to present a technique to reinforce the cavity of an endodontically treated tooth by incorporating a fiber-reinforced composite (FRC) layer into the resin coating of the tooth preparation, before the final impressions of the cavity. This technique allows the use of FRCs in combination with any kind of restorative material for an adhesive overlay/endocrown.

  7. Cobalt oxide nanoparticles as a novel high-efficiency fiber coating for solid phase microextraction of benzene, toluene, ethylbenzene and xylene from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad Bagher, E-mail: MB.Gholivand@yahoo.com [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Shamsipur, Mojtaba; Shamizadeh, Mohammad [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Moradian, Rostam; Astinchap, Bandar [Physics Department, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of); Nano Technology Research Laboratory, Razi University, Kermanshah (Iran, Islamic Republic of)

    2014-04-01

    Highlights: • Co{sub 3}O{sub 4} nanoparticles were introduced as a novel SPME fiber coating. • The fiber was evaluated for the extraction of BTEX in combination with GC–MS. • The fiber showed extraction efficiencies better than a PDMS fiber toward BTEX. • The fiber was successfully applied to the determination of BTEX in real samples. - Abstract: In this work cobalt oxide nanoparticles were introduced for preparation of a novel solid phase microextraction (SPME) fiber coating. Chemical bath deposition (CBD) technique was used in order for synthesis and immobilization of the Co{sub 3}O{sub 4} nanomaterials on a Pt wire for fabrication of SPME fiber. The prepared cobalt oxide coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The fiber was evaluated for the extraction of benzene, toluene, ethylbenzene and xylene (BTEX) in combination with GC–MS. A simplex optimization method was used to optimize the factors affecting the extraction efficiency. Under optimized conditions, the proposed fiber showed extraction efficiencies comparable to those of a commercial polydimethylsiloxane (PDMS) fiber toward the BTEX compounds. The repeatability of the fiber and its reproducibility, expressed as relative standard deviation (RSD), were lower than about 11%. No significant change was observed in the extraction efficiency of the new SPME fiber after over 50 extractions. The fiber was successfully applied to the determination of BTEX compounds in real samples. The proposed nanostructure cobalt oxide fiber is a promising alternative to the commercial fibers as it is robust, inexpensive and easily prepared.

  8. Process for preparing fine-grain metal carbide powder

    Science.gov (United States)

    Kennedy, C.R.; Jeffers, F.P.

    Fine-grain metal carbide powder suitable for use in the fabrication of heat resistant products is prepared by coating bituminous pitch on SiO/sub 2/ or Ta/sub 2/O/sub 5/ particles, heating the coated particles to convert the bituminous pitch to coke, and then heating the particles to a higher temperature to convert the particles to a carbide by reaction of said coke therewith.

  9. Influence of Fiber Orientation on Single-Point Cutting Fracture Behavior of Carbon-Fiber/Epoxy Prepreg Sheets

    Directory of Open Access Journals (Sweden)

    Yingying Wei

    2015-10-01

    Full Text Available The purpose of this article is to investigate the influences of carbon fibers on the fracture mechanism of carbon fibers both in macroscopic view and microscopic view by using single-point flying cutting method. Cutting tools with three different materials were used in this research, namely, PCD (polycrystalline diamond tool, CVD (chemical vapor deposition diamond thin film coated carbide tool and uncoated carbide tool. The influence of fiber orientation on the cutting force and fracture topography were analyzed and conclusions were drawn that cutting forces are not affected by cutting speeds but significantly influenced by the fiber orientation. Cutting forces presented smaller values in the fiber orientation of 0/180° and 15/165° but the highest one in 30/150°. The fracture mechanism of carbon fibers was studied in different cutting conditions such as 0° orientation angle, 90° orientation angle, orientation angles along fiber direction, and orientation angles inverse to the fiber direction. In addition, a prediction model on the cutting defects of carbon fiber reinforced plastic was established based on acoustic emission (AE signals.

  10. Oxidation of hydrogen-passivated silicon surfaces by scanning near-field optical lithography using uncoated and aluminum-coated fiber probes

    DEFF Research Database (Denmark)

    Madsen, Steen; Bozhevolnyi, Sergey I.; Birkelund, Karen

    1997-01-01

    Optically induced oxidation of hydrogen-passivated silicon surfaces using a scanning near-field optical microscope was achieved with both uncoated and aluminum-coated fiber probes. Line scans on amorphous silicon using uncoated fiber probes display a three-peak profile after etching in potassium...

  11. Optical fiber taste sensors using potential sensitive dye coatings. Makuden'i kanjusei shikisomaku wo mochiita hikari fiber mikaku sensor

    Energy Technology Data Exchange (ETDEWEB)

    Yamakawa, S.; Yamaguchi, A. (Toyama National College of Maritime Technology, Toyama (Japan))

    1992-12-20

    The present paper proposes a new taste recognition system using optical response patterns from multi-channel optical fiber sensors having potential sensitive dye coatings. It was found that the sensors give large changes in optical absorption spectra of the dyes when they are immersed in various taste solutions. Consequently, it was shown that the sensors can be used as a taste sensor. Six dyes, which give large changes in dye absorption, were selected from twenty dyes and used for six-channel optical fiber taste sensors array. The absorption spectra change data were processed by multiple discriminant analysis and neural networks using back-propagation algorithm. From the analytical results, it was demonstrated that salty (NaCl), bitter (quinidine), sweet (sucrose), sour (HCl), and umami (sodium glutamate) substances can be recognized from each other by using the optical taste sensor system. 11 refs., 8 figs., 2 tabs.

  12. Influence of polysaccharide-based edible coatings as carriers of prebiotic fibers on quality attributes of ready-to-eat fresh blueberries.

    Science.gov (United States)

    Alvarez, María V; Ponce, Alejandra G; Moreira, María R

    2017-10-24

    Little information is available regarding the effect of dietary fibers added into edible coatings on quality attributes of ready-to-eat fruits. The aim of this study was to evaluate the effects of sodium alginate (AL) and chitosan (CH) edible coatings enriched with four different dietary fibers (apple fiber, orange fiber, inulin and oligofructose) on microbiological, nutritional, physico-chemical and sensorial properties of ready-to-eat fresh blueberries stored for 18 days at 5 °C. The most encouraging results were found for CH coatings (with and without fibers) which significantly inhibited the growth of mesophilic bacteria and yeasts/molds (reductions up to 1.9 log CFU g-1 ), reduced decay rate by more than 50%, enhanced antioxidant properties, retained fruit firmness, delayed off-odor development and improved overall visual quality of blueberries. Oligofructose and orange fiber added to CH coatings enhanced antioxidant properties of fruits and allowed higher reductions in yeast/mold counts compared to the use of CH alone. CH-based coatings enriched with inulin, oligofructose and apple fiber extended sensory shelf life of blueberries by 6 days. AL coatings (with and without fiber) allowed delaying fungal decay and also retaining antioxidant properties but did not improve the microbiological and sensory quality of fruits. The results proved that fiber-enriched CH treatments allowed the maintenance of freshness and the improvement of the quality of ready-to-eat blueberries. It might be an interesting option to offer consumers a healthy product with prebiotic potential and an extended shelf life. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  13. One-directional uniformly coated fibers, method of preparation, and uses therefor

    Science.gov (United States)

    Newkirk, L.R.; Valencia, F.A.; Riley, R.E.; Wallace, T.C. Sr.

    A problem addressed by this invention was how to obtain very long lengths of refractory metal-coated multifilamentary yarns having a uniform coating on the filaments which make up each yarn, the coating being uniform throughout the length of the yarn such that the coated yarns are suitable for being woven and are suitable for a variety of other uses. The solution is a continuous process which employs a chemical vapor deposition reaction at relatively low temperature and pressure and a separation of the gaseous reaction products from the coated yarn prior to allowing the coated yarn to cool.

  14. MWCNT Coated Free-Standing Carbon Fiber Fabric for Enhanced Performance in EMI Shielding with a Higher Absolute EMI SE

    Directory of Open Access Journals (Sweden)

    Sudesh Jayashantha Pothupitiya Gamage

    2017-11-01

    Full Text Available A series of multi-walled carbon nanotube (MWCNT coated carbon fabrics was fabricated using a facile dip coating process, and their performance in electrical conductivity, thermal stability, tensile strength, electromagnetic interference (EMI and shielding effectiveness (SE was investigated. A solution of MWCNT oxide and sodium dodecyl sulfate (SDS in water was used in the coating process. MWCNTs were observed to coat the surfaces of carbon fibers and to fill the pores in the carbon fabric. Electrical conductivity of the composites was 16.42 S cm−1. An EMI shielding effectiveness of 37 dB at 2 GHz was achieved with a single layer of C/C composites, whereas the double layers resulted in 68 dB EMI SE at 2.7 GHz. Fabricated composites had a specific SE of 486.54 dB cm3 g−1 and an absolute SE of approximately 35,000 dB cm2 g−1. According to the above results, MWCNT coated C/C composites have the potential to be used in advanced shielding applications such as aerospace and auto mobile electronic devices.

  15. Analysis of surface plasmon resonance based bimetal coated tapered fiber optic sensor with enhanced sensitivity through radially polarized light

    Science.gov (United States)

    Goswami, Nabamita; Chauhan, Kamlesh Kumar; Saha, Ardhendu

    2016-11-01

    The presented proposal of surface plasmon resonance (SPR) configuration with tapered fiber structure and radially polarized light beam is a new and different analysis towards the sensitivity enhancement in the field of SPR based fiber optic sensors. Here the taper waist region of optical fiber having diameter around 330 μm is deposited with 40 nm thin Ag layer, 10 nm thin Au layer and the sensing layer with refractive index 1.333-1.353 respectively for achieving the bimetal coated taper fiber optic sensor with SPR configuration. The cylindrical symmetry and special radial field distribution of radially polarized light make its more interesting SPR study and leads to the enhanced excitation of surface plasmon wave. This results 10 times better sensitivity of fiber optic sensor output response as compared to p-polarized light beam with wavelength interrogation technique and 2.307 times better sensitivity with intensity interrogation technique. Also including the temperature effect in proposed taper bimetallic structure, this sensitivity analysis provides an evidence, for exploring a new idea towards the enhanced excitation of SPR which expedites the new avenues in the field of sensor applications with radially polarized light.

  16. Coating of optical fiber with a smart thermosensitive polymer for the separation of phthalate esters by solid-phase microextraction.

    Science.gov (United States)

    Hashemi-Moghaddam, Hamid; Maddah, Setayesh

    2018-02-01

    A solid-phase microextraction fiber was prepared by coating an optical fiber with a temperature-sensitive polymer to determine phthalate esters. N-Isopropylacrylamide and N,N'-methylenebisacrylamide were used as the monomer and the cross linker, respectively. The fabricated fiber was characterized by FTIR spectroscopy, thermogravimetric analysis, and scanning electron microscopy. During extraction, important factors such as extraction time, pH, temperature, and ionic strength were optimized. The fabricated fiber, which is firm, inexpensive, stable, and efficient, is a vital material used in solid-phase microextraction. Under optimum conditions, the calibration curve was linear and in the range of 1-20 μg/L (r 2  = 0.9747). The high extraction efficiency was obtained for phthalates with a detection limit of 0.12 μg/L. The fabricated fiber was successfully applied to the solid-phase micro extraction of phthalates from water samples after its extraction, followed by gas chromatography with flame ionization detection. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Properties and characterization of multilayers of carbides and diamond-like carbon

    NARCIS (Netherlands)

    Strondl, C.; Kolk, G.J. van der; Hurkmans, T.; Fleischer, W.; Trinh, T.; Marcolino Carvalho, Nuno; Hosson, J.Th.M. de

    Metal containing diamond-like carbon (Me-DLC) coatings are widely applied in industrial applications. Normally, the coatings are produced with small inclusions of carbide forming elements like the 3d, 4d or 5d metals, or Si or B. The small carbide islands have sizes of approximately 2-20 nm. The

  18. Microstructure and Tensile Properties of BN/SiC Coated Hi-Nicalon, and Sylramic SiC Fiber Preforms. Revised

    Science.gov (United States)

    Bhatt, Ramakrishna T.; Chen, Yuan L.; Morscher, Gregory N.

    2002-01-01

    Batch to batch and within batch variations, and the influence of fiber architecture on room temperature physical and tensile properties of BN/SiC coated Hi-Nicalon and Sylramic SiC fiber preform specimens were determined. The three fiber architectures studied were plain weave (PW), 5-harness satin (5HS), and 8-harness satin (8HS). Results indicate that the physical properties vary up to 10 percent within a batch, and up to 20 percent between batches of preforms. Load-reload (Hysteresis) and acoustic emission methods were used to analyze damage accumulation occurring during tensile loading. Early acoustic emission activity, before observable hysteretic behavior, indicates that the damage starts with the formation of nonbridged tunnel cracks. These cracks then propagate and intersect the load bearing "0 deg" fibers giving rise to hysteretic behavior. For the Hi-Nicalon preform specimens, the onset of "0 deg" bundle cracking stress and strain appeared to be independent of the fiber architecture. Also, the "0 deg" fiber bundle cracking strain remained nearly the same for the preform specimens of both fiber types. TEM analysis indicates that the CVI BN interface coating is mostly amorphous and contains carbon and oxygen impurities, and the CVI SiC coating is crystalline. No reaction exists between the CVI BN and SiC coating.

  19. Characterization of silicon-silicon carbide ceramic derived from carbon-carbon silicon carbide composites

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Vijay K. [Indian Institute of Technology, Varanasi (India). Dept. of Mechanical Engineering; Krenkel, Walter [Univ. of Bayreuth (Germany). Dept. of Ceramic Materials Engineering

    2013-04-15

    The main objective of the present work is to process porous silicon - silicon carbide (Si - SiC) ceramic by the oxidation of carboncarbon silicon carbide (C/C - SiC) composites. Phase studies are performed on the oxidized porous composite to examine the changes due to the high temperature oxidation. Further, various characterization techniques are performed on Si- SiC ceramics in order to study the material's microstructure. The effects of various parameters such as fiber alignment (twill weave and short/chopped fiber) and phenolic resin type (resol and novolak) are characterized.

  20. Coating applications to natural fiber composites to improve their physical, surface and water absorption characters

    Science.gov (United States)

    Natural (organic) fibers are used in reinforced composites and natural fiber composites (NFCs). These fibers have advantages over synthetic composites such as high mechanical properties, lower densities and biodegradablity. However, one major disadvantage of NFCs is their hydrophilicity. In this stu...

  1. The Mechanical and Tribology Properties of Sputtered Titanium Aluminum Nitride Coating on the Tungsten Carbide Insert Tool in the Dry Turning of Tool Steel

    Directory of Open Access Journals (Sweden)

    Esmar Budi

    2015-02-01

    Full Text Available The effect of the sputtering parameters on the mechanical tribology properties of Titanium Aluminum Nitride coating on the tungsten cabide insert tool in the dry turning of tool steel has been investigated. The coating was deposited using a Direct Current magnetron sputtering system with various substrate biases (-79 to -221 V and nitrogen flow rates (30 to 72 sccm. The dry turning test was carried out on a Computer Numeric Code machine using an optimum cutting parameter setting. The results show that the lowest flank wear (~0.4 mm was achieved using a Titanium Aluminum Nitride-coated tool that was deposited at a high substrate bias (-200 V and a high nitrogen flow rate (70 sccm. The lowest flank wear was attributed to high coating hardness.

  2. Response Characterization of a Fiber Optic Sensor Array with Dye-Coated Planar Waveguide for Detection of Volatile Organic Compounds

    Directory of Open Access Journals (Sweden)

    Jae-Sung Lee

    2014-07-01

    Full Text Available We have developed a multi-array side-polished optical-fiber gas sensor for the detection of volatile organic compound (VOC gases. The side-polished optical-fiber coupled with a polymer planar waveguide (PWG provides high sensitivity to alterations in refractive index. The PWG was fabricated by coating a solvatochromic dye with poly(vinylpyrrolidone. To confirm the effectiveness of the sensor, five different sensing membranes were fabricated by coating the side-polished optical-fiber using the solvatochromic dyes Reinhardt’s dye, Nile red, 4-aminophthalimide, 4-amino-N-methylphthalimide, and 4-(dimethylaminocinnamaldehyde, which have different polarities that cause changes in the effective refractive index of the sensing membrane owing to evanescent field coupling. The fabricated gas detection system was tested with five types of VOC gases, namely acetic acid, benzene, dimethylamine, ethanol, and toluene at concentrations of 1, 2,…,10 ppb. Second-regression and principal component analyses showed that the response properties of the proposed VOC gas sensor were linearly shifted bathochromically, and each gas showed different response characteristics.

  3. Influence of fiber type and coating on the composite properties of EPDM compounds reinforced with short aramid fibers

    NARCIS (Netherlands)

    Hintze, C.; Sadatshirazi, S.; Wiessner, S.; Talma, Auke; Heinrich, G.; Noordermeer, Jacobus W.M.

    2013-01-01

    There is a renewed interest in the application of short aramid fibers in elastomers because of the considerable improvement in mechanical and dynamic properties of the corresponding rubber composites. Possible applications of short aramid fiber–reinforced elastomers are tires, dynamically loaded

  4. Pathology of silicon carbide pneumoconiosis.

    Science.gov (United States)

    Massé, S; Bégin, R; Cantin, A

    1988-03-01

    Silicon carbide is a widely used synthetic abrasive manufactured by heating silica and coke in electric furnaces at 2400 degrees C. Until recently it had been considered a relatively inert dust in humans and animals. However, several roentgenologic surveys had revealed lesions similar to low-grade silicosis. A recent epidemiological study has revealed a 35% incidence of pulmonary problems. Tissues from three such workers were available for light microscopy. A mixed pneumoconiosis was found, and lesions can be summarized as follows: (a) abundance of intraalveolar macrophages associated with a mixture of inhaled particles including carbon, silicon, pleomorphic crystals, silicon carbide, and ferruginous bodies showing a thin black central core; (b) nodular fibrosis, generally profuse, containing silica and ferruginous bodies and associated with large amount of carbon pigment; (c) interstitial fibrosis, less prominent than the nodular form; (d) carcinoma in two cases. We believe this pneumoconiosis is sufficiently characteristic to be recognized as a distinct entity. The Stanton hypothesis on fiber properties and carcinogenesis could be applied to silicon carbide dust. At present, it appears that the occupational hazard is limited to the manufacturing process and powdered product used in some industries.

  5. In vivo Raman measurement of levofloxacin lactate in blood using a nanoparticle-coated optical fiber probe

    Science.gov (United States)

    Liu, Shupeng; Rong, Ming; Zhang, Heng; Chen, Na; Pang, Fufei; Chen, Zhenyi; Wang, Tingyun; Yan, Jianshe

    2016-01-01

    Monitoring drug concentrations in vivo is very useful for adjusting a drug dosage during treatment and for drug research. Specifically, cutting-edge “on-line” drug research relies on knowing how drugs are metabolized or how they interact with the blood in real-time. Thus, this study explored performing in vivo Raman measurements of the model drug levofloxacin lactate in the blood using a nanoparticle-coated optical fiber probe (optical fiber nano-probe). The results show that we were able to measure real-time changes in the blood concentration of levofloxacin lactate, suggesting that this technique could be helpful for performing drug analyses and drug monitoring in a clinical setting without repeatedly withdrawing blood from patients. PMID:27231590

  6. Enhanced mechanical properties and cytocompatibility of electrospun poly(L-lactide) composite fiber membranes assisted by polydopamine-coated halloysite nanotubes

    Science.gov (United States)

    Luo, Chuang; Zou, Ziping; Luo, Binghong; Wen, Wei; Li, Huihua; Liu, Mingxian; Zhou, Changren

    2016-04-01

    To improve the dispersion and interfacial interaction between halloysite nanotubes (HNTs) and poly(L-lactide) (PLLA) matrix, and hence to increase the mechanical properties and cytocompatibility of the HNTs/PLLA composite, a facile approach was developed to prepare polydopamine-coated HNTs (D-HNTs) by the self-polymerization of dopamine (DOPA), and then HNTs and D-HNTs were further introduced into PLLA matrix to fabricate HNTs/PLLA and D-HNTs/PLLA fiber membranes based on electrospinning technique. The successful immobilization of the polydopamine (PDOPA) coating on the surfaces of HNTs was confirmed, and such PDOPA coating played an important role in improving the interfacial interaction between the nanotubes and PLLA matrix. The D-HNTs were dispersed in the matrix more uniformly than untreated HNTs, and relative smooth and uniform fiber were obtained for the D-HNTs/PLLA fiber membrane. As a result, the tensile strength and modulus of the D-HNTs/PLLA fiber membrane were obviously superior to those of the HNTs/PLLA fiber membrane. Cell culture results revealed that D-HNTs/PLLA fiber membrane was more effectively to promote MC3T3-E1 cells adhesion and proliferation than neat PLLA and HNTs/PLLA fiber membrane.

  7. High-temperature protective coatings for C/SiC composites

    Directory of Open Access Journals (Sweden)

    Xiang Yang

    2014-12-01

    Full Text Available Carbon fiber-reinforced silicon carbide (C/SiC composites were well-established light weight materials combining high specific strength and damage tolerance. For high-temperature applications, protective coatings had to provide oxidation and corrosion resistance. The literature data introduced various technologies and materials, which were suitable for the application of coatings. Coating procedures and conditions, materials design limitations related to the reactivity of the components of C/SiC composites, new approaches and coating systems to the selection of protective coatings materials were examined. The focus of future work was on optimization by further multilayer coating systems and the anti-oxidation ability of C/SiC composites at temperatures up to 2073 K or higher in water vapor.

  8. Improvement of transmission properties of visible pilot beam for polymer-coated silver hollow fibers with acrylic silicone resin as buffer layer for sturdy structure

    Science.gov (United States)

    Iwai, Katsumasa; Takaku, Hiroyuki; Miyagi, Mitsunobu; Shi, Yi-Wei; Zhu, Xiao-Song; Matsuura, Yuji

    2017-02-01

    Flexible hollow fibers with 530-μm-bore size were developed for infrared laser delivery. Sturdy hollow fibers were fabricated by liquid-phase coating techniques. A silica glass capillary is used as the substrate. Acrylic silicone resin is used as a buffer layer and the buffer layer is firstly coated on the inner surface of the capillary to protect the glass tube from chemical damages due to the following silver plating process. A silver layer was inner-plated by using the conventional silver mirror-plating technique. To improve adhesion of catalyst to the buffer layer, a surface conditioner has been introduced in the method of silver mirror-plating technique. We discuss improvement of transmission properties of sturdy polymer-coated silver hollow fibers for the Er:YAG laser and red pilot beam delivery.

  9. Wavelength response of a surface plasmon resonance palladium-coated optical fiber sensor for hydrogen detection

    NARCIS (Netherlands)

    Perrotton, C.; Slaman, M.; Javahiraly, N.; Schreuders, H.; Dam, B.; Meyrueis, P.

    2011-01-01

    An optical fiber using palladium as sensitive layer is characterized in the range of 450 to 900 nm. The sensitive layer is deposited on the outside of a multimode fiber, after removing the optical cladding. The sensor is based on a measurement technique that uses the surface plasmon resonance

  10. Single Carbon Fibers with a Macroscopic-Thickness, 3D Highly Porous Carbon Nanotube Coating.

    Science.gov (United States)

    Zou, Mingchu; Zhao, Wenqi; Wu, Huaisheng; Zhang, Hui; Xu, Wenjing; Yang, Liusi; Wu, Shiting; Wang, Yunsong; Chen, Yijun; Xu, Lu; Cao, Anyuan

    2018-02-19

    Carbon fiber (CF) grafted with a layer of carbon nanotubes (CNTs) plays an important role in composite materials and other fields; to date, the applications of CNTs@CF multiscale fibers are severely hindered by the limited amount of CNTs grafted on individual CFs and the weak interfacial binding force. Here, monolithic CNTs@CF fibers consisting of a 3D highly porous CNT sponge layer with macroscopic-thickness (up to several millimeters), which is directly grown on a single CF, are fabricated. Mechanical tests reveal high sponge-CF interfacial strength owing to the presence of a thin transitional layer, which completely inhibits the CF slippage from the matrix upon fracture in CNTs@CF fiber-epoxy composites. The porous conductive CNTs@CF hybrid fibers also act as a template for introducing active materials (pseudopolymers and oxides), and a solid-state fiber-shaped supercapacitor and a fiber-type lithium-ion battery with high performances are demonstrated. These CNTs@CF fibers with macroscopic CNT layer thickness have many potential applications in areas such as hierarchically reinforced composites and flexible energy-storage textiles. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Fiber optic gas sensors with vanadium oxide and tungsten oxide nanoparticle coated claddings

    Science.gov (United States)

    Renganathan, B.; Sastikumar, D.; Raj, S. Gokul; Ganesan, A. R.

    2014-03-01

    Fiber optic gas sensors with nanoparticles of V2O5 and WO3 as the cladding of a PMMA fiber have been proposed in this work. The spectral response of these sensors for detection of ammonia, methanol and ethanol under various concentrations has been studied at room temperature. The time response characteristics of the sensors are also presented.

  12. Preparation and characterization of metal-organic framework MIL-101(Cr)-coated solid-phase microextraction fiber.

    Science.gov (United States)

    Xie, Lijun; Liu, Shuqin; Han, Zhubing; Jiang, Ruifen; Liu, Hong; Zhu, Fang; Zeng, Feng; Su, Chengyong; Ouyang, Gangfeng

    2015-01-01

    Metal-organic frameworks (MOFs) have received great attention as novel sorbents due to their fascinating structures and intriguing potential applications in various fields. In this work, a MIL-101(Cr)-coated solid-phase microextraction (SPME) fiber was fabricated by a simple direct coating method and applied to the determination of volatile compounds (BTEX, benzene, toluene, ethylbenzene, m-xylene and o-xylene) and semi-volatile compounds (PAHs, polycyclic aromatic hydrocarbons) from water samples. The extraction and desorption conditions of headspace SPME (HS-SPME) were optimized. Under the optimized conditions, the established methods exhibited excellent extraction performance. Good precision (river water by coupling with gas chromatography-mass spectrometry (GC-MS). The analytes at low concentrations (1.7 and 10 ng L(-1)) were detected, and the recoveries obtained with the spiked river water samples were in the range of 80.0-113% and 84.8-106% for BTEX and PAHs, respectively, which demonstrated the applicability of the self-made fiber. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. A Transmission Electron Microscope Characterization of Sodium Sulfate Hot Corrosion of Silicon Carbide Fiber-Reinforced Lithium Aluminosilicate Glass-Ceramic Matrix Composite

    Science.gov (United States)

    1994-09-01

    P- spodumene (Li20-Al20 3 -4SiO2 ) and mullite (3A1203- 2SIO2 ) in a high silica glass (88 wt% SiC2 and 12 wt% A1203). The fiber/matrix interface...hot corrosion. The matrix was a very fine mixture of glass and P- spodumene polycrystallites (20 nm in diameter) . The fiber/matrix interface was...binary phase diagram . . . 5 Figure 3. Longitudinal thermal expansion of solid solutions of P- spodumene (Li20-Al203-nSiO2). 6 Figure 4. Volume

  14. Optical detection of glucose and glycated hemoglobin using etched fiber Bragg gratings coated with functionalized reduced graphene oxide.

    Science.gov (United States)

    Sridevi, S; Vasu, K S; Sampath, S; Asokan, S; Sood, A K

    2016-07-01

    An enhanced optical detection of D-glucose and glycated hemoglobin (HbA1c ) has been established in this study using etched fiber Bragg gratings (eFBG) coated with aminophenylboronic acid (APBA)-functionalized reduced graphene oxide (RGO). The read out, namely the shift in Bragg wavelength (ΔλB ) is highly sensitive to changes that occur due to the adsorption of glucose (or HbA1c ) molecules on the eFBG sensor coated with APBA-RGO complex through a five-membered cyclic ester bond formation between glucose and APBA molecules. A limit of detection of 1 nM is achieved with a linear range of detection from 1 nM to 10 mM in the case of D-glucose detection experiments. For HbA1c , a linear range of detection varying from 86 nM to 0.23 mM is achieved. The observation of only 4 pm (picometer) change in ΔλB even for the 10 mM lactose solution confirms the specificity of the APBA-RGO complex coated eFBG sensors to glucose molecules. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Single-ended long period fiber grating refractive index sensor based on metal-coated surface plasma resonance

    Science.gov (United States)

    Zhao, Minfu; Zhang, Guiju; Ma, Difeng; Wang, Chinhua

    2008-12-01

    A novel single-ended reflecting long period fiber grating (LPFG) sensor with thin metal film overlay and the sensing system is described. An all-fiber reflection based surface plasma resonance (SPR) LPFG sensor with three-layer structure (core, cladding and metal) is established experimentally and fabricated with a pulsed CO2 laser writing system and vacuum evaporation coating system. Different nm-thick thin metal films are deposited on the reflected LPFG sensor for the excitation of surface plasma waves (SPWs) and the characteristics of the reflection resonance spectra of the LPFG sensor for measuring refractive index of fluids are studied. It is found that different thicknesses of different metal films show different measuring sensitivity. Through the comparison of the resonance wavelength obtained in air, water, alcohol, glycerin and their mixture solution, different sensitivities of the reflected SPR-LPFG sensor have been achieved. The proposed SPR-LPFG sensing scheme offers an efficient platform for achieving high performance fiber sensors for the measurement of ambient refractive index.

  16. Constructing Novel Fiber Reinforced Plastic (FRP Composites through a Biomimetic Approach: Connecting Glass Fiber with Nanosized Boron Nitride by Polydopamine Coating

    Directory of Open Access Journals (Sweden)

    XueMei Wen

    2013-01-01

    Full Text Available A biomimetic method was developed to construct novel fiber reinforced plastic (FRP composites. By mimicking mussel adhesive proteins, a monolayer of polydopamine was coated on glass fiber (GF surface. The polydopamine-treated GF (D-GF adsorbed boron nitride (BN nanoparticles, while obtaining micronano multiscale hybrid fillers BN-D-GF. Scanning electron microscopy (SEM results showed that the strong interfacial interaction brought by the polydopamine benefits the loading amount as well as dispersion of the nano-BN on GF’s surface. The BN-D-GF was incorporated into epoxy resin to construct “FRP nanocomposites.” The morphology, dynamic mechanical and thermal characteristics of the FRP nanocomposites were analyzed. SEM morphology revealed that BN-D-GF heterogeneous dispersed in epoxy matrix. There was good adhesion between the polymer matrix and the BN-D-GF filler. The dynamic modulus and mechanical loss were studied using dynamic mechanical analysis (DMA. Compared with neat epoxy and untreated GF reinforced composites, BN-D-GF/epoxy and D-GF/epoxy systems showed improved mechanical properties. The thermal conductivity, Shore D hardness, and insulation properties were also enhanced.

