WorldWideScience

Sample records for bimetallic corrosion

  1. Corrosion

    Science.gov (United States)

    Slabaugh, W. H.

    1974-01-01

    Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

  2. Corrosion Failures in Marine Environment

    Directory of Open Access Journals (Sweden)

    R. Krishnan

    1985-04-01

    Full Text Available This paper gives a brief description of typical marine environments and the most common form of corrosion of materials used in this environment. Some typical case histories of failures pertaining to pitting, bimetallic corrosion, dealloying, cavitation and stress corrosion cracking are illustrated as typical examples of corrosion failures.

  3. Biosensors Incorporating Bimetallic Nanoparticles

    Directory of Open Access Journals (Sweden)

    John Rick

    2015-12-01

    Full Text Available This article presents a review of electrochemical bio-sensing for target analytes based on the use of electrocatalytic bimetallic nanoparticles (NPs, which can improve both the sensitivity and selectivity of biosensors. The review moves quickly from an introduction to the field of bio-sensing, to the importance of biosensors in today’s society, the nature of the electrochemical methods employed and the attendant problems encountered. The role of electrocatalysts is introduced with reference to the three generations of biosensors. The contributions made by previous workers using bimetallic constructs, grouped by target analyte, are then examined in detail; following which, the synthesis and characterization of the catalytic particles is examined prior to a summary of the current state of endeavor. Finally, some perspectives for the future of bimetallic NPs in biosensors are given.

  4. Physical and Numerical Analysis of Extrusion Process for Production of Bimetallic Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Misiolek, W.Z.; Sikka, V.K.

    2006-08-10

    Bimetallic tubes are used for very specific applications where one of the two metals provides strength and the other provides specific properties such as aqueous corrosion and carburization, coking resistance, and special electrical and thermal properties. Bimetallic tubes have application in pulp and paper industry for heat-recovery boilers, in the chemical industry for ethylene production, and in the petrochemical industry for deep oil well explorations. Although bimetallic tubes have major applications in energy-intensive industry, they often are not used because of their cost and manufacturing sources in the United States. This project was intended to address both of these issues.

  5. Characterization and Preparation of Bimetallic Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Bing; Joe; Hwang; Ching; Hsiang; Chen; Loka; Subramanyam; Sarma; Din-gao; Liu; Jyh; Fu; Lee

    2007-01-01

    1 Results Bimetallic particles in the nanometer size range are of substantial interest due to their vast applications in catalysis[1].The synthesis of bimetallic nanoparticles with definite size with a well-control over their nanostructure remains a challenging problem.Thus there exists a great demand for both synthesis and atomic level characterization of nanostructure of bimetallic nanoparticles (NPs).With the recent advent of high-intensity tunable sources of X-rays,now available at synchrotron radia...

  6. Catalysis on singly dispersed bimetallic sites

    Science.gov (United States)

    Zhang, Shiran; Nguyen, Luan; Liang, Jin-Xia; Shan, Junjun; Liu, Jingyue; Frenkel, Anatoly I.; Patlolla, Anitha; Huang, Weixin; Li, Jun; Tao, Franklin

    2015-08-01

    A catalytic site typically consists of one or more atoms of a catalyst surface that arrange into a configuration offering a specific electronic structure for adsorbing or dissociating reactant molecules. The catalytic activity of adjacent bimetallic sites of metallic nanoparticles has been studied previously. An isolated bimetallic site supported on a non-metallic surface could exhibit a distinctly different catalytic performance owing to the cationic state of the singly dispersed bimetallic site and the minimized choices of binding configurations of a reactant molecule compared with continuously packed bimetallic sites. Here we report that isolated Rh1Co3 bimetallic sites exhibit a distinctly different catalytic performance in reduction of nitric oxide with carbon monoxide at low temperature, resulting from strong adsorption of two nitric oxide molecules and a nitrous oxide intermediate on Rh1Co3 sites and following a low-barrier pathway dissociation to dinitrogen and an oxygen atom. This observation suggests a method to develop catalysts with high selectivity.

  7. Laser deposition of bimetallic island films

    Science.gov (United States)

    Kucherik, A. O.; Arakelyan, S. M.; Kutrovskaya, S. V.; Osipov, A. V.; Istratov, A. V.; Vartanyan, T. A.; Itina, T. E.

    2016-08-01

    In this work the results of a bimetallic Au-Ag structure deposition from the colloidal system by nanosecond laser radiation are presented. The formation of the extended arrays of gold and silver nanoparticles with controlled morphology is examined. We report the results of formation bimetallic islands films with various electrical and optical properties. The changes in the optical properties of the obtained thin films are found to depend on their morphology.

  8. Magneto-optical response in bimetallic metamaterials

    CERN Document Server

    Atmatzakis, Evangelos; Fedotov, Vassili; Vienne, Guillaume; Zheludev, Nikolay I

    2016-01-01

    We demonstrate resonant Faraday polarization rotation in plasmonic arrays of bimetallic nano-ring resonators consisting of Au and Ni sections. This metamaterial design allows to optimize the trade-off between the enhancement of magneto-optical effects and plasmonic dissipation. Although Ni sections correspond to as little as ~6% of the total surface of the metamaterial, the resulting magneto-optically induced polarization rotation is equal to that of a continuous film. Such bimetallic metamaterials can be used in compact magnetic sensors, active plasmonic components and integrated photonic circuits.

  9. Stainless Steel to Titanium Bimetallic Transitions

    Energy Technology Data Exchange (ETDEWEB)

    Kaluzny, J. A. [Fermilab; Grimm, C. [Fermilab; Passarelli, D. [Fermilab

    2015-01-01

    In order to use stainless steel piping in an LCLS-II (Linac Coherent Light Source Upgrade) cryomodule, stainless steel to titanium bimetallic transitions are needed to connect the stainless steel piping to the titanium cavity helium vessel. Explosion bonded stainless steel to titanium transition pieces and bimetallic transition material samples have been tested. A sample transition tube was subjected to tests and x-ray examinations between tests. Samples of the bonded joint material were impact and tensile tested at room temperature as well as liquid helium temperature. The joint has been used successfully in horizontal tests of LCLS-II cavity helium vessels and is planned to be used in LCLS-II cryomodules. Results of material sample and transition tube tests will be presented.

  10. Bimetallic redox synergy in oxidative palladium catalysis.

    Science.gov (United States)

    Powers, David C; Ritter, Tobias

    2012-06-19

    Polynuclear transition metal complexes, which are embedded in the active sites of many metalloenzymes, are responsible for effecting a diverse array of oxidation reactions in nature. The range of chemical transformations remains unparalleled in the laboratory. With few noteworthy exceptions, chemists have primarily focused on mononuclear transition metal complexes in developing homogeneous catalysis. Our group is interested in the development of carbon-heteroatom bond-forming reactions, with a particular focus on identifying reactions that can be applied to the synthesis of complex molecules. In this context, we have hypothesized that bimetallic redox chemistry, in which two metals participate synergistically, may lower the activation barriers to redox transformations relevant to catalysis. In this Account, we discuss redox chemistry of binuclear Pd complexes and examine the role of binuclear intermediates in Pd-catalyzed oxidation reactions. Stoichiometric organometallic studies of the oxidation of binuclear Pd(II) complexes to binuclear Pd(III) complexes and subsequent C-X reductive elimination from the resulting binuclear Pd(III) complexes have confirmed the viability of C-X bond-forming reactions mediated by binuclear Pd(III) complexes. Metal-metal bond formation, which proceeds concurrently with oxidation of binuclear Pd(II) complexes, can lower the activation barrier for oxidation. We also discuss experimental and theoretical work that suggests that C-X reductive elimination is also facilitated by redox cooperation of both metals during reductive elimination. The effect of ligand modification on the structure and reactivity of binuclear Pd(III) complexes will be presented in light of the impact that ligand structure can exert on the structure and reactivity of binuclear Pd(III) complexes. Historically, oxidation reactions similar to those discussed here have been proposed to proceed via mononuclear Pd(IV) intermediates, and the hypothesis of mononuclear Pd

  11. Analysis of Manufacturing Bimetallic Tubes by the Cold Drawing Process

    Directory of Open Access Journals (Sweden)

    Halaczek D.

    2016-03-01

    Full Text Available Drawing processes apply to obtain the bimetallic tubes from the different metals and alloys, combined in the solid state, which significantly affects the specificity of this process. The manufacturing of bimetallic tubes by drawing process depends on many factors which include: preparation of the surface of materials joined in the solid state, the geometric parameters of the working tool, technological parameters of the drawing process (drawing speed, type of lubricant, the use of back pull etc.. Generally, the cold drawing process of producing the bimetallic tubes refers to metals which have high ductility (copper, aluminum, etc.. The tube sinking (tube drawing without a mandrel of bimetallic tubes together with joining them at the interface of the two metal in the solid-state is applied for tubes of the diameter range between 6 to 20 mm and based on of the reducing the diameter of the tube. However, a slight increase of wall thickness ca. 0.05 ÷ 0.10 mm can appear, which is not dangerous phenomenon in case of producing the bimetallic tubes by joining in the solid-state. The aim of the research was to investigate the technology of tubes drawing process from non-ferrous metal, drawing process of bimetallic tubes and the production of bimetallic tubes in layers composition: cooper Cu-ETP - brass CuZn37 and CuZn37 brass - copper Cu-ETP in the tube sinking process. The research program included: production of bimetallic tubes with a different composition (Cu- ETP-CuZn37 and CuZn37-Cu-ETP and a different percentage of the cross-section components; analysis of changes of tube wall thickness and the layer composition of the bimetallic tube, based on measurements on the workshop microscope; analysis of the material flow in the process of the bimetallic tubes production based on the measurements results of a profilograph CP-200.

  12. Corrosion protection

    Science.gov (United States)

    Brown, Donald W.; Wagh, Arun S.

    2003-05-27

    There has been invented a chemically bonded phosphate corrosion protection material and process for application of the corrosion protection material for corrosion prevention. A slurry of iron oxide and phosphoric acid is used to contact a warm surface of iron, steel or other metal to be treated. In the presence of ferrous ions from the iron, steel or other metal, the slurry reacts to form iron phosphates which form grains chemically bonded onto the surface of the steel.

  13. BIMETALLIC LITHIUM BOROHYDRIDES TOWARD REVERSIBLE HYDROGEN STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    Au, M.

    2010-10-21

    Borohydrides such as LiBH{sub 4} have been studied as candidates for hydrogen storage because of their high hydrogen contents (18.4 wt% for LiBH{sub 4}). Limited success has been made in reducing the dehydrogenation temperature by adding reactants such as metals, metal oxides and metal halides. However, full rehydrogenation has not been realized because of multi-step decomposition processes and the stable intermediate species produced. It is suggested that adding second cation in LiBH{sub 4} may reduce the binding energy of B-H. The second cation may also provide the pathway for full rehydrogenation. In this work, several bimetallic borohydrides were synthesized using wet chemistry, high pressure reactive ball milling and sintering processes. The investigation found that the thermodynamic stability was reduced, but the full rehydrogenation is still a challenge. Although our experiments show the partial reversibility of the bimetallic borohydrides, it was not sustainable during dehydriding-rehydriding cycles because of the accumulation of hydrogen inert species.

  14. Corrosion Engineering.

    Science.gov (United States)

    White, Charles V.

    A description is provided for a Corrosion and Corrosion Control course offered in the Continuing Engineering Education Program at the General Motors Institute (GMI). GMI is a small cooperative engineering school of approximately 2,000 students who alternate between six-week periods of academic study and six weeks of related work experience in…

  15. Corrosion sensor

    Science.gov (United States)

    Glass, Robert S.; Clarke, Jr., Willis L.; Ciarlo, Dino R.

    1994-01-01

    A corrosion sensor array incorporating individual elements for measuring various elements and ions, such as chloride, sulfide, copper, hydrogen (pH), etc. and elements for evaluating the instantaneous corrosion properties of structural materials. The exact combination and number of elements measured or monitored would depend upon the environmental conditions and materials used which are subject to corrosive effects. Such a corrosion monitoring system embedded in or mounted on a structure exposed to the environment would serve as an early warning system for the onset of severe corrosion problems for the structure, thus providing a safety factor as well as economic factors. The sensor array is accessed to an electronics/computational system, which provides a means for data collection and analysis.

  16. Modeling the melting temperature of nanoscaled bimetallic alloys.

    Science.gov (United States)

    Li, Ming; Zhu, Tian-Shu

    2016-06-22

    The effect of size, composition and dimension on the melting temperature of nanoscaled bimetallic alloys was investigated by considering the interatomic interaction. The established thermodynamics model without any arbitrarily adjustable parameters can be used to predict the melting temperature of nanoscaled bimetallic alloys. It is found that, the melting temperature and interatomic interaction of nanoscaled bimetallic alloys decrease with the decrease in size and the increasing composition of the lower surface energy metal. Moreover, for the nanoscaled bimetallic alloys with the same size and composition, the dependence of the melting temperature on the dimension can be sequenced as follows: nanoparticles > nanowires > thin films. The accuracy of the developed model is verified by the recent experimental and computer simulation results.

  17. A photoactive bimetallic framework for direct aminoformylation of nitroarenes

    Data.gov (United States)

    U.S. Environmental Protection Agency — A bimetallic catalyst, AgPd@g-C3N4, synthesized by reducing silver and palladium salts over graphitic carbon nitride (g-C3N4), enables the concerted reductive...

  18. Methanol Oxidation on Model Elemental and Bimetallic Transition Metal Surfaces

    DEFF Research Database (Denmark)

    Tritsaris, G. A.; Rossmeisl, J.

    2012-01-01

    Direct methanol fuel cells are a key enabling technology for clean energy conversion. Using density functional theory calculations, we study the methanol oxidation reaction on model electrodes. We discuss trends in reactivity for a set of monometallic and bimetallic transition metal surfaces, flat...... sites on the surface and to screen for novel bimetallic surfaces of enhanced activity. We suggest platinum copper surfaces as promising anode catalysts for direct methanol fuel cells....

  19. Equipment stainless steel entire versus steels bimetallics clad or overlay; Utilizacao de equipamentos de processo construidos em aco inoxidavel integral versus acos bimetalicos cladeado ou 'overlay'

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Itamar da Silva; Lima, Jadival Carneiro de; Leal, Murilo Fonseca; Cardoso, Amauri dos Santos; Jorjan, Roberto [PETROBRAS S.A., Sao Francisco do Conde, BA (Brazil). Refinaria Landulfo Alves Mataripen (RLAM)

    2008-07-01

    This study does not recommend the use of a pressure vessel made of integral stainless steel, due to the failure mechanisms under stress corrosion assisted by chlorides or polythionic acid. Are presented case studies of literature and analysis of reports of proceedings of RLAM reactors, showing that the materials produced by bimetallic clad overlay or are more appropriate, in terms of integrity, for use in equipment that the internal environment requires austenitic stainless steel specification.

  20. Ammonia Decomposition over Bimetallic Nitrides Supported on γ-Al2O3

    Institute of Scientific and Technical Information of China (English)

    Chun Shan LU; Xiao Nian LI; Yi Feng ZHU; Hua Zhang LIU; Chun Hui ZHOU

    2004-01-01

    A series of monometallic nitrides and bimetallic nitrides were prepared by temperature-programmed reaction with NH3. The effects of Co, Ni and Fe additives and the synergic action between Fe, Co, Ni and Mo on the ammonia decomposition activity were investigated. TPR-MS, XRD were also carried out to obtain better insight into the structure of the bimetallic nitride. The results of ammonia decomposition activity show that bimetallic nitrides are more active than monometallic nitrides or bimetallic oxides.

  1. Nanocrystal and surface alloy properties of bimetallic Gold-Platinum nanoparticles

    Directory of Open Access Journals (Sweden)

    Mott Derrick

    2006-01-01

    Full Text Available AbstractWe report on the correlation between the nanocrystal and surface alloy properties with the bimetallic composition of gold-platinum(AuPt nanoparticles. The fundamental understanding of whether the AuPt nanocrystal core is alloyed or phase-segregated and how the surface binding properties are correlated with the nanoscale bimetallic properties is important not only for the exploitation of catalytic activity of the nanoscale bimetallic catalysts, but also to the general exploration of the surface or interfacial reactivities of bimetallic or multimetallic nanoparticles. The AuPt nanoparticles are shown to exhibit not only single-phase alloy character in the nanocrystal, but also bimetallic alloy property on the surface. The nanocrystal and surface alloy properties are directly correlated with the bimetallic composition. The FTIR probing of CO adsorption on the bimetallic nanoparticles supported on silica reveals that the surface binding sites are dependent on the bimetallic composition. The analysis of this dependence further led to the conclusion that the relative Au-atop and Pt-atop sites for the linear CO adsorption on the nanoparticle surface are not only correlated with the bimetallic composition, but also with the electronic effect as a result of the d-band shift of Pt in the bimetallic nanocrystals, which is the first demonstration of the nanoscale core-surface property correlation for the bimetallic nanoparticles over a wide range of bimetallic composition.

  2. Corrosion in airframes

    OpenAIRE

    PETROVIC ZORAN C.

    2016-01-01

    The introductory chapter provides a brief reference to the issue of corrosion and corrosion damage to aircraft structures. Depending on the nature and dimensions of this non uniformity, three different categories of corrosion are defined: uniform, selective and localized corrosion. The following chapters present the forms of corrosion that can occur in three defined categories of corrosion. Conditions that cause certain types of corrosion in various corrosive environments are discussed. Examp...

  3. CORROSION IN AIRFRAMES

    OpenAIRE

    PETROVIC ZORAN C.

    2016-01-01

    The introductory chapter provides a brief reference to the issue of corrosion and corrosion damage to aircraft structures. Depending on the nature and dimensions of this non uniformity, three different categories of corrosion are defined: uniform, selective and localized corrosion. The following chapters present the forms of corrosion that can occur in three defined categories of corrosion. Conditions that cause certain types of corrosion in various corrosive environments are discussed. Examp...

  4. Bimetallic layered castings alloy steel – carbon cast steel

    Directory of Open Access Journals (Sweden)

    T. Wróbel

    2011-01-01

    Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast processso-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. ferritic-pearlitic carbon cast steel, whereas working part (layer is plate of austenitic alloy steel sort X10CrNi 18-8. The ratio of thickness between bearing and working part is 8:1. The quality of the bimetallic layered castings was evaluated on the basis of ultrasonic NDT (non-destructive testing, structure and macro- and microhardness researches.

  5. Examples of material solutions in bimetallic layered castings

    Directory of Open Access Journals (Sweden)

    S. Tenerowicz

    2011-07-01

    Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. pearlitic grey cast iron, whereas working part (layer is depending on accepted variant plates of alloy steels sort X6Cr13, X12Cr13, X10CrNi18-8 and X2CrNiMoN22-5-3. The ratio of thickness between bearing and working part is 8:1. The verification of the bimetallic layered castings was evaluated on the basis of ultrasonic NDT (non-destructive testing, structure and macro- and microhardness researches.

  6. Structure-Property Relationship in Metal Carbides and Bimetallic Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jingguan [University of Delaware

    2014-03-04

    The primary objective of our DOE/BES sponsored research is to use carbide and bimetallic catalysts as model systems to demonstrate the feasibility of tuning the catalytic activity, selectivity and stability. Our efforts involve three parallel approaches, with the aim at studying single crystal model surfaces and bridging the “materials gap” and “pressure gap” between fundamental surface science studies and real world catalysis. The utilization of the three parallel approaches has led to the discovery of many intriguing catalytic properties of carbide and bimetallic surfaces and catalysts. During the past funding period we have utilized these combined research approaches to explore the possibility of predicting and verifying bimetallic and carbide combinations with enhanced catalytic activity, selectivity and stability.

  7. Bimetallic Ni/Pd finite systems: Structure and thermodynamics of bimetallic Ni/Pd nanostructures in two and three dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Nieves-Torres, Stephanie [Department of Chemistry, University of Puerto Rico at Mayagueez, Mayagueez 00681 (Puerto Rico); Mo, Elizabeth [Department of Chemistry, Lehman College-CUNY, Bronx, NY 10468 (United States); Lopez, Gustavo E., E-mail: glopez@uprm.edu [Department of Chemistry, University of Puerto Rico at Mayagueez, Mayagueez 00681 (Puerto Rico); Department of Chemistry, Lehman College-CUNY, Bronx, NY 10468 (United States)

    2011-09-15

    Highlights: {yields} Structure and thermodynamic of Ni/Pd bimetallic clusters as a function of composition. {yields} Melting and low temperature order-disorder transitions in Ni/Pd bimetallic clusters. {yields} Implementation of efficient classical Monte Carlo techniques. - Abstract: By implementing replica-exchange Monte Carlo simulations within the multihistogram reweighting techniques, the structural and thermodynamic changes in bimetallic nickel-palladium nanostructured systems were studied as a function of composition. Specifically, two- and three-dimensional clusters composed of seven and thirteen atoms, respectively, were described using the embedded atom potential. The lowest energy equilibrium structures were determined, and associated to the degree of mixing in the material. In all cases, melting and order-disorder transitions were revealed by calculating the average constant volume heat capacity as a function of temperature. The change in Helmholtz free energy for the order-disorder transition was determined as a function of composition for each system.

  8. Underground pipeline corrosion

    CERN Document Server

    Orazem, Mark

    2014-01-01

    Underground pipelines transporting liquid petroleum products and natural gas are critical components of civil infrastructure, making corrosion prevention an essential part of asset-protection strategy. Underground Pipeline Corrosion provides a basic understanding of the problems associated with corrosion detection and mitigation, and of the state of the art in corrosion prevention. The topics covered in part one include: basic principles for corrosion in underground pipelines, AC-induced corrosion of underground pipelines, significance of corrosion in onshore oil and gas pipelines, n

  9. Bimetallic Nanoparticles as Efficient Catalysts: Facile and Green Microwave Synthesis

    Directory of Open Access Journals (Sweden)

    Magda Blosi

    2016-07-01

    Full Text Available This work deals with the development of a green and versatile synthesis of stable mono- and bi-metallic colloids by means of microwave heating and exploiting ecofriendly reagents: water as the solvent, glucose as a mild and non-toxic reducer and polyvinylpirrolidone (PVP as the chelating agent. Particle size-control, total reaction yield and long-term stability of colloids were achieved with this method of preparation. All of the materials were tested as effective catalysts in the reduction of p-nitrophenol in the presence of NaBH4 as the probe reaction. A synergistic positive effect of the bimetallic phase was assessed for Au/Cu and Pd/Au alloy nanoparticles, the latter showing the highest catalytic performance. Moreover, monoand bi-metallic colloids were used to prepare TiO2- and CeO2-supported catalysts for the liquid phase oxidation of 5-hydroxymethylfufural (HMF to 2,5-furandicarboxylic acid (FDCA. The use of Au/Cu and Au/Pd bimetallic catalysts led to an increase in FDCA selectivity. Finally, preformed Pd/Cu nanoparticles were incorporated into the structure of MCM-41-silica. The resulting Pd/Cu MCM-41 catalysts were tested in the hydrodechlorination of CF3OCFClCF2Cl to CF3OCF=CF2. The effect of Cu on the hydrogenating properties of Pd was demonstrated.

  10. Bimetallic alloy electrocatalysts with multilayered platinum-skin surfaces

    Science.gov (United States)

    Stamenkovic, Vojislav R.; Wang, Chao; Markovic, Nenad M.

    2016-01-26

    Compositions and methods of preparing a bimetallic alloy having enhanced electrocatalytic properties are provided. The composition comprises a PtNi substrate having a surface layer, a near-surface layer, and an inner layer, where the surface layer comprises a nickel-depleted composition, such that the surface layer comprises a platinum skin having at least one atomic layer of platinum.

  11. Photoluminescence of hollow gold-silver bimetallic nanoparticles

    OpenAIRE

    Weon-Sik Chae; Hee-Ok Lee; Seung-Lim Oh

    2011-01-01

    Hollow gold nanoparticles including silver were prepared by the galvanic replacement reaction of silver nanoparticles by gold. The resulting hollow gold-silver bimetallic nanoparticles show notable blue-green emissions, which are studied using steady-state and time-resolved spectroscopy.

  12. Crystalline structure-dependent growth of bimetallic nanostructures.

    Science.gov (United States)

    Li, Qian; Jiang, Ruibin; Ming, Tian; Fang, Caihong; Wang, Jianfang

    2012-11-21

    Morphological control of multimetallic nanostructures is crucial for obtaining shape-dependent physical and chemical properties. Up to date, control of the shapes of multimetallic nanostructures has remained largely empirical. Multimetallic nanostructures have been produced mostly through seed-mediated growth. Understanding the role played by starting nanocrystal seeds can help in controlling the shape and in turn the plasmonic and catalytic properties of multimetallic nanostructures. In this work, we have studied the effect of the crystalline structure and shape of Au nanocrystal seeds on the morphology of the resultant bimetallic nanostructures. Single-crystalline Au nanorods, multiply twinned Au nanorods, and multiply twinned Au nanobipyramids were employed as the starting seeds. Both silver and palladium exhibit highly preferential growth on the side surfaces of the single-crystalline Au nanorods, giving rise to bimetallic cuboids, whereas they prefer to grow at the ends of the multiply twinned Au nanorods and nanobipyramids, giving rise to bimetallic nanorods. These results indicate that the morphology of the bimetallic nanostructures is highly dependent on the crystalline structure of the Au nanocrystal seeds. Our results will be useful for guiding the preparation of multimetallic nanostructures with desired shapes and therefore plasmonic properties for various plasmon-based applications.

  13. High pressure CO hydrogenation over bimetallic Pt-Co catalysts

    DEFF Research Database (Denmark)

    Christensen, Jakob Munkholt; Medford, Andrew James; Studt, Felix

    2014-01-01

    The potential of bimetallic Pt-Co catalysts for production of higher alcohols in high pressure CO hydrogenation has been assessed. Two catalysts (Pt3Co/SiO2 and PtCo/SiO2) were tested, and the existing literature on CO hydrogenation over Pt-Co catalysts was reviewed. It is found that the catalyst...

  14. Corrosion Testing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Corrosion Testing Facility is part of the Army Corrosion Office (ACO). It is a fully functional atmospheric exposure site, called the Corrosion Instrumented Test...

  15. Monodispersed bimetallic PdAg nanoparticles with twinned structures: Formation and enhancement for the methanol oxidation

    OpenAIRE

    Zhen Yin; Yining Zhang; Kai Chen; Jing Li; Wenjing Li; Pei Tang; Huabo Zhao; Qingjun Zhu; Xinhe Bao; Ding Ma

    2014-01-01

    Monodispersed bimetallic PdAg nanoparticles can be fabricated through the emulsion-assisted ethylene glycol (EG) ternary system. Different compositions of bimetallic PdAg nanoparticles, Pd80Ag20, Pd65Ag35 and Pd46Ag54 can be obtained via adjusting the reaction parameters. For the formation process of the bimetallic PdAg nanoparticles, there have two-stage growth processes: firstly, nucleation and growth of the primary nanoclusters; secondly, formation of the secondary nanoparticles with the s...

  16. Structural Characterization of Bimetallic Nanocrystal Electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, David A [ORNL

    2016-01-01

    Late transition metal nanocrystals find applications in heterogeneous catalysis such as plasmon-enhanced catalysis and as electrode materials for fuel cells, a zero-emission and sustainable energy technology. Their commercial viability for automotive transportation has steadily increased in recent years, almost exclusively due to the discovery of more efficient bimetallic nanocatalysts for the oxygen reduction reaction (ORR) at the cathode. Despite improvements to catalyst design, achieving high activity while maintaining durability is essential to further enhance their performance for this and other important applications in catalysis. Electronic effects arising from the generation of metal-metal interfaces, from plasmonic metals, and from lattice distortions, can vastly improve sorption properties at catalytic surfaces, while increasing durability.[1] Multimetallic lattice-strained nanoparticles are thus an interesting opportunity for fundamental research.[2,3] A colloidal synthesis approach is demonstrated to produce AuPd alloy and Pd@Au core-shell nanoicosahedra as catalysts for electro-oxidations. The nanoparticles are characterized using aberration-corrected scanning transmission electron microscopy (ac-STEM) and large solid angle energy dispersive X-ray spectroscopy (EDS) on an FEI Talos 4-detector STEM/EDS system. Figure 1 shows bright-field (BF) and high-angle annular dark-field (HAADF) ac-STEM images of the alloy and core-shell nanoicosahedra together with EDS line-scans and elemental maps. These structures are unique in that the presence of twin boundaries, alloying, and core-shell morphology could create highly strained surfaces and interfaces. The shell thickness of the core-shell structures observed in HAADF-STEM images is tuned by adjusting the ratio between metal precursors (Figure 2a-f) to produce shells ranging from a few to several monolayers. Specific activity was measured in ethanol electro-oxidation to examine the effect of shell thickness on

  17. Methods to synthesize NiPt bimetallic nanoparticles by a reversed-phase microemulsion, deposition of NiPt bimetallic nanoparticles on a support, and application of the supported catalyst for CO.sub.2 reforming of methane

    KAUST Repository

    Biausque, Gregory

    2015-04-28

    Methods to synthesize NiPt bimetallic nanoparticles by a reversed-phase microemulsion, deposition of NiPt bimetallic nanoparticles on a support, and application of the supported catalyst for CO.sub.2 reforming of methane

  18. Nanosegregated bimetallic oxide anode catalyst for proton exchange membrane electrolyzer

    Science.gov (United States)

    Danilovic, Nemanja; Kang, Yijin; Markovic, Nenad; Stamenkovic, Vojislav; Myers, Deborah J.; Subbaraman, Ram

    2016-08-23

    A surface segregated bimetallic composition of the formula Ru.sub.1-xIr.sub.x wherein 0.1.ltoreq.x.ltoreq.0.75, wherein a surface of the material has an Ir concentration that is greater than an Ir concentration of the material as a whole is provided. The surface segregated material may be produced by a method including heating a bimetallic composition of the formula Ru.sub.1-xIr.sub.x, wherein 0.1.ltoreq.x.ltoreq.0.75, at a first temperature in a reducing environment, and heating the composition at a second temperature in an oxidizing environment. The surface segregated material may be utilized in electrochemical devices.

  19. Tuning structural motifs and alloying of bulk immiscible Mo-Cu bimetallic nanoparticles by gas-phase synthesis

    NARCIS (Netherlands)

    Krishnan, Gopi; Verheijen, Marcel A.; ten Brink, Gert; Palasantzas, George; Kooi, Bart J.

    2013-01-01

    Nowadays bimetallic nanoparticles (NPs) have emerged as key materials for important modern applications in nanoplasmonics, catalysis, biodiagnostics, and nanomagnetics. Consequently the control of bimetallic structural motifs with specific shapes provides increasing functionality and selectivity for

  20. Bimetallic Thermal Resists for Photomask, Micromachining and Microfabrication

    OpenAIRE

    Tu, Richard Yuqiang

    2004-01-01

    Photoresists and photomasks are two of the most critical materials in microfabrication and micromachining industries. As the shift towards shorter wavelength exposure continues, conventional organic photoresists and chromelquartz photomasks start to encounter problems. This thesis investigates and presents an alternative to organic photoresists and chromium photomasks which overcomes their intrinsic problems. A bimetallic thin film, such as BilIn and SnIIn, creates an inorganic thermal resist...

  1. Biosupported Bimetallic Pd Au Nanocatalysts for Dechlorination of Environmental Contaminants

    Energy Technology Data Exchange (ETDEWEB)

    De Corte, S.; Fitts, J.; Hennebel, T.; Sabbe, T.; Bliznuk, V.; Verschuere, S.; van der Lelie, D.; Verstraete, W.; Boon, N.

    2011-08-30

    Biologically produced monometallic palladium nanoparticles (bio-Pd) have been shown to catalyze the dehalogenation of environmental contaminants, but fail to efficiently catalyze the degradation of other important recalcitrant halogenated compounds. This study represents the first report of biologically produced bimetallic Pd/Au nanoparticle catalysts. The obtained catalysts were tested for the dechlorination of diclofenac and trichloroethylene. When aqueous bivalent Pd(II) and trivalent Au(III) ions were both added to concentrations of 50 mg L{sup -1} and reduced simultaneously by Shewanella oneidensis in the presence of H{sub 2}, the resulting cell-associated bimetallic nanoparticles (bio-Pd/Au) were able to dehalogenate 78% of the initially added diclofenac after 24 h; in comparison, no dehalogenation was observed using monometallic bio-Pd or bio-Au. Other catalyst-synthesis strategies did not show improved dehalogenation of TCE and diclofenac compared with bio-Pd. Synchrotron-based X-ray diffraction, (scanning) transmission electron microscopy and energy dispersive X-ray spectroscopy indicated that the simultaneous reduction of Pd and Au supported on cells of S. oneidensis resulted in the formation of a unique bimetallic crystalline structure. This study demonstrates that the catalytic activity and functionality of possibly environmentally more benign biosupported Pd-catalysts can be improved by coprecipitation with Au.

  2. Antibacterial activity of graphene supported FeAg bimetallic nanocomposites.

    Science.gov (United States)

    Ahmad, Ayyaz; Qureshi, Abdul Sattar; Li, Li; Bao, Jie; Jia, Xin; Xu, Yisheng; Guo, Xuhong

    2016-07-01

    We report the simple one pot synthesis of iron-silver (FeAg) bimetallic nanoparticles with different compositions on graphene support. The nanoparticles are well dispersed on the graphene sheet as revealed by the TEM, XRD, and Raman spectra. The antibacterial activity of graphene-FeAg nanocomposite (NC) towards Bacillus subtilis, Escherichia coli, and Staphylococcus aureus was investigated by colony counting method. Graphene-FeAg NC demonstrates excellent antibacterial activity as compared to FeAg bimetallic without graphene. To understand the antibacterial mechanism of the NC, oxidative stress caused by reactive oxygen species (ROS) and the glutathione (GSH) oxidation were investigated in the system. It has been observed that ROS production and GSH oxidation are concentration dependent while the increase in silver content up to 50% generally enhances the ROS production while ROS decreases on further increase in silver content. Graphene loaded FeAg NC demonstrates higher GSH oxidation capacity than bare FeAg bimetallic nanocomposite. The mechanism study suggests that the antibacterial activity is probably due to membrane and oxidative stress produced by the nanocomposites. The possible antibacterial pathway mainly includes the non-ROS oxidative stress (GSH oxidation) while ROS play minor role.

  3. PREPARATION OF NOVEL METALLIC AND BIMETALLIC CROSS-LINKED POLY (VINYL ALCOHOL) NANOCOMPOSITES UNDER MICROWAVE IRRADIATION

    Science.gov (United States)

    A facile method utilizing microwave irradiation is described that accomplishes the cross-linking reaction of PVA with metallic and bimetallic systems. Nanocomposites of PVA-cross-linked metallic systems such as Pt, Cu, and In and bimetallic systems such as Pt-In, Ag-Pt, Pt-Fe, Cu...

  4. NOVEL METALLIC AND BIMETALLIC CROSS-LINKED POLY (VINYL ALCOHOL) NANOCOMPOSITES PREPARED UNDER MICROWAVE IRRADIATION

    Science.gov (United States)

    A facile microwave irradiation approach that results in a cross-linking reaction of poly (vinyl alcohol) (PVA) with metallic and bimetallic systems is described. Nanocomposites of PVA cross-linked metallic systems such as Pt, Cu, and In and bimetallic systems such as Pt-In, Ag-P...

  5. CO methanation over supported bimetallic Ni-Fe catalysts: From computational studies towards catalyst optimization

    DEFF Research Database (Denmark)

    Kustov, Arkadii; Frey, Anne Mette; Larsen, Kasper Emil

    2007-01-01

    DFT calculations combined with a computational screening method have previously shown that bimetallic Ni-Fe alloys should be more active than the traditional Ni-based catalyst for CO methanation. That was confirmed experimentally for a number of bimetallic Ni-Fe catalysts supported on MgAl2O4. He...

  6. An in-depth understanding of the bimetallic effects and coked carbon species on an active bimetallic Ni(Co)/Al2O3 dry reforming catalyst.

    Science.gov (United States)

    Liao, Xin; Gerdts, Rihards; Parker, Stewart F; Chi, Lina; Zhao, Yongxiang; Hill, Martyn; Guo, Junqiu; Jones, Martin O; Jiang, Zheng

    2016-06-29

    Ni/Al2O3, Co/Al2O3 and bimetallic Ni(Co)/Al2O3 catalysts were prepared using an impregnation method and employed in CO2 dry reforming of methane under coking-favored conditions. The spent catalysts were carefully characterized using typical characterization technologies and inelastic neutron scattering spectroscopy. The bimetallic catalyst exhibited a superior activity and anti-coking performance compared to Ni/Al2O3, while the most resistant to coking behavior was Co/Al2O3. The enhanced activity of the Ni(Co)/Al2O3 bimetallic catalyst is attributed to the reduced particle size of metallic species and resistance to forming stable filamentous carbon. The overall carbon deposition on the spent bimetallic catalyst is comparable to that of the spent Ni/Al2O3 catalyst, whereas the carbon deposited on the bimetallic catalyst is mainly less-stable carbonaceous species as confirmed by SEM, TPO, Raman and INS characterization. This study provides an in depth understanding of alloy effects in catalysts, the chemical nature of coked carbon on spent Ni-based catalysts and, hopefully, inspires the creative design of a new bimetallic catalyst for dry reforming reactions.

  7. Atomic Structure of Au−Pd Bimetallic Alloyed Nanoparticles

    KAUST Repository

    Ding, Yong

    2010-09-08

    Using a two-step seed-mediated growth method, we synthesized bimetallic nanoparticles (NPs) having a gold octahedron core and a palladium epitaxial shell with controlled Pd-shell thickness. The mismatch-release mechanism between the Au core and Pd shell of the NPs was systematically investigated by high-resolution transmission electron microscopy. In the NPs coated with a single atomic layer of Pd, the strain between the surface Pd layer and the Au core is released by Shockley partial dislocations (SPDs) accompanied by the formation of stacking faults. For NPs coated with more Pd (>2 nm), the stacking faults still exist, but no SPDs are found. This may be due to the diffusion of Au atoms into the Pd shell layers to eliminate the SPDs. At the same time, a long-range ordered L11 AuPd alloy phase has been identified in the interface area, supporting the assumption of the diffusion of Au into Pd to release the interface mismatch. With increasing numbers of Pd shell layers, the shape of the Au-Pd NP changes, step by step, from truncated-octahedral to cubic. After the bimetallic NPs were annealed at 523 K for 10 min, the SPDs at the surface of the NPs coated with a single atomic layer of Pd disappeared due to diffusion of the Au atoms into the surface layer, while the stacking faults and the L11 Au-Pd alloyed structure remained. When the annealing temperature was increased to 800 K, electron diffraction patterns and diffraction contrast images revealed that the NPs became a uniform Au-Pd alloy, and most of the stacking faults disappeared as a result of the annealing. Even so, some clues still support the existence of the L11 phase, which suggests that the L11 phase is a stable, long-range ordered structure in Au-Pd bimetallic NPs. © 2010 American Chemical Society.

  8. Exploration of Nanotube Structure Selectivity Using Bimetallic Catalysts

    Science.gov (United States)

    Pfefferle, Lisa

    2007-10-01

    Achieving selectivity for nanotube chirality is one of the holy grails for single-walled carbon nanotube research. One approach we are following is based on the ability to engineer the size and state of the initiating metal particle to constrain the type of cap formed. The chirality/structure of a nanotube is controlled by carbon cap formation on the metal particle during the nucleation step. It has been proposed that varying the carbon-metal catalyst binding energy could help lead to structure selectivity. One reason theoretically proposed for the favoring of armchair nanotubes, for example, is the proximity of low energy binding locations for two carbon atoms. Thus blocking sites or perturbing the binding energy on adjacent sites could in theory affect the structure of the carbon cap formed in the nucleation step. Our goal is to demonstrate structure selectivity in the growth of single wall carbon nanotubes (SWNT) using a bimetallic catalyst. The catalyst used was a bimetallic CoCr-MCM 41 and the effect of different molecular ratios between the two metals on the SWNT diameter distribution was studied. We have found that by adding Cr to the Co-MCM 41 monometallic catalyst the diameter distribution shifted in a systematic manner correlated to the development of a bimetallic phase as characterized by X-Ray absorption spectroscopy (XAS). We have also found that the shift is accompanied by suppression of metallic SWNT, particularly those with diameter over 0.9 nm. We are also currently exploring the possibility of a further narrowing of the distribution by lowering the reaction temperatures.

  9. Modelling of Corrosion Cracks

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Modelling of corrosion cracking of reinforced concrete structures is complicated as a great number of uncertain factors are involved. To get a reliable modelling a physical and mechanical understanding of the process behind corrosion in needed.......Modelling of corrosion cracking of reinforced concrete structures is complicated as a great number of uncertain factors are involved. To get a reliable modelling a physical and mechanical understanding of the process behind corrosion in needed....

  10. Enhanced plasmonic behavior of bimetallic (Ag-Au multilayered spheres

    Directory of Open Access Journals (Sweden)

    Pal Umapada

    2011-01-01

    Full Text Available Abstract In this article we study the plasmonic behavior of some stable, highly biocompatible bimetallic metal-dielectric-metal (MDM and double concentric nanoshell (DCN structures. By simply switching the material of the inner structure from Au to Ag, the intensity of their surface plasmon resonance could be increased in the optical transparency region of the human tissues up to 20 and 60 percent for the MDM and DCN, respectively, while the biocompatibility is retained. The obtained results indicate that these novel structures could be highly suitable for surface enhanced Raman scattering and photothermal cancer therapy.

  11. Controllable Catalysis with Nanoparticles: Bimetallic Alloy Systems and Surface Adsorbates

    KAUST Repository

    Chen, Tianyou

    2016-05-16

    Transition metal nanoparticles are privileged materials in catalysis due to their high specific surface areas and abundance of active catalytic sites. While many of these catalysts are quite useful, we are only beginning to understand the underlying catalytic mechanisms. Opening the “black box” of nanoparticle catalysis is essential to achieve the ultimate goal of catalysis by design. In this Perspective we highlight recent work addressing the topic of controlled catalysis with bimetallic alloy and “designer” adsorbate-stabilized metal nanoparticles.

  12. Management of Reinforcement Corrosion

    DEFF Research Database (Denmark)

    Küter, André; Geiker, Mette Rica; Møller, Per

    Reinforcement corrosion is the most important cause for deterioration of reinforced concrete structures, both with regard to costs and consequences. Thermodynamically consistent descriptions of corrosion mechanisms are expected to allow the development of innovative concepts for the management...... of reinforcement corrosion....

  13. Corrosion inhibitors; Los inhibidores de corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Godinez, L. A.; Meas, Y.; Ortega-Borges, R.; Corona, A.

    2003-07-01

    In this paper, we briefly describe the characteristics, cost and electrochemical nature of the corrosion phenomena as well as some of the technologies that are currently employed to minimize its effect. The main subject of the paper however, deals with the description, classification and mechanism of protection of the so-called corrosion inhibitors. Examples of the use of these substances in different aggressive environments are also presented as means to show that these compounds, or their combination, can in fact be used as excellent and relatively cheap technologies to control the corrosion of some metals. In the last part of the paper, the most commonly used techniques to evaluate the efficiency and performance of corrosion inhibitors are presented as well as some criteria to make a careful and proper selection of a corrosion inhibitor technology in a given situation. (Author) 151 refs.

  14. Progress, Challenge, and Perspective of Bimetallic TiO2-Based Photocatalysts

    Directory of Open Access Journals (Sweden)

    Anna Zielińska-Jurek

    2014-01-01

    Full Text Available Bimetallic TiO2-based photocatalysts have attracted considerable attention in recent years as a class of highly active catalysts and photocatalysts under both UV and Vis light irradiation. Bimetallic noble metal structures deposited on TiO2 possess the ability to absorb visible light, in a wide wavelength range (broad LSPR peak, and therefore reveal the highest level of activity as a result of utilization of a large amount of incident photons. On the other hand they can enhance the rate of trapping photoexcited electrons and inhibit the recombination process due to the capability of the storage of photoexcited electrons. Based on literature two groups of bimetallic photocatalysts were distinguished. The first group includes bimetallic TiO2 photocatalysts (BMOX, highly active under UV and Vis light irradiation in a variety of oxidation reactions, and the second group presents bimetallic photocatalysts (BMRED exceptionally active in hydrogenation reactions. This review summarizes recent advances in the preparation and environmental application of bimetallic TiO2-based photocatalysts. Moreover, the effects of various parameters such as particle shape, size, amount of metals, and calcination on the photocatalytic activity of bimetallic TiO2-based photocatalysts are also discussed.

  15. CO2 activation on bimetallic CuNi nanoparticles☆

    Institute of Scientific and Technical Information of China (English)

    Natalie Austin; Brandon Butina; Giannis Mpourmpakis⁎

    2016-01-01

    Density functional theory calculations have been performed to investigate the structural, electronic, and CO2 adsorption properties of 55-atom bimetallic CuNi nanoparticles (NPs) in core-shell and decorated architectures, as well as of their monometallic counterparts. Our results revealed that with respect to the monometallic Cu55 and Ni55 parents, the formation of decorated Cu12Ni43 and core-shell Cu42Ni13 are energetically favorable. We found that CO2 chemisorbs on monometallic Ni55, core-shell Cu13Ni42, and decorated Cu12Ni43 and Cu43Ni12, whereas, it physisorbs on monometallic Cu55 and core-shell Cu42Ni13. The presence of surface Ni on the NPs is key in strongly adsorbing and activating the CO2 molecule (linear to bent transition and elongation of C˭O bonds). This activation occurs through a charge transfer from the NPs to the CO2 molecule, where the local metal d-orbital density localization on surface Ni plays a pivotal role. This work identifies insightful structure-property relationships for CO2 activation and highlights the importance of keeping a balance between NP stability and CO2 adsorption behavior in designing catalytic bimetallic NPs that activate CO2.

  16. Bimetallic Catalysts Containing Gold and Palladium for Environmentally Important Reactions

    Directory of Open Access Journals (Sweden)

    Ahmad Alshammari

    2016-07-01

    Full Text Available Supported bimetallic nanoparticles (SBN are extensively used as efficient redox catalysts. This kind of catalysis particularly using SBN has attracted immense research interest compared to their parent metals due to their unique physico-chemical properties. The primary objective of this contribution is to provide comprehensive overview about SBN and their application as promising catalysts. The present review contains four sections in total. Section 1 starts with a general introduction, recent progress, and brief summary of the application of SBN as promising catalysts for different applications. Section 2 reviews the preparation and characterization methods of SBN for a wide range of catalytic reactions. Section 3 concentrates on our own results related to the application of SBN in heterogeneous catalysis. In this section, the oxidation of cyclohexane to adipic acid (an eco-friendly and novel approach will be discussed. In addition, the application of bimetallic Pd catalysts for vapor phase toluene acetoxylation in a fixed bed reactor will also be highlighted. Acetoxylation of toluene to benzyl acetate is another green route to synthesize benzyl acetate in one step. Finally, Section 4 describes the summary of the main points and also presents an outlook on the application of SBN as promising catalysts for the production of valuable products.

  17. Optical properties and sensing applications of stellated and bimetallic nanoparticles

    Science.gov (United States)

    Smith, Alison F.

    This dissertation focuses on developing guidelines to aid in the design of new bimetallic platforms for sensing applications. Stellated metal nanostructures are a class of plasmonic colloids in which large electric field enhancements can occur at sharp features, making them excellent candidates for surface enhanced Raman spectroscopy (SERS) and surface enhanced infrared spectroscopy (SE-IRS) platforms. Shape-dependent rules for convex polyhedra such as cubes or octahedra exist, which describe far-field scattering and near-field enhancements. However, such rules are lacking for their concave (stellated) counterparts. This dissertation presents the optical response of stellated Au nanocrystals with Oh, D4h, D3h, C2v, and T d symmetry, which were modeled to systematically investigate the role of symmetry, branching, and particle orientation with respect to excitation source using finite difference time domain (FDTD) calculations. Expanding on stellated nanostructures, bimetallic compositions introduce an interplay between overall architecture and composition to provide tunable optical properties and the potential of new functionality. However, decoupling the complex compositional and structural contributions to the localized surface plasmon resonance (LSPR) remains a challenge, especially when the monometallic counterparts are not synthetically accessible for comparison and the theoretical tools for capturing gradient compositions are lacking. This dissertation explores a stellated Au-Pd nanocrystal model system with Oh symmetry to decouple structural and complex compositional effects on LSPR. (Abstract shortened by ProQuest.).

  18. Analysis of Al-Cu Bimetallic Bars Properties After Explosive Welding and Rolling in Modified Passes

    Directory of Open Access Journals (Sweden)

    Mróz S.

    2015-04-01

    Full Text Available The paper presents the results of the experimental tests of Al-Cu bimetallic bars rolling process in multi-radial modified passes. The bimetallic bars consist of aluminium core, grade 1050A and copper outer layer, grade M1E. The stocks were round bars with diameter 22 mm with a copper layer share of 15 and 30%. As a result of rolling in four passes, bars of a diameter of about 16.0 mm were obtained. A bimetallic stock was manufactured using an explosive welding method. The use of the designed arrangement of multi-radial modified stretching passes resulted in obtaining Al-Cu bimetallic bars with the required lateral dimensions, an uniform distribution of the cladding layer over the bar perimeter and high quality of shear strength between individual layers.

  19. Bimetallic structure fabricated by laser interference lithography for tuning surface plasmon resonance.

    Science.gov (United States)

    Liu, C H; Hong, M H; Cheung, H W; Zhang, F; Huang, Z Q; Tan, L S; Hor, T S A

    2008-07-07

    Tuning of surface plasmon resonance by gold and silver bimetallic thin film and bimetallic dot array is investigated. Laser interference lithography is applied to fabricate the nanostructures. A bimetallic dot structure is obtained by a lift-off procedure after gold and silver thin film deposition by an electron beam evaporator. Surface plasmon behaviors of these films and nanostructures are studied using UV-Vis spectroscopy. It is observed that for gold thin film on quartz substrate, the optical spectral peak is blue shifted when a silver thin film is coated over it. Compared to the plasmon band in single metal gold dot array, the bimetallic nanodot array shows a similar blue shift in its spectral peak. These shifts are both attributed to the interaction between gold and silver atoms. Electromagnetic interaction between gold and silver nanostructures is discussed using a simplified spring model.

  20. Fabrication of bimetallic nanostructures via aerosol-assisted electroless silver deposition for catalytic CO conversion.

    Science.gov (United States)

    Byeon, Jeong Hoon; Kim, Jang-Woo

    2014-03-12

    Bimetallic nanostructures were fabricated via aerosol-assisted electroless silver deposition for catalytic CO conversion. An ambient spark discharge was employed to produce nanocatalysts, and the particles were directly deposited on a polytetrafluoroethylene substrate for initiating silver deposition to form Pd-Ag, Pt-Ag, Au-Ag bimetallic nanostructures as well as a pure Ag nanostructure. Kinetics and morphological evolutions in the silver deposition with different nanocatalysts were comparatively studied. The Pt catalyst displayed the highest catalytic activity for electroless silver deposition, followed by the order Pd > Au > Ag. Another catalytic activity of the fabricated bimetallic structures in the carbon monoxide conversion was further evaluated at low-temperature conditions. The bimetallic systems showed significantly higher catalytic activity than that from a pure Ag system.

  1. Bimetallic Au-decorated Pd catalyst for the liquid phase hydrodechlorination of 2,4-dichlorophenol

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Juan [School of the Environment, Donghua University, Shanghai 201620 (China); Chen, Huan, E-mail: hchen404@njust.edu.cn [Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental & Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Chen, Quanyuan; Huang, Zhaolu [School of the Environment, Donghua University, Shanghai 201620 (China)

    2016-11-30

    Graphical abstract: 2,4-Dichlorophenol can be converted to phenol via the catalytic HDC method over Pd-Au/CNTs and the catalytic activity first increased and then decreased with Au content. - Highlights: • Bimetallic catalysts had smaller metal particles and larger number of exposed active site than the monometallic catalysts. • The cationization of Pd particles increased with Au content in the bimetallic catalysts. • The bimetallic catalysts exhibited higher catalytic activities for HDC of 2,4-DCP than the monometallic counterparts. • The concerted pathway for HDC of 2,4-DCP was more predominant with increasing Au content in the bimetallic catalyst. - Abstract: Monometallic and bimetallic Pd-Au catalysts supported on multi-walled carbon nanotubes (CNTs) with varied Au cooperation amounts were prepared using the complexing-reduction method in the presence of tetrahydrofuran (THF). The liquid phase catalytic hydrodechlorination (HDC) of 2,4-dichlorophenol (2,4-DCP) was investigated over these bimetallic catalysts. The catalysts were characterized by N{sub 2} adsorption-desorption isotherms, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and H{sub 2} chemisorption. Characterization results showed that the co-reduction of Pd and Au mainly formed alloy-like structure. The bimetallic catalysts had smaller metal particles and larger numbers of exposed active site than that of monometallic catalysts. In addition, compared with Pd(1.7)/CNTs and Au(0.4)/CNTs, the binding energies of Pd 3d{sub 5/2} shifted to higher positions while that of Au 4f{sub 7/2} had negative shifts in the Pd-Au bimetallic catalysts, which can be ascribed to the electrons transferred from metal Pd to Au and the cationization of Pd particles was enhanced. Accordingly, the bimetallic Pd-Au particles with different Au contents in the catalysts exhibited varied synergistic effects for the catalytic HDC of 2,4-DCP, with Pd(1.8)Au(0.4)/CNTs having the highest

  2. Monitoring Microbially Influenced Corrosion

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    Abstract Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria (SRB). The applicability and reliability of a number of corrosion monitoring techniques for monitoring MIC has been evaluated in experiments...... and diffusional effects and unreliable corrosion rates, when biofilm and ferrous sulphide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 by electrochemical techniques. Weight loss coupons and ER are recommended as necessary basic monitoring techniques....... EIS might be used for detection of MIC as the appearance of very large capacitances can be attributed to the combined ferrous sulphide and biofilm formation. Capacitance correlates directly with sulphide concentration in sterile sulphide media. Keywords: Corrosion monitoring, carbon steel, MIC, SRB...

