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Sample records for chemical conversion coatings

  1. Chemical conversion coating for protecting magnesium alloys from corrosion

    Science.gov (United States)

    Bhargava, Gaurang; Allen, Fred M.; Skandan, Ganesh; Hornish, Peter; Jain, Mohit

    2016-01-05

    A chromate-free, self-healing conversion coating solution for magnesium alloy substrates, composed of 10-20 wt. % Mg(NO.sub.3).sub.2.6H.sub.2O, 1-5 wt. % Al(NO.sub.3).sub.3.9H.sub.2O, and less than 1 wt. % of [V.sub.10O.sub.28].sup.6- or VO.sub.3.sup.- dissolved in water. The corrosion resistance offered by the resulting coating is in several hundreds of hours in salt-spray testing. This prolonged corrosion protection is attributed to the creation of a unique structure and morphology of the conversion coating that serves as a barrier coating with self-healing properties. Hydroxoaluminates form the backbone of the barrier protection offered while the magnesium hydroxide domains facilitate the "slow release" of vanadium compounds as self-healing moieties to defect sites, thus providing active corrosion protection.

  2. Preparation of micro/nano-fibrous brushite coating on titanium via chemical conversion for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bing [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji’nan 250061 (China); School of Materials Science and Engineering, Shandong University, Ji’nan, 250061 (China); Suzhou Institute, Shandong University, Suzhou, 215123 (China); Guo, Yong-yuan [Orthopedic Department, Qilu Hospital of Shandong University, Ji’nan, 250012 (China); Xiao, Gui-yong [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji’nan 250061 (China); School of Materials Science and Engineering, Shandong University, Ji’nan, 250061 (China); Suzhou Institute, Shandong University, Suzhou, 215123 (China); Lu, Yu-peng, E-mail: biosdu@sdu.edu.cn [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji’nan 250061 (China); School of Materials Science and Engineering, Shandong University, Ji’nan, 250061 (China); Suzhou Institute, Shandong University, Suzhou, 215123 (China)

    2017-03-31

    Highlights: • A chemical conversion brushite coating was prepared on titanium. • The coating exhibits fibrous morphology in micro/nano-scale. • The surface of the coating shows high hydrophilicity and corrosion resistance in the simulated body fluid. • An improvement of cell response was observed on the surface of coated Ti compared to that of the uncoated. - Abstract: Calcium phosphate coatings have been applied on the surface of Ti implants to realize better osseointegration. The formation of dicalcium phosphate dihydrate (CaHPO{sub 4}·2H{sub 2}O), mineralogically named brushite on pure Ti substrate has been investigated via chemical conversion method. Coating composition and microstructure have been investigated by X-ray diffractometer, Fourier transform infrared spectrometer and field emission scanning electron microscope. The results reveal that the coatings are composed of high crystalline brushite with minor scholzite (CaZn{sub 2}(PO{sub 4}){sub 2}·2H{sub 2}O). A micro/nano-scaled fibrous morphology can be produced in the acidic chemical conversion bath with pH 5.00. The surface of the fibrous brushite coating exhibits high hydrophilicity and corrosion resistance in the simulated body fluid. The osteoblast cells grow and spread actively on the coated samples and the proliferation numbers and alkaline phosphate activities of the cells improve significantly compared to the uncoated Ti. It is suggested that the micro/nano-fibrous brushite coating can be a potential approach to improve the osteoinductivity and osteoconductivity of Ti implant, due to its similarity in morphology and dimension to inorganic components of biological hard tissues, and favorable responses to the osteoblasts.

  3. Chemical state analysis of conversion coatings by SR-XPS and TEY-XANES

    CERN Document Server

    Noro, H; Nagoshi, M

    2002-01-01

    Chromate coatings on galvanized steel have been studied by Synchrotron Radiation (SR) based techniques that include X-ray Photoelectron Spectroscopy (XPS) and Total-Electron-Yield X-ray Absorption Near Edge Structure (TEY-XANES). Non-destructive depth profiling of the coatings by SR-XPS reveals the enhancement of Cr sup 6 sup + in the outer surface. TEY-XANES spectroscopy based on simple specimen current measurement is demonstrated as an effective technique for analyzing chemical states of conversion coatings on general bulk substrates. The sampling depth of this technique, which exceeds several tens of nanometer, is determined by the penetration length of Auger electrons excited by X-ray and the inelastic mean free path of secondary electrons excited by inelastically scattered Auger electrons. The chemical states of phosphoric acid added chromate coatings are studied using this technique. The phosphoric acid is taken into the chromate coatings as partially changed into zinc and chromium phosphates, and the r...

  4. Corrosion of AZ91D magnesium alloy with a chemical conversion coating and electroless nickel layer

    International Nuclear Information System (INIS)

    Huo Hongwei; Li Ying; Wang Fuhui

    2004-01-01

    A chemical conversion treatment and an electroless nickel plating were applied to AZ91D alloy to improve its corrosion resistance. By conversion treatment in alkaline stannate solution, the corrosion resistance of the alloy was improved to some extent as verified by immersion test and potentiodynamic polarization test in 3.5 wt.% NaCl solution at pH 7.0. X-ray diffraction patterns of the stannate treated AZ91D alloy showed the presence of MgSnO 3 · H 2 O, and SEM images indicated a porous structure, which provided advantage for the adsorption during sensitisation treatment prior to electroless nickel plating. A nickel coating with high phosphorus content was successfully deposited on the chemical conversion coating pre-applied to AZ91D alloy. The presence of the conversion coating between the nickel coating and the substrate reduced the potential difference between them and enhanced the corrosion resistance of the alloy. An obvious passivation occurred for the nickel coating during anodic polarization in 3.5 wt.% NaCl solution

  5. Study of vanadium-based chemical conversion coating on the corrosion resistance of magnesium alloy

    International Nuclear Information System (INIS)

    Yang, K.H.; Ger, M.D.; Hwu, W.H.; Sung, Y.; Liu, Y.C.

    2007-01-01

    In this study, magnesium alloy (AZ61) was immersed in vanadium containing bath with various conditions, such as the vanadium concentration, immersion time and bath temperature. The results indicate that increase of both vanadium concentration and immersion time produces a thicker conversion layer. However, when immersion time is too long, it will worsen the corrosion resistance due to the increasing of the crack density. The experimental parameter of bath temperature has no significant effect on corrosion resistance. Our results demonstrated that the better corrosion resistance coating can be obtained when the samples are submitted to an immersion in the conversion bath containing NaVO 3 with concentration of 30 g l -1 for 10 min at 80 deg. C. The presented conversion treatment has its potential to replace the chrome-based conversion coating treatment

  6. Zinc phosphate conversion coatings

    Science.gov (United States)

    Sugama, Toshifumi

    1997-01-01

    Zinc phosphate conversion coatings for producing metals which exhibit enhanced corrosion prevention characteristics are prepared by the addition of a transition-metal-compound promoter comprising a manganese, iron, cobalt, nickel, or copper compound and an electrolyte such as polyacrylic acid, polymethacrylic acid, polyitaconic acid and poly-L-glutamic acid to a phosphating solution. These coatings are further improved by the incorporation of Fe ions. Thermal treatment of zinc phosphate coatings to generate .alpha.-phase anhydrous zinc phosphate improves the corrosion prevention qualities of the resulting coated metal.

  7. Synthesis and evaluation of MgF2 coatings by chemical conversion on magnesium alloys for producing biodegradable orthopedic implants of temporary use

    International Nuclear Information System (INIS)

    Casanova, P Y; Jaimes, K J; Parada, N J; Viejo, F; Hernández-Barrios, C A; Aparicio, M; Coy, A E

    2013-01-01

    The aim of the present work was the synthesis of biodegradable MgF 2 coatings by chemical conversion on the commercial Elektron 21 and AZ91D magnesium alloys, in aqueous HF solutions for different concentrations and temperatures. The chemical composition and morphology of the coatings were analyzed by scanning electron microscopy (SEM-EDX) and X-ray diffraction (XRD). On the other hand, their corrosion behavior was evaluated by gravimetric and electrochemical measurements in Hank's solution at 37°C for different immersion times. The experimental results revealed that chemical conversion in HF produced MgF 2 coatings which corrosion resistance was enhanced by increasing the HF concentration. Further, the microstructure and composition of the base alloy played a key role on the growth and degradation mechanisms of the MgF 2 coatings

  8. Effects of pH and temperature on the deposition properties of stannate chemical conversion coatings formed by the potentiostatic technique on AZ91 D magnesium alloy

    International Nuclear Information System (INIS)

    Elsentriecy, Hassan H.; Azumi, Kazuhisa; Konno, Hidetaka

    2008-01-01

    The effects of pH and temperature of a stannate bath on the quality of stannate chemical conversion coatings formed on AZ91 D magnesium alloy by using the potentiostatic polarization technique at E = -1.1 V were investigated in order to improve uniformity and corrosion protection performance of the coating films. It was found that the uniformity and corrosion resistance of coating films deposited by potentiostatic polarization were closely associated with pH and temperature of the coating bath. The pH and temperature to obtain the best coating film were investigated as a function of corrosion protection performance evaluated by curves of potentiodynamic anodic polarization conducted in borate buffer solution. Scanning electron microscope observation and electrochemical corrosion tests of the stannate-coated samples confirmed significant improvement in uniformity and corrosion resistivity of coating films deposited by the potentiostatic technique by modifying the pH and temperature of the coating bath. It was also found that uniformity and corrosion resistivity of the coating films deposited by the potentiostatic technique were considerably improved compared to those of coatings deposited by the simple immersion method at the best conditions of pH and temperature of the coating bath

  9. Microstructure, in vitro corrosion and cytotoxicity of Ca-P coatings on ZK60 magnesium alloy prepared by simple chemical conversion and heat treatment.

    Science.gov (United States)

    Li, Kaikai; Wang, Bing; Yan, Biao; Lu, Wei

    2013-09-01

    Magnesium alloys are potential biodegradable materials for biomedical application. But their poor corrosion resistance may result in premature failure of implants. In this study, to solve this problem, Ca-P coatings were prepared on ZK60 magnesium alloy by a simple chemical conversion process and heat treatment. Surface characterization showed that a flake-like Dicalcium phosphate dihydrate (DCPD) (CaHPO₄·2H₂O) coating was formed on ZK60 alloy by the chemical conversion process. DCPD transformed into Dicalcium phosphate anhydrous (DCPa) (CaHPO₄) and Ca₂P₂O₇ after heat treatment. Results of potentiodynamic polarization showed the corrosion potential of ZK60 was increased from -1666 mV to -1566 mV with DCPD coating, while -1515 mV was obtained after heat treatment. The corrosion current density of ZK60 was measured to be reduced from 35 µA/cm² to 3.5 µA/cm² with DCPD coating, while a further reduction to 1 µA/cm² was observed after heat treatment. This indicated that the coatings improved the substrate corrosion resistance significantly, and apparently, the heat-treated coating had a higher corrosion resistance. Immersion test demonstrated that both the coatings could provide protection for the substrate and the heat-treated coating could induce deposition of bone-like apatite. Cytotoxicity evaluation revealed that none of the samples induced toxicity to L-929 cells after 1- and 3-day culture. The cytocompatibility of ZK60 was improved by the coatings, with the following sequence: uncoated ZK60 < DCPD-coated ZK60 < heat-treated coating.

  10. Effect of zinc phosphate chemical conversion coating on corrosion behaviour of mild steel in alkaline medium: protection of rebars in reinforced concrete

    International Nuclear Information System (INIS)

    Simescu, Florica; Idrissi, Hassane

    2008-01-01

    We outline the ability of zinc phosphate coatings, obtained by chemical conversion, to protect mild steel rebars against localized corrosion, generated by chloride ions in alkaline media. The corrosion resistance of coated steel, in comparison with uncoated rebars and coated and uncoated steel rebars embedded in mortar, were evaluated by open-circuit potential, potentiodynamic polarization, cronoamperometry and electrochemical impedance spectroscopy. The coated surfaces were characterized by x-ray diffraction and scanning electron microscopy. First, coated mild steel rebars were studied in an alkaline solution with and without chloride simulating a concrete pore solution. The results showed that the slow dissolution of the coating generates hydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2 . After a long immersion, the coating became dense and provided an effective corrosion resistance compared with the mild steel rebar. Secondly, the coated and uncoated steel rebars embedded in mortar and immersed in chloride solution showed no corrosion or deterioration of the coated steel. Corrosion rate is considerably lowered by this phosphate coating.

  11. Effect of zinc phosphate chemical conversion coating on corrosion behaviour of mild steel in alkaline medium: protection of rebars in reinforced concrete

    Directory of Open Access Journals (Sweden)

    Florica Simescu and Hassane Idrissi

    2008-01-01

    Full Text Available We outline the ability of zinc phosphate coatings, obtained by chemical conversion, to protect mild steel rebars against localized corrosion, generated by chloride ions in alkaline media. The corrosion resistance of coated steel, in comparison with uncoated rebars and coated and uncoated steel rebars embedded in mortar, were evaluated by open-circuit potential, potentiodynamic polarization, cronoamperometry and electrochemical impedance spectroscopy. The coated surfaces were characterized by x-ray diffraction and scanning electron microscopy. First, coated mild steel rebars were studied in an alkaline solution with and without chloride simulating a concrete pore solution. The results showed that the slow dissolution of the coating generates hydroxyapatite Ca10(PO46(OH2. After a long immersion, the coating became dense and provided an effective corrosion resistance compared with the mild steel rebar. Secondly, the coated and uncoated steel rebars embedded in mortar and immersed in chloride solution showed no corrosion or deterioration of the coated steel. Corrosion rate is considerably lowered by this phosphate coating.

  12. Chemical and structural analyses of subsurface crevices formed during spontaneous deposition of cerium-based conversion coatings

    Energy Technology Data Exchange (ETDEWEB)

    Heller, Daimon K, E-mail: dkheller@mmm.com; Fahrenholtz, William G., E-mail: billf@mst.edu; O' Keefe, Matthew J., E-mail: mjokeefe@mst.edu

    2011-11-15

    Subsurface crevices formed during the deposition of cerium-based conversion coatings were analyzed in cross-section to assess the effect of deposition and post-treatment on the structure and chemistry of phases present. An Al-O containing phase, believed to be amorphous Al(OH){sub 3}, was formed in crevices during coating deposition. Analysis by energy dispersive X-ray spectroscopy revealed the presence of up to 1.6 at.% chlorine within the Al-O phase, which was likely a product of soluble chlorides that were present in the coating solution. Cerium was not detected within crevices. After post-treatment in an 85 deg. C aqueous phosphate solution, the chloride concentration was reduced to {<=} 0.30 at.% and electron diffraction of the Al-O phase produced ring patterns, indicating it had crystallized. Some diffraction patterns could be indexed to gibbsite (Al(OH){sub 3}), but others are believed to be a combination of hydrated aluminum hydroxides and/or oxides. Aluminum phosphate was not identified. Separately from its effect on cerium-based conversion coatings, phosphate post-treatment improved the corrosion resistance of Al 2024-T3 substrates by acting to crystallize Al(OH){sub 3} present on interior surfaces of crevices and by reducing the chloride concentration in this phase. - Highlights: {yields} Analysis of subsurface crevices formed during deposition of Ce-based conversion coatings. {yields} Phosphate post-treatment improved corrosion protection in salt spray testing. {yields} Post-treatment affected the composition and structure of regions within crevices. {yields} Crystallized Al(OH){sub 3} within crevices acted as a more effective barrier to chloride ions.

  13. In Vitro Corrosion and Cytocompatibility of ZK60 Magnesium Alloy Coated with Hydroxyapatite by a Simple Chemical Conversion Process for Orthopedic Applications

    Science.gov (United States)

    Wang, Bing; Huang, Ping; Ou, Caiwen; Li, Kaikai; Yan, Biao; Lu, Wei

    2013-01-01

    Magnesium and its alloys—a new class of degradable metallic biomaterials—are being increasingly investigated as a promising alternative for medical implant and device applications due to their advantageous mechanical and biological properties. However, the high corrosion rate in physiological environments prevents the clinical application of Mg-based materials. Therefore, the objective of this study was to develop a hydroxyapatite (HA) coating on ZK60 magnesium alloy substrates to mediate the rapid degradation of Mg while improving its cytocompatibility for orthopedic applications. A simple chemical conversion process was applied to prepare HA coating on ZK60 magnesium alloy. Surface morphology, elemental compositions, and crystal structures were characterized using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction, respectively. The corrosion properties of samples were investigated by immersion test and electrochemical test. Murine fibroblast L-929 cells were harvested and cultured with coated and non-coated ZK60 samples to determine cytocompatibility. The degradation results suggested that the HA coatings decreased the degradation of ZK60 alloy. No significant deterioration in compression strength was observed for all the uncoated and coated samples after 2 and 4 weeks’ immersion in simulated body fluid (SBF). Cytotoxicity test indicated that the coatings, especially HA coating, improved cytocompatibility of ZK60 alloy for L929 cells. PMID:24300096

  14. Characterization of ceramic sol-gel coatings as an alternative chemical conversion treatment on commercial carbon steel

    International Nuclear Information System (INIS)

    Dominguez-Crespo, M.A.; Garcia-Murillo, A.; Torres-Huerta, A.M.; Carrillo-Romo, F.J.; Onofre-Bustamante, E.; Yanez-Zamora, C.

    2009-01-01

    Sol-gel yttria-stabilized zirconia (YSZ) thin films were prepared on commercial carbon steel sheets by dip-coating technique followed by a low temperature heat treatment (473, 573, and 673 K for 1 h) in order to improve both corrosion properties and adhesion. For comparison, zirconia (ZrO 2 ) coatings have been also analyzed. Electrochemical techniques, Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the anticorrosion behavior of the coatings in a 3.5 wt% NaCl solution. The adhesion with a polyester organic coating was evaluated by the pull-off technique. The typical thickness of the deposited layers ranged from 1 to 1.3 μm depending on process parameters. The obtained results indicated that sol-gel ZrO 2 and YSZ coatings without an organic coating can act as protective barriers against wet corrosion during the first hours, but they fail when the time exposure is longer than 1 day. However, when synthesized films were used as a pre-treatment and an organic coating was added (top-coated), the anticorrosive and adhesion properties were strongly affected by the temperature of the treatment, and an increase in both properties was observed at higher temperatures. The structural and morphological characteristics of the coating provide an explanation of the role of each film in the electrochemical behavior in this aggressive medium. Comparing both systems, YSZ displayed greater protective and adhesion values than exhibited for ZrO 2 which can be correlated with the stabilization of the cubic phase

  15. Characterization and corrosion behavior of phytic acid coatings, obtained by chemical conversion on magnesium substrates in physiological solution; Caracterizacion y comportamiento frente a la corrosion de recubrimientos de acido fitico, obtenidos por conversion quimica, sobre substratos de magnesio en solucion fisiologica

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Alvarado, L. A.; Lomeli, M. A.; Hernandez, L. S.; Miranda, J. M.; Narvaez, L.; Diaz, I.; Garcia-Alonso, M. C.; Escudero, M. L.

    2014-10-01

    In order to improve the corrosion resistance of biodegradable magnesium and AZ31 magnesium alloy implants, a phytic acid coating has been applied on both substrates and their protective effect against corrosion has been assessed. The morphology and the chemical nature of the conversion coating were analyzed by SEM/EDX, XRD and FTIR. The spectra showed that the conversion coating was amorphous, and it was composed of Mg, O, and P on magnesium surface, along with Al, Zn and C on AZ31 alloy. The main coating components were chelate compounds formed by phytic acid and metallic ions. The corrosion resistance of bare and coated samples was evaluated by potentiodynamic polarization technique in Hank's solution at 37 degree centigrade. The results indicate that phytic acid conversion coatings provided a very effective protection to the magnesium substrates studied. (Author)

  16. Unconventional fluoride conversion coating preparation and characterization

    Czech Academy of Sciences Publication Activity Database

    Drábiková, J.; Fintová, Stanislava; Tkacz, J.; Doležal, P.; Wasserbauer, J.

    2017-01-01

    Roč. 64, č. 6 (2017), s. 613-619 ISSN 0003-5599 Institutional support: RVO:68081723 Keywords : fluoride conversion coating * magnesium * corrosion Subject RIV: JK - Corrosion ; Surface Treatment of Materials OBOR OECD: Coating and films Impact factor: 0.364, year: 2016 http://www.emeraldinsight.com/doi/abs/10.1108/ACMM-02-2017-1757

  17. Steam initiated hydrotalcite conversion coatings

    DEFF Research Database (Denmark)

    Zhou, Lingli; Friis, Henrik; Roefzaad, Melanie

    2018-01-01

    A facile process of exploiting high-temperature steam to deposit nvironmentally friendly hydrotalcite (HT) coatings on Al alloy 6060 was developed in a spray system. Scanning electron microscopy showed the formationf a continuous and conformal coating comprised of a compact mass of crystallites. ...

  18. Examination of Nonchromate Conversion Coatings for Aluminum Armor From Three Final Candidates Using Accelerated Corrosion and Adhesion Test Methods

    National Research Council Canada - National Science Library

    Placzankis, Brian

    2001-01-01

    This study examines the effectiveness of three final candidate nonchromate conversion coatings on aluminum alloys 5083, 7039, and 6061 coated with standard solvent-based Chemical Agent Resistant Coating (CARC) system...

  19. Steam generated conversion coating on aluminium alloys

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    Aluminium and its alloys are widely used in aerospace industry owing to their high strength to weight ratio. The surface of aluminium under normal conditions has a thin oxide film (2.5-10 nm) responsible for its inherent corrosion resistance. This oxide film can further be converted or transformed...... into functional conversion coatings in order to enhance corrosion resistance and adhesion to paint systems. Chromium based conversion coatings have been extensively used on aluminium alloys to improve adhesion of subsequent paint layers and corrosion resistance. However, the use of hexavalent chromium is strictly...... regulated due to its toxic nature and suspected carcinogenicity. So, it is highly imperative to develop other alternatives for chrome conversion coatings. Treatment of aluminium with natural water at elevated temperatures results in the formation of different forms of aluminium oxide (γ-AlO(OH) , Al(OH)3...

  20. Adhesion of epoxy primer to hydrotalcite conversion coated AA2024

    Science.gov (United States)

    Leggat, Robert Benton, III

    Hydrotalcite-based (HT) conversion coatings are being developed as an environmentally benign alternative to chromate conversion coatings (CCC). Accelerated exposure tests were conducted on epoxy primed, HT-modified AA2024 to gauge service performance. HT-based conversion coatings did not perform as well as the CCC when used with an epoxy primer. The current HT chemistries are optimized for stand-alone corrosion protection, however additional research into the primer/HT interactions is necessary before they can be implemented within a coating scheme. The relative contribution of mechanical and physico-chemical interactions in controlling adhesion has been investigated in this study. Practical adhesion tests were used to assess the dry and wet bond strength of epoxy primer on HT coatings using the pull-off tensile strength (POTS) as the figure of merit. The practical adhesion of HT coated samples generally fell between that observed for the CCC and bare AA2024. Laboratory testing was done to assess the physical and chemical properties of HT coatings. Contact angle measurements were performed using powders representative of different HT chemistries to evaluate the dispersive and acid-base character of the surface. The wet POTS correlated with the electrodynamic (dipole + dispersive) parameter of the surface tension. The HT surfaces were found to be predominantly basic. Given the basicity of epoxy, these results indicate that increasing the acidic character of HT coatings may increase the adhesion performance. This was supported by electrokinetic measurements in which the dry POTS was found to increase with decreasing conversion coating iso-electric point. The correlations with the dry and wet state adhesion are interpreted as indicating that dry state adhesion is optimized by minimizing unfavorable polar interactions between the basic epoxy and HT interfaces. Wet state adhesion, where polar interactions are disrupted, is dictated by non-polar bonding. FTIR

  1. Solar energy conversion. Chemical aspects

    Energy Technology Data Exchange (ETDEWEB)

    Likhtenshtein, Gertz [Ben-Gurion Univ. of the Negev, Beersheba (Israel). Dept. of Chemistry

    2012-07-01

    Finally filling a gap in the literature for a text that also adopts the chemist's view of this hot topic, Professor Likhtenshtein, an experienced author and internationally renowned scientist, considers different physical and engineering aspects in solar energy conversion. From theory to real-life systems, he shows exactly which chemical reactions take place when converting light energy, providing an overview of the chemical perspective from fundamentals to molecular harvesting systems and solar cells. This essential guide will thus help researchers in academia and industry better understand solar energy conversion, and so ultimately help this promising, multibillion euro/dollar field to expand. (orig.)

  2. Performance Comparison of Steam-Based and Chromate Conversion Coatings on Aluminum Alloy 6060

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-01-01

    In this study, oxide layers generated on aluminum alloy 6060(UNS A96060) using a steam-based process were compared with conventional chromate and chromate-phosphate conversion coatings. Chemical composition and microstructure of the conversion coatings were investigated and their corrosion perfor...

  3. Microstructure and corrosion resistance of Ce–V conversion coating on AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Jiang, Xiao; Guo, Ruiguang; Jiang, Shuqin

    2015-01-01

    Highlights: • Through simple chemical conversion process, a Ce–V conversion coating is prepared on AZ31 magnesium alloy. The coating (∼2 μm thick) has a duplex structure and is composed of Mg, Al, Ce, V and O in the outer layer and Mg, Al, V, F and O in the inner layer. • The Ce–V conversion coating can increase the E corr by 157 mV and decrease the i corr by 80 times compared to AZ31 magnesium alloy substrate. Moreover, the performance of the Ce–V conversion coating excels the chromate conversion coating on AZ31 magnesium alloy. • The EIS results of Ce–V conversion coating indicate an increase of 10× in the corrosion resistance and a delay in the corrosion process kinetics compared to uncoated AZ31 magnesium alloy in 3.5 wt.% NaCl solution. • The ball cratering is a simple and effective technique of thickness measurement for chemical conversion coating. - Abstract: A Ce–V conversion coating was developed to improve the corrosion resistance of AZ31 magnesium alloy. Scanning electronic microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrometer (XPS), grazing incidence X-ray diffraction (GIXRD) and the ball cratering test were adopted to study the morphology, chemical composition, structure and thickness of the coating. The coating has duplex structure with network and its thickness is about 2 μm. The coating contains high contents of Ce and V, which exhibits amorphous structure. Potentiodynamic polarization shows the coating can increase the corrosion potential and reduce the corrosion current density of AZ31 magnesium alloy. Moreover, the electrochemical impedance spectra exhibit the coating significantly improves the corrosion resistance of AZ31 magnesium alloy. Results indicate that the Ce–V conversion coating can provide effective protection to AZ31 magnesium alloy

  4. Microstructure and corrosion resistance of Ce–V conversion coating on AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiao, E-mail: xiaoxiao217@126.com; Guo, Ruiguang; Jiang, Shuqin

    2015-06-30

    Highlights: • Through simple chemical conversion process, a Ce–V conversion coating is prepared on AZ31 magnesium alloy. The coating (∼2 μm thick) has a duplex structure and is composed of Mg, Al, Ce, V and O in the outer layer and Mg, Al, V, F and O in the inner layer. • The Ce–V conversion coating can increase the E{sub corr} by 157 mV and decrease the i{sub corr} by 80 times compared to AZ31 magnesium alloy substrate. Moreover, the performance of the Ce–V conversion coating excels the chromate conversion coating on AZ31 magnesium alloy. • The EIS results of Ce–V conversion coating indicate an increase of 10× in the corrosion resistance and a delay in the corrosion process kinetics compared to uncoated AZ31 magnesium alloy in 3.5 wt.% NaCl solution. • The ball cratering is a simple and effective technique of thickness measurement for chemical conversion coating. - Abstract: A Ce–V conversion coating was developed to improve the corrosion resistance of AZ31 magnesium alloy. Scanning electronic microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrometer (XPS), grazing incidence X-ray diffraction (GIXRD) and the ball cratering test were adopted to study the morphology, chemical composition, structure and thickness of the coating. The coating has duplex structure with network and its thickness is about 2 μm. The coating contains high contents of Ce and V, which exhibits amorphous structure. Potentiodynamic polarization shows the coating can increase the corrosion potential and reduce the corrosion current density of AZ31 magnesium alloy. Moreover, the electrochemical impedance spectra exhibit the coating significantly improves the corrosion resistance of AZ31 magnesium alloy. Results indicate that the Ce–V conversion coating can provide effective protection to AZ31 magnesium alloy.

  5. Conversion electron Moessbauer spectroscopic studies on the chemical states of surface layers of corroded tin plates and tin-coated iron plates

    International Nuclear Information System (INIS)

    Kato, Akinori; Endo, Kazutoyo; Sano, Hirotoshi

    1980-01-01

    By means of the conversion electron Moessbauer spectroscopy (CEMS), we studied surface layers of ''tin'' plates and tin-coated iron plates corroded by various acids. Transmission Moessbauer spectra and X-ray diffraction patterns were also measured. Metastannic acid was formed, when the ''tin'' plate was corroded by nitric acid solution. In corrosion by phosphoric acid solution, the X-ray diffractometry revealed the formation of tin(IV) pyrophosphate. In corrosion by various organic acid solutions, the formation of oxides was identified by the 119 Sn CEMS, but not by the X-ray diffractometry because of the too thin corrosion layer. In corrosion of tin-coated iron plates, maleic acid, malonic acid, formic acid, and oxalic acid were used. It was determined by CEMS that the corrosion products caused by these acids were tin(IV) oxides, although they could not be identified by the X-ray diffractometry. CEMS also confirmed that the surface of uncorroded tin-coated iron plate was already oxidized by air. Colorimetric determinations of Sn and Fe dissolved from tin-coated iron plates to various acid solutions confirmed that maleic acid had the strongest corrosion effect among the organic acids studied. (author)

  6. Protective coatings on structural materials for energy conversion systems

    International Nuclear Information System (INIS)

    John, J.T.; De, P.K.; Srinivasa, R.S.

    2000-01-01

    Full text: Structural Materials and Components used in coal fired energy conversion systems, crude oil refineries and coal gasification plants are subjected to degradation due to oxidation, sulfidation, carbonization and halogenation. Suitable protective coatings can significantly enhance their life. Protective coatings work by forming a highly stable, self-healing and slow growing protective scale at the operating temperatures. These scales act as barriers between the corrosive environment and the alloy and prevent degradation of the substitute. Three types of scales that provide such protection are based on Al 2 O 3 , Cr 2 O 3 and SiO 2 . Aluminide coatings are major alumina forming protecting coatings, applied on nickel, cobalt and iron base alloys. Aluminide coatings are prepared by enriching the surface of a component by aluminum. In this paper the formation of aluminide coatings of nickel, IN738, Alloy 800, Zircaloy-2 and pure iron by chemical vapor deposition has been described. In this technique, Aluminum chloride vapors from bath kept at 353-373 K are carried in a stream of hydrogen gas into a Hot Walled CVD chamber kept at 1173-1373 K. The AlCl 3 vapors were allowed to react with pure aluminum whereby aluminum sub-chlorides like AlCl and AlCl 2 are produced which deposit aluminum on the substrates. At the high temperature of the deposition, aluminum diffuses into the substrate and forms the aluminide coating. The process can be represented by the reaction Al (i) + AlCl 3(g) AlCl 2(s) + AlCl 2 (g) . XRD and optical microscopic studies have characterized the coatings. On pure nickel and Alloy 800 the coating consists of Ni 2 Al 3 and NiAl respectively. On pure iron the coatings consisted of FeAl. On Zircaloy-2, ZrAl 2 was also detected. The CVD coating process, XRD and optical microscopy data will be discussed further

  7. Molybdate and molybdate/permanganate conversion coatings on Mg-8.5Li alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guixiang, E-mail: wgx0357@126.com [Key Laboratory of Superlight Material and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Zhang Milin; Wu Ruizhi [Key Laboratory of Superlight Material and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)

    2012-01-15

    A novel environment-friendly conversion coating for Mg-8.5Li alloy was obtained by immersing in a solution of molybdate. The concentration of ammonium molybdate and the addition of potassium permanganate were discussed in this experiment. The surface morphology of the conversion coatings was observed by scanning electron microscopy (SEM), and the chemical composition was investigated by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Mg-8.5Li alloy and conversion coatings were investigated by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurement. The results showed that the coatings with cracked morphology were homogeneous and uniform. The conversion coatings were mainly composed of metal-oxide as detected by XPS. The results of electrochemical measurement and weight loss measurement revealed that the molybdate conversion coating had better corrosion resistance than bare alloy and chromate conversion coating, and the molybdate/permanganate conversion coating had lower corrosion current density and higher coating resistance than the molybdate conversion coating.

  8. Molybdate and molybdate/permanganate conversion coatings on Mg-8.5Li alloy

    International Nuclear Information System (INIS)

    Wang Guixiang; Zhang Milin; Wu Ruizhi

    2012-01-01

    A novel environment-friendly conversion coating for Mg-8.5Li alloy was obtained by immersing in a solution of molybdate. The concentration of ammonium molybdate and the addition of potassium permanganate were discussed in this experiment. The surface morphology of the conversion coatings was observed by scanning electron microscopy (SEM), and the chemical composition was investigated by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Mg-8.5Li alloy and conversion coatings were investigated by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurement. The results showed that the coatings with cracked morphology were homogeneous and uniform. The conversion coatings were mainly composed of metal-oxide as detected by XPS. The results of electrochemical measurement and weight loss measurement revealed that the molybdate conversion coating had better corrosion resistance than bare alloy and chromate conversion coating, and the molybdate/permanganate conversion coating had lower corrosion current density and higher coating resistance than the molybdate conversion coating.

  9. Combustion chemical vapor desposited coatings for thermal barrier coating systems

    Energy Technology Data Exchange (ETDEWEB)

    Hampikian, J.M.; Carter, W.B. [Georgia Institute of Technology, Atlanta, GA (United States)

    1995-10-01

    The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings.

  10. An environment-friendly phosphate chemical conversion coating on novel Mg-9Li-7Al-1Sn and Mg-9Li-5Al-3Sn-1Zn alloys with remarkable corrosion protection

    Science.gov (United States)

    Maurya, Rita; Siddiqui, Abdul Rahim; Balani, Kantesh

    2018-06-01

    An environment-friendly phosphate chemical conversion (PCC) coating has been deposited on novel LAT971 (Mg-9 wt%Li-7 wt%Al-1 wt%Sn) and LATZ9531 (Mg-9 wt%Li-5 wt%Al-3 wt%Sn-1 wt%Zn) alloys for improving their corrosion resistance. A dense and homogeneous flower like morphology (∼30 μm thick) was observed on the PCC coated Mg-Li based alloys. The presence of calcium hydrogen phosphate hydrate, tricalcium phosphate and trimagnesium phosphate were confirmed from the X-ray diffraction and X-ray photoelectron spectroscopy analysis. A lower corrosion current density of 6.74 × 10-7 mA/cm2 and 5.39 × 10-7 mA/cm2 was obtained for PCC coated alloys in 3.5% NaCl aqueous solution than that of uncoated LAT971 (0.82 mA/cm2) and LATZ9531 (0.34 mA/cm2) alloys, respectively, which offers corrosion protection efficiency of >99%. Electrochemical impedance spectroscopy (EIS) has revealed that the inner PCC coating (at coating/substrate interface) delay the direct contact between electrolyte and substrate, which offered higher charge transfer resistance (>4 orders of magnitude) than that of uncoated alloys. Thus, the PCC coating provides an effective corrosion protection to the ultra-lightweight LAT971 and LATZ9531 alloys surface and may be helpful in proving good anchoring with the top organic coatings or paints.

  11. Rare earth conversion coating on Mg-8.5Li alloys

    International Nuclear Information System (INIS)

    Yang Xiaowei; Wang Guixiang; Dong Guojun; Gong Fan; Zhang Milin

    2009-01-01

    The conversion coating formed by immersion in a solution containing rare earth salt on Mg-8.5Li alloy was studied and the corrosion resistance was evaluated as well. The surface morphology was observed by scanning electron microscopy (SEM), and the chemical composition was characterized by X-ray photoelectron spectroscopy (XPS). The corrosion behaviors of Mg-8.5Li alloy and conversion coating were assessed by means of potentiodynamic polarization curves, electrochemical impedance spectra (EIS) and immersion tests. The experimental results indicated that the coating with cracked morphology was homogeneous. It was mainly composed of La 2 O 3 , CeO 2 , Mn 2 O 3 and MnO 2 as detected by XPS. The results of electrochemical measurements and immersion tests revealed that the rare earth conversion coating possessed better corrosion resistance than bare alloy and chromate conversion coating.

  12. Chromate conversion coatings and their current application

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2016-04-01

    Full Text Available This paper describes formation, composition and possible production technologies of application chromate coatings. Summation of common examples of applications of these coatings in corrosion protection of metals and alloys is provided. Individual chromate coatings are divided by their dominant anions either with CrVI or CrIII. Restrictions of chromate coatings with dominantly CrVI and related toxicity of hexavalent chromium is discussed in detail. In conclusion, examples of both chromium and other, alternative coatings are summed up. Application of these coatings as a protection for concrete hot-dip galvanized reinforcement is also reviewed.

  13. Composition and Performance of Nanostructured Zirconium Titanium Conversion Coating on Aluminum-Magnesium Alloys

    Directory of Open Access Journals (Sweden)

    Sheng-xue Yu

    2013-01-01

    Full Text Available Nanostructured conversion coating of Al-Mg alloy was obtained via the surface treatment with zirconium titanium salt solution at 25°C for 10 min. The zirconium titanium salt solution is composed of tannic acid 1.00 g·L−1, K2ZrF6 0.75 g·L−1, NaF 1.25 g·L−1, MgSO4 1.0 g/L, and tetra-n-butyl titanate (TBT 0.08 g·L−1. X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and Fourier transform infrared spectrum (FT-IR were used to characterize the composition and structure of the obtained conversion coating. The morphology of the conversion coating was obtained by atomic force microscopy (AFM and scanning electron microscopy (SEM. Results exhibit that the zirconium titanium salt conversion coating of Al-Mg alloy contains Ti, Zr, Al, F, O, Mg, C, Na, and so on. The conversion coating with nm level thickness is smooth, uniform, and compact. Corrosion resistance of conversion coating was evaluated in the 3.5 wt.% NaCl electrolyte through polarization curves and electrochemical impedance spectrum (EIS. Self-corrosion current density on the nanostructured conversion coating of Al-Mg alloy is 9.7×10-8A·cm-2, which is only 2% of that on the untreated aluminum-magnesium alloy. This result indicates that the corrosion resistance of the conversion coating is improved markedly after chemical conversion treatment.

  14. Microstructure and electrochemical behavior of cerium conversion coating modified with silane agent on magnesium substrates

    Science.gov (United States)

    Lei, Li; Shi, Jing; Wang, Xin; Liu, Dan; Xu, Haigang

    2016-07-01

    The cerium conversion coating with and without different concentrations of silane agent bis-(γ-triethoxysilylpropyl)-tetrasulfide (BTESPT) modification is obtained on magnesium alloys. Detailed properties of the coatings and the role of BTESPT as an additive are studied and followed with careful discussion. The coating morphology, wettability, chemical composition and corrosion resistance are characterized by scanning electronic microscope (SEM), water contact-angle, X-ray photoelectron spectroscopy (XPS), potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of the coatings is investigated using EIS. The results indicate that the coating morphology and composition can be controlled by changing silane concentration. The combination of cerium ions and silane molecules could promote the formation of more homogenous and higher hydrophobic coating. The coating turns to be more compact and the adhesive strength between the coating and the magnesium substrate are strongly improved with the formation of Sisbnd Osbnd Si and Sisbnd Osbnd M chemical bonds. The optimum corrosion resistance of the coating in the corrosive media is obtained by 25 ml L-1 BTESPT modification. This whole study implies that the cerium conversion coating modified with certain silane agent deserves cautiousness before its application for corrosion resistance.

  15. Study of electrochemical phosphate conversion coating of metallic surfaces

    International Nuclear Information System (INIS)

    Gougelin, Patrick

    1985-01-01

    After an overview on phosphate conversion coating processes, on models of iron electrochemical dissolution, on the passivation phenomenon, and on the phosphate conversion coating treatment, this research thesis reports a detailed study of this last process. The author presents the experimental method, reports the study of this process and of passivation under constant polarization. He reports the use of various techniques and conditions: chrono-amperometry, chrono-potentiometry, cyclic volt-amperometry

  16. Studies on Chromium-free Conversion coatings on Aluminum | Oki ...

    African Journals Online (AJOL)

    The development of a chromium-free conversion coating on aluminum has been studied using transmission electron microscopy (TEM), Auger Electron (AES) and Secondary ion mass spectroscopy (SIMS) techniques. Within the limits of the resolution of the TEM, the coating is uniformly clear and featureless. It is composed ...

  17. Effect of Zn content on the chemical conversion treatments of AZ91D magnesium alloy

    International Nuclear Information System (INIS)

    Hu Lifang; Meng Qingsen; Chen Shaoping; Wang Hao

    2012-01-01

    Highlights: ► The effect of Zn content on the chemical conversion process of Mg alloy was studied. ► The coating thickness grows up with the increase of the Zn content. ► The corrosion resistance of the coating is comparable if the Zn content below 2 wt.%. ► The corrosion resistance of the coating became poorer if the Zn content beyond 2 wt.%. - Abstract: In this study, four AZ91D magnesium plates with different Zn content were treated with chemical conversion treatments. The chemical conversion coating was examined using scanning electron microscope, optical microscope and glow discharge optical emission spectrometer. The testing results indicated that increase in Zn content produced a thicker chemical conversion coating. However, when the Zn content exceeded 2 wt.%, the thickness of the chemical conversion coating decreased. To investigate the chemical conversion mechanism, potentiodynamic polarization and electrochemical impedance spectroscopy were employed to evaluate the corrosion resistance of the magnesium substrate in 3.5 wt.% NaCl solution.

  18. Zr-based conversion coatings for multi-metal substrates

    NARCIS (Netherlands)

    Cerezo Palacios, J.M.

    2015-01-01

    In this PhD work, a new surface treatment based on the application of Zr-based conversion coatings by immersion in a Cu containing Zr-based conversion solution was investigated as a replacement of the traditional phosphating process for the automotive industry. Nowadays most of the cars are made of

  19. Adhesion and corrosion studies of a lithium based conversion coating film on the 2024 aluminum alloy

    International Nuclear Information System (INIS)

    Castro, M.R.S.; Nogueira, J.C.; Thim, G.P.; Oliveira, M.A.S.

    2004-01-01

    AA2024-T3-aluminum alloy surfaces were coated using non-chromate and chromate conversion coatings. All coatings were painted with the 10P4-2-primer epoxy resin. Independent on the film formation process, films passed on the substrate/conversion coating wet tape adhesion test. However, only the chromate conversion coating passed on the conversion coating/primer epoxy resin adhesion test. Electrochemical corrosion measurements showed that non-chromate conversion coated surfaces present lower corrosion current density, bigger polarization resistance and less negative corrosion potential than chromate conversion coated surfaces

  20. Effect of HCl pre-treatment on corrosion resistance of cerium-based conversion coatings on magnesium and magnesium alloys

    International Nuclear Information System (INIS)

    Brunelli, Katya; Dabala, Manuele; Calliari, Irene; Magrini, Maurizio

    2005-01-01

    The corrosion protection afforded by a cerium conversion coating, formed by immersion in a solution containing rare earth salt and hydrogen peroxide, on pure magnesium and two magnesium alloys, AZ91 and AM50, has been studied. The effect of HCl pre-treatments on the morphology and on the corrosion resistance of the cerium conversion layer was investigated. A thicker and more homogeneous distribution of the conversion coating was obtained when the sample surface was pre-treated with acid. Higher amounts of cerium on the surface of the pre-treated samples were detected. The cerium conversion coating increased the corrosion resistance of the alloys because it ennobled the corrosion potential and decreased both the anodic and cathodic current. The acid pre-treatment further increased the corrosion resistance of the coated alloys. After five days of immersion in chloride environment the untreated samples showed localized corrosion while the chemical conversion coated samples appeared unaffected

  1. Microstructure and electrochemical behavior of cerium conversion coating modified with silane agent on magnesium substrates

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Li; Shi, Jing, E-mail: shijing@ouc.edu.cn; Wang, Xin, E-mail: wangxin.hd@163.com; Liu, Dan; Xu, Haigang

    2016-07-15

    Graphical abstract: The unmodified coating shows averaged static water contact angles of a little more than 50º, which is clearly hydrophilic for water solutions. With the silane concentration increases, the water contact angles show an increase tendency. Especially, when the silane addition is increased to 25 ml L-1, the coating surface presents a hydrophobic feature, with static water contact angle of more than 110º. - Highlights: • BTESPT modification can effectively improve the uniformity, hydrophobic performance, chemical stability and corrosion inhibition capability of traditional cerium conversion coating. • Si-O-Si linkage builds a robust structure to increase of the coating density. Si−O−Mg bonds strengthen the adhesion between the coating/substrate. • The system modified with 25 ml L{sup −1} BTESPT displays the optimum corrosion protection performance. - Abstract: The cerium conversion coating with and without different concentrations of silane agent bis-(γ-triethoxysilylpropyl)-tetrasulfide (BTESPT) modification is obtained on magnesium alloys. Detailed properties of the coatings and the role of BTESPT as an additive are studied and followed with careful discussion. The coating morphology, wettability, chemical composition and corrosion resistance are characterized by scanning electronic microscope (SEM), water contact-angle, X-ray photoelectron spectroscopy (XPS), potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of the coatings is investigated using EIS. The results indicate that the coating morphology and composition can be controlled by changing silane concentration. The combination of cerium ions and silane molecules could promote the formation of more homogenous and higher hydrophobic coating. The coating turns to be more compact and the adhesive strength between the coating and the magnesium substrate are strongly improved with the formation of Si−O−Si and Si

  2. Microstructure and electrochemical behavior of cerium conversion coating modified with silane agent on magnesium substrates

    International Nuclear Information System (INIS)

    Lei, Li; Shi, Jing; Wang, Xin; Liu, Dan; Xu, Haigang

    2016-01-01

    Graphical abstract: The unmodified coating shows averaged static water contact angles of a little more than 50º, which is clearly hydrophilic for water solutions. With the silane concentration increases, the water contact angles show an increase tendency. Especially, when the silane addition is increased to 25 ml L-1, the coating surface presents a hydrophobic feature, with static water contact angle of more than 110º. - Highlights: • BTESPT modification can effectively improve the uniformity, hydrophobic performance, chemical stability and corrosion inhibition capability of traditional cerium conversion coating. • Si-O-Si linkage builds a robust structure to increase of the coating density. Si−O−Mg bonds strengthen the adhesion between the coating/substrate. • The system modified with 25 ml L"−"1 BTESPT displays the optimum corrosion protection performance. - Abstract: The cerium conversion coating with and without different concentrations of silane agent bis-(γ-triethoxysilylpropyl)-tetrasulfide (BTESPT) modification is obtained on magnesium alloys. Detailed properties of the coatings and the role of BTESPT as an additive are studied and followed with careful discussion. The coating morphology, wettability, chemical composition and corrosion resistance are characterized by scanning electronic microscope (SEM), water contact-angle, X-ray photoelectron spectroscopy (XPS), potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of the coatings is investigated using EIS. The results indicate that the coating morphology and composition can be controlled by changing silane concentration. The combination of cerium ions and silane molecules could promote the formation of more homogenous and higher hydrophobic coating. The coating turns to be more compact and the adhesive strength between the coating and the magnesium substrate are strongly improved with the formation of Si−O−Si and Si−O−M chemical

  3. Electrical conductivity of chromate conversion coating on electrodeposited zinc

    International Nuclear Information System (INIS)

    Tencer, Michal

    2006-01-01

    For certain applications of galvanized steel protected with conversion coatings it is important that the surface is electrically conductive. This is especially important with mating surfaces for electromagnetic compatibility. This paper addresses electrical conductivity of chromate conversion coatings. A cross-matrix study using different zinc plating techniques by different labs showed that the main deciding factor is the type of zinc-plating bath used rather than the subsequent chromating process. Thus, chromated zinc plate electrodeposited from cyanide baths is non-conductive while that from alkaline (non-cyanide) and acid baths is conductive, even though the plate from all the bath types is conductive before conversion coating. The results correlate well with the microscopic structure of the surfaces as observed with scanning electron microscopy (SEM) and could be further corroborated and rationalized using EDX and Auger spectroscopies

  4. Stannate conversion coatings on Mg-8Li alloy

    International Nuclear Information System (INIS)

    Yang Lihui; Zhang Milin; Li Junqing; Yu Xiang; Niu Zhongyi

    2009-01-01

    The stannate conversion coatings (SnCC) on Mg-8Li alloy were investigated by simple immersion method. The surface morphology and composition were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction spectroscopy (XRD) techniques. The corrosion resistance was assessed by means of potentiodynamic polarization measurements and electrochemical impedance spectra (EIS). The effects of time of a stannate bath on the quality of stannate conversion coatings were investigated by SEM and EIS. It was found that the coating particles were mainly composed of hemispherical particles MgSnO 3 .3H 2 O. A comparison of results revealed the coating treated for 60 min exhibited the most uniform, dense and corrosion-resistant

  5. Growth of permanganate conversion coating on 2024-Al alloy

    International Nuclear Information System (INIS)

    Kulinich, S.A.; Akhtar, A.S.; Wong, P.C.; Wong, K.C.; Mitchell, K.A.R.

    2007-01-01

    The growth of permanganate conversion coating on aluminum 2024-T3 alloy has been studied by characterizing, with scanning Auger microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy, the coatings formed by immersion of the alloy in the coating bath (containing KMnO 4 and Na 2 B 4 O 7 , pH 9.1) for different periods of time and at different temperatures. At room temperature, during the first 1-5 min of immersion, MnO 2 deposits are formed only on the second-phase intermetallic particles (of Al-Cu-Mg and Al-Cu-Fe-Mn types), but the coating starts to develop on the Al matrix surface after 5-10 min. The coating slows down and stops after about 150 min, with a thinner deposit over the alloy matrix. The process is accelerated at higher temperatures, for example at 68 deg. C it self-limits after about 3 min. The electrochemical growth process appears to follow that established for the chromate conversion coatings, although XPS does not detect significant MnO 4 - incorporation into the permanganate coatings

  6. Energy conversion technology by chemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Oh, I W; Yoon, K S; Cho, B W [Korea Inst. of Science and Technology, Seoul (Korea, Republic of); and others

    1996-12-01

    The sharp increase in energy usage according to the industry development has resulted in deficiency of energy resources and severe pollution problems. Therefore, development of the effective way of energy usage and energy resources of low pollution is needed. Development of the energy conversion technology by chemical processes is also indispensable, which will replace the pollutant-producing and inefficient mechanical energy conversion technologies. Energy conversion technology by chemical processes directly converts chemical energy to electrical one, or converts heat energy to chemical one followed by heat storage. The technology includes batteries, fuel cells, and energy storage system. The are still many problems on performance, safety, and manufacturing of the secondary battery which is highly demanded in electronics, communication, and computer industries. To overcome these problems, key components such as carbon electrode, metal oxide electrode, and solid polymer electrolyte are developed in this study, followed by the fabrication of the lithium secondary battery. Polymer electrolyte fuel cell, as an advanced power generating apparatus with high efficiency, no pollution, and no noise, has many applications such as zero-emission vehicles, on-site power plants, and military purposes. After fabricating the cell components and operating the single cells, the fundamental technologies in polymer electrolyte fuel cell are established in this study. Energy storage technology provides the safe and regular heat energy, irrespective of the change of the heat energy sources, adjusts time gap between consumption and supply, and upgrades and concentrates low grade heat energy. In this study, useful chemical reactions for efficient storage and transport are investigated and the chemical heat storage technology are developed. (author) 41 refs., 90 figs., 20 tabs.

  7. Effect of coating parameters on the microstructure of cerium oxide conversion coatings

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Benedict Y.; Edington, Joe; O' Keefe, Matthew J

    2003-11-25

    The microstructure and morphology of cerium oxide conversion coatings prepared under different deposition conditions were characterized by transmission electron microscopy (TEM). The coatings were formed by a spontaneous reaction between a water-based solution containing CeCl{sub 3} and aluminum alloy 7075-T6 substrates. Microstructural characterization was performed to determine the crystallinity of the coatings and to obtain a better understanding of the deposition parameters on coating microstructure. The results of TEM imaging and electron diffraction analysis indicated that the as-deposited coating was composed of nanocrystalline particles of a previously unreported cerium compound. The particles of the coatings produced using glycerol as an additive were found to be much finer than those of the coatings prepared in the absence of glycerol. This indicates that glycerol may act as a grain refiner and/or growth inhibitor during coating deposition. After deposition, the coated panels were treated for 5 min in a phosphate sealing solution. The sealing treatment converted the as-deposited coating into hydrated cerium phosphate. Panels coated from solutions containing no glycerol followed by phosphate sealing performed poorly in salt fog tests. With glycerol addition, the corrosion resistance of the coatings that were phosphate sealed improved considerably, achieving an average passing rate of 85%.

  8. Chemical Processing of Nanostructured Coatings

    Science.gov (United States)

    2000-01-01

    in the literature ranging from IR imaging to anti-scratch to smart windows and waveguides. Uhlmann and Towee have taken a survey of the sol-gel...Proteins and enzymes can be encapsulated in silica glass (12), while still retaining their activity. Sol-gel coatings (13,14) of hydroxyapatite should also...Technology, 13, 261-65. 14. Lolpatin, C. M. Pizziloni, V., Alford, T. L., and Lawsaon, T (1998) Hydroxyapatite powders ad thin films prepared by sol

  9. Anti-corrosive Conversion Coating on Aluminium Alloys Using High Temperature Steam

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    or convert to a functional conversion coating. In the last several decades chromate conversion coating (CrCCs) have been the most common conversion coatings used for aluminium alloys. Due to the toxicity of the hexavalent chrome, however, environmental friendly alternatives to CrCCs have been investigated...

  10. Influence of phytic acid concentration on performance of phytic acid conversion coatings on the AZ91D magnesium alloy

    International Nuclear Information System (INIS)

    Cui Xiufang; Li Ying; Li Qingfen; Jin Guo; Ding Minghui; Wang Fuhui

    2008-01-01

    In this study, the phytic acid conversion coating, a new environmentally friendly chemical protective coating for magnesium alloys, was prepared. The influences of phytic acid concentration on the formation process, microstructure, chemical state and corrosion resistance of the conversion coatings on AZ91D magnesium alloy were investigated by means of weight gain measurement, field-emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS), respectively. And the depth profile of all elements in the optimal conversion coatings was analyzed by auger electron spectroscopy (AES). The results show that the growth, microstructure, chemical state and corrosion resistance of the conversion coatings are all obviously affected by the phytic acid concentration. The concentration of 5 g l -1 corresponds to the maximum weight gain. The main elements of the coating are Mg, Al, O, P, and C, which are distributed gradually in depth. The functional groups of conversion coatings formed in higher concentration phytic acid solution are closer to the constituent of phytic acid than those formed in lower concentration phytic acid solution. The coatings formed in 1-5 g l -1 are integrated and uniform. However, those formed in 20-50 g l -1 have some micro-cracks on the α phase. The coating formed in 5 g l -1 has the best corrosion resistance, whose open circuit current density decreases about six orders than that of the untreated sample, although the coatings deposited in 1-20 g l -1 can all improve the corrosion resistance of AZ91D

  11. Advanced materials and coatings for energy conversion systems

    Energy Technology Data Exchange (ETDEWEB)

    St Pierre, George R. [Ohio State Univ., Materials Science and Engineering Dept., Columbus, OH (United States)

    1997-12-31

    Following an historical review of the development of high-temperature alloys for energy conversion systems including turbine engines, some of the current advances in single crystal materials, intermetallics, metal-matrix composites, and ceramic-matrix composites are discussed. Particular attention is directed at creep phenomena, fatigue properties and oxidation resistance. Included within the discussions is the current status of carbon/carbon composites as potential high-temperature engineering materials and the development of coating systems for thermal barrier and oxidation protection. The specific influences of combustion gas compositions, i.e., oxidation potential, sulfur, halides, etc. are discussed. A current list of eligible advanced materials and coatings systems is presented and assessed. Finally, the critical failure mechanism and life-prediction parameters for some of the new classes of advanced structural materials are elaborated with the view to achieving affordability and extended life with a high degree of reliability. Examples are drawn from a variety of energy conversion systems. (Author)

  12. Preparation of Trivalent Chromium and Rare Earth Composite Conversion Coating on Aluminum Alloy Surface

    Science.gov (United States)

    Huang, Jianzhen

    2018-01-01

    In this paper, the surface conversion film on 6063 aluminum alloy was prepared by chemical plating process with chromium sulfate, lanthanum sulfate and sodium phosphate as film forming agent. The corrosion resistance and surface morphology of the conversion film were analyzed by pitting corrosion test of copper sulfate and SEM. The results show that when Cr2(SO4)3 is 10 g/L, La2(SO4)3 is 2 g/L, Na3PO4 is 8 g/L, pH value is 3, temperature is 40 °C, reaction time is 10 min, the corrosion resistance of the surface conversion film is the best. The conversion coating is light green, composed of Cr, La, P, Al, O and other elements.

  13. Laboratory Validation and Demonstrations of Non-Hexavalent Chromium Conversion Coatings for Steel Substrates (Briefing Charts)

    Science.gov (United States)

    2011-02-01

    UNCLASSIFIED: Approved for public release; distribution unlimited. Laboratory Validation and Demonstrations of Non- Hexavalent Chromium Conversion...00-00-2011 4. TITLE AND SUBTITLE Laboratory Validation and Demonstrations of Non- Hexavalent Chromium Conversion Coatings for Steel Substrates 5a...to MRAP II Acquisition Pretreatment /conversion coatings omitted: • Hex- chrome pretreatments prohibited for new ground vehicles • Hydrogen

  14. Glass enamel and glass-ceramic coatings for chemical apparatus

    International Nuclear Information System (INIS)

    Es'kov, A.S.; Oleinik, M.I.; Shabrova, E.A.

    1984-01-01

    Among the known anticorrosion coatings used in chemical engineering, glass enamel base coatings are distinguished by such advantages as a high degree of continuity and chemical resistance. The paper describes basic principles for the creation of acid and alkali resistant glass enamel and ceramic coatings for chemical apparatus. As the result of investgations, glass enamel coatings with increased electrical conductivity and also experimental production compositions of chemical, temperature and radiation resistant coatings for protection of chemical equipment of 12Kh18N10T stainless steel have been developed. The coatings have successfully passed testing under service conditions. A new type of coating is short-term glass enamel, which may be recommended for use in chemical machinery manufacturing and other branches of industry in oxidation-free heating and forming of stainless steels

  15. Molybdate/phosphate composite conversion coating on magnesium alloy surface for corrosion protection

    International Nuclear Information System (INIS)

    Yong Zhiyi; Zhu Jin; Qiu Cheng; Liu Yali

    2008-01-01

    In this paper, a new conversion coating-molybdate/phosphate (Mo/P) coating on magnesium alloy was prepared and investigated by electrochemical impedance spectra (EIS), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and salt-water immersion experiments, respectively. The results demonstrated that the Mo/P coating contained composite phases, which were consisted of metaphosphate as well as molybdate oxide with an 'alveolate-crystallized' structure. The composite Mo/P conversion coating had better corrosion resistance performance than molybdate (Mo) coating, and even had almost comparable corrosion protection for Mg alloy to the traditional chromate-based coating.

  16. Titanium composite conversion coating formation on CRS In the presence of Mo and Ni ions: Electrochemical and microstructure characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Eivaz Mohammadloo, H.; Sarabi, A.A., E-mail: Sarabi@aut.ac.ir

    2016-11-30

    Highlights: • Eco-friendly protective thin films for covering the CRS substrates were presented. • Comprehensive analyses were performed to evaluate the surface characteristics. • Promising approach for the surface modification of CRS substrate by Ti-based conversion coatings. - Abstract: There have been an increasing interest in finding a replacement for the chromating process due to environmental and health concerns. Hence, in this study Chrome-free chemical conversion coatings were deposited on the surface of cold-rolled steel (CRS) on the basis of Titanium (TiCC), Titanium-Nickel (TiNiCC) and titanium-molybdate (TiMoCC) based conversion coating solutions. The surface characterization was performed by field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle measuring device. Also, the corrosion behavior was assessed by the means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. FESEM and AFM study show that the TiNiCC is denser and more uniform than that TiCC and TiMoCC since, TiMoCC conversion coating presents network feature, and there were abundant micro-cracks on the surface of the coating. XPS results confirmed the precipitation of Ti and Ni oxide/hydroxide, Mn dioxide/trioxide on the surface of different Ti-based conversion coatings. Electrochemical results revealed that all Ti-based conversion coatings have better anti-corrosion properties than bare CRS. Moreover, TiNiCC treatment inhibited the corrosion of CRS to a significant degree (polarization resistance (R{sub p}) = 5510 Ω cm{sup 2}) in comparison with TiCC (R{sub p} = 2705 Ω cm{sup 2}) and TiMoCC (R{sub p} = 805 Ω cm{sup 2}).

  17. Corrosion behaviour of chemical conversion treatments on as-cast Mg-Al alloys: Electrochemical and non-electrochemical methods

    International Nuclear Information System (INIS)

    Rocca, E.; Juers, C.; Steinmetz, J.

    2010-01-01

    Magnesium alloys are often used in as-cast conditions. So, the aim of this work is to characterize the corrosion protection of as-cast AZ91D alloys coated with simple chemical conversion (phosphate-permanganate, and cerium-based coatings). With the two coatings, the electrochemical measurements show that the corrosion protection is due to both the inhibition of cathodic and anodic reactions, because of the presence of stable CeO 2 or manganese oxides in basic pH. Nevertheless, the non-electrochemical tests of corrosion are required to bring to light the healing effect of phosphate-permanganate coating compared to Ce-coating and to describe the corrosion behaviour completely. Finally phosphoric and soda pickling associated to phosphate-permanganate conversion treatment or cerium coating are ecologically efficient alternatives to fluoride-based pickling and the chromating treatment.

  18. Corrosion behaviour of chemical conversion treatments on as-cast Mg-Al alloys: Electrochemical and non-electrochemical methods

    Energy Technology Data Exchange (ETDEWEB)

    Rocca, E. [Institut Jean Lamour UMR CNRS 7198, Nancy Universite - Corrosion Group, B.P. 70239, 54506 Vandoeuvre-Les-Nancy (France)], E-mail: emmanuel.rocca@lcsm.uhp-nancy.fr; Juers, C.; Steinmetz, J. [Institut Jean Lamour UMR CNRS 7198, Nancy Universite - Corrosion Group, B.P. 70239, 54506 Vandoeuvre-Les-Nancy (France)

    2010-06-15

    Magnesium alloys are often used in as-cast conditions. So, the aim of this work is to characterize the corrosion protection of as-cast AZ91D alloys coated with simple chemical conversion (phosphate-permanganate, and cerium-based coatings). With the two coatings, the electrochemical measurements show that the corrosion protection is due to both the inhibition of cathodic and anodic reactions, because of the presence of stable CeO{sub 2} or manganese oxides in basic pH. Nevertheless, the non-electrochemical tests of corrosion are required to bring to light the healing effect of phosphate-permanganate coating compared to Ce-coating and to describe the corrosion behaviour completely. Finally phosphoric and soda pickling associated to phosphate-permanganate conversion treatment or cerium coating are ecologically efficient alternatives to fluoride-based pickling and the chromating treatment.

  19. The formation of neodymium conversion coating and the influence of post-treatment

    Energy Technology Data Exchange (ETDEWEB)

    Cui Xiufang [School of Materials Science and Chemical Engineering, Harbin Engineering University, 145 Nantong St., Harbin 150001 (China); Jin Guo, E-mail: jg97721@yahoo.com.cn [Center for Biomedical Materials and Engineering, School of Materials Science and Chemical Engineering, Harbin Engineering University, 145 Nantong St., Harbin 150001 (China); Yang Yuyun; Liu Erbao; Lin Lili; Zhong Jinggao [Center for Biomedical Materials and Engineering, School of Materials Science and Chemical Engineering, Harbin Engineering University, 145 Nantong St., Harbin 150001 (China)

    2012-01-15

    In this paper, neodymium-based conversion coating is used as a substitute for toxic chromate conversion coating on AZ91D magnesium alloys. Its formation and growth were observed via SEM, EDS, XPS, electrochemical tests and weighting experiment. The influence of post-treatment on neodymium conversion coating was measured by FTIR and electrochemical experiments in terms of morphology, component, surface functional group and corrosion resistance. The dissolution of matrix and the deposition of neodymium/magnesium oxides compete with each other in initial time. Then the deposition of neodymium oxides dominates the process. Compact coating is obtained after 20 min immersion and it is mainly made of neodymium oxides and a small amount of magnesium oxides/hydroxides. The coating post-treated is rich in OH{sup -} and PO{sub 4}{sup 3+}. The post-treatment can improve the corrosion resistance of the neodymium conversion coating effectually examined by EIS.

  20. The formation of neodymium conversion coating and the influence of post-treatment

    International Nuclear Information System (INIS)

    Cui Xiufang; Jin Guo; Yang Yuyun; Liu Erbao; Lin Lili; Zhong Jinggao

    2012-01-01

    In this paper, neodymium-based conversion coating is used as a substitute for toxic chromate conversion coating on AZ91D magnesium alloys. Its formation and growth were observed via SEM, EDS, XPS, electrochemical tests and weighting experiment. The influence of post-treatment on neodymium conversion coating was measured by FTIR and electrochemical experiments in terms of morphology, component, surface functional group and corrosion resistance. The dissolution of matrix and the deposition of neodymium/magnesium oxides compete with each other in initial time. Then the deposition of neodymium oxides dominates the process. Compact coating is obtained after 20 min immersion and it is mainly made of neodymium oxides and a small amount of magnesium oxides/hydroxides. The coating post-treated is rich in OH - and PO 4 3+ . The post-treatment can improve the corrosion resistance of the neodymium conversion coating effectually examined by EIS.

  1. Zeolite-catalyzed biomass conversion to fuels and chemicals

    DEFF Research Database (Denmark)

    Taarning, Esben; Osmundsen, Christian Mårup; Yang, Xiaobo

    2011-01-01

    Heterogeneous catalysts have been a central element in the efficient conversion of fossil resources to fuels and chemicals, but their role in biomass utilization is more ambiguous. Zeolites constitute a promising class of heterogeneous catalysts and developments in recent years have demonstrated...... their potential to find broad use in the conversion of biomass. In this perspective we review and discuss the developments that have taken place in the field of biomass conversion using zeolites. Emphasis is put on the conversion of lignocellulosic material to fuels using conventional zeolites as well...

  2. Bioelectrochemical conversion of CO2 to chemicals

    NARCIS (Netherlands)

    Bajracharya, Suman; Vanbroekhoven, Karolien; Buisman, Cees J.N.; Strik, David P.B.T.B.; Pant, Deepak

    2017-01-01

    The recent concept of microbial electrosynthesis (MES) has evolved as an electricity-driven production technology for chemicals from low-value carbon dioxide (CO2) using micro-organisms as biocatalysts. MES from CO2 comprises bioelectrochemical reduction of CO2 to multi-carbon organic compounds

  3. Lignin biomass conversion into chemicals and fuels

    DEFF Research Database (Denmark)

    Melián Rodríguez, Mayra

    Second-generation biomass or lignocellulosic biomass, which is mainly composed of cellulose, hemicellulose and lignin, is a very important and promising feedstock for the renewable production of fuels and chemicals of the future. Lignin is the second most abundant natural polymer, representing 30...... and show similar, although simplified, characteristics to the natural biopolymer. Among them, the most abundant structural unit is the β-O-4, representing approximately 60% of the bonds in hardwood and 45-50% of those in softwood. Oxidative depolymerization is one of the most viable methods for lignin...... valorization. It involves the cleavage of ether bonds, such as β-O-4 and other linkages present in lignin and its model compounds, giving aldehydes or carboxylic acids as products, depending on the reaction conditions used. In Chapter 2 of this thesis, the preparation, characterization and catalytic...

  4. The role of phosphate conversion coatings in make-up of casing connections

    NARCIS (Netherlands)

    Ernens, D; van Riet, E.J.; de Rooij, M.B.; Pasaribu, H.R.; van Haaften, W.M.; Schipper, D.J.

    2017-01-01

    Phosphate conversion coatings are widely used on (premium) casing connections for protection against corrosion. Next to that, in conjunction with the lubricant these coatings provide galling protection. The friction and wear that occurs during make-up and subsequent load cycling determines the

  5. Effect of heat treatment, top coatings and conversion coatings on the corrosion properties of black electroless Ni-P films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y., E-mail: liu_yunli@hotmail.com [R and D Department, MacDermid plc, 198 Golden Hillock Road, Birmingham B11 2PN (United Kingdom); Beckett, D.; Hawthorne, D. [R and D Department, MacDermid plc, 198 Golden Hillock Road, Birmingham B11 2PN (United Kingdom)

    2011-02-15

    Electroless black nickel-phosphorus plating is an advanced electroless nickel plating process formulated to deposit a black finish when processed through an oxidizing acid solution. Heat treatment, five types of top organic coating techniques and one conversion coating technique with three different experimental conditions were investigated to stabilize the black film and increase the hardness and corrosion resistance. Morphology and compositions of electroless nickel-phosphorous films with or without heat treatment, with five types of top organic coatings, and with three conversion coatings were compared to examine nickel, phosphorus, oxygen, carbon, silicon and chrome contents on the corrosion resistance of black surfaces by energy dispersive X-ray microanalysis and scanning electron microscope. Corrosion resistance of black electroless nickel-phosphorus coatings with or without heat treatment, with five types of top organic coatings, and with three conversion coatings was investigated by the polarization measurements and the salt spray test in 5% NaCl solution, respectively. HydroLac as the top organic coating from MacDermid showed the excellent corrosion resistance and the black EN film did not lose the black color after 48 h salt spray test. Electrotarnil B process with 0.5 ASD for 1 min stabilized the black Ni-P film immediately and increased the hardness and corrosion performance of the black Ni-P film. The black Ni-P coating with Electroarnil B process passed the 5% NaCl salt spray test for 3000 h in the black color and had a minimal corrosion current 0.8547 {mu}A/cm{sup 2} by the polarization measurement.

  6. Application of mechano-chemical synthesis for protective coating

    Indian Academy of Sciences (India)

    This can either be prevented by using grinding medium and container of same material of the milled material or by adding a coating of the milled material on them. The paper describes the observations made during a mechano-chemical reaction, being used for coating the balls and vials in a planetary ball mill.

  7. Chemical vapor deposition: A technique for applying protective coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, T.C. Sr.; Bowman, M.G.

    1979-01-01

    Chemical vapor deposition is discussed as a technique for applying coatings for materials protection in energy systems. The fundamentals of the process are emphasized in order to establish a basis for understanding the relative advantages and limitations of the technique. Several examples of the successful application of CVD coating are described. 31 refs., and 18 figs.

  8. Anticorrosive Behavior and Porosity of Tricationic Phosphate and Zirconium Conversion Coating on Galvanized Steel

    Science.gov (United States)

    Velasquez, Camilo S.; Pimenta, Egnalda P. S.; Lins, Vanessa F. C.