  17. Development of a TiO{sub 2}-coated optical fiber reactor for water decontamination; Developpement d'un reacteur a base de fibres optiques photocatalytiquement actives pour la depollution de l'eau

    Energy Technology Data Exchange (ETDEWEB)

    Danion, A

    2004-09-15

    The objective of this study was to built and to study a photo-reactor composed by TiO{sub 2}-coated optical fibers for water decontamination. The physico-chemical characteristics and the optical properties of the TiO{sub 2} coating were first studied. Then, the influences of different parameters as the coating thickness, the coating length and the coating volume were investigated both on the light transmission in the TiO{sub 2}- coated fiber and on the photo-catalytic activity of the fiber for a model compound (malic acid). The photo-catalytic degradation of malic acid was optimized using the experimental design methodology allowing to build a multi-fiber reactor comprising 57 optical fibers. The photo-degradation of malic acid was conducted in the multi-fiber reactor and it was demonstrated that the multi-fiber reactor was more efficient than the single-fiber reactor at the same fibers density. Finally, the multi-fiber reactor was applied to the photo-degradation of a fungicide, called fenamidone, and a degradation pathway was proposed. (author)

  18. Enhanced mechanical properties and cytocompatibility of electrospun poly(L-lactide) composite fiber membranes assisted by polydopamine-coated halloysite nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Chuang; Zou, Ziping [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Luo, Binghong, E-mail: tluobh@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Wen, Wei [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Li, Huihua [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Liu, Mingxian [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Zhou, Changren, E-mail: tcrz9@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China)

    2016-04-30

    Graphical abstract: - Highlights: • D-HNTs was prepared by a facile approach based on the self-polymerization of DOPA. • The D-HNTs can disperse more uniformly in PLLA matrix than untreated HNTs. • The interfacial adhesion between D-HNTs and PLLA matrix was obviously improved. • D-HNTs/PLLA fiber membrane has better tensile properties compared with HNTs/PLLA. • The D-HNTs/PLLA fiber membrane is favorable to cell adhesion and proliferation. - Abstract: To improve the dispersion and interfacial interaction between halloysite nanotubes (HNTs) and poly(L-lactide) (PLLA) matrix, and hence to increase the mechanical properties and cytocompatibility of the HNTs/PLLA composite, a facile approach was developed to prepare polydopamine-coated HNTs (D-HNTs) by the self-polymerization of dopamine (DOPA), and then HNTs and D-HNTs were further introduced into PLLA matrix to fabricate HNTs/PLLA and D-HNTs/PLLA fiber membranes based on electrospinning technique. The successful immobilization of the polydopamine (PDOPA) coating on the surfaces of HNTs was confirmed, and such PDOPA coating played an important role in improving the interfacial interaction between the nanotubes and PLLA matrix. The D-HNTs were dispersed in the matrix more uniformly than untreated HNTs, and relative smooth and uniform fiber were obtained for the D-HNTs/PLLA fiber membrane. As a result, the tensile strength and modulus of the D-HNTs/PLLA fiber membrane were obviously superior to those of the HNTs/PLLA fiber membrane. Cell culture results revealed that D-HNTs/PLLA fiber membrane was more effectively to promote MC3T3-E1 cells adhesion and proliferation than neat PLLA and HNTs/PLLA fiber membrane.

  19. Trace hydrogen sulfide gas sensor based on tungsten sulfide membrane-coated thin-core fiber modal interferometer

    Science.gov (United States)

    Deng, Dashen; Feng, Wenlin; Wei, Jianwei; Qin, Xiang; Chen, Rong

    2017-11-01

    A novel fiber-optic hydrogen sulfide sensor based on a thin-core Mach-Zehnder fiber modal interferometer (TMZFI) is demonstrated and fabricated. This in-line interferometer is composed of a short section of thin-core fiber sandwiched between two standard single mode fibers, and the fast response to hydrogen sulfide is achieved via the construction of tungsten sulfide film on the outside surface of the TMZFI using the dip-coating and calcination technique. The fabricated sensing nanofilm is characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) spectrometer, Fourier transform infrared (FTIR) and spectroscopic analysis technology, etc. Experimental results showed that the WS2 sensing film has a hexagonal structure with a compact and porous morphology. The XPS and FTIR indicate that the existence of two elements (W and S) is demonstrated. With the increasing concentration of hydrogen sulfide, the interference spectra appear blue shift. In addition, a high sensitivity of 18.37 pm/ppm and a good linear relationship are obtained within a measurement range from 0 to 80 ppm. In addition, there is an excellent selectivity for H2S, which has also been proved by the surface adsorption energy results of tungsten sulfide with four gases (H2S, N2, O2 and CO2) by using the density functional theory calculations. This interferometer has the advantages of simple structure, high sensitivity and easy manufacture, and could be used in the safety monitoring field of hydrogen sulfide gas.

  20. Influence of Heat-Treatment Temperature on the Physical Properties and Microstructure of Phosphoric Acid Coated Oxi-PAN Fiber/Phenolic Composites

    Energy Technology Data Exchange (ETDEWEB)

    Cho, D.H. [KUMHO NATIONAL UNIVERSITY OF TECHNOLOGY, KUMI (Korea, Republic of)

    1996-10-01

    Random OXI-PAN fiber/phenolic composites fabricated with uncoated and phosphoric acid coated OXI-PAN fibers were carbonized at various heat-treatment temperatures in an inert atmosphere. An effect of the presence or absence of phosphorous compound on the fiber surface in the composite after heat-treatment upon the physical properties and microstructure was studied. The physical properties of the two types of composite were explained in terms of microstructural behaviour and pore formation in the fiber, the matrix and the interface according to heat-treatment temperature. It was known that with increasing temperature the fiber/matrix interface becomes disappeared and shows a locally dense and indistinguishable phase due to possible chemical reaction between the fiber and the adjacent matrix. It was also noted that the phosphoric acid coating restraints the reduction of fiber diameter and increases the thermal stability under the carbonization condition so that it contributes somewhat to lower the volume shrinkage and to increase the carbon yield of the composite (author). 25 refs. figs.

  1. Polydimethylsiloxane/metal-organic frameworks coated fiber for solid-phase microextraction of polycyclic aromatic hydrocarbons in river and lake water samples.

    Science.gov (United States)

    Zhang, Guijiang; Zang, Xiaohuan; Li, Zhi; Wang, Chun; Wang, Zhi

    2014-11-01

    In this study, polydimethylsiloxane/metal-organic frameworks (PDMS/MOFs), including PDMS/MIL-101 and PDMS/MOF-199, were immobilized onto a stainless steel wire through sol-gel technique as solid-phase microextraction (SPME) fiber coating. The prepared fibers were used for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from water samples prior to gas chromatography-mass spectrometry (GC-MS) analysis. Under the optimized experiment conditions, the PDMS/MIL-101 coated fiber exhibited higher extraction efficiency towards PAHs than that of PDMS/MOF-199. Several parameters affecting the extraction of PAHs by SPME with PDMS/MIL-101 fiber, including the extraction temperature, extraction time, sample volume, salt addition and desorption conditions, were investigated. The limits of detection (LODs) were less than 4.0 ng L(-1) and the linearity was observed in the range from 0.01 to 2.0 µg L(-1) with the correlation coefficients (r) ranging from 0.9940 to 0.9986. The recoveries of the method for the PAHs from water samples at spiking levels of 0.05 and 0.2 µg L(-1) ranged from 78.2% to 110.3%. Single fiber repeatability and fiber-to-fiber reproducibility were less than 9.3% and 13.8%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. MICROSTRUCTURE FEATURES OF CHROME-NICKEL COATING WELDED WITH FILLER WIRE PL AN-111 WITH A 50% OVERLAP

    Directory of Open Access Journals (Sweden)

    A. G. Belik

    2017-04-01

    Full Text Available Purpose. The paper involves investigation of microstructure features of the coating welded with filler wire PL AN-111 with a 50% beads overlap. Methodology. Wear-resistant layer was formed by means of electric arc deposit welding using filler wire PL AN-111 on the plate from steel 09G2S. Deposit welding was conducted under the following parameters: welding current is of 650-750 A; arc voltage is of 30-34 V; welding speed is of 32 m/h. Microstructure was researched with application of optical microscopies “Neophot-21”, “Nikon Eclipse M200” and electron scanning microscopy JEOL JSM-6510 LV. Microhardness of structural constituentswas measuredwithtesterFM-300 (Future-Tech under loading of 10-50 g. Findings. It is shown that the overlap of the beads leads to the formation of inhomogeneous microstructure in the cross section that varies by zones from free-carbide austenite to hypereutectic microstructure with primary chromium carbides. The analysis of the microhardness of the structural constituents in various coating areas was carried out. It was found that hardness of austenite, carbide eutectic and carbides M7C3 varies in coatings in the range of 3 100-3 850 МPа, 4 100-6 800 МPа and 12 100-15 100 МPа, accordingly. Originality. Authors determined that Cr-Ni coating comprises substantially austenitic-carbide eutectic with different density and thickness of carbide fibers within eutectic colonies. Along the border “base/coating” a single-phase austenitic layer lies which turns into a layer with a hypoeutectic structure. In the heat affected zone from beads fusion austenite disintegration with the granular carbides formation was recorded. This leads to decreasing of matrix corrosion resistance due to chromium depletion. Above the zone of beads fusion, the coating has a hypereutectic structure with the presence of large primary chromium carbides. Practical value. It is shown that deposit welding with filler wire PL AN-111 with a 50

  3. Preparation, Characterization, and Millimeter Wave Attenuation of Carbon Fibers Coated with Ni-Cu-P and Ni-Co-P Alloys

    Science.gov (United States)

    Ye, Mingquan; Li, Zhitao; Wang, Chen; Han, Aijun

    2015-12-01

    Composite carbon fibers (CFs) coated with Ni-X-P (X = Cu, Co, none) alloys were prepared by electroless plating. The morphology, crystal structure, elemental composition, and millimeter wave (MMW) attenuation performance of the alloy-coated CFs were characterized by scanning electron microscopy, x-ray diffractometry, energy-dispersive spectrometry, and microwave attenuation. CFs were coated with a layer of alloy particles. The P content in the Ni-Cu-P or Ni-Co-P-coated alloy was lower than that in the Ni-P alloy, and coating alloy Ni-P was amorphous. Coating alloys exhibited crystal characteristics after Cu or Co introduction. MMW-attenuation performance of alloy-coated CFs showed that the 3 and 8 mm wave-attenuation effects of CF/Ni-Cu-P and CF/Ni-Co-P were better than those of CF/Ni-P and CFs. The 8 mm wave-attenuation values and their increases were larger than those of the 3 mm wave. The MMW-attenuation performance is attributable to the alloy bulk resistivity and P content. The 3 mm wave-attenuation effects of wavelength-coated CF samples were slightly larger than those of the half wavelength samples. An optimal weight gain value existed for the MMW-attenuation performance of alloy-coated CFs.

  4. Absorption of hydrophobic compounds into the poly(dimethylsiloxane) coating of solid-phase microextraction fibers : high partition coefficients and fluorescence microscopy images

    NARCIS (Netherlands)

    Mayer, P.; Vaes, W.H.J.; Hermens, J.L.M.

    2000-01-01

    The use of solid-phase microextraction with poly(dimethylsiloxane) (PDMS)-coated glass fibers for the extraction and analysis of hydrophobic organic analytes is increasing. The literature on this topic is characterized by large discrepancies in partition coefficients and an uncertainty of whether

  5. Microwave-assisted combustion synthesis of nano iron oxide/iron-coated activated carbon, anthracite, cellulose fiber, and silica, with arsenic adsorption studies

    Science.gov (United States)

    Combustion synthesis of iron oxide/iron coated carbons such as activated carbon, anthracite, cellulose fiber and silica is described. The reactions were carried out in alumina crucibles using a Panasonic kitchen microwave with inverter technology, and the reaction process was com...

  6. Prospective, multi-center evaluation of a silicon carbide coated cobalt chromium bare metal stent for percutaneous coronary interventions: two-year results of the ENERGY Registry.

    Science.gov (United States)

    Erbel, Raimund; Eggebrecht, Holger; Roguin, Ariel; Schroeder, Erwin; Philipp, Sebastian; Heitzer, Thomas; Schwacke, Harald; Ayzenberg, Oded; Serra, Antonio; Delarche, Nicolas; Luchner, Andreas; Slagboom, Ton

    2014-01-01

    Novel bare metal stents with improved stent design may become a viable alternative to drug-eluting stents in certain patient groups, particularly, when long-term dual antiplatelet therapy should be avoided. The ENERGY registry aimed to assess the safety and benefits of a cobalt-chromium thin strut bare metal stent with a passive coating in a large series of patients under real-world conditions. This prospective registry recruited 1016 patients with 1074 lesions in 48 centers from April to November 2010. The primary endpoint was the rate of major adverse cardiac events (MACEs), a composite of cardiac death, myocardial infarction and clinically driven target lesion revascularization. More than half of the lesions (61.0%) were type A/B1 lesions, mean lesion length was 14.5±6.5mm and mean reference vessel diameter 3.2±0.5mm. MACE rates at 6, 12 and 24months were 4.9%, 8.1% and 9.4%, target lesion revascularization rates 2.8%, 4.9% and 5.4% and definite stent thrombosis rates 0.5%, 0.6% and 0.6%. Subgroups showed significant differences in baseline and procedural characteristics which did not translate into significantly different clinical outcomes. Specifically, MACE rates at 24months were 13.5% in diabetics, 8.6% in small stents and 9.6% in acute coronary syndrome patients. The population of ENERGY reflects real-world conditions with bare metal stents being mainly used in simple lesions. In this setting, percutaneous coronary intervention using a cobalt-chromium thin strut bare metal stent with a passive coating showed very good results up to 24months. (ClinicalTrials.gov:NCT01056120) SUMMARY FOR ANNOTATED TABLE OF CONTENTS: The ENERGY international registry evaluated the safety and benefits of a cobalt-chromium thin strut bare metal stent with passive coating in 1016 patients under real-world conditions until 2years. Results were encouraging with a low composite rate of cardiac death, myocardial infarction and clinically driven target lesion revascularization, even

  7. Prospective, multi-center evaluation of a silicon carbide coated cobalt chromium bare metal stent for percutaneous coronary interventions: Two-year results of the ENERGY Registry

    Energy Technology Data Exchange (ETDEWEB)

    Erbel, Raimund, E-mail: erbel@uk-essen.de [Department of Cardiology, University of Duisburg-Essen, Essen (Germany); Eggebrecht, Holger [Cardioangiological Center Bethanien (CCB), Frankfurt (Germany); Roguin, Ariel [Department of Cardiology, Rambam Medical Center, Haifa (Israel); Schroeder, Erwin [Division of Cardiovascular Medicine, Cliniques Universitaires de Mont-Godinne, Yvoir (Belgium); Philipp, Sebastian [Department Internal Medicine/Cardiology, Elbe Klinikum Stade, Stade (Germany); Heitzer, Thomas [Department of Cardiology, Heart Center Dortmund, Dortmund (Germany); Schwacke, Harald [Department of Internal Medicine, Diakonissen-Stiftungs- Krankenhaus Speyer (Germany); Ayzenberg, Oded [The Heart Institute, Kaplan Medical Center, Rehovot (Israel); Serra, Antonio [Servicio de Cardiología, Hospital de la Santa Creu i Sant Pau, Barcelona, España (Spain); Delarche, Nicolas [Cardiology unit, Pau General Hospital, Pau (France); Luchner, Andreas [Department of Internal Medicine/Cardiology, Universitätsklinikum Regensburg (Germany); Slagboom, Ton [Department of Cardiology, Onze Lieve Vrouwe Gasthuis, Amsterdam (Netherlands)

    2014-11-15

    Background: Novel bare metal stents with improved stent design may become a viable alternative to drug-eluting stents in certain patient groups, particularly, when long-term dual antiplatelet therapy should be avoided. Purpose: The ENERGY registry aimed to assess the safety and benefits of a cobalt–chromium thin strut bare metal stent with a passive coating in a large series of patients under real-world conditions. Methods and materials: This prospective registry recruited 1016 patients with 1074 lesions in 48 centers from April to November 2010. The primary endpoint was the rate of major adverse cardiac events (MACEs), a composite of cardiac death, myocardial infarction and clinically driven target lesion revascularization. Results: More than half of the lesions (61.0%) were type A/B1 lesions, mean lesion length was 14.5 ± 6.5 mm and mean reference vessel diameter 3.2 ± 0.5 mm. MACE rates at 6, 12 and 24 months were 4.9%, 8.1% and 9.4%, target lesion revascularization rates 2.8%, 4.9% and 5.4% and definite stent thrombosis rates 0.5%, 0.6% and 0.6%. Subgroups showed significant differences in baseline and procedural characteristics which did not translate into significantly different clinical outcomes. Specifically, MACE rates at 24 months were 13.5% in diabetics, 8.6% in small stents and 9.6% in acute coronary syndrome patients. Conclusion: The population of ENERGY reflects real-world conditions with bare metal stents being mainly used in simple lesions. In this setting, percutaneous coronary intervention using a cobalt–chromium thin strut bare metal stent with a passive coating showed very good results up to 24 months. (ClinicalTrials.gov:NCT01056120) Summary for annotated table of contents: The ENERGY international registry evaluated the safety and benefits of a cobalt–chromium thin strut bare metal stent with passive coating in 1016 patients under real-world conditions until 2 years. Results were encouraging with a low composite rate of cardiac death

  8. Application of NiTi alloy coated with ZrO2 as a new fiber for solid-phase microextraction for determination of halophenols in water samples.

    Science.gov (United States)

    Budziak, Dilma; Martendal, Edmar; Carasek, Eduardo

    2007-08-29

    A new fiber for solid-phase microextraction (SPME) employing a metallic support coated with an inorganic material is proposed. A nitinol alloy (NiTi) was used as the support material due to its super elasticity and shape memory properties. Zirconium oxide (ZrO2) was electrodeposited onto NiTi using chronoamperometry. The surface characteristics and morphology of the coated and uncoated support were evaluated through scanning electronic microscopy and dispersive energy microanalysis. This assembly was applied in the extraction of three halophenols from aqueous samples. A multivariate approach was used for optimization of the variables involved in the system. The Doehlert matrix was used for evaluation of the best derivatization conditions and a Box-Behnken design to obtain the best extraction conditions. In order to investigate the repeatability, one fiber was used for six extraction tests under similar conditions and the relative standard deviations (R.S.D.) were lower than 12.5%. Detection limits were lower than 0.30 ng mL(-1). Correlation coefficients were higher than 0.997. Extraction efficiency of the NiTi-ZrO2 fiber was similar to a PDMS 7 microm commercial fiber, even though it had a lower coating thickness of 1.35 microm. Considering the amount extracted per unit volume, the NiTi-ZrO2 fiber had a better extraction profile when compared to commercial fibers. The new SPME fiber has a lifetime of over 500 extractions. Thus, it is a promising alternative for low-cost analysis, as the proposed fiber is robust, and easily and inexpensively prepared.

  9. Surface plasmon resonance on vicinity of gold-coated fiber tip

    Energy Technology Data Exchange (ETDEWEB)

    Abrahamyan, T. [Department of Radio Physics, Yerevan State University (Armenia); Nerkararyan, Kh. [Department of Radio Physics, Yerevan State University (Armenia)]. E-mail: knerkar@ysu.am

    2007-05-14

    The possibility of excitation of Surface Plasmon Polaritons (SPP) in the vicinity of the tip of a gold covered optical fiber is investigated when the tip is in the medium with a certain dielectric permittivity. In the experiment the medium was a solution consisting of dimethyl sulfoxide and ethanol liquids in which, as a result of evaporation, a smooth changing of the dielectric permittivity of the solution was taking place. During the evaporation a peak of the power of output radiation was observed from the tip of the fiber, which is explained by the resonant excitation of SPP. This mechanism of SPP excitation in the region of the tip of the optical waveguide opens up new possibilities for increasing the resolution of the nanometric scanning optical microscope and for creation of a new type of optochemical fiber sensors.

  10. Detection of volatile organic compounds using an optical fiber sensor coated with a sol-gel silica layer containing immobilized Nile red

    Science.gov (United States)

    Liu, Dejun; Lian, Xiaokang; Mallik, Arun Kumar; Han, Wei; Wei, Fangfang; Yuan, Jinhui; Yu, Chongxiu; Farrell, Gerald; Semenova, Yuliya; Wu, Qiang

    2017-04-01

    A simple volatile organic compound (VOC) sensor based on a tapered small core singlemode fiber (SCSMF) structure is reported. The tapered SCSMF fiber structure with a waist diameter of 7.0 μm is fabricated using a customized microheater brushing technique. Silica based material containing immobilized Nile red was prepared by a sol-gel method and was used as a coating applied to the surface of the tapered fiber structure. Different coating thicknesses created by a 2-pass and 4-pass coating process are investigated. The experiments demonstrate that both sensors show a linear response at different gas concentrations to all three tested VOCs (methanol, ethanol and acetone). The sensor with a thicker coating shows better sensitivities but longer response and recovery times. The best measurement resolutions for the 4-pass coating sensor are estimated to be 2.3 ppm, 1.5 ppm and 3.1 ppm for methanol, ethanol and acetone, respectively. The fastest response and recovery time of 1 min and 5 min are demonstrated by the sensor in the case of methanol.

  11. High-selectivity spectral multiplexers-demultiplexers usable in optical telecommunications obtained from multidielectric coatings at the end of optical fibers

    Science.gov (United States)

    Richier, Robert; Amra, Claude

    1991-09-01

    Economical and high-performance two-wavelength multiplexers-demultiplexers can be made from correctly cut optical fibers coated at their ends with multidielectric filters and then put together. The authors modelized the filters' performances by assimilating the inhomogeneous guided wave to an open beam whose characteristics depend upon the sort of optical fibers used in the connection and, for this purpose, introduced the notion of equivalent aperture for the guided beam. The validity of the prevision given by this model has been checked for a dichroic filter when the coating separates 850 nm and 1300 nm. Nowadays, the development of telecommunication through optical fibers induces conceivers to consider the use of closer and closer wavelengths. This implies the use of multicavity Fabry-Perot filters. The authors have made multiplexers-demultiplexers for wavelengths as close as 750 nm and 900 nm, set on optical fibers 85/125 with slight insert losses, and an optical crosstalk better than 30 dB. It is also shown that this type of coating can be used to devise multiplexers-demultiplexers working on 1.3 micrometers and 1.5 micrometers wavelengths. The experimental results prove the validity of the model used, and show that this research work can be generalized to different types of optical fibers.

  12. Oxidation-resistant interface coatings for SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Kupp, E.R.; Hurley, J.W. [and others

    1996-06-01

    The characteristics of the fiber-matrix interfaces in ceramic matrix composites control the mechanical behavior of these composites. Finite element modeling (FEM) was performed to examine the effect of interface coating modulus and coefficient of thermal expansion on composite behavior. Oxide interface coatings (mullite and alumina-titania) produced by a sol-gel method were chosen for study as a result of the FEM results. Amorphous silicon carbide deposited by chemical vapor deposition (CVD) is also being investigated for interface coatings in SiC-matrix composites. Processing routes for depositing coatings of these materials were developed. Composites with these interfaces were produced and tested in flexure both as-processed and after oxidation to examine the suitability of these materials as interface coatings for SiC/SiC composites in fossil energy applications.

  13. Oxidation-resistant interface coatings for SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Kupp, E.R.; Hurley, J.W.; Lowden, R.A. [Oak Ridge National Lab., TN (United States)] [and others

    1996-08-01

    The characteristics of the fiber-matrix interfaces in ceramic matrix composites control the mechanical behavior of these composites. Finite element modeling (FEM) was performed to examine the effect of interface coating modulus and coefficient of thermal expansion on composite behavior. Oxide interface coatings (mullite and alumina-titania) produced by a sol-gel method were chosen for study as a result of the FEM results. Amorphous silicon carbide deposited by chemical vapor deposition (CVD) is also being investigated for interface coatings in SiC-matrix composites. Processing routes for depositing coatings of these materials were developed. Composites with these interfaces were produced and tested in flexure both as-processed and after oxidation to examine the suitability of these materials as interface coatings for SiC/SiC composites in fossil energy applications.

  14. High tensile strength fly ash based geopolymer composite using copper coated micro steel fiber

    DEFF Research Database (Denmark)

    Ranjbar, Navid; Mehrali, Mehdi; Mehrali, Mohammad

    2016-01-01

    As a ceramic-like material, geopolymers show a high quasi-brittle behavior and relatively low fracture energy. To overcome this, the addition of fibers to a brittle matrix is a well-known method to improve the flexural strength. Moreover, the success of the reinforcements is dependent on the fiber...... of 56 days. Test results confirmed that MSF additions could significantly improve both ultimate flexural capacity and ductility of fly ash based geopolymer, especially at early ages without an adverse effect on ultimate compressive strength....

  15. A comparative study of graphene-coated stainless steel fiber felt and carbon cloth as anodes in MFCs.

    Science.gov (United States)

    Hou, Junxian; Liu, Zhongliang; Li, Yanxia; Yang, Siqi; Zhou, Yu

    2015-05-01

    This study investigated the stainless steel-based materials and their potential in microbial fuel cells (MFCs) anode application. Herein, AISI 316L stainless steel fiber felts (SSFFs) were used as anodes in MFCs and their performance was compared with the carbon cloth anode MFCs. The experimental results showed that the unmodified carbon cloth (CC) anode had a better performance than the unmodified SSFF anode. However, after coating a thin layer of graphene (GN) on SSFF and CC, the power density of the MFC equipped with the modified SSFF was 2,143 mW m(-2), much higher than that of the graphene-modified CC-MFC which was only 1,018 mW m(-2). The experimental results proved that the use of durable metallic backbones combined with a thin layer of carbon nanoparticles offers exciting opportunities in the advancement of MFC anode design.

  16. Application of metal coatings for functionalization of technical fibers and fabrics

    Science.gov (United States)

    Lusis, A.; Pentjuss, E.; Balodis, J.; Janeliukštis, R.; Zandersons, J.

    2011-12-01

    The metal coatings in combination with sonochemical and leaching processes are used for nanostructuring and functionalization of glass, flax and hemp fabrics. The leaching is used for nanostructuring sodium alumosilicate K-glass fabrics to obtained silica like fibre with nanoporous structure on surface and in volume. The natural fibres as well as fabrics themselves are porous media. The porous media adsorbs water and content of moisture in fabrics have to be controlled. The metal-coated fabric characterization is an actual problem. Application of metal coatings for the functionalization of technical fibres and fabrics faced with influence of moisture on functional properties, e.g., the impedance of the metal coated K-glass and flax and hemp fabrics have strong dependence of content absorbed water or moisture. Presented studies are on the moisture content determination methodology based on fhermogravimetric analyses and impedance spectroscopy. The leached K-glass fibres have three absorption sites with different kinetic and desorption heat. The flax has more complicated distribution of sorption/desorption sites. The water desorption heatl,3 kJ/g for both type of fabrics in temperature range 30-150 0C is comparable to the water evaporation heat 2,3 kJ/g at 100 0C. For leached K-glass fibre from the isothermal nitrogen sorption/desorption plot the pore volume is up to 7.5 cm3/g. and pore sizes are in range 2-100 nm.

  17. Carbon coatings on silica glass optical fibers studied by reflectance Fourier-transform infrared spectroscopy and focused ion beam scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stolov, Andrei A., E-mail: stolov@ofsoptics.com [OFS, Specialty Photonics Division, 55 Darling Drive, Avon, CT 06001 (United States); Lombardo, Jeffrey J. [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269 (United States); Slyman, Brian E.; Li, Jie [OFS, Specialty Photonics Division, 55 Darling Drive, Avon, CT 06001 (United States); Chiu, Wilson K.S. [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269 (United States)

    2012-04-30

    Carbon coatings applied on optical fibers via chemical vapor deposition were characterized by a resistance technique, focused ion beam/scanning electron microscopy (FIB/SEM), and reflectance Fourier-transform infrared spectroscopy (FTIR). The resistance technique measures the thickness of carbon film by measuring the resistance over a section of optical fiber, and backing out the film thickness. The FIB/SEM system was used to remove a cross section of the optical fiber and carbon coating and using a scanning transmission electron detector the thickness was measured. The FTIR approach is based on the fact that the wavelength of the light in the mid-infrared region ({approx} 10 {mu}m) is significantly larger than the typical thickness of the carbon coatings (< 0.1 {mu}m) which makes the coating 'semi-transparent' to the infrared light. Carbon coating deposition results in significant transformations of the band profiles of silica in the reflectance spectra that were found to correlate with the carbon coating thickness for films ranging from 0.7 nm to 54.6 nm. The observed transformations of the reflectance spectra were explained within the framework of Fresnel reflection of light from a dual-layer sample. The advantage of this approach is a much higher spatial resolution in comparison with many other known methods and can be performed more quickly than many direct measurement techniques. - Highlights: Black-Right-Pointing-Pointer Hermetic carbon films were grown on optical fibers using chemical vapor deposition. Black-Right-Pointing-Pointer Focused ion beam/scanning electron microscopy provided direct thickness values. Black-Right-Pointing-Pointer Transformations in reflectance infrared spectra correlate with carbon thickness. Black-Right-Pointing-Pointer Spectral transformations were modeled within the framework of Fresnel equations.

  18. Precipitation Coating of Monazite on Woven Ceramic Fibers: 1. Feasibility (Postprint)

    Science.gov (United States)

    2007-02-01

    by dissolving concentrated phosphoric acid ( Fish - er Scientific Co., Pittsburgh, PA) or a combination of lantha- num nitrate (Aldrich Chemical Co...testing of the fibers used in this work and Marlin Cook for his assist- ance in the preparation of microscopy samples. References 1A. G. Evans and D. B

  19. Fabrication and application of zinc-zinc oxide nanosheets coating on an etched stainless steel wire as a selective solid-phase microextraction fiber.

    Science.gov (United States)

    Song, Wenlan; Guo, Mei; Zhang, Yida; Zhang, Min; Wang, Xuemei; Du, Xinzhen

    2015-03-06

    A novel zinc-zinc oxide (Zn-ZnO) nanosheets coating was directly fabricated on an etched stainless steel wire substrate as solid-phase microextraction (SPME) fiber via previous electrodeposition of robust Zn coating. The scanning electron micrograph of the Zn-ZnO nanosheets coated fiber exhibits a flower-like nanostructure with high surface area. The SPME performance of as-fabricated fiber was investigated for the concentration and determination of polycyclic aromatic hydrocarbons, phthalates and ultraviolet (UV) filters coupled to high performance liquid chromatography with UV detection (HPLC-UV). It was found that the Zn-ZnO nanosheets coating exhibited high extraction capability, good selectivity and rapid mass transfer for some UV filters. The main parameters affecting extraction performance were investigated and optimized. Under the optimized conditions, the calibration graphs were linear over the range of 0.1-200μgL(-1). The limits of detection of the proposed method were 0.052-0.084μgL(-1) (S/N=3). The single fiber repeatability varied from 5.18% to 7.56% and the fiber-to-fiber reproducibility ranged from 6.74% to 8.83% for the extraction of spiked water with 50μgL(-1) UV filters (n=5). The established SPME-HPLC-UV method was successfully applied to the selective concentration and sensitive determination of target UV filters from real environmental water samples with recoveries from 85.8% to 105% at the spiking level of 10μgL(-1) and 30μgL(-1). The relative standard deviations were below 9.7%. Copyright © 2015. Published by Elsevier B.V.