  3. Gas-Phase Growth of Heterostructures of Carbon Nanotubes and Bimetallic Nanowires

    Directory of Open Access Journals (Sweden)

    Whi Dong Kim

    2011-01-01

    Full Text Available A simple, inexpensive, and viable method for growing multiple heterostructured carbon nanotubes (CNTs over the entire surface of Ni-Al bimetallic nanowires (NWs in the gas phase was developed. Polymer-templated bimetallic nitrate NWs were produced by electrospinning in the first step, and subsequent calcination resulted in the formation of bimetallic oxide NWs by thermal decomposition. In the second step, free-floating bimetallic NWs were produced by spray pyrolysis in an environment containing hydrogen gas as a reducing gas. These NWs were continuously introduced into a thermal CVD reactor in order to grow CNTs in the gas phase. Scanning electron microscopy (SEM, transmission electron microscopy (TEM, and Raman spectrometry analyses revealed that the catalytic Ni sites exposed in the non-catalytic Al matrix over the entire surface of the bimetallic NWs were seeded to radially grow highly graphitized CNTs, which resembled “foxtail” structures. The grown CNTs were found to have a relatively uniform diameter of approximately 10±2 nm and 10 to 15 walls with a hollow core. The average length of the gas-phase-grown CNTs can be controlled between 100 and 1000 nm by adjusting the residence time of the free-floating bimetallic NWs in the thermal CVD reactor.

  4. Erosion-corrosion; Erosionkorrosion

    Energy Technology Data Exchange (ETDEWEB)

    Aghili, B

    1999-05-01

    A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment 32 refs, 16 figs, tabs

  5. Electrochemical corrosion studies

    Science.gov (United States)

    Knockemus, W. W.

    1986-01-01

    The objective was to gain familiarity with the Model 350 Corrosion Measurement Console, to determine if metal protection by grease coatings can be measured by the polarization-resistance method, and to compare corrosion rates of 4130 steel coated with various greases. Results show that grease protection of steel may be determined electrochemically. Studies were also conducted to determine the effectiveness of certain corrosion inhibitors on aluminum and steel.

  6. Green synthesis and applications of Au-Ag bimetallic nanoparticles.

    Science.gov (United States)

    Meena Kumari, M; Jacob, John; Philip, Daizy

    2015-02-25

    This paper reports for the first time the synthesis of bimetallic nanoparticles at room temperature using the fruit juice of pomegranate. Simultaneous reduction of gold and silver ions in different molar ratios leads to the formation of alloy as well as core-shell nanostructures. The nanoparticles have been characterized using UV-vis spectroscopy, transmission electron microscopy, Fourier Transform Infrared Spectroscopy and X-ray diffraction. The synthesized alloy particles are used as catalysts in the reduction of 2-, 3-, 4-nitrophenols to the corresponding amines and in the degradation of methyl orange. The reduction kinetics for all the reactions follows pseudo-first order. The rate constants follow the order k4-nitrophenolnanoparticles enhances the thermal conductivity of the base fluid (water) showing nanofluid application. The nitric oxide and hydroxyl radical scavenging activity shown by the nanoparticles promise the potential application in biomedical field.

  7. Enantioselective Epoxide Polymerization Using a Bimetallic Cobalt Catalyst

    KAUST Repository

    Thomas, Renee M.

    2010-11-24

    A highly active enantiopure bimetallic cobalt complex was explored for the enantioselective polymerization of a variety of monosubstituted epoxides. The polymerizations were optimized for high rates and stereoselectivity, with s-factors (kfast/kslow) for most epoxides exceeding 50 and some exceeding 300, well above the threshold for preparative utility of enantiopure epoxides and isotactic polyethers. Values for mm triads of the resulting polymers are typically greater than 95%, with some even surpassing 98%. In addition, the use of a racemic catalyst allowed the preparation of isotactic polyethers in quantitative yields. The thermal properties of these isotactic polyethers are presented, with many polymers exhibiting high T m values. This is the first report of the rapid synthesis of a broad range of highly isotactic polyethers via the enantioselective polymerization of racemic epoxides. © 2010 American Chemical Society.

  8. The selective hydrogenation of crotonaldehyde over bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Schoeb, Ann M. [Iowa State Univ., Ames, IA (United States)

    1997-10-17

    The selective hydrogenation of crotonaldehyde has been investigated over a monometallic Pt/SiO2 catalyst and platinum bimetallic catalysts where the second metal was either silver, copper, or tin. The effects of addition of a second metal to the Pt/SiO2 system on the selectivity to crotyl alcohol were investigated. The Pt-Sn bimetallic catalysts were characterized by hydrogen chemisorption, 1H NMR and microcalorimetry. The Pt-Ag/SiO2 and Pt-Cu/SiO2 catalysts were characterized by hydrogen chemisorption. Pt-Sn/SiO2 catalysts selectively hydrogenated crotonaldehyde to crotyl alcohol and the method of preparation of these catalysts affected the selectivity. The most selective Pt-Sn/SiO2 catalysts for the hydrogenation of crotonaldehyde to crotyl alcohol were those in which the Sn precursor was dissolved in a HCl solution. Sn increased both the rate of formation of butyraldehyde and the rate of formation of crotyl alcohol. The Pt/SiO2, Pt-Ag/SiO2 and Pt-Cu/SiO2 catalysts produced only butyraldehyde. Initial heats of adsorption (~90 kJ/mol) measured using microcalorimetry were not affected by the presence of Sn on Pt. We can conclude that there is no through metal electronic interaction between Pt and Sn at least with respect to hydrogen surface bonds since the Pt and Pt-Sn at least with respect to hydrogen surface bonds since the Pt and Pt-Sn had similar initial heats of adsorption coupled with the invariance of the 1H NMR Knight shift.

  9. Lanthanide bimetallic helicates for in vitro imaging and sensing.

    Science.gov (United States)

    Bünzli, Jean-Claude G; Chauvin, Anne-Sophie; Vandevyver, Caroline D B; Bo, Song; Comby, Steve

    2008-01-01

    As the need for targeting luminescent biolabels increases, for mapping selected analytes, imaging of cells and organs, and tracking in cellulo processes, lanthanide bimetallic helicates are emerging as versatile bioprobes. The wrapping of three ligand strands around two metallic centers by self-assembly affords robust molecular edifices with tunable chemical and photophysical properties. In addition, heterometallic helical chelates can be assembled leading to bioprobes with inherent chiral properties. In this paper, we review the literature demonstrating that neutral [Ln(2)(L(CX))(3)] (x=1-3) helicates represent a viable alternative to existing chelating agents for bio-analyses, while featuring specific enhanced properties. These bimetallic chelates self-assemble in water, and at physiological pH the 2:3 (Ln:L(CX)) complex is by far the dominant species, conditional stability constants logbeta(23) being in the range 23-30. The metal ions are 9-coordinate and lie in sites with slightly distorted D(3) symmetry. Efficient protection from water interaction by the tightly wrapped ligand strands results in sizeable photophysical properties, with quantum yields up to 24% for Eu(III) and 11% for Tb(III), while the luminescence of several other visible and/or near-infrared emitting Ln(III) ions is also sensitized. Noncytotoxicity for all the helicates is established for several living cell lines including HeLa, HaCat, MCF-7, 5D10, and Jurkat. We present new data pertaining to the live cell imaging ability of [Eu(2)(L(C1))(3)] and compare the three systems with x=1-3 with respect to thermodynamic stability, photophysics, cell-permeation ability, and targeting capability for sensing in cellulo processes. Prospects of derivatization for characterizing specific biological interactions are discussed.

  10. Coatings and Corrosion Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Purpose: The mission of the Coatings and Corrosion Laboratory is to develop and analyze the effectiveness of innovative coatings test procedures while evaluating the...

  11. Corrosion in the oil industry

    Energy Technology Data Exchange (ETDEWEB)

    Brondel, D. (Sedco Forex, Montrouge (France)); Edwards, R. (Schlumberger Well Services, Columbus, OH (United States)); Hayman, A. (Etudes et Productions Schlumberger, Clamart (France)); Hill, D. (Schlumberger Dowell, Tulsa, OK (United States)); Mehta, S. (Schlumberger Dowell, St. Austell (United Kingdom)); Semerad, T. (Mobil Oil Indonesia, Inc., Sumatra (Indonesia))

    1994-04-01

    Corrosion costs the oil industry billions of dollars a year, a fact that makes the role of the corrosion engineer an increasingly important one. Attention is paid to how corrosion affects every aspect of exploration and production, from offshore rigs to casing. Also the role of corrosion agents such as drilling and production fluids is reviewed. Methods of control and techniques to monitor corrosion are discussed, along with an explanation of the chemical causes of corrosion. 21 figs., 32 refs.

  12. Carbon Dioxide Corrosion:

    DEFF Research Database (Denmark)

    Fosbøl, Philip Loldrup

    2008-01-01

    CO2 corrosion is a general problem in the industry and it is expensive. The focus of this study is an oil gas production related problem. CO2 corrosion is observed in offshore natural gas transportation pipelines. A general overview of the problem is presented in chapter 1. The chemical system co...

  13. Avionics Corrosion Control Study

    Science.gov (United States)

    1974-01-01

    found at seacoast (harsn) environnents is the most destructive. Differences in electrolte concentration and oxygen concentration promote corrosion...against corrosion by acting as moisture and gas barriers. CMCVIT B0.4ID *COATINGS Polyurethane’s, cprxies, silicones, and polystyrenes are the most

  14. Bimetallic Au-decorated Pd catalyst for the liquid phase hydrodechlorination of 2,4-dichlorophenol

    Science.gov (United States)

    Zhou, Juan; Chen, Huan; Chen, Quanyuan; Huang, Zhaolu

    2016-11-01

    Monometallic and bimetallic Pd-Au catalysts supported on multi-walled carbon nanotubes (CNTs) with varied Au cooperation amounts were prepared using the complexing-reduction method in the presence of tetrahydrofuran (THF). The liquid phase catalytic hydrodechlorination (HDC) of 2,4-dichlorophenol (2,4-DCP) was investigated over these bimetallic catalysts. The catalysts were characterized by N2 adsorption-desorption isotherms, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and H2 chemisorption. Characterization results showed that the co-reduction of Pd and Au mainly formed alloy-like structure. The bimetallic catalysts had smaller metal particles and larger numbers of exposed active site than that of monometallic catalysts. In addition, compared with Pd(1.7)/CNTs and Au(0.4)/CNTs, the binding energies of Pd 3d5/2 shifted to higher positions while that of Au 4f7/2 had negative shifts in the Pd-Au bimetallic catalysts, which can be ascribed to the electrons transferred from metal Pd to Au and the cationization of Pd particles was enhanced. Accordingly, the bimetallic Pd-Au particles with different Au contents in the catalysts exhibited varied synergistic effects for the catalytic HDC of 2,4-DCP, with Pd(1.8)Au(0.4)/CNTs having the highest catalytic activity. For the bimetallic catalysts, a disproportional increase of turnover frequency (TOF) was observed with increasing Au content due to the enhanced cationization of Pd particles. Moreover, the dechlorination of 2,4-DCP over the supported monometallic and bimetallic catalysts proceeded via both the stepwise and concerted pathway, and the concerted pathway became predominant with Au decoration amount in the catalyst.

  15. Monitoring corrosion rates and localised corrosion in low conductivity water

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    2006-01-01

    Monitoring of low corrosion rates and localised corrosion in a media with low conductivity is a challenge. In municipal district heating, quality control may be improved by implementing on-line corrosion monitoring if a suitable technique can be identified to measure both uniform and localised...... corrosion. Electrochemical techniques (LPR, EIS, crevice corrosion current) as well as direct measurement techniques (high-sensitive electrical resistance, weight loss) have been applied in operating plants. Changes in the corrosion processes are best monitored in non-aggressive, low conductivity media...... with sensitive electrical resistance technique and crevice corrosion current measurements....

  16. Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion

    OpenAIRE

    Xuming Zhang; Guosong Wu; Xiang Peng; Limin Li; Hongqing Feng; Biao Gao; Kaifu Huo; Chu, Paul K.

    2015-01-01

    Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface c...

  17. Corrosion Inhibitors for Reinforced Concrete

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Steel corrosion in reinforced concrete structures has been a major problem across the U.S. Steel-reinforced concrete structures are continually subject to attack by corrosion brought on by naturally occurring environmental conditions. FerroGard, a corrosion inhibitor, developed by Sika Corporation, penetrates hardened concrete to dramatically reduce corrosion by 65% and extend the structure's service life.

  18. Automated Methods Of Corrosion Measurements

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers; Andersen, Jens Enevold Thaulov; Reeve, John Ch

    1997-01-01

    The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell.......The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell....

  19. Direct decomposition of methane over SBA-15 supported Ni, Co and Fe based bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pudukudy, Manoj, E-mail: manojpudukudy@gmail.com [Fuel Cell Institute, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia); Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia); Yaakob, Zahira, E-mail: zahirayaakob65@gmail.com [Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia); Akmal, Zubair Shamsul [Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, UKM, Bangi 43600, Selangor (Malaysia)

    2015-03-01

    Graphical abstract: - Highlights: • Synthesis and characterization of Ni, Co and Fe based bimetallic catalysts supported over SBA-15. • Thermocatalytic decomposition of methane over the SBA-15 supported bimetallic catalysts. • Enhanced catalytic efficiency of the bimetallic catalysts for the production of CO{sub x} free hydrogen and nanocarbon. • Production of value added open tip hollow multi-walled carbon nanotubes. • Crystalline characterization of carbon nanotubes by XRD, Raman and thermogravimetric analysis. - Abstract: Thermocatalytic decomposition of methane is an alternative route for the production of CO{sub x}-free hydrogen and carbon nanomaterials. In this work, a set of novel Ni, Co and Fe based bimetallic catalysts supported over mesoporous SBA-15 was synthesized by a facile wet impregnation route, characterized for their structural, textural and reduction properties and were successfully used for the methane decomposition. The fine dispersion of metal oxide particles on the surface of SBA-15, without affecting its mesoporous texture was clearly shown in the low angle X-ray diffraction patterns and the transmission electron microscopy (TEM) images. The nitrogen sorption analysis showed the reduced specific surface area and pore volume of SBA-15, after metal loading due to the partial filling of hexagonal mesopores by metal species. The results of methane decomposition experiments indicated that all of the bimetallic catalysts were highly active and stable for the reaction at 700 °C even after 300 min of time on stream (TOS). However, a maximum hydrogen yield of ∼56% was observed for the NiCo/SBA-15 catalyst within 30 min of TOS. A high catalytic stability was shown by the CoFe/SBA-15 catalyst with 51% of hydrogen yield during the course of reaction. The catalytic stability of the bimetallic catalysts was attributed to the formation of bimetallic alloys. Moreover, the deposited carbons were found to be in the form of a new set of hollow

  20. Ordered macroporous bimetallic nanostructures: design, characterization, and applications.

    Science.gov (United States)

    Lu, Lehui; Eychmüller, Alexander

    2008-02-01

    Ordered porous metal nanomaterials have current and future potential applications, for example, as catalysts, as photonic crystals, as sensors, as porous electrodes, as substrates for surface-enhanced Raman scattering (SERS), in separation technology, and in other emerging nanotechnologies. Methods for creating such materials are commonly characterized as "templating", a technique that involves first the creation of a sacrificial template with a specific porous structure, followed by the filling of these pores with desired metal materials and finally the removal of the starting template, leaving behind a metal replica of the original template. From the viewpoint of practical applications, ordered metal nanostructures with hierarchical porosity, namely, macropores in combination with micropores or mesopores, are of particular interest because macropores allow large guest molecules to access and an efficient mass transport through the porous structures is enabled while the micropores or mesopores enhance the selectivity and the surface area of the metal nanostructures. For this objective, colloidal crystals (or artificial opals) consisting of three-dimensional (3D) long-range ordered arrays of silica or polymer microspheres are ideal starting templates. However, with respect to the colloidal crystal templating strategies for production of ordered porous metal nanostructures, there are two challenging questions for materials scientists: (1) how to uniformly and controllably fill the interstitial space of the colloidal crystal templates and (2) how to generate ordered composite metal nanostructures with hierarchical porosity. This Account reports on recent work in the development and applications of ordered macroporous bimetallic nanostructures in our laboratories. A series of strategies have been explored to address the challenges in colloidal crystal template techniques. By rationally tailoring experimental parameters, we could readily and selectively design

  1. The Corrosion and Preservation of Iron Antiques.

    Science.gov (United States)

    Walker, Robert

    1982-01-01

    Discusses general corrosion reactions (iron to rust), including corrosion of iron, sulfur dioxide, chlorides, immersed corrosion, and underground corrosion. Also discusses corrosion inhibition, including corrosion inhibitors (anodic, cathodic, mixed, organic); safe/dangerous inhibitors; and corrosion/inhibition in concrete/marble, showcases/boxes,…

  2. Cr(VI) reduction in wastewater using a bimetallic galvanic reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lugo-Lugo, Violeta [Centro Conjunto de Investigacion en Quimica Sustentable UAEM-UNAM, Universidad Autonoma del Estado de Mexico, Facultad de Quimica. Paseo Colon interseccion Paseo Tollocan S/N. C.P. 50120, Toluca (Mexico); Barrera-Diaz, Carlos, E-mail: cbarrera@uaemex.mx [Centro Conjunto de Investigacion en Quimica Sustentable UAEM-UNAM, Universidad Autonoma del Estado de Mexico, Facultad de Quimica. Paseo Colon interseccion Paseo Tollocan S/N. C.P. 50120, Toluca (Mexico); Bilyeu, Bryan [Xavier University of Louisiana, Department of Chemistry, 1 Drexel Drive, New Orleans, LA 70125 (United States); Balderas-Hernandez, Patricia [Centro Conjunto de Investigacion en Quimica Sustentable UAEM-UNAM, Universidad Autonoma del Estado de Mexico, Facultad de Quimica. Paseo Colon interseccion Paseo Tollocan S/N. C.P. 50120, Toluca (Mexico); Urena-Nunez, Fernando [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Col. Escandon, Delegacion Miguel Hidalgo, C.P. 11801, Mexico, D.F. (Mexico); Sanchez-Mendieta, Victor [Centro Conjunto de Investigacion en Quimica Sustentable UAEM-UNAM, Universidad Autonoma del Estado de Mexico, Facultad de Quimica. Paseo Colon interseccion Paseo Tollocan S/N. C.P. 50120, Toluca (Mexico)

    2010-04-15

    The electrochemical reduction of Cr(VI)-Cr(III) in wastewater by iron and copper-iron bimetallic plates was evaluated and optimized. Iron has been used as a reducing agent, but in this work a copper-iron galvanic system in the form of bimetallic plates is applied to reducing hexavalent chromium. The optimal pH (2) and ratio of copper to iron surface areas (3.5:1) were determined in batch studies, achieving a 100% reduction in about 25 min. The Cr(VI) reduction kinetics for the bimetallic system fit a first order mechanism with a correlation of 0.9935. Thermodynamic analysis shows that the Cr(VI) reduction is possible at any pH value. However, at pH values above 3.0 for iron and 5.5 for chromium insoluble species appear, indicating that the reaction will be hindered. Continuous column studies indicate that the bimetallic copper-iron galvanic system has a reduction capacity of 9.5890 mg Cr(VI) cm{sup -2} iron, whereas iron alone only has a capacity of 0.1269 mg Cr(VI) cm{sup -2}. The bimetallic copper-iron galvanic system is much more effective in reducing hexavalent chromium than iron alone. The exhausted plates were analyzed by SEM, EDS, and XRD to determine the mechanism and the surface effects, especially surface fouling.

  3. Facile Synthesis of Highly Active and Robust Ni-Mo Bimetallic Electrocatalyst for Hydrocarbon Oxidation in Solid Oxide Fuel Cells

    NARCIS (Netherlands)

    Hua, B.; Li, M.; Zhang, Y.-Q.; Chen, J.; Sun, Y.-F.; Yan, N.; Li, J.; Luo, J.L.

    2016-01-01

    We report a novel Ni–Mo bimetallic alloy decorated with multimicrocrystals as an efficient anode catalyst for hydrocarbon-fueled solid oxide fuel cells (SOFCs). We show that these Ni–Mo bimetallic alloys are highly active, thermally stable, and sulfur/coke tolerant electrocatalysts for hydrocarbon o

  4. Corrosion control in mining technology

    Energy Technology Data Exchange (ETDEWEB)

    Telekesi, J.

    1985-01-01

    An overview of corrosion effects in mining technology and the importance of protection is presented. The most common corrosion processes and effects are summarized and the system and criteria of their avoidance are discussed in detail. Preventive measures are recommended to decrease possible corrosion effects including the selection of corrosion-resistive constructions, to use protective coatings and inhibition techniques and some other protection possibilities where applicable. The organization aspects and the economic impact of corrosion control in mining are discussed.

  5. Corrosion-resistant uranium

    Science.gov (United States)

    Hovis, V.M. Jr.; Pullen, W.C.; Kollie, T.G.; Bell, R.T.

    1981-10-21

    The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion.

  6. Ligand-controlled Co-reduction versus electroless Co-deposition: synthesis of nanodendrites with spatially defined bimetallic distributions.

    Science.gov (United States)

    Ortiz, Nancy; Weiner, Rebecca G; Skrabalak, Sara E

    2014-12-23

    The predictable synthesis of bimetallic nanostructures via co-reduction of two metal precursors is challenging due to our limited understanding of precursor ligand effects. Here, the influence of different metal-ligand environments is systematically examined in the synthesis of Pd-Pt nanostructures as a model bimetallic system. Nanodendrites with different spatially defined Pd-Pt compositions are achieved, where the local ligand environments of metal precursors dictate if temporally separated co-reduction dominates to achieve core-shell nanostructures or whether electroless co-deposition proceeds to facilitate alloyed nanostructure formation. As the properties of bimetallic nanomaterials depend on crystal ordering and composition, chemical routes to structurally defined bimetallic nanomaterials are critically needed. The approaches reported here should be applicable to other bimetallic compositions given the established reactivity of coordination complexes available for use as precursors.

  7. Salt flux synthesis of single and bimetallic carbide nanowires

    Science.gov (United States)

    Leonard, Brian M.; Waetzig, Gregory R.; Clouser, Dale A.; Schmuecker, Samantha M.; Harris, Daniel P.; Stacy, John M.; Duffee, Kyle D.; Wan, Cheng

    2016-07-01

    Metal carbide compounds have a broad range of interesting properties and are some of the hardest and highest melting point compounds known. However, their high melting points force very high reaction temperatures and thus limit the formation of high surface area nanomaterials. To avoid the extreme synthesis temperatures commonly associated with these materials, a new salt flux technique has been employed to reduce reaction temperatures and form these materials in the nanometer regime. Additionally, the use of multiwall carbon nanotubes as a reactant further reduces the diffusion distance and provides a template for the final carbide materials. The metal carbide compounds produced through this low temperature salt flux technique maintain the nanowire morphology of the carbon nanotubes but increase in size to ˜15-20 nm diameter due to the incorporation of metal in the carbon lattice. These nano-carbides not only have nanowire like shape but also have much higher surface areas than traditionally prepared metal carbides. Finally, bimetallic carbides with composition control can be produced with this method by simply using two metal precursors in the reaction. This method provides the ability to produce nano sized metal carbide materials with size, morphology, and composition control and will allow for these compounds to be synthesized and studied in a whole new size and temperature regime.

  8. STEM-EDX tomography of bimetallic nanoparticles: A methodological investigation

    Energy Technology Data Exchange (ETDEWEB)

    Slater, Thomas J.A.; Janssen, Arne [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Camargo, Pedro H.C. [Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, São Paulo (Brazil); Burke, M. Grace [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Zaluzec, Nestor J. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Nanoscience and Technology Division, Argonne National Laboratory, Argonne, IL 60439, US (United States); Haigh, Sarah J., E-mail: sarah.haigh@manchester.ac.uk [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom)

    2016-03-15

    This paper presents an investigation of the limitations and optimisation of energy dispersive X-ray (EDX) tomography within the scanning transmission electron microscope, focussing on application of the technique to characterising the 3D elemental distribution of bimetallic AgAu nanoparticles. The detector collection efficiency when using a standard tomography holder is characterised using a tomographic data set from a single nanoparticle and compared to a standard low background double tilt holder. Optical depth profiling is used to investigate the angles and origin of detector shadowing as a function of specimen field of view. A novel time-varied acquisition scheme is described to compensate for variations in the intensity of spectrum images at each sample tilt. Finally, the ability of EDX spectrum images to satisfy the projection requirement for nanoparticle samples is discussed, with consideration of the effect of absorption and shadowing variations. - Highlights: • We investigate the methodology of STEM-EDX tomography of nanoparticles. • We present a time-varied acquisition scheme to compensate for detector shadowing. • The ability of STEM-EDX tomography to meet the projection requirement is discussed.

  9. Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Chunshan, Song; Kirby, S.; Schmidt, E. [Pennsylvania State Univ., University Park, PA (United States)] [and others

    1995-12-31

    The objective of this project is to explore bimetallic dispersed catalysts for more efficient coal liquefaction. Coal liquefaction involves cleavage of methylene, dimethylene and ether bridges connecting various aromatic units and the reactions of various oxygen functional groups. This paper describes recent results on (1) hydrodeoxygenation of O-containing polycyclic model compounds using novel organometallic catalyst precursors; and (2) activity and selectivity of dispersed Fe catalysts from organometallic and inorganic precursors for hydrocracking of 4-(1-naphthylmethyl) bibenzyl. The results showed that some iron containing catalysts have higher activity in the sulfur-free form, contrary to conventional wisdom. Adding sulfur to Fe precursors with Cp-ligands decreased the activity of the resulting catalyst. This is in distinct contrast to the cases with iron pentacarbonyl and superfine Fe{sub 2}O{sub 3}, where S addition increased their catalytic activity substantially. A positive correlation between sulfur addition and increased activity can be seen, but a reversed trend between Fe cluster size and hydrocracking conversion could be observed, for carbonyl-type Fe precursors. It is apparent that the activity and selectivity of Fe catalysts for NMBB conversion depends strongly on both the type of ligand environment, the oxidation state and the number of intermetal bonds in the molecular precursor.

  10. Regeneration of sulfur-fouled bimetallic Pd-based catalysts.

    Science.gov (United States)

    Chaplin, Brian P; Shapley, John R; Werth, Charles J

    2007-08-01

    Pd-based catalysts provide efficient and selective reduction of several drinking water contaminants, but their long-term application requires effective treatments for catalyst regeneration following fouling by constituents in natural waters. This studytested alumina-supported Pd-Cu and Pd-In bimetallic catalysts for nitrate reduction with H2 after sulfide fouling and oxidative regeneration procedures. Both catalysts were severely deactivated after treatment with microM levels of sulfide. Regeneration was attempted with dissolved oxygen, hydrogen peroxide, sodium hypochlorite, and heated air. Only sodium hypochlorite and heated air were effective regenerants, specifically restoring nitrate reduction rates for a Pd-In/gamma-Al2O3 catalyst from 20% to between 39 and 60% of original levels. Results from ICP-MS revealed that sodium hypochlorite caused dissolution of Cu from the Pd-Cu catalyst but that the Pd-In catalyst was chemically stable over a range of sulfide fouling and oxidative regenerative conditions. Analysis byXPS indicated that PdS and In2S3 complexes form during sulfide fouling, where sulfur is present as S2-, and that regeneration with sodium hypochlorite converts a portion of the S2- to S6+, with a corresponding increase in reduction rates. These results indicate that Pd-In catalysts show exceptional promise for being robust under fouling and regeneration conditions that may occur when treating natural waters.

  11. Formation of Cu/Pd bimetallic crystals by electrochemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, A.E. [Instituto de Ingenieria Electroquimica y Corrosion (INIEC), Departamento de Ingenieria Quimica, Universidad Nacional del Sur, Avda. Alem 1253, 8000 Bahia Blanca (Argentina); Salinas, D.R., E-mail: dsalinas@uns.edu.a [Instituto de Ingenieria Electroquimica y Corrosion (INIEC), Departamento de Ingenieria Quimica, Universidad Nacional del Sur, Avda. Alem 1253, 8000 Bahia Blanca (Argentina)

    2010-04-15

    The early stages of the palladium electrodeposition process onto a vitreous carbon (VC) substrate as well as the deposition of Cu on such Pd/VC modified surface were investigated using classical electrochemical techniques, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Within the potential range considered the kinetics of the Pd electrodeposition from a PdCl{sub 2} acid solution can be described by a model involving progressive nucleation on active sites and diffusion-controlled 3D growth. The nucleation rate constant, A{sub 0}, and the number of active sites of the substrate, N{sub 0}, were determined from the analysis of potentiostatic current transients on the basis of an existing theoretical model. The AFM images corroborated the progressive nucleation mechanism showing irregular palladium crystals randomly distributed over the VC surface, with different sizes and 3D morphological characteristics. The electrodeposition of Cu was carried out onto the characterized Pd/VC modified surface from a Cu{sup 2+} containing solution using a well defined polarization routine. The SEM/EDX images confirmed the formation of Cu/Pd bimetallic crystals uniformly distributed on the VC surface and the in situ AFM images obtained during this process corroborated that Cu formed a core-shell structure with the Pd crystals. Nevertheless, the subsequent anodic stripping produced only a partial dissolution of the Cu deposits, and therefore, the formation of a Cu/Pd alloy could be inferred.

  12. Effects of different additives on bimetallic Au-Pt nanoparticles electrodeposited onto indium tin oxide electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Ballarin, Barbara, E-mail: ballarin@ms.fci.unibo.i [Dipartimento di Chimica Fisica ed Inorganica, Universita di Bologna, V.le Risorgimento, 4, 40136-Bologna (Italy)] [INSTM, UdR Bologna (Italy); Gazzano, Massimo [ISOF-CNR, V. Selmi, 40126-Bologna (Italy); Tonelli, Domenica [Dipartimento di Chimica Fisica ed Inorganica, Universita di Bologna, V.le Risorgimento, 4, 40136-Bologna (Italy)] [INSTM, UdR Bologna (Italy)

    2010-09-01

    Bimetallic Au-Pt nanoparticles (Au-Pt{sub NPs}) have been synthesized using an electrochemical reduction approach. The effects of the addition of different additives in the electrodeposition bath namely KI, 1-nonanesulfonic acid sodium salt and Triton X-100 have been investigated. The structural characterization of the bimetallic nanoparticles has been carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), UV-vis spectroscopy, X-ray diffraction (XRD) and cyclic voltammetry (CV). The Au-Pt{sub NPs} prepared in the presence of KI and Triton X-100 characterized by a relatively narrow size distribution as well as a higher particle density and surface coverage whereas no changes in the morphology were observed. These results suggest a dependence of the size and distribution of the bimetallic nanoparticles from the type and concentration of the additives employed.

  13. Description of the performances of a thermo-mechanical energy harvester using bimetallic beams

    Science.gov (United States)

    Arnaud, A.; Boughaleb, J.; Monfray, S.; Boeuf, F.; Cugat, O.; Skotnicki, T.

    2016-06-01

    Many recent researches have been focused on the development of thermal energy harvesters using thermo-mechanical or thermo-electrical coupling phenomena associated to a first-order thermodynamic transition. In the case of the bimetallic strip heat engine, the exploitation of the thermo-mechanical instability of bimetallic membranes placed in a thermal gradient enables to convert heat into kinetic energy. This paper is a contribution to the modeling and the comprehension of these heat engines. By restraining the study to the simply-supported bimetallic beams and using a Ritz approximation of the beam shape, this paper aims to give an analytical solution to the first mode of the composite beams and then to evaluate the efficiency of the harvesters exploiting these kinds of instability.

  14. Design and performance benchmark of various architectures of a piezoelectric bimetallic strip heat engine

    Science.gov (United States)

    Boughaleb, J.; Arnaud, A.; Monfray, S.; Cottinet, P. J.; Quenard, S.; Boeuf, F.; Guyomar, D.; Skotnicki, T.

    2016-06-01

    This paper deals with an investigation of a thermal energy harvester based on the coupling of a piezoelectric membrane and a bimetallic strip heat engine. The general working principle of the device consists of a double conversion mechanism: the thermal energy is first converted into mechanical energy by means of a bimetallic strip, then the mechanical energy is converted into electricity with a piezoelectric membrane. This paper deals with the study and optimization of the harvester's design. First, the piezoelectric membrane configuration is studied to find the most efficient way to convert mechanical energy into electricity. A benchmark of various piezoelectric materials is then presented to point out the most efficient materials. Finally, our study focuses on the bimetallic strip's properties: the effect of its dimensions of its thermal hysteresis on the harvester's performances are studied and compared. Thanks to these different steps, we were able to point out the best configuration to convert efficiently thermal heat flux into electricity.

  15. The quality of the joint between alloy steel and unalloyed cast steel in bimetallic layered castings

    Directory of Open Access Journals (Sweden)

    T. Wróbel

    2012-01-01

    Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. ferritic-pearlitic unalloyed cast steel, whereas working part (layer is plate of austenitic alloy steel sort X2CrNi 18-9. The ratio of thickness between bearing and working part is 8:1. The aim of paper was assessed the quality of the joint between bearing and working part in dependence of pouring temperature and carbon concentration in cast steel. The quality of the joint in bimetallic layered castings was evaluated on the basis of ultrasonic non-destructive testing, structure and microhardness researches.

  16. Microbially supported synthesis of catalytically active bimetallic Pd-Au nanoparticles

    DEFF Research Database (Denmark)

    Hosseinkhani, Baharak; Søbjerg, Lina Sveidal; Rotaru, Amelia-Elena

    2012-01-01

    Bimetallic nanoparticles are considered the next generation of nanocatalysts with increased stability and catalytic activity. Bio-supported synthesis of monometallic nanoparticles has been proposed as an environmentally friendly alternative to the conventional chemical and physical protocols....... In this study we synthesize bimetallic bio-supported Pd-Au nanoparticles for the first time using microorganisms as support material. The synthesis involved two steps: (1) Formation of monometallic bio-supported Pd(0) and Au(0) nanoparticles on the surface of Cupriavidus necator cells, and (2) formation...... of bimetallic bio-supported nanoparticles by reduction of either Au(III) or Pd(II) on to the nanoparticles prepared in step one. Bio-supported monometallic Pd(0) or Au(0) nanoparticles were formed on the surface of C. necator by reduction of Pd(II) or Au(III) with formate. Addition of Au(III) or Pd...

  17. Bimetallic Metal-Organic Frameworks for Controlled Catalytic Graphitization of Nanoporous Carbons

    Science.gov (United States)

    Tang, Jing; Salunkhe, Rahul R.; Zhang, Huabin; Malgras, Victor; Ahamad, Tansir; Alshehri, Saad M.; Kobayashi, Naoya; Tominaka, Satoshi; Ide, Yusuke; Kim, Jung Ho; Yamauchi, Yusuke

    2016-07-01

    Single metal-organic frameworks (MOFs), constructed from the coordination between one-fold metal ions and organic linkers, show limited functionalities when used as precursors for nanoporous carbon materials. Herein, we propose to merge the advantages of zinc and cobalt metals ions into one single MOF crystal (i.e., bimetallic MOFs). The organic linkers that coordinate with cobalt ions tend to yield graphitic carbons after carbonization, unlike those bridging with zinc ions, due to the controlled catalytic graphitization by the cobalt nanoparticles. In this work, we demonstrate a feasible method to achieve nanoporous carbon materials with tailored properties, including specific surface area, pore size distribution, degree of graphitization, and content of heteroatoms. The bimetallic-MOF-derived nanoporous carbon are systematically characterized, highlighting the importance of precisely controlling the properties of the carbon materials. This can be done by finely tuning the components in the bimetallic MOF precursors, and thus designing optimal carbon materials for specific applications.

  18. Preparation and characterization of Ni/Co bimetallic nano-clusters

    Institute of Scientific and Technical Information of China (English)

    Jinzhang Gao; Fei Guan; Yongjun Ma; Jingwan Kang

    2003-01-01

    Ni/Co bimetallic nano-cluters have been prepared from the aqueous solution by reducing their corresponding metal salts under suitable conditions. The experimental conditions including the type and concentration of protective agent, feeding order and the pH of the solution that influence the average particle size have been studied in detail. Transmission electron microscopy (TEM)indicates that the shape of those bimetallic nano-cluster particles is spheroid. The alloy structure has been shown by X-ray powder diffraction (XRD). The X-ray photoelectron spectroscopic (XPS) data have confirmed that the nickel and cobalt in the bimetallic nano-clusters are in the zero-valence state.

  19. Synthesis of supported bimetallic nanoparticles with controlled size and composition distributions for active site elucidation

    Energy Technology Data Exchange (ETDEWEB)

    Hakim, Sikander H.; Sener, Canan; Alba Rubio, Ana C.; Gostanian, Thomas M.; O' neill, Brandon J; Ribeiro, Fabio H.; Miller, Jeffrey T.; Dumesic, James A

    2015-08-01

    Elucidation of active sites in supported bimetallic catalysts is complicated by the high level of dispersity in the nanoparticle size and composition that is inherent in conventional methods of catalyst preparation. We present a synthesis strategy that leads to highly dispersed, bimetallic nanoparticles with uniform particle size and composition by means of controlled surface reactions. We demonstrate the synthesis of three systems, RhMo, PtMo, and RhRe, consisting of a highly reducible metal with an oxophilic promoter. These catalysts are characterized by FTIR, CO chemisorption, STEM/EDS, TPR, and XAS analysis. The catalytic properties of these bimetallic nanoparticles were probed for the selective CO hydrogenolysis of (hydroxymethyl)tetrahydropyran to produce 1,6 hexanediol. Based on the characterization results and reactivity trends, the active sites in the hydrogenolysis reaction are identified to be small ensembles of the more noble metal (Rh, Pt) adjacent to highly reduced moieties of the more oxophilic metal (Mo, Re).

  20. Corrosion Inhibitors for Aluminum.

    Science.gov (United States)

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  1. The anti corrosive design of structural metallic elements in buildings with large exploitation period; El diseno anticorrovio de elementos estructurales metalicos en edificaciones con periodos prolongados de explotacion

    Energy Technology Data Exchange (ETDEWEB)

    Avila Ayon, V.; Rodriguez Quesada, A. L.

    2009-07-01

    The corrosion deterioration in metallic structural elements, with the consistent loss of his physical and mechanical properties, is cause by errors in the design or fabrication, that allows the accumulation of humidity and contaminants in the surfaces, or acceleration zones of the corrosion processes, as the bimetalics pairs. The aggressiveness of the environment and the productive processes that develop in industrial installations, causes the apparition of premature failures that engage the edification use. The identification of design errors is the first step in the conservation of these structures. the elimination and made a project adapted to the proper installations conditions, is essential procedures to prolong the edification useful life with an optimum and rational use of the resources that destined for this end. The investigation is about the results obtained in the diagnostic and the conservation of industrial installment, with large exploitation periods, in which existed evidences of failures by corrosion, specifically to the elimination of errors of design. (Author) 12 refs.

  2. Direct decomposition of methane over SBA-15 supported Ni, Co and Fe based bimetallic catalysts

    Science.gov (United States)

    Pudukudy, Manoj; Yaakob, Zahira; Akmal, Zubair Shamsul

    2015-03-01

    Thermocatalytic decomposition of methane is an alternative route for the production of COx-free hydrogen and carbon nanomaterials. In this work, a set of novel Ni, Co and Fe based bimetallic catalysts supported over mesoporous SBA-15 was synthesized by a facile wet impregnation route, characterized for their structural, textural and reduction properties and were successfully used for the methane decomposition. The fine dispersion of metal oxide particles on the surface of SBA-15, without affecting its mesoporous texture was clearly shown in the low angle X-ray diffraction patterns and the transmission electron microscopy (TEM) images. The nitrogen sorption analysis showed the reduced specific surface area and pore volume of SBA-15, after metal loading due to the partial filling of hexagonal mesopores by metal species. The results of methane decomposition experiments indicated that all of the bimetallic catalysts were highly active and stable for the reaction at 700 °C even after 300 min of time on stream (TOS). However, a maximum hydrogen yield of ∼56% was observed for the NiCo/SBA-15 catalyst within 30 min of TOS. A high catalytic stability was shown by the CoFe/SBA-15 catalyst with 51% of hydrogen yield during the course of reaction. The catalytic stability of the bimetallic catalysts was attributed to the formation of bimetallic alloys. Moreover, the deposited carbons were found to be in the form of a new set of hollow multi-walled nanotubes with open tips, indicating a base growth mechanism, which confirm the selectivity of SBA-15 supported bimetallic catalysts for the formation of open tip carbon nanotubes. The Raman spectroscopic and thermogravimetric analysis of the deposited carbon nanotubes over the bimetallic catalysts indicated their higher graphitization degree and oxidation stability.

  3. Structure analysis of bimetallic Co-Au nanoparticles formed by sequential ion implantation

    Science.gov (United States)

    Chen, Hua-jian; Wang, Yu-hua; Zhang, Xiao-jian; Song, Shu-peng; chen, Hong; Zhang, Ke; Xiong, Zu-zhao; Ji, Ling-ling; Dai, Hou-mei; Wang, Deng-jing; Lu, Jian-duo; Wang, Ru-wu; Zheng, Li-rong

    2016-08-01

    Co-Au alloy Metallic nanoparticles (MNPs) are formed by sequential ion implantation of Co and Au into silica glass at room temperature. The ion ranges of Au ions implantation process have been displayed to show the ion distribution. We have used the atomic force microscopy (AFM) and transmission electron microscopy (TEM) to investigate the formation of bimetallic nanoparticles. The extended X-ray absorption fine structure (EXAFS) has been used to study the local structural information of bimetallic nanoparticles. With the increase of Au ion implantation, the local environments of Co ions are changed enormously. Hence, three oscillations, respectively, Co-O, Co-Co and Co-Au coordination are determined.

  4. Polyfunctional two- (2D) and three- (3D) dimensional oxalate bridged bimetallic magnets

    CERN Document Server

    Clément, R; Gruselle, M; Train, C

    2003-01-01

    We report major results concerning polyfunctional two- (2D) and three- (3D) dimensional oxalate bridged bimetallic magnets. As a consequence of their specific organization they are composed of an anionic sub-lattice and a cationic counter-part. These bimetallic polymers can accommodate various counter-cations possessing specific physical properties in addition to the magnetic ones resulting from the interactions between the metallic ions in the anionic sub-lattice. Thus, molecular magnets possessing paramagnetic, conductive and optical properties are presented in this review. Refs. 60 (author)

  5. A theoretical approach for estimation of ultimate size of bimetallic nanocomposites synthesized in microemulsion systems

    Science.gov (United States)

    Salabat, Alireza; Saydi, Hassan

    2012-12-01

    In this research a new idea for prediction of ultimate sizes of bimetallic nanocomposites synthesized in water-in-oil microemulsion system is proposed. In this method, by modifying Tabor Winterton approximation equation, an effective Hamaker constant was introduced. This effective Hamaker constant was applied in the van der Waals attractive interaction energy. The obtained effective van der Waals interaction energy was used as attractive contribution in the total interaction energy. The modified interaction energy was applied successfully to predict some bimetallic nanoparticles, at different mass fraction, synthesized in microemulsion system of dioctyl sodium sulfosuccinate (AOT)/isooctane.

  6. INTERACTION OF SULPHUR WITH BIMETALLIC SURFACES: EFFECTS OF STRUCTURAL, ELECTRONIC AND CHEMICAL PROPERTIES.

    Energy Technology Data Exchange (ETDEWEB)

    RODRIGUEZ,J.A.; HRBEK,J.

    2001-10-04

    In recent years, several new interesting phenomena have been discovered when studying the interaction of sulphur with bimetallic surfaces using the modern techniques of surface science. Very small amounts of sulphur can induce dramatic changes in the morphology of bimetallic surfaces. The electronic perturbations associated with the formation of a heteronuclear metal-metal bond affect the reactivity of the bonded metals toward sulphur. This can be a very important issue to consider when trying to minimize the negative effects of sulphur poisoning or dealing with the design of desulfurization catalysts.

  7. Modelling reinforcement corrosion in concrete

    DEFF Research Database (Denmark)

    Michel, Alexander; Geiker, Mette Rica; Stang, Henrik

    2012-01-01

    A physio-chemical model for the simulation of reinforcement corrosion in concrete struc-tures was developed. The model allows for simulation of initiation and subsequent propaga-tion of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold...... is reached causing the formation of anodic and cathodic regions along the reinforcement. Critical chloride thresholds, randomly distributed along the reinforcement sur-face, link the initiation and propagation phase of reinforcement corrosion. To demonstrate the potential use of the developed model......, a numerical example is pre-sented, that illustrates the formation of corrosion cells as well as propagation of corrosion in a reinforced concrete structure....

  8. Structure and properties of bimetallic titanium and vanadium oxide clusters.

    Science.gov (United States)

    Helmich, Benjamin; Sierka, Marek; Döbler, Jens; Sauer, Joachim

    2014-05-14

    By employing a genetic algorithm together with density functional theory (B3LYP), we investigate the most stable minimum structures of several bimetallic titanium and vanadium oxide clusters that contain four metal atoms. The following compositions are studied: VnTin-4O10(-) (n = 1-4), (TiO2)VOn(-) (n = 1-4), and (TiO2)VOn(+) (n = 1-3). Apart from (TiO2)3VO(-), vanadium oxo groups are always part of the most stable minimum structures when vanadium is present. Anti-ferromagnetic coupling lowers the energy substantially if spin centers are located at neighbored metal atoms rather than at distant oxygen radical sites. Vanadium-rich or oxygen-poor compositions prefer symmetric adamantane-like cage structures, some of which have already been proposed in a previous study. In contrast, vanadium-poor and oxygen-rich compositions show versatile structural motifs that cannot be intuitively derived from the symmetric cage motif. Particularly, for Ti4O10(-) there are several non-symmetric and distorted cages that have an up to 68 kJ mol(-1) lower energy than the symmetric adamantane-like cage structure. Nevertheless, for the adamantane-like cage the simulated infra-red spectrum (within the harmonic approximation) agrees best with the experimental vibrational spectrum. The oxidative power of the (TiO2)3VO3(-) and (TiO2)3VO2(+) clusters as measured by the energy of removing 1/2 O2 (297 and 227 kJ mol(-1), respectively) is less than that of the pure vanadium oxide clusters (V2O5)VO3(-) and (V2O5)VO2(+) (283 and 165 kJ mol(-1), respectively).

  9. Corrosion and Corrosion Control in Light Water Reactors

    Science.gov (United States)

    Gordon, Barry M.

    2013-08-01

    Serious corrosion problems have plagued the light water reactor (LWR) industry for decades. The complex corrosion mechanisms involved and the development of practical engineering solutions for their mitigation will be discussed in this article. After a brief overview of the basic designs of the boiling water reactor (BWR) and pressurized water reactor (PWR), emphasis will be placed on the general corrosion of LWR containments, flow-accelerated corrosion of carbon steel components, intergranular stress corrosion cracking (IGSCC) in BWRs, primary water stress corrosion cracking (PWSCC) in PWRs, and irradiation-assisted stress corrosion cracking (IASCC) in both systems. Finally, the corrosion future of both plants will be discussed as plants extend their period of operation for an additional 20 to 40 years.

  10. Controlled surface segregation leads to efficient coke-resistant nickel/platinum bimetallic catalysts for the dry reforming of methane

    KAUST Repository

    Li, Lidong

    2015-02-03

    Surface composition and structure are of vital importance for heterogeneous catalysts, especially for bimetallic catalysts, which often vary as a function of reaction conditions (known as surface segregation). The preparation of bimetallic catalysts with controlled metal surface composition and structure is very challenging. In this study, we synthesize a series of Ni/Pt bimetallic catalysts with controlled metal surface composition and structure using a method derived from surface organometallic chemistry. The evolution of the surface composition and structure of the obtained bimetallic catalysts under simulated reaction conditions is investigated by various techniques, which include CO-probe IR spectroscopy, high-angle annular dark-field scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, extended X-ray absorption fine structure analysis, X-ray absorption near-edge structure analysis, XRD, and X-ray photoelectron spectroscopy. It is demonstrated that the structure of the bimetallic catalyst is evolved from Pt monolayer island-modified Ni nanoparticles to core-shell bimetallic nanoparticles composed of a Ni-rich core and a Ni/Pt alloy shell upon thermal treatment. These catalysts are active for the dry reforming of methane, and their catalytic activities, stabilities, and carbon formation vary with their surface composition and structure. The reform of reforming: A series of alumina-supported Ni/Pt bimetallic nanoparticles (NPs) with controlled surface composition and structure are prepared. Remarkable surface segregation for these bimetallic NPs is observed upon thermal treatment. These bimetallic NPs are active catalysts for CO2 reforming of CH4, and their catalytic activities, stabilities, and carbon formation vary with their surface composition and structure.

  11. Corrosion testing using isotopes

    Science.gov (United States)

    Hohorst, Frederick A.

    1995-12-05

    A method for determining the corrosion behavior of a material with respect to a medium in contact with the material by: implanting a substantially chemically inert gas in a matrix so that corrosion experienced by the material causes the inert gas to enter the medium; placing the medium in contact with the material; and measuring the amount of inert gas which enters the medium. A test sample of a material whose resistance to corrosion by a medium is to be tested, composed of: a body of the material, which body has a surface to be contacted by the medium; and a substantially chemically inert gas implanted into the body to a depth below the surface. A test sample of a material whose resistance to corrosion by a medium is to be tested, composed of: a substrate of material which is easily corroded by the medium, the substrate having a surface; a substantially chemically inert gas implanted into the substrate; and a sheet of the material whose resistance to corrosion is to be tested, the sheet being disposed against the surface of the substrate and having a defined thickness.

  12. Severe Environmental Corrosion Erosion Facility

    Data.gov (United States)

    Federal Laboratory Consortium — NETL’s Severe Environment Corrosion Erosion Facility in Albany, OR, allows researchers to safely examine the performance of materials in highly corrosive or erosive...

  13. ELECTRONIC AND CHEMICAL PROPERTIES OF PD IN BIMETALLIC SYSTEMS: HOW MUCH DO WE KNOW ABOUT HETERONUCLEAR METAL-METAL BONDING?

    Energy Technology Data Exchange (ETDEWEB)

    RODRIGUEZ,J.A.

    2001-09-27

    The experimental and theoretical studies described above illustrate the complex nature of the heteronuclear metal-metal bond. In many cases, bimetallic bonding induces a significant redistribution of charge around the bonded metals. This redistribution of charge is usually linked to the strength of the bimetallic bond, affects the position of the core and valence levels of the metals, and can determine the chemical reactivity of the system under study. New concepts are emerging [22,23,34,36] and eventually the coupling of experiment and theory can be useful for designing more efficient bimetallic catalysts [98,106,107].

  14. Theoretical studies of the work functions of Pd-based bimetallic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Zhao-Bin; Wu, Feng; Wang, Yue-Chao; Jiang, Hong, E-mail: jianghchem@pku.edu.cn [Beijing National Laboratory of Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2015-06-07

    Work functions of Pd-based bimetallic surfaces, including mainly M/Pd(111), Pd/M, and Pd/M/Pd(111) (M = 4d transition metals, Cu, Au, and Pt), are studied using density functional theory. We find that the work function of these bimetallic surfaces is significantly different from that of parent metals. Careful analysis based on Bader charges and electron density difference indicates that the variation of the work function in bimetallic surfaces can be mainly attributed to two factors: (1) charge transfer between the two different metals as a result of their different intrinsic electronegativity, and (2) the charge redistribution induced by chemical bonding between the top two layers. The first factor can be related to the contact potential, i.e., the work function difference between two metals in direct contact, and the second factor can be well characterized by the change in the charge spilling out into vacuum. We also find that the variation in the work functions of Pd/M/Pd(111) surfaces correlates very well with the variation of the d-band center of the surface Pd atom. The findings in this work can be used to provide general guidelines to design new bimetallic surfaces with desired electronic properties.

  15. EXAFS as a tool to interrogate the size and shape of mono and bimetallic catalyst nanoparticles

    NARCIS (Netherlands)

    Beale, A.M.; Weckhuysen, B.M.

    2013-01-01

    The influence of atom packing and the geometric arrangement of atoms on the coordination number(s) and resultant simulated EXAFS spectra for face centrered cubic (fcc), hexagonal close packed (hcp) and body centered cubic (bcc) monometallic structures and fcc bimetallic structures, has been examined

  16. Synthesis and exceptional thermal stability of Mg-based bimetallic nanoparticles during hydrogenation

    NARCIS (Netherlands)

    Krishnan, Gopi; Negrea, Raluca F.; Ghica, Corneliu; ten Brink, Gert H.; Kooi, Bart J.; Palasantzas, Georgios

    2014-01-01

    Here we report the extraordinary thermal stability of Mg rich bimetallic nanoparticles (NPs), which is important for hydrogen storage technology. The enhanced NP stability is accomplished because of two critical improvements: (i) no void development within NPs (nanoscale Kirkendall effect) during th

  17. Fundamental studies of hydrogen interaction with supported meta and bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bhatia, S.

