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Sample records for electrolytic oxidation coatings

  1. Mixed alumina and cobalt containing plasma electrolytic oxide coatings

    Science.gov (United States)

    Yar-Mukhamedova, G. Sh; Ved', M. V.; Karakurkchi, A. V.; Sakhnenko, N. D.

    2017-06-01

    Principles of plasma electrolytic oxidation of the AL25 aluminum alloy in diphosphate alkali solutions containing cobalt(2+) cations are discussed. It has been established that a variation in the concentration of the electrolyte components provides the formation of mixed-oxide coatings consisting of the basic matrix materials and the cobalt oxides of different content. An increase in the cobalt oxide content in the coating is achieved by the variation in electrolysis current density as well as the treatment time due to both the electrochemical and thermo-chemical reactions at substrate surface and in spark region. Current density intervals that provide micro-globular surface formation and uniform cobalt distribution in the coating are determined. The composition and morphology of the surface causes high catalytic properties of synthesized materials, which confirmed the results of testing in model reaction CO and benzene oxidation as well as fuel combustion for various modes of engine operation.

  2. Photoactive TiO{sub 2} coatings obtained by Plasma Electrolytic Oxidation in refrigerated electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Franz, Silvia, E-mail: silvia.franz@polimi.it; Perego, Daniele; Marchese, Ottavia; Lucotti, Andrea; Bestetti, Massimiliano

    2016-11-01

    Highlights: • Submicrometric TiO{sub 2} coatings by Plasma Electrolytic Oxidation. • TiO{sub 2} high photoactivity in the UV range. • Low temperature oxidation. • Short processing times with respect to traditional anodic oxidation. - Abstract: The effect of synthesis conditions on the properties of nanoporous TiO{sub 2} coatings obtained by PEO in refrigerated electrolytes have been investigated. Linear sweep voltammetry was carried out on the TiO{sub 2} coatings, in dark and under UV-C irradiation, in order to assess the photoelectrochemical behavior of samples. The largest photocurrents (0.18 mA/cm{sup 2}) were measured on TiO{sub 2} coatings obtained by PEO in refrigerated aqueous solutions. UV–vis spectra revealed that lowering the processing temperature from 20 to −3.5 °C induced a blue-shift of the absorption band of the TiO{sub 2} coatings from 3.05 to 3.42 eV. The main advantage of PEO in refrigerated aqueous solutions over current approaches, based on anodic oxidation and thermal treatments, is that the synthesis of photoactive TiO{sub 2} coatings can be carried out in a relatively easy, quick and reproducible way, without annealing pre- and post-treatments. Furthermore, by controlling the solution temperature in PEO process, the photocurrent of the resulting TiO{sub 2} coating reaches quite high values.

  3. Plasma electrolytic oxide coatings on silumin for oxidation CO

    Science.gov (United States)

    Borisov, V. A.; Sigaeva, S. S.; Anoshkina, E. A.; Ivanov, A. L.; Litvinov, P. V.; Vedruchenko, V. R.; Temerev, V. L.; Arbuzov, A. B.; Kuznetsov, A. A.; Mukhin, V. A.; Suprunov, G. I.; Chumychko, I. A.; Shlyapin, D. A.; Tsyrul'nikov, P. G.

    2017-08-01

    Some catalysts of CO oxidation on silumin alloy AK12M2, used for the manufacture of pistons for Russian cars were investigated. The catalysts were prepared by the method of plasma electrolytic oxidation of silumin in electrolytes of various compositions with further activation by the salts Ce, Cu, Co, Ni, Mn and Al. The catalytic tests were carried out in a flow reactor in a mixture of 1% CO and 99% air, with the temperature range of 25-500 °C. The most active catalysts in CO oxidation are those activated with Ce and Cu salts on silumin, treated for 3 hours in an electrolyte containing 4 g/l KOH, 40 g/l Na2B4O7 (conversion of CO is 93.7% at a contact time of 0.25 s). However, the catalysts obtained from silumin treated in the electrolyte containing 3 g/l KOH, 30 g/l Na2SiO3 are more suitable for practical usage. Because when the treatment time of those catalysts is 10 - 20 minutes it is possible to achieve comparable CO conversion. The morphology and composition of the catalysts were studied by the methods of a scanning electron microscope with energy-dispersive surface analysis and X-ray phase analysis. The surface of the non-activated sample consists of γ-Al2O3 and SiO2 particles, due to which the active components get attached to the support. CeO2 and CuO are present on the surface of the sample with the active component.

  4. Characterization of plasma electrolytic oxidation coatings on Zircaloy-4 formed in different electrolytes with AC current regime

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    Cheng Yingliang, E-mail: chengyingliang@hnu.edu.cn [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Matykina, Enzhe [Dpt. Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Madrid 28040 (Spain); Skeldon, Peter; Thompson, George [Corrosion and Protection Centre, School of Materials, University of Manchester, Sackville Street, Manchester M13 9PL (United Kingdom)

    2011-10-01

    Highlights: > ZrO{sub 2} coatings are grown on Zircaloy-4 by AC plasma electrolytic oxidation. > Tetragonal and monoclinic ZrO{sub 2} are formed using silicate electrolyte. > Pyrophosphate electrolyte results in flawed coatings of monoclinic ZrO{sub 2}. > Silicate favours formation of tetragonal ZrO{sub 2}, with coating hardness {approx}8 GPa. > Microstructures are related to temperature gradients and solidification rates. - Abstract: Plasma electrolytic oxidation was undertaken on Zircaloy-4 in alkaline silicate and pyrophosphate electrolytes, with a square waveform AC current regime. The resultant coatings were examined using scanning electron spectroscopy, X-ray diffraction and nanoindentation. The coatings formed in silicate electrolyte comprised mainly a porous inner layer and a more compact outer layer, with characteristic solidification structures being evident following prolonged treatment. The coatings contained monoclinic and tetragonal ZrO{sub 2}, the latter being mainly present in the outer layer, which was of hardness up to {approx}8 GPa. In contrast, extensively cracked coatings resulted from use of pyrophosphate electrolyte; the coating integrity was improved by the addition of silicate to the pyrophosphate electrolyte. The different morphologies of the coatings appeared to be related to the differing nature of the microdischarges and to the incorporation of silicon species that enhanced the formation of t-ZrO{sub 2}.

  5. Plasma electrolytic oxidation of titanium in a phosphate/silicate electrolyte and tribological performance of the coatings

    Energy Technology Data Exchange (ETDEWEB)

    Aliasghari, S.; Skeldon, P., E-mail: p.skeldon@manchester.ac.uk; Thompson, G.E.

    2014-10-15

    Highlights: • Plasma electrolytic oxidation performed of titanium in silicate/phosphate electrolyte. • Range of duty cycle, current density, positive-to-negative current ratio studied. • Coatings contain anatase, rutile, Ti{sub 3}O{sub 5}, and amorphous silica. • Ptfe incorporated into coatings by addition of ptfe emulsion to the electrolyte. • Fiction reduced but wear life relatively short due to porosity of coatings. - Abstract: Plasma electrolytic oxidation of titanium has been investigated using a phosphate/silicate electrolyte with a square waveform and a frequency of 50 Hz. A range of constant rms current densities, duty cycles and negative-to-positive current ratios was employed. The resultant coatings were examined by analytical scanning and transmission electron microscopies and X-ray diffraction. The coatings, which were limited in thickness to ∼40 to 50 μm, contained anatase, rutile, Ti{sub 2}O{sub 5} and silicon-rich, amorphous material. The tribological behaviour was investigated using a ball-on-disc test, revealing a coefficient of friction against steel of ∼0.8, which reduced to ∼0.4 by incorporation of ptfe particles from the electrolyte. However, due to the composition and morphology of the coatings, their wear life was relatively short.

  6. Factors Influencing Plasma Electrolytic Oxidation(PEO) Coatings on Magnesium Alloys: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Gunchoo [KISTI ReSEAT Program, Daejon (Korea, Republic of)

    2017-05-15

    Magnesium alloys, which possess excellent specific strength and castability, are highly susceptible to corrosion. Although anodizing is widely used to resolve this problem, it requires toxic electrolytes and produces relatively thin and weak surface coatings. Recently, plasma electrolytic oxidation (PEO) has emerged as an alternative to anodizing. Although it is derived from conventional anodizing, it uses eco-friendly electrolytes and forms thicker, denser, and harder coatings on the surface of magnesium alloys. However, PEO is a complex process involving physical, chemical, and electrochemical reactions, and it is influenced by various factors such as the alloy substrate composition, electrolyte/additive composition, and the electrical variables including the mode of power supply, applied voltage/current density, frequency, and duty cycle. In this article, the detailed effects of these parameters on the microstructure and properties of the PEO coatings are reviewed, and methods of improving the coatings are proposed.

  7. Mg-containing hydroxyapatite coatings produced by plasma electrolytic oxidation of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, Cesar Augusto; Rangel, Elidiane Cipriano; Durrant, Steven Frederick; Cruz, Nilson Cristino da, E-mail: cesar.augustoa@hotmail.com [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sorocaba, SP (Brazil). Lab. de Plasmas Tecnologicos; Delgado-Silva, Adriana de Oliveira [Universidade Federal de Sao Carlos (UFSCar), Sorocaba, SP (Brazil); Tabacniks, Manfredo H. [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Fisica

    2017-07-15

    Plasma Electrolytic Oxidation (PEO) is promising for the processing of biomaterials because it enables the production of surfaces with adjustable composition and structure. In this work, aimed at the improvement of the bioactivity of titanium, PEO has been used to grow calcium phosphide coatings on titanium substrates. The effects of the addition of magnesium acetate to the electrolytes on the composition of the coatings produced during 120 s on Ti disks using bipolar voltage pulses and solutions of calcium and magnesium acetates and sodium glycerophosphate as electrolytes have been studied. Scanning electron microscopy, X-ray energy dispersive spectroscopy, Rutherford backscattering spectroscopy, X-ray diffractometry with Rietveld refinement and profilometry were used to characterize the modified samples. Coatings composed of nearly 50 % of Mg-doped hydroxyapatite have been produced. In certain conditions up to 4% Mg can be incorporated into the coating without any observable significant structural modifications of the hydroxyapatite. (author)

  8. Preparation and Characterization of Plasma Electrolytic Oxidation Coating on 5005 Aluminum Alloy with Red Mud as an Electrolyte Additive

    Science.gov (United States)

    Liu, Shifeng; Zeng, Jianmin; Wang, Youbin

    2017-10-01

    A coating with red mud as an electrolyte additive was applied to 5005 aluminum alloy using plasma electrolytic oxidation (PEO). The phase composition of the coating was investigated using X-ray diffraction. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) was used to determine the microstructure and composition profiles of the coating. The coating/substrate adhesion was determined by scratch testing. The corrosion behaviors of the substrate and coating were evaluated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The results indicated that the PEO coating with red mud consisted mainly of α-Al2O3 and γ-Al2O3, with small amounts of Fe2O3, CaCO3, and CaTiO3. The surface of the coating was the color of the red mud. The coating had a uniform thickness of about 80 μm and consisted of two main layers: a 6- μm porous outer layer and a 74- μm dense inner layer, which showed typical metallurgical adhesion (coating/substrate adhesion strength of 59 N). The coating hardness was about 1142 HV, much higher than that of the substrate (60 HV). The corrosion potential E corr and corrosion current density i corr of the coating were estimated to be -0.743 V and 3.85 × 10-6 A cm-2 from the PDP curve in 3.5 wt pct NaCl solution, and the maximum impedance and phase angle of the coating were 11 000 Ω and -67 deg, respectively, based on EIS. PEO coating with red mud improved the surface properties and corrosion resistance of 5005 aluminum alloy. This study also shows a potential method for reusing red mud.

  9. Ceramic coatings of LA141 alloy formed by plasma electrolytic oxidation for corrosion protection.

    Science.gov (United States)

    Li, Zhijun; Yuan, Yi; Sun, Pengpeng; Jing, Xiaoyan

    2011-09-01

    Superlight Mg-Li alloy is a promising structural materials in aerospace, automobile, and electronics because of its excellent properties such as low density, high ductility, superior strength-to-weight ratio, and good damping ability. The fabrication of compact plasma electrolytic oxidation coatings with excellent corrosion resistance is valuable for the widespread application of Mg-Li alloy. Here we present a ceramic coating on the surface of Mg-14Li-1Al (LA141) alloy for corrosion protection via plasma electrolytic oxidation (PEO) in an alkaline silicate electrolyte with tungstate as an additive. X-ray photoelectron spectroscopy and thin film-X-ray diffraction analysis of coatings show that the surface coating is mainly comprised of Mg(2)SiO(4), MgO and WO(3). Scanning electron microscopy observations have revealed that the dense and compact coating formed in the presence of tungstate has less structural imperfections in comparison to the control one fabricated without use of tungstate. The effect of oxidation time on the morphology and phase composition of coatings is also examined in detail.

  10. Growth kinetics and morphology of plasma electrolytic oxidation coating on aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Erfanifar, Eliyas; Aliofkhazraei, Mahmood, E-mail: maliofkh@gmail.com; Fakhr Nabavi, Houman; Sharifi, Hossein; Rouhaghdam, Alireza Sabour

    2017-01-01

    Plasma electrolytic oxidation (PEO) was carried out on AA1190 aluminum alloy in mixed silicate-phosphate-based electrolyte in order to fabricate ceramic coating under constant current density. The variations of PEO coating duration with kinetics, surface roughness, amount and size of discharge channels were studied with respect to PEO processing time. The growth mechanism of the ceramic coating was described considering a variation of volume and diameters of discharge channels and pancakes during the PEO. Scanning electron microscope (SEM), atomic force microscope (AFM), and roughness tester were used to study the plasma discharge channels of the PEO coatings. In addition, the effect of alumina nanoparticles in the electrolyte as the suspension was studied on the geometric parameters of discharge channels. It seems that the nanoparticles are adsorbed to the locations of erupted molten oxide, where the dielectric breakdown occurs. Nanoparticles were embedded in the dense oxide layer and were adsorbed at the walls of voids and coatings surface. As a result, they caused significant changes in roughness parameters of the samples containing nanoparticles compared to those without nanoparticles. The obtained results showed that growth kinetics followed a linear trend with respect to PEO coating duration. It was also observed that in the absence of alumina nanoparticles, the average volume of the pancakes is 150% greater than the ones fabricated in the suspension of nanoparticles. Besides, increasing the PEO coating duration leads to adsorbing more nanoparticles on the coating surface, filling the voids, and flattening the surface, and alterations in R{sub v}, R{sub sk}, and R{sub lo} parameters. Correlation between the diameter of discharge channel (d{sub c}) and thickness of the pancake (h) also showed a linear relation. - Highlights: • Precise calculation of thickness of pancake with AFM. • Study of different roughness parameters for PEO coating. • Calculation

  11. Wettability and Corrosion Behavior of Chemically Modified Plasma Electrolytic Oxidation Nanocomposite Coating

    Science.gov (United States)

    Farhadi, S. S.; Aliofkhazraei, M.; Barati Darband, Gh.; Abolhasani, A.; Sabour Rouhaghdam, A.

    2017-10-01

    The aim of this paper was to investigate the effect of potassium stearate on the wettability behavior, corrosion resistance, roughness and thickness of reinforced and unreinforced plasma electrolytic oxidation (PEO) coatings with Si3N4 nanopowders. Morphological characteristic, corrosion behavior and wetting properties of the coatings were evaluated using SEM, cyclic polarization and Wilhelmy plate method, respectively. In order to obtain a better evaluation of the contact angle, roughness of the coatings was studied by AFM. The results indicated that the nanocomposite hydrophobic coatings have the best corrosion resistance. Potassium stearate could repel water from the holes of coating by reacting with aluminum and producing aluminum stearate. The contact angle of nanocomposite and normal PEO coatings was increased up to 65° due to the addition of potassium stearate. This additive could also increase the hysteresis contact angle up to 51°.

  12. An Investigation of Oxide Coating Synthesized on an Aluminum Alloy by Plasma Electrolytic Oxidation in Molten Salt

    Directory of Open Access Journals (Sweden)

    Alexander Sobolev

    2017-08-01

    Full Text Available Plasma electrolytic oxidation (PEO is a surface treatment process for obtaining oxide coatings with a high performance on valve metals. PEO is mostly performed in an aqueous solution electrolyte that limits the size of treated parts due to the fact that the system is heated. Therefore, the coating of large surfaces cannot be synthesized in an aqueous electrolyte. In the current work, an alternative approach of PEO treatment, whereby an aluminum 1050 alloy in nitrate molten salt at a temperature of 280 °C is applied, was investigated. The microstructure, phase and chemical compositions, and micro-hardness were examined using X-ray diffraction (XRD, scanning electron microscopy (SEM, energy-dispersive X-ray spectroscopy (EDS, and micro-hardness tests. The obtained results show that formed coating contains from two sub-layers: one is the outer sub-layer of the α-Al2O3 phase and the second is its inner sub-layer. It was found that the formed coating was free of any contaminants originating from the electrolyte and had no cracks or pores, which are usually present in coatings formed by PEO treatment in an aqueous solution electrolyte.

  13. Corrosion and nanomechanical behaviors of plasma electrolytic oxidation coated AA7020-T6 aluminum alloy

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    Venugopal, A., E-mail: arjun_venu@hotmail.com [Materials and Metallurgy Group, Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Thiruvananthapuram (India); Srinath, J. [Materials and Metallurgy Group, Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Thiruvananthapuram (India); Rama Krishna, L. [International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur P.O., Hyderabad 500005 (India); Ramesh Narayanan, P.; Sharma, S.C.; Venkitakrishnan, P.V. [Materials and Metallurgy Group, Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Thiruvananthapuram (India)

    2016-04-13

    Alumina coating was deposited on AA7020 aluminum alloy by plasma electrolytic oxidation (PEO) method. The corrosion, stress corrosion cracking (SCC) and nano-mechanical behaviors were examined by means of potentiodynamic polarization, slow strain rate test (SSRT) and nano-indentation tests. Potentiodynamic polarization (PP) was used to evaluate the corrosion resistance of the coating and slow strain rate test (SSRT) was used for evaluating the environmental cracking resistance in 3.5% NaCl solution. The mechanical properties (hardness and elastic modulus) were obtained from each indentation as a function of the penetration depth across the coating cross section. The above results were compared with similar PEO coated aluminum and magnesium alloys. Results indicated that PEO coating on AA7020 alloy significantly improved the corrosion resistance. However the environmental cracking resistance was found to be only marginal. The hardness and elastic modulus values were found to be much higher when compared to the base metal and similar PEO coated 7075 aluminum alloys. The fabricated coating also exhibited good adhesive strength with the substrate similar to other PEO coated aluminum alloys reported in the literature.

  14. Characterization and formation of hydroxyapatite on Ti6Al4V coated by plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Durdu, Salih; Deniz, Oemer Faruk; Kutbay, Is Latin-Small-Letter-Dotless-I l [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, Kocaeli 41400 (Turkey); Usta, Metin, E-mail: ustam@gyte.edu.tr [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, Kocaeli 41400 (Turkey)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer Ti6Al4V alloys were coated by PEO in calcium acetate and {beta}-calcium glycerophosphate. Black-Right-Pointing-Pointer Hydroxyapatite and calcium apatite based phases were directly formed on Ti6Al4V. Black-Right-Pointing-Pointer Hydroxyapatite coatings were characterized systematically for different times. Black-Right-Pointing-Pointer After 5 min, hydroxyapatite and calcium based phases begin to form on the coating. Black-Right-Pointing-Pointer HAp on the coating is amorphous due to the rapid solidification during PEO. - Abstract: In this study, Ti6Al4V alloy was coated in the solution consisting of calcium acetate (CA) and {beta}-calcium glycerophosphate ({beta}-Ca-GP) by plasma electrolytic oxidation (PEO) to produce hydroxyapatite and calcium apatite-based composite used as of bioactive and biocompatible materials in biomedical applications. The phase structures, surface morphologies, functional groups of molecules, chemical compositions of the surfaces and the binding energies of atoms in the coating were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. Anatase, rutile, calcium oxide, titanium phosphide, whitlockite, tri-calcium phosphate (TCP), perovskite calcium titanate and hydroxyapatite phases on the coating were detected by XRD analysis. The surface of coatings produced by PEO method has a porous structure. The amount of amorphous hydroxyapatite is the highest value for the coating produced at 5 min in XPS and ATR-FTIR results, whereas the amount of crystalline hydroxyapatite has the highest value for coating produced at 120 min in XRD results.

  15. Spin coating of electrolytes

    Science.gov (United States)

    Stetter, Joseph R.; Maclay, G. Jordan

    1989-01-01

    Methods for spin coating electrolytic materials onto substrates are disclosed. More particularly, methods for depositing solid coatings of ion-conducting material onto planar substrates and onto electrodes are disclosed. These spin coating methods are employed to fabricate electrochemical sensors for use in measuring, detecting and quantifying gases and liquids.

  16. Optimization of spin-coated electrodes for electrolyte-supported solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Nobrega, Shayenne Diniz da; Monteiro, Natalia Kondo; Tabuti, Francisco; Fonseca, Fabio Coral, E-mail: shaynnedn@hotmail.com, E-mail: nataliakm@usp.br, E-mail: fntabuti@ipen.br, E-mail: fabiocf@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil); Florio, Daniel Zanetti de, E-mail: daniel.florio@ufabc.edu.br [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2017-01-15

    Electrodes for electrolyte-supported solid oxide fuel cells (SOFC’s) were fabricated by spin coating. Strontium-doped lanthanum manganite (LSM) cathode and nickel yttria-stabilized zirconia cermet anodes were synthesized and processed for enhanced deposition conditions. The influence of electrode microstructural parameters was investigated by a systematic experimental procedure aiming at optimized electrochemical performance of single cells. Polarization curves showed a strong dependence on both electrode thickness and sintering temperature. By a systematic control of such parameters, the performance of single cells was significantly enhanced due to decreasing of polarization resistance from 26 Ω cm² to 0.6 Ω cm² at 800°C. The results showed that spin-coated electrodes can be optimized for fast and cost effective fabrication of SOFCs. (author)

  17. Cell adhesion to plasma electrolytic oxidation (PEO) titania coatings, assessed using a centrifuging technique.

    Science.gov (United States)

    Robinson, H J; Markaki, A E; Collier, C A; Clyne, T W

    2011-11-01

    The adhesion of bovine chondrocytes and human osteoblasts to three titania-based coatings, formed by plasma electrolytic oxidation (PEO), was compared to that on uncoated Ti-6Al-4V substrates, and some comparisons were also made with plasma sprayed hydroxyapatite (HA) coatings. This was done using a centrifuge, with accelerations of up to 160,000 g, so as to induce buoyancy forces that created normal or shear stresses at the interface. It is shown that, on all surfaces, it was easier to remove cells under normal loading than under shear loading. Cell adhesion to the PEO coatings was stronger than that on Ti-6Al-4V and similar to that on HA. Cell proliferation rates were relatively high on one of the PEO coatings, which was virtually free of aluminium, but low on the other two, which contained significant levels of aluminium. It is concluded that the Al-free PEO coating offers promise for application to prosthetic implants. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Preparation and corrosion resistance of a nanocomposite plasma electrolytic oxidation coating on Mg-1%Ca alloy formed in aluminate electrolyte containing titania nano-additives

    DEFF Research Database (Denmark)

    Daroonparvar, Mohammadreza; Yajid, M. A. M.; Yusof, N. M.

    2016-01-01

    Titania nanoparticles were utilized as suspension in alkaline aluminate electrolyte to form nanocomposite coatings on magnesium alloy containing 1 wt% calcium by plasma electrolytic oxidation process. Microhardness, wettability, potentiodynamic polarization, wettability, electrochemical impedance...... spectroscopy (EIS), and immersion tests were performed in 3.5% NaCl solution to study corrosion behavior of the coated samples in reference to the uncoated Mg alloy. The coating with 4 g/L concentration of nanoparticles showed the highest microhardness, lowest hydrophilic properties and highest corrosion...... resistance. This coating substantially diminishes the Mg dissolution in the in 3.5% NaCl solution and increases the charge transfer resistance of the Mg alloy. Although higher concentrations of nanoparticles enhanced the defect density in the coating, they resulted in lower corrosion resistance. © 2016...

  19. XPS and GDOES Characterization of Porous Coating Enriched with Copper and Calcium Obtained on Tantalum via Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Krzysztof Rokosz

    2016-01-01

    Full Text Available XPS and GDOES characterizations of porous coatings on tantalum after Plasma Electrolytic Oxidation (PEO at 450 V for 3 minutes in electrolyte containing concentrated (85% phosphoric acid with calcium nitrate and copper (II nitrate are described. Based on the obtained data, it may be concluded that the PEO coating consists of tantalum (Ta5+, calcium (Ca2+, copper (Cu2+  and Cu+, and phosphates (PO43-. It has to be pointed out that copper and calcium are distributed throughout the volume. The authors also propose a new model of PEO, based on the derivative of GDOES signals with sputtering time.

  20. The black and white coatings on Ti-6Al-4V alloy or pure titanium by plasma electrolytic oxidation in concentrated silicate electrolyte

    Science.gov (United States)

    Han, Jun-xiang; Cheng, Yu-lin; Tu, Wen-bin; Zhan, Ting-Yan; Cheng, Ying-liang

    2018-01-01

    Black TiO2 has triggered scientific interest due to its unique properties such as enhanced solar-driven photocatalytic activity. In this paper, plasma electrolytic oxidation (PEO) treatment of Ti-6Al-4V alloy has been carried out in concentrated sodium silicate electrolyte. Silica-based black and white TiO2 coatings respectively have been obtained by controlling the oxidation time. The black coating, which was formed with a short treatment time, shows good corrosion resistance and the black appearance can be attributed to the presence of Ti2+ and Ti3+ in the coating. The lower valence titanium ions are absent in the white coatings and they also contain relatively higher Na content compared to the black coatings. The white coatings have great surface roughnesses and super hydrophilicity. The bonding strengths of the black and white coatings on the Ti-6Al-4V alloy are ∼14.4 and 4.3 MPa, respectively. The vanadium contributes little to the black appearance of the coating on Ti6Al4V alloy, since the same phenomena occur for the PEO of a pure titanium substrate.

  1. Hydroxyapatite coatings containing Zn and Si on Ti-6Al-4Valloy by plasma electrolytic oxidation

    Science.gov (United States)

    Hwang, In-Jo; Choe, Han-Cheol

    2018-02-01

    In this study, hydroxyapatite coatings containing Zn and Si on Ti-6Al-4Valloy by plasma electrolytic oxidation were researched using various experimental instruments. The pore size is depended on the electrolyte concentration and the particle size and number of pore increase on surface part and pore part. In the case of Zn/Si sample, pore size was larger than that of Zn samples. The maximum size of pores decreased and minimum size of pores increased up to 10Zn/Si and Zn and Si affect the formation of pore shapes. As Zn ion concentration increases, the size of the particle tends to increase, the number of particles on the surface part is reduced, whereas the size of the particles and the number of particles on pore part increased. Zn is mainly detected at pore part, and Si is mainly detected at surface part. The crystallite size of anatase increased as the Zn ion concentration, whereas, in the case of Si ion added, crystallite size of anatase decreased.

  2. Plasma electrolytic oxidation of tantalum

    Directory of Open Access Journals (Sweden)

    Petković Marija

    2012-01-01

    Full Text Available This paper is a review of our research on the plasma electrolytic oxidation (PEO process of tantalum in 12-tungstosilicic acid. For the characterization of microdischarges during PEO, real-time imaging and optical emission spectroscopy (OES were used. The surface morphology, chemical and phase composition of oxide coatings were investigated by AFM, SEM-EDS and XRD. Oxide coating morphology is strongly dependent on PEO time. The elemental components of PEO coatings are Ta, O, Si and W. The oxide coatings are partly crystallized and mainly composed of WO3, Ta2O5 and SiO2.

  3. Formation of Ca/P ceramic coatings by Plasma Electrolytic Oxidation (PEO) on Ti6Al4V ELI alloy

    Science.gov (United States)

    Rodriguez-Jaimes, Y.; Naranjo, D. I.; Blanco, S.; García-Vergara, S. J.

    2017-12-01

    The formation of PEO ceramic coatings on Ti6Al4V ELI alloy was investigated using a phosphate/calcium containing electrolyte at 300 and 400V at 310K for different times. The Plasma Electrolytic Oxidation (PEO) coated specimens were then heat treated at 873 and 1073K for 2 hours. Scanning electron microscopy, Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray diffraction analysis were used to study the composition and the morphology of the ceramic coatings. The corrosion behaviour of the coatings was studied by Electrochemical Impedance Spectroscopy (EIS) in Simulated Body Fluid (SBF). The PEO-treated specimens primarily revealed a porous structure with thickness between 4 and 12μm, according to the voltage and process time used. The coatings are mainly composed of hydroxyapatite; however, as the voltage and anodizing time increase, the Ca/P ratio decreases. Generally, the corrosion resistance of the alloy was improved by the PEO-treated coatings, although the specimens treated at 1073K showed the presence of cracks that reduced the protective effect of the coatings.

  4. Evolution processes of the corrosion behavior and structural characteristics of plasma electrolytic oxidation coatings on AZ31 magnesium alloy

    Science.gov (United States)

    Chen, Dong; Wang, Ruiqiang; Huang, Zhiquan; Wu, Yekang; Zhang, Yi; Wu, Guorui; Li, Dalong; Guo, Changhong; Jiang, Guirong; Yu, Shengxue; Shen, Dejiu; Nash, Philip

    2018-03-01

    Evolution processes of the corrosion behavior and structural characteristics of the plasma electrolytic oxidation (PEO) coated AZ31 magnesium alloy were investigated by using scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), potentio-dynamic polarization curves and electrochemical impedance spectroscopy (EIS) measurements. Detached coating samples were fabricated by an electrochemical method and more details of the internal micro-structure of coatings were clearly observed on the fractured cross-section morphologies of the samples compared to general polished cross-section morphologies. Evolution mechanisms of the coating corrosion behavior in relation to the evolution of micro-structural characteristics were discussed in detail.

  5. Tetragonal ZrO2 phase stabilization in coating layers prepared on Zr-2.5%Nb alloy during plasma electrolytic oxidation in sodium aluminate electrolytes

    Science.gov (United States)

    Malinovschi, V.; Marin, A.; Negrea, D.; Andrei, V.; Coaca, E.

    2017-09-01

    Layers containing polycrystalline zirconia and amorphous aluminum oxide were obtained by plasma electrolytic oxidation (PEO) of Zr-2.5%Nb alloy in aqueous electrolyte solutions comprising NaAlO2 (pH  =  13.0), NaAlO2 and NaOH (pH  =  13.2), respectively. The PEO coatings were analyzed by x-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and potentiodynamic polarization tests. The deposited coating layers contain mainly tetragonal ZrO2 polycrystalline phase and amorphous aluminum oxide (Al2O3) phase. They have thicknesses between 9.0 and 53.0 µm and are uneven, heterogeneous and porous. Zirconia tetragonal phase stabilization by the aluminum oxide matrix was achieved through the ‘constraint’ mechanism. The corrosion current density values for the PEO layers are lower by 1-2 orders of magnitude than those of the untreated Zr-2.5%Nb alloy.

  6. Fabrication of Coatings on the Surface of Magnesium Alloy by Plasma Electrolytic Oxidation Using ZrO2 and SiO2 Nanoparticles

    Directory of Open Access Journals (Sweden)

    S. V. Gnedenkov

    2015-01-01

    Full Text Available Results of investigation of the incorporation of zirconia and silica nanoparticles into the coatings formed on magnesium alloy by plasma electrolytic oxidation are presented. Comprehensive research of electrochemical and mechanical properties of obtained coatings was carried out. It was established that the polarization resistance of the samples with a coating containing zirconia nanoparticles is two times higher than that for the sample with base PEO layer. One of the important reasons for improving the protective properties of coatings formed in electrolytes containing nanoparticles consists in enhanced morphological characteristics, in particular, the porosity decrease and increase of thickness and resistivity (up to two orders of magnitude for ZrO2-containing coating of porousless sublayer in comparison with base PEO layer. Incorporation of silica and zirconia particles into the coating increases the mechanical performances. The layers containing nanoparticles have greater hardness and are more wear resistant in comparison with the coatings formed in the base electrolyte.

  7. Sodium Aluminate Concentration Effects on Microstructure and Corrosion Behavior of the Plasma Electrolytic Oxidation Coatings on Pure Titanium

    Science.gov (United States)

    Molaei, Maryam; Fattah-Alhosseini, Arash; Gashti, Seyed Omid

    2017-11-01

    Sodium aluminate (NaAlO2) concentration was varied in order to understand the influence of the chemical composition of electrolyte on the spark characteristics, microstructure, and corrosion behavior of plasma electrolytic oxidation (PEO) coatings. For this purpose, PEO coatings were formed on the pure titanium substrate surface using solutions of four diverse sodium aluminate concentrations (6, 8, 10, and 12 g/L). The PEO process was carried out at constant time and voltage (180 seconds and 420 V). Studying the microstructures of samples by scanning electron microscope (SEM) and their corrosion behavior in 3.5 wt pct NaCl solutions indicated that the increase in NaAlO2 concentration (up to 10 g/L) led to an increase in uniformity and compactness, thus decreasing the size of micro-pores and increment of corrosion resistance. However, at a certain level of NaAlO2 concentration (12 g/L), large and severe sparks were created on the surface of the sample during the process, worsening the corrosion resistance and microstructure of coating.

  8. Effect of the voltage pulse frequency on the structure of TiO2 coatings grown by plasma electrolytic oxidation

    Science.gov (United States)

    Torres-Cerón, D. A.; Gordillo-Delgado, F.; Moya-Betancourt, S. N.

    2017-12-01

    Plasma Electrolytic Oxidation (PEO) is used to synthetize titanium dioxide (TiO2) ceramic coatings with the appropriate selection of an electrolyte. The dimension of the micro-cavities and the particle size at the surface can be controlled through the pulse frequency of the voltage that is applied between the electrodes. The change of surface morphology can increase the surface area-to-volume ratio. In this work, PEO of an ASME SB-265 titanium substrate (20×20×1mm) was made in a water solution containing 8g/L Na3PO4 and 0.4g/L NaOH. Hence, the coatings were fabricated using voltage pulses of 340V for 10 minutes with a 10% duty cycle and frequencies of 1000, 1500 and 2000Hz. According to the X-ray diffractograms of the obtained samples, the sintering process at 500°C during 1 hour generated Anatase titanium dioxide porous coatings. The grain size decreased approximately from 29nm for 1000 and 1500Hz pulse frequencies until 21nm for 2000Hz. On the other hand, from the micrographs of scanning electron microscopy was possible to see the uniform formation of the micro-cavities with the largest diameter, 900nm, for the lowest frequency value used in PEO.

  9. Sodium Aluminate Concentration Effects on Microstructure and Corrosion Behavior of the Plasma Electrolytic Oxidation Coatings on Pure Titanium

    Science.gov (United States)

    Molaei, Maryam; Fattah-Alhosseini, Arash; Gashti, Seyed Omid

    2018-01-01

    Sodium aluminate (NaAlO2) concentration was varied in order to understand the influence of the chemical composition of electrolyte on the spark characteristics, microstructure, and corrosion behavior of plasma electrolytic oxidation (PEO) coatings. For this purpose, PEO coatings were formed on the pure titanium substrate surface using solutions of four diverse sodium aluminate concentrations (6, 8, 10, and 12 g/L). The PEO process was carried out at constant time and voltage (180 seconds and 420 V). Studying the microstructures of samples by scanning electron microscope (SEM) and their corrosion behavior in 3.5 wt pct NaCl solutions indicated that the increase in NaAlO2 concentration (up to 10 g/L) led to an increase in uniformity and compactness, thus decreasing the size of micro-pores and increment of corrosion resistance. However, at a certain level of NaAlO2 concentration (12 g/L), large and severe sparks were created on the surface of the sample during the process, worsening the corrosion resistance and microstructure of coating.

  10. Structural, photoluminescent and photocatalytic properties of TiO2:Eu3+ coatings formed by plasma electrolytic oxidation

    Science.gov (United States)

    Stojadinović, Stevan; Radić, Nenad; Grbić, Boško; Maletić, Slavica; Stefanov, Plamen; Pačevski, Aleksandar; Vasilić, Rastko

    2016-05-01

    In this paper, we used plasma electrolytic oxidation (PEO) of titanium in water solution containing 10 g/L Na3PO4·12H2O + 2 g/L Eu2O3 powder for preparation of TiO2:Eu3+ coatings. The surfaces of obtained coatings exhibit a typical PEO porous structure. The energy dispersive X-ray spectroscopy analysis showed that the coatings are mainly composed of Ti, O, P, and Eu; it is observed that Eu content in the coatings increases with PEO time. The X-ray diffraction analysis indicated that the coatings are crystallized and composed of anatase and rutile TiO2 phases, with anatase being the dominant one. X-ray photoelectron spectroscopy revealed that Ti 2p spin-orbit components of TiO2:Eu3+ coatings are shifted towards higher binding energy, with respect to pure TiO2 coatings, suggesting that Eu3+ ions are incorporated into TiO2 lattice. Diffuse reflectance spectroscopy showed that TiO2:Eu3+ coatings exhibit evident red shift with respect to the pure TiO2 coatings. Photoluminescence (PL) emission spectra of TiO2:Eu3+ coatings are characterized by sharp emission bands in orange-red region ascribed to f-f transitions of Eu3+ ions from excited level 5D0 to lower levels 7FJ (J = 0, 1, 2, 3, and 4). The excitation PL spectra of TiO2:Eu3+ coatings can be divided into two regions: the broad band region from 250 nm to 350 nm associated with charge transfer state of Eu3+ and the series of sharp peaks in the range from 350 nm to 550 nm corresponding to direct excitation of the Eu3+ ions. It is observed that the intensity of peaks in excitation and emission PL spectra increases with the concentration of Eu3+, but the peak positions remain practically unchanged. The ratio of PL emission for electric and magnetic dipole transitions indicates highly asymmetric environment around Eu3+ ions. The photocatalytic activity (PA) of TiO2:Eu3+ coatings is evaluated by measuring the photodegradation of methyl orange under simulated sunlight conditions. It is shown that PEO time, i.e., the amount

  11. Effect of Na2WO4 in Electrolyte on Microstructure and Tribological Behavior of Micro-arc Oxidation Coatings on Ti2AlNb Alloy

    Directory of Open Access Journals (Sweden)

    LIU Xiao-hui

    2018-02-01

    Full Text Available Micro-arc oxidation (MAO ceramic coatings were prepared on Ti2AlNb alloy in silicate/phosphate electrolytes with different concentrations of Na2WO4. The influence of Na2WO4 on the coating growth process, coating structure and composition was analyzed by SEM, XRD and XPS. The tribological behavior of MAO coatings was evaluated by the ball-disc wear test. The results show that the growth rate of MAO coating in electrolyte without Na2WO4 is only 0.08μm/min, meanwhile, the coating is loose and rough, and "networks" connecting with big pores exist on the coating surface.The main phase compositions of this coating are rutile TiO2, anatase TiO2, Al2O3, and Nb2O5. The addition of Na2WO4 in the electrolyte shortens the time before sparking of Ti2AlNb alloy, increases the growth rate of the coating, improves the uniformity of coating and meanwhile, a small amount of WO3 is introduced in the coating. Besides, MAO coatings formed in the participation of Na2WO4 have better wear resistance. Severe abrasive wear occurs when the test is made on Ti2AlNb alloy with Si3N4, the friction coefficient reaches 0.5-0.7. Both the friction coefficient and wear rate decrease obviously when Ti2AlNb is treated by MAO. The friction coefficient and wear rate of MAO coating prepared in the electrolyte with 4g/L Na2WO4 are 0.24 and 6.2×10-4mm3/(N·m, respectively. Only "fish scales" caused by fatigue wear appears on the coating surface.

  12. Effects of Duty Cycle, Current Frequency, and Current Density on Corrosion Behavior of the Plasma Electrolytic Oxidation Coatings on 6061 Al Alloy in Artificial Seawater

    Science.gov (United States)

    Vakili-Azghandi, Mojtaba; Fattah-alhosseini, Arash

    2017-10-01

    In this study, the effects of duty cycle, current frequency, and current density on corrosion behavior of the plasma electrolytic oxidation (PEO) coatings on 6061 Al alloy in artificial seawater (3.5 wt pct NaCl solution) were investigated. To serve this purpose, the electrical parameters of a unipolar pulsed current were applied during the PEO process on 6061 Al alloy in alkaline silicate electrolyte with and without Al2O3 nanoparticles. The coating morphology and microstructure were characterized by the scanning electron microscopy. The corrosion behavior and electrochemical response of the specimens treated by plasma electrolytic oxidation were analyzed by the electrochemical impedance spectroscopy and the potentiodynamic polarization in artificial seawater. It was found that PEO coatings formed in the presence of Al2O3 nanoparticle had lower porosity and exhibited better corrosion behavior compared with the coatings formed in the absence of Al2O3 nanoparticle in the structure. This can be attributed to the nanoparticles' incorporation and penetration through the PEO coatings. On the other hand, the decrease in the current density and increases in the duty cycle and frequency lead to further reduction of the nanoparticles' incorporation and distribution on the coating surface.

  13. Effect of individual discharge cascades on the microstructure of plasma electrolytic oxidation coatings

    Energy Technology Data Exchange (ETDEWEB)

    Troughton, S.C. [Department of Materials Science & Metallurgy, Cambridge Universitym 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Nominé, A. [Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Dean, J. [Department of Materials Science & Metallurgy, Cambridge Universitym 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Clyne, T.W., E-mail: twc10@cam.ac.uk [Department of Materials Science & Metallurgy, Cambridge Universitym 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2016-12-15

    Highlights: • High speed current/video monitoring of discharge cascades. • SEM and X-ray Computed Tomography of cascade sites. • Effects of supply frequency and process interruption. • Explanation of cascade localisation. - Abstract: Short duration (∼1 s) PEO treatments have been applied to aluminium alloy samples on which coatings of thickness ∼100 μm had previously been created. This was done using the small area electrical monitoring system previously developed in the Gordon Laboratory in Cambridge. Voltage supply frequencies of 50 Hz and 2.5 kHz were employed. Fairly high resolution SEM micrographs were taken, covering the whole surface of small area samples (ie over a circular area of diameter about 0.9 mm). This was done both before and after the 1 s PEO treatments. X-ray tomographic data were also obtained in the vicinity of a recently-completed set of discharges. The outcomes of these observations were correlated with synchronised high speed electrical monitoring and video photography, carried out during the PEO treatment periods. Localised cascades (comprising hundreds of individual discharges) were observed in all cases, persisting throughout the 1 s periods and also reappearing in the same location when a second 1 s PEO treatment was applied to the same sample. This repetition of discharges at the same location is apparently due to the deep pores associated with these sites, creating a pathway of low electrical resistance, even after appreciable oxidation has occurred in the vicinity. Observations were made of the way in which the surfaces were reconstructed locally as discharge cascades occurred. With the high frequency voltage supply, discharge lifetimes were limited to the half-cycle period (of 200 μs), but in other respects the cascades were similar to those with the lower frequency. However, some discharges occurred during cathodic half-cycles with the high frequency supply, at the same location as the anodic discharges in the cascade

  14. The formation of tungsten doped Al{sub 2}O{sub 3}/ZnO coatings on aluminum by plasma electrolytic oxidation and their application in photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Stojadinović, Stevan, E-mail: sstevan@ff.bg.ac.rs [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Vasilić, Rastko [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Radić, Nenad [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Tadić, Nenad [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Stefanov, Plamen [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, 1113 Sofia (Bulgaria); Grbić, Boško [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia)

    2016-07-30

    Highlights: • Tungsten doped Al{sub 2}O{sub 3}/ZnO coatings are formed by plasma electrolytic oxidation (PEO). • Coatings are mainly composed of alpha alumina, ZnO and metallic tungsten. • Photocatalytic activity of doped Al{sub 2}O{sub 3}/ZnO coatings is higher than of undoped ones. • The increase of photoluminescence corresponds to decrease of photocatalytic activity. • Tungsten acts as a charge trap to reduce the recombination rate of electron/hole pairs. - Abstract: Tungsten doped Al{sub 2}O{sub 3}/ZnO coatings are formed by plasma electrolytic oxidation of aluminum substrate in supporting electrolyte (0.1 M boric acid + 0.05 M borax + 2 g/L ZnO) with addition of different concentrations of Na{sub 2}WO{sub 4}·2H{sub 2}O. The morphology, crystal structure, chemical composition, and light absorption characteristics of formed surface coatings are investigated. The X-ray diffraction and X-ray photoelectron spectroscopy results indicate that formed surface coatings consist of alpha and gamma phase of Al{sub 2}O{sub 3}, ZnO, metallic tungsten and WO{sub 3}. Obtained results showed that incorporated tungsten does not have any influence on the absorption spectra of Al{sub 2}O{sub 3}/ZnO coatings, which showed invariable band edge at about 385 nm. The photocatalytic activity of undoped and tungsten doped Al{sub 2}O{sub 3}/ZnO coatings is estimated by the photodegradation of methyl orange. The photocatalytic activity of tungsten doped Al{sub 2}O{sub 3}/ZnO coatings is higher thanof undoped Al{sub 2}O{sub 3}/ZnO coatings; the best photocatalytic activity is ascribed to coatings formed in supporting electrolyte with addition of 0.3 g/L Na{sub 2}WO{sub 4}·2H{sub 2}O. Tungsten in Al{sub 2}O{sub 3}/ZnO coatings acts as a charge trap, thus reducing the recombination rate of photogenerated electron-hole pairs. The results of PL measurements are in agreement with photocatalytic activity. Declining PL intensity corresponds to increasing photocatalytic activity of the

  15. Structure, tribocorrosion and biocide characterization of Ca, P and I containing TiO{sub 2} coatings developed by plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Sáenz de Viteri, V., E-mail: virginia.saenzdeviteri@tekniker.es [IK4-Tekniker, Polo Tecnológico de Eibar, Calle Iñaki Goenaga, 5, Eibar 20600 (Spain); Bayón, R.; Igartua, A. [IK4-Tekniker, Polo Tecnológico de Eibar, Calle Iñaki Goenaga, 5, Eibar 20600 (Spain); Barandika, G. [Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco, UPV/EHU, Apartado 644, Bilbao E-48080 (Spain); Moreno, J. Esteban; Peremarch, C. Pérez-Jorge; Pérez, M. Martínez [Department of Clinical Microbiology, IIS-Fundación Jiménez Díaz, Av. Reyes Católicos 2, Madrid 28040 (Spain)

    2016-03-30

    Graphical abstract: - Highlights: • Ca, P and I doped TiO{sub 2} coatings were developed by means of plasma electrolytic oxidation (PEO) technique. • Microstructure and chemical composition of the developed coating were in depth analyzed. • The effect of wear-corrosion synergy was studied through tribocorrosion tests. • Antibacterial efficiency of iodine as biocide agent was analyzed by means of bacterial adhesion study. • A TiO{sub 2} coating with improved wear-corrosion resistance, suitable surface for cell adhesion and biocide properties was achieved. - Abstract: In hip joint implants, in particular in the stems, wear-corrosion effects can accelerate the degradation of the biomaterial. The lack of osseointegration and the risk of contracting implant-associated infections may be other reasons for a premature failure of the implant. In this work, TiO{sub 2} coatings have been developed by means of plasma electrolytic oxidation (PEO) technique in order to achieve wear-resistant hard coatings with osseointegration ability and biocide characteristics. During the PEO process, elements that favor cell growth, like Ca and P, were introduced into the coating. With the purpose of providing the coating with antibacterial properties iodine was added like biocide agent. The microstructure and chemical composition of the developed coatings were analyzed in order to see if the surface of the films was suitable for the cell attachment. The effect of wear-corrosion synergy was studied by means of tribocorrosion tests. Finally, the biocide capacity of iodine against Staphylococcus aureus and Staphylococcus epidermidis was analyzed through bacterial adhesion tests. High wear and corrosion resistance was shown in one of the developed coatings. The achieved surface microstructures seem to be appropriate to improve the osseointegration with proper pore size and porosity index. The antibacterial capacity of iodine was confirmed for S. epidermidis.

  16. Effect of KOH to Na2SiO3 Ratio on Microstructure and Hardness of Plasma Electrolytic Oxidation Coatings on AA 6061 Alloy

    Science.gov (United States)

    Sharma, Ashutosh; Jang, Yong-Joo; Jung, Jae Pil

    2017-10-01

    In this study, plasma electrolytic oxidation (PEO) process has been employed to fabricate alumina coatings on AA 6061 aluminum alloy from an electrolyte containing water glass (Na2SiO3) and alkali (KOH). The effect of deposition time and the alkali to water glass (KOH: Na2SiO3) composition ratio on the coating morphology and properties are studied. The different phases of the oxide layer and microstructure are investigated by x-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results indicate that initially γ-Al2O3 forms in the coating, and as the processing time is increased from 5 to 60 minutes, α-Al2O3 phase becomes prominent. Further, higher the content of Na2SiO3, higher is the hardness and coating growth rate due to the formation of stable α-Al2O3 and Al-Si-O phase. It has been reported that the optimum properties of the PEO coatings can be obtained at a ratio of KOH: Na2SiO3 ≈ 15:10 followed by 10:10.

  17. Effect of KOH to Na2SiO3 Ratio on Microstructure and Hardness of Plasma Electrolytic Oxidation Coatings on AA 6061 Alloy

    Science.gov (United States)

    Sharma, Ashutosh; Jang, Yong-Joo; Jung, Jae Pil

    2017-09-01

    In this study, plasma electrolytic oxidation (PEO) process has been employed to fabricate alumina coatings on AA 6061 aluminum alloy from an electrolyte containing water glass (Na2SiO3) and alkali (KOH). The effect of deposition time and the alkali to water glass (KOH: Na2SiO3) composition ratio on the coating morphology and properties are studied. The different phases of the oxide layer and microstructure are investigated by x-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results indicate that initially γ-Al2O3 forms in the coating, and as the processing time is increased from 5 to 60 minutes, α-Al2O3 phase becomes prominent. Further, higher the content of Na2SiO3, higher is the hardness and coating growth rate due to the formation of stable α-Al2O3 and Al-Si-O phase. It has been reported that the optimum properties of the PEO coatings can be obtained at a ratio of KOH: Na2SiO3 ≈ 15:10 followed by 10:10.

  18. In-situ grown MgO-ZnO ceramic coating with high thermal emittance on Mg alloy by plasma electrolytic oxidation

    Science.gov (United States)

    Li, Hang; Lu, Songtao; Qin, Wei; Wu, Xiaohong

    2017-07-01

    Intense solar radiation and internal heat generation determine the equilibrium temperature of an in-orbit spacecraft. Thermal control coatings with low solar absorptance and high thermal emittance effectively maintain the thermal equilibrium within safe operating limits for exposed, miniaturized and highly integrated components. A novel ceramic coating with high thermal emittance and good adhesion was directly prepared on the Mg substrate using an economical process of controlled plasma electrolytic oxidation (PEO) in the electrolyte containing ZnSO4. XRD and XPS results showed that this coating was mainly composed of the MgO phase as well as an unusual ZnO crystalline phase. The adhesive strength between the coating and substrate determined by a pull-off test revealed an excellent adhesion. Thermal and optical properties test revealed that the coating exhibited a high infrared emittance of 0.88 (2-16 μm) and low solar absorptance of 0.35 (200-2500 nm). The result indicated that the formation of ZnO during the PEO process played an important role in the improvement of the coating emittance. The process developed provides a simple surface method for improving the thermal emittance of Mg alloy, which presents a promising application prospect in the thermal management of the spacecraft.

  19. Corrosion behaviors and effects of corrosion products of plasma electrolytic oxidation coated AZ31 magnesium alloy under the salt spray corrosion test

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Guo, Changhong; Jiang, Guirong [College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004 (China); Shen, Dejiu, E-mail: DejiuShen@163.com [State Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2016-08-15

    Highlights: • Corrosion behaviors of a PEO coating was investigated after the salt spray test. • Corrosion products have significant effects on corrosion behaviors of the coating. • An electrochemical corrosion model is proposed. - Abstract: The effects of corrosion products on corrosion behaviors of AZ31 magnesium alloy with a plasma electrolytic oxidation (PEO) coating were investigated under the salt spray corrosion test (SSCT). The surface morphology, cross-sectional microstructure, chemical and phase compositions of the PEO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD), respectively. Further, the corrosion process of the samples under the SSCT was examined in a non-aqueous electrolyte (methanol) using electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit. The results show that the inner layer of the coating was destroyed firstly and the corrosion products have significant effects on the corrosion behaviors of the coating. The results above are discussed and an electrochemical corrosion model is proposed in the paper.

  20. Plasma electrolytic oxidation of Titanium Aluminides

    Science.gov (United States)

    Morgenstern, R.; Sieber, M.; Grund, T.; Lampke, T.; Wielage, B.

    2016-03-01

    Due to their outstanding specific mechanical and high-temperature properties, titanium aluminides exhibit a high potential for lightweight components exposed to high temperatures. However, their application is limited through their low wear resistance and the increasing high-temperature oxidation starting from about 750 °C. By the use of oxide ceramic coatings, these constraints can be set aside and the possible applications of titanium aluminides can be extended. The plasma electrolytic oxidation (PEO) represents a process for the generation of oxide ceramic conversion coatings with high thickness. The current work aims at the clarification of different electrolyte components’ influences on the oxide layer evolution on alloy TNM-B1 (Ti43.5Al4Nb1Mo0.1B) and the creation of compact and wear resistant coatings. Model experiments were applied using a ramp-wise increase of the anodic potential in order to show the influence of electrolyte components on the discharge initiation and the early stage of the oxide layer growth. The production of PEO layers with technically relevant thicknesses close to 100 μm was conducted in alkaline electrolytes with varying amounts of Na2SiO3·5H2O and K4P2O7 under symmetrically pulsed current conditions. Coating properties were evaluated with regard to morphology, chemical composition, hardness and wear resistance. The addition of phosphates and silicates leads to an increasing substrate passivation and the growth of compact oxide layers with higher thicknesses. Optimal electrolyte compositions for maximum coating hardness and thickness were identified by statistical analysis. Under these conditions, a homogeneous inner layer with low porosity can be achieved. The frictional wear behavior of the compact coating layer is superior to a hard anodized layer on aluminum.

  1. Structural, photoluminescent and photocatalytic properties of TiO{sub 2}:Eu{sup 3+} coatings formed by plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Stojadinović, Stevan, E-mail: sstevan@ff.bg.ac.rs [University of Belgrade, Faculty of Physics, Studentski trg 12–16, Belgrade 11000 (Serbia); Radić, Nenad; Grbić, Boško [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, Belgrade 11000 (Serbia); Maletić, Slavica [University of Belgrade, Faculty of Physics, Studentski trg 12–16, Belgrade 11000 (Serbia); Stefanov, Plamen [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria); Pačevski, Aleksandar [University of Belgrade, Faculty of Mining and Geology, Đušina 7, 11000 Belgrade (Serbia); Vasilić, Rastko [University of Belgrade, Faculty of Physics, Studentski trg 12–16, Belgrade 11000 (Serbia)

    2016-05-01

    Graphical abstract: - Highlights: • TiO{sub 2}:Eu{sup 3+} coatings are formed by plasma electrolytic oxidation (PEO). • Photoluminescence is related to transitions of Eu{sup 3+} from level {sup 5}D{sub 0} to levels {sup 7}F{sub J}. • Eu{sup 3+} ions occupy non-inversion symmetry sites in the coatings. • PEO time is an important factor affecting photocatalytic activity. - Abstract: In this paper, we used plasma electrolytic oxidation (PEO) of titanium in water solution containing 10 g/L Na{sub 3}PO{sub 4}·12H{sub 2}O + 2 g/L Eu{sub 2}O{sub 3} powder for preparation of TiO{sub 2}:Eu{sup 3+} coatings. The surfaces of obtained coatings exhibit a typical PEO porous structure. The energy dispersive X-ray spectroscopy analysis showed that the coatings are mainly composed of Ti, O, P, and Eu; it is observed that Eu content in the coatings increases with PEO time. The X-ray diffraction analysis indicated that the coatings are crystallized and composed of anatase and rutile TiO{sub 2} phases, with anatase being the dominant one. X-ray photoelectron spectroscopy revealed that Ti 2p spin-orbit components of TiO{sub 2}:Eu{sup 3+} coatings are shifted towards higher binding energy, with respect to pure TiO{sub 2} coatings, suggesting that Eu{sup 3+} ions are incorporated into TiO{sub 2} lattice. Diffuse reflectance spectroscopy showed that TiO{sub 2}:Eu{sup 3+} coatings exhibit evident red shift with respect to the pure TiO{sub 2} coatings. Photoluminescence (PL) emission spectra of TiO{sub 2}:Eu{sup 3+} coatings are characterized by sharp emission bands in orange–red region ascribed to f–f transitions of Eu{sup 3+} ions from excited level {sup 5}D{sub 0} to lower levels {sup 7}F{sub J} (J = 0, 1, 2, 3, and 4). The excitation PL spectra of TiO{sub 2}:Eu{sup 3+} coatings can be divided into two regions: the broad band region from 250 nm to 350 nm associated with charge transfer state of Eu{sup 3+} and the series of sharp peaks in the range from 350 nm to 550 nm

  2. In vitro evaluation of cell proliferation and collagen synthesis on titanium following plasma electrolytic oxidation.

    Science.gov (United States)

    Whiteside, Paul; Matykina, Endzhe; Gough, Julie E; Skeldon, Peter; Thompson, George E

    2010-07-01

    Titania-based coatings produced by plasma electrolytic oxidation are being investigated as bioactive surfaces for titanium implants. In this study, plasma electrolytic oxidation was performed in calcium- and phosphorus-based electrolytes under DC conditions, resulting in coatings of thickness of approximately 8-15 mum. Coating morphologies, microstructures, and compositions were examined by scanning electron microscopy with energy-dispersive X-ray analysis, X-ray diffraction, and electron probe microanalysis. The coatings revealed a cratered morphology, with incorporated calcium and phosphorus species. Proliferation rates of primary human osteoblasts cells on the coatings were up to approximately 37% faster than those for uncoated titanium and 316L stainless steel reference materials. Further, the coatings assisted cell adhesion and generation and anchorage of collagen. The amount of collagen was upto approximately 2.4 times greater than for the reference substrates. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.

  3. Effects of duty cycle and electrolyte concentration on the microstructure and biocompatibility of plasma electrolytic oxidation treatment on zirconium metal

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Shao-Fu [Department of Materials and Mineral Resources Engineering, Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 10608, Taiwan (China); Lou, Bih-Show [Chemistry Division, Center for General Education, Chang Gung University, Taoyuan 333, Taiwan (China); Yang, Yung-Chin [Department of Materials and Mineral Resources Engineering, Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 10608, Taiwan (China); Wu, Pei-Shan [Department of Materials Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan (China); Chung, Ren-Jei [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei 10608, Taiwan (China); Lee, Jyh-Wei, E-mail: jefflee@mail.mcut.edu.tw [Department of Materials Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan (China); Center for Thin Film Technologies and Applications, Ming Chi University of Technology, New Taipei City 24301, Taiwan (China); Department of Electronic Engineering, Chang Gung University, Taoyuan 333, Taiwan (China)

    2015-12-01

    Recently, the plasma electrolytic oxidation (PEO) process has been widely studied and applied in the industrial setting due to its ability to create functional oxide layers on Al, Ti, Mg, and Zr alloys. In this work, a pulsed direct current (DC) power supply was adopted to grow the zirconia coating on pure Zr metal by PEO treatment. A fixed frequency of 1000 Hz and constant current of 2 A were used to fabricate all zirconia coatings. Duty cycle values of 25%, 75%, and 100% were used and 0.1 M K{sub 3}PO{sub 4} aqueous solution containing three different concentrations of KOH, 0.01, 0.05 and 0.1 M, was also used in fabrication. The plasma breakdown voltage decreased with increasing KOH concentration due to its higher electrolyte conductivity. The PEO oxide coating consisted of a thin continuous barrier layer and a thick porous outermost layer, which consisted of mainly monoclinic and minor tetragonal ZrO{sub 2} phases. The PEO treatment of Zr metal provided excellent corrosion resistance in Hank's solution and good biocompatibility for 3T3 and MG63 cells. These results suggest that PEO coatings having potential applications in the biomedical field were confirmed in this study. - Highlights: • Plasma electrolytic oxidation (PEO) treated coating consists of a continuous thin layer and a thick porous outermost layer. • The PEO coating thickness decreases with increasing content of KOH in electrolyte at duty cycles of 75% and 100%. • All PEO coatings provide good biocompatibility and no toxicity to both 3T3 and MG63 cells. • The PEO process greatly enhances the corrosion resistance of Zr metal to Hank's solution.

  4. Enhanced mechanical properties and increased corrosion resistance of a biodegradable magnesium alloy by plasma electrolytic oxidation (PEO).

    Science.gov (United States)

    White, Leon; Koo, Youngmi; Neralla, Sudheer; Sankar, Jagannathan; Yun, Yeoheung

    2016-06-01

    We report the enhanced mechanical properties of AZ31 magnesium alloys by plasma electrolytic oxidation (PEO) coating in NaOH, Na2SiO3, KF and NaH2PO4·2H2O containing electrolytes. Mechanical properties including wear resistance, surface hardness and elastic modulus were increased for PEO-coated AZ31 Mg alloys (PEO-AZ31). DC polarization in Hank's solution indicating that the corrosion resistance significantly increased for PEO-coating in KF-contained electrolyte. Based on these results, the PEO coating method shows promising potential for use in biodegradable implant applications where tunable corrosion and mechanical properties are needed.

  5. The Influence of Current Density and Frequency on the Microstructure and Corrosion Behavior of Plasma Electrolytic Oxidation Coatings on Ti6Al4V

    Science.gov (United States)

    Khanmohammadi, H.; Allahkaram, S. R.; Igual Munoz, A.; Towhidi, N.

    2017-02-01

    The effect of processing current density and frequency on the microstructure and corrosion behavior of the PEO coatings was studied. Coatings were characterized using FESEM, EDS, potentiodynamic polarization and EIS. The results indicated that the surface roughness, porosity and Al/Ti chemical value on the surface of the coatings increase with an increase in the current density and a decrease in the frequency of the PEO process. Corrosion investigations showed a relation between a mixed structural parameter (that contains thickness, porosity percentage and average pore diameter of the coatings) and the corrosion resistance of the PEO coatings. EIS data showed that higher coating thickness, lower surface porosity percentage and smaller pore diameter lead to the higher corrosion resistance.

  6. Effects of Surface Coating Preparation and Sliding Modes on Titanium Oxide Coated Titanium Alloy for Aerospace Applications

    Directory of Open Access Journals (Sweden)

    Bo Yuan Peng

    2014-01-01

    electrolytic oxidation (PEO. During the PEO procedure, a composition of silicate and phosphate was used as the electrolyte. In order to evaluate the coating, pin-on-disk (POD tribology tests and cyclic inclined sliding tests were used under dry room conditions. Furthermore, scanning electron microscopy (SEM and energy dispersive spectroscopy (EDS were utilized to examine the morphology and composition of the coating surfaces. The results of the POD tests revealed that the PEO coating could have a low coefficient of friction and suggested that high silicon concentrations in the PEO coatings take away oxygen from stoichiometric Ti oxides to create lubricating oxides. In addition, cyclic inclined sliding tests showed that smaller pores on the surface of the coating could permit a higher coating cohesive strength and allow the coated Ti alloy surface to perform better under high inclined sliding forces.

  7. Imaging hydrogen oxidation activity of catalyst-coated perfluoro ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 121; Issue 5. Imaging hydrogen oxidation activity of catalyst-coated perfluoro sulfonic acid-polymer electrolyte membranes using Scanning Electrochemical Microscopy. Meera Parthasarathy Vijayamohanan K Pillai. Volume 121 Issue 5 September 2009 pp 719-725 ...

  8. Surface analysis of Fe-Co-Mo electrolytic coatings

    Science.gov (United States)

    Yar-Mukhamedova, G. Sh; Sakhnenko, N. D.; Ved', M. V.; Yermolenko, I. Yu; Zyubanova, S. I.

    2017-06-01

    Coatings Fe-Co-Mo with a composition of 47 at.% iron, 28 at.% Cobalt and 25 at.% Molybdenum were deposited from citrate electrolyte using pulse electrolysis mode. Scanning electron and atomic force microscopy have established the surface morphology and topography. It was identified the parts with a globular structure which have an average size of 0.2-0.5μm and singly located sharp grains. Within the same scan area sites with developed surface were detected the topography of which is identical to the crystal structure of cobalt with the crystallites size of 0.2-1.75μm. The parameters Ra and Rq for parts with different morphology as well as average characteristics of coatings demonstrated the low roughness of the surface. It is found that the coercive force of Fe-Co-Mo films is 7-10 Oe, which allow us to classify the Fe-Co-Mo coatings as soft magnetic materials.

  9. High performance ceria-bismuth bilayer electrolyte low temperature solid oxide fuel cells (LT-SOFCs) fabricated by combining co-pressing with drop-coating

    KAUST Repository

    Hou, Jie

    2015-03-24

    The Sm0.075Nd0.075Ce0.85O2-δ-Er0.4Bi1.6O3 bilayer structure film, which showed an encouraging performance in LT-SOFCs, was successfully fabricated by a simple low cost technique combining one-step co-pressing with drop-coating.

  10. Study of Scanning Micro-arc Oxidation and Coating Development

    Science.gov (United States)

    Xia, Lingqin; Han, Jianmin; Domblesky, Joseph P.; Yang, Zhiyong; Li, Weijing

    2017-11-01

    Micro-arc oxidation (MAO) continues to be the focus of numerous investigations, whereas relatively few studies have considered scanning micro-arc oxidation (SMAO). In the present work, an experimental study was performed using stationary and moving electrodes to investigate coating development in SMAO and discern the effect of key process parameters. Examination of oxide deposits made on A356 aluminum show that coating thickness and growth rate are inversely related to inter-electrode spacing and travel speed. An evaluation of SMAO deposits made by stationary and moving nozzles revealed that coating thickness profiles follow a Gaussian distribution due to the electrolyte flow field in the impingement zone. Hardness surveys and scanning electron microscope analysis of SMAO coatings revealed that micro-hardness distributions and cross-sectional morphology are similar to MAO for a stationary nozzle but that a denser outer layer develops when a moving nozzle is used. This is attributed to a high density of discharge occurring in micropores of the oxide film and remelting which results from the moving electrolyte column. Analysis of voltage-current characteristic curves shows that the resistance of the electrolyte column is essentially linear over the range considered and results indicate that it can be modeled as a variable length resistor. While further testing is needed, results confirm that SMAO is suitable for coating large, planar parts and for repairing worn surfaces.

  11. Electropolymerisation of Aniline on AZ91 Magnesium Alloy: The Effect of Coating Electrolyte Corrosiveness

    OpenAIRE

    Asif Baloch; M. Bobby Kannan

    2017-01-01

    In this study, polyaniline was coated on AZ91 magnesium alloy using an electropolymerisation technique, and the effect of corrosiveness of the coating electrolytes on the polymerisation and the coating performance were evaluated. Two electrolytes, i.e., aniline + sodium salicylate (PASS) and aniline + potassium hydroxide (PAPH), with different corrosiveness, were used for polyaniline coating on AZ91 magnesium alloy. Potentiodynamic polarisation results suggested that salicylic acid (C7H5NaO3)...

  12. TiO2 Deposition on AZ31 Magnesium Alloy Using Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Leon White

    2013-01-01

    Full Text Available Plasma electrolytic oxidation (PEO has been used in the past as a useful surface treatment technique to improve the anticorrosion properties of Mg alloys by forming protective layer. Coatings were prepared on AZ31 magnesium alloy in phosphate electrolyte with the addition of TiO2 nanoparticles using plasma electrolytic oxidation (PEO. This present work focuses on developing a TiO2 functional coating to create a novel electrophotocatalyst while observing the surface morphology, structure, composition, and corrosion resistance of the PEO coating. Microstructural characterization of the coating was investigated by X-ray diffraction (XRD and scanning electron microscopy (SEM followed by image analysis and energy dispersive spectroscopy (EDX. The corrosion resistance of the PEO treated samples was evaluated with electrochemical impedance spectroscopy (EIS and DC polarization tests in 3.5 wt.% NaCl. The XRD pattern shows that the components of the oxide film include Mg from the substrate as well as MgO and Mg2TiO4 due to the TiO2 nanoparticle addition. The results show that the PEO coating with TiO2 nanoparticles did improve the corrosion resistance when compared to the AZ31 substrate alloy.

  13. Low temperature solid oxide electrolytes (LT-SOE): A review

    Science.gov (United States)

    Singh, B.; Ghosh, S.; Aich, S.; Roy, B.

    2017-01-01

    Low temperature solid oxide fuel cell (LT-SOFC) can be a source of power for vehicles, online grid, and at the same time reduce system cost, offer high reliability, and fast start-up. A huge amount of research work, as evident from the literature has been conducted for the enhancement of the ionic conductivity of LT electrolytes in the last few years. The basic conduction mechanisms, advantages and disadvantages of different LT oxide ion conducting electrolytes {BIMEVOX systems, bilayer systems including doped cerium oxide/stabilised bismuth oxide and YSZ/DCO}, mixed ion conducting electrolytes {doped cerium oxides/alkali metal carbonate composites}, and proton conducting electrolytes {doped and undoped BaCeO3, BaZrO3, etc.} are discussed here based on the recent research articles. Effect of various material aspects (composition, doping, layer thickness, etc.), fabrication methods (to achieve different microstructures and particle size), design related strategies (interlayer, sintering aid etc.), characterization temperature & environment on the conductivity of the electrolytes and performance of the fuel cells made from these electrolytes are shown in tabular form and discussed. The conductivity of the electrolytes and performance of the corresponding fuel cells are compared. Other applications of the electrolytes are mentioned. A few considerations regarding the future prospects are pointed.

  14. Characterization of stainless steel surface processed using electrolytic oxidation and titanium complex ion solution

    Science.gov (United States)

    Kang, Yubin; Choi, Jaeyoung; Park, Jinju; Kim, Woo-Byoung; Lee, Kun-Jae

    2017-09-01

    This study attempts to improve the physical and chemical adhesion between metals and ceramics by using electrolytic oxidation and a titanium organic/inorganic complex ion solution on the SS-304 plate. Surface analysis confirmed the existence of the Tisbnd Osbnd Mx bonds formed by the bonding between the metal ions and the Ti oxide at the surface of the pre-processed SS plate, and improved chemical adhesion during ceramic coating was expected by confirming the presence of the carboxylic group. The adhesion was evaluated by using the ceramic coating solution in order to assess the improved adhesion of the SS plate under conditions. The results showed that both the adhesion and durability were largely improved in the sample processed with all the pre-processing steps, thus confirming that the physical and chemical adhesion between metals and ceramics can be improved by enhancing the physical roughness via electrolytic oxidation and pre-processing using a Ti complex ion solution.

  15. High efficiency solid state dye sensitized solar cells with graphene-polyethylene oxide composite electrolytes.

    Science.gov (United States)

    Akhtar, M Shaheer; Kwon, Soonji; Stadler, Florian J; Yang, O Bong

    2013-06-21

    Novel and highly effective composite electrolytes were prepared by combining the two dimensional graphene (Gra) and polyethylene oxide (PEO) for the solid electrolyte of dye sensitized solar cells (DSSCs). Gra sheets were uniformly coated by the polymer layer through the ester carboxylate bonding between oxygenated species on Gra sheets and PEO. The Gra-PEO composite electrolyte showed the large scale generation of iodide ions in a redox couple. From rheological analysis, the decrease in viscosity after the addition of LiI and I2 in the Gra-PEO electrolyte might be explained by the dipolar interactions being severely disrupted by the ionic interactions of Li(+), I(-), and I3(-) ions. A composite electrolyte with 0.5 wt% Gra presented a higher ionic conductivity (3.32 mS cm(-1)) than those of PEO and other composite electrolytes at room temperature. A high overall conversion efficiency (∼5.23%) with a very high short circuit current (JSC) of 18.32 mA cm(-2), open circuit voltage (VOC) of 0.592 V and fill factor (FF) of 0.48 was achieved in DSSCs fabricated with the 0.5 wt% Gra-PEO composite electrolyte. This enhanced photovoltaic performance might be attributed to the large scale formation of iodide ions in the redox electrolyte and the relatively high ionic conductivity.