    2018-05-01

    This work evaluates the corrosion resistance of galvanized steel treated with tricationic phosphate and zirconium conversion coating after painting, by using electrochemical techniques, accelerated and field corrosion tests. A non-uniform and heterogeneous distribution of zirconium on the steel surface was observed due to preferential nucleation of the zirconium on the aluminum-rich sites on the surface of galvanized steel. The long-term anti-corrosion performance in a saline solution was better for the phosphate coating up to 120 days. The coating capacitance registered a higher increase for the zirconium coatings than the phosphate coatings up to 120 days of immersion. This result agrees with the higher porosity of zirconium coating in relation to the phosphate coating. After 3840 h of accelerated corrosion test, and after 1 year of accelerated field test, zirconium-treated samples showed an average scribe delamination length higher than the phosphate-treated samples.

  9. Corrosion behaviors in physiological solution of cerium conversion coatings on AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Cui Xiufang; Yang Yuyun; Liu Erbao; Jin Guo; Zhong Jinggao; Li Qingfen

    2011-01-01

    In this paper, a non-toxic Ce-based conversion coating was obtained on the surface of bio-medical AZ31 magnesium alloys. The micro-morphology of the coating prepared with optimal technical parameters and immersed in physiological solution (Hank's solution) in different time was observed by scanning electron microscopy (SEM), composition of the cerium conversion coating and corrosion products in Hank's solution were characterized by X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS), respectively. In addition, the corrosion property in Hank's solution was studied by electrochemical experiment and immersion test. The results show that the dense Ce-based conversion coating is obtained on the surface of AZ31 magnesium alloys in optimal technical parameters and the conversion coating consists of a mass of trivalent and tetravalent cerium oxides. The cerium conversion coating can provide obvious protection of magnesium alloys and can effectively reduce the degradation speed in Hank's solution. Also the degradation products have little influence on human body.

  10. Computational approaches to the chemical conversion of carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Daojian; Negreiros, Fabio R.; Apra, Edoardo; Fortunelli, Alessandro

    2013-06-01

    The conversion of CO2 into fuels and chemicals is viewed as an attractive route for controlling the atmospheric concentration of this greenhouse gas and recycling it, but its industrial application is limited by the low selectivity and activity of the current catalysts. Theoretical modeling, in particular density-functional theory (DFT) simulations, provides a powerful and effective tool to discover chemical reaction mechanisms and design new catalysts for the chemical conversion of CO2, overcoming the repetitious and time/labor consuming trial-and-error experimental processes. In this article we give a comprehensive survey of recent advances on mechanism determination by DFT calculations for the catalytic hydrogenation of CO2 into CO, CH4, CH3OH, and HCOOH, and CO2 methanation, as well as the photo- and electrochemical reduction of CO2. DFT-guided design procedures of new catalytic systems are also reviewed, and challenges and perspectives in this field are outlined.

  11. Investigation of the chromate conversion coating on Alclad 2024 aluminium alloy: effect of the pH of the chromate bath

    NARCIS (Netherlands)

    Campestrini, P.; Westing, E.P.M. van; Hovestad, A.; Wit, J.H.W. de

    2002-01-01

    The parameters of the chromate bath, like temperature, pH, and fluoride content, strongly affect the morphology and chemical composition of the chromate conversion coating and as a consequence have a large influence on its corrosion performance. In this paper, electrochemical impedance spectroscopy

  12. Evaluation of self-healing ability of Ce–V conversion coating on AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Xiao Jiang

    2016-09-01

    Full Text Available This study investigated the influence of cerium nitrate in vanadate solutions on the properties of Ce–V conversion coatings on AZ31 magnesium alloys, and evaluated the self-healing behavior of the Ce–V conversion coating for AZ31 magnesium alloy. The results showed that the additions of cerium nitrate prevented pentavalent vanadium from reducing to tetravalent vanadium in the coatings during conversion reaction process. Adding appropriate cerium nitrate to vanadate solution led to a thicker coating with a more compact CeVO4 layer. The corrosion behavior of the Ce–V conversion coating was investigated by the electrochemical tests and the scratch immersion test in 3.5 wt.% NaCl solution. The self-healing ability of the coating was confirmed from all tests. The surface analysis revealed that the self-healing effect of the Ce–V conversion coating was only provided by the release and migration of vanadium compounds.

  13. A new type of Ce-Mo based conversion coatings for aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Li Di; Li Guoqiang; Guo Baolan; Peng Mingxia [Coll. of Materials Science and Engineering, Beijing Univ. of Aeronautics and Astronautics, Beijing, BJ (China)

    2002-07-01

    A new type of process for forming Ce-Mo conversion coatings on Al-alloys has been developed. Conversion coatings about 3.6 {mu}m thickness were obtained by immersing Al-alloys for 20 minutes in boiling film forming solutions containing (NH{sub 4}){sub 2}Ce(NO{sub 3}){sub 6} 2.5 g/l, NaKC{sub 4}H{sub 4}O{sub 6}.4H{sub 2}O 2.5 g/l, Na{sub 2}CO{sub 3} 7.5 g/l and Na{sub 2}MoO{sub 4} 5.0 g/l. In the case of LF4 Al-alloy, polarization curves and immersion tests in 5% NaCl indicated that the conversion coatings exhibited more excellent resistance to localized corrosion than the conventional chromate conversion coatings. However, its resistance to localized corrosion was not satisfactory on LC4 Al alloy. Scanning electron microscopy (SEM) and energy dispersion analyzer of X-ray (EDAX) analysis revealed that the conversion coatings having complex surface microstructure on both LC4 and LF6 Al alloys consist mainly of O, Al and other alloying elements in addition to significant Ce and Mo. A mechanism of film formation was proposed to explain the experimental results. (orig.)

  14. ASTM B 117 Screening of Nonchromate Conversion Coatings on Aluminum Alloys 2024, 2219, 5083, and 7075 Using DOD Paint Systems

    National Research Council Canada - National Science Library

    Placzankis, Brian

    2003-01-01

    This study examines the corrosion resistance of eight nonchromate conversion coatings versus hexavalent chromium-based Alodine 1200S controls on scribed coated test panels of aluminum alloys 2024, 2219, 5083, and 7075...

  15. Superhydrophobic coatings for aluminium surfaces synthesized by chemical etching process

    Directory of Open Access Journals (Sweden)

    Priya Varshney

    2016-10-01

    Full Text Available In this paper, the superhydrophobic coatings on aluminium surfaces were prepared by two-step (chemical etching followed by coating and one-step (chemical etching and coating in a single step processes using potassium hydroxide and lauric acid. Besides, surface immersion time in solutions was varied in both processes. Wettability and surface morphologies of treated aluminium surfaces were characterized using contact angle measurement technique and scanning electron microscopy, respectively. Microstructures are formed on the treated aluminium surfaces which lead to increase in contact angle of the surface (>150°. Also on increasing immersion time, contact angle further increases due to increase in size and depth of microstructures. Additionally, these superhydrophobic coatings show excellent self-cleaning and corrosion-resistant behavior. Water jet impact, floatation on water surface, and low temperature condensation tests assert the excellent water-repellent nature of coatings. Further, coatings are to be found mechanically, thermally, and ultraviolet stable. Along with, these coatings are found to be excellent regeneration ability as verified experimentally. Although aforesaid both processes generate durable and regenerable superhydrophobic aluminium surfaces with excellent self-cleaning, corrosion-resistant, and water-repellent characteristics, but one-step process is proved more efficient and less time consuming than two-step process and promises to produce superhydrophobic coatings for industrial applications.

  16. Friction Modifier Using Adherent Metallic Multilayered or Mixed Element Layer Conversion Coatings

    Science.gov (United States)

    Schramm, Harry F. (Inventor); Defalco, Francis G. (Inventor); Starks, Lloyd L., Sr. (Inventor)

    2013-01-01

    A process for creating conversion coatings and spin, drawing, and extrusion finishes for surfaces, wherein the conversion coatings and spin, drawing, and extrusion finishes contain potassium, phosphorus, nitrogen, and one or more non-alkaline metals and/or one or more metalloids. The process comprises forming an aqueous solution of water, phosphoric acid or sulfuric acid, ammonium hydroxide, an alkali metal hydroxide, and one or more non-alkaline metals and/or one or more metalloids. The aqueous solution forms an anti-friction multilayer conversion and/or mixed element coating or a spin, drawing, and extrusion finish on a surface when applied to the surface, either directly without the use of applied external electromotive force, or as an additive in lubricating fluids.

  17. Lanthanide based conversion coatings for long term wet storage of aluminium-clad spent fuel

    International Nuclear Information System (INIS)

    Fernandes, S.M.C.; Correa, O.V.; De Souza, J.A.; Ramanathan, L.V.

    2010-01-01

    Spent fuels from research reactors are stored in basins with water of less than desirable quality at many facilities around the world and instances of cladding failure caused by pitting corrosion have been reported. Conversion coatings have been used in many industries to protect different metals, including aluminium alloys. This paper presents the results of an ongoing investigation in which the corrosion resistance of lanthanide (cerium, lanthanum and praseodymium) based conversion coated RR fuel cladding alloys has been studied. Electrochemical tests in the laboratory revealed higher corrosion resistance of CeO 2 , La 2 O 3 and Pr 2 O 3 coated AA 1100 and AA 6061 alloys in NaCl solutions. Uncoated and CeO 2 coated coupons of these alloys exposed for 50 days to the spent fuel basin of the IEA-R1 research reactor in IPEN, Brazil, revealed marked reductions in the extent of pitting corrosion. (author)

  18. New Polymer Coatings for Chemically Selective Mass Sensors

    Science.gov (United States)

    Sims, S. C.; Wright, Cassandra; Cobb, J.; McCalla, T.; Revelle, R.; Morris, V. R.; Pollack, S. K.

    1997-01-01

    There is a current need to develop sensitive and chemically specific sensors for the detection of nitric acid for in-situ measurements in the atmosphere. Polymer coatings have been synthesized and tested for their sensitivity and selectivity to nitric acid. A primary requirement for these polymers is detectability down to the parts per trillion range. The results of studies using these polymers as coatings for quartz crystal microbalances (QCM) and surface acoustic wave (SAW) devices will be presented.

  19. Physico-chemical and thermochemical studies of the hydrolytic conversion of amorphous tricalcium phosphate into apatite

    International Nuclear Information System (INIS)

    Somrani, Saida; Banu, Mihai; Jemal, Mohamed; Rey, Christian

    2005-01-01

    The conversion of amorphous tricalcium phosphate with different hydration ratio into apatite in water at 25 deg. C has been studied by microcalorimetry and several physical-chemical methods. The hydrolytic transformation was dominated by two strong exothermic events. A fast, relatively weak, wetting process and a very slow but strong heat release assigned to a slow internal rehydration and the crystallization of the amorphous phase into an apatite. The exothermic phenomenon related to the rehydration exceeded the crystalline transformation enthalpy. Rehydration occurred before the conversion of the amorphous phase into apatite and determined the advancement of the hydrolytic reaction. The apatitic phases formed evolved slightly with time after their formation. The crystallinity increased whereas the amount of HPO 4 2- ion decreased. These data allow a better understanding of the behavior of biomaterials involving amorphous phases such as hydroxyapatite plasma-sprayed coatings

  20. Conversion Coatings Produced on AZ61 Magnesium Alloy by Low-Voltage Process

    Directory of Open Access Journals (Sweden)

    Nowak M.

    2016-03-01

    Full Text Available The resultes of anodic oxide conversion coatings on wrought AZ61 magnesium alloy production are describe. The studies were conducted in a solution containing: KOH (80 g/l and KF (300 g/l using anodic current densities of 3, 5 and 10 A/dm2 and different process durations. The obtained coatings were examined under a microscope and corrosion tests were performed by electrochemical method. Based on these results, it was found that the low-voltage process produces coatings conferring improved corrosion resistance to the tested magnesium alloy.

  1. Corrosion of chromatic conversion coatings on Aluminium Alloys in electrical and electronic equipment

    International Nuclear Information System (INIS)

    Razavi, R.Sh.; Shahrabi, T.; Mozafarnia, R.

    2002-01-01

    Chromate conversion coating is applied on aluminum 6061. The optimum conditions for chromate bath composition and immersion time are also obtained for standard requirements provision such as corrosion resistance in salt spray test, electrical resistance and coating quality. The applied coatings are electrochemically tested in sea and distilled water. According to Tafel and cyclic polarization curves, the protection mechanism are evaluated in said environments. This evaluation has shown the formation of passive film layer, contains chromate and alumina on the base. The proper behavior of corrosion and electrical conductivity is probably due to this mechanism

  2. Chemically vapor deposited coatings for multibarrier containment of nuclear wastes

    International Nuclear Information System (INIS)

    Rusin, J.M.; Shade, J.W.; Kidd, R.W.; Browning, M.F.

    1981-01-01

    Chemical vapor deposition (CVD) was selected as a feasible method to coat ceramic cores, since the technology has previously been demonstrated for high-temperature gas-cooled reactor (HTGR) fuel particles. CVD coatings, including SiC, PyC (pyrolytic carbon), SiO 2 , and Al 2 O 3 were studied. This paper will discuss the development and characterization of PyC and Al 2 O 3 CVD coatings on supercalcine cores. Coatings were applied to 2 mm particles in either fluidized or vibrating beds. The PyC coating was deposited in a fluidized bed with ZrO 2 diluent from C 2 H 2 at temperatures between 1100 and 1200 0 C. The Al 2 O 3 coatings were deposited in a vibrated bed by a two-stage process to minimize loss of PyC during the overcoating operation. This process involved applying 10 μm of Al 2 O 3 using water vapor hydrolysis of AlCl 3 and then switching to the more surface-controlled hydrolysis via the H 2 + CO 2 reaction (3CO 2 + 3H 2 + 2AlCl 3 = Al 2 O 3 + 6HCl + 3CO). Typically, 50 to 80 μm Al 2 O 3 coatings were applied over 30 to 40 μm PyC coatings. The coatings were evaluated by metallographic examination, PyC oxidation tests, and leach resistance. After air oxidation for 100 hours at 750 0 C, the duplex PyC/Al 2 O 3 coated particles exhibited a weight loss of 0.01 percent. Leach resistance is being determined for temperatures from 50 to 150 0 C in various solutions. Typical results are given for selected ions. The leach resistance of supercalcine cores is significantly improved by the application of PyC and/or Al 2 O 3 coatings

  3. A Black Phosphate Conversion Coating on Steel Surface Using Antimony(III)-Tartrate as an Additive

    Science.gov (United States)

    Li, Feng; Wang, Guiping

    2016-05-01

    A novel black phosphate conversion coating was formed on steel surface through a Zn-Mn phosphating bath containing mainly ZnO, H3PO4, Mn(H2PO4)2, and Ca(NO3)2, where antimony(III)-tartrate was used as the blackening agent of phosphatization. The surface morphology and composition of the coating were characterized by scanning electron microscopy, energy dispersion spectroscopy, and x-ray photoelectron spectroscopy. Corrosion resistance of the coating was studied by potentiodynamic polarization curves and electrochemical impedance spectroscopy. The pH value of the solution had significant influence on the formation and corrosion resistance of the coating. The experimental results indicated that the Sb plays a vital role in the blackening of phosphate conversion coating. The optimal concentration of antimony(III)-tartrate in the phosphating bath used in this experiment was 1.0 g L-1, as higher values reduced the corrosion resistance of the coating. In addition, by saponification and oil seals, the corrosion duration of the black phosphate coating in a copper sulfate spot test can be as long as 20 min.

  4. Catalytic Conversion of Renewable Resources into Bulk and Fine Chemicals.

    Science.gov (United States)

    de Vries, Johannes G

    2016-12-01

    Several strategies can be chosen to convert renewable resources into chemicals. In this account, I exemplify the route that starts with so-called platform chemicals; these are relatively simple chemicals that can be produced in high yield, directly from renewable resources, either via fermentation or via chemical routes. They can be converted into the existing bulk chemicals in a very efficient manner using multistep catalytic conversions. Two examples are given of the conversion of sugars into nylon intermediates. 5-Hydroxymethylfurfural (HMF) can be prepared in good yield from fructose. Two hydrogenation steps convert HMF into 1,6-hexanediol. Oppenauer oxidation converts this product into caprolactone, which in the past, has been converted into caprolactam in a large-scale industrial process by reaction with ammonia. An even more interesting platform chemical is levulinic acid (LA), which can be obtained directly from lignocellulose in good yield by treatment with dilute sulfuric acid at 200°C. Hydrogenation converts LA into gamma-valerolactone, which is ring-opened and esterified in a gas-phase process to a mixture of isomeric methyl pentenoates in excellent selectivity. In a remarkable selective palladium-catalysed isomerising methoxycarbonylation, this mixture is converted in to dimethyl adipate, which is finally hydrolysed to adipic acid. Overall selectivities of both processes are extremely high. The conversion of lignin into chemicals is a much more complicated task in view of the complex nature of lignin. It was discovered that breakage of the most prevalent β-O-4 bond in lignin occurs not only via the well-documented C3 pathway, but also via a C2 pathway, leading to the formation of highly reactive phenylacetaldehydes. These compounds went largely unnoticed as they immediately recondense on lignin. We have now found that it is possible to prevent this by converting these aldehydes in a tandem reaction, as they are formed. For this purpose, we have used

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

    Energy Technology Data Exchange (ETDEWEB)

    Kmetz, M.A.

    1992-01-01

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

  6. The effects of addition of poly(vinyl) alcohol (PVA) as a green corrosion inhibitor to the phosphate conversion coating on the anticorrosion and adhesion properties of the epoxy coating on the steel substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ramezanzadeh, B., E-mail: ramezanzadeh-bh@icrc.ac.ir; Vakili, H.; Amini, R.

    2015-02-01

    Highlights: • Room temperature zinc phosphate coating was applied on the surface of steel sample. • Poly(vinyl) alcohol was added to the phosphating bath as a green corrosion inhibitor. • The adhesion and anticorrosion properties of the epoxy coating were investigated. • PVA decreased the phosphate crystal size and porosity. • PVA enhanced the corrosion protection and adhesion properties of the epoxy coating. - Abstract: Steel substrates were chemically treated by room temperature zinc phosphate conversion coating. Poly(vinyl) alcohol (PVA) was added to the phosphate solution as a green corrosion inhibitor. Finally, the epoxy/polyamide coating was applied on the untreated and surface treated steel samples. The effects of PVA on the morphological properties of the phosphate coating were studied by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and contact angle measuring device. The adhesion properties of the epoxy coatings applied on the surface treated samples were investigated by pull-off and cathodic delamination tests. Also, the anticorrosion properties of the epoxy coatings were studied by electrochemical impedance spectroscopy (EIS). Results showed that addition of PVA to the phosphate coating increased the population density of the phosphate crystals and decreased the phosphate grain size. The contact angle of the steel surface treated by Zn-PVA was lower than Zn treated one. The corrosion resistance of the epoxy coating was considerably increased on the steel substrate treated by zinc phosphate conversion coating containing PVA. PVA also enhanced the adhesion properties of the epoxy coating to the steel surface and decreased the cathodic delamination significantly.

  7. Chemical Conversion of Human Fibroblasts into Functional Schwann Cells

    Directory of Open Access Journals (Sweden)

    Eva C. Thoma

    2014-10-01

    Full Text Available Direct transdifferentiation of somatic cells is a promising approach to obtain patient-specific cells for numerous applications. However, conversion across germ-layer borders often requires ectopic gene expression with unpredictable side effects. Here, we present a gene-free approach that allows efficient conversion of human fibroblasts via a transient progenitor stage into Schwann cells, the major glial cell type of peripheral nerves. Using a multikinase inhibitor, we transdifferentiated fibroblasts into transient neural precursors that were subsequently further differentiated into Schwann cells. The resulting induced Schwann cells (iSCs expressed numerous Schwann cell-specific proteins and displayed neurosupportive and myelination capacity in vitro. Thus, we established a strategy to obtain mature Schwann cells from human postnatal fibroblasts under chemically defined conditions without the introduction of ectopic genes.

  8. Mono-carboxylate conversion coatings for AZ31 Mg alloy protection

    Energy Technology Data Exchange (ETDEWEB)

    Frignani, A.; Grassi, V.; Zucchi, F.; Zanotto, F. [Corrosion Study Centre A. Dacco, University of Ferrara (Italy)

    2011-11-15

    Conversion coatings on a magnesium alloy were obtained by dipping AZ31 specimens in aqueous solutions of sodium salts of mono-carboxylic acids (stearic, palmitic, myristic, lauric, mono-carboxylate ion concentration from 1 to 5 mM, depending on the salt solubility) for 24 and 72 h at room temperature, or 24 h at 50 C. The influence exerted by the treatment time, bath temperature and alkyl chain length on the efficiency of these coatings was studied. The performances of the coatings were evaluated by potentiodynamic polarization curve recording after 1 h immersion in 0.05 M Na{sub 2}SO{sub 4} solution, while their temporal evolution was monitored by electrochemical impedance spectroscopy (EIS) spectra during 24 h. Further and long lasting tests were carried out also in 0.1 M NaCl solution. The efficiency of the coatings depended on the aliphatic chain length, and increased as the treatment time and the bath temperature were increased. The coating of lower homologue only hindered the cathodic process, while those of the higher homologues markedly inhibited the anodic process too. The best performances were displayed by 24 h-50 C stearic conversion coating, which maintained a very high efficiency for over 800 h immersion in 0.05 M sulphate solution. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Effects of vacuum and ageing on Zr4/Cr3 based conversion coatings on aluminium alloys

    Science.gov (United States)

    Thirupathi, Kalaivanan; Bárczy, Pál; Vad, Kálmán; Csik, Attila; Somosvári, Béla Márton

    2018-05-01

    In this study, we investigate the impact of ageing and high vacuum on existing environmentally friendly Zr4/Cr3-based conversion coatings. The freshly formed coating undergoes several changes during ageing and exposure to high vacuum. Based on the present data, we propose that the coating formed over AA6082 and AA7075 alloys is sol-gel in nature, confirmed by secondary neutral mass spectroscopy (SNMS) using the depth profiling technique. Our findings reveal that there are elemental level changes that result in shrinkage of the coating. Most Zr ions in the coating are in the solute form, with lesser number of Cr and Al ions that disappear under high vacuum over a certain period of time. The remaining Cr, Zr and O atoms exist in a gelatinous state. During ageing, there is a continuous transition of ions from solute to gelatinous state. In addition, the deposition of coating ions is directly influenced by the substrates and their constituents. The extent of dissolution of aluminium in the conversion bath determines both Zr and Cr ion deposition. For a highly alloyed metal like AA7075, the dissolution rate is disturbed by copper and zinc.

  10. SiC Conversion Coating Prepared from Silica-Graphite Reaction

    Directory of Open Access Journals (Sweden)

    Back-Sub Sung

    2017-01-01

    Full Text Available The β-SiC conversion coatings were successfully synthesized by the SiO(v-graphite(s reaction between silica powder and graphite specimen. This paper is to describe the effects on the characteristics of the SiC conversion coatings, fabricated according to two different reaction conditions. FE-SEM, FE-TEM microstructural morphologies, XRD patterns, pore size distribution, and oxidation behavior of the SiC-coated graphite were investigated. In the XRD pattern and SAD pattern, the coating layers showed cubic SiC peak as well as hexagonal SiC peak. The SiC coatings showed somewhat different characteristics with the reaction conditions according to the position arrangement of the graphite samples. The SiC coating on graphite, prepared in reaction zone (2, shows higher intensity of beta-SiC main peak (111 in XRD pattern as well as rather lower porosity and smaller main pore size peak under 1 μm.

  11. Thick sputtered tantalum coatings for high-temperature energy conversion applications

    Energy Technology Data Exchange (ETDEWEB)

    Stelmakh, Veronika, E-mail: stelmakh@mit.edu; Peykov, Daniel; Chan, Walker R.; Senkevich, Jay J.; Joannopoulos, John D.; Soljačić, Marin; Celanovic, Ivan [Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Castillo, Robert; Coulter, Kent; Wei, Ronghua [Materials Engineering Department, Southwest Research Institute, San Antonio, Texas 78238 (United States)

    2015-11-15

    Thick sputtered tantalum (Ta) coatings on polished Inconel were investigated as a potential replacement for bulk refractory metal substrates used for high-temperature emitters and absorbers in thermophotovoltaic energy conversion applications. In these applications, high-temperature stability and high reflectance of the surface in the infrared wavelength range are critical in order to sustain operational temperatures and reduce losses due to waste heat. The reflectance of the coatings (8 and 30 μm) was characterized with a conformal protective hafnia layer as-deposited and after one hour anneals at 700, 900, and 1100 °C. To further understand the high-temperature performance of the coatings, the microstructural evolution was investigated as a function of annealing temperature. X-ray diffraction was used to analyze the texture and residual stress in the coatings at four reflections (220, 310, 222, and 321), as-deposited and after anneal. No significant changes in roughness, reflectance, or stress were observed. No delamination or cracking occurred, even after annealing the coatings at 1100 °C. Overall, the results of this study suggest that the thick Ta coatings are a promising alternative to bulk substrates and pave the way for a relatively low-cost and easily integrated platform for nanostructured devices in high-temperature energy conversion applications.

  12. Corrosion mitigation of rare-earth metals containing magnesium EV31A-T6 alloy via chrome-free conversion coating treatment

    International Nuclear Information System (INIS)

    Hamdy, Abdel Salam; Butt, Darryl P.

    2013-01-01

    Highlights: • Protective stannate coatings have been proposed for rare-earth-EV31A-T6 magnesium alloy. • A simple coating method based on direct treatment of EV31A-T6 in a diluted stannate was found promising. • Surface modification prior to stannate coating offer no substantial advantage over directly coating. • Stannate conversion coatings decrease corrosion rates by a factor of 1/7. • The coating does not display any self-healing characteristics as shown in AZ91D. -- Abstract: Magnesium alloys posses unique mechanical and physical characteristics making them attractive light-weight materials for several strategic industries such as electronics, computer, automotive and aerospace. Due to their high chemical reactivity and poor corrosion resistance, the protection of magnesium alloys from corrosion is one of the hottest topics in materials science and engineering. Addition of rare-earth metals (RE) as alloying elements to magnesium alloys is one of the common approaches to improve their mechanical properties and, sometimes, the corrosion resistance. However, the potential difference between the RE metals phase formed in the Mg matrix enhances the galvanic corrosion at the interfaces where RE metals inert phase acts as cathode and the active Mg matrix acts as anode. This paper introduces a simple one-step clean conversion coating treatment for improving the protection of RE containing magnesium EV31A-T6 alloy in Cl − media

  13. Lignite chemical conversion in an indirect heat rotary kiln gasifier

    Directory of Open Access Journals (Sweden)

    Hatzilyberis Kostas S.

    2006-01-01

    Full Text Available The results on the gasification of Greek lignite using two indirect heat (allothermal pilot rotary kiln gasifiers are reported in the present work. The development of this new reactor-gasifier concept intended for solid fuels chemical conversion exploits data and experience gained from the following two pilot plants. The first unit A (about 100 kg/h raw lignite demonstrated the production of a medium heating value gas (12-13 MJ/Nm3 with quite high DAF (dry ash free coal conversions, in an indirect heat rotary gasifier under mild temperature and pressure conditions. The second unit B is a small pilot size unit (about 10 kg/h raw lignite comprises an electrically heated rotary kiln, is an operation flexible and exhibits effective phase mixing and enhanced heat transfer characteristics. Greek lignite pyrolysis and gasification data were produced from experiments performed with pilot plant B and the results are compared with those of a theoretical model. The model assumes a scheme of three consecutive-partly parallel processes (i. e. drying, pyrolysis, and gasification and predicts DAF lignite conversion and gas composition in relatively good agreement with the pertinent experimental data typical of the rotary kiln gasifier performance. Pilot plant B is currently being employed in lime-enhanced gasification studies aiming at the production of hydrogen enriched synthesis gas. Presented herein are two typical gas compositions obtain from lignite gasification runs in the presence or not of lime. .

  14. The role of hexafluorozirconate in the formation of chromate conversion coatings on aluminum alloys

    International Nuclear Information System (INIS)

    Chidambaram, Devicharan; Clayton, Clive R.; Halada, Gary P.

    2006-01-01

    Aluminum based surfaces are routinely coated with a chromate based layer that provides unparalleled corrosion protection. Widely used conversion coating treatment formulations contain hexafluorozirconate as a major constituent besides chromate, ferricyanide, fluoride, and fluoborate. The function of hexafluorozirconate is the subject of this study as its function is still largely unknown. Hydrophobicity, surface morphology, and the chemistry of the surface, resulting from treatment with hexafluorozirconate, were studied using contact angle measurements, scanning electron microscopy, and energy dispersive spectroscopy, respectively. X-ray photoelectron spectroscopy was extensively utilized to determine the chemistry of the surface resulting from the hexafluorozirconate pretreatment. Our results indicate that fluoride ion containing hexafluorozirconate complex does not attack the oxide film in a manner that uncomplexed simple fluoride ion does. Hexafluorozirconate is involved in the formation of an Al-Zr-O-F based hydrated layer that increases the hydrophilicity of the surface, activates the surface, and lowers the corrosion resistance. These factors enhance the interaction of chromate with the alloy surface to result in the formation of a uniform conversion coating. Based on these results, a new model has been proposed for the formation of chromate conversion coatings

  15. Thermo-Chemical Conversion of Microwave Activated Biomass Mixtures

    Science.gov (United States)

    Barmina, I.; Kolmickovs, A.; Valdmanis, R.; Vostrikovs, S.; Zake, M.

    2018-05-01

    Thermo-chemical conversion of microwave activated wheat straw mixtures with wood or peat pellets is studied experimentally with the aim to provide more effective application of wheat straw for heat energy production. Microwave pre-processing of straw pellets is used to provide a partial decomposition of the main constituents of straw and to activate the thermo-chemical conversion of wheat straw mixtures with wood or peat pellets. The experimental study includes complex measurements of the elemental composition of biomass pellets (wheat straw, wood, peat), DTG analysis of their thermal degradation, FTIR analysis of the composition of combustible volatiles entering the combustor, the flame temperature, the heat output of the device and composition of the products by comparing these characteristics for mixtures with unprocessed and mw pre-treated straw pellets. The results of experimental study confirm that mw pre-processing of straw activates the thermal decomposition of mixtures providing enhanced formation of combustible volatiles. This leads to improvement of the combustion conditions in the flame reaction zone, completing thus the combustion of volatiles, increasing the flame temperature, the heat output from the device, the produced heat energy per mass of burned mixture and decreasing at the same time the mass fraction of unburned volatiles in the products.

  16. Chemical solution deposition: a path towards low cost coated conductors

    International Nuclear Information System (INIS)

    Obradors, X; Puig, T; Pomar, A; Sandiumenge, F; Pinol, S; Mestres, N; Castano, O; Coll, M; Cavallaro, A; Palau, A; Gazquez, J; Gonzalez, J C; Gutierrez, J; Roma, N; Ricart, S; Moreto, J M; Rossell, M D; Tendeloo, G van

    2004-01-01

    The achievement of low cost deposition techniques for high critical current YBa 2 Cu 3 O 7 coated conductors is one of the major objectives to achieve a widespread use of superconductivity in power applications. Chemical solution deposition techniques are appearing as a very promising methodology to achieve epitaxial oxide thin films at a low cost, so an intense effort is being carried out to develop routes for all chemical coated conductor tapes. In this work recent achievements will be presented towards the goal of combining the deposition of different type of buffer layers on metallic substrates based on metal-organic decomposition with the growth of YBa 2 Cu 3 O 7 layers using the trifluoroacetate route. The influence of processing parameters on the microstructure and superconducting properties will be stressed. High critical currents are demonstrated in 'all chemical' multilayers

  17. Microwave-assisted synthesis of lanthanum conversion coating on Mg-Li alloy and its corrosion resistance

    International Nuclear Information System (INIS)

    Song Dalei; Jing Xiaoyan; Wang Jun; Lu Shanshan; Yang Piaoping; Wang Yanli; Zhang Milin

    2011-01-01

    Graphical abstract: Highlights: → The method of microwave is used to synthesize lanthanum conversion coating. → Lanthanum conversion coating on Mg-Li alloy was studied. → Different conditions between room temperature and microwave were compared. → The corrosion behavior of lanthanum conversion coatings was studied. → The corrosion mechanism of lanthanum conversion coatings was studied. - Abstract: Lanthanum-based conversion coating on Mg-Li alloy has been prepared by a microwave-assisted method. X-ray diffractions (XRD) indicate that the intermetallic compounds of lanthanum are formed on Mg-Li alloy surface. Scanning electron microscopy (SEM) images show that the coating has different morphologies and special structures. The corrosion resistance was assessed by means of potentiodynamic polarization curves and electrochemical impedance spectra (EIS). The results indicate that this coating significantly reduces the corrosion rate of Mg-Li alloy in NaCl solution. A comparing experiment indicates that the coating prepared by microwave-assisted process has superior corrosion resistance to the coating obtained at room temperature.

  18. Fabrication of silica-coated gold nanorods and investigation of their property of photothermal conversion

    International Nuclear Information System (INIS)

    Inose, Tomoya; Oikawa, Takahiro; Shibuya, Kyosuke; Tokunaga, Masayuki; Hatoyama, Keiichiro; Nakashima, Kouichi; Kamei, Takashi; Gonda, Kohsuke; Kobayashi, Yoshio

    2017-01-01

    This study described the preparation of silica-coated Au nanorods (AuNR/SiO 2 ) in a colloidal solution, assessed their property of photothermal conversion, and investigated their ability to kill cancer cells using photothermal conversion. Au-seed nanoparticles were produced by reducing hydrogen tetrachloroaurate (HAuCl 4 ) with sodium borohydride (NaBH 4 ) in aqueous n-hexadecyltrimethylammonium bromide (CTAB) solution. AuNRs were then fabricated by reducing HAuCl 4 and silver nitrate (AgNO 3 ) with L-ascorbic acid in the aqueous CTAB solution in the presence of Au-seed nanoparticles. The as-prepared AuNRs were washed by a process composed mainly of centrifugation to remove the CTAB. The washed AuNRs were coated with silica by mixing the AuNR colloidal solution, an aqueous solution of (3-aminopropyl)trimethoxysilane, and tetraethylorthosilicate/ethanol solution with a water/ethanol solution. We found that the addition of AuNR/SiO 2 in water, in mice, and in a culture medium with cancer cells, followed by irradiation with a laser, cause an increase in temperature, demonstrating that AuNR/SiO 2 have the ability of photothermal conversion. In addition, the cancer cells in the culture medium were found to be killed due to the increase in temperature caused by the photothermal conversion. - Highlights: • This study described the preparation of silica-coated Au nanorods (AuNR/SiO 2 ) colloidal solution. • The AuNR/SiO 2 had the ability of photothermal conversion. • The AuNR/SiO 2 also had the ability to kill cancer cells using the photothermal conversion.

  19. 75 FR 4402 - Notice of National Conversation on Public Health and Chemical Exposures Leadership Council...

    Science.gov (United States)

    2010-01-27

    ... National Conversation on Public Health and Chemical Exposures Leadership Council Conference Call Time and... the second meeting of the National Conversation on Public Health and Chemical Exposures Leadership... Leadership Council provides overall guidance to the National Conversation project and will be responsible for...

  20. Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

    Science.gov (United States)

    Li, Kun; Liu, Junyao; Lei, Ting; Xiao, Tao

    2015-10-01

    A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

  1. An electrothermal chemical technology for thermal spray coatings

    International Nuclear Information System (INIS)

    Wald, S.; Appelbaum, G.; Alimi, R.; Rabani, L.; Zoler, D.; Zhitomirsky, V.; Factor, M.; Roman, I.

    1998-01-01

    A new spray technology for producing hard-coatings, has been developed at the SOREQ Nuclear Research Center. The concept is based on the extensive experience accumulated at SOREQ in the course of the development of Electrothermal (ET), Electrothermal-Chemical (ETC) and Solid-Propellant Electrothermal-Chemical (SPETC) guns(r). High quality coatings may be obtained by thermal spraying powder particles onto a variety of substrates. Mature state-of-the-art technologies such as plasma spray, high velocity oxy fuel (HVOF) and detonation gun (D-Gun) are widely used for many applications. As each method has its own drawbacks there is a need for a combination of several parameters which cannot be achieved by any existing individual commercial technology. The method presented is oriented toward a high-quality, multi-step, high-throughput, easily programmable continuous coating process and relatively inexpensive technology. The combustion products of a solid or liquid propellant accelerate the powder particles of the coating material. A pulsed-plasma jet, provided by a confined capillary discharge, ignites the propellant and controls the combustion process. The powder particles are accelerated to velocities over 1000 m/s. Due to the very high carrier gas density, high velocity, high throughput and high powder consumption efficiency are obtained. The plasma jet enables control of the gas temperature and consequently influences the powder temperature

  2. Inhibition of the corrosion of mild steel by phosphate conversion coatings

    International Nuclear Information System (INIS)

    Ashraf, W.; Khalid, S.; Rashid, A.; Arshad, M.

    1993-01-01

    Phosphating is the treatment of a metal surface to provide a coating of insoluble metal phosphate crystals which strongly adhere to the base material. Such coatings affect the appearance, surface hardness, and electrical conductivity of the metal. Phosphating is major industrial importance in the production of iron and steel surfaces, e.g., in automotive and appliance industries. The present article discusses a novel description of process controlling parameters. The process may be termed as hot phosphate (95-100 deg. C) and it employs the use of low cost chemicals and entirely new accelerator. Effective layer thickness is found to be 0.72 mg/cm /sup 2/ and can withstand moist and mild chemical conditions. The thickness of coating depends upon dipping time and temperature of the working bath. It seems to increase with increasing dipping time but then reaches a maxima. Any more dipping causes stripping and uneven coating layers. In our system most appropriate dipping time was found to be 45 minutes. The stability and completeness of coating was tested by Ferro Test and Tape Pull Test and was found to be satisfactory. The quality control parameters, such as free and total acidity have been controlled for optimum coating thickness and stability. (author)

  3. Chemical looping combustion. Fuel conversion with inherent CO2 capture

    Energy Technology Data Exchange (ETDEWEB)

    Brandvoll, Oeyvind

    2005-07-01

    Chemical looping combustion (CLC) is a new concept for fuel energy conversion with CO2 capture. In CLC, fuel combustion is split into separate reduction and oxidation processes, in which a solid carrier is reduced and oxidized, respectively. The carrier is continuously recirculated between the two vessels, and hence direct contact between air and fuel is avoided. As a result, a stoichiometric amount of oxygen is transferred to the fuel by a regenerable solid intermediate, and CLC is thus a variant of oxy-fuel combustion. In principle, pure CO2 can be obtained from the reduction exhaust by condensation of the produced water vapour. The thermodynamic potential and feasibility of CLC has been studied by means of process simulations and experimental studies of oxygen carriers. Process simulations have focused on parameter sensitivity studies of CLC implemented in 3 power cycles; CLC-Combined Cycle, CLC-Humid Air Turbine and CLC-Integrated Steam Generation. Simulations indicate that overall fuel conversion ratio, oxidation temperature and operating pressure are among the most important process parameters in CLC. A promising thermodynamic potential of CLC has been found, with efficiencies comparable to, - or better than existing technologies for CO2 capture. The proposed oxygen carrier nickel oxide on nickel spinel (NiONiAl) has been studied in reduction with hydrogen, methane and methane/steam as well as oxidation with dry air. It has been found that at atmospheric pressure and temperatures above 600 deg C, solid reduction with dry methane occurs with overall fuel conversion of 92%. Steam methane reforming is observed along with methane cracking as side reactions, yielding an overall selectivity of 90% with regard to solid reduction. If steam is added to the reactant fuel, coking can be avoided. A methodology for long-term investigation of solid chemical activity in a batch reactor is proposed. The method is based on time variables for oxidation. The results for Ni

  4. The development of chemically vapor deposited mullite coatings for the corrosion protection of SiC

    Energy Technology Data Exchange (ETDEWEB)

    Auger, M.; Hou, P.; Sengupta, A.; Basu, S.; Sarin, V. [Boston Univ., MA (United States)

    1998-05-01

    Crystalline mullite coatings have been chemically vapor deposited onto SiC substrates to enhance the corrosion and oxidation resistance of the substrate. Current research has been divided into three distinct areas: (1) Development of the deposition processing conditions for increased control over coating`s growth rate, microstructure, and morphology; (2) Analysis of the coating`s crystal structure and stability; (3) The corrosion resistance of the CVD mullite coating on SiC.

  5. Mg substituted apatite coating from alkali conversion of acidic calcium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Navarro da Rocha, Daniel, E-mail: dnr.navarro@gmail.com [Military Institute of Engineering-IME, Pça. Gen. Tiburcio, 80, P. Vermelha, Urca, Rio de Janeiro, R.J. (Brazil); Cruz, Leila Rosa de Oliveira [Military Institute of Engineering-IME, Pça. Gen. Tiburcio, 80, P. Vermelha, Urca, Rio de Janeiro, R.J. (Brazil); Campos, José Brant de [Rio de Janeiro State University - UERJ, Rio de Janeiro, R.J. (Brazil); Marçal, Rubens L. Santana Blazutti [Military Institute of Engineering-IME, Pça. Gen. Tiburcio, 80, P. Vermelha, Urca, Rio de Janeiro, R.J. (Brazil); Mijares, Dindo Q.; Coelho, Paulo G. [Department of Biomaterials and Biomimetics, New York University College of Dentistry (NYU), New York, NY (United States); Prado da Silva, Marcelo H. [Military Institute of Engineering-IME, Pça. Gen. Tiburcio, 80, P. Vermelha, Urca, Rio de Janeiro, R.J. (Brazil)

    2017-01-01

    In this work, two solutions were developed: the first, rich in Ca{sup 2+}, PO{sub 4}{sup 3−} ions and the second, rich in Ca{sup 2+}, PO{sub 4}{sup 3−} and Mg{sup 2+}, defined as Mg-modified precursor solution. For each Mg-modified precursor solution, the concentrations of Mg{sup 2+} ions were progressively increased by 5%, 10% and 15%wt. The aims of this research were to investigate the influence of magnesium ions substitution in calcium phosphate coatings on titanium surface and to evaluate these coatings by bioactivity assay in McCoy culture medium. The obtained coatings were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis, and the presence of Mg ions was confirmed by the inductively coupled plasma atomic emission spectroscopy (ICP) analysis. In vitro bioactivity assay in McCoy culture medium showed bioactivity after 14 days in incubation for the HA and 10% Mg-monetite coatings. The high chemical stability of Mg-HA coatings was verified by the bioactivity assays, and no bone-like apatite deposition, characteristic of bioactivity, was observed for Mg-HA coatings, for the time period used in this study. - Highlights: • The presence of Mg ions influenced the final apatite phase present in the produced coatings. • A lower efficiency in heterogeneous deposition and an exposure of Ti substrate in 5% Mg-monetite coatings was soon verified. • McCoy culture medium was effective in predicting the coatings bioactivity.

  6. On the growth of conversion chromate coatings on 2024-Al alloy

    International Nuclear Information System (INIS)

    Kulinich, S.A.; Akhtar, A.S.; Susac, D.; Wong, P.C.; Wong, K.C.; Mitchell, K.A.R.

    2007-01-01

    The initial growth of chromate conversion coatings on aluminium 2024-T3 alloy has been investigated by scanning Auger microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The coating initiation is shown to be influenced by the alloy microstructure. In agreement with previously proposed growth models, Cr(VI) to Cr(III) reduction begins on the Al-Cu-Fe-Mn intermetallic second-phase particles, which act as cathodic sites, and then over the entire Al matrix surface. The less noble Al-Cu-Mg second-phase particles demonstrate dual behaviour during the initial stage of coating; some dealloy, with formation of a Cu-rich sponge-like structure, while others show no evidence for etching during the first few seconds and coating deposits on them similar to the situation for the Al-Cu-Fe-Mn particles. XPS measurements show more Cr(III) at the very initial stage of nucleation and growth, whereas the amount of Cr(VI) in the coating increases with the length of the chromating treatment. This is discussed in relation to Raman spectroscopy measurements made in a separate study

  7. Rare earth conversion coatings grown on AA6061 aluminum alloys. Corrosion studies

    Energy Technology Data Exchange (ETDEWEB)

    Brachetti S, S. B. [Instituto Tecnologico de Ciudad Madero, Av. 1o. de Mayo y Sor Juana I. de la Cruz, Col. Los Mangos, 89440 Ciudad Madero, Tanaulipas (Mexico); Dominguez C, M. A.; Torres H, A. M.; Onofre B, E. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada - Altamira, Carretera Tampico-Puerto Industrial Altamira Km. 14.5, 89600 Altamira, Tamaulipas (Mexico); De la Cruz H, W., E-mail: mdominguezc@ipn.mx [UNAM, Centro de Nanociencias y Nanotecnologia, Apdo. Postal 2681, 22800 Ensenada, Baja California (Mexico)

    2014-07-01

    The present work is aimed to investigate the corrosion resistance of rare earth protective coatings deposited by spontaneous deposition on AA6061 aluminum alloy substrates. Coatings were deposited from water-based Ce(NO{sub 3}){sub 3} and La(NO{sub 3}){sub 3} solutions by varing parameters such as rare earth solution concentration, bath temperature and immersion time. The values of the Tafel slopes indicate that the cathodic process is favored by concentration polarization rather than activation polarization. Chemical and morphological characterizations of the surface before and after electrochemical evaluations were performed by X-ray photoelectron spectroscopy and scanning electron microscopy. (Author)

  8. Rare earth conversion coatings grown on AA6061 aluminum alloys. Corrosion studies

    International Nuclear Information System (INIS)

    Brachetti S, S. B.; Dominguez C, M. A.; Torres H, A. M.; Onofre B, E.; De la Cruz H, W.

    2014-01-01

    The present work is aimed to investigate the corrosion resistance of rare earth protective coatings deposited by spontaneous deposition on AA6061 aluminum alloy substrates. Coatings were deposited from water-based Ce(NO 3 ) 3 and La(NO 3 ) 3 solutions by varing parameters such as rare earth solution concentration, bath temperature and immersion time. The values of the Tafel slopes indicate that the cathodic process is favored by concentration polarization rather than activation polarization. Chemical and morphological characterizations of the surface before and after electrochemical evaluations were performed by X-ray photoelectron spectroscopy and scanning electron microscopy. (Author)

  9. Synthesis of mullite coatings by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

    Formation of mullite on ceramic substrates via chemical vapor deposition was investigated. Mullite is a solid solution of Al{sub 2}O{sub 3} and SiO{sub 2} with a composition of 3Al{sub 2}O{sub 3}{circ}2SiO{sub 2}. Thermodynamic calculations performed on the AlCl{sub 3}-SiCl{sub 4}-CO{sub 2}-H{sub 2} system were used to construct equilibrium CVD phase diagrams. With the aid of these diagrams and consideration of kinetic rate limiting factors, initial process parameters were determined. Through process optimization, crystalline CVD mullite coatings have been successfully grown on SiC and Si{sub 3}N{sub 4} substrates. Results from the thermodynamic analysis, process optimization, and effect of various process parameters on deposition rate and coating morphology are discussed.

  10. Conversion of zircaloy to a massive chemically inert form

    International Nuclear Information System (INIS)

    Atkinson, A.; Kearsey, H.A.; Knibbs, R.H.; Mercer, A.C.; Nickerson, A.K.; Pearson, D.; Sambell, R.A.J.; Taylor, R.I.

    1985-01-01

    The report covers work carried out in the period July 1980 - December 1982 on the development and assessment of an aqueous route for the conversion of Zircaloy fuel element cladding to a stable oxide form and on alternative methods for incorporating the oxide into monolithic waste forms suitable for long-term storage and disposal. The work included two aspects, preliminary process development studies aimed at demonstrating the key steps in the process, and studies on the alternative immobilization techniques and the properties of the resulting waste forms. Experimental studies have shown that the ''hydrous zirconium oxide'' (with a residual fluoride content), following calcination at about 500 0 C, can be hot-pressed at 800-1000 0 C and 22.5 MPa to a high density ceramic waste form with good capacity for the incorporation of active species, such as U 4+ and Sr 2+ , and high leach resistance. Parallel studies have been carried out on the incorporation of the washed ''hydrous zirconium oxide'' in a range of cement matrices. A preliminary chemical engineering assessment of the overall process has been made and flowsheets for a plant to convert 250 kg Zircaloy/day have been prepared

  11. CONVERSION OF LIGNOCELLULOSIC MATERIAL TO CHEMICALS AND FUELS; TOPICAL

    International Nuclear Information System (INIS)

    Edwin S. Olson

    2001-01-01

    A direct conversion of cellulosic wastes, including resin-bonded furniture and building waste, to levulinate esters is being investigated with the view to producing fuels, solvents, and chemical intermediates as well as other useful by-products in an inexpensive process. The acid-catalyzed reaction of cellulosic materials with ethanol or methanol at 200 C gives good yields of levulinate and formate esters, as well as useful by-products, such as a solid residue (charcoal) and a resinous lignin residue. An initial plant design showed reasonable rates of return for production of purified ethyl levulinate and by-products. In this project, investigations have been performed to identify and develop reactions that utilize esters of levulinic acid produced during the acid-catalyzed ethanolysis reaction. We wish to develop uses for levulinate esters that allow their marketing at prices comparable to inexpensive polymer intermediates. These prices will allow a sufficient rate of return to justify building plants for utilizing the waste lignocellulosics. If need is demonstrated for purified levulinate, the initial plant design work may be adequate, at least until further pilot-scale work on the process is performed

  12. Development of chemical conversion process of long-lived radionuclides

    International Nuclear Information System (INIS)

    Yoo, Jae Hyung; Lee, Byung Gik; Kang, Young Ho

    2001-05-01

    The objective of this project is to develop a conversion technology of long-lived radionuclides so that it can be a suitable form as a fuel or target in the nuclear transmutation system. During the first stage of the project (Apr 1997∼Mar 2001), the fundamental studies were performed with a focus on non-radioactive experiments as well as theoretical analyses in such areas as follows : fluorination of metals or metal oxides, electrorefining and electrowinning of actinides and lanthanides, pyro hydrolysis and regeneration of used molten salt. Since the chemical form of transuranium fuel in the transmutation system was assumed to be a molten fluoride, the electrolysis experiments of molten fluoride were conducted to study on the recovery of unused transuranium from the LiF-BeF 2 salt that was chosen as a basic salt medium. Fluorination of metals or metal oxides were also tested in this work by applying the method of three-phase (gas-liquid-solid) reaction. In the electrowinning experiments, the depositions of uranium, zirconium and niobium on the cathode were tested and analyzed. The electrorefining of lanthanides was studied with the salt media of FLINAK and FLICA and their behaviors were compared. In addition, the regeneration of used salts was examined by applying the method of electrolysis of molten salt, where alkali and alkali earth metals were found to be removed into the liquid lead cathode

  13. Chemical Decontamination of Metallic Waste from Uranium Conversion Plant Dismantling

    International Nuclear Information System (INIS)

    Hwang, D. S.; Choi, Y. D.; Hwang, S. T.; Park, J. H.; Byun, J. I.; Jang, N. S.

    2005-01-01

    Korea Atomic Energy Research Institute (KAERI) started a decommissioning program of the uranium conversion plant. Pre-work was carried as follows; installation of the access control facility, installation of a changing room and shower room, designation of an emergency exit way and indicating signs, installation of a radiation management facility, preparation of a storage area for tools and equipments, inspection and load test of crane, distribution and packaging of existing waste, and pre-decontamination of the equipment surface and the interior. First, decommissioning work was performed in kiln room, which will be used for temporary radioactive waste storage room. Kiln room housed hydro fluorination rotary kiln for production of uranium tetra-fluoride. The kiln is about 0.8 m in diameter and 5.5 m long. The total dismantled waste was 6,690 kg, 73 % of which was metallic waste and 27 % the others such as cable, asbestos, concrete, secondary waste, etc. And effluent treatment room and filtration room were dismantled for installation of decontamination equipment and lagoon sludge treatment equipment. There were tanks and square mixer in these rooms. The total dismantled waste was 17,250 kg, 67% of which was metallic waste and 33% the others. These dismantled metallic wastes consist of stainless and carbon steel. In this paper, the stainless steel plate and pipe were decontaminated by the chemical decontamination with ultrasonic

  14. Technology of combined chemical-mechanical fabrication of durable coatings

    Science.gov (United States)

    Smolentsev, V. P.; Ivanov, V. V.; Portnykh, A. I.

    2018-03-01

    The article presents the scientific fundamentals of methodology for calculating the modes and structuring the technological processes of combined chemical-mechanical fabrication of durable coatings. It is shown that they are based on classical patterns, describing the processes of simultaneous chemical and mechanical impact. The paper demonstrates the possibility of structuring a technological process, taking into account the systematic approach to impact management and strengthening the reciprocal positive influence of each impact upon the combined process. The combined processes have been planned for fabricating the model types of chemical-mechanical coatings of durable products in machine construction. The planning methodology is underpinned by a scientific hypothesis of a single source of impact management through energy potential of process components themselves, or by means of external energy supply through mechanical impact. The control of it is fairly thoroughly studied in the case of pulsed external strikes of hard pellets, similar to processes of vibroimpact hardening, thoroughly studied and mastered in many scientific schools of Russia.

  15. Simple down conversion nano-crystal coatings for enhancing Silicon-solar cells efficiency

    Directory of Open Access Journals (Sweden)

    Gur Mittelman

    2016-09-01

    Full Text Available Utilizing self-assembled nano-structured coatings on top of existing solar cells has thepotential to increase the total quantum efficiency of the cell using a simple and cheap process. In ourwork we have exploited the controlled absorption of nano-crystal with different band gaps to realizedown conversion artificial antennas that self-assembled on the device surface. The UV sun light isconverted to the visible light enhancing the solar cell performance in two complementary routes; a.protecting the solar cell and coatings from the UV illumination and therefore reducing the UVradiation damage. b. enhancing the total external quantum efficiency of the cell by one percent. Thisis achieved using a simple cheap process that can be adjusted to many different solar cells.

  16. Preparation and properties of chrome-free colored Ti/Zr based conversion coating on aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yi Aihua [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Li Wenfang, E-mail: mewfl@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Du Jun; Mu Songlin [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2012-06-01

    A golden conversion coating on the surface of aluminum alloy was prepared by adding tannic acid and coating-forming accelerator in the treatment solution containing titanium and zirconium ions. The growth process, main component and corrosion resistance of the conversion coating were characterized by EDS, SEM, XRD, XPS, FIIR and electrochemical workstation. The results showed that the main components of the conversion coating were Na{sub 3}AlF{sub 6} and the conversion coating owns a double-layer structure. The outer layer consists of metal-organic complex and the inner layer is mainly made up of Na{sub 3}AlF{sub 6}. The mechanism of the formation of the golden conversion coating can be deemed as nucleation, growth of Na{sub 3}AlF{sub 6} crystal and formation of metal-organic complex. In potentiodynamic polarization test, the corrosion current density decreases to 0.283 {mu}A cm{sup -2} from 5.894 {mu}A cm{sup -2}, which indicates an obvious improvement of corrosion resistance.

  17. Zr-based conversion layer on Zn-Al-Mg alloy coated steel sheets: insights into the formation mechanism

    International Nuclear Information System (INIS)

    Lostak, Thomas; Maljusch, Artjom; Klink, Björn; Krebs, Stefan; Kimpel, Matthias; Flock, Jörg; Schulz, Stephan; Schuhmann, Wolfgang

    2014-01-01

    Zr-based conversion layers are considered as environmentally friendly alternatives replacing trication phosphatation in the automotive industry. Based on excellent electronic barrier properties they provide an effective corrosion protection of the metallic substrate. In this work, thin protective layers were grown on novel Zn-Al-Mg alloy coated steel sheets by increasing the local pH-value at the sample surface leading to deposition of a Zr-based conversion layer. For this purpose Zn-Al-Mg alloy (ZM) coated steel sheets were treated in an aqueous model conversion solution containing well-defined amounts of hexafluorozirconic acid (H 2 ZrF 6 ) and characterized after different immersion times with SKPFM and field emission SEM (FE-SEM)/EDX techniques. A deposition mechanism of Zr-based conversion coatings on microstructural heterogeneous Zn-Al-Mg alloy surfaces was proposed

  18. Thermal conversion of biomass to valuable fuels, chemical feedstocks and chemicals

    Science.gov (United States)

    Peters, William A [Lexington, MA; Howard, Jack B [Winchester, MA; Modestino, Anthony J [Hanson, MA; Vogel, Fredreric [Villigen PSI, CH; Steffin, Carsten R [Herne, DE

    2009-02-24

    A continuous process for the conversion of biomass to form a chemical feedstock is described. The biomass and an exogenous metal oxide, preferably calcium oxide, or metal oxide precursor are continuously fed into a reaction chamber that is operated at a temperature of at least 1400.degree. C. to form reaction products including metal carbide. The metal oxide or metal oxide precursor is capable of forming a hydrolizable metal carbide. The reaction products are quenched to a temperature of 800.degree. C. or less. The resulting metal carbide is separated from the reaction products or, alternatively, when quenched with water, hydolyzed to provide a recoverable hydrocarbon gas feedstock.

  19. Chemical conversion of hemicellulose coproducts from forest biorefineries to polymers and chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Boluk, Y.; Jost, R. [Alberta Research Council, Edmonton, AB (Canada)

    2009-07-01

    Raw material is the basis of the chemical industry. This presentation discussed the chemical conversion of hemicellulose coproducts from forest biorefineries to polymers and chemicals. Biorefining pretreatment processes open up the biomass structure, release hemicelluloses and overcome the resistance to enzymatic hydrolysis. Although hemicellulose is the second most abundant carbohydrate, it does not have many industrial applications. The state of released hemicellulose whether polymeric, oligomeric or monosaccharides depends primarily on the pretreatment process conditions. Physical pretreatment methods include high-pressure steaming and steam explosion; milling and grinding; extrusion; and high-energy radiation. The chemical pretreatment methods involve the use of alkali, acid, gas and oxidizing agents as well as solvents. The biological pretreatment methods involve the use of lignin consuming fungi and cellulose consuming fungi. A profitable use of C5 sugars in monomeric, oligomeric and polymeric forms is necessary for a viable wood to bioethanol process. Hemicellulose composition varies depending on the biomass source. It usually has a lower molecular weight than cellulose, contains branching, and is comprised of several different monosaccharides. The existing commercial chemical products include xylitol, mannitol, and furfural. The hemicellulose coproducts from a lignocellulosic biorefinery have the potential to become a feasible replacement for their fossil-based equivalents. tabs., figs.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-06-01

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

  1. The preparation and corrosion behaviors of MAO coating on AZ91D with rare earth conversion precursor film

    International Nuclear Information System (INIS)

    Cai Jingshun; Cao Fahe; Chang Linrong; Zheng Junjun; Zhang Jianqing; Cao Chunan

    2011-01-01

    A novel kind of micro-arc oxidation (MAO) coating was prepared on magnesium alloy surface coated with rare earth conversion film (RE-film) in an alkaline aluminum oxidation electrolyte by AC power source. Inspection of scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) microspectroscopy, the structure and composition of MAO coating formed on AZ91D with RE-film under different applied voltages were investigated and the performance of the optimized MAO coating compared with the MAO coating directly formed on magnesium alloy. As the pretreatment of magnesium alloy with RE-film, the cerium oxides can be incorporated into the MAO coatings, reduce porosity of the MAO coating surface and enhance the thickness of MAO coating. These structure features and the cerium oxides incorporated into the MAO coating result in greatly improved corrosion resistance. Base on electrochemistry impedance spectroscopy (EIS) measurement, the electronic structure and composition analysis of the MAO coating, a double-layer structure, with a compact inner layer and a porous outer layer, of the coating was proposed for understanding its corrosion process.

  2. The preparation and corrosion behaviors of MAO coating on AZ91D with rare earth conversion precursor film

    Energy Technology Data Exchange (ETDEWEB)

    Cai Jingshun [Department of Chemistry, Zhejiang University, Zheda Road 38, Hangzhou, Zhejiang 310027 (China); Cao Fahe, E-mail: nelson_cao@zju.edu.cn [Department of Chemistry, Zhejiang University, Zheda Road 38, Hangzhou, Zhejiang 310027 (China); Chang Linrong; Zheng Junjun [Department of Chemistry, Zhejiang University, Zheda Road 38, Hangzhou, Zhejiang 310027 (China); Zhang Jianqing; Cao Chunan [Department of Chemistry, Zhejiang University, Zheda Road 38, Hangzhou, Zhejiang 310027 (China); State Key Laboratory for Corrosion and Protection, Institute of Metal Research, The Chinese Academy of Sciences, Shenyang 110016 (China)

    2011-02-01

    A novel kind of micro-arc oxidation (MAO) coating was prepared on magnesium alloy surface coated with rare earth conversion film (RE-film) in an alkaline aluminum oxidation electrolyte by AC power source. Inspection of scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) microspectroscopy, the structure and composition of MAO coating formed on AZ91D with RE-film under different applied voltages were investigated and the performance of the optimized MAO coating compared with the MAO coating directly formed on magnesium alloy. As the pretreatment of magnesium alloy with RE-film, the cerium oxides can be incorporated into the MAO coatings, reduce porosity of the MAO coating surface and enhance the thickness of MAO coating. These structure features and the cerium oxides incorporated into the MAO coating result in greatly improved corrosion resistance. Base on electrochemistry impedance spectroscopy (EIS) measurement, the electronic structure and composition analysis of the MAO coating, a double-layer structure, with a compact inner layer and a porous outer layer, of the coating was proposed for understanding its corrosion process.

  3. Effects of combined organic and inorganic corrosion inhibitors on the nanostructure cerium based conversion coating performance on AZ31 magnesium alloy: Morphological and corrosion studies

    International Nuclear Information System (INIS)

    Saei, E.; Ramezanzadeh, B.; Amini, R.; Kalajahi, M. Salami

    2017-01-01

    Highlights: •Cn-Mn-polyvinyl alcohol conversion coating led to more uniform and crack free film deposition. •The corrosion resistance of Ce film was noticeably improved by using combination of polyvinyl alchol and Mn2+ cations. •A synergistic effect between polyvinyl alchol-Mn2+ resulted in Ce film with enhanced morphology and corrosion resistance. -- Abstract: Magnesium (Mg) AZ31 samples were chemically treated by a series of room temperature nanostructure cerium based conversion coatings containing Mn(NO 3 ) 2 ·4H 2 O, Co(NO 3 ) 2 ·6H 2 O, and polyvinyl alcohol (PVA). The microstructure and corrosion protection properties of different samples were studied by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and polarization test in 3.5 wt.% NaCl solution. Results demonstrated that the AZ31 Mg alloy sample treated by Ce-Mn-PVA showed the highest corrosion resistance. A denser Ce film with lower crack was precipitated on the sample treated by Ce-Mn-PVA conversion coating.

  4. Assessment of Some Advanced Protective Schemes, Including Chromate and Non-Chromate Conversion Coatings for Mg Alloy ZE41A-T5 Using Electrochemical Impedance Spectroscopy

    National Research Council Canada - National Science Library

    Chang, Frank

    1994-01-01

    .... Electrochemical Impedance Spectroscopy (EIS) and salt spray tests have been employed to compare the corrosion behavior in chloride containing solutions of Mg alloy ZE41A-T5 which has been coated with various combinations of a conversion coating...

  5. GM 9540P Cyclic Accelerated Corrosion Analysis of Nonchromate Conversion Coatings on Aluminum Alloys 2024, 2219, 5083, and 7075 Using DOD Paint Systems

    National Research Council Canada - National Science Library

    Placzankis, Brian

    2003-01-01

    This study examines corrosion resistance of eight nonchromate conversion coatings versus hexavalent chromium based Alodine 1200 controls on scribed coated test panels of aluminum alloys 2024, 2219, 5083, and 7075...

  6. GM 9540P Cyclic Accelerated Corrosion Analysis of Nonchromate Conversion Coatings on Aluminum Alloys 2024, 2219, 5083, and 7075 Using DoD Paint Systems

    National Research Council Canada - National Science Library

    Placzankis, Brian

    2003-01-01

    This study examines corrosion resistance of eight nonchromate conversion coatings versus bexavalent chromium based Alodine 1200 controls on scribed coated test panels of aluminum alloys 2024, 2219, 5083, and 7075...

  7. Effect of biomass feedstock chemical and physical properties on energy conversion processes: Volume 1, Overview

    Energy Technology Data Exchange (ETDEWEB)

    Butner, R.S.; Elliott, D.C.; Sealock, L.J. Jr.; Pyne, J.W.

    1988-12-01

    Pacific Northwest Laboratory has completed an initial investigation of the effects of physical and chemical properties of biomass feedstocks relative to their performance in biomass energy conversion systems. Both biochemical conversion routes (anaerobic digestion and ethanol fermentation) and thermochemical routes (combustion, pyrolysis, and gasification) were included in the study. Related processes including chemical and physical pretreatment to improve digestibility, and size and density modification processes such as milling and pelletizing were also examined. This overview report provides background and discussion of feedstock and conversion relationships, along with recommendations for future research. The recommendations include (1) coordinate production and conversion research programs; (2) quantify the relationship between feedstock properties and conversion priorities; (3) develop a common framework for evaluating and characterizing biomass feedstocks; (4) include conversion effects as part of the criteria for selecting feedstock breeding programs; and (5) continue emphasis on multiple feedstock/conversion options for biomass energy systems. 9 refs., 3 figs., 2 tabs.

  8. Low temperature radio-chemical energy conversion processes

    International Nuclear Information System (INIS)

    Gomberg, H.J.

    1986-01-01

    This patent describes a radio-chemical method of converting radiated energy into chemical energy form comprising the steps of: (a) establishing a starting chemical compound in the liquid phase that chemically reacts endothermically to radiation and heat energy to produce a gaseous and a solid constituent of the compound, (b) irradiating the compound in its liquid phase free of solvents to chemically release therefrom in response to the radiation the gaseous and solid constituents, (c) physically separating the solid and gaseous phase constituents from the liquid, and (d) chemically processing the constituents to recover therefrom energy stored therein by the irradiation step (b)

  9. Research on chemical vapor deposition processes for advanced ceramic coatings

    Science.gov (United States)

    Rosner, Daniel E.

    1993-01-01

    Our interdisciplinary background and fundamentally-oriented studies of the laws governing multi-component chemical vapor deposition (VD), particle deposition (PD), and their interactions, put the Yale University HTCRE Laboratory in a unique position to significantly advance the 'state-of-the-art' of chemical vapor deposition (CVD) R&D. With NASA-Lewis RC financial support, we initiated a program in March of 1988 that has led to the advances described in this report (Section 2) in predicting chemical vapor transport in high temperature systems relevant to the fabrication of refractory ceramic coatings for turbine engine components. This Final Report covers our principal results and activities for the total NASA grant of $190,000. over the 4.67 year period: 1 March 1988-1 November 1992. Since our methods and the technical details are contained in the publications listed (9 Abstracts are given as Appendices) our emphasis here is on broad conclusions/implications and administrative data, including personnel, talks, interactions with industry, and some known applications of our work.

  10. Deactivating Chemical Agents Using Enzyme-Coated Nanofibers Formed by Electrospinning

    Science.gov (United States)

    2016-01-01

    7.3mM/mg). Key words Coaxial electrospinning, DFPase, Enzyme, chemical warfare , nanofiber, decontamination . Introduction Chemical warfare ...Krile, R.; Nishioka, M.; Taylor, M.; Riggs, K.; Stone, H. Decontamination of Toxic Industrial Chemicals and Chemical Warfare Agents On Building...298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 MATS COATINGS ELECTROSPINNING CHEMICAL WARFARE

  11. Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kun; Liu, Junyao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Lei, Ting, E-mail: tlei@mail.csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Xiao, Tao [2nd Xiangya Hospital, Central South University, Changsha 410011 (China)

    2015-10-30

    Highlights: • The optimum operating conditions were determined by an orthogonal experiment. • The coating is composed of oxides and hydroxides of V{sup 5+}, V{sup 4+} and Mg(OH){sub 2}. • The self-healing performance was investigated by cross-cut immersion test. • The vanadia conversion coating provided active corrosion protection to AZ31 alloy. - Abstract: A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

  12. Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Li, Kun; Liu, Junyao; Lei, Ting; Xiao, Tao

    2015-01-01

    Highlights: • The optimum operating conditions were determined by an orthogonal experiment. • The coating is composed of oxides and hydroxides of V"5"+, V"4"+ and Mg(OH)_2. • The self-healing performance was investigated by cross-cut immersion test. • The vanadia conversion coating provided active corrosion protection to AZ31 alloy. - Abstract: A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

  13. Photoassisted electrolysis of water - Conversion of optical to chemical energy

    Science.gov (United States)

    Wrighton, M. S.; Bolts, J. M.; Kaiser, S. W.; Ellis, A. B.

    1976-01-01

    A description is given of devices, termed photoelectrochemical cells, which can, in principle, be used to directly convert light to fuels and/or electricity. The fundamental principles on which the photoelectrochemical cell is based are related to the observation that irradiation of a semiconductor electrode in an electrochemical cell can result in the flow of an electric current in the external circuit. Attention is given to the basic mechanisms involved, the energy conversion efficiency, the advantages of photoelectrochemical cells, and the results of investigations related to the study of energy conversion via photoelectrochemical cells.

  14. A Molecularly Imprinted Polymer (MIP)-Coated Microbeam MEMS Sensor for Chemical Detection

    Science.gov (United States)

    2015-09-01

    ARL-RP-0536 ● SEP 2015 US Army Research Laboratory A Molecularly Imprinted Polymer (MIP)- Coated Microbeam MEMS Sensor for...ARL-RP-0536 ● SEP 2015 US Army Research Laboratory A Molecularly Imprinted Polymer (MIP)- Coated Microbeam MEMS Sensor for Chemical...TITLE AND SUBTITLE A Molecularly Imprinted Polymer (MIP)-Coated Microbeam MEMS Sensor for Chemical Detection 5a. CONTRACT NUMBER 5b. GRANT NUMBER

  15. 75 FR 52355 - Draft National Conversation on Public Health and Chemical Exposures Work Group Reports...

    Science.gov (United States)

    2010-08-25

    ... DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention Draft National Conversation on Public Health and Chemical Exposures Work Group Reports; Opportunity for Public Comment AGENCY.../nationalconversation/work_groups.html . For additional information on the National Conversation on Public Health and...

  16. Formation, adhesion and mechanical/chemical properties of protective coatings

    International Nuclear Information System (INIS)

    Mattox, D.M.

    1979-01-01

    Some general considerations for protective coatings are discussed. It is suggested that ceramic coatings may provide a class of coatings applicable to high temperature turbine blades for use in a corrosive/erosive environment. In particular, the ceraming glass materials would seem to hold promise, but little or nothing has been done on depositing these materials by vacuum processes

  17. SiO2 coating of silver nanoparticles by photoinduced chemical vapor deposition

    International Nuclear Information System (INIS)

    Boies, Adam M; Girshick, Steven L; Roberts, Jeffrey T; Zhang Bin; Nakamura, Toshitaka; Mochizuki, Amane

    2009-01-01

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO 2 ) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO 2 precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO 2 coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 0 C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10 7 particles cm -3 .