  20. Friction surfaced Stellite6 coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rao, K. Prasad; Damodaram, R. [Department of Metallurgical and Materials Engineering - Indian Institute of Technology Madras, Chennai 600 036 (India); Rafi, H. Khalid, E-mail: khalidrafi@gmail.com [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Ram, G.D. Janaki [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Reddy, G. Madhusudhan [Metal Joining Group, Defence Metallurgical Research Laboratory (DMRL) Kanchanbagh, Hyderabad 500 058 (India); Nagalakshmi, R. [Welding Research Institute, Bharat Heavy Electricals Limited, Tiruchirappalli 620 014 (India)

    2012-08-15

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: Black-Right-Pointing-Pointer Stellite6 used as coating material for friction surfacing. Black-Right-Pointing-Pointer Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. Black-Right-Pointing-Pointer Finer and uniformly distributed carbides in friction surfaced coatings. Black-Right-Pointing-Pointer Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  1. Model for the Effect of Fiber Bridging on the Fracture Resistance of Reinforced-Carbon-Carbon

    Science.gov (United States)

    Chan, Kwai S.; Lee, Yi-Der; Hudak, Stephen J., Jr.

    2009-01-01

    A micromechanical methodology has been developed for analyzing fiber bridging and resistance-curve behavior in reinforced-carbon-carbon (RCC) panels with a three-dimensional (3D) composite architecture and a silicon carbide (SiC) surface coating. The methodology involves treating fiber bridging traction on the crack surfaces in terms of a weight function approach and a bridging law that relates the bridging stress to the crack opening displacement. A procedure has been developed to deduce material constants in the bridging law from the linear portion of the K-resistance curve. This report contains information on the application of procedures and outcomes.

  2. Fiber

    Science.gov (United States)

    ... white toast. Lunch and Dinner: Make sandwiches with whole-grain breads (rye, oat, or wheat) instead of white. Make a fiber-rich sandwich with whole-grain bread, peanut butter, and bananas. Use whole-grain spaghetti ...

  3. Influence of Carbon Nanotube Coatings on Carbon Fiber by Ultrasonically Assisted Electrophoretic Deposition on Its Composite Interfacial Property

    Directory of Open Access Journals (Sweden)

    Jianjun Jiang

    2016-08-01

    Full Text Available Carbon nanotube (CNT coatings were utilized to enhance the interfacial properties of carbon fiber (CF/epoxy(EP composites by ultrasonically assisted electrophoretic deposition (EPD. A characterization of the CF surface properties was done before and after coating (surface chemistry, surface morphologies, and surface energy. The result shows that oxygenated groups concentrations of the CF surfaces experienced significant increases from 12.11% to 24.78%. Moreover, the uniform and homogeneous CNT films were tightly attached on the surface of CF, and the surface wettability of CF is significant improved by enhanced surface free energy when introduced ultrasonic during the EPD process. In addition, the interlaminar shear strength (ILSS and water absorption of CF/EP composite were measured. Scanning electron microscopy (SEM revealed that the fracture mechanisms of the new interface layer formed by depositing CNTs on the CF surface contributed to the enhancement of the mechanical performance of the epoxy. This means that the efficient method to improve interfacial performance of composites has shown great commercial application potential.

  4. Roles of inorganic oxide nanoparticles on extraction efficiency of electrospun polyethylene terephthalate nanocomposite as an unbreakable fiber coating.

    Science.gov (United States)

    Bagheri, Habib; Roostaie, Ali

    2015-01-02

    In the present work, the roles of inorganic oxide nanoparticles on the extraction efficiency of polyethylene terephthalate-based nanocomposites were extensively studied. Four fiber coatings based on polyethylene terephthalate nanocomposites containing different types of nanoparticles along with a pristine polyethylene terephthalate polymer were conveniently electrospun on stainless steel wires. The applicability of new fiber coatings were examined by headspace-solid phase microextraction of some environmentally important volatile organic compound such as benzene, toluene, ethylbenzene and xylene (BTEX), as model compounds, from aqueous samples. Subsequently, the extracted analytes were transferred into a gas chromatography by thermal desorption. Parameters affecting the morphology and capability of the prepared nanocomposites including the type of nanoparticles and their doping levels along with the coating time were optimized. Four types of nanoparticles including Fe3O4, SiO2, CoO and NiO were examined as the doping agents and among them the presence of SiO2 in the prepared nanocomposite was prominent. The homogeneity and the porous surface structure of the SiO2-polyethylene terephthalate nanocomposite were confirmed by scanning electron microscopy indicating that the nanofibers diameters were lower than 300 nm. In addition, important parameters influencing the extraction and desorption process such as temperature and extraction time, ionic strength and desorption conditions were optimized. Eventually, the developed method was validated by gas chromatography-mass spectrometry. Under optimized conditions, the relative standard deviation values for a double distilled water spiked with the selected volatile organic compounds at 50 ng L(-1) were 2-7% (n=3) while the limits of detection were between 0.7 and 0.9 ng L(-1). The method was linear in the concentration range of 10 to 1,000 ng L(-1) (R(2)>0.9992). Finally, the developed method was applied to the analysis of

  5. CMK-3 nanoporous carbon as a new fiber coating for solid-phase microextraction coupled to gas chromatography-mass spectrometry.

    Science.gov (United States)

    Rahimi, Akram; Hashemi, Payman; Badiei, Alireza; Arab, Pezhman; Ghiasvand, Ali Reza

    2011-06-10

    CMK-3 nanoporous carbon was prepared and characterized as a highly porous fiber coating, with a highly ordered carbon framework, for solid-phase microextraction (SPME). The nanomaterial was immobilized onto platinum, stainless steel and copper metal wires for preparation of new SPME fibers. The copper-CMK-3 fiber showed superior properties and therefore was applied for extraction of some phenolic compounds in combination with GC-MS. For optimization of the extraction conditions, a simplex optimization method was used. The selected conditions were: sample volume 13 ml, extraction temperature 56°C, extraction time 7 min, ultrasonic time 5.5 min, pH 5 and salt concentration 8.9%. The selected fiber showed some selectivity towards the polar phenolic compounds and its extraction efficiency was better than a commercial PDMS fiber. Linear calibration curves with correlation coefficients better than 0.99 and detection limits in the range from 0.002 to 0.068 μg mL(-1) were obtained for the fiber. No significant change was observed in the extraction efficiency of the new SPME fiber over at least 40 extractions. The fiber was successfully used for the determination of phenolic compounds in natural water samples. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Plasmon-Organic Fiber Interactions in Diamond-Like Carbon Coated Nanostructured Gold Films

    DEFF Research Database (Denmark)

    Cielecki, Pawel Piotr; Sobolewska, Elżbieta Karolina; Kostiučenko, Oksana

    2017-01-01

    Gold is the most commonly used plasmonic material, however soft and prone to mechanical deformations. It has been shown that the durability of gold plasmonic substrates can be improved by applying a protective diamond-like carbon (DLC) coating. In this work, we investigate the influence...... of such protective layers on plasmonic interactions in organic–plasmonic hybrid systems. We consider systems, consisting of 1-Cyano-quaterphenylene nanofibers on top of gold nano-square plasmonic arrays, coated with protective layers of varying thickness. We numerically investigate the spectral position of surface...... plasmon polariton resonances and electric field intensity, as a function of protective layer thickness, using the finite-difference time-domain method. To confirm the numerically indicated field enhancement preservation on top of protective layers, we experimentally map the second harmonic response...

  7. Plasmon-organic fiber interactions in diamond-like carbon coated nanostructured gold films

    Science.gov (United States)

    Cielecki, Paweł Piotr; Sobolewska, Elżbieta Karolina; Kostiuočenko, Oksana; Leißner, Till; Tamulevičius, Tomas; Tamulevičius, Sigitas; Rubahn, Horst-Günter; Adam, Jost; Fiutowski, Jacek

    2017-11-01

    Gold is the most commonly used plasmonic material, however soft and prone to mechanical deformations. It has been shown that the durability of gold plasmonic substrates can be improved by applying a protective diamond-like carbon (DLC) coating. In this work, we investigate the influence of such protective layers on plasmonic interactions in organic-plasmonic hybrid systems. We consider systems, consisting of 1-Cyano-quaterphenylene nanofibers on top of gold nano-square plasmonic arrays, coated with protective layers of varying thickness. We numerically investigate the spectral position of surface plasmon polariton resonances and electric field intensity, as a function of protective layer thickness, using the finite-difference time-domain method. To confirm the numerically indicated field enhancement preservation on top of protective layers, we experimentally map the second harmonic response of organic nanofibers. Subsequently, we characterize the plasmonic coupling between organic nanofibers and underlying substrates, considered as one of the main loss channels for photoluminescence from nanofibers, by time-resolved photoluminescence spectroscopy. Our findings reveal that, for the investigated system, plasmonic interactions are preserved for DLC coatings up to 55 nm. This is relevant for the fabrication of new passive and active plasmonic components with increased durability and hence prolonged lifetime.

  8. Influence of the polymeric coating thickness on the electrochemical performance of Carbon Fiber/PAni composites

    Directory of Open Access Journals (Sweden)

    Carla Polo Fonseca

    2015-10-01

    Full Text Available Abstract Carbon fiber/polyaniline composites (CF/PAni were synthesized at three different deposition time of 30, 60 and 90 min by oxidative polymerization. The composite materials were morphologically and physically characterized by scanning electron microscopy and by Raman spectroscopy, respectively. Their electrochemical responses were analyzed by cyclic voltammetry, by galvanostatic test, and by electrochemical impedance spectroscopy. The influence of the PAni layer thickness deposited on carbon fibers for the composite formation as well as for their electrochemical properties was discussed. The CF/PAni-30 showed a nanometric thickness with more homogeneous morphology compared to those formed in deposition times of 60 and 90 min. It also showed, from the electrochemical impedance spectroscopy measurements, the lowest charge transfer resistance value associated to the its highest value for the double-layer capacitance of 180 Fg-1 making it a very strong candidate as a supercapacitor electrode.

  9. pH-responsive hydrogel coated fiber Bragg grating-based chemo mechanical sensor bioreactor applications

    Science.gov (United States)

    Kishore, P. V. N.; Sai Shankar, M.

    2017-04-01

    This paper describes a fiber optics based pH sensor by using wavelength modulated techniques. Fiber Bragg grating (FBG) is functionalized with a stimulus responsive hydrogel which induces a strain on FBG due to mechanical expansion of the gel in response to ambient pH changes. The gel is synthesized from the blends of Poly (vinyl alcohol)/Poly (acrylic acid). The induced strain results in a shift of FBG reflected peak which is monitored by an interrogator. The sensor system shows a good linearity in acidic pH range of 3 to 7 with a sensitivity of 12.16pm/pH. Besides that it shows good repeatability which proves it to be fit for pH sensing applications.

  10. Thermal-hydraulics analysis of a PWR reactor using zircaloy and carbide silicon reinforced with type S fibers as fuel claddings: Simulation of a channel blockage transient

    Energy Technology Data Exchange (ETDEWEB)

    Matuck, Vinicius; Ramos, Mario C.; Faria, Rochkhudson B.; Reis, Patricia A.L.; Costa, Antonella L.; Pereira, Claubia, E-mail: rochkdefaria@yahoo.com.br, E-mail: matuck747@gmail.com, E-mail: patricialire@yahoo.com.br, E-mail: marc5663@gmail.com, E-mail: antonella@nuclear.ufmg.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Engenharia Nuclear

    2017-11-01

    A detailed thermal-hydraulic reactor model using as reference data from the Angra 2 Final Safety Analysis Report (FSAR) has been developed and SiC reinforced with Hi-Nicalon type S fibers (SiC HNS) was used as fuel cladding. The goal is to compare its behavior from the thermal viewpoint with the Zircaloy, at the steady- state and transient conditions. The RELAP-3D was used to perform the thermal-hydraulic analysis and a blockage transient has been investigated at full power operation. The transient considered is related to total obstruction of a core cooling channel of one fuel assembly. The calculations were performed using a point kinetic model. The reactor behavior after this transient was analyzed and the time evolution of cladding and coolant temperatures mass flow and void fraction are presented. (author)

  11. Direct synthesis of nitrogen-doped graphene on platinum wire as a new fiber coating method for the solid-phase microextraction of BXes in water samples: Comparison of headspace and cold-fiber headspace modes.

    Science.gov (United States)

    Memarian, Elham; Hosseiny Davarani, Saied Saeed; Nojavan, Saeed; Movahed, Siyavash Kazemi

    2016-09-07

    In this work, a new solid-phase microextraction fiber was prepared based on nitrogen-doped graphene (N-doped G). Moreover, a new strategy was proposed to solve problems dealt in direct coating of N-doped G. For this purpose, first, Graphene oxide (GO) was coated on Pt wire by electrophoretic deposition method. Then, chemical reduction of coated GO to N-doped G was accomplished by hydrazine and NH3. The prepared fiber showed good mechanical and thermal stabilities. The obtained fiber was used in two different modes (conventional headspace solid-phase microextraction and cold-fiber headspace solid-phase microextraction (CF-HS-SPME)). Both modes were optimized and applied for the extraction of benzene and xylenes from different aqueous samples. All effective parameters including extraction time, salt content, stirring rate, and desorption time were optimized. The optimized CF-HS-SPME combined with GC-FID showed good limit of detections (LODs) (0.3-2.3 μg/L), limit of quantifications (LOQs) (1.0-7.0 μg/L) and linear ranges (1.0-5000 μg/L). The developed method was applied for the analysis of benzene and xylenes in rainwater and some wastewater samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Application of a solid-phase microextraction fiber coated with a graphene oxide-poly(dimethylsiloxane) composite for the extraction of triazoles from water.

    Science.gov (United States)

    Li, Zhi; Ma, Ruiyang; Zhang, Guijiang; Zhang, Shuaihua; Wang, Chun; Wu, Qiuhua; Wang, Zhi

    2016-08-01

    A solid-phase microextraction fiber was prepared by mixing graphene oxide and hydroxyl-terminated polydimethylsiloxane together and then coating the mixture on the surface of etched stainless-steel wire by sol-gel technology. After aging by heating, the graphene oxide-polydimethylsiloxane composite coated fiber was used for the direct solid phase microextraction of triazole fungicides from water samples. The properties of the graphene oxide-polydimethylsiloxane coating were characterized by transmission electron microscopy and thermogravimetric analysis. And the chemical stability of the coating was tested as well. Several important experimental parameters that could influence the extraction efficiency such as desorption temperature and time, extraction temperature and time, sample pH and stirring rate, were investigated and optimized. Under the optimized conditions, the limits of detection were in the range from 0.01 to 0.03 μg/L. The results indicated that the homemade fiber had the advantages of good thermal and chemical stability and high extraction efficiency, which was successfully applied to the analysis of triazoles in water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Validation of an SPME method, using PDMS, PA, PDMS-DVB, and CW-DVB SPME fiber coatings, for analysis of organophosphorus insecticides in natural waters.

    Science.gov (United States)

    Lambropoulou, D A; Sakkas, V A; Albanis, T A

    2002-11-01

    Solid-phase microextraction (SPME) has been optimized and applied to the determination of the organophosphorus insecticides diazinon, dichlofenthion, parathion methyl, malathion, fenitrothion, fenthion, parathion ethyl, bromophos methyl, bromophos ethyl, and ethion in natural waters. Four types of SPME fiber coated with different stationary phases (PDMS, PA, PDMS-DVB, and CW-DVB) were used to examine their extraction efficiencies for the compounds tested. Conditions that might affect the SPME procedure, such as extraction time and salt content, were investigated to determine the analytical performance of these fiber coatings for organophosphorus insecticides. The optimized procedure was applied to natural waters - tap, sea, river, and lake water - spiked in the concentration range 0.5 to 50 micro g L(-1) to obtain the analytical characteristics. Recoveries were relatively high - >80% for all types of aqueous sample matrix - and the calibration plots were reproducible and linear (R(2)>0.982) for all analytes with all the fibers tested. The limits of detection ranged from 2 to 90 ng L(-1), depending on the detector and the compound investigated, with relative standard deviations in the range 3-15% at all the concentration levels tested. The SPME partition coefficients (K(f)) of the organophosphorus insecticides were calculated experimentally for all the polymer coatings. The effect of organic matter such as humic acids on extraction efficiency was also studied. The analytical performance of the SPME procedure using all the fibers in the tested natural waters proved effective for the compounds.

  14. The Affordable Pre-Finishing of Silicon Carbide for Optical Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Creare proposes to develop a novel, laser-assisted, pre-finishing process for chemical vapor deposition (CVD) coated silicon-carbide ceramics. Our innovation will...

  15. Optical fiber biosensor based on enzymatic coating matrix for catecholamines assessment in human urine

    Science.gov (United States)

    Silva, Lurdes I. B.; Freitas, Ana C.; Rocha-Santos, Teresa A. P.; Pereira, M. E.; Duarte, Armando C.

    2010-09-01

    An optical fiber (OF) biosensor has been developed and applied for simultaneous determination of catecholamines (dopamine, norepinephrine and epinephrine) in human urine. The developed analytical device shows a high potential for catecholamines quantification with a detection limit of 2.1, 2.6 and 3.4 pg mL-1 for dopamine, norepinephrine and epinephrine, respectively. The analytical performance of the OF biosensor was found to be similar to that of the High Performance Liquid Chromatography - Electrochemical Detector (HPLC-ED) regarding catecholamines determination in samples of human urine.

  16. Experience-based learning on determining the frictional coefficients of thermoset polymers incorporated with silicon carbide whiskers and chopped carbon fibers at different temperatures

    Science.gov (United States)

    Harrison, Edward; Alamir, Mohammed; Alzahrani, Naif; Asmatulu, Ramazan

    2017-04-01

    High temperature applications of materials have been increasing for various industrial applications, such as automobile brakes, clutches and thrust pads. The big portion of these materials are made out of the polymeric materials with various reinforcements. In the present study, high temperature polymeric materials were incorporated with SiC whiskers and chopped carbon fibers at 0, 5, 10 and 20wt.% and molded into desired size and shape prior to the curing process. These inclusions were selected because of their high mechanical strengths and thermal conductivity values to easily dissipate the frictional heat energy and sustain more external loads. The method of testing involves a metal ramp with an adjustable incline to find the coefficients of static and kinetic frictions by recording time and the angle of movement at various temperatures (e.g., -10°C and 50°C). The test results indicated that increasing the inclusions made drastic improvements on the coefficients of static and kinetic frictions. The undergraduate students were involved in the project and observed all the details of the process during the laboratory studies, as well as data collection, analysis and presentation. This study will be useful for the future trainings of the undergraduate engineering students on the composite, automobile and other manufacturing industries.

  17. Repetitive Immunosensor with a Fiber-Optic Device and Antibody-Coated Magnetic Beads for Semi-Continuous Monitoring of Escherichia coli O157:H7.

    Science.gov (United States)

    Taniguchi, Midori; Saito, Hirokazu; Mitsubayashi, Kohji

    2017-09-19

    A rapid and reproducible fiber-optic immunosensor for Escherichia coli O157:H7 (E. coli O157:H7) was described. The biosensor consisted of a flow cell, an optical fiber with a thin Ni layer, and a PC linked fluorometer. First, the samples with E. coli O157:H7 were incubated with magnetic beads coated with anti-E. coli O157:H7 antibodies and anti-E. coli O157:H7 antibodies labeled cyanine 5 (Cy5) to make sandwich complexes. Then the Cy5-(E. coli O157:H7)-beads were injected into a flow cell and pulled to the magnetized Ni layer on the optical fiber set in the flow cell. An excitation light (λ = 635 nm) was used to illuminate the optical fiber, and the Cy5 florescent molecules facing the optical fiber were exposed to an evanescent wave from the optical fiber. The 670 nm fluorescent light was measured using a photodiode. Finally, the magnetic intensity of the Ni layer was removed and the Cy5-E. coli O157:H7-beads were washed out for the next immunoassay. E. coli O157:H7, diluted with phosphate buffer (PB), was measured from 1 × 10⁵ to 1 × 10⁷ cells/mL. The total time required for an assay was less than 15 min (except for the pretreatment process) and repeating immunoassay on one optical fiber was made possible.

  18. Sensing application of an optical fiber dip coated with L-Cystein ethyl ester hydrochloride capped ZnTe quantum dots

    Directory of Open Access Journals (Sweden)

    Sundaray Madhulita

    2016-09-01

    Full Text Available Optical fiber in conjunction with ZnTe quantum dots (QDs is investigated for sensing application. ZnTe QDs, are synthesized by a simple chemical bottom up approach. Quantum dots are capped with L-Cystein ethyl ester hydrochloride (LEEH, to increase their stability. Then LEEH capped ZnTe QDs, whose size is estimated as 2.29 nm by effective mass approximation (EMA, are dip-coated on a cladding removed optical fiber. Different concentrations of alcohol and ammonia are used to investigate the sensing behavior. It is found that sensitivity of the sensor increases with the use of QDs for both alcohol and ammonia.

  19. Analysis of Organic Volatile Flavor Compounds in Fermented Stinky Tofu Using SPME with Different Fiber Coatings

    Directory of Open Access Journals (Sweden)

    Wei Guan

    2012-03-01

    Full Text Available The organic volatile flavor compounds in fermented stinky tofu (FST were studied using SPME-GC/MS. A total of 39 volatile compounds were identified, including nine esters, seven alcohols, five alkenes, four sulfides, three heterocycles, three carboxylic acids, three ketones, two aldehydes, one phenol, one amine and one ether. These compounds were determined by MS, and conformed by comparison of the retention times of the separated constituents with those of authentic samples and by comparison of retention indexes (RIs of separated constituents with the RIs reported in the literature. The predominant volatile compound in FST was indole, followed by dimethyl trisulfide, phenol, dimethyl disulfide and dimethyl tetrasulfide. In order to find a better extraction time, the extraction times was optimized for each type of SPME fiber; the results show that the best extraction time for Carboxen/PDMS is 60 min, for PDMS/DVB 30 min, for DVB/CAR/PDMS 60 min and for PDMS 75 min. Of the four fibers used in this work, Carboxen/PDMS is found to be the most suitable to extract the organic volatile flavor compounds in fermented stinky tofu.

  20. A Highly Sensitive Gold-Coated Photonic Crystal Fiber Biosensor Based on Surface Plasmon Resonance

    Directory of Open Access Journals (Sweden)

    Md. Rabiul Hasan

    2017-03-01

    Full Text Available In this paper, we numerically demonstrate a two-layer circular lattice photonic crystal fiber (PCF biosensor based on the principle of surface plasmon resonance (SPR. The finite element method (FEM with circular perfectly matched layer (PML boundary condition is applied to evaluate the performance of the proposed sensor. A thin gold layer is deposited outside the PCF structure, which acts as the plasmonic material for this design. The sensing layer (analyte is implemented in the outermost layer, which permits easy and more practical fabrication process compared to analyte is put inside the air holes. It is demonstrated that, at gold layer thickness of 40 nm, the proposed sensor shows maximum sensitivity of 2200 nm/RIU using the wavelength interrogation method in the sensing range between 1.33–1.36. Besides, using an amplitude interrogation method, a maximum sensitivity of 266 RIU−1 and a maximum sensor resolution of 3.75 × 10−5 RIU are obtained. We also discuss how phase matching points are varied with different fiber parameters. Owing to high sensitivity and simple design, the proposed sensor may find important applications in biochemical and biological analyte detection.

  1. Three-Dimensional Highly Stretchable Conductors from Elastic Fiber Mat with Conductive Polymer Coating.

    Science.gov (United States)

    Duan, Shasha; Wang, Zhihui; Zhang, Ling; Liu, Jin; Li, Chunzhong

    2017-09-13

    The manufacture of stretchable conductors with well-reserved electrical performance under large-degree deformations via scalable processes remains of great importance. In this work, a highly stretchable 3D conductive framework consisting of a polyurethane fiber mat (PUF) and poly(3,4-ethylenedioxythiophene) (PEDOT) is reported through facile approaches, electrospinning, and in situ interfacial polymerization, which was then backfilled with poly(dimethylsiloxane) to obtain 3D conductors. The excellent stretchability of the 3D conductive network imparted the as-prepared electrode a superior mechanical durability. Moreover, the applied strains can be effectively accommodated by the arrangement and orientation of the fibers resulting in a relatively stable electrical performance with only a 20% increased resistance at 100% stretching. Meanwhile, the resistance of the conductor could remain constant during 2000 bending cycles and showed a slight increase during 100 cycles of 50% stretching. The potential in the applications of large-area stretchable electrodes was demonstrated by the construction of LED arrays with the PUF-based conductors as electrical connections.

  2. Self-coated interfacial layer at organic/inorganic phase for temporally controlling dual-drug delivery from electrospun fibers.

    Science.gov (United States)

    Zhao, Xin; Zhao, Jingwen; Lin, Zhi Yuan William; Pan, Guoqing; Zhu, Yueqi; Cheng, Yingsheng; Cui, Wenguo

    2015-06-01

    Implantable tissue engineering scaffolds with temporally programmable multi-drug release are recognized as promising tools to improve therapeutic effects. A good example would be one that exhibits initial anti-inflammatory and long-term anti-tumor activities after tumor resection. In this study, a new strategy for self-coated interfacial layer on drug-loaded mesoporous silica nanoparticles (MSNs) based on mussel-mimetic catecholamine polymer (polydopamine, PDA) layer was developed between inorganic and organic matrix for controlling drug release. When the interface PDA coated MSNs were encapsulated in electrospun poly(L-lactide) (PLLA) fibers, the release rates of drugs located inside/outside the interfacial layer could be finely controlled, with short-term release of anti-inflammation ibuprofen (IBU) for 30 days in absence of interfacial interactions and sustained long-term release of doxorubicin (DOX) for 90 days in presence of interfacial interactions to inhibit potential tumor recurrence. The DOX@MSN-PDA/IBU/PLLA hybrid fibrous scaffolds were further found to inhibit proliferation of inflammatory macrophages and cancerous HeLa cells, while supporting the normal stromal fibroblast adhesion and proliferation at different release stages. These results have suggested that the interfacial obstruction layer at the organic/inorganic phase was able to control the release of drugs inside (slow)/outside (rapid) the interfacial layer in a programmable manner. We believe such interface polymer strategy will find applications in where temporally controlled multi-drug delivery is needed. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Flank wear study of coating carbides and cermet inserts during the dry high speed turning of AISI 1045 steel; Estudio del desgaste del flanco de carburos recubiertos y cermet durante el torneado de alta velocidad en seco del acero AISI 1045

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Gonzalez, L. W.; Perez-Rodriguez, R.; Zambrano-Robledo, P.; Guerrero-Mata, M.; Dumitrescu, L.

    2011-07-01

    This work deals with the experimental study of the flank wear evolution of two coating carbide inserts and a cermet insert during the dry finishing turning of AISI 1045 steel with 400, 500 and 600 m/min cutting speeds. The results were analyzed using the variance analysis and lineal regression analysis in order to describe the relationship between the flank wear and machining time, obtaining the adjusted model equation. The investigation demonstrated a significant effect of cutting speed and machining time on the flank wear at high speed machining. The three coating layers insert showed the best performance while the two layers insert had the worst behaviour of the cutting tool wear at high cutting speeds. (Author) 19 refs.

  4. Coating of Carbon Fiber with Polyhedral Oligomeric Silsesquioxane (POSS to Enhance Mechanical Properties and Durability of Carbon/Vinyl Ester Composites

    Directory of Open Access Journals (Sweden)

    Mujib Khan

    2011-09-01

    Full Text Available Our continuing quest to improve the performance of polymer composites under moist and saltwater environments has gained momentum in recent years with the reinforcement of inorganic nanoparticles into the polymer. The key to mitigate degradation of composites under such environments is to maintain the integrity of the fiber/matrix (F/M interface. In this study, the F/M interface of carbon/vinyl ester composites has been modified by coating the carbon fiber with polyhedral oligomeric silsesquioxane (POSS. POSS is a nanostructured inorganic-organic hybrid particle with a cubic structure having silicon atoms at the core and linked to oxygen atoms. The advantage of using POSS is that the silicon atoms can be linked to a substituent that can be almost any chemical group known in organic chemistry. Cubic silica cores are ‘hard particles’ and are about 0.53 nm in diameter. The peripheral organic unit is a sphere of about 1–3 nm in diameter. Further, cubic structure of POSS remains intact during the polymerization process and therefore with appropriate functional groups, if installed on the fiber surface, would provide a stable and strong F/M interface. Two POSS systems with two different functional groups; namely, octaisobutyl and trisilanolphenyl have been investigated. A set of chemical and mechanical procedures has been developed to coat carbon fibers with POSS, and to fabricate layered composites with vinyl ester resin. Interlaminar shear and low velocity impact tests have indicated around 17–38% improvement in mechanical properties with respect to control samples made without the POSS coating. Saltwater and hygrothermal tests at various environmental conditions have revealed that coating with POSS reduces water absorption by 20–30% and retains the composite properties.

  5. Microwave-Assisted Combustion Synthesis of Nano Iron Oxide/Iron-Coated Activated Carbon, Anthracite, Cellulose Fiber, and Silica, with Arsenic Adsorption Studies

    Directory of Open Access Journals (Sweden)

    Mallikarjuna N. Nadagouda

    2011-01-01

    Full Text Available Combustion synthesis of iron oxide/iron coated carbons such as activated carbon, anthracite, cellulose fiber, and silica is described. The reactions were carried out in alumina crucibles using a Panasonic kitchen microwave with inverter technology, and the reaction process was completed within a few minutes. The method used no additional fuel and nitrate, which is present in the precursor itself, to drive the reaction. The obtained samples were then characterized with X-ray mapping, scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDS, selected area diffraction pattern (SAED, transmission electron microscopy (TEM, X-ray diffraction (XRD, and inductively coupled plasma (ICP spectroscopy. The size of the iron oxide/iron nanoparticle-coated activated carbon, anthracite, cellulose fiber, and silica samples were found to be in the nano range (50–400 nm. The iron oxide/iron nanoparticles mostly crystallized into cubic symmetry which was confirmed by SAED. The XRD pattern indicated that iron oxide/iron nano particles existed in four major phases. That is, γ-Fe2O3, α-Fe2O3, Fe3O4, and Fe. These iron-coated activated carbon, anthracite, cellulose fiber, and silica samples were tested for arsenic adsorption through batch experiments, revealing that few samples had significant arsenic adsorption.