  16. Effects of oxide incorporation in proton conducting organic electrolytes

    OpenAIRE

    Sörgel, Seniz

    2009-01-01

    In this work, the effects of incorporation of various types of oxide particles (e.g. ZrO2, TiO2, Al2O3) into proton conducting organic electrolytes is investigated. As a weak liquid model electrolyte, moderately proton conducting imidazole is chosen. As a highly proton conducting strong polymer electrolyte, and simultaneously practically very important electrolyte, Nafion® is selected for the second part of the work. In the first part of this work, for the first time, the applicabilit...

  17. Enhanced mechanical properties and increased corrosion resistance of a biodegradable magnesium alloy by plasma electrolytic oxidation (PEO)

    Energy Technology Data Exchange (ETDEWEB)

    White, Leon; Koo, Youngmi [FIT BEST Laboratory, Engineering Research Center, Department of Chemical, Biological, and Bio Engineering, North Carolina A& T State University, Greensboro, NC 27411 (United States); Neralla, Sudheer [Jet-Hot LLC, Burlington, NC 27215 (United States); Sankar, Jagannathan [FIT BEST Laboratory, Engineering Research Center, Department of Chemical, Biological, and Bio Engineering, North Carolina A& T State University, Greensboro, NC 27411 (United States); Yun, Yeoheung, E-mail: yyun@ncat.edu [FIT BEST Laboratory, Engineering Research Center, Department of Chemical, Biological, and Bio Engineering, North Carolina A& T State University, Greensboro, NC 27411 (United States)

    2016-06-15

    Highlights: • Plasma electrolytic oxidation (PEO) method was developed to control corrosion, porosity, and mechanical property. • Mechanical properties of PEO-coated AZ31 alloys were affected by the different electrolyte. • Mechanical properties and corrosion resistance of PEO-coated AZ31 alloys were compared with uncoated one. - Abstract: We report the enhanced mechanical properties of AZ31 magnesium alloys by plasma electrolytic oxidation (PEO) coating in NaOH, Na{sub 2}SiO{sub 3}, KF and NaH{sub 2}PO{sub 4}·2H{sub 2}O containing electrolytes. Mechanical properties including wear resistance, surface hardness and elastic modulus were increased for PEO-coated AZ31 Mg alloys (PEO-AZ31). DC polarization in Hank's solution indicating that the corrosion resistance significantly increased for PEO-coating in KF-contained electrolyte. Based on these results, the PEO coating method shows promising potential for use in biodegradable implant applications where tunable corrosion and mechanical properties are needed.

  18. Synthesis and characterization of nanocomposite polymer blend electrolyte thin films by spin-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Chapi, Sharanappa; Niranjana, M.; Devendrappa, H., E-mail: dehu2010@gmail.com [Department of Physics, Mangalore University, Mangalagangothri - 574 199 (India)

    2016-05-23

    Solid Polymer blend electrolytes based on Polyethylene oxide (PEO) and poly vinyl pyrrolidone (PVP) complexed with zinc oxide nanoparticles (ZnO NPs; Synthesized by Co-precipitation method) thin films have prepared at a different weight percent using the spin-coating method. The complexation of the NPs with the polymer blend was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). The variation in film morphology was examined by polarized optical micrographs (POMs). The thermal behavior of blends was investigated under non-isothermal conditions by differential thermal analyses (DTA). A single glass transition temperature for each blend was observed, which supports the existence of compatibility of such system. The obtained results represent that the ternary based thin films are prominent materials for battery and optoelectronic device applications.

  19. Capacitance enhancement of polyaniline coated curved-graphene supercapacitors in a redox-active electrolyte

    KAUST Repository

    Chen, Wei

    2013-01-01

    We show, for the first time, a redox-active electrolyte in combination with a polyaniline-coated curved graphene active material to achieve significant enhancement in the capacitance (36-92% increase) compared to supercapacitors that lack the redox-active contribution from the electrolyte. The supercapacitors based on the redox-active electrolyte also exhibit excellent rate capability and very long cycling performance (>50 000 cycles). This journal is © The Royal Society of Chemistry.

  20. Influence of the Electrolyte Concentration on the Smooth TiO2 Anodic Coatings on Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    María Laura Vera

    2017-03-01

    Full Text Available To obtain smooth TiO2 coatings for building a new design of Ti-6Al-4V heart valve, the anodic oxidation technique in pre-spark conditions was evaluated. TiO2 coating is necessary for its recognized biocompatibility and corrosion resistance. A required feature on surfaces in contact with blood is a low level of roughness (Ra ≤ 50 nm that does not favor the formation of blood clots. The present paper compares the coatings obtained by anodic oxidation of the Ti-6Al-4V alloy using H2SO4 at different concentrations (0.1–4 M as electrolyte and applying different voltages (from 20 to 70 V. Color and morphological analysis of coatings are performed using optical and scanning microscopy. The crystalline phases were analyzed by glancing X-ray diffraction. By varying the applied voltage, different interference colors coatings were obtained. The differences in morphologies of the coatings caused by changes in acid concentration are more evident at high voltages, limiting the oxidation conditions for the desired application. Anatase phase was detected from 70 V for 1 M H2SO4. An increase in the concentration of H2SO4 decreases the voltage at which the transformation of amorphous to crystalline coatings occurs; i.e., with 4 M H2SO4, the anatase phase appears at 60 V.

  1. Proliferation and differentiation of osteoblast-like MC3T3-E1 cells ons biomimetically and electrolytically deposited calcium phosphate coatings

    NARCIS (Netherlands)

    Wang, J.; de Boer, Jan; de Groot, K.

    2009-01-01

    Biomimetic and electrolytic deposition are versatile methods to prepare calcium phosphate coatings. In this article, we compared the effects of biomimetically deposited octacalcium phosphate and carbonate apatite coatings as well as electrolytically deposited carbonate apatite coating on the

  2. Tribological Study on Plasma Electrolytic Oxidation Treatment in Al-Si Alloys for Engine Application

    Science.gov (United States)

    Eiliat, Hoda

    Automotive industry strives to reach an optimum level of fuel economy. This can be achieved by overcoming two impacting factors on fuel consumption: weight and friction force. This research contributes to reduce both. The proposed surface treatment can replace cylinder liners of hypoeutectic aluminum silicon alloy engine blocks with a thin layer of ceramic oxide composed of alpha and gamma phases of Al2O3 and mullite. The coatings are achieved in an aqueous electrolytic bath with current densities of 0.1 to 0.2 A/cm2. Coatings produced in silicate based solutions have shown good adaptability to the counter surface with an average 0.12 coefficient of friction. Coatings produced in phosphate and aluminate solution have shown signs of delamination, and excessive porosity and roughness respectively. Coatings produced under Bipolar Pulsed Direct Current mode has up to 12% higher hardness values compared to unipolar coatings. For each increment of 0.2 A/cm2 current density, there is a 30% of increase in coating growth rate. Higher pH values of the solution creates faster growth rate up to 1.5 mu/min. These coatings are 20% more susceptible to wear. Samples treated in MoS2 solution showed 22% lower average roughness values and 37% of reduction in coefficient of friction. Mild wear scars on the piston rings were detected for the optimized coatings.

  3. Characteristics and in vitro response of thin hydroxyapatite–titania films produced by plasma electrolytic oxidation of Ti alloys in electrolytes with particle additions

    Science.gov (United States)

    Yeung, W. K.; Sukhorukova, I. V.; Shtansky, D. V.; Levashov, E. A.; Zhitnyak, I. Y.; Gloushankova, N. A.; Kiryukhantsev-Korneev, P. V.; Petrzhik, M. I.; Matthews, A.

    2016-01-01

    The enhancement of the biological properties of Ti by surface doping with hydroxyapatite (HA) is of great significance, especially for orthodontic applications. This study addressed the effects of HA particle size in the electrolyte suspension on the characteristics and biological properties of thin titania-based coatings produced on Ti–6Al–4V alloy by plasma electrolytic oxidation (PEO). Detailed morphological investigation of the coatings formed by a single-stage PEO process with two-step control of the electrical parameters was performed using the Minkowski functionals approach. The surface chemistry was studied by glow discharge optical emission spectroscopy and Fourier transform infrared spectroscopy, whereas mechanical properties were evaluated using scratch tests. The biological assessment included in vitro evaluation of the coating bioactivity in simulated body fluid (SBF) as well as studies of spreading, proliferation and osteoblastic differentiation of MC3T3-E1 cells. The results demonstrated that both HA micro- and nanoparticles were successfully incorporated in the coatings but had different effects on their surface morphology and elemental distributions. The micro-particles formed an irregular surface morphology featuring interpenetrated networks of fine pores and coating material, whereas the nanoparticles penetrated deeper into the coating matrix which retained major morphological features of the porous TiO2 coating. All coatings suffered cohesive failure in scratch tests, but no adhesive failure was observed; moreover doping with HA increased the coating scratch resistance. In vitro tests in SBF revealed enhanced bioactivity of both HA-doped PEO coatings; furthermore, the cell proliferation/morphometric tests showed their good biocompatibility. Fluorescence microscopy revealed a well-organised actin cytoskeleton and focal adhesions in MC3T3-E1 cells cultivated on these substrates. The cell alkaline phosphatase activity in the presence of

  4. Composite plasma electrolytic oxidation to improve the thermal radiation performance and corrosion resistance on an Al substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Donghyun [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Sung, Dahye [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Lee, Junghoon [Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Kim, Yonghwan [Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Chung, Wonsub, E-mail: wschung1@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of)

    2015-12-01

    Highlights: • Composite plasma electrolytic oxidation was performed using dispersed CuO particles in convectional PEO electrolyte. • Thermal radiation performance and corrosion resistance were examined by FT-IR spectroscopy and electrochemical methods, respectively. • Deposited copper oxide on the surface of the Al substrate was enhanced the corrosion resistance and the emissivity compared with the conventional PEO. - Abstract: A composite plasma electrolytic oxidation (PEO) was performed for enhancing the thermal radiation performance and corrosion resistance on an Al alloy by dispersing cupric oxide (CuO) particles in a conventional PEO electrolyte. Cu-based oxides (CuO and Cu{sub 2}O) formed by composite PEO increased the emissivity of the substrate to 0.892, and made the surface being dark color, similar to a black body, i.e., an ideal radiator. In addition, the corrosion resistance was analyzed using potentio-dynamic polarization and electrochemical impedance spectroscopy tests in 3.5 wt.% NaCl aqueous solution. An optimum condition of 10 ampere per square decimeter (ASD) current density and 30 min processing time produced appropriate surface morphologies and coating thicknesses, as well as dense Cu- and Al-based oxides that constituted the coating layers.

  5. Investigation on the corrosion behaviour and microstructure of 2024-T3 Al alloy treated via plasma electrolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Fadaee, Hossein; Javidi, Mehdi, E-mail: mjavidi@yahoo.com

    2014-08-01

    Highlights: • Plasma electrolytic oxidation used to improve corrosion resistance of 2024-T3 alloy. • A conventional DC source with low applied voltage was considered for PEO. • Use of glycerin was effective in enhancement of corrosion resistance. • The surface morphology indicated coatings have a dense structure without cracking. • Degradation of coatings with immersion time was investigated. - Abstract: Plasma electrolytic oxidation treatment was performed on 2024-T3 aluminium alloy in a simple and inexpensive electrolyte. It was found that treatment time of 30 min resulted in the most noble corrosion potential and lowest corrosion current density. The surface and cross-sectional morphology indicated that the coating has a dense structure without any cracking. Furthermore, the result of X-ray diffraction analysis indicated that the coating was formed mainly from α-Al{sub 2}O{sub 3}, γ-Al{sub 2}O{sub 3}, Al{sub 3.21}Si{sub 0.47} and small amounts of amorphous phases. The presence of glycerine in the electrolyte composition resulted in not only stabilising the solution but also improving the corrosion resistance.

  6. Electrical Properties of Atmospheric Plasma-Sprayed La10(SiO4)6O3 Electrolyte Coatings

    Science.gov (United States)

    Gao, Wei; Li, Wen-Ya; Liao, Han-Lin; Coddet, Christian

    2011-06-01

    In this present work, La10(SiO4)6O3 as a promising electrolyte candidate for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been synthesized and its electrical property was investigated as a function of temperature. In order to improve the density and oxide ion conductivity of La10(SiO4)6O3, the feedstock powder was prepared by sintering the oxide mixture powders at proper sintering temperatures and times. The hexagonal apatite-type ceramic coatings with a typical composition of La10(SiO4)6O3 were deposited by atmospheric plasma spraying (APS) with different hydrogen flow rates. With increasing hydrogen flow rate oxide ion conductivity successively decreases. The highest ionic conductivity of the dense composite electrolyte coatings reaches a value of 2.4 mS/cm at 900 °C in air, which is comparable to other apatite-type lanthanum silicate (ATLS) conductors.

  7. Enhanced electrochemical performance of Lithium-ion batteries by conformal coating of polymer electrolyte.

    Science.gov (United States)

    Plylahan, Nareerat; Maria, Sébastien; Phan, Trang Nt; Letiche, Manon; Martinez, Hervé; Courrèges, Cécile; Knauth, Philippe; Djenizian, Thierry

    2014-01-01

    This work reports the conformal coating of poly(poly(ethylene glycol) methyl ether methacrylate) (P(MePEGMA)) polymer electrolyte on highly organized titania nanotubes (TiO2nts) fabricated by electrochemical anodization of Ti foil. The conformal coating was achieved by electropolymerization using cyclic voltammetry technique. The characterization of the polymer electrolyte by proton nuclear magnetic resonance ((1)H NMR) and size-exclusion chromatography (SEC) shows the formation of short polymer chains, mainly trimers. X-ray photoelectron spectroscopy (XPS) results confirm the presence of the polymer and LiTFSI salt. The galvanostatic tests at 1C show that the performance of the half cell against metallic Li foil is improved by 33% when TiO2nts are conformally coated with the polymer electrolyte.

  8. Evaluation of apatite silicates as solid oxide fuel cell electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Marrero-Lopez, D. [Dpto. de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain); Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Martin-Sedeno, M.C.; Aranda, M.A.G. [Dpto. de Quimica Inorganica, Universidad Malaga, 29071 Malaga (Spain); Pena-Martinez, J. [Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Instituto de Energias Renovables, Parque Tecnologico, Universidad de Castilla La Mancha, 02006 Albacete (Spain); Ruiz-Morales, J.C.; Nunez, P. [Dpto. de Quimica Inorganica, Universidad de La Laguna, 38200 La Laguna, Tenerife (Spain); Ramos-Barrado, J.R. [Dpto. de Fisica Aplicada I, Laboratorio de Materiales y Superficies (Unidad Asociada al C.S.I.C.), Universidad de Malaga, 29071 Malaga (Spain)

    2010-05-01

    Apatite-type silicates have been considered as promising electrolytes for Solid Oxide Fuel Cells (SOFC); however studies on the potential use of these materials in SOFC devices have received relatively little attention. The lanthanum silicate with composition La{sub 10}Si{sub 5.5}Al{sub 0.5}O{sub 26.75} has been evaluated as electrolyte with the electrode materials commonly used in SOFC, i.e. manganite, ferrite and cobaltite as cathode materials and NiO-CGO composite, chromium-manganite and Sr{sub 2}MgMoO{sub 6} as anode materials. Chemical compatibility, area-specific resistance and fuel cell studies have been performed. X-ray powder diffraction (XRPD) analysis did not reveal any trace of reaction products between the apatite electrolyte and most of the aforementioned electrode materials. However, the area-specific polarisation resistance (ASR) of these electrodes in contact with apatite electrolyte increased significantly with the sintering temperature, indicating reactivity at the electrolyte/electrode interface. On the other hand, the ASR values are significantly improved using a ceria buffer layer between the electrolyte and electrode materials to prevent reactivity. Maximum power densities of 195 and 65 mWcm{sup -2} were obtained at 850 and 700 C, respectively in H{sub 2} fuel, using an 1 mm-thick electrolyte, a NiO-Ce{sub 0.8}Gd{sub 0.2}O{sub 1.9} composite as anode and La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} as cathode materials. This fuel cell was tested for 100 h in 5%H{sub 2}-Ar atmosphere showing stable performance. (author)

  9. Contact Resistance of Tantalum Coatings in Fuel Cells and Electrolyzers using Acidic Electrolytes at Elevated Temperatures

    DEFF Research Database (Denmark)

    Jensen, Annemette Hindhede; Christensen, Erik; Barner, Jens H. Von

    2014-01-01

    Tantalum has so far been found to be the only construction material with sufficient corrosion resistance for high temperature polymer electrolyte membrane electrolyzers using acidic electrolytes above 100◦C. In this work the interfacial contact resistances of tantalum plates and tantalum coated...... stainless steel were found to be far below the US Department of Energy target value of 10mcm2. The good contact resistance of tantalum was demonstrated by simulating high temperature polymer electrolyte membrane electrolysis conditions by anodization performed in 85% phosphoric acid at 130◦C, followed...

  10. Lithium sulfide compositions for battery electrolyte and battery electrode coatings

    Science.gov (United States)

    Liang, Chengdu; Liu, Zengcai; Fu, Wunjun; Lin, Zhan; Dudney, Nancy J; Howe, Jane Y; Rondinone, Adam J

    2013-12-03

    Methods of forming lithium-containing electrolytes are provided using wet chemical synthesis. In some examples, the lithium containing electroytes are composed of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7. The solid electrolyte may be a core shell material. In one embodiment, the core shell material includes a core of lithium sulfide (Li.sub.2S), a first shell of .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7, and a second shell including one or .beta.-Li.sub.3PS.sub.4 or Li.sub.4P.sub.2S.sub.7 and carbon. The lithium containing electrolytes may be incorporated into wet cell batteries or solid state batteries.

  11. Effects of different electrolytes for micro-arc oxidation on the bond strength between titanium and porcelain.

    Science.gov (United States)

    Yuan, Xiaohui; Tan, Fei; Xu, Haitao; Zhang, Shaojun; Qu, Fuzhen; Liu, Jie

    2017-07-01

    The aim of this study is to investigate the effects of different electrolytes on the titanium-porcelain bond strength after micro-arc oxidation (MAO) treatment. Three electrolytes at the same concentration were used as MAO reaction solutions: Na2SiO3, KF, and MgSiF6. Blasting treatment was chosen as a control. After MAO treatment in each electrolyte, the titanium-porcelain bond strengths were measured by the three-point bending test, as described in ISO 9693. The morphologies and elemental compositions of the MAO coating on the titanium substrate were evaluated by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The interface between the titanium and porcelain was also observed by SEM and EDS. The MAO coatings created in different electrolytes exhibited completely different morphologies and compositions. The bond strengths of the Na2SiO3 and MgSiF6 groups were significantly higher than those of the other groups (ptitanium-porcelain interfaces were compact in the former two groups, whereas pores and cracks were visible at the interfaces in the other groups. These results indicate that MAO treatment with an appropriate electrolyte could be an effective method to increase the titanium-porcelain bonding strength. According to ISO 9693, titanium-porcelain restorations subjected to MAO treatment with an appropriate electrolyte could be appropriate for clinical use. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  12. Electrolytic deposition and corrosion resistance of Zn–Ni coatings ...

    Indian Academy of Sciences (India)

    Administrator

    are meas- ured, and are compared with that of metallic cadmium coating. Structural investigations were performed by the X-ray diffraction (XRD) method. The surface morphology and chemical composition of deposited coatings were studied using a scanning electron microscope (JEOL JSM-6480) with EDS attachment.

  13. Electrolytic deposition and corrosion resistance of Zn–Ni coatings ...

    Indian Academy of Sciences (India)

    Zn–Ni coatings were deposited under galvanostatic conditions on steel substrate (OH18N9). The influence of current density of deposition on the surface morphology, chemical and phase composition was investigated. The corrosion resistance of Zn–Ni coatings obtained at current density 10–25 mA cm-2 are measured, ...

  14. Strength of an electrolyte supported solid oxide fuel cell

    Science.gov (United States)

    Fleischhauer, Felix; Bermejo, Raul; Danzer, Robert; Mai, Andreas; Graule, Thomas; Kuebler, Jakob

    2015-11-01

    For the proper function of solid oxide fuel cells (SOFC) their structural integrity must be maintained during their whole lifetime. Any cell fracture would cause leakage and partial oxidization of the anode, leading to a reduced performance, if not catastrophic failure of the whole stack. In this study, the mechanical strength of a state of the art SOFC, developed and produced by Hexis AG/Switzerland, was investigated with respect to the influence of temperature and ageing, whilst for the anode side of the cell the strength was measured under reducing and oxidizing atmospheres. Ball-on-3-Ball bending strength tests and fractography conducted on anode and cathode half-cells revealed the underlying mechanisms, which lead to cell fracture. They were found to be different for the cathode and the anode side and that they change with temperature and ageing. Both anode and cathode sides exhibit the lowest strength at T = 850 °C, which is greatly reduced to the initial strength of the bare electrolyte. This reduction is the consequence of the formation of cracks in the electrode layer which either directly penetrate into the electrolyte (anode side) or locally increase the stress intensity level of pre-existing flaws of the electrolytes at the interface (cathode side).

  15. Electrolytic CO2 Reduction in Tandem with Oxidative Organic Chemistry.

    Science.gov (United States)

    Li, Tengfei; Cao, Yang; He, Jingfu; Berlinguette, Curtis P

    2017-07-26

    Electrochemical reduction of CO2 into carbon-based products using excess clean electricity is a compelling method for producing sustainable fuels while lowering CO2 emissions. Previous electrolytic CO2 reduction studies all involve dioxygen production at the anode, yet this anodic reaction requires a large overpotential and yields a product bearing no economic value. We report here that the cathodic reduction of CO2 to CO can occur in tandem with the anodic oxidation of organic substrates that bear higher economic value than dioxygen. This claim is demonstrated by 3 h of sustained electrolytic conversion of CO2 into CO at a copper-indium cathode with a current density of 3.7 mA cm-2 and Faradaic efficiency of >70%, and the concomitant oxidation of an alcohol at a platinum anode with >75% yield. These results were tested for four alcohols representing different classes of alcohols and demonstrate electrolytic reduction and oxidative chemistry that form higher-valued carbon-based products at both electrodes.

  16. Wear Protection of AJ62 Mg Engine Blocks using Plasma Electrolytic Oxidation Process

    Science.gov (United States)

    Zhang, Peng

    2011-12-01

    In order to reduce the fuel consumption and pollution, automotive companies are developing magnesium-intensive components. However, due to the low wear resistance of the magnesium (Mg) alloys, Mg cylinder bores are vulnerable to the sliding wear attack. In this thesis, two approaches were used to protect the cylinder bores, made of a new developed Mg engine alloy AJ62 (MgA16Mn0.34Sr2). The first one was to use a Plasma Electrolytic Oxidation (PEO) process to produce oxide coatings on the Mg bores. The wear properties of the PEO coatings were evaluated by sliding wear tests under the boundary lubrication condition at the room and elevated temperatures. It was found that due to the substrate softening and the vaporization loss of the lubricant, the tribological properties of the PEO coatings were deteriorated at the elevated temperature. In order to optimize the PEO process, a statistical method (Response surface method) was used to analyze the effects of the 4 main PEO process parameters with 2 levels for each and their interactions on the tribological properties of the PEO coatings at the room and elevated temperatures, individually. A cylinder liner made of an economical metal-matrix composite (MMC) was another approach to improve the wear resistance of the Mg cylinder bore. In this thesis, an A1383/SiO2 MMC was designed to replace the expensive Alusil alloy used in the BMW Mg/Al composite engine to build the cylinder liner. To further increase the wear resistance of the MMC, PEO process was also used to form an oxide coating on the MMC. The effects of the SiO 2 content and coating thickness on the tribological properties of the MMC were studied. To evaluate the wear properties of the optimal PEO coated Mg coupons and the MMC with the oxide coatings, Alusil and cast iron, currently used on the cylinder bores of the commercial aluminum engines, were used as reference materials. The optimal PEO coated Mg coupons and the oxidized MMC showed their advantages over the

  17. Luminescent Polymer Electrolyte Composites Using Silica Coated-Y2O3:Eu as Fillers

    Directory of Open Access Journals (Sweden)

    Mikrajuddin Abdullah

    2003-05-01

    Full Text Available Luminescent polymer electrolyte composites composed of silica coated Y2O3:Eu in polyethylene glycol (PEG matrix has been produced by initially synthesizing silica coated Y2O3:Eu and mixing with polyethylene glycol in a lithium salt solution. High luminescence intensity at round 600 nm contributed by electron transitions in Eu3+ (5D0 -> 7F0, 5D0 -> 7F1, and 5D0 -> 7F3 transitions were observed. The measured electrical conductivity was comparable to that reported for polymer electrolyte composites prepared using passive fillers (non luminescent. This approach is therefore promising for production of high intensity luminescent polymer electrolyte composites for use in development of hybrid battery/display.

  18. Sound Absorption Characteristics of Aluminum Foams Treated by Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Wei Jin

    2015-11-01

    Full Text Available Open-celled aluminum foams with different pore sizes were fabricated. A plasma electrolytic oxidation (PEO treatment was applied on the aluminum foams to create a layer of ceramic coating. The sound absorption coefficients of the foams were measured by an impedance tube and they were calculated by a transfer function method. The experimental results show that the sound absorption coefficient of the foam increases gradually with the decrease of pore size. Additionally, when the porosity of the foam increases, the sound absorption coefficient also increases. The PEO coating surface is rough and porous, which is beneficial for improvement in sound absorption. After PEO treatment, the maximum sound absorption of the foam is improved to some extent.

  19. Failure analysis of electrolyte-supported solid oxide fuel cells

    Science.gov (United States)

    Fleischhauer, Felix; Tiefenauer, Andreas; Graule, Thomas; Danzer, Robert; Mai, Andreas; Kuebler, Jakob

    2014-07-01

    For solid oxide fuel cells (SOFCs) one key aspect is the structural integrity of the cell and hence its thermo mechanical long term behaviour. The present study investigates the failure mechanisms and the actual causes for fracture of electrolyte supported SOFCs which were run using the current μ-CHP system of Hexis AG, Winterthur - Switzerland under lab conditions or at customer sites for up to 40,000 h. In a first step several operated stacks were demounted for post-mortem inspection, followed by a fractographic evaluation of the failed cells. The respective findings are then set into a larger picture including an analysis of the present stresses acting on the cell like thermal and residual stresses and the measurements regarding the temperature dependent electrolyte strength. For all investigated stacks, the mechanical failure of individual cells can be attributed to locally acting bending loads, which rise due to an inhomogeneous and uneven contact between the metallic interconnect and the cell.

  20. Effects of coating spherical iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Milosevic, Irena; Motte, Laurence; Aoun, Bachir; Li, Tao; Ren, Yang; Sun, Chengjun; Saboungi, Marie-Louise

    2017-01-01

    We investigate the effect of several coatings applied in biomedical applications to iron oxide nanoparticles on the size, structure and composition of the particles. The four structural techniques employed - TEM, DLS, VSM, SAXS and EXAFS - show no significant effects of the coatings on the spherical shape of the bare nanoparticles, the average sizes or the local order around the Fe atoms. The NPs coated with hydroxylmethylene bisphosphonate or catechol have a lower proportion of magnetite than the bare and citrated ones, raising the question whether the former are responsible for increasing the valence state of the oxide on the NP surfaces and lowering the overall proportion of magnetite in the particles. VSM measurements show that these two coatings lead to a slightly higher saturation magnetization than the citrate. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazu and Dr. Federica Migliardo.

  1. Corrosion protection of iron using porous anodic oxide/conducting polymer composite coatings.

    Science.gov (United States)

    Konno, Yoshiki; Tsuji, Etsushi; Aoki, Yoshitaka; Ohtsuka, Toshiaki; Habazaki, Hiroki

    2015-01-01

    Conducting polymers (CPs), including polypyrrole, have attracted attention for their potential in the protection of metals against corrosion; however, CP coatings have the limitation of poor adhesion to metal substrates. In this study, a composite coating, comprising a self-organized porous anodic oxide layer and a polypyrrole layer, has been developed on iron. Because of electropolymerization in the pores of the anodic oxide layer, the composite coating showed improved adhesion to the substrate along with prolonged corrosion protection in a NaCl aqueous corrosive environment. The anodic oxide layers are formed in a fluoride-containing organic electrolyte and contain a large amount of fluoride species. The removal of these fluoride species from the oxide layer and the metal/oxide interface region is crucial for improving the corrosion protection.

  2. Nylon/Graphene Oxide Electrospun Composite Coating

    Directory of Open Access Journals (Sweden)

    Carmina Menchaca-Campos

    2013-01-01

    Full Text Available Graphite oxide is obtained by treating graphite with strong oxidizers. The bulk material disperses in basic solutions yielding graphene oxide. Starting from exfoliated graphite, different treatments were tested to obtain the best graphite oxide conditions, including calcination for two hours at 700°C and ultrasonic agitation in acidic, basic, or peroxide solutions. Bulk particles floating in the solution were filtered, rinsed, and dried. The graphene oxide obtained was characterized under SEM and FTIR techniques. On the other hand, nylon 6-6 has excellent mechanical resistance due to the mutual attraction of its long chains. To take advantage of the properties of both materials, they were combined as a hybrid material. Electrochemical cells were prepared using porous silica as supporting electrode of the electrospun nylon/graphene oxide films for electrochemical testing. Polarization curves were performed to determine the oxidation/reduction potentials under different acidic, alkaline, and peroxide solutions. The oxidation condition was obtained in KOH and the reduction in H2SO4 solutions. Potentiostatic oxidation and reduction curves were applied to further oxidize carbon species and then reduced them, forming the nylon 6-6/functionalized graphene oxide composite coating. Electrochemical impedance measurements were performed to evaluate the coating electrochemical resistance and compared to the silica or nylon samples.

  3. Modification of titanium alloys surface properties by plasma electrolytic oxidation (PEO) and influence on biological response.

    Science.gov (United States)

    Echeverry-Rendón, Mónica; Galvis, Oscar; Aguirre, Robinson; Robledo, Sara; Castaño, Juan Guillermo; Echeverría, Félix

    2017-09-27

    Surface characteristics can mediate biological interaction improving or affecting the tissue integration after implantation of a biomaterial. Features such as topography, wettability, surface energy and chemistry can be key determinants for interactions between cells and materials. Plasma electrolytic oxidation (PEO) is a technique used to control this kind of parameters by the addition of chemical species and the production of different morphologies on the surfaces of titanium and its alloys. With the purpose to improve the biological response, surfaces of c.p titanium and Ti6Al4V were modified by using PEO. Different electrolytes, voltages, current densities and anodizing times were tested in order to obtain surfaces with different characteristics. The obtained materials were characterized by different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and glow discharge optical emission spectroscopy (GDOES). Wettability of the obtained surfaces were measured and the corresponding surface energies were calculated. Superhydrophilic surfaces with contact angles of about 0 degrees were obtained without any other treatment but PEO and this condition in some cases remains stable after several weeks of anodizing; crystal phase composition (anatase-rutile) of the anodic surface appears to be critical for obtaining this property. Finally, in order to verify the biological effect of these surfaces, osteoblast were seeded on the samples. It was found that cell behavior improves as SFE (surface free energy) and coating porosity increases whereas it is affected negatively by roughness. Techniques for surface modification allow changes in the coatings such as surface energy, roughness and porosity. As a consequence of this, biological response can be altered. In this paper, surfaces of c.p Ti and Ti6Al4V were modified by using plasma electrolytic oxidation (PEO) in order to accelerate the cell adhesion process.

  4. Corrosion behavior of plasma electrolytically oxidized gamma titanium aluminide alloy in simulated body fluid

    Science.gov (United States)

    Lara Rodriguez, L.; Sundaram, P.A

    2016-01-01

    Plasma electrolytic oxidized (PEO) γTiAl alloy samples were electrochemically characterized by open circuit potential (OCP), cyclic polarization and electrochemical impedance spectroscopy (EIS) to evaluate their corrosion resistance in simulated body fluid (SBF) in order to gauge their potential for biomedical applications. Experimental results through OCP and cyclic polarization studies demonstrated the protective nature and the beneficial effect of the PEO coatings on γTiAl. The PEO surface increased corrosion resistance of these surface modified alloys. EIS data indicated the presence of an underlying compact oxide layer with surface pores represented by two domes in the Nyquist plots. Electrical equivalent circuits to describe the EIS results are proposed. PMID:27818563

  5. Characterization and mechanical properties of coatings on magnesium by micro arc oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Durdu, Salih, E-mail: sdurdu@gyte.edu.tr [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, Kocaeli, 41400 (Turkey); Usta, Metin [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, Kocaeli, 41400 (Turkey)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The commercial pure magnesium was coated by MAO in sodium silicate and sodium phosphate. Black-Right-Pointing-Pointer Coatings produced in the phosphate electrolyte are thicker than ones in the silicate electrolyte. Black-Right-Pointing-Pointer Coatings in the silicate electrolyte are harder than ones in the phosphate electrolyte. Black-Right-Pointing-Pointer Adhesion strength of coatings increases with increasing coating thickness. Black-Right-Pointing-Pointer The wear resistance of the coated commercial pure magnesium is improved. - Abstracts: The commercial pure magnesium was coated by micro arc oxidation method in different aqueous solution, containing sodium silicate and sodium phosphate. Micro arc oxidation process was carried out at 0.060 A/cm{sup 2}, 0.085 A/cm{sup 2} and 0.140 A/cm{sup 2} current densities for 30 min. The thickness, phase composition, morphology, hardness, adhesion strength and wear resistance of coatings were analyzed by eddy current, X-ray diffraction (XRD), scanning electron microscope (SEM), micro hardness tester, scratch tester and ball-on disk tribometer, respectively. The average thicknesses of the micro arc oxidized coatings ranged from 27 to 48 {mu}m for sodium silicate solution and from 45 to 75 {mu}m for sodium phosphate solution. The dominant phases formed on the pure magnesium were found to be a mixture of spinel Mg{sub 2}SiO{sub 4} (Forsterite) and MgO (Periclase) for sodium silicate solution and Mg{sub 3}(PO{sub 4}){sub 2} (Farringtonite) and MgO (Periclase) for sodium phosphate solution. The average hardnesses of the micro arc oxidized coatings were between 260 HV and 470 HV for sodium silicate solution and between 175 HV and 260 HV for sodium phosphate solution. Adhesion strengths and wear resistances of coatings produced in sodium silicate solution were higher than those of the ones in sodium phosphate solution due to high hardness of coatings produced in sodium silicate solution.

  6. Water oxidation by amorphous cobalt-based oxides: volume activity and proton transfer to electrolyte bases.

    Science.gov (United States)

    Klingan, Katharina; Ringleb, Franziska; Zaharieva, Ivelina; Heidkamp, Jonathan; Chernev, Petko; Gonzalez-Flores, Diego; Risch, Marcel; Fischer, Anna; Dau, Holger

    2014-05-01

    Water oxidation in the neutral pH regime catalyzed by amorphous transition-metal oxides is of high interest in energy science. Crucial determinants of electrocatalytic activity were investigated for a cobalt-based oxide film electrodeposited at various thicknesses on inert electrodes. For water oxidation at low current densities, the turnover frequency (TOF) per cobalt ion of the bulk material stayed fully constant for variation of the thickness of the oxide film by a factor of 100 (from about 15 nm to 1.5 μm). Thickness variation changed neither the nanostructure of the outer film surface nor the atomic structure of the oxide catalyst significantly. These findings imply catalytic activity of the bulk hydrated oxide material. Nonclassical dependence on pH was observed. For buffered electrolytes with pKa values of the buffer base ranging from 4.7 (acetate) to 10.3 (hydrogen carbonate), the catalytic activity reflected the protonation state of the buffer base in the electrolyte solution directly and not the intrinsic catalytic properties of the oxide itself. It is proposed that catalysis of water oxidation occurs within the bulk hydrated oxide film at the margins of cobalt oxide fragments of molecular dimensions. At high current densities, the availability of a proton-accepting base at the catalyst-electrolyte interface controls the rate of water oxidation. The reported findings may be of general relevance for water oxidation catalyzed at moderate pH by amorphous transition-metal oxides. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. 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...

  8. Electrolytic reduction of mixed (Fe, Ti) oxide using molten calcium chloride electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Panigrahi, Mrutyunjay, E-mail: mp@mail.tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aobaku, Sendai 980-8577 (Japan); Iizuka, Atsushi; Shibata, Etsuro; Nakamura, Takashi [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aobaku, Sendai 980-8577 (Japan)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer Tan et al. have electrolyzed mixtures of TiO{sub 2} and Fe{sub 2}O{sub 3} to produce alloys containing Fe-Ti intermetallic phases such as FeTi and Fe{sub 2}Ti using the FFC process. However, the produced alloys have a porous structure with many carbon impurities, e.g., titanium carbide (TiC). Most of the carbon contamination could be caused by the presence of carbon particles in the porous alloy structure. They did not mention any obvious ways of excluding carbon and other impurities, and only suggested that the use of mixed oxides with refined structures or using a single phase, namely ilmenite (FeO{center_dot}TiO{sub 2}), were methods of decreasing impurities in the formed alloys. For future industrialization, there is an urgent need for obvious ways of producing purer Fe-Ti alloys with dense structures, rather than porous structures, as these absorb carbon impurities. Black-Right-Pointing-Pointer Finally, we successfully reduced to a highly purified Fe-Ti intermetallic alloy of FeTi and {beta}-Ti (FeTi{sub 4}) phases. FeTi phases of size around 5-10 {mu}m were dispersed in a matrix of the {beta}-Ti (FeTi{sub 4}) phase. The carbon content of the electrolyzed alloy was as low as less than 0.01 mass%. It was suggested that the dense structure of the alloy of FeTi and {beta}-Ti (FeTi{sub 4}) avoided the inclusion of carbon particle impurities, unlike the porous alloy structure. - Abstract: The production of high-purity metals or alloys using effective technologies is critical for future industrialization. With this aim in mind, a fundamental study of electrolysis in molten CaCl{sub 2} electrolytes was conducted to develop a new production process for ferrotitanium (Fe-Ti) intermetallic alloys. Mixed solid oxides of TiO{sub 2} and Fe{sub 2}O{sub 3} were used in a molar ratio of 5.44:1.00. In this composition of Ti and Fe, FeTi and {beta}-Ti containing iron can co-exist in equilibrium. A mixed solid (Fe, Ti) oxide was reduced

  9. Aggregation Kinetics of Citrate and Polyvinylpyrrolidone Coated Silver Nanoparticles in Monovalent and Divalent Electrolyte Solutions

    Science.gov (United States)

    Huynh, Khanh An; Chen, Kai Loon

    2011-01-01

    The aggregation kinetics of silver nanoparticles (AgNPs) that were coated with two commonly used capping agents—citrate and polyvinylpyrrolidone (PVP)—were investigated. Time-resolved dynamic light scattering (DLS) was employed to measure the aggregation kinetics of the AgNPs over a range of monovalent and divalent electrolyte concentrations. The aggregation behavior of citrate-coated AgNPs in NaCl was in excellent agreement with the predictions based on Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, and the Hamaker constant of citrate-coated AgNPs in aqueous solutions was derived to be 3.7 × 10-20 J. Divalent electrolytes were more efficient in destabilizing the citrate-coated AgNPs, as indicated by the considerably lower critical coagulation concentrations (2.1 mM CaCl2 and 2.7 mM MgCl2 vs. 47.6 mM NaCl). The PVP-coated AgNPs were significantly more stable than citrate-coated AgNPs in both NaCl and CaCl2, which is likely due to steric repulsion imparted by the large, non-charged polymers. The addition of humic acid resulted in the adsorption of the macromolecules on both citrate- and PVP-coated AgNPs. The adsorption of humic acid induced additional electrosteric repulsion that elevated the stability of both nanoparticles in suspensions containing NaCl or low concentrations of CaCl2. Conversely, enhanced aggregation occurred for both nanoparticles at high CaCl2 concentrations due to interparticle bridging by humic acid clusters. PMID:21630686

  10. Prospects for the indirect electrolytic oxidation of organics

    Energy Technology Data Exchange (ETDEWEB)

    Ibl, N.; Kramer, K.; Ponto, L.; Robertson, P.M.

    1978-01-01

    Batch and small continuous pilot-plant tests showed that nearly quantitative yields were obtained in the oxidation of toluene (10% in hexane) to benzaldehyde with cerium(IV) and the electrolytic reoxidation of cerium(III) in perchloric acid. Platinized titanium was the only suitable anode material for the cerium oxidation. An estimate based on a 2000 ton/yr benzaldehyde plant with 31 cells of 91.4 cm radius and 86.4 cm height operating at 1130 amp/sq m for the reagent regeneration showed a total cell cost of $525,000, of which $394,000 was for the platinum and platinization of the anodes, a total investment of $4,250,000, and a total operating cost of $1109/ton benzaldehyde. Oxidation of toluene to benzaldehyde with 0.1 M cobalt(III) in 7 M sulfuric acid gave good yields and permitted the reagent regeneration on lead oxide electrodes. Pilot studies are in progress. Flow diagram, graph, and tables.

  11. Durable rechargeable zinc-air batteries with neutral electrolyte and manganese oxide catalyst

    Science.gov (United States)

    Sumboja, Afriyanti; Ge, Xiaoming; Zheng, Guangyuan; Goh, F. W. Thomas; Hor, T. S. Andy; Zong, Yun; Liu, Zhaolin

    2016-11-01

    Neutral chloride-based electrolyte and directly grown manganese oxide on carbon paper are used as the electrolyte and air cathode respectively for rechargeable Zn-air batteries. Oxygen reduction and oxygen evolution reactions on manganese oxide show dependence of activities on the pH of the electrolyte. Zn-air batteries with chloride-based electrolyte and manganese oxide catalyst exhibit satisfactory voltage profile (discharge and charge voltage of 1 and 2 V at 1 mA cm-2) and excellent cycling stability (≈90 days of continuous cycle test), which is attributed to the reduced carbon corrosion on the air cathode and decreased carbonation in neutral electrolyte. This work describes a robust electrolyte system that improves the cycle life of rechargeable Zn-air batteries.

  12. Direct ceramic inkjet printing of yttria-stabilized zirconia electrolyte layers for anode-supported solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Tomov, R.I.; Hopkins, S.C. [Applied Superconductivity and Cryoscience Group, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB4 3QZ (United Kingdom); Krauz, M.; Kluczowski, J.R. [Institute of Power Engineering, Ceramic Department CEREL, 36-040 Boguchwala (Poland); Jewulski, J. [Institute of Power Engineering, Fuel Cells Department, 02-981 Warsaw (Poland); Glowacka, D.M. [Detector Physics Group, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Glowacki, B.A. [Applied Superconductivity and Cryoscience Group, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB4 3QZ (United Kingdom); Institute of Power Engineering, Fuel Cells Department, 02-981 Warsaw (Poland)

    2010-11-01

    Electromagnetic drop-on-demand direct ceramic inkjet printing (EM/DCIJP) was employed to fabricate dense yttria-stabilized zirconia (YSZ) electrolyte layers on a porous NiO-YSZ anode support from ceramic suspensions. Printing parameters including pressure, nozzle opening time and droplet overlapping were studied in order to optimize the surface quality of the YSZ coating. It was found that moderate overlapping and multiple coatings produce the desired membrane quality. A single fuel cell with a NiO-YSZ/YSZ ({proportional_to}6 {mu}m)/LSM + YSZ/LSM architecture was successfully prepared. The cell was tested using humidified hydrogen as the fuel and ambient air as the oxidant. The cell provided a power density of 170 mW cm{sup -2} at 800 C. Scanning electron microscopy (SEM) revealed a highly coherent dense YSZ electrolyte layer with no open porosity. These results suggest that the EM/DCIJP inkjet printing technique can be successfully implemented to fabricate electrolyte coatings for SOFC thinner than 10 {mu}m and comparable in quality to those fabricated by more conventional ceramic processing methods. (author)

  13. Aluminum Oxide Formation On Fecral Catalyst Support By Electro-Chemical Coating

    Directory of Open Access Journals (Sweden)

    Yang H.S.

    2015-06-01

    Full Text Available FeCrAl is comprised essentially of Fe, Cr, Al and generally considered as metallic substrates for catalyst support because of its advantage in the high-temperature corrosion resistance, high mechanical strength, and ductility. Oxidation film and its adhesion on FeCrAl surface with aluminum are important for catalyst life. Therefore various appropriate surface treatments such as thermal oxidation, Sol, PVD, CVD has studied. In this research, PEO (plasma electrolytic oxidation process was applied to form the aluminum oxide on FeCrAl surface, and the formed oxide particle according to process conditions such as electric energy and oxidation time were investigated. Microstructure and aluminum oxide particle on FeCrAl surface after PEO process was observed by FE-SEM and EDS with element mapping analysis. The study presents possibility of aluminum oxide formation by electro-chemical coating process without any pretreatment of FeCrAl.

  14. Effects of coating spherical iron oxide nanoparticles.

    Science.gov (United States)

    Milosevic, Irena; Motte, Laurence; Aoun, Bachir; Li, Tao; Ren, Yang; Sun, Chengjun; Saboungi, Marie-Louise

    2017-01-01

    We investigate the effect of several coatings applied in biomedical applications to iron oxide nanoparticles on the size, structure and composition of the particles. The four structural techniques employed - TEM, DLS, VSM, SAXS and EXAFS - show no significant effects of the coatings on the spherical shape of the bare nanoparticles, the average sizes or the local order around the Fe atoms. The NPs coated with hydroxylmethylene bisphosphonate or catechol have a lower proportion of magnetite than the bare and citrated ones, raising the question whether the former are responsible for increasing the valence state of the oxide on the NP surfaces and lowering the overall proportion of magnetite in the particles. VSM measurements show that these two coatings lead to a slightly higher saturation magnetization than the citrate. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Superhydrophilicity and antibacterial property of a Cu-dotted oxide coating surface

    Directory of Open Access Journals (Sweden)

    Nie Yining

    2010-09-01

    Full Text Available Abstract Background Aluminum-made settings are widely used in healthcare, schools, public facilities and transit systems. Frequently-touched surfaces of those settings are likely to harbour bacteria and be a potential source of infection. One method to utilize the effectiveness of copper (Cu in eliminating pathogens for these surfaces would be to coat the aluminum (Al items with a Cu coating. However, such a combination of Cu and Al metals is susceptible to galvanic corrosion because of their different electrochemical potentials. Methods In this work, a new approach was proposed in which electrolytic plasma oxidation (EPO of Al was used to form an oxide surface layer followed by electroplating of Cu metal on the top of the oxide layer. The oxide was designed to function as a corrosion protective and biocompatible layer, and the Cu in the form of dots was utilized as an antibacterial material. The antibacterial property enhanced by superhydrophilicity of the Cu-dotted oxide coating was evaluated. Results A superhydrophilic surface was successfully prepared using electrolytic plasma oxidation of aluminum (Al followed by electroplating of copper (Cu in a Cu-dotted form. Both Cu plate and Cu-dotted oxide surfaces had excellent antimicrobial activities against E. coli ATCC 25922, methicillin-resistant Staphylococcus aureus (MRSA ATCC 43300 and vancomycin-resistant Enterococcus faecium (VRE ATCC 51299. However, its Cu-dotted surface morphology allowed the Cu-dotted oxide surface to be more antibacterial than the smooth Cu plate surface. The enhanced antibacterial property was attributed to the superhydrophilic behaviour of the Cu-dotted oxide surface that allowed the bacteria to have a more effective killing contact with Cu due to spreading of the bacterial suspension media. Conclusion The superhydrophilic Cu-dotted oxide coating surface provided an effective method of controlling bacterial growth and survival on contact surfaces and thus reduces the

  16. Biomimetic and electrolytic calcium phosphate coatings on titanium alloy: physicochemical characteristics and cell attachment.

    Science.gov (United States)

    Wang, J; Layrolle, P; Stigter, M; de Groot, K

    2004-02-01

    Biomimetically deposited octacalcium phosphate (OCP) and carbonate apatite (BCA) as well as electrolytically deposited carbonate apatite (ECA) were considered as promising alternatives to conventional plasma spraying hydroxyapatite. This study compared their physicochemical characteristics and cell attachment behavior. The physicochemical characteristics included scanning electron microscopy observation, X-ray diffraction analysis, Fourier transform infrared spectroscopy analysis, surface roughness, coating thickness, dissolution test and scratch test. Cell attachment tests included morphology observation with stereomicroscopy and scanning electron microscopy as well as cell number count with DNA content assay. The OCP coating had 100% crystallinity and was about 40 microm thick, composed of large plate-like crystals of 30 microm, with the lowest surface roughness (R(a)=2.33 microm). The BCA coating had 60% crystallinity and was approximately 30 microm in thickness, composed of small crystals of 1-2 microm in size, with the highest surface roughness (R(a)=4.83 microm). The ECA coating had intermediate characteristics, with 78% crystallinity, 45 microm thickness, crystals of 5-6 microm and an average roughness of 3.87 microm. All coatings could be seen by eyes dissolving quickly and completely into acidic simulated body fluid (simulated physiological solutions-SPS, pH 3.0) but slowly and incompletely into neutral SPS (pH 7.3). It was suggested that the main factor determining coating dissolution in acidic SPS was the solubility isotherm, while some other factors including crystallinity and crystal size joined to determine coating dissolution in neutral SPS. In regard to adhesive strength, results of scratch test showed the critical load at the first crack of coating (L(c1)) was tightly related to crystal size as well as their arrangement, while the critical load at the total delamination of coating (L(c2)) was also related to the coating thickness. The ECA coating

  17. Sodium sulfur container with chromium/chromium oxide coating

    Science.gov (United States)

    Ludwig, Frank A.; Higley, Lin R.

    1981-01-01

    A coating of chromium/chromium oxide is disclosed for coating the surfaces of electrically conducting components of a sodium sulfur battery. This chromium/chromium oxide coating is placed on the surfaces of the electrically conducting components of the battery which are in contact with molten polysulfide and sulfur reactants during battery operation.

  18. Study on Zinc Oxide-Based Electrolytes in Low-Temperature Solid Oxide Fuel Cells.

    Science.gov (United States)

    Xia, Chen; Qiao, Zheng; Feng, Chu; Kim, Jung-Sik; Wang, Baoyuan; Zhu, Bin

    2017-12-28

    Semiconducting-ionic conductors have been recently described as excellent electrolyte membranes for low-temperature operation solid oxide fuel cells (LT-SOFCs). In the present work, two new functional materials based on zinc oxide (ZnO)-a legacy material in semiconductors but exceptionally novel to solid state ionics-are developed as membranes in SOFCs for the first time. The proposed ZnO and ZnO-LCP (La/Pr doped CeO₂) electrolytes are respectively sandwiched between two Ni 0.8 Co 0.15 Al 0.05 Li-oxide (NCAL) electrodes to construct fuel cell devices. The assembled ZnO fuel cell demonstrates encouraging power outputs of 158-482 mW cm -2 and high open circuit voltages (OCVs) of 1-1.06 V at 450-550 °C, while the ZnO-LCP cell delivers significantly enhanced performance with maximum power density of 864 mW cm -2 and OCV of 1.07 V at 550 °C. The conductive properties of the materials are investigated. As a consequence, the ZnO electrolyte and ZnO-LCP composite exhibit extraordinary ionic conductivities of 0.09 and 0.156 S cm -1 at 550 °C, respectively, and the proton conductive behavior of ZnO is verified. Furthermore, performance enhancement of the ZnO-LCP cell is studied by electrochemical impedance spectroscopy (EIS), which is found to be as a result of the significantly reduced grain boundary and electrode polarization resistances. These findings indicate that ZnO is a highly promising alternative semiconducting-ionic membrane to replace the electrolyte materials for advanced LT-SOFCs, which in turn provides a new strategic pathway for the future development of electrolytes.

  19. THE INVESTIGATION OF INFLUENCE OF LASER RADIATION ON THE STRUCTURE AND MECHANICAL PROPERTIES OF COMPOSITE ELECTROLYTIC NICKEL COATING

    Directory of Open Access Journals (Sweden)

    V. A. Zabludovsky

    2013-09-01

    Full Text Available Purpose. Investigation of laser radiation effect on the structure and mechanical properties of electrodeposited nickel composite coatings containing ultrafine diamonds. Methodology. Electrodeposition of nickel films was carried out with the addition of a standard solution of ultrafine diamonds (UFD on laser-electrolytic installation, built on the basis of the gas-discharge CO2 laser. Mechanical testing the durability of coatings were performed on a machine with reciprocating samples in conditions of dry friction against steel. The spectral microanalysis of the elemental composition of the film - substrate was performed on REMMA-102-02. Findings. Research of nickel coatings and modified ultrafine diamond electrodeposited under external stimulation laser demonstrated the dependence of the structure and mechanical properties of composite electrolytic coating (CEC, and the qualitative and quantitative distribution of nanodiamond coprecipitated from an electrodeposition method. Originality. The effect of laser light on the process of co-precipitation of the UFD, which increases the micro-hardness and wear resistance of electrolytic nickel coatings was determined. Practical value. The test method of laser-stimulated composite electrolytic nickel electrodeposition coating is an effective method of local increase in wear resistance of metal coatings, which provides durability save performance (functional properties of the surface.

  20. Antibacterial properties of Ag (or Pt)-containing calcium phosphate coatings formed by micro-arc oxidation.

    Science.gov (United States)

    Song, Won-Hoon; Ryu, Hyun Sam; Hong, Seong-Hyeon

    2009-01-01

    Silver (or platinum)-containing calcium phosphate (hydroxyapatite (HA) and tricalcium phosphate (alpha-TCP)) coatings on titanium substrates were formed by micro-arc oxidation (MAO) and their in vitro antibacterial activity and in vitro cytotoxicity were evaluated. MAO was performed in an electrolytic solution containing beta-glycerophosphate disodium salt pentahydrate (beta-GP) and calcium acetate monohydrate (CA), and Ag and Pt were introduced in the form of AgNO(3) (or CH(3)COOAg) and H(2)PtCl(6), respectively. The MG63 and human osteosarcoma (HOS) cell lines were used to investigate the proliferation and differentiation behavior of the cells, respectively, whereas two strains of bacteria, Staphylococcus aureus and Escherichia coli, were used to evaluate the antibacterial activity of the coatings. The phase, morphology, and Ag content of the coatings were strongly dependent on the applied voltage and Ag precursor concentration. HA and alpha-TCP phases were detected in the coatings oxidized above 400 V and the presence of Ag was confirmed by EDS. While the coatings with a high content of Ag were cytotoxic and those obtained in the Pt-containing electrolyte had no apparent antibacterial activity, the calcium phosphate coatings obtained in the low Ag concentration electrolyte exhibited in vitro antibacterial activity but no cytotoxicity. Thus, biocompatible calcium phosphate coatings on Ti implants with antibacterial activity can be achieved by one-step MAO. 2008 Wiley Periodicals, Inc.

  1. Oxidation behaviour and electrical properties of cobalt/cerium oxide composite coatings for solid oxide fuel cell interconnects

    DEFF Research Database (Denmark)

    Harthøj, Anders; Holt, Tobias; Møller, Per

    2015-01-01

    This work evaluates the performance of cobalt/cerium oxide (Co/CeO2) composite coatings and pure Co coatings to be used for solid oxide fuel cell (SOFC) interconnects. The coatings are electroplated on the ferritic stainless steels Crofer 22 APU and Crofer 22H. Coated and uncoated samples......, Mn, Fe and Cr oxide and the inner layer consisted of Cr oxide. The CeO2 was present as discrete particles in the outer oxide layer after exposure. The Cr oxide layer thicknesses and oxidations rates were significantly reduced for Co/CeO2 coated samples compared to for Co coated and uncoated samples...

  2. High optical and switching performance electrochromic devices based on a zinc oxide nanowire with poly(methyl methacrylate) gel electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Young Tea; Chu, Daping, E-mail: dpc31@cam.ac.uk [Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Neeves, Matthew; Placido, Frank [Thin Film Centre, University of the West of Scotland, Paisley PA1 2BE (United Kingdom); Smithwick, Quinn [Disney Research, 521 Circle Seven Drive, Glendale, Los Angeles, California 91201 (United States)

    2014-11-10

    High performance electrochromic devices have been fabricated and demonstrated utilizing a solid polymer electrolyte and zinc oxide (ZnO) nanowire (NW) array counter electrode. The poly(methyl methacrylate) based polymer electrolyte was spin coated upon hydrothermally grown ZnO NW array counter electrodes, while electron beam evaporated NiO{sub x} thin films formed the working electrodes. Excellent optical contrast and switching speeds were observed in the fabricated devices with active areas of 2 cm{sup 2}, exhibiting an optical contrast of 73.11% at the wavelength of 470 nm, combined with a fast switching time of 0.2 s and 0.4 s for bleaching and coloration, respectively.

  3. Effect of coating density on oxidation resistance and Cr vaporization from solid oxide fuel cell interconnects

    DEFF Research Database (Denmark)

    Talic, Belma; Falk-Windisch, Hannes; Venkatachalam, Vinothini

    2017-01-01

    •Protective action of dense and porous spinel coatings on Crofer 22 APU was compared. •Reduction and re-oxidation produces denser coatings than heat treating in air only. •Coating density has minor influence on oxidation resistance at 800 °C in air. •Dense coating resulted in three times lower Cr...

  4. Real-time imaging, spectroscopy, and structural investigation of cathodic plasma electrolytic oxidation of molybdenum

    Science.gov (United States)

    Stojadinović, Stevan; Tadić, Nenad; Šišović, Nikola M.; Vasilić, Rastko

    2015-06-01

    In this paper, the results of the investigation of cathodic plasma electrolytic oxidation (CPEO) of molybdenum at 160 V in a mixed solution of borax, water, and ethylene glycol are presented. Real-time imaging and optical emission spectroscopy were used for the characterization of the CPEO. During the process, vapor envelope is formed around the cathode and strong electric field within the envelope caused the generation of plasma discharges. The spectral line shape analysis of hydrogen Balmer line Hβ (486.13 nm) shows that plasma discharges are characterized by the electron number density of about 1.4 × 1021 m-3. The electron temperature of 15 000 K was estimated by measuring molybdenum atomic lines intensity. Surface morphology, chemical, and phase composition of coatings formed by CPEO were characterized by scanning electron microscopy with energy dispersive x-ray spectroscopy and x-ray diffraction. The elemental components of CPEO coatings are Mo and O and the predominant crystalline form is MoO3.

  5. Real-time imaging, spectroscopy, and structural investigation of cathodic plasma electrolytic oxidation of molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Stojadinović, Stevan, E-mail: sstevan@ff.bg.ac.rs; Tadić, Nenad; Šišović, Nikola M.; Vasilić, Rastko [Faculty of Physics, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia)

    2015-06-21

    In this paper, the results of the investigation of cathodic plasma electrolytic oxidation (CPEO) of molybdenum at 160 V in a mixed solution of borax, water, and ethylene glycol are presented. Real-time imaging and optical emission spectroscopy were used for the characterization of the CPEO. During the process, vapor envelope is formed around the cathode and strong electric field within the envelope caused the generation of plasma discharges. The spectral line shape analysis of hydrogen Balmer line H{sub β} (486.13 nm) shows that plasma discharges are characterized by the electron number density of about 1.4 × 10{sup 21 }m{sup −3}. The electron temperature of 15 000 K was estimated by measuring molybdenum atomic lines intensity. Surface morphology, chemical, and phase composition of coatings formed by CPEO were characterized by scanning electron microscopy with energy dispersive x-ray spectroscopy and x-ray diffraction. The elemental components of CPEO coatings are Mo and O and the predominant crystalline form is MoO{sub 3}.

  6. Asymmetric supercapacitor based on nanostructured porous manganese oxide and reduced graphene oxide in aqueous neutral electrolyte

    Science.gov (United States)

    Shivakumara, S.; Munichandraiah, N.

    2017-07-01

    A High energy, asymmetric supercapacitor (ASC) has been constructed using porous manganese oxide (MnO2) nanostructures as positive electrode and reduced graphene oxide (RGO) as negative electrode in 1 M Na2SO4 electrolyte. The ASC device exhibits excellent electrochemical performance, when the device is assembled with optimal mass ratio. The energy density is 22.2 W h kg-1 at a power density of 101 W kg-1, when the device is cycled reversibly in the high potential range of 0-2 V. The asymmetric supercapacitor device also exhibits a superior cycling stability with 90% retention of the initial specific capacitance after 3000 cycles.

  7. 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.

  8. The Influence of Electrolytic Concentration on the Electrochemical Deposition of Calcium Phosphate Coating on a Direct Laser Metal Forming Surface

    Directory of Open Access Journals (Sweden)

    Qianyue Sun

    2017-01-01

    Full Text Available A calcium phosphate (CaP coating on titanium surface enhances its biocompatibility, thus facilitating osteoconduction and osteoinduction with the inorganic phase of the human bone. Electrochemical deposition has been suggested as an effective means of fabricating CaP coatings on porous surface. The purpose of this study was to develop CaP coatings on a direct laser metal forming implant using electrochemical deposition and to investigate the effect of electrolytic concentration on the coating’s morphology and structure by X-ray diffraction, scanning electron microscopy, water contact angle analysis, and Fourier transform infrared spectroscopy. In group 10−2, coatings were rich in dicalcium phosphate, characterized to be thick, layered, and disordered plates. In contrast, in groups 10−3 and 10−4, the relatively thin and well-ordered coatings predominantly consisted of granular hydroxyapatite. Further, the hydrophilicity and cell affinity were improved as electrolytic concentration increased. In particular, the cells cultured in group 10−3 appeared to have spindle morphology with thick pseudopodia on CaP coatings; these spindles and pseudopodia strongly adhered to the rough and porous surface. By analyzing and evaluating the surface properties, we provided further knowledge on the electrolytic concentration effect, which will be critical for improving CaP coated Ti implants in the future.

  9. Electrolytic exfoliation of graphite in water with multifunctional electrolytes: en route towards high quality, oxide-free graphene flakes.

    Science.gov (United States)

    Munuera, J M; Paredes, J I; Villar-Rodil, S; Ayán-Varela, M; Martínez-Alonso, A; Tascón, J M D

    2016-02-07

    Electrolytic--usually referred to as electrochemical--exfoliation of graphite in water under anodic potential holds enormous promise as a simple, green and high-yield method for the mass production of graphene, but currently suffers from several drawbacks that hinder its widespread adoption, one of the most critical being the oxidation and subsequent structural degradation of the carbon lattice that is usually associated with such a production process. To overcome this and other limitations, we introduce and implement the concept of multifunctional electrolytes. The latter are amphiphilic anions (mostly polyaromatic hydrocarbons appended with sulfonate groups) that play different relevant roles as (1) an intercalating electrolyte to trigger exfoliation of graphite into graphene flakes, (2) a dispersant to afford stable aqueous colloidal suspensions of the flakes suitable for further use, (3) a sacrificial agent to prevent graphene oxidation during exfoliation and (4) a linker to promote nanoparticle anchoring on the graphene flakes, yielding functional hybrids. The implementation of this strategy with some selected amphiphiles even furnishes anodically exfoliated graphenes of a quality similar to that of flakes produced by direct, ultrasound- or shear-induced exfoliation of graphite in the liquid phase (i.e., almost oxide- and defect-free). These high quality materials were used for the preparation of catalytically efficient graphene-Pt nanoparticle hybrids, as demonstrated by model reactions (reduction of nitroarenes). The multifunctional performance of these electrolytes is also discussed and rationalized, and a mechanistic picture of their oxidation-preventing ability is proposed. Overall, the present results open the prospect of anodic exfoliation as a competitive method for the production of very high quality graphene flakes.

  10. Metallic amorphous electrodeposited molybdenum coating from aqueous electrolyte: Structural, electrical and morphological properties under current density

    Energy Technology Data Exchange (ETDEWEB)

    Nemla, Fatima [LEPCM, Department of Physics, University of Batna (Algeria); Cherrad, Djellal, E-mail: cherradphisic@yahoo.fr [Laboratory for Developing New Materials and Their Characterizations, University of Setif (Algeria)

    2016-07-01

    Graphical abstract: - Highlights: • Although difficulties related to electrodeposition of Mo films, we have successfully coated onto a cooper substrate. • A good formation of bcc Mo phase and lattice parameter was very accurate. • It seems that electrical properties of our samples are good and suitable as back contact for thin film solar cells. • It seems that grain size, microstrain and dislocation density are all managed and correlated to retain the resistivity to a considerable minimum value. - Abstract: Molybdenum coatings are extensively utilized as back contact for CIGS-based solar cells. However, their electrodeposition from aqueous electrolyte still sophisticates, since long time, owing to the high reactivity with oxygen. In this study, we present a successful 30 min electrodeposition experiment of somewhat thick (∼0.98–2.9 μm) and of moderate surface roughness RMS (∼47–58 nm), metallic bright Mo coating from aqueous electrolyte containing molybdate ions. XRD analysis and Hall Effect measurements have been used to confirm the presence of Mo. The crystal structure of deposits was slightly amorphous in nature to body centred cubic structure (bcc) Mo (110), (211) and (220) face. Lattice parameters exhibit some weak fluctuated tensile stress when compared to the reference lattice parameter. Additionally, our calculated lattice parameters are in good agreement with some previous works from literature. Discussions on the grain growth prove that they are constrained by grain boundary energy not the thickness effect. Further discussions were made on the electrical resistivity and surface morphology. Resonance scattering of Fermi electrons are expected to contribute towards the variation in the film resistivity through the carrier mobility limitation. However, studied samples might be qualified as candidates for solar cell application.

  11. Yttria-stabilized zirconia solid oxide electrolyte fuel cells: Monolithic solid oxide fuel cells

    Science.gov (United States)

    1990-10-01

    The monolithic solid oxide fuel cell (MSOFC) is currently under development for a variety of applications including coal-based power generation. The MSOFC is a design concept that places the thin components of a solid oxide fuel cell in lightweight, compact, corrugated structure, and so achieves high efficiency and excellent performance simultaneously with high power density. The MSOFC can be integrated with coal gasification plants and is expected to have high overall efficiency in the conversion of the chemical energy of coal to electrical energy. This report describes work aimed at: (1) assessing manufacturing costs for the MSOFC and system costs for a coal-based plant; (2) modifying electrodes and electrode/electrolyte interfaces to improve the electrochemical performance of the MSOFC; and (3) testing the performance of the MSOFC on hydrogen and simulated coal gas. Manufacturing costs for both the coflow and crossflow MSOFC's were assessed based on the fabrication flow charts developed by direct scaleup of tape calendering and other laboratory processes. Integrated coal-based MSOFC systems were investigated to determine capital costs and costs of electricity. Design criteria were established for a coal-fueled 200-Mw power plant. Four plant arrangements were evaluated, and plant performance was analyzed. Interfacial modification involved modification of electrodes and electrode/electrolyte interfaces to improve the MSOFC electrochemical performance. Work in the cathode and cathode/electrolyte interface was concentrated on modification of electrode porosity, electrode morphology, electrode material, and interfacial bonding. Modifications of the anode and anode/electrolyte interface included the use of additives and improvement of nickel distribution. Single cells have been tested for their electrochemical performance. Performance data were typically obtained with humidified H2 or simulated coal gas and air or oxygen.

  12. Apatite grown in niobium by two-step plasma electrolytic oxidation.

    Science.gov (United States)

    Pereira, Bruno Leandro; Lepienski, Carlos Maurício; Mazzaro, Irineu; Kuromoto, Neide Kazue

    2017-08-01

    Plasma electrolytic oxidation (PEO) of niobium plates were done electrochemically in two steps with electrolytes containing phosphorous and calcium being observed the formation of crystalline apatite. All samples were submitted to a first step of PEO using an electrolyte containing phosphate ions. The second oxidization step was made using three different electrolytes. Some samples were oxidized by PEO in electrolyte containing calcium, while in other samples it was used two mixtures of phosphoric acid and calcium acetate monohydrate solutions. Three different surface layers were obtained. The morphology and chemical composition of the films were analyzed by scanning electronic microscopy (SEM), and energy dispersive spectroscopy (EDS) respectively. It was observed that all samples submitted to two-step oxidation shown porous surface and a calcium and phosphorus rich layer. Average surface roughness (Ra) was measured by a profilometer remaining in the sub-micrometric range. The contact angle by sessile drop technique, using 1μL of distilled water was performed with an optical goniometer. It was verified a higher hydrophilicity in all surfaces compared to the polished niobium. Orthorhombic Nb 2 O 5 was identified by XRD in the oxide layer. Crystalline apatite was identified by XRD in surfaces after the second oxidation made with the Ca-rich electrolyte and a mixture of an electrolyte richer in Ca compared to P. These results indicate that a two-step oxidized niobium surface present great features for applications in the osseointegration processes: favorable chemical composition that increase the biocompatibility, the formation of crystalline niobium pentoxide (orthorhombic), high hydrophilicity and formation of crystalline calcium phosphate (apatite) under adequate electrolyte composition. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Electrolytic exfoliation of graphite in water with multifunctional electrolytes: en route towards high quality, oxide-free graphene flakes

    Science.gov (United States)

    Munuera, J. M.; Paredes, J. I.; Villar-Rodil, S.; Ayán-Varela, M.; Martínez-Alonso, A.; Tascón, J. M. D.

    2016-01-01

    Electrolytic - usually referred to as electrochemical - exfoliation of graphite in water under anodic potential holds enormous promise as a simple, green and high-yield method for the mass production of graphene, but currently suffers from several drawbacks that hinder its widespread adoption, one of the most critical being the oxidation and subsequent structural degradation of the carbon lattice that is usually associated with such a production process. To overcome this and other limitations, we introduce and implement the concept of multifunctional electrolytes. The latter are amphiphilic anions (mostly polyaromatic hydrocarbons appended with sulfonate groups) that play different relevant roles as (1) an intercalating electrolyte to trigger exfoliation of graphite into graphene flakes, (2) a dispersant to afford stable aqueous colloidal suspensions of the flakes suitable for further use, (3) a sacrificial agent to prevent graphene oxidation during exfoliation and (4) a linker to promote nanoparticle anchoring on the graphene flakes, yielding functional hybrids. The implementation of this strategy with some selected amphiphiles even furnishes anodically exfoliated graphenes of a quality similar to that of flakes produced by direct, ultrasound- or shear-induced exfoliation of graphite in the liquid phase (i.e., almost oxide- and defect-free). These high quality materials were used for the preparation of catalytically efficient graphene-Pt nanoparticle hybrids, as demonstrated by model reactions (reduction of nitroarenes). The multifunctional performance of these electrolytes is also discussed and rationalized, and a mechanistic picture of their oxidation-preventing ability is proposed. Overall, the present results open the prospect of anodic exfoliation as a competitive method for the production of very high quality graphene flakes.Electrolytic - usually referred to as electrochemical - exfoliation of graphite in water under anodic potential holds enormous promise

  14. High temperature oxidation of slurry coated interconnect alloys

    DEFF Research Database (Denmark)

    Persson, Åsa Helen

    with this interaction mechanism mainly give a geometrical protection against oxidation by blocking oxygen access at the surface of the oxide scale. The protecting effect is gradually reduced as the oxide scale grows thicker than the diameter of the coating particles. Interaction mechanism B entails a chemical reaction.......85Sr0.15)CoO3 + 10% Co3O4, LSC, coatings were found to be relatively successful in decreasing the oxidation rate, the chromium content in the outermost part of ii the dense scale, and the electrical resistance in the growing oxide scales when applied onto Crofer 22APU. But, the positive effects......In this project, high temperature oxidation experiments of slurry coated ferritic alloys in atmospheres similar to the atmosphere found at the cathode in an SOFC were conducted. From the observations possible interaction mechanisms between the slurry coatings and the growing oxide scale...