    1993-12-07

    The thesis is divided into 3 parts: interaction of H with silica supported Ru catalysts (high pressure in situ NMR), in situ NMR study of H interaction with supported Ru-group IB bimetallic catalysts, and in-situ NMR study of H effects on silica-supported Pt, Rh and Ru catalysts.

  18. Synthesis of bimetallic gold-silver alloy nanoclusters by simple mortar grinding.

    Science.gov (United States)

    Murugadoss, Arumugam; Kai, Noriko; Sakurai, Hidehiro

    2012-02-21

    A macroscale quantity of bimetallic Au-Ag alloy nanoclusters was achieved through sequential reduction by simple mortar grinding. The chitosan biopolymer was used as both a stabilizing and reducing agent. These nanoclusters exhibit excellent catalytic activity toward the reduction of 4-nitrophenol.

  19. Optical properties of multilayer bimetallic films obtained by laser deposition of colloidal particles

    Science.gov (United States)

    Antipov, A.; Arakelian, S.; Vartanyan, T.; Gerke, M.; Istratov, A.; Kutrovskaya, S.; Kucherik, A.; Osipov, A.

    2016-11-01

    The optical properties of multilayer bimetallic films composed of silver and gold nanoparticles have been investigated. The dependence of the transmission spectra of the films on their morphology is demonstrated. A finite-difference time-domain (FDTD) simulation has confirmed that there is a dependence of the transmission spectra on the average distance between particles and the number of deposited layers.

  20. Non-Precious Bimetallic Catalysts for Selective Dehydrogenation of an Organic Chemical Hydride System

    KAUST Repository

    Shaikh Ali, Anaam

    2015-07-06

    Methylcyclohexane (MCH)-Toluene (TOL) chemical hydride cycles as a hydrogen carrier system is successful with the selective dehydrogenation reaction of MCH to TOL, which has been achieved only using precious Pt-based catalysts. Herein, we report improved selectivity using non-precious metal nickel-based bimetallic catalysts, where the second metal occupies the unselective step sites.

  1. Exceptional methanol electro-oxidation activity by bimetallic concave and dendritic Pt-Cu nanocrystals catalysts

    Science.gov (United States)

    Wang, Ying-Xia; Zhou, Hui-Jing; Sun, Ping-Chuan; Chen, Tie-Hong

    2014-01-01

    PtCux (x = 1, 2 and 3) bimetallic nanocrystals with concave surface and dendritic morphology were prepared and used as electrocatalysts in methanol oxidation reaction (MOR) for polymer electrolyte membrane fuel cells. The bimetallic nanocrystals were synthesized via one-pot co-reduction of H2PtCl6 and Cu(acac)2 by oleylamine and polyvinyl pyrrolidone (PVP) in an autoclave at 180 °C. The concave dendritic bimetallic nanostructure consisted of a core rich in Cu and nanodendrites rich in Pt, which was formed via galvanic replacement of Cu by Pt. It was found that PVP played an important role in initiating, facilitating, and directing the replacement reaction. The electrochemical properties of the PtCux were characterized by cyclic voltammetry (CV) and chronoamperometry (CA). The concave dendritic PtCu2/C nanocrystals exhibited exceptionally high activity and strong poisoning resistance in MOR. At 0.75 V (vs. reversible hydrogen electrode, RHE) the mass activity and specific activity of PtCu2/C were 3.3 and 4.1 times higher than those of the commercial Pt/C catalysts, respectively. The enhanced catalytic activity could be attributed to the unique concave dendritic morphology of the bimetallic nanocrystals.

  2. Corrosion-resistant metal surfaces

    Science.gov (United States)

    Sugama, Toshifumi

    2009-03-24

    The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

  3. Corrosion-resistant metallic coatings

    OpenAIRE

    F. Presuel-Moreno; M.A. Jakab; N. Tailleart; Goldman, M.; J. R. Scully

    2008-01-01

    We describe recent computational and experimental studies on the corrosion properties of metallic coatings that can be tailored (tuned) to deliver up to three corrosion-inhibiting functions to an underlying substrate. Attributes are tuned by a selection of alloy compositions and nanostructures, ideally in alloy systems that offer flexibility of choice to optimize the corrosion-resisting properties. An amorphous Al-based coating is tuned for corrosion protection by on-demand release of ionic i...

  4. Structural disordering of de-alloyed Pt bimetallic nanocatalysts

    DEFF Research Database (Denmark)

    Spanos, Ioannis; Dideriksen, Knud; Kirkensgaard, Jacob Judas Kain;

    2015-01-01

    nanoparticles almost completely de-alloy during acid leaching, i.e. under reaction conditions in a fuel cell. To scrutinize the resulting particle structure after de-alloying we used pair distribution function (PDF) analysis and X-ray diffraction (XRD) gaining insight into the structural disorder and its...... dependence on the initial metal composition. Our results suggest that not only the ORR activity, but also the corrosion resistance of the synthesized NPs, are dependent on the structural disorder resulting from the de-alloying process....

  5. Solving A Corrosion Problem

    Science.gov (United States)

    1979-01-01

    The corrosion problem, it turned out, stemmed from the process called electrolysis. When two different metals are in contact, an electrical potential is set up between them; when the metals are surrounded by an electrolyte, or a conducting medium, the resulting reaction causes corrosion, often very rapid corrosion. In this case the different metals were the copper grounding system and the ferry's aluminum hull; the dockside salt water in which the hull was resting served as the electrolyte. After identifying the source of the trouble, the Ames engineer provided a solution: a new wire-and-rod grounding system made of aluminum like the ferry's hull so there would no longer be dissimilar metals in contact. Ames research on the matter disclosed that the problem was not unique to the Golden Gate ferries. It is being experienced by many pleasure boat operators who are probably as puzzled about it as was the Golden Gate Transit Authority.

  6. Plastics for corrosion inhibition

    CERN Document Server

    Goldade, Victor A; Makarevich, Anna V; Kestelman, Vladimir N

    2005-01-01

    The development of polymer composites containing inhibitors of metal corrosion is an important endeavour in modern materials science and technology. Corrosion inhibitors can be located in a polymer matrix in the solid, liquid or gaseous phase. This book details the thermodynamic principles for selecting these components, their compatibility and their effectiveness. The various mechanisms of metal protection – barrier, inhibiting and electromechanical – are considered, as are the conflicting requirements placed on the structure of the combined material. Two main classes of inhibited materials (structural and films/coatings) are described in detail. Examples are given of structural plastics used in friction units subjected to mechano-chemical wear and of polymer films/coatings for protecting metal objects against corrosion.

  7. Thin film corrosion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Raut, M.K.

    1980-06-01

    Corrosion of chromium/gold (Cr/Au) thin films during photolithography, prebond etching, and cleaning was evaluated. Vapors of chromium etchant, tantalum nitride etchant, and especially gold etchant were found to corrosively attack chromium/gold films. A palladium metal barrier between the gold and chromium layers was found to reduce the corrosion from gold etchant.

  8. Corrosion resistant PEM fuel cell

    Science.gov (United States)

    Fronk, Matthew Howard; Borup, Rodney Lynn; Hulett, Jay S.; Brady, Brian K.; Cunningham, Kevin M.

    2002-01-01

    A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

  9. Thermal decomposition of mono- and bimetallic magnesium amidoborane complexes.

    Science.gov (United States)

    Spielmann, Jan; Piesik, Dirk F-J; Harder, Sjoerd

    2010-07-26

    Complexes of the type [(DIPPnacnac)MgNH(R)BH(3)] have been prepared (DIPPnacnac=CH{(CMe)(2,6-iPr(2)C(6)H(3)N)}(2)). The following substituents R have been used: H, Me, iPr, DIPP (DIPP=2,6-diisopropylphenyl). Complexes [(DIPPnac- nac)MgNH(2)BH(3)].THF, [{(DIPPnac- nac)MgNH(iPr)BH(3)}(2)] and [(DIPPnacnac)MgNH(DIPP)BH(3)] were structurally characterised. The Mg amidoborane complexes decompose at a significantly higher temperature (90-110 degrees C) than the corresponding Ca amidoborane complexes (20-110 degrees C). The complexes with the smaller R substituents (H, Me) gave a mixture of decomposition products of which one could be structurally characterised as [{(DIPPnacnac)Mg}(2)(H(3)B-NMe-BH-NMe)].THF. [{(DIPP- nacnac)MgNH(iPr)BH(3)}(2)] cleanly decomposed to [(DIPPnacnac)MgH], which was characterised as a dimeric THF adduct. The amidoborane complex with the larger DIPP-substituent decomposed into a borylamide complex [(DIPPnacnac)MgN(DIPP)BH(2)], which was structurally characterised as its THF adduct. Bimetallic Mg amidoborane complexes decompose at lower temperatures (60-90 degrees C) and show a different decomposition pathway. The dinuclear Mg amidoborane complexes presented here are based on DIPPnacnac units that are either directly coupled through N-N bonding (abbreviated NN) or through a 2,6-pyridylene bridge (abbreviated PYR). Crystal structures of [PYR-{Mg(nBu)}(2)], [PYR-{MgNH(iPr)BH(3)}(2)], [NN-{MgNH(iPr)BH(3)}(2)]THF and the decomposition products [PYR-Mg(2)(iPrN-BH-iPrN-BH(3))] and [NN-Mg(2)(iPrN-BH-iPrN-BH(3))].THF are presented. The following conclusions can be drawn from these studies: i) The first step in the decomposition of a metal amidoborane complex is beta-hydride elimination, which results in formation of a metal hydride complex and R(H)N=BH(2), ii) depending on the nature of the metal, the metal hydride is either stable and can be isolated or it reacts further, iii) amidoborane anions with small R substituents decompose into the dianionic

  10. Phytogenic silver, gold, and bimetallic nanoparticles as novel antitubercular agents

    Directory of Open Access Journals (Sweden)

    Singh R

    2016-05-01

    Full Text Available Richa Singh,1 Laxman Nawale,2 Manisha Arkile,2 Sweety Wadhwani,1 Utkarsha Shedbalkar,1 Snehal Chopade,1 Dhiman Sarkar,2 Balu Ananda Chopade1,3 1Department of Microbiology, Savitribai Phule Pune University, 2Combichem-Bioresource Center, Organic Chemistry Division, National Chemical Laboratory, Pune, 3Dr Babasaheb Ambedkar Marathwada University, Aurangabad, Maharashtra, India Purpose: Multi- and extensively drug-resistant tuberculosis (TB is a global threat to human health. It requires immediate action to seek new antitubercular compounds and devise alternate strategies. Nanomaterials, in the present scenario, have opened new avenues in medicine, diagnosis, and therapeutics. In view of this, the current study aims to determine the efficacy of phytogenic metal nanoparticles to inhibit mycobacteria. Methods: Silver (AgNPs, gold (AuNPs, and gold–silver bimetallic (Au–AgNPs nanoparticles synthesized from medicinal plants, such as Barleria prionitis, Plumbago zeylanica, and Syzygium cumini, were tested against Mycobacterium tuberculosis and M. bovis BCG. In vitro and ex vivo macrophage infection model assays were designed to determine minimum inhibitory concentration (MIC and half maximal inhibitory concentration of nanoparticles. Microscopic analyses were carried out to demonstrate intracellular uptake of nanoparticles in macrophages. Besides this, biocompatibility, specificity, and selectivity of nanoparticles were also established with respect to human cell lines. Results: Au–AgNPs exhibited highest antitubercular activity, with MIC of <2.56 µg/mL, followed by AgNPs. AuNPs did not show such activity at concentrations of up to 100 µg/mL. In vitro and ex vivo macrophage infection model assays revealed the inhibition of both active and dormant stage mycobacteria on exposure to Au–AgNPs. These nanoparticles were capable of entering macrophage cells and exhibited up to 45% cytotoxicity at 30 µg/mL (ten times MIC concentration after 48 hours

  11. On the performance of surface plasmon resonance based fibre optic sensor with different bimetallic nanoparticle alloy combinations

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anuj K; Mohr, Gerhard J [Institute of Physical Chemistry, Friedrich-Schiller University, Lessingstrasse 10, 07743 Jena (Germany)], E-mail: anuj.sharma@uni-jena.de

    2008-03-07

    In this work, we have investigated the capability of different bimetallic nanoparticle alloy combinations to be used in fibre optic sensors based on the technique of surface plasmon resonance. The metals considered for this analysis are silver, gold, copper and aluminium. The performance of the sensor with different bimetallic nanoparticle alloy combinations is evaluated and compared numerically. The performance is analysed in terms of three parameters: sensitivity, signal-to-noise ratio (SNR) and operating range for the sensing layer refractive index values. On the basis of the comparison and some logistic criteria, the best possible bimetallic alloy combinations along with a requisite alloy composition ratio are predicted. The bimetallic nanoparticle alloy combination is capable of simultaneously providing larger values of sensitivity, SNR and operating range, which is not possible with any single metallic nanoparticle layer.

  12. Corrosion risks with polyethylene pipes in district cooling systems; Korrosionsrisker vid anvaendning av polyetenroer i fjaerrkylesystem

    Energy Technology Data Exchange (ETDEWEB)

    Vinka, Tor-Gunnar; Almquist, Joergen; Gubner, Rolf [Swedish Corrosion Inst., Stockholm (Sweden)

    2005-06-01

    Field exposures of carbon steel and stainless steel test cylinders have been made in the district cooling system at Affaersverken Energi AB, Karlskrona, Sweden, as well as determinations of the amount of dissolved oxygen in the district cooling water. In the district cooling system tubes of polyethylene, carbon steel and stainless steel SS 2343 according to Swedish standard SS 14 23 43 are used. Karlskrona's drinking water, without deaeration, is used in the district cooling system. The polyethylene tubes with pressure number PN 10 are placed underground. The content of dissolved oxygen was very low in Karlskrona both before and after a period of 19 days with elevated oxygen content. During these 19 days the content of dissolved oxygen in the system increased without any apparent cause. The highest recorded oxygen content was 3.4 mg O{sub 2}/l. There are no obvious explanations for the increase of oxygen in the system. However, transport of oxygen into the system through the polyethylene tubes can be excluded as the source of the entering oxygen. The corrosion rate that was determined for freely exposed carbon steel in the district heating water in Karlskrona was low, 5 {mu}m/year. The corrosion attack was of a uniform nature (general corrosion) and there were no local corrosion attacks on the carbon steel cylinders. On connecting the carbon steel with stainless steel SS 23 43 with an area ratio of 1:1 the corrosion rate of the carbon steel increased by 2-3 times as compared to free exposure without electrical connection. On the stainless steel SS 2343 there was no corrosion damage either on the freely exposed stainless steel or on stainless steel that was connected to carbon steel. There were no signs of pitting corrosion or crevice corrosion on the stainless steel cylinders. The main corrosion risk for carbon steel at an elevated content of dissolved oxygen is bimetallic corrosion (galvanic corrosion) between carbon steel and copper and copper alloys, or

  13. Corrosion risks with polyethylene pipes in district cooling systems; Korrosionsrisker vid anvaendning av polyetenroer i fjaerrkylesystem

    Energy Technology Data Exchange (ETDEWEB)

    Vinka, Tor-Gunnar; Almquist, Joergen; Gubner, Rolf [Swedish Corrosion Inst., Stockholm (Sweden)

    2005-06-01

    Field exposures of carbon steel and stainless steel test cylinders have been made in the district cooling system at Affaersverken Energi AB, Karlskrona, Sweden, as well as determinations of the amount of dissolved oxygen in the district cooling water. In the district cooling system tubes of polyethylene, carbon steel and stainless steel SS 2343 according to Swedish standard SS 14 23 43 are used. Karlskrona's drinking water, without deaeration, is used in the district cooling system. The polyethylene tubes with pressure number PN 10 are placed underground. The content of dissolved oxygen was very low in Karlskrona both before and after a period of 19 days with elevated oxygen content. During these 19 days the content of dissolved oxygen in the system increased without any apparent cause. The highest recorded oxygen content was 3.4 mg O{sub 2}/l. There are no obvious explanations for the increase of oxygen in the system. However, transport of oxygen into the system through the polyethylene tubes can be excluded as the source of the entering oxygen. The corrosion rate that was determined for freely exposed carbon steel in the district heating water in Karlskrona was low, 5 {mu}m/year. The corrosion attack was of a uniform nature (general corrosion) and there were no local corrosion attacks on the carbon steel cylinders. On connecting the carbon steel with stainless steel SS 23 43 with an area ratio of 1:1 the corrosion rate of the carbon steel increased by 2-3 times as compared to free exposure without electrical connection. On the stainless steel SS 2343 there was no corrosion damage either on the freely exposed stainless steel or on stainless steel that was connected to carbon steel. There were no signs of pitting corrosion or crevice corrosion on the stainless steel cylinders. The main corrosion risk for carbon steel at an elevated content of dissolved oxygen is bimetallic corrosion (galvanic corrosion) between carbon steel and copper and copper alloys, or

  14. Corrosion protection by anaerobiosis.

    Science.gov (United States)

    Volkland, H P; Harms, H; Wanner; Zehnder, A J

    2001-01-01

    Biofilm-forming bacteria can protect mild (unalloyed) steel from corrosion. Mild steel coupons incubated with Rhodoccocus sp. strain C125 and Pseudomonas putida mt2 in an aerobic phosphate-buffered medium containing benzoate as carbon and energy source, underwent a surface reaction leading to the formation of a corrosion-inhibiting vivianite layer [Fe3(PO4)2]. Electrochemical potential (E) measurements allowed us to follow the buildup of the vivianite cover. The presence of sufficient metabolically active bacteria at the steel surface resulted in an E decrease to -510 mV, the potential of free iron, and a continuous release of ferrous iron. Part of the dissolved iron precipitated as vivianite in a compact layer of two to three microns in thickness. This layer prevented corrosion of mild steel for over two weeks, even in a highly corrosive medium. A concentration of 20 mM phosphate in the medium was found to be a prerequisite for the formation of the vivianite layer.

  15. Smart Coatings for Corrosion Protection

    Science.gov (United States)

    Calle, Luz Marina; Li, Wendy; Buhrow, Jerry W.; Johnsey, Marissa N.

    2016-01-01

    Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. It is essential to detect corrosion when it occurs, and preferably at its early stage, so that action can be taken to avoid structural damage or loss of function. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it.

  16. Bimetallic gold-silver nanoplate array as a highly active SERS substrate for detection of streptavidin/biotin assemblies.

    Science.gov (United States)

    Bi, Liyan; Dong, Jian; Xie, Wei; Lu, Wenbo; Tong, Wei; Tao, Lin; Qian, Weiping

    2013-12-17

    The silver-modified gold nanoplate arrays as bimetallic surface-enhanced Raman scattering (SERS) substrates were optimized for the surface-enhanced Raman detection of streptavidin/biotin monolayer assemblies. The bimetallic gold-silver nanoplate arrays were fabricated by coating silver nanoparticles uniformly on the gold nanoplate arrays. Depending on silver nanoparticle coating, the localized surface plasmon resonance (LSPR) peak of the bimetallic gold-silver nanoplate arrays blue-shifted and broadened significantly. The common probe molecule, Niel Blue A sulfate (NBA) was used for testing the SERS activity of the bimetallic gold-silver nanoplate arrays. The SERS intensity increased with the silver nanoparticle coating, due to a large number of hot spots and nanoparticle interfaces. The platforms were tested against a monolayer of streptavidin functionalized over the bimetallic gold-silver nanoplate arrays showing that good quality spectra could be acquired with a short acquisition time. The supramolecular interaction between streptavidin (strep) and biotin showed subsequent modification of Raman spectra that implied a change of the secondary structure of the host biomolecule. And the detection concentration for biotin by this method was as low as 1.0 nM. The enhanced SERS performance of such bimetallic gold-silver nanoplate arrays could spur further interest in the integration of highly sensitive biosensors for rapid, nondestructive, and quantitative bioanalysis, particularly in microfluidics.

  17. Surface plasmon resonance sensing of a biomarker of Alzheimer disease in an intensity measurement mode with a bimetallic chip

    Science.gov (United States)

    Kim, Hyung Jin; Sohn, Young-Soo; Kim, Chang-duk; Jang, Dae-ho

    2016-09-01

    A surface plasmon resonance (SPR) sensor system with a bimetallic chip has been utilized to sense the very low concentration of amyloid-beta (A β)(1-42) by measurement of the reflectance variation. The bimetallic chip was comprised of Au (10 nm) and Ag (40 nm) on Cr (2 nm)-coated BK-7 glass substrate. Protein A was used to efficiently immobilize the antibody of A β(1-42) on the surface of the bimetallic chip. The reflectance curve of the bimetallic chip represented a narrower linewidth compared to that of the conventional gold (Au) chip. The SPR sensor using the bimetallic chip in the intensity interrogation mode acquired the response of A β(1-42) at concentrations of 250, 500, 750 and 1,000 pg/ml. The calibration plot showed a linear relationship between the mean reflectance variation and the A β(1-42) concentration. The results proved that the SPR sensor system with the bimetallic chip in the intensity interrogation mode can successfully detect various concentrations of A β(1-42), including critical concentration, to help diagnose Alzheimer's disease.

  18. Controlled Surface Segregation Leads to Efficient Coke-Resistant Nickel/Platinum Bimetallic Catalysts for the Dry Reforming of Methane

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lidong [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Zhou, Lu [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Ould-Chikh, Samy [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Anjum, Dalaver H. [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Kanoun, Mohammed B. [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Scaranto, Jessica [SABIC Corporate Research and Innovation Center, Thuwal (Saudi Arabia); Hedhili, Mohamed N. [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Khalid, Syed [Brookhaven National Lab. (BNL), Upton, NY (United States); Laveille, Paco V. [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); D' Souza, Lawrence [SABIC Corporate Research and Innovation Center, Thuwal (Saudi Arabia); Clo, Alain [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia); Basset, Jean-Marie [King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia)

    2015-02-03

    The surface composition and structure are of vital importance for heterogeneous catalysts, especially for bimetallic catalysts, which often vary as a function of reaction conditions (known as surface segregation). The preparation of bimetallic catalysts with controlled metal surface composition and structure is very challenging. In this study, we synthesize a series of Ni/Pt bimetallic catalysts with controlled metal surface composition and structure using a method derived from surface organometallic chemistry. Moreover, the evolution of the surface composition and structure of the obtained bimetallic catalysts under simulated reaction conditions is investigated by various techniques, which include CO-probe IR spectroscopy, high-angle annular dark-field scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, extended X-ray absorption fine structure analysis, X-ray absorption near-edge structure analysis, XRD, and X-ray photoelectron spectroscopy. It is demonstrated that the structure of the bimetallic catalyst is evolved from Pt monolayer island-modified Ni nanoparticles to core–shell bimetallic nanoparticles composed of a Ni-rich core and a Ni/Pt alloy shell upon thermal treatment. The catalysts are active for the dry reforming of methane, and their catalytic activities, stabilities, and carbon formation vary with their surface composition and structure.

  19. Noble metal-based bimetallic nanoparticles: the effect of the structure on the optical, catalytic and photocatalytic properties.

    Science.gov (United States)

    Zaleska-Medynska, Adriana; Marchelek, Martyna; Diak, Magdalena; Grabowska, Ewelina

    2016-03-01

    Nanoparticles composed of two different metal elements show novel electronic, optical, catalytic or photocatalytic properties from monometallic nanoparticles. Bimetallic nanoparticles could show not only the combination of the properties related to the presence of two individual metals, but also new properties due to a synergy between two metals. The structure of bimetallic nanoparticles can be oriented in random alloy, alloy with an intermetallic compound, cluster-in-cluster or core-shell structures and is strictly dependent on the relative strengths of metal-metal bond, surface energies of bulk elements, relative atomic sizes, preparation method and conditions, etc. In this review, selected properties, such as structure, optical, catalytic and photocatalytic of noble metals-based bimetallic nanoparticles, are discussed together with preparation routes. The effects of preparation method conditions as well as metal properties on the final structure of bimetallic nanoparticles (from alloy to core-shell structure) are followed. The role of bimetallic nanoparticles in heterogeneous catalysis and photocatalysis are discussed. Furthermore, structure and optical characteristics of bimetallic nanoparticles are described in relation to the some features of monometallic NPs. Such a complex approach allows to systematize knowledge and to identify the future direction of research.

  20. Dechlorination of disinfection by-product monochloroacetic acid in drinking water by nanoscale palladized iron bimetallic particle

    Institute of Scientific and Technical Information of China (English)

    CHEN Chao; WANG Xiangyu; CHANG Ying; LIU Huiling

    2008-01-01

    Nanoscale palladized iron (Pd/Fe) bimetallic particles were prepared by reductive deposition method. The particles were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM), transmission electron microscope (TEM), and Brunauer-Emmett-Teller-nitrogen (BET-N2) method. Data obtained from those methods indicated that nanoscale Pd/Fe bimetallic particles contained α-Fe0. Detected Pd to Fe ratio by weight (PFRW) was close to theoretical PFRW. Spherical granules with diameter of 47±11.5 nm connected with one another to form chains and the chains composed nanoscale Pd/Fe bimetallic particles. Specific surface area of particles was 51 m2/g. Factors, such as species of reductants, PFRW, dose of nanoscale Pd/Fe bimetallic particles added into solutions, solution initial pH, and a variety of solvents were studied. Dechlorination effect of monochloroacetic acid (MCAA) by different reductants followed the trend: nanoscale Pd/Fe bimetallic particles of 0.182% PFRW > nanoscale Fe > reductive Fe. When PFRW was lower than 0.083%, increasing PFRW would increase dechlorination efficiency (DE) of MCAA. But when the PFRW was higher than 0.083%, increasing PFRW caused decrease in DE. Adding more nanoscale Pd/Fe bimetallic particles to solution would enhance DE. The DE of MCAA decreased as initial pH of solution increased.

  1. Effect of coating mild steel with CNTs on its mechanical properties and corrosion behaviour in acidic medium

    Science.gov (United States)

    Abdulmalik Abdulrahaman, Mahmud; Kamaldeeen Abubakre, Oladiran; Ambali Abdulkareem, Saka; Oladejo Tijani, Jimoh; Aliyu, Ahmed; Afolabi, Ayo Samuel

    2017-03-01

    The study investigated the mechanical properties and corrosion behaviour of mild steel coated with carbon nanotubes at different coating conditions. Multi-walled carbon nanotubes (MWCNTs) were synthesized via the conventional chemical vapour deposition reaction using bimetallic Fe–Ni catalyst supported on kaolin, with acetylene gas as a carbon source. The HRSEM/HRTEM analysis of the purified carbon materials revealed significant reduction in the diameters of the purified MWCNT bundles from 50 nm to 2 nm and was attributed to the ultrasonication assisted dispersion with surfactant (gum arabic) employed in purification process. The network of the dispersed MWCNTs was coated onto the surfaces of mild steel samples, and as the coating temperature and holding time increased, the coating thickness reduced. The mechanical properties (tensile strength, yield strength, hardness value) of the coated steel samples increased with increase in coating temperature and holding time. Comparing the different coating conditions, coated mild steels at the temperature of 950 °C for 90 min holding time exhibited high hardness, yield strength and tensile strength values compared to others. The corrosion current and corrosion rate of the coated mild steel samples decreased with increase in holding time and coating temperature. The lowest corrosion rate was observed on sample coated at 950 °C for 90 min.

  2. Scanning reference electrode techniques in localized corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Isaacs, H.S.; Vyas, B.

    1979-04-01

    The principles, advantages, and implementations of scanning reference electrode techniques are reviewed. Data related to pitting, intergranular corrosion, welds and stress corrosion cracking are presented. The technique locates the position of localized corrosion and can be used to monitor the development of corrosion and changes in the corrosion rate under a wide range of conditions.

  3. Corrosion Evaluation and Corrosion Control of Steam Generators

    Energy Technology Data Exchange (ETDEWEB)

    Maeng, W. Y.; Kim, U. C.; Sung, K. W.; Na, J. W.; Lee, Y. H.; Lee, D. H.; Kim, K. M

    2008-06-15

    Corrosion damage significantly influences the integrity and efficiency of steam generator. Corrosion problems of steam generator are unsolved issues until now even though much effort is made around world. Especially the stress corrosion cracking of heat exchange materials is the first issue to be solved. The corrosion protection method of steam generator is important and urgent for the guarantee of nuclear plant's integrity. The objectives of this study are 1) to evaluate the corrosion properties of steam generator materials, 2) to optimize the water chemistry of steam generator and 3) to develop the corrosion protection method of primary and secondary sides of steam generator. The results will be reflected to the water chemistry guideline for improving the integrity and efficiency of steam generator in domestic power plants.

  4. The adsorption and decomposition of methane on Fe/Cu(110)bimetallic surface

    Institute of Scientific and Technical Information of China (English)

    鲍世宁; 范朝阳; 李海洋; 徐亚伯

    1995-01-01

    The adsorption and decomposition of methane on Fe/Cu(110) bimetallic surface have been studied by HREELS and ARUPS. The results show that the activation energy of dissociative chemisorption for methane is reduced obviously by preadsorption of iron on copper surface. The chemisorption probability of methane is so high on Fe/Cu(110) bimetallic surface that chemisorption of methane can be observed at room temperature and low pressure. When the iron coverage is lower than 1 ML, the chemisorption probability increases linearly with increasing iron coverage. After the iron coverage is beyond 1 ML(<2ML) the probability continues increasing. The iron atom with disordered structure can offer the site of dissociative chemisorption to methane too. A hydroformyl species is formed through interaction between methane and the preadsorbed oxygen atoms. The reaction enhances the dissociative chemisorption of methane on the surface.

  5. Synthesis, characterization, and growth simulations of Cu–Pt bimetallic nanoclusters

    Directory of Open Access Journals (Sweden)

    Subarna Khanal

    2014-08-01

    Full Text Available Highly monodispersed Cu–Pt bimetallic nanoclusters were synthesized by a facile synthesis approach. Analysis of transmission electron microscopy (TEM and spherical aberration (Cs-corrected scanning transmission electron microscopy (STEM images shows that the average diameter of the Cu–Pt nanoclusters is 3.0 ± 1.0 nm. The high angle annular dark field (HAADF-STEM images, intensity profiles, and energy dispersive X-ray spectroscopy (EDX line scans, allowed us to study the distribution of Cu and Pt with atomistic resolution, finding that Pt is embedded randomly in the Cu lattice. A novel simulation method is applied to study the growth mechanism, which shows the formation of alloy structures in good agreement with the experimental evidence. The findings give insight into the formation mechanism of the nanosized Cu–Pt bimetallic catalysts.

  6. A Highly Efifcient and Selective Water-Soluble Bimetallic Catalyst for Hydrogenation of Chloronitrobenzene to Chloroaniline

    Institute of Scientific and Technical Information of China (English)

    Zhou Yafen; Yang Wenjuan; Zhou Limei; Wang Manman; Ma Xiaoyan

    2015-01-01

    Selective hydrogenation of chloronitrobenzene (CNB) to chloroaniline (CAN) catalyzed by water-soluble Ru/Pt bimetallic catalyst in an aqueous-organic biphasic system was studied. It was found that the catalytic activity increased ob-viously due to the addition of platinum. Ru/Pt bimetallic catalysts exhibited a strong synergistic effect when the molar ratio of Pt was in the range of 5%—80%. Under the mild conditions including a temperature of 25℃, a hydrogen pressure of 1.0 MPa and a Pt molar ratio of 20%, the conversion of p-chloronitrobenzene (p-CNB) reached 99.9%, with the selectivity to p-chloroaniline (p-CAN) equating to 99.4%. The Ru/Pt catalyst also showed high activity and selectivity for the hydrogena-tion of other chloro-and dichloro-nitrobenzenes with different substituted positions. In addition, the catalyst can be recycled ifve times without signiifcant loss of activity.

  7. Structure and atomic vibrations in bimetallic Ni13 - n Al n clusters

    Science.gov (United States)

    Rusina, G. G.; Borisova, S. D.; Chulkov, E. V.

    2015-04-01

    The binding energy, equilibrium geometry, and vibration frequencies in bimetallic clusters Ni13 - n Al n ( n = 0-13) have been calculated using the embedded atom method potentials. It has been shown that the icosahedral structure is the most stable in monoatomic and bimetallic clusters. A tendency of Al atoms to segregate on the cluster surface has been revealed in agreement with the experimental data. The calculations of the atomic vibrations have shown the nonmonotonic dependence of the minimum and maximum vibration frequencies of cluster atoms on its composition and the coupling of their extreme values with the most stable atomic configuration. The increase in the number of Al atoms leads to the shift of the frequency spectrum and the substantial redistribution of the localization of vibrations on the cluster atoms.

  8. Synthesis and Characterization of Optically Active Fractal Seed Mediated Silver Nickel Bimetallic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Joseph Adeyemi Adekoya

    2014-01-01

    Full Text Available The synthesis of new seed mediated AgNi allied bimetallic nanocomposites was successfully carried out by the successive reduction of the metal ions in diethylene glycol, ethylene glycol, glycerol, and pentaerythritol solutions, with concomitant precipitation of Ag/Ni bimetal sols. The optical measurement revealed the existence of distinct band edge with surface plasmon resonance (SPR in the region of 400–425 nm and excitonic emission with maximum peak at 382 nm which were reminiscent of cluster-in-cluster surface enriched bimetallic silver-nickel sols. The morphological characterization by transmission electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction analyses complimented by surface scan using X-ray photoelectron spectroscopy strongly supported the formation of intimately alloyed face-centered silver/nickel nanoclusters.

  9. Synthesis of a discrete-action thermo-bimetallic actuator with a tongue

    Science.gov (United States)

    Nikolaeva, A.; McMillan, AJ; Gavriushin, S.

    2016-10-01

    The selection of suitable parameters, by experimental or intuitive processes for snap-through actuation of a bimetallic actuator at a prescribed temperature is an extremely time-consuming task. This paper describes a new methodology for the optimization of a discrete action thermo-bimetallic actuator with a tongue. This methodology makes it possible to solve the optimization task with higher efficiency. The requirement is to find optimal parameters values so that the actuator will make a snap-through at a given temperature. The constrained optimization task was performed using an evolutional algorithm and surrogate modelling and this was coded in Matlab. Functional relationships between the criteria and parameters were not set explicitly, but they were calculated using finite element method, each simulation of which was performed in Abaqus.

  10. LPG sensing performance of CuO–Ag2O bimetallic oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    K.R. Nemade

    2015-10-01

    Full Text Available In the present article, we synthesized CuO–Ag2O bimetallic oxide nanoparticles by using microwave assisted and solid state diffusion routes. The structural, morphological, optical and thermal study of as-synthesized materials were done through X-ray diffractometer (XRD, scanning electron microscope (SEM, Fourier transform infrared (FTIR, ultraviolet–visible (UV–vis and thermogravimetric analysis (TGA, respectively. Comparatively different sensing parameters such as sensing response at room temperature, operating temperature, response and recovery time and stability characteristics were investigated and discussed for liquefied petroleum gas (LPG. The CuO–Ag2O bimetallic oxide nanoparticles synthesized by microwave assisted route shows good gas sensing properties.

  11. Porous Diatomite-Immobilized Cu–Ni Bimetallic Nanocatalysts for Direct Synthesis of Dimethyl Carbonate

    Directory of Open Access Journals (Sweden)

    Yong Chen

    2012-01-01

    Full Text Available A series of diatomite-immobilized Cu–Ni bimetallic nanocatalysts was prepared under ultrasonication and evaluated for the direct synthesis of dimethyl carbonate under various conditions. Upon being fully characterized by TPR, TPD, BET, SEM, XRD, and XPS methodologies, it is found that the bimetallic composite is effectively alloyed and well immobilized inside or outside the pore of diatomite. Under the optimal conditions of 1.2 MPa and 120∘C, the prepared catalyst with loading of 15% exhibited the highest methanol conversion of 6.50% with DMC selectivity of 91.2% as well as more than 10-hour lifetime. The possible reaction mechanism was proposed and discussed in detail. To our knowledge, this is the first report to use diatomite as a catalyst support for direct DMC synthesis from methanol and CO2.

  12. Synthesis and exceptional thermal stability of Mg-based bimetallic nanoparticles during hydrogenation

    Science.gov (United States)

    Krishnan, Gopi; Negrea, Raluca F.; Ghica, Corneliu; Ten Brink, Gert H.; Kooi, Bart J.; Palasantzas, George

    2014-09-01

    Here we report the extraordinary thermal stability of Mg rich bimetallic nanoparticles (NPs), which is important for hydrogen storage technology. The enhanced NP stability is accomplished because of two critical improvements: (i) no void development within NPs (nanoscale Kirkendall effect) during their formation and (ii) suppressed Mg evaporation and NP hollowing during Mg hydrogenation at elevated temperature. The mechanism leading to the improved thermal stability of Mg-based bimetallic NPs is shown to be due to MgH2 hydride formation before evaporation can take place. These findings were tested for various compositions of Mg with Ni, Cu, and Ti, which are interesting combinations of materials for hydrogen storage systems. To achieve this we first demonstrate the synthesis mechanism of Mg-Ni and Mg-Cu NPs, which is well controlled at the single particle level, in order to accomplish multi-shell, alloy and intermetallic structures of interest for hydrogen storage tests. Aberration corrected transmission electron microscopy was carried out to unravel the detailed atomic structure and composition of the bimetallic NPs after production, processing, and hydrogenation. Finally, a simple and effective methodology is proposed for tuning the composition of the Mg-based bimetallic NPs based on the temperature-dependent nucleation behavior of NPs in the gas-phase.Here we report the extraordinary thermal stability of Mg rich bimetallic nanoparticles (NPs), which is important for hydrogen storage technology. The enhanced NP stability is accomplished because of two critical improvements: (i) no void development within NPs (nanoscale Kirkendall effect) during their formation and (ii) suppressed Mg evaporation and NP hollowing during Mg hydrogenation at elevated temperature. The mechanism leading to the improved thermal stability of Mg-based bimetallic NPs is shown to be due to MgH2 hydride formation before evaporation can take place. These findings were tested for various

  13. Corrosion resistant coating

    Science.gov (United States)

    Wrobleski, Debra A.; Benicewicz, Brian C.; Thompson, Karen G.; Bryan, Coleman J.

    1997-01-01

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  14. CORROSION PROTECTION OF ALUMINUM

    Science.gov (United States)

    Dalrymple, R.S.; Nelson, W.B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred. (D.C.W.)

  15. Nuclear corrosion science and engineering

    CERN Document Server

    2012-01-01

    Understanding corrosion mechanisms, the systems and materials they affect, and the methods necessary for accurately measuring their incidence is of critical importance to the nuclear industry for the safe, economic and competitive running of its plants. This book reviews the fundamentals of nuclear corrosion. Corrosion of nuclear materials, i.e. the interaction between these materials and their environments, is a major issue for plant safety as well as for operation and economic competitiveness. Understanding these corrosion mechanisms, the systems and materials they affect, and the methods to accurately measure their incidence is of critical importance to the nuclear industry. Combining assessment techniques and analytical models into this understanding allows operators to predict the service life of corrosion-affected nuclear plant materials, and to apply the most appropriate maintenance and mitigation options to ensure safe long term operation. This book critically reviews the fundamental corrosion mechani...

  16. Corrosion inhibitors from expired drugs.

    Science.gov (United States)

    Vaszilcsin, Nicolae; Ordodi, Valentin; Borza, Alexandra

    2012-07-15

    This paper presents a method of expired or unused drugs valorization as corrosion inhibitors for metals in various media. Cyclic voltammograms were drawn on platinum in order to assess the stability of pharmaceutically active substances from drugs at the metal-corrosive environment interface. Tafel slope method was used to determine corrosion rates of steel in the absence and presence of inhibitors. Expired Carbamazepine and Paracetamol tablets were used to obtain corrosion inhibitors. For the former, the corrosion inhibition of carbon steel in 0.1 mol L(-1) sulfuric acid solution was about 90%, whereas for the latter, the corrosion inhibition efficiency of the same material in the 0.25 mol L(-1) acetic acid-0.25 mol L(-1) sodium acetate buffer solution was about 85%.

  17. Automated methods of corrosion measurement

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Bech-Nielsen, Gregers; Reeve, John Ch

    1997-01-01

    Measurements of corrosion rates and other parameters connected with corrosion processes are important, first as indicators of the corrosion resistance of metallic materials and second because such measurements are based on general and fundamental physical, chemical, and electrochemical relations....... Hence improvements and innovations in methods applied in corrosion research are likeliy to benefit basic disciplines as well. A method for corrosion measurements can only provide reliable data if the beckground of the method is fully understood. Failure of a method to give correct data indicates a need...... to revise assumptions regarding the basis of the method, which sometimes leads to the discovery of as-yet unnoticed phenomena. The present selection of automated methods for corrosion measurements is not motivated simply by the fact that a certain measurement can be performed automatically. Automation...

  18. Corrosion-resistant metallic coatings

    Directory of Open Access Journals (Sweden)

    F. Presuel-Moreno

    2008-10-01

    Full Text Available We describe recent computational and experimental studies on the corrosion properties of metallic coatings that can be tailored (tuned to deliver up to three corrosion-inhibiting functions to an underlying substrate. Attributes are tuned by a selection of alloy compositions and nanostructures, ideally in alloy systems that offer flexibility of choice to optimize the corrosion-resisting properties. An amorphous Al-based coating is tuned for corrosion protection by on-demand release of ionic inhibitors to protect defects in the coating, by formation of an optimized barrier to local corrosion in Cl− containing environments, as well as by sacrificial cathodic prevention. Further progress in this field could lead to the design of the next generation of adaptive or tunable coatings that inhibit corrosion of underlying substrates.

  19. Levulinic acid hydrogenolysis on Al2O3-based Ni-Cu bimetallic catalysts

    Institute of Scientific and Technical Information of China (English)

    Iker Obregón; Eriz Corro; Urko Izquierdo; Jesus Requies; Pedro L. Arias

    2014-01-01

    Inexpensive γ-alumina-based nickel-copper bimetallic catalysts were studied for the hydrogenolysis of levulinic acid, a key platform molecule for biomass conversion to biofuels and other valued chemicals, into γ-valerolactone as a first step towards the production of 2-methyltetrahydrofurane. The activities of both monometallic and bimetallic catalysts were tested. Their textural and chemical characteristics were determined by nitrogen physisorption, elemental analysis, temperature-pro-grammed ammonia desorption, and temperature-programmed reduction. The monometallic nickel catalyst showed high activity but the highest by-product production and significant amounts of carbon deposited on the catalyst surface. The copper monometallic catalyst showed the lowest activity but the lowest carbon deposition. The incorporation of the two metals generated a bimetal-lic catalyst that displayed a similar activity to that of the Ni monometallic catalyst and significantly low by-product and carbon contents, indicating the occurrence of important synergetic effects. The influence of the preparation method was also examined by studying impregnated- and sol-gel-derived bimetallic catalysts. A strong dependency on the preparation procedure and calcina-tion temperature was observed. The highest activity per metal atom was achieved using the sol-gel-derived catalyst that was calcined at 450 °C. High reaction rates were achieved;the total levulinic acid conversion was obtained in less than 2 h of reaction time, yielding up to 96%γ-valerolactone, at operating temperature and pressure of 250 °C and 6.5 MPa hydrogen, respec-tively.

  20. Bimetallic Pt-Ni catalysts supported on usy zeolite for n-hexane isomerization

    Directory of Open Access Journals (Sweden)

    F. V. Barsi

    2009-06-01

    Full Text Available Isomerization of linear alkanes has had considerable importance for the refining industry because the isomers formed in this reaction have high octane number. Most works reported in the literature studied the use of bifunctional catalysts, i.e., ones that have acid sites and metallic sites. In this study, bifunctional monometallic (Ni or Pt and bimetallic catalysts (Pt-Ni, using HUSY zeolite as the support, were prepared in order to verify the role of the metal content and composition on the catalytic properties for n-hexane isomerization. The method used for metal dispersion in the zeolite was competitive ion exchange using ammine complexes [Ni(NH36]Cl2 and [Pt(NH34]Cl2 as precursors. Four series of catalysts with constant atomic metal content had total metal amounts between 130 and 280 µmol M/g cat. Catalysts were characterized by temperature programmed reduction (TPR and subjected to catalytic evaluation for n-hexane isomerization at 250 ºC and 1 atm using H2/C6 = 9 molar ratio. TPR results show an easier reducibility of Ni+2 cations in the presence of Pt, which was evidenced by the displacement of the reduction peak of those cations towards lower temperatures in bimetallic catalysts. The bimetallic catalysts presented a higher activity in the isomerization of n-hexane when compared to the monometallic ones, as well better stability as the Pt content in the solid increases. The results of the activity as a function of the Pt content in the bimetallic catalysts show a maximum value around 50% of Pt. An addition of Pt above this critical value leads to a small decrease of the catalytic activity.

  1. Bimetallic Pt-Ni catalysts supported on usy zeolite for n-hexane isomerization

    OpenAIRE

    F. V. Barsi; Cardoso,D.

    2009-01-01

    Isomerization of linear alkanes has had considerable importance for the refining industry because the isomers formed in this reaction have high octane number. Most works reported in the literature studied the use of bifunctional catalysts, i.e., ones that have acid sites and metallic sites. In this study, bifunctional monometallic (Ni or Pt) and bimetallic catalysts (Pt-Ni), using HUSY zeolite as the support, were prepared in order to verify the role of the metal content and composition on th...

  2. Stability of the Shallow Axisymmetric Parabolic-Conic Bimetallic Shell by Nonlinear Theory

    OpenAIRE

    M. Jakomin; Kosel, F.

    2011-01-01

    In this contribution, we discuss the stress, deformation, and snap-through conditions of thin, axi-symmetric, shallow bimetallic shells of so-called parabolic-conic and plate-parabolic type shells loaded by thermal loading. According to the theory of the third order that takes into account the balance of forces on a deformed body, we present a model with a mathematical description of the system geometry, displacements, stress, and thermoelastic deformations. The equations are based on the lar...

  3. Platinum-ruthenium bimetallic clusters on graphite: a comparison of vapor deposition and electroless deposition methods.

    Science.gov (United States)

    Galhenage, Randima P; Xie, Kangmin; Diao, Weijian; Tengco, John Meynard M; Seuser, Grant S; Monnier, John R; Chen, Donna A

    2015-11-14

    Bimetallic Pt-Ru clusters have been grown on highly ordered pyrolytic graphite (HOPG) surfaces by vapor deposition and by electroless deposition. These studies help to bridge the material gap between well-characterized vapor deposited clusters and electrolessly deposited clusters, which are better suited for industrial catalyst preparation. In the vapor deposition experiments, bimetallic clusters were formed by the sequential deposition of Pt on Ru or Ru on Pt. Seed clusters of the first metal were grown on HOPG surfaces that were sputtered with Ar(+) to introduce defects, which act as nucleation sites for Pt or Ru. On the unmodified HOPG surface, both Pt and Ru clusters preferentially nucleated at the step edges, whereas on the sputtered surface, clusters with relatively uniform sizes and spatial distributions were formed. Low energy ion scattering experiments showed that the surface compositions of the bimetallic clusters are Pt-rich, regardless of the order of deposition, indicating that the interdiffusion of metals within the clusters is facile at room temperature. Bimetallic clusters on sputtered HOPG were prepared by the electroless deposition of Pt on Ru seed clusters from a Pt(+2) solution using dimethylamine borane as the reducing agent at pH 11 and 40 °C. After exposure to the electroless deposition bath, Pt was selectively deposited on Ru, as demonstrated by the detection of Pt on the surface by XPS, and the increase in the average cluster height without an increase in the number of clusters, indicating that Pt atoms are incorporated into the Ru seed clusters. Electroless deposition of Ru on Pt seed clusters was also achieved, but it should be noted that this deposition method is extremely sensitive to the presence of other metal ions in solution that have a higher reduction potential than the metal ion targeted for deposition.

  4. Desorption of Furfural from Bimetallic Pt-Fe Oxides/Alumina Catalysts

    OpenAIRE

    Gloria Lourdes Dimas-Rivera; Javier Rivera de la Rosa; Carlos J. Lucio-Ortiz; José Antonio De los Reyes Heredia; Virgilio González González; Tomás Hernández

    2014-01-01

    In this work, the desorption of furfural, which is a competitive intermediate during the production of biofuel and valuable aromatic compounds, was studied using pure alumina, as well as alumina impregnated with iron and platinum oxides both individually and in combination, using thermogravimetric analysis (TGA). The bimetallic sample exhibited the lowest desorption percentage for furfural. High-resolution transmission electron microscopy (HRTEM) imaging revealed the intimate connection betwe...

  5. LPG sensing performance of CuO–Ag2O bimetallic oxide nanoparticles

    OpenAIRE

    K.R. Nemade; S.A. Waghuley

    2015-01-01

    In the present article, we synthesized CuO–Ag2O bimetallic oxide nanoparticles by using microwave assisted and solid state diffusion routes. The structural, morphological, optical and thermal study of as-synthesized materials were done through X-ray diffractometer (XRD), scanning electron microscope (SEM), Fourier transform infrared (FTIR), ultraviolet–visible (UV–vis) and thermogravimetric analysis (TGA), respectively. Comparatively different sensing parameters such as sensing response at ro...

  6. Corrosion in supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Propp, W.A.; Carleson, T.E.; Wai, Chen M.; Taylor, P.R.; Daehling, K.W.; Huang, Shaoping; Abdel-Latif, M.

    1996-05-01

    Integrated studies were carried out in the areas of corrosion, thermodynamic modeling, and electrochemistry under pressure and temperature conditions appropriate for potential applications of supercritical fluid (SCF) extractive metallurgy. Carbon dioxide and water were the primary fluids studied. Modifiers were used in some tests; these consisted of 1 wt% water and 10 wt% methanol for carbon dioxide and of sulfuric acid, sodium sulfate, ammonium sulfate, and ammonium nitrate at concentrations ranging from 0.00517 to 0.010 M for the aqueous fluids. The materials studied were Types 304 and 316 (UNS S30400 and S31600) stainless steel, iron, and AISI-SAE 1080 (UNS G10800) carbon steel. The thermodynamic modeling consisted of development of a personal computer-based program for generating Pourbaix diagrams at supercritical conditions in aqueous systems. As part of the model, a general method for extrapolating entropies and related thermodynamic properties from ambient to SCF conditions was developed. The experimental work was used as a tool to evaluate the predictions of the model for these systems. The model predicted a general loss of passivation in iron-based alloys at SCF conditions that was consistent with experimentally measured corrosion rates and open circuit potentials. For carbon-dioxide-based SCFs, measured corrosion rates were low, indicating that carbon steel would be suitable for use with unmodified carbon dioxide, while Type 304 stainless steel would be suitable for use with water or methanol as modifiers.

  7. Corrosion detection by induction

    Science.gov (United States)

    Roddenberry, Joshua L.

    Bridges in Florida are exposed to high amounts of humidity due to the state's geography. This excess moisture results in a high incidence of corrosion on the bridge's steel support cables. Also, the inclusion of ineffective waterproofing has resulted in additional corrosion. As this corrosion increases, the steel cables, responsible for maintaining bridge integrity, deteriorate and eventually break. If enough of these cables break, the bridge will experience a catastrophic failure resulting in collapse. Repairing and replacing these cables is very expensive and only increases with further damage. As each of the cables is steel, they have strong conductive properties. By inducing a current along each group of cables and measuring its dissipation over distance, a picture of structural integrity can be determined. The purpose of this thesis is to prove the effectiveness of using electromagnetic techniques to determine cable integrity. By comparing known conductive values (determined in a lab setting) to actual bridge values, the tester will be able to determine the location and severity of any damage, if present.

  8. Corrosion of bio implants

    Indian Academy of Sciences (India)

    U Kamachi Mudali; T M Sridhar; Baldev Raj

    2003-06-01

    Chemical stability, mechanical behaviour and biocompatibility in body fluids and tissues are the basic requirements for successful application of implant materials in bone fractures and replacements. Corrosion is one of the major processes affecting the life and service of orthopaedic devices made of metals and alloys used as implants in the body. Among the metals and alloys known, stainless steels (SS), Co–Cr alloys and titanium and its alloys are the most widely used for the making of biodevices for extended life in human body. Incidences of failure of stainless steel implant devices reveal the occurrence of significant localised corroding viz., pitting and crevice corrosion. Titanium forms a stable TiO2 film which can release titanium particles under wear into the body environment. To reduce corrosion and achieve better biocompatibility, bulk alloying of stainless steels with titanium and nitrogen, surface alloying by ion implantation of stainless steels and titanium and its alloys, and surface modification of stainless steel with bioceramic coatings are considered potential methods for improving the performance of orthopaedic devices. This review discusses these issues in depth and examines emerging directions.

  9. Automated Methods of Corrosion Measurements

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    1997-01-01

    electrochemical measurements as well as elemental analysis look very promising for elucidating corrosion reaction mechanisms. The study of initial surface reactions at the atomic or submicron level is becoming an important field of research in the understanding of corrosion processes. At present, mainly two...... scanning microscope techniques are employed investigating corrosion processes, and usually in situ: in situ scanning tunneling microscopy (in situ STM) and in situ scanning force microscopy (in situ AFM). It is these techniques to which attention is directed here....