  18. Coating of ceramic powders by chemical vapor deposition techniques (CVD)

    International Nuclear Information System (INIS)

    Haubner, R.; Lux, B.

    1997-01-01

    New ceramic materials with selected advanced properties can be designed by coating of ceramic powders prior to sintering. By variation of the core and coating material a large number of various powders and ceramic materials can be produced. Powders which react with the binder phase during sintering can be coated with stable materials. Thermal expansion of the ceramic materials can be adjusted by varying the coating thickness (ratio core/layer). Electrical and wear resistant properties can be optimized for electrical contacts. A fluidized bed reactor will be designed which allow the deposition of various coatings on ceramic powders. (author)

  19. Overall efficiencies for conversion of solar energy to a chemical fuel

    Science.gov (United States)

    Fish, J. D.

    A complete and consistent scheme for determining the overall efficiency of a generalized process for the conversion of solar energy into a chemical fuel (e.g. hydrogen) is developed and applied to seven conversion processes: thermal, thermochemical, photovoltaic, photogalvanic, photoelectrolysis, photosynthesis and photochemical conversion. It is demonstrated that the overall efficiency of each of these processes is determined by ten common factors: maximum theoretical efficiency, inherent absorption losses, inherent internal losses, rate limiting effects, reflection losses, transmission losses, coverage losses, system construction requirements, parasitic losses and harvesting and conversion losses. Both state-of-the-art and optimistic values are assigned to each factor for each of the seven conversion processes. State-of-the-art overall efficiencies ranged from 5% for thermal conversion down to essentially zero for thermochemical. Optimistic values in the range of about 10 to 15% are calculated for several of the processes.

  20. Chemocatalytic Conversion of Ethanol into Butadiene and Other Bulk Chemicals

    NARCIS (Netherlands)

    Angelici, C.|info:eu-repo/dai/nl/345731506; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397; Bruijnincx, P.C.A.|info:eu-repo/dai/nl/33799529X

    2013-01-01

    The development of new and improved processes for the synthesis of bio-based chemicals is one of the scientific challenges of our time. These new discoveries are not only important from an environmental point of view, but also represent an important economic opportunity, provided that the developed

  1. Characterization of the corrosion protection mechanism of cerium-based conversion coatings on high strength aluminum alloys

    Science.gov (United States)

    Pinc, William Ross

    The aim of the work presented in this dissertation is to investigate the corrosion protection mechanism of cerium-based conversion coatings (CeCCs) used in the corrosion protection of high strength aluminum alloys. The corrosion resistance of CeCCs involves two general mechanisms; barrier and active. The barrier protection mechanism was influenced by processing parameters, specifically surface preparation, post-treatment, and the use of gelatin. Post-treatment and the addition of gelatin to the coating solution resulted in fewer cracks and transformation of the coating to CePO4, which increased the corrosion resistance by improving the barrier aspect of CeCCs. CeCCs were found to best act as barriers when crack size was limited and CePO4 was present in the coating. CeCCs were found to protect areas of the substrate that were exposed in the coating, indicating that the coatings were more than simple barriers. CeCCs contained large cracks, underneath which subsurface crevices were connected to the surface by the cracks. Despite the observation that no cerium was present in crevices, coatings with crevices exhibited significant corrosion protection. The impedance of post-treated coatings with crevices increased during salt spray exposure. The increase in impedance was associated with the formation of protective oxides / hydroxides; however, crevice-free coatings also exhibited active protection leading to the conclusion that the formation of interfacial layers between the CeCC and the substrate also contributed to the active protection. Based on the overall results of the study, the optimal corrosion protection of CeCCs occurred when processing conditions produced coatings with morphologies and compositions that facilitated both the barrier and active protection mechanisms.

  2. Conversion of Lignocellulosic Biomass to Nanocellulose: Structure and Chemical Process

    Directory of Open Access Journals (Sweden)

    H. V. Lee

    2014-01-01

    Full Text Available Lignocellulosic biomass is a complex biopolymer that is primary composed of cellulose, hemicellulose, and lignin. The presence of cellulose in biomass is able to depolymerise into nanodimension biomaterial, with exceptional mechanical properties for biocomposites, pharmaceutical carriers, and electronic substrate’s application. However, the entangled biomass ultrastructure consists of inherent properties, such as strong lignin layers, low cellulose accessibility to chemicals, and high cellulose crystallinity, which inhibit the digestibility of the biomass for cellulose extraction. This situation offers both challenges and promises for the biomass biorefinery development to utilize the cellulose from lignocellulosic biomass. Thus, multistep biorefinery processes are necessary to ensure the deconstruction of noncellulosic content in lignocellulosic biomass, while maintaining cellulose product for further hydrolysis into nanocellulose material. In this review, we discuss the molecular structure basis for biomass recalcitrance, reengineering process of lignocellulosic biomass into nanocellulose via chemical, and novel catalytic approaches. Furthermore, review on catalyst design to overcome key barriers regarding the natural resistance of biomass will be presented herein.

  3. Conversion of Lignocellulosic Biomass to Nanocellulose: Structure and Chemical Process

    Science.gov (United States)

    Lee, H. V.; Hamid, S. B. A.; Zain, S. K.

    2014-01-01

    Lignocellulosic biomass is a complex biopolymer that is primary composed of cellulose, hemicellulose, and lignin. The presence of cellulose in biomass is able to depolymerise into nanodimension biomaterial, with exceptional mechanical properties for biocomposites, pharmaceutical carriers, and electronic substrate's application. However, the entangled biomass ultrastructure consists of inherent properties, such as strong lignin layers, low cellulose accessibility to chemicals, and high cellulose crystallinity, which inhibit the digestibility of the biomass for cellulose extraction. This situation offers both challenges and promises for the biomass biorefinery development to utilize the cellulose from lignocellulosic biomass. Thus, multistep biorefinery processes are necessary to ensure the deconstruction of noncellulosic content in lignocellulosic biomass, while maintaining cellulose product for further hydrolysis into nanocellulose material. In this review, we discuss the molecular structure basis for biomass recalcitrance, reengineering process of lignocellulosic biomass into nanocellulose via chemical, and novel catalytic approaches. Furthermore, review on catalyst design to overcome key barriers regarding the natural resistance of biomass will be presented herein. PMID:25247208

  4. Study on the deterioration process of a chromium-free conversion coating on AZ91D magnesium alloy in NaCl solution

    International Nuclear Information System (INIS)

    Zhao Ming; Wu Shusen; An Ping; Luo Jirong

    2006-01-01

    The morphology of a chromium-free conversion coating for AZ91D magnesium alloy was observed with an Atomic Force Microscopy. The results showed the uniform conversion coating has a relatively smooth appearance with shallow valleys. The EDX results indicated that the compositions of the coating were mainly compounds of Mg, Al, Mn, P, Ca and O. The XRD result showed that the coating contained amorphous materials and a small quantity of crystalline compound. The pitting product of the coating in NaCl water solution mainly composed of Mg, Cl, Mn, P, Ca and O. The corrosion behavior of the samples in NaCl solution was also studied by electrochemical impedance spectroscopy (EIS), which was characterized by one capacitive loop and one inductive loop. Based upon study on both a mathematical model for Faradic admittance of coating in NaCl solution and EIS, it could be considered that the inductive loop was caused by the adsorption of Cl anion and the appearance of pitting corrosion. A degradation mechanism of the coating in NaCl solution is set forth: dissolution velocity of the Cl - adsorption regions of the coating is higher than those non-adsorption regions, for Cl - anions are selective adsorption at some regions of coating surface. When the adsorption regions of coating layer are penetrated by dissolution, the pitting comes into being. The degradation mechanism of conversion coating and the mathematical model are consistent with the EIS results, polarization measurement results and coating's corrosion test results

  5. Self-healing Li-Al layered double hydroxide conversion coating modified with aspartic acid for 6N01 Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Caixia; Luo, Xiaohu; Pan, Xinyu; Liao, Liying; Wu, Xiaosong; Liu, Yali, E-mail: yaliliu@hnu.edu.cn

    2017-02-01

    Highlights: • A self-healing chrome-free Li-Al layered double hydroxide conversion coating modified with Aspartic acid was prepared. • One-step conversion coating formed by simple immersion in a conversion solution for a short time and a low temperature. • The conversion coating had excellent corrosion resistance. • The possible mechanism via exchange/self-assembly of the conversion coating was proposed in this paper. - Abstract: A self-healing Li-Al layered double hydroxide conversion coating (LCC) modified with aspartic acid (ALCC) was prepared on 6N01 Al alloy for corrosion protection. Scanning electron microscopy (SEM) showed that a compact thin film has been successfully formed on the alloy. X-ray diffraction (XRD) and FT-IR spectra proved that species of aspartic acid anions were successfully intercalated into LCC. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) testing showed that the resultant ALCC could provide effective corrosion protection for the Al alloy. During immersion of the ALCC-coated alloy in 3.5% NaCl solution, new film was formed in the area of artificially introduced scratch, indicating its self-healing capability. XPS results demonstrated that Cl- anions exchange partial Asp anions according to the change content of element on conversion coating. From the above results, the possible mechanism via exchange/self-assembly was proposed to illustrate the phenomenon of self-healing.

  6. Self-healing Li-Al layered double hydroxide conversion coating modified with aspartic acid for 6N01 Al alloy

    International Nuclear Information System (INIS)

    Zhang, Caixia; Luo, Xiaohu; Pan, Xinyu; Liao, Liying; Wu, Xiaosong; Liu, Yali

    2017-01-01

    Highlights: • A self-healing chrome-free Li-Al layered double hydroxide conversion coating modified with Aspartic acid was prepared. • One-step conversion coating formed by simple immersion in a conversion solution for a short time and a low temperature. • The conversion coating had excellent corrosion resistance. • The possible mechanism via exchange/self-assembly of the conversion coating was proposed in this paper. - Abstract: A self-healing Li-Al layered double hydroxide conversion coating (LCC) modified with aspartic acid (ALCC) was prepared on 6N01 Al alloy for corrosion protection. Scanning electron microscopy (SEM) showed that a compact thin film has been successfully formed on the alloy. X-ray diffraction (XRD) and FT-IR spectra proved that species of aspartic acid anions were successfully intercalated into LCC. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) testing showed that the resultant ALCC could provide effective corrosion protection for the Al alloy. During immersion of the ALCC-coated alloy in 3.5% NaCl solution, new film was formed in the area of artificially introduced scratch, indicating its self-healing capability. XPS results demonstrated that Cl- anions exchange partial Asp anions according to the change content of element on conversion coating. From the above results, the possible mechanism via exchange/self-assembly was proposed to illustrate the phenomenon of self-healing.

  7. Chemical Production of Graphene Catalysts for Electrochemical Energy Conversion

    DEFF Research Database (Denmark)

    Seselj, Nedjeljko

    by scanning tunneling microscopy (STM), to investigate the nature of L-cysteine bonds on Au. Synthesized electrocatalysts were characterized by spectroscopic, microscopic and electrochemical techniques. Electrocatalysis was examined by electrochemical oxidation of formic acid, methanol and ethanol, and oxygen......Recently developed FC technology is among many approaches aiming at solving the global energy challenges. FCs are electrochemical devices that convert chemical energy from fuel molecules into electrical energy via electrochemical reactions. FCs are, however, limited by the scarce and expensive...... was achieved via L-cysteine linker molecules that provided pathways for fast electron transfers during the electrocatalytic reactions. Electrochemical properties of selfassembled L-cysteine monolayers immobilized on single-crystal Au(111) surfaces were studied in ionic liquids and their structures imaged...

  8. Studies of coupled chemical and catalytic coal conversion methods

    Energy Technology Data Exchange (ETDEWEB)

    Stock, L.M.

    1990-01-01

    This report concerns our research on base-catalyzed coal solubilization and a new approach for hydrogen addition. The work on base-catalyzed, chemical solubilization is continuing. this report is focused on the hydrogenation research. Specifically it deals with the use of arene chromium carbonyl complexes as reagents for the addition of dideuterium to coal molecules. In one phase of the work, he has established that the aromatic hydrocarbons in a representative coal liquid can be converted in very good yield to arene chromium carbonyl compounds. In a second phase of the work directly related to our objective of improved methods for catalytic hydrogenation, he has established that the aromatic constituents of the same coal liquid add dideuterium in the presence of added napththalene chromium carbonyl.

  9. Quantification of simultaneous solvent evaporation and chemical curing in thermoset coatings

    DEFF Research Database (Denmark)

    Kiil, Søren

    2010-01-01

    The mechanisms of simultaneous solvent evaporation and film formation in high-solids thermoset coatings are considered. The relevant phenomena, chemical reactions, solvent diffusion and evaporation, gelation, vitrification, network mobility restrictions, and crosslinking, are quantified and a mat...

  10. Forensic collection of trace chemicals from diverse surfaces with strippable coatings.

    Science.gov (United States)

    Jakubowski, Michael J; Beltis, Kevin J; Drennan, Paul M; Pindzola, Bradford A

    2013-11-07

    Surface sampling for chemical analysis plays a vital role in environmental monitoring, industrial hygiene, homeland security and forensics. The standard surface sampling tool, a simple cotton gauze pad, is failing to meet the needs of the community as analytical techniques become more sensitive and the variety of analytes increases. In previous work, we demonstrated the efficacy of non-destructive, conformal, spray-on strippable coatings for chemical collection from simple glass surfaces. Here we expand that work by presenting chemical collection at a low spiking level (0.1 g m(-2)) from a diverse array of common surfaces - painted metal, engineering plastics, painted wallboard and concrete - using strippable coatings. The collection efficiency of the strippable coatings is compared to and far exceeds gauze pads. Collection from concrete, a particular challenge for wipes like gauze, averaged 73% over eight chemically diverse compounds for the strippable coatings whereas gauze averaged 10%.

  11. Novel Chemical Process for Producing Chrome Coated Metal

    OpenAIRE

    Pelar, Christopher; Greenaway, Karima; Zea, Hugo; Wu, Chun-Hsien; Luhrs, Claudia C.; Phillips, Jonathan

    2018-01-01

    The article of record as published may be found at http://dx.doi.org/10.3390/ma11010078 This work demonstrates that a version of the Reduction Expansion Synthesis (RES) process, Cr-RES, can create a micron scale Cr coating on an iron wire. The process involves three steps. I. A paste consisting of a physical mix of urea, chrome nitrate or chrome oxide, and water is prepared. II. An iron wire is coated by dipping. III. The coated, and dried, wire is heated to ~800 ◦C for 10 min in a tube fu...

  12. Conversion of hazardous plastic wastes into useful chemical products.

    Science.gov (United States)

    Siddiqui, Mohammad Nahid

    2009-08-15

    Azoisobutylnitrile (AIBN) initiator was used in the treatment of most widely used domestic plastics in lieu of catalysts. The pyrolysis of low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), poly-ethylene terephthalate (PET) and polystyrene (PS) plastics with azoisobutylnitrile was carried out individually under nitrogen atmosphere. A series of single (plastic/AIBN) and binary (mixed plastics/AIBN) reactions were carried out in a 25-cm(3) micro-autoclave reactor. The optimum conditions selected for this study were: 5% AIBN by weight of total plastics, 60 min, 650 psi and 420 degrees C. It was found that HDPE, LDPE, PP underwent to a maximum cracking and produced highest amounts of liquid and gaseous products. Pyrolysis of PET and PS plastics with AIBN afforded comparatively significant amount of insoluble organic materials. In other reactions, fixed ratios of mixed plastics were pyrolyzed with AIBN that afforded excellent yields of liquid hydrocarbons. This result shows a very significant increase in the liquid portions of the products on using AIBN in the pyrolysis of plastics. The use of AIBN in the pyrolysis of plastics is seems to be feasible and an environmental friendly alternative to catalytic process for maximizing the liquid fuels or chemical feed stocks in higher amounts.

  13. Conversion of hazardous plastic wastes into useful chemical products

    International Nuclear Information System (INIS)

    Siddiqui, Mohammad Nahid

    2009-01-01

    Azoisobutylnitrile (AIBN) initiator was used in the treatment of most widely used domestic plastics in lieu of catalysts. The pyrolysis of low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), poly-ethylene terephthalate (PET) and polystyrene (PS) plastics with azoisobutylnitrile was carried out individually under nitrogen atmosphere. A series of single (plastic/AIBN) and binary (mixed plastics/AIBN) reactions were carried out in a 25-cm 3 micro-autoclave reactor. The optimum conditions selected for this study were: 5% AIBN by weight of total plastics, 60 min, 650 psi and 420 o C. It was found that HDPE, LDPE, PP underwent to a maximum cracking and produced highest amounts of liquid and gaseous products. Pyrolysis of PET and PS plastics with AIBN afforded comparatively significant amount of insoluble organic materials. In other reactions, fixed ratios of mixed plastics were pyrolyzed with AIBN that afforded excellent yields of liquid hydrocarbons. This result shows a very significant increase in the liquid portions of the products on using AIBN in the pyrolysis of plastics. The use of AIBN in the pyrolysis of plastics is seems to be feasible and an environmental friendly alternative to catalytic process for maximizing the liquid fuels or chemical feed stocks in higher amounts.

  14. Conversion of concentrated solar thermal energy into chemical energy.

    Science.gov (United States)

    Tamaura, Yutaka

    2012-01-01

    When a concentrated solar beam is irradiated to the ceramics such as Ni-ferrite, the high-energy flux in the range of 1500-2500 kW/m(2) is absorbed by an excess Frenkel defect formation. This non-equilibrium state defect is generated not by heating at a low heating-rate (30 K/min), but by irradiating high flux energy of concentrated solar beam rapidly at a high heating rate (200 K/min). The defect can be spontaneously converted to chemical energy of a cation-excess spinel structure (reduced-oxide form) at the temperature around 1773 K. Thus, the O(2) releasing reaction (α-O(2) releasing reaction) proceeds in two-steps; (1) high flux energy of concentrated solar beam absorption by formation of the non-equilibrium Frenkel defect and (2) the O(2) gas formation from the O(2-) in the Frenkel defect even in air atmosphere. The 2nd step proceeds without the solar radiation. We may say that the 1st step is light reaction, and 2nd step, dark reaction, just like in photosynthesis process.

  15. Acid-resistant organic coatings for the chemical industry: a review

    DEFF Research Database (Denmark)

    Møller, Victor Buhl; Dam-Johansen, Kim; Frankær, Sarah Maria Grundahl

    2017-01-01

    Industries that work with acidic chemicals in their processes need to make choices on how to properly contain the substances and avoid rapid corrosion of equipment. Certain organic coatings and linings can be used in such environments, either to protect vulnerable construction materials, or......, in combination with fiber reinforcement, to replace them. However, degradation mechanisms of organic coatings in acid service are not thoroughly understood and relevant quantitative investigations are scarce. This review describes the uses and limitations of acid-resistant coatings in the chemical industry...

  16. Electro-chemical deposition of nano hydroxyapatite-zinc coating on titanium metal substrate.

    Science.gov (United States)

    El-Wassefy, N A; Reicha, F M; Aref, N S

    2017-08-13

    Titanium is an inert metal that does not induce osteogenesis and has no antibacterial properties; it is proposed that hydroxyapatite coating can enhance its bioactivity, while zinc can contribute to antibacterial properties and improve osseointegration. A nano-sized hydroxyapatite-zinc coating was deposited on commercially pure titanium using an electro-chemical process, in order to increase its surface roughness and enhance adhesion properties. The hydroxyapatite-zinc coating was attained using an electro-chemical deposition in a solution composed of a naturally derived calcium carbonate, di-ammonium hydrogen phosphate, with a pure zinc metal as the anode and titanium as the cathode. The applied voltage was -2.5 for 2 h at a temperature of 85 °C. The resultant coating was characterized for its surface morphology and chemical composition using a scanning electron microscope (SEM), energy dispersive x-ray spectroscope (EDS), and Fourier transform infrared (FT-IR) spectrometer. The coated specimens were also evaluated for their surface roughness and adhesion quality. Hydroxyapatite-zinc coating had shown rosette-shaped, homogenous structure with nano-size distribution, as confirmed by SEM analysis. FT-IR and EDS proved that coatings are composed of hydroxyapatite (HA) and zinc. The surface roughness assessment revealed that the coating procedure had significantly increased average roughness (Ra) than the control, while the adhesive tape test demonstrated a high-quality adhesive coat with no laceration on tape removal. The developed in vitro electro-chemical method can be employed for the deposition of an even thickness of nano HA-Zn adhered coatings on titanium substrate and increases its surface roughness significantly.

  17. 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.

  18. A new strategy for improvement of the corrosion resistance of a green cerium conversion coating through thermal treatment procedure before and after application of epoxy coating

    Energy Technology Data Exchange (ETDEWEB)

    Mahidashti, Z. [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box: 14115-143, Tehran (Iran, Islamic Republic of); Shahrabi, T., E-mail: tshahrabi34@modares.ac.ir [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box: 14115-143, Tehran (Iran, Islamic Republic of); Ramezanzadeh, B., E-mail: ramezanzadeh-bh@icrc.ac.ir [Department of Surface Coatings and Corrosion, Institute for Color Science and Technology (ICST), P.O. 16765-654, Tehran (Iran, Islamic Republic of)

    2016-12-30

    Highlights: • The Ce conversion coating was post-heated at various conditions. • The corrosion resistance of post-heated Ce films was evaluated. • A crack free and denser Ce film were obtained after post-heating. • The corrosion resistance of Ce film noticeably increased. • Post-heated Ce film resulted better protection performance of epoxy coating. - Abstract: The effect of post-heating of CeCC on its surface morphology and chemistry has been studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and contact angle (CA) measurements. The corrosion protection performance of the coatings was investigated by electrochemical impedance spectroscopy (EIS). The effect of thermal treatment of CeCC on the corrosion protection performance of epoxy coating was investigated by EIS. Results showed that the heat treatment of Ce film noticeably improved its corrosion resistance and adhesion properties compared to that of untreated samples. The CeCC deposited on the steel substrate at room temperature had a highly cracked structure, while the amount of micro-cracks significantly reduced after post-heating procedure. Results obtained from EIS analysis confirmed the effect of post-heating of CeCC on its corrosion protection performance enhancement. The increase of post-heating temperature and time up to 140 °C and 3 h led to better results.

  19. Green chemicals : A Kinetic Study on the Conversion of Glucose to Levulinic Acid

    NARCIS (Netherlands)

    Girisuta, B.; Janssen, L.P.B.M.; Heeres, H.J.

    2006-01-01

    Levulinic acid has been identified as a promising green, biomass derived platform chemical. A kinetic study on one of the key steps in the conversion of biomass to levulinic acid, i.e., the acid catalysed decomposition of glucose to levulinic acid has been performed. The experiments were performed

  20. The material balance of process of plasma-chemical conversion of polymer wastes into synthesis gas

    International Nuclear Information System (INIS)

    Tazmeev, A Kh; Tazmeeva, R N

    2017-01-01

    The process of conversion of polymer wastes in the flow of water-steam plasma which are created by the liquid electrodes plasma generators was experimentally studied. The material balance was calculated. The regularities of the participating of hydrogen and oxygen which contained in the water-steam plasma, in formation of chemical compounds in the final products were revealed. (paper)

  1. The material balance of process of plasma-chemical conversion of polymer wastes into synthesis gas

    Science.gov (United States)

    Tazmeev, A. Kh; Tazmeeva, R. N.

    2017-01-01

    The process of conversion of polymer wastes in the flow of water-steam plasma which are created by the liquid electrodes plasma generators was experimentally studied. The material balance was calculated. The regularities of the participating of hydrogen and oxygen which contained in the water-steam plasma, in formation of chemical compounds in the final products were revealed.

  2. Effect of biomass feedstock chemical and physical properties on energy conversion processes: Volume 2, Appendices

    Energy Technology Data Exchange (ETDEWEB)

    Butner, R.S.; Elliott, D.C.; Sealock, L.J., Jr.; Pyne, J.W.

    1988-12-01

    This report presents an exploration of the relationships between biomass feedstocks and the conversion processes that utilize them. Specifically, it discusses the effect of the physical and chemical structure of biomass on conversion yields, rates, and efficiencies in a wide variety of available or experimental conversion processes. A greater understanding of the complex relationships between these conversion systems and the production of biomass for energy uses is required to help optimize the complex network of biomass production, collection, transportation, and conversion to useful energy products. The review of the literature confirmed the scarcity of research aimed specifically at identifying the effect of feedstock properties on conversion. In most cases, any mention of feedstock-related effects was limited to a few brief remarks (usually in qualitative terms) in the conclusions, or as a topic for further research. Attempts to determine the importance of feedstock parameters from published data were further hampered by the lack of consistent feedstock characterization and the difficulty of comparing results between different experimental systems. Further research will be required to establish quantitative relationships between feedstocks and performance criteria in conversion. 127 refs., 4 figs., 7 tabs.

  3. Roll-coating fabrication of flexible large area small molecule solar cells with power conversion efficiency exceeding 1%

    DEFF Research Database (Denmark)

    Liu, Wenqing; Liu, Shiyong; Zawacka, Natalia Klaudia

    2014-01-01

    All solution-processed flexible large area small molecule bulk heterojunction solar cells were fabricated via roll-coating technology. Our devices were produced from slot-die coating on a lab-scale mini roll-coater under ambient conditions without the use of spin-coating or vacuum evaporation.......01%, combined with an open circuit voltage of 0.73 V, a short-circuit current density of 3.13 mA cm (2) and a fill factor of 44% were obtained for the device with SM1, which was the first example reported for efficient roll-coating fabrication of flexible large area small molecule solar cells with PCE exceeding...... methods. Four diketopyrrolopyrrole based small molecules (SMs 1-4) were utilized as electron donors with (6,6)phenyl- C61-butyric acid methyl ester as an acceptor and their photovoltaic performances based on roll-coated devices were investigated. The best power conversion efficiency (PCE) of 1...

  4. Effects of acid and alkaline based surface preparations on spray deposited cerium based conversion coatings on Al 2024-T3

    Energy Technology Data Exchange (ETDEWEB)

    Pinc, W. [Department of Materials Science Engineering, Materials Research Center, Missouri University of Science and Technology, Rolla, MO 65409 (United States)], E-mail: wrphw5@mst.edu; Geng, S.; O' Keefe, M.; Fahrenholtz, W.; O' Keefe, T. [Department of Materials Science Engineering, Materials Research Center, Missouri University of Science and Technology, Rolla, MO 65409 (United States)

    2009-01-15

    Cerium based conversion coatings were spray deposited on Al 2024-T3 and characterized to determine the effect of surface preparation on the deposition rate and surface morphology. It was found that activation of the panel using a 1-wt.% sulfuric acid solution increased the coating deposition rate compared to alkaline cleaning alone. Analysis of the surface morphology of the coatings showed that the coatings deposited on the acid treated panels exhibited fewer visible cracks compared to coatings on alkaline cleaned panels. Auger electron spectroscopy depth profiling showed that the acid activation decreased the thickness of the aluminum oxide layer and the concentration of magnesium on the surface of the panels compared to the alkaline treatment. Additionally, acid activation increased the copper concentration at the surface of the aluminum substrate. Based on the results, the acid based surface treatment appeared to expose copper rich intermetallics, thus increasing the number of cathodic sites on the surface, which led to an overall increase in the deposition rate.

  5. Thermo-economic evaluation and optimization of the thermo-chemical conversion of biomass into methanol

    International Nuclear Information System (INIS)

    Peduzzi, Emanuela; Tock, Laurence; Boissonnet, Guillaume; Maréchal, François

    2013-01-01

    In a carbon and resources constrained world, thermo-chemical conversion of lignocellulosic biomass into fuels and chemicals is regarded as a promising alternative to fossil resources derived products. Methanol is one potential product which can be used for the synthesis of various chemicals or as a fuel in fuel cells and internal combustion engines. This study focuses on the evaluation and optimization of the thermodynamic and economic performance of methanol production from biomass by applying process integration and optimization techniques. Results reveal the importance of the energy integration and in particular of the cogeneration of electricity for the efficient use of biomass. - Highlights: • A thermo-economic model for biomass conversion into methanol is developed. • Process integration and multi-objective optimization techniques are applied. • Results reveal the importance of energy integration for electricity co-generation

  6. Oxygen Barrier Coating Deposited by Novel Plasma-enhanced Chemical Vapor Deposition

    DEFF Research Database (Denmark)

    Jiang, Juan; Benter, M.; Taboryski, Rafael Jozef

    2010-01-01

    We report the use of a novel plasma-enhanced chemical vapor deposition chamber with coaxial electrode geometry for the SiOx deposition. This novel plasma setup exploits the diffusion of electrons through the inner most electrode to the interior samples space as the major energy source. This confi......We report the use of a novel plasma-enhanced chemical vapor deposition chamber with coaxial electrode geometry for the SiOx deposition. This novel plasma setup exploits the diffusion of electrons through the inner most electrode to the interior samples space as the major energy source...... effect of single-layer coatings deposited under different reaction conditions was studied. The coating thickness and the carbon content in the coatings were found to be the critical parameters for the barrier property. The novel barrier coating was applied on different polymeric materials...

  7. Physical and chemical analysis of interaction between oxide fuel and pyrocarbon coating of coated particles

    International Nuclear Information System (INIS)

    Lyutikov, R.A.; Kromov, Yu.F.; Chernikov, A.S.

    1991-01-01

    In terms of the model proposed the equilibrium pressure of gases (CO, Kr, Xe) in pyrocarbon-coated uranium dioxide fuel particles has been calculated, as function of the initial composition of the fuel (O/U), the design features of the coated particles, the fuel temperature, and the burnup. The possibility of reducing gas pressure in the particles by alloying the kernels with uranium carbide, and increasing the kernel capacity for retention of solid fission products by alloying the uranium oxide with aluminum-silicates, has been investigated. (author)

  8. Nanostructured Metal Oxide Coatings for Electrochemical Energy Conversion and Storage Electrodes

    Science.gov (United States)

    Cordova, Isvar Abraxas

    The realization of an energy future based on safe, clean, sustainable, and economically viable technologies is one of the grand challenges facing modern society. Electrochemical energy technologies underpin the potential success of this effort to divert energy sources away from fossil fuels, whether one considers alternative energy conversion strategies through photoelectrochemical (PEC) production of chemical fuels or fuel cells run with sustainable hydrogen, or energy storage strategies, such as in batteries and supercapacitors. This dissertation builds on recent advances in nanomaterials design, synthesis, and characterization to develop novel electrodes that can electrochemically convert and store energy. Chapter 2 of this dissertation focuses on refining the properties of TiO2-based PEC water-splitting photoanodes used for the direct electrochemical conversion of solar energy into hydrogen fuel. The approach utilized atomic layer deposition (ALD); a growth process uniquely suited for the conformal and uniform deposition of thin films with angstrom-level thickness precision. ALD's thickness control enabled a better understanding of how the effects of nitrogen doping via NH3 annealing treatments, used to reduce TiO2's bandgap, can have a strong dependence on TiO2's thickness and crystalline quality. In addition, it was found that some of the negative effects on the PEC performance typically associated with N-doped TiO2 could be mitigated if the NH 3-annealing was directly preceded by an air-annealing step, especially for ultrathin (i.e., transparent electrode based on a network of solution-processed Cu/Ni cores/shell nanowires (NWs) were activated by electrochemically converting the Ni metal shell into Ni(OH)2. Furthermore, an adjustment of the molar percentage of Ni plated onto the Cu NWs was found to result in a tradeoff between capacitance, transmittance, and stability of the resulting nickel hydroxide-based electrode. The nominal area capacitance and power

  9. Novel Chemical Process for Producing Chrome Coated Metal

    Directory of Open Access Journals (Sweden)

    Christopher Pelar

    2018-01-01

    Full Text Available This work demonstrates that a version of the Reduction Expansion Synthesis (RES process, Cr-RES, can create a micron scale Cr coating on an iron wire. The process involves three steps. I. A paste consisting of a physical mix of urea, chrome nitrate or chrome oxide, and water is prepared. II. An iron wire is coated by dipping. III. The coated, and dried, wire is heated to ~800 °C for 10 min in a tube furnace under a slow flow of nitrogen gas. The processed wires were then polished and characterized, primarily with scanning electron microscopy (SEM. SEM indicates the chrome layer is uneven, but only on the scale of a fraction of a micron. The evidence of porosity is ambiguous. Elemental mapping using SEM electron microprobe that confirmed the process led to the formation of a chrome metal layer, with no evidence of alloy formation. Additionally, it was found that thickness of the final Cr layer correlated with the thickness of the precursor layer that was applied prior to the heating step. Potentially, this technique could replace electrolytic processing, a process that generates carcinogenic hexavalent chrome, but further study and development is needed.

  10. Novel Chemical Process for Producing Chrome Coated Metal.

    Science.gov (United States)

    Pelar, Christopher; Greenaway, Karima; Zea, Hugo; Wu, Chun-Hsien; Luhrs, Claudia C; Phillips, Jonathan

    2018-01-05

    This work demonstrates that a version of the Reduction Expansion Synthesis (RES) process, Cr-RES, can create a micron scale Cr coating on an iron wire. The process involves three steps. I. A paste consisting of a physical mix of urea, chrome nitrate or chrome oxide, and water is prepared. II. An iron wire is coated by dipping. III. The coated, and dried, wire is heated to ~800 °C for 10 min in a tube furnace under a slow flow of nitrogen gas. The processed wires were then polished and characterized, primarily with scanning electron microscopy (SEM). SEM indicates the chrome layer is uneven, but only on the scale of a fraction of a micron. The evidence of porosity is ambiguous. Elemental mapping using SEM electron microprobe that confirmed the process led to the formation of a chrome metal layer, with no evidence of alloy formation. Additionally, it was found that thickness of the final Cr layer correlated with the thickness of the precursor layer that was applied prior to the heating step. Potentially, this technique could replace electrolytic processing, a process that generates carcinogenic hexavalent chrome, but further study and development is needed.

  11. The chemical stability of TRISO-coated HTGR fuel. Pt. 1. Status report

    International Nuclear Information System (INIS)

    Groot, P.; Cordfunke, E.H.P.; Konings, R.J.M.

    1994-12-01

    The US fuel seemed to be more difficult to produce than the German fuel. Also the chemical stability of this fuel must be investigated. The conditions are more severe in the US concept than in the German concept. Oxidation of the graphite seems to be no problem, according to US HTGR concept. A ZrC coating seems to have a number of advantages with regard to the SiC coating: (1) Better retention, (2) no reaction with Pd, (3) no thermal dissociation. Only the oxidation resistance is worse than SiC. Also the maximum stress must be determined that the ZrC coating can have. (orig./HP)

  12. Dual stimuli responsive self-reporting material for chemical reservoir coating

    Science.gov (United States)

    Lee, Tae Hee; Song, Young Kyu; Park, Sun Hee; Park, Young Il; Noh, Seung Man; Kim, Jin Chul

    2018-03-01

    In this study, we introduce a novel dual stimuli responsive self-reporting thiol-epoxy thermoset (DSRTET) coatings which can detect both crack occurrence and pH variation. For crack detection, microcapsule containing tetraphenylethylene (TPE) which exhibits aggregation induced emission (AIE) effect was prepared via multi-step emulsion polymerization and dispersed in DSRTET coatings. For pH variation detection, commercial thymol blue as a pH indicator was added into the polymer matrix. The effect of microcapsule contents in DSRTET on their curing behavior, material properties, and crack sensitivity was characterized using an oscillatory rheology, rigid body pendulum test (RPT), nano-indentation test (NST), universal test machine (UTM) and scratch tester. It was revealed that crack sensitivity of DSRTET coatings was greatly influenced by material properties as well as microcapsule content. The color transition of DSRTET coatings in response to acid or base solution were quantitatively investigated using a multi-angle spectrophotometer after simple acid and base solution drop tests. The color of DSRTET coatings changed from a pale green to red for acidic solution and to blue for basic solution. Finally, The DSRTET used in this study was applied to laboratory scale chemical reservoirs in order to verify the potential as a dual stimuli response self-reporting coating which can detect both crack in coating material and chemical spill caused by the leakage or breakage of the reservoir part.

  13. SiO{sub 2} coating of silver nanoparticles by photoinduced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Boies, Adam M; Girshick, Steven L [Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455 (United States); Roberts, Jeffrey T [Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455 (United States); Zhang Bin; Nakamura, Toshitaka; Mochizuki, Amane, E-mail: jtrob@umn.ed, E-mail: slg@umn.ed [Nitto Denko Technical Corporation, 501 Via Del Monte, Oceanside, CA 92058 (United States)

    2009-07-22

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO{sub 2}) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO{sub 2} precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO{sub 2} coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 {sup 0}C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10{sup 7} particles cm{sup -3}.

  14. The effect of post-treatment time and temperature on cerium-based conversion coatings on Al 2024-T3

    Energy Technology Data Exchange (ETDEWEB)

    Heller, Daimon K [Missouri University of Science and Technology, 101 Straumanis Hall, 401 West 16th Street, Rolla, MO 65409 (United States)], E-mail: dkhvwb@mst.edu; Fahrenholtz, William G. [Missouri University of Science and Technology, 101 Straumanis Hall, 401 West 16th Street, Rolla, MO 65409 (United States)], E-mail: billf@mst.edu; O' Keefe, Matthew J. [Missouri University of Science and Technology, 101 Straumanis Hall, 401 West 16th Street, Rolla, MO 65409 (United States)

    2010-02-15

    Corrosion performance, morphology, and electrochemical characteristics of cerium-based conversion coatings on Al 2024-T3 were examined as a function of phosphate post-treatment time and temperature. Corrosion resistance improved after post-treatment in 2.5 wt.% NH{sub 4}H{sub 2}PO{sub 4} for times up to 10 min or temperatures up to 85 deg. C. Electrochemical impedance spectroscopy and polarization testing correlated to neutral salt spray corrosion performance. Hydrated cerium oxide and peroxide species present in the as-deposited coatings were transformed to CePO{sub 4}.H{sub 2}O for post-treatments at longer times and/or higher temperatures. Based on these results, processes active during post-treatment are kinetically dependent and strongly influenced by the post-treatment time and temperature.

  15. A PMMA coated PMN–PT single crystal resonator for sensing chemical agents

    International Nuclear Information System (INIS)

    Frank, Michael; Kassegne, Sam; Moon, Kee S

    2010-01-01

    A highly sensitive lead magnesium niobate–lead titanate (PMN–PT) single crystal resonator coated with a thin film of polymethylmethacrylate (PMMA) useful for detecting chemical agents such as acetone, methanol, and isopropyl alcohol is presented. Swelling of the cured PMMA polymer layer in the presence of acetone, methanol, and isopropyl alcohol vapors is sensed as a mass change transduced to an electrical signal by the PMN–PT thickness shear mode sensor. Frequency change in the PMN–PT sensor is demonstrated to vary according to the concentration of the chemical vapor present within the sensing chamber. For acetone, the results indicate a frequency change more than 6000 times greater than that which would be expected from a quartz crystal microbalance coated with PMMA. This study is the first of its kind to demonstrate vapor loading of adsorbed chemical agents onto a polymer coated PMN–PT resonator

  16. Catalytic Conversion of Biomass to Fuels and Chemicals Using Ionic Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wei; Zheng, Richard; Brown, Heather; Li, Joanne; Holladay, John; Cooper, Alan; Rao, Tony

    2012-04-13

    This project provides critical innovations and fundamental understandings that enable development of an economically-viable process for catalytic conversion of biomass (sugar) to 5-hydroxymethylfurfural (HMF). A low-cost ionic liquid (Cyphos 106) is discovered for fast conversion of fructose into HMF under moderate reaction conditions without any catalyst. HMF yield from fructose is almost 100% on the carbon molar basis. Adsorbent materials and adsorption process are invented and demonstrated for separation of 99% pure HMF product and recovery of the ionic liquid from the reaction mixtures. The adsorbent material appears very stable in repeated adsorption/regeneration cycles. Novel membrane-coated adsorbent particles are made and demonstrated to achieve excellent adsorption separation performances at low pressure drops. This is very important for a practical adsorption process because ionic liquids are known of high viscosity. Nearly 100% conversion (or dissolution) of cellulose in the catalytic ionic liquid into small molecules was observed. It is promising to produce HMF, sugars and other fermentable species directly from cellulose feedstock. However, several gaps were identified and could not be resolved in this project. Reaction and separation tests at larger scales are needed to minimize impacts of incidental errors on the mass balance and to show 99.9% ionic liquid recovery. The cellulose reaction tests were troubled with poor reproducibility. Further studies on cellulose conversion in ionic liquids under better controlled conditions are necessary to delineate reaction products, dissolution kinetics, effects of mass and heat transfer in the reactor on conversion, and separation of final reaction mixtures.

  17. Calcium phosphate formation from sea urchin - (brissus latecarinatus via modified mechano-chemical (ultrasonic conversion method

    Directory of Open Access Journals (Sweden)

    R. Samur

    2013-07-01

    Full Text Available This study aims to produce apatite structures, such as hydroxyapatite (HA and fluorapatite (FA, from precursor calcium phosphates of biological origin, namely from sea urchin, with mechano-chemical stirring and hot-plating conversion method. The produced materials were heat treated at 800 °C for 4 hours. X-ray diffraction and scanning electron microscopy (SEM studies were conducted. Calcium phosphate phases were developed. The SEM images showed the formation of micro to nano-powders. The experimental results suggest that sea urchin, Brissus latecarinatus skeleton could be an alternative source for the production of various mono or biphasic calcium phosphates with simple and economic mechano-chemical (ultrasonic conversion method.

  18. Chromium-free conversion coatings based on inorganic salts (Zr/Ti/Mn/Mo) for aluminum alloys used in aircraft applications

    International Nuclear Information System (INIS)

    Santa Coloma, P.; Izagirre, U.; Belaustegi, Y.; Jorcin, J.B.; Cano, F.J.; Lapeña, N.

    2015-01-01

    Highlights: • Chromium-free conversion coatings for corrosion protection of aluminum alloys. • Salt spray and potentiodynamic sweep tests to study the corrosion behavior. • Local deposits on Cu-rich intermetallic particles enhanced corrosion resistance. • Surface characterization to relate bath's composition and corrosion resistance. • Best corrosion protection with conversion baths without titanium salts. - Abstract: Novel chromium-free conversion coatings based on Zr/Ti/Mn/Mo compounds were developed at a pilot scale to improve the corrosion resistance of the AA2024-T3 and AA7075-T6 aluminum alloys for aircraft applications. The influence of the presence of Zr and Ti in the Zr/Ti/Mn/Mo conversion bath's formulation on the corrosion resistance of the coated alloys was investigated. The corrosion resistance provided by the conversion coatings was evaluated by salt spray exposure and potentiodynamic sweeps. Optical and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and atomic force microscopy (AFM) operating in the Kelvin Probe mode (SKPFM) were used to provide microstructural information of the coated samples that achieved the best results in the corrosion tests. The salt spray test evidenced the higher corrosion resistance of the coated samples compared to the bare surfaces for both alloys. The potentiodynamic tests showed that the corrosion current density decreased for coated AA7075-T6 and AA2024-T3 alloys, which indicated an obvious improvement of the corrosion resistance with all the processes for both alloys. Although the corrosion resistance of the coated samples appeared to be higher for the alloy AA7075-T6 than for the alloy AA2024-T3, both alloys achieved the best corrosion protection with the coatings deposited from conversion bath formulations containing no titanium salts. The microscopy analysis on the coated AA7075-T6 samples revealed that a local deposition of Zr compounds and, possibly, an

  19. Chromium-free conversion coatings based on inorganic salts (Zr/Ti/Mn/Mo) for aluminum alloys used in aircraft applications

    Energy Technology Data Exchange (ETDEWEB)

    Santa Coloma, P., E-mail: patricia.santacoloma@tecnalia.com [TECNALIA Research & Innovation, Parque Tecnológico de San Sebastián, Mikeletegi Pasealekua 2, E-20009 Donostia-San Sebastián, Gipuzkoa (Spain); Izagirre, U.; Belaustegi, Y.; Jorcin, J.B.; Cano, F.J. [TECNALIA Research & Innovation, Parque Tecnológico de San Sebastián, Mikeletegi Pasealekua 2, E-20009 Donostia-San Sebastián, Gipuzkoa (Spain); Lapeña, N. [Boeing Research & Technology Europe, S.L.U., Avenida Sur del Aeropuerto de Barajas 38, Building 4 – 3rd Floor, E-28042 Madrid (Spain)

    2015-08-01

    Highlights: • Chromium-free conversion coatings for corrosion protection of aluminum alloys. • Salt spray and potentiodynamic sweep tests to study the corrosion behavior. • Local deposits on Cu-rich intermetallic particles enhanced corrosion resistance. • Surface characterization to relate bath's composition and corrosion resistance. • Best corrosion protection with conversion baths without titanium salts. - Abstract: Novel chromium-free conversion coatings based on Zr/Ti/Mn/Mo compounds were developed at a pilot scale to improve the corrosion resistance of the AA2024-T3 and AA7075-T6 aluminum alloys for aircraft applications. The influence of the presence of Zr and Ti in the Zr/Ti/Mn/Mo conversion bath's formulation on the corrosion resistance of the coated alloys was investigated. The corrosion resistance provided by the conversion coatings was evaluated by salt spray exposure and potentiodynamic sweeps. Optical and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and atomic force microscopy (AFM) operating in the Kelvin Probe mode (SKPFM) were used to provide microstructural information of the coated samples that achieved the best results in the corrosion tests. The salt spray test evidenced the higher corrosion resistance of the coated samples compared to the bare surfaces for both alloys. The potentiodynamic tests showed that the corrosion current density decreased for coated AA7075-T6 and AA2024-T3 alloys, which indicated an obvious improvement of the corrosion resistance with all the processes for both alloys. Although the corrosion resistance of the coated samples appeared to be higher for the alloy AA7075-T6 than for the alloy AA2024-T3, both alloys achieved the best corrosion protection with the coatings deposited from conversion bath formulations containing no titanium salts. The microscopy analysis on the coated AA7075-T6 samples revealed that a local deposition of Zr compounds and, possibly, an

  20. Method for conversion of carbohydrate polymers to value-added chemical products

    Science.gov (United States)

    Zhang, Zongchao C [Norwood, NJ; Brown, Heather M [Kennewick, WA; Su, Yu [Richland, WA

    2012-02-07

    Methods are described for conversion of carbohydrate polymers in ionic liquids, including cellulose, that yield value-added chemicals including, e.g., glucose and 5-hydroxylmethylfurfural (HMF) at temperatures below 120.degree. C. Catalyst compositions that include various mixed metal halides are described that are selective for specified products with yields, e.g., of up to about 56% in a single step process.

  1. Chemical sensors using coated or doped carbon nanotube networks

    Science.gov (United States)

    Li, Jing (Inventor); Meyyappan, Meyya (Inventor)

    2010-01-01

    Methods for using modified single wall carbon nanotubes ("SWCNTs") to detect presence and/or concentration of a gas component, such as a halogen (e.g., Cl.sub.2), hydrogen halides (e.g., HCl), a hydrocarbon (e.g., C.sub.nH.sub.2n+2), an alcohol, an aldehyde or a ketone, to which an unmodified SWCNT is substantially non-reactive. In a first embodiment, a connected network of SWCNTs is coated with a selected polymer, such as chlorosulfonated polyethylene, hydroxypropyl cellulose, polystyrene and/or polyvinylalcohol, and change in an electrical parameter or response value (e.g., conductance, current, voltage difference or resistance) of the coated versus uncoated SWCNT networks is analyzed. In a second embodiment, the network is doped with a transition element, such as Pd, Pt, Rh, Ir, Ru, Os and/or Au, and change in an electrical parameter value is again analyzed. The parameter change value depends monotonically, not necessarily linearly, upon concentration of the gas component. Two general algorithms are presented for estimating concentration value(s), or upper or lower concentration bounds on such values, from measured differences of response values.

  2. Mechanical properties of chemical vapor deposited coatings for fusion reactor application

    International Nuclear Information System (INIS)

    Mullendore, A.W.; Whitley, J.B.; Pierson, H.O.; Mattox, D.M.

    1980-01-01

    Chemical vapor deposited coatings of TiB 2 , TiC and boron on graphite substrates are being developed for application as limiter materials in magnetic confinement fusion reactors. In this application severe thermal shock conditions exist and to do effective thermo-mechanical modelling of the material response it is necessary to acquire elastic moduli, fracture strength and strain to fracture data for the coatings. Four point flexure tests have been conducted from room temperature to 2000 0 C on TiB 2 and boron coated graphite with coatings in tension and compression and the mechanical properties extracted from the load-deflection data. In addition, stress relaxation tests from 500 to 1150 0 C were performed on TiB 2 and TiC coated graphite beams to assess the low levels of plastic deformation which occur in these coatings. Significant differences have been observed between the effective mechanical properties of the coatings and literature values of the bulk properties

  3. Coating of carbon short fibers with thin ceramic layers by chemical vapor deposition

    International Nuclear Information System (INIS)

    Hackl, Gerrit; Gerhard, Helmut; Popovska, Nadejda

    2006-01-01

    Carbon short fiber bundles with a length of 6 mm were uniformly coated using specially designed, continuous chemical vapor deposition (CVD) equipment. Thin layers of titanium nitride, silicon nitride (SiC) and pyrolytic carbon (pyC) were deposited onto several kilograms of short fibers in this large scale CVD reactor. Thermo-gravimetric analyses and scanning electron microscopy investigations revealed layer thicknesses between 20 and 100 nm on the fibers. Raman spectra of pyC coated fibers show a change of structural order depending on the CVD process parameters. For the fibers coated with SiC, Raman investigations showed a deposition of amorphous SiC. The coated carbon short fibers will be applied as reinforcing material in composites with ceramic and metallic matrices

  4. Adsorption and Desorption of Chemical Warfare Agent Simulants on Silica Surfaces with Hydrophobic Coating

    International Nuclear Information System (INIS)

    Park, Eun Ji; Kim, Young Dok

    2013-01-01

    Aim of our study is finding adsorbents suitable for pre-concentration of chemical warfare agents (CWAs). We considered Tenax, bare silica and polydimethylsiloxane (PDMS)-coated silica as adsorbents for dimethyl methylphosphonate (DMMP) and dipropylene glycol methyl ether (DPGME). Tenax showed lower thermal stability, and therefore, desorption of CWA simulants and decomposition of Tenax took place simultaneously. Silica-based adsorbents showed higher thermal stabilities than Tenax. A drawback of silica was that adsorption of CWA simulant (DMMP) was significantly reduced by pre-treatment of the adsorbents with humid air. In the case of PDMS-coated silica, influence of humidity for CWA simulant adsorption was less pronounced due to the hydrophobic nature of PDMS-coating. We propose that PDMS-coated silica can be of potential importance as adsorbent of CWAs for their pre-concentration, which can facilitate detection of these CWAs

  5. Adsorption and Desorption of Chemical Warfare Agent Simulants on Silica Surfaces with Hydrophobic Coating

    Energy Technology Data Exchange (ETDEWEB)

    Park, Eun Ji; Kim, Young Dok [Sungkyunkwan Univ., Suwon (Korea, Republic of)

    2013-07-15

    Aim of our study is finding adsorbents suitable for pre-concentration of chemical warfare agents (CWAs). We considered Tenax, bare silica and polydimethylsiloxane (PDMS)-coated silica as adsorbents for dimethyl methylphosphonate (DMMP) and dipropylene glycol methyl ether (DPGME). Tenax showed lower thermal stability, and therefore, desorption of CWA simulants and decomposition of Tenax took place simultaneously. Silica-based adsorbents showed higher thermal stabilities than Tenax. A drawback of silica was that adsorption of CWA simulant (DMMP) was significantly reduced by pre-treatment of the adsorbents with humid air. In the case of PDMS-coated silica, influence of humidity for CWA simulant adsorption was less pronounced due to the hydrophobic nature of PDMS-coating. We propose that PDMS-coated silica can be of potential importance as adsorbent of CWAs for their pre-concentration, which can facilitate detection of these CWAs.

  6. X-ray texture analysis of paper coating pigments and the correlation with chemical composition analysis

    Science.gov (United States)

    Roine, J.; Tenho, M.; Murtomaa, M.; Lehto, V.-P.; Kansanaho, R.

    2007-10-01

    The present research experiments the applicability of x-ray texture analysis in investigating the properties of paper coatings. The preferred orientations of kaolin, talc, ground calcium carbonate, and precipitated calcium carbonate particles used in four different paper coatings were determined qualitatively based on the measured crystal orientation data. The extent of the orientation, namely, the degree of the texture of each pigment, was characterized quantitatively using a single parameter. As a result, the effect of paper calendering is clearly seen as an increase on the degree of texture of the coating pigments. The effect of calendering on the preferred orientation of kaolin was also evident in an independent energy dispersive spectrometer analysis on micrometer scale and an electron spectroscopy for chemical analysis on nanometer scale. Thus, the present work proves x-ray texture analysis to be a potential research tool for characterizing the properties of paper coating layers.

  7. Separation of Corn Fiber and Conversion to Fuels and Chemicals Phase II: Pilot-scale Operation

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Charles; Beery, Kyle; Orth, Rick; Zacher, Alan

    2007-09-28

    The purpose of the Department of Energy (DOE)-supported corn fiber conversion project, “Separation of Corn Fiber and Conversion to Fuels and Chemicals Phase II: Pilot-scale Operation” is to develop and demonstrate an integrated, economical process for the separation of corn fiber into its principal components to produce higher value-added fuel (ethanol and biodiesel), nutraceuticals (phytosterols), chemicals (polyols), and animal feed (corn fiber molasses). This project has successfully demonstrated the corn fiber conversion process on the pilot scale, and ensured that the process will integrate well into existing ADM corn wet-mills. This process involves hydrolyzing the corn fiber to solubilize 50% of the corn fiber as oligosaccharides and soluble protein. The solubilized fiber is removed and the remaining fiber residue is solvent extracted to remove the corn fiber oil, which contains valuable phytosterols. The extracted oil is refined to separate the phytosterols and the remaining oil is converted to biodiesel. The de-oiled fiber is enzymatically hydrolyzed and remixed with the soluble oligosaccharides in a fermentation vessel where it is fermented by a recombinant yeast, which is capable of fermenting the glucose and xylose to produce ethanol. The fermentation broth is distilled to remove the ethanol. The stillage is centrifuged to separate the yeast cell mass from the soluble components. The yeast cell mass is sold as a high-protein yeast cream and the remaining sugars in the stillage can be purified to produce a feedstock for catalytic conversion of the sugars to polyols (mainly ethylene glycol and propylene glycol) if desirable. The remaining materials from the purification step and any materials remaining after catalytic conversion are concentrated and sold as a corn fiber molasses. Additional high-value products are being investigated for the use of the corn fiber as a dietary fiber sources.

  8. Catalytic Conversion of Carbohydrates to Initial Platform Chemicals: Chemistry and Sustainability.

    Science.gov (United States)

    Mika, László T; Cséfalvay, Edit; Németh, Áron

    2018-01-24

    The replacement of fossil resources that currently provide more than 90% of our energy needs and feedstocks of the chemical industry in combination with reduced emission of carbon dioxide is one of the most pressing challenges of mankind. Biomass as a globally available resource has been proposed as an alternative feedstock for production of basic building blocks, which could partially or even fully replace the currently utilized fossil-based ones in well-established chemical processes. The destruction of lignocellulosic feed followed by oxygen removal from its cellulose and hemicellulose content by catalytic processes results in the formation of initial platform chemicals (IPCs). However, their sustainable production strongly depends on the availability of resources, their efficient or even industrially viable conversion processes, and replenishment time of feedstocks. Herein, we overview recent advances and developments in catalytic transformations of the carbohydrate content of lignocellulosic biomass to IPCs (i.e., ethanol, 3-hydroxypropionic acid, isoprene, succinic and levulinic acids, furfural, and 5-hydroxymethylfurfural). The mechanistic aspects, development of new catalysts, different efficiency indicators (yield and selectivity), and conversion conditions of their production are presented and compared. The potential biochemical production routes utilizing recently engineered microorganisms are reviewed, as well. The sustainability metrics that could be applied to the chemical industry (individual set of sustainability indicators, composite indices methods, material and energy flow analysis-based metrics, and ethanol equivalents) are also overviewed as well as an outlook is provided to highlight challenges and opportunities associated with this huge research area.

  9. Bioelectrochemical Integration of Waste Heat Recovery, Waste-to- Energy Conversion, and Waste-to-Chemical Conversion with Industrial Gas and Chemical Manufacturing Processes

    Energy Technology Data Exchange (ETDEWEB)

    Mac Dougall, James [Air Products and Chemicals, Inc., Allentown, PA (United States)

    2016-02-05

    Many U.S. manufacturing facilities generate unrecovered, low-grade waste heat, and also generate or are located near organic-content waste effluents. Bioelectrochemical systems, such as microbial fuel cells and microbial electrolysis cells, provide a means to convert organic-content effluents into electric power and useful chemical products. A novel biochemical electrical system for industrial manufacturing processes uniquely integrates both waste heat recovery and waste effluent conversion, thereby significantly reducing manufacturing energy requirements. This project will enable the further development of this technology so that it can be applied across a wide variety of US manufacturing segments, including the chemical, food, pharmaceutical, refinery, and pulp and paper industries. It is conservatively estimated that adoption of this technology could provide nearly 40 TBtu/yr of energy, or more than 1% of the U.S. total industrial electricity use, while reducing CO2 emissions by more than 6 million tons per year. Commercialization of this technology will make a significant contribution to DOE’s Industrial Technology Program goals for doubling energy efficiency and providing a more robust and competitive domestic manufacturing base.

  10. Elaboration of colloidal silica sols in aqueous medium: functionalities, optical properties and chemical detection of coating

    International Nuclear Information System (INIS)

    Le Guevel, X.

    2006-03-01

    The aim of this work was to study surface reactivity of silica nanoparticles through physical and chemical properties of sols and coatings. Applications are numerous and they are illustrated in this work by optical coating preparation for laser components and chemical gas sensor development for nitroaromatics detection. On one hand, protocol synthesis of colloidal silica sols has been developed in water medium using sol-gel process (0 to 100 w%). These sols, so-called BLUESIL, are time-stable during at least one year. Homogeneous coatings having thickness fixed to 200 nm, have been prepared on silica substrate and show high porosity and high transparence. Original films have been developed using catalytic curing in gas atmosphere (ammonia curing) conferring good abrasive resistance to the coating without significant properties modification. In order to reduce film sensitivity to molecular adsorption (water, polluting agents... ), specific BLUESIL coatings have been prepared showing hydrophobic property due to apolar species grafting onto silica nanoparticles. Using this route, coatings having several functional properties such as transparence, hydrophobicity, high porosity and good abrasive resistance have been elaborated. On the other hand, we show that colloidal silica is a material specifically adapted to the detection of nitro aromatic vapors (NAC). Indeed, the use of colloidal silica as chemical gas sensor reveals very high sensitivity, selectivity to NAC compared to Volatile Organic Compound (V.O.C) and good detection performances during one year. Moreover, chemical sensors using functionalized colloidal silica have exhibited good results of detection, even in high humidity medium (≥70 %RH). (author)

  11. Prospects of chemically deposited CoS-CU2S coatings for solar ...

    African Journals Online (AJOL)

    The thin films of Cu2S deposited on CoS-precoated glass substrates from chemical baths and annealed at 100oC were found to have desirable solar control characteristics superior to commercial tinted glass and magnetron sputtered multilayer metallic solar control coatings. These include: transmission spectra in the ...

  12. A Two-Level Undercut-Profile Substrate for Chemical-Solution-Based Filamentary Coated Conductors

    DEFF Research Database (Denmark)

    Wulff, Anders Christian; Lundeman, Jesper H.; Hansen, Jørn B.

    2016-01-01

    . In the present study, the 2LUPS concept is applied to a commercial cube-textured Ni-5at.% W tape, and the surface of the 2LUPS coated with two Gd2Zr2O7 buffer layers using chemical solution deposition is examined. Except for narrow regions near the edge of upper plateaus, the plateaus are found to be covered...

  13. Chemical vapor deposition of aluminide coatings on iron, nickel and superalloys

    International Nuclear Information System (INIS)

    John, John T.; De, P.K.; Dubey, Vivekanand; Srinivasa, Raman

    2009-08-01

    Aluminide coatings are a class of intermetallic coatings applied on nickel and cobalt base superalloys and steels to protect them from different forms of environmental degradation at high temperatures. In this report a CVD system that can produce the aluminide coatings on iron, nickel and nickel base alloys has been described and the result of chemical vapor deposition of aluminide coatings on iron specimens, their characterization, and property evaluation have been presented. The CVD system consists of an AlCl 3 bath, a stainless steel retort as a hot-wall reacto, cold traps and vacuum system. Aluminium chloride vapor was carried in a stream of hydrogen gas at a flow rate of 150 SCCM (standard cubic centimeter per minute) into the CVD reactor maintained in the temperature range of 1173 - 1373 K and at a pressure of 1.33 kPa (10 Torr). Aluminum deposition takes place from aluminium subchlorides produced by reaction between AlCl 3 and pure aluminum kept in the CVD reactor. The aluminum diffuses into the iron samples and iron aluminide phases are formed at the surface. The coatings were shining bright and showed good adherence to the substrate. The coatings consisted of FeAl phase over a wide range of experimental conditions. The growth kinetics of the coating followed a parabolic rate law and the mean activation energy was 212 ±16 kJ/mol. Optical microscopic studies on the transverse section of the coating showed that the aluminide coating on iron consisted of two layers. The top layer had a thickness in the range of 20-50 μm, and the under layer had thickness ranging from 35 to 250 μm depending on coating temperature in two hours. The thickness of the aluminide layer increased with coating duration and temperature. Electron microprobe studies (EPMA) showed that the aluminum concentration decreased steadily as distance from the surface increased. TEM studies showed that the outer most layer had a B2 order (of the FeAl phase), which extended even into the under

  14. Direct conversion of radioactive and chemical waste containing metals, ceramics, amorphous solids, and organics to glass

    International Nuclear Information System (INIS)

    Forsberg, C.W.; Beahm, E.C.; Parker, G.W.

    1994-01-01

    The Glass Material Oxidation and Dissolution System (CMODS) is a new process for direct conversion of radioactive, mixed, and chemical wastes to glass. The wastes can be in the chemical forms of metals, ceramics, amorphous solids, and organics. GMODS destroys organics and it incorporates heavy metals and radionuclides into a glass. Processable wastes may include miscellaneous spent fuels (SF), SF hulls and hardware, plutonium wastes in different forms, high-efficiency particulate air (HEPA) filters, ion-exchange resins, failed equipment, and laboratory wastes. Thermodynamic calculations indicate theoretical feasibility. Small-scale laboratory experiments (< 100 g per test) have demonstrated chemical laboratory feasibility for several metals. Additional work is needed to demonstrate engineering feasibility

  15. Studies on conversion of crude sodium diuranate to high purity uranium oxide by chemical route

    International Nuclear Information System (INIS)

    Rajan, K.C.; Ramadevi, G.; Giri, Nitai; Chakravartty, J.K.; Sreenivas, T.

    2016-01-01

    Uranium values are recovered from ores and mine rejects by employing chemical processing methods. The process chemistry could be either acidic (H 2 SO 4 medium) or alkaline (Na 2 CO 3 - NaHCO 3 medium) based depending on the nature of host rock. The end product is termed as 'yellow cake' which is sent to refining plants for final purification and fuel manufacture. Conventionally the yellow cake product is magnesium (MDU) or ammonium diuranate (ADU) in U-plants following the acidic processing route while it is sodium diuranate (SDU) in the alkaline route. The preference for SDU in plants operating with alkaline route is mainly driven by the requirement of conserving and reusing the expensive chemicals. Though alkaline processing gives relatively purer diuranate product, the practice of direct precipitation of dissolved uranium from pregnant leach liquors invariably leads to presence of impurities detrimental for downstream unit operations, mostly in solvent extraction based refining stages. In this score uranium peroxide is superior to other uranates in many respects. Two alternatives are practiced for the conversion of SDU to uranium peroxide - chemical and fluid bed precipitation. Though generic flowsheet for the conversion stage is well documented, the process conditions and complexities vary with the chemistry of the pregnant leach liquor which is specific for a given ore or a deposit. This paper discusses the process scheme tailored, optimized and tested on a kilo-gram scale for chemical conversion of SDU produced by alkaline processing of a low-grade carbonate hosted uranium ore. The entire process scheme is first of its kind in Indian uranium ore processing arena

  16. Effect of chemically reduced palladium supported catalyst on sunflower oil hydrogenation conversion and selectivity

    Directory of Open Access Journals (Sweden)

    Abdulmajid Alshaibani

    2017-02-01

    Full Text Available Catalytic hydrogenation of sunflower oil was studied in order to improve the conversion and to reduce the trans-isomerization selectivity. The hydrogenation was performed using Pd–B/γ-Al2O3 prepared catalyst and Pd/Al2O3 commercial catalyst under similar conditions. The Pd–B/γ-Al2O3 catalyst was prepared by wet impregnation and chemical reduction processes. It was characterized by Brunauer–Emmett–Teller surface area analysis (BET, X-ray powder diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. The result of sunflower oil hydrogenation on Pd–B/γ-Al2O3 catalyst showed a 17% higher conversion and a 23% lower trans-isomerization selectivity compared to the commercial Pd/Al2O3 catalyst. The chemical reduction of palladium supported catalyst using potassium borohydride (KBH4 has affected the Pd–B/γ-Al2O3 catalyst’s structure and particle size. These most likely influenced its catalytic performance toward higher conversion and lower trans-isomerization selectivity.

  17. Integrated Electrochemical Processes for CO2 Capture and Conversion to Commodity Chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Hatton, T. Alan [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Jamison, Timothy [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2013-09-30

    The Massachusetts Institute of Technology (MIT) and Siemens Corporations (SCR) are developing new chemical synthesis processes for commodity chemicals from CO2. The process is assessed as a novel chemical sequestration technology that utilizes CO2 from dilute gas streams generated at industrial carbon emitters as a raw material to produce useful commodity chemicals. Work at Massachusetts Institute of Technology (MIT) commenced on October 1st, 2010, and finished on September 30th, 2013. During this period, we have investigated and accomplished five objectives that mainly focused on converting CO2 into high-value chemicals: 1) Electrochemical assessment of catalytic transformation of CO2 and epoxides to cyclic carbonates; 2) Investigation of organocatalytic routes to convert CO2 and epoxide to cyclic carbonates; 3) Investigation of CO2 Capture and conversion using simple olefins under continuous flow; 4) Microwave assisted synthesis of cyclic carbonates from olefins using sodium bicarbonates in a green pathway; 5) Life cycle analyses of integrated chemical sequestration process. In this final report, we will describe the detailed study performed during the three year period and findings and conclusions drawn from our research.

  18. Carbon dioxide management by chemical conversion to methanol: HYDROGENATION and BI-REFORMING

    International Nuclear Information System (INIS)

    Wiesberg, Igor L.; Medeiros, José Luiz de; Alves, Rita M.B.; Coutinho, Paulo L.A.; Araújo, Ofélia Q.F.

    2016-01-01

    Highlights: • Evaluation of carbon dioxide conversion to methanol by two chemical routes. • HYDROGENATION: conversion via catalytic hydrogenation at high pressure. • BI-REFORMING: conversion via syngas from bi-reforming of natural gas. • HYDROGENATION is viable for hydrogen price inferior to 1000 US$/t. • BI-REFORMING is unable to avoid emissions; viable only if gas price is very low. - Abstract: Chemical conversion of carbon dioxide to methanol has the potential to address two relevant sustainability issues: economically feasible replacement of fossil raw materials and avoidance of greenhouse gas emissions. However, chemical stability of carbon dioxide is a challenging impediment to conversion requiring severe reaction conditions at the expense of increased energy input, therefore adding capital, operation and environmental costs, which could result in partial or total override of its potential sustainability as feedstock to the chemical and energy industries. This work investigates two innovative chemical destinations of carbon dioxide to methanol, namely a direct conversion through carbon dioxide hydrogenation (HYDROGENATION), and an indirect via carbon dioxide conversion to syngas through bi-reforming (BI-REFORMING). Process simulation is used to obtain mass and energy balances needed to support assessment of economic and environmental performance. A business scenario is considered where an industrial source of nearly pure carbon dioxide exists and an investment decision for utilization of carbon dioxide is faced. Due to uncertainties in prices of the raw materials, hydrogen (HYDROGENATION) and natural gas (BI-REFORMING), the decision procedure includes the definition of price thresholds to reach profitability. Sensitivity analyses are performed varying costs with greater uncertainty, i.e., carbon dioxide and methanol, and recalculating maximum allowable prices of raw materials. The analyses show that in a Brazilian scenario, BI-REFORMING is unlikely

  19. Thermal barrier coatings on gas turbine blades: Chemical vapor deposition (Review)

    Science.gov (United States)

    Igumenov, I. K.; Aksenov, A. N.

    2017-12-01

    Schemes are presented for experimental setups (reactors) developed at leading scientific centers connected with the development of technologies for the deposition of coatings using the CVD method: at the Technical University of Braunschweig (Germany), the French Aerospace Research Center, the Materials Research Institute (Tohoku University, Japan) and the National Laboratory Oak Ridge (USA). Conditions and modes for obtaining the coatings with high operational parameters are considered. It is established that the formed thermal barrier coatings do not fundamentally differ in their properties (columnar microstructure, thermocyclic resistance, thermal conductivity coefficient) from standard electron-beam condensates, but the highest growth rates and the perfection of the crystal structure are achieved in the case of plasma-chemical processes and in reactors with additional laser or induction heating of a workpiece. It is shown that CVD reactors can serve as a basis for the development of rational and more advanced technologies for coating gas turbine blades that are not inferior to standard electron-beam plants in terms of the quality of produced coatings and have a much simpler and cheaper structure. The possibility of developing a new technology based on CVD processes for the formation of thermal barrier coatings with high operational parameters is discussed, including a set of requirements for industrial reactors, high-performance sources of vapor precursors, and promising new materials.