  15. Insight into the interaction between layered lithium-rich oxide and additive-containing electrolyte

    Science.gov (United States)

    Tu, Wenqiang; Xia, Pan; Zheng, Xiongwen; Ye, Changchun; Xu, Mengqiang; Li, Weishan

    2017-02-01

    Electrolyte additives have been found to be effective for the cyclic stability improvement of layered lithium-rich oxide (LRO), which is ascribed to the formation of cathode films derived from the preferential oxidation of the electrolyte additives. However, the detailed mechanism on the formation of the cathode film is unclear. This paper uncovers the interaction between LRO and additive-containing electrolyte through theoretical calculations, electrochemical measurements and physical characterizations. A representative LRO, Li1.2Mn0.54Ni0.13Co0.13O2, is synthesized, and an electrolyte, 1 M LiPF6 in EC/DMC (1/2, in volume) using triethyl phosphite (TEP) as additive, is considered. Charge/discharge tests demonstrate that LRO suffers severe capacity fading and TEP can significantly improve the cyclic stability of LRO. Characterizations from SEM and TEM demonstrate that a cathode film exists on the LRO after cycling in the TEP-containing electrolyte. The theoretical calculations suggest that TEP traps the active oxygen and is then oxidized on LRO preferentially compared to the electrolyte, forming the cathode film. The further characterizations from FTIR and GC, confirm that the preferential combination of TEP with active oxygen is beneficial for the suppression of oxygen evolution, and that the resulting cathode film can suppress the electrolyte decomposition and protect LRO from destruction.

  16. Internal oxidation of laminated ternary Ru-Ta-Zr coatings

    Science.gov (United States)

    Chen, Yung-I.; Lu, Tso-Shen

    2015-10-01

    Researchers have observed the internal oxidation phenomenon in binary alloy coatings when developing refractory alloy coatings for protective purposes by conducting annealing at high temperatures and in oxygen-containing atmospheres. The coatings were assembled using cyclical gradient concentration deposition during cosputtering by employing a substrate holder rotating at a slow speed. The internally oxidized zone demonstrated a laminated structure, comprising alternating oxygen-rich and oxygen-deficient layers stacked in a general orientation. In the current study, Ru-Ta-Zr coatings were prepared with various stacking sequences during cosputtering. The Ru-Ta-Zr coatings were annealed at 600 °C in an atmosphere continuously purged with 1% O2-99% Ar mixed gas for 30 min. A transmission electron microscope was used to examine the periods of the laminated layers and crystallinity of the annealed coatings. Depth profiles produced using an Auger electron spectroscope and X-ray photoelectron spectroscope were used to certify the periodic variation of the related constituents and chemical states of the elements, respectively. The results indicate that the internally oxidized ternary coatings are stacked of Ru-, Ta2O5-, and ZrO2-dominant sublayers and that the stacking sequences of the sublayers affect the crystalline structure of the coatings. Zr is oxidized preferentially in the Ru-Ta-Zr coatings, increasing the surface hardness of the oxidized coatings.

  17. Theoretical voltammetric response of electrodes coated by solid polymer electrolyte membranes

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Marín, Ana M. [Departamento de Química y Petróleos, Universidad Nacional de Colombia, Sede Medellín, Medellín (Colombia); Hernández-Ortíz, Juan P., E-mail: jphernandezo@unal.edu.co [Departamento de Materiales, Universidad Nacional de Colombia, Sede Medellín, Medellín (Colombia); Biotechnology Center, University of Wisconsin–Madison, Madison, WI (United States)

    2014-09-24

    Highlights: • Discretized model for an interface of covered electrodes. • Two limiting behaviors are capture: double-layer and conductive interfaces. • Additional phenomena are included easily: acid/base equilibrium, ion mobility. • The model provides explanations to observed phenomena that is vaguely explained in the literature. • Implications on electrodes in fuel cells are given and it opens avenues to understand and design such systems. - Abstract: A model for the differential capacitance of metal electrodes coated by solid polymer electrolyte membranes, with acid/base groups attached to the membrane backbone, and in contact with an electrolyte solution is developed. With proper model parameters, the model is able to predict a limit response, given by Mott–Schottky or Gouy–Chapman–Stern theories depending on the dissociation degree and the density of ionizable acid/base groups. The model is also valid for other ionic membranes with proton donor/acceptor molecules as membrane counterions. Results are discussed in light of the electron transfer rate at membrane-coated electrodes for electrochemical reactions that strongly depend on the double layer structure. In this sense, the model provides a tool towards the understanding of the electro-catalytic activity on modified electrodes. It is shown that local maxima and minima in the differential capacitance as a function of the electrode potential may occur as consequence of the dissociation of acid/base molecular species, in absence of specific adsorption of immobile polymer anions on the electrode surface. Although the model extends the conceptual framework for the interpretation of cyclic voltammograms for these systems and the general theory about electrified interfaces, structural features of real systems are more complex and so, presented results only are qualitatively compared with experiments.

  18. Performance of a novel type of electrolyte-supported solid oxide fuel cell with honeycomb structure

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Morales, Juan Carlos; Savvin, Stanislav N.; Nunez, Pedro [Departmento de Quimica Inorganica, Universidad de La Laguna, 38200 Tenerife (Spain); Marrero-Lopez, David [Departamento de Fisica Aplicada I, Universidad de Malaga, 29071 Malaga (Spain); Pena-Martinez, Juan; Canales-Vazquez, Jesus [Instituto de Energias Renovables-Universidad de Castilla la Mancha, 02006 Albacete (Spain); Roa, Joan Josep; Segarra, Merce [DIOPMA, Departamento de Ciencia de los Materiales e Ing. Metalurgica, 08028 Barcelona (Spain)

    2010-01-15

    A novel design, alternative to the conventional electrolyte-supported solid oxide fuel cell (SOFC) is presented. In this new design, a honeycomb-electrolyte is fabricated from hexagonal cells, providing high mechanical strength to the whole structure and supporting the thin layer used as electrolyte of a SOFC. This new design allows a reduction of {proportional_to}70% of the electrolyte material and it renders modest performances over 320 mW cm{sup -2} but high volumetric power densities, i.e. 1.22 W cm{sup -3} under pure CH{sub 4} at 900 C, with a high OCV of 1.13 V, using the standard Ni-YSZ cermet as anode, Pt as cathode material and air as the oxidant gas. (author)

  19. Picosecond electron injection dynamics in dye-sensitized oxides in the presence of electrolyte

    NARCIS (Netherlands)

    Pijpers, J.J.H.; Ulbricht, R.; Derossi, S.; Reek, J.N.H.; Bonn, M.

    2011-01-01

    We employ time-resolved terahertz (THz) spectroscopy (TRTS) to directly monitor the picosecond dynamics of electron transfer in dye-sensitized oxides in the presence of an electrolyte phase. Understanding the time scale on which electrons are injected from the dye into the oxide phase in the

  20. Electrochemical oxidation of organic carbonate based electrolyte solutions at lithium metal oxide electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Imhof, R.; Novak, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The oxidative decomposition of carbonate based electrolyte solutions at practical lithium metal oxide composite electrodes was studied by differential electrochemical mass spectrometry. For propylene carbonate (PC), CO{sub 2} evolution was detected at LiNiO{sub 2}, LiCoO{sub 2}, and LiMn{sub 2}O{sub 4} composite electrodes. The starting point of gas evolution was 4.2 V vs. Li/Li{sup +} at LiNiO{sub 2}, whereas at LiCoO{sub 2} and LiMn{sub 2}O{sub 4}, CO{sub 2} evolution was only observed above 4.8 V vs. Li/Li{sup +}. In addition, various other volatile electrolyte decomposition products of PC were detected when using LiCoO{sub 2}, LiMn{sub 2}O4, and carbon black electrodes. In ethylene carbonate / dimethyl carbonate, CO{sub 2} evolution was only detected at LiNiO{sub 2} electrodes, again starting at about 4.2 V vs. Li/Li{sup +}. (author) 3 figs., 2 refs.

  1. Enhanced electrochemical stability and charge storage of MnO{sub 2}/carbon nanotubes composite modified by polyaniline coating layer in acidic electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Changzhou; Su, Linghao; Gao, Bo; Zhang, Xiaogang [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing 210016 (China)

    2008-10-15

    Manganese dioxide/multiwalled carbon nanotubes (MnO{sub 2}/MWCNTs) were synthesized by chemically depositing MnO{sub 2} onto the surface of MWCNTs wrapped with poly(sodium-p-styrenesulfonate). Then, polyaniline (PANI) with good supercapacitive performance was further coated onto the MnO{sub 2}/MWCNTs composite to form PANI/MnO{sub 2}/MWCNTs organic-inorganic hybrid nanoarchitecture. Electrochemical performance of the hybrid in Na{sub 2}SO{sub 4}-H{sub 2}SO{sub 4} mixed acidic electrolytes was evaluated by cyclic voltammetry (CV) and chronopotentiometry (CP) in detail. Comparative electrochemical tests revealed that the hybrid nanoarchitecture could operate in the acidic medium due to the protective modification of PANI coating layer onto the MnO{sub 2}/MWCNTs composite, and that its electrochemical behavior was greatly dependent upon the concentration of protons in the acidic electrolytes. Here, PANI not only served as a physical barrier to restrain the underlying MnO{sub 2}/MWCNTs composite from reductive-dissolution process so as to make the novel ternary hybrid material work in acidic medium to enhance the utilization of manganese oxide as much as possible, but also was another electroactive material for energy storage in the acidic mixed electrolytes. It was due to the existence of PNAI layer that an even larger specific capacitance (SC) of 384 F g{sup -1} and a much better SC retention of 79.9% over 1000 continuous charge/discharge cycles than those for the MnO{sub 2}/MWCNTs nanocomposite were delivered for the hybrid in the optimum 0.5 M Na{sub 2}SO{sub 4}-0.5 M H{sub 2}SO{sub 4} mixed acidic electrolyte. (author)

  2. Enhanced electrochemical stability and charge storage of MnO{sub 2}/carbon nanotubes composite modified by polyaniline coating layer in acidic electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Changzhou; Su Linghao; Gao Bo [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing 210016 (China); Zhang Xiaogang [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing 210016 (China)], E-mail: azhangxg@163.com

    2008-10-15

    Manganese dioxide/multiwalled carbon nanotubes (MnO{sub 2}/MWCNTs) were synthesized by chemically depositing MnO{sub 2} onto the surface of MWCNTs wrapped with poly(sodium-p-styrenesulfonate). Then, polyaniline (PANI) with good supercapacitive performance was further coated onto the MnO{sub 2}/MWCNTs composite to form PANI/MnO{sub 2}/MWCNTs organic-inorganic hybrid nanoarchitecture. Electrochemical performance of the hybrid in Na{sub 2}SO{sub 4}-H{sub 2}SO{sub 4} mixed acidic electrolytes was evaluated by cyclic voltammetry (CV) and chronopotentiometry (CP) in detail. Comparative electrochemical tests revealed that the hybrid nanoarchitecture could operate in the acidic medium due to the protective modification of PANI coating layer onto the MnO{sub 2}/MWCNTs composite, and that its electrochemical behavior was greatly dependent upon the concentration of protons in the acidic electrolytes. Here, PANI not only served as a physical barrier to restrain the underlying MnO{sub 2}/MWCNTs composite from reductive-dissolution process so as to make the novel ternary hybrid material work in acidic medium to enhance the utilization of manganese oxide as much as possible, but also was another electroactive material for energy storage in the acidic mixed electrolytes. It was due to the existence of PNAI layer that an even larger specific capacitance (SC) of 384 F g{sup -1} and a much better SC retention of 79.9% over 1000 continuous charge/discharge cycles than those for the MnO{sub 2}/MWCNTs nanocomposite were delivered for the hybrid in the optimum 0.5 M Na{sub 2}SO{sub 4}-0.5 M H{sub 2}SO{sub 4} mixed acidic electrolyte.

  3. Lead-Free Sn-Ce-O Composite Coating on Cu Produced by Pulse Electrodeposition from an Aqueous Acidic Sulfate Electrolyte

    Science.gov (United States)

    Sharma, Ashutosh; Das, Karabi; Das, Siddhartha

    2017-10-01

    Pulse-electrodeposited Sn-Ce-O composite solder coatings were synthesized on a Cu substrate from an aqueous acidic solution containing stannous sulfate (SnSO4·3H2O), sulfuric acid (H2SO4), and Triton X-100 as an additive. The codeposition was achieved by adding nano-cerium oxide powder in varying concentrations from 5 g/L to 20 g/L into the electrolytic bath. Microstructural characterization was carried out using x-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy. The XRD analysis showed that the deposits consist mainly of tetragonal β (Sn) with reduced cerium oxide species. The composite coatings thus obtained exhibit a smaller grain size, possess higher microhardness, and a lower melting point than the monolithic Sn coating. The electrical resistivity of the developed composites increases, however, but lies within the permissible limits for current lead-free solder applications. Also, an optimum balance of properties in terms of microhardness, adhesion, melting point and resistivity can be obtained with 0.9 wt.% cerium oxide in the Sn matrix, which enables potential applications in solder joints and packaging.

  4. The Infulence of Microarc Oxidation Method Modes on the Properties of Coatings

    Directory of Open Access Journals (Sweden)

    N.Y. Dudareva

    2014-07-01

    Full Text Available The experimental studies of the properties of the hardened surface layer, developed by the microarc oxidation method (MAO on the surface of Al-Si ingots from AK12D alloy have been presented here. The effect of concentration of the electrolyte components on the properties of the MAO coating, such as microhardness, thickness, porosity have been studied. The corresponding regression equations to estimate the influence of the process parameters on the quality of the developed MAO-layer, have been set up.

  5. Direct measurement of interaction forces between bovine serum albumin and poly(ethylene oxide in water and electrolyte solutions.

    Directory of Open Access Journals (Sweden)

    Sergio M Acuña

    Full Text Available The net interaction between a probe tip coated with bovine serum albumin (BSA protein and a flat substrate coated with poly(ethylene oxide (PEO polymer was measured directly on approach in water and electrolyte solutions using AFM. The approach force curve between the two surfaces was monotonically repulsive in water and in electrolyte solutions. At pH ~5, slightly above the isoelectric point (pI of BSA, and at large distances, the force was dominated by electrostatic repulsion between the oxygen atoms of the incoming protein with those belonging to the ether groups of PEO. Such repulsive force and range decreased in NaCl. Under physiological conditions, pH 6, BSA is definitely charged and the electrostatic repulsion with ether groups in PEO appears at larger separation distances. Interestingly, at pH 4, below the pI of BSA, the repulsion decreased because of an attractive, although weak, electrostatic force that appeared between the ether groups in PEO and the positively charged amino groups of BSA. However, for all solution conditions, once compression of PEO begun, the net repulsion was always dominated by short-range polymeric steric repulsion and repulsive enthalpy penalties for breaking PEO-water bonds. Results suggest that PEO in mushroom conformation may also be effective in reducing biofouling.

  6. Direct measurement of interaction forces between bovine serum albumin and poly(ethylene oxide) in water and electrolyte solutions

    Science.gov (United States)

    Bastías, José M.; Toledo, Pedro G.

    2017-01-01

    The net interaction between a probe tip coated with bovine serum albumin (BSA) protein and a flat substrate coated with poly(ethylene oxide) (PEO) polymer was measured directly on approach in water and electrolyte solutions using AFM. The approach force curve between the two surfaces was monotonically repulsive in water and in electrolyte solutions. At pH ~5, slightly above the isoelectric point (pI) of BSA, and at large distances, the force was dominated by electrostatic repulsion between the oxygen atoms of the incoming protein with those belonging to the ether groups of PEO. Such repulsive force and range decreased in NaCl. Under physiological conditions, pH 6, BSA is definitely charged and the electrostatic repulsion with ether groups in PEO appears at larger separation distances. Interestingly, at pH 4, below the pI of BSA, the repulsion decreased because of an attractive, although weak, electrostatic force that appeared between the ether groups in PEO and the positively charged amino groups of BSA. However, for all solution conditions, once compression of PEO begun, the net repulsion was always dominated by short-range polymeric steric repulsion and repulsive enthalpy penalties for breaking PEO-water bonds. Results suggest that PEO in mushroom conformation may also be effective in reducing biofouling. PMID:28296940

  7. The Study on the Overall Plasma Electrolytic Oxidation for 6061–7075 Dissimilar Aluminum Alloy Welded Parts Based on the Dielectric Breakdown Theory

    Science.gov (United States)

    Song, Xiaocun; Zhou, Jixue; Liu, Hongtao; Yang, Yuansheng

    2018-01-01

    Electrical connection of dissimilar metals will lead to galvanic corrosion. Therefore, overall surface treatment is necessary for the protection of dissimilar metal welded parts. However, serious unbalanced reactions may occur during overall surface treatment, which makes it difficult to prepare integral coating. In this paper, an overall ceramic coating was fabricated by plasma electrolytic oxidation to wrap the 6061–7075 welded part integrally. Moreover, the growth mechanism of the coating on different areas of the welded part was studied based on the dielectric breakdown theory. The reaction sequence of each area during the treatment was verified through specially designed dielectric breakdown tests. The results showed that the high impedance overall of ceramic coating can inhibit the galvanic corrosion of the 6061–7075 welded part effectively. PMID:29301306

  8. Coatings for Oxidation and Hot Corrosion Protection of Disk Alloys

    Science.gov (United States)

    Nesbitt, Jim; Gabb, Tim; Draper, Sue; Miller, Bob; Locci, Ivan; Sudbrack, Chantal

    2017-01-01

    Increasing temperatures in aero gas turbines is resulting in oxidation and hot corrosion attack of turbine disks. Since disks are sensitive to low cycle fatigue (LCF), any environmental attack, and especially hot corrosion pitting, can potentially seriously degrade the life of the disk. Application of metallic coatings are one means of protecting disk alloys from this environmental attack. However, simply the presence of a metallic coating, even without environmental exposure, can degrade the LCF life of a disk alloy. Therefore, coatings must be designed which are not only resistant to oxidation and corrosion attack, but must not significantly degrade the LCF life of the alloy. Three different Ni-Cr coating compositions (29, 35.5, 45wt. Cr) were applied at two thicknesses by Plasma Enhanced Magnetron Sputtering (PEMS) to two similar Ni-based disk alloys. One coating also received a thin ZrO2 overcoat. The coated samples were also given a short oxidation exposure in a low PO2 environment to encourage chromia scale formation. Without further environmental exposure, the LCF life of the coated samples, evaluated at 760C, was less than that of uncoated samples. Hence, application of the coating alone degraded the LCF life of the disk alloy. Since shot peening is commonly employed to improve LCF life, the effect of shot peening the coated and uncoated surface was also evaluated. For all cases, shot peening improved the LCF life of the coated samples. Coated and uncoated samples were shot peened and given environmental exposures consisting of 500 hrs of oxidation followed by 50 hrs of hot corrosion, both at 760C). The high-Cr coating showed the best LCF life after the environmental exposures. Results of the LCF testing and post-test characterization of the various coatings will be presented and future research directions discussed.

  9. Interaction mechanisms between slurry coatings and solid oxide fuel cell interconnect alloys during high temperature oxidation

    DEFF Research Database (Denmark)

    Persson, Åsa Helen; Mikkelsen, L.; Hendriksen, P.V.

    2012-01-01

    oxidation rate constant was reduced with 50–90% of that for uncoated alloy. One coating consisting of MnCo2O4 did not significantly affect the oxidation rate of the alloy, and just as for uncoated samples break-away oxidation occurred for MnCo2O4 coated samples. The interaction mechanisms between...

  10. Microstructure and antibacterial properties of Cu-doped TiO2 coating on titanium by micro-arc oxidation

    Science.gov (United States)

    Yao, Xiaohong; Zhang, Xiangyu; Wu, Haibo; Tian, Linhai; Ma, Yong; Tang, Bin

    2014-02-01

    Infection associated with titanium implants remains the most common serious complication after surgery. In this work, Cu-doped antibacterial TiO2 coating was synthesized by micro-arc oxidation of titanium in an electrolyte bearing Cu nanoparticles. Surface morphology and structure of the coating were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results indicated that Cu nanoparticles were not only distributed on the surface and inside the pores but also embedded in the coating. Cu mainly exists in the Cu2+ state in the TiO2 coating. The Cu-doped coating exhibited excellent antibacterial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).

  11. Inactivation of Pseudomonas aeruginosa by Chitosan Coated Iron Oxide Nanoparticles.

    Science.gov (United States)

    Mukherjee, Munmun; De, Sirshendu

    2016-01-01

    Pseudomonas aeruginosa is one of the potent opportunistic pathogens associated with respiratory and urinary tract infection. The bacterium owes its pathogenicity due to the intrinsic resistance to antibiotics and disinfectants. The present study is focused on the synthesis of antibacterial chitosan coated iron oxide nanoparticles for rapid inactivation of Pseudomonas aeruginosa. We have discussed the relevant patents on synthesis and antibacterial potential of metallic nanoparticles and chitosan. Chitosan coated iron oxide nanoparticles were synthesized by coprecipitation method at room temperature using non-toxic chitosan and iron salts in alkali media. The particles were characterized and evaluated for antibacterial property against Pseudomonas aeruginosa. The average size of the particles was measured as 52 nm. The surface area of the coated particles was as high as 90 ±5 m2/g. FTIR spectra confirmed the coating of chitosan on nanoparticles. The coated particles showed excellent antibacterial activity against the bacteria. The minimum inhibitory concentration of the coated particles was 105)µg mol-1. The morphological alteration and cytoplasmic leakage of bacteria were confirmed by SEM image and release of intracellular constituents, respectively. Higher 260 nm absorbance value confirmed stronger antibacterial activity of the coated nanoparticles as compared to pure chitosan and bare iron oxide nanoparticles. The study indicated that chitosan coated iron oxide nanoparticles have superior antibacterial property as compared to pure chitosan and iron oxide nanoparticles.

  12. The n-MAO/EPD bio-ceramic composite coating fabricated on ZK60 magnesium alloy using combined micro-arc oxidation with electrophoretic deposition

    Science.gov (United States)

    Xiong, Ying; Lu, Chao; Wang, Chao; Song, Renguo

    2014-12-01

    A bio-ceramic composite coating was fabricated on ZK60 magnesium (Mg) alloy using combined micro-arc oxidation (MAO) with electrophoretic deposition (EPD) technique. The MAO coating as the basal layer was produced in alkaline electrolyte with (n-MAO coating) and without (MAO coating) the addition of CeO2 and ZrO2 nano-particles, respectively. A hydroxyapatite (HA) coating as the covering layer was deposited on the n-MAO coating to improve the biological properties of the coating (n-MAO/EPD composite coating). The morphology and phase composition of three treated coatings were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). The corrosion resistance of these coatings was evaluated with potentiodynamic polarization tests and immersion tests in simulated body fluid (SBF) at 36.5 ± 0.5 °C. The XRD spectra showed that the CeO2 and ZrO2 peaks can be collected in the n-MAO coating, and HA particles exists in the n-MAO/EPD composite coating. The results of corrosion tests indicated that the n-MAO/EPD composite coating owned increased bioactivity and long-term protective ability compared with the MAO coating and the n-MAO coating. Thus Mg alloy coated with the n-MAO/EPD composite coating should be more suited as biodegradable bone implants.

  13. 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.

  14. Studies on broad spectrum corrosion resistant oxide coatings

    Indian Academy of Sciences (India)

    The corrosion resistant oxide coatings, developed and applied by the conventional vitreous enamelling techniques, showed superior resistance to a range of mineral acids at various strengths and temperatures, alkaline solutions, boiling water and chrome plating solutions. These coatings possess considerable abrasion ...

  15. Mechanical Properties of Glass Surfaces Coated with Tin Oxide

    DEFF Research Database (Denmark)

    Swindlehurst, W. E.; Cantor, B.

    1978-01-01

    The effect of tin oxide coatings on the coefficient of friction and fracture strength of glass surfaces is studied. Experiments were performed partly on commercially treated glass bottles and partly on laboratory prepared microscope slides. Coatings were applied in the laboratory by decomposition...

  16. Sol-Gel Derived, Nanostructured Oxide Lubricant Coatings

    National Research Council Canada - National Science Library

    Taylor, Douglas

    2000-01-01

    In this program, we deposited oxide coatings of titanium and nickel by wet-chemical deposition methods, also referred to as sol-gel, which showed excellent tribological properties in previous investigations...

  17. Electrolyte induced rheological modulation of graphene oxide suspensions and its applications in adsorption

    Science.gov (United States)

    Ojha, Abhijeet; Thareja, Prachi

    2018-03-01

    In this study, we report the microstructure, rheology and adsorption characteristics of aqueous suspensions of Graphene Oxide (GO) at a volume fraction (ϕGO) = 0.018, which can be transformed into gels by cation induced charge shielding and cross-linking between GO nanosheets. GO nanosheets of average thickness ∼1.5 nm and a lateral dimension of ∼750 nm are synthesized by Hummer's process. At ϕGO= 0.018, cations of varying size and valence are systematically introduced with electrolytes NH4Cl, LiCl, NaCl, KCl, MgCl2 and FeCl3 at concentrations ranging from 10-5-10-1 M to investigate their effect on the rheology of GO suspensions. Our results suggest that depending on the electrolyte concentration, size and the valence of the cation: low viscosity suspensions, fragile gels and solid-like GO-electrolyte gels are formed. The storage modulus (G') of all GO-electrolyte gels increases with the increase in electrolyte concentration and G' follows the order GO-FeCl3 > GO-MgCl2> GO-KCl > GO-NaCl > GO-LiCl > GO-NH4Cl. FESEM analysis shows that lyophilized GO-electrolyte gels with 10-1 M electrolytes have a porous morphology resulting from the aggregation of GO nanosheets. The GO-electrolyte gels are shown to adsorb high quantities of oils, with GO-FeCl3 gels showing a higher adsorption capacity. The GO-NaCl and GO-FeCl3 lyophilized gels are also shown to adsorb methylene blue dye and follow the pseudo-second-order kinetics of adsorption. Along with higher oil and dye adsorption efficiency, GO-electrolyte gels are easy to recollect after the adsorption, thus avoiding the potential toxicity for bio-organisms in water caused by GO nanosheets.

  18. Enhanced photothermal effect of plasmonic nanoparticles coated with reduced graphene oxide.

    Science.gov (United States)

    Lim, Dong-Kwon; Barhoumi, Aoune; Wylie, Ryan G; Reznor, Gally; Langer, Robert S; Kohane, Daniel S

    2013-09-11

    We report plasmonic gold nanoshells and nanorods coated with reduced graphene oxide that produce an enhanced photothermal effect when stimulated by near-infrared (NIR) light. Electrostatic interactions between nanosized graphene oxide and gold nanoparticles followed by in situ chemical reduction generated reduced graphene oxide-coated nanoparticles; the coating was demonstrated using Raman and HR-TEM. Reduced graphene oxide-coated gold nanoparticles showed enhanced photothermal effect compared to noncoated or nonreduced graphene oxide-coated gold nanoparticles. Reduced graphene oxide-coated gold nanoparticles killed cells more rapidly than did noncoated or nonreduced graphene oxide-coated gold nanoparticles.

  19. Influence of thermal spraying parameters on the corrosion resistance of aluminium oxide coatings deposited on steel 1020

    Science.gov (United States)

    Salas, Y.; Vera, E.; Moreno, M.; Pineda, Y.

    2016-02-01

    Parameters required for the preparation of coatings of aluminium oxide deposited on AISI 1020 steels were determined according to their thickness and type of flame to differentiate their behaviour against corrosion. Commercial powders were used by the method of thermal spraying deposition. The coatings were analysed by OM (optical microscopy), the thickness was measured by means of a coating thickness gauge and electrochemical techniques variables measured was the Linear Polarization Resistance (LPR) and approximation Tafel potentiodynamic curves. The corrosion current for steel 1020 with Na2SO4 electrolyte of 3.5% is of the order of hundreds of A/cm2 and coated steel given in the order of A/cm2, which leads to think that the projection produces coatings uniform low closed porosity, although techniques DC indicate a significant porosity as is observable current response to the potentiodynamic curve. The observed thicknesses fall into the hundreds of microns and little uniformity was noted in this coatings. The coatings deposited by oxidizing flame was better performance in corrosion than the coating deposited by neutral flame.

  20. In vitro studying corrosion behavior of porous titanium coating in dynamic electrolyte.

    Science.gov (United States)

    Chen, Xuedan; Fu, Qingshan; Jin, Yongzhong; Li, Mingtian; Yang, Ruisong; Cui, Xuejun; Gong, Min

    2017-01-01

    Porous titanium (PT) is considered as a promising biomaterials for orthopedic implants. Besides biocompatibility and mechanical properties, corrosion resistance in physiological environment is the other important factor affecting the long stability of an implant. In order to investigate the corrosion behavior of porous titanium implants in a dynamic physiological environment, a dynamic circle system was designed in this study. Then a titanium-based implant with PT coating was fabricated by plasma spraying. The corrosion resistance of PT samples in flowing 0.9% NaCl solution was evaluated by electrochemical measurements. Commercial pure solid titanium (ST) disc was used as a control. The studies of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) show that the pores in the PT play a negetive part in corrosion resistance and the flowing electrolyte can increase the corrosive rate of all titanium samples. The results suggest that pore design of titanium implants should pay attention to the effect of dynamic process of a physiological environment on the corrosion behavior of implants. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. The effects of plasma electrolytically oxidized NiTi on in vitro endothelialization

    NARCIS (Netherlands)

    Huan, Z.; Yu, H.; Li, H.; Ruiter, M. S.; Chang, J.; Apachitei, I.; Duszczyk, J.; de Vries, C. J. M.; Fratila-Apachitei, L. E.

    2016-01-01

    The role of biomaterials surface in controlling the interfacial biological events leading to implant integration is of key importance. In this study, the effects of NiTi surfaces treated by plasma electrolytic oxidation (PEO) on human umbilical vein endothelial cells (HUVECs) have been investigated.

  2. Fermi Potential across Working Solid Oxide Cells with Zirconia or Ceria Electrolytes

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2014-01-01

    observed for ceria based electrolytes, but also in case of solid oxide electrolyser cells (SOEC) with yttria stabilized zirconia (YSZ) big electronic leak currents have been observed for very high overvoltages on one or both electrodes. Furthermore, it is important to realize that the potential gradient...

  3. Optimum antireflection coating for Antireflection-coated Metal-Oxide-Semiconductor /AMOS/ solar cells

    Science.gov (United States)

    Yeh, Y. C. M.; Ernest, F. P.; Stirn, R. J.

    1977-01-01

    Consideration is given to the design of a single-layer optimum antireflection coating for AMOS (antireflection-coated metal-oxide-semiconductor) solar cells to match the entire sunlight spectrum. The energy conversion efficiency is maximized by maximizing the open-circuit voltage and the short-circuit current. The former is maximized by oxidation techniques and the latter is maximized by the light-coupling into the solar cell. With reference to the effective index of refraction as obtained by ellipsometry, examples of optimum antireflection coatings for 60-A Au-GaAs solar cells are presented.

  4. Carbon nanotubes-polyethylene oxide composite electrolyte for solid-state dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shaheer Akhtar, M. [School of Semiconductor and Chemical Engineering and Solar Energy Research Center, Chonbuk National University, Dukjin dong, Dukjin Gu, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Semiconductor Science and Technology, SPRC, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Park, Jung-Geun; Lee, Hyun-Cheol [School of Semiconductor and Chemical Engineering and Solar Energy Research Center, Chonbuk National University, Dukjin dong, Dukjin Gu, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Lee, S.-K. [Department of Semiconductor Science and Technology, SPRC, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Yang, O-Bong, E-mail: obyang@chonbuk.ac.k [School of Semiconductor and Chemical Engineering and Solar Energy Research Center, Chonbuk National University, Dukjin dong, Dukjin Gu, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

    2010-02-28

    Novel carbon nanotubes (CNTs)-polyethylene oxide (PEO) composite electrolyte for dye-sensitized solar cell (DSSC) was prepared and characterized for the first time. The strong bonding and interaction between CNTs and PEO in CNTs-PEO composites was observed by the characterization of X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Raman spectra. The introduction of CNTs into PEO matrix significantly improved the electrolyte properties of DSSC such as roughness, amorphicity and ionic conductivity. The solid-state DSSC fabricated with the optimum composite electrolyte (added 1% CNTs in PEO matrix, 1%CNT-PEO) achieved maximum conversion efficiency of 3.5%, an open circuit voltage (V{sub OC}) of 0.589 V, short circuit current density (J{sub SC}) of 10.64 mA/cm{sup 2} and fill factor (FF) of 56%. The highest IPCE in the DSSC fabricated with 1%CNT-PEO electrolyte is ascribed to the improved ionic conductivity of composite electrolytes and enhanced interfacial contact between electrode and electrolyte.

  5. Microwave assisted sintering of gadolinium doped barium cerate electrolyte for intermediate temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Arumugam Senthil, E-mail: senthu.ramp@gmail.com [Department of Physics, PSG College of Technology, Coimbatore, 641 004, Tamilnadu (India); Balaji, Ramamoorthy [Department of Physics, PSG College of Technology, Coimbatore, 641 004, Tamilnadu (India); Jayakumar, Srinivasalu [Department of Physics, PSG Institute of Technology and Applied Research, Coimbatore, 641 062, Tamilnadu (India); Pradeep, Chandran [Department of Physics, Indian Institute of Technology, Madras, 600 036, Tamilnadu (India)

    2016-10-01

    In Solid Oxide Fuel Cell (SOFC), electrolyte plays a vital role to increase the energy conversion efficiency. The main hurdle of such electrolyte in fuel cell is its higher operating temperature (1000 °C) which results in design limitation and higher fabrication cost. In order to reduce the operating temperature of SOFC, a suitable electrolyte has been prepared through co-precipitation method followed by microwave sintering of solid ceramic. The calcination temperature for the as-prepared powder was identified using Differential Scanning Calorimetry. The crystal structure of the sample was found to exhibit its orthorhombic perovskite structure. The particle size was determined using High-Resolution Transmission Electron Microscope with uniform in shape and size, match with XRD results and confirmed from structural analysis. Thus, the sample prepared via co-precipitation method and the solid ceramic sintered through microwave can be a promising electrolyte for fuel cells operated at intermediate temperature. - Highlights: • To synthesis the composite electrolyte by chemical method and sinter using microwave. • To reduce the operating temperature of electrolyte for high ionic conductivity in SOFC's. • To study the phase purity and to develop nanocomposite at reduced temperature.

  6. Solvothermal synthesis of gallium-indium-zinc-oxide nanoparticles for electrolyte-gated transistors.

    Science.gov (United States)

    Santos, Lídia; Nunes, Daniela; Calmeiro, Tomás; Branquinho, Rita; Salgueiro, Daniela; Barquinha, Pedro; Pereira, Luís; Martins, Rodrigo; Fortunato, Elvira

    2015-01-14

    Solution-processed field-effect transistors are strategic building blocks when considering low-cost sustainable flexible electronics. Nevertheless, some challenges (e.g., processing temperature, reliability, reproducibility in large areas, and cost effectiveness) are requirements that must be surpassed in order to achieve high-performance transistors. The present work reports electrolyte-gated transistors using as channel layer gallium-indium-zinc-oxide nanoparticles produced by solvothermal synthesis combined with a solid-state electrolyte based on aqueous dispersions of vinyl acetate stabilized with cellulose derivatives, acrylic acid ester in styrene and lithium perchlorate. The devices fabricated using this approach display a ION/IOFF up to 1 × 10(6), threshold voltage (VTh) of 0.3-1.9 V, and mobility up to 1 cm(2)/(V s), as a function of gallium-indium-zinc-oxide ink formulation and two different annealing temperatures. These results validates the usage of electrolyte-gated transistors as a viable and promising alternative for nanoparticle based semiconductor devices as the electrolyte improves the interface and promotes a more efficient step coverage of the channel layer, reducing the operating voltage when compared with conventional dielectrics gating. Moreover, it is shown that by controlling the applied gate potential, the operation mechanism of the electrolyte-gated transistors can be modified from electric double layer to electrochemical doping.

  7. Ultra-thin solution-based coating of molybdenum oxide on multiwall carbon nanotubes for high-performance supercapacitor electrodes

    KAUST Repository

    Shakir, Imran

    2014-02-01

    Uniform and conformal coating of ultrathin molybdenum oxide (MoO 3) thin film onto conducting MWCNTs was successfully synthesized through a facile, nontoxic and generally applicable precipitation method, followed by a simple heat treatment. The ultrathin MoO3 coating enables a fast and reversible redox reaction which improves the specific capacitance by utilizing the maximum number of active sites for the redox reaction, while the high porosity of the MWCNTs facilitates ion migration in the electrolyte and shorten the ion diffusion path. The ultrathin MoO3 coated MWCNTs electrodes show a very high specific capacitance of 1145 Fg -1 in 2 M Na2SO4 aqueous solution when 5 nm thick MoO3 was considered alone despite the low weight percentage of the MoO3 (16wt%). Furthermore, the ultrathin MoO3 coated MWCNTs supercapacitor electrodes exhibited excellent cycling performance of > 97% capacitance retention over 1000 cycles. © 2013 Elsevier Ltd.

  8. Antibacterial activity of zinc oxide-coated nanoporous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Skoog, S.A. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Bayati, M.R. [Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States); Petrochenko, P.E. [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Division of Biology, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD 20993 (United States); Stafslien, S.; Daniels, J.; Cilz, N. [Center for Nanoscale Science and Engineering, North Dakota State University, 1805 Research Park Drive, Fargo, ND 58102 (United States); Comstock, D.J.; Elam, J.W. [Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Narayan, R.J., E-mail: roger_narayan@msn.com [Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Box 7115, Raleigh, NC 27695-7115 (United States); Department of Materials Science and Engineering, North Carolina State University, Box 7907, Raleigh, NC 27695-7907 (United States)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer Atomic layer deposition was used to deposit ZnO on nanoporous alumina membranes. Black-Right-Pointing-Pointer Scanning electron microscopy showed continuous coatings of zinc oxide nanocrystals. Black-Right-Pointing-Pointer Activity against B. subtilis, E. coli, S. aureus, and S. epidermidis was shown. - Abstract: Nanoporous alumina membranes, also known as anodized aluminum oxide membranes, are being investigated for use in treatment of burn injuries and other skin wounds. In this study, atomic layer deposition was used for coating the surfaces of nanoporous alumina membranes with zinc oxide. Agar diffusion assays were used to show activity of zinc oxide-coated nanoporous alumina membranes against several bacteria found on the skin surface, including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis. On the other hand, zinc oxide-coated nanoporous alumina membranes did not show activity against Pseudomonas aeruginosa, Enterococcus faecalis, and Candida albicans. These results suggest that zinc oxide-coated nanoporous alumina membranes have activity against some Gram-positive and Gram-negative bacteria that are associated with skin colonization and skin infection.

  9. Oxidation behavior of Ru–Al multilayer coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yung-I, E-mail: yichen@mail.ntou.edu.tw; Zheng, Zhi-Ting; Kai, Wu; Huang, Yu-Ren

    2017-06-01

    Highlights: • Ru{sub 0.63}Al{sub 0.37} multilayer coatings were fabricated using cosputtering. • Oxidation behavior of Ru{sub 0.63}Al{sub 0.37} coatings in 1% O{sub 2}–99% Ar was studied. • Internal oxidation of Ru{sub 0.63}Al{sub 0.37} coatings at 400–600 °C was multi stage parabolic. • External oxidation of Ru{sub 0.63}Al{sub 0.37} was conducted after annealing at 700–800 °C. - Abstract: Ru{sub 0.63}Al{sub 0.37} coatings were deposited through a cyclical gradient concentration deposition at 400 °C with a substrate-holder rotation speed of 1 rpm by direct current magnetron cosputtering. Scanning electron microscopy revealed that the as-deposited coatings exhibited a multilayer structure along with the columnar structure. The oxidation behavior of the Ru{sub 0.63}Al{sub 0.37} coatings was examined through X-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Oxidation kinetics was measured using a thermogravimetric analyzer. Internal oxidation was observed for Ru{sub 0.63}Al{sub 0.37} coatings annealed in a 1% O{sub 2}–99% Ar atmosphere at 400–600 °C accompanied with activation energies of 72–84 kJ/mol. By contrast, external oxidation was observed after annealing at 700–800 °C, resulting in the formation of a continuous alumina scale consisting of crystalline δ-Al{sub 2}O{sub 3} domains, which can be attributable to the outward diffusion of Al.

  10. Oxide Dispersion Strengthened Iron Aluminide by CVD Coated Powders

    Energy Technology Data Exchange (ETDEWEB)

    Asit Biswas Andrew J. Sherman

    2006-09-25

    This I &I Category2 program developed chemical vapor deposition (CVD) of iron, aluminum and aluminum oxide coated iron powders and the availability of high temperature oxidation, corrosion and erosion resistant coating for future power generation equipment and can be used for retrofitting existing fossil-fired power plant equipment. This coating will provide enhanced life and performance of Coal-Fired Boilers components such as fire side corrosion on the outer diameter (OD) of the water wall and superheater tubing as well as on the inner diameter (ID) and OD of larger diameter headers. The program also developed a manufacturing route for readily available thermal spray powders for iron aluminide coating and fabrication of net shape component by powder metallurgy route using this CVD coated powders. This coating can also be applid on jet engine compressor blade and housing, industrial heat treating furnace fixtures, magnetic electronic parts, heating element, piping and tubing for fossil energy application and automotive application, chemical processing equipment , heat exchanger, and structural member of aircraft. The program also resulted in developing a new fabrication route of thermal spray coating and oxide dispersion strengthened (ODS) iron aluminide composites enabling more precise control over material microstructures.

  11. Composite electrolyte with proton conductivity for low-temperature solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Raza, Rizwan, E-mail: razahussaini786@gmail.com [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Energy Technology, Royal Institute of Technology, KTH, Stockholm 10044 (Sweden); Ahmed, Akhlaq; Akram, Nadeem; Saleem, Muhammad; Niaz Akhtar, Majid; Ajmal Khan, M.; Abbas, Ghazanfar; Alvi, Farah; Yasir Rafique, M. [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Sherazi, Tauqir A. [Department of Chemistry, COMSATS Institute of Information Technology, Abbotabad 22060 (Pakistan); Shakir, Imran [Sustainable Energy Technologies (SET) center, College of Engineering, King Saud University, PO-BOX 800, Riyadh 11421 (Saudi Arabia); Mohsin, Munazza [Department of Physics, Lahore College for Women University, Lahore, 54000 (Pakistan); Javed, Muhammad Sufyan [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Zhu, Bin, E-mail: binzhu@kth.se, E-mail: zhubin@hubu.edu.cn [Department of Energy Technology, Royal Institute of Technology, KTH, Stockholm 10044 (Sweden); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Science/Faculty of Computer and Information, Hubei University, Wuhan, Hubei 430062 (China)

    2015-11-02

    In the present work, cost-effective nanocomposite electrolyte (Ba-SDC) oxide is developed for efficient low-temperature solid oxide fuel cells (LTSOFCs). Analysis has shown that dual phase conduction of O{sup −2} (oxygen ions) and H{sup +} (protons) plays a significant role in the development of advanced LTSOFCs. Comparatively high proton ion conductivity (0.19 s/cm) for LTSOFCs was achieved at low temperature (460 °C). In this article, the ionic conduction behaviour of LTSOFCs is explained by carrying out electrochemical impedance spectroscopy measurements. Further, the phase and structure analysis are investigated by X-ray diffraction and scanning electron microscopy techniques. Finally, we achieved an ionic transport number of the composite electrolyte for LTSOFCs as high as 0.95 and energy and power density of 90% and 550 mW/cm{sup 2}, respectively, after sintering the composite electrolyte at 800 °C for 4 h, which is promising. Our current effort toward the development of an efficient, green, low-temperature solid oxide fuel cell with the incorporation of high proton conductivity composite electrolyte may open frontiers in the fields of energy and fuel cell technology.

  12. Corrosion Behavior of PEO Coatings Formed on AZ31 Alloy in Phosphate-Based Electrolytes with Calcium Acetate Additive

    Science.gov (United States)

    Ziyaei, E.; Atapour, M.; Edris, H.; Hakimizad, A.

    2017-07-01

    The PEO coating started on magnesium AZ31 using a unipolar DC power source. The coating was generated in the electrolyte based on Na3PO4·12H2O and KOH with calcium acetate as additive. The x-ray diffraction method showed some phases containing calcium and phosphate, which was created in the presence of additive. Also, the EDS tests of the sample's surfaces proved the existence of calcium on the surface. Based on the electrochemical tests results, the most corrosion resistance belongs to the sample with calcium acetate additive. In fact, the results of the EIS tests showed the coating with calcium acetate has the highest resistance but the lowest capacitance. However, this state belongs to the surface morphology, the lower porosity, and surface chemical composition.

  13. Thermal and oxidation stability of organo-fluorine compound-mixed electrolyte solutions for lithium ion batteries

    Science.gov (United States)

    Nishikawa, Daiki; Nakajima, Tsuyoshi; Ohzawa, Yoshimi; Koh, Meiten; Yamauchi, Akiyoshi; Kagawa, Michiru; Aoyama, Hirokazu

    2013-12-01

    Thermal and oxidation stability of fluorine compound-mixed electrolyte solutions have been investigated. Charge/discharge behavior of natural graphite electrode has been also examined in the same electrolyte solutions. Fluorine compounds demonstrate much lower reactivity with metallic Li than ethylene carbonate/dimethyl carbonate. Fluorine compound-mixed electrolyte solutions show the lower reactivity with LiC6 and the smaller exothermic peaks due to decomposition of electrolyte solutions and surface films than original solutions without fluorine compound. Oxidation currents are also smaller in fluorine compound-mixed electrolyte solutions than in original ones. First coulombic efficiencies in fluorine compound-mixed electrolyte solutions are similar to those in original ethylene carbonate-based solutions except one case. Mixing of fluorine compounds highly increase first coulombic efficiencies of natural graphite electrode in propylene carbonate-containing solution.

  14. Oxidation resistance of iron and copper foils coated with reduced graphene oxide multilayers.

    Science.gov (United States)

    Kang, Dongwoo; Kwon, Jee Youn; Cho, Hyun; Sim, Jae-Hyoung; Hwang, Hyun Sick; Kim, Chul Su; Kim, Yong Jung; Ruoff, Rodney S; Shin, Hyeon Suk

    2012-09-25

    Protecting the surface of metals such as Fe and Cu from oxidizing is of great importance due to their widespread use. Here, oxidation resistance of Fe and Cu foils was achieved by coating them with reduced graphene oxide (rG-O) sheets. The rG-O-coated Fe and Cu foils were prepared by transferring rG-O multilayers from a SiO(2) substrate onto them. The oxidation resistance of these rG-O-coated metal foils was investigated by Raman spectroscopy, optical microscopy, and scanning electron microscopy after heat treatment at 200 °C in air for 2 h. The bare metal surfaces were severely oxidized, but the rG-O-coated metal surfaces were protected from oxidation. This simple solution process using rG-O is one advantage of the present study.

  15. Manufacturing of Dysprosium-Iron Alloys by Electrolysis in Fluoride-Based Electrolytes: Oxide Solubility Determinations

    Science.gov (United States)

    Martinez, Ana Maria; Støre, Anne; Osen, Karen Sende

    2017-12-01

    Electrolytic production of light rare earth elements and alloys takes place in a fluoride-based electrolyte using rare earth oxides as raw material. The optimization of this method, mainly in terms of the energy efficiency and environmental impact control, is rather challenging. Anode effects, evolution of fluorine-containing compounds, and side cathode reactions could largely be minimized by a good control of the amount of rare earth oxide species dissolved in the fluoride-based electrolyte and their dissolution rate. The oxide content of the fluoride melts REF3-LiF (RE = Nd, Dy) at different compositions and temperatures were experimentally determined by carbothermal analysis of melt samples. The highest solubility values of oxide species, added as Dy2O3 and Dy2(CO3)3, were obtained to be of ca. 3 wt pct (expressed as Dy2O3) in the case of the equimolar DyF3-LiF melt at 1323 K (1050 °C). The oxide saturation values increased with the amount of REF3 present in the molten bath and the working temperature.

  16. Ionic and electronic transport across interfaces in thin electrolyte film, anode supported solid oxide fuel cells

    Science.gov (United States)

    Lim, Hyung-Tae

    In transport studies in oxygen ion conductors, oxygen chemical potential (muO2) has been usually assumed to be equilibrated across gas/solid electrolyte interfaces. However, since the interfaces exhibit different properties from the bulk, they must have their own ionic and electronic properties. In this study, Pt reference electrodes were embedded within the electrolyte (gadolinia-doped ceria; GDC) in an anode-supported solid oxide fuel cell to measure the electrochemical potential of electrons (ϕ) through the bulk electrolyte and its interfaces under fuel cell operating condition. Based on local equilibrium assumption, which leads to relations between electrochemical potentials of charged species and chemical potential of neutral species, the corresponding mu O2 was estimated. When the GDC is protected by a thin layer of a predominantly ionic conductor from reducing atmosphere, the muO2 varied monotonically through the GDC layer, exhibiting a relatively small change across the cathode interface region. By contrast, when the GDC was exposed to hydrogen, it was significantly reduced, resulting in higher electron concentration. The corresponding mu O2 was small through the GDC layer, exhibiting an abrupt change across the cathode interface region. This difference in the muO2 variation depending upon the relative electronic conduction in the electrolyte resulted in a large difference in the cathode overpotential. The direction of ionic/electronic current and the corresponding internal muO2 through the electrolyte can have a profound effect on its stability. If cell imbalance exists in a series-connected fuel cell stack, a "bad" cell characterized by a higher resistance can be operated under a negative voltage. To investigate the SOFC stack failure by simulating abnormal behavior in a single cell test, yttira stabilized zirconia (YSZ) electrolyte cells were tested with an applied DC bias. When operating under a negative voltage, rapid degradation occurred

  17. Reorientation of Magnetic Graphene Oxide Nanosheets in Crosslinked Quaternized Polyvinyl Alcohol as Effective Solid Electrolyte

    Directory of Open Access Journals (Sweden)

    Jia-Shuin Lin

    2016-11-01

    Full Text Available This work aims to clarify the effect of magnetic graphene oxide (GO reorientation in a polymer matrix on the ionic conduction and methanol barrier properties of nanocomposite membrane electrolytes. Magnetic iron oxide (Fe3O4 nanoparticles were prepared and dispersed on GO nanosheets (GO-Fe3O4. The magnetic GO-Fe3O4 was imbedded into a quaternized polyvinyl alcohol (QPVA matrix and crosslinked (CL- with glutaraldehyde (GA to obtain a polymeric nanocomposite. A magnetic field was applied in the through-plane direction during the drying and film formation steps. The CL-QPVA/GO-Fe3O4 nanocomposite membranes were doped with an alkali to obtain hydroxide-conducting electrolytes for direct methanol alkaline fuel cell (DMAFC applications. The magnetic field-reoriented CL-QPVA/GO-Fe3O4 electrolyte demonstrated higher conductivity and lower methanol permeability than the unoriented CL-QPVA/GO-Fe3O4 membrane or the CL-QPVA film. The reoriented CL-QPVA/GO-Fe3O4 nanocomposite was used as the electrolyte in a DMAFC and resulted in a maximum power density of 55.4 mW·cm−2 at 60 °C, which is 73.7% higher than that of the composite without the magnetic field treatment (31.9 mW·cm−2. In contrast, the DMAFC using the CL-QPVA electrolyte generated only 22.4 mW·cm−2. This research proved the surprising benefits of magnetic-field-assisted orientation of GO-Fe3O4 in facilitating the ion conduction of a polymeric electrolyte.

  18. Solid polymer electrolyte composite membrane comprising a porous support and a solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide

    Science.gov (United States)

    Liu, Han; Mittelsteadt, Cortney K; Norman, Timothy J; Griffith, Arthur E; LaConti, Anthony B

    2015-02-24

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a thin, rigid, dimensionally-stable, non-electrically-conducting support, the support having a plurality of cylindrical, straight-through pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores are unevenly distributed, with some or no pores located along the periphery and more pores located centrally. The pores are completely filled with a solid polymer electrolyte, the solid polymer electrolyte including a dispersed reduced noble metal or noble metal oxide. The solid polymer electrolyte may also be deposited over the top and/or bottom surfaces of the support.

  19. Electrolytic photodissociation of chemical compounds by iron oxide photochemical diodes

    Science.gov (United States)

    Somorjai, Gabor A.; Leygraf, Christofer H.

    1985-01-01

    Chemical compounds can be dissociated by contacting the same with a p/n type semi-conductor photochemical diode having visible light as its sole source of energy. The photochemical diode consists of low cost, readily available materials, specifically polycrystalline iron oxide doped with silicon in the case of the n-type semi-conductor electrode, and polycrystalline iron oxide doped with magnesium in the case of the p-type electrode. So long as the light source has an energy greater than 2.2 electron volts, no added energy source is needed to achieve dissociation.

  20. Electrolytic photodissociation of chemical compounds by iron oxide electrodes

    Science.gov (United States)

    Somorjai, Gabor A.; Leygraf, Christofer H.

    1984-01-01

    Chemical compounds can be dissociated by contacting the same with a p/n type semi-conductor diode having visible light as its sole source of energy. The diode consists of low cost, readily available materials, specifically polycrystalline iron oxide doped with silicon in the case of the n-type semi-conductor electrode, and polycrystalline iron oxide doped with magnesium in the case of the p-type electrode. So long as the light source has an energy greater than 2.2 electron volts, no added energy source is needed to achieve dissociation.

  1. Rapid heterogeneous oxidation of organic coatings on submicron aerosols

    Science.gov (United States)

    Lim, C. Y.; Browne, E. C.; Sugrue, R. A.; Kroll, J. H.

    2017-03-01

    Laboratory studies have found that heterogeneous oxidation can affect the composition and loading of atmospheric organic aerosol particles over time scales of several days, but most studies have examined pure organic particles only. In this study, in order to probe the reactivity of organic species confined near the particle surface, the rates and products of the OH-initiated oxidation of pure squalane particles are compared to oxidation of thin coatings of squalane on ammonium sulfate particles. The squalane reaction rate constant shows a linear dependence on the organic surface area-to-volume ratio, with rate constants for coated particles up to 10 times larger than for pure particles. Changes in the carbon oxidation state and fraction of particulate carbon remaining show similar enhancements, implying that heterogeneous oxidation may exhibit a stronger effect on the loadings and properties of organic aerosol than previously estimated from laboratory studies.

  2. 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.

  3. Chemical and electrochemical study of fabrics coated with reduced graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Molina, J., E-mail: jamopue@doctor.upv.es; Fernández, J., E-mail: jfernandezmuro@hotmail.com; Río, A.I. del, E-mail: delgaran@doctor.upv.es; Bonastre, J., E-mail: joboca@txp.upv.es; Cases, F., E-mail: fjcases@txp.upv.es

    2013-08-15

    Polyester fabrics coated with reduced graphene oxide (RGO) have been obtained and later characterized by means of chemical and electrochemical techniques. X-ray photoelectron spectroscopy showed a decrease of the oxygen content as well as an increase of the sp{sup 2} fraction after chemical reduction of graphene oxide (GO). The electrical conductivity was measured by electrochemical impedance spectroscopy (EIS) and showed a decrease of 5 orders of magnitude in the resistance (Ω) when GO was reduced to RGO. The phase angle also changed from 90° for PES-GO (capacitative behavior) to 0° for RGO coated fabrics (resistive behavior). In general an increase in the number of RGO layers produced an increase of the conductivity of the fabrics. EIS measurements in metal/sample/electrolyte configuration showed better electrocatalytic properties and faster diffusion rate for RGO specimens. Scanning electrochemical microscopy was employed to test the electroactivity of the different fabrics obtained. The sample coated with GO was not conductive since negative feedback was obtained. When GO was reduced to RGO the sample behaved like a conducting material since positive feedback was obtained. Approach curves indicated that the redox mediator had influence on the electrochemical response. The Fe(CN){sub 6}{sup 3−/4−} redox mediator produced a higher electrochemical response than Ru(NH{sub 3}){sub 6}{sup 3+/2+} one.

  4. Graphene-oxide-coated interferometric optical microfiber ethanol vapor sensor.

    Science.gov (United States)

    Zhang, Jingle; Fu, Haiwei; Ding, Jijun; Zhang, Min; Zhu, Yi

    2017-11-01

    A graphene-oxide-coated interferometric microfiber-sensor-based polarization-maintaining optical fiber is proposed for highly sensitive detecting for ethanol vapor concentration at room temperature in this paper. The strong sensing capability of the sensor to detect the concentration of ethanol vapor is demonstrated, taking advantage of the evanescent field enhancement and gas absorption of a graphene-oxide-coated microfiber. The transmission spectrum of the sensor varies with concentrations of ethanol vapor, and the redshift of the transmission spectrum has been analyzed for the concentration range from 0 to 80 ppm with sensitivity as high as 0.138 nm/ppm. The coated graphene oxide layer induces the evanescent field enhancement and gas selective adsorption, which improves sensitivity and selectivity of the microfiber gas sensor for ethanol vapor detection.

  5. The n-MAO/EPD bio-ceramic composite coating fabricated on ZK60 magnesium alloy using combined micro-arc oxidation with electrophoretic deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Ying, E-mail: yxiong@zjut.edu.cn [College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310032 (China); Lu, Chao [College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310032 (China); Wang, Chao; Song, Renguo [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164 (China)

    2014-12-15

    Highlights: • Adding CeO{sub 2}/ZrO{sub 2} nano-particles to modify the properties of n-MAO coating. • A bio-ceramic n-MAO/EPD composite coating was prepared by two-step methods. • The n-MAO/EPD composite coating with HA has a favorable anti-corrosion effect. - Abstract: A bio-ceramic composite coating was fabricated on ZK60 magnesium (Mg) alloy using combined micro-arc oxidation (MAO) with electrophoretic deposition (EPD) technique. The MAO coating as the basal layer was produced in alkaline electrolyte with (n-MAO coating) and without (MAO coating) the addition of CeO{sub 2} and ZrO{sub 2} nano-particles, respectively. A hydroxyapatite (HA) coating as the covering layer was deposited on the n-MAO coating to improve the biological properties of the coating (n-MAO/EPD composite coating). The morphology and phase composition of three treated coatings were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). The corrosion resistance of these coatings was evaluated with potentiodynamic polarization tests and immersion tests in simulated body fluid (SBF) at 36.5 ± 0.5 °C. The XRD spectra showed that the CeO{sub 2} and ZrO{sub 2} peaks can be collected in the n-MAO coating, and HA particles exists in the n-MAO/EPD composite coating. The results of corrosion tests indicated that the n-MAO/EPD composite coating owned increased bioactivity and long-term protective ability compared with the MAO coating and the n-MAO coating. Thus Mg alloy coated with the n-MAO/EPD composite coating should be more suited as biodegradable bone implants.

  6. Method of forming oxide coatings. [for solar collector heating panels

    Science.gov (United States)

    Mcdonald, G. E. (Inventor)

    1983-01-01

    This invention is concerned with an improved plating process for covering a substrate with a black metal oxide film. The invention is particularly directed to making a heating panel for a solar collector. A compound is electrodeposited from an aqueous solution containing cobalt metal salts onto a metal substrate. This compound is converted during plating into a black, highly absorbing oxide coating which contains hydrated oxides. This is achieved by the inclusion of an oxidizing agent in the plating bath. The inclusion of an oxidizing agent in the plating bath is contrary to standard electroplating practice. The hydrated oxides are converted to oxides by treatment in a hot bath, such as boiling water. An oxidizing agent may be added to the hot liquid treating bath.

  7. Trimethylsilylcyclopentadiene as a novel electrolyte additive for high temperature application of lithium nickel manganese oxide cathode

    Science.gov (United States)

    Tu, Wenqiang; Ye, Changchun; Yang, Xuerui; Xing, Lidan; Liao, Youhao; Liu, Xiang; Li, Weishan

    2017-10-01

    Electrolyte additives are necessary for the application of high potential cathode in high energy density lithium ion batteries, especially at elevated temperature. However, the electrolyte additives that can effectively suppress the dissolution of transition metal ions from cathode have seldom been developed up to date. In this work, we propose a novel electrolyte additive, trimethylsilylcyclopentadiene (SE), for high temperature application of a representative high potential cathode, lithium nickel manganese oxide (LiNi0.5Mn1.5O4). It is found that the dissolution of Mn and Ni from LiNi0.5Mn1.5O4 can be effectively suppressed by applying SE. With applying 0.25% SE, the dissolved amount of Mn and Ni is decreased by 97.4% and 98%, respectively, after 100 cycles at 55 °C. Correspondingly, the cyclic performance of LiNi0.5Mn1.5O4 is significantly improved. Physical characterizations and electrochemical measurements show that SE can be preferentially oxidized and generate a protective film on LiNi0.5Mn1.5O4. The resulting film inhibits the electrolyte decomposition and the transition metal ion dissolution.

  8. Dissolution of Neptunium and Plutonium Oxides Using a Catalyzed Electrolytic Process

    Energy Technology Data Exchange (ETDEWEB)

    Hylton, TD

    2004-10-25

    This report discusses the scoping study performed to evaluate the use of a catalyzed electrolytic process for dissolving {sup 237}Np oxide targets that had been irradiated to produce {sup 238}Pu oxide. Historically, these compounds have been difficult to dissolve, and complete dissolution was obtained only by adding hydrofluoric acid to the nitric acid solvent. The presence of fluoride in the mixture is undesired because the fluoride ions are corrosive to tank and piping systems and the fluoride ions cause interferences in the spectrophotometric analyses. The goal is to find a dissolution method that will eliminate these issues and that can be incorporated into a processing system to support the domestic production and purification of {sup 238}Pu. This study evaluated the potential of cerium(IV) ions, a strong oxidant, to attack and dissolve the oxide compounds. In the dissolution process, the cerium(IV) ions are reduced to cerium(III) ions, which are not oxidants. Therefore, an electrolytic process was incorporated to continuously convert cerium(III) ions back to cerium(IV) ions so that they can dissolve more of the oxide compounds. This study showed that the neptunium and plutonium oxides were successfully dissolved and that more development work should be performed to optimize the procedure.

  9. Applications of Oxide Coatings in Photovoltaic Devices

    Directory of Open Access Journals (Sweden)

    Sonya Calnan

    2014-03-01

    Full Text Available Metalloid and metal based oxides are an almost unavoidable component in the majority of solar cell technologies used at the time of writing this review. Numerous studies have shown increases of ≥1% absolute in solar cell efficiency by simply substituting a given layer in the material stack with an oxide. Depending on the stoichiometry and whether other elements are present, oxides can be used for the purpose of light management, passivation of electrical defects, photo-carrier generation, charge separation, and charge transport in a solar cell. In this review, the most commonly used oxides whose benefits for solar cells have been proven both in a laboratory and industrial environment are discussed. Additionally, developing trends in the use of oxides, as well as newer oxide materials, and deposition technologies for solar cells are reported.

  10. Antibacterial Activity of Zinc Oxide-Coated Nanoporous Alumina

    Science.gov (United States)

    2012-05-17

    Prior to deposition of the zinc oxide coating, the nanoporous alumina membranes were cleaned in situ using flowing ozone . Samples were exposed for 5 min...to an ozone partial pressure of ∼0.1 Torr; ozone was obtained from ultra high purity oxygen (flow rate = 400 sccm). Zinc oxide coatings were grown...H. Goudarzi, M. Navidinia, Gene Therapy and Molecular Biology 10B (2006) 263–267. [31] L.G. Miller, C. Quan, A. Shay, K. Mostafaie, K. Bharadwa, N

  11. Liquid Plasma Synthesis of Carbon Coated Iron Oxide Particles

    Science.gov (United States)

    Uygun, Aysegul; Hershkowitz, Noah; Eren, Esin; Uygun, Emre; Celik Cogal, Gamze; Yurdabak Karaca, Gozde; Manolache, Sorin; Sundaram, Gunasekaran; Sadak, Omer; Oksuz, Lutfi

    2017-10-01

    Recently, magnetic metal or metal oxide nanoparticles encapsulated in carbon are important in biomedical applications. The relevant reason to study toxicity of the magnetic nanoparticles coated by carbon is that they have great potential to contribute to cancer treatment. In this work, the synthesis of iron oxide nano-particles coated by graphitic carbon shells using pulsed plasma in liquid method. Short duration of RF plasma discharge, low electrical energy and fast quenching of the surrounding media can let to synthesize various kinds of pure nanoparticles. Corresponding author: ayseguluygun@sdu.edu.tr, lutfioksuz@sdu.edu.tr.

  12. Effect of electrolyte temperature on the thickness of anodic aluminium oxide (AAO layer

    Directory of Open Access Journals (Sweden)

    P. Michal

    2016-07-01

    Full Text Available Effect of electrolyte temperature on the thickness of resulting oxide layer has been studied. Unlike previous published studies this article was aimed to monitor the relationship between electrolyte temperature and resulting AAO layer thickness in interaction with other input factors affecting during anodizing process under special process condition, i.e. lower concentration of sulphuric acid, oxalic acid, boric acid and sodium chloride. According to Design of Experiments (DOE 80 individual test runs of experiment were carried out. Using statistical analysis and artificial intelligence for evaluation, the computational model predicting the thickness of oxide layer in the range from 5 / μm to 15 / μm with tolerance ± 0,5 / μm was developed.

  13. Oxidative degradation of polybenzimidazole membranes as electrolytes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Liao, J.H.; Li, Qingfeng; Rudbeck, H.C.

    2011-01-01

    Polybenzimidazole membranes imbibed with acid are emerging as a suitable electrolyte material for high-temperature polymer electrolyte fuel cells. The oxidative stability of polybenzimidazole has been identified as an important issue for the long-term durability of such cells. In this paper...... the oxidative degradation of the polymer membrane was studied under the Fenton test conditions by the weight loss, intrinsic viscosity, size exclusion chromatography, scanning electron microscopy and Fourier transform infrared spectroscopy. During the Fenton test, significant weight losses depending...... on the initial molecular weight of the polymer were observed. At the same time, viscosity and SEC measurements revealed a steady decrease in molecular weight. The degradation of acid doped PBI membranes under Fenton test conditions is proposed to start by the attack of hydroxyl radicals at the carbon atom...

  14. Cr and Zr/Cr nitride CAE-PVD coated aluminum bipolar plates for polymer electrolyte membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Barranco, Jose; Maza, Mario [University of Zaragoza, Department of Mechanical Engineering, Maria de Luna 3, ES-50018 Zaragoza (Spain); Barreras, Felix; Lozano, Antonio; Lopez, Ana M.; Roda, Vicente; Martin, Jesus [LITEC-CSIC, Univ. Zaragoza, Maria de Luna 10, ES-50018 Zaragoza (Spain); Fuentes, Gonzalo G.; Almandoz, Eluxka [AIN, Centro de Ingenieria Avanzada de Superficies, Cordovilla, ES-31191 Pamplona (Spain)

    2010-10-15

    In this work, two nitride coatings deposited on aluminum-based bipolar plates via cathodic arc evaporation physical vapor deposition (CAE-PVD) have been evaluated using two different techniques. The coating materials, a multi-layer chromium-zirconium nitride (ZrN-CrN) and a monolayer chromium nitride (CrN) have been exposed to electrochemical polarization tests for corrosion resistance simulating the typical environment in the anode and cathode sides in polymer electrolyte membrane fuel cells (PEMFC). Besides, two 3-cell PEMFC stacks, one per each coating material, have been formed. The migration of metal cations toward both the gas diffusion layers (GDL) and catalyst layers have been analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), after 100 h of continuous operation of the stacks. Results have shown that the two coatings applied over the Al-plates satisfy the corrosion resistance requirements in the short-term tests performed at the two stacks. Moreover, results obtained from electrochemical polarization tests have revealed that the CrN-coating confers a good corrosion resistance to the Al-based metal plate, achieving values of corrosion potential and corrosion current two orders of magnitude lower than the ones obtained for the Al alloy as-received. (author)

  15. Effect of phosphate additives on the microstructure, bioactivity, and degradability of microarc oxidation coatings on Mg-Zn-Ca-Mn alloy.

    Science.gov (United States)

    Dou, Jinhe; You, Qiongya; Gu, Guochao; Chen, Chuanzhong; Zhang, Xihua

    2016-09-20

    Calcium phosphate coatings were prepared on the surface of self-designed Mg-Zn-Ca-Mn alloy using microarc oxidization technology. To characterize the microstructures, cross-section morphologies, and compositions of the coatings, the authors used scanning electron microscopy equipped with an energy-disperse spectrometer, x-ray diffraction, and Fourier transform infrared spectroscopy. Potentiodynamic polarization in the simulated body fluid (SBF) was used to evaluate the corrosion behaviors of the samples. An SBF immersion test was used to evaluate the coating bioactivity and degradability. After the immersion tests, some bonelike apatite formed on the coating surfaces indicate that bioactivity of the coatings is excellent. The coating prepared in electrolyte containing (NaPO3)6 had slower degradation rate after immersion test for 21 days.

  16. Mediated electrochemical oxidation of organic wastes using a Co(III) mediator in a neutral electrolyte

    Science.gov (United States)

    Balazs, G. Bryan; Lewis, Patricia R.

    1999-01-01

    An electrochemical cell with a Co(III) mediator and neutral pH anolyte provides efficient destruction of organic and mixed wastes. The organic waste is concentrated in the anolyte reservoir, where the cobalt mediator oxidizes the organics and insoluble radioactive species and is regenerated at the anode until all organics are converted to carbon dioxide and destroyed. The neutral electrolyte is non-corrosive, and thus extends the lifetime of the cell and its components.

  17. Obtaining of nanostructured ZnO coatings using mechanoactivated oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Muktepavela, F [Institute of Solid State Physics, University of Latvia, Riga (Latvia); Bakradze, G [Institute of Solid State Physics, University of Latvia, Riga (Latvia); Tamanis, E [Daugavpils University, Daugavpils (Latvia); Grigorjeva, L [Institute of Solid State Physics, University of Latvia, Riga (Latvia); Kulis, P [Institute of Solid State Physics, University of Latvia, Riga (Latvia); Krutohvostovs, R [Institute of Solid State Physics, University of Latvia, Riga (Latvia)

    2007-12-15

    The concept to use nanostructured state of metal at the instant of destruction in air environment was used to obtain nanostructured Zn-ZnO coatings on glass and quartz by mechanical method. Subsequent annealing in the ambient atmosphere, annealing in vacuum and irradiation with 532-nm YAG:Nd laser were used to obtain completely oxidized, transparent ZnO coatings. The saturated with oxygen nanostructured coatings were transformed into nanostructured ZnO coatings after annealing above 773K or irradiation with laser (allowing to reach 673K) in ambient atmosphere. AFM and SEM images show that after annealing ZnO coatings have multi-shaped structure. The formation of ZnO need-like whiskers (d = 100nm, l = 2{mu}m) was observed after laser irradiation. Obtained ZnO coatings have high microhardness (10--12GPa), strong adhesion with substrates and show green and blue luminescence at room temperature. The oxidation process is mechanoactivated due to the facilitated oxygen diffusion along deformation defects: vacancies, dislocation, microcracks, and developed network of grain boundaries.

  18. Electrolyte effects on aqueous atmospheric oxidation of sulphur dioxide by ozone

    Energy Technology Data Exchange (ETDEWEB)

    Lagrange, J.; Pallares, C.; Lagrange, P. [CNRS, Strasbourg (France)

    1994-07-01

    The kinetics of sulphur(IV) oxidation by ozone in an aqueous solution were studied in various supporting electrolytes (NaClO4, NaCl, NH4ClO4, Na2SO4), using the stopped flow method. The rare data in perchlorate medium (chosen as reference electrolyte) are empirically correlated by the following expression: r = -d(O3)/dt = K(O3)(S(IV))(H(+))(exp -1/2). For each supporting electrolyte studied, the rate constant varies linearly with the ionic strength. The value of the rate constant is extrapolated to zero ionic strength. The rate constants are shown to be higher mainly when ammonium chloride and sodium sulphate are added to the solution. The effect of temperature is studied between 13 and 28 C. The reaction rate is unaffected by the trace presence of metal ion (Mm(2+), Fe(2+), Cu(2+), Fe(3+), Cr(3+)). The rate of oxidation is dissolved SO2 by O3, in water droplets under atmospheric conditions, is calculated as a function of (H(+)) and compared to the oxidation by H2O2. At zero ionic strength the ozone reaction becomes faster than hydrogen peroxide reaction above -log (H(+)) = 4.70. This effect appears at higher H(+) concentration when the ionic strength increases (-log (H(+)) = 3 in 4 mol/L NaCl or 2 mol/L Na2SO4).