  6. Processing development of 4 tantalum carbide-hafnium carbide and related carbides and borides for extreme environments

    Science.gov (United States)

    Gaballa, Osama Gaballa Bahig

    Carbides, nitrides, and borides ceramics are of interest for many applications because of their high melting temperatures and good mechanical properties. Wear-resistant coatings are among the most important applications for these materials. Materials with high wear resistance and high melting temperatures have the potential to produce coatings that resist degradation when subjected to high temperatures and high contact stresses. Among the carbides, Al4SiC4 is a low density (3.03 g/cm3), high melting temperature (>2000°C) compound, characterized by superior oxidation resistance, and high compressive strength. These desirable properties motivated this investigation to (1) obtain high-density Al4SiC4 at lower sintering temperatures by hot pressing, and (2) to enhance its mechanical properties by adding WC and TiC to the Al4SiC4. Also among the carbides, tantalum carbide and hafnium carbide have outstanding hardness; high melting points (3880°C and 3890°C respectively); good resistance to chemical attack, thermal shock, and oxidation; and excellent electronic conductivity. Tantalum hafnium carbide (Ta4HfC 5) is a 4-to-1 ratio of TaC to HfC with an extremely high melting point of 4215 K (3942°C), which is the highest melting point of all currently known compounds. Due to the properties of these carbides, they are considered candidates for extremely high-temperature applications such as rocket nozzles and scramjet components, where the operating temperatures can exceed 3000°C. Sintering bulk components comprised of these carbides is difficult, since sintering typically occurs above 50% of the melting point. Thus, Ta4 HfC5 is difficult to sinter in conventional furnaces or hot presses; furnaces designed for very high temperatures are expensive to purchase and operate. Our research attempted to sinter Ta4HfC5 in a hot press at relatively low temperature by reducing powder particle size and optimizing the powder-handling atmosphere, milling conditions, sintering

  7. Surface plasmon resonance effect induced tunable polarization filter based on gold film selectively coated photonic crystal fiber

    Science.gov (United States)

    Shi, Min; Li, Shuguang; Chen, Hailiang; Wang, Guangyao; Zhao, Yunyan

    2017-08-01

    A polarization filter based on photonic crystal fiber selectively coated with gold film is investigated. The loss spectra and the dispersion characteristics of the designed polarization filter are studied and analyzed by the finite element method. Simulation results show that the loss of core mode is 433.65 dB/cm in y polarization and 2.64 dB/cm in x polarization at the wavelength of 1.55 μm, respectively. The bandwidth of extinction ratio greater than -20 dB is 150 nm. The corresponding wavelength range is from 1.48 μm to 1.63 μm. The position and size of the little air holes along with the thickness of gold film showed influence on the polarization filter properties. And the proposed polarization filter has stable properties of with difference size and position of the little air holes. The designed polarization filter showing excellent properties can be used in polarizations filter in communication transmission.

  8. A controlled wet-spinning and dip-coating process for preparation of high-permeable TiO2 hollow fiber membranes.

    Science.gov (United States)

    Zhang, Qi; Wang, Hua; Fan, Xinfei; Chen, Shuo; Yu, Hongtao; Quan, Xie

    2016-01-01

    In order to improve the permeate flux of photocatalytic membranes, we present an approach for coupling TiO2 with ceramic hollow fiber membranes. The ceramic hollow fiber membranes with high permeate flux were fabricated by a controlled wet-spinning process using polyethersulfone (PESf) and ceramic powder as precursors and 1-methyl-2-pyrrolidinone as solvent, and the subsequent TiO2 coating was performed by a dip-coating process using tetra-n-butyl titanate as precursor. It has been found that the PESf/ceramic powder ratio could influence the structure of the membranes. Here the as-prepared TiO2 hollow fiber membranes had a pure water flux of 4,450 L/(m(2)·h). The performance of the TiO2 hollow fiber membrane was evaluated using humic acid (HA) as a test substance. The results demonstrated that this membrane exhibited a higher permeate flux under UV irradiation than in the dark and the HA removal efficiency was enhanced. The approach described here provides an operable route to the development of high-permeable photocatalytic membranes for water treatment.

  9. Drops and waves on a viscous film coating a vertical fiber

    Science.gov (United States)

    Duprat, Camille; Giorgiutti-Dauphine, Frederique

    2009-11-01

    We consider the nonlinear dynamics of a liquid viscous film flowing down a vertical fiber. The initially flat film spontaneously breaks up into a regular wavetrain due to the Rayleigh-Plateau instability. The characteristics of the fully developed structures then depend on the dominant mechanisms. When the advection of the waves by the flow dominates over the instability, we observe moderate amplitude waves that propagate without carrying mass. When surface tension is strong, the film breaks up into large amplitude drops exhibiting a recirculation region. The transition between drops and waves regimes and the corresponding structures have been characterized experimentally and numerically. When both surface tension and viscosity effects are strong, the system can be seen has a paradigm for active (unstable), dissipative and dispersive media. The particular shape of the resulting structures gives rise to complex interactions (attraction and repulsion) leading to the formation of bound states. The system then appears to select a finite number of preferred specific distances in agreement with a weak interaction theory developed by D. Tseluiko, S. Saprykin and S. Kalliadasis (Imperial College London).

  10. Nanoscale patterning of gold-coated optical fibers for improved plasmonic sensing

    Science.gov (United States)

    Antohe, Iulia; Spasic, Dragana; Delport, Filip; Li, Jiaqi; Lammertyn, Jeroen

    2017-05-01

    Merging surface plasmon resonance (SPR) to fiber optic (FO) technology has brought remarkable achievements in the field by offering attractive advantages over the conventional prism-based SPR platforms, such as simplicity, cost-effectiveness and miniaturization. However, the performance of the existing FO-SPR instruments mainly depends on the device surface condition and in particular on the structural aspect of the thin gold (Au) plasmonic film deposited on the FO substrate. In this work, a simple cost-effective colloidal lithography technique (CLT) was adapted and applied for the first time to the micrometer-sized FO substrate, to design end reflection-type FO-SPR sensors with periodic arrays of Au triangularly-shaped nanostructures on the Au mirror FO tip distal end. The nanopatterned FO-SPR sensor tips were afterwards subjected to refractometric measurements in a sucrose dilution series and subsequently compared with their non-patterned counterparts. It was observed that the spectral dips of the nanopatterned FO-SPR sensor tips were shifted towards longer wavelengths after CLT patterning. Moreover, the sensor sensitivity was improved with up to 25% compared to the conventional non-patterned FO-SPR devices. The obtained results represent important steps in the development of a new generation of FO-SPR sensors with improved performance, which can ultimately be used in various applications, ranging from food analysis and environmental monitoring, to health control and medical diagnosis.

  11. Characterization and control of the fiber-matrix interface in ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Lowden, R.A.

    1989-03-01

    Fiber-reinforced SiC composites fabricated by thermal-gradient forced-flow chemical-vapor infiltration (FCVI) have exhibited both composite (toughened) and brittle behavior during mechanical property evaluation. Detailed analysis of the fiber-matrix interface revealed that a silica layer on the surface of Nicalon Si-C-O fibers tightly bonds the fiber to the matrix. The strongly bonded fiber and matrix, combined with the reduction in the strength of the fibers that occurs during processing, resulted in the observed brittle behavior. The mechanical behavior of Nicalon/SiC composites has been improved by applying thin coatings (silicon carbide, boron, boron nitride, molybdenum, carbon) to the fibers, prior to densification, to control the interfacial bond. Varying degrees of bonding have been achieved with different coating materials and film thicknesses. Fiber-matrix bond strengths have been quantitatively evaluated using an indentation method and a simple tensile test. The effects of bonding and friction on the mechanical behavior of this composite system have been investigated. 167 refs., 59 figs., 18 tabs.

  12. Metal-organic framework-199/graphite oxide hybrid composites coated solid-phase microextraction fibers coupled with gas chromatography for determination of organochlorine pesticides from complicated samples.

    Science.gov (United States)

    Zhang, Suling; Du, Zhuo; Li, Gongke

    2013-10-15

    The hybrid material of a copper-based metal-organic framework (MOF-199) and graphite oxide (GO) was explored as the solid-phase microextraction (SPME) coating for the first time. This fiber was fabricated by using 3-amino-propyltriethoxysilane (APTES) as the cross-linking agent, which enhanced its durability and allowed more than 140 replicate extractions. With the incorporation of GO, the MOF-199/GO fibers with GO contents ranging from 5 to 15 wt% exhibited enhanced adsorption affinity to organochlorine pesticides (OCPs) compared to MOF or GO individually. This improvement was linked to the enhanced dispersive forces (increased volume of small pores) that provided by the dense carbon layers of GO. Combining the superior properties of high porosity of MOFs and the unique layered character of GO, the MOF-199/GO (10 wt%) fiber exhibited higher adsorption affinity to some OCPs than commercial polydimethylsiloxane (PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibers. This new fiber was developed for headspace (HS) SPME of eight OCPs followed by GC/ECD analysis. The limits of detection were 2.3-6.9 ng/L. The relative standard deviation (RSD) for five replicate extractions using one fiber ranged from 5.3% to 8.8%. The fiber-to-fiber reproducibility was 5.2-12.8%. This method was successfully used for simultaneous determination of eight OCPs from river water, soil, water convolvulus and longan with satisfactory recoveries of 90.6-104.4%, 82.7-96.8%, 72.2-107.7% and 82.8-94.3%, respectively. These results indicated the MOF-199/GO composite provided a promising alternative in sample pretreatment. © 2013 Elsevier B.V. All rights reserved.

  13. Development of diamond coated tool and its performance in ...

    Indian Academy of Sciences (India)

    ... could maintain low level of cutting forces and remarkably improved surface finish. It has been further revealed that success of the diamond coated tool depends primarily on adhesion of the diamond coating with the carbide substrate and this is strongly influenced by the pre-treatment of the carbide substrate surface before ...

  14. Scatter in Carbon/Silicon Carbide (C/SiC) Composites Quantified

    Science.gov (United States)

    Murthy, Pappu L. N.; Gyekenyesi, John P.; Mital, Subodh K.

    2004-01-01

    Carbon-fiber-reinforced silicon carbide matrix (C/SiC) composites processed by chemical vapor infiltration are candidate materials for aerospace thermal structures. Carbon fibers can retain properties at very high temperatures, but they are known to have poor oxidation resistance in adverse, high-temperature environments. Nevertheless, the combination of CVI-SiC matrix with higher stiffness and oxidation resistance, the interfacial coating, and additional surface-seal coating provides the necessary protection to the carbon fibers, and makes the material viable for high-temperature space applications operating under harsh environments. Furthermore, C/SiC composites, like other ceramic matrix composites (CMCs), exhibit graceful non-catastrophic failure because of various inherent energy dissipating mechanisms. The material exhibits nonlinearity in deformation even at very low stress levels. This is the result of the severe matrix microcracking present in the as processed composite because of large differences between the coefficients of thermal expansion of the fiber and the matrix. Utilization of these advanced composites in next generation space vehicles will require innovative structural configurations, updated materials, and refined analyses. Structural safety issues for these vehicles are in direct competition with performance and cost. One would have to quantify the uncertainties associated with the design using formal probabilistic methods. Specifically four fundamental aspects on which analyses are based-- (1) loading conditions, (2) material behavior, (3) geometrical configurations, and (4) structural connections between the composite components and baseline structure--are stochastic in nature. A direct way to formally account for uncertainties is to develop probabilistic structural analysis methods where all participating variables are described by appropriate probability density functions. The present work, however, focuses on analyzing the stochastic

  15. A Novel Polyaniline-Coated Bagasse Fiber Composite with Core-Shell Heterostructure Provides Effective Electromagnetic Shielding Performance.

    Science.gov (United States)

    Zhang, Yang; Qiu, Munan; Yu, Ying; Wen, Bianying; Cheng, Lele

    2017-01-11

    A facile route was proposed to synthesize polyaniline (PANI) uniformly deposited on bagasse fiber (BF) via a one-step in situ polymerization of aniline in the dispersed system of BF. Correlations between the structural, electrical, and electromagnetic properties were extensively investigated. Scanning electron microscopy images confirm that the PANI was coated dominantly on the BF surface, indicating that the as-prepared BF/PANI composite adopted the natural and inexpensive BF as its core and the PANI as the shell. Fourier transform infrared spectra suggest significant interactions between the BF and PANI shell, and a high degree of doping in the PANI shell was achieved. X-ray diffraction results reveal that the crystallization of the PANI shell was improved. The dielectric behaviors are analyzed with respect to dielectric constant, loss tangent, and Cole-Cole plots. The BF/PANI composite exhibits superior electrical conductivity (2.01 ± 0.29 S·cm-1), which is higher than that of the pristine PANI with 1.35 ± 0.15 S·cm-1. The complex permittivity, electromagnetic interference (EMI), shielding effectiveness (SE) values, and attenuation constants of the BF/PANI composite were larger than those of the pristine PANI. The EMI shielding mechanisms of the composite were experimentally and theoretically analyzed. The absorption-dominated total EMI SE of 28.8 dB at a thickness of 0.4 mm indicates the usefulness of the composite for electromagnetic shielding. Moreover, detailed comparison of electrical and EMI shielding properties with respect to the BF/PANI, dedoped BF/PANI composite, and the pristine PANI indicate that the enhancement of electromagnetic properties for the BF/PANI composite was due to the improved conductivity and the core-shell architecture. Thus, the composite has potential commercial applications for high-performance electromagnetic shielding materials and also could be used as a conductive filler to endow polymers with electromagnetic shielding

  16. Highly Stretchable Conductive Fibers from Few-Walled Carbon Nanotubes Coated on Poly(m-phenylene isophthalamide) Polymer Core/Shell Structures.

    Science.gov (United States)

    Jiang, Shujuan; Zhang, Hongbo; Song, Shaoqing; Ma, Yanwen; Li, Jinghua; Lee, Gyeong Hee; Han, Qiwei; Liu, Jie

    2015-10-27

    A core/shell stretchable conductive composite of a few-walled carbon nanotube network coated on a poly(m-phenylene isophthalamide) fiber (FWNT/PMIA) was fabricated by a dip-coating method and an annealing process that greatly enhanced interactions between the FWNT network and PMIA core as well as within the FWNT network. The first strain-conductivity test of the as-prepared FWNT/PMIA fiber showed a stretching-induced alignment of nanotubes in the shell during the deformation process and a good conductivity stability with a slight conductivity drop from 109.63 S/cm to 98.74 S/cm (Δσ/σ0 = 10%) at a strain of ∼150% (2.5 times the original length). More importantly, after the first stretching process, the fiber can be recovered with a slight increase in length but a greatly improved conductivity of 167.41 S/cm through an additional annealing treatment. The recovered fiber displays a similarly superb conductivity stability against stretching, with a decrease of only ∼13 S/cm to 154.49 S/cm (Δσ/σ0 = 8%) at a strain of ∼150%. We believe that this conductivity stability came from the formation and maintaining of aligned nanotube structures during the stretching process, which ensures the good tube-tube contacts and the elongation of the FWNT network without losing its conductivity. Such stable conductivity in stretchable fibers will be important for applications in stretchable electronics.

  17. Ultrasound-promoted coating of MOF-5 on silk fiber and study of adsorptive removal and recovery of hazardous anionic dye "congo red".

    Science.gov (United States)

    Khanjani, Somayeh; Morsali, Ali

    2014-07-01

    A metal-organic framework MOF-5 has been synthesized on silk fiber through electrostatic layer-by-layer assembly. The silk surface coating was formed via sequential dipping in an alternating bath of metal and ligand solutions at room temperature by direct mixing. SEM was used to investigate the growth of MOF-5 coating as materials for separation membrane due to their desirable properties in adsorptive removal of congo red (CR) from contaminated water. The adsorption capacity of MOF-5 is remarkable high in the liquid phase. The adsorption of CR at various concentration and contact time in spontaneous process were studied. The silk fibers containing MOF-5 open a wide field of possible applications, such as protection layers or membranes in pollution remediation wastewater and any effluent. Desorption of the dye can be carried out by using NaOH solution with more than about 50% recovery of congo red from MOF-5 coated on silk membrane filtration. In order to investigate the role of sonicating on the morphology of products, one of the reactions was performed with ultrasound irradiation and the crystal growth is completed more than other methods. The samples and adsorption of CR were characterized with SEM, powder X-ray diffraction (XRD) and UV-visible spectroscopy. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Photonic crystal fiber modal interferometer with Pd/WO3 coating for real-time monitoring of dissolved hydrogen concentration in transformer oil.

    Science.gov (United States)

    Zhang, Ya-Nan; Wu, Qilu; Peng, Huijie; Zhao, Yong

    2016-12-01

    A highly-sensitive and temperature-robust photonic crystal fiber (PCF) modal interferometer coated with Pd/WO3 film was fabricated and studied, aiming for real-time monitoring of dissolved hydrogen concentration in transformer oil. The sensor probe was fabricated by splicing two segments of a single mode fiber (SMF) with both ends of the PCF. Since the collapse of air holes in the PCF in the interfaces between SMF and PCF, a SMF-PCF-SMF interferometer structure was formed. The Pd/WO3 film was fabricated by sol-gel method and coated on the surface of the PCF by dip-coating method. When the Pd/WO3 film is exposed to hydrogen, both the length and cladding refractive index of the PCF would be changed, resulting in the resonant wavelength shift of the interferometer. Experimental results showed that the hydrogen measurement sensitivity of the proposed sensor can reach 0.109 pm/(μl/l) in the transformer oil, with the measurement range of 0-10 000 μl/l and response time less than 33 min. Besides, the proposed sensor was temperature-insensitive without any compensation process, easy to fabricate without any tapering, polishing, or etching process, low cost and quickly response without any oil-gas separation device. All these performances satisfy the actual need of real-time monitoring of dissolved hydrogen concentration in the transformer oil.

  19. Ruthenium recovery from acetic acid industrial effluent using chemically stable and high-performance polyethylenimine-coated polysulfone-Escherichia coli biomass composite fibers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sok [Division of Environmental Science and Ecological Engineering, College of Life Sciences and Biotechnology, Korea University, Seoul 02841 (Korea, Republic of); Division of Semiconductor and Chemical Engineering, Chonbuk National University, Jeonbuk 54896 (Korea, Republic of); Choi, Yoon-E, E-mail: yechoi@korea.ac.kr [Division of Environmental Science and Ecological Engineering, College of Life Sciences and Biotechnology, Korea University, Seoul 02841 (Korea, Republic of); Yun, Yeoung-Sang, E-mail: ysyun@jbnu.ac.kr [Division of Semiconductor and Chemical Engineering, Chonbuk National University, Jeonbuk 54896 (Korea, Republic of); Department of Bioprocess Engineering, Chonbuk National University, Jeonbuk 54896 (Korea, Republic of)

    2016-08-05

    Highlights: • The PEI-PSBF was fabricated and used for Ru recovery from industrial effluent. • PEI-PSBF was not swollen nor dissolved in the effluent. • PEI-PSBF showed superior sorption capacity to commercial resins. • Thin fiber type PEI-PSBF could be successfully applied in flow-through column. - Abstract: Recovery of precious metal ions from waste effluents is of high concern. In general, ruthenium (Ru) is used in the Cativa process as promoter for carbonylation catalyst and discharged into acetic acid effluent. In the present work, we have designed and developed polyethylenimine-coated polysulfone-bacterial biomass composite fiber (PEI-PSBF) to recover Ru from industrial effluent. The sorbent was manufactured by electrostatic attachment of polyethylenimine (PEI) to the surface of polysulfone-biomass composite fiber (PSBF), which was prepared through spinning of the mixture of polysulfone and Escherichia coli biomass in N,N-dimethylformamide (DMF) into water. Developed PEI-PSBF was highly stable in the acetic acid effluent. The maximum sorption capacity of the developed sorbent PEI-PSBF, coated with PEI (with M.W. of 75,000), was 121.28 ± 13.15 mg/g, which was much higher than those of ion exchange resins, TP214, Amberjet 4200, and M500. The PEI-PSBF could be successfully applied in the flow-through column system, showing 120 beds of breakthrough volume.

  20. Silicon Carbide Nanotube Oxidation at High Temperatures

    Science.gov (United States)

    Ahlborg, Nadia; Zhu, Dongming

    2012-01-01

    Silicon Carbide Nanotubes (SiCNTs) have high mechanical strength and also have many potential functional applications. In this study, SiCNTs were investigated for use in strengthening high temperature silicate and oxide materials for high performance ceramic nanocomposites and environmental barrier coating bond coats. The high · temperature oxidation behavior of the nanotubes was of particular interest. The SiCNTs were synthesized by a direct reactive conversion process of multiwall carbon nanotubes and silicon at high temperature. Thermogravimetric analysis (TGA) was used to study the oxidation kinetics of SiCNTs at temperatures ranging from 800degC to1300degC. The specific oxidation mechanisms were also investigated.

  1. Examination of tapered plastic multimode fiber-based sensor performance with silver coating for different concentrations of calcium hypochlorite by soft computing methodologies--a comparative study.

    Science.gov (United States)

    Zakaria, Rozalina; Sheng, Ong Yong; Wern, Kam; Shamshirband, Shahaboddin; Wahab, Ainuddin Wahid Abdul; Petković, Dalibor; Saboohi, Hadi

    2014-05-01

    A soft methodology study has been applied on tapered plastic multimode sensors. This study basically used tapered plastic multimode fiber [polymethyl methacrylate (PMMA)] optics as a sensor. The tapered PMMA fiber was fabricated using an etching method involving deionized water and acetone to achieve a waist diameter and length of 0.45 and 10 mm, respectively. In addition, a tapered PMMA probe, which was coated by silver film, was fabricated and demonstrated using a calcium hypochlorite (G70) solution. The working mechanism of such a device is based on the observation increment in the transmission of the sensor that is immersed in solutions at high concentrations. As the concentration was varied from 0 to 6 ppm, the output voltage of the sensor increased linearly. The silver film coating increased the sensitivity of the proposed sensor because of the effective cladding refractive index, which increases with the coating and thus allows more light to be transmitted from the tapered fiber. In this study, the polynomial and radial basis function (RBF) were applied as the kernel function of the support vector regression (SVR) to estimate and predict the output voltage response of the sensors with and without silver film according to experimental tests. Instead of minimizing the observed training error, SVR_poly and SVR_rbf were used in an attempt to minimize the generalization error bound so as to achieve generalized performance. An adaptive neuro-fuzzy interference system (ANFIS) approach was also investigated for comparison. The experimental results showed that improvements in the predictive accuracy and capacity for generalization can be achieved by the SVR_poly approach in comparison to the SVR_rbf methodology. The same testing errors were found for the SVR_poly approach and the ANFIS approach.

  2. Photocatalytic Degradation of 2, 4-dichlorophenol using N-doped SnO2/TiO2 Thin Film Coated Glass Fibers

    Directory of Open Access Journals (Sweden)

    Peerawas Kongsong

    2017-07-01

    Full Text Available Photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP contaminant in water was investigated. Composite SnO2/TiO2 films N-doped to varying degrees were prepared via sol-gel method, and coated on glass fibers by dipping method. The effects of nitrogen-doping on coating morphology, physical properties, and glyphosate degradation rates were experimentally determined. Nitrogen-doping shifted absorption wavelengths and narrowed the energy band gap, enhancing photocatalytic performance. The maximum efficiency of 2,4-DCP degradation was up to 93.65% for 12 h of 40N/SnO2/TiO2 composite film. The near optimal 40N/SnO2/TiO2 composite thin film exhibited about 4 folds degradation rates relative to pure TiO2, and should perform well in water purification applications.

  3. Silica-coated gold nanorods as saturable absorber for bound-state pulse generation in a fiber laser with near-zero dispersion

    Science.gov (United States)

    Wang, Xude; Luo, Aiping; Luo, Zhichao; Liu, Meng; Zou, Feng; Zhu, Yanfang; Xue, Jianping; Xu, Wencheng

    2017-11-01

    We presented a bound-state operation in a fiber laser with near-zero anomalous dispersion based on a silica-coated gold nanorods (GNRs@SiO2) saturable absorber (SA). Using a balanced twin detector measurement technique, the modulation depth and nonsaturable loss of the GNRs@SiO2 SA were measured to be approximately 3.5% and 39.3%, respectively. By virtue of the highly nonlinear effect of the GNRs@SiO2 SA, the bound-state pulses could be easily observed. Besides the lower-order bound-state pulses with two, three, and four solitons, the higher-order bound states with up to 12 solitons were also obtained in the laser cavity. The pulse profiles of the higher-order bound states were further reconstructed theoretically. The experimental results would give further insight towards understanding the complex nonlinear dynamics of bound-state pulses in fiber lasers.

  4. Three dimensionally honeycomb layered double hydroxides framework as a novel fiber coating for headspace solid-phase microextraction of phenolic compounds.

    Science.gov (United States)

    Abolghasemi, Mir Mahdi; Yousefi, Vahid

    2014-06-06

    A new solid phase microextraction (SPME) fiber based on high-temperature three dimensionally honeycomb layered double hydroxide (TDH-LDH) material is presented. The fiber coating can be prepared easily, it is mechanically stable and exhibits relatively high thermal stability. This study shows that three dimensionally honeycomb layered double hydroxide generated porous morphology. The TDH-LDH material was tested for the extraction of some phenolic and polycyclic aromatic hydrocarbon compounds from aqueous sample solutions in combination with gas chromatography-mass spectrometry (GC-MS). The TDH-LDH fiber contains polar groups and its efficiency for non-polar polycyclic aromatic hydrocarbon compounds was lower than phenolic compounds. On the other hand, a high tendency towards the adsorption of polar phenolic compounds was observed for the proposed fiber. The effects of the extraction and desorption parameters including extraction temperature, extraction time, ionic strength, stirring rate, pH and desorption temperature and time have been studied. In optimum conditions, the repeatability for one fiber (n=5), expressed as relative standard deviation (R.S.D. %), was between 2.8% and 7.1% for the phenolic compounds. The detection limits for the studied phenolic compounds were between 0.02 and 5.8 ng mL(-1). The developed method offers the advantage of being simple to use, with shorter analysis time, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Evidence for a silicon oxycarbide phase in the Nicalon silicon carbide fibre

    Energy Technology Data Exchange (ETDEWEB)

    Porte, L.; Sartre, A.

    1989-01-01

    The Nicalon silicon carbide fibre has been studied by X-ray photoelectron spectroscopy. Elements entering the fiber are carbon, silicon and oxygen. In addition to previously reported chemical entities (silicon carbide, silica and graphitic carbon) evidence is found of the presence of a new supplementary phase which is attributed to an intermediate silicon oxycarbide phase. As this phase is found to participate in very appreciable proportions to the composition of the fiber, some influence on the properties of this fiber can be anticipated. 17 references.

  6. Near Infrared Characterization of Hetero-Core Optical Fiber SPR Sensors Coated with Ta2O5 Film and Their Applications

    Directory of Open Access Journals (Sweden)

    Kazuhiro Watanabe

    2012-02-01

    Full Text Available This paper describes the characteristics of optical fiber sensors with surface plasmon resonance (SPR at 1,310 nm in which the scattering loss of silica optical fiber is low. SPR operation in the infrared wavelength range is achieved by coating a thin tantalum pentaoxide (Ta2O5 film. The novelty of this paper lies in the verification of how the hetero-core scheme could be operated as a commercial base candidate in the sense of easy fabrication, sufficient mechanical strength, and significant sensitivity as a liquid detector under the basis of a low loss transmission network in the near infrared wavelength region. The effect of Ta2O5 layer thickness has been experimentally revealed in the wavelength region extending to 1,800 nm by using the hetero-core structured optical fiber. SPR characterizations have been made in the wavelength region 1,000–1,300 nm, showing the feasible operation at the near infrared wavelength and the possible practical applications. In addition, the technique developed in this work has been interestingly applied to a multi-point water-detection and a water-level gauge in which tandem-connected SPR sensors system using hetero-core structured fibers were incorporated. The detailed performance characteristics are also shown on these applications.

  7. Polymethacrylate Coated Electrospun PHB Fibers as a Functionalized Platform for Bio-Diagnostics: Confirmation Analysis on the Presence of Immobilized IgG Antibodies against Dengue Virus

    Directory of Open Access Journals (Sweden)

    Samira Hosseini

    2017-10-01

    Full Text Available In this article, a combination of far field electrospinning (FFES and free-radical polymerization has been used to create a unique platform for protein immobilization via the physical attachment of biomolecules to the surface of the fiber mats. The large specific surface area of the fibers with its tailored chemistry provides a desirable platform for effective analyte-surface interaction. The detailed analysis of protein immobilization on a newly developed bio-receptive surface plays a vital role to gauge its advantages in bio-diagnostic applications. We relied on scanning electron microscopy (SEM, diameter range analysis, and X-ray photoelectron spectroscopy (XPS, along with thermal gravimetric analysis (TGA, water-in-air contact angle analysis (WCA, Fourier transform infrared spectroscopy (FTIR, and atomic force microscopy (AFM to study our developed platforms and to provide valuable information regarding the presence of biomolecular entities on the surface. Detailed analyses of the fiber mats before and after antibody immobilization have shown obvious changes on the surface of the bioreceptive surface including: (i an additional peak corresponding to the presence of an antibody in TGA analysis; (ii extra FTIR peaks corresponding to the presence of antibodies on the coated fiber platforms; and (iii a clear alteration in surface roughness recorded by AFM analysis. Confirmation analyses on protein immobilization are of great importance as they underlay substantial grounds for various biosensing applications.

  8. Immobilization of trypsin in the layer-by-layer coating of graphene oxide and chitosan on in-channel glass fiber for microfluidic proteolysis.

    Science.gov (United States)

    Bao, Huimin; Chen, Qiwen; Zhang, Luyan; Chen, Gang

    2011-12-21

    In this report, trypsin was immobilized in the layer-by-layer (LBL) coating of graphene oxide (GO) and chitosan on a piece of glass fiber to fabricate microchip bioreactor for efficient proteolysis. LBL deposition driven by electrostatic forces easily took place on the surface of the glass fiber, providing mild environmental conditions so that the denaturation and autolysis of the immobilized trypsin was minimized. Prior to use, a piece of the prepared trypsin-immobilized glass fiber was inserted into the channel of a microchip to form a core-changeable bioreactor. The novel GO-based bioreactor can be regenerated by changing its fiber core. The feasibility and performance of the unique bioreactor were demonstrated by the tryptic digestion of bovine serum albumin, myoglobin, cytochrome c, and hemoglobin and the digestion time was significantly reduced to less than 10 s. The obtained digests were identified by MALDI-TOF MS. The digestion performance of the core-changeable GO-based microchip bioreactor was comparable to that of 12-h in-solution tryptic digestion. The novel microchip bioreactor is simple and efficient, offering great promise for high-throughput protein identification.

  9. Synthesis of high active catalytic systems based on double molybdenum carbides

    OpenAIRE

    Dolmatov Vladimir; Kuznetsov Sergey; Rebrov Evgeny; Schouten Jacob Cornelis

    2015-01-01

    A new two-stage synthesis of double molybdenum and nickel carbides and high active and stable catalytic coatings of nickelpromoter molybdenum carbide in molten salts is developed. The first stage includes the formation of molybdenum–nickel alloys by an electrolytic method and currentless transfer in chloride melts. The second stage consists in the carbonization of the alloys in chloride-carbonate melt under various synthesis conditions. The stabilities of the nickel-promoter catalyti...

  10. Enhanced attached growth of microalgae Scenedesmus. LX1 through ambient bacterial pre-coating of cotton fiber carriers.

    Science.gov (United States)

    Zhuang, Lin-Lan; Azimi, Yaldah; Yu, Dawei; Wang, Wen-Long; Wu, Yin-Hu; Dao, Guo-Hua; Hu, Hong-Ying

    2016-10-01

    The role of bacteria/extracellular polymeric substances (EPS) coated carriers on attached microalgae growth in suspended-solid phase photobioreactor (sspBR) was assessed in this study. The results showed that pre-coating cotton with ambient bacteria and their EPS improved the attached microalgal growth by as much as 230% in terms of attached microalgae density. Additionally, the single cell dry weight, chemical composition and oxygen evolving activity of attached microalgae were significantly affected by the presence of bacteria/EPS coating on the cotton carriers. The protein content of microalgae cells cultivated in the ssPBRs with carriers coated by bacteria and sterilized bacteria were on average 26% and 15% more than uncoated carriers, respectively. Through absorbing and immobilizing nutrients from the bulk medium, the bacteria/EPS coating provided the attached microalgae with nitrogen/phosphorus for protein synthesis, especially during the late stages of batch cultivation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Fabrication of Metal-Organic Framework MOF-177 Coatings on Stainless Steel Fibers for Head-Space Solid-Phase Microextraction of Phenols.