  10. Panel report on corrosion in energy systems

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-06-01

    Corrosion problems in high-temperature (non aqueous) energy systems, corrosion in aqueous energy systems and institutional problems inhibiting the development of corrosion science and engineering are discussed. (FS)

  11. Fractal Dimension Calculation of a Manganese-Chromium Bimetallic Nanocomposite Using Image Processing

    Directory of Open Access Journals (Sweden)

    Amir Lashgari

    2015-01-01

    Full Text Available Bimetallic materials, which have the ability to convert heat change into mechanical movement, normally consist of two bonded strips of dissimilar metals that expand at different rates. We describe how we made a manganese-chromium (Mn-Cr bimetallic nanocomposite using the centrifuge method and a low-to-high approach. We conducted scanning electron microscope (SEM imaging, energy-dispersive X-ray spectroscopy (EDX analysis, and X-ray diffraction spectra of the nanocomposite to prove its identity. We examined how centrifuge speed, process time, and the use of an “intruder agent” affected the properties of the material. The fractal dimension is a significant factor that can be used to approximate the surface roughness, the texture segmentation, and an image of the studied compounds. We calculated the technique of fractal dimensions using image-processing values on a computer and histogram plot with the SEM image of the Mn-Cr bimetallic nanocomposite using MATLAB software. We applied the Statistical Package for the Social Sciences software for statistics data extracted from the SEM image of the nanocomposite and obtained the following results: mean = 1.778, median = 1.770, max = 1.98, min = 1.60, skewness = 0.177, range = 0.38, and harmonic mean = 1.771 for fractal dimension of the SEM image.

  12. Electrodeposition of Au/Ag bimetallic dendrites assisted by Faradaic AC-electroosmosis flow

    Directory of Open Access Journals (Sweden)

    Jianlong Ji

    2014-03-01

    Full Text Available Au/Ag bimetallic dendrites were synthesized successfully from the corresponding aqueous solution via the AC electrodeposition method. Both of the morphologies and compositions could be tuned by the electrolyte concentration and AC frequency. The prepared bimetallic dendrites were characterized by scanning electron microscopy (SEM, energy dispersive X-ray spectrometer (EDS, transmission electron microscopy (TEM and UV–vis spectroscopy. The underlying dendrite growth mechanism was then proposed in the context of the Directed Electrochemical Nanowires Assembly (DENA models. Owing to the unscreened voltage dropping in the electrolyte bulk, electromigration dominates the species flux process, and cations tend to accumulate in areas with strong electric field intensity, such as electrode edges. Moreover, Faradaic AC-electro-osmosis (ACEO flow could increase the effective diffusion layer thickness in these areas during the electrochemical reaction, and leads to dendrite growth. Further Micro-Raman observations illustrated that the Au/Ag bimetallic dendrites exhibited pronounced surface-enhanced Raman scattering (SERS activity, using 4-mercaptopyridine (4-MP as model molecules.

  13. Characterization of Bimetallic Castings with an Austenitic Working Surface Layer and an Unalloyed Cast Steel Base

    Science.gov (United States)

    Wróbel, Tomasz

    2014-05-01

    The paper presents the technology of bimetallic castings based on the founding method of layer coating directly in the cast process of the so-called method of mold cavity preparation. The prepared castings consist of two fundamental parts, i.e., the base and the working surface layer. The base part of the bimetallic casting is typical foundry material, i.e., unalloyed cast steel, whereas the working layer is a plate of austenitic alloy steel sort X2CrNi 18-9. The quality of the joint between the base part and the working layer was evaluated on the basis of ultrasonic non-destructive testing and structure examinations containing metallographic macro- and microscopic studies with the use of a light microscope (LOM) with microhardness measurements and a scanning electron microscope (SEM) with microanalysis of the chemical composition (energy dispersive spectroscopy—EDS). On the basis of the obtained results it was confirmed that the decisive phenomena needed to create a permanent joint between the two components of the bimetallic casting are carbon and heat transport in the direction from the high-carbon and hot base material which was poured into the mold in the form of liquid metal to the low-carbon and cold material of the working layer which was placed in the mold cavity in the form of a monolithic insert.

  14. Copper-silver bimetallic system on natural clinoptilolite: thermal reduction of Cu2+ and Ag+ exchanged.

    Science.gov (United States)

    Rodríguez-Iznaga, Inocente; Petranovskii, Vitalii; Castillón-Barraza, Felipe; Concepción-Rosabal, Beatriz

    2011-06-01

    Copper-silver bimetallic system supported on natural clinoptilolite from Tasajeras deposit (Cuba) was studied. Bimetallic samples were prepared by simultaneous ion exchange, and reduced in a wide temperature range in a hydrogen flow. The main goal of the work was analysis of the mutual influence of both metals on their reduction process and the properties of the resultant particles. Analysis was done by combined use of XRD and UV-Vis spectroscopy. The reduction of Cu2+ and Ag+ cations shows existence of notable inter-influence between both cations during this process. The Cu2+ reduction is favored by the presence of Ag+, which should be related with the synergetic influence of silver cations and/or clusters formed on the first stages of reduction on Cu(2+)-framework interaction, facilitating the Cu2+ reduction even at low temperature (25 and 50 degrees C). The aggregation of the reduced highly dispersed species both for copper and silver is limited in this bimetallic system. The introduction of Ag+ as the second cation in the copper-exchanged zeolites favors the copper reduction at lower temperatures (25 and 50 degrees C), and appears to be the efficient tool for the control of the size of the resultant reduced nanoparticles (it means their dispersion).

  15. Core-size-dependent catalytic properties of bimetallic Au/Ag core-shell nanoparticles.

    Science.gov (United States)

    Haldar, Krishna Kanta; Kundu, Simanta; Patra, Amitava

    2014-12-24

    Bimetallic core-shell nanoparticles have recently emerged as a new class of functional materials because of their potential applications in catalysis, surface enhanced Raman scattering (SERS) substrate and photonics etc. Here, we have synthesized Au/Ag bimetallic core-shell nanoparticles with varying the core diameter. The red-shifting of the both plasmonic peaks of Ag and Au confirms the core-shell structure of the nanoparticles. Transmission electron microscopy (TEM) analysis, line scan EDS measurement and UV-vis study confirm the formation of core-shell nanoparticles. We have examined the catalytic activity of these core-shell nanostructures in the reaction between 4-nitrophenol (4-NP) and NaBH4 to form 4-aminophenol (4-AP) and the efficiency of the catalytic reaction is found to be increased with increasing the core size of Au/Ag core-shell nanocrystals. The catalytic efficiency varies from 41.8 to 96.5% with varying core size from 10 to 100 nm of Au/Ag core-shell nanoparticles, and the Au100/Ag bimetallic core-shell nanoparticle is found to be 12-fold more active than that of the pure Au nanoparticles with 100 nm diameter. Thus, the catalytic properties of the metal nanoparticles are significantly enhanced because of the Au/Ag core-shell structure, and the rate is dependent on the size of the core of the nanoparticles.

  16. Electrodeposition of Au/Ag bimetallic dendrites assisted by Faradaic AC-electroosmosis flow

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Jianlong; Li, Pengwei; Sang, Shengbo, E-mail: sbsang@tyut.edu.cn; Zhang, Wendong, E-mail: wdzhang@tyut.edu.cn; Li, Gang; Hu, Jie [Micro and Nano-system Research Centre, College of Information Engineering, Taiyuan University of Technology, 030024, Taiyuan (China); Zhou, Zhaoying, E-mail: zhouzy@mail.tsinghua.edu.cn; Yang, Xing; Dong, Hualai [MEMS Laboratory, Department of Precision Instruments, Tsinghua University, 100084, Beijing (China)

    2014-03-15

    Au/Ag bimetallic dendrites were synthesized successfully from the corresponding aqueous solution via the AC electrodeposition method. Both of the morphologies and compositions could be tuned by the electrolyte concentration and AC frequency. The prepared bimetallic dendrites were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), transmission electron microscopy (TEM) and UV–vis spectroscopy. The underlying dendrite growth mechanism was then proposed in the context of the Directed Electrochemical Nanowires Assembly (DENA) models. Owing to the unscreened voltage dropping in the electrolyte bulk, electromigration dominates the species flux process, and cations tend to accumulate in areas with strong electric field intensity, such as electrode edges. Moreover, Faradaic AC-electro-osmosis (ACEO) flow could increase the effective diffusion layer thickness in these areas during the electrochemical reaction, and leads to dendrite growth. Further Micro-Raman observations illustrated that the Au/Ag bimetallic dendrites exhibited pronounced surface-enhanced Raman scattering (SERS) activity, using 4-mercaptopyridine (4-MP) as model molecules.

  17. Electrodeposition of Au/Ag bimetallic dendrites assisted by Faradaic AC-electroosmosis flow

    Science.gov (United States)

    Ji, Jianlong; Li, Pengwei; Sang, Shengbo; Zhang, Wendong; Zhou, Zhaoying; Yang, Xing; Dong, Hualai; Li, Gang; Hu, Jie

    2014-03-01

    Au/Ag bimetallic dendrites were synthesized successfully from the corresponding aqueous solution via the AC electrodeposition method. Both of the morphologies and compositions could be tuned by the electrolyte concentration and AC frequency. The prepared bimetallic dendrites were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), transmission electron microscopy (TEM) and UV-vis spectroscopy. The underlying dendrite growth mechanism was then proposed in the context of the Directed Electrochemical Nanowires Assembly (DENA) models. Owing to the unscreened voltage dropping in the electrolyte bulk, electromigration dominates the species flux process, and cations tend to accumulate in areas with strong electric field intensity, such as electrode edges. Moreover, Faradaic AC-electro-osmosis (ACEO) flow could increase the effective diffusion layer thickness in these areas during the electrochemical reaction, and leads to dendrite growth. Further Micro-Raman observations illustrated that the Au/Ag bimetallic dendrites exhibited pronounced surface-enhanced Raman scattering (SERS) activity, using 4-mercaptopyridine (4-MP) as model molecules.

  18. Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Chunshan Song; Schobert, H.H.; Parfitt, D.P. [and others

    1997-11-01

    Development of new catalysts is a promising approach to more efficient coal liquefaction. It has been recognized that dispersed catalysts are superior to supported catalysts for primary liquefaction of coals, because the control of initial coal dissolution or depolymerization requires intimate contact between the catalyst and coal. This research is a fundamental and exploratory study on catalytic coal liquefaction, with the emphasis on exploring novel bimetallic dispersed catalysts for coal liquefaction and the effectiveness of temperature-programmed liquefaction using dispersed catalysts. The primary objective of this research was to explore novel bimetallic dispersed catalysts from organometallic molecular precursors, that could be used in low concentrations but exhibit relatively high activity for efficient hydroliquefaction of coals under temperature-programmed conditions. We have synthesized and tested various catalyst precursors in liquefaction of subbituminous and bituminous coals and in model compound studies to examine how do the composition and structure of the catalytic precursors affect their effectiveness for coal liquefaction under different reaction conditions, and how do these factors affect their catalytic functions for hydrogenation of polyaromatic hydrocarbons, for cleavage of C-C bonds in polycyclic systems such as 4-(1-naphthylmethyl)bibenzyl, for hydrogenolysis of C-O bond such as that in dinaphthylether, for hydrodeoxygenation of phenolic compounds and other oxygen-containing compounds such as xanthene, and for hydrodesulfurization of polycyclic sulfur compounds such as dibenzothiophene. The novel bimetallic and monometallic precursors synthesized and tested in this project include various Mo- and Fe-based compounds.

  19. The effect of intermolecular hydrogen bonding on the fluorescence of a bimetallic platinum complex.

    Science.gov (United States)

    Zhao, Guang-Jiu; Northrop, Brian H; Han, Ke-Li; Stang, Peter J

    2010-09-02

    The bimetallic platinum complexes are known as unique building blocks and arewidely utilized in the coordination-driven self-assembly of functionalized supramolecular metallacycles. Hence, photophysical study of the bimetallic platinum complexes will be very helpful for the understanding on the optical properties and further applications of coordination-driven self-assembled supramolecular metallacycles. Herein, we report steady-state and time-resolved spectroscopic experiments as well as quantum chemistry calculations to investigate the significant intermolecular hydrogen bonding effects on the intramolecular charge transfer (ICT) fluorescence of a bimetallic platinum compound 4,4'-bis(trans-Pt(PEt(3))(2)OTf)benzophenone 3 in solution. We demonstrated that the fluorescent state of compound 3 can be assigned as a metal-to-ligand charge transfer (MLCT) state. Moreover, it was observed that the formation of intermolecular hydrogen bonds can effectively lengthen the fluorescence lifetime of 3 in alcoholic solvents compared with that in hexane solvent. At the same time, the electronically excited states of 3 in solution are definitely changed by intermolecular hydrogen bonding interactions. As a consequence, we propose a new fluorescence modulation mechanism by hydrogen bonding to explain different fluorescence emissions of 3 in hydrogen-bonding solvents and nonhydrogen-bonding solvents.

  20. Ferrocenyl-cymantrenyl hetero-bimetallic chalcones: Synthesis, structure and biological properties

    Science.gov (United States)

    Mishra, Sasmita; Tirkey, Vijaylakshmi; Ghosh, Avishek; Dash, Hirak R.; Das, Surajit; Shukla, Madhulata; Saha, Satyen; Mobin, Sheikh M.; Chatterjee, Saurav

    2015-04-01

    Two new ferrocenyl-cymantrenyl bimetallic chalcones, [(CO)3Mn(η5-C5H4)C(O)CHdbnd CH(η5-C5H4)Fe(η5-C5H5)] (1) and [{(CO)3Mn(η5-C5H4)C(O)CHdbnd CH(η5-C5H4)}2Fe] (2) have been synthesized. Their reactivity study with triphenylphosphine and bis-(diphenylphosphino)ferrocene led to the isolation of phosphine substituted bimetallic chalcones (3-6). Single crystal X-ray structural characterization for 1 and its phosphine analogue (3) reveals their different conformational identity with anti-conformation for 1, while syn-conformation for 3. Investigation of antimalarial and antibacterial activities was carried out for compounds 1 and 2 against two strains of Plasmodium falciparum (3D7, K1) and four bacterial strains. TD-DFT calculation was performed for compound 1 and electrochemical properties were studied for bimetallic chalcone compounds by cyclic voltammetric technique.

  1. In Situ Synthesis of Bimetallic Hybrid Nanocatalysts on a Paper-Structured Matrix for Catalytic Applications

    Directory of Open Access Journals (Sweden)

    Hirotaka Koga

    2011-11-01

    Full Text Available Bimetallic nanoparticles have attracted significant attention as their electrochemical and catalytic properties being superior to those of the individual component nanoparticles. In this study, gold-silver hybrid nanoparticles (AuAgNPs with an Aucore-Agshell nanostructure were successfully synthesized on zinc oxide (ZnO whiskers. The as-prepared nanocatalyst, denoted AuAgNPs@ZnO whisker, exhibits an excellent catalytic efficiency in the aqueous reduction of 4-nitrophenol to 4-aminophenol; the turnover frequency was up to 40 times higher than that of each component nanoparticle. Their unique features were attributed to the electronic ligand effect at the bimetallic interface. In addition, the AuAgNPs were synthesized on a ZnO whisker-containing paper with a fiber-network microstructure, which was prepared via a papermaking technique. The paper-structured AuAgNPs composite possessed both a paper-like practical utility and a good catalytic performance. Furthermore, the on-paper synthesis process for these bimetallic nanocatalysts is facile. These easy-to-handle nanocatalyst hybrid composites are expected to find a wide range of applications in various chemical and catalytic processes.

  2. Mechanisms of metal dusting corrosion

    DEFF Research Database (Denmark)

    Hummelshøj, Thomas Strabo

    In this thesis the early stages of metal dusting corrosion is addressed; the development of carbon expanded austenite, C, and the decomposition hereof into carbides. Later stages of metal dusting corrosion are explored by a systematic study of stainless steel foils exposed to metal dusting...... influence of oxygen and carbon on the metal dusting corrosion is explored. The results indicate that exposure to metal dusting conditions have a detrimental effect on the resistance against oxidation and, conversely, that exposure to oxidation has a detrimental effect on the resistance towards metal dusting....... Consequently, a combination of carburizing and oxidizing conditions has a strong mutual catalyzing effect on the metal dusting corrosion....

  3. Archaeological analogs and corrosion; Analogues archeologiques et corrosion

    Energy Technology Data Exchange (ETDEWEB)

    David, D

    2008-07-01

    In the framework of the high level and long life radioactive wastes disposal deep underground, the ANDRA built a research program on the material corrosion. In particular they aim to design containers for a very long time storage. Laboratory experiments are in progress and can be completed by the analysis of metallic archaeological objects and their corrosion after hundred years. (A.L.B.)

  4. Civil Engineering Corrosion Control. Volume 1. Corrosion Control - General

    Science.gov (United States)

    1975-01-01

    pipes, so accelerated corrosion occurs there. Small corrosion cells may result from differential aeration on pumps or sludge digesters under rust...and cables Transmission towers Shielding inside communication cables Lamp poles 1 Also used ’extensively in chemical, rutber, soap, brewery, dairy ...Inconel Applications Type of Application Materials Being Handled Evaporators concentration or magnesium chloride (tubes) Fermentation tanks Processing of

  5. Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion

    Science.gov (United States)

    Zhang, Xuming; Wu, Guosong; Peng, Xiang; Li, Limin; Feng, Hongqing; Gao, Biao; Huo, Kaifu; Chu, Paul K.

    2015-11-01

    Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface composed of an inner compact layer and top Mg-Al layered double hydroxide (LDH) microsheet is produced on a large area using a one-step process and excellent corrosion resistance is achieved in saline solutions. Moreover, inspired by the super-hydrophobic phenomenon in nature such as the lotus leaves effect, the orientation of the top microsheet layer is tailored by adjusting the hydrothermal temperature, time, and pH to produce a water-repellent surface after modification with fluorinated silane. As a result of the trapped air pockets in the microstructure, the super-hydrophobic surface with the Cassie state shows better corrosion resistance in the immersion tests. The results reveal an economical and environmentally friendly means to control and use the pre-corrosion products on magnesium alloys.

  6. Bimetallic Nanocatalysts in Mesoporous Silica for Hydrogen Production from Coal-Derived Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Kuila, Debasish [North Carolina Agricultural & Technical State Univ., Greensboro, NC (United States); Ilias, Shamsuddin [North Carolina Agricultural & Technical State Univ., Greensboro, NC (United States)

    2013-02-13

    In steam reforming reactions (SRRs) of alkanes and alcohols to produce H2, noble metals such as platinum (Pt) and palladium (Pd) are extensively used as catalyst. These metals are expensive; so, to reduce noble-metal loading, bi-metallic nanocatalysts containing non-noble metals in MCM-41 (Mobil Composition of Material No. 41, a mesoporous material) as a support material with high-surface area were synthesized using one-pot hydrothermal procedure with a surfactant such as cetyltrimethylammonium bromide (CTAB) as a template. Bi-metallic nanocatalysts of Pd-Ni and Pd-Co with varying metal loadings in MCM-41 were characterized by x-ray diffraction (XRD), N2 adsorption, and Transmission electron microscopy (TEM) techniques. The BET surface area of MCM-41 (~1000 m2/g) containing metal nanoparticles decreases with the increase in metal loading. The FTIR studies confirm strong interaction between Si-O-M (M = Pd, Ni, Co) units and successful inclusion of metal into the mesoporous silica matrix. The catalyst activities were examined in steam reforming of methanol (SRM) reactions to produce hydrogen. Reference tests using catalysts containing individual metals (Pd, Ni and Co) were also performed to investigate the effect of the bimetallic system on the catalytic behavior in the SRM reactions. The bimetallic system remarkably improves the hydrogen selectivity, methanol conversion and stability of the catalyst. The results are consistent with a synergistic behavior for the Pd-Ni-bimetallic system. The performance, durability and thermal stability of the Pd-Ni/MCM-41 and Pd-Co/MCM-41 suggest that these materials may be promising catalysts for hydrogen production from biofuels. A part of this work for synthesis and characterization of Pd-Ni-MCM-41 and its activity for SRM reactions has been published (“Development of Mesoporous Silica Encapsulated Pd-Ni Nanocatalyst for Hydrogen Production” in “Production and Purification of Ultraclean

  7. Plasmonic Properties of Bimetallic Nanostructures and Their Applications in Hydrogen Sensing and Chemical Reactions

    Science.gov (United States)

    Jiang, Ruibin

    Noble metal nanocrystals have attracted great interest from a wide range of research fields because of their intriguing properties endowed by their localized surface plasmon resonances, which are the collective oscillations of free electrons. Under resonant excitation, metal nanostructures exhibit very large scattering and absorption cross sections and large near-field enhancement. These extraordinary properties can be used in different applications, such as plasmonic sensing and imaging, plasmon-controlled optics, photothermal therapy, photocatalysis, solar cells, and so on. Gold and Silver nanocrystals have plasmon resonances in the visible and near-infrared regions. However, gold and silver are not suitable for some applications. For example, they are generally inactive for catalyzing chemical reactions. The integration of plasmonic metals with other metals can offer superior or new physical/chemical properties. In this thesis, I prepared Au/Ag and Au/Pd bimetallic nanostructures and studied their plasmonic properties and applications in hydrogen sensing and photocatalysis. Seeds have a crucial importance in the synthesis of bimetallic nanostructures. I therefore first studied the roles of the crystalline structure and shape of seeds on the overgrowth of bimetallic nanostructures. The overgrowth of silver and palladium on single crystalline Au nanorods, multicrystalline Au nanorods, and nanobipyramids were studied under the same conditions for each metal. The growths of silver and palladium on single crystalline Au nanorods gave cuboidal nanostructures, while rod-shaped nanostructures were obtained from the growths of silver and palladium on multicrystalline Au nanorods and nanobipyramids. Moreover, the growths of silver and palladium on multicrystalline Au nanobipyramids started at the stepped side facets, while the growths started at the twin boundaries on multicrystalline Au nanorods. These results unambiguously indicate that the crystalline structure of

  8. General Corrosion and Localized Corrosion of Waste Package Outer Barrier

    Energy Technology Data Exchange (ETDEWEB)

    K.G. Mon

    2004-10-01

    The waste package design for the License Application is a double-wall waste package underneath a protective drip shield (BSC 2004 [DIRS 168489]; BSC 2004 [DIRS 169480]). The purpose and scope of this model report is to document models for general and localized corrosion of the waste package outer barrier (WPOB) to be used in evaluating waste package performance. The WPOB is constructed of Alloy 22 (UNS N06022), a highly corrosion-resistant nickel-based alloy. The inner vessel of the waste package is constructed of Stainless Steel Type 316 (UNS S31600). Before it fails, the Alloy 22 WPOB protects the Stainless Steel Type 316 inner vessel from exposure to the external environment and any significant degradation. The Stainless Steel Type 316 inner vessel provides structural stability to the thinner Alloy 22 WPOB. Although the waste package inner vessel would also provide some performance for waste containment and potentially decrease the rate of radionuclide transport after WPOB breach before it fails, the potential performance of the inner vessel is far less than that of the more corrosion-resistant Alloy 22 WPOB. For this reason, the corrosion performance of the waste package inner vessel is conservatively ignored in this report and the total system performance assessment for the license application (TSPA-LA). Treatment of seismic and igneous events and their consequences on waste package outer barrier performance are not specifically discussed in this report, although the general and localized corrosion models developed in this report are suitable for use in these scenarios. The localized corrosion processes considered in this report are pitting corrosion and crevice corrosion. Stress corrosion cracking is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]).

  9. Degradation of Bimetallic Model Electrocatalysts ___ an in situ XAS Study

    Energy Technology Data Exchange (ETDEWEB)

    Friebel, Daniel

    2011-06-22

    One of the major challenges in the development of clean energy fuel cells is the performance degradation of the electrocatalyst, which, apart from poisoning effects, can suffer from corrosion due to its exposure to a harsh environment under high potentials. In this communication, we demonstrate how interactions of Pt with a transition metal support affect not only, as commonly intended, the catalytic activity, but also the reactivity of Pt towards oxide formation or dissolution. We use two well-defined single-crystal model systems, Pt/Rh(111) and Pt/Au(111) and a unique x-ray spectroscopy technique with enhanced energy resolution to monitor the potential-dependent oxidation state of Pt, and find two markedly different oxidation mechanisms on the two different substrates. This information can be of great significance for future design of more active and more stable catalysts. We have studied the potential-induced degradation of Pt monolayer model electrocatalysts on Rh(111) and Au(111) single-crystal substrates. The anodic formation of Pt oxides was monitored using in situ high energy resolution fluorescence detection x-ray absorption spectroscopy (HERFD XAS). Although Pt was deposited on both substrates in a three-dimensional island growth mode, we observed remarkable differences during oxide formation that can only be understood in terms of strong Pt-substrate interactions throughout the Pt islands. Anodic polarization of Pt/Rh(111) up to +1.6 V vs. RHE (reversible hydrogen electrode) leads to formation an incompletely oxidized passive layer, whereas formation of PtO2 and partial Pt dissolution is observed for Pt/Au(111).

  10. A new ligand system based on a bipyridine-functionalized calix[4]arene backbone leading to mono- and bimetallic complexes.

    Science.gov (United States)

    Dorta, Reto; Shimon, Linda J W; Rozenberg, Haim; Ben-David, Yehoshoa; Milstein, David

    2003-05-19

    The synthesis of a new ligand system for mono- and bimetallic complexes based on a calixarene is described. Ligand BBPC (3, bis(bipyridine)-calix[4]arene) is obtained in three steps in 40% overall yield by first brominating one of the methyl groups of the 4,4'-dimethyl-2,2'-bipyridine in two steps and subsequently reacting it with p-tert-butylcalix[4]arene under basic conditions. Reaction of BBPC (3) with 2 equiv of [Rh(NBD)(2)]BF(4) or [Rh(NBD)(CH(3)CN)(2)]BF(4) (NBD = norbornadiene) produces the bimetallic compound BBPC[Rh(NBD)BF(4)](2) (4). Treatment of the ligand with PdCl(2)(CH(3)CN)(2) leads to the isolation of the bimetallic complex BBPC[PdCl(2)](2) (5). When the nickel precursor NiBr(2)(DME) (DME = dimethoxyethane) is reacted with BBPC, the bimetallic complex BBPC[NiBr(2)](2) (6) is isolated which, upon crystallization from methanol, gives the mononuclear bis(bipyridine) complex BBPC[NiBr(OMe)] (7). Full characterization includes X-ray structural studies of complexes 4, 5, and 7. The bimetallic compounds 4 and 5 show metal to metal distances of 4.334 A (for 4) and 3.224 A (for 5). For all three complexes, unique molecular packing arrangements were found, based on hydrophobic/hydrophilic interactions.

  11. Hierarchical paramecium-like hollow and solid Au/Pt bimetallic nanostructures constructed using goethite as template

    Energy Technology Data Exchange (ETDEWEB)

    Liu Wei; Repo, Eveliina; Sillanpaeae, Mika [Laboratory of Applied Environmental Chemistry, University of Eastern Finland, Patteristonkatu 1, FI-50100 Mikkeli (Finland); Heikkilae, Mikko; Leskelae, Markku, E-mail: weiliuzk@yahoo.cn, E-mail: mika.sillanpaa@uef.fi [Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, PO Box 55 (A.I. Virtasen aukio 1), FI-00014, Helsinki (Finland)

    2010-10-01

    Novel hollow and solid paramecium-like hierarchical Au/Pt bimetallic nanostructures were constructed using goethite as template via a seed-mediated growth method. Transmission electron microscopy (TEM), {xi}-potential measurement, UV-vis spectroscopy, energy dispersive x-ray spectroscopy (EDS), ICP-AES measurement, x-ray powder diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) were utilized to systematically characterize the bimetallic nanostructures. It is found that the core structure of the paramecium-like bimetallic nanomaterial is closely related to reducing agent. When ascorbic acid is used as reducing agent, goethite serves as in situ sacrificed template and hollow paramecium-like bimetallic structure is obtained. When NH{sub 2}OH{center_dot}HCl is used, solid nanostructure with preserved goethite core is produced. Heating the reaction solution is necessary to obtain the paramecium-like morphology with rough interconnected Pt cilia shell. The thickness of Pt cilia layer can be controlled by adjusting the molar ratio of H{sub 2}PtCl{sub 6} to Au nanoseeds. The overgrowth of the rough Pt cilia is proposed to be via an autocatalytic and three-dimensional heterogeneous nucleation process first through flower-like morphology. Both the hollow and solid hierarchical paramecium-like Au/Pt bimetallic nanostructures show good catalytic activities.

  12. Gas-Phase Synthesis of Bimetallic Oxide Nanoparticles with Designed Elemental Compositions for Controlling the Explosive Reactivity of Nanoenergetic Materials

    Directory of Open Access Journals (Sweden)

    Ji Young Ahn

    2011-01-01

    Full Text Available We demonstrate a simple and viable method for controlling the energy release rate and pressurization rate of nanoenergetic materials by controlling the relative elemental compositions of oxidizers. First, bimetallic oxide nanoparticles (NPs with a homogeneous distribution of two different oxidizer components (CuO and Fe2O3 were generated by a conventional spray pyrolysis method. Next, the Al NPs employed as a fuel were mixed with CuO-Fe2O3 bimetallic oxide NPs by an ultrasonication process in ethanol solution. Finally, after the removal of ethanol by a drying process, the NPs were converted into energetic materials (EMs. The effects of the mass fraction of CuO in the CuO-Fe2O3 bimetallic oxide NPs on the explosive reactivity of the resulting EMs were examined by using a differential scanning calorimeter and pressure cell tester (PCT systems. The results clearly indicate that the energy release rate and pressurization rate of EMs increased linearly as the mass fraction of CuO in the CuO-Fe2O3 bimetallic oxide NPs increased. This suggests that the precise control of the stoichiometric proportions of the strong oxidizer (CuO and mild oxidizer (Fe2O3 components in the bimetallic oxide NPs is a key factor in tuning the explosive reactivity of EMs.

  13. DPC materials and corrosion environments.

    Energy Technology Data Exchange (ETDEWEB)

    Ilgen, Anastasia Gennadyevna; Bryan, Charles R.; Teich-McGoldrick, Stephanie; Hardin, Ernest

    2014-10-01

    After an exposition of the materials used in DPCs and the factors controlling material corrosion in disposal environments, a survey is given of the corrosion rates, mechanisms, and products for commonly used stainless steels. Research needs are then identified for predicting stability of DPC materials in disposal environments. Stainless steel corrosion rates may be low enough to sustain DPC basket structural integrity for performance periods of as long as 10,000 years, especially in reducing conditions. Uncertainties include basket component design, disposal environment conditions, and the in-package chemical environment including any localized effects from radiolysis. Prospective disposal overpack materials exist for most disposal environments, including both corrosion allowance and corrosion resistant materials. Whereas the behavior of corrosion allowance materials is understood for a wide range of corrosion environments, demonstrating corrosion resistance could be more technically challenging and require environment-specific testing. A preliminary screening of the existing inventory of DPCs and other types of canisters is described, according to the type of closure, whether they can be readily transported, and what types of materials are used in basket construction.

  14. Agricultural Polymers as Corrosion Inhibitors

    Science.gov (United States)

    Agricultural polymers were composed of extra-cellular polysaccharides secreted by Leuconostoc mesenteroides have been shown to inhibit corrosion on corrosion-sensitive metals. The substantially pure exopolysaccharide has a general structure consisting of alpha(1-6)-linked D-glucose backbone and appr...

  15. Microbiologically Influenced Corrosion

    Science.gov (United States)

    2015-11-05

    temporarily protective films of iron sulfides form on low-alloy steel surfaces with a conse- quent reduction in the corrosion rate. High rates of SPP...fine clay sun·ounded by a film of water. Under low flow conditions, these particles precipitate and form a sludge deposit. 27.4 TESTING 27 .4.1 A...tion of iron sulfide within a 28-day period were scored as positive for SRB. Additionally, the time required for black. ening was suggested as a

  16. INHIBITION OF CORROSION

    Science.gov (United States)

    Atherton, J.E. Jr.; Gurinsky, D.H.

    1958-06-24

    A method is described for preventing corrosion of metallic container materials by a high-temperature liquid bismuth flowing therein. The method comprises fabricating the containment means from a steel which contains between 2 and 12% chromium, between 0.5 and 1.5% of either molybdenum and silicon, and a minimum of nickel and manganese, and maintaining zirconium dissolved in the liquid bismuth at a concentration between 50 parts per million and its saturation value at the lowest temperature in the system.

  17. Fatigue and Corrosion in Metals

    CERN Document Server

    Milella, Pietro Paolo

    2013-01-01

    This textbook, suitable for students, researchers and engineers, gathers the experience of more than 20 years of teaching fracture mechanics, fatigue and corrosion to professional engineers and running experimental tests and verifications to solve practical problems in engineering applications. As such, it is a comprehensive blend of fundamental knowledge and technical tools to address the issues of fatigue and corrosion. The book initiates with a systematic description of fatigue from a phenomenological point of view, since the early signs of submicroscopic damage in few surface grains and continues describing, step by step, how these precursors develop to become mechanically small cracks and, eventually, macrocracks whose growth is governed by fracture mechanics. But fracture mechanics is also introduced to analyze stress corrosion and corrosion assisted fatigue in a rather advanced fashion. The author dedicates a particular attention to corrosion starting with an electrochemical treatment that mechanical e...

  18. IN DRIFT CORROSION PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    D.M. Jolley

    1999-12-02

    As directed by a written development plan (CRWMS M&O 1999a), a conceptual model for steel and corrosion products in the engineered barrier system (EBS) is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). This document provides the conceptual framework for the in-drift corrosion products sub-model to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. However, the concepts discussed within this report may also apply to some near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts.

  19. Synthesis of Ag-Au bimetallic film at liquid-liquid interface and its application in vapor sensing

    Energy Technology Data Exchange (ETDEWEB)

    Pasricha, Renu, E-mail: pasrichar@mail.nplindia.ernet.i [Material Characterization Division, National Physical Laboratory, New Delhi-110012 (India); Gupta, Shweta [Material Characterization Division, National Physical Laboratory, New Delhi-110012 (India); Sastry, M. [Tata Chemical Innovation Center, Anmol Pride, Baner Road, Pune-45 (India); Singh, Nahar; Gupta, Prabhat [Material Characterization Division, National Physical Laboratory, New Delhi-110012 (India)

    2010-11-30

    We demonstrate a novel process for preparing densely packed film of silver nanoparticles at the liquid-liquid interface followed by a transmetallation reaction with gold ion to yield a film of bimetallic nanoparticles. Films of assembled silver as well as Ag-Au bimetallic were characterized by UV-vis-spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. I-V measurement shows linear behavior for both the films with ca. five orders of magnitude drop in resistance for the Ag-Au bimetallic film. Temperature dependent I-V measurement revealed a semiconductor to metal transition after transmetallation reaction. The films where checked for their potential application in chemical vapor sensing to ammonia vapors.

  20. Recognition and Analysis of Corrosion Failure Mechanisms

    Directory of Open Access Journals (Sweden)

    Steven Suess

    2006-02-01

    Full Text Available Corrosion has a vast impact on the global and domestic economy, and currently incurs losses of nearly $300 billion annually to the U.S. economy alone. Because of the huge impact of corrosion, it is imperative to have a systematic approach to recognizing and mitigating corrosion problems as soon as possible after they become apparent. A proper failure analysis includes collection of pertinent background data and service history, followed by visual inspection, photographic documentation, material evaluation, data review and conclusion procurement. In analyzing corrosion failures, one must recognize the wide range of common corrosion mechanisms. The features of any corrosion failure give strong clues as to the most likely cause of the corrosion. This article details a proven approach to properly determining the root cause of a failure, and includes pictographic illustrations of the most common corrosion mechanisms, including general corrosion, pitting, galvanic corrosion, dealloying, crevice corrosion, microbiologically-influenced corrosion (MIC, corrosion fatigue, stress corrosion cracking (SCC, intergranular corrosion, fretting, erosion corrosion and hydrogen damage.

  1. A Multifunctional Coating for Autonomous Corrosion Control

    Science.gov (United States)

    Calle, Luz M.; Li, Wenyan; Buhrow, Jerry W.; Jolley, Scott t.

    2011-01-01

    Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it. The multi-functionality of the coating is based on microencapsulation technology specifically designed for corrosion control applications. This design has, in addition to all the advantages of existing microcapsulation designs, the corrosion controlled release function that triggers the delivery of corrosion indicators and inhibitors on demand, only when and where needed. Microencapsulation of self-healing agents for autonomous repair of mechanical damage to the coating is also being pursued. Corrosion indicators, corrosion inhibitors, as well as self-healing agents, have been encapsulated and dispersed into several paint systems to test the corrosion detection, inhibition, and self-healing properties of the coating. Key words: Corrosion, coating, autonomous corrosion control, corrosion indication, corrosion inhibition, self-healing coating, smart coating, multifunctional coating, microencapsulation.

  2. Investigation on Atmospheric Corrosiveness in Hainan Province

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    According to the results of four-year exposure tests for carbon steel samples in Hainan province, the influences of meteorological factors and Cl- on atmospheric corrosion were investigated. The feature of atmospheric corrosion in this area was summarized. A corrosive map for the area was drawn. The corrosion products on carbon steel at some typical places were analyzed by XRD and XPS.

  3. Corrosion Prevention and Control Applications Guide

    Science.gov (United States)

    1987-03-31

    Money, Manpower Called Keys to Progress, Aviation Week & Space Technology, October 6, 1980. 12. Reboul , M. C., Galvanic Corrosion of Aluminum, National...PA, April 1980. 25. Reboul , M.C., Galvanic Corrosion of Aluminum, National Association of Corrosion Engineers, Corrosion, V. 35#9, September 1979. 146

  4. Facile Fabrication of Composition-Tuned Ru-Ni Bimetallics in Ordered Mesoporous Carbon for Levulinic Acid Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying; Gao, Guang; Zhang, Xin; Li, Fuwei [ChinaU - Petroleum; (Chinese Aca. Sci.)

    2016-02-04

    Bimetallic catalysts are of great importance due to their unique catalytic properties. However, their conventional synthesis requires tedious multistep procedures and prolonged synthetic time, and the resulting bimetallics usually disperse unevenly and show poor stability. It is challenging to develop a facile and step-economic synthetic methodology for highly efficient bimetallic catalysts. In this study, we report an elegant metal complex-involved multicomponent assembly route to highly efficient Ru–Ni bimetallics in ordered mesoporous carbons (OMC). The fabrication of composition-tuned Ru–Ni bimetallics in OMC (RuxNi1–x–OMC, x = 0.5–0.9) was facilely realized via in situ construction of CTAB-directed cubic Ia3d chitosan-ruthenium–nickel–silica mesophase before pyrolysis and silica removal. The resulting RuxNi1–x–OMC materials are in-depth characterized with X-ray diffraction, N2 adsorption–desorption, transmission electron microscopy, infrared spectrum, and X-ray absorption fine structure. This facile fabrication method renders homogeneously dispersed Ru–Ni bimetallics embedded in the mesoporous carbonaceous framework and creates a highly active and stable Ru0.9Ni0.1–OMC catalyst for the hydrogenation of levulinic acid (LA) to prepare γ-valerolactone (GVL), a biomass-derived platform molecule with wide application in the preparation of renewable chemicals and liquid transportation fuels. A high TOF (>2000 h–1) was obtained, and the Ru0.9Ni0.1–OMC catalyst could be used at least 15 times without obvious loss of its catalytic performance.

  5. Corrosion behavior of duplex coatings

    Directory of Open Access Journals (Sweden)

    K. Raghu Ram Mohan Reddy

    2016-07-01

    Full Text Available The titanium alloys are used in defense, aerospace, automobile, chemical plants and biomedical applications due to their very high strength and lightweight properties. However, corrosion is a life-limiting factor when Ti alloys are exposed to different chemical environments at high temperatures. In the present paper, duplex NiCrAlY/WC–Co coating is coated onto Ti6Al4V substrate to investigate the corrosion behavior of both coated samples and the substrate. The duplex coating was performed with NiCrAlY as the intermediate coat of 200 μm thickness deposited by HVOF process and WC–Co ceramic top coat with varying thicknesses of 250 μm, 350 μm and 450 μm deposited by DS process. Potentiodynamic polarization tests were employed to investigate the corrosion performance of duplex coated samples and substrate in Ringer’s solution at 37 °C and pH value was set to 5.7. Finally the results reveal that 350 μm thick coated samples showed highest corrosion resistance compared to 250 μm thick samples as well as bare substrate. However, the 450 μm thick coated sample showed poor corrosion resistance compared to the substrate. The scale formed on the samples upon corrosion was characterized by using SEM analysis to understand the degree of corrosion behavior.

  6. Diffusion Coatings as Corrosion Inhibitors

    Science.gov (United States)

    Ivanov, Radoslav; Ignatova-Ivanova, Tsveteslava

    2016-03-01

    Corrosion is the cause of irretrievable loss of huge amounts of metals and alloys. The harmful effects of corrosion can be reduced significantly by applying appropriate methods of corrosion protection. One method to protect metals against corrosion is the formation of diffusion coatings on them. High corrosion resistance is typical for the boride diffusion layers. Aluminothermy is one of the main methods for diffusion saturation of the surface of metal products with various elements, including boron, and under certain conditions with aluminum, too. Samples of steel 45 were put to aluminothermic diffusion saturation with boron in a pressurized steel container at a temperature of 1100K, for 6 hours in powdered aluminothermic mixtures. The content of B2O3 in the starting mixtures decreased from the optimum - 20% to 0%, and the content of Al and the activator - (NH4)2.4BF3 is constant, respectively 7% and 0.5%. Al2O3 was used as filler. The borided samples were tested for corrosion resistance in 10% HCl for 72 hours. The results show that their corrosion resistance depends on the composition of the starting saturating mixture (mainly on the content of B2O3), and respectively on the composition, structure, thickness and degree of adhesion of the layer to the metal base.

  7. Diffusion Coatings as Corrosion Inhibitors

    Directory of Open Access Journals (Sweden)

    Ivanov Radoslav

    2016-03-01

    Full Text Available Corrosion is the cause of irretrievable loss of huge amounts of metals and alloys. The harmful effects of corrosion can be reduced significantly by applying appropriate methods of corrosion protection. One method to protect metals against corrosion is the formation of diffusion coatings on them. High corrosion resistance is typical for the boride diffusion layers. Aluminothermy is one of the main methods for diffusion saturation of the surface of metal products with various elements, including boron, and under certain conditions with aluminum, too. Samples of steel 45 were put to aluminothermic diffusion saturation with boron in a pressurized steel container at a temperature of 1100K, for 6 hours in powdered aluminothermic mixtures. The content of В2О3 in the starting mixtures decreased from the optimum - 20% to 0%, and the content of Al and the activator - (NH42.4BF3 is constant, respectively 7% and 0.5%. Al2O3 was used as filler. The borided samples were tested for corrosion resistance in 10% HCl for 72 hours. The results show that their corrosion resistance depends on the composition of the starting saturating mixture (mainly on the content of В2О3, and respectively on the composition, structure, thickness and degree of adhesion of the layer to the metal base.

  8. Corrosion protection and control using nanomaterials

    CERN Document Server

    Cook, R

    2012-01-01

    This book covers the use of nanomaterials to prevent corrosion. The first section deals with the fundamentals of corrosion prevention using nanomaterials. Part two includes a series of case studies and applications of nanomaterials for corrosion control.$bCorrosion is an expensive and potentially dangerous problem in many industries. The potential application of different nanostructured materials in corrosion protection, prevention and control is a subject of increasing interest. Corrosion protection and control using nanomaterials explores the potential use of nanotechnology in corrosion control. The book is divided into two parts. Part one looks at the fundamentals of corrosion behaviour and the manufacture of nanocrystalline materials. Chapters discuss the impact of nanotechnology in reducing corrosion cost, and investigate the influence of various factors including thermodynamics, kinetics and grain size on the corrosion behaviour of nanocrystalline materials. There are also chapters on electrodeposition ...

  9. Exploration of Cocatalyst Effects on a Bimetallic Cobalt Catalyst System: Enhanced Activity and Enantioselectivity in Epoxide Polymerization

    KAUST Repository

    Widger, Peter C. B.

    2011-07-26

    Organic ionic compounds were synthesized and investigated as cocatalysts with a bimetallic cobalt complex for enantioselective epoxide polymerization. The identities of both the cation and the anion were systematically varied, and the subsequent reactivity was studied. The nature of the ionic cocatalyst dramatically impacted the rate and enantioselectivity of the catalyst system. The ionic cocatalyst [P(N=P(N(CH2)4)3) 4 +][tBuCO2 -] in combination with a bimetallic cobalt complex produced a catalyst system that exhibited the greatest activity and selectivity for a variety of monosubstituted epoxides. © 2011 American Chemical Society.

  10. Plasmonic effects of au/ag bimetallic multispiked nanoparticles for photovoltaic applications.

    Science.gov (United States)

    Sharma, Manisha; Pudasaini, Pushpa Raj; Ruiz-Zepeda, Francisco; Vinogradova, Ekaterina; Ayon, Arturo A

    2014-09-10

    In recent years, there has been considerable interest in the use of plasmons, that is, free electron oscillations in conductors, to boost the performance of both organic and inorganic thin film solar cells. This has been driven by the possibility of employing thin active layers in solar cells in order to reduce materials costs, and is enabled by significant advances in fabrication technology. The ability of surface plasmons in metallic nanostructures to guide and confine light in the nanometer scale has opened up new design possibilities for solar cell devices. Here, we report the synthesis and characterization of highly monodisperse, reasonably stable, multipode Au/Ag bimetallic nanostructures using an inorganic additive as a ligand for photovoltaic applications. A promising surface enhanced Raman scattering (SERS) effect has been observed for the synthesized bimetallic Au/Ag multispiked nanoparticles, which compare favorably well with their Au and Ag spherical nanoparticle counterparts. The synthesized plasmonic nanostructures were incorporated on the rear surface of an ultrathin planar c-silicon/organic polymer hybrid solar cell, and the overall effect on photovoltaic performance was investigated. A promising enhancement in solar cell performance parameters, including both the open circuit voltage (VOC) and short circuit current density (JSC), has been observed by employing the aforementioned bimetallic multispiked nanoparticles on the rear surface of solar cell devices. A power conversion efficiency (PCE) value as high as 7.70% has been measured in a hybrid device with Au/Ag multispiked nanoparticles on the rear surface of an ultrathin, crystalline silicon (c-Si) membrane (∼ 12 μm). This value compares well to the measured PCE value of 6.72% for a similar device without nanoparticles. The experimental observations support the hope for a sizable PCE increase, due to plasmon effects, in thin-film, c-Si solar cells in the near future.

  11. Surface plasmon polariton assisted optical switching in noble bimetallic nanoparticle system

    Energy Technology Data Exchange (ETDEWEB)

    Dhara, Sandip, E-mail: dhara@igcar.gov.in, E-mail: chenkh@pub.iams.sinica.edu.tw [Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Lu, C.-Y.; Tu, W.-S. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Magudapathy, P. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Huang, Y.-F.; Chen, K.-H., E-mail: dhara@igcar.gov.in, E-mail: chenkh@pub.iams.sinica.edu.tw [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Center for Condensed Matter Science, National Taiwan University, Taipei 106, Taiwan (China)

    2015-01-12

    Photoresponse of bimetallic Au-Ag nanoparticle embedded soda glass (Au-Ag@SG) substrate is reported for surface plasmon assisted optical switching using 808 nm excitation. Au-Ag@SG system is made by an ion beam technique where Ag{sup +} is introduced first in the soda glass matrix by ion exchange technique. Subsequently, 400 keV Au{sup +} is implanted in the sample for different fluences, which is followed by an ion beam annealing process using 1 MeV Si{sup +} at a fixed fluence of 2 × 10{sup 16} ions·cm{sup −2}. Characteristic surface plasmon resonance (SPR) peaks around 400 and 550 nm provided evidence for the presence of Au and Ag nanoparticles. An optical switching in the Au-Ag@SG system with 808 nm, which is away from the characteristic SPR peaks of Ag and Au nanoparticles, suggests the possible role of two photon absorption (TPA) owing to the presence of interacting electric dipole in these systems. The role of surface plasmon polariton is emphasized for the propagation of electronic carrier belonging to the conduction electron of Au-Ag system in understanding the observed photoresponse. Unique excitation dependent photoresponse measurements confirm the possible role of TPA process. A competitive interband and intraband transitions in the bimetallic system of Au and Ag, which may be primarily responsible for the observation, are validated qualitatively using finite difference time domain calculations where inter-particle separation of Au and Ag plays an important role. Thus, a smart way of optical switching can be envisaged in noble bimetallic nanocluster system where long wavelength with higher skin depth can be used for communication purpose.

  12. RESOURCE-SAVING TECHNOLOGY FOR HIGH-SPEED HOT EXTRUSION OF BIMETALLIC ROD PARTS

    Directory of Open Access Journals (Sweden)

    I. V. Kachanov

    2016-01-01

    Full Text Available Processes of high-speed shaping changes and especially high-speed hot extrusion create efficient conditions for treatment of weakly plastic and poorly deformable materials which are widely used in tool making facilities. Due to the fact that high-speed stamping provides accurate billets with increased mechanical properties, it can be used as a technological process for manufacturing rod parts of die tooling operating under conditions of increased loads and wear. The purpose of the given paper is to carry out experimental investigations on the possibility to obtain a bimetallic rod tool where structural steel is considered as a basis of the tool and a working cavity is made of high-alloyed tool steel with its saving up to 90 %. A scheme of loading and geometry of conjugated surfaces of the composite billet have been developed in the paper. Technology for obtaining bimetallic rod parts of die tooling with deformation at speed of vд = 70–80 m/s and composite billet temperature of Т = (1150±20 ºС has been experimentally tested with formation of a compound due to plastic flow of two billet parts on contact surface with removal of surface oxide films. Microstructures of the bimetallic compounds obtained with the help of high-speed hot extrusion method for compositions of structural and high-alloy steels have been investigated and their high quality has been proved during the investigations. Dependences of micro-hardness distribution have been established outbound two steel contact plane in the zone of connection that are characterized by a minimum micro-hardness value in the connection joint. Availability of more plastic zone in the contact plane contributes to reduction of residual stresses due to their relaxation in this zone and higher joint strength.

  13. Comparative toxicity study of Ag, Au, and Ag-Au bimetallic nanoparticles on Daphnia magna.

    Science.gov (United States)

    Li, Ting; Albee, Brian; Alemayehu, Matti; Diaz, Rocio; Ingham, Leigha; Kamal, Shawn; Rodriguez, Maritza; Bishnoi, Sandra Whaley

    2010-09-01

    A comparative assessment of the 48-h acute toxicity of aqueous nanoparticles synthesized using the same methodology, including Au, Ag, and Ag-Au bimetallic nanoparticles, was conducted to determine their ecological effect in freshwater environments through the use of Daphnia magna, using their mortality as a toxicological endpoint. D. magna are one of the standard organisms used for ecotoxicity studies due to their sensitivity to chemical toxicants. Particle suspensions used in toxicity testing were well-characterized through a combination of absorbance measurements, atomic force or electron microscopy, flame atomic absorption spectrometry, and dynamic light scattering to determine composition, aggregation state, and particle size. The toxicity of all nanoparticles tested was found to be dose and composition dependent. The concentration of Au nanoparticles that killed 50% of the test organisms (LC(50)) ranged from 65-75 mg/L. In addition, three different sized Ag nanoparticles (diameters = 36, 52, and 66 nm) were studied to analyze the toxicological effects of particle size on D. magna; however, it was found that toxicity was not a function of size and ranged from 3-4 μg/L for all three sets of Ag nanoparticles tested. This was possibly due to the large degree of aggregation when these nanoparticles were suspended in standard synthetic freshwater. Moreover, the LC(50) values for Ag-Au bimetallic nanoparticles were found to be between that of Ag and Au but much closer to that of Ag. The bimetallic particles containing 80% Ag and 20% Au were found to have a significantly lower toxicity to Daphnia (LC(50) of 15 μg/L) compared to Ag nanoparticles, while the toxicity of the nanoparticles containing 20% Ag and 80% Au was greater than expected at 12 μg/L. The comparison results confirm that Ag nanoparticles were much more toxic than Au nanoparticles, and that the introduction of gold into silver nanoparticles may lower their environmental impact by lowering the amount

  14. Shutdown corrosion in geothermal energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, Peter F.

    1982-10-08

    Experience has shown that corrosion occurring during geothermal energy utilization system downtime--shutdown corrosion--can pose a serious threat to successful operations. Shutdown corrosion in geothermal plants appears more severe than would be expected in their nongeothermal analogs, and its mitigation may pose a severe challenge to corrosion engineering personnel. This paper presents four case histories of geothermal shutdown corrosion problems. General methods of mitigation are explored.

  15. Critical Study of Corrosion Damaged Concrete Structures

    OpenAIRE

    Sallehuddin Shah Ayop; John Cairns

    2013-01-01

    Corrosion of steel reinforcement in concrete is one of the major problems with respect to the durability of reinforced concrete structures. The degradation of the structure strength due to reinforcement corrosion decreases its design life. This paper presents the literature study on the influence of the corrosion on concrete structure starting from the mechanism of the corrosion until the deterioration stage and the structural effects of corrosion on concrete structures.