  20. Appearance of a conductive carbonaceous coating in a CO2 dielectric barrier discharge and its influence on the electrical properties and the conversion efficiency

    International Nuclear Information System (INIS)

    Belov, Igor; Paulussen, Sabine; Bogaerts, Annemie

    2016-01-01

    This work examines the properties of a dielectric barrier discharge (DBD) reactor, built for CO 2 decomposition, by means of electrical characterization, optical emission spectroscopy and gas chromatography. The discharge, formed in an electronegative gas (such as CO 2 , but also O 2 ), exhibits clearly different electrical characteristics, depending on the surface conductivity of the reactor walls. An asymmetric current waveform is observed in the metal-dielectric (MD) configuration, with sparse high-current pulses in the positive half-cycle (HC) and a more uniform regime in the negative HC. This indicates that the discharge is operating in two alternating regimes with rather different properties. At high CO 2 conversion regimes, a conductive coating is deposited on the dielectric. This so-called coated MD configuration yields a symmetric current waveform, with current peaks in both the positive and negative HCs. In a double-dielectric (DD) configuration, the current waveform is also symmetric, but without current peaks in both the positive and negative HC. Finally, the DD configuration with conductive coating on the inner surface of the outer dielectric, i.e. so-called coated DD, yields again an asymmetric current waveform, with current peaks in the negative HC. These different electrical characteristics are related to the presence of the conductive coating on the dielectric wall of the reactor and can be explained by an increase of the local barrier capacitance available for charge transfer. The different discharge regimes affect the CO 2 conversion, more specifically, the CO 2 conversion is lowest in the clean DD configuration. It is somewhat higher in the coated DD configuration, and still higher in the MD configuration. The clean and coated MD configuration, however, gave similar CO 2 conversion. These results indicate that the conductivity of the dielectric reactor walls can highly promote the development of the high-amplitude discharge current pulses and

  1. Chemical coal conversion yesterday, today, and tomorrow; Der Chemierohstoff Kohle: gestern, heute und morgen

    Energy Technology Data Exchange (ETDEWEB)

    Talbiersky, J. [UCP Chemicals AG, Wien (Austria)

    2007-01-15

    Shortage in mineral oil and gas as well as a high price level have caused a renaissance in coal conversion technologies, at the end of the 70's. Today we have a similar situation. Now coal coversion technologies will be in the focus again but hopefully as a longterm strategy. The most important coal conversion technologies as liquefaction, gasification, coking and calcium carbide synthesis are discussed regarding their use for the production of chemicals. The most important source for aromatic chemicals from coal is till now coal tar with an availability of 22 Mio. t/a. The manufacturing of coal tar is discussed as an example for making aromatic products from a complex feed stock that you get by the fixed bed gasification, coal liquefaction and coking. Also the special marketing strategy that is necessary to be competitive against products from the petroindustry. It can be expected, that coal gasification as a source for synthesis gas will become more and more important. Synthesis gas is the access to aliphatic hydrocarbons by Fischer Tropsch synthesis and to methanol, a chemical with a high synthetic potential. Also the new hydrothermal carbonization of biomass to synthetic coal is mentioned. (orig.)

  2. Hygroscopicity of mineral dust particles: Roles of chemical mixing state and hygroscopic conversion timescale

    Science.gov (United States)

    Sullivan, R. C.; Moore, M. J.; Petters, M. D.; Laskin, A.; Roberts, G. C.; Kreidenweis, S. M.; Prather, K. A.

    2009-05-01

    Our laboratory investigations of mineral dust particle hygroscopicity are motivated by field observations of the atmospheric processing of dust. During ACE-Asia we observed sulphate and nitrate to be strongly segregated from each other in individual aged Asian dust particles. CCN activation curves of pure calcium minerals as proxies for fresh (calcium carbonate) and aged (calcium sulphate, nitrate, chloride) dust indicate that this mixing state would cause a large fraction of aged dust particles to remain poor warm cloud nucleation potential, contrary to previous assumptions. The enrichment of oxalic acid in calcium-rich dust particles could have similar effects due to the formation of insoluble calcium oxalate. Soluble calcium nitrate and chloride reaction products are hygroscopic and will transform mineral dust into excellent CCN. Generating insoluble mineral particles wet by atomization produced particles with much higher hygroscopicity then when resuspended dry. The atomized particles are likely composed of dissolved residuals and do not properly reflect the chemistry of dry mineral powders. Aerosol flow tube experiments were employed to study the conversion of calcium carbonate into calcium nitrate via heterogeneous reaction with nitric acid, with simultaneous measurements of the reacted particles' chemistry and hygroscopicity. The timescale for this hygroscopic conversion was found to occur on the order of a few hours under tropospheric conditions. This implies that the conversion of non-hygroscopic calcite- containing dust into hygroscopic particles will be controlled by the availability of nitric acid, and not by the atmospheric residence time. Results from recent investigations of the effect of secondary coatings on the ice nucleation properties of dust particles will also be presented. The cloud formation potential of aged dust particles depends on both the quantity and form of the secondary species that have reacted or mixed with the dust. These results

  3. Modelling of solar cells with down-conversion of high energy photons, anti-reflection coatings and light trapping

    International Nuclear Information System (INIS)

    Vos, Alexis de; Szymanska, Aleksandra; Badescu, Viorel

    2009-01-01

    In classical solar cells, each absorbed photon gives rise to one electron-hole pair, irrespective of the photon energy. By applying an appropriate photoluminescent layer in front of the solar cell semiconductor, one can convert one high energy photon into two low energy photons (so-called down-conversion). In the present study, we do not consider photoluminescent layers that merely shift down photon energies (without enhancing the number of photons). In principle, these two photons can then generate two electron-hole pairs in the solar cell, thus increasing the efficiency of the device. However, the two photons emitted by the converter, are not necessarily emitted in the direction of the semiconductor: they can also be emitted in the direction 'back to the sun'. As most semiconductors have a high refractive index, in case the luminescent material has a low refractive index, more than half of the photoluminescence emission is lost in the sun direction, resulting in a net loss of light current generated by the solar cell instead of an increase. On the other hand, a high refractive index of the conversion layer (e.g. equal to the solar cell refractive index) will lead to a bad optical coupling with the air and a good optical coupling with the semiconductor, and therefore, more than 50% of the emitted low energy photons will actually reach the solar cell. However, in the latter case, many solar photons do not reach the converter in the first place because of reflection at the air-converter interface. As a result, it turns out that, in the absence of any anti-reflection coating, a refractive index n 2 of the converting layer in the range between n 1 1/2 and n 1 is optimal, where n 1 is the refractive index of the solar cell material. If, however, an anti-reflection coating is applied between air and the converter, the best choice for n 2 is n 1 . Finally, if two anti-reflection coatings are applied (the former between air and the converter, the latter between the

  4. Surface Modification of α-Fe Metal Particles by Chemical Surface Coating

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The structure of α-Fe metal magnetic recording particles coated with silane coupling agents have been studied by TEM, FT-IR, EXAFS, Mossbauer. The results show that a close, uniform, firm and ultra thin layer, which is beneficial to the magnetic and chemical stability, has been formed by the cross-linked chemical bond Si-O-Si. And the organic molecule has chemically bonded to the particle surface, which has greatly affected the surface Fe atom electronic structure. Furthermore, the covalent bond between metal particle surface and organic molecule has obvious effect on the near edge structure of the surface Fe atoms.

  5. Chemical changes in DMP1-null murine bone & silica based pecvd coatings for titanium implant osseoapplications

    Science.gov (United States)

    Maginot, Megen

    In order to improve clinical outcomes in bone-implant systems, a thorough understanding of both local bone chemistry and implant surface chemistry is necessary. This study consists, therefore, of two main parts: one focused on determining the nature of the changes in bone chemistry in a DMP1-null transgenic disease model and the other on the development of amorphous silica-based coatings for potential use as titanium bone implant coatings. For the study of bone mineral in the DMP1 transgenic model, which is known to have low serum phosphate levels, transgenic DMP1-null and wild type mice were fed a high phosphate diet, sacrificed, and had their long bone harvested. This bone was characterized using SEM, FTIR, microCT and XANES and compared to DMP1-null and wild type control groups to assess the therapeutic effect of high Pi levels on the phenotype and the role of DMP1 in mineralization in vivo. Findings suggest that though the high phosphate diet results in restoring serum phosphate levels, it does not completely rescue the bone mineral phenotype at an ultrastructural level and implicates DMP1 in phosphate nucleation. Since plasma enhanced chemical vapor deposition (PECVD) silica like coatings have not previously been fabricated for use in oessoapplications, the second part of this study initially focused on the characterization of novel SiOx chemistries fabricated via a chemical vapor deposition process that were designed specifically to act as bioactive coatings with a loose, hydrogenated structure. These coatings were then investigated for their potential initial stage response to bone tissue through immersion in a simulated body fluid and through the culture of MC3T3 cells on the coating surfaces. Coating surfaces were characterized by SEM, FTIR, contact angle measurements, and XANES. Coating dissolution and ionic release were also investigated by ICP-OES. Findings suggest that some SiOx chemistries may form a bioactive coating while more highly substituted

  6. Chemical stability of fluorine-containing coatings of cold drying for radiation - protection technique articles

    International Nuclear Information System (INIS)

    Shigorina, I.I.; Zvyagintseva, N.V.; Egorov, B.N.

    1977-01-01

    The chemical stability of fluorolon coatings, which are not subjected to heat treatment or hot drying during application, has been studied. The test for layer life-time has been performed by submerging specimens in agressive medium. The time for one upper removable layer to fail under steady action of agressive liquid is found to be: > 12 months at 20 deg C, 6-9 months at 40 deg C; at 60 deg C the time of layer stability depends upon medium: 1 month for nitric, 2 months for acetic, 2-3 months for sulphuric and hydrochloric acid. The coatings are recommended for practical application in radiation-protective technique

  7. WC-Co coatings deposited by the electro-thermal chemical spray method

    Energy Technology Data Exchange (ETDEWEB)

    Zhitomirsky, V.N. [Tel Aviv Univ. (Israel). Faculty of Engineering; Wald, S.; Rabani, L.; Zoler, D. [Propulsion Physics Division, SOREQ NRC, 81800, Yavne (Israel); Factor, M.; Roman, I. [School of Applied Sciences, The Hebrew University, 91904, Jerusalem (Israel); Cuperman, S.; Bruma, C. [School of Physics and Astronomy, Tel-Aviv University, 69978, Tel-Aviv (Israel)

    2000-10-02

    A novel thermal spray technology - an electro-thermal chemical spray (ETCS) for producing hard coatings is presented. The experimental coating apparatus consists of a machine gun barrel, a cartridge containing the coating material in powder form, a solid propellant, and a plasma ignition system. The plasma ignition system produces plasma in pulsed mode to ignite the solid propellant. On ignition, the drag force exerted by the combustion gases accelerates the powder particles towards the substrate. Using the ETCS technique, the process of single-shot WC-Co coating deposition on stainless steel substrate was studied. The influence of process parameters (plasma energy, mass of the solid propellant and the coated powder, distance between the gun muzzle and the substrate) on the coating structure and some of its properties were investigated. It was shown that ECTS technique effectively deposited the WC-Co coating with deposition thicknesses of 100-200 {mu}m per shot, while deposition yield of {proportional_to}70% was attained. The WC-Co coatings consisted of carbide particles distributed in amorphous matrix. The powder particle velocity was found to depend on the solid propellant mass and was weakly dependent on the plasma energy, while the particle processing temperature was strongly dependent on the plasma energy and almost independent of the solid propellant mass. Whilst increasing the solid propellant mass from 5 to 7 g, the deposition rate and yield correspondingly increased. When increasing the plasma energy, the temperature of the powder particles increased, the average carbide particle size decreased and their shape became more rounded. The deposition yield and microhardness at first increased and then achieved saturation by increasing the plasma energy. (orig.)

  8. Development of Diffusion barrier coatings and Deposition Technologies for Mitigating Fuel Cladding Chemical Interactions (FCCI)

    Energy Technology Data Exchange (ETDEWEB)

    Sridharan, Kumar; Allen, Todd; Cole, James

    2013-02-27

    The goal of this project is to develop diffusion barrier coatings on the inner cladding surface to mitigate fuel-cladding chemical interaction (FCCI). FCCI occurs due to thermal and radiation enhanced inter-diffusion between the cladding and fuel materials, and can have the detrimental effects of reducing the effective cladding wall thickness and lowering the melting points of the fuel and cladding. The research is aimed at the Advanced Burner Reactor (ABR), a sodium-cooled fast reactor, in which higher burn-ups will exacerbate the FCCI problem. This project will study both diffusion barrier coating materials and deposition technologies. Researchers will investigate pure vanadium, zirconium, and titanium metals, along with their respective oxides, on substrates of HT-9, T91, and oxide dispersion-strengthened (ODS) steels; these materials are leading candidates for ABR fuel cladding. To test the efficacy of the coating materials, the research team will perform high-temperature diffusion couple studies using both a prototypic metallic uranium fuel and a surrogate the rare-earth element lanthanum. Ion irradiation experiments will test the stability of the coating and the coating-cladding interface. A critical technological challenge is the ability to deposit uniform coatings on the inner surface of cladding. The team will develop a promising non-line-of-sight approach that uses nanofluids . Recent research has shown the feasibility of this simple yet novel approach to deposit coatings on test flats and inside small sections of claddings. Two approaches will be investigated: 1) modified electrophoretic deposition (MEPD) and 2) boiling nanofluids. The coatings will be evaluated in the as-deposited condition and after sintering.

  9. Comparative study on Ti/Zr/V and chromate conversion treated aluminum alloys: Anti-corrosion performance and epoxy coating adhesion properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wen; Li, Wenfang, E-mail: mewfli@163.com; Mu, Songlin; Fu, Nianqing; Liao, Zhongmiao

    2017-05-31

    Highlights: • The surface roughness and surface free energy of the AA6063 are significantly increased after TZVCC treatment. • The anti-corrosion performance of the AA6063 is effectively enhanced after TZVCC treatment. • Both the corrosion resistance and wet adhesion properties of the epoxy coating on the AA6063 are noticeably improved after TZVCC treatment. - Abstract: In this study, a Ti/Zr/V conversion coating (TZVCC) was deposited on the surface of aluminum alloy 6063 (AA6063) as an alternative of the chromate conversion coating (CCC). Both the TZVCC treated AA6063 (TZVCC/AA6063) and CCC treated AA6063 (CCC/AA6063) were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and contact angle measuring device. The anti-corrosion performance of the TZVCC/AA6063 and CCC/AA6063 was evaluated by electrochemical measurements and neutral salt spray tests. It showed that both the surface roughness and surface free energy of the AA6063 were significantly increased after TZVCC treatment. The anti-corrosion performance of TZVCC/AA6063 was superior to that of CCC/AA6063. In addition, the effects of the TZVCC and CCC on the adhesion properties and anti-corrosion performance of epoxy coating applied on samples were examined by pull-off tests and electrochemical impedance spectroscopy (EIS). The dry, wet and recovery adhesive strengths of the epoxy coating on TZVCC treated samples (epoxy coated TZVCC/AA6063) were very close to those of epoxy coating on CCC treated ones (epoxy coated CCC/AA6063). The epoxy coated TZVCC/AA6063 showed better corrosion resistance than the epoxy coated CCC/AA6063 and epoxy coated AA6063.

  10. Model analysis of the chemical conversion of exhaust species in the expanding plumes of subsonic aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Moellhoff, M.; Hendricks, J.; Lippert, E.; Petry, H. [Koeln Univ. (Germany). Inst. fuer Geophysik und Meteorologie; Sausen, R. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

    1997-12-31

    A box model and two different one-dimensional models are used to investigate the chemical conversion of exhaust species in the dispersing plume of a subsonic aircraft flying at cruise altitude. The effect of varying daytime of release as well as the impact of changing dispersion time is studied with special respect to the aircraft induced O{sub 3} production. Effective emission amounts for consideration in mesoscale and global models are calculated. Simulations with modified photolysis rates are performed to show the sensitivity of the photochemistry to the occurrence of cirrus clouds. (author) 8 refs.

  11. Model analysis of the chemical conversion of exhaust species in the expanding plumes of subsonic aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Moellhoff, M; Hendricks, J; Lippert, E; Petry, H [Koeln Univ. (Germany). Inst. fuer Geophysik und Meteorologie; Sausen, R [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

    1998-12-31

    A box model and two different one-dimensional models are used to investigate the chemical conversion of exhaust species in the dispersing plume of a subsonic aircraft flying at cruise altitude. The effect of varying daytime of release as well as the impact of changing dispersion time is studied with special respect to the aircraft induced O{sub 3} production. Effective emission amounts for consideration in mesoscale and global models are calculated. Simulations with modified photolysis rates are performed to show the sensitivity of the photochemistry to the occurrence of cirrus clouds. (author) 8 refs.

  12. Conformal coating of amorphous silicon and germanium by high pressure chemical vapor deposition for photovoltaic fabrics

    Science.gov (United States)

    Ji, Xiaoyu; Cheng, Hiu Yan; Grede, Alex J.; Molina, Alex; Talreja, Disha; Mohney, Suzanne E.; Giebink, Noel C.; Badding, John V.; Gopalan, Venkatraman

    2018-04-01

    Conformally coating textured, high surface area substrates with high quality semiconductors is challenging. Here, we show that a high pressure chemical vapor deposition process can be employed to conformally coat the individual fibers of several types of flexible fabrics (cotton, carbon, steel) with electronically or optoelectronically active materials. The high pressure (˜30 MPa) significantly increases the deposition rate at low temperatures. As a result, it becomes possible to deposit technologically important hydrogenated amorphous silicon (a-Si:H) from silane by a simple and very practical pyrolysis process without the use of plasma, photochemical, hot-wire, or other forms of activation. By confining gas phase reactions in microscale reactors, we show that the formation of undesired particles is inhibited within the microscale spaces between the individual wires in the fabric structures. Such a conformal coating approach enables the direct fabrication of hydrogenated amorphous silicon-based Schottky junction devices on a stainless steel fabric functioning as a solar fabric.

  13. Polyaniline-coated halloysite nanotubes via in-situ chemical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Long [State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Wang Tingmei [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Liu Peng [State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)], E-mail: pliu@lzu.edu.cn

    2008-12-30

    Polyaniline coated halloysite nanotubes (PANI/HNTs) were prepared by the in-situ soapless emulsion polymerization of the anilinium chloride adsorbed halloysite nanotubes (HNTs), obtained by the dispersion of HNTs in acidic aqueous solution of aniline with magnetic stirring and ultrasonic irradiation, by using ammonium persulfate (APS) as oxidant. The effect of the acidities of the polymerizing media on the crystal structure of the nanotubes was investigated with X-ray diffraction (XRD) technique. The surface conducting coatings of the hybrids were characterized with X-ray photoelectron spectroscopy (XPS). The morphological analyses showed that the polyaniline coated halloysite nanotubes via the in-situ chemical oxidation polymerization with ultrasonic irradiation had the better well-defined structures, by the transmission electron microscopy (TEM). The conductivities of the PANI/HNTs hybrids increased with the increasing of the amounts of HCl dopant added in the emulsion polymerization.

  14. Superconducting magnesium diboride coatings for radio frequency cavities fabricated by hybrid physical-chemical vapor deposition

    Science.gov (United States)

    Wolak, M. A.; Tan, T.; Krick, A.; Johnson, E.; Hambe, M.; Chen, Ke; Xi, X. X.

    2014-01-01

    We have investigated the coating of an inner surface of superconducting radio frequency cavities with a magnesium diboride thin film by hybrid physical-chemical vapor deposition (HPCVD). To simulate a 6 GHz rf cavity, a straight stainless steel tube of 1.5-inch inner diameter and a dummy stainless steel cavity were employed, on which small sapphire and metal substrates were mounted at different locations. The MgB2 films on these substrates showed uniformly good superconducting properties including Tc of 37-40 K, residual resistivity ratio of up to 14, and root-mean-square roughness Rq of 20-30 nm. This work demonstrates the feasibility of coating the interior of cylindrical and curved objects with MgB2 by the HPCVD technique, an important step towards superconducting rf cavities with MgB2 coating.

  15. Polyaniline-coated halloysite nanotubes via in-situ chemical polymerization

    International Nuclear Information System (INIS)

    Zhang Long; Wang Tingmei; Liu Peng

    2008-01-01

    Polyaniline coated halloysite nanotubes (PANI/HNTs) were prepared by the in-situ soapless emulsion polymerization of the anilinium chloride adsorbed halloysite nanotubes (HNTs), obtained by the dispersion of HNTs in acidic aqueous solution of aniline with magnetic stirring and ultrasonic irradiation, by using ammonium persulfate (APS) as oxidant. The effect of the acidities of the polymerizing media on the crystal structure of the nanotubes was investigated with X-ray diffraction (XRD) technique. The surface conducting coatings of the hybrids were characterized with X-ray photoelectron spectroscopy (XPS). The morphological analyses showed that the polyaniline coated halloysite nanotubes via the in-situ chemical oxidation polymerization with ultrasonic irradiation had the better well-defined structures, by the transmission electron microscopy (TEM). The conductivities of the PANI/HNTs hybrids increased with the increasing of the amounts of HCl dopant added in the emulsion polymerization.

  16. Superconducting magnesium diboride coatings for radio frequency cavities fabricated by hybrid physical-chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    M. A. Wolak

    2014-01-01

    Full Text Available We have investigated the coating of an inner surface of superconducting radio frequency cavities with a magnesium diboride thin film by hybrid physical-chemical vapor deposition (HPCVD. To simulate a 6 GHz rf cavity, a straight stainless steel tube of 1.5-inch inner diameter and a dummy stainless steel cavity were employed, on which small sapphire and metal substrates were mounted at different locations. The MgB_{2} films on these substrates showed uniformly good superconducting properties including T_{c} of 37–40 K, residual resistivity ratio of up to 14, and root-mean-square roughness R_{q} of 20–30 nm. This work demonstrates the feasibility of coating the interior of cylindrical and curved objects with MgB_{2} by the HPCVD technique, an important step towards superconducting rf cavities with MgB_{2} coating.

  17. Plasma Assisted Chemical Vapour Deposition – Technological Design Of Functional Coatings

    Directory of Open Access Journals (Sweden)

    Januś M.

    2015-06-01

    Full Text Available Plasma Assisted Chemical Vapour Deposition (PA CVD method allows to deposit of homogeneous, well-adhesive coatings at lower temperature on different substrates. Plasmochemical treatment significantly impacts on physicochemical parameters of modified surfaces. In this study we present the overview of the possibilities of plasma processes for the deposition of diamond-like carbon coatings doped Si and/or N atoms on the Ti Grade2, aluminum-zinc alloy and polyetherketone substrate. Depending on the type of modified substrate had improved the corrosion properties including biocompatibility of titanium surface, increase of surface hardness with deposition of good adhesion and fine-grained coatings (in the case of Al-Zn alloy and improving of the wear resistance (in the case of PEEK substrate.

  18. Transition Metal Coatings for Energy Conversion and Storage; Electrochemical and High Temperature Applications

    Science.gov (United States)

    Falola, Bamidele Daniel

    sequestration easier. One complication of oxyfuel coal combustion is that corrosion problems can be exacerbated due to flue gas recycling, which is employed to dilute the pure O2 feed and reduce the flame temperature. Refractory metal diffusion coatings of Ti and Zr atop P91 steel were created and tested for their ability to prevent corrosion in an oxidizing atmosphere at elevated temperature. Using pack cementation, diffusion coatings of thickness approximately 12 and 20 microm are obtained for Ti and Zr, respectively. The effects of heating to 950°C for 24 hr in 5% O2 in He are studied in situ by thermogravimetric analyses (TGA), and ex situ by SEM analyses and depth profiling by EDX. For Ti-coated, Zr-coated and uncoated P91 samples, extended heating in an oxidizing environment causes relatively thick oxide growth, but extensive oxygen penetration greater than 2.7 mm below the sample surface, and eventual oxide exfoliation, are observed only for the uncoated P91 sample. For the Ti- and Zr-coated samples, oxygen penetrates approximately 16 and 56 microm, respectively, below the surface. in situ TGA verifies that Ti-and Zr-coated P91 samples undergo far smaller mass changes during corrosion than uncoated samples, reaching close to steady state mass after approximately four hours.

  19. Layer-by-Layer Enabled Nanomaterials for Chemical Sensing and Energy Conversion

    Science.gov (United States)

    Paterno, Leonardo G.; Soler, Maria A. G.

    2013-06-01

    The layer-by-layer (LbL) technique is a wet chemical method for the assembly of ultrathin films, with thicknesses up to 100 nm. This method is based on the successive transfer of molecular layers to a solid substrate that is dipped into cationic and anionic solutions in an alternating fashion. The adsorption is mainly driven by electrostatic interactions so that many molecular and nanomaterial systems can be engineered under this method. Moreover, it is inexpensive, can be easily performed, and does not demand sophisticated equipment or clean rooms. The most explored use of the LbL technique is to build up molecular devices for chemical sensing and energy conversion. Both applications require ultrathin films where specific elements must be organized with high control of thickness and spatial distribution, preferably in the nanolength and mesolength scales. In chemical sensors, the LbL technique is employed to assemble specific sensoactive materials such as conjugated polymers, enzymes, and immunological elements onto appropriated electrodes. Molecular recognition events are thus transduced by the assembled sensoactive layer. In energy-conversion devices, the LbL technique can be employed to fabricate different device's parts including electrodes, active layers, and auxiliary layers. In both applications, the devices' performance can be fully modulated and improved by simply varying film thickness and molecular architecture. The present review article highlights the main features of the LbL technique and provides a brief description of different (bio)chemical sensors, solar cells, and organic light-emitting diodes enabled by the LbL approach.

  20. Layer-by-layer fabrication of chemical-bonded graphene coating for solid-phase microextraction.

    Science.gov (United States)

    Zhang, Suling; Du, Zhuo; Li, Gongke

    2011-10-01

    A new fabrication strategy of the graphene-coated solid-phase microextraction (SPME) fiber is developed. Graphite oxide was first used as starting coating material that covalently bonded to the fused-silica substrate using 3-aminopropyltriethoxysilane (APTES) as cross-linking agent and subsequently deoxidized by hydrazine to give the graphene coating in situ. The chemical bonding between graphene and the silica fiber improve its chemical stability, and the obtained fiber was stable enough for more than 150 replicate extraction cycles. The graphene coating was wrinkled and folded, like the morphology of the rough tree bark. Its performance is tested by headspace (HS) SPME of polycyclic aromatic hydrocarbons (PAHs) followed by GC/MS analysis. The results showed that the graphene-coated fiber exhibited higher enrichment factors (EFs) from 2-fold for naphthalene to 17-fold for B(b)FL as compared to the commercial polydimethylsioxane (PDMS) fiber, and the EFs increased with the number of condensed rings of PAHs. The strong adsorption affinity was believed to be mostly due to the dominant role of π-π stacking interaction and hydrophobic effect, according to the results of selectivity study for a variety of organic compounds including PAHs, the aromatic compounds with different substituent groups, and some aliphatic hydrocarbons. For PAHs analysis, the graphene-coated fiber showed good precision (<11%), low detection limits (1.52-2.72 ng/L), and wide linearity (5-500 ng/L) under the optimized conditions. The repeatability of fiber-to-fiber was 4.0-10.8%. The method was applied to simultaneous analysis of eight PAHs with satisfactory recoveries, which were 84-102% for water samples and 72-95% for soil samples, respectively.

  1. The atmospheric chemical vapour deposition of coatings on glass

    International Nuclear Information System (INIS)

    Sanderson, Kevin David

    1996-01-01

    The deposition of thin films of indium oxide, tin doped indium oxide (ITO) and titanium nitride for solar control applications have been investigated by Atmospheric Chemical Vapour Deposition (APCVD). Experimental details of the deposition system and the techniques used to characterise the films are presented. Results from investigations into the deposition parameters, the film microstructure and film material properties are discussed. A range of precursors were investigated for the deposition of indium oxide. The effect of pro-mixing the vaporised precursor with an oxidant source and the deposition temperature has been studied. Polycrystalline In 2 O 3 films with a resistivity of 1.1 - 3x10 -3 Ω cm were obtained with ln(thd) 3 , oxygen and nitrogen. The growth of ITO films from ln(thd) 3 , oxygen and a range of tin dopants is also presented. The effect of the dopant precursor, the doping concentration, deposition temperature and the effect of additives on film growth and microstructure is discussed. Control over the preferred orientation growth of ITO has been achieved by the addition of acetate species during film growth. Insitu infra-red spectroscopy has been used to identify the gas phase species and identify the species responsible for the film modification. ITO films with a resistivities of 1.5 - 4x10 -4 Ω cm have been achieved. The deposition of titanium nitride by the APCVD of Ti(NMe 2 ) 4 and a mixture of Ti(NMe 2 ) 4 and ammonia is reported. Contamination of the films and pro-reaction between the precursors in the gas phase is discussed, and the synthesis of new precursors for the deposition of titanium nitride is reported. New precursors have been synthesised under anaerobic conditions and characterised by infra-red spectroscopy, 1 H and 13 C NMR, mass spectrometry, thermal gravemetric analysis and three by single crystal X-ray diffraction. Deposition of titanium nitride utilising two new precursors is reported. (author)

  2. Vanadium diffusion coating on HT-9 cladding for mitigating the fuel cladding chemical interactions

    Science.gov (United States)

    Lo, Wei-Yang; Yang, Yong

    2014-08-01

    Fuel cladding chemical interaction (FCCI) has been identified as one of the crucial issues for developing Ferritic/Martensitic (F/M) stainless steel claddings for metallic fuels in a fast reactor. The anticipated elevated temperature and high neutron flux can significantly aggravate the FCCI, in terms of formation of inter-diffusion and lower melting point eutectic phases. To mitigate the FCCI, vanadium carbide coating as a diffusion barrier was deposited on the HT-9 substrate using a pack cementation diffusion coating (PCDC) method, and the processing temperature was optimized down to 730 °C. A solid metallurgical bonding between the coating layer and substrate was achieved, and the coating is free from through depth cracks. The microstructural characterizations using SEM and TEM show a nanostructured grain structure. EDS/WDS and XRD analysis confirm the phase of coating layer as V2C. Diffusion couple tests at 660 °C for 100 h demonstrate that V2C layer with a thickness of less than 5 μm can effectively eliminate the inter-diffusion between the lanthanide cerium and HT-9 steel.

  3. Biocompatibility of Titania Nanotube Coatings Enriched with Silver Nanograins by Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Piotr Piszczek

    2017-09-01

    Full Text Available Bioactivity investigations of titania nanotube (TNT coatings enriched with silver nanograins (TNT/Ag have been carried out. TNT/Ag nanocomposite materials were produced by combining the electrochemical anodization and chemical vapor deposition methods. Fabricated coatings were characterized by scanning electron microscopy (SEM, X-ray photoelectron spectroscopy (XPS, and Raman spectroscopy. The release effect of silver ions from TNT/Ag composites immersed in bodily fluids, has been studied using inductively coupled plasma mass spectrometry (ICP-MS. The metabolic activity assay (MTT was applied to determine the L929 murine fibroblasts adhesion and proliferation on the surface of TNT/Ag coatings. Moreover, the results of immunoassays (using peripheral blood mononuclear cells—PBMCs isolated from rats allowed the estimation of the immunological activity of TNT/Ag surface materials. Antibacterial activity of TNT/Ag coatings with different morphological and structural features was estimated against two Staphylococcus aureus strains (ATCC 29213 and H9. The TNT/Ag nanocomposite layers produced revealed a good biocompatibility promoting the fibroblast adhesion and proliferation. A desirable anti-biofilm activity against the S. aureus reference strain was mainly noticed for these TiO2 nanotube coatings, which contain dispersed Ag nanograins deposited on their surface.

  4. Vanadium diffusion coating on HT-9 cladding for mitigating the fuel cladding chemical interactions

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Wei-Yang; Yang, Yong, E-mail: yongyang@ufl.edu

    2014-08-01

    Fuel cladding chemical interaction (FCCI) has been identified as one of the crucial issues for developing Ferritic/Martensitic (F/M) stainless steel claddings for metallic fuels in a fast reactor. The anticipated elevated temperature and high neutron flux can significantly aggravate the FCCI, in terms of formation of inter-diffusion and lower melting point eutectic phases. To mitigate the FCCI, vanadium carbide coating as a diffusion barrier was deposited on the HT-9 substrate using a pack cementation diffusion coating (PCDC) method, and the processing temperature was optimized down to 730 °C. A solid metallurgical bonding between the coating layer and substrate was achieved, and the coating is free from through depth cracks. The microstructural characterizations using SEM and TEM show a nanostructured grain structure. EDS/WDS and XRD analysis confirm the phase of coating layer as V{sub 2}C. Diffusion couple tests at 660 °C for 100 h demonstrate that V{sub 2}C layer with a thickness of less than 5 μm can effectively eliminate the inter-diffusion between the lanthanide cerium and HT-9 steel.

  5. Preparation and chemical stability of iron-nitride-coated iron microparticles

    International Nuclear Information System (INIS)

    Luo Xin; Liu Shixiong

    2007-01-01

    Iron-nitride-coated iron microparticles were prepared by nitridation of the surface of iron microparticles with ammonia gas at a temperature of 510 deg. C. The phases, composition, morphology, magnetic properties, and chemical stability of the particles were studied. The phases were α-Fe, ε-Fe 3 N, and γ-Fe 4 N. The composition varied from the core to the surface, with 99.8 wt% Fe in the core, and 93.8 wt% Fe and 6 wt% N in the iron-nitride coating. The thickness of the iron-nitride coating was about 0.28 μm. The chemical stability of the microparticles was greatly improved, especially the corrosion resistance in corrosive aqueous media. The saturation magnetization and the coercive force were 17.1x10 3 and 68 kA/m, respectively. It can be concluded that iron-nitride-coated iron microparticles will be very useful in many fields, such as water-based magnetorheological fluids and polishing fluids

  6. Conversion factors from counts to chemical ratios for the EURITRACK tagged neutron inspection system

    International Nuclear Information System (INIS)

    El Kanawati, W.; Perot, B.; Carasco, C.; Eleon, C.; Valkovic, V.; Sudac, D.; Obhodas, J.

    2011-01-01

    The EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) uses 14 MeV neutrons produced by the 3 H(d,n) 4 H fusion reaction to detect explosives and narcotics in cargo containers. Reactions induced by fast neutrons produce gamma rays, which are detected in coincidence with the associated alpha particle to determine the neutron direction. In addition, the neutron path length is obtained from a time-of-flight measurement, thus allowing the origin of the gamma rays inside the container to be determined. Information concerning the chemical composition of the target material is obtained from the analysis of the energy spectrum. The carbon, oxygen, and nitrogen relative count contributions must be converted to chemical proportions to distinguish illicit and benign organic materials. An extensive set of conversion factors based on Monte Carlo numerical simulations has been calculated, taking into account neutron slowing down and photon attenuation in the cargo materials. An experimental validation of the method is presented by comparing the measured chemical fractions of known materials, in the form of bare samples or hidden in a cargo container, to their real chemical composition. Examples of application to real cargo containers are also reported, as well as simulated data with explosives and illicit drugs.

  7. Conversion factors from counts to chemical ratios for the EURITRACK tagged neutron inspection system

    Energy Technology Data Exchange (ETDEWEB)

    El Kanawati, W. [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France); Perot, B., E-mail: bertrand.perot@cea.fr [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France); Carasco, C.; Eleon, C. [CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-Paul-lez-Durance (France); Valkovic, V. [A.C.T.d.o.o., Prilesje 4, 10000 Zagreb (Croatia); Sudac, D.; Obhodas, J. [Ruder Boskovic Institute, Bijenicka c. 54, 10000 Zagreb (Croatia)

    2011-10-21

    The EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) uses 14 MeV neutrons produced by the {sup 3}H(d,n){sup 4}H fusion reaction to detect explosives and narcotics in cargo containers. Reactions induced by fast neutrons produce gamma rays, which are detected in coincidence with the associated alpha particle to determine the neutron direction. In addition, the neutron path length is obtained from a time-of-flight measurement, thus allowing the origin of the gamma rays inside the container to be determined. Information concerning the chemical composition of the target material is obtained from the analysis of the energy spectrum. The carbon, oxygen, and nitrogen relative count contributions must be converted to chemical proportions to distinguish illicit and benign organic materials. An extensive set of conversion factors based on Monte Carlo numerical simulations has been calculated, taking into account neutron slowing down and photon attenuation in the cargo materials. An experimental validation of the method is presented by comparing the measured chemical fractions of known materials, in the form of bare samples or hidden in a cargo container, to their real chemical composition. Examples of application to real cargo containers are also reported, as well as simulated data with explosives and illicit drugs.

  8. Sputtered titanium oxynitride coatings for endosseous applications: Physical and chemical evaluation and first bioactivity assays

    Energy Technology Data Exchange (ETDEWEB)

    Banakh, Oksana, E-mail: oksana.banakh@he-arc.ch [Institute of Applied Microtechnologies, Haute Ecole Arc Ingénierie (HES-SO), Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Moussa, Mira, E-mail: mira.moussa@unige.ch [Laboratory of Biomaterials, University of Geneva, 19, rue Barthelemy Menn, CH-1205 Geneva (Switzerland); Matthey, Joel, E-mail: joel.matthey@he-arc.ch [Institute of Applied Microtechnologies, Haute Ecole Arc Ingénierie (HES-SO), Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Pontearso, Alessandro, E-mail: alessandro.pontearso@he-arc.ch [Institute of Applied Microtechnologies, Haute Ecole Arc Ingénierie (HES-SO), Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Cattani-Lorente, Maria, E-mail: maria.cattani-lorente@unige.ch [Laboratory of Biomaterials, University of Geneva, 19, rue Barthelemy Menn, CH-1205 Geneva (Switzerland); Sanjines, Rosendo, E-mail: rosendo.sanjines@epfl.ch [Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Condensed Matter Physics, Station 3, CH-1015 Lausanne (Switzerland); Fontana, Pierre, E-mail: Pierre.Fontana@hcuge.ch [Haemostasis laboratory, Geneva University Hospital, Rue Gabrielle-Perret-Gentil 4, CH-1205 Geneva (Switzerland); Wiskott, Anselm, E-mail: anselm.wiskott@unige.ch [Laboratory of Biomaterials, University of Geneva, 19, rue Barthelemy Menn, CH-1205 Geneva (Switzerland); Durual, Stephane, E-mail: stephane.durual@unige.ch [Laboratory of Biomaterials, University of Geneva, 19, rue Barthelemy Menn, CH-1205 Geneva (Switzerland)

    2014-10-30

    Highlights: • Titanium oxynitride coatings (TiN{sub x}O{sub y}) with chemical composition ranging from TiN to TiO{sub 2} were deposited by magnetron sputtering from a metallic Ti target using a mixture of O{sub 2} + N{sub 2}. • The coatings structure as well as physical, chemical and mechanical properties progressively changes as a function of oxygen content in the TiN{sub x}O{sub y.} • All TiN{sub x}O{sub y} coatings show a significantly higher level of bioactivity as compared to bare Ti substrates (1.2 to 1.4 fold increase in cell proliferation). Despite variations in surface chemistry, topography and surface tension observed on films as a function of chemical composition, no significant differences in the films’ biological activity were observed after 3 days of testing. - Abstract: Titanium oxynitride coatings (TiN{sub x}O{sub y}) are considered a promising material for applications in dental implantology due to their high corrosion resistance, their biocompatibility and their superior hardness. Using the sputtering technique, TiN{sub x}O{sub y} films with variable chemical compositions can be deposited. These films may then be set to a desired value by varying the process parameters, that is, the oxygen and nitrogen gas flows. To improve the control of the sputtering process with two reactive gases and to achieve a variable and controllable coating composition, the plasma characteristics were monitored in-situ by optical emission spectroscopy. TiN{sub x}O{sub y} films were deposited onto commercially pure (ASTM 67) microroughened titanium plates by reactive magnetron sputtering. The nitrogen gas flow was kept constant while the oxygen gas flow was adjusted for each deposition run to obtain films with different oxygen and nitrogen contents. The physical and chemical properties of the deposited films were analyzed as a function of oxygen content in the titanium oxynitride. The potential application of the coatings in dental implantology was assessed by

  9. Research of boron conversion coating in neutron detector with boron deposited GEM

    International Nuclear Information System (INIS)

    Ye Di; Sun Zhijia; Zhou Jianrong; Wang Yanfeng; Yang Guian; Xu Hong; Chen Yuanbai; Xiao Yu; Diao Xungang

    2014-01-01

    GEM is a flourishing new gas detector and nowadays its technology become more mature. It has outstanding properties, such as excellent position resolution, high counting rate, radiation resistance, simple and flexible signal readout, can be large-area detector, wide application range. Detector with boron deposited GEM uses multilayer GEM with deposited boron film as neutron conversion carrier which reads out the information of neutron shot from the readout electrode with gas amplification from every GEM layer. The detector is high performance which can meet the demands of neutron detector of a new generation. Boron deposited neutron conversion electrode with boron deposited cathode and GEM included is the core part of the detector. As boron is a high-melting-point metalloid (> 2 000 ℃), electroplating and thermal evaporation are inappropriate ways. So finding a way to deposit boron on electrode which can meet the demands become a key technology in the development of neutron detector with boron deposited GEM. Compared with evaporation, sputtering has features such as low deposition temperature, high film purity, nice adhesive, thus is appropriate for our research. Magnetron sputtering is a improved way of sputtering which can get lower sputtering air pressure and higher target voltage, so that we can get better films. Through deposit process, the research uses magnetron sputtering to deposit pure boron film on copper electrode and GEM film. This method can get high quality, nice adhere, high purity, controllable uniformity, low cost film with high speed film formation. (authors)

  10. Surface-dependent chemical equilibrium constants and capacitances for bare and 3-cyanopropyldimethylchlorosilane coated silica nanochannels

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo; Frey, Jared; Pennathur, Sumita

    2011-01-01

    , and pK+ are constant and independent of surface composition. Our theoretical model consists of three parts: (i) a chemical equilibrium model of the bare or coated wall, (ii) a chemical equilibrium model of the buffered bulk electrolyte, and (iii) a self-consistent Gouy–Chapman–Stern triple-layer model...... of the electrochemical double layer coupling these two equilibrium models. To validate our model, we used both pH-sensitive dye-based capillary filling experiments as well as electro-osmotic current-monitoring measurements. Using our model we predict the dependence of ζ potential, surface charge density, and capillary...

  11. Lipids as renewable resources: current state of chemical and biotechnological conversion and diversification.

    Science.gov (United States)

    Metzger, J O; Bornscheuer, U

    2006-06-01

    Oils and fats are the most important renewable raw materials of the chemical industry. They make available fatty acids in such purity that they may be used for chemical conversions and for the synthesis of chemically pure compounds. Oleic acid (1) from "new sunflower," linoleic acid (2) from soybean, linolenic acid (3) from linseed, erucic acid (4) from rape seed, and ricinoleic acid (5) from castor oil are most important for chemical transformations offering in addition to the carboxy group one or more C-C-double bonds. New plant oils containing fatty acids with new and interesting functionalities such as petroselinic acid (6) from Coriandrum sativum, calendic acid (7) from Calendula officinalis, alpha-eleostearic acid (8) from tung oil, santalbic acid (9) from Santalum album (Linn.), and vernolic acid (10) from Vernonia galamensis are becoming industrially available. The basic oleochemicals are free fatty acids, methyl esters, fatty alcohols, and fatty amines as well as glycerol as a by-product. Their interesting new industrial applications are the usage as environmentally friendly industrial fluids and lubricants, insulating fluid for electric utilities such as transformers and additive to asphalt. Modern methods of synthetic organic chemistry including enzymatic and microbial transformations were applied extensively to fatty compounds for the selective functionalization of the alkyl chain. Syntheses of long-chain diacids, omega-hydroxy fatty acids, and omega-unsaturated fatty acids as base chemicals derived from vegetable oils were developed. Interesting applications were opened by the epoxidation of C-C-double bonds giving the possibility of photochemically initiated cationic curing and access to polyetherpolyols. Enantiomerically pure fatty acids as part of the chiral pool of nature can be used for the synthesis of nonracemic building blocks.

  12. PROCESSES PROCEEDING ON CONCRETE COATING SURFACES IN CASE OF THEIR CHEMICAL PROTECTION AGAINST WINTER SLIPPERINESS

    Directory of Open Access Journals (Sweden)

    M. K. Pshembaev

    2016-01-01

    Full Text Available Concrete coatings of road traffic highways along with operational loadings caused by flow of traffic are subjected to weather and climate impacts. These are the following impacts: changes in temperature and air humidity, solar radiation,surface wind speed which is participating in formation of active heat-and-mass transfer in a surface layer of the concrete coating. One of the most complicated and important periods in the road traffic highway operation is so called transitional nature period (from Summer to Autumn and from Winter to Spring. These periods are accompanied by intensive rain and snow fall and possible formation of ice loading on the surface of cement and concrete coatings. These impacts significantly deteriorate friction properties of road pavement (friction factor φ is decreased up to 0.4 and less that can be a prerequisite to creation of various accident situations due to sharp increase in braking distance. For example, while having dry pavement the friction factor φ is equal to 0.80–0.85, and during icy condition of the road the factor φ constitutes 0.08–0.15 that consequently entails an increase in braking distance from 7.5 up to 20.0 m and more. It is quite possible that ice layer appears on the surface of concrete coatings when road traffic highways are used in winter season. Various methods are applicable to remove ice from the surface they can include also ice-melting chemicals and sodium chloride NaCl in particular. The chemical decreases freezing temperature of the formed brine and causes ice melting at negative temperature. Processes of NaCl dissolution and ice melting have an endothermic character, in other words these processes are accompanied by heat ingress and due to it temperature is sharply decreasing in the surface layer of the concrete coating which is under the melting ice and in this case phenomenon of thermal shock is observed.

  13. Ceramic coatings by ion irradiation of polycarbosilanes and polysiloxanes. Pt. 1: Conversion mechanism

    International Nuclear Information System (INIS)

    Pivin, J.C.; Colombo, P.

    1997-01-01

    Changes of composition and structure of various types of polysiloxanes and polycarbosilanes when submitted to irradiation with ions of increasing mass, were analysed by means of several ion-beam analytical techniques, Raman and Fourier transform-infrared spectroscopes. Ion irradiations is as efficient as annealing at temperatures above 1000 o C for releasing hydrogen from these organic-inorganic polymers, and the radiolytic evolution of hydrogen is selective, whereas methane, silanes and carbon monoxide are also evolved during heat treatments. The kinetics of the polymer conversion into amorphous ceramics depends strongly on the linear density of energy transferred by ions to electron shells of target atoms, according to the ion energy per nucleon and to the nature of the side groups. Some of the carbon atoms segregate in clusters exhibiting a diamond-like hybridization state, in contrast to the clusters of turbostatic graphite formed in pyrolysed films. (Author)

  14. INVESTIGATION OF TRIVALENT CHROMIUM-BASED CONVERSION COATINGS ON ELECTROGALVANISED STEEL

    Directory of Open Access Journals (Sweden)

    Célia Regina Tomachuk

    2012-12-01

    Full Text Available The passivation process of electrogavanised steel is very important, especially for improving of the corrosion protection and the thickness of the layer obtained can further enhance such protection. In the market exists Cr(III‑based thick layers passivation, however, are operated around 60°C. In order to attend market demands a new process with only 20% of the chromium content is developed, which operates at room temperature. The corrosion behavior was investigated through electrochemical impedance spectroscopy technique in chloride solution and accelerated tests in salt spray chamber. The combination of these tests provides a more complete assessment of the behavior against corrosion of layer passivation obtained. The results with respect to appearance, brightness, uniformity, layer thickness and corrosion resistance are similar to those presented by Cr(III based passivation existing market and Cr(VI based conversion treatment.

  15. Recent Advances in Photoelectrochemical Applications of Silicon Materials for Solar-to-Chemicals Conversion.

    Science.gov (United States)

    Zhang, Doudou; Shi, Jingying; Zi, Wei; Wang, Pengpeng; Liu, Shengzhong Frank

    2017-11-23

    Photoelectrochemical (PEC) technology for the conversion of solar energy into chemicals requires cost-effective photoelectrodes to efficiently and stably drive anodic and/or cathodic half-reactions to complete the overall reactions for storing solar energy in chemical bonds. The shared properties among semiconducting photoelectrodes and photovoltaic (PV) materials are light absorption, charge separation, and charge transfer. Earth-abundant silicon materials have been widely applied in the PV industry, and have demonstrated their efficiency as alternative photoabsorbers for photoelectrodes. Many efforts have been made to fabricate silicon photoelectrodes with enhanced performance, and significant progress has been achieved in recent years. Herein, recent developments in crystalline and thin-film silicon-based photoelectrodes (including amorphous, microcrystalline, and nanocrystalline silicon) immersed in aqueous solution for PEC hydrogen production from water splitting are summarized, as well as applications in PEC CO 2 reduction and PEC regeneration of discharged species in redox flow batteries. Silicon is an ideal material for the cost-effective production of solar chemicals through PEC methods. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Biochemical Conversion Processes of Lignocellulosic Biomass to Fuels and Chemicals - A Review.

    Science.gov (United States)

    Brethauer, Simone; Studer, Michael H

    2015-01-01

    Lignocellulosic biomass - such as wood, agricultural residues or dedicated energy crops - is a promising renewable feedstock for production of fuels and chemicals that is available at large scale at low cost without direct competition for food usage. Its biochemical conversion in a sugar platform biorefinery includes three main unit operations that are illustrated in this review: the physico-chemical pretreatment of the biomass, the enzymatic hydrolysis of the carbohydrates to a fermentable sugar stream by cellulases and finally the fermentation of the sugars by suitable microorganisms to the target molecules. Special emphasis in this review is put on the technology, commercial status and future prospects of the production of second-generation fuel ethanol, as this process has received most research and development efforts so far. Despite significant advances, high enzyme costs are still a hurdle for large scale competitive lignocellulosic ethanol production. This could be overcome by a strategy termed 'consolidated bioprocessing' (CBP), where enzyme production, enzymatic hydrolysis and fermentation is integrated in one step - either by utilizing one genetically engineered superior microorganism or by creating an artificial co-culture. Insight is provided on both CBP strategies for the production of ethanol as well as of advanced fuels and commodity chemicals.

  17. On the tungsten single crystal coatings achieved by chemical vapor transportation deposition

    Energy Technology Data Exchange (ETDEWEB)

    Shi, J.Q.; Shen, Y.B.; Yao, S.Y.; Zhang, P.J.; Zhou, Q.; Guo, Y.Z. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Tan, C.W., E-mail: tanchengwen@bit.edu.cn [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); China Astronaut Research and Training Center, Beijing 100094 (China); Yu, X.D. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); China Astronaut Research and Training Center, Beijing 100094 (China); Nie, Z.H. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Ma, H.L. [China Astronaut Research and Training Center, Beijing 100094 (China); Cai, H.N. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2016-12-15

    The tungsten single crystal has many excellent properties, namely a high melting point, high anti-creeping strength. Chemical vapor transportation deposition (CVTD) is a possible approach to achieve large-sized W single crystals for high-temperature application such as the cathode of a thermionic energy converter. In this work, CVTD W coatings were deposited on the monocrystalline molybdenum substrate (a tube with < 111 > axial crystalline orientation) using WCl{sub 6} as a transport medium. The microstructures of the coatings were investigated by a scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). The as-deposited coatings are hexagonal prisms—rough surfaces perpendicular to < 110 > with alternating hill-like bulges and pits at the side edges of the prisms, and flat surfaces perpendicular to < 112 > with arc-shaped terraces at the side faces. This can be explained by two-dimensional nucleation -mediated lateral growth model. Some parts of the coatings contain hillocks of an exotic morphology (noted as “abnormal growth”). The authors hypothesize that the abnormal growth is likely caused by the defects of the Mo substrate, which facilitate W nucleation sites, cause orientation difference, and may even form boundaries in the coatings. A dislocation density of 10{sup 6} to 10{sup 7} (counts/cm{sup 2}) was revealed by an etch-pit method and synchrotron X-ray diffraction. As the depositing temperature rises, the dislocation density decreases, and no sub-boundaries are found on samples deposited over 1300 °C, as a result of atom diffusion and dislocation climbing. - Highlights: •The varied growth rate causes the different morphologies of different planes. •The W coating is a single crystal when only single hillocks appear. •The (110) plane tends to have the lowest dislocation density. •The dislocation density tends to decrease as the temperature increases.

  18. On the tungsten single crystal coatings achieved by chemical vapor transportation deposition

    International Nuclear Information System (INIS)

    Shi, J.Q.; Shen, Y.B.; Yao, S.Y.; Zhang, P.J.; Zhou, Q.; Guo, Y.Z.; Tan, C.W.; Yu, X.D.; Nie, Z.H.; Ma, H.L.; Cai, H.N.

    2016-01-01

    The tungsten single crystal has many excellent properties, namely a high melting point, high anti-creeping strength. Chemical vapor transportation deposition (CVTD) is a possible approach to achieve large-sized W single crystals for high-temperature application such as the cathode of a thermionic energy converter. In this work, CVTD W coatings were deposited on the monocrystalline molybdenum substrate (a tube with < 111 > axial crystalline orientation) using WCl 6 as a transport medium. The microstructures of the coatings were investigated by a scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). The as-deposited coatings are hexagonal prisms—rough surfaces perpendicular to < 110 > with alternating hill-like bulges and pits at the side edges of the prisms, and flat surfaces perpendicular to < 112 > with arc-shaped terraces at the side faces. This can be explained by two-dimensional nucleation -mediated lateral growth model. Some parts of the coatings contain hillocks of an exotic morphology (noted as “abnormal growth”). The authors hypothesize that the abnormal growth is likely caused by the defects of the Mo substrate, which facilitate W nucleation sites, cause orientation difference, and may even form boundaries in the coatings. A dislocation density of 10 6 to 10 7 (counts/cm 2 ) was revealed by an etch-pit method and synchrotron X-ray diffraction. As the depositing temperature rises, the dislocation density decreases, and no sub-boundaries are found on samples deposited over 1300 °C, as a result of atom diffusion and dislocation climbing. - Highlights: •The varied growth rate causes the different morphologies of different planes. •The W coating is a single crystal when only single hillocks appear. •The (110) plane tends to have the lowest dislocation density. •The dislocation density tends to decrease as the temperature increases.

  19. Chemical and Sensory Quality Preservation in Coated Almonds with the Addition of Antioxidants.

    Science.gov (United States)

    Larrauri, Mariana; Demaría, María Gimena; Ryan, Liliana C; Asensio, Claudia M; Grosso, Nelson R; Nepote, Valeria

    2016-01-01

    Almonds provide many benefits such as preventing heart disease due to their high content of oleic fatty acid-rich oil and other important nutrients. However, they are susceptible to oxidation reactions causing rancidity during storage. The objective of this work was to evaluate the chemical and sensory quality preservation of almonds coated with carboxymethyl cellulose and with the addition of natural and synthetic antioxidants during storage. Four samples were prepared: almonds without coating (C), almonds coated with carboxymethyl cellulose (CMC), almonds coated with CMC supplemented with peanut skins extract (E), and almonds coated with CMC and supplemented with butylhydroxytoluene (BHT). Proximate composition and fatty acid profile were determined on raw almonds. Almond samples (C, CMC, E and BHT) were stored at 40 °C for 126 d. Lipid oxidation indicators: peroxide value (PV), conjugated dienes (CD), volatile compounds (hexanal and nonanal), and sensory attributes were determined for the stored samples. Samples showed small but significant increases in PV, CD, hexanal and nonanal contents, and intensity ratings of negative sensory attributes (oxidized and cardboard). C had the highest tendency to deterioration during storage. At the end of storage (126 d), C had the highest PV (3.90 meqO2 /kg), and BHT had the lowest PV (2.00 meqO2 /kg). CMC and E samples had similar intermediate PV values (2.69 and 2.57 meqO2 /kg, respectively). CMC coating and the addition of natural (peanut skin extract) and synthetic (BHT) antioxidants provide protection to the roasted almond product. © 2015 Institute of Food Technologists®

  20. Conversion of metallurgical coke and coal using a Coal Direct Chemical Looping (CDCL) moving bed reactor

    International Nuclear Information System (INIS)

    Luo, Siwei; Bayham, Samuel; Zeng, Liang; McGiveron, Omar; Chung, Elena; Majumder, Ankita; Fan, Liang-Shih

    2014-01-01

    Highlights: • Accumulated more than 300 operation hours were accomplished for the moving bed reducer reactor. • Different reactor operation variables were investigated with optimal conditions identified. • High conversions of sub-bituminous coal and bituminous coal were achieved without flow problems. • Co-current and counter-current contact modes were tested and their applicability was discussed. - Abstract: The CLC process has the potential to be a transformative commercial technology for a carbon-constrained economy. The Ohio State University Coal Direct Chemical Looping (CDCL) process directly converts coal, eliminating the need for a coal gasifier oran air separation unit (ASU). Compared to other solid-fuel CLC processes, the CDCL process is unique in that it consists of a countercurrent moving bed reducer reactor. In the proposed process, coal is injected into the middle of the moving bed, whereby the coal quickly heats up and devolatilizes, splitting the reactor roughly into two sections with no axial mixing. The top section consists of gaseous fuel produced from the coal volatiles, and the bottom section consists of the coal char mixed with the oxygen carrier. A bench-scale moving bed reactor was used to study the coal conversion with CO 2 as the enhancing gas. Initial tests using metallurgical cokefines as feedstock were conducted to test the effects of operational variables in the bottom section of the moving bed reducer, e.g., reactor temperature, oxygen carrier to char ratio, enhancer gas CO 2 flow rate, and oxygen carrier flow rates. Experiments directly using coal as the feedstock were subsequently carried out based on these test results. Powder River Basin (PRB) coal and Illinois #6 coal were tested as representative sub-bituminous and bituminous coals, respectively. Nearly complete coal conversion was achieved using composite iron oxide particles as the oxygen carriers without any flow problems. The operational results demonstrated that a

  1. Fully solar-powered photoelectrochemical conversion for simultaneous energy storage and chemical sensing.

    Science.gov (United States)

    Wang, Yongcheng; Tang, Jing; Peng, Zheng; Wang, Yuhang; Jia, Dingsi; Kong, Biao; Elzatahry, Ahmed A; Zhao, Dongyuan; Zheng, Gengfeng

    2014-06-11

    We report the development of a multifunctional, solar-powered photoelectrochemical (PEC)-pseudocapacitive-sensing material system for simultaneous solar energy conversion, electrochemical energy storage, and chemical detection. The TiO2 nanowire/NiO nanoflakes and the Si nanowire/Pt nanoparticle composites are used as photoanodes and photocathodes, respectively. A stable open-circuit voltage of ∼0.45 V and a high pseudocapacitance of up to ∼455 F g(-1) are obtained, which also exhibit a repeating charging-discharging capability. The PEC-pseudocapacitive device is fully solar powered, without the need of any external power supply. Moreover, this TiO2 nanowire/NiO nanoflake composite photoanode exhibits excellent glucose sensitivity and selectivity. Under the sun light illumination, the PEC photocurrent shows a sensitive increase upon different glucose additions. Meanwhile in the dark, the open-circuit voltage of the charged pseudocapacitor also exhibits a corresponding signal over glucose analyte, thus serving as a full solar-powered energy conversion-storage-utilization system.

  2. Physico-chemical conversion of sulphur dioxide in a power plant plume

    International Nuclear Information System (INIS)

    Lewin, E.E.

    1978-03-01

    A review is given of the actual knowledge of SO 2 atmospheric processes gained from laboratory and field experiments. Implementation is described of the instrumentation, operational procedures and analytical methods in connection with a field study of the conversion and dispersion of SO 2 in an oil-fired power plant plume. Furthermore, the preliminary results are included of five experiments performed until the end of 1976. Measurements were performed from an aircraft and included continuous registration of NOsub(x), SO 2 , SF 6 , and particle concentrations, as well as temperature and humidity. It was planned to label sulphur from the source in question with sulphur-35. However, this part of the experiment had to be abandoned because of public opinion on the use of radioactive tracers. Sulphur hexafluoride was used as an internal tracer for the plume. A half-life for SO 2 of about 30 min was determined from one of the experiments. In this connection the possibility of using NOsub(x) as a conservative tracer is shown. Possible ways of removal are discussed and the rate of two of the processes is calculated by means of a model describing the chemical conversion in a dispersing plume. (author)

  3. Study on CexLa1-xO2 Buffer Layer used in Coated Conductors by Chemical Solution Method

    DEFF Research Database (Denmark)

    Zhao, Yue; Suo, Hongli; Grivel, Jean-Claude

    2009-01-01

    Developing multi-functional single buffer layer is one of the most important challenges for simplification of coated conductors configuration. Ladoped CeO2 films were prepared by chemical solution method. And surface morphology and texture quality of the La-doped CeO2 films were investigated...... method. It suggects that Ce0.9La0.1O2 film prepared by chemical solution route have a promising prospect for the simplification of coated conductors configuration....

  4. Quantitative chemical method for the determination of the disordered carbon component in pyrocarbon coatings of fuel particles

    International Nuclear Information System (INIS)

    Wolfrum, E.A.; Nickel, H.

    1977-01-01

    The chemical behavior of the surface of pyrocarbon (PyC) coatings of nuclear fuel particles was investigated in aqueous suspension by reaction with oxygen at room temperature. The concentration of the disordered material component, which has a large internal surface, can be identified by means of a pH change. Using this fact, a chemical method was developed that can be used for the quantitative determination of the concentration of this carbon component in the PyC coating

  5. Chemical conversion of natural gas. Final report; Kjemisk konvertering av naturgass. Sluttrapport

    Energy Technology Data Exchange (ETDEWEB)

    Simonsen, Haavard

    2000-07-01

    This report presents examples of gas research of a high international class. This research has strengthened the technological position of Norwegian industry in the field of gas utilization, which will be of great importance for Norwegian industry, nationally and internationally. The competence of the research and development institutions has been further developed within the subjects of catalysis, reactor technology and chemical engineering. These subjects are of central importance irrespective of whether or not the gas is to be utilized with or without CO{sub 2} deposition, for synthetic diesel, for methanol, for olefins, for proteins, for hydrogen or other purposes. The main purpose of the programme discussed was to educate PhDs and to develop skill of strategic importance for Norwegian industry. There are sections on synthesis gas, direct conversion, methanol to olefins, fluidized bed reactors and system technology.

  6. The effects to the structure and electrochemical behavior of zinc phosphate conversion coatings with ethanolamine on magnesium alloy AZ91D

    International Nuclear Information System (INIS)

    Li Qing; Xu Shuqiang; Hu Junying; Zhang Shiyan; Zhong Xiankang; Yang Xiaokui

    2010-01-01

    This paper discussed a zinc phosphate conversion coating formed on magnesium alloy AZ91D from the phosphating bath with varying amounts of ethanolamine (MEA). The effects of MEA on the form, structure, phase composition and electrochemical behavior of the phosphate coatings were examined using an scanning electron microscopy (SEM), X-ray diffraction (XRD) potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) measurements. Interpretations of the electrical elements of the equivalent circuit were obtained from the SEM structure of the coatings, assumed to be formed of two layers: an outer porous crystal layer and an inner flat amorphous layer. The result showed that adding MEA refined the microstructure of the crystal layer and that the phosphate coating, derived at the optimal content of 1.2 g/L, with the most uniform and compact outer crystal layer provided the best corrosion protection.

  7. Effect of Thickness on the Morphology and Corrosion Behavior of Cerium-Based Conversion Coatings on AZ31B Magnesium Alloy

    Science.gov (United States)

    Castano, Carlos E.; Maddela, Surender; O'Keefe, Matthew J.; Wang, Yar-Ming

    Cerium-based conversion coatings (CeCCs) were deposited onto AZ31B magnesium alloy substrates using a spontaneous reaction of CeCl3, H2O2 and gelatin in a water-based solution. The coating thickness was adjusted by controlling the immersion time in the deposition solution. Prior to deposition, the AZ31B substrates were treated using an acid pickling in nitric acid and then an alkaline cleaning in sodium metasilicate pentahydrate. After deposition, the coated samples were immersed in a phosphate bath that converted cerium oxide/hydroxide into cerium phosphate. Electrochemical impedance spectroscopy, potentiodynamic polarization and neutral salt spray testing studies indicated that 100 nm thick CeCC had better corrosion performance than 400 nm coatings. Characterization of the CeCCs by transmission electron microscopy (TEM) revealed a three layer structure with different compositions.

  8. Carbon dioxide conversion to fuels and chemicals using a hybrid green process

    International Nuclear Information System (INIS)

    Ramachandriya, Karthikeyan D.; Kundiyana, Dimple K.; Wilkins, Mark R.; Terrill, Jennine B.; Atiyeh, Hasan K.; Huhnke, Raymond L.

    2013-01-01

    Highlights: • A unique CO 2 conversion technology using microorganisms was demonstrated. • Corn steep liquor medium enhanced production of n-butanol and n-hexanol. • Cotton seed extract (CSE) medium promoted ethanol formation. • CSE medium without morpholinoethanesulfonic acid buffer reduced the cost by 99%. - Abstract: A unique hybrid technology that uses renewable hydrogen (H 2 ) and carbon dioxide (CO 2 ) sequestered from large point sources, to produce fuels and chemicals has been proposed and tested. The primary objective of this research was to determine the feasibility of using two acetogenic bacteria to metabolize H 2 and CO 2 for the production of ethanol. Three experiments were conducted in small scale reactors to select a bacterium, feed gas composition and nutrient medium source to produce ethanol. The results indicated that Clostridium carboxidivorans produced 33% more ethanol and 66% less acetic acid compared to Clostridium ragsdalei, making C. carboxidivorans the better candidate for ethanol production. Furthermore, the removal of morpholinoethanesulfonic acid (MES) buffer from cotton seed extract (CSE) medium offered a low-cost medium for fermentations. Additionally, we observed that corn steep liquor (CSL) in the medium diversified the product range with both bacteria. Maximum concentrations of ethanol, n-butanol, n-hexanol, acetic acid, butyric acid, and hexanoic acid from different fermentation treatments were 2.78 g L −1 , 0.70 g L −1 , 0.52 g L −1 , 4.06 g L −1 , 0.13 g L −1 and 0.42 g L −1 , respectively. This study highlights the important role that acetogenic microbes can offer for CO 2 conversion into valuable fuels and chemicals

  9. Preparation of Ti species coating hydrotalcite by chemical vapor deposition for photodegradation of azo dye.

    Science.gov (United States)

    Xiao, Gaofei; Zeng, HongYan; Xu, Sheng; Chen, ChaoRong; Zhao, Quan; Liu, XiaoJun

    2017-10-01

    TiO 2 in anatase crystal phase is a very effective catalyst in the photocatalytic oxidation of organic compounds in water. To improve its photocatalytic activity, the Ti-coating MgAl hydrotalcite (Ti-MgAl-LDH) was prepared by chemical vapor deposition (CVD) method. Response surface method (RSM) was employed to evaluate the effect of Ti species coating parameters on the photocatalytic activity, which was found to be affected by the furnace temperature, N 2 flow rate and influx time of precursor gas. Application of RSM successfully increased the photocatalytic efficiency of the Ti-MgAl-LDH in methylene blue photodegradation under UV irradiation, leading to improved economy of the process. According to the results from X-ray diffraction, scanning electron microscopy, Brunner-Emmet-Teller and Barrett-Joyner-Hallender, thermogravimetric and differential thermal analysis, UV-vis diffuse reflectance spectra analyses, the Ti species (TiO 2 or/and Ti 4+ ) were successfully coated on the MgAl-LDH matrix. The Ti species on the surface of the Ti-MgAl-LDH lead to a higher photocatalytic performance than commercial TiO 2 -P25. The results suggested that CVD method provided a new approach for the industrial preparation of Ti-coating MgAl-LDH material with good photocatalytic performances. Copyright © 2017. Published by Elsevier B.V.

  10. Erythrocyte membrane-coated gold nanocages for targeted photothermal and chemical cancer therapy

    Science.gov (United States)

    Zhu, Dao-Ming; Xie, Wei; Xiao, Yu-Sha; Suo, Meng; Zan, Ming-Hui; Liao, Qing-Quan; Hu, Xue-Jia; Chen, Li-Ben; Chen, Bei; Wu, Wen-Tao; Ji, Li-Wei; Huang, Hui-Ming; Guo, Shi-Shang; Zhao, Xing-Zhong; Liu, Quan-Yan; Liu, Wei

    2018-02-01

    Recently, red blood cell (RBC) membrane-coated nanoparticles have attracted much attention because of their excellent immune escapability; meanwhile, gold nanocages (AuNs) have been extensively used for cancer therapy due to their photothermal effect and drug delivery capability. The combination of the RBC membrane coating and AuNs may provide an effective approach for targeted cancer therapy. However, few reports have shown the utilization of combining these two technologies. Here, we design erythrocyte membrane-coated gold nanocages for targeted photothermal and chemical cancer therapy. First, anti-EpCam antibodies were used to modify the RBC membranes to target 4T1 cancer cells. Second, the antitumor drug paclitaxel (PTX) was encapsulated into AuNs. Then, the AuNs were coated with the modified RBC membranes. These new nanoparticles were termed EpCam-RPAuNs. We characterized the capability of the EpCam-RPAuNs for selective tumor targeting via exposure to near-infrared irradiation. The experimental results demonstrate that EpCam-RPAuNs can effectively generate hyperthermia and precisely deliver the antitumor drug PTX to targeted cells. We also validated the biocompatibility of the EpCam-RAuNs in vitro. By combining the molecularly modified targeting RBC membrane and AuNs, our approach provides a new way to design biomimetic nanoparticles to enhance the surface functionality of nanoparticles. We believe that EpCam-RPAuNs can be potentially applied for cancer diagnoses and therapies.

  11. Bitumen coating as a tool for improving the porosity and chemical stability of simulated cement-waste forms

    International Nuclear Information System (INIS)

    Saleh, H.M.

    2010-01-01

    Coating process of simulated cement-based waste form with bitumen was evaluated by performing physical and chemical experimental tests. X-ray diffraction (X-RD), Fourier transform infrared spectroscopy (FT-IR) and electron microscope investigations were applied on coated and non-coated simulated waste forms. Experimental results indicated that coating process improved the applicable properties of cement-based waste form such as porosity and leachability. Diffusion coefficients and leach indecies of coated specimens were calculated and show acceptable records. It could be stated that coating cemented waste form by bitumen emulsion, isolate the radioactive contaminants, thus reduces their back release to surrounding and in consequently save the environment proper and safe

  12. Surface characteristic of chemically converted graphene coated low carbon steel by electro spray coating method for polymer electrolyte membrane fuel cell bipolar plate.

    Science.gov (United States)

    Kim, Jungsoo; Kim, Yang Do; Nam, Dae Geun

    2013-05-01

    Graphene was coated on low carbon steel (SS400) by electro spray coating method to improve its properties of corrosion resistance and contact resistance. Exfoliated graphite was made of the graphite by chemical treatment (Chemically Converted Graphene, CCG). CCG is distributed using dispersing agent, and low carbon steel was coated with diffuse graphene solution by electro spray coating method. The structure of the CCG was analyzed using XRD and the coating layer of surface was analyzed using SEM. Analysis showed that multi-layered graphite structure was destroyed and it was transformed in to fine layers graphene structure. And the result of SEM analysis on the surface and the cross section, graphene layer was uniformly formed with 3-5 microm thickness on the surface of substrate. Corrosion resistance test was applied in the corrosive solution which is similar to the polymer electrolyte membrane fuel cell (PEMFC) stack inside. And interfacial contact resistance (ICR) test was measured to simulate the internal operating conditions of PEMFC stack. As a result of measuring corrosion resistance and contact resistance, it could be confirmed that low carbon steel coated with CCG was revealed to be more effective in terms of its applicability as PEMFC bipolar plate.

  13. Synthesis of Cu-coated Graphite Powders Using a Chemical Reaction Process

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jun-Ho; Park, Hyun-Kuk; Oh, Ik-Hyun [Korea Institute of Industrial Technology (KITECH), Gwangju (Korea, Republic of); Lim, Jae-Won [Chonbuk National University, Jeonju (Korea, Republic of)

    2017-05-15

    In this paper, Cu-coated graphite powders for a low thermal expansion coefficient and a high thermal conductivity are fabricated using a chemical reaction process. The Cu particles adhere to the irregular graphite powders and they homogeneously disperse in the graphite matrix. Cu-coated graphite powders are coarser at approximately 3-4 μm than the initial graphite powders; furthermore, their XRD patterns exhibit a low intensity in the oxide peak with low Zn powder content. For the passivation powders, the transposition solvent content has low values, and the XRD pattern of the oxide peaks is almost non-existent, but the high transposition solvent content does not exhibit a difference to the non-passivation treated powders.