  19. Modifying zirconia solid electrolyte surface property to enhance oxide transport

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, B.Y.; Song, S.Y. [Univ. of Hawaii, Honolulu, HI (United States)

    1996-12-31

    Bismuth-strontium-calcium-copper oxide (Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, BSCCO) is known for its high T{sub c} superconducting behavior and mixed conducting property. The applicability of similar high T{sub c} cuprates for intermediate-temperature solid oxide fuel cell (SOFC) application has been studied recently. We investigated the electrochemical behavior of several Ag{vert_bar}BSCCO{vert_bar}10 mol% yttria-stabilized zirconia (YSZ){vert_bar}Ag and Ag{vert_bar}YSZ{vert_bar}Ag cells using complex impedance spectroscopy. A highly uniform and porous microstructure was observed at the interface of the YSZ and BSCCO. The ionic conductivity determined from the Nyquest plots in the temperature range of 200-700{degrees}C agrees with the values reported in the literature. The specific resistance of the BSCCO{vert_bar}YSZ interface was also determined to be lower than those of the conventional manganite electrode, suggesting that BSCCO seems attractive for cathode applications in SOFC.

  20. Antimicrobial activity of tantalum oxide coatings decorated with Ag nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Huiliang, E-mail: hlc@mail.sic.ac.cn; Meng, Fanhao; Liu, Xuanyong, E-mail: xyliu@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2016-07-15

    Silver plasma immersion ion implantation was used to decorate silver nanoparticles (Ag NPs) on tantalum oxide (TO) coatings. The coatings acted against bacterial cells (Staphylococcus epidermidis) in the dark by disrupting their integrity. The action was independent of silver release and likely driven by the electron storage capability of the Schottky barriers established at the interfaces between Ag NPs and the TO support. Moreover, no apparent side effect on the adhesion and differentiation of rat bone mesenchymal stem cells was detected when using Ag NPs-modified TO coatings. These results demonstrate that decoration of tantalum oxide using Ag NPs could be a promising procedure for improving the antibacterial properties for orthopedic and dental implants.

  1. Effect of process parameters on coating composition of cathodic ...

    Indian Academy of Sciences (India)

    trolysis in 50 vol% ethanol electrolyte and coatings comprising carbon nanostructure and copper oxide are formed on the copper. The effect of ... to produce complex coating such as carbon structures, oxides. [6,7], titanium, molybdenum ... be controlled for the production of high-quality coatings. Current density is one of the ...

  2. Refractory Oxide Coatings on Titanium for Nitric Acid Applications

    Science.gov (United States)

    Ravi Shankar, A.; Kamachi Mudali, U.

    2014-07-01

    Tantalum and Niobium have good corrosion resistance in nitric acid as well as in molten chloride salt medium encountered in spent fuel nuclear reprocessing plants. Commercially, pure Ti (Cp-Ti) exhibits good corrosion resistance in nitric acid medium; however, in vapor condensates of nitric acid, significant corrosion was observed. In the present study, a thermochemical diffusion method was pursued to coat Ta2O5, Nb2O5, and Ta2O5 + Nb2O5 on Ti to improve the corrosion resistance and enhance the life of critical components in reprocessing plants. The coated samples were characterized by XRD, SEM, EDX, profilometry, micro-scratch test, and ASTM A262 Practice-C test in 65 pct boiling nitric acid. The SEM micrograph of the coated samples showed that uniform dense coating containing Ta2O5 and/or Nb2O5 was formed. XRD patterns indicated the formation of TiO2, Ta2O5/Nb2O5, and mixed oxide/solid solution phase on coated Ti samples. ASTM A262 Practice-C test revealed reproducible outstanding corrosion resistance of Ta2O5-coated sample in comparison to Nb2O5- and Ta2O5 + Nb2O5-coated sample. The hardness of the Ta2O5-coated Cp-Ti sample was found to be twice that of uncoated Cp-Ti. The SEM and XRD results confirmed the presence of protective oxide layer (Ta2O5, rutile TiO2, and mixed phase) on coated sample which improved the corrosion resistance remarkably in boiling liquid phase of nitric acid compared to uncoated Cp-Ti and Ti-5Ta-1.8Nb alloy. Three phase corrosion test conducted on Ta2O5-coated samples in boiling 11.5 M nitric acid showed poor corrosion resistance in vapor and condensate phases of nitric acid due to poor adhesion of the coating. The adhesive strength of the coated samples needs to be optimized in order to improve the corrosion resistance in vapor and condensate phases of nitric acid.

  3. A modified anode/electrolyte structure for a solid oxide electrochemical cell and a method for making said structure

    DEFF Research Database (Denmark)

    2013-01-01

    A novel modified anode/electrolyte structure for a solid oxide electrochemical cell is an assembly comprising (a) an anode consisting of a backbone of electronically conductive perovskite oxides selected from the group of doped strontium titanates and mixtures thereof, (b) a scandia and yttria...... treatments resulted in a distribution of the metallic and/or ceramic interlayers in the electrolyte/anode backbone junction taking place. The structure is prepared by (a) depositing a ceramic interlayer onto one side of the electrolyte, (b) optionally applying a metallic interlayer thereon, (c) repeating...

  4. Selection of a Commercial Anode Oxide Coating for Electro-oxidation of Cyanide

    Directory of Open Access Journals (Sweden)

    Lanza Marcos Roberto V.

    2002-01-01

    Full Text Available This paper presents a study of the performance of two commercial dimensionally stable anode (DSA® oxide coatings in the electrochemical process for cyanide oxidation. The coatings studied were 70TiO2/30RuO2 and 55Ta2O5/45IrO2, on Ti substrate. The efficiency of both materials in the electro-oxidation of free cyanide was compared using linear voltammetry and electrolysis at constant potential. The 70TiO2/30RuO2 electrode shows a better performance in the electro-oxidation of free cyanide.

  5. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries

    Science.gov (United States)

    Porcarelli, Luca; Gerbaldi, Claudio; Bella, Federico; Nair, Jijeesh Ravi

    2016-01-01

    Here we demonstrate that by regulating the mobility of classic −EO− based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm−1 are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li+), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient conditions. PMID:26791572

  6. Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries.

    Science.gov (United States)

    Porcarelli, Luca; Gerbaldi, Claudio; Bella, Federico; Nair, Jijeesh Ravi

    2016-01-21

    Here we demonstrate that by regulating the mobility of classic -EO- based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm(-1) are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li(+)), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient conditions.

  7. Successful Stabilization of Graphene Oxide in Electrolyte Solutions: Enhancement of Bio-functionalization and Cellular Uptake

    Science.gov (United States)

    Hong, Bong Jin; Compton, Owen C.; An, Zhi; Eryzazici, Ibrahim; Nguyen, SonBinh T.

    2013-01-01

    Aqueous dispersions of graphene oxide are inherently unstable in the presence of electrolytes, which screen the electrostatic surface charge on these nanosheets and induce irreversible aggregation. Two complementary strategies, utilizing either electrostatic or steric stabilization, have been developed to enhance the stability of graphene oxide in electrolyte solutions, allowing it to stay dispersed in cell culture media and serum. The electrostatic stabilization approach entails further oxidation of graphene oxide to low C/O ratio (~1.03) and increases ionic tolerance of these nanosheets. The steric stabilization technique employs an amphiphilic block copolymer that serves as a non-covalently bound surfactant to minimize the aggregate-induced nanosheets-nanosheet interactions. Both strategies can stabilize graphene oxide nanosheets with large dimensions (>300 nm) in biological media, allowing for an enhancement of >250% in the bioconjugation efficiency of streptavidin in comparison to untreated nanosheets. Notably, both strategies allow the stabilized nanosheets to be readily uptake by cells, demonstrating their excellent performance as potential drug delivery vehicles. PMID:22017285

  8. Osteogenic potential of a novel microarc oxidized coating formed on Ti6Al4V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yaping [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China); Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Lou, Jin [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China); Zeng, Lilan [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Xiang, Junhuai; Zhang, Shufang; Wang, Jun; Xiong, Fucheng; Li, Chenglin [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China); Zhao, Ying, E-mail: ying.zhao@siat.ac.cn [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Zhang, Rongfa, E-mail: rfzhang-10@163.com [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China)

    2017-08-01

    Highlights: • Phytic acid is used as the MAO electrolyte of titanium alloys. • MAO coatings are composed of rutile, anatase, TiP{sub 2}O{sub 7} and some OH{sup −} groups. • The MAO samples present excellent in vitro cytocompatibility. - Abstract: In order to improve the biocompatibility, Ti6Al4V alloys are processed by micro arc oxidation (MAO) in a novel electrolyte of phytic acid, a natural organic phosphorus-containing matter. The MAO coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The cytocompatibility of Ti6A14V alloys before and after MAO were comprehensively evaluated. The results showed that the fabricated MAO coatings were composed of rutile, anatase, TiP{sub 2}O{sub 7} as well as some OH{sup −} groups, exhibiting the excellent hydrophilicity and a porous structure with small micro pores. No cytotoxicity towards MC3T3-E1cells was observed in this study. In particular, MAO treated Ti6Al4V alloys presented comparable cell adhesion and proliferation as well as significantly enhanced alkaline phosphatase activity, extracellular matrix (ECM) mineralization and collagen secretion in comparison with the untreated control. The results suggest that the Ti6Al4V alloys treated by MAO in phytic acid can be used as implants for orthopaedic applications, providing a simple and practical method to widen clinical acceptance of titanium alloys.

  9. Water vapor exchange system using a hydrophilic microporous layer coated gas diffusion layer to enhance performance of polymer electrolyte fuel cells without cathode humidification

    Science.gov (United States)

    Kitahara, Tatsumi; Nakajima, Hironori; Morishita, Masashi

    2012-09-01

    Polymer electrolyte fuel cells (PEFCs) generally have external humidifiers to supply humidified hydrogen and oxidant gases, which prevents dehydration of the membrane. If a PEFC could be operated without humidification, then external humidifiers could be removed, which would result in a simplified PEFC system with increased total efficiency and reduced cost. A water vapor exchange system installed in the PEFC was developed to enhance the performance without cathode humidification. A gas diffusion layer (GDL) coated with a hydrophobic microporous layer (MPL) was used at the active reaction area. A GDL coated with a hydrophilic MPL consisting of polyvinyl alcohol (PVA) and carbon black was used at the cathode water vapor exchange area to promote water transport from the cathode outlet wet gas to the anode inlet dry gas. This is effective for reducing the IR overpotential, which enhances the PEFC performance. Appropriate enhancement of hydrophilicity by increasing the PVA content in the MPL to 20 mass% is effective to increase water transport from the cathode to anode. At the anode water exchange area, a GDL without the hydrophilic MPL is effective to promote water transport from the water exchange area to the active reaction area, which enhances the PEFC performance.

  10. Study of the effect of Pyrophosphate in low voltage Plasma Electrolytic Oxidation on the corrosion resistance of AZ31B Magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Jae Gon; Kim, Eng Chan [Yeungnam University, Gyeongsan (Korea, Republic of); Kim, Ki Hong [Catholic University of Daegu, Gyeongsan (Korea, Republic of)

    2016-01-15

    In this study, low voltage Plasma Electrolytic Oxidation (PEO) was utilized to eliminate the drawbacks of high voltage PEO such as high cost, dimensional deformation, and porosity. Low voltage PEO produces a thin coating, which leads to low corrosion resistance. In order to solve this problem, 0.1⁓0.6 M pyrophosphates were added to a bath containing 1.4 M NaOH and 0.35 M Na{sub 2}SiO{sub 3}.PEO at 70V was conducted at 25℃ for 3 minutes. The chemical composition, morphology, and corrosion resistance of the anodized coating were analyzed. The anodized film was composed of MgO, Mg{sub 2}SiO{sub 4}, and Mg{sub 2}O{sub 7}P{sub 2}. Themorphology of the film showed a inappropriately dense structure and low porosity in the anodized layers. It is found that low voltage Plasma Electrolytic Oxidation in cooperation with phosphating treatment can provide good corrosion protection for the AZ31B magnesium alloy.

  11. Corrosion study of the graphene oxide and reduced graphene oxide-based epoxy coatings

    Science.gov (United States)

    Ghauri, Faizan Ali; Raza, Mohsin Ali; Saad Baig, Muhammad; Ibrahim, Shoaib

    2017-12-01

    This work aims to determine the effect of graphene oxide (GO) and reduced graphene oxide (rGO) incorporation as filler on the corrosion protection ability of epoxy coatings in saline media. GO was derived from graphite powder following modified Hummers’ method, whereas rGO was obtained after reduction of GO with hydrazine solution. About 1 wt.% of GO or rGO were incorporated in epoxy resin by solution mixing process followed by ball milling. GO and rGO-based epoxy composite coatings were coated on mild steel substrates using film coater. The coated samples were characterized by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests after 1 and 24 h immersion in 3.5% NaCl. The results suggested that GO-based epoxy composite coatings showed high impedance and low corrosion rate.

  12. Surface Properties of PAN-based Carbon Fibers Modified by Electrochemical Oxidization in Organic Electrolyte Systems

    Directory of Open Access Journals (Sweden)

    WU Bo

    2016-09-01

    Full Text Available PAN-based carbon fibers were modified by electrochemical oxidization using fatty alcohol polyoxyethylene ether phosphate (O3P, triethanolamine (TEOA and fatty alcohol polyoxyethylene ether ammonium phosphate (O3PNH4 as organic electrolyte respectively. Titration analysis, single fiber fracture strength measurement and field emission scanning electron microscopy (FE-SEM were used to evaluate the content of acidic functional group on the surface, mechanical properties and surface morphology of carbon fiber. The optimum process of electrochemical treatment obtained is at 50℃ for 2min and O3PNH4 (5%, mass fraction as the electrolyte with current density of 2A/g. In addition, the surface properties of modified carbon fibers were characterized by X-ray photoelectron spectroscopy (XPS and single fiber contact angle test. The results show that the hydrophilic acidic functional groups on the surface of carbon fiber which can enhance the surface energy are increased by the electrochemical oxidation using O3PNH4 as electrolyte, almost without any weakening to the mechanical properties of carbon fiber.

  13. Improving the oxidation resistance and stability of Ag nanoparticles by coating with multilayered reduced graphene oxide

    Science.gov (United States)

    Li, Yahui; Zhang, Huayu; Wu, Bowen; Guo, Zhuo

    2017-12-01

    A kind of coating nanostructure, Ag nanoparticles coated with multilayered reduced graphene oxide (RGO), is fabricated by employing a three-step reduction method in an orderly manner, which is significantly different from the conventional structures that are simply depositing or doping with Ag nanoparticles on RGO via chemical reduction. The as-prepared nanostructure is investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electronic diffraction (SEAD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results show that the obtained Ag/RGO nanostructure is observed to be a perfect coating structure with well dispersed Ag particles, which is responsible for the remarkable oxidation resistance. The results of XPS spectra indicate the content of metallic Ag is far greater than that of Ag oxides despite of prolonged exposure to the air, which fully demonstrate the excellent stability of thus coating nanostructure.

  14. Improvement of cathode-electrolyte interfaces of tubular solid oxide fuel cells by fabricating dense YSZ electrolyte membranes with indented surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Dehua; Liu, Mingfei; Xie, Kui; Sheng, Jin; Liu, Xingqin; Meng, Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Wang, Yonghong; Peng, Xiaobo [Institute of Materials Science and Engineering, Hefei University of Technology (China)

    2008-01-03

    To improve cathode-electrolyte interfaces of solid oxide fuel cells (SOFCs), dense YSZ electrolyte membranes with indented surfaces were fabricated on tubular NiO/YSZ anode supports by two comparable methods. Electrochemistry impedance spectroscopy (EIS) and current-voltage tests of the cells were carried out to characterize the cathode-electrolyte interfaces. Results showed that the electrode polarization resistances of the modified cells were reduced by 52% and 35% at 700 C, and the maximum power densities of cells were remarkably increased, even by 146.6% and 117.8% at lower temperature (700 C), respectively. The indented surfaces extended the active zone of cathode and enhanced interfacial adhesion, which led to the major improvement in the cell performance. (author)

  15. Oxide-based synaptic transistors gated by solution-processed gelatin electrolytes

    Science.gov (United States)

    He, Yinke; Sun, Jia; Qian, Chuan; Kong, Ling-An; Gou, Guangyang; Li, Hongjian

    2017-04-01

    In human brain, a large number of neurons are connected via synapses. Simulation of the synaptic behaviors using electronic devices is the most important step for neuromorphic systems. In this paper, proton conducting gelatin electrolyte-gated oxide field-effect transistors (FETs) were used for emulating synaptic functions, in which the gate electrode is regarded as pre-synaptic neuron and the channel layer as the post-synaptic neuron. In analogy to the biological synapse, a potential spike can be applied at the gate electrode and trigger ionic motion in the gelatin electrolyte, which in turn generates excitatory post-synaptic current (EPSC) in the channel layer. Basic synaptic behaviors including spike time-dependent EPSC, paired-pulse facilitation (PPF), self-adaptation, and frequency-dependent synaptic transmission were successfully mimicked. Such ionic/electronic hybrid devices are beneficial for synaptic electronics and brain-inspired neuromorphic systems.

  16. Ion beam mixed oxidation protective coating on Zry-4 cladding

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae-Won, E-mail: pjw@kaeri.re.kr; Kim, Jae-Un; Park, Jeong-Yong

    2016-06-15

    In this study, SiC was coated on the surface of Zry-4 cladding to improve the oxidation protectiveness. In the coating of SiC onto Zry-4, the prime concern was adhesion at an elevated temperature. Here, a 70 keV N ion beam was irradiated onto a SiC coating layer of ∼100 nm in thickness; this was deposited via the e-beam evaporation method. Additional coating to a target thickness was then carried out. The films deposited without ion-beam mixing (IBM) often peeled-off at an elevated temperature, while the IBM SiC film always adhered to Zry-4, even after heating to ∼1000 °C; at such a temperature, however, cracks formed in the film. X-ray photoelectron spectroscopy (XPS) analysis showed that the deposited SiC film contained about 20 at.% of O, while after annealing in air, 76 at.% of O was found on the surface layer. This implied that both the surface of SiC film and Zry-4 in the crack lines were oxidized. Comparing the Zr3d peak positions across the interface, a shift of binding energy by ∼1 eV was detected, representing that, in view of favorable thermodynamics, SiC/Zry-4 seems to be an acceptable system to apply IBM. To heal the crack, the process of IBM for a 1 μm thick coating and annealing was repeated. High-resolution field emission secondary electron microscopy (FE-SEM) showed that the crack lines, the main places at which oxidation occurred, were gradually covered as the process was repeated, ensuring enhanced oxidation protectiveness.

  17. Oxidation and thermal shock behavior of thermal barrier coated 18/10CrNi alloy with coating modifications

    Energy Technology Data Exchange (ETDEWEB)

    Guergen, Selim [Vocational School of Transportation, Anadolu University, Eskisehir (Turkmenistan); Diltemiz, Seyid Fehmi [Turkish Air Force1st Air Supply and Maintenance Center Command, Eskisehir (Turkmenistan); Kushan, Melih Cemal [Dept. of Mechanical Engineering, Eskisehir Osmangazi University, Eskisehir (Turkmenistan)

    2017-01-15

    In this study, substrates of 18/10CrNi alloy plates were initially sprayed with a Ni-21Cr-10Al-1Y bond coat and then with an yttria stabilized zirconia top coat by plasma spraying. Subsequently, plasma-sprayed Thermal barrier coatings (TBCs) were treated with two different modification methods, namely, vacuum heat treatment and laser glazing. The effects of modifications on the oxidation and thermal shock behavior of the coatings were evaluated. The effect of coat thickness on the bond strength of the coats was also investigated. Results showed enhancement of the oxidation resistance and thermal shock resistance of TBCs following modifications. Although vacuum heat treatment and laser glazing exhibited comparable results as per oxidation resistance, the former generated the best improvement in the thermal shock resistance of the TBCs. Bond strength also decreased as coat thickness increased.

  18. Effect of Anode Pulse-Width on the Microstructure and Wear Resistance of Microarc Oxidation Coatings

    Directory of Open Access Journals (Sweden)

    Zhen-Wei Li

    2017-06-01

    Full Text Available Microarc oxidation (MAO coatings were prepared on 2024-T4 aluminum alloys using a pulsed bipolar power supply at different anode pulse-widths. After the MAO coatings were formed, the micropores and microcracks on the surface of the MAO coatings were filled with Fluorinated ethylene propylene (FEP dispersion for preparing MAO self-lubricating composite coatings containing FEP. The effect of the anode pulse-width on the microstructure and wear resistance of the microarc oxidation coatings was investigated. The wear resistance of the microarc oxidation self-lubricating composite coatings was analyzed. The results revealed that the MAO self-lubricating composite coatings integrated the advantages of wear resistance of the MAO ceramic coatings and a low friction coefficient of FEP. Compared to the MAO coatings, the microarc oxidation self-lubricating composite coatings exhibited a lower friction coefficient and lower wear rates.

  19. Iron oxide nanoparticles with different polymer coatings for photothermal therapy

    Science.gov (United States)

    Yang, Jia; Fan, Lu; Xu, Yanhong; Xia, Jindong

    2017-10-01

    Iron oxide nanoparticles (Fe3O4 NPs) have attracted significant attention in view of their potential applications in biomedicine. Surface coatings or modifications are generally needed to improve the colloidal stability of Fe3O4 NPs in a physiological environment. In this study, Fe3O4 NPs in the size range of 12-15 nm coated with polyacrylic acid (PAA), poly(vinyl alcohol) (PVA), and polyethyleneimine (PEI) were synthesized through a mild reduction route to investigate their potential for photothermal therapy. The polymer-coated Fe3O4 NPs dispersed well in water and formed stable colloids; the surface charges of the particles were dependent on the nature of the surface coating. The strong absorption in the near-infrared (NIR) region enabled the coated Fe3O4 NPs to be used as agents in photothermal therapy. The photothermal conversion efficiency of PEI-coated Fe3O4 NPs (PEI-Fe3O4 NPs) distinctly decreased when exposed to a cell culture medium. In addition, PEI-Fe3O4 NPs showed higher cytotoxicity and enhanced cellular uptake efficiency when compared to PAA-coated Fe3O4 NPs (PAA-Fe3O4 NPs) and PVA-coated Fe3O4 NPs (PVA-Fe3O4 NPs). This study highlights the importance of optimizing the surface properties of Fe3O4 NPs when using them in biomedical applications and provides guidelines for the design and development of functional Fe3O4 NPs for cancer therapy. [Figure not available: see fulltext.

  20. Inhibition of Sulfide Mineral Oxidation by Surface Coating Agents: Batch

    Science.gov (United States)

    Choi, J.; Ji, M. K.; Yun, H. S.; Park, Y. T.; Gee, E. D.; Lee, W. R.; Jeon, B.-H.

    2012-04-01

    Mining activities and mineral industries have impacted on rapid oxidation of sulfide minerals such as pyrite (FeS2) which leads to Acid Mine Drainage (AMD) formation. Some of the abandoned mines discharge polluted water without proper environmental remediation treatments, largely because of financial constraints in treating AMD. Magnitude of the problem is considerable, especially in countries with a long history of mining. As metal sulfides become oxidized during mining activities, the aqueous environment becomes acid and rich in many metals, including iron, lead, mercury, arsenic and many others. The toxic heavy metals are responsible for the environmental deterioration of stream, groundwater and soils. Several strategies to remediate AMD contaminated sites have been proposed. Among the source inhibition and prevention technologies, microencapsulation (coating) has been considered as a promising technology. The encapsulation is based on inhibition of O2 diffusion by surface coating agent and is expected to control the oxidation of pyrite for a long time. Potential of several surface coating agents for preventing oxidation of metal sulfide minerals from both Young-Dong coal mine and Il-Gwang gold mine were examined by conducting batch experiments and field tests. Powdered pyrite as a standard sulfide mineral and rock samples from two mine outcrops were mixed with six coating agents (KH2PO4, MgO and KMnO4 as chemical agents, and apatite, cement and manganite as mineral agents) and incubated with oxidizing agents (H2O2 or NaClO). Batch experiments with Young-Dong coal mine samples showed least SO42- production in presence of KMnO4 (16% sulfate production compared to no surface coating agents) or cement (4%) within 8 days. In the case of Il-Gwang mine samples, least SO42- production was observed in presence of KH2PO4 (8%) or cement (2%) within 8 days. Field-scale pilot tests at Il-Gwang site also showed that addition of KH2PO4 decreased sulfate production from 200 to

  1. Oxidation Prevention Properties of Reduced Graphene Oxide Mixed with 1-Octanethiol-Coated Copper Nanopowder Composites

    OpenAIRE

    Danee Cho; Dahyun Choi; Youngjun Pyo; Rajendra C. Pawar; Yongil Kim; Yoon, Eric H.; Caroline Sunyong Lee

    2016-01-01

    1-Octanethiol-coated Cu nanoparticles were mixed with reduced graphene oxide (rGO) to fabricate Cu nanoinks with enhanced oxidation prevention. Graphene oxide (GO) was synthesized using modified Hummer’s method and rGO was reduced from GO using hydrazine hydrate. Copper nanoinks were fabricated with varying concentrations of rGO (Cu : rGO ratios of 100 : 1, 500 : 1, and 1000 : 1 wt.%). The coating layers on the copper nanoparticles and rGO were observed using transmission electron microscopy ...

  2. Effect of Anode Pulse-Width on the Microstructure and Wear Resistance of Microarc Oxidation Coatings

    OpenAIRE

    Zhen-Wei Li; Shi-Chun Di

    2017-01-01

    Microarc oxidation (MAO) coatings were prepared on 2024-T4 aluminum alloys using a pulsed bipolar power supply at different anode pulse-widths. After the MAO coatings were formed, the micropores and microcracks on the surface of the MAO coatings were filled with Fluorinated ethylene propylene (FEP) dispersion for preparing MAO self-lubricating composite coatings containing FEP. The effect of the anode pulse-width on the microstructure and wear resistance of the microarc oxidation coatings was...

  3. Influence of electrolytes (TEABF4 and TEMABF4) on electrochemical performance of graphite oxide derived from needle coke.

    Science.gov (United States)

    Yang, Sunhye; Kim, Ick-Jun; Choi, In-Sik; Bae, Mi-Kyeong; Kim, Hyun-Soo

    2013-05-01

    The structure of needle coke was changed to graphite oxide structure after oxidation treatment with 70 wt.% of nitric acid and sodium chlorate (NaClO3), and the inter-layer distance of the oxidized needle coke was expanded to 6.9 angstroms. The first charge profile of the oxidized needle coke-cell with 1.2 M TEMABF4/acetonitrile solution displayed that the intercalation of electrolyte ions into the inter-layer occurred at 1.0 V, which value is lower than 1.3 V of the oxidized needle coke-cell with 1.2 M TEABF4/acetonitrile solution. After first charge/discharge, the cell using TEMABF4 electrolyte exhibited smaller electrode resistance of 0.05 omega, and larger specific volume capacitance of 25.5 F/ml at the two-electrode system in the potential range 0-2.5 V than those of the cell using TEABF4 electrolyte. Compared to the TEABF4 electrolyte, better electrochemical performance of the TEMABF4 electrolyte in the oxidized needle coke may be caused by the smaller cation (TEMA+) size and better ion mobility in the nanopores between inter-layers.

  4. Oxide Protective Coats for Ir/Re Rocket Combustion Chambers

    Science.gov (United States)

    Fortini, Arthur; Tuffias, Robert H.

    2003-01-01

    An improved material system has been developed for rocket engine combustion chambers for burning oxygen/ hydrogen mixtures or novel monopropellants, which are highly oxidizing at operating temperatures. The baseline for developing the improved material system is a prior iridium/rhenium system for chambers burning nitrogen tetroxide/monomethyl hydrazine mixtures, which are less oxidizing. The baseline combustion chamber comprises an outer layer of rhenium that provides structural support, plus an inner layer of iridium that acts as a barrier to oxidation of the rhenium. In the improved material system, the layer of iridium is thin and is coated with a thermal fatigue-resistant refractory oxide (specifically, hafnium oxide) that serves partly as a thermal barrier to decrease the temperature and thus the rate of oxidation of the rhenium. The oxide layer also acts as a barrier against the transport of oxidizing species to the surface of the iridium. Tests in which various oxygen/hydrogen mixtures were burned in iridium/rhenium combustion chambers lined with hafnium oxide showed that the operational lifetimes of combustion chambers of the improved material system are an order of magnitude greater than those of the baseline combustion chambers.

  5. Bacterial adhesion on amorphous and crystalline metal oxide coatings

    Energy Technology Data Exchange (ETDEWEB)

    Almaguer-Flores, Argelia [Facultad de Odontología, División de Estudios de Posgrado e Investigación, Universidad Nacional Autónoma de México, Circuito exterior s/n, Ciudad Universitaria, 04510 México D.F. (Mexico); Silva-Bermudez, Phaedra, E-mail: suriel21@yahoo.com [Unidad de Ingeniería de Tejidos, Terapia Celular y Medicina Regenerativa, Instituto Nacional de Rehabilitación, Calzada México-Xochimilco No. 289, Col. Arenal de Guadalupe, 14389 México D.F. (Mexico); Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, 04510 México D.F. (Mexico); Galicia, Rey; Rodil, Sandra E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, 04510 México D.F. (Mexico)

    2015-12-01

    Several studies have demonstrated the influence of surface properties (surface energy, composition and topography) of biocompatible materials on the adhesion of cells/bacteria on solid substrates; however, few have provided information about the effect of the atomic arrangement or crystallinity. Using magnetron sputtering deposition, we produced amorphous and crystalline TiO{sub 2} and ZrO{sub 2} coatings with controlled micro and nanoscale morphology. The effect of the structure on the physical–chemical surface properties was carefully analyzed. Then, we studied how these parameters affect the adhesion of Escherichia coli and Staphylococcus aureus. Our findings demonstrated that the nano-topography and the surface energy were significantly influenced by the coating structure. Bacterial adhesion at micro-rough (2.6 μm) surfaces was independent of the surface composition and structure, contrary to the observation in sub-micron (0.5 μm) rough surfaces, where the crystalline oxides (TiO{sub 2} > ZrO{sub 2}) surfaces exhibited higher numbers of attached bacteria. Particularly, crystalline TiO{sub 2}, which presented a predominant acidic nature, was more attractive for the adhesion of the negatively charged bacteria. The information provided by this study, where surface modifications are introduced by means of the deposition of amorphous or crystalline oxide coatings, offers a route for the rational design of implant surfaces to control or inhibit bacterial adhesion. - Highlights: • Amorphous (a) and crystalline (c) TiO{sub 2} and ZrO{sub 2} coatings were deposited. • The atomic ordering influences the coatings surface charge and nano-topography. • The atomic ordering modifies the bacterial adhesion for the same surface chemistry. • S. aureus adhesion was lower on a-TiO{sub 2} and a-ZrO{sub 2} than on their c-oxide counterpart. • E. coli adhesion on a-TiO{sub 2} was lower than on the c-TiO{sub 2}.

  6. Electrochemical Characterization of Ion Transport Properties of Poly(ethylene oxide)- and Poly(diethylene oxide-methylene oxide)-LiTFSI Electrolytes

    Science.gov (United States)

    Hasan, Alexandra; Pesko, Danielle; Balsara, Nitash

    Polymer electrolytes may enable the next generation of lithium-ion batteries with improved energy density and safety. Improving battery electrolyte performance requires the optimization of three independent transport properties: ionic conductivity, diffusion coefficient, and transference number. To gain a fundamental understanding of the relationship between monomer structure and ion transport, we compare the electrolyte properties of two linear polyethers, poly(ethylene oxide) (PEO) and poly(diethylene oxide-methylene oxide) (2EO-MO), mixed with bis(trifluoromethane)sulfonimide lithium salt (LiTSFI). We characterize the ion transport properties through potentiostatic methods including ac impedance spectroscopy, restricted diffusion, and steady-state current measurements as a function of temperature and salt concentration. Results indicate that PEO and 2EO-MO have comparable ionic conductivities, and 2EO-MO has a higher transference number throughout the entire concentration range. Impedance measurements also suggest that 2EO-MO has a lower interfacial resistance, indicating that charge transfer at the electrode surface occurs more rapidly. Our results suggest that monomer structure can be tuned in order to optimize ion transport properties of polymer electrolytes.

  7. Fuel electrode for solid oxide electrolyte fuel cell. Kotai denkaishitsugata nenryo denchi no nenryo denkyoku

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, A.

    1993-03-19

    Cermet mixed with nickel and stabilized zirconia (YSZ) is normally used for the fuel electrode of the high temperature solid oxide electrolyte fuel cell which uses coal gasification gas or natural gas as the primary fuel. When acidic YSZ is used as the aggregate for this electrode, however, carbon tends to precipitate to shorten the life of the fuel cell. This invention relates to means of preventing direct contact of hydrocarbon with the first porous electrode layer, wherein the first porous electrode layer containing YSZ aggregate and nickel metal or its oxide particles is formed on the surface of the solid electrolyte substrate, on which the second porous electrode layer containing basic aggregate and nickel metal or its oxide particles is formed. MgAl2O4, CaAl2O4, MgO[center dot]2TiO2, and MgO[center dot]ZrO2 are used as the basic aggregates which comprise the second porous electrode layer. 12 figs., 2 tabs.

  8. Tungsten oxide thin films obtained by anodisation in low electrolyte concentration

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Nadja B.D. da [Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas, Campus Capão do Leão, s/n, Pelotas, RS (Brazil); Pazinato, Julia C.O. [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Sombrio, Guilherme; Pereira, Marcelo B.; Boudinov, Henri [Instituto de Física, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Gündel, André; Moreira, Eduardo C. [Universidade Federal do Pampa, Travessa 45, 1650 Bagé, RS (Brazil); Garcia, Irene T.S., E-mail: irene.garcia@ufrgs.br [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil)

    2015-03-02

    Tungsten oxide nanostructured films were grown on tungsten substrates by anodisation under a fixed voltage and with sodium fluoride as electrolyte. The effect of the anion chloride and the influence of the modifying agent disodium hydrogen phosphate in the tungsten oxide films were also investigated. The structural characterisation of the films was performed by scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The band gap was determined through diffuse reflectance spectroscopy. The thin films were photoluminescent and emitted in the range of 300 to 630 nm when irradiated at 266 nm. The synthesised films efficiently degraded of methyl orange dye in the presence of hydrogen peroxide and 250 nm radiation. The modifying agent was responsible for the improvement of the photocatalytic activity. Films with similar photocatalytic performance were obtained when the system sodium fluoride and disodium hydrogen phosphate were replaced by sodium chloride. The porous structure and low band gap values were responsible for the photocatalytic behaviour. - Highlights: • Tungsten oxide thin films were obtained by anodisation of tungsten in aqueous media. • The performance of the NaCl, NaF and NaF/Na{sub 2}HPO{sub 4} as electrolytes was investigated. • The relation between structure and optical behaviour has been discussed. • Films obtained with NaCl and NaF/Na{sub 2}HPO{sub 4} present similar photocatalytic activity.

  9. Thiourea incorporated poly(ethylene oxide) as transparent gel polymer electrolyte for dye sensitized solar cell applications

    Science.gov (United States)

    Pavithra, Nagaraj; Velayutham, David; Sorrentino, Andrea; Anandan, Sambandam

    2017-06-01

    A new series of transparent gel polymer electrolytes are prepared by adding various weight percent of thiourea coupled with poly(ethylene oxide) for the application of dye-sensitized solar cells. Coupling of thiourea in the presence of iodine undergoes dimerization reaction to produce formamidine disulfide. Fourier Transform Infrared spectroscopy shows that the interactions of thiourea and formamidine disulfide with electronegative ether linkage of poly(ethylene oxide) results in conformational changes of gel polymer electrolytes. Electrochemical impedance spectroscopy and linear sweep voltammetry experiments reveal an increment in ionic conductivity and tri-iodide diffusion coefficient, for thiourea modified gel polymer electrolytes. Finally, the prepared electrolytes are used as a redox mediator in dye-sensitized solar cells and the photovoltaic properties were studied. Apart from transparency, the gel polymer electrolytes with thiorurea show higher photovoltaic properties compared to bare gel polymer electrolyte and a maximum photocurrent efficiency of 7.17% is achieved for gel polymer electrolyte containing 1 wt% of thiourea with a short circuit current of 11.79 mA cm-2 and open circuit voltage of 834 mV. Finally, under rear illumination, almost 90% efficiency is retained upon compared to front illumination.

  10. Photoluminescent polysaccharide-coated germanium(IV) oxide nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Lobaz, Volodymyr; Rabyk, Mariia; Pánek, Jiří; Doris, E.; Nallet, F.; Štěpánek, Petr; Hrubý, Martin

    2016-01-01

    Roč. 294, č. 7 (2016), s. 1225-1235 ISSN 0303-402X R&D Projects: GA MŠk(CZ) 7AMB14FR027; GA ČR(CZ) GA13-08336S; GA MZd(CZ) NV15-25781A Institutional support: RVO:61389013 Keywords : germanium oxide nanoparticles * polysaccharide coating * photoluminescent label Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.723, year: 2016

  11. In Situ Study of Strain-Dependent Ion Conductivity of Stretchable Polyethylene Oxide Electrolyte

    Science.gov (United States)

    Kelly, Taylor; Ghadi, Bahar Moradi; Berg, Sean; Ardebili, Haleh

    2016-02-01

    There is a strong need in developing stretchable batteries that can accommodate stretchable or irregularly shaped applications including medical implants, wearable devices and stretchable electronics. Stretchable solid polymer electrolytes are ideal candidates for creating fully stretchable lithium ion batteries mainly due to their mechanical and electrochemical stability, thin-film manufacturability and enhanced safety. However, the characteristics of ion conductivity of polymer electrolytes during tensile deformation are not well understood. Here, we investigate the effects of tensile strain on the ion conductivity of thin-film polyethylene oxide (PEO) through an in situ study. The results of this investigation demonstrate that both in-plane and through-plane ion conductivities of PEO undergo steady and linear growths with respect to the tensile strain. The coefficients of strain-dependent ion conductivity enhancement (CSDICE) for in-plane and through-plane conduction were found to be 28.5 and 27.2, respectively. Tensile stress-strain curves and polarization light microscopy (PLM) of the polymer electrolyte film reveal critical insights on the microstructural transformation of stretched PEO and the potential consequences on ionic conductivity.

  12. Evolution of Insulator-Metal Phase Transitions in Epitaxial Tungsten Oxide Films during Electrolyte-Gating.

    Science.gov (United States)

    Nishihaya, Shinichi; Uchida, Masaki; Kozuka, Yusuke; Iwasa, Yoshihiro; Kawasaki, Masashi; Nishihaya, S; Uchida, M; Kozuka, Y; Iwasa, Y; Kawasaki, M; Iwasa, Y; Kawasaki, M

    2016-08-31

    An interface between an oxide and an electrolyte gives rise to various processes as exemplified by electrostatic charge accumulation/depletion and electrochemical reactions such as intercalation/decalation under electric field. Here we directly compare typical device operations of those in electric double layer transistor geometry by adopting A-site vacant perovskite WO3 epitaxial thin films as a channel material and two different electrolytes as gating agent. In situ measurements of X-ray diffraction and channel resistance performed during the gating revealed that in both the cases WO3 thin film reaches a new metallic state through multiple phase transitions, accompanied by the change in out-of-plane lattice constant. Electrons are electrostatically accumulated from the interface side with an ionic liquid, while alkaline metal ions are more uniformly intercalated into the film with a polymer electrolyte. We systematically demonstrate this difference in the electrostatic and electrochemical processes, by comparing doped carrier density, lattice deformation behavior, and time constant of the phase transitions.

  13. Effect of pre-oxidation on the oxidation resistance of spinel-coated Fe-Cr ferritic alloy for solid oxide fuel cell applications

    Science.gov (United States)

    Ou, Ding Rong; Cheng, Mojie

    2014-02-01

    Low-temperature-sintered MnCo2O4-MnO2 coatings have been prepared on pre-oxidized SUS430 ferritic alloy by slurry coating. The effect of pre-oxidation treatment before slurry coating is then investigated. Microstructural and electrical characterizations show that 25 h of pre-oxidation at 800 °C could significantly improve the oxidation resistance of the coated alloy and effectively inhibit the increase in area-specific electrical resistance during long-term oxidation. These effects can be explained by the interfacial reactions between the coating and the pre-oxidized alloy during sintering and oxidation tests. Furthermore, this study suggests that the dense reaction layer at the coating-alloy interface could be the key to improving the oxidation resistance of metallic interconnects with low-temperature-sintered spinel coatings.

  14. Versatile ferrofluids based on polyethylene glycol coated iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Brullot, W., E-mail: ward.brullot@fys.kuleuven.be [Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Heverlee, Leuven (Belgium); Reddy, N.K. [Department of Chemical Engineering, Katholieke Universiteit Leuven, Willem de Croylaan 46, 3001 Heverlee, Leuven (Belgium); Wouters, J.; Valev, V.K.; Goderis, B. [Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Heverlee, Leuven (Belgium); Vermant, J. [Department of Chemical Engineering, Katholieke Universiteit Leuven, Willem de Croylaan 46, 3001 Heverlee, Leuven (Belgium); Verbiest, T. [Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Heverlee, Leuven (Belgium)

    2012-06-15

    Versatile ferrofluids based on polyethylene glycol coated iron oxide nanoparticles were obtained by a facile protocol and thoroughly characterized. Superparamagnetic iron oxide nanoparticles synthesized using a modified forced hydrolysis method were functionalized with polyethylene glycol silane (PEG silane), precipitated and dried. These functionalized particles are dispersable in a range of solvents and concentrations depending on the desired properties. Examples of tunable properties are magnetic behavior, optical and magneto-optical response, thermal features and rheological behavior. As such, PEG silane functionalized particles represent a platform for the development of new materials that have broad applicability in e.g. biomedical, industrial or photonic environments. Magnetic, optical, magneto-optical, thermal and rheological properties of several ferrofluids based on PEG coated particles with different concentrations of particles dispersed in low molecular mass polyethylene glycol were investigated, establishing the applicability of such materials. - Highlights: Black-Right-Pointing-Pointer Ferrofluids based on polyethylene glycol coated iron oxide nanoparticles. Black-Right-Pointing-Pointer Magnetic, optical, magneto-optical, thermal and rheological characterization of ferrofluids. Black-Right-Pointing-Pointer Tunable properties of versatile polyethylene glycol stabilized ferrofluids.

  15. Influence of the electrolyte's pH on the properties of electrochemically deposited hydroxyapatite coating on additively manufactured Ti64 alloy.

    Science.gov (United States)

    Vladescu, Alina; Vranceanu, Diana M; Kulesza, Slawek; Ivanov, Alexey N; Bramowicz, Mirosław; Fedonnikov, Alexander S; Braic, Mariana; Norkin, Igor A; Koptyug, Andrey; Kurtukova, Maria O; Dinu, Mihaela; Pana, Iulian; Surmeneva, Maria A; Surmenev, Roman A; Cotrut, Cosmin M

    2017-12-01

    Properties of the hydroxyapatite obtained by electrochemical assisted deposition (ED) are dependent on several factors including deposition temperature, electrolyte pH and concentrations, applied potential. All of these factors directly influence the morphology, stoichiometry, crystallinity, electrochemical behaviour, and particularly the coating thickness. Coating structure together with surface micro- and nano-scale topography significantly influence early stages of the implant bio-integration. The aim of this study is to analyse the effect of pH modification on the morphology, corrosion behaviour and in vitro bioactivity and in vivo biocompatibility of hydroxyapatite prepared by ED on the additively manufactured Ti64 samples. The coatings prepared in the electrolytes with pH = 6 have predominantly needle like morphology with the dimensions in the nanometric scale (~30 nm). Samples coated at pH = 6 demonstrated higher protection efficiency against the corrosive attack as compared to the ones coated at pH = 5 (~93% against 89%). The in vitro bioactivity results indicated that both coatings have a greater capacity of biomineralization, compared to the uncoated Ti64. Somehow, the coating deposited at pH = 6 exhibited good corrosion behaviour and high biomineralization ability. In vivo subcutaneous implantation of the coated samples into the white rats for up to 21 days with following histological studies showed no serious inflammatory process.

  16. Transport and viability of Escherichia coli cells in clean and iron oxide coated sand following coating with silver nanoparticles.

    Science.gov (United States)

    Ngwenya, Bryne T; Curry, Philip; Kapetas, Leon

    2015-08-01

    A mechanistic understanding of processes controlling the transport and viability of bacteria in porous media is critical for designing in situ bioremediation and microbiological water decontamination programs. We investigated the combined influence of coating sand with iron oxide and silver nanoparticles on the transport and viability of Escherichia coli cells under saturated conditions. Results showed that iron oxide coatings increase cell deposition which was generally reversed by silver nanoparticle coatings in the early stages of injection. These observations are consistent with short-term, particle surface charge controls on bacteria transport, where a negatively charged surface induced by silver nanoparticles reverses the positive charge due to iron oxide coatings, but columns eventually recovered irreversible cell deposition. Silver nanoparticle coatings significantly increased cell inactivation during transit through the columns. However, when viability data is normalised to volume throughput, only a small improvement in cell inactivation is observed for silver nanoparticle coated sands relative to iron oxide coating alone. This counterintuitive result underscores the importance of net surface charge in controlling cell transport and inactivation and implies that the extra cost for implementing silver nanoparticle coatings on porous beds coated with iron oxides may not be justified in designing point of use water filters in low income countries. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Microplasma synthesis on aluminum with additions of iron and nickel soluble complexes in electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Rogov, A.B., E-mail: alex-lab@bk.ru [Nikolaev Institute of Inorganic Chemistry. 3, Acad. Lavrentiev Ave, Novosibirsk, 630090 (Russian Federation); Mironov, I.V.; Terleeva, O.P.; Slonova, A.I. [Nikolaev Institute of Inorganic Chemistry. 3, Acad. Lavrentiev Ave, Novosibirsk, 630090 (Russian Federation)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Alkaline homogeneous electrolyte with transition metals complexes. Black-Right-Pointing-Pointer Coatings contain metallic iron, nickel and their oxides in alumina-silica matrix. Black-Right-Pointing-Pointer Effect of Fe/Ni ratio on coatings properties and process characteristics. - Abstract: The microplasma synthesis of coatings containing iron and nickel from homogeneous electrolytes has been studied. For stabilization of transition metals in solution, it is proposed to use chelation. It was found that the synthesis of coatings using alternating current leads to the formation of metallic iron and nickel particles in addition to oxide phases. The iron and nickel complexes concentrations ratio in the electrolyte correlates with the coatings composition. Obtained coatings have been studied by scanning electron microscopy with X-ray microanalyser and by X-ray diffraction with Cu and Mo radiation. The metal content in the coating was determined spectrophotometrically from the absorption of iron thiocyanate complexes and nickel dimethylglyoxime complex.

  18. Mechanical degradation of coating systems in high-temperature cyclic oxidation

    CSIR Research Space (South Africa)

    Pennefather, RC

    1996-01-01

    Full Text Available Cyclic oxidation tests were performed on a large variety of commercially available overlay coatings. The results confirmed that the composition of the coating as well as the processing method of the coating can affect the life of the system. Coating...

  19. Comparative study of bioactivity of collagen scaffolds coated with graphene oxide and reduced graphene oxide.

    Science.gov (United States)

    Kanayama, Izumi; Miyaji, Hirofumi; Takita, Hiroko; Nishida, Erika; Tsuji, Maiko; Fugetsu, Bunshi; Sun, Ling; Inoue, Kana; Ibara, Asako; Akasaka, Tsukasa; Sugaya, Tsutomu; Kawanami, Masamitsu

    2014-01-01

    Graphene oxide (GO) is a single layer carbon sheet with a thickness of less than 1 nm. GO has good dispersibility due to surface modifications with numerous functional groups. Reduced graphene oxide (RGO) is produced via the reduction of GO, and has lower dispersibility. We examined the bioactivity of GO and RGO films, and collagen scaffolds coated with GO and RGO. GO and RGO films were fabricated on a culture dish. Some GO films were chemically reduced using either ascorbic acid or sodium hydrosulfite solution, resulting in preparation of RGO films. The biological properties of each film were evaluated by scanning electron microscopy (SEM), atomic force microscopy, calcium adsorption tests, and MC3T3-E1 cell seeding. Subsequently, GO- and RGO-coated collagen scaffolds were prepared and characterized by SEM and compression tests. Each scaffold was implanted into subcutaneous tissue on the backs of rats. Measurements of DNA content and cell ingrowth areas of implanted scaffolds were performed 10 days post-surgery. The results show that GO and RGO possess different biological properties. Calcium adsorption and alkaline phosphatase activity were strongly enhanced by RGO, suggesting that RGO is effective for osteogenic differentiation. SEM showed that RGO-modified collagen scaffolds have rough, irregular surfaces. The compressive strengths of GO- and RGO-coated scaffolds were approximately 1.7-fold and 2.7-fold greater, respectively, when compared with the non-coated scaffold. Tissue ingrowth rate was 39% in RGO-coated scaffolds, as compared to 20% in the GO-coated scaffold and 16% in the non-coated scaffold. In summary, these results suggest that GO and RGO coatings provide different biological properties to collagen scaffolds, and that RGO-coated scaffolds are more bioactive than GO-coated scaffolds.

  20. Polypyrrole-coated samarium oxide nanobelts: fabrication, characterization, and application in supercapacitors

    Science.gov (United States)

    Liu, Peng; Wang, Yunjiao; Wang, Xue; Yang, Chao; Yi, Yanfeng

    2012-11-01

    Polypyrrole-coated samarium oxide nanobelts were synthesized by the in situ chemical oxidative surface polymerization technique based on the self-assembly of pyrrole on the surface of the amine-functionalized Sm2O3 nanobelts. The morphologies of the polypyrrole/samarium oxide (PPy/Sm2O3) nanocomposites were characterized using transmission electron microscope. The UV-vis absorbance of these samples was also investigated, and the remarkable enhancement was clearly observed. The electrochemical behaviors of the PPy/Sm2O3 composites were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge. The results indicated that the PPy/Sm2O3 composite electrode was fully reversible and achieved a very fast Faradaic reaction. After being corrected into the weight percentage of the PPy/Sm2O3 composite at a current density of 20 mA cm-2 in a 1.0 M NaNO3 electrolyte solution, a maximum discharge capacity of 771 F g-1 was achieved in a half-cell setup configuration for the PPy/Sm2O3 composites electrode with the potential application to electrode materials for electrochemical capacitors.

  1. Polypyrrole-coated samarium oxide nanobelts: fabrication, characterization, and application in supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Liu Peng, E-mail: pliu@lzu.edu.cn; Wang Yunjiao; Wang Xue; Yang Chao; Yi Yanfeng [College of Chemistry and Chemical Engineering, Lanzhou University, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry (China)

    2012-11-15

    Polypyrrole-coated samarium oxide nanobelts were synthesized by the in situ chemical oxidative surface polymerization technique based on the self-assembly of pyrrole on the surface of the amine-functionalized Sm{sub 2}O{sub 3} nanobelts. The morphologies of the polypyrrole/samarium oxide (PPy/Sm{sub 2}O{sub 3}) nanocomposites were characterized using transmission electron microscope. The UV-vis absorbance of these samples was also investigated, and the remarkable enhancement was clearly observed. The electrochemical behaviors of the PPy/Sm{sub 2}O{sub 3} composites were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge. The results indicated that the PPy/Sm{sub 2}O{sub 3} composite electrode was fully reversible and achieved a very fast Faradaic reaction. After being corrected into the weight percentage of the PPy/Sm{sub 2}O{sub 3} composite at a current density of 20 mA cm{sup -2} in a 1.0 M NaNO{sub 3} electrolyte solution, a maximum discharge capacity of 771 F g{sup -1} was achieved in a half-cell setup configuration for the PPy/Sm{sub 2}O{sub 3} composites electrode with the potential application to electrode materials for electrochemical capacitors.

  2. Electrolytic Synthesis of Ni-W-MWCNT Composite Coating for Alkaline Hydrogen Evolution Reaction

    Science.gov (United States)

    Elias, Liju; Hegde, A. Chitharanjan

    2018-01-01

    Nickel-tungsten multi-walled carbon nanotube (Ni-W-MWCNT) composite films were fabricated by an electrodeposition technique, and their electrocatalytic activity toward hydrogen evolution reaction (HER) was studied. Ni-W-MWCNT composite films with a homogeneous dispersion of MWCNTs were deposited from an optimal Ni-W plating bath containing functionalized MWCNTs, under galvanostatic condition. The presence of functionalized MWCNT was found to enhance the induced codeposition of the reluctant metal W and resulted in a W-rich composite coating with improved properties. The electrocatalytic behaviors of Ni-W-MWCNT composite coating toward HER were studied by cyclic voltammetry (CV) and chronopotentiometry techniques in 1.0 M KOH medium. Further, Tafel polarization and electrochemical impedance spectroscopy (EIS) studies were carried out to establish the kinetics of HER on the alloy and composite electrodes. The experimental results revealed that the addition of MWCNTs (having a diameter of around 10-15 nm) into the alloy plating bath has a significant effect on the electrocatalytic behavior of Ni-W alloy deposit. The Ni-W-MWCNT composite coating was found to show better HER activity than the conventional Ni-W alloy coating. The enhanced electrocatalytic activity of Ni-W-MWCNT composite coating is attributed to the MWCNT intersticed in the deposit matrix, evidenced by surface morphology, composition and phase structure of the coating through SEM, EDS and XRD analyses, respectively.

  3. Solid oxide reversible cells (SORCs) using LaGaO3-based oxide electrolyte and oxide fuel electrode

    Science.gov (United States)

    Ishihara, Tatsumi

    2017-09-01

    Activity of La0.8Sr0.2FeO3 (LSF) to the fuel electrode reaction in Solid Oxide Reversible Cells (SORCs) was investigated by using La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) and Ba0.6La0.4CoO3 (BLC) as electrolyte and air electrode, respectively. In electrolysis mode (SOEC), LSF electrode exhibited small overpotential under the atmosphere without H2 co-feeding; the current densities reached -1.42, -0.92, -0.36 A/cm2 at 1.4 V at 900, 800, 700 °C, respectively and H2 formation rate is well agreed with that estimated by Faraday's law. On the other hand, in the SOEC-SOFC reversible mode with the gas composition of 20% steam /20%H2/60%Ar, the maximum power densities of 0.42, 0.28, 0.11 W/cm2 were achieved at 900, 800 and 700 °C, respectively. In addition, the cyclic reversible operation was also investigated at 800 °C, and it was found that the cell showed high stability over 30 cycles. DC polarization measurement suggests that the exchange current density of LSF is 14 mA/cm2 at 700 °C, which is almost the same with that of Ni-YSZ reported. XRD measurement and SEM observation after the reversible measurement suggest that LSF is highly stable under SOEC-SOFC cyclic operation condition. Therefore, LSF is promising as the fuel electrode for SORCs, although the conductivity is not sufficiently high as electrode.

  4. Synthesis of yttria-doped bismuth oxide powder by carbonate coprecipitation for IT-SOFC electrolyte.

    Science.gov (United States)

    Lee, J G; Kim, S H; Yoon, H H

    2011-01-01

    Yttria-doped bismuth oxide (YBO) powders were synthesized by ammonium carbonate coprecipitation for the preparation of electrolytes of an intermediate temperature solid oxide fuel cell (IT-SOFC). The starting salts were yttrium and bismuth nitrate. The crystal structures and the morphological characteristics of the particles were analyzed by XRD and SEM, respectively. The ionic conductivity of the sintered pellet was measured by an electrochemical impedance analyzer. The size of the calcined YBO powders were in the range of 20-100 nm as measured by SEM images. The YBO pellets had a face-centered cubic structure, and their crystallite size was about 54-88 nm. The ionic conductivity of the YBO pellets sintered at 800 degrees C was observed to be 2.7 x 10(-1) Scm-(-1) at 700 degrees C. The ball-milling of the YBO powder before it was pelletized was found to have been unrequired probably because of a good sinterability of the YBO powders that was prepared via the ammonium carbonate coprecipitation method. The results showed that the ammonium carbonate coprecipitation process could be used as the cost-efficient method of producing YBO electrolytes for IT-SOFC.

  5. Osteogenic potential of a novel microarc oxidized coating formed on Ti6Al4V alloys

    Science.gov (United States)

    Wang, Yaping; Lou, Jin; Zeng, Lilan; Xiang, Junhuai; Zhang, Shufang; Wang, Jun; Xiong, Fucheng; Li, Chenglin; Zhao, Ying; Zhang, Rongfa

    2017-08-01

    In order to improve the biocompatibility, Ti6Al4V alloys are processed by micro arc oxidation (MAO) in a novel electrolyte of phytic acid, a natural organic phosphorus-containing matter. The MAO coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The cytocompatibility of Ti6A14V alloys before and after MAO were comprehensively evaluated. The results showed that the fabricated MAO coatings were composed of rutile, anatase, TiP2O7 as well as some OH- groups, exhibiting the excellent hydrophilicity and a porous structure with small micro pores. No cytotoxicity towards MC3T3-E1cells was observed in this study. In particular, MAO treated Ti6Al4V alloys presented comparable cell adhesion and proliferation as well as significantly enhanced alkaline phosphatase activity, extracellular matrix (ECM) mineralization and collagen secretion in comparison with the untreated control. The results suggest that the Ti6Al4V alloys treated by MAO in phytic acid can be used as implants for orthopaedic applications, providing a simple and practical method to widen clinical acceptance of titanium alloys.

  6. Weathering of tin oxide coated glass with low IR emissivity

    Energy Technology Data Exchange (ETDEWEB)

    Raedlein, E.; Buksak, A.; Heide, G.; Glaeser, H.J.; Frischat, G.H. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. fuer Nichtmetallische Werkstoffe

    2002-06-01

    The weathering of K-glass has been studied by measuring transmission and reflection in the visible (VIS), near infrared (NIR) and infrared (IR) wavelength ranges, by chemical depth profiling with secondary neutral mass spectrometry (SNMS) and by atomic force microscopy (AFM) imaging. K-glass is a commercial tin oxide coated glass with low IR emissivity. The SnO{sub 2}:F-coated side has been exposed to atmospheric conditions for up to 32 weeks and for up to two years. It could be shown that the optical properties are only affected in the VIS range, but the visible contamination does not influence the high IR reflection. This means that the heat-insulating properties of window glazings with the K-glass coating on the surface do not degrade under atmospheric conditions. Chemical depth profiles did not reveal major changes, except for an increase in the signals of minor elements on the surface, namely sodium, carbon and silicon. AFM showed that after 32 weeks the deep valleys of the rather rough crystalline SnO{sub 2}:F are partially filled up. The high transmission of new K-glass can be regained since contamination or corrosion products can be removed by washing. The coating itself is chemically stable. (orig.)

  7. Silicon oxide permeation barrier coating of PET bottles and foils

    Science.gov (United States)

    Steves, Simon; Deilmann, Michael; Awakowicz, Peter

    2009-10-01

    Modern packaging materials such as polyethylene terephthalate (PET) have displaced established materials in many areas of food and beverage packaging. Plastic packing materials offer are various advantages concerning production and handling. PET bottles for instance are non-breakable and lightweight compared to glass and metal containers. However, PET offers poor barrier properties against gas permeation. Therefore, the shelf live of packaged food is reduced. Permeation of gases can be reduced by depositing transparent plasma polymerized silicon oxide (SiOx) barrier coatings. A microwave (2.45 GHz) driven low pressure plasma reactor is developed based on a modified Plasmaline antenna to treat PET foils or bottles. To increase the barrier properties of the coatings furthermore a RF substrate bias (13.56 MHz) is applied. The composition of the coatings is analyzed by means of Fourier transform infrared (FTIR) spectroscopy regarding carbon and hydrogen content. Influence of gas phase composition and substrate bias on chemical composition of the coatings is discussed. A strong relation between barrier properties and film composition is found: good oxygen barriers are observed as carbon content is reduced and films become quartz-like. Regarding oxygen permeation a barrier improvement factor (BIF) of 70 is achieved.

  8. Data on the surface morphology of additively manufactured Ti-6Al-4V implants during processing by plasma electrolytic oxidation

    Directory of Open Access Journals (Sweden)

    Ingmar A.J. van Hengel

    2017-08-01

    Full Text Available Additively manufactured Ti-6Al-4V implants were biofunctionalized using plasma electrolytic oxidation. At various time points during this process scanning electron microscopy imaging was performed to analyze the surface morphology (van Hengel et al., 2017 [1]. This data shows the changes in surface morphology during plasma electrolytic oxidation. Data presented in this article are related to the research article “Selective laser melting porous metallic implants with immobilized silver nanoparticles kill and prevent biofilm formation by methicillin-resistant Staphylococcus aureus” (van Hengel et al., 2017 [1].

  9. Nanosized TiN-SBR hybrid coating of stainless steel as bipolar plates for polymer electrolyte membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Masanobu [Taiyo Stainless Spring Co. Ltd., 2-8-6 Shakujiicho, Nerimaku, Tokyo 177-0041 (Japan); Myung, Seung-Taek [Department of Chemical Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551 (Japan)], E-mail: smyung@iwate-u.ac.jp; Asaishi, Ryo [Department of Chemical Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551 (Japan); Sun, Yang-Kook [Department of Chemical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Yashiro, Hitoshi [Department of Chemical Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551 (Japan)], E-mail: yashiro@iwate-u.ac.jp

    2008-12-30

    In attempt to improve interfacial electrical conductivity of stainless steel for bipolar plates of polymer electrolyte membrane fuel cells, TiN nanoparticles were electrophoretically deposited on the surface of stainless steel with elastic styrene butadiene rubber (SBR) particles. From transmission electron microscopic observation, it was found that the TiN nanoparticles (ca. 50 nm) surrounded the spherical SBR particles (ca. 300-600 nm), forming agglomerates. They were well adhered on the surface of the type 310S stainless steel. With help of elasticity of SBR, the agglomerates were well fitted into the interfacial gap between gas diffusion layer (GDL) and stainless steel bipolar plate, and the interfacial contact resistance (ICR), simultaneously, was successfully reduced. A single cell using the TiN nanoparticles-coated bipolar plates, consequently, showed comparable cell performance with the graphite employing cell at a current density of 0.5 A cm{sup -2} (12.5 A). Inexpensive TiN nanoparticle-coated type 310S stainless steel bipolar plates would become a possible alternate for the expensive graphite bipolar plates as use in fuel cell applications.

  10. Fabrication of thin yttria-stabilized-zirconia dense electrolyte layers by inkjet printing for high performing solid oxide fuel cells

    DEFF Research Database (Denmark)

    Esposito, Vincenzo; Gadea, Christophe; Hjelm, Johan

    2015-01-01

    In this work, we present how a low-cost HP Deskjet 1000 inkjet printer was used to fabricate a 1.2 mm thin, dense and gas tight 16 cm2 solid oxide fuel cells (SOFC) electrolyte. The electrolyte was printed using an ink made of highly diluted (...) powders (50 nm in size) in an aqueous medium. The ink was designed to be a highly dispersed, long term stable colloidal suspension, with optimal printability characteristics. The electrolyte was made by a multiple printing procedure, which ensures coverage of the several flaws occurring in a single...... printing pass. Together with an optimized sintering procedure this resulted in good adhesion and densification of the electrolyte. The SOFC exhibited a close-to-theoretical open circuit voltage and a remarkable peak power density above 1.5 W cm-2 at 800 °C....

  11. Preparation and Properties of Microarc Oxidation Self-Lubricating Composite Coatings on Aluminum Alloy

    OpenAIRE

    Zhenwei Li; Shichun Di

    2017-01-01

    Microarc oxidation (MAO) coatings were prepared on 2024-T4 aluminum alloy using pulsed bipolar power supply at different cathode current densities. The MAO ceramic coatings contained many crater-like micropores and a small number of microcracks. After the MAO coatings were formed, the coated samples were immersed into a water-based Polytetrafluoroethylene (PTFE) dispersion. The micropores and microcracks on the surface of the MAO coatings were filled with PTFE dispersion for preparing MAO sel...

  12. Oxidation resistance of the nanostructured YSZ coating on the IN-738 superalloy

    Directory of Open Access Journals (Sweden)

    Ahmad Keyvani

    2014-12-01

    Full Text Available Conventional and nanostructured YSZ coatings were deposited on the IN-738 Ni super alloy by the atmospheric plasma spray technique. The oxidation was measured at 1100°C in an atmospheric electrical furnace. According to the experimental results the nanostructured coatings showed a better oxidation resistance than the conventional ones. The improved oxidation resistance of the nanocoating could be explained by the change in structure to a dense and more packed structure in this coating. The mechanical properties of the coatings were tested using the thermal cyclic, nanoindentation and bond strength tests, during which the nanostructured YSZ coating showed a better performance by structural stability.

  13. Virus-Assembled Flexible Electrode-Electrolyte Interfaces for Enhanced Polymer-Based Battery Applications

    Directory of Open Access Journals (Sweden)

    Ayan Ghosh

    2012-01-01

    Full Text Available High-aspect-ratio cobalt-oxide-coated Tobacco mosaic virus (TMV- assembled polytetrafluoroethylene (PTFE nonstick surfaces were integrated with a solvent-free polymer electrolyte to create an anode-electrolyte interface for use in lithium-ion batteries. The virus-assembled PTFE surfaces consisted primarily of cobalt oxide and were readily intercalated with a low-molecular-weight poly (ethylene oxide (PEO based diblock copolymer electrolyte to produce a solid anode-electrolyte system. The resulting polymer-coated virus-based system was then peeled from the PTFE backing to produce a flexible electrode-electrolyte component. Electrochemical studies indicated the virus-structured metal-oxide PEO-based interface was stable and displayed robust charge transfer kinetics. Combined, these studies demonstrate the development of a novel solid-state electrode architecture with a unique peelable and flexible processing attribute.

  14. Synthesis of coral-like tantalum oxide films via anodization in mixed organic-inorganic electrolytes.

    Directory of Open Access Journals (Sweden)

    Hongbin Yu

    Full Text Available We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two-electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 nm. The pores interlaced each other and the depth was about 150 nm. After calcination, the as-synthesized amorphous tantalum oxide could be crystallized to the orthorhombic crystal system. As observed in photocatalytic experiments, the coral-like tantalum oxide exhibited a higher photocatalytic activity for the degradation of phenol than that with a compact surface morphology, and the elimination rate of phenol increased by 66.7%.

  15. Synthesis of coral-like tantalum oxide films via anodization in mixed organic-inorganic electrolytes.

    Science.gov (United States)

    Yu, Hongbin; Zhu, Suiyi; Yang, Xia; Wang, Xinhong; Sun, Hongwei; Huo, Mingxin

    2013-01-01

    We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two-electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 nm. The pores interlaced each other and the depth was about 150 nm. After calcination, the as-synthesized amorphous tantalum oxide could be crystallized to the orthorhombic crystal system. As observed in photocatalytic experiments, the coral-like tantalum oxide exhibited a higher photocatalytic activity for the degradation of phenol than that with a compact surface morphology, and the elimination rate of phenol increased by 66.7%.

  16. Study on electrolytic reduction with controlled oxygen flow for iron from molten oxide slag containing FeO

    Directory of Open Access Journals (Sweden)

    Gao Y.M.

    2013-01-01

    Full Text Available A ZrO2-based solid membrane electrolytic cell with controlled oxygen flow was constructed: graphite rod /[O]Fe+C saturated / ZrO2(MgO/(FeO slag/iron crucible. The feasibility of extraction of iron from molten oxide slag containing FeO at an applied voltage was investigated by means of the electrolytic cell. The effects of some important process factors on the FeO electrolytic reduction with the controlled oxygen flow were discussed. The results show that: solid iron can be extracted from molten oxide slag containing FeO at 1450ºC and an applied potential of 4V. These factors, such as precipitation and growth of solid iron dendrites, change of the cathode active area on the inner wall of the iron crucible and ion diffusion flux in the molten slag may affect the electrochemical reaction rate. The reduction for Fe2+ ions mainly appears on new iron dendrites of the iron crucible cathode, and a very small amount of iron are also formed on the MSZ (2.18% MgO partially stabilized zirconia tube/slag interface due to electronic conductance of MSZ tube. Internal electronic current through MSZ tube may change direction at earlier and later electrolytic reduction stage. It has a role of promoting electrolytic reduction for FeO in the molten slag at the earlier stage, but will lower the current efficiency at the later stage. The final reduction ratio of FeO in the molten slag can achieve 99%. A novel electrolytic method with controlled oxygen flow for iron from the molten oxide slag containing FeO was proposed. The theory of electrolytic reduction with the controlled oxygen flow was developed.

  17. Effects of pH Value of the Electrolyte and Glycine Additive on Formation and Properties of Electrodeposited Zn-Fe Coatings

    Science.gov (United States)

    2013-01-01

    Environmentally friendly and cyanide-free sulfate bath under continuous current and the corrosion behavior of electrodeposits of zinc-iron alloys were studied by means of electrochemical tests in a solution of 3.5% NaCl in presence and absence of glycine. The effects of pH on the quality of Zn-Fe coatings were investigated in order to improve uniformity and corrosion protection performance of the coating films. The deposit morphology was analyzed using scanning electron microscopy (SEM), and X-ray diffraction (XRD) was used to determine the preferred crystallographic orientations of the deposits. It was found that the uniformity and corrosion resistance of Zn-Fe coating films were strongly associated with pH of the coating electrolyte. To obtain the effect of pH on the film quality and corrosion performances of the films, the corrosion test was performed with potentiodynamic anodic polarization method. It was also observed that uniformity and corrosion resistivity of the coating films were decreased towards pH = 5 and then improved with increasing pH value of the electrolyte. The presence of glycine in the plating bath decreases the corrosion resistance of Zn-Fe coatings. PMID:23844388

  18. Hybrid Adsorptive and Oxidative Removal of Natural Organic Matter Using Iron Oxide-Coated Pumice Particles

    Directory of Open Access Journals (Sweden)

    Sehnaz Sule Kaplan Bekaroglu

    2016-01-01

    Full Text Available The aim of this work was to combine adsorptive and catalytic properties of iron oxide surfaces in a hybrid process using hydrogen peroxide and iron oxide-coated pumice particles to remove natural organic matter (NOM in water. Experiments were conducted in batch, completely mixed reactors using various original and coated pumice particles. The results showed that both adsorption and catalytic oxidation mechanisms played role in the removal of NOM. The hybrid process was found to be effective in removing NOM from water having a wide range of specific UV absorbance values. Iron oxide surfaces preferentially adsorbed UV280-absorbing NOM fractions. Furthermore, the strong oxidants produced from reactions among iron oxide surfaces and hydrogen peroxide also preferentially oxidized UV280-absorbing NOM fractions. Preloading of iron oxide surfaces with NOM slightly reduced the further NOM removal performance of the hybrid process. Overall, the results suggested that the tested hybrid process may be effective for removal of NOM and control disinfection by-product formation.

  19. Transport and viability of Escherichia coli cells in clean and iron oxide coated sand following coating with silver nanoparticles

    OpenAIRE

    Ngwenya, Bryne

    2015-01-01

    A mechanistic understanding of processes controlling the transport and viability of bacteria in porous media is critical for designing in situ bioremediation and microbiological water decontamination programs. We investigated the combined influence of coating sand with iron oxide and silver nanoparticles on the transport and viability of Escherichia coli cells under saturated conditions. Results showed that iron oxide coatings increase cell deposition which was generally reversed by silver na...

  20. Tantalum oxide thin films as protective coatings for sensors

    DEFF Research Database (Denmark)

    Christensen, Carsten; Reus, Roger De; Bouwstra, Siebe

    1999-01-01

    Reactively sputtered tantalum oxide thin-films have been investigated as protective coating for aggressive media exposed sensors. Tantalum oxide is shown to be chemically very robust. The etch rate in aqueous potassium hydroxide with pH 11 at 140°C is lower than 0.008 Å/h. Etching in liquids with p......H values in the range from pH 2-11 have generally given etch rates below 0.04 Å/h. On the other hand patterning is possible in hydrofluoric acid. Further, the passivation behaviour of amorphous tantalum oxide and polycrystalline Ta2O5 is different in buffered hydrofluoric acid. By ex-situ annealing in O2...... the residual thin-film stress can be altered from compressive to tensile and annealing at 450°C for 30 minutes gives a stress-free film. The step coverage of the sputter deposited amorphous tantalum oxide is reasonable, but metallisation lines are hard to cover. Sputtered tantalum oxide exhibits high...