    Science.gov (United States)

    Wang, Guan-Hua; Lei, Yong-Qian

    2017-08-01

    Direct head-space solid-phase microextraction (HS-SPME) of phenols in water is usually difficult due to its polarity and solubility in aqueous matrix. Herein we report the fabrication of metal-organic framework MOF-177 coated stainless steel fiber for the HS-SPME of phenols (2-methylolphenol, 4-methylolphenol, 2,4-dimethylolphenol, 2,4-dichlorphenol, and 3-methyl-4-chlorophenol) in environmental water samples prior to the gas chromatography-mass spectrometry detection. Several parameters affecting the extraction efficiency were optimized in the experiment, including extraction temperature and time, the pH value and salt addition. The results indicated that the coated fiber gave low detection limits (0.015-0.043 μg L(-1)) and good repeatability with the RSD ranging from 2.8% to 5.5% for phenols. The recoveries are between 84.5%-98.6% with the spiked level of 10 μg L(-1) for the real water samples. The established method may afford a kind of potential enrichment material and a reference method for the analysis of methylphenols in water samples.

  12. ENTIRELY AQUEOUS SOLUTION-GEL ROUTE FOR THE PREPARATION OF ZIRCONIUM CARBIDE, HAFNIUM CARBIDE AND THEIR TERNARY CARBIDE POWDERS

    Directory of Open Access Journals (Sweden)

    Zhang Changrui

    2016-07-01

    Full Text Available An entirely aqueous solution-gel route has been developed for the synthesis of zirconium carbide, hafnium carbide and their ternary carbide powders. Zirconium oxychloride (ZrOCl₂.8H₂O, malic acid (MA and ethylene glycol (EG were dissolved in water to form the aqueous zirconium carbide precursor. Afterwards, this aqueous precursor was gelled and transformed into zirconium carbide at a relatively low temperature (1200 °C for achieving an intimate mixing of the intermediate products. Hafnium and the ternary carbide powders were also synthesized via the same aqueous route. All the zirconium, hafnium and ternary carbide powders exhibited a particle size of ∼100 nm.

  13. High-Melt Carbon-Carbon Coating for Nozzle Extensions

    Science.gov (United States)

    Thompson, James

    2015-01-01

    Carbon-Carbon Advanced Technologies, Inc. (C-CAT), has developed a high-melt coating for use in nozzle extensions in next-generation spacecraft. The coating is composed primarily of carbon-carbon, a carbon-fiber and carbon-matrix composite material that has gained a spaceworthy reputation due to its ability to withstand ultrahigh temperatures. C-CAT's high-melt coating embeds hafnium carbide (HfC) and zirconium diboride (ZrB2) within the outer layers of a carbon-carbon structure. The coating demonstrated enhanced high-temperature durability and suffered no erosion during a test in NASA's Arc Jet Complex. (Test parameters: stagnation heat flux=198 BTD/sq ft-sec; pressure=.265 atm; temperature=3,100 F; four cycles totaling 28 minutes) In Phase I of the project, C-CAT successfully demonstrated large-scale manufacturability with a 40-inch cylinder representing the end of a nozzle extension and a 16-inch flanged cylinder representing the attach flange of a nozzle extension. These demonstrators were manufactured without spalling or delaminations. In Phase II, C-CAT worked with engine designers to develop a nozzle extension stub skirt interfaced with an Aerojet Rocketdyne RL10 engine. All objectives for Phase II were successfully met. Additional nonengine applications for the coating include thermal protection systems (TPS) for next-generation spacecraft and hypersonic aircraft.

  14. Fiber Bragg distributed chemical sensor

    NARCIS (Netherlands)

    Boersma, A.; Saalmink, M.; Lucassen, T.; Wiegersma, S.; Jansen, T.H.; Jansen, R.; Cheng, L.K.

    2011-01-01

    A distributed chemical sensor is developed by coating multiple Bragg gratings in a single glass fiber with chemical responsive coatings. The composition of the coating is tuned to the target chemicals to be measured and the optical response of the coated grating is optimized by changing the coating

  15. A comparison between the effect of zirconia-coated FRC and glass fiber posts on the fracture resistance of endodontically treated teeth

    Directory of Open Access Journals (Sweden)

    Ezatollah Jalalian

    2014-04-01

    Full Text Available   Background and Aims : The root fracture resistance of endodontically treated teeth depends on the types of posts. The aim of this study was to compare the effect of two types of bonded non-metallic posts with different elasticity modulus on the fracture resistance of endodontically treated teeth under compressive loads.   Materials and Methods: In this in vitro experimental study, 20 fresh extracted mandibular premolars were selected and sectioned adjacent to the CEJ and then were endodontically treated. The specimens were randomly divided into two groups (n=10. After post space preparations, the fiber RTD Light posts (R.T.D, France and zirconia coated fiber posts (ICE light, Danville were cemented into the root canals. Composite resin (Lumiglass R.T.D, France cores were built up. Aluminium foil was used to mimic the PDL, and the specimens were embedded in acrylic resin and tested in a Universal Testing Machine. A compressive load was applied at a 90 degree angle until fracture at a crosshead speed of 1mm/min. Data were analyzed using one-way ANOVA and T test .   Results: The mean fracture resistance of R.T.D group was (1083.11 ± 156.74 (N and the mean of ICE light group was (865.18 ± 106.24 (N. The highest mean fracture resistance was observed in RTD fiberglass and a statistically significant difference was observed between the two groups (P<0.001.   Conclusion: FRC posts with zirconia coating due to unfavorable fractures of the teeth should be used with caution, and thus, fiber posts are preferred.

  16. Determination of chlorophenols in landfill leachate using headspace sampling with ionic liquid-coated solid-phase microextraction fibers combined with gas chromatography-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Tse-Tsung; Chen, Chung-Yu [Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan (China); Li Zuguang [Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan (China); College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014, Zhejiang (China); Yang, Thomas Ching-Cherng [Department of Chemistry, National Kaohsiung Normal University, Kaohsiung 82444, Taiwan (China); Lee, Maw-Rong, E-mail: mrlee@dragon.nchu.edu.tw [Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan (China)

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer Ionic liquid (IL), ([C{sub 4}MIM][PF{sub 6}]), was rapid synthesized by microwave radiation. Black-Right-Pointing-Pointer Trace chlorophenols in landfill leachate were extract by SPME coated IL. Black-Right-Pointing-Pointer The IL-coated SPME-GC/MS method is low-cost, solvent-free and sensitive. - Abstract: A new microextraction technique based on ionic liquid solid-phase microextraction (IL-SPME) was developed for determination of trace chlorophenols (CPs) in landfill leachate. The synthesized ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C{sub 4}MIM][PF{sub 6}]), was coated onto the spent fiber of SPME for extraction of trace CPs. After extraction, the absorbed analytes were desorbed and quantified using gas chromatography-mass spectrometry (GC/MS). The term of the proposed method is as ionic liquid-coated of solid-phase microextraction combined with gas chromatography-mass spectrometry (IL-SPME-GC/MS). No carryover effect was found, and every laboratory-made ionic liquids-coated-fiber could be used for extraction at least eighty times without degradation of efficiency. The chlorophenols studied were 2,4-dichlorophenol (2,4-DP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP). The best results of chlorophenols analysis were obtained with landfill leachate at pH 2, headspace extraction for 4 min, and thermal desorption with the gas chromatograph injector at 240 Degree-Sign C for 4 min. Linearity was observed from 0.1 to 1000 {mu}g L{sup -1} with relative standard deviations (RSD) less than 7% and recoveries were over 87%. The limit of detection (LOD) for pentachlorophenol was 0.008 {mu}g L{sup -1}. The proposed method was tested by analyzing landfill leachate from a sewage farm. The concentrations of chlorophenols were detected to range from 1.1 to 1.4 {mu}g L{sup -1}. The results demonstrate that the IL-SPME-GC/MS method is highly effective in

  17. Design and fabrication of carbon fibers with needle-like nano-HA coating to reinforce granular nano-HA composites.

    Science.gov (United States)

    Wang, Xudong; Zhao, Xueni; Zhang, Li; Wang, Wanying; Zhang, Jing; He, Fuzhen; Yang, Jianjun

    2017-08-01

    Carbon fibers (CFs) with needle-like nano-hydroxyapatite (nHA) coating were first used as reinforcing materials named nHA-CFs to improve the mechanical properties of pure HA. A powder mixture containing nHA-CFs and granular nano-HA (gHA) was directly sintered by hot pressing at appropriate sintering pressure and temperature. A three-phase nHA-CFs/gHA composite was designed, fabricated, and used as an artificial bone. Results show that the bending strengths of the nHA-CFs/gHA composite are approximately 41.1% and 59.2% higher than those of CFs/gHA composite and pure HA, respectively. The possible reinforcing mechanism of nHA-CFs in the composite is also proposed at the end. When nHA-CFs are applied for preparation of nHA-CFs/gHA composites, the internal stress on its phase boundary with gHA matrix generated during cooling of sintered is significantly reduced due to the presence of the nHA coatings. It infers that nHA coatings on CFs might act as a bridge to control the forming of interfacial gaps between the gHA matrix and the CFs effectively. Our work provides additional insights into the feasibility of nHA-CFs/gHA composites as load-bearing implant materials in clinical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Experimental demonstration of a high-sensitivity humidity sensor based on an Agarose-coated transmission-type photonic crystal fiber interferometer.

    Science.gov (United States)

    Mathew, Jinesh; Semenova, Yuliya; Farrell, Gerald

    2013-06-01

    We present a detailed study of a high-sensitivity relative humidity (RH) sensor based on Agarose-coated transmission type photonic crystal fiber interferometer for what is the first time to our knowledge. The sensor shows a wavelength shift of approximately 56 nm for a humidity change of 58% RH. The repeatability of the coating layer formation and the evolution of the coating layers on passing the device though Agarose solution multiple times are studied in detail by observing the spectral shift resulting from the effect on the effective index of the cladding mode. Also, a detailed study is reported of the sensor performance in terms of its sensitivity, repeatability, and long-term stability. The sensor shows a linear response for an RH change in the range of 40%-80% RH with a humidity resolution of 0.017% RH and a higher humidity resolution of 0.007% RH in the range 80%-95% RH. The measurement accuracy of the sensor in the RH range 40%-80% is ±2% RH, and in the range 80%-95%, the accuracy is about ±1% RH. The response time of the sensor is 86 ms, when RH jumps from 50% to 90%. The temperature dependence of the sensor is found to be ~0.27 nm/°C, which is quite small compared to the RH sensitivity of the sensor.

  19. HP-SPME of volatile polycyclic aromatic hydrocarbons from water using multiwalled carbon nanotubes coated on a steel fiber through electrophoretic deposition

    Energy Technology Data Exchange (ETDEWEB)

    Maghsoudi, S.; Noroozian, E. [Shahid Bahonar Univ., Kerman (Iran, Islamic Republic of). Dept. of Chemistry

    2012-08-15

    A headspace solid-phase microextraction (SPME) method using a stainless steel wire electrophoretically coated with dodecylsulfate modified multiwalled carbon nanotubes was used for the gas chromatographic (GC) determination of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Electrophoretic deposition was easily carried out from an aqueous sodium dodecylsulfate medium. The effects of various parameters on the efficiency of SPME process, such as extraction time, extraction temperature, ionic strength, desorption time, and desorption temperature were studied. Under optimized conditions, the detection limits for the various PAHs studied varied from 0.03 to 0.07 ng mL{sup -1}. The inter-day and intra-day relative standard deviations at a 10 ng mL{sup -1} concentration level (n = 7) using a single-fiber were from 5.5 to 9.7 and 4.1 to 8.5 %, respectively. The fiber-to-fiber RSD% (n = 3) was between 7.3 and 11.1 %. The linear ranges were between 0.1 and 100 ng mL{sup -1}. The method was successfully applied to the analysis of a real sample with the recoveries from 88 to 105 % for 5 ng mL{sup -1} and 89 to 101 % for 0.5 ng mL{sup -1} samples. (orig.)

  20. Application of poly(dimethylsiloxane) fiber sol-gel coated onto NiTi alloy electrodeposited with zirconium oxide for the determination of organochlorine pesticides in herbal infusions.

    Science.gov (United States)

    Budziak, Dilma; Martendal, Edmar; Carasek, Eduardo

    2008-08-01

    A PDMS fiber sol-gel coated onto an NiTi alloy previously electrodeposited with zirconium oxide (named NiTi-ZrO(2)-PDMS) was applied to the determination of organochlorine pesticides (OCPs) in infusions of peppermint (Mentha piperita L.), lemon grass (Cymbopogon citratus Stapf), chamomile (Matricaria recutita L.), lemon balm (Melissa officinalis L.), and anise seeds (Pimpinella anisum L.). Salting-out effect, extraction time, and extraction temperature were optimized firstly by means of a full-factorial design and then using a Doehlert matrix. No salt addition and 50 min of extraction at 70 degrees C were the optimum conditions. Satisfactory LODs in the range of 2-17 ng/L, as well as good correlation coefficients (at least 0.9981) in the linear range studied, were obtained. Calibration was successfully applied using an infusion of M. recutita L. and recovery tests were performed to ensure the accuracy of the method, with values in the range of 77-120%. Comparison of the NiTi-ZrO(2)-PDMS with commercially available PDMS fibers showed that the proposed fiber has an extraction efficiency comparable to that of PDMS 30 microm for the compounds evaluated, demonstrating its potential applicability.

  1. Photolithography of thick photoresist coating in anisotropically etched V-grooves for electrically controlled liquid crystal photonic bandgap fiber devices

    DEFF Research Database (Denmark)

    Wei, Lei; Khomtchenko, Elena; Alkeskjold, Thomas Tanggaard

    2009-01-01

    Thick photoresist coating for electrode patterning in anisotropically etched v-grooves is investigated. The photoresist coverage is compared with and without soft baking. Two-step exposure is applied for a complete exposure and minimizing the resolution loss....

  2. Composite materials and bodies including silicon carbide and titanium diboride and methods of forming same

    Science.gov (United States)

    Lillo, Thomas M.; Chu, Henry S.; Harrison, William M.; Bailey, Derek

    2013-01-22

    Methods of forming composite materials include coating particles of titanium dioxide with a substance including boron (e.g., boron carbide) and a substance including carbon, and reacting the titanium dioxide with the substance including boron and the substance including carbon to form titanium diboride. The methods may be used to form ceramic composite bodies and materials, such as, for example, a ceramic composite body or material including silicon carbide and titanium diboride. Such bodies and materials may be used as armor bodies and armor materials. Such methods may include forming a green body and sintering the green body to a desirable final density. Green bodies formed in accordance with such methods may include particles comprising titanium dioxide and a coating at least partially covering exterior surfaces thereof, the coating comprising a substance including boron (e.g., boron carbide) and a substance including carbon.

  3. Non-Lubricated Diamond-Coated Bearings Reinforced by Carbon Fibers to Work in Lunar Dust Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop low cost diamond composite bearings utilizing our new high pressure technology for carbon fiber reinforced 3-D C/C composites and mixtures of...

  4. Silicon Carbide Electronic Devices

    Science.gov (United States)

    Neudeck, P. G.

    2001-01-01

    The status of emerging silicon carbide (SiC) widebandgap semiconductor electronics technology is briefly surveyed. SiC-based electronic devices and circuits are being developed for use in high-temperature, high-power, and/or high-radiation conditions under which conventional semiconductors cannot function. Projected performance benefits of SiC electronics are briefly illustrated for several applications. However, most of these operational benefits of SiC have yet to be realized in actual systems, primarily owing to the fact that the growth techniques of SiC crystals are relatively immature and device fabrication technologies are not yet sufficiently developed to the degree required for widespread, reliable commercial use. Key crystal growth and device fabrication issues that limit the performance and capability of high-temperature and/or high-power SiC electronics are identified. The electrical and material quality differences between emerging SiC and mature silicon electronics technology are highlighted.

  5. Molecularly imprinted polymer coated solid-phase microextraction fiber prepared by surface reversible addition-fragmentation chain transfer polymerization for monitoring of Sudan dyes in chilli tomato sauce and chilli pepper samples.

    Science.gov (United States)

    Hu, Xiaogang; Fan, Yanan; Zhang, Yi; Dai, Guimei; Cai, Quanling; Cao, Yujuan; Guo, Changjuan

    2012-06-20

    Surface reversible addition-fragmentation chain transfer (RAFT) polymerization method was firstly applied to the preparation of molecularly imprinted polymer (MIP) coated silicon solid-phase microextraction (SPME) fibers. With Sudan I as template, an ultra-thin MIP coating with about 0.55-μm thickness was obtained with homogeneous structure and controlled composition, due to the controllable radical growing and chain propagation in surface RAFT polymerization. The MIP-coated fibers were found with enhanced selectivity coefficients (3.0-6.5) to Sudan I-IV dyes in contrast with those reported in our previous work. Furthermore, the ultra-thin thickness of MIP coating was helpful to the effective elution of template and fast adsorption/desorption kinetics, so only about 18 min was needed for MIP-coated SPME operation. The detection limits of 21-55 ng L(-1) were achieved for four Sudan dyes, when MIP-coated SPME was coupled with liquid chromatography (LC) and mass spectrometry (MS) detection. The MIP-coated SPME-LC-MS/MS method was tested for the monitoring of ultra trace Sudan dyes in spiked chilli tomato sauce and chilli pepper samples, and high enrichment effect, remarkable matrix peaks-removing capability, and consequent high sensitivities were achieved to four Sudan dyes. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. An automated solid-phase microextraction method based on magnetic molecularly imprinted polymer as fiber coating for detection of trace estrogens in milk powder.

    Science.gov (United States)

    Lan, Hangzhen; Gan, Ning; Pan, Daodong; Hu, Futao; Li, Tianhua; Long, Nengbing; Qiao, Li

    2014-02-28

    A new automated solid-phase micro extraction (SPME) sampling method was developed for quantitative enrichment of estrogens (ES) from milk powder, using magnetic molecularly imprinted polymer (MMIP) as fiber coating. The method (MMIP-SPME) was built with several electromagnetic stainless steel fibers, placed in parallel for simultaneously extraction. The MMIP was synthesized using core-shell Fe3O4@SiO2 nanoparticles (NPs) as magnetic support. Estradiol (E2) was employed as the template molecule, acrylamide (AA) as functional monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. MMIP can be easily absorbed or desorbed from fibers when the current is turned on or off, creating magnetism. Compared to traditional MIP-SPME, the prepared procedure of MMIP-SPME is time-saving and organic solvent-free. The proposed device significantly improved the efficiency of separation and enrichment of estrogens from complex matrices thereby and facilitating the pretreatment steps by electromagnetically controlled extraction fibers to achieve full automation. Several experimental parameters were studied, including extraction and desorption kinetics, solution pH, desorption solution, ratio, and shuttle rate. The newly developed MMIP-SPME showed good sensitivity and high binding capacity, fast adsorption kinetics and desorption kinetics for estrone (E1), estradiol (E2), estriol (E3) and diethylstilbestrol (DES) under optimized conditions. The detection limits for the four estrogens were 1.5-5.5ngg(-1) with excellent reproducibility (RSD values less than 7.1%) when milk powder samples spiked with analytes at 20, 100 and 250ngg(-1) were studied. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Method Developed for Improving the Thermomechanical Properties of Silicon Carbide Matrix Composites

    Science.gov (United States)

    Bhatt, Ramakrishna T.; DiCarlo, James A.

    2004-01-01

    Today, a major thrust for achieving engine components with improved thermal capability is the development of fiber-reinforced silicon-carbide (SiC) matrix composites. These materials are not only lighter and capable of higher use temperatures than state-of-the-art metallic alloys and oxide matrix composites (approx. 1100 C), but they can provide significantly better static and dynamic toughness than unreinforced silicon-based monolithic ceramics. However, for successful application in advanced engine systems, the SiC matrix composites should be able to withstand component service stresses and temperatures for the desired component lifetime. Since the high-temperature structural life of ceramic materials is typically controlled by creep-induced flaw growth, a key composite property requirement is the ability to display high creep resistance under these conditions. Also, because of the possibility of severe thermal gradients in the components, the composites should provide maximum thermal conductivity to minimize the development of thermal stresses. State-of-the-art SiC matrix composites are typically fabricated via a three-step process: (1) fabrication of a component-shaped architectural preform reinforced by high-performance fibers, (2) chemical vapor infiltration of a fiber coating material such as boron nitride (BN) into the preform, and (3) infiltration of a SiC matrix into the remaining porous areas in the preform. Generally, the highest performing composites have matrices fabricated by the CVI process, which produces a SiC matrix typically more thermally stable and denser than matrices formed by other approaches. As such, the CVI SiC matrix is able to provide better environmental protection to the coated fibers, plus provide the composite with better resistance to crack propagation. Also, the denser CVI SiC matrix should provide optimal creep resistance and thermal conductivity to the composite. However, for adequate preform infiltration, the CVI SiC matrix

  8. Fabrication of ciprofloxacin molecular imprinted polymer coating on a stainless steel wire as a selective solid-phase microextraction fiber for sensitive determination of fluoroquinolones in biological fluids and tablet formulation using HPLC-UV detection.

    Science.gov (United States)

    Mirzajani, Roya; Kardani, Fatemeh

    2016-04-15

    A molecularly imprinted polymer (MIP) fiber on stainless steel wire using ciprofloxacin template with a mild template removal condition was synthetized and evaluated for fiber solid phase microextraction (SPME) of fluoroquinolones (FQs) from biological fluids and pharmaceutical samples, followed by high performance liquid chromatography analysis with UV detection (HPLC-UV). The developed MIP fiber exhibited high selectivity for the analytes in complex matrices. The coating of the fibers were inspected using fourier transform infrared spectrophotometry, thermogaravimetric analysis, energy dispersive X-ray (EDX) spectroscopy as well as by scanning electron microscopy (SEM). The fiber shows high thermal stability (up to 300°C), good reproducibility and long lifetime. The composite coating did not swell in organic solvents nor did it strip off from the substrate. It was also highly stable and extremely adherent to the surface of the stainless steel fiber. The fabricated fiber exclusively exhibited excellent extraction efficiency and selectivity for some FQs. The effective parameters influencing the microextraction efficiency such as pH, extraction time, desorption condition, and stirring rate were investigated. Under optimized conditions, the limits of detection of the four FQs ranged from 0.023-0.033 μg L(-1) (S/N=5) and the calibration graphs were linear in the concentration range from 0.1-40 μg L(-1), the inter-day and intraday relative standard deviations (RSD) for various FQs at three different concentration level (n=5) using a single fiber were 1.1-4.4% and the fiber to fiber RSD% (n=5) was 4.3-6.7% at 5 μg L(-1) of each anlyetes. The method was successfully applied for quantification of FQs in real samples including serum, plasma and tablet formulation with the recoveries between 97 to 102%. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Graphene Nanoplatelet Reinforced Tantalum Carbide

    Science.gov (United States)

    2015-08-27

    et. al. Ultrahigh-pressure consolidation and deformation of tantalum carbide at ambient and high temperatures. Acta Materialia 61-11 (2013) 4001-4009...matrix to reinfor- cement . Al–5BNNT exhibits high deformability as it undergoes 75% thickness reduction in a single pass of cold rolling without...4009Ultrahigh-pressure consolidation and deformation of tantalum carbide at ambient and high temperatures Debrupa Lahiri a, Virendra Singh b, Giovani

  10. Characterization of electrogenerated polypyrrole-benzophenone films coated on poly(pyrrole-methyl metacrylate) optic-conductive fibers.

    Science.gov (United States)

    Abu-Rabeah, Khalil; Atias, Danit; Herrmann, Sebastien; Frenkel, Julia; Tavor, Dorith; Cosnier, Serge; Marks, Robert S

    2009-09-01

    A conductive surface was created for the development of a biosensing platform via chemical polymerization of pyrrole onto the surface of poly(methyl methacrylate) (PMMA) fibers, with a subsequent electrogeneration of a photoactive linker pyrrole-benzophenone (PyBz) monomer on the fiber surface. Irradiation of the benzophenone groups embedded in the polypyrrole (Ppy) films by UV (350 nm) formed active radicals, allowing covalent attachment of the desired biomaterials. Characterization and optimization of this platform were carried out, with the platform showing conductive, stable, thin, controllable, and light-transmissible film features. Various parameters such as time deposition, process temperature, and activator plus pyrrole monomer concentrations were examined in the study. The morphology and permeability of the optic-fiber PMMA fibers were investigated to examine mass transfer ability. Cyclic voltammetry and amperometry techniques were applied to characterize the electrical features of the surface and charge transfer. The platform potential was then demonstrated by the construction of both amperometric and optical biosensors.

  11. Photocatalytic Treatment of Desalination Concentrate Using Optical Fibers Coated With Nanostructured Thin Films: Impact of Water Chemistry and Seasonal Climate Variations.

    Science.gov (United States)

    Lin, Lu; Wang, Huiyao; Luo, Hongmei; Xu, Pei

    2016-05-01

    Treatment of desalination concentrate can reduce concentrate volume for disposal, increase water recovery and convert waste to resource. However, concentrate treatment is costly and energy intensive due to high concentrations of salt and recalcitrant organic matter in concentrate. Photocatalytic oxidation provides a novel energy neutral technology for concentrate treatment by degrading organic contaminants. Polymer-assisted hydrothermal deposition method was used to synthesize innovative pure and Fe-doped TiO2 mixed-phase nanocomposite thin films on side-glowing optical fibers (SOFs). The properties of the photocatalysts-coated SOF were characterized by surface morphology, nanostructure, crystallite size and phase and zeta potential. Photodegradation efficiency and durability of the photocatalysts treating different types of desalination concentrate was studied under natural sunlight. Synthetic solutions and reverse osmosis (RO) concentrates from brackish water and municipal wastewater desalination facilities were tested to elucidate the impact of water chemistry, operating conditions and seasonal climate variations (solar irradiation intensity and temperature) on photocatalytic efficiency. High ionic strength and divalent electrolyte ions in RO concentrate accelerated photocatalytic process, whereas the presence of carbonate species and organic matter hindered photodegradation. Outdoor testing of immobilized continuous-flow photoreactors suggested that the catalyst-coated SOFs can utilize a wide spectrum of natural sunlight and achieved durable photocatalytic performance. © 2016 The American Society of Photobiology.

  12. Photocatalytic degradation of glyphosate in water by N-doped SnO2/TiO2 thin-film-coated glass fibers.

    Science.gov (United States)

    Kongsong, Peerawas; Sikong, Lek; Niyomwas, Sutham; Rachpech, Vishnu

    2014-01-01

    Photocatalytic degradation of glyphosate contaminated in water was investigated. The N-doped SnO2/TiO2 films were prepared via sol-gel method, and coated on glass fibers by dipping method. The effects of nitrogen doping on coating morphology, physical properties and glyphosate degradation rates were experimentally determined. Main variable was the concentration of nitrogen doping in range 0-40 mol%. Nitrogen doping results in shifting the absorption wavelengths and narrowing the band gap energy those lead to enhancement of photocatalytic performance. The near optimal 20N/SnO2/TiO2 composite thin film exhibited about two- and four-folds of glyphosate degradation rates compared to the undoped SnO2/TiO2 and TiO2 films when photocatalytic treatment were performed under UV and solar irradiations, respectively, due to its narrowest band gap energy (optical absorption wavelength shifting to visible light region) and smallest crystallite size influenced by N-doping. © 2014 The American Society of Photobiology.

  13. Investigation of antifouling and disinfection potential of chitosan coated iron oxide-PAN hollow fiber membrane using Gram-positive and Gram-negative bacteria.

    Science.gov (United States)

    Mukherjee, Munmun; De, Sirshendu

    2017-06-01

    Chitosan coated iron oxide nanoparticles were impregnated into polyacrylonitrile based hollow fiber membrane. The molecular weight cut off was varied in the range of 120 to 145kDa with the concentration of nanoparticles. Incorporation of nanoparticles improved the permeability, mechanical property and hydrophilicity of the membrane. The contact angle of the membrane decreased from 80° to 51° and the permeability increased by 31% at 0.5wt% nanoparticles concentration. The antibacterial and antifouling property of the membrane were investigated with two biofilm causing Gram positive and Gram negative bacteria. The damage of cell membrane was directly confirmed by release of cellular constituent absorbing in 260nm. The cellular deformation on the membrane surface was evident by direct microscopic observation in FESEM. This damage was likely caused by electrostatic interaction between NH3+ group of nanoparticles and anionic components of phosphoryl group of bacteria. The hollow fiber membrane shows promising antibiofouling property even after long experimental run as evident by 95% flux recovery ratio. The effect of operating conditions on rejection and flux profile was investigated during long experimental run. The result indicated that there was no detectable iron in the permeate sample that could impose adverse health hazard. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Silicon Carbide Growth

    Science.gov (United States)

    2005-01-01

    Andrew Trunek has focused on supporting the Sic team through the growth of Sic crystals, making observations and conducting research that meets the collective needs and requirements of the team while fulfilling program commitments. Cancellation of the Ultra Efficient Engine Technology (UEET) program has had a significant negative impact on resources and research goals. This report highlights advancements and achievements made with this cooperative agreement over the past year. NASA Glenn Research Center (GRC) continues to make advances in silicon carbide (SiC) research during the past year. Step free surfaces were used as substrates for the deposition of GaN epilayers that yielded very low dislocation densities. Defect free 3C- SiC was successfully nucleated on step free mesas and test diodes were fabricated. Web growth techniques were used to increase the usable surface area of dislocation free SiC by approximately equal to 40%. The greatest advancement has been attained on stepped surfaces of SiC. A metrology standard was developed using high temperature etching techniques titled "Nanometer Step Height Standard". This development culminated in being recognized for a 2004 R&D100 award and the process to produce the steps received a NASA Space Act award.

  15. Microstructure of WC/C coatings deposited on steel substrates

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Carvalho, N.J.M.; Brebbia, CA

    2001-01-01

    Electron microscopy, including scanning (SEM), transmission (TEM) and high-resolution (HRTEM) were employed to characterise slightly different tungsten carbide/carbon coatings deposited onto steel substrates. Complementary techniques, such as X-ray diffraction (XRD), Auger electron spectroscopy

  16. Conformal coating of Ni(OH)2 nanoflakes on carbon fibers by chemical bath deposition for efficient supercapacitor electrodes

    KAUST Repository

    Alhebshi, Nuha

    2013-01-01

    A novel supercapacitor electrode structure has been developed in which a uniform and conformal coating of nanostructured Ni(OH)2 flakes on carbon microfibers is deposited in situ by a simple chemical bath deposition process at room temperature. The microfibers conformally coated with Ni(OH) 2 nanoflakes exhibit five times higher specific capacitance compared to planar (non-conformal) Ni(OH)2 nanoflake electrodes prepared by drop casting of Ni(OH)2 powder on the carbon microfibers (1416 F g-1vs. 275 F g-1). This improvement in supercapacitor performance can be ascribed to the preservation of the three-dimensional structure of the current collector, which is a fibrous carbon fabric, even after the conformal coating of Ni(OH)2 nanoflakes. The 3-D network morphology of the fibrous carbon fabric leads to more efficient electrolyte penetration into the conformal electrode, allowing the ions to have greater access to active reaction sites. Cyclic stability testing of the conformal and planar Ni(OH)2 nanoflake electrodes, respectively, reveals 34% and 62% drop in specific capacitance after 10 000 cycles. The present study demonstrates the crucial effect that electrolyte penetration plays in determining the pseudocapacitive properties of the supercapacitor electrodes. © 2013 The Royal Society of Chemistry.