  14. Synthesis of Ceramic Protective Coatings for Chemical Plant Parts Operated in Hi-temperature and Corrosive/Erosive Environment

    International Nuclear Information System (INIS)

    Son, M. C.; Park, J. R.; Hong, K. T.; Seok, H. K.

    2005-01-01

    Some feasibility studies are conducted to produce an advanced ceramic coating, which reveals superior chemical and mechanical strength, on metal base structure used in chemical plant. This advanced coating on metallic frame can replace ceramic delivery pipe and reaction chamber used in chemical plant, which are operated in hi-temperature and corrosive/erosive environment. An dual spraying is adopted to reduce the residual stress in order to increase the coating thickness and the residual stress is estimated by in-situ manner. Then new methodology is tried to form special coating of yttrium aluminum garnet(YAG), which reveals hi-strength and low-creep rates at hi-temperature, superior anti-corrosion property, hi-stability against Alkali-Vapor corrosion, and so on, on iron base structure. To verify the formation of YAG during thermal spraying, XRD(X ray diffraction) technique was used

  15. The Tribological Behaviors of Three Films Coated on Biomedical Titanium Alloy by Chemical Vapor Deposition

    Science.gov (United States)

    Wang, Song; Liao, Zhenhua; Liu, Yuhong; Liu, Weiqiang

    2015-11-01

    Three thin films (DLC, a-C, and TiN) were performed on Ti6Al4V by chemical vapor deposition. Carbon ion implantation was pretreated for DLC and a-C films while Ti transition layer was pretreated for TiN film to strengthen the bonding strength. X-ray diffraction, Raman measurement, nano-hardness and nano-scratch tester, and cross-section etching by FIB method were used to analyze film characteristics. Tribological behaviors of these coatings were studied by articulation with both ZrO2 and UHMWPE balls using ball-on-disk sliding. The thickness values reached ~0.46, ~0.33, and ~1.67 μm for DLC, a-C, and TiN film, respectively. Nano-hardness of the coatings compared with that of untreated and bonding strength (critical load in nano-scratch test) values of composite coatings compared with that of monolayer film all increased significantly, respectively. Under destructive test (ZrO2 ball conterface) in bovine serum lubrication, TiN coating revealed the best wear resistance while DLC showed the worst. Film failure was mainly attributed to the plowing by hard ZrO2 ball characterized by abrasive and adhesive wear. Under normal test (UHMWPE ball conterface), all coatings showed significant improvement in wear resistance both in dry sliding and bovine serum lubrication. Both DLC and a-C films showed less surface damage than TiN film due to the self-lubricating phenomenon in dry sliding. TiN film showed the largest friction coefficient both in destructive and normal tests, devoting to the big TiN grains thus leading to much rougher surface and then a higher value. The self-lubricating film formed on DLC and a-C coating could also decrease their friction coefficients. The results indicated that three coatings revealed different wear mechanisms, and thick DLC or a-C film was more promising in application in lower stress conditions such as artificial cervical disk.

  16. SnS thin films deposited by chemical bath deposition, dip coating and SILAR techniques

    Science.gov (United States)

    Chaki, Sunil H.; Chaudhary, Mahesh D.; Deshpande, M. P.

    2016-05-01

    The SnS thin films were synthesized by chemical bath deposition (CBD), dip coating and successive ionic layer adsorption and reaction (SILAR) techniques. In them, the CBD thin films were deposited at two temperatures: ambient and 70 °C. The energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and optical spectroscopy techniques were used to characterize the thin films. The electrical transport properties studies on the as-deposited thin films were done by measuring the I-V characteristics, DC electrical resistivity variation with temperature and the room temperature Hall effect. The obtained results are deliberated in this paper.

  17. Biochemical Conversion: Using Enzymes, Microbes, and Catalysis to Make Fuels and Chemicals

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-07-26

    This fact sheet describes the Bioenergy Technologies Office's biochemical conversion work and processes. BETO conducts collaborative research, development, and demonstration projects to improve several processing routes for the conversion of cellulosic biomass.

  18. Influence of culture media on the physical and chemical properties of Ag-TiCN coatings

    Science.gov (United States)

    Carvalho, I.; Escobar Galindo, R.; Henriques, M.; Palacio, C.; Carvalho, S.

    2014-08-01

    The aim of this study was to verify the possible physical and chemical changes that may occur on the surface of Ag-TiCN coatings after exposure to the culture media used in microbiological and cytotoxic assays, respectively tryptic soy broth (TSB) and Dulbecco's modified eagle's medium (DMEM). After sample immersion for 24 h in the media, analyses were performed by glow discharge optical emission spectroscopy discharge radiation (GDOES), Rutherford backscattering spectroscopy (RBS) and x-ray photoelectron spectroscopy (XPS). The results of GDOES profile, RBS and XPS spectra, of samples immersed in TSB, demonstrated the formation of a thin layer of carbon, oxygen and nitrogen that could be due to the presence of proteins in TSB. After 24 h of immersion in DMEM, the results showed the formation of a thin layer of calcium phosphates on the surface, since the coatings displayed a highly oxidized surface in which calcium and phosphorus were detected. All these results suggested that the formation of a layer on the coating surface prevented the release of silver ions in concentrations that allow antibacterial activity.

  19. Status and perspectives of CO2 conversion into fuels and chemicals by catalytic, photocatalytic and electrocatalytic processes

    NARCIS (Netherlands)

    Kondratenko, E.V.; Mul, Guido; Baltrusaitis, Jonas; Larrazábal, G.O.; Pérez-Ramírez, J.

    2013-01-01

    This review highlights recent developments and future perspectives in carbon dioxide usage for the sustainable production of energy and chemicals and to reduce global warming. We discuss the heterogeneously catalysed hydrogenation, as well as the photocatalytic and electrocatalytic conversion of CO2

  20. Formation of a cerium conversion coating on magnesium alloy using ascorbic acid as additive. Characterisation and anticorrosive properties of the formed films

    OpenAIRE

    A.P. Loperena; I.L. Lehr; S.B. Saidman.

    2016-01-01

    Cerium-based conversion coatings were formed on AZ91D magnesium alloy by immersion of the substrate in solutions containing Ce(NO3)3, H2O2 and ascorbic acid (HAsc). The characterisation of the films was performed by electrochemical and surface analysis techniques such as SEM, EDS, X-ray diffraction and X-ray photoelectron spectroscopy (XPS). The degree of corrosion protection achieved was evaluated in simulated physiological solution by the open circuit potential monitoring, polarisation tech...

  1. Hydrothermal Conversion of Neutral Sulfite Semi-Chemical Red Liquor into Hydrochar

    Directory of Open Access Journals (Sweden)

    Ramy Gamgoum

    2016-06-01

    Full Text Available Hydrochar was produced from neutral sulfite semi-chemical (NSSC red liquor as a possible bio-based solid fuel for use in power generation facilities. Hydrothermal conversion (HTC experiments were conducted using a fixed liquor-to-water volume ratio of 1:8 and reaction time of 3 h. Solutions were processed using different chemical additives, pH and temperature conditions to determine the optimum conditions required for producing a high energy content solid fuel. The hydrochar samples produced were analyzed by ultimate, thermogravimetric (TGA and Fourier transform infrared spectroscopy (FTIR analyses to determine physicochemical properties that are important for utilization as a fuel. The residual process liquids were also analyzed to better understand the effect of HTC process conditions on their properties. It was determined that the optimum conditions for producing a solid fuel was at a reaction temperature of 250 °C, in the presence of acetic acid at pH 3. The maximum energy content (HHV of the hydrochar produced from red liquor at this condition was 29.87 MJ/kg, and its ash content was 1.12 wt.%. This result reflects the effect of increasing reaction temperature on the physicochemical characteristics of the hydrochar. The increase of HTC temperature significantly reduces the ash content of the hydrochar, leads to a significant increase in the carbon content of the hydrochar, and a reduction in both the oxygen and hydrogen content. These effects suggests an increase in the degree of condensation of the hydrochar products, and consequently the formation of a high energy content material. Based on TGA and FTIR analyses, hydrochars prepared at high HTC temperature showed lower adsorbed moisture, hemicellulose and cellulose contents, with enrichment in content of higher temperature volatiles, such as lignin.

  2. Microstructure and corrosion performance of steam-based conversion coatings produced in the presence of TiO2 particles on aluminium alloys

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Gudla, Visweswara Chakravarthy; Jellesen, Morten Stendahl

    2016-01-01

    The steam-based conversion coatings containing TiO2 particleswere prepared using a two-step process comprising of spin coating of particles onto an aluminiumsubstrate followed by a high-pressure steam treatment. Process has resulted in the formation of aluminium oxide layer (~1.3 μm thick) embedded...... to the coatings without TiO2 particles, while the shift in thepitting potential was a function of the steam treatment time and degree of particle incorporation into the oxide....... with TiO2 particles. The electrochemical measurements showthe beneficial effect of TiO2 particles in the oxide layer by exhibiting lowestanodic and cathodic activities, and reduced pit depth. The presence of TiO2 particles shifts the corrosion potentialvalues to positive side (noble side) when compared...

  3. Design of electrolyzer for carbon dioxide conversion to fuels and chemicals

    Science.gov (United States)

    Rosen, Jonathan S.

    The stabilization of global atmospheric CO2 levels requires a transition towards a renewable energy based economy as well as methods for handling current CO2 output from fossil fuels. Challenges with renewable energy intermittency have thus far limited the use of these alternative energy sources to only a fraction of the current energy portfolio. To enable more widespread use of renewable energy systems, methods of large scale energy storage must be developed to store excess renewable energy when demand is low and allow for combined use of energy storage and renewable systems when demand is high. To date, no one technique has demonstrated energy storage methods on the gigawatt scale needed for integration with renewable sources; therefore the development of suitable energy storage technologies, such as CO2 electrolysis to fuels is needed. In this work, research efforts have focused on two major thrusts related to electrochemical methods of CO 2 conversion to fuels. The first thrust focuses on the synthesis and design of highly efficient anode and cathode catalysts with emphasis on understanding structure-property relationships. A second thrust focuses on the design of novel electrochemical devices for CO2 conversion and integration of synthesized materials into flow cell systems. On the anode side, the synthesis of highly active catalysts using abundant transition metals is crucial to reducing capital costs and enabling widespread use of electrochemical CO2 conversion devices. Highly active mesoporous Co3O4 and metal-substituted Co3O4 water oxidation catalysts were designed to investigate the role of the spinel structure on water oxidation activity. Further analysis of metal substituted samples reveal the importance of the octahedral sites in the spinel structure, which was later used to design an Mg-Co3O4 sample with improved water oxidation activity. The design of efficient cathode materials which can selectivity reduce CO2 to fuels and chemicals is critical to

  4. Catalytic conversion of biomass pyrolysis-derived compounds with chemical liquid deposition (CLD) modified ZSM-5.

    Science.gov (United States)

    Zhang, Huiyan; Luo, Mengmeng; Xiao, Rui; Shao, Shanshan; Jin, Baosheng; Xiao, Guomin; Zhao, Ming; Liang, Junyu

    2014-03-01

    Chemical liquid deposition (CLD) with KH550, TEOS and methyl silicone oil as the modifiers was used to modify ZSM-5 and deposit its external acid sites. The characteristics of modified catalysts were tested by catalytic conversion of biomass pyrolysis-derived compounds. The effects of different modifying conditions (deposited amount, temperature, and time) on the product yields and selectivities were investigated. The results show KH550 modified ZSM-5 (deposited amount of 4%, temperature of 20°C and time of 6h) produced the maximum yields of aromatics (24.5%) and olefins (16.5%), which are much higher than that obtained with original ZSM-5 catalyst (18.8% aromatics and 9.8% olefins). The coke yield decreased from 44.1% with original ZSM-5 to 26.7% with KH550 modified ZSM-5. The selectivities of low-molecule-weight hydrocarbons (ethylene and benzene) decreased, while that of higher molecule-weight hydrocarbons (propylene, butylene, toluene, and naphthalene) increased comparing with original ZSM-5. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Surface-dependent chemical equilibrium constants and capacitances for bare and 3-cyanopropyldimethylchlorosilane coated silica nanochannels.

    Science.gov (United States)

    Andersen, Mathias Bækbo; Frey, Jared; Pennathur, Sumita; Bruus, Henrik

    2011-01-01

    We present a combined theoretical and experimental analysis of the solid-liquid interface of fused-silica nanofabricated channels with and without a hydrophilic 3-cyanopropyldimethylchlorosilane (cyanosilane) coating. We develop a model that relaxes the assumption that the surface parameters C(1), C(2), and pK(+) are constant and independent of surface composition. Our theoretical model consists of three parts: (i) a chemical equilibrium model of the bare or coated wall, (ii) a chemical equilibrium model of the buffered bulk electrolyte, and (iii) a self-consistent Gouy-Chapman-Stern triple-layer model of the electrochemical double layer coupling these two equilibrium models. To validate our model, we used both pH-sensitive dye-based capillary filling experiments as well as electro-osmotic current-monitoring measurements. Using our model we predict the dependence of ζ potential, surface charge density, and capillary filling length ratio on ionic strength for different surface compositions, which can be difficult to achieve otherwise. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. Carbon coated (carbonous) catalyst in ebullated bed reactor for production of oxygenated chemicals from syngas/CO2

    International Nuclear Information System (INIS)

    Peizheng Zhou

    2002-01-01

    This report summarizes the work completed under DOE's Support of Advanced Fuel Research program, Contract No. DE-FG26-99FT40681. The contract period was October 2000 through September 2002. This R and D program investigated the modification of the mechanical strength of catalyst extrudates using Hydrocarbon Technologies, Inc. (HTI) carbon-coated catalyst technology so that the ebullated bed technology can be utilized to produce valuable oxygenated chemicals from syngas/CO 2 efficiently and economically. Exothermic chemical reactions benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. The carbon-coated extrudates prepared using these procedures had sufficient attrition resistance and surface area for use in ebullated bed operation. The low cost of carbon coating makes the carbon-coated catalysts highly competitive in the market of catalyst extrudates

  7. Chemical stability and osteogenic activity of plasma-sprayed boron-modified calcium silicate-based coatings.

    Science.gov (United States)

    Lu, Xiang; Li, Kai; Xie, Youtao; Huang, Liping; Zheng, Xuebin

    2016-11-01

    In recent years, CaSiO 3 bio-ceramic coatings have attracted great attention because of their good bioactivity. However, their high degradation rates in physiological environment restrict their practical applications. In this work, boron-modified CaSiO 3 ceramic (Ca 11 Si 4 B 2 O 22 , B-CS) coating was developed on Ti substrates by plasma-spraying technique attempting to obtain enhanced chemical stability and osteogenic activity. The B-CS coating possessed significantly increased chemical stability due to the introduction of boron and consequently the modified crystal structure, while maintaining good bioactivity. Scanning electron microscope and immunofluorescence studies showed that better cellular adhesion and extinctive filopodia-like processes were observed on the B-CS coating. Compared with the pure CaSiO 3 (CS) coating, the B-CS coating promoted MC3T3-E1 cells attachment and proliferation. In addition, enhanced collagen I (COL-I) secretion, alkaline phosphatase activity, and extracellular matrix mineralization levels were detected from the B-CS coating. According to RT-PCR results, notable up-regulation expressions of mineralized tissue-related genes, such as runt-related transcription factor 2 (Runx2), bone sialoprotein and osteocalcin, and bone morphogenetic protein 7 (BMP-7) were observed on the B-CS coating compared with the CS coating. The above results suggested that Ca 11 Si 4 B 2 O 22 coatings possess excellent osteogenic activity and might be a promising candidate for orthopedic applications.

  8. boron nitride coating of uranium dioxide and uranium dioxide-gadolinium oxide fuels by chemical precipitation method

    International Nuclear Information System (INIS)

    Uslu, I.; Tanker, E.; Guenduez, G.

    1997-01-01

    In this research pure urania and urania-gadolinia (5 and 10 %) fuels were coated with boron nitride (BN). This is achieved through chemical vapor deposition (CVD) using boron tricloride BCl 3 ) and ammonia (NH 3 ) at 600 C.Boron tricloride and ammonia are carried to tubular furnace using hydrogen as carrier gas. The coated samples were sintered at 1600 K. The properties of the coated samples were observed using BET surface area analysis, infrared spectra (IR), X-Ray Diffraction and Scanning Electron Microscope (SEM) techniques

  9. Properties of plasma assisted chemical vapor deposited coatings of titanium boride on Ti--6Al--4V alloy substrates

    International Nuclear Information System (INIS)

    Otter, F.A.; Amisola, G.B.; Roman, W.C.; Hay, S.O.

    1992-01-01

    Coatings prepared in a radio-frequency-plasma (plasma assisted chemical vapor deposition) reactor employing in situ laser diagnostics have been tested and characterized. Detailed characterization studies are important to relate gas phase laser diagnostic studies and concurrent heterogeneous modeling efforts to coating characteristics. Establishing how deposition conditions are correlated with coating properties is expected to provide needed methodology for scale up of applications in the hard face protective coating area. After a brief discussion of preparation conditions and mechanical test results, we present results of chemical and physical measurements on these coatings. Measurement techniques include x-ray diffraction, Dektak surface roughness, scanning tunneling microscopy, scanning electron microscopy, and SEI, Auger electron spectroscopy, x-ray photoelectron spectroscopy, and Rutherford backscattering spectroscopy. The coatings (∼20 μm thick) are very hard (40 GPa at depths over 100 nm), adherent (60 N on scratch test), and sand erosion resistant (>40x as durable as Ti-6Al-4V). They are highly oriented with the c axis (hexagonal-close-packed) normal to the coating surface, rough (∼1 μm), and off-stoichiometry (TiB 2.2 )

  10. Fabrication and properties of iron-based soft magnetic composites coated with parylene via chemical vapor deposition polymerization

    International Nuclear Information System (INIS)

    Wu, Shen; Sun, Aizhi; Lu, Zhenwen; Cheng, Chuan

    2015-01-01

    This paper focuses on novel iron-based soft magnetic composites synthesis utilizing low friction factor parylene C films to coat iron powder via chemical vapor deposition polymerization. The morphology, magnetic properties, density, and chemical stability of parylene insulated iron particles were investigated. The coated parylene insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. The thickness of parylene C film is averagely 300 nm according to the results of transmission electron microscopy. Parylene C film uniformly coated the powder surface resulting in reducing the permeability imaginary part, increasing electrical resistivity and increasing the operating frequency of the synthesized magnets. It was shown that the parylene C coated compacts exhibited noticeably higher density compared to the epoxy resin coated compacts at the same pressure, suppress at 800 MPa increased the density by 17.02%. The result of Tafel curves indicated that the resistance of the iron particles to corrosion by NaCl solution is obviously improved after being insulated with parylene C film. - Highlights: • Parylene C uniformly coated the powder, increased the operating frequency of SMCs. • Compared with epoxy coated, the density of SMCs increased by 17.02% at 800 MPa. • The resistance of the iron particles is obviously improved with parylene film insulated

  11. Chemical treatment and biomimetic coating evaluating in zirconia-alumina ceramics

    International Nuclear Information System (INIS)

    Aguiar, Amanda Abati

    2007-01-01

    Ceramic materials, as alumina and zirconia have been explored along the years as biomaterials application. The bio inert nature has been stimulating the development of new alternatives, as chemical treatments to improve the biological application of these ceramics. The biomimetic process of bio inert ceramics for coating apatite is based on soaking the implant in a simulated body fluid, SBF, with ion concentrations nearly equal to those of human blood plasma. The bioactivity of the material is related with the formation of a layer constituted of hydroxyapatite low crystalline, similar to the biological apatite. The biocompatibility associated to the structural properties of the alumina and zirconia has been stimulating the clinical use of these materials, mainly in areas of larger mechanical requests, places not recommended for bioactive hydroxyapatite, for instance. In this work samples of alumina, zirconia doped with Yttria (3% mol) and composites of alumina and zirconia doped with Yttria (3% mol) were prepared by co-precipitation method, calcinate, sintered, chemically treated with solutions of acid phosphoric and sodium hydroxide and them immersed in 1.0 M and 1.5 M SBF. The calcinate powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), gas adsorption (BET) and laser diffraction. The XRD results indicate that the samples are low crystalline. It was observed for BET that the samples present high specific surface area. The results of laser diffraction and SEM showed that the powders are agglomerates. The sintered samples were analyzed by XRD, SEM and X-ray fluorescence (XRF). The phases quantified by Rietveld method were: cubic, tetragonal and monoclinic of the zirconia, besides the phase alpha of the alumina. The chemical treatment with phosphoric acid didn't present a tendency of larger apatite formation in relation to the samples no chemically treated. The treatment with sodium hydroxide provoked accentuated transformation of

  12. Microstructure, chemical states, and mechanical properties of V–C–Co coatings prepared by non-reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Zhang, Xiaojuan; Wang, Bo; Zhan, Zhaolin; Huang, Feng

    2013-01-01

    V–C–Co coatings have been prepared by non-reactive magnetron co-sputtering from VC and Co targets. The microstructure, chemical states, and mechanical properties are examined as a function of Co content in the coatings. The coatings are dense, with columnar growth structures. High resolution transmission electron microscopy (HRTEM) studies identify a nanocomposite microstructure for the 12.4 at.% Co coating, in which ligament-like Co-rich regions partially separate the nanocrystalline VC grains. X-ray photoelectron spectroscopy studies reveal a noticeable charge transfer from Co 2p states to C 1s states. This charge transfer, in addition to the ligament-like Co-rich regions as revealed by HRTEM, points to the formation of a strong Co/VC interface. The nanoindentation hardness of the coatings drops steadily with the Co content, from 29 GPa for pure VC to ∼ 21 GPa for the 12.4 at.% Co coating. Meanwhile, the plasticity characteristic increased from 0.42 to 0.53. - Highlights: • Nanocomposite V–C–Co coatings with strong Co/VC interfaces were formed. • Found nanocrystalline VC grains separated by ∼ 1 nm thin Co-rich ligaments. • A noticeable amount of C-Co bonds between VC and Co is identified. • V–C–Co coatings exhibited a higher plasticity characteristic than VC

  13. Microstructure, chemical states, and mechanical properties of V–C–Co coatings prepared by non-reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaojuan [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650000 (China); Wang, Bo [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhan, Zhaolin [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650000 (China); Huang, Feng, E-mail: huangfeng@nimte.ac.cn [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China)

    2013-07-01

    V–C–Co coatings have been prepared by non-reactive magnetron co-sputtering from VC and Co targets. The microstructure, chemical states, and mechanical properties are examined as a function of Co content in the coatings. The coatings are dense, with columnar growth structures. High resolution transmission electron microscopy (HRTEM) studies identify a nanocomposite microstructure for the 12.4 at.% Co coating, in which ligament-like Co-rich regions partially separate the nanocrystalline VC grains. X-ray photoelectron spectroscopy studies reveal a noticeable charge transfer from Co 2p states to C 1s states. This charge transfer, in addition to the ligament-like Co-rich regions as revealed by HRTEM, points to the formation of a strong Co/VC interface. The nanoindentation hardness of the coatings drops steadily with the Co content, from 29 GPa for pure VC to ∼ 21 GPa for the 12.4 at.% Co coating. Meanwhile, the plasticity characteristic increased from 0.42 to 0.53. - Highlights: • Nanocomposite V–C–Co coatings with strong Co/VC interfaces were formed. • Found nanocrystalline VC grains separated by ∼ 1 nm thin Co-rich ligaments. • A noticeable amount of C-Co bonds between VC and Co is identified. • V–C–Co coatings exhibited a higher plasticity characteristic than VC.

  14. Characteristics and corrosion studies of vanadate conversion coating formed on Mg–14 wt%Li–1 wt%Al–0.1 wt%Ce alloy

    International Nuclear Information System (INIS)

    Ma Yibin; Li Ning; Li Deyu; Zhang Milin; Huang Xiaomei

    2012-01-01

    Highlights: ► Vanadate film forms on the surface of Mg–Li–Al–Ce alloy. ► Vanadate coating improves the corrosion resistance. ► Vanadate coating is composed of Mg(OH) 2 , Li 2 O and V 2 O 5 . - Abstract: Mg–14Li–1Al–0.1Ce alloy is immersed in NH 4 VO 3 + K 3 (Fe(CN) 6 ) solutions with different NH 4 VO 3 and/or K 3 (Fe(CN) 6 ) concentrations, and different immersion time. The surface morphology and composition of the vanadate coating are then characterized by scanning electron microscopy with energy dispersion spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), and the corrosion behavior of the conversion coating is studied by polarization technique and electrochemical impedance spectroscopy (EIS). The experimental results indicate that the vanadate film with better corrosion resistance forms on Mg–Li–Al–Ce surface after the sample is immersed in 30 g L −1 NH 4 VO 3 + 3.75 g L −1 K 3 (Fe(CN) 6 ) solution at 80 °C for 10 min. The coating consists of V 2 O 5 , Li 2 O and Mg(OH) 2 .

  15. Characteristics and corrosion studies of vanadate conversion coating formed on Mg-14 wt%Li-1 wt%Al-0.1 wt%Ce alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ma Yibin [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Li Ning, E-mail: lininghit@263.net [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Li Deyu [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Zhang Milin; Huang Xiaomei [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Vanadate film forms on the surface of Mg-Li-Al-Ce alloy. Black-Right-Pointing-Pointer Vanadate coating improves the corrosion resistance. Black-Right-Pointing-Pointer Vanadate coating is composed of Mg(OH){sub 2}, Li{sub 2}O and V{sub 2}O{sub 5}. - Abstract: Mg-14Li-1Al-0.1Ce alloy is immersed in NH{sub 4}VO{sub 3} + K{sub 3}(Fe(CN){sub 6}) solutions with different NH{sub 4}VO{sub 3} and/or K{sub 3}(Fe(CN){sub 6}) concentrations, and different immersion time. The surface morphology and composition of the vanadate coating are then characterized by scanning electron microscopy with energy dispersion spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), and the corrosion behavior of the conversion coating is studied by polarization technique and electrochemical impedance spectroscopy (EIS). The experimental results indicate that the vanadate film with better corrosion resistance forms on Mg-Li-Al-Ce surface after the sample is immersed in 30 g L{sup -1} NH{sub 4}VO{sub 3} + 3.75 g L{sup -1} K{sub 3}(Fe(CN){sub 6}) solution at 80 Degree-Sign C for 10 min. The coating consists of V{sub 2}O{sub 5}, Li{sub 2}O and Mg(OH){sub 2}.

  16. Symposium on the Physical Chemistry of Solar Energy Conversion, Indianapolis American Chemical Society Meetings, Fall 2013

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Tianquan [PI, Emory Univ.

    2013-09-20

    The Symposium on the Physical Chemistry of Solar Energy Conversion at the Fall ACS Meeting in Indianapolis, IN (Sept. 8-12) featured the following sessions (approx. 6 speakers per session): (1) Quantum Dots and Nanorods for Solar Energy Conversion (2 half-day sessions); (2) Artificial Photosynthesis: Water Oxidation; (3) Artificial Photosynthesis: Solar Fuels (2 half-day sessions); (4) Organic Solar Cells; (5) Novel Concepts for Solar Energy Conversion (2 half-day sessions); (6) Emerging Techniques for Solar Energy Conversion; (7) Interfacial Electron Transfer

  17. Chemical state analysis of oxidation products on steel surface by conversion electron Moessbauer spectrometry

    International Nuclear Information System (INIS)

    Ujihira, Yusuke; Nomura, Kiyoshi

    1978-01-01

    The polished NT-70H steel (Fe: 95.97%, C: 0.56%, diameter: 5 cm, thickness: 0.5 cm) was immersed in deionized water or in solutions containing (0.25 -- 0.5) M of chloride, sulfate and nitrate ions. The chemical states of oxidation products of iron on the surface were identified through the analysis of conversion electron Moessbauer spectra (CEMS). CEMS of the steel surface, which had been dipped in deionized water, revealed that γ-FeOOH was formed on the surface. The thickness of γ-FeOOH layer increased with the increase of the duration of dipping. Dissolved oxygen in the solution played an essential role in the oxidation of iron to γ-FeOOH. Oxidation product of iron dipped in the 0.5 M sodium chloride solution was identified as γ-FeOOH. Amorphous paramagnetic iron (III) compound tended to form in the presence of hydrogen peroxide or ammonium ions in the solutions. The increase of alkalinity of the solution up to pH 12 suppressed the oxidation rate and assisted the formation of green rust, which was confirmed by the appearance of the quadrupole splitting peaks of the green rust. In the 0.25 M sodium sulfate solution, oxidation of the steel surface proceeded slowly and the quadrupole splitting peaks of Fe(OH) 2 were seen in the CEMS. The peak intensity of Fe(OH) 2 gradually decreased and that of γ-FeOOH increased by the extension of immersion of steel in the solution. Magnetite (Fe 3 O 4 ) layer was developed beneath the γ-FeOOH layer, when steel was dipped in 0.5 M sodium nitrate solution. However, the peaks of Fe 3 O 4 were not seen on CEMS of steel surface immersed in 0.5 M ammonium nitrate solution. Thus, applying the feasibility of CEMS for the characterization of oxidated compounds of iron on the steel surface formed by the immersion in solutions, the oxidation mechanism of the steel surface was discussed based upon the results of chemical state analyses. (author)

  18. Tantalum coating on porous Ti6Al4V scaffold using chemical vapor deposition and preliminary biological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiang, E-mail: xiangliwj@sjtu.edu.cn [School of Mechanical Engineering, Shanghai Jiao Tong University, State Key Laboratory of Mechanical System and Vibration, Shanghai, 200240 (China); Wang, Lin [Institute of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi' an, 710032 (China); Yu, Xiaoming [The Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016 (China); Feng, Yafei [Institute of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi' an, 710032 (China); Wang, Chengtao [School of Mechanical Engineering, Shanghai Jiao Tong University, State Key Laboratory of Mechanical System and Vibration, Shanghai, 200240 (China); Yang, Ke [The Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016 (China); Su, Daniel [School of Mechanical Engineering, Shanghai Jiao Tong University, State Key Laboratory of Mechanical System and Vibration, Shanghai, 200240 (China)

    2013-07-01

    Porous tantalum (Ta), produced via chemical vapor deposition (CVD) of commercially pure Ta onto a vitreous carbon, is currently available for use in orthopedic applications. However, the relatively high manufacturing cost and the incapability to produce customized implant using medical image data have limited its application to gain widespread acceptance. In this study, Ta film was deposited on porous Ti6Al4V scaffolds using CVD technique. Digital microscopy and scanning electron microscopy indicated that the Ta coating evenly covered the entire scaffold structure. X-ray diffraction analysis showed that the coating consisted of α and β phases of Ta. Goat mesenchymal stem cells were seeded and cultured on the Ti6Al4V scaffolds with and without coating. The tetrazolium-based colorimetric assay exhibited better cell adhesion and proliferation on Ta-coated scaffolds compared with uncoated scaffolds. The porous scaffolds were subsequently implanted in goats for 12 weeks. Histological analysis revealed similar bone formation around the periphery of the coated and uncoated implants, but bone ingrowth is better within the Ta-coated scaffolds. To demonstrate the ability of producing custom implant for clinical applications via this technology, we designed and fabricated a porous Ti6Al4V scaffold with segmental mandibular shape derived from patient computerized tomography data. - Highlights: • Ta film was coated on porous Ti6Al4V scaffold using chemical vapor deposition. • Tantalum coating allowed for higher levels of cell adhesion and proliferation. • Better new bone formation occurred inside the tantalum-coated scaffolds. • Clinical image data was integrated with EBM to fabricate customized scaffold.

  19. Tantalum coating on porous Ti6Al4V scaffold using chemical vapor deposition and preliminary biological evaluation

    International Nuclear Information System (INIS)

    Li, Xiang; Wang, Lin; Yu, Xiaoming; Feng, Yafei; Wang, Chengtao; Yang, Ke; Su, Daniel

    2013-01-01

    Porous tantalum (Ta), produced via chemical vapor deposition (CVD) of commercially pure Ta onto a vitreous carbon, is currently available for use in orthopedic applications. However, the relatively high manufacturing cost and the incapability to produce customized implant using medical image data have limited its application to gain widespread acceptance. In this study, Ta film was deposited on porous Ti6Al4V scaffolds using CVD technique. Digital microscopy and scanning electron microscopy indicated that the Ta coating evenly covered the entire scaffold structure. X-ray diffraction analysis showed that the coating consisted of α and β phases of Ta. Goat mesenchymal stem cells were seeded and cultured on the Ti6Al4V scaffolds with and without coating. The tetrazolium-based colorimetric assay exhibited better cell adhesion and proliferation on Ta-coated scaffolds compared with uncoated scaffolds. The porous scaffolds were subsequently implanted in goats for 12 weeks. Histological analysis revealed similar bone formation around the periphery of the coated and uncoated implants, but bone ingrowth is better within the Ta-coated scaffolds. To demonstrate the ability of producing custom implant for clinical applications via this technology, we designed and fabricated a porous Ti6Al4V scaffold with segmental mandibular shape derived from patient computerized tomography data. - Highlights: • Ta film was coated on porous Ti6Al4V scaffold using chemical vapor deposition. • Tantalum coating allowed for higher levels of cell adhesion and proliferation. • Better new bone formation occurred inside the tantalum-coated scaffolds. • Clinical image data was integrated with EBM to fabricate customized scaffold

  20. Chemical and Morphological Characterization of Magnetron Sputtered at Different Bias Voltages Cr-Al-C Coatings

    Directory of Open Access Journals (Sweden)

    Aleksei Obrosov

    2017-02-01

    Full Text Available MAX phases (M = transition metal, A = A-group element, and X = C/N are of special interest because they possess a unique combination of the advantages of both metals and ceramics. Most attention is attracted to the ternary carbide Cr2AlC because of its excellent high-temperature oxidation, as well as hot corrosion resistance. Despite lots of publications, up to now the influence of bias voltage on the chemical bonding structure, surface morphology, and mechanical properties of the film is still not well understood. In the current study, Cr-Al-C films were deposited on silicon wafers (100 and Inconel 718 super alloy by dc magnetron sputtering with different substrate bias voltages and investigated using Scanning Electron Microscopy (SEM, X-ray Photoelectron Spectroscopy (XPS, X-ray Diffraction (XRD, Atomic Force Microscopy (AFM, and nanoindentation. Transmission Electron Microscopy (TEM was used to analyze the correlation between the growth of the films and the coating microstructure. The XPS results confirm the presence of Cr2AlC MAX phase due to a negative shift of 0.6–0.9 eV of the Al2p to pure aluminum carbide peak. The XRD results reveal the presence of Cr2AlC MAX Phase and carbide phases, as well as intermetallic AlCr2. The film thickness decreases from 8.95 to 6.98 µm with increasing bias voltage. The coatings deposited at 90 V exhibit the lowest roughness (33 nm and granular size (76 nm combined with the highest hardness (15.9 GPa. The ratio of Al carbide to carbide-like carbon state changes from 0.12 to 0.22 and correlates with the mechanical properties of the coatings. TEM confirms the columnar structure, with a nanocrystalline substructure, of the films.

  1. Co3O4 protective coatings prepared by Pulsed Injection Metal Organic Chemical Vapour Deposition

    DEFF Research Database (Denmark)

    Burriel, M.; Garcia, G.; Santiso, J.

    2005-01-01

    of deposition temperature. Pure Co3O4 spinel structure was found for deposition temperatures ranging from 360 to 540 degreesC. The optimum experimental parameters to prepare dense layers with a high growth rate were determined and used to prepare corrosion protective coatings for Fe-22Cr metallic interconnects......Cobalt oxide films were grown by Pulsed Injection Metal Organic Chemical Vapour Deposition (PI-MOCVD) using Co(acac)(3) (acac=acetylacetonate) precursor dissolved in toluene. The structure, morphology and growth rate of the layers deposited on silicon substrates were studied as a function......, to be used in Intermediate Temperature Solid Oxide Fuel Cells. (C) 2004 Elsevier B.V. All rights reserved....

  2. 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.

  3. Self-healing Li-Al layered double hydroxide conversion coating modified with aspartic acid for 6N01 Al alloy

    Science.gov (United States)

    Zhang, Caixia; Luo, Xiaohu; Pan, Xinyu; Liao, Liying; Wu, Xiaosong; Liu, Yali

    2017-02-01

    A self-healing Li-Al layered double hydroxide conversion coating (LCC) modified with aspartic acid (ALCC) was prepared on 6N01 Al alloy for corrosion protection. Scanning electron microscopy (SEM) showed that a compact thin film has been successfully formed on the alloy. X-ray diffraction (XRD) and FT-IR spectra proved that species of aspartic acid anions were successfully intercalated into LCC. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) testing showed that the resultant ALCC could provide effective corrosion protection for the Al alloy. During immersion of the ALCC-coated alloy in 3.5% NaCl solution, new film was formed in the area of artificially introduced scratch, indicating its self-healing capability. XPS results demonstrated that Cl- anions exchange partial Asp anions according to the change content of element on conversion coating. From the above results, the possible mechanism via exchange/self-assembly was proposed to illustrate the phenomenon of self-healing.

  4. Conversion of carbon dioxide to value-added chemicals in atmospheric pressure dielectric barrier discharges

    International Nuclear Information System (INIS)

    Paulussen, Sabine; Verheyde, Bert; Tu Xin; Sels, Bert; De Bie, Christophe; Martens, Tom; Petrovic, Dragana; Bogaerts, Annemie

    2010-01-01

    The aim of this work consists of the evaluation of atmospheric pressure dielectric barrier discharges for the conversion of greenhouse gases into useful compounds. Therefore, pure CO 2 feed flows are administered to the discharge zone at varying discharge frequency, power input, gas temperature and feed flow rates, aiming at the formation of CO and O 2 . The discharge obtained in CO 2 is characterized as a filamentary mode with a microdischarge zone in each half cycle of the applied voltage. It is shown that the most important parameter affecting the CO 2 -conversion levels is the gas flow rate. At low flow rates, both the conversion and the CO-yield are significantly higher. In addition, also an increase in the gas temperature and the power input give rise to higher conversion levels, although the effect on the CO-yield is limited. The optimum discharge frequency depends on the power input level and it cannot be unambiguously stated that higher frequencies give rise to increased conversion levels. A maximum CO 2 conversion of 30% is achieved at a flow rate of 0.05 L min -1 , a power density of 14.75 W cm -3 and a frequency of 60 kHz. The most energy efficient conversions are achieved at a flow rate of 0.2 L min -1 , a power density of 11 W cm -3 and a discharge frequency of 30 kHz.

  5. Super-adiabatic combustion in Al2O3 and SiC coated porous media for thermoelectric power conversion

    International Nuclear Information System (INIS)

    Mueller, Kyle T.; Waters, Oliver; Bubnovich, Valeri; Orlovskaya, Nina; Chen, Ruey-Hung

    2013-01-01

    The combustion of ultra-lean fuel/air mixtures provides an efficient way to convert the chemical energy of hydrocarbons and low-calorific fuels into useful power. Matrix-stabilized porous medium combustion is an advanced technique in which a solid porous medium within the combustion chamber conducts heat from the hot gaseous products in the upstream direction to preheat incoming reactants. This heat recirculation extends the standard flammability limits, allowing the burning of ultra-lean and low-calorific fuel mixtures and resulting a combustion temperature higher than the thermodynamic equilibrium temperature of the mixture (i.e., super-adiabatic combustion). The heat generated by this combustion process can be converted into electricity with thermoelectric generators, which is the goal of this study. The design of a porous media burner coupled with a thermoelectric generator and its testing are presented. The combustion zone media was a highly-porous alumina matrix interposed between upstream and downstream honeycomb structures with pore sizes smaller than the flame quenching distance, preventing the flame from propagating outside of the central section. Experimental results include temperature distributions inside the combustion chamber and across a thermoelectric generator; along with associated current, voltage and power output values. Measurements were obtained for a catalytically inert Al 2 O 3 medium and a SiC coated medium, which was tested for the ability to catalyze the super-adiabatic combustion. The combustion efficiency was obtained for stoichiometric and ultra-lean (near the lean flammability limit) mixtures of CH 4 and air. - Highlights: • Design of a porous burner coupled with a thermoelectric module. • Super-adiabatic combustion in a highly-porous ceramic matrix was investigated. • Both alumina and silicon carbide ceramic surfaces were used as porous media. • Catalytic properties of Al 2 O 3 and SiC ceramic surfaces were studied

  6. Evaluation of corrosion behaviour of tantalum coating obtained by low pressure chemical vapor deposition using electrochemical polarization

    Science.gov (United States)

    Levesque, A.; Bouteville, A.; de Baynast, H.; Laveissière, B.

    2002-06-01

    antalum coatings are elaborated on titanium substrates through Low Pressure Chemical Vapor Deposition from tantalum pentachloride-hydrogen gaseous phase at a deposition temperature of 800 °C and a total pressure of 3.3 mbar. The aim of this paper is to evaluate the effectiveness of this tantalum coating in corrosive solution. Optical Microscopy and Scanning Electron Microscopy observations reveal that deposits are of 1.7 μm in thickness and conformal. The corrosion resistance of tantalum coated titanium substrates is quantified through standard potentiodynamic polarization method. Even for tantalum coatings exhibiting some defects as pores, the corrosion current density is as low as 0.25 mA/cm^2.in very agressive solutions like kroll reagent (HN03/HF).

  7. Magnesium carbide synthesis from methane and magnesium oxide - a potential methodology for natural gas conversion to premium fuels and chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, A.F.; Modestino, A.J.; Howard, J.B. [Massachusetts Institute of Technology, Cambridge, MA (United States)] [and others

    1995-12-31

    Diversification of the raw materials base for manufacturing premium fuels and chemicals offers U.S. and international consumers economic and strategic benefits. Extensive reserves of natural gas in the world provide a valuable source of clean gaseous fuel and chemical feedstock. Assuming the availability of suitable conversion processes, natural gas offers the prospect of improving flexibility in liquid fuels and chemicals manufacture, and thus, the opportunity to complement, supplement, or displace petroleum-based production as economic and strategic considerations require. The composition of natural gas varies from reservoir to reservoir but the principal hydrocarbon constituent is always methane (CH{sub 4}). With its high hydrogen-to-carbon ratio, methane has the potential to produce hydrogen or hydrogen-rich products. However, methane is a very chemically stable molecule and, thus, is not readily transformed to other molecules or easily reformed to its elements (H{sub 2} and carbon). In many cases, further research is needed to augment selectivity to desired product(s), increase single-pass conversions, or improve economics (e.g. there have been estimates of $50/bbl or more for liquid products) before the full potential of these methodologies can be realized on a commercial scale. With the trade-off between gas conversion and product selectivity, a major challenge common to many of these technologies is to simultaneously achieve high methane single-pass conversions and high selectivity to desired products. Based on the results of the scoping runs, there appears to be strong indications that a breakthrough has finally been achieved in that synthesis of magnesium carbides from MgO and methane in the arc discharge reactor has been demonstrated.

  8. Atomic Layer Deposition of Chemical Passivation Layers and High Performance Anti-Reflection Coatings on Back-Illuminated Detectors

    Science.gov (United States)

    Hoenk, Michael E. (Inventor); Greer, Frank (Inventor); Nikzad, Shouleh (Inventor)

    2014-01-01

    A back-illuminated silicon photodetector has a layer of Al2O3 deposited on a silicon oxide surface that receives electromagnetic radiation to be detected. The Al2O3 layer has an antireflection coating deposited thereon. The Al2O3 layer provides a chemically resistant separation layer between the silicon oxide surface and the antireflection coating. The Al2O3 layer is thin enough that it is optically innocuous. Under deep ultraviolet radiation, the silicon oxide layer and the antireflection coating do not interact chemically. In one embodiment, the silicon photodetector has a delta-doped layer near (within a few nanometers of) the silicon oxide surface. The Al2O3 layer is expected to provide similar protection for doped layers fabricated using other methods, such as MBE, ion implantation and CVD deposition.

  9. Thermochemical Conversion of Lignin for Fuels and Chemicals: A Review Conversion thermochimique de la lignine en carburants et produits chimiques : une revue

    Directory of Open Access Journals (Sweden)

    Joffres B.

    2013-10-01

    Full Text Available Lignin is one of the biomass components potentially usable as renewable resource to produce fuels or chemicals. After separation from the lignocellulosic matrix, this macromolecule is nowadays essentially valorized by combustion in paper mills. If second generation ethanol is produced in the future from lignocellulosic biomass, some increasing reserves of lignin will be available in addition to the ones coming from the paper industry. The main thermochemical ways such as pyrolysis, solvolysis, hydrothermal conversion and hydroconversion considered for the valorization of the lignin are reviewed in this article. La lignine est une des composantes de la biomasse lignocellulosique potentiellement valorisable comme ressource renouvelable pour la production de carburants ou de produits chimiques. Après séparation de la matrice lignocellulosique, cette macromolécule est de nos jours essentiellement utilisée comme combustible dans l’industrie papetière. Outre cette filière papetière, la production d’éthanol de seconde génération à partir de la cellulose aura comme conséquence la mise à disponibilité d’encore plus grandes quantités de lignine. De nouvelles applications pourront donc être proposées pour l’utilisation de cette bio-ressource. Les différentes voies thermochimiques : pyrolyse, solvolyse, conversion hydrothermale et hydroconversion envisagées pour la valorisation de la lignine sont décrites dans cet article.

  10. Nanostructured Semiconductor Electrodes for Solar Energy Conversion and Innovations in Undergraduate Chemical Lab Curriculum

    Science.gov (United States)

    Lee, Sudarat

    This dissertation presents the methodology and discussion of preparing nanostructured, high aspect ratio p-type phosphide-based binary and ternary semiconductors via "top-down" anodic etching, a process which creates nanostructures from a large parent entity, and "bottom-up" vapor-liquid-solid growth, a mechanism which builds up small clusters of molecules block-by-block. Such architecture is particularly useful for semiconducting materials with incompatible optical absorption depth and charge carrier diffusion length, as it not only relaxes the requirement for high-grade crystalline materials, but also increases the carrier collection efficiencies for photons with energy greater than or equal to the band gap. The main focus of this dissertation is to obtain nanostructured p-type phosphide semiconductors for photoelectrochemical (PEC) cell applications. Chapter II in the thesis describes a methodology for creating high-aspect ratio p-GaP that function as a photocathode under white light illumination. Gallium phosphide (GaP, band gap: 2.26 eV) is a suitable candidate for solar conversion and energy storage due to its ability to generate large photocurrent and photovoltage to drive fuel-forming reactions. Furthermore, the band edge positions of GaP can provide sufficient kinetics for the reduction of protons and carbon dioxide. The structure is prepared by anodic etching, and the resulting macroporous structures are subsequently doped with Zn by thermally driving in Zn from conformal ZnO films prepared by atomic layer deposition (ALD). The key finding of this work is a viable doping strategy involving ALD ZnO films for making functioning p-type GaP nanostructures. Chapter III compares the GaP nanowires grown from gold (Au) and tin (Sn) VLS catalysts in a benign solid sublimation growth scheme in terms of crystal structure and photoactivity. Sn is less noble than Au, allowing complete removal of Sn metal catalysts from the nanowires through wet chemical etching which

  11. DMF as an Additive in a Two-Step Spin-Coating Method for 20% Conversion Efficiency in Perovskite Solar Cells.

    Science.gov (United States)

    Wu, Jionghua; Xu, Xin; Zhao, Yanhong; Shi, Jiangjian; Xu, Yuzhuan; Luo, Yanhong; Li, Dongmei; Wu, Huijue; Meng, Qingbo

    2017-08-16

    DMF as an additive has been employed in FAI/MAI/IPA (FA= CH 2 (NH 2 ) 2 , MA = CH 3 NH 3 , IPA = isopropanol) solution for a two-step multicycle spin-coating method in order to prepare high-quality FA x MA 1-x PbI 2.55 Br 0.45 perovskite films. Further investigation reveals that the existence of DMF in the FAI/MAI/IPA solution can facilitate perovskite conversion, improve the film morphology, and reduce crystal defects, thus enhancing charge-transfer efficiency. By optimization of the DMF amount and spin-coating cycles, compact, pinhole-free perovskite films are obtained. The nucleation mechanisms of perovskite films in our multicycle spin-coating process are suggested; that is, the introduction of DMF in the spin-coating FAI/MAI/IPA solution can lead to the formation of an amorphous phase PbX 2 -AI-DMSO-DMF (X = I, Br; A = FA, MA) instead of intermediate phase (MA) 2 Pb 3 I 8 ·2DMSO. This amorphous phase, similar to that in the one-step method, can help FAI/MAI penetrate into the PbI 2 framework to completely convert into the perovskite. As high as 20.1% power conversion efficiency (PCE) has been achieved with a steady-state PCE of 19.1%. Our work offers a simple repeatable method to prepare high-quality perovskite films for high-performance PSCs and also help further understand the perovskite-crystallization process.

  12. Evaluation of an interlaboratory comparison of the chemical assay of U, Th, oxide coated particles

    International Nuclear Information System (INIS)

    Tamberg, T.; Thiele, D.; Brodda, B.G.

    1981-09-01

    The prototype reactor THTR in Schmehausen (Germany, F.R.) burns a (Th,U)O 2 nuclear fuel using 93% enriched uranium. This material is particularly Safeguards sensitive. It was therefore desirable for the Safeguards Analytical Laboratory (SAL) and other laboratories of the Agency Network to collect experience and test their performance in the analysis of such materials. Support was requested from the ''Joint Programme between the IAEA and the Federal Republic of Germany for the Development of Safeguards Techniques'' to perform, as a first step, an interlaboratory comparison of the chemical assay of U and Th in pyrocarbon-coated BISO-type fuel particles. Such an intercomparison was organized under the auspices of the Institut fuer Chemische Technologie (ICT) of the Kernforschungsanlage Juelich GmbH (KFA). SAL prepared a statistical evaluation of the results which was discussed in Vienna in June 1980. The objective of the project was to define the state of the art in the chemical assay of U-Th fuels and the analytical requirements for the sampling of materials of major interest to Agency Safeguards at present

  13. The formation of FHA coating on biodegradable Mg-Zn-Zr alloy using a two-step chemical treatment method

    International Nuclear Information System (INIS)

    Jiang, S.T.; Zhang, J.; Shun, S.Z.; Chen, M.F.

    2016-01-01

    Highlights: • Use a two-step chemical treatment method for formation of FHA coating on biodegradable Mg-Zn-Zr alloy;. • We reported the formation mechanism of FHA coating on Mg-Zn-Zr alloy and achieved optimum properties;. • The MgF_2 coating and FHA coating provide effective protection for the Mg alloy substrate and the FHA coating showed better corrosion resistance. - Abstract: To improve the corrosion resistance of the biomedical magnesium alloy, a two-step chemical treatment method has been employed to prepare an FHA coating on the alloy surface. Prior to forming an FHA layer, the samples of Mg-3 wt% Zn-0.5 wt% Zr alloy were soaked in HF with concentration of 20% (v/v) at 37 °C temperature for 2 h, and were then placed into an aqueous solution with 0.1 mol/L Ca(NO_3).4H_2O and 0.06 mol/L NH_4H_2PO_4 at 90 °C to prepare the Ca-P coating. The concentrations of Mg"2"+, F"− ions, and pH variation with immersing time in the solution were investigated to explore the growth mechanism of FHA. The surface morphologies and compositions of the coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the alloy surface treated with acid formed a layer of MgF_2 nanoparticles with a thickness of 0.7 μm. The corrosion resistance of coatings in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the substrate with FHA coating had good corrosion resistance. After immersing into the calcium phosphate solution, some small spherical particles were first formed on the surface; these then cover the surface completely after 20 min. Some clusters consisting of needle-like crystal were observed in the spherical particles covering the surface, and the Ca/P ratio of the needle-like crystal was 1.46, clearly growing along the c axis preferred orientation growth. After immersion for 60 min, the FHA coating with

  14. The formation of FHA coating on biodegradable Mg-Zn-Zr alloy using a two-step chemical treatment method

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, S.T.; Zhang, J.; Shun, S.Z. [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin (China); Chen, M.F., E-mail: mfchentj@126.com [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin (China); Tianjin Key Laboratory of Display Materials and Photoelectric Device, Tianjin University of Technology , Tianjin (China)

    2016-12-01

    Highlights: • Use a two-step chemical treatment method for formation of FHA coating on biodegradable Mg-Zn-Zr alloy;. • We reported the formation mechanism of FHA coating on Mg-Zn-Zr alloy and achieved optimum properties;. • The MgF{sub 2} coating and FHA coating provide effective protection for the Mg alloy substrate and the FHA coating showed better corrosion resistance. - Abstract: To improve the corrosion resistance of the biomedical magnesium alloy, a two-step chemical treatment method has been employed to prepare an FHA coating on the alloy surface. Prior to forming an FHA layer, the samples of Mg-3 wt% Zn-0.5 wt% Zr alloy were soaked in HF with concentration of 20% (v/v) at 37 °C temperature for 2 h, and were then placed into an aqueous solution with 0.1 mol/L Ca(NO{sub 3}).4H{sub 2}O and 0.06 mol/L NH{sub 4}H{sub 2}PO{sub 4} at 90 °C to prepare the Ca-P coating. The concentrations of Mg{sup 2+}, F{sup −} ions, and pH variation with immersing time in the solution were investigated to explore the growth mechanism of FHA. The surface morphologies and compositions of the coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the alloy surface treated with acid formed a layer of MgF{sub 2} nanoparticles with a thickness of 0.7 μm. The corrosion resistance of coatings in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the substrate with FHA coating had good corrosion resistance. After immersing into the calcium phosphate solution, some small spherical particles were first formed on the surface; these then cover the surface completely after 20 min. Some clusters consisting of needle-like crystal were observed in the spherical particles covering the surface, and the Ca/P ratio of the needle-like crystal was 1.46, clearly growing along the c axis preferred orientation growth. After

  15. Using Fluorescence XANES Measurement to Correct the Content of Hexavalent Chromium in Chromate Conversion Coatings Determined by Diphenyl Carbazide Color Test

    International Nuclear Information System (INIS)

    Nishino, Junichi; Ofuchi, Hironori; Taniguchi, Yosuke; Honma, Tetsuo; Sekikawa, Toshikazu; Otani, Haruka; Bando, Akio

    2007-01-01

    The Restriction of the use of certain Hazardous Substances (RoHS) directive will take effect on July 1 of this year. From that date, the use of chromate conversion coatings containing hexavalent chromium will not be permitted. By comparing the concentration of Cr6+ determined by the diphenyl carbazide color test and by fluorescence XANES (X-Ray Absorption Near Edge Structure) measurement, we can correct for the Cr6+ content of the color test. This will enable the use of the diphenyl carbazide color test to check product shipments in compliance with the RoHS directive

  16. Bio-based C-3 Platform Chemical: Biotechnological Production and -Conversion of 3-Hydroxypropionaldehyde

    OpenAIRE

    Rezaei, Roya

    2013-01-01

    Demands for efficient, greener, economical and sustainable production of chemicals, materials and energy have led to development of industrial biotechnology as a key technology area to provide such products from bio-based raw materials from agricultural-, forestry- and related industrial residues and by-products. For the bio-based industry, it is essential to develop a number of building blocks or platform chemicals for C2-C6 chemicals and even aromatic chemicals. 3-hydroxypropionaldehyde (3H...

  17. Corrosion resistance of multilayered magnesium phosphate/magnesium hydroxide film formed on magnesium alloy using steam-curing assisted chemical conversion method

    International Nuclear Information System (INIS)

    Ishizaki, Takahiro; Kudo, Ruriko; Omi, Takeshi; Teshima, Katsuya; Sonoda, Tsutomu; Shigematsu, Ichinori; Sakamoto, Michiru

    2012-01-01

    Anticorrosive multilayered films were successfully prepared on magnesium alloy AZ31 by chemical conversion treatment, followed by steam curing treatment. The crystal structures, chemical composition, surface morphologies, chemical bonding states of the film was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscope (FE-SEM) measurements. All the films had thicknesses of ranging from 24 to 32 μm. The film had two layers that were composed of crystalline NH 4 MgPO 4 ·H 2 O, Mg 2 PO 4 OH·3H 2 O, Mg(OH) 2 and amorphous MgO. The outer layers include magnesium, oxygen, and phosphorous, and the inner layers include magnesium and oxygen. The corrosion resistant performances of the multilayered films in 5 wt% NaCl aqueous solution were investigated by electrochemical and gravimetric measurements. The potentiodynamic polarization curves revealed that the corrosion current density (j corr ) of all the film coated magnesium alloys decreased by more than four orders of magnitude as compared to that of the bare magnesium alloy, indicating that all the films had an inhibiting effect of corrosion reaction. Gravimetric measurements showed that the average corrosion rates obtained from the weight loss rates were estimated to be in the ranges of ca. 0.085–0.129 mm/y. American Society for Testing and Materials (ASTM) standard D 3359-02 cross cut tape test revealed that the adhesion of our anticorrosive multilayered film to the magnesium alloy surface was very good.

  18. Chemical synthesis and characterization of hollow dopamine coated, pentagonal and flower shaped magnetic iron oxide nanoparticles

    Science.gov (United States)

    Riasat, Rabia; Kaynat, Sumbal

    2018-04-01

    Iron oxide nanoparticles have gained attention recently in the field of nanoscience and technology due to their unique physicochemical properties. We hereby chemically synthesized novel pentagonal flower shaped iron oxide nanoparticles by thermal decomposition of iron penta-carbonyl in a two way annealing process. Controlled oxidation by acid etching was performed for these nanoparticles. At first 13 nm core shell nanoparticles of iron oxide (Fe/Fe3O4) were synthesized at 120°C annealing temperature that act as template material. The core shell nanoparticles then converted into porous hollow core shell nanoparticles (PH Fe/ Fe3O4) in a two way annealing process of heating, first at 100°C then at 250°C and heating rate of 5°C was kept constant throughout the reaction time. X-Ray diffraction (XRD) was done for the phase confirmation of as synthesized nanoparticles. Transmission electron microscopy (TEM) and higher resolution transmission electron microscopy (HRTEM) clearly shows the flower like nanoparticles that are approx. 16 nm-18 nm in size having the 4-5 nm core of Fe and 1-2 nm of the pores in the shell while the cavity between the shell and core is about 2 nm and the shell is 4-5 nm in diameter according to the TEM micrographs. The as prepared nanoparticles were then surface functionalized by dopamine polymer to make them water dispersible. Fourier transform Infrared spectroscopy confirmed the dopamine coating on the nanoparticles and the magnetic saturation of 38 emu/g of nanoparticles was analyzed by vibrating sample magnetometer (VSM). Magnetic saturation persists in the dopamine coated nanoparticles. These nanoparticles were surface functionalized with dopamine and show dispersity in the aqueous media and can further be exploited in many nano-biotechnological applications including target specific therapeutic applications for several diseases.

  19. Effects of heat treatment on the microstructure of amorphous boron carbide coating deposited on graphite substrates by chemical vapor deposition

    International Nuclear Information System (INIS)

    Li Siwei; Zeng Bin; Feng Zude; Liu Yongsheng; Yang Wenbin; Cheng Laifei; Zhang Litong

    2010-01-01

    A two-layer boron carbide coating is deposited on a graphite substrate by chemical vapor deposition from a CH 4 /BCl 3 /H 2 precursor mixture at a low temperature of 950 o C and a reduced pressure of 10 KPa. Coated substrates are annealed at 1600 o C, 1700 o C, 1800 o C, 1900 o C and 2000 o C in high purity argon for 2 h, respectively. Structural evolution of the coatings is explored by electron microscopy and spectroscopy. Results demonstrate that the as-deposited coating is composed of pyrolytic carbon and amorphous boron carbide. A composition gradient of B and C is induced in each deposition. After annealing, B 4 C crystallites precipitate out of the amorphous boron carbide and grow to several hundreds nanometers by receiving B and C from boron-doped pyrolytic carbon. Energy-dispersive spectroscopy proves that the crystallization is controlled by element diffusion activated by high temperature annealing, after that a larger concentration gradient of B and C is induced in the coating. Quantified Raman spectrum identifies a graphitization enhancement of pyrolytic carbon. Transmission electron microscopy exhibits an epitaxial growth of B 4 C at layer/layer interface of the annealed coatings. Mechanism concerning the structural evolution on the basis of the experimental results is proposed.

  20. Preparation of rutile TiO(2) coating by thermal chemical vapor deposition for anticoking applications.

    Science.gov (United States)

    Tang, Shiyun; Wang, Jianli; Zhu, Quan; Chen, Yaoqiang; Li, Xiangyuan

    2014-10-08

    To inhibit the metal catalytic coking and improve the oxidation resistance of TiN coating, rutile TiO2 coating has been directly designed as an efficient anticoking coating for n-hexane pyrolysis. TiO2 coatings were prepared on the inner surface of SS304 tubes by a thermal CVD method under varied temperatures from 650 to 900 °C. The rutile TiO2 coating was obtained by annealing the as-deposited TiO2 coating, which is an alternative route for the deposition of rutile TiO2 coating. The morphology, elemental and phase composition of TiO2 coatings were characterized by SEM, EDX and XRD, respectively. The results show that deposition temperature of TiO2 coatings has a strong effect on the morphology and thickness of as-deposited TiO2 coatings. Fe, Cr and Ni at.% of the substrate gradually changes to 0 when the temperature is increased to 800 °C. The thickness of TiO2 coating is more than 6 μm and uniform by metalloscopy, and the films have a nonstoichiometric composition of Ti3O8 when the deposition temperature is above 800 °C. The anticoking tests show that the TiO2 coating at a deposition temperature of 800 °C is sufficiently thick to cover the cracks and gaps on the surface of blank substrate and cut off the catalytic coke growth effect of the metal substrate. The anticoking ratio of TiO2 coating corresponding to each 5 cm segments is above 65% and the average anticoking ratio of TiO2 coating is up to 76%. Thus, the TiO2 coating can provide a very good protective layer to prevent the substrate from severe coking efficiently.

  1. Bonding Characteristics and Chemical Inertness of Zr–Si–N Coatings with a High Si Content in Glass Molding

    Directory of Open Access Journals (Sweden)

    Li-Chun Chang

    2018-05-01

    Full Text Available High-Si-content transition metal nitride coatings, which exhibited an X-ray amorphous phase, were proposed as protective coatings on glass molding dies. In a previous study, the Zr–Si–N coatings with Si contents of 24–30 at.% exhibited the hardness of Si3N4, which was higher than those of the middle-Si-content (19 at.% coatings. In this study, the bonding characteristics of the constituent elements of Zr–Si–N coatings were evaluated through X-ray photoelectron spectroscopy. Results indicated that the Zr 3d5/2 levels were 179.14–180.22 and 180.75–181.61 eV for the Zr–N bonds in ZrN and Zr3N4 compounds, respectively. Moreover, the percentage of Zr–N bond in the Zr3N4 compound increased with increasing Si content in the Zr–Si–N coatings. The Zr–N bond of Zr3N4 dominated when the Si content was >24 at.%. Therefore, high Si content can stabilize the Zr–N compound in the M3N4 bonding structure. Furthermore, the thermal stability and chemical inertness of Zr–Si–N coatings were evaluated by conducting thermal cycle annealing at 270 °C and 600 °C in a 15-ppm O2–N2 atmosphere. The results indicated that a Zr22Si29N49/Ti/WC assembly was suitable as a protective coating against SiO2–B2O3–BaO-based glass for 450 thermal cycles.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-01

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

  3. Dual-enhanced photothermal conversion properties of reduced graphene oxide-coated gold superparticles for light-triggered acoustic and thermal theranostics

    Science.gov (United States)

    Lin, Li-Sen; Yang, Xiangyu; Niu, Gang; Song, Jibin; Yang, Huang-Hao; Chen, Xiaoyuan

    2016-01-01

    A rational design of highly efficient photothermal agents that possess excellent light-to-heat conversion properties is a fascinating topic in nanotheranostics. Herein, we present a facile route to fabricate size-tunable reduced graphene oxide (rGO)-coated gold superparticles (rGO-GSPs) and demonstrate their dual-enhanced photothermal conversion properties for photoacoustic imaging and photothermal therapy. For the first time, graphene oxide (GO) was directly used as an emulsifying agent for the preparation of gold superparticles (GSPs) with near-infrared absorption by the emulsion method. Moreover, GO spontaneously deposited on the surface of GSPs could also act as the precursor of the rGO shell. Importantly, both the plasmonic coupling of the self-assembled gold nanoparticles and the interaction between GSPs and rGO endow rGO-GSPs with enhanced photothermal conversion properties, allowing rGO-GSPs to be used for sensitive photoacoustic detection and efficient photothermal ablation of tumours in vivo. This study provides a facile approach to prepare colloidal superparticles-graphene hybrid nanostructures and will pave the way toward the design and optimization of photothermal nanomaterials with improved properties for theranostic applications.A rational design of highly efficient photothermal agents that possess excellent light-to-heat conversion properties is a fascinating topic in nanotheranostics. Herein, we present a facile route to fabricate size-tunable reduced graphene oxide (rGO)-coated gold superparticles (rGO-GSPs) and demonstrate their dual-enhanced photothermal conversion properties for photoacoustic imaging and photothermal therapy. For the first time, graphene oxide (GO) was directly used as an emulsifying agent for the preparation of gold superparticles (GSPs) with near-infrared absorption by the emulsion method. Moreover, GO spontaneously deposited on the surface of GSPs could also act as the precursor of the rGO shell. Importantly, both the

  4. The effect of surface pre-conditioning treatments on the local composition of Zr-based conversion coatings formed on aluminium alloys

    Science.gov (United States)

    Cerezo, J.; Vandendael, I.; Posner, R.; de Wit, J. H. W.; Mol, J. M. C.; Terryn, H.

    2016-03-01

    This study investigates the effect of different alkaline, acidic and thermal pre-conditioning treatments applied to different Al alloy surfaces. The obtained results are compared to the characteristics of Zr-based conversion coatings that were subsequently generated on top of these substrates. Focus is laid on typical elemental distributions on the sample surfaces, in particular on the amount of precipitated functional additives such as Cu species that are present in the substrate matrix as well as in the conversion bath solutions. To this aim, Field Emission Auger Electron spectra, depth profiles and surface maps with superior local resolution were acquired and compared to scanning electron microscopy images of the sample. The results show how de-alloying processes, which occur at and around intermetallic particles in the Al matrix during typical industrial alkaline or acidic cleaning procedures, provide a significant source of crystallization cores for any following coating processes. This is in particular due for Cu-species, as the resulting local Cu structures on the surface strongly affect the film formation and compositions of state-of-the-art Zr-based films. The findings are highly relevant for industrial treatments of aluminium surfaces, especially for those that undergo corrosion protection and painting process steps prior to usage.

  5. Up-conversion luminescence application in Er3+: TiO2 thin film prepared by dip coating sol-gel route

    International Nuclear Information System (INIS)

    Badr, Y.; Battisha, I.K.; Salah, A.; Salem, M.A.

    2008-01-01

    Sol-gel derived nano-crystalline titanium dioxide films doped with 1 up to 5% Er 3+ ions were prepared by dip coating sol-gel method. The coating sol was obtained by hydrolysis of Ti(OC 4 H 9 ) 4 in ethanol/HCI solution. The FT-Raman and the X-ray diffraction (XRD) were carried out to determine the crystal structure of the prepared samples. The morphology SEM and the cross-sectional of the film were used to characterize the microstructure and the thickness of the prepared film. It is shown that relative homogeneous, crack-free and transparent film was achieved via dipping process at 500 deg C. After the excitation with laser diode at wavelength 808 nm, visible (Vis) and infrared (IR) up-conversion emissions were evidenced in the thin film samples under investigation. The up-conversion was found to depend strongly on the Er 3+ ion concentrations. The visible emission was found to be at 540, 560, 590 and 640 nm for thin film. They are attributed to intra-4f transition of Er 3+ ions and assigned to the ( 2 H 11/2 + 4 S 3/2 ) and 4 F 9/2 , which are populated through excited state absorption (ESA) for 808 nm excitation. (author)

  6. Characterization of CuS nanocrystalline thin films synthesized by chemical bath deposition and dip coating techniques

    International Nuclear Information System (INIS)

    Chaki, Sunil H.; Deshpande, M.P.; Tailor, Jiten P.

    2014-01-01

    CuS thin films were synthesized by chemical bath deposition and dip coating techniques at ambient temperature. The energy dispersive analysis of X-rays of the thin films confirmed that both the as synthesized thin films are stoichiometric. The X-ray diffraction of the chemical bath deposited and dip coating deposited thin films showed that the films possess hexagonal structure having lattice parameters, a = b = 3.79 A and c = 16.34 A. The crystallite sizes determined from the X-ray diffraction data using Scherrer's formula for the chemical bath deposition and dip coating deposition thin films came out to be nearly 11 nm and 13 nm, respectively. The optical microscopy of the as deposited thin films surfaces showed that the substrates are well covered in both the deposited films. The scanning electron microscopy of the thin films clearly showed that in chemical bath deposited thin films the grain size varies from few μm to nm, while in dip coating deposited films the grain size ranges in nm. The optical bandgap determined from the optical absorbance spectrum analysis showed, chemical bath deposited thin films possess direct bandgap of 2.2 eV and indirect bandgap of 1.8 eV. In the case of dip coating deposited thin films, the direct bandgap is 2.5 eV and indirect bandgap is 1.9 eV. The d.c. electrical resistivity variation with temperature for both the deposited films showed that the resistivity decreases with temperature thus confirming the semiconducting nature. The thermoelectric power variations with temperature and the room temperature Hall Effect study of both the synthesized CuS thin films showed them to be of p-type conductivity. The obtained results are discussed in details. - Highlights: • CuS thin films were synthesized by chemical bath deposition and dip coating techniques. • The films possessed hexagonal structure. • The optical absorption showed that the films had direct and indirect bandgap. • Study of electrical transport properties

  7. Chemically grafted carbon-coated LiFePO4 using diazonium chemistry

    Science.gov (United States)

    Delaporte, Nicolas; Perea, Alexis; Amin, Ruhul; Zaghib, Karim; Bélanger, Daniel

    2015-04-01

    The effect of surface functionalization of aminophenyl and bromophenyl groups on carbon-coated LiFePO4 and the electrochemical properties of composite electrode containing these materials are reported. The functionalization was performed by spontaneous reduction of the corresponding in situ generated diazonium ions. The resulting chemically grafted LiFePO4/C materials were characterized by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) to confirm the presence of the surface organic species. XRD analyses indicated the cathode material was partially oxidized. Thermogravimetric and elemental analyses revealed the loading of grafted molecules was between 0.2 and 1.1 wt.% depending on the reaction conditions. Interestingly, the electrochemical performances of the modified LiFePO4/C are not adversely affected by the presence of either aminophenyl and bromophenyl groups at the carbon surface, and in fact the grafted LiFePO4/C displayed slightly superior discharge capacity at the highest C rate investigated for a low loading of organic molecules.

  8. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Wallenhorst, L.M.; Loewenthal, L.; Avramidis, G.; Gerhard, C.; Militz, H.; Ohms, G.; Viöl, W.