  16. Corrosion Protection of Electrically Conductive Surfaces

    OpenAIRE

    Jian Song; Liangliang Wang; Andre Zibart; Christian Koch

    2012-01-01

    The basic function of the electrically conductive surface of electrical contacts is electrical conduction. The electrical conductivity of contact materials can be largely reduced by corrosion and in order to avoid corrosion, protective coatings must be used. Another phenomenon that leads to increasing contact resistance is fretting corrosion. Fretting corrosion is the degradation mechanism of surface material, which causes increasing contact resistance. Fretting corrosion occurs when there is...

  17. Corrosion-resistant sulfur concretes

    Science.gov (United States)

    McBee, W. C.; Sullivan, T. A.; Jong, B. W.

    1983-04-01

    Sulfur concretes have been developed by the Bureau of Mines as construction materials with physical and mechanical properties that suit them for use in acid and salt corrosive environments where conventional concretes fail. Mixture design methods were established for preparing sulfur concretes using different types of aggregates and recently developed mixed-modified sulfur cements. Bench-scale testing of the sulfur concretes has shown their potential value. Corrosion resistance, strength, and durability of sulfur concrete are superior to those of conventional materials. Field in situ evaluation tests of the sulfur concretes as replacement for conventional concrete materials are in progress in corrosive areas of 24 commercial chemical, fertilizer, and metallurgical plants.

  18. Cracking and corrosion recovery boiler

    Energy Technology Data Exchange (ETDEWEB)

    Suik, H. [Tallinn Technical University, Horizon Pulp and Paper, Tallinn (Estonia)

    1998-12-31

    The corrosion of heat surfaces and the cracking the drums are the main problems of the recovery boiler. These phenomena have been appeared during long-term operation of boiler `Mitsubishi - 315` erected at 1964. Depth of the crack is depending on the number of shutdowns and on operation time. Corrosion intensity of different heat surfaces is varying depend on the metal temperature and the conditions at place of positioning of tube. The lowest intensity of corrosion is on the bank tubes and the greatest is on the tubes of the second stage superheater and on the tubes at the openings of air ports. (orig.) 5 refs.

  19. Corrosion-resistant coating development

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Kupp, D.M.; Martin, R.L. [Oak Ridge National Lab., TN (United States)

    1997-12-01

    SiC-based heat exchangers have been identified as the prime candidate material for use as heat exchangers in advanced combined cycle power plants. Unfortunately, hot corrosion of the SiC-based materials created by alkali metal salts present in the combustion gases dictates the need for corrosion-resistant coatings. The well-documented corrosion resistance of CS-50 combined with its low (and tailorable) coefficient of thermal expansion and low modulus makes CS-50 an ideal candidate for this application. Coatings produced by gelcasting and traditional particulate processing have been evaluated.

  20. Review on Stress Corrosion and Corrosion Fatigue Failure of Centrifugal Compressor Impeller

    Institute of Scientific and Technical Information of China (English)

    SUN Jiao; CHEN Songying; QU Yanpeng; LI Jianfeng

    2015-01-01

    Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

  1. Rapid dechlorination of chlorinated organic compounds by nickel/iron bimetallic system in water

    Institute of Scientific and Technical Information of China (English)

    TONG Shao-ping; WEI Hong; MA Chun-an; LIU Wei-ping

    2005-01-01

    Detoxification of chlorinated organic compounds via reaction with nickel/iron powder was implemented in aqueous solution. Compared to iron, nickel/iron bimetallic powder had higher hydrodechlorination activities for both atrazine (ATR) and p-chlorophenol (pCP); nickel/iron (2.96%, w/w) was shown to have the largest specific surface area and the optimum proportion for the dechlorination of both ATR and pCP. Electrochemical measurements showed that the adsorbed hydrogen atom on the nickel must have been the dominant reductive agent for the dechlorination of both ATR andpCP in this system.

  2. Electrical performances of pyroelectric bimetallic strip heat engines describing a Stirling cycle

    Science.gov (United States)

    Arnaud, A.; Boughaleb, J.; Monfray, S.; Boeuf, F.; Cugat, O.; Skotnicki, T.

    2015-12-01

    This paper deals with the analytical modeling of pyroelectric bimetallic strip heat engines. These devices are designed to exploit the snap-through of a thermo-mechanically bistable membrane to transform a part of the heat flowing through the membrane into mechanical energy and to convert it into electric energy by means of a piezoelectric layer deposited on the surface of the bistable membrane. In this paper, we describe the properties of these heat engines in the case when they complete a Stirling cycle, and we evaluate the performances (available energy, Carnot efficiency...) of these harvesters at the macro- and micro-scale.

  3. Enhanced antibacterial activity of bimetallic gold-silver core-shell nanoparticles at low silver concentration

    Science.gov (United States)

    Banerjee, Madhuchanda; Sharma, Shilpa; Chattopadhyay, Arun; Ghosh, Siddhartha Sankar

    2011-12-01

    Herein we report the development of bimetallic Au@Ag core-shell nanoparticles (NPs) where gold nanoparticles (Au NPs) served as the seeds for continuous deposition of silver atoms on its surface. The core-shell structure and morphology were examined by UV-Vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). The core-shell NPs showed antibacterial activity against both Gram negative (Escherichia coli and Pseudomonas aeruginosa) and Gram positive (Enterococcus faecalis and Pediococcus acidilactici) bacteria at low concentration of silver present in the shell, with more efficacy against Gram negative bacteria. TEM and flow cytometric studies showed that the core-shell NPs attached to the bacterial surface and caused membrane damage leading to cell death. The enhanced antibacterial properties of Au@Ag core-shell NPs was possibly due to the more active silver atoms in the shell surrounding gold core due to high surface free energy of the surface Ag atoms owing to shell thinness in the bimetallic NP structure.Herein we report the development of bimetallic Au@Ag core-shell nanoparticles (NPs) where gold nanoparticles (Au NPs) served as the seeds for continuous deposition of silver atoms on its surface. The core-shell structure and morphology were examined by UV-Vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). The core-shell NPs showed antibacterial activity against both Gram negative (Escherichia coli and Pseudomonas aeruginosa) and Gram positive (Enterococcus faecalis and Pediococcus acidilactici) bacteria at low concentration of silver present in the shell, with more efficacy against Gram negative bacteria. TEM and flow cytometric studies showed that the core-shell NPs attached to the bacterial surface and caused membrane damage leading to cell death. The enhanced antibacterial properties of Au@Ag core-shell NPs was

  4. Bimetallic PtxCoy nanoparticles with curved faces for highly efficient hydrogenation of cinnamaldehyde

    Science.gov (United States)

    Gu, Yan; Zhao, Yonghui; Wu, Panpan; Yang, Bo; Yang, Nating; Zhu, Yan

    2016-05-01

    The control of the curved structure of bimetallic nanocrystals is a challenge, due to the rate differential for atom deposition and surface diffusion of alien atomic species on specific crystallographic planes of seeds. Herein, we report how to tune the degree of concavity of bimetallic PtxCoy concave nanoparticles using carboxylic acids as surfactants with an oleylamine system, leading to the specific crystallographic planes being exposed. The terminal carboxylic acids with a bridge ring or a benzene ring serving as structure regulators could direct the formation of curved faces with exposed high-index facets, and long-chain saturated fatty acids favored the production of curved faces with exposed low-index facets, while long-chain olefin acids alone benefited the formation of a flat surface with exposed low-index planes. Furthermore, these PtxCoy particles with curved faces displayed superior catalytic behaviour to cinnamaldehyde hydrogenation when compared with PtxCoy with flat faces. PtxCoy nanoparticles with curved faces exhibited over 6-fold increase in catalytic activity compared to PtxNiy nanoparticles with curved faces, and near 40-fold activity increase was observed in comparison with PtxFey nanoparticles with curved faces.The control of the curved structure of bimetallic nanocrystals is a challenge, due to the rate differential for atom deposition and surface diffusion of alien atomic species on specific crystallographic planes of seeds. Herein, we report how to tune the degree of concavity of bimetallic PtxCoy concave nanoparticles using carboxylic acids as surfactants with an oleylamine system, leading to the specific crystallographic planes being exposed. The terminal carboxylic acids with a bridge ring or a benzene ring serving as structure regulators could direct the formation of curved faces with exposed high-index facets, and long-chain saturated fatty acids favored the production of curved faces with exposed low-index facets, while long

  5. Free-Standing Bimetallic Nanorings and Nanoring Arrays Made by On-Wire Lithography

    Energy Technology Data Exchange (ETDEWEB)

    Liusman, C.; Li, S. Z.; Chen, X. D.; Wei, W.; Zhang, H.; Schatz, George C.; Boey, F.; Mirkin, Chad

    2010-12-28

    This paper describes a new strategy for synthesizing free-standing bimetallic nanorings and nanoring arrays based upon on-wire lithography and a galvanic replacement reaction. The strategy allows one to tune the diameter, length, and therefore aspect ratio of the nanorings. In addition, it can be used to produce arrays of nanorings in high yield with control over number and spacing. Spectroscopic studies and discrete dipole approximation calculations show that nanoring dimers exhibit greater surface enhanced Raman scattering than the analogous nanodisk dimers.

  6. STUDY ON POLYMER- Ru- Co BIMETALLIC COMPLEXES CATALYSTS Ⅱ. X-RAY PHOTOELECTRON SPECTROSCOPIC ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    ZONG Huijuan; TANG Qi; CHEN Zonghan; JIANG Yingyan

    1991-01-01

    Polymer-Ru-Co bimetallic complexes have been examined by X-ray photoelectron spectroscopy.The catalyst is highly active only when the mole ratio of Co/Ru is 4:3. The activity of catalysts does not depend on the total Co/Ru ratio, but on the surface stoichiometry of Co and Ru. When the relative intensities of Co2p and Ru3d of XP S peaks are close to each other and both are high, the catalyst exhibits its maximum activity.The mechanism of catalytic hydroformylation has been discussed.

  7. Erosion--Corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Vyas, B.

    1978-01-01

    The deterioration of materials by corrosion or erosion by itself presents a formidable problem and for this reason investigators have studied these two phenomena independently. In fact, there are very few systematic studies on E-C and the majority of references mention it only in passing. In most real systems, however, the two destructive processes take place simultaneously, hence the purpose of this review is to present the various interactions between the chemical and mechanical agents leading to accelerated degradation of the material. The papers cited in the review are those that lead to a better understanding of the process involved in the accelerated rate of material loss under E-C conditions.

  8. Corrosion Problems in Absorption Chillers

    Science.gov (United States)

    Stetson, Bruce

    1978-01-01

    Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

  9. Greener Approach towards Corrosion Inhibition

    Directory of Open Access Journals (Sweden)

    Neha Patni

    2013-01-01

    Full Text Available Corrosion control of metals is technically, economically, environmentally, and aesthetically important. The best option is to use inhibitors for protecting metals and alloys against corrosion. As organic corrosion inhibitors are toxic in nature, so green inhibitors which are biodegradable, without any heavy metals and other toxic compounds, are promoted. Also plant products are inexpensive, renewable, and readily available. Tannins, organic amino acids, alkaloids, and organic dyes of plant origin have good corrosion-inhibiting abilities. Plant extracts contain many organic compounds, having polar atoms such as O, P, S, and N. These are adsorbed on the metal surface by these polar atoms, and protective films are formed, and various adsorption isotherms are obeyed. Various types of green inhibitors and their effect on different metals are mentioned in the paper.

  10. Accelerated corrosion test and corrosion failure distribution model of aircraft structural aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Wen-lin; MU Zhi-tao; JIN Ping

    2006-01-01

    Based on corrosion damage data of 10 years for a type of aircraft aluminum alloy, the statistical analysis was conducted by Gumbel, Normal and two parameters Weibull distribution function. The results show that aluminum alloy structural member has the corrosion history of pitting corrosion-intergranular corrosion-exfoliation corrosion, and the maximum corrosion depth is in conformity to normal distribution. The accelerated corrosion test was carried out with the complied equivalent airport accelerated environment spectrum. The corrosion damage failure modes of aluminum alloy structural member indicate that the period of validity of the former protective coating is about 2.5 to 3 years, and that of the novel protective coating is about 4.0 to 4.5 years. The corrosion kinetics law of aluminum spar flange was established by fitting corrosion damage test data. The law indicates two apparent corrosion stages of high strength aluminum alloy section material: pitting corrosion and intergranular corrosion/exfoliation corrosion.The test results agree with the statistical fit result of corrosion data collected from corrosion member in service. The fractional error is 5.8% at the same calendar year. The accelerated corrosion test validates the corrosion kinetics law of aircraft aluminum alloy in service.

  11. Electrochemical Studies of Atmospheric Corrosion.

    Science.gov (United States)

    1979-01-01

    Todynamlc polarization curves using a mod ifiedatmospheric corrosion mon i tor (ACM). Norma l Tafel behavior was observed , the limiting current for oxygen...following a suggestion of Peter Serada, who is heading a task group on time-of-wetness measurements In ASTM GO1 .04, in which the author is participating...about 5 papers except for 1968 where a symposium on atmospheric corrosion was held which resulted in the publ ication of an ASTM Special Technical

  12. Corrosion Control Anniston Army Depot

    Science.gov (United States)

    2010-02-09

    parts. • Anodize, Chrome, and Black Oxide (et.al.) • Substrate Prep and CARC paint. Stowage • Climate controlled storage (limited). • Weather...resistant (rain, uv) stowage . • Right Material – Right Time In Process Actions Bldgs 129 and 114 • Installation of new cleaning technologies for small... Rack Dehydration Prep Area CARC Application Flash-Off Oven De-mask and Anti- Corrosion App. Planned Future Actions Survey • Perform a corrosion survey

  13. Corrosion resistant neutron absorbing coatings

    Science.gov (United States)

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  14. Maintainability Improvement Through Corrosion Prediction

    Science.gov (United States)

    1997-12-01

    potential, current, pH, and chloride ion concentration were made along a simulated corrosion fatigue crack for HY80 (UNS K31820) steel in seawater...frequency range of 0.05-50 Hz, a 7075-T6 aluminium alloy and 304 and 316L stainless steels were fatigue tested in 3.0% NaCl solution. The increments...DESCRIPTORS: Conference Paper; Aluminum base alloys- Mechanical properties; Austenitic stainless steels - Mechanical properties; Corrosion fatigue

  15. Structural, electronic and adsorption properties of Rh(111)/Mo(110) bimetallic catalyst: A DFT study

    Science.gov (United States)

    Palotás, K.; Bakó, I.; Bugyi, L.

    2016-12-01

    Geometric and electronic characterizations of one monolayer rhodium with Nishiyama-Wassermann (NW) structure on Mo(110) substrate have been performed by density functional theory (DFT) calculations. In the NW structure the Rh atoms form a wavy structure propagating along the [001] direction, characterized by an amplitude of 0.26 Å in the [110] direction and by 0.10 Å in the [110] direction of the Mo(110) substrate. Strain and ligand effects operating in the rhodium film are distinguished and found to be manifested in the downward shift of the d-band center of the electron density of states (DOS) by 0.11 eV and 0.18 eV, respectively. The shift in the d-band center of Rh DOS predicts a decrease in the surface reactivity toward CO adsorption, which has been verified by detailed calculations of bond energies of CO located at on-top, bridge and hollow adsorption sites. The CO adsorption energies are decreased by about 35% compared to those reported for pure Rh(111), offering novel catalytic pathways for the molecule. An in-depth analysis of the charge transfer and the partial DOS characters upon CO adsorption on the NW-structured Rh(111)/Mo(110) bimetallic catalyst and on the pure Rh(111) surface sheds light on the bonding mechanism of CO and on the governing factors determining its lowered bond energy on the bimetallic surface.

  16. Electrocatalysis of fuel cells reaction on Pt and Pt-bimetallic anode catalysts: A selective review

    Directory of Open Access Journals (Sweden)

    Stamenković Vojislav

    2002-01-01

    Full Text Available In this review we selectively summarize recent progress, primarily from our laboratory, in the development of interrelationships between the kinetics of the fuel cells reactions and the structure/composition of anode catalysts. The focus is placed on two types of metallic surfaces: platinum single crystals and bimetallic surfaces based on Pt. In the first part it was illustrated that the hydcogen reaction is structure sensitive process, with Pt(110 being an order of magnitude more active than either of the atomically "flatter" (100 and (111 surfaces. The hydrogen reaction on Pt(hkl modified by pseudomorphic Pd (submonolayers shows the "volcano-like" behavior, having the maximum rate on Pt(111 modified by 1 ML of Pd. The Pt(111-Pd system is used to demonstrate how the energetics of intermediates formed in the hydrogen reaction is affected by interfacial bonding and energetic constraints produced between pseudomorphic Pd films and the Pt(111 substrate. In the second part it was shown that the oxidation of Ha in the presence of CO occurs concurrently with CO oxidation on Pt and Pt bimetallic surfaces. The Pt-Ru system is used to demonstrate that both the bifunctional effect and the ligand effect contribute to the influence of Ru on the CO oxidation rate and for Hz oxidation process in the presence of CO. The knowledge is then used to create the real-life catalyst with the catalytic activities which are, to the greatest extend possible similar to the tailor-made surface.

  17. Photochemical synthesis of mono and bimetallic nanoparticles and their use in catalysis

    Science.gov (United States)

    Pardoe, Andrea

    2011-07-01

    Nanomaterials have become a popular topic of research over the years because of their many important applications. It can be a challenge to stabilize the particles at a nanometer size, while having control over their surface features. Copper nanoparticles were synthesized photochemically using a photogenerated radical allowing spatial and temporal control over their formation. The synthesis was affected by the stabilizers used, which changed the size, dispersity, rate of formation, and oxidation rate. Copper nanoparticles suffer from their fast oxidation in air, so copper-silver bimetallic nanoparticles were synthesized in attempts to overcome the oxidation of copper nanoparticles. Bimetallic nanoparticles were synthesized, but preventing the oxidation of the copper nanoparticles proved difficult. One important application of nanoparticles that was explored here is in catalyzing organic reactions. Because of the fast oxidation of copper nanoparticles, silver nanoparticles were synthesized photochemically on different supports including TiO2 and hydrotalcite (HTC). Their catalytic efficiency was tested using alcohol oxidations. Different silver nanoparticle shapes (decahedra and plates) were compared with the spheres to see the different catalytic efficiencies.

  18. High strength bimetallic composite material fabricated by electroslag casting and characteristics of its composite interface

    Directory of Open Access Journals (Sweden)

    Tian-shun Dong

    2016-11-01

    Full Text Available Bimetallic composite material of bainitic steel and PD3 steel was produced with electroslag casting process, and element distribution of its composite interface was investigated by theoretical calculation and energy dispersive spectrometer (EDS. Results show that the tensile strength (1,450 MPa, hardness (HRC 41-47 and impact toughness (94.7J·cm-2 of bainitic steel were comparatively high, while its elongation was slightly low (4.0%. Tensile strength (1,100 MPa, hardness (>HRC 31 and elongation (7.72% of the interface were also relatively high, but its impact toughness was low at 20.4 J·cm-2. Results of theoretical calculation of the element distribution in the interface region were basically consistent with that of EDS. Therefore, electroslag casting is a practical process to produce bimetallic composite material of bainitic steel and PD3 steel, and theoretical calculation also is a feasible method to study element distribution of their interface.

  19. Using supported Au nanoparticles as starting material for preparing uniform Au/Pd bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Villa, Alberto [Universita di Milano, Italy; Prati, Laura [Universita di Milano, Italy; Su, Dangshen [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Wang, Di [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Veith, Gabriel M [ORNL

    2010-01-01

    One of the best methods for producing bulk homogeneous (composition) supported bimetallic AuPd clusters involves the immobilization of a protected Au seed followed by the addition of Pd. This paper investigates the importance of this gold seed in controlling the resulting bimetallic AuPd clusters structures, sizes and catalytic activities by investigating three different gold seeds. Uniform Au-Pd alloy were obtained when a steric/electrostatic protecting group, poly(vinyl alcohol) (PVA), was used to form the gold clusters on activated carbon (AC). In contrast Au/AC precursors prepared using Au nanoparticles with only electrostatic stabilization (tetrakis(hydroxypropyl)phosphonium chloride (THPC)), or no stabilization (magnetron sputtering) produced inhomogeneous alloys and segregation of the gold and palladium. The uniform alloyed catalyst (Pd{at}Au{sub PVA}/AC) is the most active and selective catalyst, while the inhomogenous catalysts are less active and selective. Further study of the PVA protected Au clusters revealed that the amount of PVA used is also critical for the preparation of uniform alloyed catalyst, their stability, and their catalytic activity.

  20. Structure analysis of bimetallic Co–Au nanoparticles formed by sequential ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hua-jian [Hubei province Key Laboratory of Systems Science in Metallurgical Process, Wuhan University of Science and Technology, Wuhan 430081 (China); Wang, Yu-hua, E-mail: wangyuhua@wust.edu.cn [Hubei province Key Laboratory of Systems Science in Metallurgical Process, Wuhan University of Science and Technology, Wuhan 430081 (China); Zhang, Xiao-jian [Hubei province Key Laboratory of Systems Science in Metallurgical Process, Wuhan University of Science and Technology, Wuhan 430081 (China); Song, Shu-peng [State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Chen, Hong; Zhang, Ke; Xiong, Zu-zhao; Ji, Ling-ling; Dai, Hou-mei; Wang, Deng-jing; Lu, Jian-duo; Wang, Ru-wu [Hubei province Key Laboratory of Systems Science in Metallurgical Process, Wuhan University of Science and Technology, Wuhan 430081 (China); Zheng, Li-rong [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2016-08-15

    Highlights: • Co–Au alloy Metallic nanoparticles (MNPs) are formed by ion implantation in silica glass. • The ion ranges of Au ions implantation process have been displayed to show the ion distribution. • EXAFS, AFM and TEM have been used to study the local structural information of imetallic nanoparticles. • With the increase of Au ion implantation, the local environments of Co ions are changed enormously. Three oscillations are determined. - Abstract: Co–Au alloy Metallic nanoparticles (MNPs) are formed by sequential ion implantation of Co and Au into silica glass at room temperature. The ion ranges of Au ions implantation process have been displayed to show the ion distribution. We have used the atomic force microscopy (AFM) and transmission electron microscopy (TEM) to investigate the formation of bimetallic nanoparticles. The extended X-ray absorption fine structure (EXAFS) has been used to study the local structural information of bimetallic nanoparticles. With the increase of Au ion implantation, the local environments of Co ions are changed enormously. Hence, three oscillations, respectively, Co–O, Co–Co and Co–Au coordination are determined.

  1. Selective hydrogenation of citral over Au-based bimetallic catalysts in supercritical carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Selective hydrogenation of citral was investigated over Au-based bimetallic catalysts in the environmentally benign supercritical carbon dioxide (scCO2) medium.The catalytic performances were different in citral hydrogenation when Pd or Ru was mixed (physically and chemically) with Au.Compared with the corresponding monometallic catalyst,the total conversion and the selectivity to citronellal (CAL) were significantly enhanced over TiO2 supported Pd and Au bimetallic catalysts (physically and chemically mixed);however,the conversion and selectivity did not change when Ru was physically mixed with Au catalyst compared to the monometallic Ru/TiO2,and the chemically mixed Ru-Au/TiO2 catalyst did not show any activity.The effect of CO2 pressure on the conversion of citral and product selectivity was significantly different over the Au/TiO2,Pd-Au/TiO2,and Pd/TiO2 catalysts.It was assumed to be ascribed to the difference in the interactions between Au,Pd nanoparticles and CO2 under different CO2 pressures.

  2. On Metal Segregation of Bimetallic Nanocatalysts Prepared by a One-Pot Method in Microemulsions

    Directory of Open Access Journals (Sweden)

    Concha Tojo

    2017-02-01

    Full Text Available A comparative study on different bimetallic nanocatalysts prepared from microemulsions using a one-pot method has been carried out. The analysis of experimental observations, complemented by simulation studies, provides detailed insight into the factors affecting nanoparticle architecture: (1 The metal segregation in a bimetallic nanocatalysts is the result of the combination of three main kinetic parameters: the reduction rate of metal precursors (related to reduction standard potentials, the material intermicellar exchange rate (determined by microemulsion composition, and the metal precursors concentration; (2 A minimum difference between the reduction standard potentials of the two metals of 0.20 V is needed to obtain a core-shell structure. For values ∆ε0 smaller than 0.20 V the obtaining of alloys cannot be avoided, neither by changing the microemulsion nor by increasing metal concentration; (3 As a rule, the higher the film flexibility around the micelles, the higher the degree of mixture in the nanocatalyst; (4 A minimum concentration of metal precursors is required to get a core-shell structure. This minimum concentration depends on the microemulsion flexibility and on the difference in reduction rates.

  3. Bimetallic oxamato complexes synthesized into mesoporous matrix as precursor to tunable nanosized oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kalinke, Lucas H.G. [Instituto de Química, Universidade Federal de Goiás—UFG, Goiânia, GO 74001-970 (Brazil); Instituto Federal de Goiás—IFG, Anápolis, GO (Brazil); Stumpf, Humberto O. [Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais—UFMG, Belo Horizonte, MG (Brazil); Mazali, Italo O. [Instituto de Química, Universidade Estadual de Campinas—UNICAMP, Campinas, SP (Brazil); Cangussu, Danielle, E-mail: danielle_cangussu@ufg.br [Instituto de Química, Universidade Federal de Goiás—UFG, Goiânia, GO 74001-970 (Brazil)

    2015-10-15

    Highlights: • The bimetallic oxamato complexes as single-source precursor. • We prepared into a porous silica glass tunable nanosized oxide powders. • X-ray diffraction shows the formation of CeO{sub 2}/CuO and spinel cobaltite. • The different number of IDC allows control of the nanoparticle size. - Abstract: The bimetallic complexes were employed to prepare into a porous silica glass tunable nanosized oxide powders through the single source precursor (SSP) method. These materials were prepared by first anchoring of [Cu(opba)]{sup 2−} [opba = ortho-phenylenebis(oxamato)], second by reaction in situ with second metal [Co(II) or Ce(III)] and followed by a thermal treatment. The different number of impregnation–decomposition cycles (IDC) allows control of the nanoparticle size. X-ray diffraction shows the formation of mixture CeO{sub 2}–CuO and spinel copper cobaltite. Raman spectroscopy confirmed the formation of such phases. Transmission electron microscopy images revealed that spinel cobaltite particles (8 IDC) present a mean size of about 9 nm, whereas for the CeO{sub 2}–CuO phase the particle diameters are 4 nm (2 IDC) and 8 nm (6 IDC). For CeO{sub 2}–CuO the diffuse reflectance spectroscopy indicates a consistent red shift in band gap from 3.41 to 2.87 eV with increasing of particle size due to quantum confinement effect.

  4. First principles investigations of small bimetallic PdGa clusters as catalysts for hydrogen dissociation

    Science.gov (United States)

    Kaul, Indu; Ghosh, Prasenjit

    2017-04-01

    Using first principles density functional theory based calculations, we have studied hydrogen dissociation on sub nanometer bimetallic clusters formed from d-block (Pd) and p-block (Ga) elements in gas phase to explore the feasibility of using them as cheap catalysts for hydrogen dissociation. Our calculations show that the dimers, trimers and tetramers of these clusters are thermodynamically more stable than the pure ones for all Ga concentrations. For a given cluster size, we find that the clusters containing equal amount of Pd and Ga are the most stable ones. In contrast to bulk PdGa, the contribution of Pd-d states to the highest occupied molecular orbitals of the bimetallic clusters are either very small or absent. Study of adsorption of hydrogen molecule on these clusters show that hydrogen binds in an activated form only on the Pd rich clusters. From the calculations of hydrogen dissociation barriers on tetramers of pure Pd, 25% Ga (Pd3Ga) and 50% Ga (Pd2Ga2) we find that Pd3Ga is the most efficient catalyst for hydrogen dissociation with barriers even lower than that on the PdGa surfaces.

  5. Enhancement of Hydrogen Storage Behavior of Complex Hydrides via Bimetallic Nanocatalysts Doping

    Directory of Open Access Journals (Sweden)

    Prakash C. Sharma

    2012-10-01

    Full Text Available Pristine complex quaternary hydride (LiBH4/2LiNH2 and its destabilized counterpart (LiBH4/2LiNH2/nanoMgH2 have recently shown promising reversible hydrogen storage capacity under moderate operating conditions. The destabilization of complex hydride via nanocrystalline MgH2 apparently lowers the thermodynamic heat values and thus enhances the reversible hydrogen storage behavior at moderate temperatures. However, the kinetics of these materials is rather low and needs to be improved for on-board vehicular applications. Nanocatalyst additives such as nano Ni, nano Fe, nano Co, nano Mn and nano Cu at low concentrations on the complex hydride host structures have demonstrated a reduction in the decomposition temperature and overall increase in the hydrogen desorption reaction rates. Bi-metallic nanocatalysts such as the combination of nano Fe and nano Ni have shown further pronounced kinetics enhancement in comparison to their individual counterparts. Additionally, the vital advantage of using bi-metallic nanocatalysts is to enable the synergistic effects and characteristics of the two transitional nanometal species on the host hydride matrix for the optimized hydrogen storage behavior.

  6. A bimetallic nanocomposite electrode for direct and rapid biosensing of p53 DNA plasmid

    Indian Academy of Sciences (India)

    Ezat Hamidi-Asl; Jahan-Bakhsh Raoof; Nahid Naghizadeh; Simin Sharifi; Mohammad Saeid Hejazi

    2015-09-01

    A new label-free electrochemical DNA biosensor is presented based on carbon paste electrode (CPE) modified with gold (Au) and platinum (Pt) nanoparticles to prepare the bimetallic nanocomposite electrode. The proposed sensor was made by immobilization of 15-mer single stranded oligonucleotide probe related to p53 gene for detection of DNA plasmid samples. The hybridization detection relied on the alternation in the guanine oxidation signal following hybridization of the probe with complementary genomic DNA.The technique of differential pulse voltammetry (DPV) was used for monitoring guanine oxidation. To optimize the performance of the modified CPE, different electrodes were prepared in various percentages of Au and Pt nanoparticles. The modified electrode containing 15% Au/Pt bimetallic nanoparticles (15% Au/Pt-MCPE) was selected as the best working electrode. The selectivity of the sensor was investigated using plasmid samples containing non-complementary oligonucleotides. The detection limit of the biosensor was studied and calculated to be 53.10 pg L−1.

  7. Ag-Cu Bimetallic Nanoparticles Prepared by Microemulsion Method as Catalyst for Epoxidation of Styrene

    Directory of Open Access Journals (Sweden)

    Hong-Kui Wang

    2012-01-01

    Full Text Available Ag/Cu bimetallic nanocatalysts supported on reticulate-like γ-alumina were prepared by a microemulsion method using N2H4·H2O as the reducing agent. The catalysts were activated by calcination followed with hydrogen reduction at 873K, and the properties were confirmed using various characterization techniques. Compared with metal oxides particles, Ag-Cu particles exhibited smaller sizes (<5 nm after calcination in H2 at 873K. XPS results indicated that the binding energies changed with the Ag/Cu ratios, suggesting that increasing the copper content gave both metals a greater tendency to lose electrons. Furthermore, Ag-Cu bimetallic nanoparticles supported on γ-alumina showed better catalytic activity on the epoxidation of styrene as compared with the corresponding monometallic silver or copper. The styrene oxide selectivity could reach 76.6% at Ag/Cu molar ratio of 3/1, while the maximum conversion (up to 94.6% appeared at Ag/Cu molar ratio of 1/1 because of the maximum interaction between silver and copper.

  8. Enantioselective polymerization of epoxides using biaryl-linked bimetallic cobalt catalysts: A mechanistic study

    KAUST Repository

    Ahmed, Syud M.

    2013-12-18

    The enantioselective polymerization of propylene oxide (PO) using biaryl-linked bimetallic salen Co catalysts was investigated experimentally and theoretically. Five key aspects of this catalytic system were examined: (1) the structural features of the catalyst, (2) the regio- and stereoselectivity of the chain-growth step, (3) the probable oxidation and electronic state of Co during the polymerization, (4) the role of the cocatalyst, and (5) the mechanism of monomer enchainment. Several important insights were revealed. First, density functional theory (DFT) calculations provided detailed structural information regarding the regio- and stereoselective chain-growth step. Specifically, the absolute stereochemistry of the binaphthol linker determines the enantiomer preference in the polymerization, and the interaction between the salen ligand and the growing polymer chain is a fundamental aspect of enantioselectivity. Second, a new bimetallic catalyst with a conformationally flexible biphenol linker was synthesized and found to enantioselectively polymerize PO, though with lower enantioselectivity than the binaphthol linked catalysts. Third, DFT calculations revealed that the active form of the catalyst has two active exo anionic ligands (chloride or carboxylate) and an endo polymer alkoxide which can ring-open an adjacent cobalt-coordinated epoxide. Fourth, calculations showed that initiation is favored by an endo chloride ligand, while propagation is favored by the presence of two exo carboxylate ligands. © 2013 American Chemical Society.

  9. Properties of two-dimensional insulators: A DFT study of bimetallic oxide CrW2O9 clusters adsorption on MgO ultrathin films

    Science.gov (United States)

    Zhu, Jia; Zhang, Hui; Zhao, Ling; Xiong, Wei; Huang, Xin; Wang, Bin; Zhang, Yongfan

    2016-08-01

    Periodic density functional theory calculations have been performed to study the electronic properties of bimetallic oxide CrW2O9 clusters adsorbed on MgO/Ag(001) ultrathin films (activities with respect to that of pure W3O9 clusters. As a consequence, present results reveal that the adsorption of bimetallic oxide CrW2O9 clusters on the MgO/Ag(001) ultrathin films provide a new perspective to tune and modify the properties and chemical reactivity of bimetallic oxide adsorbates as a function of the thickness of the oxide films.

  10. Core-shell Rh-Pt nanocubes: A model for studying compressive strain effects in bimetallic nanocatalysts

    Science.gov (United States)

    Harak, Ethan William

    Shape-controlled bimetallic nanocatalysts often have increased activities and stabilities over their monometallic counterparts due to surface strain effects and electron transfer between the two metals. Here, we demonstrate that the degree of surface strain can be manipulated in shape-controlled nanocrystals through a bimetallic core shell architecture. This ability is achieved in a model core shell Rh Pt nanocube system through control of shell thickness. An increase in the Pt shell thickness leads to more compressive strain, which can increase the Pt 4f7/2 binding energy by as much as 0.13 eV. This change in electronic structure is correlated with a weakening of surface-adsorbate interactions, which we exploit to reduce catalyst poisoning by CO during formic acid electrooxidation. In fact, by precisely controlling the Pt shell thickness, the maximum current density achieved with Rh Pt nanocubes was 3.5 times greater than that achieved with similarly sized Pt nanocubes, with decreased CO generation as well. This system serves as a model for how bimetallic architectures can be used to manipulate the electronic structure of nanoparticle surfaces for efficient catalysis. The strategy employed here should enable the performance of bimetallic nanomaterials comprised of more cost-effective metals to be enhanced as well.

  11. Preparation of Au-Pd bimetallic nanoparticles in porous germania nanospheres: A study of their morphology and catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Regan, Maureen R. [Department of Chemistry, Fordham University, 441, East Fordham Road, Bronx, NY 10458 (United States); Banerjee, Ipsita A. [Department of Chemistry, Fordham University, 441, East Fordham Road, Bronx, NY 10458 (United States)]. E-mail: banerjee@fordham.edu

    2006-03-15

    Size controlled Au-Pd bimetallic nanoparticles with an average size of 7-10 nm were grown in porous germania nanospheres. The properties of the resulting nanocomposites were characterized by electron microscopy, energy dispersive spectroscopy, and ultraviolet-visible spectroscopy. The catalytic activity of the nanocomposites was also examined by studying the degradation of p-nitroaniline.

  12. Influence of the Au/Ag ratio on the catalytic activity of dendrimer-encapsulated bimetallic nanoparticles in microreactors

    NARCIS (Netherlands)

    Ricciardi, R.; Huskens, J.; Verboom, W.

    2015-01-01

    Dendrimer-encapsulated Au/Ag alloy nanoparticles (Au/Ag DENs) were covalently attached to a monolayer-functionalized inner surface of glass microreactors. The influence of the bimetallic alloy structure and of the different metal ratios was investigated for the reduction of 4-nitrophenol using NaBH4

  13. Effect of mono- and bimetallic nanoparticles Fe, Ni, & Fe/Ni based on carbon nanocomposites on electrocatalytic properties of anodes

    Science.gov (United States)

    Ranabhat, K.; Pylinina, A. I.; Skripkin, K. S.; Sofronova, E. A.; Revina, A. A.; Kasatkin, V. E.; Patrikeev, L. N.; Lapshinsky, V. A.

    2016-10-01

    The optical properties of metallic Fe nanoparticles (NPs), Ni NPs and bimetallic Fe/Ni NPs produced under radiolysis in anaerobic condition based on a chemical reduction in the presence of oxygen and quercetin in reversed micellar solutions, and electrokinetic properties of nanoparticles carbon-based nanocomposites were studied. The possibility of the preparation of coating using different nanocomposites with anomalous electrocatalytic is addressed.

  14. Migrating corrosion inhibitor protection of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Bjegovic, D.; Miksic, B.

    1999-11-01

    Migrating corrosion inhibitors (MCI) were developed to protect steel rebar from corrosion in concrete. They were designed to be incorporated as an admixture during concrete batching or used for surface impregnation of existing concrete structures. Two investigations are summarized. One studied the effectiveness of MCIs as a corrosion inhibitor for steel rebar when used as an admixture in fresh concrete mix. The other is a long-term study of MCI concrete impregnation that chronicles corrosion rates of rebar in concrete specimens. Based on data from each study, it was concluded that migrating corrosion inhibitors are compatible with concrete and effectively delay the onset of corrosion.

  15. Solutions of corrosion Problems in advanced Technologies

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Karlsson, Asger

    1999-01-01

    Austenitic and ferritic steels were exposed in the superheater area of a straw-fired CHP plant. The specimens were exposed for 1400 hours at 450-600°C. The rate of corrosion was assessed based on unattacked metal remaining. The corrosion products and course of corrosion for the various steel types...... were investigated using light optical and scanning electron microscopy. The ferritic steels suffered from corrosion mainly via material loss. The austenitic steels suffered from predominantly selective corrosion resulting in chromium depletion from the alloy. A clear trend was observed that selective...... corrosion increased with increasing chromium content of the alloy....

  16. Corrosion behavior of corrosion resistant alloys in stimulation acids

    Energy Technology Data Exchange (ETDEWEB)

    Cheldi, Tiziana [ENI E and P Division, 20097 San Donato Milanese Milano (Italy); Piccolo, Eugenio Lo; Scoppio, Lucrezia [Centro Sviluppo Materiali, via Castel Romano 100, 00128 Rome (Italy)

    2004-07-01

    In the oil and gas industry, selection of CRAs for downhole tubulars is generally based on resistance to corrosive species in the production environment containing CO{sub 2}, H{sub 2}S, chloride and in some case elemental sulphur. However, there are non-production environments to which these materials must also be resistant for either short term or prolonged duration; these environments include stimulation acids, brine and completion fluids. This paper reports the main results of a laboratory study performed to evaluate the corrosion and stress corrosion behaviour to the acidizing treatments of the most used CRAs for production tubing and casing. Laboratory tests were performed to simulate both 'active' and 'spent' acids operative phases, selecting various environmental conditions. The selected steel pipes were a low alloyed steel, martensitic, super-martensitic, duplex 22 Cr, superduplex 25 Cr and super-austenitic stainless steels (25 Cr 35 Ni). Results obtained in the 'active' acid environments over the temperature range of 100-140 deg. C, showed that the blend acids with HCl at high concentration and HCl + HF represented too much severe conditions, where preventing high general corrosion and heavy localised corrosion by inhibition package becomes very difficult, especially for duplex steel pipe, where, in some case, the specimens were completely dissolved into the solution. On the contrary, all steels pipes were successfully protected by inhibitor when organic acid solution (HCOOH + CH{sub 3}COOH) were used. Furthermore, different effectiveness on corrosion protection was showed by the tested inhibitors packages: e.g. in the 90% HCl at 12% + 10 CH{sub 3}COOH acid blend. In 'spent' acid environments, all steel pipes showed to be less susceptible to the localised and general corrosion attack. Moreover, no Sulphide Stress Corrosion Cracking (SSC) was observed. Only one super-austenitic stainless steel U-bend specimen showed

  17. General Corrosion and Localized Corrosion of the Drip Shield

    Energy Technology Data Exchange (ETDEWEB)

    F. Hua

    2004-09-16

    The repository design includes a drip shield (BSC 2004 [DIRS 168489]) that provides protection for the waste package both as a barrier to seepage water contact and a physical barrier to potential rockfall. The purpose of the process-level models developed in this report is to model dry oxidation, general corrosion, and localized corrosion of the drip shield plate material, which is made of Ti Grade 7. This document is prepared according to ''Technical Work Plan For: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The models developed in this report are used by the waste package degradation analyses for TSPA-LA and serve as a basis to determine the performance of the drip shield. The drip shield may suffer from other forms of failure such as the hydrogen induced cracking (HIC) or stress corrosion cracking (SCC), or both. Stress corrosion cracking of the drip shield material is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]). Hydrogen induced cracking of the drip shield material is discussed in ''Hydrogen Induced Cracking of Drip Shield'' (BSC 2004 [DIRS 169847]).

  18. Corrosion of steel structures in sea-bed sediment

    Indian Academy of Sciences (India)

    Xiutong Wang; Jizhou Duan; Yan Li; Jie Zhang; Shide Ma; Baorong Hou

    2005-04-01

    Seabed sediment (SBS) is a special soil that is covered by seawater. With the developments in marine oil exploitation and engineering, more and more steel structures have been buried in SBS. SBS corrosion has now become a serious problem in marine environment and an important issue in corrosion science. In this paper, approach in the field of SBS corrosion is reviewed. Electrochemical and microbial corrosion factors, corrosion mechanism, measurement of metal corrosion rate, corrosion evaluation and prediction of corrosion are also discussed here.

  19. Report on accelerated corrosion studies.

    Energy Technology Data Exchange (ETDEWEB)

    Mowry, Curtis Dale; Glass, Sarah Jill; Sorensen, Neil Robert

    2011-03-01

    Sandia National Laboratories (SNL) conducted accelerated atmospheric corrosion testing for the U.S. Consumer Product Safety Commission (CPSC) to help further the understanding of the development of corrosion products on conductor materials in household electrical components exposed to environmental conditions representative of homes constructed with problem drywall. The conditions of the accelerated testing were chosen to produce corrosion product growth that would be consistent with long-term exposure to environments containing humidity and parts per billion (ppb) levels of hydrogen sulfide (H{sub 2}S) that are thought to have been the source of corrosion in electrical components from affected homes. This report documents the test set-up, monitoring of electrical performance of powered electrical components during the exposure, and the materials characterization conducted on wires, screws, and contact plates from selected electrical components. No degradation in electrical performance (measured via voltage drop) was measured during the course of the 8-week exposure, which was approximately equivalent to 40 years of exposure in a light industrial environment. Analyses show that corrosion products consisting of various phases of copper sulfide, copper sulfate, and copper oxide are found on exposed surfaces of the conductor materials including wires, screws, and contact plates. The morphology and the thickness of the corrosion products showed a range of character. In some of the copper wires that were observed, corrosion product had flaked or spalled off the surface, exposing fresh metal to the reaction with the contaminant gasses; however, there was no significant change in the wire cross-sectional area.

  20. Corrosion in Electronic Devices and Sensors to Prevent Corrosion

    Directory of Open Access Journals (Sweden)

    Siddharth Dev

    2014-02-01

    Full Text Available Many types of metal and alloys are used in various electronic devices and components like computers, microchips, printed circuit board (PCB, integrated circuits, transistors, and diodes etc. Such components have variety of applications in the field of medical, aerospace, automotive sectors, telecommunication and defense. These components are exposed to different types of environments. The increased used of electronics has also increased the demand for reliability. The size of electronic equipment is also very significant parameter and it has been decreasing presently at a faster rate. The smaller size of equipment has undetectable failures. Though the corrosion taking place in electronic components is generally of micro level which can not be detected easily but the services of device are seized. The paper deals with the various types of corrosion in electronic components as a case study and an approach towards development of some sensor for corrosion monitoring.

  1. Bimetallic Catalysts and Platinum Surfaces Studied by X-ray Absorption Spectroscopy and Scanning Tunnelling Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roenning, Magnus

    2000-07-01

    Bimetallic catalyst systems used in Fischer-Tropsch synthesis (Co-Re/Al{sub 2}O{sub 3}) and in the naphtha reforming process (Pt-Re/Al{sub 2}O{sub 3}) have been studied in situ using X-ray absorption spectroscopy (EXAFS). Additionally, the adsorption of ethene on platinum single crystal surfaces has been investigated using scanning tunnelling microscopy. In situ EXAFS at the cobalt K absorption edge have been carried out at 450{sup o}C on the hydrogen reduction of a rhenium-promoted Co{sub 3}O{sub 4}/Al{sub 2}O{sub 3} catalyst. Reductions carried out using 100% hydrogen and 5% hydrogen in helium gave different results. Whereas the reduction using dilute hydrogen leads to bulk-like metallic cobalt particles (hcp or fcc), reaction with pure hydrogen yields a more dispersed system with smaller cobalt metal particles (< 40 A). The results are rationalised in terms of different degrees of reoxidation of cobalt by the higher and lower concentrations of water generated during the reduction of cobalt oxide by 100% and 5% hydrogen, respectively. Additionally, in both reduction protocols a small fraction (3 -4 wt%) of the cobalt content is randomly dispersed over the tetrahedral vacancies of the alumina support. This dispersion occurs during reduction and not calcination. The cobalt in these sites cannot be reduced at 450 {sup o}C. The local environments about the rhenium atoms in Co-Re/{gamma}-A1{sub 2}O{sub 3} catalyst after different reduction periods have been studied by X-ray absorption spectroscopy. A bimetallic catalyst containing 4.6 wt% cobalt and 2 wt% rhenium has been compared with a corresponding monometallic sample with 2 wt% rhenium on the same support. The rhenium L{sub III} EXAFS analysis shows that bimetallic particles are formed after reduction at 450{sup o}C with the average particle size being 10-15 A. Rhenium is shown to be reduced at a later stage than cobalt. The fraction of cobalt atoms entering the support obstructs the access to the support for the

  2. Bimetallic Catalysts and Platinum Surfaces Studied by X-ray Absorption Spectroscopy and Scanning Tunnelling Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roenning, Magnus

    2000-07-01

    Bimetallic catalyst systems used in Fischer-Tropsch synthesis (Co-Re/Al{sub 2}O{sub 3}) and in the naphtha reforming process (Pt-Re/Al{sub 2}O{sub 3}) have been studied in situ using X-ray absorption spectroscopy (EXAFS). Additionally, the adsorption of ethene on platinum single crystal surfaces has been investigated using scanning tunnelling microscopy. In situ EXAFS at the cobalt K absorption edge have been carried out at 450{sup o}C on the hydrogen reduction of a rhenium-promoted Co{sub 3}O{sub 4}/Al{sub 2}O{sub 3} catalyst. Reductions carried out using 100% hydrogen and 5% hydrogen in helium gave different results. Whereas the reduction using dilute hydrogen leads to bulk-like metallic cobalt particles (hcp or fcc), reaction with pure hydrogen yields a more dispersed system with smaller cobalt metal particles (< 40 A). The results are rationalised in terms of different degrees of reoxidation of cobalt by the higher and lower concentrations of water generated during the reduction of cobalt oxide by 100% and 5% hydrogen, respectively. Additionally, in both reduction protocols a small fraction (3 -4 wt%) of the cobalt content is randomly dispersed over the tetrahedral vacancies of the alumina support. This dispersion occurs during reduction and not calcination. The cobalt in these sites cannot be reduced at 450 {sup o}C. The local environments about the rhenium atoms in Co-Re/{gamma}-A1{sub 2}O{sub 3} catalyst after different reduction periods have been studied by X-ray absorption spectroscopy. A bimetallic catalyst containing 4.6 wt% cobalt and 2 wt% rhenium has been compared with a corresponding monometallic sample with 2 wt% rhenium on the same support. The rhenium L{sub III} EXAFS analysis shows that bimetallic particles are formed after reduction at 450{sup o}C with the average particle size being 10-15 A. Rhenium is shown to be reduced at a later stage than cobalt. The fraction of cobalt atoms entering the support obstructs the access to the support for the

  3. Synergy effect of naphthenic acid corrosion and sulfur corrosion in crude oil distillation unit

    Science.gov (United States)

    Huang, B. S.; Yin, W. F.; Sang, D. H.; Jiang, Z. Y.

    2012-10-01

    The synergy effect of naphthenic acid corrosion and sulfur corrosion at high temperature in crude oil distillation unit was studied using Q235 carbon-manganese steel and 316 stainless steel. The corrosion of Q235 and 316 in corrosion media containing sulfur and/or naphthenic acid at 280 °C was investigated by weight loss, scanning electron microscope (SEM), EDS and X-ray diffractometer (XRD) analysis. The results showed that in corrosion media containing only sulfur, the corrosion rate of Q235 and 316 first increased and then decreased with the increase of sulfur content. In corrosion media containing naphthenic acid and sulfur, with the variations of acid value or sulfur content, the synergy effect of naphthenic acid corrosion and sulfur corrosion has a great influence on the corrosion rate of Q235 and 316. It was indicated that the sulfur accelerated naphthenic acid corrosion below a certain sulfur content but prevented naphthenic acid corrosion above that. The corrosion products on two steels after exposure to corrosion media were investigated. The stable Cr5S8 phases detected in the corrosion products film of 316 were considered as the reason why 316 has greater corrosion resistance to that of Q235.

  4. Quantitative measures of corrosion and prevention: application to corrosion in agriculture

    NARCIS (Netherlands)

    Schouten, J.C.; Gellings, P.J.

    1987-01-01

    The corrosion protection factor (c.p.f.) and the corrosion condition (c.c.) are simple instruments for the study and evaluation of the contribution and efficiency of several methods of corrosion prevention and control. The application of c.p.f. and c.c. to corrosion and prevention in agriculture in

  5. Corrosion effects on friction factors

    Energy Technology Data Exchange (ETDEWEB)

    Magleby, H.L.; Shaffer, S.J.

    1996-03-01

    This paper presents the results of NRC-sponsored material specimen tests that were performed to determine if corrosion increases the friction factors of sliding surfaces of motor-operated gate valves, which could require higher forces to close and open safety-related valves when subjected to their design basis differential pressures. Friction tests were performed with uncorroded specimens and specimens subjected to accelerated corrosion. Preliminary tests at ambient conditions showed that corrosion increased the friction factors, indicating the need for additional tests duplicating valve operating parameters at hot conditions. The additional tests showed friction factors of corroded specimens were 0.1 to 0.2 higher than for uncorroded specimens, and that the friction factors of the corroded specimens were not very dependent on contact stress or corrosion film thickness. The measured values of friction factors for the three corrosion films tested (simulating three operating times) were in the range of 0.3 to 0.4. The friction factor for even the shortest simulated operating time was essentially the same as the others, indicating that the friction factors appear to reach a plateau and that the plateau is reached quickly.

  6. Graphene: corrosion-inhibiting coating.

    Science.gov (United States)

    Prasai, Dhiraj; Tuberquia, Juan Carlos; Harl, Robert R; Jennings, G Kane; Rogers, Bridget R; Bolotin, Kirill I

    2012-02-28

    We report the use of atomically thin layers of graphene as a protective coating that inhibits corrosion of underlying metals. Here, we employ electrochemical methods to study the corrosion inhibition of copper and nickel by either growing graphene on these metals, or by mechanically transferring multilayer graphene onto them. Cyclic voltammetry measurements reveal that the graphene coating effectively suppresses metal oxidation and oxygen reduction. Electrochemical impedance spectroscopy measurements suggest that while graphene itself is not damaged, the metal under it is corroded at cracks in the graphene film. Finally, we use Tafel analysis to quantify the corrosion rates of samples with and without graphene coatings. These results indicate that copper films coated with graphene grown via chemical vapor deposition are corroded 7 times slower in an aerated Na(2)SO(4) solution as compared to the corrosion rate of bare copper. Tafel analysis reveals that nickel with a multilayer graphene film grown on it corrodes 20 times slower while nickel surfaces coated with four layers of mechanically transferred graphene corrode 4 times slower than bare nickel. These findings establish graphene as the thinnest known corrosion-protecting coating.

  7. Investigation of a Cu/Pd Bimetallic System Electrodeposited on Boron-Doped Diamond Films for Application in Electrocatalytic Reduction of Nitrate

    Directory of Open Access Journals (Sweden)

    Jorge T. Matsushima

    2012-01-01

    Full Text Available The Cu/Pd bimetallic system electrodeposited on boron-doped diamond (BDD films for application, as electrode material in the electrochemical reduction of nitrate was studied. The electrochemical behavior of Cu, Pd, and Cu/Pd bimetallic system was evaluated by cyclic voltammetry. From these results, the formation of the Cu/Pd composite was verified. In addition, Cu with different phases and a Cu/Pd phase in the composite were obtained. Morphological analysis by scanning electron microscopy (SEM revealed a homogeneous distribution of Cu/Pd bimetallic particles with intermediary dimensions compared to those observed in Cu or Pd electrodeposits separately. These composites were tested as electrocatalysts for nitrate reduction in Britton-Robinson buffer solution (pH 9. Electrochemical measurements showed that composites with higher Cu content displayed the best electrocatalytic activity for nitrate reduction, and the Cu/Pd phase in the bimetallic system served to improve the Cu adherence on BDD electrode.