  1. Tantalum oxide thin films as protective coatings for sensors

    DEFF Research Database (Denmark)

    Christensen, Carsten; Reus, Roger De; Bouwstra, Siebe

    1999-01-01

    Reactively sputtered tantalum oxide thin films have been investigated as protective coatings for aggressive media exposed sensors. Tantalum oxide is shown to be chemically very robust. The etch rate in aqueous potassium hydroxide with pH 11 at 140°C is lower than 0.008 Å h-l. Etching in liquids...... with pH values in the range from pH 2 to 11 have generally given etch rates below 0.04 Å h-l. On the other hand patterning is possible in hydrofluoric acid. Further, the passivation behaviour of amorphous tantalum oxide and polycrystalline Ta2O5 is different in buffered hydrofluoric acid. By ex situ...... annealing O2 in the residual thin-film stress can be altered from compressive to tensile and annealing at 450°C for 30 minutes gives a stress-free film. The step coverage of the sputter deposited amorphous tantalum oxide is reasonable, but metallization lines are hard to cover. Sputtered tantalum oxide...

  2. Non-electrolytic synthesis of copper oxide/carbon nanocomposite by surface plasma in super-dehydrated ethanol

    Science.gov (United States)

    Kozak, Dmytro S.; Sergiienko, Ruslan A.; Shibata, Etsuro; Iizuka, Atsushi; Nakamura, Takashi

    2016-02-01

    Electrolytic processes are widely used to synthesize different nanomaterials and it does not depend on what kind of the method has been applied (wet-chemistry, sonochemistry, plasma chemistry, electrolysis and so on). Generally, the reactions in the electrolyte are considered to be reduction/oxidation (REDOX) reactions between chemical reagents or the deposition of matter on the electrodes, in line with Faraday’s law. Due to the presence of electroconductive additives in any electrolyte, the polarization effect of polar molecules conducting an electrical current disappears, when external high-strength electric field is induced. Because initially of the charge transfer always belongs of electroconductive additive and it does not depend on applied voltage. The polarization of ethanol molecules has been applied to conduct an electric current by surface plasma interaction for the synthesis of a copper oxide/carbon nanocomposite material.

  3. Operation of Thin-Film Electrolyte Metal-Supported Solid Oxide Fuel Cells in Lightweight and Stationary Stacks: Material and Microstructural Aspects

    Directory of Open Access Journals (Sweden)

    Daniel Roehrens

    2016-09-01

    Full Text Available In this study we report on the development and operational data of a metal-supported solid oxide fuel cell with a thin film electrolyte under varying conditions. The metal-ceramic structure was developed for a mobile auxiliary power unit and offers power densities of 1 W/cm2 at 800 °C, as well as robustness under mechanical, thermal and chemical stresses. A dense and thin yttria-doped zirconia layer was applied to a nanoporous nickel/zirconia anode using a scalable adapted gas-flow sputter process, which allowed the homogeneous coating of areas up to 100 cm2. The cell performance is presented for single cells and for stack operation, both in lightweight and stationary stack designs. The results from short-term operation indicate that this cell technology may be a very suitable alternative for mobile applications.

  4. Effects of ionic liquids on cation dynamics in amorphous polyethylene oxide electrolytes.

    Science.gov (United States)

    Chattoraj, Joyjit; Diddens, Diddo; Heuer, Andreas

    2014-01-14

    We perform extensive molecular dynamics simulations of a poly(ethylene oxide)-based polymer electrolyte material containing lithium bis(trifluoromethanesulfonyl)imide salt for a wide temperature regime above and below the experimental crystallization temperature with and without N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid (IL). The impact of the IL-concentration on the cation dynamics is studied. The increase of the cation mobility upon addition of IL is significant but temperature-independent. This can be related to distinct variations of the underlying transport properties as expressed within the previously introduced transport model of polymer electrolytes. Even for the largest IL concentration the transport model perfectly predicts the non-trivial time-dependence of the cationic mean square displacement for all temperatures. Finally, we compare our numerical and theoretical findings with the results of recent nuclear magnetic resonance experiments. In this way we can exclusively relate the strong experimentally observed dependence of the low-temperature Li-diffusivity on the IL concentration to the impact of IL on crystallization.

  5. Reduced graphene oxide aerogel with high-rate supercapacitive performance in aqueous electrolytes

    Science.gov (United States)

    2013-01-01

    Reduced graphene oxide aerogel (RGOA) is synthesized successfully through a simultaneous self-assembly and reduction process using hypophosphorous acid and I2 as reductant. Nitrogen sorption analysis shows that the Brunauer-Emmett-Teller surface area of RGOA could reach as high as 830 m2 g−1, which is the largest value ever reported for graphene-based aerogels obtained through the simultaneous self-assembly and reduction strategy. The as-prepared RGOA is characterized by a variety of means such as scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Electrochemical tests show that RGOA exhibits a high-rate supercapacitive performance in aqueous electrolytes. The specific capacitance of RGOA is calculated to be 211.8 and 278.6 F g−1 in KOH and H2SO4 electrolytes, respectively. The perfect supercapacitive performance of RGOA is ascribed to its three-dimensional structure and the existence of oxygen-containing groups. PMID:23692674

  6. Electrolytic Plasma Processing for Sequential Cleaning and Coating Deposition for Cadmium Plating Replacement

    Science.gov (United States)

    2008-08-01

    Department of Defense. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer , or otherwise...which Cd is currently being applied include AISI 4340, Hy-Tuf, Aermet 100, M50, 300M, PH13-8Mo stainless steel and maraging grades 200-250. The...power of the cyanide solutions. Additional corrosion resistance is often gained by applying a chromate conversion coating to the Cd-plated components

  7. Variable Emittance Electrochromics Using Ionic Electrolytes and Low Solar Absorptance Coatings

    Science.gov (United States)

    Chandrasekhar, Prasanna

    2011-01-01

    One of the last remaining technical hurdles with variable emittance devices or skins based on conducting polymer electrochromics is the high solar absorptance of their top surfaces. This high solar absorptance causes overheating of the skin when facing the Sun in space. Existing technologies such as mechanical louvers or loop heat pipes are virtually inapplicable to micro (< 20 kg) and nano (< 5 kg) spacecraft. Novel coatings lower the solar absorption to Alpha(s) of between 0.30 and 0.46. Coupled with the emittance properties of the variable emittance skins, this lowers the surface temperature of the skins facing the Sun to between 30 and 60 C, which is much lower than previous results of 100 C, and is well within acceptable satellite operations ranges. The performance of this technology is better than that of current new technologies such as microelectromechanical systems (MEMS), electrostatics, and electrophoretics, especially in applications involving micro and nano spacecraft. The coatings are deposited inside a high vacuum, layering multiple coatings onto the top surfaces of variable emittance skins. They are completely transparent in the entire relevant infrared region (about 2 to 45 microns), but highly reflective in the visible-NIR (near infrared) region of relevance to solar absorptance.

  8. Mitigation of chromium poisoning of cathodes in solid oxide fuel cells employing CuMn1.8O4 spinel coating on metallic interconnect

    Science.gov (United States)

    Wang, Ruofan; Sun, Zhihao; Pal, Uday B.; Gopalan, Srikanth; Basu, Soumendra N.

    2018-02-01

    Chromium poisoning is one of the major reasons for cathode performance degradation in solid oxide fuel cells (SOFCs). To mitigate the effect of Cr-poisoning, a protective coating on the surface of interconnect for suppressing Cr vaporization is necessary. Among the various coating materials, Cu-Mn spinel coating is considered to be a potential candidate due to their good thermal compatibility, high stability and good electronic conductivity at high temperature. In this study, Crofer 22 H meshes with no protective coating, those with commercial CuMn2O4 spinel coating and the ones with lab-developed CuMn1.8O4 spinel coating were investigated. The lab-developed CuMn1.8O4 spinel coating were deposited on Crofer 22 H mesh by electrophoretic deposition and densified by a reduction and re-oxidation process. With these different Crofer 22 H meshes (bare, CuMn2O4-coated, and CuMn1.8O4-coated), anode-supported SOFCs with Sr-doped LaMnO3-based cathode were electrochemically tested at 800 °C for total durations of up to 288 h. Comparing the mitigating effects of the two types of Cu-Mn spinel coatings on Cr-poisoning, it was found that the performance of the denser lab-developed CuMn1.8O4 spinel coating was distinctly better, showing no degradation in the cell electrochemical performance and significantly less Cr deposition near the cathode/electrolyte interface after the test.

  9. Comparison of iron and copper doped manganese cobalt spinel oxides as protective coatings for solid oxide fuel cell interconnects

    DEFF Research Database (Denmark)

    Talic, Belma; Molin, Sebastian; Wiik, Kjell

    2017-01-01

    MnCo2O4, MnCo1.7Cu0.3O4 and MnCo1.7Fe0.3O4 are investigated as coatings for corrosion protection of metallic interconnects in solid oxide fuel cell stacks. Electrophoretic deposition is used to deposit the coatings on Crofer 22 APU alloy. All three coating materials reduce the parabolic oxidation...

  10. Branched Rod-Coil Polyimide-Poly(Alkylene Oxide) Copolymers and Electrolyte Compositions

    Science.gov (United States)

    Meador, Maryann B. (Inventor); Tigelaar, Dean M. (Inventor)

    2014-01-01

    Crosslinked polyimide-poly(alkylene oxide) copolymers capable of holding large volumes of liquid while maintaining good dimensional stability. Copolymers are derived at ambient temperatures from amine endcapped amic-acid oligomers subsequently imidized in solution at increased temperatures, followed by reaction with trifunctional compounds in the presence of various additives. Films of these copolymers hold over four times their weight at room temperature of liquids such as ionic liquids (RTIL) and/or carbonate solvents. These rod-coil polyimide copolymers are used to prepare polymeric electrolytes by adding to the copolymers various amounts of compounds such as ionic liquids (RTIL), lithium trifluoromethane-sulfonimide (LiTFSi) or other lithium salts, and alumina.

  11. Nanostructured Gd-CeO2 electrolyte for solid oxide fuel cell by aqueous tape casting

    Science.gov (United States)

    Akbari-Fakhrabadi, A.; Mangalaraja, R. V.; Sanhueza, Felipe A.; Avila, Ricardo E.; Ananthakumar, S.; Chan, S. H.

    2012-11-01

    Gadolinia-doped ceria (Ce0.9Gd0.1O1.95, GDC) electrolyte was fabricated by aqueous-based tape casting method for solid oxide fuel cells (SOFCs). The ceramic powder prepared by combustion synthesis was used with poly acrylic acid (PAA), poly vinyl alcohol (PVA), poly ethylene glycol (PEG), Octanol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate and double distilled water as dispersant, binder, plasticizer, defoamer, surfactant and solvent respectively, to prepare stable GDC slurry. The conditions for preparing stable GDC slurries were studied and optimized by sedimentation, zeta potential and viscosity measurements. Green tapes with smooth surface, flexibility, thickness in the range of 0.35-0.4 mm and 45% relative green density were prepared. Conventional and flash sintering techniques were used and compared for densification which demonstrated the possibility of surpassing sintering at high temperatures and retarding related grain growth.

  12. Fe-doped 8YSZ at different composition for solid electrolyte in solid oxide fuel cell

    Directory of Open Access Journals (Sweden)

    Johar B.

    2016-01-01

    Full Text Available Pure 8 mol% yttria stabilized zirconia (YSZ and Fe-doped (1 mol%, 2 mol% and 3 mol% YSZ electrolyte were prepared and sintered at 1550°C. Transition metal oxide is added into YSZ as sintering aided has a function to reduce the sintering temperature. The microstructure, crystal structure and ionic conductivity of pure YSZ and Fe-doped YSZ at different composition were investigated. The amount of cubic phase decreased as the amount of Fe increased. Fe-doped 8YSZ had higher conductivity than pure 8YSZ. The ionic conductivity of 3FeYSZ is 9.35×10−8 S/cm higher than 1FeYSZ which is 4.72×10−9 S/cm when operated at 300°C.

  13. Ink-jet printing of electrolyte and anode functional layer for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Young, D.; Sukeshini, A.M.; Cummins, R. [Department of Mechanical and Materials Engineering, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH 45430 (United States); Xiao, H. [Aerospace Power and Propulsion, UES Corp., Dayton, OH 45432 (United States); Rottmayer, M.; Reitz, T. [The Air Force Research Laboratory, Propulsion Directorate, 1950 Fifth Street, Building 18, Wright-Patterson Air Force Base, OH 45433 (United States)

    2008-09-15

    In this work, solid oxide fuel cells were fabricated by ink-jet printing. The cells were characterized in order to study the resulting microstructure and electrochemical performance. Scanning electron microscopy revealed a highly conformal 6-12 {mu}m thick dense yttria-stabilized zirconia electrolyte layer, and a porous anode-interlayer. Open circuit voltages ranged from 0.95 to 1.06 V, and a maximum power density of 0.175 W cm{sup -2} was achieved at 750 C. These results suggest that the ink-jet printing technique may be used to fabricate stable SOFC structures that are comparable to those fabricated by more conventional ceramics processing methods. This study also highlights the significance of overall cell microstructural impact on cell performance and stability. (author)

  14. Data on the surface morphology of additively manufactured Ti-6Al-4V implants during processing by plasma electrolytic oxidation

    NARCIS (Netherlands)

    van Hengel, I.A.J.; Riool, Martijn; Fratila-Apachitei, E.L.; Witte-Bouma, Janneke; Farrell, Eric; Zadpoor, A.A.; Zaat, Sebastian A.J.; Apachitei, I.

    2017-01-01

    Additively manufactured Ti-6Al-4V implants were biofunctionalized using plasma electrolytic oxidation. At various time points during this process scanning electron microscopy imaging was performed to analyze the surface morphology (van Hengel et al., 2017) [1]. This data shows the changes in

  15. Data on the surface morphology of additively manufactured Ti-6Al-4V implants during processing by plasma electrolytic oxidation

    NARCIS (Netherlands)

    van Hengel, I.A.J. (Ingmar A.J.); M. Riool (Martijn); L.E. Fratila-Apachitei (L.); J. Witte-Bouma (Janneke); E. Farrell (Eric); A.A. Zadpoor (Amir Abbas); S.A.J. Zaat (Sebastiaan); I. Apachitei (I.)

    2017-01-01

    textabstractAdditively manufactured Ti-6Al-4V implants were biofunctionalized using plasma electrolytic oxidation. At various time points during this process scanning electron microscopy imaging was performed to analyze the surface morphology (van Hengel et al., 2017) [1]. This data shows the

  16. Effect of SiO 2 3–/OH–on plasma electrolytic oxidation of Ti–5Mo–4V ...

    Indian Academy of Sciences (India)

    Plasma electrolyte oxidation (PEO) was utilized to produce thick films on titanium and Ti–5Mo–4V–3Al alloys by immersing them in various solutions of Na2SiO3 and KOH with different concentrations to investigate the effect of SiO 3 2 − /OH– relations on the morphology and formed phases by utilizing SEM and XRD.

  17. Rotating disk electrode study of borohydride oxidation in a molten eutectic electrolyte and advancements in the intermediate temperature borohydride battery

    Science.gov (United States)

    Wang, Andrew; Gyenge, Előd L.

    2017-08-01

    The electrode kinetics of the NaBH4 oxidation reaction (BOR) in a molten NaOH-KOH eutectic mixture is investigated by rotating disk electrode (RDE) voltammetry on electrochemically oxidized Ni at temperatures between 458 K and 503 K. The BH4- diffusion coefficient in the molten alkali eutectic together with the BOR activation energy, exchange current density, transfer coefficient and number of electrons exchanged, are determined. Electrochemically oxidized Ni shows excellent BOR electrocatalytic activity with a maximum of seven electrons exchanged and a transfer coefficient up to one. X-ray photoelectron spectroscopy (XPS) reveals the formation of NiO as the catalytically active species. The high faradaic efficiency and BOR rate on oxidized Ni anode in the molten electrolyte compared to aqueous alkaline electrolytes is advantageous for power sources. A novel molten electrolyte battery design is investigated using dissolved NaBH4 at the anode and immobilized KIO4 at the cathode. This battery produces a stable open-circuit cell potential of 1.04 V, and a peak power density of 130 mW cm-2 corresponding to a superficial current density of 160 mA cm-2 at 458 K. With further improvements and scale-up borohydride molten electrolyte batteries and fuel cells could be integrated with thermal energy storage systems.

  18. Ionic conductivity studies of solid oxide fuel cell electrolytes and theoretical modeling of an entire solid oxide fuel cell

    Science.gov (United States)

    Pornprasertsuk, Rojana

    Because of the steep increase in oil prices, the global warming effect and the drive for energy independence, alternative energy research has been encouraged worldwide. The sustainable fuels such as hydrogen, biofuel, natural gas, and solar energy have attracted the attention of researchers. To convert these fuels into a useful energy source, an energy conversion device is required. Fuel cells are one of the energy conversion devices which convert chemical potentials into electricity. Due to their high efficiency, the ease to scale from 1 W range to megawatts range, no recharging requirement and the lack of CO2 and NOx emission (if H2 and air/O 2 are used), fuel cells have become a potential candidate for both stationary power generators and portable applications. This thesis has been focused primarily on solid oxide fuel cell (SOFC) studies due to its high efficiency, varieties of fuel choices, and no water management problem. At the present, however, practical applications of SOFCs are limited by high operating temperatures that are needed to create the necessary oxide-ion vacancy mobility in the electrolyte and to create sufficient electrode reactivities. This thesis introduces several experimental and theoretical approaches to lower losses both in the electrolyte and the electrodes. Yttria stabilized zirconia (YSZ) is commonly used as a solid electrolyte for SOFCs due to its high oxygen-ion conductivity. To improve the ionic conductivity for low temperature applications, an approach that involves dilating the structure by irradiation and introducing edge dislocations into the electrolyte was studied. Secondly, to understand the activation loss in SOFC, the kinetic Monte Carlo (KMC) technique was implemented to model the SOFC operation to determining the rate-limiting step due to the electrodes on different sizes of Pt catalysts. The isotope exchange depth profiling technique was employed to investigate the irradiation effect on the ionic transport in different

  19. Intermediate temperature solid oxide fuel cell based on lanthanum gallate electrolyte

    Science.gov (United States)

    Inagaki, Toru; Nishiwaki, Futoshi; Yamasaki, Satoru; Akbay, Taner; Hosoi, Kei

    The Kansai Electric Power Co. Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been developing intermediate temperature solid oxide fuel cells (IT-SOFCs) which are operable at a temperature range between 600 and 800 °C. There are some significant features in IT-SOFC of KEPCO-MMC: (1) highly conductive lanthanum gallate-based oxide is adopted as an electrolyte to realize high-performance disk-type electrolyte-supported cells; (2) the cell-stacks with seal-less structure using metallic separators allow residual fuel to burn around the stack and the combustion heat is utilized for thermally self-sustainable operation; (3) the separators have flexible arms by which separate compressive forces can be applied for manifold parts and interconnection parts. We are currently participating in the project by New Energy and Industrial Technology Development Organization (NEDO) to develop 10 kW-class combined heat and power (CHP) systems. In FY2006, a 10 kW-class module was developed, with which the electrical efficiency of 50%HHV was obtained based on DC 12.6 kW. In the first quarter of FY2007, the 10 kW-class CHP system using the module gave the electrical efficiency of 41%HHV on AC 10 kW and the overall efficiency of 82%HHV when exhaust heat was recovered as 60 °C hot water. Currently, the operation has been accumulated for about 2500 h to evaluate the long-term stability of the system.

  20. Nickel-silver alloy electrocatalysts for hydrogen evolution and oxidation in an alkaline electrolyte.

    Science.gov (United States)

    Tang, Maureen H; Hahn, Christopher; Klobuchar, Aidan J; Ng, Jia Wei Desmond; Wellendorff, Jess; Bligaard, Thomas; Jaramillo, Thomas F

    2014-09-28

    The development of improved catalysts for the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) in basic electrolytes remains a major technical obstacle to improved fuel cells, water electrolyzers, and other devices for electrochemical energy storage and conversion. Based on the free energy of adsorbed hydrogen intermediates, theory predicts that alloys of nickel and silver are active for these reactions. In this work, we synthesize binary nickel-silver bulk alloys across a range of compositions and show that nickel-silver alloys are indeed more active than pure nickel for hydrogen evolution and, possibly, hydrogen oxidation. To overcome the mutual insolubility of silver and nickel, we employ electron-beam physical vapor codeposition, a low-temperature synthetic route to metastable alloys. This method also produces flat and uniform films that facilitate the measurement of intrinsic catalytic activity with minimal variations in the surface area, ohmic contact, and pore transport. Rotating-disk-electrode measurements demonstrate that the hydrogen evolution activity per geometric area of the most active catalyst in this study, Ni0.75Ag0.25, is approximately twice that of pure nickel and has comparable stability and hydrogen oxidation activity. Our experimental results are supported by density functional theory calculations, which show that bulk alloying of Ni and Ag creates a variety of adsorption sites, some of which have near-optimal hydrogen binding energy.

  1. Fabrication of electrospun silk fibroin scaffolds coated with graphene oxide and reduced graphene for applications in biomedicine.

    Science.gov (United States)

    Aznar-Cervantes, Salvador; Martínez, Jose G; Bernabeu-Esclapez, Antonia; Lozano-Pérez, A Abel; Meseguer-Olmo, Luis; Otero, Toribio F; Cenis, Jose L

    2016-04-01

    Silk fibroin and graphene are both promising biomaterials described in the bibliography. Hybrid scaffolds combining their properties could be attractive for tissue engineering applications. In this work, a new methodology to produce electrospun fibroin scaffolds coated with graphene materials is provided. The mechanical, electrical and electrochemical properties of the materials attained were characterised. The fibre diameters were measured (from 3.9 to 5.2 μm). The samples coated with reduced grapheme were electronic conductors and electroactive in liquid electrolytes, showing maximum oxidation and reduction (around−0.4 V peak). The chronoamperometric responses showed a reduction shoulder, pointing to the entrance of balancing cations from the solution by nucleation–relaxation: the reaction induced structural changes in the graphene. In order to check the biocompatibility of the materials, they were seeded with L929 fibroblasts. The excellent biocompatibility of silk fibroin meshes was maintained after coating with graphene, being the proliferation results equal in all the treatments 7 days after the seeding (Tukey, p N 0.05).The conductive and electroactive properties of meshes coated with reduced graphene allow the potential application of local electric fields or local ionic currents to cell cultures, biological interfaces or animal models without host response.

  2. Ion-Conductive Properties of a Polymer Electrolyte Based on Ethylene Carbonate/Ethylene Oxide Random Copolymer.

    Science.gov (United States)

    Morioka, Takashi; Nakano, Koji; Tominaga, Yoichi

    2017-04-01

    A random copolymer of ethylene oxide with CO2 , namely, poly(ethylene carbonate/ethylene oxide) (P(EC/EO)), has been synthesized as a novel candidate for polymer electrolytes. Electrolyte composed of P(EC/EO) and lithium bis(fluorosulfonyl)imide has an ionic conductivity of 0.48 mS cm-1 and a Li transference number (t+ ) of 0.66 at 60 °C. To study ion-conductive behavior of P(EC/EO)-based electrolytes, the Fourier transform infrared (FT-IR) technique is used to analyze the interactions between Li+ and functional groups of the copolymer. The carbonate groups may interact preferentially with Li+ rather than the ether groups in P(EC/EO). This study suggests that copolymerization of carbonate and flexible ether units can realize both high conductivity and t+ for polymer electrolytes. High-performance P(EC/EO) electrolyte is expected to be a candidate material for use in all-solid-state batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Influence of Pt particles on the porosity of Al{sub 2}O{sub 3} coating prepared by cathode plasma electrolytic deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng [Beijing Key Laboratory for Corrosion, Erosion and Surface Technology, University of Science and Technology Beijing, 100083, Beijing (China); Research Institute of Aerospace Special Materials and Processing Technology, 100074, Beijing (China); He, Yedong, E-mail: htgroup@mater.ustb.edu.cn [Beijing Key Laboratory for Corrosion, Erosion and Surface Technology, University of Science and Technology Beijing, 100083, Beijing (China); Zhang, Jin [Beijing Key Laboratory for Corrosion, Erosion and Surface Technology, University of Science and Technology Beijing, 100083, Beijing (China)

    2016-12-01

    Porous Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-Pt coatings were successfully prepared on the Ni-based alloy by cathode plasma electrolytic deposition. It is found that the porosity of coatings can be reduced obviously by Pt particles co-deposited with Al{sub 2}O{sub 3}. This phenomenon can be attributed to that the mechanism of plasma discharge is changed in such CPED. As the Pt particles are dispersed in the Al{sub 2}O{sub 3} coating, the electron avalanche is difficult to occur. So, the breakdown takes place in the Al{sub 2}O{sub 3}-Pt coating difficultly, the destructive effect of the breakdown will therefore be decreased, and the porosity of Al{sub 2}O{sub 3} coating can be reduced which has been verified by the results of surface morphologies of the coatings. - Highlights: • The Al{sub 2}O{sub 3}-Pt coatings were prepared on Ni-based alloys by CPED. • The porosity of coating is reduced obviously by Pt particles dispersed with Al{sub 2}O{sub 3}. • The related mechanisms of plasma discharge in CPED were discussed.

  4. Influence of oxidation temperature on the oxide scale formation of NiCoCrAl coatings

    Science.gov (United States)

    Sugiarti, E.; Zaini, K. A.; Sundawa, R.; Wang, Y.; Ohnuki, S.; Hayashi, S.

    2017-04-01

    Intermetalic coatings of NiCoCrAl have been successfully developed on low carbon steel substrate to improve oxidation resistance in extreme environments. The influence of oxidation temperature on the oxide scale formation was studied in the temperature range of 600-1000 °C. The measurements were made in air under isothermal oxidation test for 100 h. The surface morphology showed that a cauliflower like structure developed entire the oxide scale of sample oxidized at 800 °C and 1000 °C, while partly distributed on the surface of sample oxidized at 600 °C. The XRD analysis identified Cr2O3 phase predominantly formed on the oxidized sample at 600 °C and meta-stable Al2O3 with several polymorphs crystalline structures: η, δ, θ, κ, and α-Al2O3 at relatively high temperatures, i.e. 800 °C and 1000 °C. A Cross-sectional microstructure showed that complex and porous structures formed on the top surface of 600 °C and 1000 °C samples. In contrast, a very thin oxide scale formed on 800 °C oxidized samples and it appeared to act as a diffusion barrier of oxygen to diffuse inward, hence could increase in the service life of carbon steel substrate.

  5. Effect of Nb Doping on High Temperature Oxidation Resistance of Ti-Al Alloyed Coatings

    Directory of Open Access Journals (Sweden)

    DAI Jing-jie

    2017-02-01

    Full Text Available Ti-Al alloyed coatings with different Nb doping contents were fabricated on TC4 titanium alloy by laser surface alloying to improve high temperature oxidation resistance of the alloy. Structures and high temperature oxidation behaviors of the alloyed coatings were analyzed and tested by X-ray diffraction (XRD, scanning electron microscope (SEM, energy dispersive spectrometer (EDS and box-type resistance furnace. The results show that the alloyed coatings consist of TiAl and Ti3Al, and no niobium compound are formed in Ti-Al-Nb alloyed coatings. The alloyed coatings are uniform and exhibit excellent metallurgical bonding with the substrates. A large amount of surface cracks and a few penetrating cracks are formed in Ti-Al alloyed coating without Nb doping, while no obvious cracks are formed in Ti-Al alloyed coating with Nb doping. The oxidation mass gains of all the alloyed coatings were significantly lower than those of the substrate. The alloyed coatings with Nb doping exhibit more excellent high temperature oxidation resistance due to the beneficial machanism of Nb doping. The mechanism of Nb doping on improving high temperature oxidation resistance of Ti-Al alloyed coatings includes reducing the defect concentration of TiO2, refining oxide grains and promoting the formation of Al2O3.

  6. Effects of nano-zinc oxide based paint on weathering performance of coated wood

    OpenAIRE

    Can, Ahmet; Sivrikaya, Hüseyin

    2014-01-01

    Nano-sized zinc oxide (ZnO) was chosen as a suitable candidate for the UV-protection of coatings. The accelerated weathering performances of Scots pine coated with wood paint mixed with nano- ZnO were investigated. Uncoated specimens, specimens coated with only nano-ZnO and nano-zinc oxide based paint were used as references. This work describes the effect of the nanoparticles and paint performance on accelerated weathering performance of coated specimens. 1 ml and 3 ml nano-zinc oxide is add...

  7. Urea coated with oxidized charcoal reduces ammonia volatilization

    Directory of Open Access Journals (Sweden)

    Diogo Mendes de Paiva

    2012-08-01

    Full Text Available Urea is the most consumed nitrogen fertilizer in the world. However, its agronomic and economic efficiency is reduced by the volatilization of NH3, which can reach 78 % of the applied nitrogen. The coating of urea granules with acidic compounds obtained by charcoal oxidation has the potential to reduce the volatilization, due to the acidic character, the high buffering capacity and CEC. This work aimed to evaluate the effect of HNO3-oxidized carbon on the control of NH3 volatilization. These compounds were obtained by oxidation of Eucalyptus grandis charcoal, produced at charring temperatures of 350 and 450 ºC, with 4.5 mol L-1 HNO3. The charcoal was oxidized by solubilization in acidic or alkaline medium, similar to the procedure of soil organic matter fractionation (CHox350 and CHox450. CHox was characterized by C, H, O, N contents and their respective atomic relations, by the ratio E4 (absorbance 465 nm by E6 (absorbance 665 nm, and by active acidity and total acidity (CEC. The inhibitory effect of CHox on the urease activity of Canavalia ensiformis was assessed in vitro. The NH3 volatilization from urea was evaluated with and without coating of oxidized charcoal (U-CHox350 or U-CHox450 in a closed system with continuous air flow. The pH of both CHox was near 2.0, but the total acidity of CHox350 was higher, 72 % of which was attributed to carboxylic groups. The variation in the ionization constants of CHox350 was also greater. The low E4/E6 ratios characterize the high stability of the compounds in CHox. CHox did not inhibit the urease activity in vitro, although the maximum volatilization peak from U-CHox450 and U-CHox350 occurred 24 h after that observed for uncoated urea. The lowest volatilization rate was observed for U-CHox350 as well as a 43 % lower total amount of NH3 volatilized than from uncoated urea.

  8. In situ infrared characterisation of the interfacial oxide during the anodic dissolution of a silicon electrode in fluoride electrolytes

    Science.gov (United States)

    da Fonseca, C.; Ozanam, F.; Chazalviel, J.-N.

    1996-09-01

    The interfacial oxides formed under steady-state anodic polarisation of p-silicon in fluoride electrolytes have been studied using in situ infrared spectroscopy in the difference mode. The oxide is characterized in the 900 to 1250 cm -1 range by the vSiO TO and LO bands, and by other absorption bands related to oxide defects such as non-bridging oxygens. The shape and magnitude of all these bands strongly depend on formation potential as well as on electrolyte composition. Oxide thickness can be estimated from the intensity of the TO absorption band. It is shown to increase with potential and to be little dependent on electrolyte composition. On the other hand, obtaining reliable structural information requires to quantitatively account for both LO and TO bands. Specifically, the frequency splitting between LO and TO modes as well as a properly defined average frequency appear as the relevant parameters. In the present case, the oxides grown at low current (i.e., for low fluoride concentration and at potentials corresponding to the second electropolishing plateau) are those exhibiting a high SiO vibrator density and a low defect concentration.

  9. Gentamicin coated iron oxide nanoparticles as novel antibacterial agents

    Science.gov (United States)

    Bhattacharya, Proma; Neogi, Sudarsan

    2017-09-01

    Applications of different types of magnetic nanoparticles for biomedical purposes started a long time back. The concept of surface functionalization of the iron oxide nanoparticles with antibiotics is a novel technique which paves the path for further application of these nanoparticles by virtue of their property of superparamagnetism. In this paper, we have synthesized novel iron oxide nanoparticles surface functionalized with Gentamicin. The average size of the particles, concluded from the HR-TEM images, came to be around 14 nm and 10 nm for unmodified and modified nanoparticles, respectively. The magnetization curve M(H) obtained for these nanoparticles are typical of superparamagnetic nature and having almost zero values of coercivity and remanance. The release properties of the drug coated nanoparticles were studied; obtaining an S shaped profile, indicating the initial burst effect followed by gradual sustained release. In vitro investigations against various gram positive and gram negative strains viz Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis indicated significant antibacterial efficiency of the drug-nanoparticle conjugate. The MIC values indicated that a small amount like 0.2 mg ml-1 of drug capped particles induce about 98% bacterial death. The novelty of the work lies in the drug capping of the nanoparticles, which retains the superparamagnetic nature of the iron oxide nanoparticles and the medical properties of the drug simultaneously, which is found to extremely blood compatible.

  10. Antibacterial activity of polymer coated cerium oxide nanoparticles.

    Directory of Open Access Journals (Sweden)

    Vishal Shah

    Full Text Available Cerium oxide nanoparticles have found numerous applications in the biomedical industry due to their strong antioxidant properties. In the current study, we report the influence of nine different physical and chemical parameters: pH, aeration and, concentrations of MgSO(4, CaCl(2, KCl, natural organic matter, fructose, nanoparticles and Escherichia coli, on the antibacterial activity of dextran coated cerium oxide nanoparticles. A least-squares quadratic regression model was developed to understand the collective influence of the tested parameters on the anti-bacterial activity and subsequently a computer-based, interactive visualization tool was developed. The visualization allows us to elucidate the effect of each of the parameters in combination with other parameters, on the antibacterial activity of nanoparticles. The results indicate that the toxicity of CeO(2 NPs depend on the physical and chemical environment; and in a majority of the possible combinations of the nine parameters, non-lethal to the bacteria. In fact, the cerium oxide nanoparticles can decrease the anti-bacterial activity exerted by magnesium and potassium salts.

  11. Antibacterial Activity of Polymer Coated Cerium Oxide Nanoparticles

    Science.gov (United States)

    Shah, Vishal; Shah, Shreya; Shah, Hirsh; Rispoli, Fred J.; McDonnell, Kevin T.; Workeneh, Selam; Karakoti, Ajay; Kumar, Amit; Seal, Sudipta

    2012-01-01

    Cerium oxide nanoparticles have found numerous applications in the biomedical industry due to their strong antioxidant properties. In the current study, we report the influence of nine different physical and chemical parameters: pH, aeration and, concentrations of MgSO4, CaCl2, KCl, natural organic matter, fructose, nanoparticles and Escherichia coli, on the antibacterial activity of dextran coated cerium oxide nanoparticles. A least-squares quadratic regression model was developed to understand the collective influence of the tested parameters on the anti-bacterial activity and subsequently a computer-based, interactive visualization tool was developed. The visualization allows us to elucidate the effect of each of the parameters in combination with other parameters, on the antibacterial activity of nanoparticles. The results indicate that the toxicity of CeO2 NPs depend on the physical and chemical environment; and in a majority of the possible combinations of the nine parameters, non-lethal to the bacteria. In fact, the cerium oxide nanoparticles can decrease the anti-bacterial activity exerted by magnesium and potassium salts. PMID:23110109

  12. Plasma electrolytic oxidation of AZ91D magnesium alloy with different additives and its corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Fa-he; Cao, Jiang-lin; Zhang, Zhao [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Zhang, Jian-qing; Cao, Chu-nan [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); State Key Laboratory for Corrosion and Protection, Institute of Metal Research, The Chinese Academy of Sciences, Shenyang 110016 (China)

    2007-09-15

    Plasma electrolytic oxidation (PEO) of Mg-based AZ91D alloys was investigated using 50 Hz AC anodizing technique in an alkaline borate solution, which contained a new kind of organic additive and without F, P, and Cr. The anodizing technological parameters have been optimized and a kind of ivory-white smooth anodic film with high corrosion resistance was obtained. It was found that the formation of the anodic films was always coupled with sparking and oxygen evolution, whose intensity changed with the additive and anodizing voltage. All EIS plots have two capacitive loops and one low frequency inductive component. Two capacitive arcs present the barrier and porous layer of the PEO film and the inductive component in the low frequency domain is a complex behavior due to the porous structure connected to the electrolyte. EIS plots and fitting results show that a self-sealing process of the PEO firm with different additives takes place in the beginning of immersion time, then corrosion attack becomes a preponderant process to promote the degradation of the film. Tafel results show that PEO treatment decreases the corrosion current density by four, even five orders of magnitude, while additives content does not affect strongly the electrochemical corrosion behavior. Salt spray test shows that the PEO film formed with NaAlO{sub 2} and Na{sub 2}SiO{sub 3} presents good corrosion resistance, over 600 h without any sealing treatment. The difference of corrosion resistance arose by additives examined by electrochemical techniques and salt spray test does not show strict corresponding relationship. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  13. Graphene Oxide Bionanocomposite Coatings with High Oxygen Barrier Properties

    Directory of Open Access Journals (Sweden)

    Ilke Uysal Unalan

    2016-12-01

    Full Text Available In this work, we present the development of bionanocomposite coatings on poly(ethylene terephthalate (PET with outstanding oxygen barrier properties. Pullulan and graphene oxide (GO were used as main polymer phase and nanobuilding block (NBB, respectively. The oxygen barrier performance was investigated at different filler volume fractions (ϕ and as a function of different relative humidity (RH values. Noticeably, the impermeable nature of GO was reflected under dry conditions, in which an oxygen transmission rate (OTR, mL·m−2·24 h−1 value below the detection limit of the instrument (0.01 mL·m−2·24 h−1 was recorded, even for ϕ as low as 0.0004. A dramatic increase of the OTR values occurred in humid conditions, such that the barrier performance was totally lost at 90% RH (the OTR of coated PET films was equal to the OTR of bare PET films. Modelling of the experimental OTR data by Cussler’s model suggested that the spatial ordering of GO sheets within the main pullulan phase was perturbed because of RH fluctuations. In spite of the presence of the filler, all the formulations allowed the obtainment of final materials with haze values below 3%, the only exception being the formulation with the highest loading of GO (ϕ ≈ 0.03. The mechanisms underlying the experimental observations are discussed.

  14. Molecular dynamics simulation of polymer electrolytes based on poly(ethylene oxide) and ionic liquids. II. Dynamical properties.

    Science.gov (United States)

    Costa, Luciano T; Ribeiro, Mauro C C

    2007-10-28

    Dynamical properties of polymer electrolytes based on poly(ethylene oxide) (PEO) and ionic liquids of 1-alkyl-3-methylimidazolium cations were calculated by molecular dynamics simulations with previously proposed models [L. T. Costa and M. C. Ribeiro, J. Chem. Phys. 124, 184902 (2006)]. The effect of changing the ionic liquid concentration, temperature, and the 1-alkyl-chain lengths, [1,3-dimethylimidazolium]PF(6) and [1-butyl-3-methylimidazolium]PF(6) ([dmim]PF(6) and [bmim]PF(6)), was investigated. Cation diffusion coefficient is higher than those of anion and oxygen atoms of PEO chains. Ionic mobility in PEO[bmim]PF(6) is higher than in PEO[dmim]PF(6), so that the ionic conductivity kappa of the former is approximately ten times larger than the latter. The ratio between kappa and its estimate from the Nernst-Einstein equation kappa/kappa(NE), which is inversely proportional to the strength of ion pairs, is higher in ionic liquid polymer electrolytes than in polymer electrolytes based on inorganic salts with Li(+) cations. Calculated time correlation functions corroborate previous evidence from the analysis of equilibrium structure that the ion pairs in ionic liquid polymer electrolytes are relatively weak. Structural relaxation at distinct spatial scales is revealed by the calculation of the intermediate scattering function at different wavevectors. These data are reproduced with stretched exponential functions, so that temperature and wavevector dependences of best fit parameters can be compared with corresponding results for polymer electrolytes containing simpler ions.

  15. Effects of Voltage on Microstructure and Corrosion Resistance of Micro-arc Oxidation Ceramic Coatings Formed on KBM10 Magnesium Alloy

    Science.gov (United States)

    Lu, J. P.; Cao, G. P.; Quan, G. F.; Wang, C.; Zhuang, J. J.; Song, R. G.

    2018-01-01

    Micro-arc oxidation (MAO) coatings on KBM10 magnesium alloy were prepared in an electrolyte system with sodium silicate, potassium hydroxide, sodium tungstate, and citric acid. The effects of voltage on the microstructure and corrosion resistance of MAO coatings were studied using stereoscopic microscopy, scanning electron microscopy, x-ray diffraction, scratch tests, potentiodynamic polarization, and electrochemical impedance spectroscopy. The results showed that the roughness of the MAO coatings, diameter, and number of pores increase with the increase in voltage. The coating formed at the voltage of 350 V exhibited the best adhesive strength when evaluated by the automatic scratch tester. The coatings were mainly composed of MgO, MgWO4, and Mg2SiO4, and the content of Mg2SiO4 increased with the increase in voltage. The corrosion resistance of MAO coatings could be improved by changing the applied voltage, and the best corrosion resistance of MAO coating was observed at the voltage of 350 V.

  16. Mussel-Inspired Polydopamine Coated Iron Oxide Nanoparticles for Biomedical Application

    Directory of Open Access Journals (Sweden)

    Xiangling Gu

    2015-01-01

    Full Text Available Mussel-inspired polydopamine (PDA coated iron oxide nanoparticles have served as a feasible, robust, and functional platform for various biomedical applications. However, there is scarcely a systemic paper reviewed about such functionalising nanomaterials to date. In this review, the synthesis of iron oxide nanoparticles, the mechanism of dopamine self-oxidation, the interaction between iron oxide and dopamine, and the functionality and the safety assessment of dopamine modified iron oxide nanoparticles as well as the biomedical application of such nanoparticles are discussed. To enlighten the future research, the opportunities and the limitations of functionalising iron oxide nanoparticles coated with PDA are also analyzed.

  17. Ambient temperature proton polymeric electrolytes based on poly(ethylene oxide)-poly(methyl methacrylate) blends

    Energy Technology Data Exchange (ETDEWEB)

    Przyluski, J. (Div. of Solid State Tech., Dept. of Chemistry, Warsaw Univ. of Tech., Warszawa (Poland)); Dabrowska, A. (Div. of Solid State Tech., Dept. of Chemistry, Warsaw Univ. of Tech., Warszawa (Poland)); Stys, S. (Div. of Solid State Tech., Dept. of Chemistry, Warsaw Univ. of Tech., Warszawa (Poland)); Wieczorek, W. (Div. of Solid State Tech., Dept. of Chemistry, Warsaw Univ. of Tech., Warszawa (Poland))

    1993-03-01

    The paper deals with utilization of polymeric electrolytes based on complexes of phosphoric acid or ammonium thiocyanate with electrodonor polymerin ambient temperature fuel cells. Properties of the studied electrolytes are described on the basis of impedance spectroscopy and differential scanning calorimetry data. Impedance spectroscopy studies of the fuel cells evidenced that the electrode-electrolyte interfacial phenomena play a crucial role on the cell performance. (orig.)

  18. Preparation and Properties of Microarc Oxidation Self-Lubricating Composite Coatings on Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Zhenwei Li

    2017-04-01

    Full Text Available Microarc oxidation (MAO coatings were prepared on 2024-T4 aluminum alloy using pulsed bipolar power supply at different cathode current densities. The MAO ceramic coatings contained many crater-like micropores and a small number of microcracks. After the MAO coatings were formed, the coated samples were immersed into a water-based Polytetrafluoroethylene (PTFE dispersion. The micropores and microcracks on the surface of the MAO coatings were filled with PTFE dispersion for preparing MAO self-lubricating composite coatings. The microstructure and properties of MAO coatings and the wear resistance of microarc oxidation self-lubricating composite coatings were analyzed by SEM, laser confocal microscope, X-ray diffractometry (XRD, Vickers hardness test, scratch test and ball-on-disc abrasive tests, respectively. The results revealed that the wear rates of the MAO coatings decreased significantly with an increase in cathode current density. Compared to the MAO coatings, the microarc oxidation self-lubricating composite coatings exhibited a lower friction coefficient and lower wear rates.

  19. Hydrothermal signature in ferromanganese oxide coatings on pumice from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Kalangutkar, N.G.; Iyer, S.D.; Mascarenhas-Pereira, M.B.L.; Nath, B.N.

    oxide coats and botryoidal structure suggest accretion by colloidal formation. Radiolarians and phillipsite (Fig. 3d) were included at later stage within the vesicles. Phillipsite is a mineral formed essentially during diagenesis. The XRD analyses... to identify a hydrothermal influence to understand the genesis of the FeMn oxides. The patchy oxide coats and botryoidal structure of FeMn suggest accretion by colloidal formation. The pumice samples usually contain clay, within the vesicles, which has ion...

  20. Hydrophobic coating of polyaniline-poly(propylene oxide) copolymer for direct immersion solid phase microextraction of carbamate pesticides.

    Science.gov (United States)

    Ai, Youhong; Zhang, Jingqiang; Zhao, Faqiong; Zeng, Baizhao

    2015-08-14

    A nanostructural polyaniline-poly(propylene oxide) (PANI-PPO) composite coating was electrochemically synthesized on a stainless steel wire, by using acidic ionic liquid 1-sulfobutyl-3-methylimidazolium hydrosulfate as supporting electrolyte. The coating showed strong hydrophobicity and allowed for the direct immersion solid-phase microextraction of carbamate pesticides (i.e. 2-(1-methylethoxy) phenyl methylcarbamate, m-tolyl-n-methylcarbamate, 2-(1-methylethyl) phenyl methylcarbamate, 2-(1-methylpropyl) phenol methylcarbamate and 2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) in complex matrices. Moreover, this coating could be used for at least 120 times of extraction. When it was coupled with gas chromatography for the determination of these carbamate pesticides the linear ranges were about 0.1-100 μg L(-1) and the detection limits were 0.012-0.048 μg L(-1). It also displayed acceptable repeatability and reproducibility. When a fiber was used for five successive measurements the relative standard deviations (RSDs) were smaller than 8.7%, and the RSDs for fiber-to-fiber were 5.7-12.9% (n=5). The practical feasibility of the proposed method was evaluated by determining carbamate pesticides in vegetable samples and the recoveries for standards added were 79.8-108.8%. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. The oxidation behavior of classical thermal barrier coatings exposed to extreme temperature

    Directory of Open Access Journals (Sweden)

    Alina DRAGOMIRESCU

    2017-03-01

    Full Text Available Thermal barrier coatings (TBC are designed to protect metal surfaces from extreme temperatures and improve their resistance to oxidation during service. Currently, the most commonly used systems are those that have the TBC structure bond coat (BC / top coat (TC layers. The top coat layer is a ceramic layer. Oxidation tests are designed to identify the dynamics of the thermally oxide layer (TGO growth at the interface of bond coat / top coat layers, delamination mechanism and the TBC structural changes induced by thermal conditions. This paper is a short study on the evolution of aluminum oxide protective layer along with prolonged exposure to the testing temperature. There have been tested rectangular specimens of metal super alloy with four surfaces coated with a duplex thermal barrier coating system. The specimens were microscopically and EDAX analyzed before and after the tests. In order to determine the oxide type, the samples were analyzed using X-ray diffraction. The results of the investigation are encouraging for future studies. The results show a direct relationship between the development of the oxide layer and long exposure to the test temperature. Future research will focus on changing the testing temperature to compare the results.

  2. A study of ferrocene diffusion dynamics in network poly(ethylene oxide) polymer electrolyte by solid-state voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, M.; Longmire, M.L.; Murray, R.W. (Univ. of North Carolina, Chapel Hill (USA))

    1990-03-22

    The diffusion rates of five ferrocene derivatives dissolved in an amorphous, cross-linked poly(ethylene oxide) (PEO) polymer electrolyte are measured by an electrochemical technique which detects the rate of their transport to an oxidizing microdisk electrode. The diffusion coefficients in dilute ferrocene/polymer solutions at 65{degree}C vary from 3 {times} 10{sup {minus}7} to 2 {times} 10{sup {minus}8} cm{sup 2} s{sup {minus}1} depending on the size of the ferrocene derivative. The diffusion coefficients decrease with increasing ferrocene concentration, increasing LiClO{sub 4} electrolyte concentration, and decreasing temperature; values approaching 10{sup {minus}10} cm{sup 2} s{sup {minus}1} are encountered at room temperature.

  3. Gas diffusion layers coated with a microporous layer containing hydrophilic carbon nanotubes for performance enhancement of polymer electrolyte fuel cells under both low and high humidity conditions

    Science.gov (United States)

    Kitahara, Tatsumi; Nakajima, Hironori; Okamura, Kosuke

    2015-06-01

    Gas diffusion layers (GDLs) coated with a hydrophobic microporous layer (MPL) composed of carbon black and polytetrafluoroethylene (PTFE) have been commonly used to improve the water management characteristics of polymer electrolyte fuel cells (PEFCs). However, the hydrophobic MPL coated GDL designed to prevent dehydration of the membrane under low humidity conditions is generally inferior at reducing flooding under high humidity conditions. It is therefore important to develop a robust MPL coated GDL that can enhance the PEFC performance regardless of the humidity conditions. In the present study, a GDL coated with an MPL containing hydrophilic carbon nanotubes (CNTs) was developed. The less hydrophobic pores incorporating CNTs are effective at conserving the membrane humidity under low humidity conditions. The MPL with CNTs is also effective at expelling excess water from the catalyst layer while maintaining oxygen flow pathways from the GDL substrate, allowing the mean flow pore diameter to be decreased to 2 μm without reducing the ability of the MPL to prevent flooding under high humidity conditions. An MPL coated GDL with a CNT content of 4 mass% exhibits significantly higher performance under both low and high humidity conditions than a hydrophobic MPL coated GDL.

  4. Electrolytic Production of Ti5Si3/TiC Composites by Solid Oxide Membrane Technology

    Science.gov (United States)

    Zheng, Kai; Zou, Xingli; Xie, Xueliang; Lu, Changyuan; Chen, Chaoyi; Xu, Qian; Lu, Xionggang

    2018-02-01

    This paper investigated the electrolytic production of Ti5Si3/TiC composites from TiO2/SiO2/C in molten CaCl2. The solid-oxide oxygen-ion-conducting membrane tube filled with carbon-saturated liquid tin was served as the anode, and the pressed spherical TiO2/SiO2/C pellet was used as the cathode. The electrochemical reduction process was carried out at 1273 K and 3.8 V. The characteristics of the obtained cathode products and the reaction mechanism of the electroreduction process were studied by a series of time-dependent electroreduction experiments. It was found that the electroreduction process generally proceeds through the following steps: TiO2/SiO2/C → Ti2O3, CaTiO3, Ca2SiO4, SiC → Ti5Si3, TiC. The morphology observation and the elemental distribution analysis indicate that the reaction routes for Ti5Si3 and TiC products are independent during the electroreduction process.

  5. Interstitial Oxide Ion Distribution and Transport Mechanism in Aluminum-Doped Neodymium Silicate Apatite Electrolytes.

    Science.gov (United States)

    An, Tao; Baikie, Tom; Orera, Alodia; Piltz, Ross O; Meven, Martin; Slater, Peter R; Wei, Jun; Sanjuán, María L; White, T J

    2016-04-06

    Rare earth silicate apatites are one-dimensional channel structures that show potential as electrolytes for solid oxide fuel cells (SOFC) due to their high ionic conductivity at intermediate temperatures (500-700 °C). This advantageous property can be attributed to the presence of both interstitial oxygen and cation vacancies, that create diffusion paths which computational studies suggest are less tortuous and have lower activation energies for migration than in stoichiometric compounds. In this work, neutron diffraction of Nd(28+x)/3AlxSi6-xO26 (0 ≤ x ≤ 1.5) single crystals identified the locations of oxygen interstitials, and allowed the deduction of a dual-path conduction mechanism that is a natural extension of the single-path sinusoidal channel trajectory arrived at through computation. This discovery provides the most thorough understanding of the O(2-) transport mechanism along the channels to date, clarifies the mode of interchannel motion, and presents a complete picture of O(2-) percolation through apatite. Previously reported crystallographic and conductivity measurements are re-examined in the light of these new findings.

  6. Mechanism for carbon direct electrochemical reactions in a solid oxide electrolyte direct carbon fuel cell

    Science.gov (United States)

    Li, Chen; Shi, Yixiang; Cai, Ningsheng

    The carbon direct electrochemical reactions in a solid oxide electrolyte direct carbon fuel cell (DCFC) are investigated experimentally with CH 4-deposited carbon at the anode as fuel. The surface morphology of the anode cross-sections is characterized using a scanning electron microscope (SEM), the elemental distribution using an energy dispersive spectrometer (EDS) and an X-ray photoelectron spectroscopy (XPS), and the deposited carbon microstructures using a Raman spectrometer. The results indicate that all the carbon deposited on the yttrium-stabilized zirconium (YSZ) particle surfaces, the Ni particle surfaces, as well as the three-phase boundary, can participate in the electrochemical reactions during the fuel cell discharging. The direct electrochemical reactions for carbon require the two conditions that the O 2- in the ionic conductor contact with a carbon reactive site and that the released electrons are conducted to the external circuit. The electrochemical reactions for the deposited carbon are most difficult on the Ni particle surfaces, easier on the YSZ particle surfaces and easiest at the three-phase boundary. Not all the carbon deposited in the anode participates in the direct electrochemical reactions. The deposited carbon and the O 2- in the YSZ react to form the double-bonded adsorbed carbonyl group C dbnd O.

  7. Microporous Ni-doped TiO2 film photocatalyst by plasma electrolytic oxidation.

    Science.gov (United States)

    Yao, Zhongping; Jia, Fangzhou; Tian, Shujun; Li, ChunXiang; Jiang, Zhaohua; Bai, Xuefeng

    2010-09-01

    Ni-doped TiO2 film catalysts were prepared by a plasma electrolytic oxidation (PEO) method and were mainly characterized by means of SEM, EDS, XRD, XPS, and DRS, respectively. The effects of Ni doping on the structure, composition and optical absorption property of the film catalysts were investigated along with their inherent relationships. The results show that the film catalyst is composed of anatase and rutile TiO2 with microporous structure. Doping Ni changes the phase composition and the lattice parameters (interplanar crystal spacing and cell volume) of the films. The optical absorption range of TiO2 film gradually expands and shifts to the red with increasing dosages. Both direct and indirect transition band gaps of the TiO2 films are deduced consequently. Moreover, the photocatalytic activity of the film catalysts for splitting Na2S+Na2SO3 solution into H2 is enhanced by doping with an appropriate amount of Ni. The as-prepared TiO2 film catalyst doping with 10 g/L of Ni(Ac)2 presents the highest photocatalytic reducing activity.

  8. Design of a novel immobilized solid acid coating and its application in Fenton-like oxidation of phenol

    Science.gov (United States)

    Wang, Jiankang; Jiang, Zhaohua; Wang, Yajing; Xia, Qixing; Yao, Zhongping

    2017-07-01

    A novel immobilized solid acid coating on Q235 carbon steel was successfully prepared via plasma electrolytic oxidation. Sulfate functionalized Fe3O4/FeAl2O4 was confirmed by XRD, TEM and XPS analysis and surface acidic property was verified by NH3-TPD measurement. Fenton-like degradation performance was evaluated by employing phenol as target pollutant. Fast phenol degradation under the wide range of pH (pH 6-9) was accomplished within only 11 min. Without sulfate functionalization, phenol could hardly be degraded by Fenton-like oxidation which meant that after sulfate functionalization the existence of acidic microenvironment on the catalyst surface not only provided an optimal circumstance for enhanced Fenton-like reaction, but also avoided adjusting pH of the treated wastewater. A reasonable Fenton-like degradation mechanism was proposed. This paper offered a novel design thought for synthesizing excellent Fenton-like coating catalyst under circumneutral pH.

  9. Oxides with polyatomic anions considered as new electrolyte materials for solid oxide fuel cells (SOFCs)

    Energy Technology Data Exchange (ETDEWEB)

    Bin Hassan, Oskar Hasdinor

    2010-10-21

    Materials with Polyatomic anions of [Al{sub 2}O{sub 7}]{sup -8}, [Ti{sub 2}O{sub 8}]{sup -8} and [P{sub 2}O{sub 7}]{sup -4} were investigated with respect to their ionic conductivity properties as well as its thermal expansion properties with the aim to use them as SOFCs electrolytes. The polyatomic anion groups selected from the oxy-cuspidine family of Gd{sub 4}Al{sub 2}O{sub 9} and Gd{sub 4}Ti{sub 2}O{sub 10} as well as from pyrophosphate SnP{sub 2}O{sub 7}. The pure oxy-cuspidine Gd{sub 4}Al{sub 2}O{sub 9}, the series of Gd{sub 4}Al{sub 2-x}Mg{sub x}O{sub 9-x/2} with x=0.10-1.0 and Gd{sub 4-x}M{sub x}Al{sub 2}O{sub 9-x/2} (M=Ca, Sr) with x = 0.05-0.5 were prepared successfully by the citrate complexation method. All samples showed the crystal structure of monoclinic oxycuspidine structure with space group of P2{sub 1/c} and Z=4. No solid solution was observed for Gd{sub 4}Al{sub 2-x}Mg{sub x}O{sub 9-x/2} where additional phases of Gd{sub 2}O{sub 3} and MgO were presence. XRD semiquantitative analysis together with SEM-EDX analysis revealed that Mg{sup 2+} was not able to substitute the Al{sup 3+} ions even at low Mg{sup 2+} concentration. The solid solution limit of Gd{sub 4-x}Ca{sub x}Al{sub 2}O{sub 9-x/2} and Gd{sub 4-x}Sr{sub x}Al{sub 2}O{sub 9-x/2} was determined between 0.05-0.10 and 0.01-0.05 mol for Ca and Sr, respectively. Beyond the substitution limit Gd{sub 4}Al{sub 2}O{sub 9}, GdAlO{sub 3} and SrGd{sub 2}Al{sub 2}O{sub 7} appeared as additional phases. The highest electrical conductivity obtained at 900 C yielded {sigma}= 1.49 x 10{sup -4}Scm{sup -1} for Gd{sub 3.95}Ca{sub 0.05}Al{sub 2}O{sub 8.98}. In comparison, the conductivity of pure Gd{sub 4}Al{sub 2}O{sub 9} was {sigma}= 1.73 x 10{sup -5} Scm{sup -1}. The conductivities determined were in a similar range as those of other cuspidine materials investigated previously. The thermal expansion coefficient of Gd{sub 4}Al{sub 2}O{sub 9} at 1000 C was 7.4 x 10{sup -6}K{sup -1}. The earlier reported

  10. Titanium-nitride-oxide-coated coronary stents: insights from the available evidence.

    Science.gov (United States)

    Karjalainen, Pasi P; Nammas, Wail

    2017-06-01

    Coating of stent surface with a biocompatible material is suggested to improve stent safety profile. A proprietary process was developed to coat titanium-nitride-oxide on the stent surface, based on plasma technology that uses the nano-synthesis of gas and metal. Preclinical in vitro and in vivo investigation confirmed blood compatibility of titanium (nitride-) oxide films. Titanium-nitride-oxide-coated stents demonstrated a better angiographic outcome, compared with bare-metal stents at mid-term follow-up; however, they failed to achieve non-inferiority for angiographic outcome versus second-generation drug-eluting stents. Observational studies showed adequate clinical outcome at mid-term follow-up. Non-randomized studies showed an outcome of titanium-nitride-oxide-coated stents comparable to - or better than - first-generation drug-eluting stents at long-term follow-up. Two randomized controlled trials demonstrated comparable efficacy outcome, and a better safety outcome of titanium-nitride-oxide-coated stents versus drug-eluting stents at long-term follow-up. Evaluation by optical coherence tomography at mid-term follow-up revealed better neointimal strut coverage associated with titanium-nitride-oxide-coated stents versus drug-eluting stents; yet, neointimal hyperplasia thickness was greater. Key messages Stents coated with titanium-nitride-oxide demonstrated biocompatibility in preclinical studies: they inhibit platelet and fibrin deposition, and reduce neointimal growth. In observational and non-randomized studies, titanium-nitride-oxide-coated stents were associated with adequate safety and efficacy outcome. In randomized trials of patients with acute coronary syndrome, titanium-nitride-oxide-coated stents were associated with a better safety outcome, compared with drug-eluting stents; efficacy outcome was comparable.

  11. Polypropylene oil as fuel for solid oxide fuel cell with samarium doped-ceria (SDC)-carbonate as electrolyte

    Science.gov (United States)

    Syahputra, R. J. E.; Rahmawati, F.; Prameswari, A. P.; Saktian, R.

    2017-03-01

    The research focusses on converting polypropylene oil as pyrolysis product of polypropylene plastic into an electricity. The converter was a direct liquid fuel-solid oxide fuel cell (SOFC) with cerium oxide based material as electrolyte. The polypropylene vapor flowed into fuel cell, in the anode side and undergo oxidation reaction, meanwhile, the Oxygen in atmosphere reduced into oxygen ion at cathode. The fuel cell test was conducted at 400 - 600 °C. According to GC-MS analysis, the polypropylene oil consist of C8 to C27 hydrocarbon chain. The XRD analysis result shows that Na2CO3 did not change the crystal structure of SDC even increases the electrical conductivity. The maximum power density is 0.079 mW.cm-2 at 773 K. The open circuite voltage is 0.77 volt. Chemical stability test by analysing the single cell at before and after fuel cell test found that ionic migration occured during fuel cell operation. It is supported by the change of elemental composition in the point position of electrolyte and at the electrolyte-electrode interface

  12. Effect of Perovskite coating on oxide scale growth on Fe-22Cr

    DEFF Research Database (Denmark)

    Persson, Åsa; Mikkelsen, Lars; Hendriksen, Peter Vang

    2006-01-01

    A coating consisting of La0.85Sr0.15MnO3 (LSM) was deposited onto two Fe 22 wt % Cr alloys Crofer 22APU and Sandvik lC44Mo20. The evolution of the oxide layers developing underneath the coatings during oxidation was investigated. The effect of the LSM coating on oxidation rate and microstructure...... of the oxide scale was investigated, and possible effects on the overall oxidation mechanism are discussed. It was found that the growth rate for coated Crofer 22APU was decreased by a factor of 3 in comparison with the uncoated samples, and the thickness of the chromia layer in the scales decreased in favor...

  13. Mussel-Inspired Polydopamine Coated Iron Oxide Nanoparticles for Biomedical Application

    OpenAIRE

    Gu, Xiangling; Zhang, Yancong; Sun, Hanwen; Song, Xinfeng; Fu, Chunhua; Dong, Pingxuan

    2015-01-01

    Mussel-inspired polydopamine (PDA) coated iron oxide nanoparticles have served as a feasible, robust, and functional platform for various biomedical applications. However, there is scarcely a systemic paper reviewed about such functionalising nanomaterials to date. In this review, the synthesis of iron oxide nanoparticles, the mechanism of dopamine self-oxidation, the interaction between iron oxide and dopamine, and the functionality and the safety assessment of dopamine modified iron oxide n...

  14. Preparation and performances of Co-Mn spinel coating on a ferritic stainless steel interconnect material for solid oxide fuel cell application

    Science.gov (United States)

    Zhang, H. H.; Zeng, C. L.

    2014-04-01

    Ferritic stainless steels have become the candidate materials for interconnects of intermediate temperature solid oxide fuel cell (SOFC). The present issues to be solved urgently for the application of ferritic stainless steel interconnects are their rapid increase in contact resistance and Cr poisoning. In the present study, a chloride electrolyte suspension has been developed to electro-deposit a Co-Mn alloy on a type 430 stainless steel, followed by heat treatment at 750 °C in argon and at 800 °C in air to obtain Co-Mn spinel coatings. The experimental results indicate that an adhesive and compact Co-Mn alloy layer can be deposited in the chloride solution. After heat treatment, a complex coating composed of an external MnCo2O4 layer and an inner Cr-rich oxide layer has been formed on 430SS. The coating improves the oxidation resistance of the steel at 800 °C in air, especially in wet air, and inhibits the outward diffusion of Cr from the Cr-rich scale. Moreover, a low contact resistance has been achieved with the application of the spinel coatings.

  15. High Transparent Metal Oxide / Polyimide Antistatic Coatings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA requires clear antistatic coatings that can withstand exposure to the rigors of the space environment. Agiltron proposes a coating consisting of inorganic...

  16. Characterization of porous TiO2 surfaces formed on 316L stainless steel by plasma electrolytic oxidation for stent applications

    NARCIS (Netherlands)

    Huan, Z.; Fratila-Apachitei, L.E.; Apachitei, I.; Duszczyk, J.

    2012-01-01

    In this study, a porous oxide layer was formed on the surface of 316L stainless steel (SS) by combining Ti magnetron sputtering and plasma electrolytic oxidation (PEO) with the aim to produce a polymer-free drug carrier for drug eluting stent (DES) applications. The oxidation was performed

  17. Application of a Coated Film Catalyst Layer Model to a High Temperature Polymer Electrolyte Membrane Fuel Cell with Low Catalyst Loading Produced by Reactive Spray Deposition Technology

    Directory of Open Access Journals (Sweden)

    Timothy D. Myles

    2015-10-01

    Full Text Available In this study, a semi-empirical model is presented that correlates to previously obtained experimental overpotential data for a high temperature polymer electrolyte membrane fuel cell (HT-PEMFC. The goal is to reinforce the understanding of the performance of the cell from a modeling perspective. The HT-PEMFC membrane electrode assemblies (MEAs were constructed utilizing an 85 wt. % phosphoric acid doped Advent TPS® membranes for the electrolyte and gas diffusion electrodes (GDEs manufactured by Reactive Spray Deposition Technology (RSDT. MEAs with varying ratios of PTFE binder to carbon support material (I/C ratio were manufactured and their performance at various operating temperatures was recorded. The semi-empirical model derivation was based on the coated film catalyst layer approach and was calibrated to the experimental data by a least squares method. The behavior of important physical parameters as a function of I/C ratio and operating temperature were explored.

  18. Grain boundary analysis and ionic conductivity of superplastic cubic zirconia for solid oxide fuel cell electrolytes

    Science.gov (United States)

    Martin, Michael Craig

    Yttrium stabilized zirconia (YSZ) is the material most commonly used for solid oxide fuel cell (SOFC) electrolytes because it has high oxygen ion conductivity at elevated temperatures. Manufacturing and sealing of the SOFC YSZ electrolyte is relatively expensive and cost could be reduced if the ceramic could be net shape formed. Methods to net shape form YSZ by superplastic deformation have been developed by introducing SiO2 as a second phase, but the impact of this approach on ionic conductivity was not known. This dissertation focuses on understanding how SiO2 affects the ionic conductivity of YSZ. The present work necessitated the design and fabrication of an appropriate impedance spectroscopy test capability and the preparation and evaluation of a matrix of samples with various silica amounts and grain sizes. Impedance spectroscopy is the figure of merit used to measure and evaluate ionic conductivity. Impedance spectroscopy at temperatures from 350 to 700°C and analytical electron microscopy were used to characterize grain boundary conductivity and grain boundary segregation of in 8 mol% yttrium cubic stabilized zirconia (8Y-CSZ). 1 to 10 wt% of silica was added as an intergranular phase. Grain growth experiments were conducted at temperatures of 1350°C to 1600°C for times from 0.1 to 100 hours. Grain boundary widths were determined from impedance spectroscopy data using a brick layer model. Average grain boundary widths were also determined from analytical electron microscopy conducted at Oak Ridge National Laboratory and the amount of yttrium and silicon segregation at grain boundaries was determined from chemical composition line scans. Results indicate that the addition of intergranular SiO2 to 8Y-CSZ leads to smaller grain size (due to grain boundary pinning) therefore increased grain boundary area and reduced total ionic conductivity. For a constant grain size, the specific grain boundary and the total ionic conductivity is not significantly affected

  19. Enhanced lithium battery with polyethylene oxide-based electrolyte containing silane-Al2 O3 ceramic filler.

    Science.gov (United States)

    Zewde, Berhanu W; Admassie, Shimelis; Zimmermann, Jutta; Isfort, Christian Schulze; Scrosati, Bruno; Hassoun, Jusef

    2013-08-01

    A solid polymer electrolyte prepared by using a solvent-free, scalable technique is reported. The membrane is formed by low-energy ball milling followed by hot-pressing of dry powdered polyethylene oxide polymer, LiCF3 SO3 salt, and silane-treated Al2 O3 (Al2 O3 -ST) ceramic filler. The effects of the ceramic fillers on the properties of the ionically conducting solid electrolyte membrane are characterized by using electrochemical impedance spectroscopy, XRD, differential scanning calorimeter, SEM, and galvanostatic cycling in lithium cells with a LiFePO4 cathode. We demonstrate that the membrane containing Al2 O3 -ST ceramic filler performs well in terms of ionic conductivity, thermal properties, and lithium transference number. Furthermore, we show that the lithium cells, which use the new electrolyte together with the LiFePO4 electrode, operate within 65 and 90 °C with high efficiency and long cycle life. Hence, the Al2 O3 -ST ceramic can be efficiently used as a ceramic filler to enhance the performance of solid polymer electrolytes in lithium batteries. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Oxidation Prevention Properties of Reduced Graphene Oxide Mixed with 1-Octanethiol-Coated Copper Nanopowder Composites

    Directory of Open Access Journals (Sweden)

    Danee Cho

    2016-01-01

    Full Text Available 1-Octanethiol-coated Cu nanoparticles were mixed with reduced graphene oxide (rGO to fabricate Cu nanoinks with enhanced oxidation prevention. Graphene oxide (GO was synthesized using modified Hummer’s method and rGO was reduced from GO using hydrazine hydrate. Copper nanoinks were fabricated with varying concentrations of rGO (Cu : rGO ratios of 100 : 1, 500 : 1, and 1000 : 1 wt.%. The coating layers on the copper nanoparticles and rGO were observed using transmission electron microscopy and characterized by X-ray photoemission spectroscopy, X-ray diffraction, and Raman spectroscopy. It was observed that surface roughness increased as the concentration of rGO in Cu patterns increased, and an optimized Cu : rGO weight ratio of 1,000 : 1 was established. After sintering, the electrical properties and corrosion resistance of copper patterns both with and without rGO were measured and monitored for 200 days. The copper pattern with rGO (Cu : rGO = 1,000 : 1 was found to maintain its initial resistivity (1.63 × 10−7 Ω·m for 150 days. Corrosion tests were conducted to confirm the oxidation prohibition of rGO. The resistance polarization (Rp of the copper pattern was measured to be 1.5 times higher than that of the copper pattern without rGO. Thus, rGO was shown to prevent oxidation and improve the conductivity of copper patterns.

  1. Insights into electrode/electrolyte interfacial processes and the effect of nanostructured cobalt oxides loading on graphene-based hybrids by scanning electrochemical microscopy

    Science.gov (United States)

    Gupta, Sanju; Carrizosa, Sara B.

    2016-12-01

    Nanostructured cobalt oxide polymorphs (CoO and Co3O4) deposited via electrodeposition allowed optimal loading on supercapacitive graphene nanosheets producing a set of graphene-based hybrids namely, CoO/GO, CoO/ErGO, Co3O4/GO, Co3O4/rGO, and Co3O4/ErGO, as pseudocapacitive electrochemical electrodes. We gained fundamental insights into the complex physicochemical interfacial processes at electrode surfaces and electrode/electrolyte (or solid/liquid) interfaces by scanning electrochemical microscopy operating in the feedback probe approach and imaging modes while monitoring and mapping the redox probe (re)activity behavior. We determined the various experimental descriptors including diffusion coefficient, electron transfer rate, and electroactive site distribution on electrodes. We emphasize the interplay of (1) heterogeneous basal and edge plane active sites, (2) graphene surface functional moieties (conducting/semiconducting), and (3) crystalline spinel cobalt oxides (semiconducting/insulating) coated graphene, reinforcing the available electron density of states in the vicinity of the Fermi level contributing to higher electroactivity, faster interfacial diffusion, and shorter distances for electron transfer, facilitated through molecular and chemical bridges obtained by electrodeposition as compared with the physical deposition.