    2017-01-01

    Highlights: • Zn/ZnO mixed systems were deposited from elemental zinc by a cold plasma-spray process. • Oxidation was confirmed by XPS. • The coatings exhibited a strong absorption in the UV spectral range, thus being suitable as protective layers, e.g. on thermosensitive materials. - Abstract: In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  9. Chemical solution deposition of LaMnO3-based films for coated conductors

    International Nuclear Information System (INIS)

    Shi, D Q; Zhu, X B; Kim, J H; Wang, L; Zeng, R; Dou, S X; Lei, H C; Sun, Y P

    2008-01-01

    LaMnO 3 -based films were prepared using the chemical solution deposition method. It was found that the films on perovskite oxide single crystal substrates are highly (h00)-oriented when the annealing atmosphere is oxygen or air; however, when the substrate is yttrium-stabilized ZrO 2 , only the La 1-x Na x MnO 3 films are highly (h00)-oriented, and other LaMnO 3 -based films are (110)-oriented. Under a reducing annealing atmosphere, the atmosphere must be wet in order to create a suitable oxygen partial pressure to crystallize the LaMnO 3 -based films. After annealing under a wet reducing atmosphere the LaMnO 3 -based films are (110)-oriented when the films are directly deposited on Ni tapes; however, when SrTiO 3 -buffered Ni tapes are used, the LaMnO 3 films are (h00)-oriented, which is suitable for subsequent growth of YBCO. The results suggest that it is possible to tune the orientation of buffer layers using suitable templates, which can widen the selection of buffer layers for coated conductors in the all metallorganic deposition approach

  10. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    Energy Technology Data Exchange (ETDEWEB)

    Wallenhorst, L.M., E-mail: lena.wallenhorst@hawk-hhg.de [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Loewenthal, L.; Avramidis, G. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Gerhard, C. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Fraunhofer Institute for Surface Engineering and Thin Films, Application Center for Plasma and Photonics, Von-Ossietzky-Str. 100, 37085 Göttingen (Germany); Militz, H. [Wood Biology and Wood Products, Burckhardt Institute, Georg-August-University Göttingen, Büsgenweg 4, 37077 Göttingen (Germany); Ohms, G. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Viöl, W. [University of Applied Sciences and Arts, Laboratory of Laser and Plasma Technologies, Von-Ossietzky-Str. 99, 37085 Göttingen (Germany); Fraunhofer Institute for Surface Engineering and Thin Films, Application Center for Plasma and Photonics, Von-Ossietzky-Str. 100, 37085 Göttingen (Germany)

    2017-07-15

    Highlights: • Zn/ZnO mixed systems were deposited from elemental zinc by a cold plasma-spray process. • Oxidation was confirmed by XPS. • The coatings exhibited a strong absorption in the UV spectral range, thus being suitable as protective layers, e.g. on thermosensitive materials. - Abstract: In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  11. Numerical investigation of a straw combustion boiler – Part I: Modelling of the thermo-chemical conversion of straw

    Directory of Open Access Journals (Sweden)

    Dernbecher Andrea

    2016-01-01

    Full Text Available In the framework of a European project, a straw combustion boiler in conjunction with an organic Rankine cycle is developed. One objective of the project is the enhancement of the combustion chamber by numerical methods. A comprehensive simulation of the combustion chamber is prepared, which contains the necessary submodels for the thermo-chemical conversion of straw and for the homogeneous gas phase reactions. Part I introduces the modelling approach for the thermal decomposition of the biomass inside the fuel bed, whereas part II deals with the simulation of the gas phase reactions in the freeboard.

  12. Surface modification of reverse osmosis desalination membranes by thin-film coatings deposited by initiated chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ozaydin-Ince, Gozde, E-mail: gozdeince@sabanciuniv.edu [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Matin, Asif, E-mail: amatin@mit.edu [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Khan, Zafarullah, E-mail: zukhan@mit.edu [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Zaidi, S.M. Javaid, E-mail: zaidismj@kfupm.edu.sa [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Gleason, Karen K., E-mail: kkgleasn@mit.edu [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2013-07-31

    Thin-film polymeric reverse osmosis membranes, due to their high permeation rates and good salt rejection capabilities, are widely used for seawater desalination. However, these membranes are prone to biofouling, which affects their performance and efficiency. In this work, we report a method to modify the membrane surface without damaging the active layer or significantly affecting the performance of the membrane. Amphiphilic copolymer films of hydrophilic hydroxyethylmethacrylate and hydrophobic perfluorodecylacrylate (PFA) were synthesized and deposited on commercial RO membranes using an initiated chemical vapor deposition technique which is a polymer deposition technique that involves free-radical polymerization initiated by gas-phase radicals. Relevant surface characteristics such as hydrophilicity and roughness could be systematically controlled by varying the polymer chemistry. Increasing the hydrophobic PFA content in the films leads to an increase in the surface roughness and hydrophobicity. Furthermore, the surface morphology studies performed using the atomic force microscopy show that as the thickness of the coating increases average surface roughness increases. Using this knowledge, the coating thickness and chemistry were optimized to achieve high permeate flux and to reduce cell attachment. Results of the static bacterial adhesion tests show that the attachment of bacterial cells is significantly reduced on the coated membranes. - Highlights: • Thin films are deposited on reverse osmosis membranes. • Amphiphilic thin films are resistant to protein attachment. • The permeation performance of the membranes is not affected by the coating. • The thin film coatings delayed the biofouling.

  13. In situ spray deposition of cell-loaded, thermally and chemically gelling hydrogel coatings for tissue regeneration.

    Science.gov (United States)

    Pehlivaner Kara, Meryem O; Ekenseair, Adam K

    2016-10-01

    In this study, the efficacy of creating cellular hydrogel coatings on warm tissue surfaces through the minimally invasive, sprayable delivery of thermoresponsive liquid solutions was investigated. Poly(N-isopropylacrylamide)-based (pNiPAAm) thermogelling macromers with or without addition of crosslinking polyamidoamine (PAMAM) macromers were synthesized and used to produce in situ forming thermally and chemically gelling hydrogel systems. The effect of solution and process parameters on hydrogel physical properties and morphology was evaluated and compared to poly(ethylene glycol) and injection controls. Smooth, fast, and conformal hydrogel coatings were obtained when pNiPAAm thermogelling macromers were sprayed with high PAMAM concentration at low pressure. Cellular hydrogel coatings were further fabricated by different spraying techniques: single-stream, layer-by-layer, and dual stream methods. The impact of spray technique, solution formulation, pressure, and spray solution viscosity on the viability of fibroblast and osteoblast cells encapsulated in hydrogels was elucidated. In particular, the early formation of chemically crosslinked micronetworks during bulk liquid flow was shown to significantly affect cell viability under turbulent conditions compared to injectable controls. The results demonstrated that sprayable, in situ forming hydrogels capable of delivering cell populations in a homogeneous therapeutic coating on diseased tissue surfaces offer promise as novel therapies for applications in regenerative medicine. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2383-2393, 2016. © 2016 Wiley Periodicals, Inc.

  14. Chemical energy conversion as enabling factor to move to a renewable energy economy

    Energy Technology Data Exchange (ETDEWEB)

    Abate, Salvatore; Centi, Gabriele; Perathoner, Siglinda [Mesina Univ. (Italy). Section Industrial Chemistry; ERIC aisbl and INSTM/CASPE, Messina (Italy)

    2015-07-01

    The role of chemical energy storage and solar fuels as key elements for the sustainable chemical and energy production is discussed in this concept paper. It is shown how chemical energy storage, with the development of drop-in carbon-based solar fuels, will play a central role in the future low-carbon economy, but it is necessary to consider its out-of-the-grid use, rather than being limited to be a tool for smart grids. Related aspects discussed are the possibility to: (i) enable a system of trading renewable energy on a world scale (out-of-the-grid), including the possibility to exploit actually unused remote resources, (ii) develop a solar-driven and low-carbon chemical production, which reduces the use of fossil fuels and (iii) create a distributed energy production, going beyond the actual limitations and dependence on the grid.

  15. Physical, Chemical and Microbial Characteristic of Gouda Cheese Using Propolis (Apis milifera Liguistica as Coating Material

    Directory of Open Access Journals (Sweden)

    Lilik Eka Radiati

    2012-02-01

    Full Text Available Gouda cheeses were coated with different coating materials consist of pliol, beeswax, and beeswax containing different concentration of propolis  by 0,2, 0,4 and 0,8%  and stored  during  ripening at 10oC period. The result showed that no different of moisture, fat and protein content, hardness, pH value of cheese products. The hydrolysis process at maturity caused decreasing of  pH value. Added propolis in the coating material could inhibited  mould and yeast growth significantly. Key words:  Gouda Cheese, propolis, edible coating

  16. Methods for conversion of carbohydrates in ionic liquids to value-added chemicals

    Science.gov (United States)

    Zhao, Haibo [The Woodlands, TX; Holladay, Johnathan E [Kennewick, WA; Zhang, Zongchao C [Norwood, NJ

    2011-05-10

    Methods are described for converting carbohydrates including, e.g., monosaccharides, disaccharides, and polysaccharides in ionic liquids to value-added chemicals including furans, useful as chemical intermediates and/or feedstocks. Fructose is converted to 5-hydroxylmethylfurfural (HMF) in the presence of metal halide and acid catalysts. Glucose is effectively converted to HMF in the presence of chromium chloride catalysts. Yields of up to about 70% are achieved with low levels of impurities such as levulinic acid.

  17. Modeling the high-temperature gas-cooled reactor process heat plant: a nuclear to chemical conversion process

    International Nuclear Information System (INIS)

    Pfremmer, R.D.; Openshaw, F.L.

    1982-05-01

    The high-temperature heat available from the High-Temperature Gas-Cooled Reactor (HTGR) makes it suitable for many process applications. One of these applications is a large-scale energy production plant where nuclear energy is converted into chemical energy and stored for industrial or utility applications. This concept combines presently available nuclear HTGR technology and energy conversion chemical technology. The design of this complex plant involves questions of interacting plant dynamics and overall plant control. This paper discusses how these questions were answered with the aid of a hybrid computer model that was developed within the time-frame of the conceptual design studies. A brief discussion is given of the generally good operability shown for the plant and of the specific potential problems and their anticipated solution. The paper stresses the advantages of providing this information in the earliest conceptual phases of the design

  18. Structured catalyst bed and method for conversion of feed materials to chemical products and liquid fuels

    Science.gov (United States)

    Wang, Yong , Liu; Wei, [Richland, WA

    2012-01-24

    The present invention is a structured monolith reactor and method that provides for controlled Fischer-Tropsch (FT) synthesis. The invention controls mass transport limitations leading to higher CO conversion and lower methane selectivity. Over 95 wt % of the total product liquid hydrocarbons obtained from the monolithic catalyst are in the carbon range of C.sub.5-C.sub.18. The reactor controls readsorption of olefins leading to desired products with a preselected chain length distribution and enhanced overall reaction rate. And, liquid product analysis shows readsorption of olefins is reduced, achieving a narrower FT product distribution.

  19. The direct conversion of synthesis gas to chemicals / Ernest du Toit

    OpenAIRE

    Du Toit, Ernest

    2002-01-01

    The catalytic conversion of synthesis gas, obtainable from the processing of coal, biomass or natural gas, to a complex hydrocarbon product stream can be achieved via the Fischer-Tropsch process. The Fischer-Tropsch synthesis process has evolved from being mainly a fuel producing process in the early 1950's to that of a solvent and speciality wax production process towards the end of the 1970's. From the early 1980's there has been a clear shift towards the production of commod...

  20. Ductile polyelectrolyte macromolecule-complexed zinc phosphate conversion crystal pre-coatings and topcoatings embodying a laminate

    Science.gov (United States)

    Sugama, Toshifumi; Kukacka, Lawrence E.; Carciello, Neal R.

    1987-01-01

    This invention relates to a precoat, laminate, and method for ductile coatings on steel and non-ferrous metals which comprises applying a zinc phosphating coating solution modified by a solid polyelectrolyte selected from polyacrylic acid (PAA), polymethacrylic acid (PMA), polyitaconic acid (PIA), and poly-L-glutamic acid. The contacting of the resin with the phosphating solution is made for a period of up to 20 hours at about 80.degree. C. The polyelectrolyte or the precoat is present in about 0.5-5.0% by weight of the total precoat composition and after application, the precoat base is dried for up to 5 hours at about 150.degree. C. to desiccate. Also, a laminate may be formed where polyurethane (PU) is applied as an elastomeric topcoating or polyfuran resin is applied as a glassy topcoating. It has been found that the use of PAA at a molecular weight of about 2.times.10.sup.5 gave improved ductility modulus effect.

  1. Corrosion Performance of Composite Galvanic Coatings with Variable Concentration of Polymeric Nanoaggregates and/or Cr(III) Conversion Layers

    NARCIS (Netherlands)

    Koleva, D.A.; Taheri, P.; Tsvetkova, N.; Boshkov, N.; Van Breugel, K.; De Wit, J.H.W.; Mol, J.M.C.

    2011-01-01

    This paper reports on the corrosion performance of composite zinc layers (~ 8µm) on a steel substrate, considering the influence of nano-aggregates and Cr(III) conversion layers, compared to control (only Zn layers) conditions. The main factors, influencing the corrosion performance of Zn in this

  2. Phosphate conversion coating reduces the degradation rate and suppresses side effects of metallic magnesium implants in an animal model.

    Science.gov (United States)

    Rahim, Muhammad Imran; Tavares, Ana; Evertz, Florian; Kieke, Marc; Seitz, Jan-Marten; Eifler, Rainer; Weizbauer, Andreas; Willbold, Elmar; Jürgen Maier, Hans; Glasmacher, Birgit; Behrens, Peter; Hauser, Hansjörg; Mueller, Peter P

    2017-08-01

    Magnesium alloys have promising mechanical and biological properties for the development of degradable implants. However, rapid implant corrosion and gas accumulations in tissue impede clinical applications. With time, the implant degradation rate is reduced by a highly biocompatible, phosphate-containing corrosion layer. To circumvent initial side effects after implantation it was attempted to develop a simple in vitro procedure to generate a similarly protective phosphate corrosion layer. To this end magnesium samples were pre-incubated in phosphate solutions. The resulting coating was well adherent during routine handling procedures. It completely suppressed the initial burst of corrosion and it reduced the average in vitro magnesium degradation rate over 56 days almost two-fold. In a small animal model phosphate coatings on magnesium implants were highly biocompatible and abrogated the appearance of gas cavities in the tissue. After implantation, the phosphate coating was replaced by a layer with an elemental composition that was highly similar to the corrosion layer that had formed on plain magnesium implants. The data demonstrate that a simple pre-treatment could improve clinically relevant properties of magnesium-based implants. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1622-1635, 2017. © 2016 Wiley Periodicals, Inc.

  3. Conversion of wastes into bioelectricity and chemicals by using microbial electrochemical technologies.

    Science.gov (United States)

    Logan, Bruce E; Rabaey, Korneel

    2012-08-10

    Waste biomass is a cheap and relatively abundant source of electrons for microbes capable of producing electrical current outside the cell. Rapidly developing microbial electrochemical technologies, such as microbial fuel cells, are part of a diverse platform of future sustainable energy and chemical production technologies. We review the key advances that will enable the use of exoelectrogenic microorganisms to generate biofuels, hydrogen gas, methane, and other valuable inorganic and organic chemicals. Moreover, we examine the key challenges for implementing these systems and compare them to similar renewable energy technologies. Although commercial development is already underway in several different applications, ranging from wastewater treatment to industrial chemical production, further research is needed regarding efficiency, scalability, system lifetimes, and reliability.

  4. Conversion of Wastes into Bioelectricity and Chemicals by Using Microbial Electrochemical Technologies

    KAUST Repository

    Logan, B. E.

    2012-08-09

    Waste biomass is a cheap and relatively abundant source of electrons for microbes capable of producing electrical current outside the cell. Rapidly developing microbial electrochemical technologies, such as microbial fuel cells, are part of a diverse platform of future sustainable energy and chemical production technologies. We review the key advances that will enable the use of exoelectrogenic microorganisms to generate biofuels, hydrogen gas, methane, and other valuable inorganic and organic chemicals. Moreover, we examine the key challenges for implementing these systems and compare them to similar renewable energy technologies. Although commercial development is already underway in several different applications, ranging from wastewater treatment to industrial chemical production, further research is needed regarding efficiency, scalability, system lifetimes, and reliability.

  5. Mechanical properties of chemically bonded sand core materials dipped in sol-gel coating impregnated with filter

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Tiedje, Niels Skat

    2012-01-01

    A novel sol-gel coating impregnated with filter dust was applied on chemically bonded sand core materials by dipping. After curing, the strengths of the core materials were measured under uniaxial loading using a new strength testing machine (STM). The STM presents the loading history as a force-...... of the chemically bonded sand core materials, a combination of flexural and compression tests is suggested for improving the casting quality. © 2012 W. S. Maney & Son Ltd.......A novel sol-gel coating impregnated with filter dust was applied on chemically bonded sand core materials by dipping. After curing, the strengths of the core materials were measured under uniaxial loading using a new strength testing machine (STM). The STM presents the loading history as a force...... the strengths were increased under compression. The mode of fracture of the chemically bonded sand core materials was observed to be intergranular through the binder. The stiffness of the chemically bonded sand core materials was determined. For better understanding of the mechanical properties...

  6. Chemical conversion of cisplatin and carboplatin with histidine in a model protein crystallized under sodium iodide conditions

    Energy Technology Data Exchange (ETDEWEB)

    Tanley, Simon W. M.; Helliwell, John R., E-mail: john.helliwell@manchester.ac.uk [University of Manchester, Brunswick Street, Manchester M13 9PL (United Kingdom)

    2014-08-29

    Crystals of HEWL with cisplatin and HEWL with carboplatin grown in sodium iodide conditions both show a partial chemical transformation of cisplatin or carboplatin to a transiodoplatin (PtI{sub 2}X{sub 2}) form. The binding is only at the N{sup δ} atom of His15. A further Pt species (PtI{sub 3}X) is also seen, in both cases bound in a crevice between symmetry-related protein molecules. Cisplatin and carboplatin are platinum anticancer agents that are used to treat a variety of cancers. Previous X-ray crystallographic studies of carboplatin binding to histidine in hen egg-white lysozyme (HEWL) showed a partial chemical conversion of carboplatin to cisplatin owing to the high sodium chloride concentration used in the crystallization conditions. Also, the co-crystallization of HEWL with carboplatin in sodium bromide conditions resulted in the partial conversion of carboplatin to the transbromoplatin form, with a portion of the cyclobutanedicarboxylate (CBDC) moiety still present. The results of the co-crystallization of HEWL with cisplatin or carboplatin in sodium iodide conditions are now reported in order to determine whether the cisplatin and carboplatin converted to the iodo form, and whether this took place in a similar way to the partial conversion of carboplatin to cisplatin in NaCl conditions or to transbromoplatin in NaBr conditions as seen previously. It is reported here that a partial chemical transformation has taken place to a transplatin form for both ligands. The NaI-grown crystals belonged to the monoclinic space group P2{sub 1} with two molecules in the asymmetric unit. The chemically transformed cisplatin and carboplatin bind to both His15 residues, i.e. in each asymmetric unit. The binding is only at the N{sup δ} atom of His15. A third platinum species is also seen in both conditions bound in a crevice between symmetry-related molecules. Here, the platinum is bound to three I atoms identified based on their anomalous difference electron densities

  7. Analyses on the U-Mo/Al Chemical Interaction and the Effects of Diffusion Barrier Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Ho Jin; Kim, Woo Jeong; Cho, Woo Hyung; Jeong, Yong Jin; Lee, Yoon Sang; Park, Jong Man; Kim, Chang Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    While many HEU-fueled research reactors have been converted by adopting LEU U{sub 3}Si{sub 2} fuel in harmony with the Reduced Enrichment for Research and Test Reactors (RERTR) program, some high performance research reactors still need the development of advanced fuels with higher uranium densities. Currently, gamma-phase U-Mo alloys are considered promising candidates to be used as high uranium density fuel for the high performance reactors. For the production of UMo alloy powder, the centrifugal atomization technology developed by KAERI has been considered the most promising way because of high yield production and excellent powder quality when compared with other possible methods such as grinding, machining or hydriding-dehydriding. However, severe pore formation associated with an extensive interaction between the U-Mo and Al matrix, although the irradiation performance of U-Mo itself showed most stable, delay the fuel qualification of UMo fuel for high performance research reactors. Because the reaction products, i.e. uranium aluminides (UAlx), is less dense than the mixed reactants, the volume of the fuel meat increases after formation of interaction layer(IL). In addition to the impact on the swelling performance, the reaction layers between the U-Mo and Al matrix induces a degradation of the thermal conductivities of the U-Mo/Al dispersion fuels. The chemical interaction between the U-Mo and Al matrix are analyzed in this study to find remedies to reduce the growth of the interaction layers during irradiation. In addition, various coating technologies for the formation of diffusion barriers on U-Mo particles are proposed as a result of the analyses

  8. Improvement on the electrochemical characteristics of graphite anodes by coating of the pyrolytic carbon using tumbling chemical vapor deposition

    International Nuclear Information System (INIS)

    Han, Young-Soo; Lee, Jai-Young

    2003-01-01

    The electrochemical characteristics of graphite coated with pyrolytic carbon materials using tumbling chemical vapor deposition (CVD) process have been studied for the active material of anodes in lithium ion secondary batteries. Coating of pyrolytic carbons on the surface of graphite particles, which tumble in a rotating reactor tube, was performed through the pyrolysis of liquid propane gas (LPG). The surface morphology of these graphite particles coated with pyrolytic carbon has been observed with scanning electron microscopy (SEM). The surface of graphite particles can well be covered with pyrolytic carbon by tumbling CVD. High-resolution transmission electron microscopy (HRTEM) image of these carbon particles shows that the core part is highly ordered carbon, while the shell part is disordered carbon. We have found that the new-type carbon obtained from tumbling CVD has a uniform core (graphite)-shell (pyrolytic carbon) structure. The electrochemical property of the new-type carbons has been examined using a charge-discharge cycler. The coating of pyrolytic carbon on the surface of graphite can effectively reduce the initial irreversible capacity by 47.5%. Cyclability and rate-capability of theses carbons with the core-shell structure are much better than those of bare graphite. From electrochemical impedance spectroscopy (EIS) spectra, it is found that the coating of pyrolytic carbon on the surface of graphite causes the decrease of the contact resistance in the carbon electrodes, which means the formation of solid electrolyte interface (SEI) layer is suppressed. We suggest that coating of pyrolytic carbon by the tumbling CVD is an effective method in improving the electrochemical properties of graphite electrodes for lithium ion secondary batteries

  9. The formation of FHA coating on biodegradable Mg-Zn-Zr alloy using a two-step chemical treatment method

    Science.gov (United States)

    Jiang, S. T.; Zhang, J.; Shun, S. Z.; Chen, M. F.

    2016-12-01

    To improve the corrosion resistance of the biomedical magnesium alloy, a two-step chemical treatment method has been employed to prepare an FHA coating on the alloy surface. Prior to forming an FHA layer, the samples of Mg-3 wt% Zn-0.5 wt% Zr alloy were soaked in HF with concentration of 20% (v/v) at 37 °C temperature for 2 h, and were then placed into an aqueous solution with 0.1 mol/L Ca(NO3).4H2O and 0.06 mol/L NH4H2PO4 at 90 °C to prepare the Ca-P coating. The concentrations of Mg2+, F- ions, and pH variation with immersing time in the solution were investigated to explore the growth mechanism of FHA. The surface morphologies and compositions of the coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the alloy surface treated with acid formed a layer of MgF2 nanoparticles with a thickness of 0.7 μm. The corrosion resistance of coatings in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the substrate with FHA coating had good corrosion resistance. After immersing into the calcium phosphate solution, some small spherical particles were first formed on the surface; these then cover the surface completely after 20 min. Some clusters consisting of needle-like crystal were observed in the spherical particles covering the surface, and the Ca/P ratio of the needle-like crystal was 1.46, clearly growing along the c axis preferred orientation growth. After immersion for 60 min, the FHA coating with completely uniform growth was obtained on the Mg-Zn-Zr alloy surface with its thickness reaching about 120 μm.

  10. Alcoholysis: A Promising Technology for Conversion of Lignocellulose and Platform Chemicals.

    Science.gov (United States)

    Zhu, Shanhui; Guo, Jing; Wang, Xun; Wang, Jianguo; Fan, Weibin

    2017-06-22

    In the catalytic conversion of lignocellulose to valuable products, the first entry point is to break down these biopolymers to sugar units or aromatic monomers, which is conventionally achieved by hydrolysis in water medium. Recent years have seen tremendous progress in the alcoholysis process, which has remarkable advantages, such as the avoidance of treating waste water, suppression of humins or chars, and enhancement of reaction rate and product yield. Advances have been focused on the alcoholysis of cellulose, hemicellulose, and lignin to alkyl glucosides, xylosides, and aromatic monomers, respectively. Alcoholysis of the platform molecule furfuryl alcohol (FAL) to alkyl levulinate (AL) and integrated alcoholysis of cellulose and furfural into AL are also summarized. This Minireview highlights the comparisons between alcoholysis and hydrolysis, the reaction mechanism of alcoholysis, and future challenges for industrial applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Plasma-Sprayed Hydroxylapatite-Based Coatings: Chemical, Mechanical, Microstructural, and Biomedical Properties

    Science.gov (United States)

    Heimann, Robert B.

    2016-06-01

    This contribution discusses salient properties and functions of hydroxylapatite (HA)-based plasma-sprayed coatings, including the effect on biomedical efficacy of coating thickness, phase composition and distribution, amorphicity and crystallinity, porosity and surface roughness, cohesion and adhesion, micro- and nano-structured surface morphology, and residual coating stresses. In addition, it will provide details of the thermal alteration that HA particles undergo in the extremely hot plasma jet that leads to dehydroxylated phases such as oxyhydroxylapatite (OHA) and oxyapatite (OA) as well as thermal decomposition products such as tri-(TCP) and tetracalcium phosphates (TTCP), and quenched phases such as amorphous calcium phosphate (ACP). The contribution will further explain the role of ACP during the in vitro interaction of the as-deposited coatings with simulated body fluid resembling the composition of extracellular fluid (ECF) as well as the in vivo responses of coatings to the ECF and the host tissue, respectively. Finally, it will briefly describe performance profiles required to fulfill biological functions of osteoconductive bioceramic coatings designed to improve osseointegration of hip endoprostheses and dental root implants. In large parts, the content of this contribution is a targeted review of work done by the author and his students and coworkers over the last two decades. In addition, it is considered a stepping stone toward a standard operation procedure aimed at depositing plasma-sprayed bioceramic implant coatings with optimum properties.

  12. Effect of chemical composition of steel on the structure of hot – dip galvanized coating

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2016-01-01

    Full Text Available This article describes the effect of the content of conventional steel impurity elements on the thickness and composition of the zinc layer. This article is focused primarily on low-temperature, batch hot-dip galvanizing; however, the continuous coating process is also mentioned. The main discussion covers galvanizing from pure zinc melt, and only touches on galvanizing from melts with the usual amounts of aluminium (0,2 wt. %. Silicon, phosphorus, aluminium and sulfur may have an especially negative effect on the mechanical properties of the coating and its final appearance. The content of ballast carbon and manganese has a rather limited effect on composition and coating thickness.

  13. Chemically bonded ceramic matrix composites: Densification and conversion to diffusion bonding

    International Nuclear Information System (INIS)

    Johnson, B.R.; Guelguen, M.A.; Kriven, W.M.

    1995-01-01

    Chemically bonded ceramics appear to be a promising alternative route for near-net shape fabrication of multi-phase ceramic matrix composites (CMC's). The hydraulic (and refractory) properties of fine mono-calcium aluminate (CaAl 2 O 4 ) powders were used as the chemically bonding matrix phase, while calcia stabilized zirconia powders were the second phase material. Samples containing up to 70 wt% (55 vol%) zirconia have been successfully compacted and sintered. Various processing techniques were evaluated. Processing was optimized based on material properties, dilatometry and simultaneous thermal analysis (DTA/TGA). The physical characteristics of this novel CMC were characterized by hardness, density, and fracture toughness testing. Microstructures were evaluated by SEM and phase identification was verified using XRD

  14. The effect of cerium-based conversion treatment on the cathodic delamination and corrosion protection performance of carbon steel-fusion-bonded epoxy coating systems

    Energy Technology Data Exchange (ETDEWEB)

    Ramezanzadeh, B., E-mail: ramezanzadeh@aut.ac.ir [Department of Surface Coatings and Corrosion, Institute for Color Science and Technology (ICST), 16765-654, Tehran (Iran, Islamic Republic of); Rostami, M. [Department of Nanomaterials and Nanocoatings, Institute for Color Science and Technology (ICST), 16765-654, Tehran (Iran, Islamic Republic of)

    2017-01-15

    Highlights: • Steel surface was treated by Ce and acid phosphoric solutions. • Ce treatment considerably enhanced the surface energy and produce nanoscale roughness. • Ce treated samples showed enhanced adhesion to FBE coating. • Ce treatment of steel significantly reduced the FBE cathodic delamination rate. • Ce treated sample showed enhanced corrosion resistance. - Abstract: The effect of surface pre-treatment of pipe surface by green cerium compound and phosphoric acid solution on the fusion-bonded epoxy (FBE) coating performance was studied. The composition and surface morphology of the steel samples treated by acid and Ce solutions were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), equipped with energy dispersive spectroscopy (EDS). Also, the surface free energy was evaluated on these samples through contact angle measurements. In addition, the effect of Ce and acid washing procedures on the adhesion properties and corrosion protection performance of the FBE was examined by pull-off, salt spray and electrochemical impedance spectroscopy (EIS) tests. Results showed that compared to acid washing, the chemical treatment by Ce solution noticeably increased the surface free energy of steel, improved the adhesion properties of FBE, decreased the cathodic delamination rate of FBE, and enhanced the coating corrosion resistance compared to the acid washed samples.

  15. Overview of recent advances in thermo-chemical conversion of biomass

    International Nuclear Information System (INIS)

    Zhang Linghong; Xu Chunbao; Champagne, Pascale

    2010-01-01

    Energy from biomass, bioenergy, is a perspective source to replace fossil fuels in the future, as it is abundant, clean, and carbon dioxide neutral. Biomass can be combusted directly to generate heat and electricity, and by means of thermo-chemical and bio-chemical processes it can be converted into bio-fuels in the forms of solid (e.g., charcoal), liquid (e.g., bio-oils, methanol and ethanol), and gas (e.g., methane and hydrogen), which can be used further for heat and power generation. This paper provides an overview of the principles, reactions, and applications of four fundamental thermo-chemical processes (combustion, pyrolysis, gasification, and liquefaction) for bioenergy production, as well as recent developments in these technologies. Some advanced thermo-chemical processes, including co-firing/co-combustion of biomass with coal or natural gas, fast pyrolysis, plasma gasification and supercritical water gasification, are introduced. The advantages and disadvantages, potential for future applications and challenges of these processes are discussed. The co-firing of biomass and coal is the easiest and most economical approach for the generation of bioenergy on a large-sale. Fast pyrolysis has attracted attention as it is to date the only industrially available technology for the production of bio-oils. Plasma techniques, due to their high destruction and reduction efficiencies for any form of waste, have great application potential for hazardous waste treatment. Supercritical water gasification is a promising approach for hydrogen generation from biomass feedstocks, especially those with high moisture contents.

  16. Chemical looping combustion: A new low-dioxin energy conversion technology.

    Science.gov (United States)

    Hua, Xiuning; Wang, Wei

    2015-06-01

    Dioxin production is a worldwide concern because of its persistence and carcinogenic, teratogenic, and mutagenic effects. The pyrolysis-chemical looping combustion process of disposing solid waste is an alternative to traditional solid waste incineration developed to reduce the dioxin production. Based on the equilibrium composition of the Deacon reaction, pyrolysis gas oxidized by seven common oxygen carriers, namely, CuO, NiO, CaSO4, CoO, Fe2O3, Mn3O4, and FeTiO3, is studied and compared with the pyrolysis gas directly combusted by air. The result shows that the activity of the Deacon reaction for oxygen carriers is lower than that for air. For four typical oxygen carriers (CuO, NiO, Fe2O3, and FeTiO3), the influences of temperature, pressure, gas composition, and tar on the Deacon reaction are discussed in detail. According to these simulation results, the dioxin production in China, Europe, the United States, and Japan is predicted for solid waste disposal by the pyrolysis-chemical looping combustion process. Thermodynamic analysis results in this paper show that chemical looping combustion can reduce dioxin production in the disposal of solid waste. Copyright © 2015. Published by Elsevier B.V.

  17. Basic mechanisms of photosynthesis and applications to improved production and conversion of biomass to fuels and chemical products

    Energy Technology Data Exchange (ETDEWEB)

    El-Sayed, M. [Georgia Institute of Tech., Atlanta, GA (United States); Greenbaum, E. [Oak Ridge National Laboratory, TN (United States); Wasielewski, M. [Argonne National Lab., IL (United States)

    1996-09-01

    Natural photosynthesis, the result of 3.5 billion years of evolutionary experimentation, is the best proven, functional solar energy conversion technology. It is responsible for filling the vast majority of humanity`s energy, nutritional, and materials needs. Understanding the basic physical chemical principles underlying photosynthesis as a working model system is vital to further exploitation of this natural technology. These principles can be used to improve or modify natural photosynthesis so that it is more efficient or so that it can produce unusual products such as hydrogen, methane, methanol, ethanol, diesel fuel substitutes, biodegradable materials, or other high value chemical products. Principles garnered from the natural process can also be used to design artificial photosynthetic devices that employ analogs of natural antenna and reaction center function, self-assembly and repair concepts, photoinduced charge transfer processes, photoprotection, and dark reactions that facilitate catalytic action to convert light into, useful chemical or electrical energy. The present broad understanding of many structural and functional aspects of photosynthesis has resulted from rapid recent research progress. X-ray structures of several key photosynthetic reaction centers and antenna systems are available, and the overall principles controlling photoinduced energy and electron transfer are being established.

  18. Project W-314 Polyurea Special Protective Coating (SPC) Test Plan Chemical Compatibility and Physical Characteristics Testing

    International Nuclear Information System (INIS)

    MAUSER, R.W.

    2001-01-01

    This Test Plan outlines the testing to be done on the Special Protective Coating (SPC) Polyurea which includes: Tank Waste Compatibility, Decontamination Factor Testing, and Adhesion Strength Testing after a sample has been exposed to Radiation

  19. Thermochemical Conversion of Woody Biomass to Fuels and Chemicals Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Pendse, Hemant P. [Univ. of Maine, Orono, ME (United States)

    2015-09-30

    Maine and its industries identified more efficient utilization of biomass as a critical economic development issue. In Phase I of this implementation project, a research team was assembled, research equipment was implemented and expertise was demonstrated in pyrolysis, hydrodeoxygenation of pyrolysis oils, catalyst synthesis and characterization, and reaction engineering. Phase II built upon the infrastructure to innovate reaction pathways and process engineering, and integrate new approaches for fuels and chemical production within pulp and paper and other industries within the state. This research cluster brought together chemists, engineers, physicists and students from the University of Maine, Bates College, and Bowdoin College. The project developed collaborations with Oak Ridge National Laboratory and Brookhaven National Laboratory. The specific research projects within this proposal were of critical interest to the DoE - in particular the biomass program within EERE and the catalysis/chemical transformations program within BES. Scientific and Technical Merit highlights of this project included: (1) synthesis and physical characterization of novel size-selective catalyst/supports using engineered mesoporous (1-10 nm diameter pores) materials, (2) advances in fundamental knowledge of novel support/ metal catalyst systems tailored for pyrolysis oil upgrading, (3) a microcalorimetric sensing technique, (4) improved methods for pyrolysis oil characterization, (5) production and characterization of woody biomass-derived pyrolysis oils, (6) development of two new patented bio oil pathways: thermal deoxygenation (TDO) and formate assisted pyrolysis (FASP), and (7) technoeconomics of pyrolysis of Maine forest biomass. This research cluster has provided fundamental knowledge to enable and assess pathways to thermally convert biomass to hydrocarbon fuels and chemicals.

  20. Chemical vapour deposition at atmospheric pressure of graphene on molybdenum foil: Effect of annealing time on characteristics and corrosion stability of graphene coatings

    International Nuclear Information System (INIS)

    Naghdi, Samira; Jevremović, Ivana; Mišković-Stanković, Vesna; Rhee, Kyong Yop

    2016-01-01

    Highlights: • Atmospheric pressure chemical vapor deposition of graphene on molybdenum foils. • Quality and domain size of graphene layers increased with longer annealing times. • The number of graphene layers decreased with longer annealing times. • Graphene coatings on molybdenum foils exhibited corrosion inhibitive properties. - Abstract: In this work, the effect of pre-annealing of Mo substrate on the quality of graphene layers grown by chemical vapour deposition was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. Moreover, different electrochemical techniques were employed to investigate the corrosion stability of the graphene coated Mo in 0.1 M NaCl. Longer annealing time resulted in less defective graphene coatings with fewer layers. Graphene coating on the annealed Mo provided better protection against corrosion during the initial exposure times, while after prolonged exposure times, both graphene coatings on annealed and non-annealed Mo exhibited nearly the same corrosion inhibitive properties.

  1. An integrated biorefinery concept for conversion of sugar beet pulp into value-added chemicals and pharmaceutical intermediates.

    Science.gov (United States)

    Cárdenas-Fernández, Max; Bawn, Maria; Hamley-Bennett, Charlotte; Bharat, Penumathsa K V; Subrizi, Fabiana; Suhaili, Nurashikin; Ward, David P; Bourdin, Sarah; Dalby, Paul A; Hailes, Helen C; Hewitson, Peter; Ignatova, Svetlana; Kontoravdi, Cleo; Leak, David J; Shah, Nilay; Sheppard, Tom D; Ward, John M; Lye, Gary J

    2017-09-21

    Over 8 million tonnes of sugar beet are grown annually in the UK. Sugar beet pulp (SBP) is the main by-product of sugar beet processing which is currently dried and sold as a low value animal feed. SBP is a rich source of carbohydrates, mainly in the form of cellulose and pectin, including d-glucose (Glu), l-arabinose (Ara) and d-galacturonic acid (GalAc). This work describes the technical feasibility of an integrated biorefinery concept for the fractionation of SBP and conversion of these monosaccharides into value-added products. SBP fractionation is initially carried out by steam explosion under mild conditions to yield soluble pectin and insoluble cellulose fractions. The cellulose is readily hydrolysed by cellulases to release Glu that can then be fermented by a commercial yeast strain to produce bioethanol at a high yield. The pectin fraction can be either fully hydrolysed, using physico-chemical methods, or selectively hydrolysed, using cloned arabinases and galacturonases, to yield Ara-rich and GalAc-rich streams. These monomers can be separated using either Centrifugal Partition Chromatography (CPC) or ultrafiltration into streams suitable for subsequent enzymatic upgrading. Building on our previous experience with transketolase (TK) and transaminase (TAm) enzymes, the conversion of Ara and GalAc into higher value products was explored. In particular the conversion of Ara into l-gluco-heptulose (GluHep), that has potential therapeutic applications in hypoglycaemia and cancer, using a mutant TK is described. Preliminary studies with TAm also suggest GluHep can be selectively aminated to the corresponding chiral aminopolyol. The current work is addressing the upgrading of the remaining SBP monomer, GalAc, and the modelling of the biorefinery concept to enable economic and Life Cycle Analysis (LCA).

  2. Metalorganic chemical vapor deposition of iron disulfide and its use for solar energy conversion

    Science.gov (United States)

    Ennaoui, Ahmed; Fiechter, Sebastian; Vogel, Ralf; Giersig, M.; Weller, Horst; Tributsch, Helmut

    1992-12-01

    Thin polycrystalline films of iron disulfide have been grown on different substrates by chemical vapour deposition. The films were characterized using optical absorption and TEM. RBS and EDAX analysis has been used to explore the chemical stoichiometry. XRD and FTIR allowed the identification of both FeS2 phases pyrite and marcasite. A novel method for sensitization of highly porous Ti02 elecrodes with ultra thin (10-20 nm) polycrystalline films of FeS2 (pyrite) is presented. Photoelectrochemical solar cell using the above electrode generated high photovoltage of up to 600mV compared with single crystalline electrode (200 mV). In this device the semiconductor with a small band gap and high absorption coefficient (FeS2 pyrite; EG = 0.9 eV; a = 6 x 105 cm-1) absorbs the light and injects electrons into the conduction band the wide band gap semiconductor (Ti02 anatase; EG = 3.2 eV). Regeneration of holes is taking place by electron transfer from redox system in the electrolyte.

  3. All-chemical YBa2Cu3O7 coated conductors on IBAD-YSZ stainless steel substrates

    International Nuclear Information System (INIS)

    Pomar, A; Cavallaro, A; Coll, M; Gazquez, J; Palau, A; Sandiumenge, F; Puig, T; Obradors, X; Freyhardt, H C

    2006-01-01

    We report on the fabrication of all-chemical YBa 2 Cu 3 O 7 coated conductors on IBAD-YSZ (IBAD stands for ion beam assisted deposition; YSZ is yttrium stabilized zirconia) stainless steel substrates. YBCO films were grown by the trifluoroacetates route on top of CeO 2 buffer layers made by metal-organic decomposition. The achievement of atomically flat CeO 2 surfaces is found to be a key factor for obtaining clean interfaces with YBCO and high performance. Coated conductors with percolative critical currents of J c GB (65 K) = 1.8 MA cm -2 were achieved. The determination of the intra-grain critical current J c G from inductive measurements suggests that the limiting factor for J c GB is the YBCO in-plane texture, which is already of higher quality than that of the IBAD-YSZ cap layer. (rapid communication)

  4. Residual stress in thick low-pressure chemical-vapor deposited polycrystalline SiC coatings on Si substrates

    Science.gov (United States)

    Choi, D.; Shinavski, R. J.; Steffier, W. S.; Spearing, S. M.

    2005-04-01

    Residual stress in thick coatings of polycrystalline chemical-vapor deposited SiC on Si substrates is a key variable that must be controlled if SiC is to be used in microelectromechanical systems. Studies have been conducted to characterize the residual stress level as a function of deposition temperature, Si wafer and SiC coating thickness, and the ratios of methyltrichlorosilane to hydrogen and hydrogen chloride. Wafer curvature was used to monitor residual stress in combination with a laminated plate analysis. Compressive intrinsic (growth) stresses were measured with magnitudes in the range of 200-300MPa; however, these can be balanced with the tensile stress due to the thermal-expansion mismatch to leave near-zero stress at room temperature. The magnitude of the compressive intrinsic stress is consistent with previously reported values of surface stress in combination with the competition between grain-boundary energy and elastic strain energy.

  5. Effect of NiO/SiO2 on thermo-chemical conversion of waste cooking oil to hydrocarbons

    Directory of Open Access Journals (Sweden)

    J. Sani

    2017-05-01

    Full Text Available Increase in organic waste generation, dwindling nature of global oil reserves coupled with environmental challenges caused by waste oil disposal and burning of fossil fuels necessitated the need for alternative energy resources. Waste cooking oil obtained from the frying fish outlet was analyzed for its physicochemical properties using ASTM D-975 methods. Acid and Iodine values of the oil were 30.43 ± 0.32 mgKOH/g and 57.08 ± 0.43 mgI2/100 g respectively. Thermo-chemical conversion of the oil using NiO/SiO2 at different reaction conditions (pressure, temperature, and catalyst concentration at a residence time of 3 h yielded 33.63% hydrocarbons. Hydro-catalytic pyrolysis of waste cooking oil at 400 °C, H2 pressure of 15 bars, and catalyst to oil ratio of 0.25 g/100 cm3 resulted in highest hydrocarbon yield (41.98%. The fuel properties of the product were: cetane number (71.16, high heating value (41.43 MJ/kg, kinematic viscosity (2.01 mm2/s, density (0.94 g/ml, saponification value (185.1 ± 3.96 mgKOH/g, and iodine value (20.57 ± 0.20 I2/100 g respectively. These results show that the NiO/SiO2 could be a suitable catalyst for conversion of waste vegetable oil to hydrocarbons. Keywords: Energy, Chemical engineering

  6. Study of the conversion of lignocellulosic (aspen) materials to liquid fuels and chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Pepper, J M; Eager, R L; Mathews, J F

    1979-01-01

    Studies were completed on the use of the small-scale semi-continuous reactor whereby lignocellulosic materials may be converted into a fuel oil. Changes in design and operation were made and further data obtained as a result of studies of the following parameters: pretreatment with sulfuric acid, operating pressure, presence or absence of CO, and nature of feedstock. The major study has centered around the design, construction and testing of a small-scale continuous reactor whose operation was based upon the use of a newly designed screw unit to compress and deliver the wood meal to the reactor site. Chemical studies on oils were obtained from both wood and cellulose. Semi-continuous reactor experiments were run to demonstrate that proto oil could be made continuously under conditions similar to batch runs, and to outline the ranges of the process variable in which satisfactory operation can be maintained for extended periods of time. 7 refs., 4 figs., 5 tabs.

  7. Chemical and physical conversion in cold atmosphere and the effect of radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kulmala, M.; Aalto, P.; Korhonen, P.; Laaksonen, A.; Vesala, T. [Helsinki Univ. (Finland). Dept. of Physics

    1996-12-31

    The project is focusing on the formation and growth mechanisms of atmospheric aerosol and cloud droplets. Both aerosol particles and cloud droplets affect strongly on the atmospheric radiation fluxes by scattering and absorption. The droplet formation results from physical and chemical processes occurring simultaneously. The studies concerning the tropospheric cloud droplet formation, laboratory experiments with a cloud chamber and stratospheric cloud formation are summarized. The recent studies summarized in this presentation indicate that both aerosol particles and cloud droplets have a significant role in climatic change and ozone depletion problems. The anthropogenic emissions of gaseous and particulate pollutants change the properties of atmospheric aerosols and cloud droplets. The research in this field will be continued and more quantitative understanding based both experimental and theoretical studies is required

  8. Biological conversion of carbon dioxide and hydrogen into liquid fuels and industrial chemicals.

    Science.gov (United States)

    Hawkins, Aaron S; McTernan, Patrick M; Lian, Hong; Kelly, Robert M; Adams, Michael W W

    2013-06-01

    Non-photosynthetic routes for biological fixation of carbon dioxide into valuable industrial chemical precursors and fuels are moving from concept to reality. The development of 'electrofuel'-producing microorganisms leverages techniques in synthetic biology, genetic and metabolic engineering, as well as systems-level multi-omic analysis, directed evolution, and in silico modeling. Electrofuel processes are being developed for a range of microorganisms and energy sources (e.g. hydrogen, formate, electricity) to produce a variety of target molecules (e.g. alcohols, terpenes, alkenes). This review examines the current landscape of electrofuel projects with a focus on hydrogen-utilizing organisms covering the biochemistry of hydrogenases and carbonic anhydrases, kinetic and energetic analyses of the known carbon fixation pathways, and the state of genetic systems for current and prospective electrofuel-producing microorganisms. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Chemical and physical conversion in cold atmosphere and the effect of radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kulmala, M; Aalto, P; Korhonen, P; Laaksonen, A; Vesala, T [Helsinki Univ. (Finland). Dept. of Physics

    1997-12-31

    The project is focusing on the formation and growth mechanisms of atmospheric aerosol and cloud droplets. Both aerosol particles and cloud droplets affect strongly on the atmospheric radiation fluxes by scattering and absorption. The droplet formation results from physical and chemical processes occurring simultaneously. The studies concerning the tropospheric cloud droplet formation, laboratory experiments with a cloud chamber and stratospheric cloud formation are summarized. The recent studies summarized in this presentation indicate that both aerosol particles and cloud droplets have a significant role in climatic change and ozone depletion problems. The anthropogenic emissions of gaseous and particulate pollutants change the properties of atmospheric aerosols and cloud droplets. The research in this field will be continued and more quantitative understanding based both experimental and theoretical studies is required

  10. Studies of coupled chemical and catalytic coal conversion methods. Tenth quarterly report, January--March 1990

    Energy Technology Data Exchange (ETDEWEB)

    Stock, L.M.

    1990-12-31

    This report concerns our research on base-catalyzed coal solubilization and a new approach for hydrogen addition. The work on base-catalyzed, chemical solubilization is continuing. this report is focused on the hydrogenation research. Specifically it deals with the use of arene chromium carbonyl complexes as reagents for the addition of dideuterium to coal molecules. In one phase of the work, he has established that the aromatic hydrocarbons in a representative coal liquid can be converted in very good yield to arene chromium carbonyl compounds. In a second phase of the work directly related to our objective of improved methods for catalytic hydrogenation, he has established that the aromatic constituents of the same coal liquid add dideuterium in the presence of added napththalene chromium carbonyl.

  11. Experimental setup for producing tungsten coated graphite tiles using plasma enhanced chemical vapor deposition technique for fusion plasma applications

    International Nuclear Information System (INIS)

    Chauhan, Sachin Singh; Sharma, Uttam; Choudhary, K.K.; Sanyasi, A.K.; Ghosh, J.; Sharma, Jayshree

    2013-01-01

    Plasma wall interaction (PWI) in fusion grade machines puts stringent demands on the choice of materials in terms of high heat load handling capabilities and low sputtering yields. Choice of suitable material still remains a challenge and open topic of research for the PWI community. Carbon fibre composites (CFC), Beryllium (Be), and Tungsten (W) are now being considered as first runners for the first wall components of future fusion machines. Tungsten is considered to be one of the suitable materials for the job because of its superior properties than carbon like low physical sputtering yield and high sputter energy threshold, high melting point, fairly high re-crystallization temperature, low fuel retention capabilities, low chemical sputtering with hydrogen and its isotopes and most importantly the reparability with various plasma techniques both ex-situ and in-situ. Plasma assisted chemical vapour deposition is considered among various techniques as the most preferable technique for fabricating tungsten coated graphite tiles to be used as tokamak first wall and target components. These coated tiles are more favourable compared to pure tungsten due to their light weight and easier machining. A system has been designed, fabricated and installed at SVITS, Indore for producing tungsten coated graphite tiles using Plasma Enhanced Chemical Vapor Deposition (PE-CVD) technique for Fusion plasma applications. The system contains a vacuum chamber, a turbo-molecular pump, two electrodes, vacuum gauges, mass analyzer, mass flow controllers and a RF power supply for producing the plasma using hydrogen gas. The graphite tiles will be put on one of the electrodes and WF6 gas will be inserted in a controlled manner in the hydrogen plasma to achieve the tungsten-coating with WF6 dissociation. The system is integrated at SVITS, Indore and a vacuum of the order of 3*10 -6 is achieved and glow discharge plasma has been created to test all the sub-systems. The system design with

  12. Synthesis of polystyrene coated SiC nanowires as fillers in a polyurethane matrix for electromechanical conversion

    Energy Technology Data Exchange (ETDEWEB)

    Rybak, Andrzej; Warde, Micheline; Bechelany, Mikhael; Brioude, Arnaud; Toury, Berangere; Cornu, David; Miele, Philippe [Laboratoire des Multimateriaux et Interfaces, UMR 5615 CNRS, Universite Lyon 1, Universite de Lyon, 43 Boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France); Beyou, Emmanuel; Chaumont, Philippe [Ingenierie des Materiaux Polymeres, UMRCNRS 5223, Laboratoire des Materiaux Polymeres et des Biomateriaux, Universite Lyon 1, Universite de Lyon, 15 Boulevard Latarget, 69622 Villeurbanne Cedex (France); Guiffard, Benoit; Seveyrat, Laurence; Guyomar, Daniel, E-mail: beyou@univ-lyon1.fr, E-mail: David.Cornu@iemm.univ-montp2.fr [Laboratoire de Genie Electrique et Ferroelectricite, LGEF-INSA Lyon, Batiment Gustave Ferrie, 8 rue de la Physique, F-69621 Villeurbanne Cedex (France)

    2010-04-09

    Grafting of polystyrene (PS) from silica coating of silicon carbide nanowires (SiCNWs) has been performed by a two-step nitroxide mediated free radical polymerization (NMP) of styrene. First, an alkoxyamine based on N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide (DEPN) was covalently attached onto NWs through free surface silanol groups. To immobilize the alkoxyamine initiator on the silica surface, alkoxylamine was formed in situ by the simultaneous reaction of polymerizable acryloxy propyl trimethoxysilane (APTMS), azobis isobutyronitrile (AIBN), and DEPN, which was used as a radical trap. Polystyrene chains with controlled molecular weights and narrow polydispersity were then grown from the alkoxyamine-functionalized NWs surface in the presence of a 'free' sacrificial styrylDEPN alkoxyamine. Both the initiator and polystyrene chains were characterized by FTIR and {sup 13}C solid-state NMR and quantified by TGA. Ensuing nanocomposites were characterized by FEG-SEM, TEM and Raman spectroscopy. EDX analysis performed on functionalized nanowires during FEG-SEM analysis also gave evidence of grafting by a strong increase in the average C/Si atomic ratio. Incorporation of 2 wt% NWs into the polyurethane (PU) matrix has been carried out to prepare homogeneous nanocomposite films. The electric field induced thickness strain response has been investigated for the polystyrene-grafted silica coated SiC NWs (PU-SiC-SiO{sub 2}-PS) nanocomposites and compared to pure polyurethane film and PU-SiC-SiO{sub 2} nanocomposite without polystyrene grafting. At a moderate electric field of 10 V {mu}m{sup -1}, SiC-SiO{sub 2}-PS loading increased the strain level of pure PU by a factor of 2.2. This improvement came partially due to polystyrene grafting since PU-SiC-SiO{sub 2} films showed only a 1.7 times increase. The observed higher strain response of these nanocomposites makes them very attractive for micro-electromechanical applications.

  13. Conversion of chemical energy in an explosive by a magnetohydrodynamic method

    International Nuclear Information System (INIS)

    Lebedev, E.F.; Ostashev, V.E.; Svetsov, G.A.

    1983-01-01

    In this paper, the authors examine different methods for realizing the MHD method for converting chemical energy of a condensed explosive into pulsed electrical energy. It is shown that explosive MHD generators, which are compact sources of powerful pulses of electrical energy, are characterized by their relative simplicity, autonomy and maneuverability of firing and they are capable of operating in the frequency-periodic mode. A number of projects have been proposed for explosive MHD generators in the megajoule range. Practical experience has been gained in creating frequency-periodic action generators as well as autonomous setups using superconducting magnetic systems. The increase in the operational efficiency of an explosive MHD generator is primarily related to increasing the magnetic Reynolds number of the flow, which can be attained, in particular, by using different schemes for accumulating the energy of the explosion. The use of a metallic liner, which expands under the pressure of the detonation products, in an explosive MHD generator is, in the practical sense, apparently hopeless. The general information available on the parameters and properties of explosive MHD generators gives a basis for concluding that this generator is a promising source of powerful energy pulses. In a certain range of parameters, it can be an alternative to the use of conventional high-energy pulse devices

  14. Conversion of KCl into KBH4 by Mechano-Chemical Reaction and its Catalytic Decomposition

    Science.gov (United States)

    Bilen, Murat; Gürü, Metin; Çakanyildirim, Çetin

    2017-07-01

    Production of KBH4, in the presence of KCl, B2O3 and MgH2 by means of a mechanical reaction and a dehydrogenation kinetic, constitute the main parts of this study. Operating time and reactant ratio are considered as two parameters for the mechanical reaction to obtain the maximum yield. The production process was carried out in a ball milling reactor, and the product residue was purified with ethylene diamine (EDA) and subsequently characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and x-ray Diffraction (XRD) analyses. Optimum time for mechano-chemical treatment and reactant ratio (MgH2/KCl) were obtained as 1000 min and 1.0, respectively. Synthesized and commercial KBH4 were compared by hydrolysis tests in the presence of Co1-xNix/Al2O3 heterogeneous catalyst. Hydrogen generation rates, activation energy and order of the KBH4 decomposition reaction were obtained as 1578 {mL}_{{{{H}}2 }} \\min^{ - 1} {g}_{{catalyst}}^{ - 1}, 39.2 kJ mol-1 and zero order, respectively.

  15. Main routes for the thermo-conversion of biomass into fuels and chemicals. Part 1: Pyrolysis systems

    International Nuclear Information System (INIS)

    Balat, Mustafa; Balat, Mehmet; Kirtay, Elif; Balat, Havva

    2009-01-01

    Since the energy crises of the 1970s, many countries have become interest in biomass as a fuel source to expand the development of domestic and renewable energy sources and reduce the environmental impacts of energy production. Biomass is used to meet a variety of energy needs, including generating electricity, heating homes, fueling vehicles and providing process heat for industrial facilities. The methods available for energy production from biomass can be divided into two main categories: thermo-chemical and biological conversion routes. There are several thermo-chemical routes for biomass-based energy production, such as direct combustion, liquefaction, pyrolysis, supercritical water extraction, gasification, air-steam gasification and so on. The pyrolysis is thermal degradation of biomass by heat in the absence of oxygen, which results in the production of charcoal (solid), bio-oil (liquid), and fuel gas products. Pyrolysis liquid is referred to in the literature by terms such as pyrolysis oil, bio-oil, bio-crude oil, bio-fuel oil, wood liquid, wood oil, liquid smoke, wood distillates, pyroligneous tar, and pyroligneous acid. Bio-oil can be used as a fuel in boilers, diesel engines or gas turbines for heat and electricity generation.

  16. Recent progress in the development of solid catalysts for biomass conversion into high value-added chemicals

    Science.gov (United States)

    Hara, Michikazu; Nakajima, Kiyotaka; Kamata, Keigo

    2015-06-01

    In recent decades, the substitution of non-renewable fossil resources by renewable biomass as a sustainable feedstock has been extensively investigated for the manufacture of high value-added products such as biofuels, commodity chemicals, and new bio-based materials such as bioplastics. Numerous solid catalyst systems for the effective conversion of biomass feedstocks into value-added chemicals and fuels have been developed. Solid catalysts are classified into four main groups with respect to their structures and substrate activation properties: (a) micro- and mesoporous materials, (b) metal oxides, (c) supported metal catalysts, and (d) sulfonated polymers. This review article focuses on the activation of substrates and/or reagents on the basis of groups (a)-(d), and the corresponding reaction mechanisms. In addition, recent progress in chemocatalytic processes for the production of five industrially important products (5-hydroxymethylfurfural, lactic acid, glyceraldehyde, 1,3-dihydroxyacetone, and furan-2,5-dicarboxylic acid) as bio-based plastic monomers and their intermediates is comprehensively summarized.

  17. Recent progress in the development of solid catalysts for biomass conversion into high value-added chemicals

    International Nuclear Information System (INIS)

    Hara, Michikazu; Nakajima, Kiyotaka; Kamata, Keigo

    2015-01-01

    In recent decades, the substitution of non-renewable fossil resources by renewable biomass as a sustainable feedstock has been extensively investigated for the manufacture of high value-added products such as biofuels, commodity chemicals, and new bio-based materials such as bioplastics. Numerous solid catalyst systems for the effective conversion of biomass feedstocks into value-added chemicals and fuels have been developed. Solid catalysts are classified into four main groups with respect to their structures and substrate activation properties: (a) micro- and mesoporous materials, (b) metal oxides, (c) supported metal catalysts, and (d) sulfonated polymers. This review article focuses on the activation of substrates and/or reagents on the basis of groups (a)–(d), and the corresponding reaction mechanisms. In addition, recent progress in chemocatalytic processes for the production of five industrially important products (5-hydroxymethylfurfural, lactic acid, glyceraldehyde, 1,3-dihydroxyacetone, and furan-2,5-dicarboxylic acid) as bio-based plastic monomers and their intermediates is comprehensively summarized. (focus issue review)

  18. Recent progress in the development of solid catalysts for biomass conversion into high value-added chemicals

    Science.gov (United States)

    Hara, Michikazu; Nakajima, Kiyotaka; Kamata, Keigo

    2015-01-01

    In recent decades, the substitution of non-renewable fossil resources by renewable biomass as a sustainable feedstock has been extensively investigated for the manufacture of high value-added products such as biofuels, commodity chemicals, and new bio-based materials such as bioplastics. Numerous solid catalyst systems for the effective conversion of biomass feedstocks into value-added chemicals and fuels have been developed. Solid catalysts are classified into four main groups with respect to their structures and substrate activation properties: (a) micro- and mesoporous materials, (b) metal oxides, (c) supported metal catalysts, and (d) sulfonated polymers. This review article focuses on the activation of substrates and/or reagents on the basis of groups (a)–(d), and the corresponding reaction mechanisms. In addition, recent progress in chemocatalytic processes for the production of five industrially important products (5-hydroxymethylfurfural, lactic acid, glyceraldehyde, 1,3-dihydroxyacetone, and furan-2,5-dicarboxylic acid) as bio-based plastic monomers and their intermediates is comprehensively summarized. PMID:27877800

  19. Nano-hydroxyapatite colloid suspension coated on chemically modified porous silicon by cathodic bias: a suitable surface for cell culture

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Alejandra [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Electroquimica y Energia Quimica de la Universidad de Costa Rica (CELEQ), Universidad de Costa Rica, 2060 (Costa Rica); Gonzalez, Jerson [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Garcia-Pineres, Alfonso [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Investigacion en Biologia Celular y Molecular (CIBCM), Universidad de Costa Rica, 2060 (Costa Rica); Montero, Mavis L. [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Electroquimica y Energia Quimica de la Universidad de Costa Rica (CELEQ), Universidad de Costa Rica, 2060 (Costa Rica); Centro de Ciencia e Ingenieria en Materiales (CICIMA), Universidad de Costa Rica, 2060 (Costa Rica)

    2011-06-15

    The properties of porous silicon make it an interesting material for biological applications. However, porous silicon is not an appropriate surface for cell growth. Surface modification is an alternative that could afford a bioactive material. In this work, we report a method to yield materials by modification of the porous silicon surface with hydroxyapatite of nanometric dimensions, produced using an electrochemical process and coated on macroporous silicon substrates by cathodic bias. The chemical nature of the calcium phosphate deposited on the substrates after the experimental process and the amount of cell growth on these surfaces were characterized. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Mechanisms of radiation - chemical conversion of high-paraffinic crude oil

    International Nuclear Information System (INIS)

    Zaikin, Yu.A.; Zaikina, R.F.; Silverman, J.

    2002-01-01

    Complete text of publication follows. Regularities of radiation-thermal cracking (RTC) are studied in high-paraffinic oil. Irradiation of oil samples by 2 MeV electrons was performed using a special facility assembled at the electron accelerator ELU-4. The following characteristic RTC features were observed in oil with high contents of heavy paraffins: low level of isomerization in light RTC fractions; very high polymerization rate and low olefin contents in RTC products; relatively low yields of light fractions at low irradiation dose rates; increase in the molecular weight of the gasoline fraction as the irradiation dose rate grows. Similar intense polymerization of RTC products was observed in our experiments with such wastes of oil extraction as asphalt-pitch-paraffin sediments (APPS). Theoretically this feedstock contains great reserves of hydrogen, and, therefore, has high potential yields of light fractions. However, in this case RTC was accompanied by intense reactions of polymerization and chemical adsorption that limited the maximum yields of light RTC products to 40% in our experiments. A specific feature of APPS radiation-induced destruction is formation of the big amount of a reactive paraffinic residue. As a result of interaction with the polymerizing residue the light liquid fractions were completely absorbed and the heavy residue got denser and solidified after several days of exposure at room temperature. RTC regularities in heavy paraffinic oil differ from those observed both in highly viscous petroleum feedstock and light paraffin oils. We attribute these observations to the behavior of heavy alkyl radicals that initiate polymerization and isomerization in heavy paraffin fractions

  1. Conformal coating of Ni(OH)2 nanoflakes on carbon fibers by chemical bath deposition for efficient supercapacitor electrodes

    KAUST Repository

    Alhebshi, Nuha

    2013-01-01

    A novel supercapacitor electrode structure has been developed in which a uniform and conformal coating of nanostructured Ni(OH)2 flakes on carbon microfibers is deposited in situ by a simple chemical bath deposition process at room temperature. The microfibers conformally coated with Ni(OH) 2 nanoflakes exhibit five times higher specific capacitance compared to planar (non-conformal) Ni(OH)2 nanoflake electrodes prepared by drop casting of Ni(OH)2 powder on the carbon microfibers (1416 F g-1vs. 275 F g-1). This improvement in supercapacitor performance can be ascribed to the preservation of the three-dimensional structure of the current collector, which is a fibrous carbon fabric, even after the conformal coating of Ni(OH)2 nanoflakes. The 3-D network morphology of the fibrous carbon fabric leads to more efficient electrolyte penetration into the conformal electrode, allowing the ions to have greater access to active reaction sites. Cyclic stability testing of the conformal and planar Ni(OH)2 nanoflake electrodes, respectively, reveals 34% and 62% drop in specific capacitance after 10 000 cycles. The present study demonstrates the crucial effect that electrolyte penetration plays in determining the pseudocapacitive properties of the supercapacitor electrodes. © 2013 The Royal Society of Chemistry.

  2. Mathematical modelling of simultaneous solvent evaporation and chemical curing in thermoset coatings: A parameter study

    DEFF Research Database (Denmark)

    Kiil, Søren

    2011-01-01

    A mathematical model, describing the curing behaviour of a two-component, solvent-based, thermoset coating, is used to conduct a parameter study. The model includes curing reactions, solvent intra-film diffusion and evaporation, film gelation, vitrification, and crosslinking. A case study with a ...

  3. Chemical, biochemical, and microbiological aspects of chitosan quaternary salt as active coating on sliced apples

    Directory of Open Access Journals (Sweden)

    Douglas de Britto

    2012-09-01

    Full Text Available The biocompatibility of chitosan and chitosan quaternary salt coatings was evaluated for use as edible coatings for sliced apple. Measurement of water loss, color change, and fungal growth appearance were monitored as a function of time. A significant brownish effect was observed on chitosan coated slices, varying greatly from L* = 76.5 and Hue angle = 95.9° (t = 0 to L* = 45.3 and Hue angle = 69.8° (t = 3 days, whilst for TMC coated samples the variation was considerable lower (L* = 74.1; Hue angle = 95.0° to (L* = 67.0; Hue angle = 83.8° within the same period. The hydrosoluble derivative N,N,N-trimethylchitosan demonstrated good antifungal activity against P. expansum although highly dependent on the polymer properties such as degree of quaternization. The most efficient formulation was that prepared from derivative having a degree of quaternization of 45%, high solubility, and high viscosity. This formulation restrained fungus spreading up to 30%, while for the control it reached almost 80% of the total assessed surfaces during 7 days of storage.

  4. A coupled mechanical-chemical model for reflecting the influence of stress on oxidation reactions in thermal barrier coating

    Science.gov (United States)

    Chen, Lin; Yueming, Li

    2018-06-01

    In this paper, a coupled mechanical-chemical model is established based on the thermodynamic framework, in which the contribution of chemical expansion to free energy is introduced. The stress-dependent chemical potential equilibrium at the gas-solid interface and the stress gradient-dependent diffusion equation as well as a so-called generalized force which is conjugate to the oxidation rate are derived from the proposed model, which could reflect the influence of stresses on the oxidation reaction. Based on the proposed coupled mechanical-chemical model, a user element subroutine is developed in ABAQUS. The numerical simulation of the high temperature oxidation in the thermal barrier coating is carried out to verify the accuracy of the proposed model, and then the influence of stresses on the oxidation reaction is investigated. In thermally grown oxide, the considerable stresses would be induced by permanent volumetric swelling during the oxidation. The stresses play an important role in the chemical potential equilibrium at the gas-solid interface and strongly affect the oxidation reaction. The gradient of the stresses, however, only occurs in the extremely thin oxidation front layer, which plays a very limited role in the oxidation reaction. The generalized force could be divided into the stress-dependent and the stress-independent parts. Comparing with the stress-independent part, the stress-dependent part is smaller, which has little influence on oxidation reaction.

  5. Operating parameters effect on physico-chemical characteristics of nanocrystalline apatite coatings electrodeposited on 316L stainless steel

    Science.gov (United States)

    Pham, Thi Nam; Thanh Dinh, Thi Mai; Thom Nguyen, Thi; Phuong Nguyen, Thu; Kergourlay, E.; Grossin, D.; Bertrand, G.; Pebere, N.; Marcelin, S. J.; Charvillat, C.; Drouet, C.

    2017-09-01

    Hydroxyapatite (HAp) was known as a bone implant material due to its biocompatibility, bioactive, chemical stability and its compositional similarity to natural bone. In this work nanocrystalline HAp coatings were prepared on 316L stainless steel (316LSS) substrates using a potentio-dynamic method (potential scanning in the range from 0 to  -1.6 V/SCE) in the presence of dissolved 3  ×  10-2 M Ca(NO3)2  +  1.8  ×  10-2 M NH4H2PO4  +  0.15 M NaNO3 and 6% H2O2 (w/w). We report the influence of experimental conditions such as temperature (25 °C-60 °C), scanning rate (1 mV s-1-10 mV s-1) and scanning times (1 times-7 times) on the morphology, structure and composition of the HAp coatings by FTIR, XRD and SEM analysis. The results show that the morphology and purity of the HAp coating were greatly affected by temperature, scanning rate and reaction time with rate of 5 mV s-1, reaction time of 26.67 min (corresponding 5 scanning times) and 25 °C, giving better coatings. The in vivo test results after 3 months grafting on femur of dogs of HAp/316LSS material showed that: the material did not induce any osteitis, osteomyelitis or structural abnormalities. The osteitis and osteomyelitis were not observed in microscopy images.

  6. Structural and chemical analysis of process residue from biochemical conversion of wheat straw (Triticum aestivum L.) to ethanol

    DEFF Research Database (Denmark)

    Hansen, Mads Anders Tengstedt; Jørgensen, Henning; Laursen, Kristian Holst

    2013-01-01

    Biochemical conversion of lignocellulose to fermentable carbohydrates for ethanol production is now being implemented in large-scale industrial production. Applying hydrothermal pretreatment and enzymatic hydrolysis for the conversion process, a residue containing substantial amounts of lignin...

  7. Aging study on carboxymethyl cellulose-coated zero-valent iron nanoparticles in water: Chemical transformation and structural evolution

    International Nuclear Information System (INIS)

    Dong, Haoran; Zhao, Feng; Zeng, Guangming; Tang, Lin; Fan, Changzheng; Zhang, Lihua; Zeng, Yalan; He, Qi; Xie, Yankai; Wu, Yanan

    2016-01-01

    Highlights: • The chemical transformation and structural evolution of CMC-nZVI were investigated. • CMC could slow down the aging rate of nZVI and alter the species transformation. • Fe_3O_4 and/or γ-Fe_2O_3 are the dominant corrosion products of bare nZVI after aging. • γ-FeOOH is the primary corrosion product of CMC-nZVI after aging. - Abstract: To assess the long-term fate and the associated risks of nanoscale zero-valent iron (nZVI) used in the water remediation, it is essential to understand the chemical transformations during aging of nZVI in water. This study investigated the compositional and structural evolution of bare nZVI and carboxymethyl cellulose (CMC) coated nZVI in static water over a period of 90 days. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize the corrosion products of nZVI and CMC-nZVI. Results show that both the structures and the compositions of the corrosion products change with the process of aging, but the coating of CMC could slow down the aging rate of nZVI (as indicated by the slower drop in Fe"0 intensity in XRD pattern). For the bare nZVI, magnetite (Fe_3O_4) and/or maghemite (γ-Fe_2O_3) are the dominant corrosion products after 90 days of aging. However, for the CMC-nZVI, the core-shell spheres collapses to acicular-shaped structures after aging with crystalline lepidocrocite (γ-FeOOH) as the primary end product. Moreover, more lepidocrocite present in the corrosion products of CMC-nZVI with higher loading of CMC, which reveals that the CMC coating could influence the transformation of iron oxides.