  8. Catalytic Sorption of (Chloro)Benzene and Napthalene in Aqueous Solutions by Granular Activated Carbon Supported Bimetallic Iron and Palladium Nanoparticles

    Science.gov (United States)

    Adsorption of benzene, chlorobenzene, and naphthalene on commercially available granular activated carbon (GAC) and bimetallic nanoparticle (Fe/Pd) loaded GAC was investigated for the potential use in active capping of contaminated sediments. Freundlich and Langmuir linearizatio...

  9. Microencapsulation of Corrosion Indicators for Smart Coatings

    Science.gov (United States)

    Li, Wenyan; Buhrow, Jerry W.; Jolley, Scott T.; Calle, Luz M.; Hanna,Joshua S.; Rawlins, James W.

    2011-01-01

    A multifunctional smart coating for the autonomous detection, indication, and control of corrosion is been developed based on microencapsulation technology. This paper summarizes the development, optimization, and testing of microcapsules specifically designed for early detection and indication of corrosion when incorporated into a smart coating. Results from experiments designed to test the ability of the microcapsules to detect and indicate corrosion, when blended into several paint systems, show that these experimental coatings generate a color change, indicative of spot specific corrosion events, that can be observed with the naked eye within hours rather than the hundreds of hours or months typical of the standard accelerated corrosion test protocols.. Key words: smart coating, corrosion detection, microencapsulation, microcapsule, pH-sensitive microcapsule, corrosion indicator, corrosion sensing paint

  10. Method For Testing Properties Of Corrosive Lubricants

    Science.gov (United States)

    Ohi, James; De La Cruz, Jose L.; Lacey, Paul I.

    2006-01-03

    A method of testing corrosive lubricating media using a wear testing apparatus without a mechanical seal. The wear testing apparatus and methods are effective for testing volatile corrosive lubricating media under pressure and at high temperatures.

  11. CATALYSIS SCIENCE INITIATIVE: From First Principles Design to Realization of Bimetallic Catalysts for Enhanced Selectivity

    Energy Technology Data Exchange (ETDEWEB)

    MAVRIKAKIS, MANOS

    2007-05-03

    In this project, we have integrated state-of-the-art Density Functional Theory (DFT) models of heterogeneous catalytic processes with high-throughput screening of bimetallic catalytic candidates for important industrial problems. We have studied a new class of alloys characterized by a surface composition different from the bulk composition, and investigated their stability and activity for the water-gas shift reaction and the oxygen reduction reaction. The former reaction is an essential part of hydrogen production; the latter is the rate-limiting step in low temperature H2 fuel cells. We have identified alloys that have remarkable stability and activity, while having a much lower material cost for both of these reactions. Using this knowledge of bimetallic interactions, we have also made progress in the industrially relevant areas of carbohydrate reforming and conversion of biomass to liquid alkanes. One aspect of this work is the conversion of glycerol (a byproduct of biodiesel production) to synthesis gas. We have developed a bifunctional supported Pt catalyst that can cleave the carbon-carbon bond while also performing the water-gas shift reaction, which allows us to better control the H2:CO ratio. Knowledge gained from the theoretical metal-metal interactions was used to develop bimetallic catalysts that perform this reaction at low temperature, allowing for an efficient coupling of this endothermic reaction with other reactions, such as Fischer-Tropsch or methanol synthesis. In our work on liquid alkane production from biomass, we have studied deactivation and selectivity in these areas as a function of metal-support interactions and reaction conditions, with an emphasis on the bifunctionality of the catalysts studied. We have identified a stable, active catalyst for this process, where the selectivity and yield can be controlled by the reaction conditions. While complete rational design of catalysts is still elusive, this work demonstrates the power of

  12. Novel platinum–palladium bimetallic nanoparticles synthesized by Dioscorea bulbifera: anticancer and antioxidant activities

    Directory of Open Access Journals (Sweden)

    Ghosh S

    2015-12-01

    Full Text Available Sougata Ghosh,1 Rahul Nitnavare,1 Ankush Dewle,1 Geetanjali B Tomar,1 Rohan Chippalkatti,1 Piyush More,1 Rohini Kitture,2 Sangeeta Kale,2 Jayesh Bellare,3 Balu A Chopade4 1Institute of Bioinformatics and Biotechnology, University of Pune, 2Department of Applied Physics, Defense Institute of Advanced Technology, Pune, 3Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, 4Department of Microbiology, University of Pune, Pune, India Abstract: Medicinal plants serve as rich sources of diverse bioactive phytochemicals that might even take part in bioreduction and stabilization of phytogenic nanoparticles with immense therapeutic properties. Herein, we report for the first time the rapid efficient synthesis of novel platinum–palladium bimetallic nanoparticles (Pt–PdNPs along with individual platinum (PtNPs and palladium (PdNPs nanoparticles using a medicinal plant, Dioscorea bulbifera tuber extract (DBTE. High-resolution transmission electron microscopy revealed monodispersed PtNPs of size 2–5 nm, while PdNPs and Pt–PdNPs between 10 and 25 nm. Energy dispersive spectroscopy analysis confirmed 30.88%±1.73% elemental Pt and 68.96%±1.48% elemental Pd in the bimetallic nanoparticles. Fourier transform infrared spectra indicated strong peaks at 3,373 cm-1, attributed to hydroxyl group of polyphenolic compounds in DBTE that might play a key role in bioreduction in addition to the sharp peaks at 2,937, 1,647, 1,518, and 1,024 cm-1, associated with C–H stretching, N–H bending in primary amines, N–O stretching in nitro group, and C–C stretch, respectively. Anticancer activity against HeLa cells showed that Pt–PdNPs exhibited more pronounced cell death of 74.25% compared to individual PtNPs (12.6% or PdNPs (33.15%. Further, Pt–PdNPs showed an enhanced scavenging activity against 2,2-diphenyl-1-picrylhydrazyl, superoxide, nitric oxide, and hydroxyl radicals. Keywords: Dioscorea bulbifera, platinum nanoparticles

  13. Smart Coatings for Launch Site Corrosion Protection

    Science.gov (United States)

    Calle, Luz M.

    2014-01-01

    Smart, environmentally friendly paint system for early corrosion detection, mitigation, and healing that will enable supportability in KSC launch facilities and ground systems through their operational life cycles. KSC's Corrosion Technology Laboratory is developing a smart, self-healing coating that can detect and repair corrosion at an early stage. This coating is being developed using microcapsules specifically designed to deliver the contents of their core when corrosion starts.

  14. Multicomponent Oxide Systems for Corrosion Protection.

    Science.gov (United States)

    1980-11-15

    and Si(OEt) 4 are somewhat lpss corrosive to aluminum than is SiCI 4 alone, although some pitting occurs for slow hydrolysis after coating by solutions...humidity (x) 86 A𔃻 determinants of corrosion resistance. The magnesium-silicon- aluminum alloy AA 6061 is generally considered to have good corrosion ... 6061 ), the corrosion resistance exceeded that of the chromate coatings. The feasibilityof the basic approach taken here has been validated. It

  15. A Preliminary Report on the Strength and Metallography of a Bimetallic Friction Stir Weld Joint Between AA6061 and MIL-DTL-46100E High Hardness Steel Armor

    Science.gov (United States)

    2012-11-26

    bimetallic friction stir weld joint between AA6061 and MIL-DTL-46100E High Hardness steel armor. ABSTRACT One half inch thick plates of 6061-T6 aluminum...alloy and High Hardness steel armor (MIL- STD-46100) were successfully joined by the friction stir welding (FSW) process using a tungsten-rhenium...4. TITLE AND SUBTITLE A preliminary report on the strength and metallography of a bimetallic friction stir weld joint between AA6061 and MIL-DTL

  16. Surface modification for corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1993-06-01

    The raw gas environments that arise from coal gasification have chemical compositions that are low in pO{sub 2} and moderate-to-high in pS{sub 2}. Metallic materials for service in such an environment undergo predominantly sulfidation attack at temperatures of 400 to 700{degree}C. Modification of alloy compositions in bulk can alter the scaling processes and lead to improvements in corrosion resistance, but the benefits can only be attained at temperatures much higher than the service temperatures of the components. Modification of surfaces of structural components by several of the coating techniques examined in this study showed substantial benefit in corrosion resistance when tested in simulated coal gasification environments. The paper presents several examples of surface modification and their corrosion performance.

  17. Electrochemical corrosion of metallic biomaterials.

    Science.gov (United States)

    Pourbaix, M

    1984-05-01

    Methods of electrochemical thermodynamics (electrode potential-pH equilibrium diagrams) and electrochemical kinetics (polarization curves) may help to understand and predict the corrosion behaviour of metals and alloys in the presence of body fluids. A short review of the literature is given concerning some applications of such methods, both in vitro and in vivo, relating to surgical implants (stainless steels, chromium-cobalt-molybdenum alloys, titanium and titanium alloys) and to dental alloys (silver-tin-copper amalgams, silver-base and gold-base casting alloys, nickel-base casting alloys). Attention is drawn to the necessity of more basic research on crevice- and fretting-corrosion of surgical implant materials and dental alloys, and to the toxicity of corrosion products. A perfect understanding of the exact significance of electrode-potentials is essential for the success of such a task.

  18. Strain Measurement Technology for Corrosion Fatigue Specimen

    Institute of Scientific and Technical Information of China (English)

    ZHONG; Wei-hua; NING; Guang-sheng; ZHANG; Chang-yi; TONG; Zhen-feng; YANG; Wen

    2015-01-01

    Main pipeline is the key component of nuclear power plants(NPPs).Under the first loop water and low-cyclic load condition,the main pipeline may be induced to corrosion fatigue failure.Thus,it’s necessary to test and get the corrosion fatigue property of main pipeline material.During the corrosion fatigue test,the strain

  19. 7 CFR 2902.44 - Corrosion preventatives.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Corrosion preventatives. 2902.44 Section 2902.44... Items § 2902.44 Corrosion preventatives. (a) Definition. Products designed to prevent the deterioration (corrosion) of metals. (b) Minimum biobased content. The preferred procurement product must have a...

  20. 49 CFR 193.2625 - Corrosion protection.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Corrosion protection. 193.2625 Section 193.2625...: FEDERAL SAFETY STANDARDS Maintenance § 193.2625 Corrosion protection. (a) Each operator shall determine which metallic components could, unless corrosion is controlled, have their integrity or...

  1. Corrosion-Induced Concrete Cracking Model Considering Corrosion-Filled Paste

    OpenAIRE

    Dong, Jianfeng; Zhao, Yuxi; Wu, Yingyao; Jin, Weiliang

    2016-01-01

    A TCP–TCL model is established to describe the relationship between the thickness of the corrosion-filled paste (CP) and that of the corrosion layer (CL). This model can describe the phenomenon that the corrosion filling in the concrete pores and accumulating at the steel/concrete interface occur synchronously. Based on the TCP–TCL model, a corrosion-induced concrete cracking model, which can quantitatively consider corrosion-filled paste at concrete/steel interface, is proposed. Combined wit...

  2. Corrosion-Inhibitor Efficiency Control: Comparison by Means of Different Portable Corrosion Rate Meters

    OpenAIRE

    Martinez Sierra, Isabel; Andrade Perdrix, Maria del Carmen; Rebolledo Ramos, Nuria; Luo, L; De Schutter, G

    2010-01-01

    Corrosion-inhibiting substances have been applied to suppress corrosion mainly on bare steel, but when corrosion is progressing, suppression can be achieved if anodic and cathodic reactions are avoided, which is not an easy objective, particularly if the bare metal is surrounded by concrete. In the present article, several corrosion inhibitors are studied to identify their inhibition efficiency in concrete. The percentage of reduction of the corrosion rate without and with inhibitor is named ...

  3. Electrochemical Measurement of Atmospheric Corrosion

    Science.gov (United States)

    DeArmond, Anna H.; Davis, Dennis D.; Beeson, Harold D.

    1999-01-01

    Corrosion of Shuttle thruster components in atmospheres containing high concentrations of nitrogen tetroxide (NTO) and water is an important issue in ground operations of bipropellant systems in humid locations. Measurements of the corrosivities of NTO-containing atmospheres and the responses of different materials to these atmospheres have been accomplished using an electrochemical sensor. The sensor is composed of alternating aluminum/titanium strips separated by thin insulating layers. Under high humidity conditions a thin film of water covers the surface of the sensor. Added NTO vapor reacts with the water film to form a conductive medium and establishes a galvanic cell. The current from this cell can be integrated with respect to time and related to the corrosion activity. The surface layer formed from humid air/NTO reacts in the same way as an aqueous solution of nitric acid. Nitric acid is generally considered an important agent in NTO corrosion situations. The aluminum/titanium sensor is unresponsive to dry air, responds slightly to humid air (> 75% RH), and responds strongly to the combination of humid air and NTO. The sensor response is a power function (n = 2) of the NTO concentration. The sensor does not respond to NTO in dry air. The response of other materials in this type of sensor is related to position of the material in a galvanic series in aqueous nitric acid. The concept and operation of this electrochemical corrosion measurement is being applied to other corrosive atmospheric contaminants such as hydrogen chloride, hydrogen fluoride, sulfur dioxide, and acidic aerosols.

  4. Corrosion performance of structural alloys.

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1999-07-15

    Component reliability and long-term trouble-free performance of structural materials are essential in power-generating and gasification processes that utilize coal as a feedstock. During combustion and conversion of coal, the environments encompass a wide range of oxygen partial pressures, from excess-air conditions in conventional boilers to air-deficient conditions in 10W-NO{sub x} and gasification systems. Apart from the environmental aspects of the effluent from coal combustion and conversion, one concern from the systems standpoint is the aggressiveness of the gaseous/deposit environment toward structural components such as waterwall tubes, steam superheaters, syngas coolers, and hot-gas filters. The corrosion tests in the program described in this paper address the individual and combined effects of oxygen, sulfur, and chlorine on the corrosion response of several ASME-coded and noncoded structural alloys that were exposed to air-deficient and excess-air environments typical of coal-combustion and gasification processes. Data in this paper address the effects of preoxidation on the subsequent corrosion performance of structural materials such as 9Cr-1Mo ferritic steel, Type 347 austenitic stainless steel, Alloys 800, 825, 625, 214, Hastelloy X, and iron aluminide when exposed at 650 C to various mixed-gas environments with and without HCI. Results are presented for scaling kinetics, microstructural characteristics of corrosion products, detailed evaluations of near-surface regions of the exposed specimens, gains in our mechanistic understanding of the roles of S and Cl in the corrosion process, and the effect of preoxidation on subsequent corrosion.

  5. Crystal and electronic structure study of AgAu and AgCu bimetallic alloy thin films by X-ray techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ozkendir, O. Murat, E-mail: ozkendir@gmail.com [Mersin University, Faculty of Technology, Energy Systems Engineering, Tarsus (Turkey); Mersin University, Institute of Natural Science, Department of Nanotechnology and Advanced Materials, Mersin (Turkey); Cengiz, E. [Karadeniz Technical University, Faculty of Science, Department of Physics, Trabzon (Turkey); Yalaz, E. [Mersin University, Institute of Natural Science, Department of Nanotechnology and Advanced Materials, Mersin (Turkey); Söğüt, Ö.; Ayas, D.H. [Kahramanmaraş Sütçü İmam Üniversitesi, Faculty of Science and Letters, Department of Physics, Kahramanmaraş (Turkey); Thammajak, B. Nirawat [Synchrotron Light Research Institute (Public Organisation), 111 University Avenue, T. Suranaree, A. Muang, Nakhon Ratchasima 30000 (Thailand)

    2016-05-15

    Highlights: • Crystal and electronic properties of bimetallic AgCu and AgAu alloy thin films were studied. • Both AgCu and AgAu bimetallic samples were determined to have cubic crystal geometry. • Strong influence of Cu and Au atoms on the electronic structure of the Ag atoms were determined. - Abstract: Crystal and electronic structure properties of bimetallic AgAu and AgCu alloy thin films were investigated by X-ray spectroscopic techniques. The aim of this study is to probe the influence of Au or Cu atoms on the electronic behaviors of Ag ions in bimetallic alloy materials that yields different crystal properties. To identify the mechanisms causing crystal phase transitions, study were supported by the collected EXAFS (Extended X-ray Absorption Fine Structure) data. Crystal structures of both Cu and Au doped bimetallic Ag samples were determined mainly in cubic geometry with “Fm3m” space group. Through the Ag–Au and Ag–Cu molecular interactions during bimetallic alloy formations, highly overlapped electronic levels that supports large molecular band formations were observed with different ionization states. Besides, traces of the d–d interactions in Au rich samples were determined as the main interplay in the broad molecular bond formations. The exact atomic locations and types in the samples were determined by EXAFS studies and supported by the performed calculations with FEFF scientific code.

  6. Corrosive effects of hvdc transmission

    Energy Technology Data Exchange (ETDEWEB)

    Cornwell, F.E.; Backstrom, T.E.

    1966-02-01

    Field tests using ac transmission lines for introduction of direct current into the earth at widely separated points are described. One test circuit was between a Tracy pumping plant and a Shasta power plant in California, and two others were in the Hoover power plant area. Evaluation of the effects of such ground currents on corrosion of buried metalwork was a primary aim of the tests. Potential gradients, pipe-to-soil potentials, and soil resistivities are discussed in detail. Estimates are made of the distances from ehv dc terminal installations within which corrosion prevention procedures may become necessary.

  7. Coatings for improved corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1992-05-01

    Several coating approaches are being developed to resist attack in coal-fired environments and thereby minimize corrosion of underlying substrate alloys and extend the time for onset of breakaway corrosion. In general, coating systems can be classified as either diffusion or overlay type, which are distinguished principally by the method of deposition and the structure of the resultant coating-substrate bond. The coating techniques examined are pack cementation, electrospark deposition, physical and chemical vapor deposition, plasma spray, and ion implantation. In addition, ceramic coatings are used in some applications.

  8. High temperature corrosion in gasifiers

    Directory of Open Access Journals (Sweden)

    Bakker Wate

    2004-01-01

    Full Text Available Several commercial scale coal gasification combined cycle power plants have been built and successfully operated during the last 5-10 years. Supporting research on materials of construction has been carried out for the last 20 years by EPRI and others. Emphasis was on metallic alloys for heat exchangers and other components in contact with hot corrosive gases at high temperatures. In this paper major high temperature corrosion mechanisms, materials performance in presently operating gasifiers and future research needs will be discussed.

  9. Cyclone reburning retrofit: Corrosion evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Sarv, H.; Paul, L.D. (Babcock and Wilcox Co., New Orleans, LA (USA))

    1991-01-01

    Reburning is an emerging NO{sub x} reducing technology which offers cyclone boiler owners a promising alternative to the more expensive flue gas cleanup techniques. Pilot-scale test results have shown that the corrosive H{sub 2}S gas can evolve during reburn. This can pose a potential problem and concern in retrofits burning high-sulfur Illinois coals. This research program is intended to assess tube corrosion under simulated reburning conditions (temperature, stoichiometry, and H{sub 2}S concentration). Performance of existing carbon steel as well as other alloys will be tested and compared. 1 fig.

  10. Cyclone reburning retrofit: Corrosion evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Farzan, H.; Paul, L.D. (Babcock and Wilcox Co., New Orleans, LA (USA))

    1990-01-01

    Reburning is an emerging NO{sub x} reducing technology which offers cyclone boiler owners a promising alternative to the more expensive flue gas cleanup techniques. Pilot-scale test results have shown that the corrosive H{sub 2}S gas can evolve during reburn. This can pose a potential problem and concern in retrofits burning high-sulfur Illinois coals. This research program is intended to assess tube corrosion under simulated reburning conditions (temperature, stoichiometry, and H{sub 2}S concentration). Performance of existing carbon steel as well as other alloys will be tested and compared. 1 fig.

  11. Microbial Influenced Corrosion (MIC) Study

    Science.gov (United States)

    2012-05-23

    low lying areas breaks down protective coating system and causes structural corrosion , • Water and organic/inorganic nutrients BUSINESS SENSITIVE...Chemical disinfection (T.O 1-1-8 and T.O 1-1-691) • Biocidal rinses and coatings • Biocidal Corrosion Preventative Compounds or CPCs BUSINESS...Type: H    Proprietary  Coating  w/ Silver  Inhibitor   Non‐Chrome Treatment + Mg‐Rich  Primer  Coupon Type: I    Prekote® (Pantheon Chemical) N/A

  12. Corrosion Reliability of Electronic Systems

    DEFF Research Database (Denmark)

    Ambat, Rajan; Jensen, Stine G.; Møller, Per

    2008-01-01

    Inherently two factors namely multi-material usage and potential bias makes electronic devices susceptible to corrosion if exposed to humid conditions. The problem is compounded today due to miniaturization and contamination effects. The reduction in size of the components and close spacing...... on a Printed Circuit Board (PCB) for high density packing has greatly increased the risk of corrosion under humid conditions. An important issue is the failures due to electrolytic metal migration. This paper describes an investigation of the electrolytic migration of Sn-Pb solder lines on PCBs in humid...

  13. Gold-platinum bimetallic nanotubes templated from tellurium nanowires as efficient electrocatalysts for methanol oxidation reaction

    Science.gov (United States)

    Lu, Chenchen; Kong, Wei; Zhang, Huying; Song, Bo; Wang, Zhenghua

    2015-11-01

    In this paper, gold-platinum (Au-Pt) bimetallic nanotubes with different Au/Pt ratio are successfully synthesized through a simple wet-chemical reduction route in which tellurium (Te) nanowires serve as both sacrificial template and reducing agent. The hollow nanostructure of Au-Pt nanotubes is formed due to Kirkendall effect. The as-prepared Au-Pt nanotubes can be applied as catalyst for methanol oxidation reaction, and the results indicate that the Au-Pt nanotubes with an Au/Pt ratio of 1:1 show the best electrochemical catalytic performances. Furthermore, the catalytic activity of the Au-Pt nanotubes is also better than Pt nanotubes and commercial Pt/C catalyst.

  14. PROPERTIES OF POLYMER SUPPORTED Ni-Cu BIMETALLIC CATALYSTS PREPARED BY SOLVATED METAL ATOM IMPREGNATION

    Institute of Scientific and Technical Information of China (English)

    WU Shihua; ZHU Changying; HUANG Wenqiang

    1996-01-01

    D-72 resin supported nickel-copper catalysts prepared by solvated metal atom impregnation (SMAI) were studied by magnetic measurements and X-ray photoelectron spectroscopy (XPS). The Ni particles on the catalysts are very highly dispersed and display superparamagnetic behaviour. Ni-Cu alloy clusters were found to be formed. The surface compositions are different from the bulk concentrations. In contrast with the surface enrichment in copper generally observed on conventional Ni-Cu catalysts, the surfaces of these catalysts are enriched in nickel. The nickel is in both zero and valent states, while copper is mainly in metallic state. Catalytic data show that the formation of Ni-Cu alloy clusters has a profound effect on the catalytic activities of the catalysts in the hydrogenation of furfural. The activity of the Ni:Cu ratio of one bimetallic catalysts is much higher than that of the Ni or Cu monometallic catalyst.

  15. Glycerol conversion into value added chemicals over bimetallic catalysts in supercritical carbon dioxide

    Science.gov (United States)

    Hidayati, Luthfiana N.; Sudiyarmanto, Adilina, Indri B.

    2017-01-01

    Development of alternative energy from biomass encourage the experiments and production of biodiesel lately. Biodiesel industries widely expand because biodiesel as substitute of fossil fuel recognized as promising renewable energy. Glycerol is a byproduct of biodiesel production, which is resulted 10% wt average every production. Meanwhile, carbon dioxide is a gas that is very abundant amount in the atmosphere. Glycerol and carbon dioxide can be regarded as waste, possibly will produce value-added chemical compounds through chemically treated. In this preliminary study, conversion of glycerol and carbon dioxide using bimetallic catalyst Ni-Sn with various catalyst supports : MgO, γ-Al2O3, and hydrotalcite. Catalysts which have been prepared, then physically characterized by XRD, surface area and porosity analysis, and thermal gravity analysis. Catalytic test performance using supercritical carbon dioxide conditions. Furthermore, the products were analyzed by GC. The final product mostly contained of propylene glycol and glycerol carbonate.

  16. Surface-Bound Ligands Modulate Chemoselectivity and Activity of a Bimetallic Nanoparticle Catalyst

    KAUST Repository

    Vu, Khanh B.

    2015-04-03

    "Naked" metal nanoparticles (NPs) are thermodynamically and kinetically unstable in solution. Ligands, surfactants, or polymers, which adsorb at a particle\\'s surface, can be used to stabilize NPs; however, such a mode of stabilization is undesirable for catalytic applications because the adsorbates block the surface active sites. The catalytic activity and the stability of NPs are usually inversely correlated. Here, we describe an example of a bimetallic (PtFe) NP catalyst stabilized by carboxylate surface ligands that bind preferentially to one of the metals (Fe). NPs stabilized by fluorous ligands were found to be remarkably competent in catalyzing the hydrogenation of cinnamaldehyde; NPs stabilized by hydrocarbon ligands were significantly less active. The chain length of the fluorous ligands played a key role in determining the chemoselectivity of the FePt NP catalysts. (Chemical Presented). © 2015 American Chemical Society.

  17. Bi-Metallic Composite Structures With Designed Internal Residual Stress Field

    Science.gov (United States)

    Brice, Craig A.

    2014-01-01

    Shape memory alloys (SMA) have a unique ability to recover small amounts of plastic strain through a temperature induced phase change. For these materials, mechanical displacement can be accomplished by heating the structure to induce a phase change, through which some of the plastic strain previously introduced to the structure can be reversed. This paper introduces a concept whereby an SMA phase is incorporated into a conventional alloy matrix in a co-continuous reticulated arrangement forming a bi-metallic composite structure. Through memory activation of the mechanically constrained SMA phase, a controlled residual stress field is developed in the interior of the structure. The presented experimental data show that the memory activation of the SMA composite component significantly changes the residual stress distribution in the overall structure. Designing the structural arrangement of the two phases to produce a controlled residual stress field could be used to create structures that have much improved durability and damage tolerance properties.

  18. Surface Plasmon Resonance from Bimetallic Interface in Au–Ag Core–Shell Structure Nanowires

    Directory of Open Access Journals (Sweden)

    Zhu Jian

    2009-01-01

    Full Text Available Abstract Transverse surface plasmon resonances (SPR in Au–Ag and Ag–Au core–shell structure nanowires have been investigated by means of quasi-static theory. There are two kinds of SPR bands resulting from the outer surface of wall metal and the interface between core and wall metals, respectively. The SPR corresponding to the interface, which is similar to that of alloy particle, decreases and shifts obviously with increasing the wall thickness. However, the SPR corresponding to the outer surface, which is similar to that of pure metal particle, increases and shifts slightly with increasing the wall thickness. A mechanism based on oscillatory surface electrons under coulombic attraction is developed to illuminate the shift fashion of SPR from bimetallic core–shell interface. The net charges and extra coulombic force in metallic wall affect the SPR energy and the shift fashion.

  19. Stability of the Shallow Axisymmetric Parabolic-Conic Bimetallic Shell by Nonlinear Theory

    Directory of Open Access Journals (Sweden)

    M. Jakomin

    2011-01-01

    Full Text Available In this contribution, we discuss the stress, deformation, and snap-through conditions of thin, axi-symmetric, shallow bimetallic shells of so-called parabolic-conic and plate-parabolic type shells loaded by thermal loading. According to the theory of the third order that takes into account the balance of forces on a deformed body, we present a model with a mathematical description of the system geometry, displacements, stress, and thermoelastic deformations. The equations are based on the large displacements theory. We numerically calculate the deformation curve and the snap-through temperature using the fourth-order Runge-Kutta method and a nonlinear shooting method. We show how the temperature of both snap-through depends on the point where one type of the rotational curve transforms into another.

  20. Dual Wavelength Laser Writing and Measurement Methodology for High Resolution Bimetallic Grayscale Photomasks

    Science.gov (United States)

    Qarehbaghi, Reza

    Grayscale bimetallic photomasks consist of bi-layer thermal resists (Bismuth-on-Indium or Tin-on-Indium) which become controllably transparent when exposed to a focused laser beam as a function of the absorbed power changing from ~3OD (unexposed) to writing. This thesis investigates using two wavelength beams for mask writing (514.5nm) and OD measurement (457.9nm) separated from a multi-line Argon ion laser source: a Dual Wavelength Writing and Measurement System. The writing laser profile was modified to a top-hat using a beam shaper. Several mask patterns tested the creation of high resolution grayscale masks. Finally, for creation of 3D structures in photoresist, the mask transparency to resist thickness requirements was formulated and linear slope patterns were successfully created.

  1. SULFUR-RESISTANT BIMETALLIC NOBLE METAL CATALYSTS FOR AROMATIC HYDROGENATION OF DIESEL FUEL

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Y zeolite supporting noble metal catalysts, as the important industrial catalysts for aromatics hydrogenation, have received increasing attention in recent years. Pd-M/Y bimetallic catalysts, where M is non-noble metal element, were prepared to investigate the effects of the addition of a second metal. Pd-M/Y catalysts were evaluated under the following conditions: H2 pressure 4.2 MPa, MHSV 4.0 h-1, sulfur content in feed 3000 μg/g. The microreactor results indicated that the second metal remarkably affects the hydrogenation activity of Pd/Y catalysts. Among them, Cr and W improve the sulfur resistance of Pd/Y, but La, Mn, Mo and Ag make the sulfur resistance worse and the second metals have no evident influence on product selectivity and acidic properties of the catalysts.

  2. Effects of Irregular Bimetallic Nanostructures on the Optical Properties of Photosystem I from Thermosynechococcus elongatus

    Directory of Open Access Journals (Sweden)

    Imran Ashraf

    2015-07-01

    Full Text Available The fluorescence of photosystem I (PSI trimers in proximity to bimetallic plasmonic nanostructures have been explored by single-molecule spectroscopy (SMS at cryogenic temperature (1.6 K. PSI serves as a model for biological multichromophore-coupled systems with high potential for biotechnological applications. Plasmonic nanostructures are fabricated by thermal annealing of thin metallic films. The fluorescence of PSI has been intensified due to the coupling with plasmonic nanostructures. Enhancement factors up to 22.9 and 5.1 are observed for individual PSI complexes coupled to Au/Au and Ag/Au samples, respectively. Additionally, a wavelength dependence of fluorescence enhancement is observed, which can be explained by the multichromophoric composition of PSI.

  3. The synthesis of Pt/Ag bimetallic nanoparticles using a successive solution plasma process.

    Science.gov (United States)

    Kim, Sung Min; Lee, Sang Yul; Lee, Min Hyung; Kim, Jung Wan

    2014-12-01

    A successive solution plasma process was developed for the synthesis of Pt/Ag bimetallic nanoparticles. Ag nanoparticles were made first by applying a high voltage of bipolar pulsed DC to anode and cathode electrodes composed of Ag rods. The solution containing Ag nanoparticles was discharged successively using Pt electrodes. The joule heating and electrolysis between electrodes generated vapors, and solution plasma was sustained due to progressive ionization and excitation in the vapor phase. The maximum current and voltage breakdown was observed at approximately 8.9 A and 900 V with an interval of 25 μs, which indicated that an intense solution plasma was sustained continuously. The Pt-on-Ag heterogeneous nanostructures formed, and finally, the Ag nanoparticles were completely covered by Pt nanoparticles after a discharge duration of 1,200 s.

  4. Photodissociation and spectroscopy of gas phase bimetallic clusters. Progress report for 1990--1991

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, M.A.

    1991-12-31

    The general goals of this research project are (1) to synthesize novel bimetallic clusters in the gas phase; (2) to characterize their geometry, electronic structure, and chemical bonding; and (3) to compare these heterogeneous systems to corresponding pure component clusters. Clusters are synthesized by pulsed laser vaporization of solid metal rods coincident with laser photolysis of volatile metal complexes (e.g., metal carbonyls). Two techniques are used to characterize cluster properties: resonant two-photon ionization spectroscopy (R2PI) of neutral clusters and laser photodissociation spectroscopy of cluster ions. The project focuses on the selected mixtures of iron, chromium, and molybdenum with bismuth, aluminum and silver to probe a variety of heterogeneous effects in transition metal-main group metal mixtures.

  5. Characterization and reactivity of Pd Pt bimetallic supported catalysts obtained by laser vaporization of bulk alloy

    Science.gov (United States)

    Rousset, J. L.; Cadete Santos Aires, F. J.; Bornette, F.; Cattenot, M.; Pellarin, M.; Stievano, L.; Renouprez, A. J.

    2000-09-01

    Bimetallic Pd-Pt clusters produced by laser vaporization of bulk alloy have been deposited on high surface alumina. Energy dispersive X-ray (EDX) analysis and transmission electron microscopy (TEM) show that they have a perfectly well-defined stoichiometry and a narrow range of size. Therefore, they constitute ideal systems to investigate alloying effects towards reactivity. Pd-Pt alloys are already known for their applications in the hydrogenation of unsaturated hydrocarbons, especially aromatics, because this system is highly resistant to sulfur and nitrogen poisoning. In this context, the catalytic properties of this system have been investigated in the hydrogenation of tetralin in the presence of hydrogen sulfide. Preliminary results show that this model catalyst is more sulfur-resistant than each of the pure supported metals prepared by chemical methods.

  6. Using Mechanical Alloying to Create Bimetallic Catalysts for Vapor-Phase Carbon Nanofiber Synthesis

    Directory of Open Access Journals (Sweden)

    Laura Guevara

    2015-10-01

    Full Text Available Carbon nanofibers were generated over bimetallic catalysts in an atmospheric pressure chemical vapor deposition (APCVD reactor. Catalyst compositions of Fe 30 at%, Cu and Ni 30 at% and Cu were mechanically alloyed using high-energy ball milling over durations of 4, 8, 12, 16, and 20 h. The catalyst powders were then used to produce carbon nanofibers in ethylene and hydrogen (4:1 at temperatures of 500, 550, and 600 °C. The microstructures of the catalysts were characterized as a function of milling time as well as at deposition temperature. The corresponding carbon deposition rates were assessed and are correlated to the microstructural features of each catalyst. The milling process directly determines the performance of each catalyst toward carbon deposition, and both catalysts performed comparably to those made by traditional co-precipitation methods. Considerations in miscible and immiscible nanostructured alloy systems are discussed.

  7. FORMATION MECHANISM FOR THE NANOSCALE AMORPHOUS INTERFACE IN PULSE-WELDED AL/FE BIMETALLIC SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jingjing; Yu, Qian; Zhang, Zijiao; Xu, Wei; Sun, Xin

    2016-05-20

    Pulse or impact welding traditionally has been referred to as “solid-state” welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed in the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the resulted recrystallization occurred on the aluminum side of the interface.

  8. High-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles for phenol hydrogenation

    Science.gov (United States)

    Huang, Chao; Yang, Xu; Yang, Hui; Huang, Peiyan; Song, Huiyu; Liao, Shijun

    2014-10-01

    A high-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles (MSN), PdRu/MSN, was prepared by a facile impregnation-hydrogen reduction method. It was found that PdRu/MSN showed 5 times higher activity than that of Pd/MSN towards the liquid-phase hydrogenation of phenol. The catalysts were characterized comprehensively by multiple techniques, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature program reduction (TPR). It was revealed that adding Ru could effectively improve the Pd dispersion and promote the electronic interaction between the Pd and Ru, both of which contribute to enhancing the catalytic activity.

  9. Desorption of Furfural from Bimetallic Pt-Fe Oxides/Alumina Catalysts

    Directory of Open Access Journals (Sweden)

    Gloria Lourdes Dimas-Rivera

    2014-01-01

    Full Text Available In this work, the desorption of furfural, which is a competitive intermediate during the production of biofuel and valuable aromatic compounds, was studied using pure alumina, as well as alumina impregnated with iron and platinum oxides both individually and in combination, using thermogravimetric analysis (TGA. The bimetallic sample exhibited the lowest desorption percentage for furfural. High-resolution transmission electron microscopy (HRTEM imaging revealed the intimate connection between the iron and platinum oxide species on the alumina support. The mechanism of furfural desorption from the Pt-Fe/Al2O3 0.5%-0.5% sample was determined using physisorbed furfural instead of chemisorbed furfural; this mechanism involved the oxidation of the C=O group on furfural by the catalyst. The oxide nanoparticles on γ-Al2O3 support helped to stabilize the furfural molecule on the surface.

  10. Computational study of alkynes insertion into metal-hydride bonds catalyzed by bimetallic complexes.

    Science.gov (United States)

    Di Tommaso, Stefania; Tognetti, Vincent; Sicilia, Emilia; Adamo, Carlo; Russo, Nino

    2010-11-01

    Density Functional Theory investigations on the insertion mechanism of phenylacetylene into metal-hydride bonds in bimetallic (Pt,Os) catalysts have been carried out. The results obtained have been also compared with the non-reactive monometallic (Os-based) system, to elucidate the cooperative effects and to explain the observed absence of reactivity. The identified reaction path involves phenylacetylene coordination followed by the insertion into the metal-hydride bond, leading to the formation of the experimentally observed products. Both steps do not require large energies compatible with the experimental conditions. The comparison with the reaction path for the monometallic species gives some hints on the cooperative effects due to the presence of the second metal which is related to its role in the CO release for creating a coordination site for phenylacetylene and not in the insertion energetics. The calculations provide a detailed analysis of the reaction complexity and provide a rationale for the efficiency of the process.

  11. Ag-Sn Bimetallic Catalyst with a Core-Shell Structure for CO2 Reduction.

    Science.gov (United States)

    Luc, Wesley; Collins, Charles; Wang, Siwen; Xin, Hongliang; He, Kai; Kang, Yijin; Jiao, Feng

    2017-02-08

    Converting greenhouse gas carbon dioxide (CO2) to value-added chemicals is an appealing approach to tackle CO2 emission challenges. The chemical transformation of CO2 requires suitable catalysts that can lower the activation energy barrier, thus minimizing the energy penalty associated with the CO2 reduction reaction. First-row transition metals are potential candidates as catalysts for electrochemical CO2 reduction; however, their high oxygen affinity makes them easy to be oxidized, which could, in turn, strongly affect the catalytic properties of metal-based catalysts. In this work, we propose a strategy to synthesize Ag-Sn electrocatalysts with a core-shell nanostructure that contains a bimetallic core responsible for high electronic conductivity and an ultrathin partially oxidized shell for catalytic CO2 conversion. This concept was demonstrated by a series of Ag-Sn bimetallic electrocatalysts. At an optimal SnOx shell thickness of ∼1.7 nm, the catalyst exhibited a high formate Faradaic efficiency of ∼80% and a formate partial current density of ∼16 mA cm(-2) at -0.8 V vs RHE, a remarkable performance in comparison to state-of-the-art formate-selective CO2 reduction catalysts. Density-functional theory calculations showed that oxygen vacancies on the SnO (101) surface are stable at highly negative potentials and crucial for CO2 activation. In addition, the adsorption energy of CO2(-) at these oxygen-vacant sites can be used as the descriptor for catalytic performance because of its linear correlation to OCHO* and COOH*, two critical intermediates for the HCOOH and CO formation pathways, respectively. The volcano-like relationship between catalytic activity toward formate as a function of the bulk Sn concentration arises from the competing effects of favorable stabilization of OCHO* by lattice expansion and the electron conductivity loss due to the increased thickness of the SnOx layer.

  12. Efficiency of bimetallic PtPd on polydopamine modified on various carbon supports for alcohol oxidations

    Science.gov (United States)

    Pinithchaisakula, A.; Ounnunkad, K.; Themsirimongkon, S.; Promsawan, N.; Waenkaew, P.; Saipanya, S.

    2017-02-01

    In this work, the preparation, characterization, and electrocatalytic analysis of the catalysts on various carbon substrates for direct alcohol fuel cells were studied. Selected carbons were modified with/without polydopamine (labelled as PDA-C and C) and further metal electrodeposited incorporated onto the glassy carbon (labelled as 5Pt1Pd/PDA-C and 5Pt1Pd/C). Four various carbon materials were used e.g. graphite (G), carbon nanotube (CNT), graphene (GP) and graphene oxide (GO) and the carbons were modified with PDA denoted as PDA-G, PDA-CNT, PDA-GP and PDA-GO, respectively. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) experimental observation showed narrow size distribution of metal anchored on the PDA-C and C materials. Chemical compositions and oxidation states of the catalysts were determined by X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX). The catalytic performances for small organic electro-oxidation (e.g. methanol and ethanol) were measured by cyclic voltammetry (CV). Among different PDA-C and C catalysts, monometallic Pt showed less activity than the bimetallic catalysts. Among catalysts with PDA, the 5Pt1Pd/PDA-GO catalyst facilitated methanol and ethanol oxidations with high oxidation currents and If/Ib value and stability with low potentials while among catalysts without PDA, the 5Pt1Pd/CNT provides highest activity and stability. It was found that the catalysts with PDA provided high activity and stability than the catalysts without PDA. The improved catalytic performance of the prepared catalysts could be related to the higher active surface area from polymer modification and bimetallic catalyst system in the catalyst composites.

  13. The Effect of Precursor Ligands and Oxidation State in the Synthesis of Bimetallic Nano-Alloys

    KAUST Repository

    LaGrow, Alec P.

    2015-05-12

    The characteristics of bimetallic nanomaterials are dictated by their size, shape and elemental distribution. Solution synthesis is widely utilized to form nanomaterials, such as nanoparticles, with controlled size and shape. However, the effects of variables on the characteristics of bimetallic nanomaterials are not completely understood. In this study, we used a continuous-flow synthetic strategy to explore the effects of the ligands and the oxidation state of a metal precursor in a shape-controlled synthesis on the final shape of the nanomaterials and the elemental distribution within the alloy. We demonstrate that this strategy can tune the size of monodisperse PtM (M=Ni or Cu) alloy nanocrystals ranging from 3 to 16 nm with an octahedral shape using acetylacetonate or halide precursors of Pt(II), Pt(IV) and Ni or Cu (II). The nanoparticles formed from halide precursors showed an enrichment of platinum on their surfaces, and the bromides could oxidatively etch the nanoparticles during synthesis with the O2/Br- pair. The two nanocrystal precursors can be uti-lized independently and can control the size with a trend of Pt(acac)2

  14. Probing the electronic and catalytic properties of a bimetallic surface with 3 nm resolution

    Science.gov (United States)

    Zhong, Jin-Hui; Jin, Xi; Meng, Lingyan; Wang, Xiang; Su, Hai-Sheng; Yang, Zhi-Lin; Williams, Christopher T.; Ren, Bin

    2016-11-01

    An atomic- and molecular-level understanding of heterogeneous catalysis is required to characterize the nature of active sites and improve the rational design of catalysts. Achieving this level of characterization requires techniques that can correlate catalytic performances to specific surface structures, so as to avoid averaging effects. Tip-enhanced Raman spectroscopy combines scanning probe microscopy with plasmon-enhanced Raman scattering and provides simultaneous topographical and chemical information at the nano/atomic scale from ambient to ultrahigh-vacuum and electrochemical environments. Therefore, it has been used to monitor catalytic reactions and is proposed to correlate the local structure and function of heterogeneous catalysts. Bimetallic catalysts, such as Pd-Au, show superior performance in various catalytic reactions, but it has remained challenging to correlate structure and reactivity because of their structural complexity. Here, we show that TERS can chemically and spatially probe the site-specific chemical (electronic and catalytic) and physical (plasmonic) properties of an atomically well-defined Pd(sub-monolayer)/Au(111) bimetallic model catalyst at 3 nm resolution in real space using phenyl isocyanide as a probe molecule (Fig. 1a). We observe a weakened N≡C bond and enhanced reactivity of phenyl isocyanide adsorbed at the Pd step edge compared with that at the Pd terrace. Density functional theory corroborates these observations by revealing a higher d-band electronic profile for the low-coordinated Pd step edge atoms. The 3 nm spatial resolution we demonstrate here is the result of an enhanced electric field and distinct electronic properties at the step edges.

  15. Novel platinum-palladium bimetallic nanoparticles synthesized by Dioscorea bulbifera: anticancer and antioxidant activities.

    Science.gov (United States)

    Ghosh, Sougata; Nitnavare, Rahul; Dewle, Ankush; Tomar, Geetanjali B; Chippalkatti, Rohan; More, Piyush; Kitture, Rohini; Kale, Sangeeta; Bellare, Jayesh; Chopade, Balu A

    2015-01-01

    Medicinal plants serve as rich sources of diverse bioactive phytochemicals that might even take part in bioreduction and stabilization of phytogenic nanoparticles with immense therapeutic properties. Herein, we report for the first time the rapid efficient synthesis of novel platinum-palladium bimetallic nanoparticles (Pt-PdNPs) along with individual platinum (PtNPs) and palladium (PdNPs) nanoparticles using a medicinal plant, Dioscorea bulbifera tuber extract (DBTE). High-resolution transmission electron microscopy revealed monodispersed PtNPs of size 2-5 nm, while PdNPs and Pt-PdNPs between 10 and 25 nm. Energy dispersive spectroscopy analysis confirmed 30.88% ± 1.73% elemental Pt and 68.96% ± 1.48% elemental Pd in the bimetallic nanoparticles. Fourier transform infrared spectra indicated strong peaks at 3,373 cm(-1), attributed to hydroxyl group of polyphenolic compounds in DBTE that might play a key role in bioreduction in addition to the sharp peaks at 2,937, 1,647, 1,518, and 1,024 cm(-1), associated with C-H stretching, N-H bending in primary amines, N-O stretching in nitro group, and C-C stretch, respectively. Anticancer activity against HeLa cells showed that Pt-PdNPs exhibited more pronounced cell death of 74.25% compared to individual PtNPs (12.6%) or PdNPs (33.15%). Further, Pt-PdNPs showed an enhanced scavenging activity against 2,2-diphenyl-1-picrylhydrazyl, superoxide, nitric oxide, and hydroxyl radicals.

  16. Cu-Sn Bimetallic Catalyst for Selective Aqueous Electroreduction of CO2 to CO

    KAUST Repository

    Sarfraz, Saad

    2016-03-23

    We report a selective and stable electrocatalyst utilizing non-noble metals consisting of Cu and Sn for the efficient and selective reduction of CO2 to CO over a wide potential range. The bimetallic electrode was prepared through the electrodeposition of Sn species on the surface of oxide-derived copper (OD-Cu). The Cu surface, when decorated with an optimal amount of Sn, resulted in a Faradaic efficiency (FE) for CO greater than 90% and a current density of −1.0 mA cm−2 at −0.6 V vs. RHE, compared to the CO FE of 63% and −2.1 mA cm−2 for OD-Cu. Excess Sn on the surface caused H2 evolution with a decreased current density. X-ray diffraction (XRD) suggests the formation of Cu-Sn alloy. Auger electron spectroscopy of the sample surface exhibits zero-valent Cu and Sn after the electrodeposition step. Density functional theory (DFT) calculations show that replacing a single Cu atom with a Sn atom leaves the d-band orbitals mostly unperturbed, signifying no dramatic shifts in the bulk electronic structure. However, the Sn atom discomposes the multi-fold sites on pure Cu, disfavoring the adsorption of H and leaving the adsorption of CO relatively unperturbed. Our catalytic results along with DFT calculations indicate that the presence of Sn on reduced OD-Cu diminishes the hydrogenation capability—i.e., the selectivity towards H2 and HCOOH—while hardly affecting the CO productivity. While the pristine monometallic surfaces (both Cu and Sn) fail to selectively reduce CO2, the Cu-Sn bimetallic electrocatalyst generates a surface that inhibits adsorbed H*, resulting in improved CO FE. This study presents a strategy to provide a low-cost non-noble metals that can be utilized as a highly selective electrocatalyst for the efficient aqueous reduction of CO2.

  17. Assessing Level and Effectiveness of Corrosion Education in the UAE

    Directory of Open Access Journals (Sweden)

    Hwee Ling Lim

    2012-01-01

    Full Text Available The consequences of corrosion can be minimized by an engineering workforce well trained in corrosion fundamentals and management. Since the United Arab Emirates incurs the second highest cost of corrosion after Saudi Arabia, this paper examined the quality of corrosion education in the UAE. Surveys with academia and industry respondents showed that dedicated corrosion courses and engineering courses that integrated corrosion into the curricula were available in UAE universities, but graduates had insufficient knowledge of corrosion engineering and superficial understanding of corrosion in real-life design contexts. The effectiveness of corrosion education is determined by both competence in corrosion knowledge/skills and availability of resources (faculty and research. Though most departments would not hire new corrosion-specialist faculty, department research efforts and industry partnerships in corrosion research were present. The paper concluded with recommendations for improving knowledge and skills of future engineers in corrosion and enhancing corrosion instruction to better meet industry needs.

  18. General Corrosion and Localized Corrosion of Waste Package Outer Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J.C.; McCright, R.D.

    2000-01-28

    Alloy 22 is an extremely Corrosion Resistant Material, with a very stable passive film. Based upon exposures in the LTCTF, the GC rates of Alloy 22 are typically below the level of detection, with four outliers having reported rates up to 0.75 #mu#m per year. In any event, over the 10,000 year life of the repository, GC of the Alloy 22 (assumed to be 2 cm thick) should not be life limiting. Because measured corrosion potentials are far below threshold potentials, localized breakdown of the passive film is unlikely under plausible conditions, even in SSW at 120 deg C. The pH in ambient-temperature crevices formed from Alloy 22 have been determined experimentally, with only modest lowering of the crevice pH observed under plausible conditions. Extreme lowering of the crevice pH was only observed under situations where the applied potential at the crevice mouth was sufficient to result in catastrophic breakdown of the passive film above the threshold potential in non-buffered conditions not characteristic of the Yucca Mountain environment. In cases where naturally ocurring buffers are present in the crevice solution, little or no lowering of the pH was observed, even with significant applied potential. With exposures of twelve months, no evidence of crevice corrosion has been observed in SDW, SCW and SAW at temperatures up to 90 deg C. An abstracted model has been presented, with parameters determined experimentally, that should enable performance assessment to account for the general and localized corrosion of this material. A feature of this model is the use of the materials specification to limit the range of corrosion and threshold potentials, thereby making sure that substandard materials prone to localized attack are avoided. Model validation will be covered in part by a companion SMR on abstraction of this model.

  19. Nodular Corrosion Characteristics of Zirconium Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Gil; Jeong, Y. H.; Park, S. Y.; Lee, D. J

    2003-01-15

    This study was reported the effect of the nodular corrosion on the nuclear reactor environmental along with metallurgical influence, also suggested experimental scheme related to evaluate nodular corrosion characteristics of Zr-1 Nb alloy. Remedial strategies against the nodular corrosion should firstly develop plan to assess the effect of the water quality condition (Oxygen, Hydrogen) as well as the boiling on the nodular corrosion, secondarily establish plan to control heat treatment process to keep a good resistance on nodular corrosion in Zr-1Nb alloy as former western reactor did.

  20. Atmospheric corrosion sensor based on strain measurement

    Science.gov (United States)

    Kasai, Naoya; Hiroki, Masatoshi; Yamada, Toshirou; Kihira, Hiroshi; Matsuoka, Kazumi; Kuriyama, Yukihisa; Okazaki, Shinji

    2017-01-01

    In this paper, an in situ atmospheric corrosion sensor based on strain measurement is discussed. The theoretical background for measuring the reduction in thickness of low carbon steel is also presented. Based on the theoretical considerations, a test piece and apparatus for an atmospheric corrosion sensor were designed. Furthermore, in a dry–wet cyclic accelerated exposure experiment, the measured strain indicated thinning of the test piece, although the corrosion product generated on the surface of the test piece affected the results. The atmospheric corrosion sensor would be effective for evaluating atmospheric corrosion of many types of infrastructure.

  1. Analyses of containment structures with corrosion damage

    Energy Technology Data Exchange (ETDEWEB)

    Cherry, J.L.

    1996-12-31

    Corrosion damage to a nuclear power plant containment structure can degrade the pressure capacity of the vessel. For the low-carbon, low- strength steels used in containments, the effect of corrosion on material properties is discussed. Strain-to-failure tests, in uniaxial tension, have been performed on corroded material samples. Results were used to select strain-based failure criteria for corroded steel. Using the ABAQUS finite element analysis code, the capacity of a typical PWR Ice Condenser containment with corrosion damage has been studied. Multiple analyses were performed with the locations of the corrosion the containment, and the amount of corrosion varied in each analysis.