  2. Effect of proton-conduction in electrolyte on electric efficiency of multi-stage solid oxide fuel cells

    Science.gov (United States)

    Matsuzaki, Yoshio; Tachikawa, Yuya; Somekawa, Takaaki; Hatae, Toru; Matsumoto, Hiroshige; Taniguchi, Shunsuke; Sasaki, Kazunari

    2015-01-01

    Solid oxide fuel cells (SOFCs) are promising electrochemical devices that enable the highest fuel-to-electricity conversion efficiencies under high operating temperatures. The concept of multi-stage electrochemical oxidation using SOFCs has been proposed and studied over the past several decades for further improving the electrical efficiency. However, the improvement is limited by fuel dilution downstream of the fuel flow. Therefore, evolved technologies are required to achieve considerably higher electrical efficiencies. Here we present an innovative concept for a critically-high fuel-to-electricity conversion efficiency of up to 85% based on the lower heating value (LHV), in which a high-temperature multi-stage electrochemical oxidation is combined with a proton-conducting solid electrolyte. Switching a solid electrolyte material from a conventional oxide-ion conducting material to a proton-conducting material under the high-temperature multi-stage electrochemical oxidation mechanism has proven to be highly advantageous for the electrical efficiency. The DC efficiency of 85% (LHV) corresponds to a net AC efficiency of approximately 76% (LHV), where the net AC efficiency refers to the transmission-end AC efficiency. This evolved concept will yield a considerably higher efficiency with a much smaller generation capacity than the state-of-the-art several tens-of-MW-class most advanced combined cycle (MACC). PMID:26218470

  3. Mn(II) removal from groundwater with manganese oxide-coated filter media.

    Science.gov (United States)

    Piispanen, Jutta K; Sallanko, Jarmo T

    2010-11-01

    Removing soluble manganese from groundwater requires a strong chemical oxidant, such as ozone or potassium permanganate, or raising the pH to alkaline value (over pH 9). Biological or adsorption processes can also be applied. Filter media naturally or industrially coated with manganese oxide are effective in adsorptive manganese removal. In this work, a layer of commercial manganese oxide coated medium was added to the top of an experimental sand/anthracite filter column to improve manganese removal. The coated layer was ca 28 cm thick (20% of the total filter depth) and the sand layer was 110 cm thick. The coated layer enhanced the manganese removal markedly. Manganese removal increased by over 91%, and manganese remained in the treated water. Also iron removal was enhanced. Filters with added coated layer recovered faster than reference filter from filter backwashes. Sodium hypochlorite feed, which was tested in regeneration of the filter medium, had a slight negative effect on the filter performance.

  4. Microstructure, mechanical properties and oxidation behaviors of magnetron sputtered NbN{sub x} coatings

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Zhengbing, E-mail: zbqi@xmut.edu.cn [College of Materials Science and Engineering, Xiamen University of Technology, Xiamen (China); Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen (China); Wu, Zhengtao; Zhang, Dongfang [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen (China); Zuo, Juan [College of Materials Science and Engineering, Xiamen University of Technology, Xiamen (China); Wang, Zhoucheng, E-mail: zcwang@xmu.edu.cn [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen (China)

    2016-08-05

    Mechanical properties and oxidation resistance are of importance for the NbN{sub x} coatings as used in cutting and forming tools. In this study, the NbN{sub x} coatings were deposited by magnetron sputtering at nitrogen partial pressure ranging from 0 to 40%. The chemical and phase compositions, morphologies, mechanical properties and oxidation behaviors of the NbN{sub x} coatings were investigated by electron probe microanalysis, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, scanning and transmission electron microscopy, and nanoindentation measurements. The results reveal the composition evolution of the NbN{sub x} coatings as α-Nb (0%), β-Nb{sub 2}N (5%), a mixture of β-Nb{sub 2}N and δ-NbN (10%), and δ-NbN (20–40%). The single phase coatings exhibit columnar structure while the mixed phases coating shows nano-composite structure. Compared with the single phase δ-NbN coatings (21.6 ± 0.8–28.0 ± 1.2 GPa), higher hardness of the single phase β-Nb{sub 2}N coating (30.9 ± 1.0 GPa) is due to the higher covalent character and much finer grains. The maximum hardness reaches 33.3 ± 1.5 GPa for the nano-composite coating with mixed phases of β-Nb{sub 2}N and δ-NbN. The oxidation results demonstrate that the activation energies are 219.3 and 192.3 kJ/mol for the Nb{sub 2}N and NbN coatings respectively. Non-protective Nb{sub 2}O{sub 5} scales with cracks and pores result in poorer oxidation resistance of the NbN coating in comparison to the Nb{sub 2}N coating. - Highlights: • Chemical and phase compositions and microstructure of NbN{sub x} coatings were investigated. • Maximum hardness is obtained for nano-composite coating with mixed Nb{sub 2}N and NbN phases. • Activation energies are 219.3 and 192.3 kJ/mol for oxidation of Nb{sub 2}N and NbN coatings. • Non-protective Nb{sub 2}O{sub 5} scales with cracks and pores lower oxidation resistance of NbN coating.

  5. Development of Oxidation Resistant Coatings on GRCop-84 Substrates by Cold Spray Process

    Science.gov (United States)

    Karthikeyan, J.

    2007-01-01

    GRCop-84, a Cu-CR-Nb alloy, has been developed for rocket engine liner applications. For maximum life additional oxidation protection is required to prevent blanching. NiCrAlY was identified as a suitable coating, and efforts were initiated to develop suitable coating techniques. Cold spray is one technique under consideration. Efforts at ASB Industries to produce dense, adherent coatings are detailed. The work culminated in the production of samples for testing at NASA Glenn Research Center.

  6. Synthesis and characterization of polyvinylpyrrolidone coated cerium oxide nanoparticles.

    Science.gov (United States)

    Merrifield, Ruth C; Wang, Zhi Wei; Palmer, Richard E; Lead, Jamie R

    2013-01-01

    There is a pressing need for the development of standard and reference nanomaterials for environmental nanoscience and nanotoxicology. To that aim, suspensions of polyvinylpyrrolidone (PVP)-coated ceria nanoparticles (NPs) were produced. Four differently sized monodispersed samples were produced by using different PVP chain lengths. The chemical and physical properties of these NPs were characterized as prepared and in different ecotoxicology exposure media. Dynamic light scattering analysis showed that the samples were monodispersed, with an unchanged size when suspended in the different media over a 72 h period. Electron microscopy confirmed this and revealed that the larger (ca. 20 nm) particles were aggregates composed of the smaller individual particles (4-5 nm). Electron energy loss spectroscopy (EELS) showed that the smallest and largest samples were composed almost entirely of cerium(III) oxide, with only small amounts of cerium(IV) present in the largest sample. Dissolved cerium concentrations in media were low and constant, showing that the NPs did not dissolve over time. The simple synthesis of the these NPs and their physical and chemical stability in different environmental conditions make them potentially suitable for use as reference materials for (eco)toxicology and surface water environmental studies.

  7. Nanocarbon coating on the basis of partially reduced graphene oxide

    Science.gov (United States)

    Bocharov, G. S.; Budaev, V. P.; Eletskii, A. V.; Fedorovich, S. D.

    2017-11-01

    There has been developed an approach to the production of graphene as a result of the thermal reduction of graphene oxide (GO). GO has been synthesized by the use of the modified Hummers method with utilization of sodium nitrate and concentrated sulfuric acid. A paper-like material of 40 – 60 μm in thickness and 1.2 g/cm3 in density was formed on a filter after deposition from dispersion. The material was cut onto samples of about 15×25 mm2 in size which were experienced to the thermal treatment at various temperatures between 100 and 800 °C. This resulted in a set of GO samples reduced to various degrees. The degree of reduction was determined on the basis of measurements of the conductivity. Along with that the evolution of samples density was studied as the annealing temperature was enhanced. The analysis of the X-ray photoelectron spectra of partially reduced GO permitted the determination of the dynamics of changing the chemical composition of the material in the process of the thermal treatment. The analysis of Raman spectra of the GO samples indicates rather high degree of the disordering of the material. A possibility of the usage of the material produced as a nanocarbon coating in experiments on the interaction of high intense liquid flows with a wall surface is discussed.

  8. Steam oxidation and the evaluation of coatings and material performance through collaborative research

    Energy Technology Data Exchange (ETDEWEB)

    Fry, A.T. [National Physical Lab., Teddington (United Kingdom); Aguero, A. [INTA, Madrid (Spain)

    2010-07-01

    Over the last five years through the COST 536 Programme researchers across Europe have been collaborating to better understand the phenomena of steam oxidation and to characterise coated and uncoated materials for use in power plants. During this period fundamental study of the oxidation mechanisms and changes in the oxidation kinetics caused by the presence of steam have been undertaken. Materials covering a range of high temperature plant applications have been studied, from low alloy martensitic alloys through to Ni-based superalloy materials, with investigations into the effect of increasing temperatures and pressures on the oxidation kinetics, oxide morphology and spallation characteristics. In addition conventional and novel coatings have been evaluated to assess their potential use in new USC plant. This paper will present an overview of these activities demonstrating the effect that steam has on the oxidation of alloys and coatings. (orig.)

  9. Comparison of iron and copper doped manganese cobalt spinel oxides as protective coatings for solid oxide fuel cell interconnects

    Science.gov (United States)

    Talic, Belma; Molin, Sebastian; Wiik, Kjell; Hendriksen, Peter Vang; Lein, Hilde Lea

    2017-12-01

    MnCo2O4, MnCo1.7Cu0.3O4 and MnCo1.7Fe0.3O4 are investigated as coatings for corrosion protection of metallic interconnects in solid oxide fuel cell stacks. Electrophoretic deposition is used to deposit the coatings on Crofer 22 APU alloy. All three coating materials reduce the parabolic oxidation rate in air at 900 °C and 800 °C. At 700 °C there is no significant difference in oxidation rate between coated samples and uncoated pre-oxidized Crofer 22 APU. The cross-scale area specific resistance (ASR) is measured in air at 800 °C using La0.85Sr0.1Mn1.1O3 (LSM) contact plates to simulate the interaction with the cathode in a SOFC stack. All coated samples have three times lower ASR than uncoated Crofer 22 APU after 4370 h aging. The ASR increase with time is lowest with the MnCo2O4 coating, followed by the MnCo1.7Fe0.3O4 and MnCo1.7Cu0.3O4 coatings. LSM plates contacted to uncoated Crofer 22 APU contain significant amounts of Cr after aging, while all three coatings effectively prevent Cr diffusion into the LSM. A complex Cr-rich reaction layer develops at the coating-alloy interface during oxidation. Cu and Fe doping reduce the extent of this reaction layer at 900 °C, while at 800 °C the effect of doping is insignificant.

  10. Anticoagulation and endothelial cell behaviors of heparin-loaded graphene oxide coating on titanium surface

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Chang-Jiang, E-mail: panchangjiang@hyit.edu.cn [Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huai' an 223003 (China); Pang, Li-Qun [Department of General Surgery, Huai' an First People' s Hospital, Nanjing Medical University, Huai' an 223300 (China); Gao, Fei [Zhejiang Zylox Medical Devices Co., Ltd., Hangzhou 310000 (China); Wang, Ya-Nan; Liu, Tao; Ye, Wei; Hou, Yan-Hua [Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huai' an 223003 (China)

    2016-06-01

    Owing to its unique physical and chemical properties, graphene oxide (GO) has attracted tremendous interest in many fields including biomaterials and biomedicine. The purpose of the present study is to investigate the endothelial cell behaviors and anticoagulation of heparin-loaded GO coating on the titanium surface. To this end, the titanium surface was firstly covered by the polydopamine coating followed by the deposition of the GO coating. Heparin was finally loaded on the GO coating to improve the blood compatibility. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) indicated that the heparin-loaded GO coating was successfully created on the titanium surface. The scanning electron microscopy (SEM) images indicated that a relative uniform GO coating consisting of multilayer GO sheets was formed on the substrate. The hydrophilicity of the titanium surface was enhanced after the deposition of GO and further improved significantly by the loading heparin. The GO coating can enhance the endothelial cell adhesion and proliferation as compared with polydopamine coating and the blank titanium. Loading heparin on the GO coating can significantly reduce the platelet adhesion and prolong the activated partial thromboplastin time (APTT) while not influence the endothelial cell adhesion and proliferation. Therefore, the heparin-loaded GO coating can simultaneously enhance the cytocompatibility to endothelial cells and blood compatibility of biomaterials. Because the polydopamine coating can be easily prepared on most of biomaterials including polymer, ceramics and metal, thus the approach of the present study may open up a new window of promising an effective and efficient way to promote endothelialization and improve the blood compatibility of blood-contact biomedical devices such as intravascular stents. - Highlights: • Heparin-loaded graphene oxide coating was

  11. Mechanical degradation of coating systems in high-temperature cyclic oxidation

    CSIR Research Space (South Africa)

    Pennefather, RC

    1995-01-01

    Full Text Available temperature, an extensive testing programme was undertaken. During testing an observation was made that in addition to the usual oxidation of the coating, another degradation mechanism was pragmatic; a mechanical effect caused by the instability of the coating...

  12. Turbostratic boron nitride coated on high-surface area metal oxide templates

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; Egeblad, Kresten; Brorson, M.

    2007-01-01

    Boron nitride coatings on high-surface area MgAl2O4 and Al2O3 have been synthesized and characterized by transmission electron microscopy and by X-ray powder diffraction. The metal oxide templates were coated with boron nitride using a simple nitridation in a flow of ammonia starting from ammonium...

  13. Interdiffusion between Co3O4 coating and the oxide scale of Fe-22Cr alloy

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Friehling, Peter B.; Linderoth, Søren

    2002-01-01

    on Fe-Cr alloys. Coatings of Co3O4 were deposited on a Fe-22Cr alloy by plasma spraying and spray-painting. As-deposited samples were oxidised in air containing 1% H2O at 900C for various exposure time. During exposure the Fe-22Cr alloy forms an oxide scale, which reacts with the coating. The effects...

  14. Impact of structure and morphology of nanostructured ceria coating on AISI 304 oxidation kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Aadhavan, R.; Suresh Babu, K., E-mail: sureshbabu.nst@pondiuni.edu.in

    2017-07-31

    Highlights: • Ceria coating reduced the oxidation kinetics of AISI304 by 3–4 orders. • Lower deposition rate (0.1 Å/s) resulted in dense and uniform coating. • Substrate temperature of 100 °C provided coating with smaller crystallite size. • Surface morphology of the coating has strong influence in oxidation protection. - Abstract: Nanostructured ceria-based coatings are shown to be protective against high-temperature oxidation of AISI 304 due to the dynamics of oxidation state and associated defects. However, the processing parameters of deposition have a strong influence in determining the structural and morphological aspects of ceria. The present work focuses on the effect of variation in substrate temperature (50–300 °C) and deposition rate (0.1–50 Å/s) of ceria in electron beam physical vapour evaporation method and correlates the changes in structure and morphology to high-temperature oxidation protection. Unlike deposition rate, substrate temperature exhibited a profound influence on crystallite size (7–18 nm) and oxygen vacancy concentration. Upon isothermal oxidation at 1243 K for 24 h, bare AISI 304 exhibited a linear mass gain with a rate constant of 3.0 ± 0.03 × 10{sup −3} kg{sup 2} m{sup −4} s{sup −1} while ceria coating lowered the kinetics by 3–4 orders. Though the thickness of the coating was kept constant at 2 μm, higher deposition rate offered one order lower protection due to the porous nature of the coating. Variation in the substrate temperature modulated the porosity as well as oxygen vacancy concentration and displayed the best protection for coatings deposited at moderate substrate temperature. The present work demonstrates the significance of selecting appropriate processing parameters to obtain the required morphology for efficient high-temperature oxidation protection.

  15. Cerium oxide as conversion coating for the corrosion protection of aluminum

    Directory of Open Access Journals (Sweden)

    JELENA GULICOVSKI

    2013-11-01

    Full Text Available CeO2 coatings were formed on the aluminum after Al surface preparation, by dripping the ceria sol, previously prepared by forced hydrolysis of Ce(NO34. The anticorrosive properties of ceria coatings were investigated by the electrochemical impedance spectroscopy (EIS during the exposure to 0.03 % NaCl. The morphology of the coatings was examined by the scanning electron microscopy (SEM. EIS data indicated considerably larger corrosion resistance of CeO2-coated aluminum than for bare Al. The corrosion processes on Al below CeO2 coating are subjected to more pronounced diffusion limitations in comparison to the processes below passive aluminum oxide film, as the consequence of the formation of highly compact protective coating. The results show that the deposition of ceria coatings is an effective way to improve corrosion resistance for aluminum.

  16. Synthesis of pseudopolyrotaxanes-coated Superparamagnetic Iron Oxide Nanoparticles as new MRI contrast agent

    NARCIS (Netherlands)

    Hosseini, F.; Panahifar, A.; Adeli, M.; Amiri, H.; Lascialfari, A.; Orsini, F.; Doschak, M.R.; Mahmoudi, M.

    2013-01-01

    Superparamagnetic Iron Oxide Nanoparticles (SPIONs) were synthesized and coated with pseudopolyrotaxanes (PPRs) and proposed as a novel hybrid nanostructure for medical imaging and drug delivery. PPRs were prepared by addition of alpha-cyclodextrin rings to functionalized polyethylene glycol (PEG)

  17. Tunable transport property of oxygen ion in metal oxide thin film: Impact of electrolyte orientation on conductivity.

    Science.gov (United States)

    Arunkumar, P; Ramaseshan, R; Dash, S; Babu, K Suresh

    2017-06-14

    Quest for efficient ion conducting electrolyte thin film operating at intermediate temperature (~600 °C) holds promise for the real-world utilization of solid oxide fuel cells. Here, we report the correlation between mixed as well as preferentially oriented samarium doped cerium oxide electrolyte films fabricated by varying the substrate temperatures (100, 300 and 500 °C) over anode/ quartz by electron beam physical vapor deposition. Pole figure analysis of films deposited at 300 °C demonstrated a preferential (111) orientation in out-off plane direction, while a mixed orientation was observed at 100 and 500 °C. As per extended structural zone model, the growth mechanism of film differs with surface mobility of adatom. Preferential orientation resulted in higher ionic conductivity than the films with mixed orientation, demonstrating the role of growth on electrochemical properties. The superior ionic conductivity upon preferential orientation arises from the effective reduction of anisotropic nature and grain boundary density in highly oriented thin films in out-of-plane direction, which facilitates the hopping of oxygen ion at a lower activation energy. This unique feature of growing an oriented electrolyte over the anode material opens a new approach to solving the grain boundary limitation and makes it as a promising solution for efficient power generation.

  18. Improved transport property of proton-conducting solid oxide fuel cell with multi-layered electrolyte structure

    Science.gov (United States)

    Shimada, Hiroyuki; Yamaguchi, Toshiaki; Sumi, Hirofumi; Nomura, Katsuhiro; Yamaguchi, Yuki; Fujishiro, Yoshinobu

    2017-10-01

    A multi-layered electrolyte structure is proposed for proton-conducting solid oxide fuel cells (SOFCs) to achieve higher power density and higher open-circuit voltage (OCV). Although recent proton-conducting SOFCs have demonstrated high power density, their OCVs have been lower than that of conventional SOFCs with stabilized zirconia because proton-conducting oxides intrinsically have electron-hole conduction. The proposed electrolyte structure has a porous BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) layer deposited on a dense BZCYYb layer. This structure effectively improves both cathode polarization and ionic transport property, resulting in higher power density with higher OCV. Also, discussion based on an equivalent circuit model of proton-conducting SOFCs clearly reveals a mechanism that determines OCV, namely, higher ohmic resistance and lower electrode polarization resistance lead to higher OCV. Our results suggest that higher electrode performance is essential for proton-conducting SOFCs to achieve higher OCV, particularly in the case of anode-supported configurations with thin electrolyte.

  19. Structured multilayered electrodes of proton/electron conducting polymer for polymer electrolyte membrane fuel cells assembled by spray coating

    Energy Technology Data Exchange (ETDEWEB)

    Wolz, Andre; Zils, Susanne; Roth, Christina [Institute for Materials Science, TU Darmstadt, Petersenstr. 23, D-64287 Darmstadt (Germany); Michel, Marc [Department of Advanced Materials and Structures, CRP Henri Tudor, 66 Rue de Luxembourg, L-4002 Esch-sur-Alzette (Luxembourg)

    2010-12-15

    Membrane electrode assemblies (MEAs) for fuel cell applications consist of electron conductive support materials, proton conductive ionomer, and precious metal nanoparticles to enhance the catalytic activity towards H{sub 2} oxidation and O{sub 2} reduction. An optimized connection of all three phases is required to obtain a high noble metal utilization, and accordingly a good performance. Using polyaniline (PANI) as an alternative support material, the generally used ionomer Nafion {sup registered} could be replaced in the catalyst layer. PANI has the advantage to be electron and proton conductive at the same time, and can be used as a catalyst support as well. In this study, a new technique building up alternating layers of PANI supported catalyst and single-walled carbon nanotubes (SWCNT) supported catalyst is introduced. Multilayers of PANI and SWCNT catalysts are used on the cathode side, whereas the anode side is composed of commercial platinum/carbon black catalyst and Nafion {sup registered}, applied by an airbrush. No additional Nafion {sup registered} ionomer is used for proton conductivity of the cathode. The so called spray coating method results in high power densities up to 160 mW cm{sup -2} with a Pt loading of 0.06 mg cm{sup -2} at the cathode, yielding a Pt utilization of 2663 mW mg{sub Pt}{sup -1}. As well as PANI, supports of SWCNTs have the advantage to have a fibrous structure and additional, they provide high electron conductivity. The combination of the new technique and the fibrous 1-dimensional support materials leads to a porous 3-dimensional electrode network which could enhance the gas transport through the electrode as well as the Pt utilization. The spray coating method could be upgraded to an in-line process and is not restricted to batch production. (author)

  20. Lithium batteries using poly(ethylene oxide)-based non-aqueous electrolytes

    Science.gov (United States)

    Chen, Zonghai; Amine, Khalil

    2015-09-08

    Lithium-air cells employing poly(ethyleneoxide) phosphate-based electrolytes may be prepared and exhibit improved charge carrying capacity. Such PEO phosphates generally have the formulas IIa, IIb, IIc, where: ##STR00001##

  1. Hypertension potentiates cataractogenesis in rat eye through modulation of oxidative stress and electrolyte homeostasis

    Directory of Open Access Journals (Sweden)

    Samsroz Ahmad Khan

    2016-09-01

    Conclusion: Based on our findings, it can be concluded that systemic hypertension significantly increases the risk of cataract formation in the rat eyes via modulation of the antioxidant defense mechanism and electrolyte homeostasis.

  2. Design, analysis, and fabrication of oxide-coated iridium/rhenium combustion chambers

    Science.gov (United States)

    Jang, Q.; Tuffias, R. H.; Laferla, R.; Ghoniem, N. M.

    1993-01-01

    Iridium-coated rhenium (Ir/Re) combustion chambers provide high temperature, oxidation-resistant operation for radiation-cooled liquid-fueled rocket engines. A 22-N (5-lb(sub f)) chamber has been operated for 15 hours at 2200 C (4000 F) using nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) propellant, with negligible internal erosion. The oxidation resistance of these chambers could be further increased by the addition of refractory oxide coatings, providing longer life and/or operation in more oxidizing and higher temperature environments. The oxide coatings would serve as a thermal and diffusion barrier for the iridium coating, lowering the temperature of the iridium layer while also preventing the ingress of oxygen and egress of iridium oxides. This would serve to slow the failure mechanisms of Ir/Re chambers, namely the diffusion of rhenium to the inner surface and the oxidation of iridium. Such protection could extend chamber lifetimes by tens or perhaps hundreds of hours, and allow chamber operation on stoichiometric or higher mixture ratio oxygen/hydrogen (O2/H2) propellant. Extensive thermomechanical, thermochemical, and mass transport modeling was performed as a key material/structure design tool. Based on the results of these analyses, several 22-N oxide-coated Ir/Re chambers were fabricated and delivered to NASA Lewis Research Center for hot-fire testing.

  3. Effective Infiltration of Gel Polymer Electrolyte into Silicon-Coated Vertically Aligned Carbon Nanofibers as Anodes for Solid-State Lithium-Ion Batteries.

    Science.gov (United States)

    Pandey, Gaind P; Klankowski, Steven A; Li, Yonghui; Sun, Xiuzhi Susan; Wu, Judy; Rojeski, Ronald A; Li, Jun

    2015-09-23

    This study demonstrates the full infiltration of gel polymer electrolyte into silicon-coated vertically aligned carbon nanofibers (Si-VACNFs), a high-capacity 3D nanostructured anode, and the electrochemical characterization of its properties as an effective electrolyte/separator for future all-solid-state lithium-ion batteries. Two fabrication methods have been employed to form a stable interface between the gel polymer electrolyte and the Si-VACNF anode. In the first method, the drop-casted gel polymer electrolyte is able to fully infiltrate into the open space between the vertically aligned core-shell nanofibers and encapsulate/stabilize each individual nanofiber in the polymer matrix. The 3D nanostructured Si-VACNF anode shows a very high capacity of 3450 mAh g(-1) at C/10.5 (or 0.36 A g(-1)) rate and 1732 mAh g(-1) at 1C (or 3.8 A g(-1)) rate. In the second method, a preformed gel electrolyte film is sandwiched between an Si-VACNF electrode and a Li foil to form a half-cell. Most of the vertical core-shell nanofibers of the Si-VACNF anode are able to penetrate into the gel polymer film while retaining their structural integrity. The slightly lower capacity of 2800 mAh g(-1) at C/11 rate and ∼1070 mAh g(-1) at C/1.5 (or 2.6 A g(-1)) rate have been obtained, with almost no capacity fade for up to 100 cycles. Electrochemical impedance spectroscopy does not show noticeable changes after 110 cycles, further revealing the stable interface between the gel polymer electrolyte and the Si-VACNFs anode. These results show that the infiltrated flexible gel polymer electrolyte can effectively accommodate the stress/strain of the Si shell due to the large volume expansion/contraction during the charge-discharge processes, which is particularly useful for developing future flexible solid-state lithium-ion batteries incorporating Si-anodes.

  4. Electrokinetic characterization of poly(acrylic acid) and poly(ethylene oxide) brushes in aqueous electrolyte solutions

    NARCIS (Netherlands)

    Zimmermann, R.; Norde, W.; Cohen Stuart, M.A.; Werner, C.

    2005-01-01

    Surfaces carrying hydrophilic polymer brushes were prepared from poly(styrene)-poly(acrylic acid) and poly(styrene)-poly(ethylene oxide) diblock copolymers, respectively, using a Langmuir-Blodgett technique and employing poly(styrene)-coated planar glass as substrates. The electrical properties of

  5. Spinel-based coatings for metal supported solid oxide fuel cells

    DEFF Research Database (Denmark)

    Stefan, Elena; Neagu, Dragos; Blennow Tullmar, Peter

    2017-01-01

    Metal supports and metal supported half cells developed at DTU are used for the study of a solution infiltration approach to form protective coatings on porous metal scaffolds. The metal particles in the anode layer, and sometimes even in the support may undergo oxidation in realistic operating...... conditions leading to severe cell degradation. Here, a controlled oxidation of the porous metal substrate and infiltration of Mn and/or Ce nitrate solutions are applied for in situ formation of protective coatings. Our approach consists of scavenging the FeCr oxides formed during the controlled oxidation...

  6. Application of Liquid-Phase Direct Fluorination: Novel Synthetic Methods for a Polyfluorinated Coating Material and a Monomer of a Perfluorinated Polymer Electrolyte Membrane

    Directory of Open Access Journals (Sweden)

    Takashi Okazoe

    2012-04-01

    Full Text Available A new polyfluorinated anti-staining coating material CF3O(CF2CF2OxCF2-CONHCH2CH2CH2Si(OCH33 has been developed by utilizing the PERFECT method, which employs a liquid-phase direct fluorination reaction with elemental fluorine as a key step. Direct fluorination of a partially-fluorinated ester, which was prepared from a non-fluorinated poly(ethylene glycol and a perfluorinated acyl fluoride, followed by methanolysis, gave the perfluorinated corresponding compound, which was led to the coating material for surface treating agents, and the methyl ester of the starting perfluorinated acyl fluoride. Application to the synthesis of a new perfluorinated bifunctional sulfonate monomer CF2=CFOCF2CF2CF2OCF(CF2SO2F2 for polymer electrolyte membranes (PEMs of fuel cells was also developed.

  7. Fermi Potential across Working Solid Oxide Cells with Zirconia or Ceria Electrolytes

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2014-01-01

    Two kinds of electrochemical relevant potentials are important in order to describe several observed phenomena in operating electrochemical cells with solid electrolytes. This paper gives illustrative examples of how the profiles of the two potential types, the Galvani potential, φ, and the elect...... stabilized zirconia (YSZ) electrolytes. The nature of the two potential types and the importance of each of them for the cell operation are explained....

  8. Improvement in energy release properties of boron-based propellant by oxidant coating

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Daolun; Liu, Jianzhong, E-mail: jzliu@zju.edu.cn; Chen, Binghong; Zhou, Junhu; Cen, Kefa

    2016-08-20

    Highlights: • NH{sub 4}ClO{sub 4}, KNO{sub 3}, KClO{sub 4} and HMX coated B were used to prepare propellant samples. • FTIR, XRD and SEM were used for the microstructure analysis of the prepared B. • Thermal oxidation and combustion characteristics of the propellants were studied. • HMX coating was the most beneficial to the energy release of the samples. - Abstract: The energy release properties of a propellant can be improved by coating boron (B) particles with oxidants. In the study, B was coated with four different oxidants, namely, NH{sub 4}ClO{sub 4}, KNO{sub 3}, LiClO{sub 4}, and cyclotetramethylenetetranitramine (HMX), and the corresponding propellant samples were prepared. First, the structural and morphological analyses of the pretreated B were carried out. Then, the thermal analysis and laser ignition experiments of the propellant samples were carried out. Coating with NH{sub 4}ClO{sub 4} showed a better performance than mechanical mixing with the same component. Coating with KNO{sub 3} efficiently improved the ignition characteristics of the samples. Coating with LiClO{sub 4} was the most beneficial in reducing the degree of difficulty of B oxidation. Coating with HMX was the most beneficial in the heat release of the samples. The KNO{sub 3}-coated sample had a very high combustion intensity in the beginning, but then it rapidly became weak. Large amounts of sparks were ejected during the combustion of the LiClO{sub 4}-coated sample. The HMX-coated sample had the longest self-sustaining combustion time (4332 ms) and the highest average combustion temperature (1163.92 °C).

  9. Formation of nitrous oxide (N2O) hydrate in soil mineral suspensions with electrolytes

    Science.gov (United States)

    Kyung, D.; Enkh-Amgalan, T.; Lee, W.

    2013-05-01

    We have identified the effects of solid surface (illite, nontronite, sphalerite, kaolinite) and electrolyte (NaCl, KCl, CaCl2, MgCl2) types on the formation of N2O hydrate in this study. The hydrate formation experiments were conducted at hydrate forming condition (273.3K and 30 bar) by injecting N2O gas into the soil mineral suspensions with and without electrolytes in a 50mL pressurized vessel. The formation of N2O hydrate in aqueous electrolyte solutions was slower than that in deionized water. Ion charge and size were significant factors affecting N2O hydrate formation kinetic in electrolytes solutions. The addition of soil mineral suspensions accelerated the formation of N2O hydrate in the electrolyte solutions. Surface area and ionic strength of soil minerals highly influenced on formation kinetic of N2O hydrate. The hydrate formation times in the solid suspensions without electrolytes were very similar to that in the deionized water. The results obtained from this research could be indirectly applied to the fate of N2O sequestered into geological formations as well as its storage as a form of N2O hydrate.

  10. Formation and properties of composite nanostructured PEO-coatings on metals and alloys

    Directory of Open Access Journals (Sweden)

    Mashtalyar Dmitry V.

    2017-01-01

    Full Text Available Results of investigation of the incorporation of zirconia and titanium nitride nanoparticles into the coatings formed on magnesium alloy by plasma electrolytic oxidation are presented. Comprehensive research of electrochemical and mechanical properties of obtained coatings was carried out. It was established that the polarization resistance of the samples with a coating containing zirconia nanoparticles is in two fold higher than for the sample with base PEO-coating. One of the important reasons for improving the protective properties of coatings formed in electrolytes containing nanoparticles consists in enhanced morphological characteristics, in particular, the porosity decrease and increase of thickness and resistivity of porousless sublayer in comparison with base PEO-layer. Incorporation of zirconia and titanium nitride particles into the coating increases the mechanical performances. The coating containing nanoparticles have greater hardness and are more wear resistant in comparison with the coatings formed in the electrolyte without nanoparticle.

  11. Mechanical properties of PEO-coatings on the surface of magnesium alloy MA8 modified by TiN nanoparticles

    Science.gov (United States)

    Imshinetsky, Igor M.; Mashtalyar, Dmitriy V.; Sunebryukhov, Sergey L.; Gnedenkov, Sergey V.

    2017-09-01

    The methods to form protective coatings by the plasma electrolytic oxidation method (PEO) in the electrolytic system containing nanosized particles of titanium nitride has been develoted. Tribological and morfological studies of the composite coatings have been carried out. It has been established that the microhardness of the coating with nanoparticles concentration of 3 g/l increases by 2 folds, while the wear resistance - by 2.2 fold, as compared to respective values for the PEO-coating formed in the electrolyte without nanoparticles.

  12. Comparison of in situ and ex situ reduced graphene oxide reinforced electroless nickel phosphorus nanocomposite coating

    Energy Technology Data Exchange (ETDEWEB)

    Sadhir, M. Hasan; Saranya, M.; Aravind, M. [Department of Mechanical Engineering, College of Engineering Guindy, Anna University, Chennai 600025 (India); Srinivasan, A. [Departments of Chemistry, College of Engineering Guindy, Anna University, Chennai 600025 (India); Siddharthan, A., E-mail: sidharth@annauniv.edu [Department of Mechanical Engineering, College of Engineering Guindy, Anna University, Chennai 600025 (India); Department of Mechanical Engineering, CEG Campus, Anna University, Chennai 600025 (India); Rajendran, N. [Departments of Chemistry, College of Engineering Guindy, Anna University, Chennai 600025 (India)

    2014-11-30

    Highlights: • First kind of electroless nickel phosphorous (EN) reduced graphene oxide (rGO) coatings. • Change in preferential orientation of grain growth of heat treated in situ EN-rGO coating. • Better corrosion resistance of in situ EN-rGO coating. • 2 stages of reduction of Graphene (GE) to GO, during - coating and heat treatment. • Soft nature of GO for similar to polymer from low hardness of EN-GO coating. - Abstract: Electroless nickel-phosphorus (EN)–reduced graphene oxide (rGO) composite coating was carried out to compare the ex situ route of reinforcement of reduced GO in EN coating (EN-rGO) and in situ route of reinforced of rGO in EN coating (EN-GO). The coatings were characterized using X-ray diffraction (XRD) and attenuated total reflectance infrared spectroscopy (ATR-IR) for phase determination and to show the presence of reinforcement of rGO in the coatings respectively. ATR-IR spectra indicated that GO was chemically reduced in situ while deposition of EN-GO composite and thermal reduction during its heat treatment. XRD pattern of heat treated EN-GO coating show the change in preferred orientation of nickel deposit. Upon heat treatment, the hardness of EN and EN-GO and EN-rGO deposits increased while the corrosion resistance decreased except for EN-GO coating. The hardness of EN-rGO and EN-GO coating is approximately half the value of EN deposit. The electrochemical polarization studies indicated that EN-GO deposit was corrosive resistant than EN-rGO and EN deposit.

  13. Electrochemical combustion of indigo at ternary oxide coated titanium anodes

    Directory of Open Access Journals (Sweden)

    María I. León

    2014-12-01

    Full Text Available The film of iridium and tin dioxides doped with antimony (IrO2-SnO2–Sb2O5 deposited on a Ti substrate (mesh obtained by Pechini method was used for the formation of ·OH radicals by water discharge. Detection of ·OH radicals was followed by the use of the N,N-dimethyl-p-nitrosoaniline (RNO as a spin trap. The electrode surface morphology and composition was characterized by SEM-EDS. The ternary oxide coating was used for the electrochemical combustion of indigo textile dye as a model organic compound in chloride medium. Bulk electrolyses were then carried out at different volumetric flow rates under galvanostatic conditions using a filter-press flow cell. The galvanostatic tests using RNO confirmed that Ti/IrO2-SnO2-Sb2O5 favor the hydroxyl radical formation at current densities between 5 and 7 mA cm-2, while at current density of 10 mA cm-2 the oxygen evolution reaction occurs. The indigo was totally decolorized and mineralized via reactive oxygen species, such as (·OH, H2O2, O3 and active chlorine formed in-situ at the Ti/IrO2-SnO2-Sb2O5 surface at volumetric flow rates between 0.1-0.4 L min-1 and at fixed current density of 7 mA cm-2. The mineralization of indigo carried out at 0.2 L min-1 achieved values of 100 %, with current efficiencies of 80 % and energy consumption of 1.78 KWh m-3.

  14. SELECTION OF OXIDES FOR STABILIZATION OF ZIRCONIUM DIOXIDE WHILE OBTAINING THERMAL BARRIER COATINGS

    Directory of Open Access Journals (Sweden)

    V. V. Okovity

    2015-01-01

    Full Text Available The paper analyzes selection of oxides and describes in details a majority of oxide systems which are applicable for stabilization of zirconium dioxide while obtaining thermal barrier coatings with maximum amount of tetragonal phase. Methodology of investigation is based on a review of analytical information on the current state of thermal barrier coatings on the basis of zirconium dioxide stabilized by oxides of rare-earth metals. The method used for application of  zirconium dioxide thermal barrier coatings is plasma spraying. Positive results have been also obtained while applying e-beam sputtering, ion-plasma deposition and magnetron sputtering. Nevertheless preferred plasma spraying application for thermal barrier coatings still continues due to its high productivity and versatility that permits to deposit metallic and ceramic materials of the ordered chemical and phase composition.Ytterbium and cerium oxides have been selected as oxides for stabilization of zirconium dioxide in order to obtain thermal barrier coatings. The paper also considers аn oxide system of zirconium dioxide: “hafnium oxide – yttrium oxide”, representing in itself the structure which is similar to zirconium dioxide.

  15. 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.

  16. Cyclic Oxidation Behavior of CuCrAl Cold-Sprayed Coatings for Reusable Launch Vehicles

    Science.gov (United States)

    Raj, Sai; Karthikeyan, J.

    2009-01-01

    The next generation of reusable launch vehicles is likely to use GRCop-84 [Cu-8(at.%)Cr-4%Nb] copper alloy combustion liners. The application of protective coatings on GRCop-84 liners can minimize or eliminate many of the environmental problems experienced by uncoated liners and significantly extend their operational lives and lower operational cost. A newly developed Cu- 23 (wt.%) Cr-5% Al (CuCrAl) coating, shown to resist hydrogen attack and oxidation in an as-cast form, is currently being considered as a protective coating for GRCop-84. The coating was deposited on GRCop-84 substrates by the cold spray deposition technique, where the CuCrAl was procured as gas-atomized powders. Cyclic oxidation tests were conducted between 773 and 1,073 K to characterize the coated substrates.

  17. 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.

  18. Bilayer polymer/oxide coating for electroluminescent organic semiconductors

    DEFF Research Database (Denmark)

    Tavares, Luciana

    of the fibers with oxygen. We have developed a bilayer coating that does not change significantly the p6P spectrum but strongly reduces bleaching. This bilayer coating consists of a first layer of a stable polymer (PMMA) on top of the organic nanofibers as a protecting layer for avoiding modifications of the p6......P luminescence spectrum and as a second layer SiOx for blocking the oxyg en penetration. In this work, we show the applicability of this bilayer coating of PMMA/SiOx in prolonging the operational lifetime of field-effect transistor (FET) devices based on p6P nanofibers. The coating prevents strong...... degradation of transferred nanofibers on FET platforms during electrical biasing as is observed for uncoated devices. We are currently investigating the effect of the coating during electrically stimulated light emission experiments from transferred fibers on transistor platforms....

  19. Reduced bleaching in organic nanofibers by bilayer polymer/oxide coating

    DEFF Research Database (Denmark)

    Tavares, Luciana; Kjelstrup-Hansen, Jakob; Rubahn, Horst-Günter

    2010-01-01

    the technological use of the nanofibers problematic. In order to investigate the photoinduced reaction in nanofibers, optical bleaching experiments have been performed by irradiating both pristine and coated nanofibers with UV light. Oxide coating materials (SiOx [2] and Al2O3) were applied onto p6P nanofibers....... These treatments caused a reduction of the bleaching reaction but in addition, the nanofiber luminescence spectrum was significantly altered. It was observed that some polymer coatings (P(TFE-PDD), and PMMA) do not interfere with the luminescence spectrum from the p6P but are not effective in stopping...... the bleaching. Bilayer coatings with first a polymer material, which should work as a protection layer to avoid modifications of the p6P luminescence spectrum, and second an oxide layer used as oxygen blocker were tested and it was found that a particular bilayer polymer/oxide combination results...

  20. Oxidation Behavior of Titanium Carbonitride Coating Deposited by Atmospheric Plasma Spray Synthesis

    Science.gov (United States)

    Zhu, Lin; He, Jining; Yan, Dianran; Liao, Hanlin; Zhang, Nannan

    2017-10-01

    As a high-hardness and anti-frictional material, titanium carbonitride (TiCN) thick coatings or thin films are increasingly being used in many industrial fields. In the present study, TiCN coatings were obtained by atmospheric plasma spray synthesis or reactive plasma spray. In order to promote the reaction between the Ti particles and reactive gases, a home-made gas tunnel was mounted on a conventional plasma gun to perform the spray process. The oxidation behavior of the TiCN coatings under different temperatures in static air was carefully investigated. As a result, when the temperature was over 700 °C, the coatings suffered from serious oxidation, and finally they were entirely oxidized to the TiO2 phase at 1100 °C. The principal oxidation mechanism was clarified, indicating that the oxygen can permeate into the defects and react with TiCN at high temperatures. In addition, concerning the use of a TiCN coating in high-temperature conditions, the microhardness of the oxidized coatings at different treatment temperatures was also evaluated.

  1. Pulsed photoinitiated synthesis of reduced graphitic oxides-coated Co3O4 nanocomposite thin film for silicon-based micro-supercapacitor application

    Science.gov (United States)

    Luo, Sijun; Oguntoye, Moses; Bourgeois, Briley; Shipman, Joshua; Pesika, Noshir; Chrisey, Douglas

    Herein we report a novel approach to pulsed photoinitiated synthesis of reduced graphitic oxides-coated Co3O4 in-situ nanocomposite thin film on Cu-coated silicon substrate through pulsed white light irradiating photosensitive Co-organic precursor drop-casted on the substrate. The instantaneous photoinitiated pyrolysis of precursor occurred in the first pulse irradiation forms graphitic oxides-coated Co3O4 nanocrystalline composite thin film with a 3-D nanostructure. The subsequent tens of pulses irradiation with a fluence of 7.7 J/cm2 for about 40 seconds improves the crystalline quality of Co3O4 nanograins and leads to reduction of graphitic oxides through pulsed photothermal effect. After 80,000 times of stable charge-discharge cycling in KOH electrolyte (measured at 2 mA/cm2 in a three-electrode cell), the nanocomposite thin film with a thickness around 1 um shows unoptimized specific areal capacity as high as 50 mF/cm2 and rate capability of 60 % retention from 0.1 mA/cm2 to 10 mA/cm2. This straightforward and scalable thin film processing opens a way to practical application of thin film-based micro-supercapacitor in silicon-based microelectronics devices and microelectromechanical systems.

  2. Accumulation of magnetic iron oxide nanoparticles coated with variably sized polyethylene glycol in murine tumors

    DEFF Research Database (Denmark)

    Larsen, Esben Kjær Unmack; Nielsen, Thomas; Wittenborn, Thomas

    2012-01-01

    Iron oxide nanoparticles have found widespread applications in different areas including cell separation, drug delivery and as contrast agents. Due to water insolubility and stability issues, nanoparticles utilized for biological applications require coatings such as the commonly employed...... polyethylene glycol (PEG). Despite its frequent use, the influence of PEG coatings on the physicochemical and biological properties of iron nanoparticles has hitherto not been studied in detail. To address this, we studied the effect of 333–20 000 Da PEG coatings that resulted in larger hydrodynamic size......, lower surface charge, longer circulation half-life, and lower uptake in macrophage cells when the particles were coated with high molecular weight (Mw) PEG molecules. By use of magnetic resonance imaging, we show coating-dependent in vivo uptake in murine tumors with an optimal coating Mw of 10 000 Da...

  3. Effects of grain boundaries at the electrolyte/cathode interfaces on oxygen reduction reaction kinetics of solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Min Gi; Koo, Ja Yang; Ahn, Min Woo; Lee, Won Young [Dept. of Mechanical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of)

    2017-04-15

    We systematically investigated the effects of grain boundaries (GBs) at the electrolyte/cathode interface of two conventional electrolyte materials, i.e., yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC). We deposited additional layers by pulsed laser deposition to control the GB density on top of the polycrystalline substrates, obtaining significant improvements in peak power density (two-fold for YSZ and three-fold for GDC). The enhanced performance at high GB density in the additional layer could be ascribed to the accumulation of oxygen vacancies, which are known to be more active sites for oxygen reduction reactions (ORR) than grain cores. GDC exhibited a higher enhancement than YSZ, due to the easier formation, and thus higher concentration, of oxygen vacancies for ORR. The strong relation between the concentration of oxygen vacancies and the surface exchange characteristics substantiated the role of GBs at electrolyte/cathode interfaces on ORR kinetics, providing new design parameters for highly performing solid oxide fuel cells.

  4. Tuning thin-film electrolyte for lithium battery by grafting cyclic carbonate and combed poly(ethylene oxide) on polysiloxane.

    Science.gov (United States)

    Li, Jie; Lin, Yue; Yao, Hehua; Yuan, Changfu; Liu, Jin

    2014-07-01

    A tunable polysiloxane thin-film electrolyte for all-solid-state lithium-ion batteries was developed. The polysiloxane was synthesized by hydrosilylation of polymethylhydrosiloxane with cyclic [(allyloxy)methyl]ethylene ester carbonic acid and vinyl tris(2-methoxyethoxy)silane. (1) H NMR spectroscopy and gel-permeation chromatography demonstrated that the bifunctional groups of the cyclic propylene carbonate (PC) and combed poly(ethylene oxide) (PEO) were well grafted on the polysiloxane. At PC/PEO=6:4, the polysiloxane-based electrolyte had an ionic conductivity of 1.55 × 10(-4) and 1.50 × 10(-3)  S cm(-1) at 25 and 100 °C, respectively. The LiFePO4 /Li batteries fabricated with the thin-film electrolyte presented excellent cycling performance in the temperature range from 25 to 100 °C with an initial discharge capacity at a rate of 1 C of 88.2 and 140 mA h g(-1) at 25 and 100 °C, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Ab initio investigation of ground-states and ionic motion in particular in zirconia-based solid-oxide electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Hirschfeld, Julian Arndt

    2012-12-11

    Electrolytes with high ionic conductivity at lower temperatures are the prerequisite for the success of Solid Oxide Fuel Cells (SOFC). One candidate is doped zirconia. In the past, the electrical resistance of zirconia based SOFC electrolytes has mainly been decreased by reducing its thickness. But there are limits to reducing the thickness and one can say that nowadays the normal ways are basically exhausted to further enhance the conductivity of well-known electrolyte materials. Hence, new approaches need to be found to discover windows of enhanced ionic conductivity. This can be achieved by understanding the quantum-mechanical oxygen transport in unconventional configurations of doped zirconia. Therefore, such an understanding is of fundamental importance. In this thesis two approaches are pursued, the investigation of the strain dependent ionic migration in zirconia based electrolytes and the designing of an electrolyte material structure with enhanced and strongly anisotropic ionic conductivity. The first approach expands the elementary understanding of oxygen migration in oxide lattices. The migration barrier of the oxygen ion jumps in zirconia is determined by applying the Density Functional Theory (DFT) calculations in connection with the Nudged Elastic Band (NEB) method. These computations show an unexpected window of decreased migration barriers at high compressive strains. Similar to other publications a decrease in the migration barrier for expansive strain is observed. But, in addition, a migration barrier decrease under high compressive strains is found beyond a maximal height of the migration barrier. A simple analytic model offers an explanation. The drop of the migration barrier at high compressions originates from the elevation of the ground-state energy. This means: Increasing ground state energies becomes an interesting alternative to facilitate ionic mobility. The second approach is based on the idea, that actually, only in the direction of ion

  6. Bilayer polymer/oxide coating for organic semiconductors

    DEFF Research Database (Denmark)

    Tavares, Luciana; Kjelstrup-Hansen, Jakob; Rubahn, Horst-Günter

    of the nanofibers with oxygen. Operation of devices in vacuum is a solution but the equipment necessary makes impossible the manufacturing of the devices so we propose the use of a coating for reducing bleaching. It is observed that spin-coated PMMA do not damage the morphology of the fragile nanofibers and also do...... luminescence spectrum and SiOx as a second layer for blocking the oxygen penetration. Bilayer coating PMMA/SiOx results in a significant reduction of bleaching without affecting significantly the emission spectrum from the nanofibers as well to avoid strong degradation of the nanofibers during electrical...

  7. Record-low sintering-temperature (600 °C) of solid-oxide fuel cell electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Dasari, Hari Prasad, E-mail: energyhari@nitk.edu.in [High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Chemical Engineering Department, National Institute of Technology Karnataka, Mangalore 575025, Karnataka (India); Ahn, Kiyong; Park, Sun-Young; Hong, Jongsup; Kim, Hyoungchul; Yoon, Kyung Joong; Son, Ji-Won; Kim, Byung-Kook; Lee, Hae-Weon [High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Lee, Jong-Ho, E-mail: jongho@kist.re.kr [High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)

    2016-07-05

    One of the major problems arising with Solid-Oxide Fuel Cell (SOFC) electrolyte is conventional sintering which requires a very high temperature (>1300 °C) to fully density the electrolyte material. In the present study, the sintering temperature of SOFC electrolyte is drastically decreased down to 600 °C. Combinational effects of particle size reduction, liquid-phase sintering mechanism and microwave sintering resulted in achieving full density in such a record-low sintering temperature. Gadolinium doped Ceria (GDC) nano-particles are synthesized by co-precipitation method, Lithium (Li), as an additional dopant, is used as liquid-phase sintering aid. Microwave sintering of this electrolyte material resulted in decreasing the sintering temperature to 600 °C. Micrographs obtained from Scanning/Transmission Electron Microscopy (SEM/TEM) clearly pointed a drastic growth in grain-size of Li-GDC sample (∼150 nm) than compared to GDC sample (<30 nm) showing the significance of Li addition. The sintered Li-GDC samples displayed an ionic conductivity of ∼1.00 × 10{sup −2} S cm{sup −1} at 600 °C in air and from the conductivity plots the activation energy is found to be 0.53 eV. - Highlights: • Sintering temperature is drastically decreased to 600 °C. • Key factors: Particle size reduction, liquid-phase and microwave sintering. • Nano-Li-GDC sample has ionic conductivity of ∼1.00 × 10{sup −2} S cm{sup −1} at 600 °C in air.

  8. The impact of the mass density on selected optical and non-optical properties of oxide coatings

    Science.gov (United States)

    Stenzel, Olaf

    2014-02-01

    The density of optical coatings is one of the most crucial material-related parameters in interference coating science and technology. It has an impact on the refractive index, the transparency range, and the mechanical stress of a coating material. This tutorial provides a background on the classical theory relating the coating density to the mentioned parameters. Simple models are presented that highlight the correlations between optical constants, stress, and shifting behavior of different oxide coatings. Comparison with the experiment is performed on the basis of numerous experimental data, which stem from hafnium oxide, zirconium oxide, tantalum pentoxide, and silicon dioxide.

  9. Energetics of perovskite-type materials applied in solid oxide fuel cells (SOFCs): Electrolytes, cathodes and interconnects

    Science.gov (United States)

    Cheng, Jihong

    Perovskite-type oxides (ABO3) find a great variety of applications in solid oxide fuel cells (SOFCs), including solid electrolytes, cathodes and interconnects, which are closely related to the defect chemistry involved. Thermodynamic studies are needed to systematically understand the nature of the structure-property relations and provide guidance to predict and/or select proper materials. High temperature solution calorimetry in molten oxide solvents is a powerful tool and has been applied for several perovskite systems that have simple (undoped) and complex (doped) compositions. LaBO3 perovskites (B = Al, Ga, Sc, In, Cr, Fe, Co, Ni) represent a group of excellent parent materials for electrolytes, cathodes, and interconnects in SOFCs. Their enthalpies of formation from oxides generally exhibit a relationship between stability and the major structural parameter for perovskites, the tolerance factor. As the tolerance factor deviates more from unity, the enthalpy of formation from oxides becomes less exothermic. This work verifies this general trend for A3+B3+O3 type perovskites, joining other two types, i.e., A1+B5+O 3 and A2+B4+O3. In alkaline earth doped perovskites, though structural parameters are likely to continue affecting stability, defects, which are introduced upon doping, actually play a more profound role in defining energetic trends. In the newly developed electrolyte materials, Mg, Sr, and Ba-doped LaGaO 3 perovskites, oxygen vacancies are created to compensate the charge imbalance between dopant and host ions. Oxygen vacancies have a destabilization effect on the structure due to the partial disconnection of the corner-shared BO6 octahedral framework. On the other hand, they tend to order at the short-range scale, forming vacancy-dopant clusters, as evidenced by neutron diffraction. In alkaline earth doped perovskites that contain transition metals, two charge compensation scenarios are possible: oxidation of the transition metal or creation of

  10. Role of Oxides and Porosity on High-Temperature Oxidation of Liquid-Fueled HVOF Thermal-Sprayed Ni50Cr Coatings

    Science.gov (United States)

    Song, B.; Bai, M.; Voisey, K. T.; Hussain, T.

    2017-02-01

    High chromium content in Ni50Cr thermally sprayed coatings can generate a dense and protective scale at the surface of coating. Thus, the Ni50Cr coating is widely used in high-temperature oxidation and corrosion applications. A commercially available gas atomized Ni50Cr powder was sprayed onto a power plant steel (ASME P92) using a liquid-fueled high velocity oxy-fuel thermal spray with three processing parameters in this study. Microstructure of as-sprayed coatings was examined using oxygen content analysis, mercury intrusion porosimetry, scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD). Short-term air oxidation tests (4 h) of freestanding coatings (without boiler steel substrate) in a thermogravimetric analyzer at 700 °C were performed to obtain the kinetics of oxidation of the as-sprayed coating. Long-term air oxidation tests (100 h) of the coated substrates were performed at same temperature to obtain the oxidation products for further characterization in detail using SEM/EDX and XRD. In all samples, oxides of various morphologies developed on top of the Ni50Cr coatings. Cr2O3 was the main oxidation product on the surface of all three coatings. The coating with medium porosity and medium oxygen content has the best high-temperature oxidation performance in this study.

  11. Stress controlled gas-barrier oxide coatings on semi-crystalline polymers

    Energy Technology Data Exchange (ETDEWEB)

    Rochat, G. [Laboratoire de Technologie des Composites et Polymeres (LTC), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Leterrier, Y. [Laboratoire de Technologie des Composites et Polymeres (LTC), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Fayet, P. [Tetra Pak (Suisse) SA, Tetra Pak R and D, Plasma Technology, C.P. 32, CH-1680 Romont (Switzerland); Manson, J.-A.E. [Laboratoire de Technologie des Composites et Polymeres (LTC), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)]. E-mail: jan-anders.manson@epfl.ch

    2005-07-22

    Thin silicon oxide (SiO{sub x}) barrier coatings formed by plasma enhanced chemical vapor deposition on poly(ethylene terephthalate) (PET) substrates were subjected to post-deposition annealing treatments in the temperature range for orientation relaxation of the polymer. The resulting change in coating internal stress state was measured by means of thermo-mechanical analyses, and its effect on the coating cohesive properties and coating/polymer adhesion was determined from the analysis of uniaxial fragmentation tests in situ in a scanning electron microscope, assuming a Weibull-type probability of failure and a perfectly plastic stress transfer at the SiO{sub x}/PET interface. The strain to failure and intrinsic fracture toughness of the ultrathin oxide coating were found to be as high as 5.7% and 10 J/m{sup 2}, respectively, and its interfacial shear strength with PET was found to be close to 100 MPa. Annealing for 10 min at 150 deg. C did not modify the oxygen permeation properties of the SiO{sub x}/PET film, which suggests that the defect population of the oxide was not affected by the thermal treatment. In contrast, the coating internal compressive stress resulting from annealing was shown to increase by 40% the apparent coating cohesive properties and adhesion to the polymer.

  12. A fully spray-coated fuel cell membrane electrode assembly using Aquivion ionomer with a graphene oxide/cerium oxide interlayer

    Science.gov (United States)

    Breitwieser, Matthias; Bayer, Thomas; Büchler, Andreas; Zengerle, Roland; Lyth, Stephen M.; Thiele, Simon

    2017-05-01

    A novel multilayer membrane electrode assembly (MEA) for polymer electrolyte membrane fuel cells (PEMFCs) is fabricated in this work, within a single spray-coating device. For the first time, direct membrane deposition is used to fabricate a PEMFC by spraying the short-side-chain ionomer Aquivion directly onto the gas diffusion electrodes. The fully sprayed MEA, with an Aquivion membrane 10 μm in thickness, achieved a high power density of 1.6 W/cm2 for H2/air operation at 300 kPaabs. This is one of the highest reported values for thin composite membranes operated in H2/air atmosphere. By the means of confocal laser scanning microscopy, individual carbon fibers from the gas diffusion layer are identified to penetrate through the micro porous layer (MPL), likely causing a low electrical cell resistance in the range of 150 Ω cm2 through the thin sprayed membranes. By spraying a 200 nm graphene oxide/cerium oxide (GO/CeO2) interlayer between two layers of Aquivion ionomer, the impact of the electrical short is eliminated and the hydrogen crossover current density is reduced to about 1 mA/cm2. The peak power density of the interlayer-containing MEA drops only by 10% compared to a pure Aquivion membrane of similar thickness.

  13. Anti-biofilm activity of zinc oxide and hydroxyapatite nanoparticles as dental implant coating materials.

    Science.gov (United States)

    Abdulkareem, Elham H; Memarzadeh, K; Allaker, R P; Huang, J; Pratten, J; Spratt, D

    2015-12-01

    Dental implants are prone to failure as a result of bacterial biofilm accumulation. Such biofilms are often resistant to traditional antimicrobials and the use of nanoparticles as implant coatings may offer a means to control infection over a prolonged period. The objective of this study was to determine the antibiofilm activity of nanoparticulate coated titanium (Ti) discs using a film fermenter based system. Metal oxide nanoparticles of zinc oxide (nZnO), hydroxyapatite (nHA) and a combination (nZnO+nHA) were coated using electrohydrodynamic deposition onto Ti discs. Using human saliva as an inoculum, biofilms were grown on coated discs for 96 h in a constant depth film fermenter under aerobic conditions with artificial saliva and peri-implant sulcular fluid. Viability assays and biofilm thickness measurements were used to assess antimicrobial activity. Following 96 h, reduced numbers of facultatively anaerobic and Streptococcus spp. on all three nano-coated surfaces were demonstrated. The proportion of non-viable microorganisms was shown to be higher on nZnO and composite (nZnO+nHA) coated surfaces at 96 h compared with nHA coated and uncoated titanium. Biofilm thickness comparison also demonstrated that nZnO and composite coatings to be the most effective. The findings support the use of coating Ti dental implant surfaces with nZnO to provide an antimicrobial function. Current forms of treatment for implant associated infection are often inadequate and may result in chronic infection requiring implant removal and resective/regenerative procedures to restore and reshape supporting tissue. The use of metal oxide nanoparticles to coat implants could provide osteoconductive and antimicrobial functionalities to prevent failure. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Durability of hydrophobic coatings for superhydrophobic aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Jenner, Elliot, E-mail: Elj17@pitt.edu [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Barbier, Charlotte, E-mail: barbiercn@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); D’Urso, Brian, E-mail: dursobr@pitt.edu [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States)

    2013-10-01

    Robust and easily produced superhydrophobic surfaces are of great interest for mechanical applications, including drag reduction and MEMS. We produce novel superhydrophobic surfaces with several different coatings and tested the durability of each of these coatings with respect to long term immersion in water in order to determine the most long-lasting surface preparation. A pair of combinations of spin on polymers, surface features, and adhesion promoters was found that provide long term durability.

  15. Properties and structure of oxide layers on thin coating of titanium alloy

    Directory of Open Access Journals (Sweden)

    Jan Krčil

    2015-12-01

    Full Text Available Present work discusses issues of growth and characterization of a thin oxide layer formed on the surface of a titanium-niobium alloy. An oxide layer on the surface of titanium alloys introduces a corrosion resistance and also a bio-compatibility, which is required for a medical application. Although this oxide layer is a result of a spontaneous passivation, for the practical applications it is necessary to control the growth of oxides. In this work the oxide layer was formed on the PVD coating from Ti39Nb alloy which was sputtered on three different base materials: CP Ti grade 2, stainless steel AISI 316LVM and titanium alloy Ti–6Al–4V ELI. The oxide layer was created by a thermal oxidation at 600 °C for three different oxidation periods: 1, 4 and 8 hours. After the oxidation process the influence of oxidation characteristics and base materials on the thickness and properties of oxide layer was studied. There was observed a change of color and surface roughness. The oxide layer surface as well as the layer thickness was observed by SEM. The influence of the substrate material under the coating on the oxide layer should be more investigated in the future.

  16. Microstructural Characteristics and Oxidation Behavior of Low-Pressure Cold-Sprayed CoNiCrAlY Coatings

    Science.gov (United States)

    Zhang, Lin-wei; Lu, Lei; Wang, Lu; Ning, Xian-jin; Wang, Quan-sheng; Wang, Ri-xin

    2017-10-01

    CoNiCrAlY coatings were deposited by low-pressure cold spraying and subsequently heat-treated at 1050 °C for 4 h in a vacuum environment. The microstructural characteristics and oxidation behavior of CoNiCrAlY coatings were investigated. The as-sprayed coating exhibited low porosity and oxygen content. The high plastic deformation of the sprayed particles led to significant refinement of γ-matrix and dissolution of β-(Ni,Co)Al phase in the as-sprayed coating. After heat treatment, the single phase (γ) in the as-sprayed coating was converted into a γ/β microstructure, and a continuous single α-Al2O3 scale was formed on the coating surface. Vacuum heat treatment can postpone the formation of spinel oxides within 100 h. After being oxidized at 1050 °C for 400 h, the heat-treated coating exhibited better oxidation resistance than the as-sprayed coating. The reduced growth rate of the oxide scale and the suppression of the formation of spinel oxides can be attributed to the vacuum heat treatment, as well as the intrinsic microstructure of the cold-sprayed coating. Finally, the effects of the microstructural changes induced during the cold spraying process on the growth of the thermally grown oxide and the oxidation mechanisms of the CoNiCrAlY coatings were discussed.

  17. Study on poly(ethylene-oxide) electrolytes with ionophores for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lisowska-Oleksiak, A.; Inerowicz, H.D. [Technical Univ. Gdansk (Poland). Dept. of Chemistry

    1999-09-01

    Kinetics and mechanism for the electrodeposition of lithium from tetraethylene glycol dimethyl ether electrolytes formed from lithium perchlorate and ionophores have been studied using voltammetric and chronoamperometric methods at Pt and Au electrodes. The ionophore influence on stripping efficiencies, nucleation overpotentials, exchange current densities was evaluated. The type of nucleation and crystal growth process was determined. (orig.)

  18. Manufacture and demonstration of organic photovoltaic-powered electrochromic displays using roll coating methods and printable electrolytes

    DEFF Research Database (Denmark)

    Jensen, Jacob; Dam, Henrik Friis; Reynolds, John R.

    2012-01-01

    Electrochromic devices (ECDs) were prepared on flexible substrates using spray coating and slot-die coating methods. The electrochromic materials were the conjugated electroactive polymers, poly((2,2-bis(2-ethylhexyloxymethyl)-propylene-1,3-dioxy)-3,4-thiophene-2,5-diyl) as a vibrantly colored ac...

  19. Characterization and corrosion behavior of ceramic coating on magnesium by micro-arc oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Durdu, Salih [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, Kocaeli 41400 (Turkey); Aytac, Aylin [Gazi University, Faculty of Science, Department of Chemistry, Teknikokullar, Ankara 06500 (Turkey); Usta, Metin, E-mail: ustam@gyte.edu.tr [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, Kocaeli 41400 (Turkey)

    2011-08-25

    Highlights: {center_dot} The commercial pure magnesium was coated by micro-arc oxidation method. {center_dot} The coating is composed of two layers, a porous outer layer and a dense inner layer. {center_dot} A super corrosion resistance was achieved with MAO coatings. {center_dot} Coating with Mg{sub 2}SiO{sub 4} is more resistant to corrosion than that containing Mg{sub 3}(PO{sub 4}){sub 2}. - Abstract: In this study, the commercial pure magnesium was coated in different aqueous solutions of Na{sub 2}SiO{sub 3} and Na{sub 3}PO{sub 4} by the micro-arc oxidation method (MAO). Coating thickness, phase composition, surface and cross sectional morphology and corrosion resistance of coatings were analyzed by eddy current method, X-ray diffraction (XRD), scanning electron microscope (SEM) and tafel extrapolation method, respectively. The average thickness of the coatings ranged from 52 to 74 {mu}m for sodium silicate solution and from 64 to 88 {mu}m for sodium phosphate solution. The dominant phases on the coatings were detected as spinal Mg{sub 2}SiO{sub 4} (Forsterite) and MgO (Periclase) for sodium silicate solution and Mg{sub 3}(PO{sub 4}){sub 2} (Farringtonite) and MgO (Periclase) for sodium phosphate solution. SEM images reveal that the coating is composed of two layers as of a porous outer layer and a dense inner layer. The corrosion results show the coating consisting Mg{sub 2}SiO{sub 4} is more resistant to corrosion than that containing Mg{sub 3}(PO{sub 4}){sub 2}.

  20. Carboxymethyl cellulose coating decreases toxicity and oxidizing capacity of nanoscale zerovalent iron.

    Science.gov (United States)

    Zhou, Lei; Thanh, Thao Le; Gong, Jianyu; Kim, Jae-Hwan; Kim, Eun-Ju; Chang, Yoon-Seok

    2014-06-01

    Nanoscale zerovalent iron (NZVI) with modified surface via coating with organic stabilizers has been documented with enhanced colloidal stability and dispersity. Therefore, the expanded application potential and accompanying intrinsic exposure of such nanoparticle can be anticipated. In our study, carboxymethyl cellulose (CMC)-stabilized NZVI (CNZVI) exerted minimized oxidative stress response and slower disruption of cell membrane integrity, resulting in mitigated cytotoxicity towards bacteria Agrobacterium sp. PH-08 as compared with the uncoated counterpart. The corrosive oxidation of both nanoparticles in oxygenic water provided a better understanding of coating effect. The decreased oxidative degradation of probe 4-chlorophenol with CNZVI than NZVI implicated a weaker oxidizing capacity, which might overweight massive adhesion-mediated redox damage and explain the different exposure outcome. However, enhanced evolution of iron oxide as well as the promoted production of hydrogen peroxide adversely demonstrated CMC-coating facilitated iron corrosion by oxygen, suggesting CMC was most likely to act as a radical scavenger and compete with organics or bacteria for oxidants. Moreover, XRD, XPS and TEM results showed that the spherical NZVI was oxidized to form needle-shaped iron oxide-hydroxide (γFeOOH) with no detectable oxidative stress for PH-08, alleviating worries regarding exotoxicological impact of iron nanotechnology. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Ionic conductivity of a polymer electrolyte with modified carbonate as a plasticizer for poly(ethylene oxide)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H.S.; Yang, X.Q.; McBreen, J. (Brookhaven National Lab., Upton, NY (United States)); Xu, Z.S.; Skotheim, T.A. (Moltech Corp., Stony Brook, NY (United States)); Okamoto, Y. (Polytechnic Univ., Brooklyn, NY (United States))

    1994-04-01

    A new type of plasticizer, a modified carbonate (MC3) made by attaching three ethylene oxide units to the 4-position of ethylene carbonate, has been synthesized. The ionic conductivity of a polymer electrolyte using this type of plasticizer in a poly(ethylene oxide) (PEO)-LiCF[sub 3]SO[sub 3] complex has been studied. Adding 50% of this plasticizer by weight of PEO to the PEO-LiCF[sub 3]SO[sub 3] complex, yielded an ionic conductivity of 5 [times] 10[sup [minus]5] S/cm at 25 C, which is two orders of magnitude higher than that found for a PEO-LiCF[sub 3]SO[sub 3] electrolyte without a plasticizer, and one order of magnitude higher than that found when using propylene carbonate (PC) as a plasticizer. The temperature dependence of the conductivity and thermal analysis results indicate that this new plasticizer increases the ionic conductivity throughout the entire complex system, whereas conventional plasticizers, like PC, simply create a high conductivity pathway through the plasticizer itself. The new plasticizer also enhances the ion pair dissociation which in turn improves the ionic conductivity.

  2. Preparation and characterization of solid electrolytes for solid oxide fuel cells. Quarterly report, July 1--September 30, 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    During this quarter, the authors have analyzed EXAFS spectra of rare earth doped ceria and identified Gd and Sm doped ceria electrolytes for further investigations in this project. Although electrical properties of the material have been examined in detail, very little work has considered the microstructural/property relationships, particularly in relationship to atomic and geometric structures of these ceria based oxides. The authors have observed an ionic conductivity of 8.3 {times} 10{sup {minus}2} S/Cm in the (CeO{sub 2}){sub 0.8}(GdO{sub 1.5}){sub 0.2} at 800 C which is approximately four times that of Y{sub 2}O{sub 3} doped ZrO{sub 3} doped ZrO{sub 2} at the same temperature. The fraction of Ce{sup +4} ions reduced to Ce{sup +3} as a function of temperature and oxygen partial pressure. The partial reduction of cerium oxide generates mobile electrons and causes electronic conductivity in the electrolyte at temperatures above 500 C. In this quarter, the authors have attempted to measure the microstructural properties using SEM, TEM and HVC STM techniques. Other parts of this investigation are also discussed.

  3. Characterization of the wear resistant aluminum oxide - 40% titaniumdioxide coating

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2014-02-01

    Full Text Available Plasma spray coatings play an important role in the design of surface properties of engineering components in order to increase their durability and performance under different operating conditions. Coatings are the most often used for wear resistance. This paper presents the microstructure and mechanical properties Al2O3_­40wt.%TiO2 coating resistant to dry friction slide, grain abrasion and erosion of particles at operating temperatures up to 540°C. In order to obtain the optimal characteristics of coating was performed  optimization  of deposition parameters. The powder Al2O3­40wt.%TiO2 is deposited atmospheric plasma spraying (APS process with a plasma current of 700, 800 and 900A. Evaluate the quality of the coating Al2O3­40wt.%TiO2 were made on the basis of their hardness, tensile bond strength and microstructure. The best performance showed the deposited layers with 900A. The morphology of the powder particles Al2O3­40wt.%TiO2 was examined with SEM (Scanning Electron Microscope. Microstructure of the coatings was examined by light microscopy. Analysis of the deposited layers was performed in accordance with standard Pratt & Whitney. Evaluation of mechanical properties of the layers was done by examining HV0.3 microhardness and tensile strength of the tensile testing. Studies have shown that plasma currents significantly affects the mechanical properties and microstructure of coatings which are of crucial importance for the protection for components subjected to wear       

  4. Structural evolution, thermomechanical recrystallization and electrochemical corrosion properties of Ni-Cu-Mg amorphous coating on mild steel fabricated by dual-anode electrolytic processing

    Science.gov (United States)

    Abdulwahab, M.; Fayomi, O. S. I.; Popoola, A. P. I.

    2016-07-01

    The electrolytic Ni-Cu based alloy coating with admixed interfacial blend of Mg have been successfully prepared on mild steel substrate by dual anode electroplating processes over a range of applied current density and dwell time. The electrocodeposition of Ni-Cu-Mg coating was investigated in the presence of other bath additives. The influence of deposition current on surface morphology, adhesion behavior, preferred crystal orientation, surface topography and electrochemical activity of Ni-Cu-Mg alloy coating on mild steel were systematically examined. The thermal stability of the developed composite materials was examined via isothermal treatment. Scanning electron microscope equipped with EDS, X-ray diffraction, Atomic force microscope, micro-hardness tester and 3 μmetrohm Potentiostat/galvanostat were used to compare untreated and isothermally treated electrocodeposited composite. The induced activity of the Ni-Cu-Mg alloy changed the surface modification and results to crystal precipitation within the structural interface by the formation of Cu, Ni2Mg3 phase. The obtained results showed that the introduction of Mg particles in the plating bath generally modified the surface and brings an increase in the hardness and corrosion resistance of Ni-Cu-Mg layers fabricated. Equally, isothermally treated composites demonstrated an improved properties indicating 45% increase in the micro-hardness and 79.6% corrosion resistance which further showed that the developed composite is thermally stable.