  8. Development of a combined piezoresistive pressure and temperature sensor using a chemical protective coating for Kraft pulp digester process monitoring

    International Nuclear Information System (INIS)

    Mohammadi, Abdolreza R; Chiao, Mu; Bennington, Chad P J

    2011-01-01

    We have developed an integrated piezoresistive pressure and temperature sensor for multiphase chemical reactors, primarily Kraft pulp digesters (pH 13.5, temperatures up to 175 °C, reaching a local maximum of 180 °C and pressures up to 2 MPa). The absolute piezoresistive pressure sensor consisted of a large square silicon diaphragm (1000 × 1000 µm 2 ) and high resistance piezoresistors (10 000 Ω). A 4500 Ω buried piezoresistive wire was patterned on the silicon chip to form a piezoresistive temperature sensor which was used for pressure sensor compensation and temperature measurement. A 4 µm thick Parylene HT® coating, a chemically resistant epoxy and a silicone conformal coating were deposited to passivate the pressure sensor against the caustic environment in Kraft digesters. The sensors were characterized up to 2 MPa and 180 °C in an environment chamber. A maximum thermal error of ±0.72% full-scale output (FSO), an average sensitivity of 0.116 mV (V kPa) −1 and a power consumption of 0.3 mW were measured in the pressure sensor. The sensors' resistances were measured before and after test in a Kraft pulping cycle and showed no change in their values. SEM pictures and topographical surfaces were also analyzed before and after pulp liquor exposure and showed no observable changes.

  9. Gentamicin coating of plasma chemical oxidized titanium alloy prevents implant-related osteomyelitis in rats.

    Science.gov (United States)

    Diefenbeck, M; Schrader, C; Gras, F; Mückley, T; Schmidt, J; Zankovych, S; Bossert, J; Jandt, K D; Völpel, A; Sigusch, B W; Schubert, H; Bischoff, S; Pfister, W; Edel, B; Faucon, M; Finger, U

    2016-09-01

    Implant related infection is one of the most feared and devastating complication associated with the use of orthopaedic implant devices. Development of anti-infective surfaces is the main strategy to prevent implant contamination, biofilm formation and implant related osteomyelitis. A second concern in orthopaedics is insufficient osseointegration of uncemented implant devices. Recently, we reported on a macroporous titanium-oxide surface (bioactive TiOB) which increases osseointegration and implant fixation. To combine enhanced osseointegration and antibacterial function, the TiOB surfaces were, in addition, modified with a gentamicin coating. A rat osteomyelitis model with bilateral placement of titanium alloy implants was employed to analyse the prophylactic effect of gentamicin-sodiumdodecylsulfate (SDS) and gentamicin-tannic acid coatings in vivo. 20 rats were randomly assigned to four groups: (A) titanium alloy; PBS inoculum (negative control), (B) titanium alloy, Staphylococcus aureus inoculum (positive control), (C) bioactive TiOB with gentamicin-SDS and (D) bioactive TiOB plus gentamicin-tannic acid coating. Contamination of implants, bacterial load of bone powder and radiographic as well as histological signs of implant-related osteomyelitis were evaluated after four weeks. Gentamicin-SDS coating prevented implant contamination in 10 of 10 tibiae and gentamicin-tannic acid coating in 9 of 10 tibiae (infection prophylaxis rate 100% and 90% of cases, respectively). In Group (D) one implant showed colonisation of bacteria (swab of entry point and roll-out test positive for S. aureus). The interobserver reliability showed no difference in the histologic and radiographic osteomyelitis scores. In both gentamicin coated groups, a significant reduction of the histological osteomyelitis score (geometric mean values: C = 0.111 ± 0.023; D = 0.056 ± 0.006) compared to the positive control group (B: 0.244 ± 0.015; p < 0.05) was observed. The

  10. Uranium conversion

    International Nuclear Information System (INIS)

    Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina

    2006-03-01

    FOI, has performed a study on uranium conversion processes that are of importance in the production of different uranium compounds in the nuclear industry. The same conversion processes are of interest both when production of nuclear fuel and production of fissile material for nuclear weapons are considered. Countries that have nuclear weapons ambitions, with the intention to produce highly enriched uranium for weapons purposes, need some degree of uranium conversion capability depending on the uranium feed material available. This report describes the processes that are needed from uranium mining and milling to the different conversion processes for converting uranium ore concentrate to uranium hexafluoride. Uranium hexafluoride is the uranium compound used in most enrichment facilities. The processes needed to produce uranium dioxide for use in nuclear fuel and the processes needed to convert different uranium compounds to uranium metal - the form of uranium that is used in a nuclear weapon - are also presented. The production of uranium ore concentrate from uranium ore is included since uranium ore concentrate is the feed material required for a uranium conversion facility. Both the chemistry and principles or the different uranium conversion processes and the equipment needed in the processes are described. Since most of the equipment that is used in a uranium conversion facility is similar to that used in conventional chemical industry, it is difficult to determine if certain equipment is considered for uranium conversion or not. However, the chemical conversion processes where UF 6 and UF 4 are present require equipment that is made of corrosion resistant material

  11. Biomass valorisation by staged degasification A new pyrolysis-based thermochemical conversion option to produce value-added chemicals from lignocellulosic biomass

    NARCIS (Netherlands)

    de Wild, P. J.; den Uil, H.; Reith, J. H.; Kiel, J. H. A.; Heeres, H. J.

    Pyrolysis of lignocellulosic biomass leads to an array Of useful solid, liquid and gaseous products. Staged degasification is a pyrolysis-based conversion route to generate value-added chemicals from biomass. Because of different thermal stabilities of the main biomass constituents hemicellulose.

  12. Project W-314 Polyurea Special Protective Coating (SPC) Test Report Chemical Compatibility and Physical Characteristics Testing

    International Nuclear Information System (INIS)

    MAUSER, R.W.

    2001-01-01

    This Engineering Test report outlines the results obtained from testing polyurea on its decon factor, tank waste compatibility, and adhesion strength when subjected to a high level of gamma radiation. This report is used in conjunction with RPP-7187 Project W-314 Pit Coatings Repair Requirements Analysis, to document the fact polyurea meets the project W-314 requirements contained in HNF-SD-W314-PDS-005 and is therefore an acceptable SPC for use in W-314 pit refurbishments

  13. Chemical synthesis of nickel ferrite spinel designed as an insulating bilayer coating on ferromagnetic particles

    Czech Academy of Sciences Publication Activity Database

    Strečková, M.; Hadraba, Hynek; Bureš, R.; Fáberová, M.; Roupcová, Pavla; Kuběna, Ivo; Medvecký, L.; Girman, V.; Kollár, P.; Füzer, J.; Čižmár, E.

    2015-01-01

    Roč. 270, MAY (2015), s. 66-76 ISSN 0257-8972 R&D Projects: GA ČR(CZ) GA14-25246S; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : soft magnetic composite * NiFe2O4 spinel ferrite * coating * precipitation method * focused ion beam Subject RIV: JG - Metallurgy Impact factor: 2.139, year: 2015

  14. Chemical stability of the fiber coating/matrix interface in silicon-based ceramic matrix composites

    International Nuclear Information System (INIS)

    Lee, K.N.; Jacobson, N.S.

    1995-01-01

    Carbon and boron nitride are used as fiber coatings in silicon-based composites. In order to assess the long-term stability of these materials, reactions of carbon/Si 3 N 4 and BN/SiC were studied at high temperatures with Knudsen effusion, coupon tests, and by microstructural examination. in the carbon/Si 3 N 4 system, carbon reacted with Si 3 N 4 to form gaseous N 2 and SiC. The formation of SiC limited further reaction by physically separating the carbon and Si 3 N 4 . Consequently, the development of high p(N 2 ) at the interface, predicted from thermochemical calculations, did not occur, thus limiting the potential deleterious effects of the reaction on the composite. Strong indications of a reaction between BN and SiC were shown by TEM and SIMS analysis of the BN/SiC interface. In long-term exposures, this reaction can lead to a depletion of a BN coating and/or an unfavorable change of the interfacial properties, limiting the beneficial effects of the coating

  15. Chemical Stability of the Fiber Coating/Matrix Interface in Silicon-Based Ceramic Matrix Composites

    Science.gov (United States)

    Lee, Kang N.; Jacobson, Nathan S.

    1995-01-01

    Carbon and boron nitride are used as fiber coatings in silicon-based composites. In order to assess the long-term stability of these materials, reactions of carbon/Si3N4 and BN/SiC were studied at high temperatures with Knudsen effusion, coupon tests, and microstructural examination. In the carbon/Si3N4 system, carbon reacted with Si3N4 to form gaseous N2 and SiC. The formation of SiC limited further reaction by physically separating the carbon and Si3N4. Consequently, the development of high p(N2) at the interface, predicted from thermochemical calculations, did not occur, thus limiting the potential deleterious effects of the reaction on the composite. Strong indications of a reaction between BN and SiC were shown by TEM and SIMS analysis of the BN/SiC interface. In long-term exposures, this reaction can lead to a depletion of a BN coating and/or an unfavorable change of the interfacial properties, limiting the beneficial effects of the coating.

  16. A new electrothermal-chemical method for metals, carbides, and ceramics hard coating: Experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Zoler, D.; Bruma, C.; Cuperman, S.

    1999-07-01

    A new method and an experimental device for powders of metals, carbides and ceramics coating of various substrates are presented. The powder-particles are accelerated and heated by a mixture of plasma and gases resulted from the burning of an energetic (propellant). The operating prototype already allows one to obtain coatings of metals, carbides and ceramics. Some of the coatings obtained, especially those by carbides powders, indicate even at the present stage of research, properties (as hardness, porosity) which are comparable to those provided by the presently industrial methods in use. The accelerating-heating agent in the device (the plasma-gas mixture) is characterized by very high densities (up to 120 kg/m{sup 3}), temperatures (up to 20,000 K) and velocities (more than 1,500 m/s). Due to these characteristics, the powder particles are accelerated to velocities significantly higher than those reached in other coating devices as, for example, the detonation (D) gun. Some preliminary experimental data show that the accelerated particle can reach velocities higher than 1,000 m/s. In parallel, in order to better understand the phenomena taking place inside the device and to determine the optimal process parameters leading to high quality coatings an appropriate theoretical model was developed. The model is able to describe the complex processes of plasma-gas-propellant interaction, gas flow and powder particles heating and acceleration. The model gives a detailed description of the gas, propellant and accelerated particle parameters, their spatial distribution and temporal evolution; predicts their dependence on the values of some input quantities such as: the plasma energy, propellant characteristics and accelerated particles type and geometry. The computational results the authors obtained show that, indeed, during the acceleration process the particles are heated, melted and eventually vaporized. One of the most interesting theoretical results is that the

  17. Multifunctional surface modification of silk fabric via graphene oxide repeatedly coating and chemical reduction method

    Science.gov (United States)

    Cao, Jiliang; Wang, Chaoxia

    2017-05-01

    Multifunctional silk fabrics with electrical conductive, anti-ultraviolet and water repellent were successfully prepared by surface modification with graphene oxide (GO). The yellow-brown GO deposited on the surface of silk fabric was converted into graphitic black reduced graphene (RGO) by sodium hydrosulfite. The surface properties of silk fabrics were changed by repeatedly RGO coating process, which have been proved by SEM and XPS. The SEM results showed that the RGO sheets were successive form a continuously thin film on the surface of silk fabrics, and the deposition of GO or RGO also can be proved by XPS. The electrical conductivity was tested by electrical surface resistance value of the silk fabric, the surface resistance decreased with increasing of RGO surface modification times, and a low surface resistance value reached to 3.24 KΩ cm-1 after 9 times of modification, indicating the silk obtained excellent conductivity. The UPF value of one time GO modification silk fabric (silk-1RGO) was enhanced significantly to 24.45 in comparison to 10.40 of original silk. The contact angle of RGO coating silk samples was all above of 120°. The durability of RGO coated silk fabrics was tested by laundering. The electrical surface resistance of silk-4RGO (65.74 KΩ cm-1), silk-6RGO (15.54 KΩ cm-1) and silk-8RGO (3.86 KΩ cm-1) fabrics was up to 86.82, 22.30 and 6.57 KΩ cm-1 after 10 times of standard washing, respectively. The UPF value, contact angle and color differences of RGO modified silk fabric slightly changed before and after 10 times of standard washing. Therefore, the washing fastness of electric conduction, anti-ultraviolet and water repellent multifunctional silk fabrics was excellent.

  18. Combined chemical and EIS study of the reaction of zinc coatings under alkaline conditions

    International Nuclear Information System (INIS)

    Walkner, Sarah; Hassel, Achim Walter

    2014-01-01

    Graphical abstract: - Highlights: • An electrochemical unit for automatic EIS and pH modulation is used. • ZnMg2Al2 and ZnAl53 are studied in alkaline solutions. • Amount of consumed sodium hydroxide allows following hydroxide formation and film thickness. • Cross sections of 13 μm show excellent agreement with consumed hydroxide. • ZnAl53 consumes more hydroxide due to soluble aluminate formation. - Abstract: Two different zinc coatings of composition ZnMg2Al2 (Zn + 2 wt.% Mg + 2 wt.% Al) and ZnAl53 (Zn + 53 wt.% Al) were investigated in aqueous solution at pH 12.0 with a novel setup, the so-called impedance titrator. This device is able to perform electrochemical measurements including, but not limited to, impedance spectroscopy in dependency of different pH-values. The setup allows holding the pH-value with a precision of at least 0.05 by dosing the required amount of titrating agent to the system. If the alkaline pH region is investigated, hydroxide ions are consumed in the course of passive layer formation. The amount of consumed hydroxide allows to quantitatively follow the formation of the hydroxide film and its thickness. Cross section SEM shows an excellent agreement of 13 μm after 7 h for ZnMg2Al2. At a constant pH value, the hydroxide concentration is constant and film formation is well defined and kinetically characterised. The consumption of hydroxide by the ZnAl53 coating is higher resulting from the solubility of the Al as aluminate under alkaline conditions. The composition of the precipitates contains less than 3 wt.% of Al. The observed processes and the formation of corrosion products are recorded and differences in the behaviour of the two coatings are discussed

  19. Sensory and chemical stability in coated peanuts with the addition of essential oils and synthetic antioxidants

    Directory of Open Access Journals (Sweden)

    Olmedo, R. H.

    2012-03-01

    Full Text Available The objective of this work was to evaluate the antioxidant effect of essential oils on the oxidative stability of coated peanuts. Untreated coated peanuts (CP and treated coated peanuts with the addition of rosemary (CP-R, oregano (CP-O and laurel (CP-L essential oils and BHT (CPBHT were prepared. Peroxide values (PV and p-anisidine values (AV and the intensity ratings of sensory attributes by descriptive analysis were measured during 112 days of storage at room temperature (23°C. CP-BHT exhibited the lowest PV and AV increase. CP-R, CP-O and CP-L showed lower rates of increase in PV and AV than CP. The oxidized and cardboard flavor intensity ratings increased much more in CP during storage than the other studied products. CPBHT also showed the lowest increase in the intensity ratings of these sensory attributes. Three essential oils, namely, laurel, oregano and rosemary showed antioxidant activity and increased the shelf life of coated peanuts.

    El objetivo de este trabajo fue evaluar el efecto antioxidante de aceites esenciales sobre la estabilidad oxidativa en maní recubiertos. Se prepararon maníes recubiertos sin agregados (CP, y con el agregado de aceites esenciales de romero (CP-R, orégano (CP-O y laurel (CP-L y BHT (CPBHT. Se midieron, durante 112 días de almacenamiento, los valores de peróxidos (PV y p-anisidina (AV, y las intensidades de atributos sensoriales mediante análisis descriptivo. CP-BHT presentó el menor valor de PV y AV. CP-R, CP-O y CP-L tuvieron mayor PV y AV respecto a CP. Los valores de intensidad del sabor oxidado y cartón tuvieron un mayor incremento en CP durante el almacenamiento con respecto a los otros productos estudiados. La muestra CP-BHT también mostró los menores valores de intensidad de estos atributos sensoriales. Los aceites esenciales de laurel, orégano y romero presentaron actividad antioxidante e incrementaron la vida útil del maní recubierto.

  20. Antimicrobial activity of novel nanostructured Cu-SiO2 coatings prepared by chemical vapour deposition against hospital related pathogens.

    Science.gov (United States)

    Varghese, Sajnu; Elfakhri, Souad O; Sheel, David W; Sheel, Paul; Bolton, Frederick J Eric; Foster, Howard A

    2013-09-05

    There is increasing recognition that the healthcare environment acts as an important reservoir for transmission of healthcare acquired infections (HCAI). One method of reducing environmental contamination would be use of antimicrobial materials. The antimicrobial activity of thin silica-copper films prepared by chemical vapour deposition was evaluated against standard strains of bacteria used for disinfectant testing and bacteria of current interest in HCAI. The structure of the coatings was determined using Scanning Electron Microscopy and their hardness and adhesion to the substrate determined. Antimicrobial activity was tested using a method based on BS ISO 22196:2007. The coatings had a pale green-brown colour and had a similar hardness to steel. SEM showed nano-structured aggregates of Cu within a silica matrix. A log10 reduction in viability of >5 could be obtained within 4 h for the disinfectant test strains and within 6 h for producing Acinetobacter baumannii, Klebsiella pneumoniae and Stenotrophomonas maltophilia. Activity against the other hospital isolates was slower but still gave log10 reduction factors of >5 for extended spectrum β-lactamase producing Escherichia coli and >3 for vancomycin resistant Enterococcus faecium, methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa within 24 h. The results demonstrate the importance of testing antimicrobial materials destined for healthcare use against isolates of current interest in hospitals as well as standard test strains. The coatings used here can also be applied to substrates such as metals and ceramics and have potential applications where reduction of microbial environmental contamination is desirable.

  1. Hybrid Physical Chemical Vapor Deposition of Superconducting Magnesium Diboride Coatings for Large Scale Radio Frequency Cavities

    Science.gov (United States)

    Lee, Namhoon; Withanage, Wenura; Tan, Teng; Wolak, Matthaeus; Xi, Xiaoxing

    2016-03-01

    Magnesium diboride (MgB2) is considered to be a great candidate for next generation superconducting radio frequency (SRF) cavities due to its higher critical temperature Tc (40 K) and increased thermodynamic critical field Hc compared to other conventional superconductors. These properties significantly reduce the BCS surface resistance (RsBCS)and residual resistance (Rres) according to theoretical studies and suggest the possibility of an enhanced accelerating field (Eacc) . We have investigated the possibility of coating the inner surface of a 3 GHz SRF cavity with MgB2 by using a hybrid physical-vapor deposition (HPCVD) system which was modified for this purpose. To simulate a real 3 GHz SRF cavity, a stainless steel mock cavity has been employed for the study. The film quality was characterized on small substrates that were placed at selected locations within the cavity. MgB2 films on stainless steel foils, niobium pieces and SiC substrates showed transition temperatures of above 36 K. Dielectric resonance measurements resulted in promising Q values as obtained for the MgB2 films grown on the various substrates. By employing the HPCVD technique, a uniform film was achieved across the cavity interior, demonstrating the feasibility of HPCVD for MgB2 coatings for SRF cavities.

  2. Growth of CdS thin films on indium coated glass substrates via chemical bath deposition and subsequent air annealing

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Biswajit; Kumar, Kamlesh; Singh, Balwant Kr; Banerjee, Pushan; Das, Subrata, E-mail: neillohit@yahoo.co.in

    2014-11-30

    Graphical abstract: - Highlights: • CdS film grown on indium coated glass substrates via CBD and subsequent annealing. • Disappearance of the indium (1 1 2) peak confirms interdiffusion at 300 °C. • SIMS indicates the subsequent interdiffusion at progressively higher temperature. • Composite In–CdS layer showed lower photosensitivity compared to pure CdS. - Abstract: In the present work attempts were made to synthesize indium doped CdS films by fabricating In/CdS bilayers using CBD-CdS on vacuum evaporated In thin films and subsequent air annealing. 135 nm CdS films were grown onto 20 nm and 35 nm indium coated glass substrate employing chemical bath deposition technique. The In/CdS bilayers thus formed were subjected to heat treatment at the temperatures between 200 and 400 °C for 4 min in the muffle furnace to facilitate indium to diffuse into the CdS films. XRD pattern ascertained no noticeable shift in lattice constant implying grain boundary metal segregation, while secondary ion mass spectrometry indicated the diffusion profile of indium into CdS matrices. Mass spectrometry results showed that substantial diffusion of indium had been taken place within CdS at 400 °C. Dark and photocurrent with different illumination time were measured to ascertain the photosensitivity of pure and composite CdS films.

  3. Coating of diamond-like carbon nanofilm on alumina by microwave plasma enhanced chemical vapor deposition process.

    Science.gov (United States)

    Rattanasatien, Chotiwan; Tonanon, Nattaporn; Bhanthumnavin, Worawan; Paosawatyanyong, Boonchoat

    2012-01-01

    Diamond-like carbon (DLC) nanofilms with thickness varied from under one hundred to a few hundred nanometers have been successfully deposited on alumina substrates by microwave plasma enhanced chemical vapor deposition (MW-PECVD) process. To obtain dense continuous DLC nanofilm coating over the entire sample surface, alumina substrates were pre-treated to enhance the nucleation density. Raman spectra of DLC films on samples showed distinct diamond peak at around 1332 cm(-1), and the broad band of amorphous carbon phase at around 1550 cm(-1). Full width at half maximum height (FWHM) values indicated good formation of diamond phase in all films. The result of nano-indentation test show that the hardness of alumina samples increase from 7.3 +/- 2.0 GPa in uncoated samples to 15.8 +/- 4.5-52.2 +/- 2.1 GPa in samples coated with DLC depending on the process conditions. It is observed that the hardness values are still in good range although the thickness of the films is less than a hundred nanometer.

  4. Chemical bath deposited and dip coating deposited CuS thin films - Structure, Raman spectroscopy and surface study

    Science.gov (United States)

    Tailor, Jiten P.; Khimani, Ankurkumar J.; Chaki, Sunil H.

    2018-05-01

    The crystal structure, Raman spectroscopy and surface microtopography study on as-deposited CuS thin films were carried out. Thin films deposited by two techniques of solution growth were studied. The thin films used in the present study were deposited by chemical bath deposition (CBD) and dip coating deposition techniques. The X-ray diffraction (XRD) analysis of both the as-deposited thin films showed that both the films possess covellite phase of CuS and hexagonal unit cell structure. The determined lattice parameters of both the films are in agreement with the standard JCPDS as well as reported data. The crystallite size determined by Scherrer's equation and Hall-Williamsons relation using XRD data for both the as-deposited thin films showed that the respective values were in agreement with each other. The ambient Raman spectroscopy of both the as-deposited thin films showed major emission peaks at 474 cm-1 and a minor emmision peaks at 265 cm-1. The observed Raman peaks matched with the covellite phase of CuS. The atomic force microscopy of both the as-deposited thin films surfaces showed dip coating thin film to be less rough compared to CBD deposited thin film. All the obtained results are presented and deliberated in details.

  5. Density-controllable nonvolatile memory devices having metal nanocrystals through chemical synthesis and assembled by spin-coating technique

    International Nuclear Information System (INIS)

    Wang Guangli; Chen Yubin; Shi Yi; Pu Lin; Pan Lijia; Zhang Rong; Zheng Youdou

    2010-01-01

    A novel two-step method is employed, for the first time, to fabricate nonvolatile memory devices that have metal nanocrystals. First, size-averaged Au nanocrystals are synthesized chemically; second, they are assembled into memory devices by a spin-coating technique at room temperature. This attractive approach makes it possible to tailor the diameter and control the density of nanocrystals individually. In addition, processes at room temperature prevent Au diffusion, which is a main concern for the application of metal nanocrystal-based memory. The experimental results, both the morphology characterization and the electrical measurements, reveal that there is an optimum density of nanocrystal monolayer to balance between long data retention and a large hysteresis memory window. At the same time, density-controllable devices could also feed the preferential emphasis on either memory window or retention time. All these facts confirm the advantages and novelty of our two-step method. (semiconductor devices)

  6. Tensile test of a silicon microstructure fully coated with submicrometer-thick diamond like carbon film using plasma enhanced chemical vapor deposition method

    Science.gov (United States)

    Zhang, Wenlei; Uesugi, Akio; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

    2017-06-01

    This paper reports the tensile properties of single-crystal silicon (SCS) microstructures fully coated with sub-micrometer thick diamond like carbon (DLC) film using plasma enhanced chemical vapor deposition (PECVD). To minimize the deformations or damages caused by non-uniform coating of DLC, which has high compression residual stress, released SCS specimens with the dimensions of 120 µm long, 4 µm wide, and 5 µm thick were coated from the top and bottom side simultaneously. The thickness of DLC coating is around 150 nm and three different bias voltages were used for deposition. The tensile strength improved from 13.4 to 53.5% with the increasing of negative bias voltage. In addition, the deviation in strength also reduced significantly compared to bare SCS sample.

  7. Schiff Base Ligand Coated Gold Nanoparticles for the Chemical Sensing of Fe(III Ions

    Directory of Open Access Journals (Sweden)

    Abiola Azeez Jimoh

    2015-01-01

    Full Text Available New Schiff base-coated gold nanoparticles (AuNPs of type AuNP@L (where L: thiolated Schiff base ligand have been synthesized and characterized using various spectroscopic techniques. The AuNPs and AuNP@L were imaged by transmission electron microscopy (TEM and were confirmed to be well-dispersed, uniformly distributed, spherical nanoparticles with an average diameter of 8–10 nm. Their potential applications for chemosensing were investigated in UV-Vis and fluorescence spectroscopic studies. The AuNP@L exhibited selectivity for Fe3+ in an ethanol/water mixture (ratio 9 : 1 v/v. The absorption and emission spectral studies revealed a 1 : 1 binding mode for Fe3+, with binding constants of 8.5×105 and 2.9×105 M−1, respectively.

  8. Aging study on carboxymethyl cellulose-coated zero-valent iron nanoparticles in water: Chemical transformation and structural evolution

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Haoran, E-mail: dongh@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, Hunan 410082 (China); Zhao, Feng; Zeng, Guangming; Tang, Lin; Fan, Changzheng; Zhang, Lihua; Zeng, Yalan; He, Qi; Xie, Yankai; Wu, Yanan [College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, Hunan 410082 (China)

    2016-07-15

    Highlights: • The chemical transformation and structural evolution of CMC-nZVI were investigated. • CMC could slow down the aging rate of nZVI and alter the species transformation. • Fe{sub 3}O{sub 4} and/or γ-Fe{sub 2}O{sub 3} are the dominant corrosion products of bare nZVI after aging. • γ-FeOOH is the primary corrosion product of CMC-nZVI after aging. - Abstract: To assess the long-term fate and the associated risks of nanoscale zero-valent iron (nZVI) used in the water remediation, it is essential to understand the chemical transformations during aging of nZVI in water. This study investigated the compositional and structural evolution of bare nZVI and carboxymethyl cellulose (CMC) coated nZVI in static water over a period of 90 days. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize the corrosion products of nZVI and CMC-nZVI. Results show that both the structures and the compositions of the corrosion products change with the process of aging, but the coating of CMC could slow down the aging rate of nZVI (as indicated by the slower drop in Fe{sup 0} intensity in XRD pattern). For the bare nZVI, magnetite (Fe{sub 3}O{sub 4}) and/or maghemite (γ-Fe{sub 2}O{sub 3}) are the dominant corrosion products after 90 days of aging. However, for the CMC-nZVI, the core-shell spheres collapses to acicular-shaped structures after aging with crystalline lepidocrocite (γ-FeOOH) as the primary end product. Moreover, more lepidocrocite present in the corrosion products of CMC-nZVI with higher loading of CMC, which reveals that the CMC coating could influence the transformation of iron oxides.

  9. Diamond-like carbon coatings on a CoCrMo implant alloy: A detailed XPS analysis of the chemical states at the interface

    International Nuclear Information System (INIS)

    Mueller, U.; Falub, C.V.; Thorwarth, G.; Voisard, C.; Hauert, R.

    2011-01-01

    Low friction and wear resistant coatings have a long history of successful applications in industry. It has long been hoped that these coatings, especially diamond-like carbon (DLC), could also be used successfully in load-bearing joint implants, extending implant life time considerably. However, despite several medical studies carried out so far, no regular DLC-coated implants are available on the market. In most cases, failure was due to insufficient long-term stability of the adhesion of such coatings on implants in vivo. That is because introducing a coated implant not only brings the coating into contact with the body environment but also the interface that controls the adhesion. This usually reactively formed interface must be considered to be at least one additional material which must be not only biocompatible, but also unsusceptible to corrosive attack. The aim of this paper is to analyze in detail the interface, i.e., the transition region between the substrate and the coating. This knowledge is necessary in order to find the right measures to ensure the long-term stability of the adhesion. Results for DLC coatings on a cobalt-chromium-molybdenum alloy are presented. It is shown that a very thin interface layer is formed, with the alloy on one side and the carbon film on the other side. This layer consists of a mixture of carbides from all the metals of the base material. This result is obtained by means of measuring depth profiles using X-ray photoelectron spectroscopy because these spectra yield not only the chemical composition of the interface but a detailed analysis provides information on the chemical states across the interface.

  10. A solid-state nuclear magnetic resonance study of post-plasma reactions in organosilicone microwave plasma-enhanced chemical vapor deposition (PECVD) coatings.

    Science.gov (United States)

    Hall, Colin J; Ponnusamy, Thirunavukkarasu; Murphy, Peter J; Lindberg, Mats; Antzutkin, Oleg N; Griesser, Hans J

    2014-06-11

    Plasma-polymerized organosilicone coatings can be used to impart abrasion resistance and barrier properties to plastic substrates such as polycarbonate. Coating rates suitable for industrial-scale deposition, up to 100 nm/s, can be achieved through the use of microwave plasma-enhanced chemical vapor deposition (PECVD), with optimal process vapors such as tetramethyldisiloxane (TMDSO) and oxygen. However, it has been found that under certain deposition conditions, such coatings are subject to post-plasma changes; crazing or cracking can occur anytime from days to months after deposition. To understand the cause of the crazing and its dependence on processing plasma parameters, the effects of post-plasma reactions on the chemical bonding structure of coatings deposited with varying TMDSO-to-O2 ratios was studied with (29)Si and (13)C solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) using both single-pulse and cross-polarization techniques. The coatings showed complex chemical compositions significantly altered from the parent monomer. (29)Si MAS NMR spectra revealed four main groups of resonance lines, which correspond to four siloxane moieties (i.e., mono (M), di (D), tri (T), and quaternary (Q)) and how they are bound to oxygen. Quantitative measurements showed that the ratio of TMDSO to oxygen could shift the chemical structure of the coating from 39% to 55% in Q-type bonds and from 28% to 16% for D-type bonds. Post-plasma reactions were found to produce changes in relative intensities of (29)Si resonance lines. The NMR data were complemented by Fourier transform infrared (FTIR) spectroscopy. Together, these techniques have shown that the bonding environment of Si is drastically altered by varying the TMDSO-to-O2 ratio during PECVD, and that post-plasma reactions increase the cross-link density of the silicon-oxygen network. It appears that Si-H and Si-OH chemical groups are the most susceptible to post-plasma reactions. Coatings produced at a

  11. Thick boron carbide coatings for protection of tokamak first wall and divertor

    International Nuclear Information System (INIS)

    Buzhinskij, O.I.; Semenets, Yu.M.

    1999-01-01

    A review of characteristics of various types of boron carbide coatings considered as candidate materials for protection of tokamak inner surfaces against high energy heat fluxes is presented. Such coatings are produced by various methods: chemical vapor deposition by means of chloride and fluoride techniques, gas conversion, plasma spray and reaction-sintering. Contrary to pure carbon materials, B 4 C has much lower chemical and high-temperature sputtering, is capable to oxygen gettering and lower hydrogen recycling. In contrast to thin boronization films, the thick coatings can resist high heat fluxes such as in tokamak divertors. Comparative analysis shows that coatings produced by the diffusion methods, such as fluoride CVD and gas conversion, are more resistent to heat loads, and one of the most promising candidates are the fluoride CVD coatings. (orig.)

  12. Development of advanced mesostructured catalytic coatings on different substrates for fine chemical synthesis

    NARCIS (Netherlands)

    Protasova, L.N.

    2011-01-01

    Catalytic microstructured reactors are becoming widely recognized for their unique properties, such as high surface–to–volume ratios, isothermal conditions due to high heat transfer rates, enhanced safety, and potential applications in chemistry and in chemical industry. The efficient use of

  13. TEM Microstructure and Chemical Composition of Transition Zone Between Steel Tube and An Inconel 625 Weld Overlay Coating Produced by CMT Method

    Directory of Open Access Journals (Sweden)

    Rozmus-Górnikowska M.

    2017-06-01

    Full Text Available The aim of this work was to investigate the microstructure and chemical composition of the transition zone between 16Mo3 steel and Inconel 625 weld overlay coating produced by the Cold Metal Transfer (CMT method. Investigations were primarily carried out through transmission electron microscopy (TEM on thin foils prepared by FIB (Focus Ion Beam.

  14. Comparison study of different coatings on degradation performance and cell response of Mg-Sr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shangguan, Yongming [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Sun, Lina [Jinzhou Medical University, Jinzhou 121000 (China); Wan, Peng, E-mail: pwan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR (China); Tan, Lili [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Wang, Chengyue [Jinzhou Medical University, Jinzhou 121000 (China); Fan, Xinmin [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Qin, Ling [Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR (China); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2016-12-01

    To solve the problem of rapid degradation for magnesium-based implants, surface modification especially coating method is widely studied and showed the great potential for clinical application. However, as concerned to the further application and medical translation for biodegradable magnesium alloys, there are still lack of data and comparisons among different coatings on their degradation and biological properties. This work studied three commonly used coatings on Mg-Sr alloy, including micro-arc oxidation coating, electrodeposition coating and chemical conversion coating, and compared these coatings for requirements of favorable degradation and biological performances, how each of these coating systems has performed. Finally the mechanism for the discrepancy between these coatings is proposed. The results indicate that the micro-arc oxidation coating on Mg-Sr alloy exhibited the best corrosion resistance and cell response among these coatings, and is proved to be more suitable for the orthopedic application. - Highlights: • The MAO, PED and Sr-P coating were fabricated on Mg-Sr alloy to evaluate the degradation. • The MAO coating showed the greatest degradation performance among these three coatings. • The PED coating exhibited worse corrosion resistance even than Mg-Sr substrate. • The value of cell proliferation and ALP activity were ranked in the following order: MAO > Sr-P > PED.

  15. Comparison study of different coatings on degradation performance and cell response of Mg-Sr alloy

    International Nuclear Information System (INIS)

    Shangguan, Yongming; Sun, Lina; Wan, Peng; Tan, Lili; Wang, Chengyue; Fan, Xinmin; Qin, Ling; Yang, Ke

    2016-01-01

    To solve the problem of rapid degradation for magnesium-based implants, surface modification especially coating method is widely studied and showed the great potential for clinical application. However, as concerned to the further application and medical translation for biodegradable magnesium alloys, there are still lack of data and comparisons among different coatings on their degradation and biological properties. This work studied three commonly used coatings on Mg-Sr alloy, including micro-arc oxidation coating, electrodeposition coating and chemical conversion coating, and compared these coatings for requirements of favorable degradation and biological performances, how each of these coating systems has performed. Finally the mechanism for the discrepancy between these coatings is proposed. The results indicate that the micro-arc oxidation coating on Mg-Sr alloy exhibited the best corrosion resistance and cell response among these coatings, and is proved to be more suitable for the orthopedic application. - Highlights: • The MAO, PED and Sr-P coating were fabricated on Mg-Sr alloy to evaluate the degradation. • The MAO coating showed the greatest degradation performance among these three coatings. • The PED coating exhibited worse corrosion resistance even than Mg-Sr substrate. • The value of cell proliferation and ALP activity were ranked in the following order: MAO > Sr-P > PED.

  16. Zirconia sol-gel coatings deposited on 304 stainless steel for chemical protection in acid media

    International Nuclear Information System (INIS)

    Luna, F. Perdomo; Atik, M.; Avaca, Luis A.; Aegerter, M.A.

    1995-01-01

    Zr O 2 thin films were prepared by sol-gel method and using dip-coating technique for deposition on 304 austenitic stainless steel, from sonocatalyzed sols of zirconia alkoxide, isopropanol (Zr(O C 3 H 7 )4/C 3 H 7 OH = 0.5), glacial acetic acid and water (C H 3 CO OH/H 2 O = 0.5). The films were dried at 40 deg C/15 min and thermally treated in the air with a linear variation of 5 deg C/min and two isothermal holdings at 400 deg C during 1 h and afterwards at 800 deg C during several periods of time (up to 20 h). The film thickness ranges between 0.6 and 0.8 μm. Structure and morphology were studied by x-ray diffraction and scanning electron microscopy. The corrosion potential, the corrosion current density, the polarization resistance and the corrosion rate (mpy) in 1,0 N aqueous solution of H 2 SO 4 at room temperature were determined using potentiometric polarization curves with a scanning velocity of 1 mV/s. These films act as a blocking physical layer in the corrosion media and increase the substrate life time in a factor of 7

  17. Zirconia sol-gel coatings deposited on 304 stainless steel for chemical protection in acid media

    Energy Technology Data Exchange (ETDEWEB)

    Luna, F Perdomo; Atik, M; Avaca, Luis A; Aegerter, M A [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica

    1996-12-31

    Zr O{sub 2} thin films were prepared by sol-gel method and using dip-coating technique for deposition on 304 austenitic stainless steel, from sonocatalyzed sols of zirconia alkoxide, isopropanol (Zr(O C{sub 3} H{sub 7})4/C{sub 3} H{sub 7} OH = 0.5), glacial acetic acid and water (C H{sub 3} CO OH/H{sub 2} O = 0.5). The films were dried at 40 deg C/15 min and thermally treated in the air with a linear variation of 5 deg C/min and two isothermal holdings at 400 deg C during 1 h and afterwards at 800 deg C during several periods of time (up to 20 h). The film thickness ranges between 0.6 and 0.8 {mu}m. Structure and morphology were studied by x-ray diffraction and scanning electron microscopy. The corrosion potential, the corrosion current density, the polarization resistance and the corrosion rate (mpy) in 1,0 N aqueous solution of H{sub 2} SO{sub 4} at room temperature were determined using potentiometric polarization curves with a scanning velocity of 1 mV/s. These films act as a blocking physical layer in the corrosion media and increase the substrate life time in a factor of 7 16 refs., 3 figs., 1 tab.

  18. Optical fibre sensor coated with porous silica layers for gas and chemical vapour detection

    Czech Academy of Sciences Publication Activity Database

    Abdelghani, A.; Chovelon, J. M.; Jaffrezic-Renault, N.; Lacroix, M.; Gagnaire, H.; Veillas, C.; Berková, Daniela; Chomát, Miroslav; Matějec, Vlastimil

    B44, l/3 (1997), s. 495-498 ISSN 0925-4005 R&D Projects: GA ČR GA102/95/0871; GA ČR GA102/96/0939 Grant - others:EU COPERNICUS(XE) CIPA-CT94-0140 Keywords : nonelectric sensing devices * optical fibres * chemical sensors * sol-gel processing Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 0.858, year: 1997

  19. The Influence of Chemical Alloying on the High Temperature Wear Resistance of H-Free DLC Coatings

    NARCIS (Netherlands)

    Galvan, D.; Pei, Y.T.; Hosson, J.T.M. De; Cavaleiro, A.; Chandra, T; Tsuzaki, K; Militzer, M; Ravindran, C

    2007-01-01

    A commercial RF-sputtering deposition rig was employed to deposit H-free diamond-like carbon (DLC) coatings. The influence of alloying elements such as Ti and Si on the structure, mechanical and tribological properties of the coatings was investigated. The coating was observed in cross section and

  20. Silicon Nitride Antireflection Coatings for Photovoltaic Cells

    Science.gov (United States)

    Johnson, C.; Wydeven, T.; Donohoe, K.

    1984-01-01

    Chemical-vapor deposition adapted to yield graded index of refraction. Silicon nitride deposited in layers, refractive index of which decreases with distance away from cell/coating interface. Changing index of refraction allows adjustment of spectral transmittance for wavelengths which cell is most effective at converting light to electric current. Average conversion efficiency of solar cells increased from 8.84 percent to 12.63 percent.

  1. New sol–gel refractory coatings on chemically-bonded sand cores for foundry applications to improve casting surface quality

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Poulsen, T.; Stage, R.K.

    2011-01-01

    Foundry refractory coatings protect bonded sand cores and moulds from producing defective castings during the casting process by providing a barrier between the core and the liquid metal. In this study, new sol–gel refractory coating on phenolic urethane cold box (PUCB) core was examined. The coa......Foundry refractory coatings protect bonded sand cores and moulds from producing defective castings during the casting process by providing a barrier between the core and the liquid metal. In this study, new sol–gel refractory coating on phenolic urethane cold box (PUCB) core was examined......–gel coated cores have better surface quality than those from uncoated cores and comparable surface quality with the commercial coatings. Therefore, the new sol–gel coating has a potential application in the foundry industry for improving the surface finish of castings thereby reducing the cost of fettling...

  2. Observation of high coercive fields in chemically synthesized coated Fe-Pt nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Dalavi, Shankar B.; Panda, Rabi N., E-mail: rnp@goa.bits-pilani.ac.in

    2017-04-15

    Nanocrystalline Fe-Pt alloys have been synthesized via chemical reduction route using various capping agents; such as: oleic acid/oleylamine (route-1) and oleic acid/CTAB (route-2). We could able to synthesize Fe50Pt and Fe54Pt alloys via route 1 and 2, respectively. As-prepared Fe-Pt alloys crystallize in disordered fcc phase with crystallite sizes of 2.3 nm and 6 nm for route-1 and route-2, respectively. Disordered Fe-Pt alloys were transformed to ordered fct phase after annealing at 600 °C. SEM studies confirm the spherical shape morphologies of annealed Fe-Pt nanoparticles with SEM particle sizes of 24.4 nm and 21.2 nm for route-1 and route-2, respectively. TEM study confirms the presence of 4.6 nm particles for annealed Fe50Pt alloys with several agglomerating clusters of bigger size and appropriately agrees well with the XRD study. Room temperature magnetization studies of as-prepared Fe-Pt alloys (fcc) show ferromagnetism with negligible coercivities. Average magnetic moments per particle for as-prepared Fe-Pt alloys were estimated to be 753 μ{sub B} and 814 μ{sub B}, for route 1 and 2, respectively. Ordered fct Fe-Pt alloys show high values of coercivities of 10,000 Oe and 10,792 Oe for route-1 and route-2, respectively. Observed magnetic properties of the fct Fe-Pt alloys nps were interpreted with the basis of order parameters, size, surface, and composition effects. - Highlights: • Synthesis of capped nanocrystalline Fe-Pt alloys via chemical routes. • Ordered fct phase were obtained at 600 °C. • Microstructural studies were carried out using SEM and TEM. • Investigation on evolution of magnetic properties from fcc to fct state. • Maximum values of coercivities up to 10,792 Oe were observed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-11-29

    Fuel cladding chemical interactions (FCCI) have been acknowledged as a critical issue in a metallic fuel/steel cladding system due to the formation of low melting intermetallic eutectic compounds between the fuel and cladding steel, resulting in reduction in cladding wall thickness as well as a formation of eutectic compounds that can initiate melting in the fuel at lower temperature. In order to mitigate FCCI, diffusion barrier coatings on the cladding inner surface have been considered. In order to generate the required coating techniques, pack cementation, electroplating, and electrophoretic deposition have been investigated. However, these methods require a high processing temperature of above 700 oC, resulting in decarburization and decomposition of the martensites in a ferritic/martensitic (F/M) cladding steel. Alternatively, organometallic chemical vapor deposition (OMCVD) can be a promising process due to its low processing temperature of below 600 oC. The aim of the project is to conduct applied and fundamental research towards the development of diffusion barrier coatings on the inner surface of F/M fuel cladding tubes. Advanced cladding steels such as T91, HT9 and NF616 have been developed and extensively studied as advanced cladding materials due to their excellent irradiation and corrosion resistance. However, the FCCI accelerated by the elevated temperature and high neutron exposure anticipated in fast reactors, can have severe detrimental effects on the cladding steels through the diffusion of Fe into fuel and lanthanides towards into the claddings. To test the functionality of developed coating layer, the diffusion couple experiments were focused on using T91 as cladding and Ce as a surrogate lanthanum fission product. By using the customized OMCVD coating equipment, thin and compact layers with a few micron between 1.5 µm and 8 µm thick and average grain size of 200 nm and 5 µm were successfully obtained at the specimen coated between 300oC and

  4. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    Science.gov (United States)

    Wallenhorst, L. M.; Loewenthal, L.; Avramidis, G.; Gerhard, C.; Militz, H.; Ohms, G.; Viöl, W.

    2017-07-01

    In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  5. Solar Photocatalytic Removal of Chemical and Bacterial Pollutants from Water Using Pt/TiO2-Coated Ceramic Tiles

    Directory of Open Access Journals (Sweden)

    S. P. Devipriya

    2012-01-01

    Full Text Available Semiconductor photocatalysis has become an increasingly promising technology in environmental wastewater treatment. The present work reports a simple technique for the preparation of platinum-deposited TiO2 catalysts and its immobilization on ordinary ceramic tiles. The Pt/TiO2 is characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDAX, and diffuse reflectance spectroscopy (DRS. Deposition of Pt on TiO2 extends the optical absorption of the latter to the visible region which makes it attractive for solar energy application. Optimum loading of Pt on TiO2 was found to be 0.5%. The Pt/TiO2 is coated on ceramic tiles and immobilized. This catalyst was found effective for the solar photocatalytic removal of chemical and bacterial pollutants from water. Once the parameters are optimized, the Pt/TiO2/tile can find application in swimming pools, hospitals, water theme parks, and even industries for the decontamination of water.

  6. Chemical Conversion Pathways and Kinetic Modeling for the OH-Initiated Reaction of Triclosan in Gas-Phase

    Directory of Open Access Journals (Sweden)

    Xue Zhang

    2015-04-01

    Full Text Available As a widely used antimicrobial additive in daily consumption, attention has been paid to the degradation and conversion of triclosan for a long time. The quantum chemistry calculation and the canonical variational transition state theory are employed to investigate the mechanism and kinetic property. Besides addition and abstraction, oxidation pathways and further conversion pathways are also considered. The OH radicals could degrade triclosan to phenols, aldehydes, and other easily degradable substances. The conversion mechanisms of triclosan to the polychlorinated dibenzopdioxin and furan (PCDD/Fs and polychlorinated biphenyls (PCBs are clearly illustrated and the toxicity would be strengthened in such pathways. Single radical and diradical pathways are compared to study the conversion mechanism of dichlorodibenzo dioxin (DCDD. Furthermore, thermochemistry is discussed in detail. Kinetic property is calculated and the consequent ratio of kadd/ktotal and kabs/ktotal at 298.15 K are 0.955 and 0.045, respectively. Thus, the OH radical addition reactions are predominant, the substitute position of OH radical on triclosan is very important to generate PCDD and furan, and biradical is also a vital intermediate to produce dioxin.

  7. Chemical conversion pathways and kinetic modeling for the OH-initiated reaction of triclosan in gas-phase.

    Science.gov (United States)

    Zhang, Xue; Zhang, Chenxi; Sun, Xiaomin; Kang, Lingyan; Zhao, Yan

    2015-04-10

    As a widely used antimicrobial additive in daily consumption, attention has been paid to the degradation and conversion of triclosan for a long time. The quantum chemistry calculation and the canonical variational transition state theory are employed to investigate the mechanism and kinetic property. Besides addition and abstraction, oxidation pathways and further conversion pathways are also considered. The OH radicals could degrade triclosan to phenols, aldehydes, and other easily degradable substances. The conversion mechanisms of triclosan to the polychlorinated dibenzopdioxin and furan (PCDD/Fs) and polychlorinated biphenyls (PCBs) are clearly illustrated and the toxicity would be strengthened in such pathways. Single radical and diradical pathways are compared to study the conversion mechanism of dichlorodibenzo dioxin (DCDD). Furthermore, thermochemistry is discussed in detail. Kinetic property is calculated and the consequent ratio of k add/k total and k abs/k total at 298.15 K are 0.955 and 0.045, respectively. Thus, the OH radical addition reactions are predominant, the substitute position of OH radical on triclosan is very important to generate PCDD and furan, and biradical is also a vital intermediate to produce dioxin.

  8. Tribological behavior at elevated temperature of multilayer TiCN/TiC/TiN hard coatings produced by chemical vapor deposition

    International Nuclear Information System (INIS)

    Bao Mingdong; Xu Xuebo; Zhang Haijun; Liu Xiaoping; Tian Linhai; Zeng Zhaoxin; Song Yubin

    2011-01-01

    Multilayer hard coatings of TiCN/TiC/TiN on high speed steel substrates were deposited using a chemical vapor deposition system. Evaluations of microstructure, wear morphology of coatings were characterized by scanning electron microscopy, and optical microscopy. Friction coefficient and wear rates of coatings were investigated using ball-on-disk tester sliding against a WC ball at a constant load of 20 N. Tribological behavior of the coatings at room and elevated temperature were discussed. Different changing tendency of friction coefficient were observed from ball-on-disc experiments. Results showed that the friction coefficient of coatings increased gradually to a highest value, then to a relatively constant value at room temperature dry sliding wear. The friction coefficient exhibited a reverse variation tendency at temperature of 550 °C. It got a higher value at the first sliding friction cycles. Then the value of friction coefficient decreased, suffered irregular oscillations and kept a relatively lower value with increasing sliding time. Reasons of the variation of friction coefficient with sliding time and wear mechanism were analyzed and discussed at room and elevated temperatures, respectively.

  9. Physico-chemical properties and efficacy of silk fibroin fabric coated with different waxes as wound dressing.

    Science.gov (United States)

    Kanokpanont, Sorada; Damrongsakkul, Siriporn; Ratanavaraporn, Juthamas; Aramwit, Pornanong

    2013-04-01

    Silk fibroin (SF) has been widely used as a wound dressing material due to its suitable physical and biological characteristics. In this study, a non-adhesive wound dressing which applies to cover the wound surface as an absorbent pad that would absorb wound fluid while accelerate wound healing was developed. The modification of SF fabrics by wax coating was purposed to prepare the non-adhesive wound dressing that is required in order to minimize pain and risk of repeated injury. SF woven fabrics were coated with different types of waxes including shellac wax, beeswax, or carnauba wax. Physical and mechanical properties of the wax-coated SF fabrics were characterized. It was clearly observed that all waxes could be successfully coated on the SF fabrics, possibly due to the hydrophobic interactions between hydrophobic domains of SF and waxes. The wax coating improved tensile modulus and percentage of elongation of the SF fabrics due to the denser structure and the thicker fibers coated. The in vitro degradation study demonstrated that all wax-coated SF fabrics remained up to 90% of their original weights after 7 weeks of incubation in lysozyme solution under physiological conditions. The wax coating did not affect the degradation behavior of the SF fabrics. A peel test of the wax-coated SF fabrics was carried out in the partial- and full-thickness wounds of porcine skin in comparison to that of the commercial wound dressing. Any wax-coated SF fabrics were less adhesive than the control, as confirmed by less number of cells attached and less adhesive force. This might be that the wax-coated SF fabrics showed the hydrophobic property, allowing the loosely adherence to the hydrophilic wound surface. In addition, the in vivo biocompatibility test of the wax-coated SF fabrics was performed in Sprague-Dawley rats with subcutaneous model. The irritation scores indicated that the carnauba wax-coated SF fabric was not irritant while the shellac wax or beeswax-coated SF

  10. The perspective effects of various seed coating substances on rice seed variety Khao Dawk Mali 105 storability II: the case study of chemical and biochemical properties.

    Science.gov (United States)

    Thobunluepop, P; Pan-in, W; Pawelzik, E; Vearasilp, S

    2009-04-01

    The aim of this study was to investigate the effects of seed coating substances; chemical fungicide (CA) and biological fungicide polymers [chitosan-lignosulphonate polymer (CL) and eugenol incorporated into chitosan-lignosulphonate polymer (E+CL)] on chemical and biochemical changes of rice seeds cv. KDML 105, which have been studied during storage for 12 months. CA significantly affected the rice seed chemical properties and the associated seed deterioration. After 12 months storage, protein content decreased accompanied by declined of lipid content, increased free fatty acids and activated lipoxygenase enzyme. In the case of biological fungicide coated seeds, the antioxidative scavenging enzymes were ascorbate peroxidase and superoxide dismutase and a high antioxidant activity protected them. Moreover, the sugar content was positive correlated with seed germination and vigor. The biological coated seeds were found to maintain high sugar contents inside the seeds, which resulted high seed storability significantly. In contrast, under fungicide stress (CA), those compounds were lost that directly affected seed vigor during storage.

  11. A comparative physico-chemical study of chlorapatite and hydroxyapatite: from powders to plasma sprayed thin coatings.

    Science.gov (United States)

    Demnati, I; Grossin, D; Combes, C; Parco, M; Braceras, I; Rey, C

    2012-10-01

    Due to their bioactivity and osteoconductivity, hydroxyapatite (HA) plasma sprayed coatings have been widely developed for orthopedic uses. However, the thermodynamic instability of HA leads frequently to a mixture of phases which limit the functional durability of the coating. This study investigates the plasma spraying of chlorapatite (ClA) powder, known to melt without decomposition, onto pure titanium substrates using a low energy plasma spray system (LEPS). Pure ClA powder was prepared by a solid gas reaction at 950 °C and thermogravimetric analysis showed the good thermal stability of ClA powder in the range 30-1400 °C compared to that of the HA powder. Characterization of ClA coating showed that ClA had a very high crystalline ratio and no other crystalline phase was detected in the coating. HA and ClA coatings composition, microstructure and in vitro bioactivity potential were studied, compared and discussed. In vitro SBF test on HA and ClA coatings revealed the formation of a poorly crystalline apatite on the coating surface suggesting that we could expect a good osteoconductivity especially for the ClA coating prepared by the LEPS system.

  12. Process for the conversion of and aqueous biomass hydrolyzate into fuels or chemicals by the selective removal of fermentation inhibitors

    Science.gov (United States)

    Hames, Bonnie R.; Sluiter, Amie D.; Hayward, Tammy K.; Nagle, Nicholas J.

    2004-05-18

    A process of making a fuel or chemical from a biomass hydrolyzate is provided which comprises the steps of providing a biomass hydrolyzate, adjusting the pH of the hydrolyzate, contacting a metal oxide having an affinity for guaiacyl or syringyl functional groups, or both and the hydrolyzate for a time sufficient to form an adsorption complex; removing the complex wherein a sugar fraction is provided, and converting the sugar fraction to fuels or chemicals using a microorganism.

  13. Conversion of glucose into platform chemicals using aluminophosphates (SAPO-5 and MeAPO-5 in [BMIM]Cl ionic liquid

    Directory of Open Access Journals (Sweden)

    L. Ayele

    2014-01-01

    Full Text Available The conversion of glucose into platform chemicals such as 5-hydroxymethylfurfural, levulinic acid and formic acid has been investigated using two aluminophosphate based zeotypes (SAPO-5 and MeAPO-5 catalysts in 1-butyl-3-methylimidazolium chloride [BMIM]Cl ionic liquid as a reaction medium. The silico aluminophosphates (SAPO-5 and metal aluminophosphates (MeAPO-5 were designed and chosen for their tunable amount and strength of acid sites. The dehydration of glucose using each catalyst gave more than 90% glucose conversion. Among all the catalysts tested, the most hydrophilic SAPO-5 (1.5T results in a better 5-HMF yield of 8% at 100 °C and 6 h reaction time. Contrary to this, the more hydrophobic SAPO-5 gives higher yield of levulinic acid and formic acid and no 5-HMF yield at this particular reaction time. In general, despite the higher glucose conversion attained by these aluminophosphate based catalysts, the lower yield obtained by these materials can be attributed to the type of acidity and the incompatibility of the pore diameter of the AFI channels of the catalysts and the desired products. DOI: http://dx.doi.org/10.4314/bcse.v28i1.6

  14. Formation of a cerium conversion coating on magnesium alloy using ascorbic acid as additive. Characterisation and anticorrosive properties of the formed films

    Directory of Open Access Journals (Sweden)

    A.P. Loperena

    2016-12-01

    The presence of HAsc in the conversion solution causes changes in the morphology, adherence and anticorrosive performance of the films. The improvement in the corrosion resistance is closely associated with the corrosion inhibition properties of HAsc.

  15. The selective conversion of glutamic acid in amino acid mixtures using glutamate decarboxylase--a means of separating amino acids for synthesizing biobased chemicals.

    Science.gov (United States)

    Teng, Yinglai; Scott, Elinor L; Sanders, Johan P M

    2014-01-01

    Amino acids (AAs) derived from hydrolysis of protein rest streams are interesting feedstocks for the chemical industry due to their functionality. However, separation of AAs is required before they can be used for further applications. Electrodialysis may be applied to separate AAs, but its efficiency is limited when separating AAs with similar isoelectric points. To aid the separation, specific conversion of an AA to a useful product with different charge behavior to the remaining compounds is desired. Here the separation of L-aspartic acid (Asp) and L-glutamic acid (Glu) was studied. L-Glutamate α-decarboxylase (GAD, Type I, EC 4.1.1.15) was applied to specifically convert Glu into γ-aminobutyric acid (GABA). GABA has a different charge behavior from Asp therefore allowing a potential separation by electrodialysis. Competitive inhibition and reduced operational stability caused by Asp could be eliminated by maintaining a sufficiently high concentration of Glu. Immobilization of GAD does not reduce the enzyme's initial activity. However, the operational stability was slightly reduced. An initial study on the reaction operating in a continuous mode was performed using a column reactor packed with immobilized GAD. As the reaction mixture was only passed once through the reactor, the conversion of Glu was lower than expected. To complete the conversion of Glu, the stream containing Asp and unreacted Glu might be recirculated back to the reactor after GABA has been removed. Overall, the reaction by GAD is specific to Glu and can be applied to aid the electrodialysis separation of Asp and Glu. © 2014 American Institute of Chemical Engineers.

  16. The Synthesis of Anatase Nanoparticles and the Preparation of Photocatalytically Active Coatings Based on Wet Chemical Methods for Self-Cleaning Applications

    Directory of Open Access Journals (Sweden)

    Dejan Verhovšek

    2012-01-01

    Full Text Available We report on an improved sol-gel method for the production of highly photocatalytic titanium dioxide (TiO2 anatase nanoparticles which can provide appropriate control over the final characteristics of the nanoparticles, such as particle size, crystallinity, crystal structure, morphology, and also the degree of agglomeration. The synthesized anatase nanoparticles were characterized using various techniques, such as X-ray powder diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM, and were tested in coatings for self-cleaning glass and ceramic surfaces. The coatings were prepared using a soft chemistry route and are completely transparent to visible light and exhibit a high photocatalytic effect, which was determined by contact-angle measurements. Finally, it is worth mentioning that both the sol-gel synthesis method and the coating-preparation method are based on a wet chemical process, thus presenting no risk of handling the TiO2 anatase nanoparticles in their potentially hazardous powder form at any stage of our development. Low-price, easy-to-handle, and nontoxic materials were used. Therefore, our work represents an important contribution to the development of TiO2 anatase nanoparticle coatings that provide a high photocatalytic effect and can thus be used for numerous applications.

  17. Structural and chemical analysis of silica-doped β-TCP ceramic coatings on surgical grade 316L SS for possible biomedical application

    Directory of Open Access Journals (Sweden)

    Karuppasamy Prem Ananth

    2015-09-01

    Full Text Available We have developed a novel approach to introduce silica-doped β-tricalcium phosphate (Si-β-TCP on 316L SS substrates for enhanced biological properties. Doping of β-TCP with silica loadings ranging from 0 to 8 mol% was carried out using chemical precipitation method. Si-β-TCP powder was sintered at 800 °C followed by coating it on 316L SS substrate using electrophoretic deposition. The coated and uncoated samples were investigated by various characterization techniques such as X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, field emission scanning electron microscopy (FESEM and X-ray fluorescence spectroscopy (XRF. Biomineralization ability of the coatings was evaluated by immersing in simulated body fluid (SBF solution for different number of days such as 7, 14, 21 and 28 days. The results obtained in our study have shown that the apatite formation ability was high for the 8 mol% of Si-β-TCP. This will promote better biomineralization ability compared to the other coatings.

  18. Photoelectrochemical energy conversion obtained with ultrathin organo-metallic-chemical-vapor-deposition layer of FeS2 (pyrite) on TiO2

    International Nuclear Information System (INIS)

    Ennaoui, A.; Fiechter, S.; Tributsch, H.; Giersig, M.; Vogel, R.; Weller, H.

    1992-01-01

    Ultrathin (10 to 20 nm thick), polycrystalline films of FeS 2 (pyrite) were grown on TiO 2 (anatase) by chemical vapor deposition. The FeS 2 films were characterized using optical absorption and high-resolution electron microscopy. Photoelectrochemical solar cells, using TiO 2 (anatase) coated with FeS 2 ultrathin films, generated high open-circuit photo-voltages, of up to 600 mV, compared with a single crystal of pyrite electrode (200 mV). The photoelectrochemical behavior shows a strong dependence of photovoltage and photocurrent on the pH of the solution. This paper reports that it is explained by electron injection from the conduction band of FeS 2 to the conduction band of TiO 2 . Regeneration of holes is taking place by electron transfer from the redox system in the electrolyte

  19. Photoelectrochemical energy conversion obtained with ultrathin organo-metallic-chemical-vapor-deposition layer of FeS[sub 2] (pyrite) on TiO[sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Ennaoui, A.; Fiechter, S.; Tributsch, H. (Abt. Solare Energetik, Hahn-Meitner-Inst., D-1000 Berlin 39 (Germany)); Giersig, M.; Vogel, R.; Weller, H. (Abt. Photochemie, Hahn-Meitner-Inst., D-1000 Berlin 39 (Germany))

    1992-09-01

    Ultrathin (10 to 20 nm thick), polycrystalline films of FeS[sub 2] (pyrite) were grown on TiO[sub 2] (anatase) by chemical vapor deposition. The FeS[sub 2] films were characterized using optical absorption and high-resolution electron microscopy. Photoelectrochemical solar cells, using TiO[sub 2] (anatase) coated with FeS[sub 2] ultrathin films, generated high open-circuit photo-voltages, of up to 600 mV, compared with a single crystal of pyrite electrode (200 mV). The photoelectrochemical behavior shows a strong dependence of photovoltage and photocurrent on the pH of the solution. This paper reports that it is explained by electron injection from the conduction band of FeS[sub 2] to the conduction band of TiO[sub 2]. Regeneration of holes is taking place by electron transfer from the redox system in the electrolyte.

  20. Synthesis and analysis of separation networks for the recovery of intracellular chemicals generated from microbial-based conversions.

    Science.gov (United States)

    Yenkie, Kirti M; Wu, Wenzhao; Maravelias, Christos T

    2017-01-01

    Bioseparations can contribute to more than 70% in the total production cost of a bio-based chemical, and if the desired chemical is localized intracellularly, there can be additional challenges associated with its recovery. Based on the properties of the desired chemical and other components in the stream, there can be multiple feasible options for product recovery. These options are composed of several alternative technologies, performing similar tasks. The suitability of a technology for a particular chemical depends on (1) its performance parameters, such as separation efficiency; (2) cost or amount of added separating agent; (3) properties of the bioreactor effluent (e.g., biomass titer, product content); and (4) final product specifications. Our goal is to first synthesize alternative separation options and then analyze how technology selection affects the overall process economics. To achieve this, we propose an optimization-based framework that helps in identifying the critical technologies and parameters. We study the separation networks for two representative classes of chemicals based on their properties. The separation network is divided into three stages: cell and product isolation (stage I), product concentration (II), and product purification and refining (III). Each stage exploits differences in specific product properties for achieving the desired product quality. The cost contribution analysis for the two cases (intracellular insoluble and intracellular soluble) reveals that stage I is the key cost contributor (>70% of the overall cost). Further analysis suggests that changes in input conditions and technology performance parameters lead to new designs primarily in stage I. The proposed framework provides significant insights for technology selection and assists in making informed decisions regarding technologies that should be used in combination for a given set of stream/product properties and final output specifications. Additionally, the

  1. Progress towards all-chemical superconducting YBa{sub 2}Cu{sub 3}O{sub 7}-coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Obradors, X [Institut de Ciencia de Materials de Barcelona, CSIC Campus de la UAB, 08193 Bellaterra (Spain); Puig, T [Institut de Ciencia de Materials de Barcelona, CSIC Campus de la UAB, 08193 Bellaterra (Spain); Pomar, A [Institut de Ciencia de Materials de Barcelona, CSIC Campus de la UAB, 08193 Bellaterra (Spain)

    2006-03-15

    Chemical solution deposition (CSD) has recently emerged as a very competitive technique for obtaining epitaxial films of high quality with controlled nanostructure. In particular, the all-CSD approach is considered to be one of the most promising approaches for cost-effective production of second-generation superconducting wires. The trifluoroacetate (TFA) route is a very versatile route for achieving epitaxial YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO) layers with high critical currents. In this work, recent advances towards improvement of the performance of several conductor architectures based on the YBCO TFA process will be presented. We show that new improved anhydrous TFA precursors allow a significant shortening of the pyrolysis time ({approx}1.5 h), and we have increased the total film thickness in a single deposition using polymeric additives. On the other hand, further understanding of the YBCO nucleation and growth process has allowed us to obtain a controlled microstructure and high critical currents (J{sub c}{approx}4-5 MA cm{sup -2} and I{sub c}{approx}300 A cm{sup -1} width at 77 K). The growth conditions (CSD) and post-processing conditions (sputtering and CSD) for the underlying oxide cap and buffer layers (CeO{sub 2}, BaZrO{sub 3}, SrTiO{sub 3}, La{sub 2}Zr{sub 2}O{sub 7} (La,Sr)MnO{sub 3}) and of self-organized nanostructures (CeO{sub 2}, BaZrO{sub 3}) deposited by CSD have been investigated to obtain high-quality interfaces in multilayered systems. Different single-crystal or metallic substrates (YSZ-IBAD (yttrium stabilized zirconia-ion beam assisted deposition) and Ni-RABiT (rolling assisted biaxial texturing)) have been investigated and long ({approx}10 m) CSD biaxially textured buffers (CeO{sub 2}, La{sub 2}Zr{sub 2}O{sub 7}) have been grown on Ni-RABiT substrates using a reel-to-reel system. High-performance TFA-YBCO-coated conductors have been obtained on vacuum-based buffer layers (I{sub c}{approx}140 A cm{sup -1} width) and on CSD buffer layers

  2. High-throughput analysis for preparation, processing and analysis of TiO2 coatings on steel by chemical solution deposition

    International Nuclear Information System (INIS)

    Cuadrado Gil, Marcos; Van Driessche, Isabel; Van Gils, Sake; Lommens, Petra; Castelein, Pieter; De Buysser, Klaartje

    2012-01-01

    Highlights: ► High-throughput preparation of TiO 2 aqueous precursors. ► Analysis of stability and surface tension. ► Deposition of TiO 2 coatings. - Abstract: A high-throughput preparation, processing and analysis of titania coatings prepared by chemical solution deposition from water-based precursors at low temperature (≈250 °C) on two different types of steel substrates (Aluzinc® and bright annealed) is presented. The use of the high-throughput equipment allows fast preparation of multiple samples saving time, energy and material; and helps to test the scalability of the process. The process itself includes the use of IR curing for aqueous ceramic precursors and possibilities of using UV irradiation before the final sintering step. The IR curing method permits a much faster curing step compared to normal high temperature treatments in traditional convection devices (i.e., tube furnaces). The formulations, also prepared by high-throughput equipment, are found to be stable in the operational pH range of the substrates (6.5–8.5). Titanium alkoxides itself lack stability in pure water-based environments, but the presence of the different organic complexing agents prevents it from hydrolysis and precipitation reactions. The wetting interaction between the substrates and the various formulations is studied by the determination of the surface free energy of the substrates and the polar and dispersive components of the surface tension of the solutions. The mild temperature program used for preparation of the coatings however does not lead to the formation of pure crystalline material, necessary for the desired photocatalytic and super-hydrophilic behavior of these coatings. Nevertheless, some activity can be reported for these amorphous coatings by monitoring the discoloration of methylene blue in water under UV irradiation.

  3. Microstructure, physical and chemical properties of nanostructured (Ti–Hf–Zr–V–Nb)N coatings under different deposition conditions

    Energy Technology Data Exchange (ETDEWEB)

    Pogrebnjak, A.D.; Yakushchenko, I.V. [Sumy State University, 2, Rymsky Korsakov Str., 40007 Sumy (Ukraine); Bagdasaryan, A.A., E-mail: artemsumdu@ukr.net [Sumy State University, 2, Rymsky Korsakov Str., 40007 Sumy (Ukraine); Bondar, O.V. [Sumy State University, 2, Rymsky Korsakov Str., 40007 Sumy (Ukraine); Krause-Rehberg, R. [Martin-Luther-University Halle-Wittenberg, Halle (Germany); Abadias, G.; Chartier, P. [Institut P' , University of Poitiers, Chasseneuil-Futuroscope (France); Oyoshi, K.; Takeda, Y. [National Institute for Material Science, Tsukuba (Japan); Beresnev, V.M. [Kharkiv National University, 21, Svobody Sq., 4, 61022 Kharkiv (Ukraine); Sobol, O.V. [National Technical University, Kharkiv Polytechnic Institute, Kharkiv (Ukraine)

    2014-10-15

    High-entropy alloy and nitride coatings (TiHfZrVNb)N were prepared by the cathodic-arc-vapor-deposition method under various deposition conditions. The composition, crystal structure, strain-stress state, profiles of defects and atoms in-depth and at surfaces of the (TiHfZrVNb)N coatings were characterized by EDS and SEM analysis, X-ray diffraction with “α-sin{sup 2}ψ” method of measurements and slow positron beam. The oxidation behavior of nitride films after annealing at 600 °C temperature was studied. The results indicate that nitride coatings show the face-centered cubic crystal structure. The redistributions of elements and defects, their arrangement (segregation) due to the thermally stimulated diffusion and termination of the spinodal segregation near the interfaces, around the grains and subgrains were found. The peak hardness and modulus of the nitride films were 44.3 and 384 GPa, respectively. The tribological properties of the (TiHfZrVNb)N coatings against AISI 1045 were evaluated by a ball-on-disc tribometer with a 3.0 N applied load. - Highlights: • (Ti–Hf–Zr–V–Nb)N coatings produced by CAVD exhibit enhanced strength. • The influence of deposition parameters on the defect structure in the coating was discussed. • Partial relaxation of compressive stress is observed after thermal annealing at 600 °C. • Coatings deposited on the steel substrate improve its tribological performance.