  2. Corrosion of Metal-Matrix Composites with Aluminium Alloy Substrate

    Directory of Open Access Journals (Sweden)

    B. Bobic

    2010-03-01

    Full Text Available The corrosion behaviour of MMCs with aluminium alloy matrix was presented. The corrosion characteristics of boron-, graphite-, silicon carbide-, alumina- and mica- reinforced aluminium MMCs were reviewed. The reinforcing phase influence on MMCs corrosion rate as well as on various corrosion forms (galvanic, pitting, stress corrosion cracking, corrosion fatique, tribocorrosion was discussed. Some corrosion protection methods of aluminium based MMCs were described

  3. The dual role of microbes in corrosion.

    Science.gov (United States)

    Kip, Nardy; van Veen, Johannes A

    2015-03-01

    Corrosion is the result of a series of chemical, physical and (micro) biological processes leading to the deterioration of materials such as steel and stone. It is a world-wide problem with great societal and economic consequences. Current corrosion control strategies based on chemically produced products are under increasing pressure of stringent environmental regulations. Furthermore, they are rather inefficient. Therefore, there is an urgent need for environmentally friendly and sustainable corrosion control strategies. The mechanisms of microbially influenced corrosion and microbially influenced corrosion inhibition are not completely understood, because they cannot be linked to a single biochemical reaction or specific microbial species or groups. Corrosion is influenced by the complex processes of different microorganisms performing different electrochemical reactions and secreting proteins and metabolites that can have secondary effects. Information on the identity and role of microbial communities that are related to corrosion and corrosion inhibition in different materials and in different environments is scarce. As some microorganisms are able to both cause and inhibit corrosion, we pay particular interest to their potential role as corrosion-controlling agents. We show interesting interfaces in which scientists from different disciplines such as microbiology, engineering and art conservation can collaborate to find solutions to the problems caused by corrosion.

  4. Corrosion resistant metallic bipolar plate

    Science.gov (United States)

    Brady, Michael P.; Schneibel, Joachim H.; Pint, Bruce A.; Maziasz, Philip J.

    2007-05-01

    A corrosion resistant, electrically conductive component such as a bipolar plate for a PEM fuel cell includes 20 55% Cr, balance base metal such as Ni, Fe, or Co, the component having thereon a substantially external, continuous layer of chromium nitride.

  5. Corrosion inhibition for distillation apparatus

    Science.gov (United States)

    Baumert, Kenneth L.; Sagues, Alberto A.; Davis, Burtron H.; Schweighardt, Frank K.

    1985-01-01

    Tower material corrosion in an atmospheric or sub-atmospheric distillation tower in a coal liquefaction process is reduced or eliminated by subjecting chloride-containing tray contents to an appropriate ion-exchange resin to remove chloride from such tray contents materials.

  6. CORROSION RESISTANT JACKETED METAL BODY

    Science.gov (United States)

    Brugmann, E.W.

    1958-08-26

    Reactor faul elements of the elongated cylindrical type which are jacketed in a corrosion resistant material are described. Each feel element is comprised of a plurality of jacketed cylinders of fissionable material in end to end abutting relationship, the jackets being welded together at their adjoining ends to retain the individual segments together and seat the interior of the jackets.

  7. Effect of corrosion on flexural bond strength

    Directory of Open Access Journals (Sweden)

    Akshatha Shetty

    2014-09-01

    Full Text Available Corrosion is one of the main causes affecting durability of structures. Corrosion effects on structures cannot be ignored and replaced. To understand the performance of structures there is a need to study the rate at which different corrosion levels occur. Hence the present investigation has been taken up to study the behaviour of NBS (National Bureau of Standard beam specimens made up of Ordinary Portland Cement (OPC and Portland Pozzolona Cement (PPC concrete matrix were subjected to accelerated corrosion for different corrosion levels of 2.5 % to 10 % at 2.5 % interval. Results are compared with those for control beam specimen. It is observed that bond stress value decreases with the increase in corrosion levels. Also corrosion leads to the decline of load carrying capacity.

  8. Evolutionary Computation Techniques for Predicting Atmospheric Corrosion

    Directory of Open Access Journals (Sweden)

    Amine Marref

    2013-01-01

    Full Text Available Corrosion occurs in many engineering structures such as bridges, pipelines, and refineries and leads to the destruction of materials in a gradual manner and thus shortening their lifespan. It is therefore crucial to assess the structural integrity of engineering structures which are approaching or exceeding their designed lifespan in order to ensure their correct functioning, for example, carrying ability and safety. An understanding of corrosion and an ability to predict corrosion rate of a material in a particular environment plays a vital role in evaluating the residual life of the material. In this paper we investigate the use of genetic programming and genetic algorithms in the derivation of corrosion-rate expressions for steel and zinc. Genetic programming is used to automatically evolve corrosion-rate expressions while a genetic algorithm is used to evolve the parameters of an already engineered corrosion-rate expression. We show that both evolutionary techniques yield corrosion-rate expressions that have good accuracy.

  9. Corrosion Rate Monitoring in District Heating Systems

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Nielsen, Lars Vendelbo; Andersen, A.

    2005-01-01

    Quality control in district heating systems to keep uniform corrosion rates low and localized corrosion minimal is based on water quality control. Side-stream units equipped with carbon steel probes for online monitoring were mounted in district heating plants to investigate which techniques would...... be applicable, and if on-line monitoring could improve the quality control. Water quality monitoring was applied as well as corrosion rate monitoring with linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), electrical resistance (ER) technique, mass loss and a crevice corrosion...... cell for localized corrosion risk estimation. Important variations in corrosion rate due to changes in make-up water quality were detected with the continuous monitoring provided by ER and crevice cell, while LPR gave unreliable corrosion rates. The acquisition time of two-three days for EIS...

  10. High Temperature Corrosion on Biodust Firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi

    The high content of alkali metals and chlorine in biomass gives rise to fouling/slagging and corrosion of heat exchange components, such as superheaters, in biomass fired power plants. Increasing the lifetime of these components, and in addition, preventing unwarranted plant shutdowns due...... to their failure, requires understanding of the complex corrosion mechanisms, as well as development of materials that are resistant to corrosion under biomass firing conditions, thereby motivating the current work. To understand the mechanisms of corrosion attack, comprehensive analysis of corrosion products...... was necessary. In the present work, two complementary methodologies based on analysis of cross sections and plan views were applied to achieve comprehensive characterization of corrosion products. The suitability of these methods for both laboratory scale and full scale corrosion investigations was demonstrated...

  11. NASA's Corrosion Technology Laboratory at the Kennedy Space Center: Anticipating, Managing, and Preventing Corrosion

    Science.gov (United States)

    Calle, Luz Marina

    2015-01-01

    The marine environment at NASAs Kennedy Space Center (KSC) has been documented by ASM International (formerly American Society for Metals) as the most corrosive in North America. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pads were rendered even more severe by the highly corrosive hydrochloric acid (HCl) generated by the solid rocket boosters (SRBs). Numerous failures at the launch pads are caused by corrosion. The structural integrity of ground infrastructure and flight hardware is critical to the success, safety, cost, and sustainability of space missions. NASA has over fifty years of experience dealing with unexpected failures caused by corrosion and has developed expertise in corrosion control in the launch and other environments. The Corrosion Technology Laboratory at KSC evolved, from what started as an atmospheric exposure test site near NASAs launch pads, into a capability that provides technical innovations and engineering services in all areas of corrosion for NASA, external partners, and customers.This paper provides a chronological overview of NASAs role in anticipating, managing, and preventing corrosion in highly corrosive environments. One important challenge in managing and preventing corrosion involves the detrimental impact on humans and the environment of what have been very effective corrosion control strategies. This challenge has motivated the development of new corrosion control technologies that are more effective and environmentally friendly. Strategies for improved corrosion protection and durability can have a huge impact on the economic sustainability of human spaceflight operations.

  12. Kinetics of Oxidation of L-Leucine by Mono-and Bimetallic Gold and Silver Nanoparticles in Hydrogen Peroxide Solution

    Institute of Scientific and Technical Information of China (English)

    P.VENKATESAN; J.SANTHANALAKSHMI

    2012-01-01

    The catalytic activity of surfactant stabilized mono- and bimetallic Au and Ag nanoparticles for the oxidation of an amino acid,L-leucine,was studied using hydrogen peroxide as the oxidant.The Au and Ag nanoparticle catalysts exhibited very good catalytic activity and the kinetics of the reaction were found to be pseudo-first order with respect to the amino acid.The effects of several factors,such as oxidant concentration,ionic strength,pH,and catalyst concentration on the reaction,were also investigated.In particular,optimal oxidant and catalyst concentrations were determined.Very high concentrations of the metal nano-catalysts or the oxidant led to a dramatic increase in reaction rate.Moreover,bimetallic Au-Ag catalysts provided higher selectivity than pure Au or Ag.

  13. Breakdown of the Hume-Rothery Rules in Sub-Nanometer-Sized Ta-Containing Bimetallic Small Clusters

    Science.gov (United States)

    Miyajima, Ken; Fukushima, Naoya; Himeno, Hidenori; Yamada, Akira; Mafuné, Fumitaka

    2009-11-01

    The Hume-Rothery rules are empirical rules to predict the solid solubility of metals. We examined whether the rules hold for sub-nanometer-sized small particles. We prepared bimetallic cluster ions in the gas phase by a double laser ablation technique. Taking advantage of the magic compositions of the bimetallic cluster ions relating to the distinguished stabilities, the coalescence or the segregation of Ta and another element in the sub-nanometer-sized clusters was discussed. It was found that W, Nb, and Mo readily coalesce with Ta, while Ag, Al, Au, Co, Cu, Fe, Hf, Ni, Pt, Ti, and V are segregated from Ta. On the basis of these results, we concluded that the Hume-Rothery rules do not hold for sub-nanometer-sized particles.

  14. One step electrochemical synthesis of bimetallic PdAu supported on nafion–graphene ribbon film for ethanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Shendage, Suresh S., E-mail: sureshsshendage@gmail.com; Singh, Abilash S.; Nagarkar, Jayashree M., E-mail: jm.nagarkar@ictmumbai.edu.in

    2015-10-15

    Highlights: • Electrochemical deposition of bimetallic PdAu NPs. • Highly loaded PdAu NPs are obtained. • Nafion–graphene supported PdAu NPs shows good activity for ethanol electrooxidation. - Abstract: A nafion–graphene ribbon (Nf–GR) supported bimetallic PdAu nanoparticles (PdAu/Nf–GR) catalyst was prepared by electrochemical codeposition of Pd and Au at constant potential. The prepared catalyst was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD). The average particle size of PdAu nanoparticles (NPs) determined from XRD was 3.5 nm. The electrocatalytic activity of the PdAu/Nf–GR catalyst was examined by cyclic voltametry. It was observed that the as prepared catalyst showed efficient activity and good stability for ethanol electrooxidation in alkaline medium.

  15. SYNTHESIS OF POLYMER-STABILIZED PLATINUM/RUTHENIUM BIMETALLIC COLLOIDS AND THEIR CATALYTIC PROPERTIES FOR SELECTIVE HYDROGENATION OF CROTONALDEHYDE

    Institute of Scientific and Technical Information of China (English)

    Wei-xia Tu; Han-fan Liu

    2005-01-01

    Polymer-stabilized platinum/ruthenium bimetallic colloids (Pt/Ru) were synthesized by polyol reduction with microwave irradiation and characterized by TEM and XPS. The colloidal nanoparticles have small and narrow size distributions. Catalytic performance of the Pt/Ru colloidal catalysts was investigated on the selective hydrogenation of crontonaldehyde (CRAL). A suitable amount of the added metal ions and base can improve the selectivity of CRAL to crotylalcohol (CROL) remarkably. The catalytic activity and the selectivity are dependent on the compositions of bimetallic colloids. Thereinto, PVP-stabilized 9Pt/1Ru colloid with a molar ratio of metals Pt:Ru = 9:1 shows the highest catalytic selectivity 77.3% to CROL at 333 K under 4.0 MPa of hydrogen.

  16. Titanium corrosion in alkaline hydrogen peroxide environments

    Science.gov (United States)

    Been, Jantje

    1998-12-01

    The corrosion of Grade 2 titanium in alkaline hydrogen peroxide environments has been studied by weight loss corrosion tests, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) measurements and potentiodynamic polarography. Calcium ions and wood pulp were investigated as corrosion inhibitors. In alkaline peroxide, the titanium corrosion rate increased with increasing pH, temperature, and hydrogen peroxide concentration. The corrosion controlling mechanism is thought to be the reaction of the oxide with the perhydroxyl ion. No evidence of thermodynamically stable calcium titanate was found in the surface film of test coupons exposed to calcium-inhibited alkaline peroxide solutions. Calcium inhibition is probably the result of low local alkali and peroxide concentrations at the metal surface produced by reaction of adsorbed calcium with hydrogen peroxide. It has been shown that the inhibiting effect of calcium is temporary, possibly through an effect of calcium on the chemical and/or physical stability of the surface oxide. Pulp is an effective and stable corrosion inhibitor. Raising the pulp concentration decreased the corrosion rate. The inhibiting effect of pulp may be related to the adsorption and interaction of the pulp fibers with H 2O2, thereby decreasing the peroxide concentration and rendering the solution less corrosive. The presence of both pulp and calcium led to higher corrosion rates than obtained by either one inhibitor alone. Replacement of hydrofluoric acid with alkaline peroxide for pickling of titanium was investigated. Titanium corrosion rates in alkaline peroxide exceeded those obtained in the conventional hydrofluoric acid bath. General corrosion was observed with extensive roughening of the surface giving a dull gray appearance. Preferred dissolution of certain crystallographic planes was investigated through the corrosion of a titanium single crystal. Whereas the overall effect on the corrosion rate was small

  17. Buckling of a Shallow Rectangular Bimetallic Shell Subjected to Outer Loads and Temperature and Supported at Four Opposite Points

    OpenAIRE

    M. Jakomin; Kosel, F.; Kosel, T.

    2009-01-01

    We have formulated a geometric non-linear mathematical-physical model of the snap-through of the system of a thin-walled shallow bimetallic translation shell in a homogenous temperature field according to the theory of large displacements, moderate rotations, and small strains of the shell element. The model enables the calculation of the geometric conditions, of shallow translation shells, due to the influences of temperature and mechanical loads. The results are based on the numeric solutio...

  18. Synergetic effects leading to coke-resistant NiCo bimetallic catalysts for dry reforming of methane

    KAUST Repository

    Li, Lidong

    2015-01-08

    A new dry reforming of methane catalyst comprised of NiCo bimetallic nanoparticles and a Mgx(Al)O support that exhibits high coke resistance and long-term on-stream stability is reported. The structural characterization by XRD, TEM, temperature-programmed reduction, and BET analysis demonstrates that the excellent performance of this catalyst is ascribed to the synergy of various parameters, including metal-nanoparticle size, metal-support interaction, catalyst structure, ensemble size, and alloy effects.

  19. Facile synthesis of Pd-based bimetallic nanocrystals and their application as catalysts for methanol oxidation reaction

    Science.gov (United States)

    Xi, Pinxian; Cao, Yang; Yang, Fengchun; Ma, Cai; Chen, Fengjuan; Yu, Sha; Wang, Shuai; Zeng, Zhengzhi; Zhang, Xin

    2013-06-01

    We employed an efficient and facile route to synthesise monodisperse Pd-based bimetallic nanocrystals (MPd: M = Cu, Co and Ni) via a controlled co-reduction of Pd(ii) chloride and M(ii) nitrate at 200-230 °C in the presence of oleylamine (OAm). These monodisperse Pd-based nanocrystals have small dimensions, unique structures and homogeneous morphology, thus exhibit efficient catalytic activities for methanol oxidation in alkaline solution, which is much better than commercial Pd/C with same amount of palladium. The catalytic activities of these nanocrystals followed the order of NiPd/C > CoPd/C > CuPd/C > commercial Pd/C, due to the different synergistic effects. Our results show that these Pd-based bimetallic nanocrystals can be promising as practical catalysts for methanol oxidation reactions and other catalytic reactions in further investigations.We employed an efficient and facile route to synthesise monodisperse Pd-based bimetallic nanocrystals (MPd: M = Cu, Co and Ni) via a controlled co-reduction of Pd(ii) chloride and M(ii) nitrate at 200-230 °C in the presence of oleylamine (OAm). These monodisperse Pd-based nanocrystals have small dimensions, unique structures and homogeneous morphology, thus exhibit efficient catalytic activities for methanol oxidation in alkaline solution, which is much better than commercial Pd/C with same amount of palladium. The catalytic activities of these nanocrystals followed the order of NiPd/C > CoPd/C > CuPd/C > commercial Pd/C, due to the different synergistic effects. Our results show that these Pd-based bimetallic nanocrystals can be promising as practical catalysts for methanol oxidation reactions and other catalytic reactions in further investigations. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00912b

  20. Enzymatic plasmonic engineering of Ag/Au bimetallic nanoshells and their use for sensitive optical glucose sensing.

    Science.gov (United States)

    He, Haili; Xu, Xiaolong; Wu, Haoxi; Jin, Yongdong

    2012-04-03

    Enzyme works for plasmonic nanostructure: an interesting enzyme-responsive hybrid Ag/Au-GOx bimetallic nanoshell (NS) system is reported, in which control over the enzyme reaction of glucose oxidase (GOx) can automatically fine-tune the morphology (from complete NS to porous NS) and optical properties of the hybrid nanostructure. The phenomenon is further exploited as a new platform for sensitive optical glucose sensing.

  1. The use of mechanical alloying for the preparation of palladized magnesium bimetallic particles for the remediation of PCBs.

    Science.gov (United States)

    Coutts, Janelle L; Devor, Robert W; Aitken, Brian; Hampton, Michael D; Quinn, Jacqueline W; Clausen, Christian A; Geiger, Cherie L

    2011-09-15

    The kinetic rate of dechlorination of a polychlorinated biphenyl (PCB-151) by mechanically alloyed Mg/Pd was studied for optimization of the bimetallic system. Bimetal production was first carried out in a small-scale environment using a SPEX 8000M high-energy ball mill with 4-μm-magnesium and palladium impregnated on graphite, with optimized parameters including milling time and Pd-loading. A 5.57-g sample of bimetal containing 0.1257% Pd and ball milled for 3 min resulted in a degradation rate of 0.00176 min(-1)g(-1) catalyst as the most reactive bimetal. The process was then scaled-up, using a Red Devil 5400 Twin-Arm Paint Shaker, fitted with custom plates to hold milling canisters. Optimization parameters tested included milling time, number of ball bearings used, Pd-loading, and total bimetal mass milled. An 85-g sample of bimetal containing 0.1059% Pd and ball-milled for 23 min with 16 ball bearings yielded the most reactive bimetal with a degradation rate of 0.00122 min(-1)g(-1) catalyst. Further testing showed adsorption did not hinder extraction efficiency and that dechlorination products were only seen when using the bimetallic system, as opposed to any of its single components. The bimetallic system was also tested for its ability to degrade a second PCB congener, PCB-45, and a PCB mixture (Arochlor 1254); both contaminants were seen to degrade successfully.

  2. Bimetallic Au/Pd catalyzed aerobic oxidation of alcohols in the poly(ethylene glycol)/CO2 system

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Bimetallic Au/Pd nanoparticles were prepared and used to catalyze oxidation of alcohols in the poly(ethylene glycol) (PEG)/CO2 biphasic system using O2 as the oxidant without adding any base.The catalytic activity of Au/Pd bimetal with different mole ratios was studied using benzyl alcohol as the substrate.It was found that bimetallic Au/Pd nanoparticles with Au:Pd=1:3.5 had higher catalytic activity than monometallic Au,Pd and the bimetallic Au/Pd nanoparticles with other molar ratios.The effect of CO2 pressure on the oxidation of benzyl alcohol and 1-phenylethanol in PEG/CO2 was investigated.It was demonstrated that CO2 pressure could be used to tune the conversion and selectivity of the reactions effectively.α,β-Unsaturated alcohols were also studied and found to be more reactive than benzyl alcohol and 1-phenylethanol.Recycling experiments showed that the Au/Pd/PEG/CO2 catalytic system could be recycled at least four times without reducing the activity.In addition,the catalytic system is clean and the products can be separated easily.

  3. Polymer Film Supported Bimetallic Au-Ag Catalysts for Electrocatalytic Oxidation of Ammonia Borane in Alkaline Media

    Institute of Scientific and Technical Information of China (English)

    Şükriye Ulubay Karabiberoglu; ÇagrCeylan Koçak; Süleyman Kocak; Zekerya Dursun

    2016-01-01

    Ammonia borane is widely used in most areas including fuel cell applications. The present paper describes electrochemical behavior of ammonia borane in alkaline media on the poly(p-aminophenol) film modified with Au and Ag bimetallic nanoparticles. The glassy carbon electrode was firstly covered with polymeric film electrochemically and then, Au, Ag, and Au–Ag nanoparticles were deposited on the polymeric film, respectively. The surface morphology and chemical composition of these electrodes were examined by scanning electron microscopy, transmission electron microscopy, electrochemical impedance spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. It was found that alloyed Au–Ag bimetallic nanoparticles are formed. Electrochemical measurements indicate that the developed electrode modified by Au–Ag bimetallic nanoparticles exhibit the highest electrocatalytic activity for ammonia borane oxidation in alkaline media. The rotating disk electrode voltammetry demonstrates that the developed electrode can catalyze almost six-electron oxidation pathway of ammonia borane. Our results may be attractive for anode materials of ammonia borane fuel cells under alkaline conditions.

  4. Atomic structure and thermal stability of Pt-Fe bimetallic nanoparticles: from alloy to core/shell architectures.

    Science.gov (United States)

    Huang, Rao; Wen, Yu-Hua; Shao, Gui-Fang; Sun, Shi-Gang

    2016-06-22

    Bimetallic nanoparticles comprising noble metal and non-noble metal have attracted intense interest over the past few decades due to their low cost and significantly enhanced catalytic performances. In this article, we have explored the atomic structure and thermal stability of Pt-Fe alloy and core-shell nanoparticles by molecular dynamics simulations. In Fe-core/Pt-shell nanoparticles, Fe with three different structures, i.e., body-centered cubic (bcc), face-centered cubic (fcc), and amorphous phases, has been considered. Our results show that Pt-Fe alloy is the most stable configuration among the four types of bimetallic nanoparticles. It has been discovered that the amorphous Fe cannot stably exist in the core and preferentially transforms into the fcc phase. The phase transition from bcc to hexagonal close packed (hcp) has also been observed in bcc-Fe-core/Pt-shell nanoparticles. In contrast, Fe with the fcc structure is the most preferred as the core component. These findings are helpful for understanding the structure-property relationships of Pt-Fe bimetallic nanoparticles, and are also of significance to the synthesis and application of noble metal based nanoparticle catalysts.

  5. Bimetallic nanostructures as active Raman markers: gold-nanoparticle assembly on 1D and 2D silver nanostructure surfaces.

    Science.gov (United States)

    Gunawidjaja, Ray; Kharlampieva, Eugenia; Choi, Ikjun; Tsukruk, Vladimir V

    2009-11-01

    It is demonstrated that bimetallic silver-gold anisotropic nanostructures can be easily assembled from various nanoparticle building blocks with well-defined geometries by means of electrostatic interactions. One-dimensional (1D) silver nanowires, two-dimensional (2D) silver nanoplates, and spherical gold nanoparticles are used as representative building blocks for bottom-up assembly. The gold nanoparticles are electrostatically bound onto the 1D silver nanowires and the 2D silver nanoplates to give bimetallic nanostructures. The unique feature of the resulting nanostructures is the particle-to-particle interaction that subjects absorbed analytes to an enhanced electromagnetic field with strong polarization dependence. The Raman activity of the bimetallic nanostructures is compared with that of the individual nanoparticle blocks by using rhodamine 6G solution as the model analyte. The Raman intensity of the best-performing silver-gold nanostructure is comparable with the dense array of silver nanowires and silver nanoplates that were prepared by means of the Langmuir-Blodgett technique. An optimized design of a single-nanostructure substrate for surface-enhanced Raman spectroscopy (SERS), based on a wet-assembly technique proposed here, can serve as a compact and low-cost alternative to fabricated nanoparticle arrays.

  6. Sonophotodeposition of bimetallic photocatalysts Pd-Au/TiO2 : application to selective oxidation of methanol to methyl formate.

    Science.gov (United States)

    Colmenares, Juan C; Lisowski, Paweł; Łomot, Dariusz; Chernyayeva, Olga; Lisovytskiy, Dmytro

    2015-05-22

    The aim of this work is to develop bimetallic Pd-Au/TiO2 P90 systems, which are highly active and selective for the photocatalytic oxidation of methanol to form methyl formate. Modification of commercial TiO2 P90 with Pd-Au nanoparticles was successfully achieved for the first time by means of a sonophotodeposition (SPD) method. The prepared materials were characterized by TEM, UV/Vis spectroscopy, X-ray photoelectron spectroscopy, and powder XRD. The Pd-Au bimetallic nanoparticles supported on titania exhibited remarkably enhanced catalytic activity in selective methanol oxidation to form methyl formate due to the synergism of Au and Pd particles, as well as the strong interaction between TiO2 and Pd-Au. SPD is a green methodology that can be used to prepare well-defined bimetallic surfaces on semiconductor supports with great promise for catalytic applications, in which selectivity can be tuned through adjustment of the surface composition.

  7. Microencapsulation Technology for Corrosion Mitigation by Smart Coatings

    Science.gov (United States)

    Buhrow, Jerry; Li, Wenyan; Jolley, Scott; Calle, Luz M.

    2011-01-01

    A multifunctional, smart coating for the autonomous control of corrosion is being developed based on micro-encapsulation technology. Corrosion indicators as well as corrosion inhibitors have been incorporated into microcapsules, blended into several paint systems, and tested for corrosion detection and protection effectiveness. This paper summarizes the development, optimization, and testing of microcapsules specifically designed to be incorporated into a smart coating that will deliver corrosion inhibitors to mitigate corrosion autonomously. Key words: smart coating, corrosion inhibition, microencapsulation, microcapsule, pH sensitive microcapsule, corrosion inhibitor, corrosion protection pain

  8. Electrochemical characterisation speeds up prediction of corrosion behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Schuring, E.W.; Hooijmans, J.W. [ECN Environment and Energy Engineering, Petten (Netherlands)

    2013-04-15

    The contents of this presentation show the following elements: Introduction; Corrosion in real life; Why Electrochemical characterisation of corrosion; Applications (corrosion resistance coatings, corrosion behaviour (brazed) joints); Available electrochemical corrosion techniques; Standards; Conclusions. In the Conclusions the corrosion screening method is summarized: ECN method fast; within 1h -1 week results depending on test method; Fast pre-selection of promising materials/combinations (cost savings); Determining of corrosion initiation; Determination of corrosion mechanisms and propagation; Life time predictions possible; Strong combination with metallographic post-investigation; Ranking materials / constructions for corrosion performance.

  9. Corrosion inhibition of a hygroscopic inorganic dust-depressor

    Institute of Scientific and Technical Information of China (English)

    Longzhe Jin; Lu Wang; Dongke Chen

    2006-01-01

    Metallic corrosion is a serious problem in the application of a hygroscopic inorganic dust-depressor. The basic characteristics of a hygroscopic inorganic dust-depressor and its corrosivity, corrosion mechanism, as well as the principle of corrosion inhibition were analyzed. The static mass-loss test was carried out to investigate the corrosion behavior and the effect of the dustdepressor. The static corrosion rates of steel specimens were measured in six different corrosion inhibitor solutions of the dustdepressor, and the suitable corrosion inhibitors for the dust-depressor to reduce the corrosivity were found out.

  10. INTERNAL CORROSION MONITORING IN OFFSHORE PLATFORMS

    Directory of Open Access Journals (Sweden)

    Fernando Benedicto Mainier

    2008-08-01

    Full Text Available Corrosion is one of the main causes of failures in equipment and pipes in off-shore oil production. These failures harm the process, slow the production operational chronogram, and generate high costs of maintenance, beyond generation risks to health and environment. Due to the fact that most of the equipment, tubing and pipes of production platforms are made of steel, in general, carbon steel, the industry of petroleum exploration will always coexist with the corrosive process. The use of a Corrosion Monitoring Plan to diagnostic, to control and to manage the evolution of corrosives process in off-shore oil platforms is the strategy proposed in this work to prevent problems as described above. The Internal Corrosion Monitoring Plan (ICMP, is based on lab analysis of the corrosively of fluids and residues showed periodically in off-shore operational platform; in the corrosion rate determined by the periodic use of test bodies installed inside off-shore oil platforms tubing systems, as mass loss coupons and electric resistance probes; and finally, in periodic operational data collect obtained during the off-shore oil platform systems operation. The ICMP will direct and manage the actions to be taken in case of aggravation of a corrosive process, quickly identifying to the corrosive mechanisms and its localization in the various systems of the platforms. The optimized use of the corrosion inhibitor and other chemical products are one of the main advantages of the ICMP.

  11. Corrosion Protection of Electrically Conductive Surfaces

    Directory of Open Access Journals (Sweden)

    Jian Song

    2012-11-01

    Full Text Available The basic function of the electrically conductive surface of electrical contacts is electrical conduction. The electrical conductivity of contact materials can be largely reduced by corrosion and in order to avoid corrosion, protective coatings must be used. Another phenomenon that leads to increasing contact resistance is fretting corrosion. Fretting corrosion is the degradation mechanism of surface material, which causes increasing contact resistance. Fretting corrosion occurs when there is a relative movement between electrical contacts with surfaces of ignoble metal. Avoiding fretting corrosion is therefore extremely challenging in electronic devices with pluggable electrical connections. Gold is one of the most commonly used noble plating materials for high performance electrical contacts because of its high corrosion resistance and its good and stable electrical behavior. The authors have investigated different ways to minimize the consumption of gold for electrical contacts and to improve the performance of gold plating. Other plating materials often used for corrosion protection of electrically conductive surfaces are tin, nickel, silver and palladium. This paper will deal with properties and new research results of different plating materials in addition to other means used for corrosion protection of electrically conductive surfaces and the testing of corrosion resistance of electrically conductive surfaces.

  12. 49 CFR 192.477 - Internal corrosion control: Monitoring.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control: Monitoring. 192.477... Control § 192.477 Internal corrosion control: Monitoring. If corrosive gas is being transported, coupons... internal corrosion. Each coupon or other means of monitoring internal corrosion must be checked two...

  13. 49 CFR 192.491 - Corrosion control records.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Corrosion control records. 192.491 Section 192.491... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Requirements for Corrosion Control § 192.491 Corrosion... detail to demonstrate the adequacy of corrosion control measures or that a corrosive condition does...

  14. Corrosion Behaviour of Titanium Anodized Film in Different Corrosive Environments

    Directory of Open Access Journals (Sweden)

    Mr. Sunil D. Kahar

    2014-07-01

    Full Text Available Anodizing is an electrochemical process in which thickness of the natural oxide layer is increased and converted it into a decorative, durable, corrosion-resistant film. Titanium is used as a biocompatible material in human implants due to its excellent corrosion and wears resistance. Stable, continuous, highly adherent, and protective oxide films can be developed on titanium using various acid or alkaline baths. Anodizing of titanium generates a spectrum of different color without use of dyes. This spectrum of color dependent on the thickness of the oxide, voltage ranges, interference of light reflecting off the oxide surface and reflecting off the underlying metal surface. The anodized film of Titanium is mainly consists of TiO2 or mixtures of TiO2 & Ti2O3 etc. In the present work, Pure Titanium plate has been anodized using bath of Chromic Acid at different voltage range. The anodized film is characterized by visual observation, SEM & EDAX analysis & A.C Impedance Spectroscopy, while the corrosion studies were performed using Potentiodynamic studies were performed in 3.5% NaCl & 0.1N H2SO4. The Results show that the anodized film of Titanium show different spectrum of colors from Brown-Violet-Tea or Peacock. SEM & EDAX analyses show that the anodized film of Titanium is mainly made up of TiO2 and Ti2O3. Potentiodynamic study implies that the film developed on Titanium using the bath of Chromic Acid exhibits good corrosion resistance. The A.C. Impedance study shows that the film is more compact, adherent and more uniform in chromic acid bath.

  15. Pt-based Bi-metallic Monolith Catalysts for Partial Upgrading of Microalgae Oil

    Energy Technology Data Exchange (ETDEWEB)

    Lawal, Adeniyi [Stevens Inst. of Technology, Hoboken, NJ (United States); Manganaro, James [Anasyn LLC, Princeton, NJ (United States); Goodall, Brian [Valicor Renewables LLC, Dexter, MI (United States); Farrauto, Robert [Columbia Univ., New York, NY (United States)

    2015-03-24

    Valicor’s proprietary wet extraction process in conjunction with thermochemical pre-treatment was performed on algal biomass from two different algae strains, Nannochloropsis Salina (N.S.) and Chlorella to produce algae oils. Polar lipids such as phospholipids were hydrolyzed, and metals and metalloids, known catalyst poisons, were separated into the aqueous phase, creating an attractive “pre-refined” oil for hydrodeoxygenation (HDO) upgrading by Stevens. Oil content and oil extraction efficiency of approximately 30 and 90% respectively were achieved. At Stevens, we formulated a Pt-based bi-metallic catalyst which was demonstrated to be effective in the hydro-treating of the algae oils to produce ‘green’ diesel. The bi-metallic catalyst was wash-coated on a monolith, and in conjunction with a high throughput high pressure (pilot plant) reactor system, was used in hydrotreating algae oils from N.S. and Chlorella. Mixtures of these algae oils and refinery light atmospheric gas oil (LAGO) supplied by our petroleum refiner partner, Marathon Petroleum Corporation, were co-processed in the pilot plant reactor system using the Pt-based bi-metallic monolith catalyst. A 26 wt% N.S. algae oil/74 wt % LAGO mixture hydrotreated in the reactor system was subjected to the ASTM D975 Diesel Fuel Specification Test and it met all the important requirements, including a cetane index of 50.5. An elemental oxygen analysis performed by an independent and reputable lab reported an oxygen content of trace to none found. The successful co-processing of a mixture of algae oil and LAGO will enable integration of algae oil as a refinery feedstock which is one of the goals of DOE-BETO. We have presented experimental data that show that our precious metal-based catalysts consume less hydrogen than the conventional hydrotreating catalyst NiMo Precious metal catalysts favor the hydrodecarbonylation/hydrodecarboxylation route of HDO over the dehydration route preferred by base metal

  16. A non-destructive test method to monitor corrosion products and corrosion-induced cracking in reinforced cement based materials

    DEFF Research Database (Denmark)

    Michel, Alexander; Pease, Bradley Justin; Peterova, Adela;

    2011-01-01

    ) was conducted to describe the impact of water-to-cement ratio and corrosion current density (i.e., corrosion rate) on the reinforcement corrosion process. Focus was placed, in particular on the determination of the corrosion accommodating region (CAR) and time to corrosion-induced cracking. Experimental results...

  17. Corrosion-Activated Micro-Containers for Environmentally Friendly Corrosion Protective Coatings

    Science.gov (United States)

    Li, Wenyan; Buhrow, J. W.; Zhang, X.; Johnsey, M. N.; Pearman, B. P.; Jolley, S. T.; Calle, L. M.

    2016-01-01

    This work concerns the development of environmentally friendly encapsulation technology, specifically designed to incorporate corrosion indicators, inhibitors, and self-healing agents into a coating, in such a way that the delivery of the indicators and inhibitors is triggered by the corrosion process, and the delivery of self-healing agents is triggered by mechanical damage to the coating. Encapsulation of the active corrosion control ingredients allows the incorporation of desired autonomous corrosion control functions such as: early corrosion detection, hidden corrosion detection, corrosion inhibition, and self-healing of mechanical damage into a coating. The technology offers the versatility needed to include one or several corrosion control functions into the same coating.The development of the encapsulation technology has progressed from the initial proof-of-concept work, in which a corrosion indicator was encapsulated into an oil-core (hydrophobic) microcapsule and shown to be delivered autonomously, under simulated corrosion conditions, to a sophisticated portfolio of micro carriers (organic, inorganic, and hybrid) that can be used to deliver a wide range of active corrosion ingredients at a rate that can be adjusted to offer immediate as well as long-term corrosion control. The micro carriers have been incorporated into different coating formulas to test and optimize the autonomous corrosion detection, inhibition, and self-healing functions of the coatings. This paper provides an overview of progress made to date and highlights recent technical developments, such as improved corrosion detection sensitivity, inhibitor test results in various types of coatings, and highly effective self-healing coatings based on green chemistry. The NASA Kennedy Space Centers Corrosion Technology Lab at the Kennedy Space Center in Florida, U.S.A. has been developing multifunctional smart coatings based on the microencapsulation of environmentally friendly corrosion

  18. Microbiologically Influenced Corrosion: an Update

    Science.gov (United States)

    2014-01-01

    the material that failed was carbon steel and the electrolyte were saline waters, but the microorgan- isms, the environments and the corrosion...different salinities . Martin et al.42 demonstrated that Ecorr ennoblement was site specific, varying 100 mV versus SCE between locations, with higher...microbial consortium of the fungus Aspergillus niger and bacteria influenced the corrosion–inhibiting effectiveness of Crz6 leached from chromate (CrO{24

  19. Electrochemical corrosion testing of metal waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, D. P.; Peterson, J. J.; Katyal, H. K.; Keiser, D. D.; Hilton, B. A.

    1999-12-14

    Electrochemical corrosion tests have been conducted on simulated stainless steel-zirconium (SS-Zr) metal waste form (MWF) samples. The uniform aqueous corrosion behavior of the samples in various test solutions was measured by the polarization resistance technique. The data show that the MWF corrosion rates are very low in groundwaters representative of the proposed Yucca Mountain repository. Galvanic corrosion measurements were also conducted on MWF samples that were coupled to an alloy that has been proposed for the inner lining of the high-level nuclear waste container. The experiments show that the steady-state galvanic corrosion currents are small. Galvanic corrosion will, hence, not be an important mechanism of radionuclide release from the MWF alloys.

  20. CORROSION MONITORING OF PLUTONIUM OXIDE AND SNF

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, D.G.; Haas, C.M.; Smith, C.M.; Ohl, P.C.

    2003-02-27

    While developing a method to measure pressure in totally sealed stainless steel containers holding spent nuclear fuel at the U.S. DOE Hanford Site, Vista Engineering Technologies, LLC (Vista Engineering) personnel adapted the central concept to corrosion monitoring techniques for the same containers. The ability to monitor corrosion within vessels containing spent nuclear fuel, plutonium and other hazardous materials is imperative for safe storage. Vista Engineering personnel have devised a way to monitor corrosion in a totally sealed stainless steel container using a Magnetically Coupled Corrosion Gauge (MCCG) Patent Pending. The MCCG can be used to detect corrosion as well as measure corrosion rate and does not require any penetration of the containment vessel, which minimizes pressure boundary surface area and sensitive weld materials in the vessels.

  1. Self-organization of bimetallic PdAu nanoparticles on SiO{sub 2} surface

    Energy Technology Data Exchange (ETDEWEB)

    Ruffino, F., E-mail: francesco.ruffino@ct.infn.it; Grimaldi, M. G. [Universita di Catania, Dipartimento di Fisica e Astronomia (Italy)

    2011-06-15

    Bimetallic PdAu nanoparticles on SiO{sub 2} substrate were produced by a sequential room-temperature sputtering deposition method. By the atomic force microscopy technique we studied the nanoparticles self-organization mechanisms in various conditions. First, Pd nucleation and growth proceeds at the substrate defects and the Pd nanoparticles density increase rapidly. During the second sputtering deposition, Au atoms adsorb on the SiO{sub 2} and diffuse toward Pd nanoparticles without forming new nuclei. The Au atoms are trapped by the preformed Pd nanoparticles, forming PdAu bimetallic nanoparticles which size increases. Furthermore, fixing the amount of deposited Pd and increasing the amount of deposited Au, we analyzed the evolution of the PdAu film surface morphology: we observe that the PdAu grows initially as three-dimensional islands; then the PdAu film morphology evolves from compact three-dimensional islands to partially coalesced worm-like structures, followed by a percolation morphology and finally to a continuous and rough film. The application of the interrupted coalescence model allowed us to evaluate the critical mean island diameter R{sub c} Almost-Equal-To 2.8 nm for the partial coalescence process. The application of the dynamic scaling theory of growing interfaces allowed us to evaluate the dynamic growth exponent {beta} = 0.21 {+-} 0.01 from the evolution of the film surface roughness. Finally, fixing the amount of deposited Pd and Au we studied the self-organization mechanism of the PdAu nanoparticles induced by thermal processes performed in the 973-1173 K temperature range. The observed kinetic growth mechanism is consistent with a surface diffusion-limited ripening of the nanoparticles with a temperature-dependent growth exponent. The dependence of the growth exponent on the temperature is supposed to be linked to the variation with the temperature of the characteristics of the PdAu alloy. The activation energy for the surface diffusion

  2. Corrosion Preventive Compounds Lifetime Testing

    Science.gov (United States)

    Hale, Stephanie M.; Kammerer, Catherine C.; Copp, Tracy L.

    2007-01-01

    Lifetime Testing of Corrosion Preventive Compounds (CPCs) was performed to quantify performance in the various environments to which the Space Shuttle Orbiter is exposed during a flight cycle. Three CPCs are approved for use on the Orbiter: RD Calcium Grease, Dinitrol AV-30, and Braycote 601 EF. These CPCs have been rigorously tested to prove that they mitigate corrosion in typical environments, but little information is available on how they perform in the unique combination of the coastal environment at the launch pad, the vacuum of low-earth orbit, and the extreme heat of reentry. Currently, there is no lifetime or reapplication schedule established for these compounds that is based on this combination of environmental conditions. Aluminum 2024 coupons were coated with the three CPCs and exposed to conditions that simulate the environments to which the Orbiter is exposed. Uncoated Aluminum 2024 coupons were exposed to the environmental conditions as a control. Visual inspection and Electro- Impedance Spectroscopy (EIS) were performed on the samples in order to determine the effectiveness of the CPCs. The samples were processed through five mission life cycles or until the visual inspection revealed the initiation of corrosion and EIS indicated severe degradation of the coating.

  3. Corrosion performance of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1993-03-01

    Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe{sub 3}Al-based alloys to improve the engineering ductility of these alloys. This paper describes results from the ongoing program to evaluate the corrosion performance of these alloys. The experimental program at Argonne National Laboratory involvesthermogravimetric analyses of alloys exposed to environments that simulate coal gasification and fluidized-bed combustion. Experiments were conducted at 650--1000{degrees}C in simulated oxygen/sulfur gas mixtures. In addition, oxidation/sulfidation behavior of several alumina-forming Fe-Al and Fe-Cr-Ni-Al alloys was determined for comparison with the corrosion rates obtained on iron aluminides. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HC1-containing gases and in the presence of slag from a slogging gasifier. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales. Thermal cycling tests are used to examine the spalling resistance of the scales.

  4. Corrosion performance of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1993-03-01

    Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe[sub 3]Al-based alloys to improve the engineering ductility of these alloys. This paper describes results from the ongoing program to evaluate the corrosion performance of these alloys. The experimental program at Argonne National Laboratory involvesthermogravimetric analyses of alloys exposed to environments that simulate coal gasification and fluidized-bed combustion. Experiments were conducted at 650--1000[degrees]C in simulated oxygen/sulfur gas mixtures. In addition, oxidation/sulfidation behavior of several alumina-forming Fe-Al and Fe-Cr-Ni-Al alloys was determined for comparison with the corrosion rates obtained on iron aluminides. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HC1-containing gases and in the presence of slag from a slogging gasifier. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales. Thermal cycling tests are used to examine the spalling resistance of the scales.

  5. Corrosion behavior in heat pipe

    Directory of Open Access Journals (Sweden)

    Anurak Rodbumrung

    2016-01-01

    Full Text Available The aim of this study was to perform life testing and determine the effect of working fluid on the corrosion of a heat pipe with a sintered wick. The heat pipe was made from a copper tube. The inner heat pipe was filled with 99.97% pure copper powder as a dendritic for the sintering process. The heat pipe had an outer diameter of 6 mm with a length of 200 mm, and distilled water and ethanol were the working fluids. The operating temperature at the evaporator was 125°C. The analysis consisted of using a scanning electron microscope, energy dispersive X-ray spectrometry and atomic absorption spectroscopy. The results of the scanning electron microscope and energy dispersive X-ray spectrometry analysis showed that the corrosion of the heat pipe was uniform. The result of the atomic absorption spectroscopy indicated that the concentration of the copper in the ethanol as the working fluid was greater than in the distilled water as the working fluid, and the highest concentration of copper particles in the ethanol was 22.7499 ppm or 0.0409 mg after testing for 3000 h. The concentration of copper was higher when the length of the life test increased due to corrosion of the heat pipe.

  6. Aluminum corrosion product release kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Matt, E-mail: Matthew.Edwards@cnl.ca; Semmler, Jaleh; Guzonas, Dave; Chen, Hui Qun; Toor, Arshad; Hoendermis, Seanna

    2015-07-15

    Highlights: • Release of Al corrosion product was measured in simulated post-LOCA sump solutions. • Increased boron was found to enhance Al release kinetics at similar pH. • Models of Al release as functions of time, temperature, and pH were developed. - Abstract: The kinetics of aluminum corrosion product release was examined in solutions representative of post-LOCA sump water for both pressurized water and pressurized heavy-water reactors. Coupons of AA 6061 T6 were exposed to solutions in the pH 7–11 range at 40, 60, 90 and 130 °C. Solution samples were analyzed by inductively coupled plasma atomic emission spectroscopy, and coupon samples were analyzed by secondary ion mass spectrometry. The results show a distinct “boron effect” on the release kinetics, expected to be caused by an increase in the solubility of the aluminum corrosion products. New models were developed to describe both sets of data as functions of temperature, time, and pH (where applicable)

  7. Recognition and Analysis of Corrosion Failure Mechanisms

    OpenAIRE

    Steven Suess

    2006-01-01

    Corrosion has a vast impact on the global and domestic economy, and currently incurs losses of nearly $300 billion annually to the U.S. economy alone. Because of the huge impact of corrosion, it is imperative to have a systematic approach to recognizing and mitigating corrosion problems as soon as possible after they become apparent. A proper failure analysis includes collection of pertinent background data and service history, followed by visual inspection, photographic documentation, materi...

  8. Corrosion of oil-fired domestic boilers

    Energy Technology Data Exchange (ETDEWEB)

    Koebel, M.; Elsener, M.

    1989-05-01

    Depending on the surface temperature of the flue gas side the corrosion of oil fired domestic boilers proceeds either mainly by acid corrosion or by oxygen corrosion: (1) At surface temperatures of 60/sup 0/C and higher the corrosion mechanism of acid corrosion prevails and the corrosion rates amount to 0.1-0.3 mm/year (values referred to continuous burner operation). The corrosion products consist of soluble iron(II)- and iron(III)sulfates. Higher corrosion rates can be attributed to an appreciable catalytic formation of sulfur trioxide on the corrosion products formed on the convective heating surfaces. (2) At surface temperatures of 40/sup 0/C the mechanism of oxygen corrosion already dominates and the corrosion rates are about ten times higher (1.5-3 mm/year, referred to continuous burner operation). The high portion of iron oxide hydrates, especially goethit (/alpha/-FeOOH), makes the corrosion products difficult to remove. (3) Distinctly reduced service lives are also expected for the so called reduced temperature boilers ('Niedertemperaturkessel') and low temperature boilers ('Tieftemperaturkessel'): According to the manufacturers these boilers may be operated at boiler water temperatures well below 60/sup 0/C, as they are equipped with constructive measures to enhance the surface temperature on the flue gas side. However, these measures are only fully effective under stationary conditions. Some of the results were obtained from weight loss measurements on test specimen made from St 35.8 and gray cast iron, that were exposed to the flue gases of an fired experimental boiler. Other important results come from field measurements of the sulfuric acid content of about 30 boilers that are in practical use. (orig.).

  9. The oxidation and corrosion of ODS alloys

    Science.gov (United States)

    Lowell, Carl E.; Barrett, Charles A.

    1990-01-01

    The oxidation and hot corrosion of high temperature oxide dispersion strengthened (ODS) alloys are reviewed. The environmental resistance of such alloys are classified by oxide growth rate, oxide volatility, oxide spalling, and hot corrosion limitations. Also discussed are environmentally resistant coatings for ODS materials. It is concluded that ODS NiCrAl and FeCrAl alloys are highly oxidation and corrosion resistant and can probably be used uncoated.

  10. Oxidation And Hot Corrosion Of ODS Alloy

    Science.gov (United States)

    Lowell, Carl E.; Barrett, Charles A.

    1993-01-01

    Report reviews oxidation and hot corrosion of oxide-dispersion-strengthened (ODS) alloys, intended for use at high temperatures. Classifies environmental resistances of such alloys by rates of growth of oxides, volatilities of oxides, spalling of oxides, and limitations imposed by hot corrosion. Also discusses environmentally resistant coatings for ODS materials. Concludes ODS NICrAl and FeCrAl alloys highly resistant to oxidation and corrosion and can be used uncoated.

  11. Optimising corrosion monitoring in district heating systems

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Thorarinsdottir, R.I.; Andersen, A.

    2002-01-01

    A three-year project - financially supported by the Nordic Industrial Fund - on monitoring of corrosion in district heating systems has been initiated with participation of researchers and industrial partners in Denmark, Finland, Iceland, Norway and Sweden. The primary objective of the project...... is to improve the quality control in district heating systems by corrosion monitoring. In Danish systems electrochemical impedance spectroscopy (EIS), linear polarisation resistance (LPR), high-sensitive electrical resistance (ER) technology, crevice corrosion probes, as well as weight loss coupons...

  12. Natural analogues of nuclear waste glass corrosion.

    Energy Technology Data Exchange (ETDEWEB)

    Abrajano, T.A. Jr.; Ebert, W.L.; Luo, J.S.

    1999-01-06

    This report reviews and summarizes studies performed to characterize the products and processes involved in the corrosion of natural glasses. Studies are also reviewed and evaluated on how well the corrosion of natural glasses in natural environments serves as an analogue for the corrosion of high-level radioactive waste glasses in an engineered geologic disposal system. A wide range of natural and experimental corrosion studies has been performed on three major groups of natural glasses: tektite, obsidian, and basalt. Studies of the corrosion of natural glass attempt to characterize both the nature of alteration products and the reaction kinetics. Information available on natural glass was then compared to corresponding information on the corrosion of nuclear waste glasses, specifically to resolve two key questions: (1) whether one or more natural glasses behave similarly to nuclear waste glasses in laboratory tests, and (2) how these similarities can be used to support projections of the long-term corrosion of nuclear waste glasses. The corrosion behavior of basaltic glasses was most similar to that of nuclear waste glasses, but the corrosion of tektite and obsidian glasses involves certain processes that also occur during the corrosion of nuclear waste glasses. The reactions and processes that control basalt glass dissolution are similar to those that are important in nuclear waste glass dissolution. The key reaction of the overall corrosion mechanism is network hydrolysis, which eventually breaks down the glass network structure that remains after the initial ion-exchange and diffusion processes. This review also highlights some unresolved issues related to the application of an analogue approach to predicting long-term behavior of nuclear waste glass corrosion, such as discrepancies between experimental and field-based estimates of kinetic parameters for basaltic glasses.

  13. Corrosion problems and solutions in oil refining and petrochemical industry

    CERN Document Server

    Groysman, Alec

    2017-01-01

    This book addresses corrosion problems and their solutions at facilities in the oil refining and petrochemical industry, including cooling water and boiler feed water units. Further, it describes and analyzes corrosion control actions, corrosion monitoring, and corrosion management. Corrosion problems are a perennial issue in the oil refining and petrochemical industry, as they lead to a deterioration of the functional properties of metallic equipment and harm the environment – both of which need to be protected for the sake of current and future generations. Accordingly, this book examines and analyzes typical and atypical corrosion failure cases and their prevention at refineries and petrochemical facilities, including problems with: pipelines, tanks, furnaces, distillation columns, absorbers, heat exchangers, and pumps. In addition, it describes naphthenic acid corrosion, stress corrosion cracking, hydrogen damages, sulfidic corrosion, microbiologically induced corrosion, erosion-corrosion, and corrosion...

  14. Accelerated corrosion testing results for specimens containing uncoated reinforcing steel and corrosion inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Kondratova, I. L.; Montes, P.; Bremner, T. W. [New Brunswick Univ., Dept, of Civil Engineering, Fredericton, NB (Canada)

    2000-07-01

    Concrete mixtures (water-cement ratios of 0.25, 0.40. or 0.60) containing uncoated reinforcing bars with a simulated crack, formed transverse to the axis of the bar, and with three commercial corrosion inhibitors added for corrosion protection (organic corrosion inhibitor,calcium nitrate-based corrosion inhibitor, and migratory corrosion inhibitor), were tested for corrosion damage. The objective was to evaluate the effectiveness of the different corrosion inhibitors in uncracked and cracked concrete slabs in a simulated marine environment. The specimens were placed in an accelerated exposure cabinet with four cycles of wetting and drying per day in simulated seawater, and corrosion rates measured using the linear polarization technique. Water-soluble chloride content in the rebars was analyzed at the end of the exposure period. The three corrosion inhibitors were found to show a wide variation in performance. There was a direct correlation between their effectiveness and addition rate. All three appeared to be more effective in reducing corrosion rate in a higher water-to-cement ratio concrete. Consistent performance was provided only by calcium nitrate at an addition rate of 25 litre/cu m of concrete, with water-to-cement ratios of 0.60 and 0.40. Pitting corrosion was observed in all pre-cracked high performance concrete specimens; the depth of the pit tended to be deeper when a corrosion inhibitor was used. 6 refs., 6 tabs., 6 figs.