  5. Effect of Zirconium Oxide Nanofiller and Dibutyl Phthalate Plasticizer on Ionic Conductivity and Optical Properties of Solid Polymer Electrolyte

    Directory of Open Access Journals (Sweden)

    Siti Mariah Mohd Yasin

    2014-01-01

    Full Text Available New solid polymer electrolytes (SPE based on poly(ethylene oxide (PEO doped with lithium trifluoromethanesulfonate (LiCF3SO3, dibutyl phthalate (DBP plasticizer, and zirconium oxide (ZrO2 nanoparticles were prepared by solution-casting technique. The conductivity was enhanced by addition of dibutyl phthalate (DBP plasticizer and ZrO2 nanofiller with maximum conductivity (1.38×10-4 Scm-1. The absorption edge and band gap values showed decreases upon addition of LiSO3CF3, DBP, and ZrO2 due to the formation of localized states in the SPE and the degree of disorder in the films increased.

  6. Solid-state supercapacitors with ionic liquid gel polymer electrolyte based on poly (3, 4-ethylenedioxythiophene), carbon nanotubes, and metal oxides nanocomposites for electrical energy storage

    Science.gov (United States)

    Obeidat, Amr M.

    Clean and renewable energy systems have emerged as an important area of research having diverse and significant new applications. These systems utilize different energy storage methods such as the batteries and supercapacitors. Supercapacitors are electrochemical energy storage devices that are designed to bridge the gap between batteries and conventional capacitors. Supercapacitors which store electrical energy by electrical double layer capacitance are based on large surface area structured carbons. The materials systems in which the Faradaic reversible redox reactions store electrical energy are the transition metal oxides and electronically conducting polymers. Among the different types of conducting polymers, poly (3, 4- ethylenedioxythiophene) (PEDOT) is extensively investigated owing to its chemical and mechanical stability. Due to instability of aqueous electrolytes at high voltages and toxicity of organic electrolytes, potential of supercapacitors has not been fully exploited. A novel aspect of this work is in utilizing the ionic liquid gel polymer electrolyte to design solid-state supercapacitors for energy storage. Various electrochemical systems were investigated including graphene, PEDOT, PEDOT-carbon nanotubes, PEDOT-manganese oxide, and PEDOT-iron oxide nanocomposites. The electrochemical performance of solid-state supercapacitor devices was evaluated based on cyclic voltammetry (CV), charge-discharge (CD), prolonged cyclic tests, and electrochemical impedance spectroscopy (EIS) techniques. Raman spectroscopy technique was also utilized to analyze the bonding structure of the electrode materials. The graphene solid-state supercapacitor system displayed areal capacitance density of 141.83 mF cm-2 based on high potential window up to 4V. The PEDOT solid-state supercapacitor system was synthesized in acetonitrile and aqueous mediums achieving areal capacitance density of 219.17 mF cm-2. The hybrid structure of solid-state supercapacitors was also

  7. Improving the oxidation resistance of AlCrN coatings by tailoring chromium out-diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Escobar Galindo, R., E-mail: rescobar@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, E-28049 Madrid (Spain); Endrino, J.L. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, E-28049 Madrid (Spain); Martinez, R. [AIN-Centro de Ingenieria Avanzada de Superficies, Cordovilla, E-31191 Pamplona (Spain); Albella, J.M. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, E-28049 Madrid (Spain)

    2010-11-15

    In this work, we have studied the improvement on the oxidation resistance of AlCrN-based coatings by adding a subsurface titanium nitride barrier layer. Since oxidation is interrelated with the inward diffusion of oxygen into the surface of Al{sub x}Cr{sub 1-x}N (x = 0.70) coatings and the outward diffusion of Cr to the surface, the oxidation behaviour of the aluminium-rich AlCrN coatings can be tuned by designing the coating in an appropriate layered structure. The buried depth of the embedded layer and the oxidation time were varied, and the changes in the AlCrN/TiN depth composition profiles and surface oxidation stoichiometry were analysed by means of Glow Discharge Optical Emission Spectroscopy (GDOES) and Cross Sectional SEM (X-SEM) maps. It was observed that when a TiN diffusion barrier of 300 nm was deposited near the top surface (500 nm from the surface) the inhibition of the inward diffusion of oxygen and formation of beneficial alumina surface layers was promoted and consequently an increase of the oxidation resistance is achieved. This is explained in terms of a limited surplus of chromium from the coating to the surface. This was corroborated after performing experiments using CrN as embedded barrier layer which resulted in a continuous surplus of chromium to the surface and the formation of Cr-rich oxides. GDOES, in combination with X-SEM elemental maps, was proved to be a fast and accurate technique to monitor composition in-depth changes during oxidation, providing unique information regarding the oxide structure formation.

  8. Modelling of the mercury loss in fluorescent lamps under the influence of metal oxide coatings

    Science.gov (United States)

    Santos Abreu, A.; Mayer, J.; Lenk, D.; Horn, S.; Konrad, A.; Tidecks, R.

    2016-11-01

    The mercury transport and loss mechanisms in the metal oxide coatings of mercury low pressure discharge fluorescent lamps have been investigated. An existing model based on a ballistic process is discussed in the context of experimental mercury loss data. Two different approaches to the modeling of the mercury loss have been developed. The first one is based on mercury transition rates between the plasma, the coating, and the glass without specifying the underlying physical processes. The second one is based on a transport process driven by diffusion and a binding process of mercury reacting to mercury oxide inside the layers. Moreover, we extended the diffusion based model to handle multi-component coatings. All approaches are applied to describe mercury loss experiments under the influence of an Al 2 O 3 coating.

  9. Oleic acid-grafted chitosan/graphene oxide composite coating for corrosion protection of carbon steel.

    Science.gov (United States)

    Fayyad, Eman M; Sadasivuni, Kishor Kumar; Ponnamma, Deepalekshmi; Al-Maadeed, Mariam Al Ali

    2016-10-20

    An anticorrosion coating film based on the formation of nanocomposite coating is reported in this study. The composite consisted of chitosan (green matrix), oleic acid, and graphene oxide (nano filler). The nanocomposite coating was arranged on the surface of carbon steel, and the corrosion resistance was monitored using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP). Compared to the pure chitosan (CS) coating, the corrosion resistance of oleic acid-modified chitosan/graphene oxide film (CS/GO-OA) is increased by 100 folds. Since the well-dispersed smart grafted nanolayers delayed the penetration rate of corrosive species and thus maintained long term anticorrosive stability which is correlated with hydrophobicity and permeability. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Method of producing an oxide dispersion strengthened coating and micro-channels

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Bruce S; Chyu, Minking K; Alvin, Mary Anne; Gleeson, Brian M

    2013-12-17

    The disclosure provides a method for the production of composite particles utilizing a mechano chemical bonding process following by high energy ball milling on a powder mixture comprised of coating particles, first host particles, and second host particles. The composite particles formed have a grain size of less than one micron with grains generally characterized by a uniformly dispersed coating material and a mix of first material and second material intermetallics. The method disclosed is particularly useful for the fabrication of oxide dispersion strengthened coatings, for example using a powder mixture comprised of Y.sub.2O.sub.3, Cr, Ni, and Al. This particular powder mixture may be subjected to the MCB process for a period generally less than one hour following by high energy ball milling for a period as short as 2 hours. After application by cold spraying, the composite particles may be heat treated to generate an oxide-dispersion strengthened coating.

  11. Transport, retention, and long-term release behavior of polymer-coated silver nanoparticles in saturated quartz sand: The impact of natural organic matters and electrolyte.

    Science.gov (United States)

    Hou, Jun; Zhang, Mingzhi; Wang, Peifang; Wang, Chao; Miao, Lingzhan; Xu, Yi; You, Guoxiang; Lv, Bowen; Yang, Yangyang; Liu, Zhilin

    2017-10-01

    This study investigated the transport and long-term release of stabilized silver nanoparticles (AgNPs), including polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs) and bare AgNPs (Bare-AgNPs), in the presence of natural organic matters (NOMs; both humic acids (HA) and alginate (Alg)) and an electrolyte (Ca 2+ ) in a sand-packed column. Very low breakthrough rate (C/C 0 ) of AgNPs (below 0.04) occurred in the absence of NOM and the electrolyte. Increasing the concentration of NOM and decreasing the influent NOM solution's ionic strength (IS) reduced the retention of AgNPs. The reduced NP retention at high NOM and low IS was mainly attributed to the increased energy barrier between the AgNPs and the sand grain surface. Notably, the retention of PVP-AgNPs was enhanced at high Alg concentration and low IS, which mainly resulted from the improved hydrophobicity that could increase the interaction between the PVP-AgNPs and the collector. The total release amount of PVP-AgNPs (10.03%, 9.50%, 28.42%, 6.37%) and Bare-AgNPs (3.28%, 2.58%, 10.36%, 1.54%) were gained when exposed to four kinds of NOM solutions, including deionized water, an electrolyte solution (1 mM Ca 2+ ), HA with an electrolyte (1 mM Ca 2+ ), and a Alg (40 mg/L) solution with an electrolyte (1 mM Ca 2+ ). The long-term release of retained silver nanoparticles in the quartz sand was mostly through the form of released Ag NPs. The factors that increased the mobility of AgNPs in quartz sand could improve the release of the AgNPs. The release of AgNPs had no significant change in the presence Ca 2+ but were increased in the presence of HA. The Alg slightly decreased the release of AgNPs by increasing the hydrophobicity of AgNPs. The results of the study indicated that all the tested NOM and Ca 2+ have prominent influence on the transport and long-term release behavior of silver nanoparticles in saturated quartz sand. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Femtosecond laser damage resistance of oxide and mixture oxide optical coatings.

    Science.gov (United States)

    Mangote, Benoit; Gallais, Laurent; Commandré, Mireille; Mende, Mathias; Jensen, Lars; Ehlers, Henrik; Jupé, Marco; Ristau, Detlev; Melninkaitis, Andrius; Mirauskas, Julius; Sirutkaitis, Valdas; Kičas, Simonas; Tolenis, Tomas; Drazdys, Ramutis

    2012-05-01

    We report on the laser damage resistance of ion beam-sputtered oxide materials (Al2O3, Nb2O5, HfO2, SiO2, Ta2O5, ZrO2) and mixtures of Al2O3-SiO2, Nb2O5-SiO2, HfO2-SiO2, Ta2O5-SiO2, and ZrO2-SiO2, irradiated by single 500 fs pulses at 1030 nm. Laser-induced damage threshold (LIDT), refractive index, and bandgaps of the single-layer coatings are measured. For pure oxide materials a linear evolution of the LIDT with bandgap is observed. The results are in accordance with our simulations based on photo-ionization and avalanche-ionization. In the case of mixtures, however, deviations from the previous behaviors are evidenced. The evolution of the LIDT as a function of the refractive index is analyzed, and an empirical description of the relation between refractive index and LIDT is proposed.

  13. Kinetics of the electrolytic Fe+2/Fe+3 oxidation on various anode materials

    Directory of Open Access Journals (Sweden)

    Cifuentes, L.

    2003-08-01

    Full Text Available The kinetics of the electrolytic Fe+2/Fe+3 oxidation, relevant to hydro-electrometallurgical processing, have been studied on lead, platinum, ruthenium oxide, iridium oxide and graphite anodes in ferrous sulfate-sulfuric acid solutions. The oxidation rate depends on ferrous sulfate concentration, solution temperature and degree of agitation. Potentiodynamic studies show that: a the highest oxidation rate is obtained on platinum; b lead is unsuitable as anodic material for the said reaction; c the remaining anode materials show a similar and satisfactory performance.

    Se ha estudiado la cinética de la oxidación electrolítica Fe+2/Fe+3 -relevante para el procesamiento hidroelectrometalúrgico- sobre plomo, platino, óxido de rutenio, óxido de iridio y grafito en soluciones de sulfato ferroso en ácido sulfúrico. La velocidad de oxidación depende de la concentración de sulfato ferroso, la temperatura de la solución y el grado de agitación. Estudios potenciodinámicos demuestran que: a las mayores velocidades de oxidación se obtienen sobre platino; b el plomo es inadecuado como material anódico para la reacción mencionada; c los materiales anódicos restantes exhiben un desempeño similar y satisfactorio.

  14. Evaluation of the mechanical properties of microarc oxidation coatings and 2024 aluminium alloy substrate

    CERN Document Server

    Xue Wen Bin; Deng Zhi Wei; Chen Ru Yi; Li Yong Liang; Zhang Ton Ghe

    2002-01-01

    A determination of the phase constituents of ceramic coatings produced on Al-Cu-Mg alloy by microarc discharge in alkaline solution was performed using x-ray diffraction. The profiles of the hardness, H, and elastic modulus, E, across the ceramic coating were determined by means of nanoindentation. In addition, a study of the influence of microarc oxidation coatings on the tensile properties of the aluminium alloy was also carried out. The results show that the H-and E-profiles are similar, and both of them exhibit a maximum value at the same depth of coating. The distribution of the alpha-Al sub 2 O sub 3 phase content determines the H- and E-profiles of the coatings. The tensile properties of 2024 aluminium alloy show less change after the alloy has undergone microarc discharge surface treatment.

  15. The Effect of Heat Treatment on the Oxidation Behavior of HVOF and VPS CoNiCrAlY Coatings

    Science.gov (United States)

    Saeidi, S.; Voisey, K. T.; McCartney, D. G.

    2009-06-01

    Free-standing VPS and HVOF CoNiCrAlY coatings were produced. The as-sprayed HVOF coating retained the γ/β microstructure of the feedstock powder, and the VPS coating consisted of a single (γ) phase. A 3-h, 1100 °C heat treatment in vacuum converted the single-phase VPS coating to a two-phase γ/β microstructure and coarsened the γ/β microstructure of the HVOF coating. Oxidation of free-standing as-sprayed and heat-treated coatings of each type was carried out in air at 1100 °C for a duration of 100 h. Parabolic rate constant(s), K p, were determined for free-standing, as-sprayed VPS and HVOF coatings as well as for free-standing coatings that were heat treated prior to oxidation. The observed increase in K p following heat treatment is attributed to a sintering effect eliminating porosity from the coating during heat treatment. The lower K p values determined for both HVOF coatings compared to the VPS coatings is attributed to the presence of oxides in the HVOF coatings, which act as the barrier to diffusion. Oxidation of the as-sprayed coatings produced a dual-layer oxide consisting of an inner α-Al2O3 layer and outer spinel layer. Oxidation of the heat-treated samples resulted in a single-layer oxide, α-Al2O3. The formation of a thin α-Al2O3 layer during heat treatment appeared to prevent nucleation and growth of spinel oxides during subsequent oxidation.

  16. Pulsed sonication for alumina coatings on high-capacity oxides: Performance in lithium-ion cells

    Science.gov (United States)

    Pol, Vilas G.; Li, Yan; Dogan, Fulya; Secor, Ethan; Thackeray, Michael M.; Abraham, Daniel P.

    2014-07-01

    High-capacity xLi2MnO3·(1 - x)LiMO2 (M = Ni, Mn, Co) oxides show relatively rapid performance degradation when cycled at voltages >4.5 V vs. Li/Li+. Previous research has indicated that modifying the oxide surfaces with coatings, such as alumina, reduces cell impedance rise and improves capacity retention. In this article, we demonstrate pulsed-sonication as a rapid and effective approach for coating alumina on Li1.2Ni0.175Mn0.525Co0.1O2 (0.5Li2MnO3·0.5LiNi0.44Mn0.31Co0.25O2) particles. Oxide integrity and morphology is maintained after the sonochemical process and subsequent heat-treatment. Energy dispersive spectroscopy (EDS) X-ray elemental maps show uniform coating of all secondary particles. 27Al Magic Angle Spinning (MAS) NMR data confirm the presence of alumina and mainly indicate octahedral aluminum occupancy in a six-coordinate environment with oxygen. Full cells containing electrodes with the alumina-coated particles demonstrate lower initial impedance rise and better capacity retention during extended cycling to high voltages. However, the coating has a negligible effect on the voltage hysteresis and voltage fade behavior displayed by these oxides. The various data indicate that the pulsed sonochemical technique is a viable approach for coating oxide particles. The methodology described herein can easily be extended beyond alumina to include coatings such as AlF3, MgO, and MgF2.

  17. Pulsed sonication for alumina coatings on high-capacity oxides: Performance in lithium-ion cells

    Energy Technology Data Exchange (ETDEWEB)

    Pol, Vilas G.; Li, Yan; Dogan, Fulya; Secor, Ethan; Thackeray, Michael M.; Abraham, Daniel P.

    2014-07-01

    High-capacity xLi2MnO3•(1-x)LiMO2 (M=Ni, Mn, Co) oxides show relatively rapid performance degradation when cycled at voltages >4.5V vs. Li/Li+. Previous research has indicated that modifying the oxide surfaces with coatings, such as alumina, reduces cell impedance rise and improves capacity retention. In this article, we demonstrate pulsed-sonication as a rapid and effective approach for coating alumina on Li1.2Ni0.175Mn0.525Co0.1O2 (0.5Li2MnO3•0.5LiNi0.44Mn0.31Co0.25O2) particles. Oxide integrity and morphology is maintained after the sonochemical process and subsequent heat-treatment. Energy dispersive spectroscopy (EDS) X-ray elemental maps show uniform coating of all secondary particles. 27Al Magic Angle Spinning (MAS) NMR data confirm the presence of alumina and mainly indicate octahedral aluminum occupancy in a six-coordinate environment with oxygen. Full cells containing electrodes with the alumina-coated particles demonstrate lower initial impedance rise and better capacity retention during extended cycling to high voltages. However, the coating has a negligible effect on the voltage hysteresis and voltage fade behavior displayed by these oxides. The various data indicate that the pulsed sonochemical technique is a viable approach for coating oxide particles. The methodology described herein can easily be extended beyond alumina to include coatings such as AlF3, MgO, and MgF2.

  18. Performance Stability of Silicone Oxide-Coated Plastic Parenteral Vials.

    Science.gov (United States)

    Weikart, Christopher M; Pantano, Carlo G; Shallenberger, Jeff R

    2017-01-01

    A new packaging system was developed for parenteral pharmaceuticals that combines the best attributes of plastic and glass without their respective drawbacks. This technological advancement is based on the synergy between high-precision injection-molded plastics and plasma coating technology. The result is a shatter-resistant, optically clear, low-particulate, and chemically durable packaging system. The demand for this product is driven by the expanding market, regulatory constraints, and product recalls for injectable drugs and biologics packaged in traditional glass materials. It is shown that this new packaging system meets or exceeds the important performance characteristics of glass, especially in eliminating the glass delamination and breakage that has been observed in many products. The new packaging system is an engineered, multilayer, glass-coated plastic composite that provides a chemically stable contact surface and oxygen barrier performance that exceeds a 2 year shelf life requirement. Evaluation of the coating system characteristics and performance stability to chemical, temperature, and mechanical extremes are reported herein.LAY ABSTRACT: A new packaging system for parenteral pharmaceuticals was developed that combines the best attributes of plastic and glass without their respective drawbacks. This technological advancement is based on the synergy between high-precision injection-molded plastics and plasma coating technology. The result is a shatter-resistant, optically clear, low-particulate, and chemically durable packaging system. It is shown that this new packaging system meets or exceeds the important performance characteristics of glass, especially in eliminating the glass delamination and breakage that has been observed in many products. The new packaging system is an engineered, multilayer, glass-coated plastic composite that provides a chemically stable contact surface and oxygen barrier performance that exceeds a 2 year shelf life

  19. Effect of coating thickness of iron oxide nanoparticles on their relaxivity in the MRI.

    Science.gov (United States)

    Hajesmaeelzadeh, Farzaneh; Shanehsazzadeh, Saeed; Grüttner, Cordula; Daha, Fariba Johari; Oghabian, Mohammad Ali

    2016-02-01

    Iron oxide nanoparticles have found prevalent applications in various fields including drug delivery, cell separation and as contrast agents. Super paramagnetic iron oxide (SPIO) nanoparticles allow researchers and clinicians to enhance the tissue contrast of an area of interest by increasing the relaxation rate of water. In this study, we evaluate the dependency of hydrodynamic size of iron oxide nanoparticles coated with Polyethylene glycol (PEG) on their relativities with 3 Tesla clinical MRI. We used three groups of nanoparticles with nominal sizes 20, 50 and 100 nm with a core size of 8.86 nm, 8.69 nm and 10.4 nm that they were covered with PEG 300 and 600 Da. A clinical magnetic resonance scanner determines the T1 and T2 relaxation times for various concentrations of PEG-coated nanoparticles. The size measurement by photon correlation spectroscopy showed the hydrodynamic sizes of MNPs with nominal 20, 50 and 100 nm with 70, 82 and 116 nm for particles with PEG 600 coating and 74, 93 and 100 nm for particles with PEG 300 coating, respectively. We foud that the relaxivity decreased with increasing overall particle size (via coating thickness). Magnetic resonance imaging showed that by increasing the size of the nanoparticles, r2/r1 increases linearly. According to the data obtained from this study it can be concluded that increments in coating thickness have more influence on relaxivities compared to the changes in core size of magnetic nanoparticles.

  20. Electrical Properties of Conductive Cotton Yarn Coated with Eosin Y Functionalized Reduced Graphene Oxide.

    Science.gov (United States)

    Kim, Eunju; Arul, Narayanasamy Sabari; Han, Jeong In

    2016-06-01

    This study reports the fabrication and investigation of the electrical properties of two types of conductive cotton yarns coated with eosin Y or eosin B functionalized reduced graphene (RGO) and bare graphene oxide (GO) using dip-coating method. The surface morphology of the conductive cotton yarn coated with reduced graphene oxide was observed by Scanning Electron Microscope (SEM). Due to the strong electrostatic attractive forces, the negatively charged surface such as the eosin Y functionalized reduced graphene oxide or bare GO can be easily coated to the positively charged polyethyleneimine (PEI) treated cotton yarn. The maximum current for the conductive cotton yarn coated with eosin Y functionalized RGO and bare GO with 20 cycles repetition of (5D + R) process was found to be 793.8 μA and 3482.8 μA. Our results showed that the electrical conductivity of bare GO coated conductive cotton yarn increased by approximately four orders of magnitude with the increase in the dipping cycle of (5D+R) process.

  1. Protecting BOPP film from UV degradation with an atomic layer deposited titanium oxide surface coating

    Energy Technology Data Exchange (ETDEWEB)

    Lahtinen, Kimmo, E-mail: kimmo.lahtinen@lut.fi [ASTRaL, Lappeenranta University of Technology, Mikkeli (Finland); Maydannik, Philipp; Seppänen, Tarja; Cameron, David C. [ASTRaL, Lappeenranta University of Technology, Mikkeli (Finland); Johansson, Petri; Kotkamo, Sami; Kuusipalo, Jurkka [Paper Converting and Packaging Technology, Tampere University of Technology, Tampere (Finland)

    2013-10-01

    Titanium oxide layers were deposited onto a BOPP film by atomic layer deposition in order to prevent UV degradation of the film. The coatings were deposited in a low-temperature process at 80 °C by using tetrakis(dimethylamido)titanium and ozone as titanium and oxygen precursors, respectively. UV block characteristics of the coatings and their effect on the polymer were measured by using UV–vis and IR spectrometry, and differential scanning calorimetry. According to the results, the coatings provided a considerable decrease in the photodegradation of the BOPP film during UV exposure. IR spectra showed that during a 6-week UV exposure, a 67 nm titanium oxide coating was able to almost completely prevent the formation of photodegradation products in the film. The mechanical properties of the film were also protected by the coating, but as opposed to what the IR study suggested they were still somewhat compromised by the UV light. After a 6-week exposure, the tensile strength and elongation at break of the 67 nm titanium oxide coated film decreased to half of the values measured before the treatment. This should be compared to the complete degradation suffered by the uncoated base sheet already after only 4 weeks of treatment. The results show that nanometre scale inorganic films deposited by ALD show a promising performance as effective UV protection for BOPP substrates.

  2. Coating Optimization of Superparamagnetic Iron Oxide Nanoparticles for High T2 relaxivity

    OpenAIRE

    Tong, Sheng; Hou, Sijian; Zheng, Zhilan; Zhou, Jun; Bao, Gang

    2010-01-01

    We describe a new method for coating superparamagnetic iron oxide nanoparticles (SPIOs) and demonstrate that, by fine-tuning the core size and PEG coating of SPIOs, the T2 relaxivity per-particle can be increased by > 200 fold. With 14 nm core and PEG1000 coating, SPIOs can have T2 relaxivity of 385 s−1mM−1, which is among the highest of all SPIOs reported. In vivo tumor imaging results demonstrated the potential of the SPIOs for clinical applications.

  3. Effect of Li3PO4 coating of layered lithium-rich oxide on electrochemical performance

    Science.gov (United States)

    Chen, Dongrui; Zheng, Feng; Li, Liu; Chen, Min; Zhong, Xiaoxin; Li, Weishan; Lu, Li

    2017-02-01

    A novel composite of layered lithium-rich oxide, Li-Rich@Li3PO4, coated with Li3PO4 is synthesized through polydopamine template method. Physical characterizations reveal that Li-Rich@Li3PO4 is composed of nanoparticles of 100-200 nm that are coated with a uniform Li3PO4 layer of about 5 nm in thickness. Galvanostatic charge/discharge tests demonstrate enhanced cycling stability and largely increased rate capability of the material after Li3PO4 coating.

  4. Investigation of microstructural and physical characteristics of nano composite tin oxide-doped Al3+ in Zn2+ based composite coating by DAECD technique

    Science.gov (United States)

    Anawe, P. A. L.; Fayomi, O. S. I.; Popoola, A. P. I.

    In other to overcome the devastating deterioration of mild steel in service, Zn-based embedded Al/SnO2 composite coatings have been considered as reinforcing alternative replacements to the more traditional deposition for improved surface properties by using Dual Anode Electrolytic Co-deposition (DAECD) technique from chloride bath. The structural characterization of the starting materials and deposited coating are evaluated using scanning electron microscopy (SEM), equipped with energy dispersive X-ray spectroscopy (EDX) elemental analysis and atomic force microscope (AFM). The hardness behaviour, wear and intermetallic distribution was examined by diamond based microhardness tester, CETR reciprocating sliding test rig and X-ray diffractometer (XRD) respectively. The corrosion properties of the developed coating were examined in 3.5% NaCl. The microstructure of the deposited sample obtained at 7% SnO2, revealed fine-grains deposit of the Al/SnO2 on the mild steel surface. The results showed that the Al/SnO2 strengthening alloy plays a significant role in impelling the wear and corrosion behaviour of Zn-Al/SnO2 coatings in an aggressive saline environment. Interestingly Zn-30Al-7Sn-chloride showed the highest wear and improved corrosion resistance due to Al/SnO2 oxide passive film that forms during anodic polarization. This work established that co-deposition of mild steel with Al/SnO2 is auspicious in increasing the anti-wear and corrosion progression.

  5. Thermal reduction of graphene-oxide-coated cotton for oil and organic solvent removal

    Energy Technology Data Exchange (ETDEWEB)

    Hoai, Nguyen To, E-mail: hoaito@pvu.edu.vn; Sang, Nguyen Nhat; Hoang, Tran Dinh

    2017-02-15

    Highlights: • A new method for preparation of reduced-graphene-oxide (RGO) coated cotton is proposed. • The RGO-Cotton composites were carefully characterized using many modern techniques. • RGO-Cotton exhibited superhydrophobicity and superolephilicity. • RGO-Cotton sponges can absorb many types of oils and organic solvents and can be recycled. - Abstract: The reduced-graphene-oxide (RGO)-coated cotton sponge (RGO-Cot) was prepared by simply heating a graphene-oxide (GO)-coated cotton sponge, which was fabricated by dipping a commercial cotton sponge into a GO dispersion, under vacuum at 200 °C for 2 h. The thus prepared RGO-Cot sponges exhibited superhydrophobicity and superoleophilicity, with a water contact angle of 151°. These RGO-Cot sponges could be used for removal of many types of oils and organic solvents as they exhibit absorption capacities in the range of 22–45 times their weight and good absorption recyclability.

  6. Reversible wettability conversion of electrodeposited graphene oxide/titania nanocomposite coating: Investigation of surface structures

    Energy Technology Data Exchange (ETDEWEB)

    Naghdi, Samira; Jaleh, Babak, E-mail: bkjaleh@yahoo.com; Shahbazi, Nima

    2016-04-15

    Graphical abstract: - Highlights: • Electrophoretic deposition of Graphene oxide/titania on aluminum surface. • Superhydrophilicity of the GO/TiO{sub 2} coating (WCA ≈ 5°). • Wettability switching of the coating via thermal annealing to superhyrophobic. • The superhydrophobic coating was changed to superhydrophilic due to UV irradiance. • The GO/TiO{sub 2} coating has reversible wettability. - Abstract: Graphene oxide/titania (GO/TiO{sub 2}) nanocomposite have been successfully prepared by a simple method and deposited on the surface of aluminum (Al) by the electrophoretic deposition method. The effect of thermal annealing on wettability of GO/TiO{sub 2} coating has been investigated. According to the obtained results, the water contact angle (WCA) increased with an increase in annealing temperature which may be attributed to the regulation of coating from superhydrophilic (WCA ≈ 5°) to superhydrophobic (WCA ≈ 148°) via thermal annealing. Moreover, the superhydrophobic coating was changed to a superhydrophilic one by using ultraviolet irradiation and this effect was reversible by heat treatment.

  7. Influences of poly(ether urethane) introduction on poly(ethylene oxide) based polymer electrolyte for solvent-free dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Yanfang; Xiang Wanchun [CAS Key Laboratory of Photochemistry, Institute of Chemistry, BNLMS, Chinese Academy of Sciences, Beijing 100190 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Chen Shen; Fang Shibi; Zhou Xiaowen; Zhang Jingbo [CAS Key Laboratory of Photochemistry, Institute of Chemistry, BNLMS, Chinese Academy of Sciences, Beijing 100190 (China); Lin Yuan [CAS Key Laboratory of Photochemistry, Institute of Chemistry, BNLMS, Chinese Academy of Sciences, Beijing 100190 (China)], E-mail: linyuan@iccas.ac.cn

    2009-11-01

    A poly(ether urethane) (PEUR)/poly(ethylene oxide) (PEO)/SiO{sub 2} based nanocomposite polymer is prepared and employed in the construction of high efficiency all-solid-state dye-sensitized nanocrystalline solar cells. The introduction of low-molecular weight PEUR prepolymer into PEO electrolyte has greatly enhance the electrolyte performance by both improving the interfacial contact properties of electrode/electrolyte and decreasing the PEO crystallization, which were confirmed by XRD and SEM characteristics. The effects of polymer composition, nano SiO{sub 2} content on the ionic conductivity and I{sub 3}{sup -} ions diffusion of polymer-blend electrolyte are investigated. The optimized composition yields an energy conversion efficiency of 3.71% under irradiation by white light (100 mW cm{sup -2})

  8. Ionic conductivity and electrochemical properties of cross-linked poly[siloxane-g-oligo(ethylene oxide)] gel-type polymer electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Junkyoung [Advanced Materials Division, Korea Research Institute of Chemical Technology, P.O. Box 107, Daejeon 305-600 (Korea, Republic of); Department of Engineering Chemistry, Hanyang University, Seoul, 133-791 (Korea, Republic of); Kang, Yongku [Advanced Materials Division, Korea Research Institute of Chemical Technology, P.O. Box 107, Daejeon 305-600 (Korea, Republic of)]. E-mail: ykang@krict.re.kr; Suh, Dong Hack [Department of Engineering Chemistry, Hanyang University, Seoul, 133-791 (Korea, Republic of); Lee, Changjin [Advanced Materials Division, Korea Research Institute of Chemical Technology, P.O. Box 107, Daejeon 305-600 (Korea, Republic of)

    2004-11-30

    Poly[siloxane-g-oligo(ethylene oxide)] tetraacrylate cross-linker was synthesized, and the gel polymer electrolytes (GPE) was prepared by thermal curing using them. Increase of conductivity with decrease of T{sub g} was observed as the content of liquid electrolyte increased. Maximum conductivity was found to be 3.92 x 10{sup -3} S/cm at 30 deg. C with a 70 wt.% 1 M LiPF{sub 6} in EC/PC (1:1). The electrochemical stability of the resulting gel polymer electrolyte could be extended to up to 4.4 V. Applicability of the resulting polymer electrolyte for lithium battery was tested by Li vertical bar GPE vertical bar LiCoO{sub 2} cell.

  9. Ionic conductivity and electrochemical properties of cross-linked poly[siloxane-g-oligo(ethylene oxide)] gel-type polymer electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Junkyoung Lee [Korea Research Institute of Chemical Technology, Daejeon (Korea). Advanced Materials Division; Hanyang University, Seoul (Korea). Department of Engineering Chemistry; Yongku Kang; Changjin Lee [Korea Research Institute of Chemical Technology, Daejeon (Korea). Advanced Materials Division; Dong Hack Suh [Hanyang University, Seoul (Korea). Department of Engineering Chemistry

    2004-11-30

    Poly[siloxane-g-oligo(ethylene oxide)] tetraacrylate cross-linker was synthesized, and the gel polymer electrolytes (GPE) was prepared by thermal curing using them. Increase of conductivity with decrease of T{sub g} was observed as the content of liquid electrolyte increased. Maximum conductivity was found to be 3.92 x 10{sup -3} S/cm at 30 {sup o}C with a 70 wt.% 1 M LiPF{sub 6} in EC/PC (1:1). The electrochemical stability of the resulting gel polymer electrolyte could be extended to up to 4.4 V. Applicability of the resulting polymer electrolyte for lithium battery was tested by Li/GPE/LiCoO{sub 2} cell. (author)

  10. Application of Electro-Oxidation Method for Treatment of Dye Textile Wastewater Using Stainless Steel Electrode: Study of Electrolyte Concentration Effect to Color Removal

    Directory of Open Access Journals (Sweden)

    Jumardin Rua

    2017-09-01

    Full Text Available The increasing number of textile industries has created a new problem of environmental pollution from waste produced. Entering of concentrated wastewater that containing of complex organic compounds to agricultural land and rivers has caused loss to humans or the environment. Treatment of dye textile wastewater by electro-oxidation method using stainless steel electrode has been done. This research consists of several stages: analysis of electrode composition with SEM-EDX, electrolysis of wastewater at variation of electrolyte concentration and analysis of electrolyte concentration effect to color removal percentage of wastewater. The result shows that the electrode composition consisted of iron, chromium, nickel and silica with the main composition of iron in the amount of 72.2%. After electrolysis on variations of electrolyte concentration and analysis of color removal percentage of wastewater, obtained that the largest of color removal percentage on the use of electrolyte concentration of 3% in the amount of 98.81%

  11. Electrochemical oxidation of wastewater containing aromatic amines using a flow electrolytic reactor

    OpenAIRE

    de Moraes, PB; Bertazzoli, R.; Bidoia, ED

    2013-01-01

    Aromatic amines are environmental pollutants and represent one of the most important classes of industrial and natural chemicals. Some types of complex effluents containing these chemical species, mainly those originated from chemicals plants are not fully efficiently treated by conventional processes. In this work, the use of electrochemical technology through an electrolytic pilot scale flow reactor is considered for treatment of wastewater of a chemical industry manufacturer of antioxidant...

  12. Adhesion property and high-temperature oxidation behavior of Cr-coated Zircaloy-4 cladding tube prepared by 3D laser coating

    Science.gov (United States)

    Kim, Hyun-Gil; Kim, Il-Hyun; Jung, Yang-Il; Park, Dong-Jun; Park, Jeong-Yong; Koo, Yang-Hyun

    2015-10-01

    A 3D laser coating technology using Cr powder was developed for Zr-based alloys considering parameters such as: the laser beam power, inert gas flow, cooling of Zr-based alloys, and Cr powder control. This technology was then applied to Zr cladding tube samples to study the effect of Cr coating on the high-temperature oxidation of Zr-based alloys in a steam environment of 1200 °C for 2000s. It was revealed that the oxide layer thickness formed on the Cr-coated tube surface was about 25-times lower than that formed on a Zircaloy-4 tube surface. In addition, both the ring compression and the tensile tests were performed to evaluate the adhesion properties of the Cr-coated sample. Although some cracks were formed on the Cr-coated layer, the Cr-coated layer had not peeled off after the two tests.

  13. Rational coating of Li7P3S11 solid electrolyte on MoS2 electrode for all-solid-state lithium ion batteries

    Science.gov (United States)

    Xu, R. C.; Wang, X. L.; Zhang, S. Z.; Xia, Y.; Xia, X. H.; Wu, J. B.; Tu, J. P.

    2018-01-01

    Large interfacial resistance between electrode and electrolyte limits the development of high-performance all-solid-state batteries. Herein we report a uniform coating of Li7P3S11 solid electrolyte on MoS2 to form a MoS2/Li7P3S11 composite electrode for all-solid-state lithium ion batteries. The as-synthesized Li7P3S11 processes a high ionic of 2.0 mS cm-1 at room temperature. Due to homogeneous union and reduced interfacial resistance, the assembled all-solid-state batteries with the MoS2/Li7P3S11 composite electrode exhibit higher reversible capacity of 547.1 mAh g-1 at 0.1 C and better cycling stability than the counterpart based on untreated MoS2. Our study provides a new reference for design/fabrication of advanced electrode materials for high-performance all-solid-state batteries.

  14. Studies on broad spectrum corrosion resistant oxide coatings

    Indian Academy of Sciences (India)

    Unknown

    are quartz, soda ash, hydrated borax, boric acid, titania, rutile, tri-sodium phosphate, potassium nitrate, lithium carbonate, barium carbonate, di-ammonium hydrogen phosphate, ammonium di-hydrogen phosphate, etc. The coating materials are prepared by melting the batch at ~ 1300°C and the average yield of frit is ~ 80% ...

  15. Wettability and corrosion of alumina embedded nanocomposite MAO coating on nanocrystalline AZ31B magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gheytani, M.; Aliofkhazraei, M., E-mail: maliofkh@gmail.com; Bagheri, H.R.; Masiha, H.R.; Rouhaghdam, A. Sabour

    2015-11-15

    In this paper, micro- and nanocrystalline AZ31B magnesium alloy were coated by micro-arc oxidation method. In order to fabricate nanocrystalline surface layer, surface mechanical attrition treatment was performed and nano-grains with average size of 5–10 nm were formed on the surface of the samples. Coating process was carried out at different conditions including two coating times and two types of electrolyte. Alumina nanoparticles were utilized as suspension in electrolyte to form nanocomposite coatings by micro-arc oxidation method. Potentiodynamic polarization, percentage of porosity, and wettability tests were performed to study various characteristics of the coated samples. The results of scanning electron microscope imply that samples coated in silicate-based electrolyte involve much lower surface porosity (∼25%). Besides, the results of wettability test indicated that the maximum surface tension with deionized water is for nanocrystalline sample. In this regard, the sample coated in silicate-based suspension was 4 times more hydrophilic than the microcrystalline sample. - Highlights: • MAO in phosphate electrolyte needs higher energy as compared to silicate electrolyte. • Less porosity and finer grain size on free surface of the silicate-based coatings. • Observed porosity from top surface of coating shows the effect of the final MAO sparks. • SMAT affects surface roughness and accelerates growth kinetics.

  16. Oxide-Nanoparticle Containing Coatings for High Temperature Alloys

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-04-01

    This factsheet describes a study whose objective is to examine the feasibility of using Electromagnetic Stirring (EMS) techniques in dispersing the oxide nanoparticles uniformly within the liquid steel.

  17. Chitosan-zinc oxide nanocomposite coatings for the prevention of marine biofouling.

    Science.gov (United States)

    Al-Naamani, Laila; Dobretsov, Sergey; Dutta, Joydeep; Burgess, J Grant

    2017-02-01

    Marine biofouling is a worldwide problem affecting maritime industries. Global concerns about the high toxicity of antifouling paints have highlighted the need to develop less toxic antifouling coatings. Chitosan is a natural polymer with antimicrobial, antifungal and antialgal properties that is obtained from partial deacetylation of crustacean waste. In the present study, nanocomposite chitosan-zinc oxide (chitosan-ZnO) nanoparticle hybrid coatings were developed and their antifouling activity was tested. Chitosan-ZnO nanoparticle coatings showed anti-diatom activity against Navicula sp. and antibacterial activity against the marine bacterium Pseudoalteromonas nigrifaciens. Additional antifouling properties of the coatings were investigated in a mesocosm study using tanks containing natural sea water under controlled laboratory conditions. Each week for four weeks, biofilm was removed and analysed by flow cytometry to estimate total bacterial densities on the coated substrates. Chitosan-ZnO hybrid coatings led to better inhibition of bacterial growth in comparison to chitosan coatings alone, as determined by flow cytometry. This study demonstrates the antifouling potential of chitosan-ZnO nanocomposite hybrid coatings, which can be used for the prevention of biofouling. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Long period gratings coated with hafnium oxide by plasma-enhanced atomic layer deposition for refractive index measurements.

    Science.gov (United States)

    Melo, Luis; Burton, Geoff; Kubik, Philip; Wild, Peter

    2016-04-04

    Long period gratings (LPGs) are coated with hafnium oxide using plasma-enhanced atomic layer deposition (PEALD) to increase the sensitivity of these devices to the refractive index of the surrounding medium. PEALD allows deposition at low temperatures which reduces thermal degradation of UV-written LPGs. Depositions targeting three different coating thicknesses are investigated: 30 nm, 50 nm and 70 nm. Coating thickness measurements taken by scanning electron microscopy of the optical fibers confirm deposition of uniform coatings. The performance of the coated LPGs shows that deposition of hafnium oxide on LPGs induces two-step transition behavior of the cladding modes.

  19. Preparation, characterization and dynamical mechanical properties of dextran-coated iron oxide nanoparticles (DIONPs).

    Science.gov (United States)

    Can, Hatice Kaplan; Kavlak, Serap; ParviziKhosroshahi, Shahed; Güner, Ali

    2017-04-20

    Dextran-coated iron oxide nanoparticles (DIONPs) with appropriate surface chemistry exhibit many interesting properties that can be exploited in a variety of biomedical applications such as magnetic resonance imaging (MRI) contrast enhancement, tissue repair, hyperthermia, drug delivery and in cell separation. This paper reports the experimental detail for preparation, characterization and investigation of thermal and dynamical mechanical characteristics of the dextran-coated Fe3O4 magnetic nanoparticles. In our work, DIONPs were prepared in a 1:2 ratio of Fe(II) and Fe(III) salt in the HCl solution with NaOH at given temperature. The obtained dextran-coated iron-oxide nanoparticles structure-property correlation was characterized by spectroscopic methods; attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and XRD. Coating dextran on the iron-oxide proof of important peaks can be seen from the ATR-FTIR. Dramatic crystallinity increment can be observed from the XRD pattern of the iron-oxide dextran nanoparticles. The thermal analysis was examined by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). Dynamical mechanical properties of dextran nanoparticles were analysed by dynamic mechanical analysis (DMA). Thermal stability of the iron oxide dextran nanoparticles is higher than that of the dextran.

  20. Doxorubicin loaded PVA coated iron oxide nanoparticles for targeted drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Kayal, S. [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Ramanujan, R.V., E-mail: ramanujan@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2010-04-06

    Magnetic drug targeting is a drug delivery system that can be used in locoregional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by coprecipitation of iron oxide followed by coating with polyvinyl alcohol (PVA). Characterization was carried out using X-ray diffraction, TEM, TGA, FTIR and VSM techniques. The magnetic core of the carriers was magnetite (Fe{sub 3}O{sub 4}), with average size of 10 nm. The room temperature VSM measurements showed that magnetic particles were superparamagnetic. The amount of PVA bound to the iron oxide nanoparticles were estimated by thermogravimetric analysis (TGA) and the attachment of PVA to the iron oxide nanoparticles was confirmed by FTIR analysis. Doxorubicin (DOX) drug loading and release profiles of PVA coated iron oxide nanoparticles showed that up to 45% of adsorbed drug was released in 80 h, the drug release followed the Fickian diffusion-controlled process. The binding of DOX to the PVA was confirmed by FTIR analysis. The present findings show that DOX loaded PVA coated iron oxide nanoparticles are promising for magnetically targeted drug delivery.

  1. W-containing oxide layers obtained on aluminum and titanium by PEO as catalysts in thiophene oxidation

    Science.gov (United States)

    Rudnev, V. S.; Lukiyanchuk, I. V.; Vasilyeva, M. S.; Morozova, V. P.; Zelikman, V. M.; Tarkhanova, I. G.

    2017-11-01

    W-containing oxide layers fabricated on titanium and aluminum alloys by Plasma electrolytic oxidation (PEO) have been tested in the reaction of the peroxide oxidation of thiophene. Samples with two types of coatings have been investigated. Coatings I contained tungsten oxide in the matrix and on the surface of amorphous silica-titania or silica-alumina layers, while coatings II comprised crystalline WO3 and/or Al2(WO4)3. Aluminum-supported catalyst containing a smallest amount of transition metals in the form of tungsten oxides and manganese oxides in low oxidation levels showed high activity and stability.

  2. Vacuum-arc chromium-based coatings for protection of zirconium alloys from the high-temperature oxidation in air

    Energy Technology Data Exchange (ETDEWEB)

    Kuprin, A.S.; Belous, V.A.; Voyevodin, V.N., E-mail: voyev@kipt.kharkov.ua; Bryk, V.V.; Vasilenko, R.L.; Ovcharenko, V.D.; Reshetnyak, E.N.; Tolmachova, G.N.; V' yugov, P.N.

    2015-10-15

    Multilayer Cr–Zr/Cr/Cr–N coatings for protection of zirconium alloys from the high-temperature oxidation in air have been obtained by the vacuum-arc evaporation technique with application of filters for plasma cleaning from macroparticles. The effect of the coatings on the corrosion resistance of zirconium alloys at test temperatures between 660 and 1100 °C for 3600 s has been investigated. The thickness, structure, phase composition, mechanical properties of the coatings and oxide layers before and after oxidation tests were examined by scanning electron microscopy, X-ray diffraction analysis and nanoindentation technique. It is shown that the hard multilayer coating effectively protects zirconium from the oxidation in air for 1 h at test temperatures. As a result of the oxidation in the coating the CrO and Cr{sub 2}O{sub 3} oxides are formed which reduce the oxygen penetration through the coating. At maximum test temperature of 1100 °C the oxide layer thickness in the coating is about 5 μm. The tube shape remains unchanged independent of alloy type. It has been found that uncoated zirconium oxidizes rapidly throughout the temperature range under study. At 1100 °C a porous monoclinic ZrO{sub 2} oxide layer of ≥120 μm is formed that leads to the deformation of the samples, cracking and spalling of the oxide layer.

  3. UV protective zinc oxide coating for biaxially oriented polypropylene packaging film by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lahtinen, Kimmo, E-mail: kimmo.lahtinen@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Kääriäinen, Tommi, E-mail: tommi.kaariainen@colorado.edu [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Johansson, Petri, E-mail: petri.johansson@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Kotkamo, Sami, E-mail: sami.kotkamo@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Maydannik, Philipp, E-mail: philipp.maydannik@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Seppänen, Tarja, E-mail: tarja.seppanen@lut.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Kuusipalo, Jurkka, E-mail: jurkka.kuusipalo@tut.fi [Paper Converting and Packaging Technology, Tampere University of Technology, P.O.Box 589, FI-33101 Tampere (Finland); Cameron, David C., E-mail: david.cameron@miktech.fi [ASTRaL, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland)

    2014-11-03

    Biaxially oriented polypropylene (BOPP) packaging film was coated with zinc oxide (ZnO) coatings by atomic layer deposition (ALD) in order to protect the film from UV degradation. The coatings were made at a process temperature of 100 °C using diethylzinc and water as zinc and oxygen precursors, respectively. The UV protective properties of the coatings were tested by using UV–VIS and infrared spectrometry, differential scanning calorimetry (DSC) and a mechanical strength tester, which characterised the tensile and elastic properties of the film. The results obtained with 36 and 67 nm ZnO coatings showed that the ZnO UV protective layer is able to provide a significant decrease in photodegradation of the BOPP film under UV exposure. While the uncoated BOPP film suffered a complete degradation after a 4-week UV exposure, the 67 nm ZnO coated BOPP film was able to preserve half of its original tensile strength and 1/3 of its elongation at break after a 6-week exposure period. The infrared analysis and DSC measurements further proved the UV protection of the ZnO coatings. The results show that a nanometre scale ZnO coating deposited by ALD is a promising option when a transparent UV protection layer is sought for polymer substrates. - Highlights: • Atomic layer deposited zinc oxide coatings were used as UV protection layers. • Biaxially oriented polypropylene (BOPP) film was well protected against UV light. • Formation of UV degradation products in BOPP was significantly reduced. • Mechanical properties of the UV exposed BOPP film were significantly improved.

  4. The promising application of graphene oxide as coating materials in orthopedic implants: preparation, characterization and cell behavior.

    Science.gov (United States)

    Zhao, Changhong; Lu, Xiuzhen; Zanden, Carl; Liu, Johan

    2015-02-10

    To investigate the potential application of graphene oxide (GO) in bone repair, this study is focused on the preparation, characterization and cell behavior of graphene oxide coatings on quartz substrata. GO coatings were prepared on the substrata using a modified dip-coating procedure. Atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman spectroscopy results demonstrated that the as-prepared coatings in this study were homogeneous and had an average thickness of ~67 nm. The rapid formation of a hydroxyapatite (HA) layer in the simulated body fluid (SBF) on GO coated substrata at day 14, as proved by SEM and x-ray diffraction (XRD), strongly indicated the bioactivity of coated substrata. In addition, MC3T3-E1 cells were cultured on the coated substrata to evaluate cellular activities. Compared with the non-coated substrata and tissue culture plates, no significant difference was observed on the coated substrata in terms of cytotoxicity, viability, proliferation and apoptosis. However, interestingly, higher levels of alkaline phosphatase (ALP) activity and osteocalcin (OC) secretion were observed on the coated substrata, indicating that GO coatings enhanced cell differentiation compared with non-coated substrata and tissue culture plates. This study suggests that GO coatings had excellent biocompatibility and more importantly promoted MC3T3-E1 cell differentiation and might be a good candidate as a coating material for orthopedic implants.

  5. Improving pH sensitivity by field-induced charge regulation in flexible biopolymer electrolyte gated oxide transistors

    Science.gov (United States)

    Liu, Ning; Gan, Lu; Liu, Yu; Gui, Weijun; Li, Wei; Zhang, Xiaohang

    2017-10-01

    Electrical manipulation of charged ions in electrolyte-gated transistors is crucial for enhancing the electric-double-layer (EDL) gating effect, thereby improving their sensing abilities. Here, indium-zinc-oxide (IZO) based thin-film-transistors (TFTs) are fabricated on flexible plastic substrate. Acid doped chitosan-based biopolymer electrolyte is used as the gate dielectric, exhibiting an extremely high EDL capacitance. By regulating the dynamic EDL charging process with special gate potential profiles, the EDL gating effect of the chitosan-gated TFT is enhanced, and then resulting in higher pH sensitivities. An extremely high sensitivity of ∼57.8 mV/pH close to Nernst limit is achieved when the gate bias of the TFT sensor sweeps at a rate of 10 mV/s. Additionally, an enhanced sensitivity of 2630% in terms of current variation with pH range from 11 to 3 is realized when the device is operated in the ion depletion mode with a negative gate bias of -0.7 V. Robust ionic modulation is demonstrated in such chitosan-gated sensors. Efficiently driving the charged ions in the chitosan-gated IZO-TFT provides a new route for ultrasensitive, low voltage, and low-cost biochemical sensing technologies.

  6. Bio-sorbable, liquid electrolyte gated thin-film transistor based on a solution-processed zinc oxide layer.

    Science.gov (United States)

    Singh, Mandeep; Palazzo, Gerardo; Romanazzi, Giuseppe; Suranna, Gian Paolo; Ditaranto, Nicoletta; Di Franco, Cinzia; Santacroce, Maria Vittoria; Mulla, Mohammad Yusuf; Magliulo, Maria; Manoli, Kyriaki; Torsi, Luisa

    2014-01-01

    Among the metal oxide semiconductors, ZnO has been widely investigated as a channel material in thin-film transistors (TFTs) due to its excellent electrical properties, optical transparency and simple fabrication via solution-processed techniques. Herein, we report a solution-processable ZnO-based thin-film transistor gated through a liquid electrolyte with an ionic strength comparable to that of a physiological fluid. The surface morphology and chemical composition of the ZnO films upon exposure to water and phosphate-buffered saline (PBS) are discussed in terms of the operation stability and electrical performance of the ZnO TFT devices. The improved device characteristics upon exposure to PBS are associated with the enhancement of the oxygen vacancies in the ZnO lattice due to Na(+) doping. Moreover, the dissolution kinetics of the ZnO thin film in a liquid electrolyte opens the possible applicability of these devices as an active element in "transient" implantable systems.

  7. Electrolyte salts for nonaqueous electrolytes

    Science.gov (United States)

    Amine, Khalil; Zhang, Zhengcheng; Chen, Zonghai

    2012-10-09

    Metal complex salts may be used in lithium ion batteries. Such metal complex salts not only perform as an electrolyte salt in a lithium ion batteries with high solubility and conductivity, but also can act as redox shuttles that provide overcharge protection of individual cells in a battery pack and/or as electrolyte additives to provide other mechanisms to provide overcharge protection to lithium ion batteries. The metal complex salts have at least one aromatic ring. The aromatic moiety may be reversibly oxidized/reduced at a potential slightly higher than the working potential of the positive electrode in the lithium ion battery. The metal complex salts may also be known as overcharge protection salts.

  8. Performance of Electrolyte Supported Solid Oxide Fuel Cells with STN Anodes

    DEFF Research Database (Denmark)

    Veltzé, Sune; Reddy Sudireddy, Bhaskar; Jørgensen, Peter Stanley

    2013-01-01

    high fuel utilization and redox cycling have been performed to identify the performance limiting parameters in this new type of full ceramic SOFCs. Measured performances and stability have been further tentatively linked to modifications of the nano-sized infiltrates within the anode.......In order to replace the state of the art Ni-cermet as SOFC anode, electrolyte supported cells comprising CGO/Ni infiltrated Nbdoped SrTiO3 anodes, and LSM/YSZ cathodes have been developed and tested as single 5 x 5 cm2 cells. The initial performance reached 0.4 W/cm2 at 850 C. Further tests under...

  9. Antibacterial properties and cytocompatibility of tantalum oxide coatings with different silver content

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Heng-Li [School of Dentistry, China Medical University, Taichung 404, Taiwan (China); Chang, Yin-Yu, E-mail: yinyu@mail2000.com.tw; Chen, Hung-Jui; Chou, Yu-Kai [Department of Mechanical and Computer-Aided Engineering, National Formosa University, Yunlin 632, Taiwan (China); Lai, Chih-Ho [School of Medicine, China Medical University, Taichung 404, Taiwan (China); Chen, Michael Y. C. [Division of Oral and Maxillofacial Surgery, China Medical University Hospital, Taichung 404, Taiwan (China)

    2014-03-15

    Tantalum (Ta) oxides and their coatings have been proved to increase their applications in the biomedical fields by improving osseointegration and wear resistance. In this study, Ta oxide coatings containing different proportions of Ag are deposited on SS304 materials. A twin-gun magnetron sputtering system is used to deposit the tantalum oxide-Ag coating. In this study, Staphylococcus aureus, which exhibits physiological commensalism on the human skin, nares, and mucosal and oral areas, is chosen as the model for in vitro antibacterial analyses via a fluorescence staining method using Syto9. The cytocompatibility and adhesive morphology of human skin fibroblast cells (CCD-966SK) on the coatings are also determined by using the microculture tetrazolium assay. This study shows that Ta{sub 2}O{sub 5} and Ta{sub 2}O{sub 5}-Ag coatings with 12.5 at. % of Ag exhibit improved antibacterial effects against S. aureus and have good skin fibroblast cell cellular biocompatibility.

  10. Oxidation study of coated Crofer 22 APU steel in dry oxygen

    DEFF Research Database (Denmark)

    Molin, Sebastian; Chen, Ming; Hendriksen, Peter Vang

    2014-01-01

    The effect of a dual layer coating composed of a layer of a Co3O4 and a layer of a La0.85Sr0.15MnO3/Co3O4 mixture on the high temperature corrosion of the Crofer 22 APU alloy is reported. Oxidation experiments were performed in dry oxygen at three temperatures: 800 °C, 850 °C and 900 °C for periods...... up to 1000 h. Additionally at 850 °C a 5000 h long oxidation test was performed to evaluate longer term suitability of the proposed coating. Corrosion kinetics were evaluated by measuring mass gain during oxidation. The corrosion kinetics for the coated samples are analyzed in terms of a parabolic...... rate law. Microstructural features were investigated by scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffractometry. The coating is effective in reducing the corrosion rate and in ensuring long lifetime of coated alloys. The calculated activation energy for the corrosion...

  11. Microhardness and wear resistance of PEO-coated 5754 aluminum alloy

    Science.gov (United States)

    Vyaliy, I. E.; Egorkin, V. S.; Sinebryukhov, S. L.; Minaev, A. N.; Gnedenkov, S. V.

    2017-09-01

    We present results of the study aimed at assessing the effect of duty cycle (D) during plasma electrolytic oxidation (PEO) on protective properties of the coatings produced on 5754 aluminum alloy. It is shown that increasing the duty cycle of a microsecond current pulses leads to increased hardness and reduced abrasive wear of the PEO-layers, improving mechanical properties. The obtained data allowed confirming, that increasing the amount of energy consumed for coating growth leads to the formation of thicker PEO-layers with improved tribological properties. The effect of duty cycle during plasma electrolytic oxidation on protective properties of the produced coatings was assessed.

  12. Y-doped BaZrO3 as a chemically stable electrolyte for proton-conducting solid oxide electrolysis cells (SOECs)

    KAUST Repository

    Bi, Lei

    2015-01-01

    A proton-conducting solid oxide electrolysis cell using an Y-doped BaZrO3 electrolyte film, which has been demonstrated to be chemically stable, was successfully fabricated for the first time and showed a promising electrolysis performance.

  13. In vitro toxicity assessment of chitosan oligosaccharide coated iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Sudeep Shukla

    2015-01-01

    Full Text Available Iron oxide nanoparticles (INPs have potential biological, biomedical and environmental applications. These applications require surface modification of the iron oxide nanoparticles, which makes it non-toxic, biocompatible, stable and non-agglomerative in natural and biological surroundings. In the present study, iron oxide nanoparticles (INPs and chitosan oligosaccharide coated iron oxide nanoparticles (CSO-INPs were synthesized to evaluate the effect of surface coating on the stability and toxicity of nanoparticles. Comparative in vitro cytotoxicity of nanoparticles was evaluated in HeLa (human cervix carcinoma, A549 (human lung carcinoma and Hek293 (human embryonic kidney cells by using 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay along with flow cytometry study for cell viability, membrane integrity, mitochondrial membrane potential (MMP and reactive oxygen species (ROS production. Morphological alteration in nanoparticles treated cells was analyzed by Acridine orange/ethidium bromide double staining and electron microscopy. Synthesized nanoparticles were found to be spherical in shape, well dispersed and stable at various pH values, making them suitable for biomedical and environmental applications. The present study also indicates that the chitosan oligosaccharide coating on iron oxide nanoparticles results in the decrease in cellular damage and moderate ROS production, thereby, significantly decreasing the cytotoxic impact of bare iron oxide nanoparticles.

  14. Electrophoretic deposition and electrochemical behavior of novel graphene oxide-hyaluronic acid-hydroxyapatite nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ming; Liu, Qian; Jia, Zhaojun; Xu, Xuchen; Shi, Yuying [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Cheng, Yan, E-mail: chengyan@pku.edu.cn [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zheng, Yufeng [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Xi, Tingfei [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Wei, Shicheng [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Oral and Maxillofacial Surgery, School of Stomatology, Peking University, Beijing 100081 (China)

    2013-11-01

    Novel ternary graphene oxide-hyaluronic acid-hydroxyapatite (GO-HY-HA) nanocomposite coatings were prepared on Ti substrate using anodic electrophoretic deposition (EPD). Hyaluronic acid was employed as charging additive and dispersion agent during EPD. The kinetics and mechanism of the deposition, and the microstructure of the coated samples were investigated using scanning electron microscopy, X-ray diffraction, Raman spectrum, thermo-gravimetric analysis, and microscopic Fourier transform infrared analysis. The results showed that the addition of GO sheets into the HY-HA suspensions could increase the deposition rate and inhibit cracks creation and propagation in the coatings. The corrosion resistant of the resulting samples were evaluated using potentiodynamic polarization method in simulated body fluid, and the GO-HY-HA coatings could effectively improve the anti-corrosion property of the Ti substrate.

  15. 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.

  16. Influence of Surface Finishing on the Oxidation Behaviour of VPS MCrAlY Coatings

    Science.gov (United States)

    Fossati, Alessio; di Ferdinando, Martina; Bardi, Ugo; Scrivani, Andrea; Giolli, Carlo

    2012-03-01

    CoNiCrAlY coatings were produced by means of the vacuum plasma spraying (VPS) process onto CMSX-4 single crystal nickel superalloy disk substrates. As-sprayed samples were annealed at high temperatures in low vacuum. Three kinds of finishing processes were carried out, producing three types of samples: as-sprayed, mechanically smoothed by grinding, ground and PVD coated by using aluminum targets in an oxygen atmosphere. Samples were tested under isothermal conditions, in air, at 1000 °C, and up to 5000 h. Morphological, microstructural and compositional analyses were performed on the coated samples in order to assess the high temperature oxidation behavior provided by the three different surface finishing processes. Several differences were observed: grinding operations decrease the oxidation resistance, whereas the PVD process can increase the performances over longer time with respect of the as-sprayed samples.

  17. The role of ionic electrolytes on capacitive performance of ZnO-reduced graphene oxide nanohybrids with thermally tunable morphologies.

    Science.gov (United States)

    Prakash, Anand; Bahadur, D

    2014-02-12

    In the present work, the role of the reaction temperatures on the morphologies of zinc oxide-reduced graphene oxide (ZnO-RGO) nanohybrids and their supercapacitive performance in two different aqueous electrolytes (1.0 M KCl and Na2SO4) were investigated. The ZnO-RGO nanohybrids were synthesized at two different temperatures (ca. 95 and 145 °C) by solvothermal method and labeled as ZnO-RGO-1 and ZnO-RGO-2, respectively. The structure and composition of ZnO-RGO nanohybrids were confirmed by means of X-ray diffraction, electron microscopes (scanning and transmission), X-ray photoelectron, photoluminescence, and Raman spectroscopy. These results show that the temperature allows a good control on loading and morphology of ZnO nanoassemblies in ZnO-RGO nanohybrids and at elevated temperature of 145 °C, ZnO nanoassemblies break and get completely embedded into RGO matrices. The electrochemical performance of ZnO-RGO nanohybrids was examined by cyclic voltammograms (CVs), galvanostatic charge-discharge (chronopotentiometry) and electrochemical impedance spectroscopy (EIS) in 1.0 M KCl and Na2SO4 aqueous electrolytes respectively. Combining the EIS and zeta potential behavior, a direct link between the charge transfer resistance and electrical double layers is established which is responsible for excellent capacitive performance of ZnO-RGO-2. The ZnO-RGO-2 displays high specific capacitance (107.9 F/g, scan rate = 50 mVs(-1)) in 1.0 M KCl and exhibits merely 4.2% decay in specific capacitance values over 200 cycles.

  18. Hydrolysis of and oxide solubilities in melts related to electrolytic magnesium production

    Energy Technology Data Exchange (ETDEWEB)

    Vindstad, J.E.

    1996-12-31

    It takes about 13-14 kWh to produce 1 kg magnesium metal by today`s technology, although the thermodynamic energy required is only about 6.8 kWh/kg (at 700{sup o}C). The specific energy consumption of a magnesium electrolysis cell is inversely proportional to the current efficiency, which is affected by the presence of impurities in the electrolyte. A high current efficiency requires that the cathode is well wetted by the liquid magnesium and that the latter is well wetted by the electrolyte. If the metal does not wet the cathode, and the melt not the metal, then the cathodic overvoltage and thus also the energy consumption increases. The presence of water has a detrimental effect on the electrolysis because an MgO film forms on the metal when the water reacts with the magnesium produced, thus interfering with the wetting of the cathode by the metal. It follows that a thorough knowledge of the processes going on in the hydrolysis is important for improving the energy efficiency of the magnesium production. The first part of this doctoral thesis discusses experiments on the equilibria established during hydrolysis of pure liquid MgCl{sub 2} and of a liquid NaCl-MgCl{sub 2} mixture at 730 and 675 {sup o}C. The second part deals with the effect of fluoride on the solubility of MgO in MgCl{sub 2}-containing melts. 67 refs., 35 figs., 12 tabs.

  19. Iron oxide coating films in soda-lime glass by triboadhesion

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, J. O.; Arjona, M. J. [Boulevard Bahia s/n esq. Ignacio Comonfort, Chetumal (Mexico); Rodriguez-Lelis, J. M. [Interior Internado Palmira s/n, Cuernavaca, Morelos (Mexico)

    2009-04-15

    In the triboadhesion process the coating material is passed through a rotating cotton mop and the substrate to be coated. The cotton mop rotates at high velocity and exerts pressure on the surface of the substrate. The combined effect of pressure and velocity of the coating mop on the substrate increases its temperature close to the melting point, allowing deposition and diffusion of the coating material within the substrate. After it is deposited, its particles are embedded within the base material forming a thin film composite. The amount of the coating material deposited on the substrate has its maximum at the surface and then decreases as a function of the local temperature within the base material. Bearing this in mind, in the present work, triboadhesion is employed to deposit iron oxide in a substrate of soda-lime glass, with the purpose of determining the feasibility of using this technique for solar control coatings. It was found, through electronic scan microscopy, that a composite material film is formed following the coating direction. Reflectance and transmittance tests were carried out on the glass samples. A 20% difference was found in the visible spectral region (VIS), and a reduction between 10 and 20% in the Near Infrared Region (NIR). These results showed that the triboadhesion is a promising technique for the application of thin films for solar control or solar cells

  20. Protein Corona Composition of Superparamagnetic Iron Oxide Nanoparticles with Various Physico-Chemical Properties and Coatings

    Science.gov (United States)

    Sakulkhu, Usawadee; Mahmoudi, Morteza; Maurizi, Lionel; Salaklang, Jatuporn; Hofmann, Heinrich

    2014-05-01

    Because of their biocompatibility and unique magnetic properties, superparamagnetic iron oxide nanoparticles NPs (SPIONs) are recognized as some of the most prominent agents for theranostic applications. Thus, understanding the interaction of SPIONs with biological systems is important for their safe design and efficient applications. In this study, SPIONs were coated with 2 different polymers: polyvinyl alcohol polymer (PVA) and dextran. The obtained NPs with different surface charges (positive, neutral, and negative) were used as a model study of the effect of surface charges and surface polymer materials on protein adsorption using a magnetic separator. We found that the PVA-coated SPIONs with negative and neutral surface charge adsorbed more serum proteins than the dextran-coated SPIONs, which resulted in higher blood circulation time for PVA-coated NPs than the dextran-coated ones. Highly abundant proteins such as serum albumin, serotransferrin, prothrombin, alpha-fetoprotein, and kininogen-1 were commonly found on both PVA- and dextran-coated SPIONs. By increasing the ionic strength, soft- and hard-corona proteins were observed on 3 types of PVA-SPIONs. However, the tightly bound proteins were observed only on negatively charged PVA-coated SPIONs after the strong protein elution.

  1. An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid

    Science.gov (United States)

    Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO3)2•6H2O functionalization of zeolite. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The adsorption capacity of the adsorbents at 21...

  2. Reduced Graphene Oxide Coating with Anticorrosion and Electrochemical Property-Enhancing Effects Applied in Hydrogen Storage System.

    Science.gov (United States)

    Du, Yi; Li, Na; Zhang, Tong-Ling; Feng, Qing-Ping; Du, Qian; Wu, Xing-Hua; Huang, Gui-Wen

    2017-08-30

    Low-capacity retention is the most prominent problem of the magnesium nickel alloy (Mg2Ni), which prevents it from being commercially applied. Here, we propose a practical method for enhancing the cycle stability of the Mg2Ni alloy. Reduced graphene oxide (rGO) possesses a graphene-based structure, which could provide high-quality barriers that block the hydroxyl in the aqueous electrolyte; it also possesses good hydrophilicity. rGO has been successfully coated on the amorphous-structured Mg2Ni alloy via electrostatic assembly to form the rGO-encapsulated Mg2Ni alloy composite (rGO/Mg2Ni). The experimental results show that ζ potentials of rGO and the modified Mg2Ni alloy are totally opposite in water, with values of -11.0 and +22.4 mV, respectively. The crumpled structure of rGO sheets and the contents of the carbon element on the surface of the alloy are measured using scanning electron microscopy, transmission electron microscopy, and energy dispersive spectrometry. The Tafel polarization test indicates that the rGO/Mg2Ni system exhibits a much higher anticorrosion ability against the alkaline solution during charging/discharging. As a result, high-capacity retentions of 94% (557 mAh g(-1)) at the 10th cycle and 60% (358 mAh g(-1)) at the 50th cycle have been achieved, which are much higher than the results on Mg2Ni capacity retention combined with the absolute value reported so far to our knowledge. In addition, both the charge-transfer reaction rate and the hydrogen diffusion rate are proven to be boosted with the rGO encapsulation. Overall, this work demonstrates the effective anticorrosion and electrochemical property-enhancing effects of rGO coating and shows its applicability in the Mg-based hydrogen storage system.

  3. Oxidation behavior of NiCoCrAlY coatings deposited by double-Glow plasma alloying

    Science.gov (United States)

    Cui, Shiyu; Miao, Qiang; Liang, Wenping; Li, Baiqiang

    2018-01-01

    The NiCoCrAlY coatings were deposited on the Inconel 718 alloy substrates by a novel method called double-glow plasma alloying (DG). The phases and microstructure of the coatings were investigated by X-ray diffraction analysis while their chemical composition was analyzed using scanning electron microscopy. The morphology of the NiCoCrAlY coatings was typical of coatings formed by DG, with their structure consisting of uniform submicron-sized grains. Further, the coatings showed high adhesion strength (critical load >46 N). In addition, the oxidation characteristics of the coatings and the substrate were examined at three different temperatures (850, 950, and 1050 °C) using a muffle furnace. The coatings showed a lower oxidation rate, which was approximately one-tenth of that of the substrate. Even after oxidation for 100 h, the Al2O3 phase was the primary phase in the surface coating (850 °C), with the thickness of the oxide film increasing to 0.65 μm at 950 °C. When the temperature was increased beyond 1050 °C, the elemental Al and Ni were consumed in the formation of the oxide scale, which underwent spallation at several locations. The oxidation products of Cr, which were produced in large amounts and had a prism-like structure, controlled the subsequent oxidation behavior at the surface.

  4. The oxidation of organic additives in the positive vanadium electrolyte and its effect on the performance of vanadium redox flow battery

    Science.gov (United States)

    Nguyen, Tam D.; Whitehead, Adam; Scherer, Günther G.; Wai, Nyunt; Oo, Moe O.; Bhattarai, Arjun; Chandra, Ghimire P.; Xu, Zhichuan J.

    2016-12-01

    Despite many desirable properties, the vanadium redox flow battery is limited, in the maximum operation temperature that can be continuously endured, before precipitation begins in the positive electrolyte. Many additives have been proposed to improve the thermal stability of the charged positive electrolyte. However, we have found that the apparent stability, revealed in laboratory testing, is often simply an artifact of the test method and arises from the oxidation of the additive, with corresponding partial reduction of V(V) to V(IV). This does not improve the stability of the electrolyte in an operating system. Here, we examined the oxidation of some typical organic additives with carboxyl, alcohol, and multi-functional groups, in sulfuric acid solutions containing V(V). The UV-vis measurements and titration results showed that many compounds reduced the state-of-charge (SOC) of vanadium electrolyte, for example, by 27.8, 88.5, and 81.9% with the addition of 1%wt of EDTA disodium salt, pyrogallol, and ascorbic acid, respectively. The cell cycling also indicated the effect of organic additives on the cell performance, with significant reduction in the usable charge capacity. In addition, a standard screening method for thermally stable additives was introduced, to quickly screen suitable additives for the positive vanadium electrolyte.