  4. Growth of ZnS-coated ZnO nanorod arrays on (1 0 0) silicon substrate by two-step chemical synthesis

    International Nuclear Information System (INIS)

    Kumarakuru, Haridas; Urgessa, Zelalem N.; Olivier, Ezra J.; Botha, Johannes R.; Venter, Andre; Neethling, Johannes H.

    2014-01-01

    Highlights: • ZnS coated ZnO nanorods were synthesized using a simple two-step chemical method. • The uniform ZnS coating exhibits a polycrystalline face centered cubic structure. • Initial ZnS deposit exhibits a partial epitaxial relationship with ZnO. • An ion-exchange reaction was deduced for this sulphidation process. • Detailed microscopy results are complemented by room temperature photoluminescence. - Abstract: In this study, ZnS coated ZnO nanorods were synthesized using a simple, cost effective two-step chemical method. A continuous coating of ZnS on a ZnO nanorod, having a uniform thickness, is demonstrated using high resolution transmission electron microscopy, electron energy loss spectroscopy and selected area diffraction (SAD). These core–shell structures can be produced at relatively low temperatures (75 °C) and within relatively short times (3 h). The ZnS coating exhibits a polycrystalline structure with a lattice parameter of 5.35 Å, which is 1.1% smaller than the unstrained cubic zinc-blende structure. The SAD pattern taken at the ZnO–ZnS interface exhibits a partial epitaxial relationship, where (1 0 –1 0) ZnO//(1 1 1) ZnS. Our detailed analysis shows that the ZnS shell comprises two different regions: a ZnS rich inner shell region is produced via the first sulphidation process, followed by a mixture of ZnO and ZnS in the outer shell region during the second treatment. From the detailed microscopy results a growth mechanism is proposed for each step of the sulphidation process. The results are complemented by room temperature photoluminescence spectroscopy. Strong emission from free excitons in ZnO is observed at 3.27 eV before ZnS coating, while a composite band peaking at 2.9 eV is measured after sulphidation. The origin of the latter will be discussed

  5. Growth of ZnS-coated ZnO nanorod arrays on (1 0 0) silicon substrate by two-step chemical synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kumarakuru, Haridas, E-mail: haridas.kumarakuru@nmmu.ac.za [Centre for High Resolution Transmission Electron Microscopy (CHRTEM), Department of Physics, P.O.Box 77000, Nelson Mandela Metropolitan University (NMMU), Port Elizabeth 6031 (South Africa); Urgessa, Zelalem N. [Department of Physics, Nelson Mandela Metropolitan University (NMMU), P.O. Box 77000, Port Elizabeth 6031 (South Africa); Olivier, Ezra J. [Centre for High Resolution Transmission Electron Microscopy (CHRTEM), Department of Physics, P.O.Box 77000, Nelson Mandela Metropolitan University (NMMU), Port Elizabeth 6031 (South Africa); Botha, Johannes R.; Venter, Andre [Department of Physics, Nelson Mandela Metropolitan University (NMMU), P.O. Box 77000, Port Elizabeth 6031 (South Africa); Neethling, Johannes H. [Centre for High Resolution Transmission Electron Microscopy (CHRTEM), Department of Physics, P.O.Box 77000, Nelson Mandela Metropolitan University (NMMU), Port Elizabeth 6031 (South Africa); Department of Physics, Nelson Mandela Metropolitan University (NMMU), P.O. Box 77000, Port Elizabeth 6031 (South Africa)

    2014-11-05

    Highlights: • ZnS coated ZnO nanorods were synthesized using a simple two-step chemical method. • The uniform ZnS coating exhibits a polycrystalline face centered cubic structure. • Initial ZnS deposit exhibits a partial epitaxial relationship with ZnO. • An ion-exchange reaction was deduced for this sulphidation process. • Detailed microscopy results are complemented by room temperature photoluminescence. - Abstract: In this study, ZnS coated ZnO nanorods were synthesized using a simple, cost effective two-step chemical method. A continuous coating of ZnS on a ZnO nanorod, having a uniform thickness, is demonstrated using high resolution transmission electron microscopy, electron energy loss spectroscopy and selected area diffraction (SAD). These core–shell structures can be produced at relatively low temperatures (75 °C) and within relatively short times (3 h). The ZnS coating exhibits a polycrystalline structure with a lattice parameter of 5.35 Å, which is 1.1% smaller than the unstrained cubic zinc-blende structure. The SAD pattern taken at the ZnO–ZnS interface exhibits a partial epitaxial relationship, where (1 0 –1 0) ZnO//(1 1 1) ZnS. Our detailed analysis shows that the ZnS shell comprises two different regions: a ZnS rich inner shell region is produced via the first sulphidation process, followed by a mixture of ZnO and ZnS in the outer shell region during the second treatment. From the detailed microscopy results a growth mechanism is proposed for each step of the sulphidation process. The results are complemented by room temperature photoluminescence spectroscopy. Strong emission from free excitons in ZnO is observed at 3.27 eV before ZnS coating, while a composite band peaking at 2.9 eV is measured after sulphidation. The origin of the latter will be discussed.

  6. Erosion behaviour of physically vapour-deposited and chemically vapour-deposited SiC films coated on molybdenum during oxygenated argon beam thinning

    International Nuclear Information System (INIS)

    Shikama, T.; Kitajima, M.; Fukutomi, M.; Okada, M.

    1984-01-01

    The erosion behaviour during bombardment with a 5 keV argon beam at room temperature was studied for silicon carbide (SiC) films of thickness of about 10 μm coated on molybdenum by physical vapour deposition (PVD) and chemical vapour deposition (CVD). The PVD SiC (plasma-assisted ion plating) exhibited a greater thinning rate than the CVD SiC film. Electron probe X-ray microanalysis revealed that the chemical composition of PVD SiC was changed to a composition enriched in silicon by the bombardment, and there was a notable change in its surface morphology. The CVD SiC retained its initial chemical composition with only a small change in its surface morphology. Auger electron spectroscopy indicated that silicon oxide was formed on the surface of PVD SiC by the bombardment. The greater thinning rate and easier change in chemical composition in PVD SiC could be attributed to its readier chemical reaction with oxygen due to its more non-uniform structure and weaker chemical bonding. Oxygen was present as one of the impurities in the argon beam. (Auth.)

  7. Report on investigations and studies on chemical conversion of photo-energy; Hikari energy no kagakuteki henkan ni kansuru chosa kenkyu hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1984-03-01

    This paper summarizes problems in utilization of solar energy, their solutions, features, the currently achieved results, and prospects. With regard to water decomposition using semiconductors, simultaneous generation of hydrogen and oxygen has already been achieved, and there is high possibility of raising the efficiency by improving catalysts. Water decomposition using metal complexes has acceleration of charge isolation as the largest problem, whose prospect of solution is not necessarily bright at the present time. Photo-catalytic reaction is a field to be discussed as one means of developing a new synthesizing method from the viewpoint of organic synthetic chemistry. Conversion into electric energy that uses a photovoltaic process has high efficiency, and is a field to be noted. In photo-energy conversion by means of photo-synthesis, living organisms performing hydrogen production at high efficiency have been discovered. Important studies include the studies in terms of chemical engineering using these living organisms, improvement of breeds by gene manipulations, and studies that utilize living organisms or part of the constituting components. (NEDO)

  8. Modelling Chemical Kinetics of Soybean Oil Transesterification Process for Biodiesel Production: An Analysis of Molar Ratio between Alcohol and Soybean Oil Temperature Changes on the Process Conversion Rate

    Directory of Open Access Journals (Sweden)

    Maicon Tait

    2006-12-01

    Full Text Available A mathematical model describing chemical kinetics of transesterification of soybean oil for biodiesel production has been developed. The model is based on the reverse mechanism of transesterification reactions and describes dynamics concentration changes of triglycerides, diglycerides, monoglycerides, biodiesel, and glycerol production. Reaction rate constants were written in the Arrhenius form. An analysis of key process variables such as temperature and molar ratio soybean oil- alcohol using response surface analysis was performed to achieve the maximum soybean conversion rate to biodiesel. The predictive power of the developed model was checked for the very wide range of operational conditions and parameters values by fitting different experimental results for homogeneous catalytic and non-catalytic processes published in the literature. A very good correlation between model simulations and experimental data was observed.

  9. A four-layer model for calculating the dispersion and chemical conversion of pollutants in the atmosphere

    International Nuclear Information System (INIS)

    Nguyen, T.H.

    1989-01-01

    A four-layer model for the calculation of the propagation and chemical change of emitted pollutants in the ground level troposphere is presented. The following influences on the spreading of pollutants are considered: the height of the mixing layer, the orography, the horizontal and vertical advection, the horizontal and vertical diffusion, the diurnal variation of insolation, the source strength of the emissions of NO x , HC, SO 2 and CO. The knowledge of the wind field is an essential precondition for spreading calculations in the ground level troposphere. For the calculation of the wind field, a wind model is developed with the help of the variation calculation. The propagation and the chemical change of pollutants in the atmosphere in the Upper Rhine Graben are calculated for various atmospheric conditions and emission data. The influences of the wind power orography, the parametrization of the turbulent diffusion and the emission volume on the concentration of the photooxidants are studied in detail. (orig./KW) With 82 figs., 9 tabs [de

  10. Influence of carbon chemical bonding on the tribological behavior of sputtered nanocomposite TiBC/a-C coatings

    International Nuclear Information System (INIS)

    Abad, M.D.; Sanchez-Lopez, J.C.; Brizuela, M.; Garcia-Luis, A.; Shtansky, D.V.

    2010-01-01

    The tribological performance of nanocomposite coatings containing Ti-B-C phases and amorphous carbon (a-C) are studied. The coatings are deposited by a sputtering process from a sintered TiB 2 :TiC target and graphite, using pulsed direct current and radio frequency sources. By varying the sputtering power ratio, the amorphous carbon content of the coatings can be tuned, as observed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The crystalline component consists of very disordered crystals with a mixture of TiB 2 /TiC or TiB x C y phases. A slight increase in crystalline order is detected with the incorporation of carbon in the coatings that is attributed to the formation of a ternary TiB x C y phase. An estimation of the carbon present in the form of carbide (TiB x C y or TiC) and amorphous (a-C) is performed using fitting analysis of the C 1s XPS peak. The film hardness (22 to 31 GPa) correlates with the fraction of the TiB x C y phase that exists in the coatings. The tribological properties were measured by a pin-on-disk tribometer in ambient conditions, using 6 mm tungsten carbide balls at 1 N. The friction coefficients and the wear rates show similar behavior, exhibiting an optimum when the fraction of C atoms in the amorphous phase is near 50%. This composition enables significant improvement of the friction coefficients and wear rates (μ ∼ 0.1; k -6 mm 3 /Nm), while maintaining a good value of hardness (24.6 GPa). Establishing the correlation between the lubricant properties and the fraction of a-C is very useful for purposes of tailoring the protective character of these nanocomposite coatings to engineering applications.

  11. Superhydrophobic powder additives to enhance chemical agent resistant coating systems for military equipment for the U.S. Marine Corps (USMC) Corrosion Prevention and Control (CPAC) Program

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, Steven J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Armstrong, Beth L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Haynes, James A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-07-01

    The primary goal of the CPAC program at ORNL was to explore the feasibility of introducing various silica-based superhydrophobic (SH) powder additives as a way to improve the corrosion resistance of US Department of Defense (DOD) military-grade chemical agent resistant coating (CARC) systems. ORNL had previously developed and patented several SH technologies of interest to the USMC, and one of the objectives of this program was to identify methods to incorporate these technologies into the USMC’s corrosion-resistance strategy. This report discusses findings of the CPAC and their application.

  12. Chemical and electrochemical synthesis of nano-sized TiO{sub 2} anatase for large-area photon conversion

    Energy Technology Data Exchange (ETDEWEB)

    Babasaheb, Raghunath Sankapal; Shrikrishna, Dattatraya Sartale; Lux-Steiner, M.Ch.; Ennaoui, A. [Hahn-Meitner-Institut, Div. of Solar Energy Research, Berlin (Germany)

    2006-05-15

    We report on the synthesis of nanocrystalline titanium dioxide thin films and powders by chemical and electrochemical deposition methods. Both methods are simple, inexpensive and suitable for large-scale production. Air-annealing of the films and powders at T = 500 C leads to densely packed nanometer sized anatase TiO{sub 2} particles. The obtained layers are characterized by different methods such as: X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Titanium dioxide TiO{sub 2} (anatase) phase with (101) preferred orientation has been obtained for the films deposited on glass; indium doped tin oxide (ITO) and quartz substrates. The powder obtained as the byproduct consists of TiO{sub 2} with anatase-phase as well. (authors)

  13. Chemical and electrochemical synthesis of nano-sized TiO2 anatase for large-area photon conversion

    International Nuclear Information System (INIS)

    Babasaheb, Raghunath Sankapal; Shrikrishna, Dattatraya Sartale; Lux-Steiner, M.Ch.; Ennaoui, A.

    2006-01-01

    We report on the synthesis of nanocrystalline titanium dioxide thin films and powders by chemical and electrochemical deposition methods. Both methods are simple, inexpensive and suitable for large-scale production. Air-annealing of the films and powders at T = 500 C leads to densely packed nanometer sized anatase TiO 2 particles. The obtained layers are characterized by different methods such as: X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Titanium dioxide TiO 2 (anatase) phase with (101) preferred orientation has been obtained for the films deposited on glass; indium doped tin oxide (ITO) and quartz substrates. The powder obtained as the byproduct consists of TiO 2 with anatase-phase as well. (authors)

  14. Catalytic Upgrading of Thermochemical Intermediates to Hydrocarbons: Conversion of Lignocellulosic Feedstocks to Aromatic Fuels and High Value Chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Cortright, Randy [Virent, Inc., Madison, WI (United States); Rozmiarek, Bob [Virent, Inc., Madison, WI (United States); Van Straten, Matt [Virent, Inc., Madison, WI (United States)

    2017-11-28

    The principal objective of this project was to develop a fully integrated catalytic process that efficiently converts lignocellulosic feedstocks (e.g. bagasse, corn stover, and loblolly pine) into aromatic-rich fuels and chemicals. Virent led this effort with key feedstock support from Iowa State University. Within this project, Virent leveraged knowledge of catalytic processing of sugars and biomass to investigate two liquefaction technologies (Reductive Catalytic Liquefaction (USA Patent No. 9,212,320, 2015) and Solvolysis (USA Patent No. 9,157,030, 2015) (USA Patent No. 9,157,031, 2015)) that take advantage of proprietary catalysts at temperatures less than 300°C in the presence of unique solvent molecules generated in-situ within the liquefaction processes.

  15. Nitrogen and triple oxygen isotopes in near-road air samples using chemical conversion and thermal decomposition.

    Science.gov (United States)

    Smirnoff, Anna; Savard, Martine M; Vet, Robert; Simard, Marie-Christine

    2012-12-15

    The determination of triple oxygen (δ(18)O and δ(17)O) and nitrogen isotopes (δ(15)N) is important when investigating the sources and atmospheric paths of nitrate and nitrite. To fully understand the atmospheric contribution into the terrestrial nitrogen cycle, it is crucial to determine the δ(15)N values of oxidised and reduced nitrogen species in precipitation and dry deposition. In an attempt to further develop non-biotic methods and avoid expensive modifications of the gas-equilibration system, we have combined and modified sample preparation procedures and analytical setups used by other researchers. We first chemically converted NO(3)(-) and NH(4)(+) into NO(2)(-) and then into N(2)O. Subsequently, the resulting gas was decomposed into N(2) and O(2) and analyzed by isotope ratio mass spectrometry (IRMS) using a pre-concentration system equipped with a gold reduction furnace. The δ(17)O, δ(18)O and δ(15)N values of nitrate and nitrite samples were acquired simultaneously in one run using a single analytical system. Most importantly, the entire spectrum of δ(17)O, δ(18)O and/or δ(15)N values was determined from atmospheric nitrate, nitric oxide, ammonia and ammonium. The obtained isotopic values for air and precipitation samples were in good agreement with those from previous studies. We have further advanced chemical approaches to sample preparation and isotope analyses of nitrogen-bearing compounds. The proposed methods are inexpensive and easily adaptable to a wide range of laboratory conditions. This will substantially contribute to further studies on sources and pathways of nitrate, nitrite and ammonium in terrestrial nitrogen cycling. Copyright © 2012 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.

  16. Chemical and biological assessment of Cd-polluted sediment for land use: The effect of stabilization using chitosan-coated zeolite.

    Science.gov (United States)

    Wen, Jia; Zeng, Guangming

    2018-04-15

    Disposal of dredged sediment contaminated with heavy metals on site or in landfills inevitably causes leaching of metals that generate new environmental problems. In this study, we investigated the effectiveness of stabilizing heavy metal Cd in sediment taken from Dongting Lake, China, using a chitosan-coated zeolite, and assessed the feasibility of reusing the stabilized sediment in river bank soil based on chemical and biological analyses. Results showed that the addition of chitosan-coated zeolite significantly reduced acid-exchangeable Cd by 8% in the dredged sediment and 7% in a sediment-soil mixture. Cadmium leachability was greatly reduced in the amended sediment or sediment-soil mixture. Toxicity bioassay using Eisenia fetida showed the mortality rate of worms reduced by 16% in sediment-soil mixture with a Cd concentration of 550 mg/kg and by 17% under a Cd concentration of 250 mg/kg, both with the addition of modified zeolite. Moreover, assimilation of Cd in the earthworms was decreased by a maximum of 36 mg/kg in the sediment-soil mixture with zeolite amendment. These results indicate that the reuse of Cd-contaminated sediment following chitosan-coated zeolite modification is a feasible option for treating the dredged sediment, and could thus benefit both aquatic and terrestrial systems. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Advanced zirconia-coated carbonyl-iron particles for acidic magnetorheological finishing of chemical-vapor-deposited ZnS and other IR materials

    Science.gov (United States)

    Salzman, S.; Giannechini, L. J.; Romanofsky, H. J.; Golini, N.; Taylor, B.; Jacobs, S. D.; Lambropoulos, J. C.

    2015-10-01

    We present a modified version of zirconia-coated carbonyl-iron (CI) particles that were invented at the University of Rochester in 2008. The amount of zirconia on the coating is increased to further protect the iron particles from corrosion when introduced to an acidic environment. Five low-pH, magnetorheological (MR) fluids were made with five acids: acetic, hydrochloric, nitric, phosphoric, and hydrofluoric. All fluids were based on the modified zirconia-coated CI particles. Off-line viscosity and pH stability were measured for all acidic MR fluids to determine the ideal fluid composition for acidic MR finishing of chemical-vapor-deposited (CVD) zinc sulfide (ZnS) and other infrared (IR) optical materials, such as hot-isostatic-pressed (HIP) ZnS, CVD zinc selenide (ZnSe), and magnesium fluoride (MgF2). Results show significant reduction in surface artifacts (millimeter-size, pebble-like structures on the finished surface) for several standard-grade CVD ZnS substrates and good surface roughness for the non-CVD MgF2 substrate when MR finished with our advanced acidic MR fluid.

  18. Characterization of Carbon-Contaminated B4C-Coated Optics after Chemically Selective Cleaning with Low-Pressure RF Plasma.

    Science.gov (United States)

    Moreno Fernández, H; Rogler, D; Sauthier, G; Thomasset, M; Dietsch, R; Carlino, V; Pellegrin, E

    2018-01-22

    Boron carbide (B 4 C) is one of the few materials that is expected to be most resilient with respect to the extremely high brilliance of the photon beam generated by free electron lasers (FELs) and is thus of considerable interest for optical applications in this field. However, as in the case of many other optics operated at light source facilities, B 4 C-coated optics are subject to ubiquitous carbon contaminations. Carbon contaminations represent a serious issue for the operation of FEL beamlines due to severe reduction of photon flux, beam coherence, creation of destructive interference, and scattering losses. A variety of B 4 C cleaning technologies were developed at different laboratories with varying success. We present a study regarding the low-pressure RF plasma cleaning of carbon contaminated B 4 C test samples via inductively coupled O 2 /Ar, H 2 /Ar, and pure O 2 RF plasma produced following previous studies using the same ibss GV10x downstream plasma source. Results regarding the chemistry, morphology as well as other aspects of the B 4 C optical coating before and after the plasma cleaning are reported. We conclude that among the above plasma processes only plasma based on pure O 2 feedstock gas exhibits the required chemical selectivity for maintaining the integrity of the B 4 C optical coatings.

  19. Synthesis of BaTiO3 nanoparticles from TiO2-coated BaCO3 particles derived using a wet-chemical method

    Directory of Open Access Journals (Sweden)

    Yuuki Mochizuki

    2014-03-01

    Full Text Available BaCO3 particles coated with amorphous TiO2 precursor are prepared by a wet chemical method to produce BaTiO3 nanoparticles at low temperatures. Subsequently, we investigate the formation behavior of BaTiO3 particles and the particle growth behavior when the precursor is subjected to heat treatment. The state of the amorphous TiO2 coating on the surface of BaCO3 particles depends on the concentration of NH4HCO3, and the optimum concentration is found to be in the range 0.5–1.0 M. Thermogravimetric curves of the BaCO3 particles coated with the TiO2 precursor, prepared from BaCO3 particles of various sizes, show BaTiO3 formation occurring mainly at 550–650 °C in the case of fine BaCO3 particles. However, as evidenced from the curves, the temperature of formation of BaTiO3 shifts to higher values with an increase in the size of the BaCO3 particles. The average particle size of single phase BaTiO3 at heat-treatment temperature of 650–900 °C is observed to be in the range 60–250 nm.

  20. Two level undercut-profile substrate-based filamentary coated conductors produced using metal organic chemical vapor deposition

    DEFF Research Database (Denmark)

    Insinga, Andrea R.; Sundaram, Aarthi; Hazelton, Drew W.

    2018-01-01

    The two level undercut-profile substrate (2LUPS) has been introduced as a concept for subdividing rare-earth-Ba$_{2}$Cu$_{3}$O$_{7}$ (REBCO) coated conductors (CC) into narrow filaments which reduces the AC losses and improves field stability for DC magnets. The 2LUPS consists of two levels...

  1. Morphological and chemical evaluation of bone with apatite-coated Al2O3 implants as scaffolds for bone repair

    Directory of Open Access Journals (Sweden)

    A. L. M. Maia F.

    2013-12-01

    Full Text Available The clinical challenge in the reconstruction of bone defects has stimulated several studies in search of alternatives to repair these defects. The ceramics are considered as synthetic scaffolds and are used in dentistry and orthopedics. This study aimed to evaluate by micro energy-dispersive X-ray fluorescence spectrometry (µ-EDXRF and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS, the influence of uncoated and apatite-coated Al2O3 implants on bone regeneration. Twelve samples of Al2O3 implants were prepared and half of this samples (n = 6 were apatite-coated by the modified biomimetic method and then the ceramic material were implanted in the tibia of rabbits. Three experimental groups were tested: Group C - control, surgery procedure without ceramic implant, Group Ce - uncoated Al2O3 implants (n = 6 and Group CeHA - apatite-coated Al2O3 implants (n = 6. The deposition of bone tissue was determined by measuring the weight content of Ca and P through surface mapping of bone-implant interface by µ-EDXRF and through point analysis by EDS. It was observed after thirty days of treatment a greater deposition of Ca and P in the group treated with CeHA (p <0.001 compared to group C. The results suggest that ceramic coated with hydroxyapatite (CeHA can be an auxiliary to bone deposition in tibia defect model in rabbits.

  2. Metallic coating of microspheres

    International Nuclear Information System (INIS)

    Meyer, S.F.

    1980-01-01

    Extremely smooth, uniform metal coatings of micrometer thicknesses on microscopic glass spheres (microspheres) are often needed as targets for inertial confinement fusion (ICF) experiments. The first part of this paper reviews those methods used successfully to provide metal coated microspheres for ICF targets, including magnetron sputtering, electro- and electroless plating, and chemical vapor pyrolysis. The second part of this paper discusses some of the critical aspects of magnetron sputter coating of microspheres, including substrate requirements, the sticking of microspheres during coating (preventing a uniform coating), and the difficulties in growing the desired dense, smooth, uniform microstructure on continuously moving spherical substrates

  3. Exploring physical and chemical factors influencing the properties of recombinant prion protein and the real-time quaking-induced conversion (RT-QuIC) assay.

    Science.gov (United States)

    Cheng, Keding; Sloan, Angela; Avery, Kristen M; Coulthart, Michael; Carpenter, Michael; Knox, J David

    2014-01-01

    Real-time quaking-induced conversion (RT-QuIC), a highly specific and sensitive assay able to detect low levels of the disease-inducing isoform of the prion protein (PrP(d)) in brain tissue biopsies and cerebral spinal fluid, has great potential to become a method for diagnosing prion disease ante mortem. In order to standardize the assay method for routine analysis, an understanding of how physical and chemical factors affect the stability of the recombinant prion protein (rPrP) substrate and the RT-QuIC assay's sensitivity, specificity, and reproducibility is required. In this study, using sporadic Creutzfeldt-Jakob Disease brain homogenate to seed the reactions and an in vitro-expressed recombinant prion protein, hamster rPrP, as the substrate, the following factors affecting the RT-QuIC assay were examined: salt and substrate concentrations, substrate storage, and pH. Results demonstrated that both the generation of the quality and quantities of rPrP substrate critical to the reaction, as well as the RT-QuIC reaction itself required strict adherence to specific physical and chemical conditions. Once optimized, the RT-QuIC assay was confirmed to be a very specific and sensitive assay method for sCJD detection. Findings in this study indicate that further optimization and standardization of RT-QuIC assay is required before it can be adopted as a routine diagnostic test.

  4. Reduced bed temperature at thermo-chemical conversion of difficult fuels; Saenkt baeddtemperatur vid termokemisk omvandling av svaara braenslen

    Energy Technology Data Exchange (ETDEWEB)

    Niklasson, Fredrik; Haraldsson, Conny; Johansson, Andreas; Claesson, Frida; Baefver, Linda; Ryde, Daniel

    2010-05-15

    needed to obtain reliable quantitative results. Under pyrolysis (in nitrogen), a strong coupling was found between temperature and measured concentrations of alkali and zinc in the flue gas, especially between 750 and 850 deg C. These findings imply that reactors for gasification (or pyrolysis) of waste and biofuels will benefit from being operated at temperatures below 850 deg C to reduce the alkali content in the product gas. On the other hand, there could be other advantages of operating a gasifier at higher temperatures. The influence of the reactor temperature on the release of alkali metals was found to be less pronounced during combustion as compared to pyrolysis. The reason for this could be that oxygen takes part in the reaction scheme controlling the release of the alkali metals, but it could also be a consequence of locally higher temperatures in the fuel particle while burning. The tests showed that a larger fraction of zinc was released during devolatilisation, compared to the alkali metals of which typically less than 10 % was found to be released during devolatilisation. Some additional tests where HCl was added to the fluidizing gas showed, as expected, that the presence of HCl increases the release of alkali metals from the bottom ash. Agglomeration temperatures were determined for two bed sand samples that had been extracted under operating bed temperatures of 870 and 750 deg C in a commercial waste fired FB-boiler. While sand samples were heated in order to find the agglomeration temperature, considerably more alkali metals were released from the sand sampled at 750 deg C. The agglomeration temperature was somewhat lower for this sand, but it was still considerably higher than normal operating bed temperature of the boiler. The present lab-scale study shows that the release of alkali metals and zinc into the flue gas from waste is reduced, or at least considerably decelerated, by a lowered fuel conversion temperature. However, the atmosphere and bed

  5. Coated particle waste form development

    International Nuclear Information System (INIS)

    Oma, K.H.; Buckwalter, C.Q.; Chick, L.A.

    1981-12-01

    Coated particle waste forms have been developed as part of the multibarrier concept at Pacific Northwest Laboratory under the Alternative Waste Forms Program for the Department of Energy. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low-temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed (FB) coaters, screw agitated coaters (SAC), and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated at PNL as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders-of-magnitude increase in chemical durability. Because the aluminum coatings were porous, the superior leach resistance must be due to either a chemical interaction or to a pH buffer effect. Because they are complex, coated waste form processes rank low in process feasibility. Of all the possible coated particle processes, plasma sprayed marbles have the best rating. Carbon coating of pellets by CVD ranked ninth when compared with ten other processes. The plasma-spray-coated marble process ranked sixth out of eleven processes

  6. Photocatalytic TiO2 and Doped TiO2 Coatings to Improve the Hygiene of Surfaces Used in Food and Beverage Processing—A Study of the Physical and Chemical Resistance of the Coatings

    Directory of Open Access Journals (Sweden)

    Parnia Navabpour

    2014-07-01

    Full Text Available TiO2 coatings deposited using reactive magnetron sputtering and spray coating methods, as well as Ag- and Mo-doped TiO2 coatings were investigated as self-cleaning surfaces for beverage processing. The mechanical resistance and retention of the photocatalytic properties of the coatings were investigated over a three-month period in three separate breweries. TiO2 coatings deposited using reactive magnetron sputtering showed better mechanical durability than the spray coated surfaces, whilst the spray-deposited coating showed enhanced retention of photocatalytic properties. The presence of Ag and Mo dopants improved the photocatalytic properties of TiO2 as well as the retention of these properties. The spray-coated TiO2 was the only coating which showed light-induced hydrophilicity, which was retained in the coatings surviving the process conditions.

  7. Surface chemical analysis and ab initio investigations of CsI coated C fiber cathodes for high power microwave sources

    Science.gov (United States)

    Vlahos, Vasilios; Morgan, Dane; LaCour, Matthew; Golby, Ken; Shiffler, Don; Booske, John H.

    2010-02-01

    CsI coated C fiber cathodes are promising electron emitters utilized in field emission applications. Ab initio calculations, in conjunction with experimental investigations on CsI-spray coated C fiber cathodes, were performed in order to better understand the origin of the low turn-on E-field obtained, as compared to uncoated C fibers. One possible mechanism for lowering the turn-on E-field is surface dipole layers reducing the work function. Ab initio modeling revealed that surface monolayers of Cs, CsI, Cs2O, and CsO are all capable of producing low work function C fiber cathodes (1 eV<Φ<1.5 eV), yielding a reduction in the turn-on E-field by as much as ten times, when compared to the bare fiber. Although a CsI-containing aqueous solution is spray deposited on the C fiber surface, energy dispersive x-ray spectroscopy and scanning auger microscopy measurements show coabsorption of Cs and I into the fiber interior and Cs and O on the fiber surface, with no surface I. It is therefore proposed that a cesium oxide (CsxOy) surface coating is responsible, at least in part, for the low turn E-field and superior emission characteristics of this type of fiber cathode. This CsxOy layer could be formed during preconditioning heating. CsxOy surface layers cannot only lower the fiber work function by the formation of surface dipoles (if they are thin enough) but may also enhance surface emission through their ability to emit secondary electrons due to a process of grazing electron impact. These multiple electron emission processes may explain the reported 10-100 fold reduction in the turn-on E-field of coated C fibers.

  8. Chemical treatment and biomimetic coating evaluating in zirconia-alumina ceramics; Avaliacao de tratamentos quimicos e recobrimento biomimetico em ceramicas de alumina-zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Amanda Abati

    2007-07-01

    Ceramic materials, as alumina and zirconia have been explored along the years as biomaterials application. The bio inert nature has been stimulating the development of new alternatives, as chemical treatments to improve the biological application of these ceramics. The biomimetic process of bio inert ceramics for coating apatite is based on soaking the implant in a simulated body fluid, SBF, with ion concentrations nearly equal to those of human blood plasma. The bioactivity of the material is related with the formation of a layer constituted of hydroxyapatite low crystalline, similar to the biological apatite. The biocompatibility associated to the structural properties of the alumina and zirconia has been stimulating the clinical use of these materials, mainly in areas of larger mechanical requests, places not recommended for bioactive hydroxyapatite, for instance. In this work samples of alumina, zirconia doped with Yttria (3% mol) and composites of alumina and zirconia doped with Yttria (3% mol) were prepared by co-precipitation method, calcinate, sintered, chemically treated with solutions of acid phosphoric and sodium hydroxide and them immersed in 1.0 M and 1.5 M SBF. The calcinate powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), gas adsorption (BET) and laser diffraction. The XRD results indicate that the samples are low crystalline. It was observed for BET that the samples present high specific surface area. The results of laser diffraction and SEM showed that the powders are agglomerates. The sintered samples were analyzed by XRD, SEM and X-ray fluorescence (XRF). The phases quantified by Rietveld method were: cubic, tetragonal and monoclinic of the zirconia, besides the phase alpha of the alumina. The chemical treatment with phosphoric acid didn't present a tendency of larger apatite formation in relation to the samples no chemically treated. The treatment with sodium hydroxide provoked accentuated transformation

  9. Fiscal 1997 report on the results on the international standardization R and D. Development of chemical methods to analyze/evaluate metallic coatings of surface treated steel coating sheets; 1997 nendo seika hokokusho kokusai hyojun soseigata kenkyu kaihatsu. Hyomen shori koban mekkiso no kagaku bunseki hyoka hoho no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    The paper studied the international standardization of the chemical analysis method and glow discharge optical emission spectrometry. Chemical composition and coating thickness (g/m{sup 2}) of 14 kinds of specimens including alloy coatings and organic coating with zinc and aluminum as base were analyzed by the above-mentioned methods to examine the relation between the both. As the chemical analysis method, used was inductively coupled plasma atomic emission spectrometry. To study the relation between the methods, it was found to be necessary to recognize morphology at the boundary between the coating and base steel using, for example, scanning electron microscope (SEM) and electro-probe micro-analysis (EPMA). To measure traceability of the analysis method, with the chemical analysis method as a judgement method, it is necessary to make reference materials by coating materials, to use the calibration graph confirmed by the materials and to adopt the glow discharge optical emission spectrometry. On the basis of such way of thinking, drafts were worked out for the international standardization of the chemical analysis method and glow discharge optical emission spectrometry. 7 refs., 117 figs., 33 tabs.

  10. Conversion chimique des surfaces d'alliages d'aluminium sans chrome hexavalent

    OpenAIRE

    Ely , Marion

    2016-01-01

    Conversion coatings are used in aerospace industry to protect the metal from corrosion and to promote paint adhesion. Currently, chromate conversion coatings are used, but chromate is toxic and carcinogenic and its use will be forbidden by the European REACh regulation. TCP (Trivalent Chromium Protection) conversion coatings, are considered as a promising alternative to replace chromate conversion coating. This work focuses on the characterisation of the TCP layer and considers each step of t...

  11. Chemical speciation of arsenic species in human blood serum by liquid chromatography using a phosphatidylcholine-coated ODS column with detection by ICP-MS

    International Nuclear Information System (INIS)

    Hasegawa, Takuya; Ishise, Jotaro; Fukumoto, Yasuharu; Matsuura, Hirotaka; Zhu, Yanbei; Umemura, Tomonari; Haraguchi, Hiroki; Yamamoto, Kazuhito; Naoe, Tomoki

    2007-01-01

    Chemical speciation of arsenic species in human blood serum was performed by high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP-MS) with direct sample injection, where an octadecylsilyl silica (ODS) column coated with phosphatidylcholine (PC) (hereafter known as 'PC-coated ODS column') was used as the separation column. In arsenic species analysis, a citrate buffer solution (pH 4.0) was used as the mobile phase, in which the following reagents were added: sodium 1-dodecanesulfonate (SDS), tetramethylammonium hydroxide (TMAH), which are ion-pair reagents to separate inorganic and organic arsenic species, and 3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate (CHAPS), which is a protein-solubilizing agent to prevent adsorption of proteins on the column. As a result of optimization, five representative arsenic species spiked in human blood serum reference material could be separated from each other within 5 min on the PC-coated ODS column by elution with a 5 mM citrate buffer (pH 4.0) containing 5 mM SDS, 5 mM THAH, and 0.2 mM CHAPS. The detection limits obtained by ICP-MS were 3.1, 2.7, 4.5, 2.5, and 2.5 ng of As g -1 for arsenate (iAs V ), arsenite (iAs III ), monomethylarsonic acid (MMA), dimethylarsenic acid (DMA), and arsenobetaine (AB), respectively, when the injection volume was 20 μL. The present separation system was also applied to speciation analysis of arsenic species in human blood serum collected from a leukemia patient after therapeutic treatment with arsenic. (author)

  12. EB-curing of coatings on wood composite boards

    International Nuclear Information System (INIS)

    Czvikovszky, T.; Czajlic, I.; Takacs, E.; Ille, A.; Salleh, N.G.; Alpar, T.

    1988-01-01

    The industrial radiation processing using low energy electron beam (EB) accelerators lower than 300 keV offers high speed, safe technologies for the chemical conversion of thin layer coatings. Because of the nonselective mode of initiating chain reaction polymerization involving free radicals in synthetic coating layers and suitable substrates, the EB curing of the coatings on woods and papers has particular advantage. Hungary decided to start an up-to-date EB line to process cement-bound (CB) wood chipboards with pigmented acrylic coatings. The CB wood chipboards contain more than 60 % of portland cement and up to 40 % of wood particles. They are produced as large boads of 6 - 16 mm thickness. In their fireproof character and other aspects, they are similar to asbestos-cement boards without containing carcinagenic asbestos, and are stable against moisture and atmospheric influences. EB-cured acrylate coating improved further those properties, and makes them valuable structural material. Oligomers and monomers as the main components of EB curable coatings, the irradiation with a Van de Graaff type electron accelerator of 2 MeV and the results are reported. The oligomers play the most important role in the formation of radiation curable coatings. (K.I.)

  13. Perspective on direct conversion

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, W B

    1963-10-15

    The objective of direct conversion is high electrical output for minimum total cost, and not always high conversion efficiency. The wide range of techniques embracing cryogenics and hot plasma derives from the special requirements of source, environment, and application. Sources include solar and other radiation, nuclear fission and fusion, chemical energy, and heat. Environments and applications range from space vehicles to submarines and from giant power networks to isolated buoys and pocket devices. (auth)

  14. Physical and chemical characterization of Ag-doped Ti coatings produced by magnetron sputtering of modular targets

    International Nuclear Information System (INIS)

    Schmitz, Tobias; Warmuth, Franziska; Werner, Ewald; Hertl, Cornelia; Groll, Jürgen; Gbureck, Uwe; Moseke, Claus

    2014-01-01

    Silver-doped Ti films were produced using a single magnetron sputtering source equipped with a titanium target containing implemented silver modules under variation of bias voltage and substrate temperature. The Ti(Ag) films were characterized regarding their morphology, contact angle, phase composition, silver content and distribution as well as the elution of Ag + ions into cell media. SEM and AFM pictures showed that substrate heating during film deposition supported the formation of even and dense surface layers with small roughness values, an effect that could even be enforced, when a substrate bias voltage was applied instead. The deposition of both Ti and Ag was confirmed by X-ray diffraction. ICP-MS and EDX showed a clear correlation between the applied sputtering parameters and the silver content of the coatings. Surface-sensitive XPS measurements revealed that higher substrate temperatures led to an accumulation of Ag in the near-surface region, while the application of a bias voltage had the opposite effect. Additional elution measurements using ICP-MS showed that the release kinetics depended on the amount of silver located at the film surface and hence could be tailored by variation of the sputter parameters. - Highlights: • Modular targets were used to deposit Ti(Ag) films. • Ag-content is adjustable by bias voltage, sputtering power and substrate temperature. • Coating parameters significantly change film morphology and roughness. • A critical parameter for Ag release is the fraction of silver on the film surface

  15. Tribological performance evaluation of coated steels with TiNbCN subjected to tribo-chemical wear in Ringers solution

    International Nuclear Information System (INIS)

    Caballero G, J.; Aperador, W.; Caicedo, J. C.

    2016-01-01

    With the aim of generating solutions against the deterioration of the joint prostheses, it was studied the tribo-corrosive behavior of titanium niobium carbonitride (TiNbCN) deposited on stainless steel AISI 316 LVM using the technique of magnetron sputtering physical vapor deposition. The tests were performed in a balanced saline solution (Ringers solution) which represents the characteristics of the body fluids, using an equipment where the micro-abrasive wear is generated by the contact of micro particles in the system; the micro-abrasion-corrosion mechanism is described by means of the incorporation of an electrochemical cell consisting of three electrodes. Both the substrate and the coating, were subjected to micro-abrasive wear simultaneously with the electrochemical tests of Tafel polarization curves and electrochemical impedance spectroscopy (EIS); subsequently of the tests, the specimens were analyzed by optical microscopy and scanning electron microscopy characterizing the surface morphology. It was observed that the coating presents an increase in its corrosion and wear resistance with the presence of a simulated biological fluid. The samples were characterized via X-ray diffraction. (Author)

  16. Tribological performance evaluation of coated steels with TiNbCN subjected to tribo-chemical wear in Ringers solution

    Energy Technology Data Exchange (ETDEWEB)

    Caballero G, J.; Aperador, W. [Universidad Militar Nueva Granada, Volta Research Group, 101-80 Bogota (Colombia); Caicedo, J. C., E-mail: g.ing.materiales@gmail.com [Universidad del Valle, Tribology Polymers, Powder Metallurgy and Processing of Solid Recycled Research Group, Cali (Colombia)

    2016-11-01

    With the aim of generating solutions against the deterioration of the joint prostheses, it was studied the tribo-corrosive behavior of titanium niobium carbonitride (TiNbCN) deposited on stainless steel AISI 316 LVM using the technique of magnetron sputtering physical vapor deposition. The tests were performed in a balanced saline solution (Ringers solution) which represents the characteristics of the body fluids, using an equipment where the micro-abrasive wear is generated by the contact of micro particles in the system; the micro-abrasion-corrosion mechanism is described by means of the incorporation of an electrochemical cell consisting of three electrodes. Both the substrate and the coating, were subjected to micro-abrasive wear simultaneously with the electrochemical tests of Tafel polarization curves and electrochemical impedance spectroscopy (EIS); subsequently of the tests, the specimens were analyzed by optical microscopy and scanning electron microscopy characterizing the surface morphology. It was observed that the coating presents an increase in its corrosion and wear resistance with the presence of a simulated biological fluid. The samples were characterized via X-ray diffraction. (Author)

  17. A Model for Generation of Martian Surface Dust, Soil and Rock Coatings: Physical vs. Chemical Interactions, and Palagonitic Plus Hydrothermal Alteration

    Science.gov (United States)

    Bishop, J. L.; Murchie, S.; Pieters, C.; Zent, A.

    1999-01-01

    This model is one of many possible scenarios to explain the generation of the current surface material on Mars using chemical, magnetic and spectroscopic data from Mars and geologic analogs from terrestrial sites. One basic premise is that there are physical and chemical interactions of the atmospheric dust particles and that these two processes create distinctly different results. Physical processes distribute dust particles on rocks, forming physical rock coatings, and on the surface between rocks forming soil units; these are reversible processes. Chemical reactions of the dust/soil particles create alteration rinds on rock surfaces or duricrust surface units, both of which are relatively permanent materials. According to this model the mineral components of the dust/soil particles are derived from a combination of "typical" palagonitic weathering of volcanic ash and hydrothermally altered components, primarily from steam vents or fumeroles. Both of these altered materials are composed of tiny particles, about 1 micron or smaller, that are aggregates of silicates and iron oxide/oxyhydroxide/sulfate phases. Additional information is contained in the original extended abstract.

  18. Growth, microstructure, and field-emission properties of synthesized diamond film on adamantane-coated silicon substrate by microwave plasma chemical vapor deposition

    International Nuclear Information System (INIS)

    Tiwari, Rajanish N.; Chang Li

    2010-01-01

    Diamond nucleation on unscratched Si surface is great importance for its growth, and detailed understanding of this process is therefore desired for many applications. The pretreatment of the substrate surface may influence the initial growth period. In this study, diamond films have been synthesized on adamantane-coated crystalline silicon {100} substrate by microwave plasma chemical vapor deposition from a gaseous mixture of methane and hydrogen gases without the application of a bias voltage to the substrates. Prior to adamantane coating, the Si substrates were not pretreated such as abraded/scratched. The substrate temperature was ∼530 deg. C during diamond deposition. The deposited films are characterized by scanning electron microscopy, Raman spectrometry, x-ray diffraction, and x-ray photoelectron spectroscopy. These measurements provide definitive evidence for high-crystalline quality diamond film, which is synthesized on a SiC rather than clean Si substrate. Characterization through atomic force microscope allows establishing fine quality criteria of the film according to the grain size of nanodiamond along with SiC. The diamond films exhibit a low-threshold (55 V/μm) and high current-density (1.6 mA/cm 2 ) field-emission (FE) display. The possible mechanism of formation of diamond films and their FE properties have been demonstrated.

  19. The Effect of Sintering Oxygen Partial Pressure on a SmBiO3 Buffer Layer for Coated Conductors via Chemical Solution Deposition

    Directory of Open Access Journals (Sweden)

    Xiaolei Zhu

    2016-10-01

    Full Text Available The application of high-temperature YBa2Cu3O7−δ (YBCO superconducting material is a considerable prospect for the growing energy shortages. Here, SmBiO3 (SBO films were deposited on (100-orientated yttrium-stabilized zirconia (YSZ simple crystal substrates via the chemical solution deposition (CSD approach for coated conductors, and the effects of sintering oxygen partial pressure on SBO films were studied. The crystalline structures and surface morphologies of SBO films were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and atomic force microscope (AFM. The optimized growth temperature, the intensity ratios of the SBO (200 peak to the SBO (111 peak, and the crystallinities of SBO films increased with the sintering oxygen partial pressure. The SEM and AFM images displayed a smooth and well-distributed surface in the argon atmosphere. The subsequent YBCO films with superconducting transition temperatures (Tc = 89.5 K, 90.2 K, and 86.2 K and critical current densities (Jc = 0.88 MA/cm2, 1.69 MA/cm2, and 0.09 MA/cm2; 77 K, self-field were deposited to further check the qualities of the SBO layer. These results indicated that sintering oxygen partial pressure had an effect on the epitaxial growth of the SBO buffer layer and YBCO superconducting properties. The experimental results may be a usable reference for the epitaxial growth of YBCO-coated conductors and other oxides.

  20. Two-component spin-coated Ag/CNT composite films based on a silver heterogeneous nucleation mechanism adhesion-enhanced by mechanical interlocking and chemical grafting

    Science.gov (United States)

    Zhang, Yang; Kang, Zhixin; Bessho, Takeshi

    2017-03-01

    In this paper, a new method for the synthesis of silver carbon nanotube (Ag/CNT) composite films as conductive connection units for flexible electronic devices is presented. This method is about a two-component solution process by spin coating with an after-treatment annealing process. In this method, multi-walled carbon nanotubes (MWCNTs) act as the core of silver heterogeneous nucleation, which can be observed and analyzed by a field-emission scanning electron microscope. With the effects of mechanical interlocking, chemical grafting, and annealing, the interfacial adhesive strength between films and PET sheets was enhanced to 12 N cm-1. The tensile strength of the Ag/CNT composite films was observed to increase by 38% by adding 5 g l-1 MWCNTs. In the four-probe method, the resistivity of Ag/CNT-5 declined by 78.2% compared with pristine Ag films. The anti-fatigue performance of the Ag/CNT composite films was monitored by cyclic bending deformation and the results revealed that the growth rate of electrical resistance during the deformation was obviously retarded. As for industrial application, this method provides an efficient low-cost way to prepare Ag/CNT composite films and can be further applied to other coating systems.

  1. Comparative physical, chemical and biological assessment of simple and titanium-doped ovine dentine-derived hydroxyapatite coatings fabricated by pulsed laser deposition

    Science.gov (United States)

    Duta, L.; Mihailescu, N.; Popescu, A. C.; Luculescu, C. R.; Mihailescu, I. N.; Çetin, G.; Gunduz, O.; Oktar, F. N.; Popa, A. C.; Kuncser, A.; Besleaga, C.; Stan, G. E.

    2017-08-01

    We report on the synthesis by Pulsed Laser Deposition of simple and Ti doped hydroxyapatite thin films of biological (ovine dentine) origin. Detailed physical, chemical, mechanical and biological investigations were performed. Morphological examination of films showed a surface composed of spheroidal particulates, of micronic size. Compositional analyses pointed to the presence of typical natural doping elements of bone, along with a slight non-stoichiometry of the deposited films. Structural investigations proved the monophasic hydroxyapatite nature of both simple and Ti doped films. Ti doping of biological hydroxyapatite induced an overall downgrade of the films crystallinity together with an increase of the films roughness. It is to be emphasized that bonding strength values measured at film/Ti substrate interface were superior to the minimum value imposed by International Standards regulating the load-bearing implant coatings. In vitro tests on Ti doped structures, compared to simple ones, revealed excellent biocompatibility in human mesenchymal stem cell cultures, a higher proliferation rate and a good cytocompatibility. The obtained results aim to elucidate the overall positive role of Ti doping on the hydroxyapatite films performance, and demonstrate the possibility to use this novel type of coatings as feasible materials for future implantology applications.

  2. Catalytic Conversion of Carbohydrates

    DEFF Research Database (Denmark)

    Osmundsen, Christian Mårup

    a renewable route to aromatics. The conversion of biomass by high temperature processes is a desirable prospect due to the high volumetric production rates which can be achieved, and the ability of these types of processes to convert a wide range of substrates. Current processes however typically have rather...... with the production of commodity chemicals from the most abundantly available renewable source of carbon, carbohydrates. The production of alkyl lactates by the Lewis acid catalyzed conversion of hexoses is an interesting alternative to current fermentation based processes. A range of stannosilicates were...... to be an efficient initial conversion step in the utilization of biomass for chemicals production. The shift from an oil based chemical industry to one based on renewable resources is bound to happen sooner or later, however the environmental problems associated with the burning of fossil resources means...

  3. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  4. Fabrication of 100 A class, 1 m long coated conductor tapes by metal organic chemical vapor deposition and pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V.; Lee, H.G.; Li, Y.; Xiong, X.; Qiao, Y.; Reeves, J.; Xie, Y.; Knoll, A.; Lenseth, K

    2003-10-15

    SuperPower has been scaling up YBa{sub 2}Cu{sub 3}O{sub x}-based second-generation superconducting tapes by techniques such as pulsed laser deposition (PLD) using industrial laser and metal organic chemical vapor deposition (MOCVD). Both techniques offer advantage of high deposition rates, which is important for high throughput. Using highly-polished substrates produced in a reel-to-reel polishing facility and buffer layers deposited in a pilot ion beam assisted deposition facility, meter-long second-generation high temperature superconductor tapes have been produced. 100 A class, meter-long coated conductor tapes have been reproducibly demonstrated in this work by both MOCVD and PLD. The best results to date are 148 A over 1.06 m by MOCVD and 135 A over 1.1 m by PLD using industrial laser.

  5. Sm-doped CeO2 single buffer layer for YBCO coated conductors by polymer assisted chemical solution deposition (PACSD) method

    International Nuclear Information System (INIS)

    Li, G.; Pu, M.H.; Sun, R.P.; Wang, W.T.; Wu, W.; Zhang, X.; Yang, Y.; Cheng, C.H.; Zhao, Y.

    2008-01-01

    An over 150 nm thick Sm 0.2 Ce 0.8 O 1.9-x (SCO) single buffer layer has been deposited on bi-axially textured NiW (2 0 0) alloy substrate. Highly in-plane and out-of-plane oriented, dense, smooth and crack free SCO single layer has been obtained via a polymer-assisted chemical solution deposition (PACSD) approach. YBCO thin film has been deposited equally via a PACSD route on the SCO-buffered NiW, the as grown YBCO yielding a sharp transition at T c0 = 87 K as well as J c (0 T, 77 K) ∼ 1 MA/cm 2 . These results indicates that RE (lanthanides other than Ce) doping may be an effective approach to improve the critical thickness of solution derived CeO 2 film, which renders it a promising candidate as single buffer layer for YBCO coated conductors

  6. Phase Evolution of YBa2Cu3O7-x films by all-chemical solution deposition route for coated conductors

    DEFF Research Database (Denmark)

    Yue, Zhao; Tang, Xiao; Wu, Wei

    2014-01-01

    In order to understand the all-chemical-solution-deposition (CSD) processes for manufacturing coated conductors, we investigated the phase evolution of YBa2Cu3O7 (YBCO) films deposited by a low-fluorine metal-organic solution deposition (LF-MOD) method on CSD derived Ce0.9La0.1O2/Gd2Zr2O7/Ni......W. It is shown that the phase transition from the pyrolyzed film to fully converted YBCO film in the LF-MOD process is similar to that in typical trifluoroacetates-metal organic deposition (TFA-MOD) processes even though the amount of TFA in the solution is reduced by almost one half compared with typical TFA...

  7. Synthesis and characterization of polyethylene glycol (PEG) coated Fe3O4 nanoparticles by chemical co-precipitation method for biomedical applications.

    Science.gov (United States)

    Anbarasu, M; Anandan, M; Chinnasamy, E; Gopinath, V; Balamurugan, K

    2015-01-25

    Polyethylene glycol (PEG) coated Fe3O4 nanoparticles were synthesized by chemical co-precipitation method. With polyethylene glycol (PEG) as a stabilizer and dispersant. The X-ray diffraction and selected area electron diffraction (SAED) results show that the cubic inverse spinel structure of pure phase polycrystalline Fe3O4 was obtained. The scanning electron microscopy (SEM) and field emission transmission electron microscopy (FE-TEM) results exhibited that the resulted Fe3O4 nanoparticles were roughly spherical in shape with narrow size distribution and homogenous shape. Fourier transform infrared spectroscopy (FT-IR) results suggested that PEG indicated with Fe3O4 via its carbonyl groups. Results of vibrating sample magnetometer (VSM) indicated that the prepared Fe3O4 nanoparticles exhibit superparamagnetic behavior and high saturation magnetization at room temperature. Such Fe3O4 nanoparticles with favorable size and tunable magnetic properties are promising biomedical applications. Copyright © 2014. Published by Elsevier B.V.

  8. Reactions of N2O5 with Salty and Surfactant-Coated Glycerol: Interfacial Conversion of Br- to Br2 Mediated by Alkylammonium Cations.

    Science.gov (United States)

    Shaloski, Michael A; Gord, Joseph R; Staudt, Sean; Quinn, Sarah L; Bertram, Timothy H; Nathanson, Gilbert M

    2017-05-18

    Gas-liquid scattering and product-yield experiments are used to investigate reactions of N 2 O 5 with glycerol containing Br - and surfactant ions. N 2 O 5 oxidizes Br - to Br 2 for every solution tested: 2.7 M NaBr, 0.03 M tetrahexylammonium bromide (THABr), 0.03 M THABr + 0.5 M NaBr, 0.03 M THABr + 0.5 M NaCl, 0.03 M THABr + 0.01 M sodium dodecyl sulfate (SDS), and 0.01 M cetyltrimethylammonium bromide (CTABr). N 2 O 5 also reacts with glycerol itself to produce mono- and dinitroglycerin. Surface tension measurements indicate that 0.03 M THABr and 2.7 M NaBr have similar interfacial Br - concentrations, though their bulk Br - concentrations differ by 90-fold. We find that twice as much Br 2 is produced in the presence of THA + , implying that the conversion of Br - to Br 2 is initiated at the interface, perhaps mediated by the charged, hydrophobic pocket within the surface THA + cation. The addition of 0.5 M NaBr, 0.5 M NaCl, or 0.01 M SDS to 0.03 M THABr lowers the Br 2 production rate by 23%, 63%, and 67% of the THABr value, respectively. When CTA + is substituted for THA + , Br 2 production drops to 12% of the THABr value. The generation of Br 2 under such different conditions implies that trace amounts of surface-active alkylammonium ions can catalyze interfacial N 2 O 5 reactions, even when salts and other surfactants are present.

  9. Chemical nature and structure of organic coating of quantum dots is crucial for their application in imaging diagnostics

    Science.gov (United States)

    Bakalova, Rumiana; Zhelev, Zhivko; Kokuryo, Daisuke; Spasov, Lubomir; Aoki, Ichio; Saga, Tsuneo

    2011-01-01

    Background: One of the most attractive properties of quantum dots is their potential to extend the opportunities for fluorescent and multimodal imaging in vivo. The aim of the present study was to clarify whether the composition and structure of organic coating of nanoparticles are crucial for their application in vivo. Methods: We compared quantum dots coated with non-crosslinked amino-functionalized polyamidoamine (PAMAM) dendrimers, quantum dots encapsulated in crosslinked carboxyl-functionalized PAMAM dendrimers, and silica-shelled amino-functionalized quantum dots. A multimodal fluorescent and paramagnetic quantum dot probe was also developed and analyzed. The probes were applied intravenously in anesthetized animals for visualization of brain vasculature using two-photon excited fluorescent microscopy and visualization of tumors using fluorescent IVIS® imaging (Caliper Life Sciences, Hopkinton, MA) and magnetic resonance imaging. Results: Quantum dots coated with non-crosslinked dendrimers were cytotoxic. They induced side effects in vivo, including vasodilatation with a decrease in mean arterial blood pressure and heart rate. The quantum dots penetrated the vessels, which caused the quality of fluorescent imaging to deteriorate. Quantum dots encapsulated in crosslinked dendrimers had low cytotoxicity and were biocompatible. In concentrations quantum dots/kg bodyweight, these nanoparticles did not affect blood pressure and heart rate, and did not induce vasodilatation or vasoconstriction. PEGylation (PEG [polyethylene glycol]) was an indispensable step in development of a quantum dot probe for in vivo imaging, based on silica-shelled quantum dots. The non-PEGylated silica-shelled quantum dots possessed low colloidal stability in high-salt physiological fluids, accompanied by rapid aggregation in vivo. The conjugation of silica-shelled quantum dots with PEG1100 increased their stability and half-life in the circulation without significant enhancement of their

  10. Preparation and corrosion resistance of magnesium phytic acid/hydroxyapatite composite coatings on biodegradable AZ31 magnesium alloy.

    Science.gov (United States)

    Zhang, Min; Cai, Shu; Zhang, Feiyang; Xu, Guohua; Wang, Fengwu; Yu, Nian; Wu, Xiaodong

    2017-06-01

    In this work, a magnesium phytic acid/hydroxyapatite composite coating was successfully prepared on AZ31 magnesium alloy substrate by chemical conversion deposition technology with the aim of improving its corrosion resistance and bioactivity. The influence of hydroxyapatite (HA) content on the microstructure and corrosion resistance of the coatings was investigated. The results showed that with the increase of HA content in phytic acid solution, the cracks on the surface of the coatings gradually reduced, which subsequently improved the corrosion resistance of these coated magnesium alloy. Electrochemical measurements in simulated body fluid (SBF) revealed that the composite coating with 45 wt.% HA addition exhibited superior surface integrity and significantly improved corrosion resistance compared with the single phytic acid conversion coating. The results of the immersion test in SBF showed that the composite coating could provide more effective protection for magnesium alloy substrate than that of the single phytic acid coating and showed good bioactivity. Magnesium phytic acid/hydroxyapatite composite, with the desired bioactivity, can be synthesized through chemical conversion deposition technology as protective coatings for surface modification of the biodegradable magnesium alloy implants. The design idea of the new type of biomaterial is belong to the concept of "third generation biomaterial". Corrosion behavior and bioactivity of coated magnesium alloy are the key issues during implantation. In this study, preparation and corrosion behavior of magnesium phytic acid/hydroxyapatite composite coatings on magnesium alloy were studied. The basic findings and significance of this paper are as follows: 1. A novel environmentally friendly, homogenous and crack-free magnesium phytic acid/hydroxyapatite composite coating was fabricated on AZ31 magnesium alloy via chemical conversion deposition technology with the aim of enhancing its corrosion resistance and

  11. Boundary layer measurements of the OH radical in the vicinity of an isolated power plant plume - SO2 and NO2 chemical conversion times

    Science.gov (United States)

    Davis, D. D.; Philen, D.; Mcgee, T.; Heaps, W.

    1979-01-01

    Direct measurements of the OH radical in the vicinity of an isolated power plant plume are reported. These measurements were used to estimate the conversion time of SO2 to H2SO4-sulfate aerosol via the initiating step OH + SO2 + M yields HSO3. Using the near-high-noon measured value of OH (9.5 million per cu cm), resulted in a 1/e conversion time of 1.4 days. The latter lifetime would correspond to a conversion rate of about 2%/hr. When the lifetime calculation was modified to take into consideration the OH diurnal cycle, the 1/e conversion time for SO2 was found to be 4.4 days, giving an apparent overall rate of conversion of about 0.7%/hr. Similar calculations carried out for the conversion of NO2 to NHO3 resulted in 1/e lifetimes for NO2 of 2-3 h for midday time periods.

  12. Surface chemical functionalisation of epoxy photoresist-based microcantilevers with organic-coated TiO2 nanocrystals

    DEFF Research Database (Denmark)

    Ingrosso, C.; Sardella, E.; Keller, S. S.

    2012-01-01

    In this Letter, a solution-based approach has been used for chemically immobilising oleic acid (OLEA)-capped TiO2 nanocrystals (NCs) on the surface of microcantilevers formed of SU-8, a negative tone epoxy photoresist. The immobilisation has been carried out at room temperature, under visible lig...

  13. Uranium conversion; Urankonvertering

    Energy Technology Data Exchange (ETDEWEB)

    Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina [Swedish Defence Research Agency (FOI), Stockholm (Sweden)

    2006-03-15

    FOI, has performed a study on uranium conversion processes that are of importance in the production of different uranium compounds in the nuclear industry. The same conversion processes are of interest both when production of nuclear fuel and production of fissile material for nuclear weapons are considered. Countries that have nuclear weapons ambitions, with the intention to produce highly enriched uranium for weapons purposes, need some degree of uranium conversion capability depending on the uranium feed material available. This report describes the processes that are needed from uranium mining and milling to the different conversion processes for converting uranium ore concentrate to uranium hexafluoride. Uranium hexafluoride is the uranium compound used in most enrichment facilities. The processes needed to produce uranium dioxide for use in nuclear fuel and the processes needed to convert different uranium compounds to uranium metal - the form of uranium that is used in a nuclear weapon - are also presented. The production of uranium ore concentrate from uranium ore is included since uranium ore concentrate is the feed material required for a uranium conversion facility. Both the chemistry and principles or the different uranium conversion processes and the equipment needed in the processes are described. Since most of the equipment that is used in a uranium conversion facility is similar to that used in conventional chemical industry, it is difficult to determine if certain equipment is considered for uranium conversion or not. However, the chemical conversion processes where UF{sub 6} and UF{sub 4} are present require equipment that is made of corrosion resistant material.

  14. Study of chromate coatings by radioisotope tracing

    International Nuclear Information System (INIS)

    Drozda, T.; Maleczki, E.; Farkas, G.

    1984-01-01

    New radioactive tracer methods were developed to determine chromium(III) and total chromium [chromium(III)+chromium(VI)] content simultaneously. They are capable of investigating solutions and the conversion coating itself in the solid phase, respectively. The increase of chromium(III) concentration in the yellow chromate coating, and the chromium(III) to total chromium ratio in the conversion coating were determined as a function of the treating period. (author)

  15. Comparing REACH Chemical Safety Assessment information with practice-a case-study of polymethylmethacrylate (PMMA) in floor coating in The Netherlands.

    Science.gov (United States)

    Spee, Ton; Huizer, Daan

    2017-10-01

    On June 1st, 2007 the European regulation on Registration, Evaluation and Restriction of Chemical substances (REACH) came into force. Aim of the regulation is safe use of chemicals for humans and for the environment. The core element of REACH is chemical safety assessment of chemicals and communication of health and safety hazards and risk management measures throughout the supply chain. Extended Safety Data Sheets (Ext-SDS) are the primary carriers of health and safety information. The aim of our project was to find out whether the actual exposure to methyl methacrylate (MMA) during the application of polymethylmethacrylate (PMMA) in floor coatings as assessed in the chemical safety assessment, reflect the exposure situations as observed in the Dutch building practice. Use of PMMA flooring and typical exposure situations during application were discussed with twelve representatives of floor laying companies. Representative situations for exposure measurements were designated on the basis of this inventory. Exposure to MMA was measured in the breathing zone of the workers at four construction sites, 14 full shift samples and 14 task based samples were taken by personal air sampling. The task-based samples were compared with estimates from the Targeted Risk Assessment Tool (v3.1) of the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC-TRA) as supplied in the safety assessment from the manufacturer. For task-based measurements, in 12 out of 14 (86%) air samples measured exposure was higher than estimated exposure. Recalculation with a lower ventilation rate (50% instead of 80%) together with a higher temperature during mixing (40°C instead of 20°C) in comparison with the CSR, reduced the number of underestimated exposures to 10 (71%) samples. Estimation with the EMKG-EXPO-Tool resulted in unsafe exposure situations for all scenarios, which is in accordance with the measurement outcomes. In indoor situations, 5 out of 8 full shift exposures (62

  16. Biodegradable films and spray coatings as eco-friendly alternative to petro-chemical derived mulching films

    Directory of Open Access Journals (Sweden)

    G. Vox

    2013-09-01

    Full Text Available The use of plastic mulching films in horticulture causes the serious drawback of huge amount of wastes to be disposed of at the end of their lifetime. Several pre-competitive research products based on raw materials coming from renewable sources were recently developed to be used as biodegradable materials for soil mulching. Biodegradable materials are designed in order both to retain their mechanical and physical properties during their using time and to degrade at the end of their lifetime. These materials can be integrated directly in the soil in order to biodegrade because the bacterial flora transforms them in carbon dioxide or methane, water and biomass. The innovative materials can be obtained using natural polymers, such as starch, cellulose, chitosan, alginate and glucomannan. Biodegradable extruded mulching films were performed by means of thermo-plasticizing process. Spray mulch coatings were realized directly in field, by spraying water solutions based on natural polysaccharides, thus covering the cultivated soil with a protective thin geo-membrane. In this paper an overview on the formulation development, processing understanding, field performance, mechanical and radiometric properties of these innovative materials for soil mulching is presented. In field the biodegradable mulching films showed suitable mechanical properties if compared to the low density polyethylene films. The radiometric properties and their effect on the temperature condition and on weed control in the mulched soil were evaluated too. At the end of their lifetime the biodegradable materials were shattered and buried into the soil together with plants.

  17. Catalytic Conversion of Biofuels

    DEFF Research Database (Denmark)

    Jørgensen, Betina

    This thesis describes the catalytic conversion of bioethanol into higher value chemicals. The motivation has been the unavoidable coming depletion of the fossil resources. The thesis is focused on two ways of utilising ethanol; the steam reforming of ethanol to form hydrogen and the partial oxida...

  18. Comparative physical, chemical and biological assessment of simple and titanium-doped ovine dentine-derived hydroxyapatite coatings fabricated by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Duta, L.; Mihailescu, N.; Popescu, A.C.; Luculescu, C.R. [National Institute for Lasers, Plasma and Radiation Physics, 077125 Magurele (Romania); Mihailescu, I.N., E-mail: ion.mihailescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, 077125 Magurele (Romania); Çetin, G.; Gunduz, O. [Department of Bioengineering, Faculty of Engineering, Marmara University, 34722 Istanbul (Turkey); Oktar, F.N. [Department of Bioengineering, Faculty of Engineering, Marmara University, 34722 Istanbul (Turkey); Department of Medical Imaging Techniques, Vocational School of Health Services, Marmara University, 34668 Istanbul (Turkey); Nanotechnology and Biomaterials Application & Research Centre, Marmara University, 34722 Istanbul (Turkey); Popa, A.C. [National Institute of Materials Physics, 077125 Magurele (Romania); Army Centre for Medical Research, 010195 Bucharest (Romania); Kuncser, A.; Besleaga, C. [National Institute of Materials Physics, 077125 Magurele (Romania); Stan, G.E., E-mail: george_stan@infim.ro [National Institute of Materials Physics, 077125 Magurele (Romania)

    2017-08-15

    Highlights: • Pulsed laser deposition of Ti doped hydroxyapatite films of biological origin. • Downgrade of films’ crystallinity and increase of roughness induced by Ti doping. • Bonding strength values superior to minimum value imposed by ISO standards. • Excellent biocompatibility in hMSC cultures of Ti doped structures. • Ti doped hydroxyapatite films as feasible materials for implantology applications. - Abstract: We report on the synthesis by Pulsed Laser Deposition of simple and Ti doped hydroxyapatite thin films of biological (ovine dentine) origin. Detailed physical, chemical, mechanical and biological investigations were performed. Morphological examination of films showed a surface composed of spheroidal particulates, of micronic size. Compositional analyses pointed to the presence of typical natural doping elements of bone, along with a slight non-stoichiometry of the deposited films. Structural investigations proved the monophasic hydroxyapatite nature of both simple and Ti doped films. Ti doping of biological hydroxyapatite induced an overall downgrade of the films crystallinity together with an increase of the films roughness. It is to be emphasized that bonding strength values measured at film/Ti substrate interface were superior to the minimum value imposed by International Standards regulating the load-bearing implant coatings. In vitro tests on Ti doped structures, compared to simple ones, revealed excellent biocompatibility in human mesenchymal stem cell cultures, a higher proliferation rate and a good cytocompatibility. The obtained results aim to elucidate the overall positive role of Ti doping on the hydroxyapatite films performance, and demonstrate the possibility to use this novel type of coatings as feasible materials for future implantology applications.

  19. Comparative physical, chemical and biological assessment of simple and titanium-doped ovine dentine-derived hydroxyapatite coatings fabricated by pulsed laser deposition

    International Nuclear Information System (INIS)

    Duta, L.; Mihailescu, N.; Popescu, A.C.; Luculescu, C.R.; Mihailescu, I.N.; Çetin, G.; Gunduz, O.; Oktar, F.N.; Popa, A.C.; Kuncser, A.; Besleaga, C.; Stan, G.E.

    2017-01-01

    Highlights: • Pulsed laser deposition of Ti doped hydroxyapatite films of biological origin. • Downgrade of films’ crystallinity and increase of roughness induced by Ti doping. • Bonding strength values superior to minimum value imposed by ISO standards. • Excellent biocompatibility in hMSC cultures of Ti doped structures. • Ti doped hydroxyapatite films as feasible materials for implantology applications. - Abstract: We report on the synthesis by Pulsed Laser Deposition of simple and Ti doped hydroxyapatite thin films of biological (ovine dentine) origin. Detailed physical, chemical, mechanical and biological investigations were performed. Morphological examination of films showed a surface composed of spheroidal particulates, of micronic size. Compositional analyses pointed to the presence of typical natural doping elements of bone, along with a slight non-stoichiometry of the deposited films. Structural investigations proved the monophasic hydroxyapatite nature of both simple and Ti doped films. Ti doping of biological hydroxyapatite induced an overall downgrade of the films crystallinity together with an increase of the films roughness. It is to be emphasized that bonding strength values measured at film/Ti substrate interface were superior to the minimum value imposed by International Standards regulating the load-bearing implant coatings. In vitro tests on Ti doped structures, compared to simple ones, revealed excellent biocompatibility in human mesenchymal stem cell cultures, a higher proliferation rate and a good cytocompatibility. The obtained results aim to elucidate the overall positive role of Ti doping on the hydroxyapatite films performance, and demonstrate the possibility to use this novel type of coatings as feasible materials for future implantology applications.