  17. Ultra-Weak Fiber Bragg Grating Sensing Network Coated with Sensitive Material for Multi-Parameter Measurements

    Directory of Open Access Journals (Sweden)

    Wei Bai

    2017-06-01

    Full Text Available A multi-parameter measurement system based on ultra-weak fiber Bragg grating (UFBG array with sensitive material was proposed and experimentally demonstrated. The UFBG array interrogation principle is time division multiplex technology with two semiconductor optical amplifiers as timing units. Experimental results showed that the performance of the proposed UFBG system is almost equal to that of traditional FBG, while the UFBG array system has obvious superiority with potential multiplexing ability for multi-point and multi-parameter measurement. The system experimented on a 144 UFBG array with the reflectivity of UFBG ~0.04% for the four target parameters: hydrogen, humidity, temperature and salinity. Moreover, a uniform solution was customized to divide the cross-sensitivity between temperature and other target parameters. It is expected that this scheme will be capable of handling thousands of multi-parameter sensors in a single fiber.

  18. Experimental and theoretical studies on localized surface plasmon resonance based fiber optic sensor using graphene oxide coated silver nanoparticles

    Science.gov (United States)

    Nayak, Jeeban Kumar; Parhi, Purnendu; Jha, Rajan

    2016-07-01

    An optical fiber based refractive index sensor using graphene oxide (GO) encapsulated silver nanoparticles (AgNPs) is reported. The AgNPs are encapsulated with a very thin layer of GO as it controls the inter-particle distance thereby preventing aggregation. The encapsulation also enhances the colloidal stability and prevents the oxidation of the AgNPs by separating them from direct contact with the aqueous medium. High-resolution transmission electron microscopy results support the formation of 1 nm thick GO around AgNPs of an average size of 35 nm. A Raman spectrometer and a UV-VIS spectrometer have been used to characterize and study the synthesized nanoparticles along with GO. Further, Raman spectra support a 64.72% increase in D-peak intensity and a 52.91% increase in G-peak intensity of the GO-encapsulated AgNPs (GOE-AgNPs) with respect to GO. Further, the GOE-AgNPs are immobilized on the core of functionalized plastic-cladded silica fiber. FESEM confirms the immobilization of the GOE-AgNPs on the fiber core. We observed that the peak absorbance changes by 87.55% with a 0.05 change in the refractive index. The sensitivity of the proposed fiber sensor is found to be 0.9406 ΔA/RIU along with a resolution of 12.8  ×  {{10}-4} RIU. MATLAB is used to calculate the absorbance of the AgNPs by considering the bound and free electron contribution along with the size-dependent dispersion of the nanoparticles. We found that the simulation results are in good agreement with the experimental results.

  19. Functionalization and cellular uptake of boron carbide nanoparticles

    DEFF Research Database (Denmark)

    Mortensen, M. W.; Björkdahl, O.; Sørensen, P. G.

    2006-01-01

    In this paper we present surface modification strategies of boron carbide nanoparticles, which allow for bioconjugation of the transacting transcriptional activator (TAT) peptide and fluorescent dyes. Coated nanoparticles can be translocated into murine EL4 thymoma cells and B16 F10 malignant...... melanoma cells in amounts as high as 0.3 wt. % and 1 wt. %, respectively. Neutron irradiation of a test system consisting of untreated B16 cells mixed with B16 cells loaded with boron carbide nanoparticles were found to inhibit the proliferative capacity of untreated cells, showing that cells loaded...... with boron-containing nanoparticles can hinder the growth of neighboring cells upon neutron irradiation. This could provide the first step toward a T cell-guided boron neutron capture therapy....

  20. Friction and wear of radiofrequency-sputtered borides, silicides, and carbides

    Science.gov (United States)

    Brainard, W. A.; Wheeler, D. R.

    1978-01-01

    The friction and wear properties of several refractory compound coatings were examined. These compounds were applied to 440 C bearing steel surfaces by radiofrequency (RF) sputtering. The refractory compounds were the titanium and molybdenum borides, the titanium and molybdenum silicides, and the titanium, molybdenum, and boron carbides. Friction testing was done with a pin-on-disk wear apparatus at loads from 0.1 to 5.0 newtons. Generally, the best wear properties were obtained when the coatings were bias sputtered onto 440 C disks that had been preoxidized. Adherence was improved because of the better bonding of the coatings to the iron oxide formed during preoxidation. As a class the carbides provided wear protection to the highest loads. Titanium boride coatings provided low friction and good wear properties to moderate loads.

  1. Characteristics of hot-pressed fiber-reinforced ceramics with SiC matrix

    Science.gov (United States)

    Miyoshi, Tadahiko; Kodama, Hironori; Sakamoto, Hiroshi; Goto, Akihiro; Iijima, Shiroo

    1989-11-01

    Silicon carbide ceramics’ matrix composites with SiC or C filaments were fabricated through hot pressing, and the effects of the filament pullout on their fracture toughness were experimentally investigated. The C-rich coating layers on the SiC filaments were found to have a significant effect on the frictional stress at the filament/matrix interfaces, through assising the filamet pullout from the matrix. Although the coating layers were apt to burn out in the sintering process of SiC matrix compposites, a small addition of carbon to the raw materials was found to be effective for the retention of the layers on the fibers, thus increasing the fracture toughness of the composites. The fracture toughness of the C filament/SiC matrix composite increased with temperature due to the larger interfacial frictional stress at higher temperatures, because of the higher thermal expansion of the filament in the radial direction than that of the matrix.

  2. Scalable Quantum Photonics with Single Color Centers in Silicon Carbide.

    Science.gov (United States)

    Radulaski, Marina; Widmann, Matthias; Niethammer, Matthias; Zhang, Jingyuan Linda; Lee, Sang-Yun; Rendler, Torsten; Lagoudakis, Konstantinos G; Son, Nguyen Tien; Janzén, Erik; Ohshima, Takeshi; Wrachtrup, Jörg; Vučković, Jelena

    2017-03-08

    Silicon carbide is a promising platform for single photon sources, quantum bits (qubits), and nanoscale sensors based on individual color centers. Toward this goal, we develop a scalable array of nanopillars incorporating single silicon vacancy centers in 4H-SiC, readily available for efficient interfacing with free-space objective and lensed-fibers. A commercially obtained substrate is irradiated with 2 MeV electron beams to create vacancies. Subsequent lithographic process forms 800 nm tall nanopillars with 400-1400 nm diameters. We obtain high collection efficiency of up to 22 kcounts/s optical saturation rates from a single silicon vacancy center while preserving the single photon emission and the optically induced electron-spin polarization properties. Our study demonstrates silicon carbide as a readily available platform for scalable quantum photonics architecture relying on single photon sources and qubits.

  3. Scalable Quantum Photonics with Single Color Centers in Silicon Carbide

    Science.gov (United States)

    Radulaski, Marina; Widmann, Matthias; Niethammer, Matthias; Zhang, Jingyuan Linda; Lee, Sang-Yun; Rendler, Torsten; Lagoudakis, Konstantinos G.; Son, Nguyen Tien; Janzén, Erik; Ohshima, Takeshi; Wrachtrup, Jörg; Vučković, Jelena

    2017-03-01

    Silicon carbide is a promising platform for single photon sources, quantum bits (qubits) and nanoscale sensors based on individual color centers. Towards this goal, we develop a scalable array of nanopillars incorporating single silicon vacancy centers in 4H-SiC, readily available for efficient interfacing with free-space objective and lensed-fibers. A commercially obtained substrate is irradiated with 2 MeV electron beams to create vacancies. Subsequent lithographic process forms 800 nm tall nanopillars with 400-1,400 nm diameters. We obtain high collection efficiency, up to 22 kcounts/s optical saturation rates from a single silicon vacancy center, while preserving the single photon emission and the optically induced electron-spin polarization properties. Our study demonstrates silicon carbide as a readily available platform for scalable quantum photonics architecture relying on single photon sources and qubits.

  4. A molybdenum disulfide/reduced graphene oxide fiber coating coupled with gas chromatography-mass spectrometry for the saponification-headspace solid-phase microextraction of polychlorinated biphenyls in food.

    Science.gov (United States)

    Lv, Fangying; Gan, Ning; Cao, Yuting; Zhou, You; Zuo, Rongjie; Dong, Youren

    2017-11-24

    In this work, the molybdenum disulfide/reduced graphene oxide (MoS2/RGO) composite material was synthesized as a fiber coating to extract seven indicator polychlorinated biphenyls (PCBs; PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, and PCB180) present in food via a saponification-headspace solid-phase microextraction assay (saponification-HS-SPME). The MoS2/RGO coating was prepared and deposited on a stainless steel wire with the help of a silicone sealant and used as an SPME fiber. The alkali solution dissolved the fat and helped in releasing the PCBs present in milk to the headspace for extraction under 100°C. Following desorption in the inlet, the targets were quantified by gas chromatography-mass spectrometry. The effects of sorbent dosage, extraction time, added salts, and stirring rate on the extraction efficiency were investigated. The new coating was able to adsorb a higher amount of analytes, which was about 1.1-2.9 times in comparison with the commercially available SPME fiber (coated with divinylbenzene/carboxen/polydimethylsiloxane). It also showed the highest adsorption capability toward PCBs, which was 1.5-2.7 times that of the prepared RGO modified fiber. Moreover, MoS2 also showed a strong affinity toward PCBs in a manner similar to its affinity for graphene. The developed method is simple and environmentally friendly as it does not require any organic solvents. Furthermore, it exhibits good sensitivity with detection limits less than 0.1ngmL-1, linearity (0.25-100ngmL-1), and reproducibility (relative standard deviation below 10% for n=3). The novel SPME fibers are inexpensive, reusable, and can be easily prepared and manipulated. In addition, the saponification-HS-SPME assay was also found to be suitable for screening persistent organic pollutants in dairy products. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. INCREASING THE EFFICIENCY OF THE ALLOYED LAYER FORMATION WHEN HARDENING TUNGSTEN CARBIDE WITH COMBINED METHODS

    Directory of Open Access Journals (Sweden)

    Mr. Anatoly D. Verkhoturov

    2016-12-01

    Full Text Available This article describes the research aimed at improving the tungsten carbide durability with the help of spark alloying methods, arc welding and laser processing. The paper presents the formation of the alloyed layer thickness of more than 1400 mm with gradient transition properties. The parameters of the islet coating formation for durability improvement by laser processing are represented.

  6. Parameters optimization, microstructure and micro-hardness of silicon carbide laser deposited on titanium alloy

    CSIR Research Space (South Africa)

    Adebiyia, DI

    2016-06-01

    Full Text Available Silicon carbide (SiC), has excellent mechanical properties such as high hardness and good wear resistance, and would have been a suitable laser-coating material for titanium alloy to enhance the poor surface hardness of the alloy. However, SiC has...

  7. Silicon carbide as platform for energy applications

    DEFF Research Database (Denmark)

    Syväjärvi, Mikael; Jokubavicius, Valdas; Sun, Jianwu

    Silicon carbide is emerging as a novel material for a range of energy and environmental technologies. Previously, silicon carbide was considered as a material mainly for transistor applications. We have initiated the use of silicon carbide material towards optoelectronics in general lighting and ...

  8. New method for synthesis of metal carbides, nitrides and carbonitrides

    Energy Technology Data Exchange (ETDEWEB)

    Koc, R.; Folmer, J.S.; Kodambaka, S.K. [Southern Illinois Univ., Carbondale, IL (United States)] [and others

    1997-04-01

    The purpose of this work is to develop a novel synthesis method using a carbothermic reduction reaction of carbon coated precursors for producing high purity, submicron, non-agglomerated powders of metal carbide, metal nitride and metal boride systems. The authors also want to demonstrate the advantages of the process and provide information on the applicability of the process for synthesizing related advanced ceramic powders (e.g. SiC, WC, TiN, TiB{sub 2}, Si{sub 3}N{sub 4}). During the FY96 of the project, steps are taken to investigate the reaction mechanisms and phase evolution during the formation of TiC from carbon coated titania precursors and to produce submicron TiC powders with desired stoichiometries. Depending on the carbon content in the coated titania precursor, TiC powder was produced with different stoichiometries (different amount of oxygen and free carbon).

  9. Radiation response of SiC-based fibers

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States); Kohyama, Akira [Inst. of Advanced Energy, Kyoto (Japan); Snead, L.L. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    The radiation response of a base-line carbide composite (SiC/SiC) made with Nicalon{trademark} CG fiber reinforcement was presented for a broad range of dose and irradiation temperatures. Strength loss in this composite and a similar composite made with Tyranno{trademark} fiber was related to shrinkage and a predicted mass loss in the Nicalon CG or Tyranno fibers. In Table 1, measured relative density and length changes ({Delta}p/p{sub o} and {Delta}L/L{sub o}, respectively) for coated and uncoated fibers irradiated at high doses and temperatures (43 dpa-SiC at 1000 C and 80 dpa-SiC at 800 C) are given. Also given are the relative mass loss changes {Delta}m/m{sub o}, calculated from {Delta}p/p{sub o} and {Delta}L/L{sub o} by the expression {Delta}m/m{sub o} = 3 {Delta}L/L{sub o} + {Delta}p/p{sub o}.

  10. A novel graphene nanosheets coated stainless steel fiber for microwave assisted headspace solid phase microextraction of organochlorine pesticides in aqueous samples followed by gas chromatography with electron capture detection.

    Science.gov (United States)

    Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

    2011-09-28

    In this study, a novel graphene nanosheets (GNSs) coated solid phase microextraction (SPME) fiber was prepared by immobilizing microwave synthesized GNSs on a stainless steel wire. Microwave synthesized GNSs were verified by X-ray diffraction, field emission-scanning electron microscopy (FE-SEM) and transmission electron microscope (TEM). GNS-SPME fiber was characterized using FE-SEM and the results showed the GNS coating was homogeneous, porous, and highly adherent to the surface of the stainless steel fiber. The performance and feasibility of the GNS-SPME fiber was evaluated under one-step microwave assisted (MA) headspace (HS) SPME followed by gas chromatography with electron capture detection for five organochlorine pesticides (OCPs) in aqueous samples. Parameters influencing the extraction efficiency of MA-HS-GNS-SPME such as microwave irradiation power and time, pH, ionic strength, and desorption conditions were thoroughly examined. Under the optimized conditions, detection limits for the OCPs varied between 0.16 and 0.93 ng L(-1) and linear ranges varied between 1 and 1500 n gL(-1), with correlation coefficients ranging from 0.9984 to 0.9998, and RSDs in the range of 3.6-15.8% (n=5). In comparison with the commercial 100 μm polydimethylsiloxane fiber, the GNS coated fiber showed better extraction efficiency, higher mechanical and thermal stability (up to 290°C), longer life span (over 250 times), and lower production cost. The method was successfully applied to the analysis of real water samples with recoveries ranged between 80.1 and 101.1% for river water samples. The results demonstrated that the developed MA-HS-GNS-SPME method was a simple, rapid, efficient pretreatment and environmentally friendly procedure for the analysis of OCPs in aqueous samples. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Method to produce catalytically active nanocomposite coatings

    Science.gov (United States)

    Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

    2016-02-09

    A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

  12. Method to produce catalytically active nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

    2017-12-19

    A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

  13. Fabrication and Characterization of Multi-Walled Carbon Nanotube (MWCNT) and Ni-Coated Multi-Walled Carbon Nanotube (Ni-MWCNT) Repair Patches for Carbon Fiber Reinforced Composite Systems

    Science.gov (United States)

    Johnson, Brienne; Caraccio, Anne; Tate, LaNetra; Jackson, Dionne

    2011-01-01

    Multi-walled carbon nanotube (MWCNT)/epoxy and nickel-coated multi-walled carbon nanotube (Ni-MWCNT)/epoxy systems were fabricated into carbon fiber composite repair patches via vacuum resin infusion. Two 4 ply patches were manufactured with fiber orientations of [90/ 90/ 4590] and [0/90/ +45/ -45]. Prior to resin infusion, the MWCNT/Epoxy system and NiMWCNT/ epoxy systems were optimized for dispersion quality. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to determine the presence ofcarbon nanotubes and assess dispersion quality. Decomposition temperatures were determined via thermogravametric analysis (TGA). SEM and TGA were also used to evaluate the composite repair patches.

  14. Hollow mesoporous carbon spheres-based fiber coating for solid-phase microextraction of polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Hu, Xingru; Liu, Chao; Li, Jiansheng; Luo, Rui; Jiang, Hui; Sun, Xiuyun; Shen, Jinyou; Han, Weiqing; Wang, Lianjun

    2017-10-20

    In this study, a novel hollow mesoporous carbon spheres-based fiber (HMCSs-F) was fabricated to immobilize HMCSs onto a stainless steel wire for solid-phase microextraction (SPME). Characterization results showed that the HMCSs-F possessed a large specific surface area, high porosity and uniform pore size. To demonstrate the extraction performance, a series of polycyclic aromatic hydrocarbons (PAHs) was chosen as target analytes. The experimental parameters including extraction and desorption conditions were optimized. Compared to commercial fibers, the HMCSs-F exhibited better extraction efficiency for PAHs. More interestingly, a good extraction selectivity for PAHs from the complex matrix was observed in these HMCSs-F. The enhanced SPME performance was attributed to the unique pore structure and special surface properties of the HMCSs. Furthermore, under the optimum conditions, the limits of detection (LODs) for the HMCSs-F were in the range of 0.20-1.15ngL-1 with a corresponding relative standard deviation that was below 8.6%. The method was successfully applied for the analysis of PAHs in actual environmental water samples with recoveries ranging from 85.9% to 112.2%. These results imply that the novel HMCSs-F have potential application in environmental water analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Preparation and characterization of porous calcium titanate-based coated glass fiber filter material and its application in determination of lead and cadmium ion concentrations in water.

    Science.gov (United States)

    Zhang, Dong; Yu, Ping; He, Xiang

    2011-01-01

    Glass fiber filter coated with a porous block adsorption agent of calcium titanate (GPCTO) was prepared by the citric acid sol-gel method, and characterized by X-ray diffraction, scanning electron microscopy, and FTIR spectrophotometry. Its Pb2+ and Cd2+ adsorption properties from water were studied. Adsorption and elution were investigated under different conditions, as were the thermodynamics and kinetics of adsorption, using Cd ion as representative. Calcium titanate may react with glass fiber, forming Si-O-Ti and B-O-Ti bonds and becoming a composite adsorbent. The Pb and Cd ions were quantitatively retained at pH 4-9; their adsorption capacities by the GPCTO were 199.72 and 19.68 mg/g, respectively. The isothermal data were described by the Langmuir equation. The dynamic data followed the pseudo-second-order kinetic model well. The enthalpy change (AH) of the adsorption process was 37.160 kJ/mol. At various temperatures, Gibbs free energy changes (delta G) were negative, and entropy changes (delta S) were positive. The activation energy (Ea) was 38.127 kJ/mol for the adsorption. Cd ion adsorption by the GPCTO was endothermic and spontaneous. The adsorbed Pb and Cd ions were completely recovered by elution with 2 M HNO3. The Pb+ and Cd2+ concentration factors were up to 200. The method has been applied to the preconcentration for flame atomic absorption spectrometric determinations of trace Pb and Cd ions in water samples. The recoveries were 95.2 to 102.4% for Pb and 92.2 to 98.0% for Cd.

  16. Effect of Mo ion-implantation on the adhesion of diamond coatings

    CERN Document Server

    Yang Shie; Wang Xiao Ping; Li Hui; Ma Bing Xian; Qin Guang Yong; Zhang Bing Lin

    2002-01-01

    Diamond coatings were deposited on the cobalt-cemented tungsten carbide (YG6) substrates, which have been implanted with Mo ions, by microwave plasma CVD (MPCVD) method. The effect of ion-implantation on the adhesion of diamond coatings was studied. The results showed that the chemical compositions of cemented carbide substrate surfaces change obviously after Mo ion-implantation; and the adhesion strength between the CVD diamond coatings and the substrates implanted with Mo ions in proper concentration is improved remarkably

  17. Solid polymer substrates and coated fibers containing 2,4,6-trinitrobenzene motifs as smart labels for the visual detection of biogenic amine vapors.

    Science.gov (United States)

    Pablos, Jesús L; Vallejos, Saúl; Muñoz, Asunción; Rojo, María J; Serna, Felipe; García, Félix C; García, José M

    2015-06-08

    Attempts to polymerize trinitrobenzene derivatives (TNB) have been fruitless so far. Accordingly, polymers containing TNB have not been exploited in spite of their envisaged potential applications. Here, we describe two ways for preparing polymers with TNB moieties thus overcoming the previously reported polymerization impairments. We also report on the exploitation of the materials, both obtained as tractable transparent films and coated fibers, as smart labels for the visual detection of amine vapors. More precisely, amines in the atmosphere surrounding the sensory materials diffuse into them reacting with the TNB motifs forming highly colored Meisenheimer complexes, giving rise to development of color and to the naked eye sensing phenomenon. This is the case of highly volatile amines, such as trimethylamine, produced in food spoilage, specifically in the deterioration of fish or meat, for which the color development of the smart labels can be used as a visual test for food freshness. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Graphene-coated hollow fiber membrane as the cathode in anaerobic electrochemical membrane bioreactors – Effect of configuration and applied voltage on performance and membrane fouling

    KAUST Repository

    Werner, Craig M.

    2015-12-22

    Electrically conductive, graphene-coated hollow-fiber porous membranes were used as cathodes in anaerobic electrochemical membrane bioreactors (AnEMBRs) operated at different applied voltages (0.7 V and 0.9 V) using a new rectangular reactor configuration, compared to a previous tubular design (0.7 V). The onset of biofouling was delayed and minimized in rectangular reactors operated at 0.9 V, compared to those at 0.7 V due to higher rates of hydrogen production. Maximum transmembrane pressures for the rectangular reactor were only 0.10 bar (0.7 V) or 0.05 bar (0.9 V) after 56 days of operation, compared to 0.46 bar (0.7 V) for the tubular reactor after 52 days. The thickness of the membrane biofouling layer was approximately 0.4 µm for rectangular reactors and 4 µm for the tubular reactor. Higher permeate quality (TSS = 0.05 mg/L) was achieved in the rectangular AnEMBR than the tubular AnEMBR (TSS = 17 mg/L), likely due to higher current densities that minimized the accumulation of cells in suspension. These results show that the new rectangular reactor design, which had increased rates of hydrogen production, successfully delayed the onset of cathode biofouling and improved reactor performance.

  19. ZnO coated Fabry-Perot interferometric optical fiber for detection of gasoline blend vapors: Refractive index and fringe visibility manipulation studies

    Science.gov (United States)

    Pawar, Dnyandeo; Kitture, Rohini; Kale, S. N.

    2017-03-01

    ZnO nanoparticles-coated Fabry-Perot interferometer based optical fiber sensor is demonstrated to detect different gasoline blend concentrations in ethanol. Different gasoline blends (with ethanol varying from 0% (E0) to 100% (E100)) have been subjected to the sensor to observe the change in refractive index of the material that leads to the wavelength shift and fringe visibility change of the interference spectrum. The sensor shows the remarkable response with different gasoline blend mixtures within the time span of 0-60 s in terms of wavelength and Intensity (power) shift. The maximum wavelength shift of 12.1 nm is observed for E0 mixture and least of 3 nm for E100 in 60 s, respectively. A fast response time and recovery time of 5 s and 9 s, respectively, are obtained for E0 mixture. The results are related to the formation of interference pattern due the ZnO-mediated-Fabry-Perot cavity, changes in refractive index with the change in external gaseous environment, changes in fringe visibility of the spectrum and the interaction of oxygen vacancies on ZnO surface with the gasoline moieties. The rates of sensing and recovery times are related to the Reid vapor pressures of ethanol and gasoline. Hence a dual scale of sensing, both in terms of wavelength shift (refractive index) and intensity shift (fringe visibility) has been proposed for gasoline blend sensing.

  20. Barley husk carbon as the fiber coating for the solid-phase microextraction of twelve pesticides in vegetables prior to gas chromatography-mass spectrometric detection.

    Science.gov (United States)

    Liang, Weiqian; Wang, Juntao; Zang, Xiaohuan; Dong, Wenhuan; Wang, Chun; Wang, Zhi

    2017-03-31

    In this work, a barley husk biomaterial was successfully carbonized by hydrothermal method. The carbon had a high specific surface area and good stability. It was coated onto a stainless steel wire through sol-gel technique to prepare a solid-phase microextraction fiber for the extraction of trace levels of twelve pesticides (tsumacide, fenobucarb, indoxacarb, diethofencarb, thimet, terbufos, malathion, thiamethoxam, imidacloprid, buprofezin, acetamiprid, thiamethoxam) from vegetable samples prior to gas chromatography-mass spectrometric (GC-MS) detection. The main experimental parameters that could influence the extraction efficiency such as extraction time, extraction temperature, sample pH, sample salinity, stirring rate, desorption temperature and desorption time, were investigated. Under the optimized conditions, the linearity was observed in the range of 0.2-75.0μgkg(-1) for tomato samples, and 0.3-60.0μgkg(-1) for cucumber samples, with the correlation coefficients (r) ranging from 0.9959 to 0.9983. The limits of detection of the method were 0.01-0.05μgkg(-1) for tomato samples, and 0.03-0.10μgkg(-1) for cucumber samples. The recoveries of the analytes for the method from spiked samples were in the range of 76%-104%, and the precision, expressed as the relative standard deviations, was less than 12%. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Fiber optic surface plasmon resonance based hexachlorobenzene sensor exploiting layer-by-layer coatings of GNP/SnO2 dendrites nanocomposite

    Science.gov (United States)

    Sharma, Sonika; Gupta, Banshi D.

    2017-11-01

    An efficient fiber optic surface plasmon resonance based hexachlorobenzene (HCB) sensor is designed using layer by layer coating method. SnO2 nanoparticle [(SnO2)N] and SnO2 dendrites [(SnO2)D] are used to synthesize graphene nanoplatelets (GNP) based nanocomposites (labelled as GSN and GSD, respectively) to fabricate potential sensing layer. The combination of GNP and SnO2 nanostructures shows synergistic effects and provides high sensitivity and selectivity to the sensor. Post-immobilization method is used to prepare nanocomposites. Owing to difference in structures, GSN and GSD possess unique properties such as large surface area, catalytic nature, tunable porosity and non-toxicity and hence provide potential pathway for efficient sensing performance for HCB. Scanning electron microscopy (SEM) is used to confirm the preparation of [(SnO2)N], [(SnO2)D] and GSD. The GSD based probe fabricated with optimized parameters operates in the concentration range 0 g l‑1 to 10‑2 g l‑1 with low detection limit 1.085  ×  10‑15 g l‑1. The selectivity of the sensor is confirmed by carrying out the experiments using various possible interferands. The sensor can be used for online monitoring and remote sensing.

  2. Effects of Fiber/Matrix Interface and its Composition on Mechanical Properties of Hi Nicalon/Celsian Composites

    Science.gov (United States)

    Bansal, Narottam P.; Eldridge, Jeffrey I.

    1998-01-01

    Fiber-reinforced ceramic matrix composites (CMC) are prospective candidate materials for high temperature structural applications in aerospace, energy conservation, power generation, nuclear, petrochemical, and other industries. At NASA Lewis, we are investigating celsian matrix composites reinforced with various types of silicon carbide fibers. The objective of the present study was to investigate the effects of fiber/matrix interface and its composition on the mechanical properties of silicon carbide (Hi-Nicalon) fiber-reinforced celsian matrix composites.

  3. Syntesis of nitrides and carbides at surface of titanium by Nd-YAG pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Covelli, L.; Pierdominici, F.; Smurov, I.; Tosto, S.

    1991-12-31

    Microstructural SEM observations were carried out on samples of Ti irradiated with a Nd-YAG pulsed laser in the range of 10-40 J energy and 3-10 msec pulse length. The treatments were carried out on samples exposed to an atmosphere of nitrogen and on samples coated with graphite; it was thus possible to obtain nitrides and carbides as a consequence of laser irradiation. The morphology and distribution of the phases allowed research to obtain information about the fluid dynamics within the melt pool. It was found that the mechanisms of Ti nitride and carbide formation and growth are basically the same.

  4. Improved patterning of ITO coated with gold masking layer on glass substrate using nanosecond fiber laser and etching

    Science.gov (United States)

    Tan, Nguyen Ngoc; Hung, Duong Thanh; Anh, Vo Tran; BongChul, Kang; HyunChul, Kim

    2015-05-01

    In this paper, an indium-tin oxide (ITO) thin-film patterning method for higher pattern quality and productivity compared to the short-pulsed laser direct writing method is presented. We sputtered a thin ITO layer on a glass substrate, and then, plated a thin gold layer onto the ITO layer. The combined structure of the three layers (glass-ITO-gold) was patterned using laser-induced plasma generated by an ytterbium pulsed fiber laser (λ = 1064 nm). The results showed that the process parameters of 50 mm/s in scanning speed, 14 ns pulse duration, and a repetition rate of 7.5 kHz represented optimum conditions for the fabrication of ITO channels. Under these conditions, a channel 23.4 μm wide and 20 nm deep was obtained. However, built-up spikes (∼15 nm in height) resulted in a decrease in channel quality, and consequently, short circuit occurred at some patterned positions. These built-up spikes were completely removed by dipping the ITO layer into an etchant (18 wt.% HCl). A gold masking layer on the ITO surface was found to increase the channel surface quality without any decrease in ITO thickness. Moreover, the effects of repetition rate, scanning speed, and etching characteristics on surface quality were investigated.

  5. Novel fabrication of silicon carbide based ceramics for nuclear applications

    Science.gov (United States)

    Singh, Abhishek Kumar

    Advances in nuclear reactor technology and the use of gas-cooled fast reactors require the development of new materials that can operate at the higher temperatures expected in these systems. These materials include refractory alloys based on Nb, Zr, Ta, Mo, W, and Re; ceramics and composites such as SiC--SiCf; carbon--carbon composites; and advanced coatings. Besides the ability to handle higher expected temperatures, effective heat transfer between reactor components is necessary for improved efficiency. Improving thermal conductivity of the fuel can lower the center-line temperature and, thereby, enhance power production capabilities and reduce the risk of premature fuel pellet failure. Crystalline silicon carbide has superior characteristics as a structural material from the viewpoint of its thermal and mechanical properties, thermal shock resistance, chemical stability, and low radioactivation. Therefore, there have been many efforts to develop SiC based composites in various forms for use in advanced energy systems. In recent years, with the development of high yield preceramic precursors, the polymer infiltration and pyrolysis (PIP) method has aroused interest for the fabrication of ceramic based materials, for various applications ranging from disc brakes to nuclear reactor fuels. The pyrolysis of preceramic polymers allow new types of ceramic materials to be processed at relatively low temperatures. The raw materials are element-organic polymers whose composition and architecture can be tailored and varied. The primary focus of this study is to use a pyrolysis based process to fabricate a host of novel silicon carbide-metal carbide or oxide composites, and to synthesize new materials based on mixed-metal silicocarbides that cannot be processed using conventional techniques. Allylhydridopolycarbosilane (AHPCS), which is an organometal polymer, was used as the precursor for silicon carbide. Inert gas pyrolysis of AHPCS produces near-stoichiometric amorphous

  6. Radiation Damage of Quartz Fibers

    OpenAIRE

    Hagopian, V

    1999-01-01

    Quartz fibers are used in high energy physics experiments as the active medium in high radiation area calorimetry. Quartz fibers are also used in the transmission of optical signals. Even though quartz does not damage by moderate amounts of irradiation, the clad of the fibers and the protective coating ( buffer) do damage reducing light transmission. Various types of quartz fibers have been irradiated and measured for light transmission. The most radiation hard quartz fibers are those with qu...