  5. Hydrophobic cotton textile surfaces using an amphiphilic graphene oxide (GO) coating

    Science.gov (United States)

    Tissera, Nadeeka D.; Wijesena, Ruchira N.; Perera, J. Rangana; de Silva, K. M. Nalin; Amaratunge, Gehan A. J.

    2015-01-01

    We report for the first time hydrophobic properties on cotton fabric successfully achieved by grafting graphene oxide on the fabric surface, using a dyeing method. Graphite oxide synthesized by oxidizing natural flake graphite employing improved Hummer's method showed an inter layer spacing of ∼1 nm from XRD. Synthesized graphite oxide was exfoliated in water using ultrasound energy to obtain graphene oxide (GO). AFM data obtained for the graphene oxide dispersed in an aqueous medium revealed a non-uniform size distribution. FTIR characterization of the synthesized GO sheets showed both hydrophilic and hydrophobic functional groups present on the nano sheets giving them an amphiphilic property. GO flakes of different sizes were successfully grafted on to a cotton fabric surface using a dip dry method. Loading different amounts of graphene oxide on the cotton fiber surface allowed the fabric to demonstrate different degrees of hydrophobicity. The highest observed water contact angle was at 143° with the highest loading of graphene oxide. The fabric surfaces grafted with GO also exhibits adhesive type hydrophobicity. Microscopic characterization of the fiber surface using SEM and AFM reveals the deposition of GO sheets on the fiber surface as a conformal coating. Analysis of the fabric surface using UV-vis absorption allowed identification of the ratio of hydrophobic to hydrophilic domains present on the GO coated cotton fabric surface. Hydrophobic properties on cotton fabric are ascribed to two dimensional amphiphilic properties of deposited GO nano sheets, which successfully lower the interfacial energy of the fabric surface.

  6. Preparation of an antibacterial, hydrophilic and photocatalytically active polyacrylic coating using TiO2nanoparticles sensitized by graphene oxide.

    Science.gov (United States)

    Nosrati, Rahimeh; Olad, Ali; Shakoori, Sahar

    2017-11-01

    In recent years more attentions have been paid for preparation of coatings with self-cleaning and antibacterial properties. These properties allow the surface to maintain clean and health over long times without any need to cleaning or disinfection. Acrylic coatings are widely used on various surfaces such as automotive, structural and furniture which their self-cleaning and antibacterial ability is very important. The aim of this work is the preparation of a polyacrylic based self-cleaning and antibacterial coating by the modification of TiO 2 as a coating additive. TiO 2 nanoparticles were sensitized to the visible light irradiation using graphene oxide through the preparation of TiO 2 /graphene oxide nanocomposite. Graphene oxide was prepared via a modified Hummers method. TiO 2 /graphene oxide nanocomposite was used as additive in a polyacrylic coating formulation. Hydrophilicity, photocatalytic and antibacterial activities as well as coating stability were evaluated for TiO 2 /graphene oxide modified polyacrylic coating and compared with that of pristine TiO 2 modified and unmodified polyacrylic coatings. TiO 2 /graphene oxide nanocomposite and polyacrylic coating modified by TiO 2 /graphene oxide additive were characterized using FT-IR, UV-Vis, XRD, and FESEM techniques. The effect of TiO 2 /graphene oxide composition and its percent in the coating formulation was evaluated on the polyacrylic coating properties. Results showed that polyacrylic coating having 3% W TiO 2 /graphene oxide nanocomposite additive with TiO 2 to graphene oxide ratio of 100:20 is the best coating considering most of beneficial features such as high photodecolorization efficiency of organic dye contaminants, high hydrophilicity, and stability in water. According to the results, TiO 2 is effectively sensitized by graphene oxide and the polyacrylic coating modified by TiO 2 /graphene oxide nanocomposite shows good photocatalytic activity under visible light irradiation. Copyright © 2017

  7. Effect of Oxide Coating on Performance of Copper-Zinc Oxide-Based Catalyst for Methanol Synthesis via Hydrogenation of Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Tetsuo Umegaki

    2015-11-01

    Full Text Available The effect of oxide coating on the activity of a copper-zinc oxide–based catalyst for methanol synthesis via the hydrogenation of carbon dioxide was investigated. A commercial catalyst was coated with various oxides by a sol-gel method. The influence of the types of promoters used in the sol-gel reaction was investigated. Temperature-programmed reduction-thermogravimetric analysis revealed that the reduction peak assigned to the copper species in the oxide-coated catalysts prepared using ammonia shifts to lower temperatures than that of the pristine catalyst; in contrast, the reduction peak shifts to higher temperatures for the catalysts prepared using L(+-arginine. These observations indicated that the copper species were weakly bonded with the oxide and were easily reduced by using ammonia. The catalysts prepared using ammonia show higher CO2 conversion than the catalysts prepared using L(+-arginine. Among the catalysts prepared using ammonia, the silica-coated catalyst displayed a high activity at high temperatures, while the zirconia-coated catalyst and titania-coated catalyst had high activity at low temperatures. At high temperature the conversion over the silica-coated catalyst does not significantly change with reaction temperature, while the conversion over the zirconia-coated catalyst and titania-coated catalyst decreases with reaction time. From the results of FTIR, the durability depends on hydrophilicity of the oxides.

  8. Microstructure and Properties of Composite Coatings Obtained on Aluminium Alloys

    Directory of Open Access Journals (Sweden)

    Bara M.

    2016-09-01

    Full Text Available This paper presents methods of modifying the anode surface layers of Al2O3 by introducing carbon to their microstructure. Composite coatings were prepared using two different methods. In the first, coatings were formed by means of oxidation under constant current conditions. Anodic oxidation of aluminium was conducted in a multicomponent electrolyte with the addition of organic acids and graphite. The second method was based on the formation of oxide coatings in an electrolyte without the addition of graphite or heat treatment of the layers of succinic acid. The obtained coatings were tested using SEM, TEM, and GDOES (glow discharge optical emission spectrometry and their tribological and stereometric properties were measured. The study demonstrated the beneficial effects of the methods when used to improve the tribological properties of sliding couples.

  9. Anodic Behavior of the Aluminum Current Collector in Imide-Based Electrolytes: Influence of Solvent, Operating Temperature, and Native Oxide-Layer Thickness.

    Science.gov (United States)

    Meister, Paul; Qi, Xin; Kloepsch, Richard; Krämer, Elisabeth; Streipert, Benjamin; Winter, Martin; Placke, Tobias

    2017-02-22

    The inability of imide salts to form a sufficiently effective passivation layer on aluminum current collectors is one of the main obstacles that limit their broad application in electrochemical energy-storage systems. However, under certain circumstances, the use of electrolytes with imide electrolyte salts in combination with the aluminum current collector is possible. In this contribution, the stability of the aluminum current collector in electrolytes containing either lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) or lithium fluorosulfonyl-(trifluoromethanesulfonyl) imide (LiFTFSI) as conductive salt was investigated by electrochemical techniques, that is, cyclic voltammetry (CV) and chronocoulometry (CC) in either room-temperature ionic liquids or in ethyl methyl sulfone. In particular, the influence of the solvent, operating temperature, and thickness of the native oxide layer of aluminum on the pit formation at the aluminum current collector surface was studied by means of scanning electron microscopy. In general, a more pronounced aluminum dissolution and pit formation was found at elevated temperatures as well as in solvents with a high dielectric constant. An enhanced thickness of the native aluminum oxide layer increases the oxidative stability versus dissolution. Furthermore, we found a different reaction rate depending on dwell time at the upper cut-off potential for aluminum dissolution in TFSI- and FTFSI-based electrolytes during the CC measurements; the use of LiFTFSI facilitated the dissolution of aluminum compared to LiTFSI. Overall, the mechanism of anodic aluminum dissolution is based on: i) the attack of the Al2 O3 surface by acidic species and ii) the dissolution of bare aluminum into the electrolyte, which, in turn, is influenced by the electrolyte's dielectric constant. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Inter-diffusion between Co3O4 coatings and the oxide scale on Fe-22Cr

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Linderoth, Søren; Mogensen, Mogens Bjerg

    2007-01-01

    The oxidation behaviour of a commercially available Fe-22Cr alloy coated with a Co3O4 layer by spray-painting or plasma-spraying was investigated at 1173K in air with 1% H2O and compared to the oxidation behaviour of the non-coated alloy. The oxide morphology was examined with X-ray diffraction......, electron microscopy, and energy dispersive X-ray spectroscopy. Cr2O3 developed in-between the Co3O4 coating and the alloy, whilst alloying elements of the substrate were incorporated in the coating, regardless of the deposition method. The coatings reduced the growth rate of the Cr2O3 layer as well...... plasma-sprayed and the non-coated samples. The difference in morphology is suggested to be an effect of SiO2 nucleation assisted by Kirkendall void formation....

  11. 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.

  12. Poly (3,4-ethylenedioxythiophene) graphene oxide composite coatings for controlling magnesium implant corrosion.

    Science.gov (United States)

    Catt, Kasey; Li, Huaxiu; Cui, X Tracy

    2017-01-15

    Magnesium (Mg) is a promising biodegradable implant material because of its appropriate mechanical properties and safe degradation products. However, in vivo corrosion speed and hydrogen gas production need to be controlled for uses in biomedical applications. Here we report the development of a conducting polymer 3,4-ethylenedioxythiphene (PEDOT) and graphene oxide (GO) composite coating as a corrosion control layer. PEDOT/GO was electropolymerized on Mg samples in ethanol media. The coated Mg samples were subjected to various corrosion tests. The PEDOT/GO coating significantly reduced the rate of corrosion as evidenced by lower Mg ion concentration and pH of the corrosion media. In addition, the coating decreased the evolved hydrogen. Electrochemical analysis of the corroding samples showed more positive corrosion potential, a decreased corrosion current, and an increase in the polarization resistance. PEDOT/GO corrosion protection is attributed to three factors; an initial passive layer preventing solution ingress, buildup of negative charges in the film, and formation of corrosion protective Mg phosphate layer through redox coupling with Mg corrosion. To explore the biocompatibility of the coated implants in vitro, corrosion media from PEDOT/GO coated or uncoated Mg samples were exposed to cultured neurons where PEDOT/GO coated samples showed decreased toxicity. These results suggest that PEDOT/GO coating will be an effective treatment for controlling corrosion of Mg based medical implants. Coating Mg substrates with a PEDOT/GO composite coating showed a significant decrease in corrosion rate. While conducting polymer coatings have been used to prevent corrosion on various metals, there has been little work on the use of these coatings for Mg. Additionally, to our knowledge, there has not been a report of the combined used of conducting polymer and GO as a corrosion control layer. Corrosion control is attributed to an initial barrier layer followed by

  13. Electrolyte-gated, high mobility inorganic oxide transistors from printed metal halides.

    Science.gov (United States)

    Garlapati, Suresh Kumar; Mishra, Nilesha; Dehm, Simone; Hahn, Ramona; Kruk, Robert; Hahn, Horst; Dasgupta, Subho

    2013-11-27

    Inkjet printed and low voltage (≤1 V) driven field-effect transistors (FETs) are prepared from precursor-made In2O3 as the transistor channel and a composite solid polymer electrolyte (CSPE) as the gate dielectric. Printed halide precursors are annealed at different temperatures (300-500 °C); however, the devices that are heated to 400 °C demonstrate the best electrical performance including field-effect mobility as high as 126 cm(2) V(-1) s(-1) and subthreshold slope (68 mV/dec) close to the theoretical limit. These outstanding device characteristics in combination with ease of fabrication, moderate annealing temperatures and low voltage operation comprise an attractive set of parameters for battery compatible and portable electronics.

  14. Tungsten oxide coatings deposited by plasma spray using powder and solution precursor for detection of nitrogen dioxide gas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao, E-mail: zhangc@yzu.edu.cn [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Wang, Jie [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Geng, Xin [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China)

    2016-05-25

    Increasing attention has been paid on preparation methods for resistive-type gas sensors based on semiconductor metal oxides. In this work, tungsten oxide (WO{sub 3}) coatings were prepared on alumina substrates and used as gas sensitive layers. The coatings were deposited by atmospheric plasma spray using powder, solution precursor, or a combination of both. Tungsten oxide powder through a powder port and ammonium tungstate aqueous solution through a liquid port were injected into plasma stream respectively or together to deposit WO{sub 3} coatings. Phase structures in the coatings were characterized by X-ray diffraction analyzer. The field-emission scanning electron microscopy images confirmed that the coatings were in microstructure, nanostructure or micro-nanostructure. The sensing properties of the sensors based on the coatings exposed to 1 ppm nitrogen dioxide gas were characterized in a home-made instrument. Sensing properties of the coatings were compared and discussed. The influences of gas humidity and working temperature on the sensor responses were further studied. - Highlights: • Porous gas sensitive coatings were deposited by plasma spray using powder and solution precursor. • Crystallized WO{sub 3} were obtained through hybrid plasma spray plus a pre-conditioned step. • Plasma power had an important influence on coating microstructure. • The particle size of atmospheric plasma-sprayed microstructured coating was stable. • Solution precursor plasma-sprayed WO{sub 3} coatings had nanostructure and showed good responses to 1 ppm NO{sub 2}.

  15. Photoluminescence blue shift of indium phosphide nanowire networks with aluminum oxide coating

    Energy Technology Data Exchange (ETDEWEB)

    Fryauf, David M.; Zhang, Junce; Norris, Kate J.; Diaz Leon, Juan J.; Oye, Michael M.; Kobayashi, Nobuhiko P. [Nanostructured Energy Conversion Technology and Research (NECTAR), Advanced Studies Laboratories, University of California, Santa Cruz, CA (United States); Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA (United States); NASA Ames Research Center, Moffett Field, CA (United States); Wei, Min [Baskin School of Engineering, University of California Santa Cruz, Santa Cruz, CA (United States); School of Micro-Electronics and Solid-Electronics, University of Electronic Science and Technology of China, Chengdu (China)

    2014-07-15

    This paper describes our finding that optical properties of semiconductor nanowires were modified by depositing a thin layer of metal oxide. Indium phosphide nanowires were grown by metal organic chemical vapor deposition on silicon substrates with gold catalyst resulting in three-dimensional nanowire networks, and optical properties were obtained from the collective nanowire networks. The networks were coated with an aluminum oxide thin film deposited by plasma-enhanced atomic layer deposition. We studied the dependence of the peak wavelength of photoluminescence spectra on the thickness of the oxide coatings. A continuous blue shift in photoluminescence spectra was observed when the thickness of the oxide coating was increased. The observed blue shift is attributed to the Burstein-Moss effect due to increased carrier concentration in the nanowire cores caused by repulsion from intrinsic negative fixed charges located at the inner oxide surface. Samples were further characterized by scanning electron microscopy, Raman spectroscopy, transmission electron microscopy, and selective area diffractometry to better understand the physical mechanisms for the blue shift. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Fabrication of Oxide Dispersion Strengthened Bond Coats with Low Al2O3 Content

    Science.gov (United States)

    Bergholz, Jan; Pint, Bruce A.; Unocic, Kinga A.; Vaßen, Robert

    2017-06-01

    Nanoscale oxide dispersions have long been used to increase the oxidation and wear resistance of alloys used as bond coatings in thermal barrier coatings. Their manufacturing via mechanical alloying is often accompanied by difficulties regarding their particle size, homogeneous distribution of the oxide dispersions inside the powder, involving considerable costs, due to cold welding of the powder during milling. A significant improvement in this process can be achieved by the use of process control agent (PCA) to achieve the critical balance between cold welding and fracturing, thereby enhancing the process efficiency. In this investigation, the influence of the organic additive stearic acid on the manufacturing process of Al2O3-doped CoNiCrAlY powder was investigated. Powders were fabricated via mechanical alloying at different milling times and PCA concentrations. The results showed a decrease in particle size, without hindering the homogeneous incorporation of the oxide dispersions. Two powders manufactured with 0.5 and 1.0 wt.% PCA were deposited by high velocity oxygen fuel (HVOF) spraying. Results showed that a higher content of elongated particles in the powder with the higher PCA content led to increased surface roughness, porosity and decreased coating thickness, with areas without embedded oxide particles.

  17. Bilayer electrolyte-anode for solid oxide fuel cell; Obtencao de bicamadas eletrolito-anodo para pilhas a combustivel de oxido solido

    Energy Technology Data Exchange (ETDEWEB)

    Crochemore, G.B.; Marcomini, R.F.; Souza, D.P.F. de [Universidade Federal de Sao Carlos (GEMM/UFSCAR), Sao Carlos, SP (Brazil). Programa de Pos Graduacao em Ciencia e Engenharia de Materiais], Email: dulcina@ufscar.br; Rabelo, A.A. [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Fac. de Engenharia de Materiais

    2010-07-01

    Solid oxide fuel cell is a high efficient device hence it plays a very important role in the hydrogen economy. However, the cell operation temperature must be lower than 800 deg C, what is attainable for thin Yttria stabilized zirconia (YSZ) electrolytes. The tape casting process is the most used technique because it allows a very fine tuning of the tape thickness. In this work it were investigated the processing conditions for obtaining electrolyte-anode (YSZ/ YSZ-NiO) bilayers with no lamination after the sintering process. (author)

  18. In situ functionalization and PEO coating of iron oxide nanocrystals using seeded emulsion polymerization.

    Science.gov (United States)

    Kloust, Hauke; Schmidtke, Christian; Feld, Artur; Schotten, Theo; Eggers, Robin; Fittschen, Ursula E A; Schulz, Florian; Pöselt, Elmar; Ostermann, Johannes; Bastús, Neus G; Weller, Horst

    2013-04-16

    Herein we demonstrate that seeded emulsion polymerization is a powerful tool to produce multiply functionalized PEO coated iron oxide nanocrystals. Advantageously, by simple addition of functional surfactants, functional monomers, or functional polymerizable linkers-solely or in combinations thereof-during the seeded emulsion polymerization process, a broad range of in situ functionalized polymer-coated iron oxide nanocrystals were obtained. This was demonstrated by purposeful modulation of the zeta potential of encapsulated iron oxide nanocrystals and conjugation of a dyestuff. Successful functionalization was unequivocally proven by TXRF. Furthermore, the spatial position of the functional groups can be controlled by choosing the appropriate spacers. In conclusion, this methodology is highly amenable for combinatorial strategies and will spur rapid expedited synthesis and purposeful optimization of a broad scope of nanocrystals.

  19. Ceramic coated Y1 magnesium alloy surfaces by microarc oxidation ...

    Indian Academy of Sciences (India)

    The magnesium alloys occupy an important place in marine applications, but their poor corrosion resistance, wear resistance, hardness and so on, have limited their application. To meet these defects, some techniques are developed. Microarc oxidation is a one such recently developed surface treatment technology under ...

  20. Biocompatible and fluorescent superparamagnetic iron oxide nanoparticles with superior magnetic properties coated with charged polysaccharide derivatives.

    Science.gov (United States)

    Lachowicz, Dorota; Szpak, Agnieszka; Malek-Zietek, Katarzyna E; Kepczynski, Mariusz; Muller, Robert N; Laurent, Sophie; Nowakowska, Maria; Zapotoczny, Szczepan

    2017-02-01

    Syntheses and characterizations of biocompatible superparamagnetic iron oxide nanoparticles with embedded curcumin and coated with ultrathin layer of hyaluronic acid-curcumin (HA-Cur) conjugate have been reported. Zeta potential measurements confirmed effective coating of native iron oxide nanoparticles stabilized by cationic derivative of chitosan (SPION-CCh) with the synthesized HA-Cur conjugate. Both SPIONs with embedded curcumin and the ones coated with HA-Cur (SPION-CCh/HA-Cur) revealed desired magnetic characteristics while fluorescent properties were much better for the coated nanoparticles. SPION-CCh/HA-Cur nanoparticles were shown to be very promising candidates for T2 MRI contrast agents as they can easily penetrate cell membrane and their relaxivity is exceptionally high (ca. 470mM(-1)s(-1)). They may be also tracked using confocal fluorescence microscopy due to the presence of fluorescent curcumin in the coating. In vitro studies indicated that the obtained SPIONs-CCh/HA-Cur were non-toxic for EA.hy926 endothelial cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Effect of coating thickness of iron oxide nanoparticles on their relaxivity in the MRI

    Directory of Open Access Journals (Sweden)

    Farzaneh Hajesmaeelzadeh

    2016-02-01

    Full Text Available Objective(s:Iron oxide nanoparticles have found prevalent applications in various fields including drug delivery, cell separation and as contrast agents. Super paramagnetic iron oxide (SPIO nanoparticles allow researchers and clinicians to enhance the tissue contrast of an area of interest by increasing the relaxation rate of water. In this study, we evaluate the dependency of hydrodynamic size of iron oxide nanoparticles coated with Polyethylene  glycol (PEG on their relativities with 3 Tesla clinical MRI. Materials and Methods: We used three groups of nanoparticles with nominal sizes 20, 50 and 100 nm with a core size of 8.86 nm, 8.69 nm and 10.4 nm that they were covered with PEG 300 and 600 Da. A clinical magnetic resonance scanner determines the T1 and T2 relaxation times for various concentrations of PEG-coated nanoparticles. Results: The size measurement by photon correlation spectroscopy showed the hydrodynamic sizes of MNPs with nominal 20, 50 and 100 nm with 70, 82 and 116 nm for particles with PEG 600 coating and 74, 93 and 100 nm for  particles with PEG 300 coating, respectively. We foud that the relaxivity decreased with increasing overall particle size (via coating thickness. Magnetic resonance imaging showed that by increasing the size of the nanoparticles, r2/r1 increases linearly. Conclusion: According to the data obtained from this study it can be concluded that increments in coating thickness have more influence on relaxivities compared to the changes in core size of magnetic nanoparticles.

  2. The new aspects of the anticorrosive ZnO@SiO2 core-shell NPs in stabilizing of the electrolytic Ni bath and the Ni coating structure; electrochemical behavior of the resulting nano-composite coatings.

    Science.gov (United States)

    Sharifalhoseini, Zahra; Entezari, Mohammad H

    2015-10-01

    The pure phase of the ZnO nanoparticles (NPs) as anticorrosive pigments was synthesized by the sonication method. The surfaces of the sono-synthesized nanoparticles were covered with the protective silica layer. The durability of the coated and uncoated ZnO NPs in the used electrolytic Ni bath was determined by flame atomic absorption spectrometry. In the present research the multicomponent Ni bath as the complex medium was replaced by the simple one. The used nickel-plating bath was just composed of the Ni salts (as the sources of the Ni(2+) ions) to better clarify the influence of the presence of the ZnO@SiO2 core-shell NPs on the stability of the medium. The effect of ZnO@SiO2 NPs incorporation on the morphology of the solid electroformed Ni deposit was studied by scanning electron microscopy (SEM). Furthermore, the influence of the co-deposited particles in the Ni matrix on the corrosion resistance of the Ni coating was evaluated by the electrochemical methods including linear polarization resistance (LPR) and Tafel extrapolation. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Assessing the anti-fungal efficiency of filters coated with zinc oxide nanoparticles

    Science.gov (United States)

    Decelis, Stephen; Sardella, Davide; Triganza, Thomas; Brincat, Jean-Pierre; Gatt, Ruben; Valdramidis, Vasilis P.

    2017-05-01

    Air filters support fungal growth, leading to generation of conidia and volatile organic compounds, causing allergies, infections and food spoilage. Filters that inhibit fungi are therefore necessary. Zinc oxide (ZnO) nanoparticles have anti-fungal properties and therefore are good candidates for inhibiting growth. Two concentrations (0.012 M and 0.12 M) were used to coat two types of filters (melt-blown and needle-punched) for three different periods (0.5, 5 and 50 min). Rhizopus stolonifer and Penicillium expansum isolated from spoiled pears were used as test organisms. Conidial suspensions of 105 to 103 spores ml-1 were prepared in Sabouraud dextrose agar at 50°C, and a modified slide-culture technique was used to test the anti-fungal properties of the filters. Penicillium expansum was the more sensitive organism, with inhibition at 0.012 M at only 0.5 min coating time on the needle-punched filter. The longer the coating time, the more effective inhibition was for both organisms. Furthermore, it was also determined that the coating process had only a slight effect on the Young's Moduli of the needle-punched filters, while the Young's Moduli of the melt-blown filters is more susceptible to the coating method. This work contributes to the assessment of the efficacy of filter coating with ZnO nanopaticles aimed at inhibiting fungal growth.

  4. Preparation and characterization of the micro-arc oxidation composite coatings on magnesium alloys

    Directory of Open Access Journals (Sweden)

    Yanfeng Ge

    2014-12-01

    Full Text Available The magnesium alloys attract the light-weight manufacture due to its high strength to weight ratio, however the poor corrosion resistance limits the application in automobile industry. The Micro-arc Composite Ceramic (MCC coatings on AZ91D magnesium alloys were prepared by Micro-arc Oxidation (MAO and electrophoresis technologies. The microstructure, corrosion resistance, abrasion resistance, stone impact resistance and adhesion of MCC coatings were studied respectively. The cross section morphologies showed that the outer organic coating was filled into the hole on surface of MAO coating, and it acted as a shelter against corrosive products. The copper-accelerated acetic acid salt spray Test, abrasion resistance test, stone impact resistance test, thermal shock resistance test and adhesion test were used to evaluate the protective characterization by the third testing organization which approved by GM. The test results showed the composite coatings meet all the requirements. The MCC coating on Mg presents excellent properties, and it is a promising surface treatment technology on magnesium alloys for production vehicles.

  5. Dissolution kinetics of macronutrient fertilizers coated with manufactured zinc oxide nanoparticles.

    Science.gov (United States)

    Milani, Narges; McLaughlin, Mike J; Stacey, Samuel P; Kirby, Jason K; Hettiarachchi, Ganga M; Beak, Douglas G; Cornelis, Geert

    2012-04-25

    The solubility of Zn in Zn fertilizers plays an important role in the agronomic effectiveness of the fertilizer. On the basis of thermodynamics, zinc oxide (ZnO) nanoparticles (NPs) should dissolve faster and to a greater extent than bulk ZnO particles (equivalent spherical diameter >100 nm). These novel solubility features of ZnO NPs might be exploited to improve the efficiency of Zn fertilizers. In this study, we compared the Zn solubility and dissolution kinetics of ZnO nanoparticles and bulk ZnO particles coated onto two selected granular macronutrient fertilizers, urea and monoammonium phosphate (MAP). The main Zn species on coated MAP and urea granules were zinc ammonium phosphate and ZnO, respectively. Coated MAP granules showed greater Zn solubility and faster dissolution rates in sand columns compared to coated urea granules, which may be related to pH differences in the solution surrounding the fertilizer granules. The kinetics of Zn dissolution was not affected by the size of the ZnO particles applied for coating of either fertilizer type, possibly because solubility was controlled by formation of the same compounds irrespective of the size of the original ZnO particles used for coating.

  6. Enhanced gas sensing of Au nanocluster-doped or -coated zinc oxide thin films

    Science.gov (United States)

    Socol, G.; Axente, E.; Ristoscu, C.; Sima, F.; Popescu, A.; Stefan, N.; Mihailescu, I. N.; Escoubas, L.; Ferreira, J.; Bakalova, S.; Szekeres, A.

    2007-10-01

    We demonstrated that doping or covering with Au nanoclusters boosts gas sensing effectiveness of optical metal oxide sensors. The sensing response of pulsed laser deposited ZnO films as sensing element was tested by m-line technique for low concentration (1000ppm) of butane in environmental N2. The optical interrogation was performed for three types of coatings: undoped ZnO, undoped ZnO structures partially covered with Au nanoclusters, or obtained from Au (0.5wt%) doped ZnO targets. Nanocluster coating tripled the sensitivity, while doping resulted in an increase of up to 45% as compared with simple structures.

  7. Influence of dextran coating on the magnetic behaviour of iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Dutz, Silvio [Institute for Physical High Technology, Albert-Einstein-Strasse 9, 07745 Jena (Germany) and Department of Biomedical Engineering, University of Applied Sciences, Jena (Germany)]. E-mail: silvio.dutz@ipht-jena.de; Andrae, Wilfried [Institute for Physical High Technology, Albert-Einstein-Strasse 9, 07745 Jena (Germany); Department of Biomedical Engineering, University of Applied Sciences, Jena (Germany); Hergt, Rudolf [Institute for Physical High Technology, Albert-Einstein-Strasse 9, 07745 Jena (Germany); Mueller, Robert [Institute for Physical High Technology, Albert-Einstein-Strasse 9, 07745 Jena (Germany); Oestreich, Christiane [Institute of Ceramic Materials, Freiberg University of Mining and Technology (Germany); Schmidt, Christopher [Institute for Physical High Technology, Albert-Einstein-Strasse 9, 07745 Jena (Germany); Department of Materials Engineering, University of Applied Sciences, Jena (Germany); Toepfer, Jorg [Department of Materials Engineering, University of Applied Sciences, Jena (Germany); Zeisberger, Matthias [Institute for Physical High Technology, Albert-Einstein-Strasse 9, 07745 Jena (Germany); Bellemann, Matthias E. [Department of Biomedical Engineering, University of Applied Sciences, Jena (Germany)

    2007-04-15

    Magnetic iron oxide nanoparticles with mean diameters in the range from 10 to 30 nm were prepared by modified chemical precipitation routes. The particles were suspended in an aqueous solution by coating of the particles with carboxymethyldextran. A stability against agglomeration was achieved over a period of more than 7 days. In the present investigation, the structural and the magnetic properties of the nanoparticles were investigated. The influence of the dextran shell on the strength of the dipole-dipole interactions between the neighbouring particles was determined by investigation of the remanence behaviour (Henkel plot) of coated as well as of uncoated particles.

  8. A chemically stable electrolyte with a novel sandwiched structure for proton-conducting solid oxide fuel cells (SOFCs)

    KAUST Repository

    Bi, Lei

    2013-11-01

    A chemically stable electrolyte structure was developed for proton-conducting SOFCs by using two layers of stable BaZr0.7Pr 0.1Y0.2O3 -δ to sandwich a highly-conductive but unstable BaCe0.8Y0.2O 3 -δ electrolyte layer. The sandwiched electrolyte structure showed good chemical stability in both CO2 and H2O atmosphere, indicating that the BZPY layers effectively protect the inner BCY electrolyte, while the BCY electrolyte alone decomposed completely under the same conditions. Fuel cell prototypes fabricated with the sandwiched electrolyte achieved a relatively high performance of 185 mW cm- 2 at 700 C, with a high electrolyte film conductivity of 4 × 10- 3 S cm- 1 at 600 C. © 2013 Elsevier B.V.

  9. Coatings on stainless steel for solid oxide fuel cell interconnects

    OpenAIRE

    Clarke, Richard

    2012-01-01

    Enabling inexpensive and ubiquitous steels for use as solid oxide fuel cell interconnects has two major hurdles to overcome. Firstly, corrosion must be limited such that the interconnect can have longevity. Secondly, the evaporation of chromium from the corrosion layer must also be limited such that the fuel cell can have longevity. The evaporation of chromium from chromia, titanium doped chromia, and chromium cobalt spinels was studied and characterized. Spinels lost the least amount of m...

  10. Steam Electrolysis by Proton-Conducting Solid Oxide Electrolysis Cells (SOECs) with Chemically Stable BaZrO3-Based Electrolytes

    KAUST Repository

    Bi, Lei

    2015-07-17

    BaZrO3-based material was applied as the electrolyte for proton-conducting solid oxide fuel cells (SOECs). Compared with the instability of BaCeO3-based proton-conductors, BaZrO3-based material could be a more promising candidate for proton-conducting SOECs due to its excellent chemical stability under H2O conditions, but few reports on this aspect has been made due to the processing difficulty for BaZrO3. Our recent pioneering work has demonstrated the feasibility of using BaZrO3-based electrolyte for SOECs and the fabricated cell achieves relatively high cell performance, which is comparable or even higher than that for BaCeO3-based SOECs and offers better chemical stability. Cell performance can be further improved by tailoring the electrolyte and electrode. © The Electrochemical Society.

  11. An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lingling, E-mail: lasier_wang@hotmail.com [College of Chemical Engineering and Materials, Quanzhou Normal University, Quanzhou 362000, Fujian (China); Environmental Engineering and Science Program, 705 Engineering Research Center, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Han, Changseok [ORISE Post-doctoral Fellow, The U.S. Environmental Protection Agency, ORD, NRMRL, STD, CPB, 26 W. Martin Luther King Jr. Drive, Cincinnati, OH 45268 (United States); Nadagouda, Mallikarjuna N. [The U.S. Environmental Protection Agency, ORD, NRMRL, WSWRD, WQMB, 26 W. Martin Luther King Jr. Drive, Cincinnati, OH 45268 (United States); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, 705 Engineering Research Center, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Nireas-International Water Research Centre, School of Engineering, University of Cyprus, PO Box 20537, 1678, Nicosia (Cyprus)

    2016-08-05

    Highlights: • An innovative adsorbent was successfully synthesized to remove humic acid. • The adsorbent possessed high adsorption capacity for humic acid. • The adsorption capacity remarkably increased after an acid modification. • The adsorption capacity was proportional to the amount of ZnO coated on zeolite. • Electrostatic interactions are a major factor at the first stage of the process. - Abstract: Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO{sub 3}){sub 2}·6H{sub 2}O functionalization of zeolite 4A. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The synthesized materials were characterized by porosimetry analysis, scanning electron microscopy, X-Ray diffraction analysis, and high resolution transmission electron microscopy. The maximum adsorption capacity of the adsorbents at 21 ± 1 °C was about 60 mgC g{sup −1}. The results showed that the positive charge density of ZnO-coated zeolite adsorbents was proportional to the amount of ZnO coated on zeolite and thus, ZnO-coated zeolite adsorbents exhibited a greater affinity for negatively charged ions. Furthermore, the adsorption capacity of ZnO-coated zeolite adsorbents increased markedly after acid modification. Adsorption experiments demonstrated ZnO-coated zeolite adsorbents possessed high adsorption capacity to remove HA from aqueous solutions mainly due to strong electrostatic interactions between negative functional groups of HA and the positive charges of ZnO-coated zeolite adsorbents.

  12. Coating-dependent induction of cytotoxicity and genotoxicity of iron oxide nanoparticles.

    Science.gov (United States)

    Magdolenova, Zuzana; Drlickova, Martina; Henjum, Kristi; Rundén-Pran, Elise; Tulinska, Jana; Bilanicova, Dagmar; Pojana, Giulio; Kazimirova, Alena; Barancokova, Magdalena; Kuricova, Miroslava; Liskova, Aurelia; Staruchova, Marta; Ciampor, Fedor; Vavra, Ivo; Lorenzo, Yolanda; Collins, Andrew; Rinna, Alessandra; Fjellsbø, Lise; Volkovova, Katarina; Marcomini, Antonio; Amiry-Moghaddam, Mahmood; Dusinska, Maria

    2015-05-01

    Surface coatings of nanoparticles (NPs) are known to influence advantageous features of NPs as well as potential toxicity. Iron oxide (Fe3O4) NPs are applied for both medical diagnostics and targeted drug delivery. We investigated the potential cytotoxicity and genotoxicity of uncoated iron oxide (U-Fe3O4) NPs in comparison with oleate-coated iron oxide (OC-Fe3O4) NPs. Testing was performed in vitro in human lymphoblastoid TK6 cells and in primary human blood cells. For cytotoxicity testing, relative growth activity, trypan blue exclusion, (3)H-thymidine incorporation and cytokinesis-block proliferation index were assessed. Genotoxicity was evaluated by the alkaline comet assay for detection of strand breaks and oxidized purines. Particle characterization was performed in the culture medium. Cellular uptake, morphology and pathology were evaluated by electron microscopy. U-Fe3O4 NPs were found not to be cytotoxic (considering interference of NPs with proliferation test) or genotoxic under our experimental conditions. In contrast, OC-Fe3O4 NPs were cytotoxic in a dose-dependent manner, and also induced DNA damage, indicating genotoxic potential. Intrinsic properties of sodium oleate were excluded as a cause of the toxic effect. Electron microscopy data were consistent with the cytotoxicity results. Coating clearly changed the behaviour and cellular uptake of the NPs, inducing pathological morphological changes in the cells.

  13. Microstructure characterization of oxidation of aluminized coating prepared by a combined process

    Science.gov (United States)

    Liu, H. B.; Tao, J.; Xu, J.; Chen, Z. F.; Sun, X. J.; Xu, Z.

    2008-08-01

    Alumina layer is a good candidate for the tritium penetration barrier that is important in the control of tritium losses due to permeation through structural materials used in high-temperature gas-cooled reactors and in fusion reactors. This paper describes the microstructure of the oxide film of the tritium penetration barrier formed on 316L stainless steel, which was prepared by a combined process, namely, aluminizing and oxidizing treatments using a double glow plasma technology. Microstructure and phase structure of the coatings investigated were examined by scanning electronic microscope (SEM), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM), respectively. The chemical composition and the chemical states of Al, O elements in the oxidation film were identified by X-ray photoelectron spectroscopy (XPS). After aluminization, the typical microstructure of the coating mainly consisted of an outer high aluminum-containing intermetallic compound layer (Fe 2Al 5 and FeAl) and intermediate ferritic stainless steel (α Fe(Al))layer followed by the austenitic substrate. After the combined process, an oxide layer that consisted of Al 2O 3 and spinel FeAl 2O 4 had been successfully formed on the aluminizing coating surface, with an amorphous outmost surface and an underlying subsurface nanocrystalline structure.

  14. Comparison between field and laboratory steam oxidation testing on aluminide coatings on P92

    Energy Technology Data Exchange (ETDEWEB)

    Agueero, A.; Gonzalez, V.; Gutierrez, M. [Instituto Nacional de Tecnica Aeroespacial, Ctra. Ajalvir Km 4, 28850 Torrejon de Ardoz (Spain); Knoedler, R.; Straub, S. [Alstom Power Systems GmbH, Boveristrasse 22, 68309 Mannheim (Germany); Muelas, R. [Ingenieria y Servicios Aeroespaciales, P Pintor Rosales 34, 28008 Madrid (Spain)

    2011-06-15

    Steam oxidation has become an important issue for steam power plants as operating temperatures increase from the current 550 to 600-650 C. For the last 10 years several groups have been carrying out steam oxidation testing of both uncoated substrates and coatings in the laboratory. On the other hand, field testing results are very scarce. In this paper, a comparison of laboratory steam oxidation testing with field test results carried out by Alstom at the Kraftwerk Westfalen power station located in Hamm, Germany will be presented. Both slurry deposited aluminide coatings and uncoated P92 steel have been included in the study. Under steam (atmospheric pressure) and isothermal conditions in the laboratory at 650 C, spallation of oxides formed on ferritic steels occurs after significantly longer time when compared to exposure to real operating conditions. Oxide spallation results in serious damage in steam power plants by obstructing heat exchanger tubes, erosion of valves and turbine blades, etc. Moreover, the thickness of the oxide scales formed under field testing conditions is significantly higher after similar exposure. On the other hand, aluminide coated P92, which exhibit thickness through cracks, have shown to be stable in the laboratory for up to 60 000 h at 650 C under steam, without evidence of crack propagation. However, field test results indicate that some degree of crack propagation occurs but without causing substrate attack up to 21 700 h of exposure. Moreover, the aluminium oxide observed in both laboratory and field tested specimens is different. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Boron cross-linked graphene oxide/polyvinyl alcohol nanocomposite gel electrolyte for flexible solid-state electric double layer capacitor with high performance

    KAUST Repository

    Huang, Yi-Fu

    2014-06-01

    A new family of boron cross-linked graphene oxide/polyvinyl alcohol (GO-B-PVA) nanocomposite gels is prepared by freeze-thaw/boron cross-linking method. Then the gel electrolytes saturated with KOH solution are assembled into electric double layer capacitors (EDLCs). Structure, thermal and mechanical properties of GO-B-PVA are explored. The electrochemical properties of EDLCs using GO-B-PVA/KOH are investigated, and compared with those using GO-PVA/KOH gel or KOH solution electrolyte. FTIR shows that boron cross-links are introduced into GO-PVA, while the boronic structure inserted into agglomerated GO sheets is demonstrated by DMA analysis. The synergy effect of the GO and the boron crosslinking benefits for ionic conductivity due to unblocking ion channels, and for improvement of thermal stability and mechanical properties of the electrolytes. Higher specific capacitance and better cycle stability of EDLCs are obtained by using the GO-B-PVA/KOH electrolyte, especially the one at higher GO content. The nanocomposite gel electrolytes with excellent electrochemical properties and solid-like character are candidates for the industrial application in high-performance flexible solid-state EDLCs. © 2014 Elsevier Ltd.

  16. Effects of background electrolytes and ionic strength on enrichment of Cd(II) ions with magnetic graphene oxide-supported sulfanilic acid.

    Science.gov (United States)

    Hu, Xin-jiang; Liu, Yun-guo; Zeng, Guang-ming; You, Shao-hong; Wang, Hui; Hu, Xi; Guo, Yi-ming; Tan, Xiao-fei; Guo, Fang-ying

    2014-12-01

    To elucidate the influence mechanisms of background electrolytes and ionic strength on Cd(II) removal, the adsorption of Cd(II) onto magnetic graphene oxide-supported sulfanilic acid (MGO-SA) in aqueous solutions containing different types and concentrations of background electrolytes was studied. The results indicate that Cd(II) adsorption was strongly dependent on pH and could be strongly affected by background electrolytes and ionic strength. The Cd(II) removal was decreased with the presence of background electrolyte cations (Na(+), K(+), Ca(2+), Mg(2+), Mn(2+), Zn(2+), and Ni(2+)), and the divalent cations exerted more obvious influences on the Cd(II) uptake than the monovalent cations at pH 6. Both Cl(-) and NO3(-) had negative effects on Cd(II) adsorption because they can form water-soluble metal-anion complexes with Cd(II) ions. The presence of 0.01molL(-1) Na3PO4 reduced the removal percentage of Cd(II) at pH5. The Cd(II) adsorption was sensitive to changes in the concentration of NaCl, NaNO3, NaClO4, and Na3PO4. Besides, the adsorption isotherm of Cd(II) onto MGO-SA could be well described by the Freundlich model and was also influenced by the type of background electrolyte ions and the ionic strength. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Optimization of nanoparticulate indium tin oxide slurries for the manufacture of ultra-thin indium tin oxide coatings with the slot-die coating process

    Energy Technology Data Exchange (ETDEWEB)

    Wegener, M.; Riess, K.; Roosen, A. [Erlangen-Nuremberg Univ., Erlangen (Germany). Dept. of Materials Science, Glass and Ceramics

    2016-07-01

    This paper deals with the optimization of colloidal processing to achieve suitable nanoparticulate indium tin oxide (ITO) slurries for the production of sub-μm-thin ITO coatings with the slot die coating process. For application in printed electronics these ITO coatings, which are composite films consisting of nanoparticulate ITO and a polymeric binder, should offer high flexibility, transparency and electrical conductivity. To preserve their flexibility, the composite films are not subject to any heat treatment, instead they are used as deposited and dried. To achieve very good transparency and electrical conductivity at the same time, the slurries must exhibit excellent dispersivity to result in a dense particle packing during film formation and drying. To reduce materials costs, films with thicknesses of several 100 nm are of interest. Therefore, the slot-die technique was applied as a fast, pre-dosing technique to produce sub-μm-thin ITO/binder composite films. The resulting ITO/binder films were characterized with regard to their key properties such as total transmission and specific electrical resistance. With the colloidal optimization of ethanol- and water-based nanoparticulate ITO slurries using PVP and PVB as binders, it was possible to achieve films of 250 nm in thickness exhibiting high total transmission of ∝ 93 % and a low specific electrical resistance of ∝ 10 Ω.cm.

  18. Influence of Mn-Co Spinel Coating on Oxidation Behavior of Ferritic SS Alloys for SOFC Interconnect Applications

    DEFF Research Database (Denmark)

    Venkatachalam, Vinothini; Molin, Sebastian; Kiebach, Wolff-Ragnar

    2014-01-01

    ). The oxidation behavior of both the coated and bare alloy was evaluated at 800°C in air for 1000 h. The oxidation kinetics were investigated using weight gain and scale thickness measurements. The weight gain per unit surface area of the bare alloy exhibited parabolic oxidation behavior. The influence of Mn...

  19. Zinc-oxide nanowires electrochemically grown onto sol-gel spin-coated seed layers

    Energy Technology Data Exchange (ETDEWEB)

    Bojorge, Claudia D.; Canepa, Horacio R. [CINSO, CONICET-CITEDEF, Juan B. de La Salle 4397, CP 1603 Villa Martelli, Buenos Aires (Argentina); Kent, Vladimir R.; Teliz, Erika; Marotti, Ricardo E.; Dalchiele, Enrique A. [Facultad de Ingenieria, Instituto de Fisica, Universidad de la Republica, J. H. Reissig 565, CC 30, CP 11000, Montevideo (Uruguay); Henriquez, Rodrigo; Gomez, Humberto [Facultad de Ciencias, Instituto de Quimica, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile)

    2011-07-15

    The electrochemical deposition of ZnO nanowires (NW) was optimized by growing onto a previously deposited seed layer. The ZnO seed layer was prepared by a sol-gel process from different precursor solutions and deposited onto FTO/glass by spin coating. Afterwards, NW were electrochemically grown onto those seed layers. The electrolyte was an aqueous solution of the Zn{sup +2} precursor (1 mM zinc acetate) and a supporting electrolyte (0.1 M sodium acetate), saturated with bubbling oxygen. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and optical transmittance. The XRD measurements show typical diffraction pattern of ZnO wurtzite structure. The SEM micrographs show the presence of smooth NW with hexagonal sections with diameters ranging from 40 to 250 nm. The optical transmittance reveals the presence of ZnO with bandgap energy between 3.23 and 3.29 eV. These spectra show a monotonically increasing transmittance from the UV into the red part of the spectrum. This feature may be originated in the dispersion of light at the NW and can be used to enhance below-gap absorption. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Size-Dependent Accumulation of PEGylated Silane-Coated Magnetic Iron Oxide Nanoparticles in Murine Tumors

    DEFF Research Database (Denmark)

    Larsen, Esben Kjær Unmack; Nielsen, T.; Wittenborn, T.

    2009-01-01

    Magnetic nanoparticles (MNP) can be used as contrast-enhancing agents to visualize tumors by magnetic resonance imaging (MRI). Here we describe an easy synthesis method of magnetic nanoparticles coated with polyethylene glycol (PEG) and demonstrate size-dependent accumulation in murine tumors...... following intravenous injection. Biocompatible iron oxide MNPs coated with PEG were prepared by replacing oleic acid with a biocompatible and commercially available silane-PEG to provide an easy and effective method for chemical coating. The colloidal stable PEGylated MNPs were magnetically separated...... into two distinct size subpopulations of 20 and 40 nm mean diameters with increased phagocytic uptake observed for the 40 nm size range in vitro. MRI detection revealed greater iron accumulation in murine tumors for 40 nm nanoparticles after intravenous injection. The enhanced MRI contrast of the larger...

  1. Magnetorheology of suspensions based on graphene oxide coated or added carbonyl iron microspheres and sunflower oil

    Science.gov (United States)

    Chen, Kaikai; Zhang, Wen Ling; Shan, Lei; Zhang, Xiangjun; Meng, Yonggang; Choi, Hyoung Jin; Tian, Yu

    2014-10-01

    Magnetorheological (MR) fluids based on carbonyl iron (CI) particles coated with graphene oxide (GO) and sunflower oils were studied and compared with MR fluids (MRFs) prepared with CI particles added with GO sheets. Adding GO sheets into CI had a negligible effect on the rheological properties of the MRF. Coating the spheres with GO markedly decreased the shear strength at high shear rates due to the remarkable lubricating function of the GO surface. Different behaviors were observed in the shear thickening phenomenon when the GO surface changed the mechanical interaction between particles. The results demonstrated the importance of the role of interparticle friction for MRF in shear mode and discussed the weak shear thickening phenomenon with fine lubricating coating layers and oils.

  2. Application of electrocatalytic oxidation of brown coal for anticorrosive coating of steel

    Energy Technology Data Exchange (ETDEWEB)

    Studnicki, M. (Zaklad Karbochemii PAN, Gliwice (Poland))

    1992-02-01

    Explains a method for preparing anticorrosive steel coatings. Brown coal was oxidized at 0.15 V and 0.5 A in a mixture with hydrogen peroxide (30%), sulfuric acid, ethanol and nickel nitrate. A sulfoxide inhibitor was further prepared as well as Epidain 5 epoxy resin and a rubber-asphalt composition. All components were used in 15 different mixtures. Steel plates were treated with the mixtures for 1 hour. Plates were further treated for 76 hours with 0.1% sulfuric acid and 0.021% NaCl solution. The mass loss of coating mixtures was measured and compared to that of Ketec standard coating. The surface protection factor reached as high as 75%. Nonlinear regression analysis and computer calculations were employed to determine the role of separate mixture components. Coefficients obtained by calculations are discussed. 10 refs.

  3. Electrochemical Oxidation of Silver and Copper in Aqueous Basic Media and in Fused Hydroxide Electrolytes

    Directory of Open Access Journals (Sweden)

    Tejada-Rosales, E. M.

    2004-04-01

    Full Text Available The anodic oxidations of copper and silver electrodes in basic media are reported. Experiments were conducted both in aqueous NaOH solutions and in a flux of molten NaOH/KOH eutectic. The oxidation processes were studied by means of cyclic voltammetry and chronoamperometries and the phases obtained were systematically characterized by x-ray diffraction. The ranges of stability of each phase in the different media studied are reported. In addition to known oxides of copper or silver, a new silver oxide was isolated.

    En este trabajo se describe la oxidación anódico de electrodos de plata y de cobre en medios básicos. Se han utilizado tanto medios acuosos como hidróxidos fundidos (eutéctico NaOH/KOH. Los procesos de oxidación se han estudiado mediante voltametría cíclica y cronoamperometría, y las fases resultantes han sido caracterizadas por difracción de Rayos X. Los rangos de estabilidad encontrados para cada uno dependen del medio utilizado. Además de óxidos conocidos de cobre y de plata, se ha aislado un nuevo óxido de plata.

  4. Pt supported on nanosized oxides for electrocatalyst used in polymer electrolyte fuel cells

    DEFF Research Database (Denmark)

    Banu, N.; Serban, E. C.; Marinescu, A.

    2011-01-01

    Even though Pt is a standard catalyst for fuel cells, new advanced materials with low activation energy and high specific surface area are required. Researches proved that conducting oxides are the emerging candidates as support for Pt catalysts targeting replacement of nanocarbons. This paper pr...

  5. Titania nanotubes from weak organic acid electrolyte: Fabrication, characterization and oxide film properties

    Energy Technology Data Exchange (ETDEWEB)

    Munirathinam, Balakrishnan, E-mail: blkrish88@gmail.com; Neelakantan, Lakshman

    2015-04-01

    In this study, TiO{sub 2} nanotubes were fabricated using anodic oxidation in fluoride containing weak organic acid for different durations (0.5 h, 1 h, 2 h and 3 h). Scanning electron microscope (SEM) micrographs reveal that the morphology of titanium oxide varies with anodization time. Raman spectroscopy and X-ray diffraction (XRD) results indicate that the as-formed oxide nanotubes were amorphous in nature, yet transform into crystalline phases (anatase and rutile) upon annealing at 600 °C. Wettability measurements show that both as-formed and annealed nanotubes exhibited hydrophilic behavior. The electrochemical behavior was ascertained by DC polarization and AC electrochemical impedance spectroscopy (EIS) measurements in 0.9% NaCl solution. The results suggest that the annealed nanotubes showed higher impedance (10{sup 5}–10{sup 6} Ω cm{sup 2}) and lower passive current density (10{sup −7} A cm{sup −2}) than the as-formed nanotubes. In addition, we investigated the influence of post heat treatment on the semiconducting properties of the oxides by capacitance measurements. In vitro bioactivity test in simulated body fluid (SBF) showed that precipitation of Ca/P is easier in crystallized nanotubes than the amorphous structure. Our study uses a simple strategy to prepare nano-structured titania films and hints the feasibility of tailoring the oxide properties by thermal treatment, producing surfaces with better bioactivity. - Highlights: • TiO{sub 2} nanotubes were synthesized in a citric acid and sodium fluoride environment. • Wettability measurements show that both as-formed and annealed nanotubes exhibited hydrophilic behavior. • TiO{sub 2} nanotube layer behaves as an n-type semiconductor. • Annealed TiO{sub 2} nanotubes had a higher impedance magnitude compared to as-formed nanotubes.

  6. Surface characteristics of coated polyester fabric with reduced graphene oxide and polypyrrole

    Energy Technology Data Exchange (ETDEWEB)

    Berendjchi, Amirhosein [Department of Textile Engineering, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Khajavi, Ramin, E-mail: khajavi@azad.ac.ir [Nano Technology Research Center, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Yousefi, Ali Akbar [Faculty of Polymer Processing, Iran Polymer and Petrochemical Institute, Tehran (Iran, Islamic Republic of); Yazdanshenas, Mohammad Esmail [Department of Textile Engineering, Yazd Branch, Islamic Azad University, Yazd (Iran, Islamic Republic of)

    2016-03-30

    Graphical abstract: - Highlights: • PET in form of film or membrane is hydrophobic and its wetting behavior follows the Wenzel wetting theory. In the form of textile materials it shows hydrophilicity. • rGO coated PET fabric shows hydrophobicity and its wetting behavior places between Wenzel and Cassie–Baxter models. • PET coated fabric by PPy shows superhydrophobicity and its wetting behavior is consistence with Cassie–Baxter model. • Due to oxidation of the rGO during in situ synthesis of PPy the rGO–PPy coated PET shows hydrophilicity. - Abstract: In this study, the influence of coating polyethylene terephthalate (PET) fabric with reduced graphene oxide (rGO) and polypyrrole (PPy), individually or in combination (rGO–PPy), on surface chemistry and roughness (focusing on wetting behavior), were analyzed systematically. Characterization was carried out by observing the topography (atomic force microscopy – AFM) and stating surface analysis (X-ray photoelectron spectroscopy – XPS), contact angles (goniometry), water shedding angles, and surface energy values of the samples. The results showed that the contact angles of pristine (uncoated), GO and rGO–PPy coated samples were 0°, while it was 92°, 123° and 151° for hot pressed (2nd pristine sample), rGO and PPy samples, respectively. A zero contact angle for PET sample was due to its wicking ability. Results were interpreted with Young, Wenzel and Cassie Baxter equations. It was found that PPy coated samples were consistent with Cassie–Baxter equation, while rGO placed between Wenzel and Cassie–Baxter wetting models.

  7. The High-Temperature Wear and Oxidation Behavior of CrC-Based HVOF Coatings

    Science.gov (United States)

    Houdková, Šárka; Česánek, Zdeněk; Smazalová, Eva; Lukáč, František

    2018-01-01

    Three commercially available chromium carbide-based powders with different kinds of matrix (Cr3C2-25%NiCr; Cr3C2-25%CoNiCrAlY and Cr3C2-50%NiCrMoNb) were deposited by an HVOF JP-5000 spraying gun, evaluated and compared. The influence of heat treatment on the microstructure and properties, as well as the oxidation resistance in a hot steam environment ( p = 24 MPa; T = 609 °C), was evaluated by SEM and XRD with respect to their potential application in the steam power industry. The sliding wear resistance measured at room and elevated ( T = 600 °C) temperatures according to ASTM G-133. For all three kinds of chromium carbide-based coatings, the precipitation of secondary carbides from the supersaturated matrix was observed during the heat treatment. For Cr3C2-25%NiCr coating annealed in hot steam environment as well as for Cr3C2-25%CoNiCrAlY coating in both environments, the inner carbide oxidation was recorded. The sliding wear resistance was found equal at room temperature, regardless of the matrix composition and content, while at elevated temperatures, the higher wear was measured, varying in dependence on the matrix composition and content. The chromium carbide-based coating with modified matrix composition Cr3C2-50%NiCrMoNb is suitable to replace the Cr3C2-25%NiCr coating in a hot steam environment to eliminate the risk of failure caused by inner carbide oxidation.

  8. Polymer Electrolytes

    Science.gov (United States)

    Hallinan, Daniel T.; Balsara, Nitash P.

    2013-07-01

    This review article covers applications in which polymer electrolytes are used: lithium batteries, fuel cells, and water desalination. The ideas of electrochemical potential, salt activity, and ion transport are presented in the context of these applications. Potential is defined, and we show how a cell potential measurement can be used to ascertain salt activity. The transport parameters needed to fully specify a binary electrolyte (salt + solvent) are presented. We define five fundamentally different types of homogeneous electrolytes: type I (classical liquid electrolytes), type II (gel electrolytes), type III (dry polymer electrolytes), type IV (dry single-ion-conducting polymer electrolytes), and type V (solvated single-ion-conducting polymer electrolytes). Typical values of transport parameters are provided for all types of electrolytes. Comparison among the values provides insight into the transport mechanisms occurring in polymer electrolytes. It is desirable to decouple the mechanical properties of polymer electrolyte membranes from the ionic conductivity. One way to accomplish this is through the development of microphase-separated polymers, wherein one of the microphases conducts ions while the other enhances the mechanical rigidity of the heterogeneous polymer electrolyte. We cover all three types of conducting polymer electrolyte phases (types III, IV, and V). We present a simple framework that relates the transport parameters of heterogeneous electrolytes to homogeneous analogs. We conclude by discussing electrochemical stability of electrolytes and the effects of water contamination because of their relevance to applications such as lithium ion batteries.

  9. Photocatalytic fabrics based on reduced graphene oxide and TiO{sub 2} coatings

    Energy Technology Data Exchange (ETDEWEB)

    Molina, J., E-mail: jamopue@doctor.upv.es [Departamento de Ingeniería Textil y Papelera, EPS de Alcoy, Universitat Politècnica de València, Plaza Ferrándiz y Carbonell s/n, 03801 Alcoy (Spain); Department of Textile Engineering, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); Fernandes, F., E-mail: b6073@fisica.uminho.pt [Department Physics, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); Fernández, J., E-mail: jaferse1@posgrado.upv.es [Departamento de Ingeniería Textil y Papelera, EPS de Alcoy, Universitat Politècnica de València, Plaza Ferrándiz y Carbonell s/n, 03801 Alcoy (Spain); Pastor, M., E-mail: marianapastor88@gmail.com [Department Physics, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); Correia, A., E-mail: anacamcorreia@gmail.com [Department Physics, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); Souto, A.P., E-mail: souto@det.uminho.pt [Department of Textile Engineering, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); Carneiro, J.O., E-mail: carneiro@fisica.uminho.pt [Department Physics, University of Minho, Azurém Campus, 4800-058 Guimarães (Portugal); and others

    2015-09-15

    Graphical abstract: - Highlights: • Photocatalytic fabrics were produced with reduced graphene oxide (RGO) and TiO{sub 2}. • Charge transfer resistance decreased with the increasing number of RGO layers. • Scanning electrochemical microscopy showed the photoresponse obtained. • Photocatalytic properties were tested with Rhodamine B solutions. • Photocatalytic efficiency increased with the number of RGO layers. - Abstract: The purpose of this work is to obtain photocatalytic fabrics based on reduced graphene oxide (RGO) and TiO{sub 2} coatings on polyester fabrics. The influence of the applied number of RGO coatings on properties such as light absorption, conductivity, electroactivity and photocatalytic properties of the fabrics was established. An improvement of these properties with the number of RGO coatings applied was obtained. FESEM, EDX, XPS and FTIR-ATR showed the incorporation of the TiO{sub 2} nanoparticles on the fabrics. FTIR-ATR showed the formation of a bidentate carboxylic ligand with titanium atoms. The photocatalytic properties of the fabrics were tested with Rhodamine B dye solutions. Photocatalytic efficiency increased with the number of RGO coatings, due to the increased light absorption, and better electrical properties. The charge transfer resistance (R{sub ct}) and its time constant (τ) decreased, indicating a better electron transfer which helps to increase the lifetime of the pair electron/hole.

  10. PAMAM dendrimer-coated iron oxide nanoparticles: synthesis and characterization of different generations

    Energy Technology Data Exchange (ETDEWEB)

    Khodadust, Rouhollah, E-mail: raoul.1357@gmail.com; Unsoy, Gozde [Middle East Technical University, Department of Biotechnology (Turkey); Yalc Latin-Small-Letter-Dotless-I n, Serap [Ahi Evran University, Department of Food Engineering (Turkey); Gunduz, Gungor [Middle East Technical University, Department of Chemical Engineering (Turkey); Gunduz, Ufuk, E-mail: ufukg@metu.edu.tr [Middle East Technical University, Department of Biotechnology (Turkey)

    2013-03-15

    This study focuses on the synthesis and characterization of different generations (G{sub 0}-G{sub 7}) of polyamidoamine (PAMAM) dendrimer-coated magnetic nanoparticles (DcMNPs). In this study, superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method. The synthesized nanoparticles were modified with aminopropyltrimethoxysilane for dendrimer coating. Aminosilane-modified MNPs were coated with PAMAM dendrimer. The characterization of synthesized nanoparticles was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), dynamic light scattering, and vibrating sample magnetometry (VSM) analyses. TEM images demonstrated that the DcMNPs have monodisperse size distribution with an average particle diameter of 16 {+-} 5 nm. DcMNPs were found to be superparamagnetic through VSM analysis. The synthesis, aminosilane modification, and dendrimer coating of iron oxide nanoparticles were validated by FTIR and XPS analyses. Cellular internalization of nanoparticles was studied by inverted light scattering microscopy, and cytotoxicity was determined by XTT analysis. Results demonstrated that the synthesized DcMNPs, with their functional groups, symmetry perfection, size distribution, improved magnetic properties, and nontoxic characteristics could be suitable nanocarriers for targeted cancer therapy upon loading with various anticancer agents.

  11. Oxidation performance of high temperature steels and coatings for future supercritical power plants

    Energy Technology Data Exchange (ETDEWEB)

    Auerkari, Pertti; Salonen, Jorma; Toivonen, Aki; Penttilae, Sami [VTT, Espoo (Finland); Haekkilae, Juha [Foster Wheeler Energia, Varkaus (Finland); Aguero, Alina; Gutierrez, Marcos; Muelas, Raul [INTA, Madrid (Spain); Fry, Tony [NPL (United Kingdom)

    2010-07-01

    The operating efficiency of current and future thermal power plants is largely dependent on the applied temperature and pressure, which are in part limited by the internal oxidation resistance of the structural materials in the steam systems. Alternative and reference materials for such systems have been tested within the COST 536 (ACCEPT) project, including bulk reference materials (ferritic P92 and austenitic 316 LN steels) and several types of coatings under supercritical combined (oxygen) water chemistry (150 ppb DO) at 650 C/300 bar. The testing results from a circulating USC autoclave showed that under such conditions the reference bulk steels performed poorly, with extensive oxidation already after relatively short term exposure to the supercritical medium. Better protection was attained by suitable coatings, although there were clear differences in the protective capabilities between different coating types, and some challenges remain in applying (and repairing) coatings for the internal surfaces of welded structures. The materials performance seems to be worse in supercritical than in subcritical conditions, and this appears not to be only due to the effect of temperature. The implications are considered from the point of view of the operating conditions and materials selection for future power plants. (orig.)

  12. Novel graphene-oxide-coated SPR interfaces for biosensing applications

    Science.gov (United States)

    Volkov, V. S.; Stebunov, Yu. V.; Yakubovsky, D. I.; Fedyanin, D. Yu.; Arsenin, A. V.

    2017-09-01

    Carbon allotropes-based nanomaterials possess unique physical and chemical properties including high surface area, the possibility of pi-stacking interaction with a wide range of biological objects, rich availability of oxygen-containing functional groups in graphene-oxide (GO), and excellent optical properties, which make them an ideal candidate for use as a universal immobilization platform in SPR biosensing. Here, we propose a new surface plasmon resonance (SPR) biosensing interface for sensitive and selective detection of small molecules. This interface is based on the GO linking layers deposited on the gold/copper surface of SPR sensor chips. To estimate the binding capacity of GO layers, modification of carboxyl groups to N-Hydroxysuccinimide esters was performed in the flow cell of SPR instrument. For comparison, the same procedure was applied to commercial sensor chips based on linking layers of carboxymethylated dextran.

  13. Surface functionalization of dopamine coated iron oxide nanoparticles for various surface functionalities

    Energy Technology Data Exchange (ETDEWEB)

    Sherwood, Jennifer; Xu, Yaolin; Lovas, Kira [Chemical and Biological Engineering, The University of Alabama, Tuscaloosa , AL 35487 (United States); Qin, Ying [Alabama Innovation and Mentoring of Entrepreneurs, The University of Alabama, Tuscaloosa, AL 35487 (United States); Bao, Yuping, E-mail: ybao@eng.ua.edu [Chemical and Biological Engineering, The University of Alabama, Tuscaloosa , AL 35487 (United States)

    2017-04-01

    We present effective conjugation of four small molecules (glutathione, cysteine, lysine, and Tris(hydroxymethyl)aminomethane) onto dopamine-coated iron oxide nanoparticles. Conjugation of these molecules could improve the surface functionality of nanoparticles for more neutral surface charge at physiological pH and potentially reduce non-specific adsorption of proteins to nanoparticles surfaces. The success of conjugation was evaluated with dynamic light scattering by measuring the surface charge changes and Fourier transform infrared spectroscopy for surface chemistry analysis. The stability of dopamine-coated nanoparticles and the ability of conjugated nanoparticles to reduce the formation of protein corona were evaluated by measuring the size and charge of the nanoparticles in biological medium. This facile conjugation method opens up possibilities for attaching various surface functionalities onto iron oxide nanoparticle surfaces for biomedical applications.

  14. Preparation and characterization of silica coated iron oxide magnetic nano-particles.

    Science.gov (United States)

    Li, Ying-Sing; Church, Jeffrey S; Woodhead, Andrea L; Moussa, Filsun

    2010-09-01

    Iron oxide magnetic nano-particles have been prepared by precipitation in an aqueous solution of iron(II) and iron(III) chlorides under basic condition. Surface modifications have been carried out by using tetraethoxysilane (TEOS) and mercaptopropyltrimethoxysilane (MPTMS). The uncoated and coated particles have been characterized with transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, thermal gravimetric analysis (TGA), and infrared (IR) and Raman spectroscopy. The particle sizes as measured from TEM images were found to have mean diameters of 13nm for the uncoated and about 19nm for the coated particles. The measured IR spectra of the uncoated and MPTMS coated particles showed the conversion of magnetite to hematite at high temperature. The results obtained from both IR spectroscopy and TGA revealed that the mercaptopropylsilyl group in the MPTMS coated magnetite decomposed at 600 degrees C and the silica layer of the TEOS coated magnetite was rather stable. Raman spectroscopy has shown the laser heating effect through the conversion of magnetite to maghemite and hematite. Copyright 2010 Elsevier B.V. All rights reserved.

  15. Polyelectrolyte coating on superparamagnetic iron oxide nanoparticles as interface between magnetic core and biorelevant media.

    Science.gov (United States)

    Tombácz, Etelka; Farkas, Katalin; Földesi, Imre; Szekeres, Márta; Illés, Erzsébet; Tóth, Ildikó Y; Nesztor, Daniel; Szabó, Tamás

    2016-12-06

    Nanoparticles do not exist in thermodynamical equilibrium because of high surface free energy, thus they have only kinetic stability. Spontaneous changes can be delayed by designed surface coating. In biomedical applications, superparamagnetic iron oxide nanoparticles (SPIONs) require an optimized coating in order to fulfil the expectation of medicine regulatory agencies and ultimately that of biocompatibility. In this work, we show the high surface reactivity of naked SPIONs due to ≡Fe-OH sites, which can react with H + /OH - to form pH- and ionic strength-dependent charges. We explain the post-coating of naked SPIONs with organic polyacids via multi-site complex bonds formed spontaneously. The excess polyacids can be removed from the medium. The free COOH groups in coating are prone to react with active biomolecules like proteins. Charging and pH- and salt-dependent behaviour of carboxylated SPIONs were characterized quantitatively. The interrelation between the coating quality and colloidal stability measured under biorelevant conditions is discussed. Our coagulation kinetics results allow us to predict colloidal stability both on storage and in use; however, a simpler method would be required to test SPION preparations. Haemocompatibility tests (smears) support our qualification for good and bad SPION manufacturing; the latter 'promises' fatal outcome in vivo .

  16. The immunotoxicity of graphene oxides and the effect of PVP-coating.

    Science.gov (United States)

    Zhi, Xiao; Fang, Hongliang; Bao, Chenchen; Shen, Guangxia; Zhang, Jiali; Wang, Kan; Guo, Shouwu; Wan, Tao; Cui, Daxiang

    2013-07-01

    Graphene oxide (GO) immunotoxicity is not clarified well up to date. Herein we reported the effects of GOs with and without polyvinylpyrrolidone (PVP) coating on human immune cells such as dendritic cells (DCs), T lymphocytes and macrophages. Human immune cells such as dendritic cells (DCs), T lymphocytes and macrophages were isolated from health donated bloods, PVP-coating GO (PVP-GO) exhibited lower immunogenicity compared with pure GO on the aspect of inducing differentiation and maturation of dendritic cells (DCs), the levels of secreted TNF-α and IL-1β had no obvious difference between two groups, yet the secretion of IL-6 remained in PVP-coating GO group. In addition, PVP-coating GO delayed significantly the apoptotic process of T lymphocytes, at the same time, and exhibited anti-phagocytosis ability against macrophages and markedly enhanced the physiological activity of macrophages. In conclusion, PVP-coating GO possesses good immunological biocompatibility and immunoenhancement effects in vitro, and is likely to be an available candidate of immunoadjuvant in the future. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. A Graphite Oxide Paper Polymer Electrolyte for Direct Methanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    Ravi Kumar

    2011-01-01

    Full Text Available A flow directed assembly of graphite oxide solution was used in the formation of free-standing graphene oxide paper of approximate thickness of 100 μm. The GO papers were characterised by XRD and SEM. Electrochemical characterization of the GO paper membrane electrode assembly revealed proton conductivities of 4.1 × 10−2 S cm−1 to 8.2 × 10−2 S cm−1 at temperatures of 25–90°C. A direct methanol fuel cell, at 60°C, gave a peak power density of 8 mW cm−2 at a current density of 35 mA cm−2.

  18. Growth Kinetics of Anodic Oxide Films Formed on Zircaloy-2 in Various Electrolytes

    Directory of Open Access Journals (Sweden)

    V. Jeevana Jyothi

    2009-01-01

    Full Text Available The Kinetics of anodic oxidation of zircaloy-2 have been studied at current densities ranging from 4 to 12 mA cm-2 at room temperature in order to investigate the dependence of ionic current density on the field across the oxide film. Thickness of the anodic films was estimated from capacitance data. The formation rate, current efficiency and differential field were found to increase with increase in the ionic current density for zircaloy-2. Plots of logarithm of formation rate vs. logarithm of current density is fairly linear. From linear plots of logarithm of ionic current density vs. differential field and applying the Cabrera - Mott theory, the half - jump distance (a and height of energy barrier (W were deduced.

  19. Attenuation of the in vitro neurotoxicity of 316L SS by graphene oxide surface coating.

    Science.gov (United States)

    Tasnim, Nishat; Kumar, Alok; Joddar, Binata

    2017-04-01

    A persistent theme in biomaterials research comprises of surface engineering and modification of bare metallic substrates for improved cellular response and biocompatibility. Graphene Oxide (GO), a derivative of graphene, has outstanding chemical and mechanical properties; its large surface to volume ratio, ease of surface modification and processing make GO an attractive coating material. GO-coatings have been extensively studied as biosensors. Further owing to its surface nano-architecture, GO-coated surfaces promote cell adhesion and growth, making it suitable for tissue engineering applications. The need to improve the long-term durability and therapeutic effectiveness of commercially available bare 316L stainless steel (SS) surfaces led us to adopt a polymer-free approach which is cost-effective and scalable. GO was immobilized on to 316L SS utilizing amide linkage, to generate a strongly adherent uniform coating with surface roughness. GO-coated 316L SS surfaces showed increased hydrophilicity and biocompatibility with SHSY-5Y neuronal cells, which proliferated well and showed decreased reactive oxygen species (ROS) expression. In contrast, cells did not adhere to bare uncoate