  7. Silicon Carbide Nanotube Synthesized

    Science.gov (United States)

    Lienhard, Michael A.; Larkin, David J.

    2003-01-01

    Carbon nanotubes (CNTs) have generated a great deal of scientific and commercial interest because of the countless envisioned applications that stem from their extraordinary materials properties. Included among these properties are high mechanical strength (tensile and modulus), high thermal conductivity, and electrical properties that make different forms of single-walled CNTs either conducting or semiconducting, and therefore, suitable for making ultraminiature, high-performance CNT-based electronics, sensors, and actuators. Among the limitations for CNTs is their inability to survive in high-temperature, harsh-environment applications. Silicon carbon nanotubes (SiCNTs) are being developed for their superior material properties under such conditions. For example, SiC is stable in regards to oxidation in air to temperatures exceeding 1000 C, whereas carbon-based materials are limited to 600 C. The high-temperature stability of SiCNTs is envisioned to enable high-temperature, harsh-environment nanofiber- and nanotube-reinforced ceramics. In addition, single-crystal SiC-based semiconductors are being developed for hightemperature, high-power electronics, and by analogy to CNTs with silicon semiconductors, SiCNTs with single-crystal SiC-based semiconductors may allow high-temperature harsh-environment nanoelectronics, nanosensors, and nanoactuators to be realized. Another challenge in CNT development is the difficulty of chemically modifying the tube walls, which are composed of chemically stable graphene sheets. The chemical substitution of the CNTs walls will be necessary for nanotube self-assembly and biological- and chemical-sensing applications. SiCNTs are expected to have a different multiple-bilayer wall structure, allowing the surface Si atoms to be functionalized readily with molecules that will allow SiCNTs to undergo self-assembly and be compatible with a variety of materials (for biotechnology applications and high-performance fiber-reinforced ceramics).

  8. A solid-phase microextraction platinized stainless steel fiber coated with a multiwalled carbon nanotube-polyaniline nanocomposite film for the extraction of thymol and carvacrol in medicinal plants and honey.

    Science.gov (United States)

    Ghiasvand, Alireza; Dowlatshah, Samira; Nouraei, Nadia; Heidari, Nahid; Yazdankhah, Fatemeh

    2015-08-07

    A mechanically hard and cohesive porous fiber, with large surface area, for more strong attachment of the coating was provided by platinizing a stainless steel wire. Then, the platinized stainless steel fiber was coated with a multiwalled carbon nanotube/polyaniline (MWCNT/PANI) nanocomposite using electrophoretic deposition (EPD) method and applied for the extraction of thymol and carvacrol with direct-immersion solid-phase microextraction (DI-SPME) method followed by high-performance liquid chromatography-ultraviolet detection (HPLC-UV) quantification. To provide a larger coarse surface for the tightened attachment of coating on the fiber, a stainless steel wire was platinized using a suitable optimized EPD method. Different experimental parameters were studied and the optimal conditions were obtained as: pH of the sample solution: 2; extraction time: 60min; salt content in the sample solution: 1% w/v NaNO3; desorption time: 60min; type and volume of the desorption solvent: acetonitrile, 100μL. Under the optimized conditions, limits of detection (LODs) were 0.6 and 0.8μgmL(-1) for thymol and carvacrol, respectively. Linear dynamic range (LDR) for the calibration curves of both analytes were 1-80μgmL(-1). Relative standard deviation (RSD%, n=6) was 6.8 for thymol and 12.7 for carvacrol. The proposed fiber was successfully applied for the recovery and determination of thymol and carvacrol in thyme, savory, and honey samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Diethylenetriamine-assisted synthesis of amino-rich hydrothermal carbon-coated electrospun polyacrylonitrile fiber adsorbents for the removal of Cr(VI) and 2,4-dichlorophenoxyacetic acid.

    Science.gov (United States)

    Zhao, Rui; Li, Xiang; Sun, Bolun; Ji, He; Wang, Ce

    2017-02-01

    An environmentally benign and efficient hydrothermal carbonization method is widely applied for the preparation of carbon-based adsorbents. However, the adsorption capacity toward anionic species would be influenced due to the negatively charged surface of the traditional hydrothermal carbonaceous materials; moreover most of the carbonaceous materials were in the form of powder which restricted the practical applications. Herein, amino-rich hydrothermal carbon-coated electrospun polyacrylonitrile fiber (PAN@NC) adsorbents were obtained through one-step hydrothermal carbonization approach assisted by diethylenetriamine using polyacrylonitrile (PAN) fibers as the templates, which showed highly efficient adsorption for anionic pollutants. The PAN@NC fibers were characterized in detail to confirm their structures and composition. The flexible and robust PAN@NC fiber membrane exhibited high adsorption capacity and good regeneration and recycling ability toward the anionic metal ion Cr(VI) and herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). According to the Langmuir model, the adsorption behaviors showed monolayer adsorption capacities of 290.70mg/g and 164.47mg/g for Cr(VI) and 2,4-D, respectively, which were higher than that of many other adsorbents. Recycling study indicated that the removal efficiencies for both pollutants retained above 90% after five cycles. These findings demonstrate that PAN@NC fibers are promising adsorbents for the removal of anionic pollutants from wastewater solutions. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Full-field characterization of thermal diffusivity in continuous-fiber ceramic composite materials and components

    Science.gov (United States)

    Steckenrider, J. Scott; Ellingson, William A.; Rothermel, Scott A.

    1995-03-01

    Continuous-fiber ceramic matrix composites (CFCCs) are currently being developed for various high-temperature applications, including use in advanced heat engines. Among the material classes of interest for such applications are silicon carbide (SiC)-fiber-reinforced SiC (SiC(f)/SiC), SiC-fiber-reinforced silicon nitride (SiC(f)/Si3N4), aluminum oxide (Al2O3)-fiber-reinforced Al2O3 (Al2O3(f)/Al2O3), and others. In such composites, the condition of the interfaces (between the fibers and matrix) are critical to the mechanical and thermal behavior of the component (as are conventional mechanical defects such as cracks, porosity, etc.). For example, oxidation of this interface (especially on carbon coated fibers) can seriously degrade both mechanical and thermal properties. Furthermore, thermal shock damage can degrade the matrix through extensive crack generation. A nondestructive evaluation method that could be used to assess interface condition, thermal shock damage, and to detect other `defects' would thus be very beneficial, especially if applicable to full-scale components. One method under development uses infrared thermal imaging to provide `single-shot' full-field assessment of the distribution of thermal properties in large components by measuring thermal diffusivity. By applying digital image filtering, interpolation, and least-squares-estimation techniques for noise reduction, we can achieve acquisition and analysis times of minutes or less with submillimeter spatial resolution. The system developed at Argonne National Laboratory has been used to examine the effects of thermal shock, oxidation treatment, density variations, and variations in oxidation resistance coatings in a full array of test specimens. Subscale CFCC components with nonplanar geometries have also been studied for manufacturing-induced variations in thermal properties.

  11. THE MACHINING OF HARDENED CARBON STEELS BY COATED CUTTING TOOLS

    Directory of Open Access Journals (Sweden)

    Yusuf ŞAHİN

    2001-02-01

    Full Text Available The investigation of machining AISI 1050 carbon steels hardened to the 60 HRC hardness was carried out to determine the tool life and wear behaviour of the various cutting tools under different conditions. These experiments were conducted at using coated ceramic cutting tools and carbide cutting tools. The experimental results showed that the coated ceramic tools exhibited better performance than those of the coated carbide tools when machining the hardened steels. Moreover, wear behaviour of cutting tools were investigated in a scanning electron microscope. Electron microscopic examination also indicated that flank wear, thermal cracks on the tool nose combined with the nose deformation on the tools were responsible for the wear behaviour of the ceramic tools. For the carbide tools, however, removal of coated material from the substrate tool and combined with the crater wear were effective for the machining the hardened steel.

  12. A high area, porous and resistant platinized stainless steel fiber coated by nanostructured polypyrrole for direct HS-SPME of nicotine in biological samples prior to GC-FID quantification.

    Science.gov (United States)

    Abdolhosseini, Sana; Ghiasvand, Alireza; Heidari, Nahid

    2017-09-01

    The surface of a stainless steel fiber was made porous, resistant and cohesive using electrophoretic deposition and coated by the nanostructured polypyrrole using an amended in-situ electropolymerization method. The coated fiber was applied for direct extraction of nicotine in biological samples through a headspace solid-phase microextraction (HS-SPME) method followed by GC-FID determination. The effects of the important experimental variables on the efficiency of the developed HS-SPME-GC-FID method, including pH of sample solution, extraction temperature and time, stirring rate, and ionic strength were evaluated and optimized. Under the optimal experimental conditions, the calibration curve was linear over the range of 0.1-20μgmL-1 and the detection limit was obtained 20ngmL-1. Relative standard deviation (RSD, n=6) was calculated 7.6%. The results demonstrated the superiority of the proposed fiber compared with the most used commercial types. The proposed HS-SPME-GC-FID method was successfully used for the analysis of nicotine in urine and human plasma samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Obtenção de um revestimento compósito de poliéster-uretana reforçado com alumina pela técnica de deposição por imersão sobre fibras de poliamida 6 Preparation of a composite coating of alumina reinforced polyester urethane by dip coating on polyamide 6 fibers

    Directory of Open Access Journals (Sweden)

    F. A. L. Sánchez

    2009-12-01

    Full Text Available O uso de revestimentos compósitos de matriz polimérica e reforço cerâmico capazes de manter a flexibilidade e a elasticidade das fibras poliméricas, agregando propriedades típicas dos materiais cerâmicos (como ação bactericida ou fotocatalítica, resistência à chama, ao desgaste e à abrasão, tem atraído interesse da indústria têxtil. Baseado na técnica dip coating e usando fibras sintéticas de poliamida como substrato, foram produzidas suspensões de poliéster-uretana com partículas de alumina (tamanho médio de partícula 2,2 μm para obtenção de revestimentos uniformes e espessos sobre o material base, poliamida 6. A viscosidade das suspensões foi controlada pela adição de carboximetilcelulose e avaliada por reometria rotacional. A distribuição granulométrica das suspensões também foi determinada. Os parâmetros operacionais do dip coating, i.e., velocidade de bobinamento e temperatura dos fornos, foram mantidos constantes em todas as amostras. O processo mostrou viabilidade para deposição uniforme do recobrimento avaliado, com espessura adequada, indicando ser promissor para revestir fibras, agregando propriedades de interesse tecnológico.Ceramic reinforced polymer composite coatings that can retain the flexibility and elasticity of the polymeric fibers, being also able to incorporate the functionality of ceramic materials (e.g. fire, wear, or abrasion resistance, antibacterial performance, photocatalytic effect are interesting to the processing of textile materials. In this work, polyester-urethane slurries with alumina particles (mean particle size: 2.2 μm were developed based on the dip coating technique and using polyamide-6 synthetic fibers as the substrate, seeking to obtain an uniform and thick coating. The viscosity of the slurries was varied using carboxymethylcellulose as a rheological agent and evaluated by rotational rheometry. Particle size distribution of the slurries was also analyzed. The

  14. Shear properties at the PyC/SiC interface of a TRISO-coating

    Science.gov (United States)

    Nozawa, T.; Snead, L. L.; Katoh, Y.; Miller, J. H.

    2007-09-01

    The failure behavior of TRISO-coated fuel particles depends significantly on the shear strength at the interface between the inner pyrolytic carbon (PyC) and silicon carbide (SiC) coatings. In this study, a micro-indentation fiber push-out test was applied to measure the interfacial shear properties of a model TRISO-coated tube. Of particular emphasis is that this study developed a non-linear shear-lag model for a transversely isotropic composite material due to insufficiency in the existing isotropic models as applied to layered TRISO-coating systems. In the model, the effects of thermal residual stresses and the roughness-induced clamping stress were identified as particularly important. The rigorous model proposed in this study provides more reasonable data on two important interfacial parameters: the interfacial debond shear strength and the interfacial friction stress. The modified model coupled with experiments yields an interfacial debond shear strength of 240 ± 40 MPa. This high interfacial strength, though slightly lower than that obtained by the existing isotropic model (˜280 MPa), allows significant loads to be transferred between inner PyC and SiC in application. Additionally, an interfacial friction stress of 120 ± 30 MPa was determined. This high friction stress is attributed primarily to the roughness at the cracked interface rather than clamping effects due to differing coefficients of thermal expansion.

  15. Growth and Physical Structure of Amorphous Boron Carbide Deposited by Magnetron Sputtering on a Silicon Substrate with a Titanium Interlayer

    Directory of Open Access Journals (Sweden)

    Roberto Caniello

    2013-01-01

    Full Text Available Multilayer amorphous boron carbide coatings were produced by radiofrequency magnetron sputtering on silicon substrates. To improve the adhesion, titanium interlayers with different thickness were interposed between the substrate and the coating. Above three hundreds nanometer, the enhanced roughness of the titanium led to the growth of an amorphous boron carbide with a dense and continuing columnar structure, and no delamination effect was observed. Correspondingly, the adhesion of the coating became three time stronger than in the case of a bare silicon substrate. Physical structure and microstructural proprieties of the coatings were investigated by means of a scan electron microscopy, atomic force microscopy and X-ray diffraction. The adhesion of the films was measured by a scratch tester.

  16. Hydroxide catalysis bonding of silicon carbide

    NARCIS (Netherlands)

    Veggel, A.A. van; Ende, D.A. van den; Bogenstahl, J.; Rowan, S.; Cunningham, W.; Gubbels, G.H.M.; Nijmeijer, H.

    2008-01-01

    For bonding silicon carbide optics, which require extreme stability, hydroxide catalysis bonding is considered [Rowan, S., Hough, J. and Elliffe, E., Silicon carbide bonding. UK Patent 040 7953.9, 2004. Please contact Mr. D. Whiteford for further information: D.Whiteford@admin.gla.ac.uk]. This

  17. Silver diffusion through silicon carbide in microencapsulated nuclear fuels TRISO; Difusion de plata a traves de carburo de silicio en combustibles nucleares microencapsulados TRISO

    Energy Technology Data Exchange (ETDEWEB)

    Cancino T, F.; Lopez H, E., E-mail: Felix.cancino@cinvestav.edu.mx [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Saltillo, Av. Industria Metalurgica No. 1062, Col. Ramos Arizpe, 25900 Saltillo, Coahuila (Mexico)

    2013-10-15

    The silver diffusion through silicon carbide is a challenge that has persisted in the development of microencapsulated fuels TRISO (Tri structural Isotropic) for more than four decades. The silver is known as a strong emitter of gamma radiation, for what is able to diffuse through the ceramic coatings of pyrolytic coal and silicon carbide and to be deposited in the heat exchangers. In this work we carry out a recount about the art state in the topic of the diffusion of Ag through silicon carbide in microencapsulated fuels and we propose the role that the complexities in the grain limit can have this problem. (Author)

  18. Femtosecond laser induced breakdown spectroscopy of silver within surrogate high temperature gas reactor fuel coated particles

    CSIR Research Space (South Africa)

    Roberts, DE

    2010-11-01

    Full Text Available The detection of metallic silver on Chemical Vapour Deposited (CVD) grown silicon carbide and in Pebble Bed Modular Reactor (PBMR) supplied tri-structural isotropic (TRISO) coated particles (with 500 µm diameter zirconium oxide surrogate kernel) has...

  19. Carbide braze cladding for titanium components; Auftragloeten von Karbiden fuer Verschleissschutz von Titanbauteilen

    Energy Technology Data Exchange (ETDEWEB)

    Bobzin, K.; Ernst, F.; Roesing, J.; Rojas, Y. [RWTH Aachen (Germany)

    2007-07-01

    The abrasion resistance of pure titanium and titanium alloys is not always sufficient for applications where wear resistance demands play an important roll, especially for systems which involve relative sliding tribosystems such as valves, piping connections, etc. Because of this and due to the increasing interest on light materials for structural purposes, the necessity to develop innovative coating techniques in order to increase lifetime and performance of tools keeps on arising. Surface coatings produced by combining braze filler metal with carbide particles increase surface hardness and wear resistance of pure titanium and titanium alloys, which result to be of considerable interest for many engineering applications. This study shows different composite systems based on silver braze and titanium braze alloys, which were especially designed for commercial titanium alloys. The produced carbide/brazing mixtures were brazed and characterised by means of microscopy and ball-on-disc tests, showing an improvement on the wear resistant properties when compared to titanium. (orig.)

  20. Synthesis of layered zinc hydroxide intercalated with dodecyl sulfate organic-inorganic hybrid nanocomposite as a fiber coating for the headspace solid-phase microextraction of aromatic hydrocarbons from water.

    Science.gov (United States)

    Yousefi, Vahid; Parastari, Sheyda; Gorji, Mohsen; Foroutani, Reza; Mahdavi, Mehri; Hazizadeh, Behzad

    2016-12-01

    We describe the synthesis of a layered zinc hydroxide-dodecyl sulfate organic-inorganic hybrid nanocomposite as a new solid-phase microextraction fiber. The fiber coating can be prepared easily in a short time and the reaction is at room temperature; it is mechanically stable and exhibits relatively high thermal stability. The synthesized layered zinc hydroxide-dodecyl sulfate nanocomposite was successfully prepared and immobilized on a stainless steel wire and evaluated for the extraction of aromatic compounds from aqueous sample solutions in combination with gas chromatography and mass spectrometry. The method yields good results for some validation parameters. Under optimum conditions (extraction time: 15 min, extraction temperature: 50°C, desorption time: 1 min, desorption temperature: 250°C, salt concentration: 0.5 g/mL), the limit of detection and dynamic linear range were 0.69-3.2 ng/L and 10-500 ng/L, respectively. The method was applied to the analyses of benzene, toluene, ethylbenzene, and o-, p-, and m-xylenes in two real water samples collected from the Aji river and Mehran river, Tabriz, Iran. Under optimum conditions, the repeatability and reproducibility for one fiber (n = 3), expressed as the relative standard deviation, was 3.2-7.3% and 4.2-11.2% respectively. The fibers are thermally stable and yield better recoveries than conventional methods of analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Influence of melt treatments and polished CVD diamond coated ...

    Indian Academy of Sciences (India)

    WINTEC

    At present, the cemented carbide inserts alone or with. TiN, TiC or TiN + .... Carbide grade. Uncoated insert-K-10: 94%WC + 6%CO. Polished CVD diamond coated, Ra, 0⋅14–0⋅16 μm the present work and geometry of the inserts are given in table 3. .... duces a chip and plastic deformation of the chip and the workpiece ...

  2. Determination of phthalate esters in drinking water and edible vegetable oil samples by headspace solid phase microextraction using graphene/polyvinylchloride nanocomposite coated fiber coupled to gas chromatography-flame ionization detector.

    Science.gov (United States)

    Amanzadeh, Hatam; Yamini, Yadollah; Moradi, Morteza; Asl, Yousef Abdossalmi

    2016-09-23

    In the current study, a graphene/polyvinylchloride nanocomposite was successfully coated on a stainless steel substrate by a simple dip coating process and used as a novel headspace solid phase microextraction (HS-SPME) fiber for the extraction of phthalate esters (PEs) from drinking water and edible vegetable oil samples. The prepared SPME fibers exhibited high extractability for PEs (due to the dominant role of π-π stacking interactions and hydrophobic effects) yielding good sensitivity and precision when followed by a gas chromatograph with a flame ionization detector (GC-FID). The optimization strategy of the extraction process was carried out using the response surface method based on a central composite design. The developed method gave a low limit of detection (0.06-0.08μgL(-1)) and good linearity (0.2-100μgL(-1)) for the determination of the PEs under the optimized conditions (extraction temperature, 70±1°C; extraction time, 35min; salt concentration, 30% w/v; stirring rate, 900rpm; desorption temperature, 230°C; and desorption time, 4min) whereas the repeatability and fiber-to-fiber reproducibility were in the range 6.1-7.8% and 8.9-10.2%, respectively. Finally, the proposed method was successfully applied to the analysis of PEs in drinking water and edible oil samples with good recoveries (87-112%) and satisfactory precisions (RSDs<8.3%), indicating the absence of matrix effects in the proposed HS-SPME method. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. An alkalinizing oral rehydration solution containing lecithin-coated citrus fiber is superior to a nonalkalinizing solution in treating 360 calves with naturally acquired diarrhea.

    Science.gov (United States)

    Goodell, G M; Campbell, J; Hoejvang-Nielsen, L; Stansen, W; Constable, P D

    2012-11-01

    The aim of this field study was to compare the efficacy and cost of 2 commercially available oral rehydration therapy (ORT) solutions in treating dairy calves with naturally acquired diarrhea. A total of 1,349 newborn Holstein-Friesian calves were prospectively enrolled in the study. Calves were housed in individual hutches and fed a mixture of pasteurized hospital milk and an all-milk protein milk replacer twice per day. Calves were monitored twice each day from d 2 of life until 30 d of age for the presence or absence of diarrhea, and were assigned a fecal score and a hydration score at each examination. Calves that developed mild to severe diarrhea that did not need intravenous fluids and did not have clinical evidence of concurrent disease (n = 360) were assigned randomly to receive 1 of 2 commercial ORT solutions: a hypertonic alkalinizing ORT containing lecithin-coated citrus fibers (Diaque, group D, n = 180; Boehringer Ingelheim, Ingelheim, Germany), and an isotonic nonalkalinizing ORT (RE-SORB, group R, n = 180; Pfizer Animal Health, New York, NY) for 2 to 8d; the duration of treatment depended on whether diarrhea was still present. No significant differences were observed in mortality rates or treatment failure rates between the 2 treatment groups. Fecal consistency returned to normal more quickly in group D calves than in group R calves; consequently, group D calves were treated for 1d less than were group R calves. The increase in body weight after 4d of treatment was larger in group D than in group R. The average daily gain from birth to weaning in calves that did not develop concurrent disease (such as pneumonia) during the study period tended to be higher in group D calves (0.53±0.11 kg/d) than in group R calves (0.51±0.09 kg/d). The smaller number of treatments at a lower cost per treatment produced a cost advantage of $4.82 per treated calf in group D calves compared with group R calves. Our findings support the concept that milk should continue

  4. Synthesis and characterization of silicon-based polymers for use as organic/inorganic hybrids and silicon carbide precursors

    Science.gov (United States)

    Sellinger, Alan

    Organic/inorganic hybrids from silsesquioxanes. This Dissertation describes the synthesis and characterization of methacrylate, epoxy and liquid crystalline (LC)-containing organic/inorganic hybrid materials based on silsesquioxanes. While the methacrylate and epoxy groups provide polymerizable moieties to the hybrids, the LC component is anticipated to provide toughness, and oxidative stability as well as minimize shrinkage during curing. The inorganic silsesquioxane portion, ((RSiOsb{1.5})sb8, cubes), which closely resembles specific crystalline forms of silica and zeolites, may be covalently linked to a variety of organic functional groups. As a result, single-phase organic/inorganic hybrids are formed that when polymerized mimic silica-reinforced composites. The resultant hybrids are liquids at room temperature, and hence allow for single-phase composite processing, ideal for abrasion-resistant coatings and filling molds, as in dental restorative applications. The reactions are based on inexpensive starting materials, have high yields (>80%), and form soluble products containing up to 65% masked silica. The hybrids were characterized using NMR spectroscopy (sp1H,\\ sp{13}C,\\ sp{29}Si), FTIR, size exclusion chromatography (SEC), and thermal analysis (TGA, DSC). A modified polymethylsilane as a precursor of silicon carbide. It is generally known that polymer precursor routes to silicon carbide (SiC) are very important in the processing of SiC fibers and high performance SiC parts with specific shapes. It is further known that commercial SiC precursor polymers are often not resistant to oxidation, and are based on monomers rich in carbon. As a result of this, their pyrolysis yields SiC rich in oxygen and carbon, a feature which drastically reduces the final materials' ultimate properties (high temperature resistance, tensile strength, modulus). To remedy this, we describe in this work the synthesis and characterization of a modified polymethylsilane (mPMS) which

  5. Evaluation of Codisposal Viability for TH/U Carbide (Fort Saint Vrain HTGR) DOE-Owned Fuel

    Energy Technology Data Exchange (ETDEWEB)

    H. radulescu

    2001-09-28

    There are more than 250 forms of US Department of Energy (DOE)-owned spent nuclear fuel (SNF). Due to the variety of the spent nuclear fuel, the National Spent Nuclear Fuel Program has designated nine representative fuel groups for disposal criticality analyses based on fuel matrix, primary fissile isotope, and enrichment. The Fort Saint Vrain reactor (FSVR) SNF has been designated as the representative fuel for the Th/U carbide fuel group. The FSVR SNF consists of small particles (spheres of the order of 0.5-mm diameter) of thorium carbide or thorium and high-enriched uranium carbide mixture, coated with multiple, thin layers of pyrolytic carbon and silicon carbide, which serve as miniature pressure vessels to contain fission products and the U/Th carbide matrix. The coated particles are bound in a carbonized matrix, which forms fuel rods or ''compacts'' that are loaded into large hexagonal graphite prisms. The graphite prisms (or blocks) are the physical forms that are handled in reactor loading and unloading operations, and which will be loaded into the DOE standardized SNF canisters. The results of the analyses performed will be used to develop waste acceptance criteria. The items that are important to criticality control are identified based on the analysis needs and result sensitivities. Prior to acceptance to fuel from the Th/U carbide fuel group for disposal, the important items for the fuel types that are being considered for disposal under the Th/U carbide fuel group must be demonstrated to satisfy the conditions determined in this report.

  6. Uranium Carbide Powder Ignition Studies

    Energy Technology Data Exchange (ETDEWEB)

    Berthinier, C.; Coullomb, S.; Rado, C.; Le Guyadec, F. [CEA, DEN, DTEC, SDTC, LEME, F-30207 Bagnols-sur-Ceze (France); Chatillon, C.; Blanquet, E.; Boichot, R. [SIMAP, Sciences et Ingenierie des Materiaux et Procedes, INPG-CNRS-UJF ENSEEG, BP 75, 38402 St Martin-d' Heres (France)

    2009-06-15

    Mixed (U, Pu) carbide, constituted by means of 80% of uranium monocarbide (UC), is considered as a possible fuel material for future gas fast reactors or sodium fast reactor. However, UC undergoes a strong exothermic reaction with air and fine powders of UC are pyrophoric. Thus, it is necessary to understand this high reactivity in order to determine safe handling conditions for the production and reprocessing of carbide fuels. UC powder was obtained by arc melting and milling. The reactivity of uranium carbide was studied in oxidizing atmosphere and different experimental devices were used to determine ignition temperatures. The phases formed at the various observed stages of the oxidation process were determined by post-mortem X ray diffraction analysis. Studies were first performed using small quantities of UC powder (around 50 mg) in Differential Thermal Analysis / Thermogravimetric Analysis (DTA/TGA) and Differential Scanning Calorimetry (DSC). Experiments were realized using different parameters, such as heating rate and gas flow rate and composition, to determine their influence on pyro-phoricity. Results obtained with small quantities (tens of milligrams) revealed that UC powder is highly reactive in air in the range 200- 250 deg. C. Studies were also performed in the 'Pyro' test facility multi-function furnace allowing CCD camera recording, during heating and ignition, through view-ports. Lower ignition temperatures, around 100 deg. C, were obtained using around 1 g UC powder samples. Results are discussed and analysed with theory of burning curve ignition and numerical simulations. Simulations aim to understand the influence of the different parameters on pyro-phoricity. Small scale simulations (on a spherical grain) confirm the influence of UC grains size, heat rate and gas composition on powder ignition temperature with small quantities. The issue is now to understand the influence of grain pile form factor and volume on the pyro-phoricity of

  7. Evaluation of a new method for chemical coating of aluminum wire with molecularly imprinted polymer layer. Application for the fabrication of triazines selective solid-phase microextraction fiber

    Energy Technology Data Exchange (ETDEWEB)

    Djozan, Djavanshir, E-mail: djozan@tabrizu.ac.ir [Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of); Ebrahimi, Bahram [Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of); Mahkam, Mehrdad [Chemistry Department, Azarbaijan University of Tarbiat Moallem, Tabriz (Iran, Islamic Republic of); Farajzadeh, Mir Ali [Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2010-07-26

    A new solid-phase microextraction (SPME) fiber is fabricated through ultra violet irradiation polymerization of ametryn-molecularly imprinted polymer on the surface of anodized-silylated aluminum wire. The prepared fiber is durable with very good chemical and thermal stability which can be coupled to GC and GC/MS. The effective parameters on the fabrication and application procedures such as spraying mode, ultra violet irradiation (polymerization) time, number of sprayings and polymerizations, pH and ionic strength of sample and extraction time were optimized. This fiber shows high selectivity with great extraction capacity toward triazines. SPME and GC analysis of ametryn, prometryn, terbutryn, atrazine, simazine, propazine and cyanazine using the fabricated fiber result in the detection limits of 9, 32, 27, 43, 51, 74 and 85 ng mL{sup -1}, respectively. The reliability of the prepared fiber in real samples has been investigated and proved by using spiked tap water, rice, maize and onion samples.

  8. Electrochemical behaviors of a wearable woven textile Li-ion battery consisting of a core and wound electrode fibers coated with active materials

    Science.gov (United States)

    Kim, C.; Bang, S.; Zhou, D.; Yun, S.

    2017-04-01

    A new fiber-type Li-ion battery that consists of carbon nanotube fibers deposited with active materials has been developed and tested. The active materials, LiMn2O4 and Li4Ti5O12, were deposited on the surface of carbon nanotube fibers in order to use as electrodes. Tensile strength of the CNT fibers with active material was measured by tensile tests to investigate the mechanical characteristics. Electrochemical property is also measured by a battery tester during charging and discharging. The results show that current discharge capacity is about 25 mAh/g between 3.0 V and 4.2 V. That means the fiber with active materials is good for an anode electrode. Mathematical material models considering the lithium concentration and the length of Li-C bond have been established in order to predict the effective elastic modulus of electrode composite materials.

  9. Preconcentration and determination of polybrominated diphenyl ethers in environmental water samples by solid-phase microextraction with Fe3O4-coated bamboo charcoal fibers prior to gas chromatography-mass spectrometry.

    Science.gov (United States)

    Zhao, Ru-Song; Liu, Yan-Long; Chen, Xiang-Feng; Yuan, Jin-Peng; Bai, Ai-Ying; Zhou, Jia-Bin

    2013-03-26

    In this paper, bamboo charcoals were modified using Fe3O4 nanosheets for the first time. The composites, as a novel solid-phase microextraction (SPME) fiber coating, were used for the extraction of seven polybrominated diphenyl ethers (PBDEs) in environmental water samples. The extraction factors (stirring rate, extraction time, and ionic strength) and desorption factors (desorption time and desorption temperature) of the fibers were systematically investigated and optimized. Under optimum conditions, the linear range was 1-1000 ng L(-1). Based on the ratio of chromatographic signal to base line noise (SN(-1)=3), the limits of detection (LODs) can reach 0.25-0.62 ng L(-1). The novel method was successful in the analysis of PBDEs in real environmental water samples. The results indicate that bamboo charcoal/Fe3O4 as an SPME coating material coupled with gas chromatography-negative chemical ionization-mass spectrometry is an excellent method for the routine analysis of PBDEs at trace levels in environmental water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Thermal Expansion of Hafnium Carbide

    Science.gov (United States)

    Grisaffe, Salvatore J.

    1960-01-01

    Since hafnium carbide (HfC) has a melting point of 7029 deg. F, it may have many high-temperature applications. A literature search uncovered very little information about the properties of HfC, and so a program was initiated at the Lewis Research Center to determine some of the physical properties of this material. This note presents the results of the thermal expansion investigation. The thermal-expansion measurements were made with a Gaertner dilatation interferometer calibrated to an accuracy of +/- 1 deg. F. This device indicates expansion by the movement of fringes produced by the cancellation and reinforcement of fixed wave-length light rays which are reflected from the surfaces of two parallel quartz glass disks. The test specimens which separate these disks are three small cones, each approximately 0.20 in. high.

  11. Microstructure and mechanical properties of proton irradiated zirconium carbide

    Energy Technology Data Exchange (ETDEWEB)

    Yang Yong [Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States)], E-mail: yyang@cae.wisc.edu; Dickerson, Clayton A.; Swoboda, Hannah [Material Science Program, University of Wisconsin-Madison, Madison, WI 53706 (United States); Miller, Brandon; Allen, Todd R. [Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2008-09-01

    Zirconium carbide is a candidate ceramic being considered for metal-carbide-base composite-type fuels, as well as for an alternative coating material for TRISO particle fuels. Ensuring adequate mechanical properties and dimensional stability in response to radiation is a key part in developing a practical ZrC-base fuel. The existing available radiation response data for ZrC is limited and insufficient. In the present study, ZrC was irradiated with a 2.6 MeV proton beam at 800 deg. C to doses of 0.7 and 1.5 dpa. Following radiation, the radiation induced damage microstructure is comprised of a high density of nanometer-sized Frank loops, but no irradiation induced amorphization, voids, or precipitates were observed. A slight lattice expansion was found in the irradiated ZrC, in good agreement with the reported results from neutron irradiation. The changes in microhardness and fracture toughness properties induced in the irradiated samples were measured using indentation techniques. The hardness and the fracture toughness both increase with increasing radiation dose.

  12. Ion beam figuring of CVD silicon carbide mirrors

    Science.gov (United States)

    Gailly, P.; Collette, J.-P.; Fleury Frenette, K.; Jamar, C.

    2017-11-01

    Optical and structural elements made of silicon carbide are increasingly found in space instruments. Chemical vapor deposited silicon carbide (CVD-SiC) is used as a reflective coating on SiC optics in reason of its good behavior under polishing. The advantage of applying ion beam figuring (IBF) to CVD-SiC over other surface figure-improving techniques is discussed herein. The results of an IBF sequence performed at the Centre Spatial de Liège on a 100 mm CVD-SiC mirror are reported. The process allowed to reduce the mirror surface errors from 243 nm to 13 nm rms . Beside the surface figure, roughness is another critical feature to consider in order to preserve the optical quality of CVD-SiC . Thus, experiments focusing on the evolution of roughness were performed in various ion beam etching conditions. The roughness of samples etched at different depths down to 3 ≠m was determined with an optical profilometer. These measurements emphasize the importance of selecting the right combination of gas and beam energy to keep roughness at a low level. Kaufman-type ion sources are generally used to perform IBF but the performance of an end-Hall ion source in figuring CVD-SiC mirrors was also evaluated in this study. In order to do so, ion beam etching profiles obtained with the end-Hall source on CVD-SiC were measured and used as a basis for IBF simulations.

  13. Oxidation Behavior of Carbon Fiber-Reinforced Composites

    Science.gov (United States)

    Sullivan, Roy M.

    2008-01-01

    OXIMAP is a numerical (FEA-based) solution tool capable of calculating the carbon fiber and fiber coating oxidation patterns within any arbitrarily shaped carbon silicon carbide composite structure as a function of time, temperature, and the environmental oxygen partial pressure. The mathematical formulation is derived from the mechanics of the flow of ideal gases through a chemically reacting, porous solid. The result of the formulation is a set of two coupled, non-linear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations are solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of the spatial location and time. The local rate of carbon oxidation is determined at each time step using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The non-linear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual finite element method, allowing for the solution of the differential equations numerically.

  14. Monitoring the thin film formation during sputter deposition of vanadium carbide

    Energy Technology Data Exchange (ETDEWEB)

    Kaufholz, Marthe, E-mail: marthe.kaufholz@kit.edu; Krause, Bärbel; Kotapati, Sunil; Köhl, Martin [ANKA/Institut für Photonenforschung und Synchrotronstrahlung, Karlsruher Institut für Technologie, Karlsruhe (Germany); Mantilla, Miguel F. [Max-Planck-Institut für Intelligente Systeme, Stuttgart (Germany); Stüber, Michael; Ulrich, Sven [Institut für Angewandte Materialien - Angewandte Werkstoffphysik, Karlsruher Institut für Technologie, Karlsruhe (Germany); Schneider, Reinhard; Gerthsen, Dagmar [Laboratorium für Elektronenmikroskopie, Karlsruher Institut für Technologie, Karlsruhe (Germany); Baumbach, Tilo [ANKA/Institut für Photonenforschung und Synchrotronstrahlung, Karlsruher Institut für Technologie, Karlsruhe (Germany)

    2015-01-01

    The theoretical description and the experimental realisation of in situ X-ray reflectivity measurements during thin film deposition of polycrystalline vanadium carbide coatings are presented. The thin film formation of magnetron sputtered polycrystalline coatings was monitored by in situ X-ray reflectivity measurements. The measured intensity was analyzed using the Parratt algorithm for time-dependent thin film systems. Guidelines for the on-line interpretation of the data were developed. For thick coatings, the experimental resolution needs to be included in the data evaluation in order to avoid misinterpretations. Based on a simple layer model, the time-dependent mean electron density, roughness and growth velocity were extracted from the data. As an example, the method was applied to the hard coating material vanadium carbide. Both instantaneous and slowly varying changes of the coating could be detected. It was shown that the growth velocity is proportional to the DC power. Significant changes of the microstructure induced by the working gas pressure are mainly driven by the chemical composition.

  15. Theoretical prediction of energy release rate for interface crack initiation by thermal stress in environmental barrier coatings for ceramics

    Science.gov (United States)

    Kawai, E.; Umeno, Y.

    2017-05-01

    As weight reduction of turbines for aircraft engines is demanded to improve fuel consumption and curb emission of carbon dioxide, silicon carbide (SiC) fiber reinforced SiC matrix composites (SiC/SiC) are drawing enormous attention as high-pressure turbine materials. For preventing degradation of SiC/SiC, environmental barrier coatings (EBC) for ceramics are deposited on the composites. The purpose of this study is to establish theoretical guidelines for structural design which ensures the mechanical reliability of EBC. We conducted finite element method (FEM) analysis to calculate energy release rates (ERRs) for interface crack initiation due to thermal stress in EBC consisting of Si-based bond coat, Mullite and Ytterbium (Yb)-silicate layers on a SiC/SiC substrate. In the FEM analysis, the thickness of one EBC layer was changed from 25 μm to 200 μm while the thicknesses of the other layers were fixed at 25 μm, 50 μm and 100 μm. We compared ERRs obtained by the FEM analysis and a simple theory for interface crack in a single-layered structure where ERR is estimated as nominal strain energy in the coating layers multiplied by a constant factor (independent of layer thicknesses). We found that, unlike the case of single-layered structures, the multiplication factor is no longer a constant but is determined by the combination of consisting coating layer thicknesses.

  16. Method of producing novel silicon carbide articles. [Patent application

    Science.gov (United States)

    Milewski, J.V.

    1982-06-18

    A method of producing articles comprising reaction-bonded silicon carbide (SiC) and graphite (and/or carbon) is given. The process converts the graphite (and/or carbon) in situ to SiC, thus providing the capability of economically obtaining articles made up wholly or partially of SiC having any size and shape in which graphite (and/or carbon) can be found or made. When the produced articles are made of an inner graphite (and/or carbon) substrate to which SiC is reaction bonded, these articles distinguish SiC-coated graphite articles found in the prior art by the feature of a strong bond having a gradual (as opposed to a sharply defined) interface which extends over a distance of mils. A method for forming SiC whisker-reinforced ceramic matrices is also given. The whisker-reinforced articles comprise SiC whiskers which substantially retain their structural integrity.

  17. Nanostructured thin film coatings with different strengthening effects

    Directory of Open Access Journals (Sweden)

    Panfilov Yury

    2017-01-01

    Full Text Available A number of articles on strengthening thin film coatings were analyzed and a lot of unusual strengthening effects, such as super high hardness and plasticity simultaneously, ultra low friction coefficient, high wear-resistance, curve rigidity increasing of drills with small diameter, associated with process formation of nanostructured coatings by the different thin film deposition methods were detected. Vacuum coater with RF magnetron sputtering system and ion-beam source and arc evaporator for nanostructured thin film coating manufacture are represented. Diamond Like Carbon and MoS2 thin film coatings, Ti, Al, Nb, Cr, nitride, carbide, and carbo-nitride thin film materials are described as strengthening coatings.

  18. Trace determination of organophosphate esters in environmental water samples with an ionogel-based nanoconfined ionic liquid fiber coating for solid-phase microextraction with gas chromatography and flame photometric detection.

    Science.gov (United States)

    Pang, Long; Pang, Rong; Ge, Liming; Zheng, Liqing; Zhao, Jihong; Zhang, Hongzhong

    2016-11-01

    Organophosphate esters, widely used as flame retardants and plasticizers, are regarded as a class of emerging pollutants. In this work, a novel approach was developed for the fabrication of a solid-phase microextraction fiber by using hybrid silica-based materials with immobilized ionic liquids with sol-gel technology, and the prepared solid-phase microextraction fiber was then coupled with gas chromatography and flame photometric detection for the analysis of six organophosphate esters. The high loading of 1-hexadecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide was confined within the hybrid network. The developed solid-phase microextraction fiber possesses a coating thickness of ∼35 μm with good thermal stability and long lifetime. The parameters affecting the extraction efficiency such as extraction time, temperature, pH, and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.04-0.95 μg L(-1) , and the precision of the method assessed with repeatability and reproducibility of (RSD%) ˂13 and ˂29%, respectively. The proposed method was successfully applied to determine the six organophosphate esters in three real water samples, with recoveries in the range of 64.8-125.4% at two different spiking concentration levels. As a result, the proposed method demonstrated its potential for application in trace determination of organophosphate esters in actual water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Dynamics of carbide formation in iron-supported catalysts of the Fischer-Tropsch process promoted by copper and potassium

    Science.gov (United States)

    Kazak, V. O.; Pankina, G. V.; Chernavskii, P. A.; Lunin, V. V.

    2017-05-01

    The kinetics of the formation of iron carbides during the activation of iron-coated catalyst for Fischer-Tropsch synthesis promoted by copper and potassium, and by carbon monoxide and syngas, is studied. It is established that the presence of copper lowers the initial temperature of hematite reduction to magnetite and leads to the formation of carbide in both CO and CO/H2. Potassium slows the rate of magnetite formation, but it accelerates the formation of iron oxide. It is shown that the rate of carbide formation during magnetite reduction for catalysts is half that in the reaction of hematite reduction to magnetite in both CO and CO/H2.

  20. Conformal Coating of Cobalt-Nickel Layered Double Hydroxides Nanoflakes on Carbon Fibers for High-performance Electrochemical Energy Storage Supercapacitor Devices

    KAUST Repository

    Warsi, Muhammad Farooq

    2014-07-01

    High specific capacitance coupled with the ease of large scale production is two desirable characteristics of a potential pseudo-supercapacitor material. In the current study, the uniform and conformal coating of nickel-cobalt layered double hydroxides (CoNi0.5LDH,) nanoflakes on fibrous carbon (FC) cloth has been achieved through cost-effective and scalable chemical precipitation method, followed by a simple heat treatment step. The conformally coated CoNi0.5LDH/FC electrode showed 1.5 times greater specific capacitance compared to the electrodes prepared by conventional non-conformal (drop casting) method of depositing CoNi0.5LDH powder on the carbon microfibers (1938 Fg-1 vs 1292 Fg-1). Further comparison of conformally and non-conformally coated CoNi0.5LDH electrodes showed the rate capability of 79%: 43% capacity retention at 50 Ag-1 and cycling stability 4.6%: 27.9% loss after 3000 cycles respectively. The superior performance of the conformally coated CoNi0.5LDH is mainly due to the reduced internal resistance and fast ionic mobility between electrodes as compared to non-conformally coated electrodes which is evidenced by EIS and CV studies. © 2014 Elsevier Ltd.

  1. Micromechanical analysis of constitutive properties of active piezoelectric structural fiber (PSF) composites

    Science.gov (United States)

    Ng, Kenny; Dai, Qingli

    2011-04-01

    Recent studies showed that the active piezoelectric structural fiber (PSF) composites may achieve significant and simultaneous improvements in sensing/actuating, stiffness, fracture toughness and vibration damping. These characteristics can be very important in the application of civil, mechanical and aerospace structures. The PSF is fabricated by coating the piezoceramic onto the silicon carbide core fiber with electrophoretic deposition (EPD) process to overcome the fragile nature of the monolithic piezoelectric materials. The PSF composite laminates are made of longitudinally poled PSFs that are unidirectionally deployed in the polymer binding matrix. The PSF laminate transducer has electrical inputs/outputs that are delivered through a separate etched interdigital electrode layer. This study analyzed the electromechanical properties with the generalized dilute scheme for active PSF composite laminate by considering multiinclusions. The well-known Mori-Tanaka approach was used to evaluate the concentration tensor in the multi-inclusion micromechanics model. To accurately predict the transverse properties, the extended role of mixtures were applied by considering the inclusions' geometry and shape. The micromechanical finite element modeling was also conducted with representative volume element (RVE) to compare with the micromechanics analysis on the electromechanical properties. The micromechanics analysis and finite element micromechanical modeling were conducted with varied fiber geometry dimensions and volume fractions. These comparison studies indicate the combined micromechanics models with the generalized dilute scheme can effectively predict the electro-elastic properties of multi-inclusion PSF composites.

  2. High-performance silica/silica fiber for endoscopic applications

    Science.gov (United States)

    McCann, Brian P.

    1993-05-01

    Silica-core/silica-clad fibers have become very popular tools for a variety of therapeutic and diagnostic applications. Two types of conventional silica/silica fibers having acrylate and polyimide coatings are reviewed. The properties of dual-waveguide silica/silica fiber are discussed; and the superior bend performance with this design is presented. Silicone/nylon and hard-fluoropolymer/TefzelTM dual-coated fibers are included as the dual-waveguide samples. Sample fibers of each of the four coating types were manufactured into 400/440 micrometers size, 0.22 NA fiber.

  3. Thermal degradation study of silicon carbide threads developed for advanced flexible thermal protection systems

    Science.gov (United States)

    Tran, Huy Kim; Sawko, Paul M.

    1992-01-01

    Silicon carbide (SiC) fiber is a material that may be used in advanced thermal protection systems (TPS) for future aerospace vehicles. SiC fiber's mechanical properties depend greatly on the presence or absence of sizing and its microstructure. In this research, silicon dioxide is found to be present on the surface of the fiber. Electron Spectroscopy for Chemical Analysis (ESCA) and Scanning Electron Microscopy (SEM) show that a thin oxide layer (SiO2) exists on the as-received fibers, and the oxide thickness increases when the fibers are exposed to high temperature. ESCA also reveals no evidence of Si-C bonding on the fiber surface on both as-received and heat treated fibers. The silicon oxide layer is thought to signal the decomposition of SiC bonds and may be partially responsible for the degradation in the breaking strength observed at temperatures above 400 C. The variation in electrical resistivity of the fibers with increasing temperature indicates a transition to a higher band gap material at 350 to 600 C. This is consistent with a decomposition of SiC involving silicon oxide formation.

  4. Preparation of fluorescein-functionalized electrospun fibers coated with TiO{sub 2} and gold nanoparticles for visible-light-induced photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Won Suk [Department of Chemistry, Hannam University, Daejeon 306-791 (Korea, Republic of); Choi, Insung S. [Department of Chemistry, KAIST, Daejeon 305-701 (Korea, Republic of); Lee, Jungkyu K., E-mail: jkl@knu.ac.kr [Molecular-Level Interface Research Center, Department of Chemistry and Green-Nano Research Center, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Yoon, Kuk Ro, E-mail: kryoon@hannam.ac.kr [Department of Chemistry, Hannam University, Daejeon 306-791 (Korea, Republic of)

    2015-08-01

    We demonstrated a new type of visible light-induced photocatalyst, comprising fluorescein molecules, TiO{sub 2}, and gold nanoparticles anchored onto polymer fibers. The synthesized fiber composite was fully characterized by thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, FT-IR spectroscopy, contact angle measurement, and fluorescence microscopy. Under sunlight and visible light irradiation, the photocatalytic activity of the tricomponent system showed 2–3 times greater photodegradation efficiency for methylene blue than a representative photocatalyst, Degussa P25. - Graphical abstract: PSS/PAH-FITC/TiO{sub 2}/AuNP composite demonstrated 2–3 times greater visible light photodegradation efficiency for methylene blue than a representative photocatalyst, Degussa P25. Display Omitted - Highlights: • Synthesis of a novel composite, polymer fiber/organic dye/TiO{sub 2}/gold nanoparticles. • The composite was characterized by TGA, SEM, TEM, and fluorescence microscopy. • Improved visible light photocatalytic activity of the sythesized novel composite.

  5. Single-walled carbon nanotubes coated fibers for solid-phase microextraction and gas chromatography-mass spectrometric determination of pesticides in Tea samples.

    Science.gov (United States)

    Wu, Fang; Lu, Wanping; Chen, Jinghua; Liu, Wei; Zhang, Lan

    2010-08-15

    Using a single-walled carbon nanotubes (SWCNTs) as stationary phase of solid-phase microextraction (SPME) fibers, a simple, low cost and environmentally friendly method for extraction of 13 pesticides in Tea samples has been developed following gas chromatography-mass spectrometric determination. Potential factors affecting the extraction efficiency were investigated and optimized, including extraction and desorption time, extraction temperature, stirring rate, solution pH and ionic strength. Under optimized conditions, the linearity of the developed method was in the range of 0.125-25 ng/mL with correlation coefficients greater than 0.9928 and the limits of detections (LODs) were 0.027-0.23 ng/mL (S/N=3). Meanwhile, the relative standard deviations (RSDs) for five successive measurements with single fiber, fiber-to-fiber, day-to-day were 2.3-13.0, 8.2-14.6 and 4.1-12.5%, respectively, indicating good reproducibility of the proposed method. The fiber had high extraction efficiency for studied pesticides in comparison with commercial poly(dimethylsiloxane) (PDMS) and polyacrylate (PA) fibers and could be used for more than 70 times without decrease of efficiency. The developed method was successfully applied for the analysis of real samples including green Tea, oolong Tea, white Tea, and flower Tea, and the recoveries of the pesticides spiked in these samples ranged from 75.1 to 118.4%. Chlorfenapyr and lambda-cyhalothrin were found in the Tea samples bought randomly from local market. The results demonstrated that the developed SWCNTs-SPME method was a simple, efficient pretreatment and enrichment procedure for pesticides in complex matrices. Copyright 2010 Elsevier B.V. All rights reserved.

  6. High-birefringence photonic crystal fiber polarization filter with gold-coated and liquid-filled air holes based on surface plasmon resonance

    Science.gov (United States)

    Lou, Junbo; Li, Shuguang; Cheng, Tonglei; Yan, Xin; Zhang, Xuenan

    2018-01-01

    A high-birefringence photonic crystal fiber polarization filter is proposed. The coupling theory is used to explain full and incomplete couplings. The resonance point can be adjusted to the communication band by optimizing the fiber structure parameters. Numerical simulation results indicate that the resonance strength can reach 924.96 and 710.28 dB.cm-1 at the communication wavelength of 1.31 and 1.55 μm in x- and y-polarized directions, respectively. By filling liquid analyte, the confinement loss can reach 804.52 dB.cm-1 at the wavelength of 1.55 μm. Furthermore, when the fiber length of L equals 500 μm, the peak value of the cross talk (CT) can reach 389.15 and -280.52 dB, respectively. When the length of the fiber L equals 200 μm, the bandwidth of the CT better than 20 dB is up to 120 nm at the wavelength of 1.31 μm, and the bandwidth of the CT<-20 dB is up to 140 nm at the wavelength of 1.55 μm. These properties make it a good candidate for designing types of polarization filter devices.

  7. Carbides composite surface layers produced by (PTA)

    Energy Technology Data Exchange (ETDEWEB)

    Tajoure, Meloud, E-mail: Tajoore2000@yahoo.com [MechanicalEng.,HIHM,Gharian (Libya); Tajouri, Ali, E-mail: Tajouri-am@yahoo.com, E-mail: dr.mokhtarphd@yahoo.com; Abuzriba, Mokhtar, E-mail: Tajouri-am@yahoo.com, E-mail: dr.mokhtarphd@yahoo.com [Materials and Metallurgical Eng., UOT, Tripoli (Libya); Akreem, Mosbah, E-mail: makreem@yahoo.com [Industrial Research Centre,Tripoli (Libya)

    2013-12-16

    The plasma transferred arc technique was applied to deposit a composite layer of nickel base with tungsten carbide in powder form on to surface of low alloy steel 18G2A type according to polish standard. Results showed that, plasma transferred arc hard facing process was successfully conducted by using Deloro alloy 22 plus tungsten carbide powders. Maximum hardness of 1489 HV and minimum dilution of 8.4 % were achieved by using an arc current of 60 A. However, when the current was further increased to 120 A and the dilution increases with current increase while the hardness decreases. Microstructure of the nickel base deposit with tungsten carbide features uniform distribution of reinforcement particles with regular grain shape half - dissolved in the matrix.

  8. Silicon Carbide Etching Using Chlorine Trifluoride Gas

    Science.gov (United States)

    Habuka, Hitoshi; Oda, Satoko; Fukai, Yasushi; Fukae, Katsuya; Takeuchi, Takashi; Aihara, Masahiko

    2005-03-01

    The etch rate, chemical reactions and etched surface of β-silicon carbide are studied in detail using chlorine trifluoride gas. The etch rate is greater than 10 μm min-1 at 723 K with a flow rate of 0.1 \\ell min-1 at atmospheric pressure in a horizontal reactor. The maximum etch rate at a substrate temperature of 773 K is 40 μm min-1 with a flow rate of 0.25 \\ell min-1. The step-like pattern that initially exists on the β-silicon carbide surface tends to be smoothed; the root-mean-square surface roughness decreases from its initial value of 5 μm to 1 μm within 15 min; this minimum value is maintained for more than 15 min. Therefore, chlorine trifluoride gas is considered to have a large etch rate for β-silicon carbide associated with making a rough surface smooth.

  9. 1976 scientific progress report. [Fuel and coating materials for HTGR]; Wissenschaftlicher Ergebnisberict 1976

    Energy Technology Data Exchange (ETDEWEB)

    Nickel, H.

    1976-07-01

    Activities at the Institute for Reactor Materials in the production and properties of high temperature gas cooled reactor fuel and coating materials are summarized. Major emphasis was placed on investigations of pyrocarbon, BISO and TRISO coatings, uranium and thorium oxides and carbides, and graphite and matrix materials. A list of publications is included. (HDR)

  10. Cryogenic Far-IR Laser Absorptivity Measurements of the Herschel Space Observatory Telescope Mirror Coatings

    NARCIS (Netherlands)

    Fischer, J.; Klaassen, T.O.; Hovenier, J.W.; Jakob, G.; Poglitsch, A.; Sternberg, O.

    2004-01-01

    Far-infrared laser calorimetry was used to measure the absorptivity, and thus the emissivity, of aluminum-coated silicon carbide mirror samples produced during the coating qualification run of the Herschel Space Observatory telescope to be launched by the European Space Agency in 2007. The samples

  11. Novel Base Metal-Palladium Catalytic Diesel Filter Coating with NO2 Reducing Properties

    DEFF Research Database (Denmark)

    Johansen, K.; Dahl, S.; Mogensen, G.

    2007-01-01

    price structure. The novel base metal/palladium catalytic coat has been applied on commercial silicon carbide wall flow diesel filters and tested in an engine test bench. Results from engine bench tests concerning soot combustion, HC-, CO-, NO2- removal with the novel coat will are compared to present...

  12. Silicon carbide microsystems for harsh environments

    CERN Document Server

    Wijesundara, Muthu B J

    2011-01-01

    Silicon Carbide Microsystems for Harsh Environments reviews state-of-the-art Silicon Carbide (SiC) technologies that, when combined, create microsystems capable of surviving in harsh environments, technological readiness of the system components, key issues when integrating these components into systems, and other hurdles in harsh environment operation. The authors use the SiC technology platform suite the model platform for developing harsh environment microsystems and then detail the current status of the specific individual technologies (electronics, MEMS, packaging). Additionally, methods

  13. A comparison study on a sulfonated graphene-polyaniline nanocomposite coated fiber for analysis of nicotine in solid samples through the traditional and vacuum-assisted HS-SPME.

    Science.gov (United States)

    Ghiasvand, Alireza; Koonani, Samira; Yazdankhah, Fatemeh; Farhadi, Saeid

    2017-11-06

    A simple, rapid, and reliable headspace solid-phase microextraction (HS-SPME) procedure, reinforced by applying vacuum in the extraction vial, was developed. It was applied for the extraction of nicotine in solid samples prior to determination by gas chromatography-flame ionization detection (GC-FID). First, the surface of a narrow stainless steel wire was made porous and adhesive by platinization to obtain a durable, higher surface area, and resistant fiber. Then, a thin film of sulfonated graphene/polyaniline (Sulf-G/PANI) nanocomposite was synthesized and simultaneously coated on the platinized fiber using the electrophoretic deposition (EPD) method. It was demonstrated that the extraction efficiency remarkably increased by applying the reduced-pressure condition in the extraction vial. To evaluate the conventional HS-SPME and vacuum-assisted HS-SPME (VA-HS-SPME) platforms, all experimental parameters affecting the extraction efficiency including desorption time and temperature, extraction time and temperature and moisture content of sample matrix were optimized. The highest extraction efficiency was obtained at 60°C, 10min (extraction temperature and time) and 280°C, 2min (desorption condition), for VA-HS-SPME strategy, while for conventional HS-SPME the extraction and desorption conditions found to be 100°C, 30min and 280°C, 2min, respectively. The Sulf-G/PANI coated fiber showed high thermal stability, good chemical/mechanical resistance, and long lifetime. For analysis of nicotine in solid samples using VA-HS-SPME-GC-FID, linear dynamic range (LDR) was 0.01-30μgg(-1) (R(2)=0.996), the relative standard deviation (RSD%, n=6), for analyses of 1μgg(-1) nicotine was calculated 3.4% and limit of detection (LOD) found to be 0.002μgg(-1). The VA-HS-SPME-GC-FID strategy was successfully carried out for quantitation of nicotine in hair and tobacco real samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. for zeolite coating

    Directory of Open Access Journals (Sweden)

    Carlos Renato Rambo

    2006-01-01

    Full Text Available Biotemplating is the processing of microcellular ceramics by reproduction of natural morphologies, where the microstructural features of the biotemplate are maintained in the biomorphic ceramic. Different biotemplates with distinct pore anatomies were used to produce biomorphic supports for the zeolite coating: wood, cardboard, sea-sponge and sisal. The biomorphic ceramics were produced by distinguished processing routes: Al-gas infiltration-reaction, liquid-metal infiltration, dip-coating and sol-gel synthesis, in order to produce nitrides, carbides and oxides, depending on the processing conditions. The zeolite coating was performed by hydrothermal growth of MFI-type (Silicalite-1 and ZSM-5 zeolite crystals onto the internal pore walls of the biomorphic templates. The final biomorphic ceramic-zeolite composites were physically characterized, evaluated in terms of their gas adsorption capabilities and correlated to their microstructure and specific pore anatomy. The combination of the properties of the biomorphic ceramics with the adsorption properties of zeolites results in materials with distinct properties as potential candidates for adsorption and catalytic applications due to their characteristic porosity, molecular sieving capabilities and high thermo-mechanical strength.

  15. Synthesis and Analysis of Alpha Silicon Carbide Components for Encapsulation of Fuel Rods and Pellets

    Energy Technology Data Exchange (ETDEWEB)

    Kevin M. McHugh; John E. Garnier; George W. Griffith

    2011-09-01

    The chemical, mechanical and thermal properties of silicon carbide (SiC) along with its low neutron activation and stability in a radiation field make it an attractive material for encapsulating fuel rods and fuel pellets. The alpha phase (6H) is particularly stable. Unfortunately, it requires very high temperature processing and is not readily available in fibers or near-net shapes. This paper describes an investigation to fabricate a-SiC as thin films, fibers and near-net-shape products by direct conversion of carbon using silicon monoxide vapor at temperatures less than 1700 C. In addition, experiments to nucleate the alpha phase during pyrolysis of polysilazane, are also described. Structure and composition were characterized using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Preliminary tensile property analysis of fibers was also performed.

  16. Optical Fiber Embedded in Epoxy Glass Unidirectional Fiber Composite System.

    Science.gov (United States)

    Severin, Irina; El Abdi, Rochdi; Corvec, Guillaume; Caramihai, Mihai

    2013-12-20

    We aimed to embed silica optical fibers in composites (epoxy vinyl ester matrix reinforced with E-glass unidirectional fibers in mass fraction of 60%) in order to further monitor the robustness of civil engineering structures (such as bridges). A simple system was implemented using two different silica optical fibers (F1-double coating of 172 µm diameter and F2-single coating of 101.8 µm diameter respectively). The optical fibers were dynamically tensile tested and Weibull plots were traced. Interfacial adhesion stress was determined using pull-out test and stress values were correlated to fracture mechanisms based on SEM observations. In the case of the optical fiber (OF) (F1)/resin system and OF (F1)/composite system, poor adhesion was reported that may be correlated to interface fracture at silica core level. Relevant applicable results were determined for OF (F2)/composite system.

  17. Structure and Abrasive Wear of Composite HSS M2/WC Coating

    Directory of Open Access Journals (Sweden)

    S. F. Gnyusov

    2012-01-01

    Full Text Available Features of phase-structure formation and abrasive wear resistance of composite coatings “WC-M2 steel” worn against tungsten monocarbide have been investigated. It was established that adding 20 wt.% WC to the deposited powder mixture leads to the increase in M6C carbide content. These carbides show a multimodal size distribution consisting of ~5.9 μm eutectic carbides along the grain boundaries, ~0.25 μm carbides dispersed inside the