  15. New corrosion issues in gas sweetening plants

    Energy Technology Data Exchange (ETDEWEB)

    Asperger, R.G. (CLI International and Asperger Technologies, Houston, TX (United States))

    Gas treating plants are experiencing corrosion problems which impact on efficiency and safety. While general corrosion is not particularly hazardous in the gas processing industry, local corrosion is very dangerous since it has several different mechanisms, all of which have dangerously high rates, and it occurs at locations which are hard to find and hard to predict. A newly discovered, velocity-dependent type of corrosion is reported. It is related to yet-undefined species which cause excessively high corrosion in areas of turbulence. This accelerated corrosion is not due to erosion or cavitation, but to a diffusion-limited reaction accelerated by turbulence. A full-flow test loop was built to evaluate the corrosiveness of gas plant solutions at their normal temperature and flow rates. Test runs were conducted with Co[sub 2]-loaded amine solutions for periods of 12 days. Carbon steel specimens mounted in the test loop were examined and corrosion rates calculated. Chromium alloys were shown to be attacked by corrodents in the low-velocity part of the loop and very aggressively attacked in the high-velocity part. The tests demonstrate the need for rigorous monitoring of corrosion in areas of higher velocity such as piping elbows and other points of turbulence. 5 refs., 2 figs., 3 tabs.

  16. Classification of corrosion risk zones using GIS

    Science.gov (United States)

    Georgiou, Nikolas; Anastasiou, Constantina; Tantele, Elia A.; Votsis, Renos A.; Danezis, Chris

    2016-08-01

    Corrosion of steel reinforcement is the major deterioration factor of the RC infrastructures. Several factors are contributing towards increasing the corrosion risk like the exposure and environmental conditions which are a function of the geographical location of the infrastructure. Information for these conditions and their affected areas can be proved valuable at design stage and/or during maintenance planning. This study aims to relate corrosion risk of RC infrastructures with their geographical location. The corrosion risk is quantified through data from NDT methods and subsequently correlated with its location. Therefore high risk areas with structures prone to corrosion deterioration are identified. The latter is implemented via GIS tools in order to create maps that describe how corrosion risk is related to the location of each structure. Two GIS methods are suggested, the grid system and the use of classified areas. Corrosion data has been collected from labs about various constructions in Cyprus and used in conjunction with GIS tools to provide useful information on corrosion identification. The outcome is a digitized map of the Limassol area which indicates the risks levels associated with corrosion of the steel reinforcement.

  17. Fouling corrosion in aluminum heat exchangers

    Directory of Open Access Journals (Sweden)

    Su Jingxin

    2015-06-01

    Full Text Available Fouling deposits on aluminum heat exchanger reduce the heat transfer efficiency and cause corrosion to the apparatus. This study focuses on the corrosive behavior of aluminum coupons covered with a layer of artificial fouling in a humid atmosphere by their weight loss, Tafel plots, electrochemical impedance spectroscopy (EIS, and scanning electron microscope (SEM observations. The results reveal that chloride is one of the major elements found in the fouling which damages the passive film and initiates corrosion. The galvanic corrosion between the metal and the adjacent carbon particles accelerates the corrosive process. Furthermore, the black carbon favors the moisture uptake, and gives the dissolved oxygen greater chance to migrate through the fouling layer and form a continuous diffusive path. The corrosion rate decreasing over time is conformed to electrochemistry measurements and can be verified by Faraday’s law. The EIS results indicate that the mechanism of corrosion can be interpreted by the pitting corrosion evolution mechanism, and that pitting was observed on the coupons by SEM after corrosive exposure.

  18. Corrosion Fatigue in District Heating Water Tanks

    DEFF Research Database (Denmark)

    Maahn, Ernst Emanuel

    1996-01-01

    Three candidate materials for construction of buffer tanks for district heating water have been tested for corrosion fatigue properties in a district heating water environment. The investigation included Slow Strain Rate Testing of plain tensile specimens, crack initiation testing by corrosion...... fatigue of plain tensile specimens and crack growth rate determination for Compact Tensile Specimens under corrosion fatigue conditions. The three materials are equal with respect to stress corrosion sensibility and crack initiation. Crack growth rate is increased with a factor of 4-6 relative to an inert...

  19. Recent Corrosion Research Trends in Weld Joints

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hwan Tae; Kil, Sang Cheol [Korea Institute of Science and Technology Information, Seoul (Korea, Republic of); Hwang, Woon Suk [Inha University, Incheon (Korea, Republic of)

    2007-04-15

    The increasing interest in the corrosion properties of weld joints in the corrosive environment is placing stringent demands on the manufacturing techniques and performance requirements, and the manufacture employs the high quality and efficiency welding process to produce welds. Welding plays an important role in the fabrication of chemical plants, nuclear power plant, ship construction, and this has led to an increasing attention to the corrosion resistant weld joints. This paper covers recent technical trends of welding technologies for corrosion resistance properties including the COMPENDEX DB analysis of welding materials, welding process, and welding fabrications

  20. Corrosion Prevention and Control Planning Guidebook Spiral 3

    Science.gov (United States)

    2007-09-01

    and Design Corrosion Considerations • General corrosion • Galvanic corrosion • Pitting corrosion • Concentration cell corrosion • Dealloying...due to corrosion can often be quantified through physi- cal measurements. These may include plating thickness loss, pit depth measurements, torque...approval) Group II Cadmium, zinc (use requires approval) Aluminum alloy 5052, 5056, A356 (and other casting alloys), 6061 , 6013, 6063 (and other

  1. The effect of organic matter associated with the corrosion products on the corrosion of mild steel in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Wagh, A.B.

    the corrosion of mild steel and the temperature and dissolved oxygen of seawater. In contrast to this, the corrosion and mild steel was inversely related to the organic carbon and water extractable carbohydrates associated with the corrosion products of mild...

  2. Ultrafast carrier dynamics in bimetallic nanostructure-enhanced methylammonium lead bromide perovskites.

    Science.gov (United States)

    Zarick, Holly F; Boulesbaa, Abdelaziz; Puretzky, Alexander A; Talbert, Eric M; DeBra, Zachary R; Soetan, Naiya; Geohegan, David B; Bardhan, Rizia

    2017-01-26

    In this work, we examine the impact of hybrid bimetallic Au/Ag core/shell nanostructures on the carrier dynamics of methylammonium lead tribromide (MAPbBr3) mesoporous perovskite solar cells (PSCs). Plasmon-enhanced PSCs incorporated with Au/Ag nanostructures demonstrated improved light harvesting and increased power conversion efficiency by 26% relative to reference devices. Two complementary spectral techniques, transient absorption spectroscopy (TAS) and time-resolved photoluminescence (trPL), were employed to gain a mechanistic understanding of plasmonic enhancement processes. TAS revealed a decrease in the photobleach formation time, which suggests that the nanostructures improve hot carrier thermalization to an equilibrium distribution, relieving hot phonon bottleneck in MAPbBr3 perovskites. TAS also showed a decrease in carrier decay lifetimes, indicating that nanostructures enhance photoinduced carrier generation and promote efficient electron injection into TiO2 prior to bulk recombination. Furthermore, nanostructure-incorporated perovskite films demonstrated quenching in steady-state PL and decreases in trPL carrier lifetimes, providing further evidence of improved carrier injection in plasmon-enhanced mesoporous PSCs.

  3. Magnetic properties of bimetallic clusters composed of Gd and transition metals

    Science.gov (United States)

    Mukherjee, Prajna; Gupta, Bikash C.; Jena, Puru

    2016-02-01

    Gadolinium, a rare earth metal, is ferromagnetic, while Mn, a transition metal atom, is antiferromagnetic in the bulk phase. Clusters of these elements, however, share some common properties; both exhibit ferrimagnetic behavior and maintain magnetic moments close to their free atomic value. Using density functional theory and generalized gradient approximation for exchange and correlation, we have studied the magnetic properties of bimetallic clusters composed of Gd and Mn to see if they show unusual behavior. The coupling between Gd and Mn spins is found to be antiferromagnetic, while that between Mn atoms is ferromagnetic. Moreover, the bonding between Gd and Mn atoms is stronger than that between the Gd atoms or Mn atoms, thus enabling the possibility of creating more stable magnetic particles. A systematic study of the magnetic and binding properties of clusters composed of Gd atom and other transition metal atoms such as V, Sc, Ti, Cr, Fe, and Co is also carried out to probe the effect of 3d-orbital occupation on magnetic coupling.

  4. Tryptophan-Assisted Synthesis Reduces Bimetallic Gold/Silver Nanoparticle Cytotoxicity and Improves Biological Activity

    Directory of Open Access Journals (Sweden)

    Igor O. Shmarakov

    2014-10-01

    Full Text Available Aiming to reduce the potential in vivo hepato-and neph‐ rotoxicity of Ag/Au bimetallic nanoparticles (NPs stabi‐ lized by sodium dodecyl sulphate (SDS, an approach involving a simultaneous reduction of silver nitrate and tetrachlorauratic acid using tryptophan (Trp as a reduc‐ ing/stabilizing agent was applied during NP synthesis. The obtained Ag/Au/Trp NPs (5-15 nm sized were able to form stable aggregates with an average size of 370-450 nm and were potentially less toxic than Ag/Au/SDS in relation to a mouse model system based on clinical biochemical param‐ eters and oxidative damage product estimation. Ag/Au/Trp NPs were shown to exhibit anticancer activity in relation to a Lewis lung carcinoma model. The data generated from the present study support the fact that the use of tryptophan in NP synthesis is effective in attenuating the potential hepatotoxicity and nephrotoxicity of NPs during their in vivo application.

  5. Pt-Pd bimetallic nanoparticles on MWCNTs: catalyst for hydrogen peroxide electrosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Felix-Navarro, R. M., E-mail: moi6salazar@hotmail.com; Beltran-Gastelum, M.; Salazar-Gastelum, M. I.; Silva-Carrillo, C.; Reynoso-Soto, E. A.; Perez-Sicairos, S.; Lin, S. W. [Centro de Graduados e Investigacion, Instituto Tecnologico de Tijuana (Mexico); Paraguay-Delgado, F. [Centro de Investigacion en Materiales Avanzados (Mexico); Alonso-Nunez, G. [Centro de Nanociencias y Nanotecnologia (Mexico)

    2013-08-15

    Bimetallic nanoparticles of Pt-Pd were deposited by the microemulsion method on a multiwall carbon nanotube (MWCNTs) to obtain a Pt-Pd/MWCNTs for electrocatalytic reduction of O{sub 2} to H{sub 2}O{sub 2}. The activity and selectivity of the catalyst was determined qualitatively by the rotating disk electrode method in acidic medium. The catalyst was spray-coated onto a reticulated vitreous carbon substrate and quantitatively was tested in bulk electrolysis for 20 min under potentiostatic conditions (0.5 V vs Ag/AgCl) in a 0.5 M H{sub 2}SO{sub 4} electrolyte using dissolved O{sub 2}. The bulk electrolysis experiments show that the Pt-Pd/MWCNTs catalyst is more efficient for H{sub 2}O{sub 2} electrogeneration than a MWCNTs catalyst. Nitrobenzene degradation by electrogenerated H{sub 2}O{sub 2} alone and Electro-Fenton process were also tested. Our results show that both processes decompose nitrobenzene, but the Electro-Fenton process does it more efficiently. The prepared nanoparticulated catalyst shows a great potential in environmental applications.

  6. Mechanistic investigation of the reaction of epoxides with heterocumulenes catalysed by a bimetallic aluminium salen complex.

    Science.gov (United States)

    Beattie, Christopher; North, Michael

    2014-06-23

    The bimetallic aluminium(salen) complex [(Al(salen))2O] is known to catalyse the reaction between epoxides and heterocumulenes (carbon dioxide, carbon disulfide and isocyanates) leading to five-membered ring heterocycles. Despite their apparent similarities, these three reactions have very different mechanistic features, and a kinetic study of oxazolidinone synthesis combined with previous kinetic work on cyclic carbonate and cyclic dithiocarbonate synthesis showed that all three reactions follow different rate equations. An NMR study of [Al(salen)]2O and phenylisocyanate provided evidence for an interaction between them, consistent with the rate equation data. A variable-temperature kinetics study on all three reactions showed that cyclic carbonate synthesis had a lower enthalpy of activation and a more negative entropy of activation than the other two heterocycle syntheses. The kinetic study was extended to oxazolidinone synthesis catalysed by the monometallic complex Al(salen)Cl, and this reaction was found to have a much less negative entropy of activation than any reaction catalysed by [Al(salen)]2O, a result that can be explained by the partial dissociation of an oligomeric Al(salen)Cl complex. A mechanistic rationale for all of the results is presented in terms of [Al(salen)]2O being able to function as a Lewis acid and/or a Lewis base, depending upon the susceptibility of the heterocumulene to reaction with nucleophiles.

  7. Enhanced and tunable optical quantum efficiencies from plasmon bandwidth engineering in bimetallic CoAg nanoparticles

    Directory of Open Access Journals (Sweden)

    A. Malasi

    2016-10-01

    Full Text Available Plasmonic nanoparticles are amongst the most effective ways to resonantly couple optical energy into and out of nanometer sized volumes. However, controlling and/or tuning the transfer of this incident energy to the surrounding near and far field is one of the most interesting challenges in this area. Due to the dielectric properties of metallic silver (Ag, its nanoparticles have amongst the highest radiative quantum efficiencies (η, i.e., the ability to radiatively transfer the incident energy to the surrounding. Here we report the discovery that bimetallic nanoparticles of Ag made with immiscible and plasmonically weak Co metal can show comparable and/or even higher η values. The enhancement is a result of the narrowing of the plasmon bandwidth from these bimetal systems. The phenomenological explanation of this effect based on the dipolar approximation points to the reduction in radiative losses within the Ag nanoparticles when in contact with cobalt. This is also supported by a model of coupling between poor and good conductors based on the surface to volume ratio. This study presents a new type of bandwidth engineering, one based on using bimetal nanostructures, to tune and/or enhance the quality factor and quantum efficiency for near and far-field plasmonic applications.

  8. Nanocrystalline MgO supported nickel-based bimetallic catalysts for carbon dioxide reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Meshkani, Fereshteh [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran); Rezaei, Mehran [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran)

    2010-10-15

    Nanocrystalline magnesium oxide with high surface area and plate-like shape was employed as catalyst support for preparation of nickel-based bimetallic catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by X-ray diffraction (XRD), N{sub 2} adsorption (BET), Temperature programmed oxidation and desorption (TPO-TPD), Thermal gravimetric and differential thermal gravimetric (TGA-DTG), H{sub 2} chemisorption and Transmission and electron microscopies (TEM and SEM) analyses. CO{sub 2}-TPD data showed the high CO{sub 2} adsorption capacity of catalysts which improves the resistance of catalysts against the carbon formation. The H{sub 2} chemisorption results also indicated that the addition of Pt to nickel catalyst improved the nickel dispersion. The obtained results revealed that the prepared catalysts showed a high activity and stability during the reaction with a low amount of deposited carbon. Addition of Pt to nickel catalyst improved both the activity and resistivity against carbon formation. (author)

  9. Effects of bimetallic catalysts on synthesis of nitrogen-doped carbon nanotubes as nanoscale energetic materials

    Institute of Scientific and Technical Information of China (English)

    Hao Liu; Yong Zhang; Ruying Li; Xueliang Sun; Hakima Abou-Rachid

    2011-01-01

    Well aligned nitrogen-doped carbon nanotubes (CNx-NTs),as energetic materials,are synthesized on a silicon substrate by aerosol-assisted chemical vapor deposition.Tungsten (W) and molybdenum (Mo) metals are respectively introduced to combine with iron (Fe) to act as a bimetallic co-catalyst layer.Correlations between the composition and shape of the co-catalyst and morphology,size,growth rate and nitrogen doping amount of the synthesized CNx-NTs are investigated by secondary and backscattered electron imaging in a field emission scanning electron microscope (FESEM) and X-ray photoelectron spectrometer (XPS).Compared to pure iron catalyst.W-Fe co-catalyst can result in lower growth rate,larger diameter and wider size distribution of the CNx-NTs; while incorporation of molybdenum into the iron catalyst layer can reduce the diameter and size distribution of the nanotubes.Compared to the sole iron catalyst,Fe-W catalyst impedes nitrogen doping while Fe-Mo catalyst promotes the incorporation of nitrogen into the nanotubes.The present work indicates that CNx-NTs with modulated size,growth rate and nitrogen doping concentration are expected to be synthesized by tuning the size and composition of co-catalysts,which may find great potential in producing CNx-NTs with controlled structure and properties.

  10. Enhancement of bimetallic Fe-Mn/CNTs nano catalyst activity and product selectivity using microemulsion technique

    Institute of Scientific and Technical Information of China (English)

    Zahra; Zolfaghari; Ahmad; Tavasoli; Saber; Tabyar; Ali; Nakhaei; Pour

    2014-01-01

    Bimetallic Fe-Mn nano catalysts supported on carbon nanotubes(CNTs) were prepared using microemulsion technique with water-to-surfactant ratios of 0.4-1.6. The nano catalysts were extensively characterized by different methods and their activity and selectivity in Fischer-Tropsch synthesis(FTS) have been assessed in a fixed-bed microreactor. The physicochemical properties and performance of the nanocatalysts were compared with the catalyst prepared by impregnation method. Very narrow particle size distribution has been produced by the microemulsion technique at relatively high loading of active metal. TEM images showed that small metal nano particles in the range of 3–7 nm were not only confined inside the CNTs but also located on the outer surface of the CNTs. Using microemulsion technique with water to surfactant ratio of0.4 decreased the average iron particle sizes to 5.1 nm. The reduction percentage and dispersion percentage were almost doubled. Activity and selectivity were found to be dependent on the catalyst preparation method and average iron particle size. CO conversion and FTS rate increased from 49.1% to 71.0% and 0.144 to 0.289 gHC/(gcat h), respectively. While the WGS rate decreased from 0.097 to 0.056 gCO2/(gcat h). C5+liquid hydrocarbons selectivity decreased slightly and olefins selectivity almost doubled.

  11. Design and Processing of Bimetallic Aluminum Alloys by Sequential Casting Technique

    Science.gov (United States)

    Karun, Akhil S.; Hari, S.; Ebhota, Williams S.; Rajan, T. P. D.; Pillai, U. T. S.; Pai, B. C.

    2017-01-01

    Sequential casting is a facile and fairly new technique to produce functionally graded materials (FGMs) and components by controlled mold filling process. In the present investigation, functionally graded bimetallic aluminum alloys are produced by sequential gravity casting using A390-A319 and A390-A6061 alloy combinations. The control in pouring time between two melts has shown a significant effect on the quality and nature of interface bonding. The microstructure reveals good interface miscibility achieved through diffusion bonding between the alloys. A higher hardness of 160 BHN in the A390 region is obtained in both sequential cast systems, and a minimum value of 105 and 91 BHN is observed in the A319 and A6061 regions, respectively. The tensile and compression strength for A390-A319 are 337 and 490 MPa, whereas for A390-A6061, they are 364 and 401 MPa, respectively, which are significantly higher compared with the standard values of the base alloys, which confirms strong interface bonding. The A390 region shows higher wear resistance compared with other regions of the sequential cast system. The process described in this study is a potential and efficient approach to create good bonding between two different aluminum alloys to develop advanced functional and structural materials.

  12. thesis of high-purity carbon nanotubes over alumina and silica supported bimetallic catalysts

    Directory of Open Access Journals (Sweden)

    Sanja Ratković

    2009-10-01

    Full Text Available Carbon nanotubes (CNTs were synthesized by a catalytic chemical vapor deposition method (CCVD of ethylene over alumina and silica supported bimetallic catalysts based on Fe, Co and Ni. The catalysts were prepared by a precipitation method, calcined at 600 °C and in situ reduced in hydrogen flow at 700 °C. The CNTs growth was carried out by a flow the mixture of C2H4 and nitrogen over the catalyst powder in a horizontal oven. The structure and morphology of as-synthesized CNTs were characterized using SEM. The as-synthesized nanotubes were purified by acid and basic treatments in order to remove impurities such as amorphous carbon, graphite nanoparticles and metal catalysts. XRD and DTA/TG analyses showed that the amounts of by-products in the purified CNTs samples were reduced significantly. According to the observed results, ethylene is an active carbon source for growing high-density CNTs with high yield but more on alumina-supported catalysts than on their silica- supported counterparts. The last might be explained by SMSI formed in the case of alumina-supported catalysts, resulting in higher active phase dispersion.

  13. Bimetallic strip for low temperature use. [4-300/sup 0/K

    Science.gov (United States)

    Bussiee, J.F.; Welch, D.O.; Suenaga, M.

    A class of mechanically pre-stressed structures is provided suitably bi-layer strips, consisting of a layer of group 5 transition metals in intimate contact with a layer of an intermetallic compound of transition metals with certain group 3A, 4A or 5A metals or metalloids such as Ga, In, Si, Ge, Sn, As or Sb. The changes of Young's modulus of these bi-layered combinations at temperatures in the region of somewhat above absolute zero provides a useful means of sensing temperature changes. Such bi-metallic strips may be used as control strips in thermostats, or in direct dial reading instruments. The structures are made by preparing a sandwich of a group 5B transition metal strip between the substantially thicker strips of an alloy between copper and a predetermined group 3A, 4A or 5A metal or metalloid, holding the three layers are heated, cooled the copper alloys and is removed. Removing one of the two formed interlayer alloys between the transition metal and the metal previously alloyed with copper remain.

  14. Pd-Au bimetallic catalysts: understanding alloy effects from planar models and (supported) nanoparticles.

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Feng; Goodman, Wayne D.

    2012-12-21

    Pd-Au bimetallic catalysts often display enhanced catalytic activities and selectivities compared with Pd-alone catalysts. This enhancement is often caused by two alloy effects, i.e., ensemble and ligand effects. The ensemble effect is dilution of surface Pd by Au. With increasing surface Au coverages, contiguous Pd ensembles disappear and isolated Pd ensembles form. For certain reactions, for example vinyl acetate synthesis, this effect is responsible for reaction rate enhancement via the formation of highly active surface sites, e.g., isolated Pd pairs. The disappearance of contiguous Pd ensembles also switches off side reactions catalyzed by these sites. This explains selectivity increase of certain reactions, for example direct H2O2 synthesis. The ligand effect is electronic perturbation of Au to Pd. By direct charge transfer or affecting bond length, the ligand effect causes the Pd d band to be more filled and the d-band center away from the Fermi level. Both changes make Pd more "atomic like" therefore binding reactants and products weaker. For certain reactions, this eliminates the so-called "self poisoning" and enhances activity/selectivity.

  15. Preparation and characterization of planar Ni–Au bimetallic model catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fan, E-mail: fan.yang@chem.tamu.edu; Yao, Yunxi; Yan, Zhen; Min, Hlaing; Goodman, D. Wayne

    2013-10-15

    Ni–Au bimetallic model catalysts were prepared as thin films on Re(0 0 0 1) or Ru(0 0 0 1) single crystal substrates. Surface compositions and electronic structures of the Ni–Au thin films were characterized by low energy ion scattering spectroscopy and X-ray photoelectron spectroscopy, respectively. Surface alloys were prepared by annealing Ni–Au thin films from 500 to 800 K, resulting in substantial surface enrichment of Au. Annealing a Ni–Au thin film with a 1:1 bulk composition ratio at 700 K for 10 min resulted in a surface alloy with 84% (atomic concentration) of Au in the outermost surface layer. The surface atomic structure was investigated using CO as probe molecules, which exclusively adsorbs on the Ni atoms rather than on the Au atoms at room temperature. Polarization modulation infrared reflection absorption spectroscopy of CO adsorption on Ni–Au surface alloys showed that CO adsorption on two-fold bridge sites decreased and finally disappeared with an increase of Au surface concentration. The absence of Ni bridge site CO adsorption indicated that Ni atoms were isolated by Au atoms on Ni–Au alloyed surface.

  16. Controlled synthesis and magnetic properties of nickel phosphide and bimetallic iron-nickel phosphide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Bhupendra; Ho, Chia-Ling [National Cheng Kung University, Department of Chemical Engineering, Taiwan (China); Tseng, Yuan-Chieh [National Chiao Tung University, Department of Materials Science and Engineering, Taiwan (China); Lo, Chieh-Tsung, E-mail: tsunglo@mail.ncku.edu.tw [National Cheng Kung University, Department of Chemical Engineering, Taiwan (China)

    2012-02-15

    Nickel phosphide (Ni{sub 2}P) and bimetallic iron-nickel phosphides [(Fe{sub x}Ni{sub y}){sub 2}P] nanorods were fabricated by a seeded growth strategy. This strategy utilized pre-synthesized Fe{sub 3}O{sub 4} nanoparticles as seeds and the thermal decomposition of metal precursors by multiple injections in a solution containing trioctylphosphine and didodecyldimethylammonium bromide (DDAB). The nanorods were characterized by transmission electron microscopy, X-ray diffraction, and magnetic measurements were carried out using superconducting quantum interference device (SQUID). The rod length was tunable, ranging from 10 to 110 nm depending on the number of injections, whereas the diameter of the rods was nearly 6 nm. It was found that the rod size increased with the number of injections under the constant total injection concentration and reaction time. In addition, the effect of the DDAB quantity used as a co-surfactant was studied, which showed that an optimum quantity was required to achieve uniform nanorods. Magnetic characterizations were performed over the two kinds of nanorods to identify their respective magnetic phases. The results demonstrated that the Ni{sub 2}P nanorods were defined as a Curie-Weiss paramagnet, whereas the (Fe{sub x}Ni{sub y}){sub 2}P nanorods exhibited superparamagnetic characteristics.

  17. The study of magnetic properties and relaxation processes in Co/Au bimetallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hrubovčák, Pavol [Department of Condensed Matter Physics, P.J. Šafárik University, Park Angelinum 9, Košice (Slovakia); Zeleňáková, Adriana, E-mail: adriana.zelenakova@upjs.sk [Department of Condensed Matter Physics, P.J. Šafárik University, Park Angelinum 9, Košice (Slovakia); Zeleňák, Vladimir [Department of Inorganic Chemistry, P.J. Šafárik University, Moyzesova 11, Košice (Slovakia); Kováč, Jozef [Institute of Experimental Physics, SAS, Watsonova 41, Košice (Slovakia)

    2015-11-15

    Co/Au bimetallic fine nanoparticles were prepared employing the method of microemulsion using reverse micelle as nanoreactor, controlling the particles size. Magnetic and structural properties of two different samples Co/Au1 and Co/Au2 with almost comparable size of Co core and different size of Au layer were studied. The investigation of magnetic relaxation processes present in the particles was carried out by means of ac and dc magnetization data obtained at different temperatures and magnitudes of magnetic field. We observed the existence of superspin glass state characterized by the strong inter-particle interactions in the nanoparticle systems. In this paper, we discuss the attributes of novel superspin glass magnetic state reflected on various features (saturated FC magnetization at low temperatures, shift of the Cole–Cole arc downwards) and calculated parameters (relaxation time, critical exponent zv ∼ 10 and frequency dependent criterion p < 0.05). Comparison of the magnetic properties of two studied samples show that the thickness of diamagnetic Au shell significantly influences the magnetic interactions and change the relaxation dynamics. - Highlights: • Co/Au fine nanoparticles prepared by reverse micelle as nanoreactor, controlling the size. • Existence of superspin glass state confirmed from ac magnetic susceptibility study. • Individual particles exhibit the collective behavior below glass temperature T{sub SSG}. • Influence of diamagnetic shell on the magnetic properties of core–shell nanoparticles.

  18. Nanowire networks and hollow nanospheres of Ag–Au bimetallic alloys at room temperature

    Science.gov (United States)

    Britto Hurtado, R.; Cortez-Valadez, M.; Arizpe-Chávez, H.; Flores-Lopez, N. S.; Álvarez, Ramón A. B.; Flores-Acosta, M.

    2017-03-01

    Due to their physicochemical properties, metallic nanoalloys have potential applications in biomedicine, electrocatalysis and electrochemical sensors, among many other fields. New alternative procedures have emerged in order to reduce production costs and the use of toxic substances. In this study we present a novel low-toxicity synthesis method for the fabrication of nanowire networks (NWNs) and Ag–Au hollow nanospheres. The synthesis process is performed at room temperature without any sophisticated equipment, such as special cameras or furnaces, etc. Transmission electron microscopy showed that the NWNs contain random alloys with a diameter of between 10–13 nm. The radius for the hollow nanospheres is approximately located between 70–130 nm. The absorption bands in the UV–vis spectrum associated with the surface plasmon in Ag–Au bimetallic nanoparticles are highlighted at 385 nm for the NWNs and 643 nm for the hollow nanospheres. The study was performed with low-toxicity substances, such as rongalite, ascorbic acid and sucrose, and showed high efficiency for the fabrication of these types of nanostructures, as well as good stability for long periods of time.

  19. Growth and characterization of bimetallic (Na and K) phthalate single crystals

    Science.gov (United States)

    Amuthambigai, C.; Mahadevan, C. K.; Sahaya Shajan, X.

    2016-10-01

    Bimetallic (Na and K) phthalate single crystals were grown by the solvent evaporation method and characterized. X-ray diffraction (single crystal and powder), Fourier transform infrared spectral and atomic absorption spectral measurements indicate a centrosymmetric trigonal crystal system (space group Pbar{3}1c) with chemical composition as Na0.51K1.49C8O4H4.H2O. UV-Vis-NIR spectral measurement indicates an optical transmittance of 72 % in the wavelength range 300-1200 nm. The crystal is found to be nonlinear optically active due to local non-centrosymmetry. Thermal and mechanical stabilities of the grown crystal were examined by thermogravimetric and microhardness measurements. Electrical (both AC, with various frequencies ranging from 200 Hz to 200 kHz, and DC) measurements were taken at various temperatures ranging from 30 to 60 °C by the parallel plate capacitor method. The electrical parameters considered are found to increase with the increase in temperature. The AC and DC activation energies were also estimated. The observed high dielectric constants and good second harmonic generation efficiency indicate that the crystal is expected to be useful in capacitor technology and photonic devices.

  20. Surface structure and reaction performances of highly dispersed and supported bimetallic catalysts

    Institute of Scientific and Technical Information of China (English)

    林励吾; 杨维慎; 贾继飞; 徐竹生; 张涛; 范以宁; 寇元; 沈俭一

    1999-01-01

    Surface structures of Pt-Sn and Pt-Fe bimetallic catalysts have been investigated by means of Mssbauer spectroscopy, Pt-LⅢ-edge EXAFS and H2-adsorption. The results showed that the second component, such as Sn or Fe, remained in the oxidative state and dispersed on the γ-Al2O3 surface after reduction, while Pt was completely reduced to the metallic state and dispersed on either the metal oxide surface or the γ-Al2O3 surface. By correlating the distribution of Pt species on different surfaces with the reaction and adsorption performances, it is proposed that two kinds of active Pt species existed on the surfaces of both catalysts, named M1 sites and M2 sites. M1 sites are the sites in which Pt directly anchored on the γ-Al2O3 surface, while M2 sites are those in which Pt anchored on the metal oxide surface. M1 sites are favorable for low temperature H2 adsorption, and responsible for the hydrogenolysis reaction and carbon deposition, while M2 sites which adsorb more H2 at higher tem

  1. Porous bimetallic PdNi catalyst with high electrocatalytic activity for ethanol electrooxidation.

    Science.gov (United States)

    Feng, Yue; Bin, Duan; Yan, Bo; Du, Yukou; Majima, Tetsuro; Zhou, Weiqiang

    2017-05-01

    Porous bimetallic PdNi catalysts were fabricated by a novel method, namely, reduction of Pd and Ni oxides prepared via calcining the complex chelate of PdNi-dimethylglyoxime (PdNi-dmg). The morphology and composition of the as-prepared PdNi were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Furthermore, the electrochemical properties of PdNi catalysts towards ethanol electrooxidation were also studied by electrochemical impedance spectrometry (EIS), cyclic voltammetry (CV) and chronoamperometry (CA) measurement. In comparison with porous Pd and commercial Pd/C catalysts, porous structural PdNi catalysts showed higher electrocatalytic activity and durability for ethanol electrooxidation, which may be ascribed to Pd and Ni property, large electroactive surface area and high electron transfer property. The Ni exist in the catalyst in the form of the nickel hydroxides (Ni(OH)2 and NiOOH) which have a high electron and proton conductivity enhances the catalytic activity of the catalysts. All results highlight the great potential application of the calcination-reduction method for synthesizing high active porous PdNi catalysts in direct ethanol fuel cells.

  2. High-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles for phenol hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chao [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China); Yang, Xu [Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Yang, Hui; Huang, Peiyan; Song, Huiyu [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China); Liao, Shijun, E-mail: chsjliao@scut.edu.cn [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China)

    2014-10-01

    Graphical abstract: The addition of Ru could significantly improve the performance of the mesoporous silica nanoparticles supported PdRu/MSN catalyst, which showed over 5 times higher mass activity than the mono-Pd/MSN towards the liquid-phase hydrogenation of phenol. The improved dispersion and the electronic interaction contributed to the enhanced catalytic activity for the catalyst towards phenol hydrogenation. - Highlights: • PdRu bimetal catalyst supported on mesoporous silica nanoparticles was prepared. • The average sizeof PdRu alloy is smaller than that of mono-Pd. • The addition of Ru to Pd modulates the electronic properties between Pd and Ru. • PdRu/MSN catalyst shows superior activity on phenol hydrogenation than Pd/MSN. • PdRu/MSN catalyst shows good selectivity for cyclohexanol to some extent. - Abstract: A high-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles (MSN), PdRu/MSN, was prepared by a facile impregnation–hydrogen reduction method. It was found that PdRu/MSN showed 5 times higher activity than that of Pd/MSN towards the liquid-phase hydrogenation of phenol. The catalysts were characterized comprehensively by multiple techniques, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature program reduction (TPR). It was revealed that adding Ru could effectively improve the Pd dispersion and promote the electronic interaction between the Pd and Ru, both of which contribute to enhancing the catalytic activity.

  3. Optical absorption of (Ag-Au133(SCH352 bimetallic monolayer-protected clusters

    Directory of Open Access Journals (Sweden)

    Alessandro Fortunelli

    2016-10-01

    Full Text Available The evolution of the optical absorption spectrum of bimetallic Ag-Au monolayer-protected clusters (MPC obtained by progressively doping Ag into the experimentally known structure of Au133(SR52 was predicted via rigorous time-dependent density-functional theory (TDDFT calculations. In addition to monometallic Au133(SR52 and Ag133(SR52 species, 5 different (Ag-Au133(SR52 homotops were considered with varying Ag content and site positioning, and their electronic structure and optical response were analyzed in terms of Projected Density Of States (PDOS, the induced or transition electron density, and Transition Component Maps (TCM at selected excitation energies. It was found that Ag doping led to the effects rather different from those encountered in bare metal clusters. And it was also observed that Ag doping could produce structured spectral features, especially in the 3–4 eV range but also in the optical region if Ag atoms were located in the sub-staple region, as rationalized by the accompanying electronic analysis. Additionally, Au doping into the staples of Ag-rich MPC also gave rise to a more homogeneous induced electron density. These findings show the great sensitivity of the electronic response of MPC nanoalloy systems to the exact location of the alloying sites.

  4. Dual-frequency plasmon lasing modes in active three-layered bimetallic Ag/Au nanoshells

    Science.gov (United States)

    Wu, DaJian; Wu, XueWei; Cheng, Ying; Jin, BiaoBing; Liu, XiaoJun

    2015-11-01

    The optical properties of three-layered silver-gold-silica (SGS) nanoshells with gain have been investigated theoretically by using Mie theory. Surface plasmon amplification by stimulated emission of radiation (spaser) phenomena can be observed at two plasmon modes of the active SGS nanoshell in the visible region. It is found with the decrease in the radius of the inner Ag core that the critical value of ɛg″(ωg ) for the super-resonance of the low-energy mode increases first and then decreases while that for the high-energy mode decreases. An interesting overlap between the two curves for the critical value of ɛg″(ωg ) can be found at a special core radius. At this point, two super-resonances can be achieved concurrently at the low- and high-energy modes of the active SGS nanoshell with the same gain coefficient. This dual-frequency spaser based on the bimetallic Ag/Au nanoshell may be an efficient candidate for designing the nanolaser.

  5. Enhanced and tunable optical quantum efficiencies from plasmon bandwidth engineering in bimetallic CoAg nanoparticles

    Science.gov (United States)

    Malasi, A.; Taz, H.; Ehrsam, M.; Goodwin, J.; Garcia, H.; Kalyanaraman, R.

    2016-10-01

    Plasmonic nanoparticles are amongst the most effective ways to resonantly couple optical energy into and out of nanometer sized volumes. However, controlling and/or tuning the transfer of this incident energy to the surrounding near and far field is one of the most interesting challenges in this area. Due to the dielectric properties of metallic silver (Ag), its nanoparticles have amongst the highest radiative quantum efficiencies (η), i.e., the ability to radiatively transfer the incident energy to the surrounding. Here we report the discovery that bimetallic nanoparticles of Ag made with immiscible and plasmonically weak Co metal can show comparable and/or even higher η values. The enhancement is a result of the narrowing of the plasmon bandwidth from these bimetal systems. The phenomenological explanation of this effect based on the dipolar approximation points to the reduction in radiative losses within the Ag nanoparticles when in contact with cobalt. This is also supported by a model of coupling between poor and good conductors based on the surface to volume ratio. This study presents a new type of bandwidth engineering, one based on using bimetal nanostructures, to tune and/or enhance the quality factor and quantum efficiency for near and far-field plasmonic applications.

  6. High Temperature Plasticity of Bimetallic Magnesium and Aluminum Friction Stir Welded Joints

    Science.gov (United States)

    Regev, Michael; El Mehtedi, Mohamad; Cabibbo, Marcello; Quercetti, Giovanni; Ciccarelli, Daniele; Spigarelli, Stefano

    2014-02-01

    The high temperature deformation of a bimetallic AZ31/AA6061 Friction Stir Welded joint was investigated in the present study by constant load creep experiments carried out at 473 K (200 °C). The microstructural analysis revealed the strongly inhomogeneous nature of the weld, which was characterized by an extremely fine grain size in the magnesium-rich zones and by the extensive presence of intermetallic phases. In the high stress regime, the creep strain was concentrated in the refined and particle-rich microstructure of the weld zone, while the AA6061 base metal remained undeformed. In the low stress regime, deformation became more homogeneously distributed between the AZ31 base metal and the weld zone. The creep behavior of the weld was found to obey the constitutive equation describing the minimum creep rate dependence on applied stress for the base AZ31, slightly modified to take into account the finer microstructure and the role of secondary phase particles, i.e., the retardation of grain growth and the obstruction of grain boundary sliding.

  7. NASA's Corrosion Technology Laboratory at the Kennedy Space Center: Anticipating, Managing, and Preventing Corrosion

    Science.gov (United States)

    Calle, Luz Marina

    2014-01-01

    Corrosion is the degradation of a material that results from its interaction with the environment. The marine environment at NASAs Kennedy Space Center (KSC) has been documented by ASM International (formerly American Society for Metals) as the most corrosive in the United States. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pads were rendered even more severe by the 70 tons of highly corrosive hydrochloric acid that were generated by the solid rocket boosters. Numerous failures at the launch pads are caused by corrosion.The structural integrity of ground infrastructure and flight hardware is critical to the success, safety, cost, and sustainability of space missions. As a result of fifty years of experience with launch and ground operations in a natural marine environment that is highly corrosive, NASAs Corrosion Technology Laboratory at KSC is a major source of corrosion control expertise in the launch and other environments. Throughout its history, the Laboratory has evolved from what started as an atmospheric exposure facility near NASAs launch pads into a world-wide recognized capability that provides technical innovations and engineering services in all areas of corrosion for NASA and external customers.This presentation will provide a historical overview of the role of NASAs Corrosion Technology in anticipating, managing, and preventing corrosion. One important challenge in managing and preventing corrosion involves the detrimental impact on humans and the environment of what have been very effective corrosion control strategies. This challenge has motivated the development of new corrosion control technologies that are more effective and environmentally friendly. Strategies for improved corrosion protection and durability can have a huge impact on the economic sustainability of human spaceflight operations.

  8. Environmental Friendly Coatings and Corrosion Prevention For Flight Hardware Project

    Science.gov (United States)

    Calle, Luz

    2014-01-01

    Identify, test and develop qualification criteria for environmentally friendly corrosion protective coatings and corrosion preventative compounds (CPC's) for flight hardware an ground support equipment.

  9. Doping effect on the Janus-like structure of a copper-iron bimetallic nanocluster and its solid-liquid phase transition

    Science.gov (United States)

    Taherkhani, Farid; Seresht, Pegah Freshteh

    2015-04-01

    A molecular dynamics simulation with a new-application potential model has been explored for melting temperature, radial distribution of iron-copper bimetallic nanoclusters, and their bulk for the first time. At low copper weight percentages, the melting temperature changes a little for the bulk structures; however, for nanostructures, the variation of melting temperature is significant. At medium copper-doping values, there is a melting-temperature plateau in bimetallic nanoclusters. For many catalysis applications, Janus-like structures are considered, which occur at around 53% iron weight in copper at room temperature, when copper-iron bimetallic nanoclusters clearly consist of two distinct faces. Our result for the melting temperature of the bulk alloy confirms the experimental result.

  10. Fatigue in the Presence of Corrosion (Fatigue sous corrosion)

    Science.gov (United States)

    1999-03-01

    riennes et de la maintenance des a~ronefs. Cette rencontre a 6t6 A l’origine de discussions soutenues. L’ atelier avait pour objectifs: "* faciliter...of Corrosion/Fatigue Interaction in the Development of Multiple 20 Site Damage in Longitudinal Fuselage Skin Splices by G.F. Eastaugh, A.A. Merati, D.L... site damage in the considerations prevented him from attending. He had planned attachment to the fuselage. He noted that the cracking found to present

  11. Screening of soil corrosivity by field testing: Results and design of an electrochemical soil corrosion probe

    DEFF Research Database (Denmark)

    Nielsen, Lars vendelbo; Bruun, Niels Kåre

    1996-01-01

    The corrosivity of different types of soil have been assessed by exposing carbon-steel plates at 50 different locations in Denmark for an extended period of time. The investigations included weight loss measurements and analysis of the chemical compositions of the corrosion products formed...... on the plates during exposure. An electrochemical soil corrosion probe has been designed and manufactured allowing for simultaneous measurements of several qauntities to predict corrosion. The probe consists of individual sections capable of measuring redox-potential, corrosion potential, soil resistivity...

  12. High Temperature Corrosion under Laboratory Conditions Simulating Biomass-Firing: A Comprehensive Characterization of Corrosion Products

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2014-01-01

    characterization of the corrosion products. The corrosion products consisted of three layers: i) the outermost layer consisting of a mixed layer of K2SO4 and FexOy on a partly molten layer of the initial deposit, ii) the middle layer consists of spinel (FeCr2O4) and Fe2O3, and iii) the innermost layer is a sponge......-like Ni3S2 containing layer. At the corrosion front, Cl-rich protrusions were observed. Results indicate that selective corrosion of Fe and Cr by Cl, active oxidation and sulphidation attack of Ni are possible corrosion mechanisms....

  13. Synthesis and characterization of bimetallic Cu-Ni/ZrO{sub 2} nanocatalysts: H{sub 2} production by oxidative steam reforming of methanol

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Hernandez, R.; Mondragon Galicia, G.; Mendoza Anaya, D.; Palacios, J. [Instituto Nacional de Investigaciones Nucleares; Carretera Mexico-Toluca S/N La Marquesa, Ocoyoacac, Estado de Mexico C.P. 52750 (Mexico); Angeles-Chavez, C. [Programa de Ingenieria Molecular, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas, No. 152, C.P. 07730, Mexico D.F. (Mexico); Arenas-Alatorre, J. [Instituto de Fisica-UNAM, Apartado Postal 20-364, C.P. 01000, Mexico D.F. (Mexico)

    2008-09-15

    Cu/ZrO{sub 2}, Ni/ZrO{sub 2} and bimetallic Cu-Ni/ZrO{sub 2} catalysts were prepared by deposition-precipitation method to produce hydrogen by oxidative steam reforming of methanol (OSRM) reaction in the range of 250-360 C. TPR analysis of the Cu-Ni/ZrO{sub 2} catalyst showed that the presence of Cu facilitates the reduction of the Ni at lower temperatures. In addition, this sample showed two reduction peaks, the former peak was attributed to the reduction of the adjacent Cu and Ni atoms which could be forming a bimetallic Cu-rich phase, and the second was assigned to the remaining Ni atoms forming bimetallic Ni-rich nanoparticles. Transmission Electron Microscopy revealed Cu or Ni nanoparticles on the monometallic samples, while bimetallic nanoparticles were identified on the Cu-Ni/ZrO{sub 2} catalyst. On the other hand, Cu-Ni/ZrO{sub 2} catalyst exhibited better catalytic activity than the monometallic samples. The difference between them was related to the Cu-Ni nanoparticles present on the former catalyst, as well as the bifunctional role of the bimetallic phase and the support that improve the catalytic activity. All the catalysts showed the same selectivity toward H{sub 2} at the maximum reaction temperature and it was {proportional_to}60%. The high selectivity toward CO is associated to the presence of the bimetallic Ni-rich nanoparticles, as evidenced by TEM-EDX analysis, since this behavior is similar to the one showed by the monometallic Ni-catalyst. (author)

  14. Corrosion of RoHS-Compliant Surface Finishes in Corrosive Mixed Flowing Gas Environments

    Science.gov (United States)

    Hannigan, K.; Reid, M.; Collins, M. N.; Dalton, E.; Xu, C.; Wright, B.; Demirkan, K.; Opila, R. L.; Reents, W. D.; Franey, J. P.; Fleming, D. A.; Punch, J.

    2012-03-01

    Recently, the corrosion resistance of printed wiring board (PWB) finishes has generated considerable interest due to field failures observed in various parts of the world. This study investigates the corrosion issues associated with the different lead-free PWB surface finishes. Corrosion products on various PWB surface finishes generated in mixed flowing gas (MFG) environments were studied, and analysis techniques such as scanning electron microscopy, energy-dispersive x-ray, x-ray diffraction, focused ion beam, and scanning Auger microscopy were used to quantify the corrosion layer thickness and determine the composition of corrosion products. The corrosion on organic solderability preservative samples shows similar corrosion products to bare copper and is mainly due to direct attack of copper traces by corrosive gases. The corrosion on electroless nickel immersion gold occurs primarily through the porosity in the film and is accelerated by the galvanic potential between gold and copper; similar results were observed on immersion silver. Immersion tin shows excellent corrosion resistance due to its inherent corrosion resistance in the MFG environment as well as the opposite galvanic potential between tin and copper compared with gold or silver and copper.

  15. Effects of alternating magnetic field on the corrosion rate and corrosion products of copper

    Institute of Scientific and Technical Information of China (English)

    GUO Bin; ZHANG Peng; JIN Yongping; CHENG Shukang

    2008-01-01

    The effects of alternating magnetic field on the corrosion morphologies, corrosion rate, and corrosion products of copper in 3.5% NaCl solution, sea water, and magnetized sea water were investigated using electrochemical test, scanning electron microscopy/energy dispersive analysis system of X-ray (SEM/EDAX), and X-ray diffraction (XRD). The results show that the corrosion rate of copper in magnetized sea water is minimal. Moreover, the surface of the specimen in magnetized sea water is uniform and compact as compared with those in 3.5% NaCl solution and sea water. The corrosion products of copper in magnetized sea water are mainly Cu2O and CuCl2. However, the corrosion products in sea water are CuCl, Cu2Cl(OH)3, and FeCl3·6H2O. The electrochemical corrosion mechanisms of copper in the three media were also discussed.

  16. Field corrosion characterization of soil corrosion of X70 pipeline steel in a red clay soil

    Directory of Open Access Journals (Sweden)

    Shengrong Wang

    2015-06-01

    Full Text Available The corrosion behavior of X70 pipeline steel buried in red soil environment has been studied. The surface morphology and elemental distribution were determined by scanning electron microscopy (SEM,energy dispersive X-ray spectroscopy (EDS, and X-ray diffraction (XRD. The corrosion kinetics was evaluated by weight loss measurement. The results show that in red soil, the corrosion rate of X70 steel decreases with time, and follows the exponential decay law. General corrosion with non-uniform and localized pitting occurred on the steel surface. α-FeOOH was the dominate products during corrosion in whole buried periods, and the corrosion products exhibited well protective properties. The potentiodynamic polarization tests revealed that icorr decreased with time, indicating the improvement of corrosion resistance. The results of Electrochemical impendence spectroscopy (EIS are consistent with potentiodynamic polarization tests.

  17. Corrosion Products and Formation Mechanism During Initial Stage of Atmospheric Corrosion of Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    XIAO Kui; DONG Chao-fang; LI Xiao-gang; WANG Fu-ming

    2008-01-01

    The formation and development of corrosion products on carbon steel surface during the initial stage of atmospheric corrosion in a laboratory simulated environment have been studied by scanning electron microscopy (SEM)and Raman spectroscopy.The results showed that two different shapes of corrosion products,that is,ring and chain,were formed in the initial stage of corrosion.MnS clusters were found in the nuclei of corrosion products at the active local corrosion sites.The ring-shaped products were composed of lepidocrocite (γ-FeOOH) and maghemite(γ-Fe2 O3) transformed from lepidocrocite.The chain-type products were goethite (α-FeOOH).A formation mechanism of the corrosion products is proposed.

  18. Corrosion Mechanism of Corrosion-Resistant Steel Developed for Bottom Plate of Cargo Oil Tanks

    Institute of Scientific and Technical Information of China (English)

    Feilong SUN; Xiaogang LI; Fan ZHANG; Xuequn CHENG; Cheng ZHOU; Nianchun WU; Yuqun YIN

    2013-01-01

    A new type of corrosion-resistant steel consisting of ferrite and bainite phases was developed for cargo oil tanks of crude oil tankers.The corrosion rate of this new steel was 0.22 mm/a,which was equivalent to ca.1/5 of the criterion (≤ 1 mm/a) for corrosion-resistant steels.The composition and element distribution of the corrosion products were investigated by micro-Raman spectrometry and energy dispersive spectrometer.The results demonstrated that the corrosion product was composed of α-FeOOH,Fe3O4 and a continuous Cu enrichment layer.This kind of corrosion product was protective to the steel matrix and accounted for the enhancement of the corrosion resistance of the new developed steel.

  19. Field corrosion characterization of soil corrosion of X70 pipeline steel in a red clay soil

    Institute of Scientific and Technical Information of China (English)

    Shengrong Wang; Cuiwei Dun; Xiaogang Li; Zhiyong Liunn; Min Zhu; Dawei Zhang

    2015-01-01

    The corrosion behavior of X70 pipeline steel buried in red soil environment has been studied. The surface morphology and elemental distribution were determined by scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The corrosion kinetics was evaluated by weight loss measurement. The results show that in red soil, the corrosion rate of X70 steel decreases with time, and follows the exponential decay law. General corrosion with non-uniform and localized pitting occurred on the steel surface.α-FeOOH was the dominate products during corrosion in whole buried periods, and the corrosion products exhibited well protective properties. The potentiodynamic polarization tests revealed that icorr decreased with time, indicating the improvement of corrosion resistance. The results of Electrochemical impendence spectroscopy (EIS) are consistent with potentiodynamic polarization tests.

  20. Corrosivity of paper mill effluent and corrosion performance of stainless steel.

    Science.gov (United States)

    Ram, Chhotu; Sharma, Chhaya; Singh, A K

    2015-01-01

    Present study relates to the corrosivity of paper mill effluent and corrosion performance of stainless steel (SS) as a construction material for the effluent treatment plant (ETP). Accordingly, immersion test and electrochemical polarization tests were performed on SS 304 L, 316 L and duplex 2205 in paper mill effluent and synthetic effluent. This paper presents electrochemical polarization measurements, performed for the first time to the best of the authors' information, to see the influence of chlorophenols on the corrosivity of effluents. The corrosivity of the effluent was observed to increase with the decrease in pH and increase in Cl- content while the addition of SO4- tends to inhibit corrosion. Mill effluent was found to be more corrosive as compared to synthetic effluent and has been attributed to the presence of various chlorophenols. Corrosion performance of SS was observed to govern by the presence of Cr, Mo and N contents.

  1. Review of studies on corrosion of magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    ZENG Rong-chang; ZHANG jin; HUANG Wei-jiu; W. DIETZEL; K. U. KAINER; C. BLAWERT; KE Wei

    2006-01-01

    This review provided some recent progress of the research on corrosion mechanisms of magnesium and its alloys and a basis for follow-on research. Galvanic corrosion,pitting corrosion,intergranular corrosion (IGC),filiform corrosion,crevice corrosion,stress corrosion cracking (SCC),and corrosion fatigue (CF) were discussed. The influence of metallurgical factors such as alloying elements,microstructure and secondary phases,processing factors such as heat treatment and weld,and environmental factors including temperature,relative humidity,solution pH values and concentration on corrosion were discussed. In particular,a mechanism of pitting corrosion caused by AlMn particles was proposed. The corrosion properties of AZ91D weld material were investigated.

  2. Corrosion problems with aqueous coolants, final report

    Energy Technology Data Exchange (ETDEWEB)

    Diegle, R B; Beavers, J A; Clifford, J E

    1980-04-11

    The results of a one year program to characterize corrosion of solar collector alloys in aqueous heat-transfer media are summarized. The program involved a literature review and a laboratory investigation of corrosion in uninhibited solutions. It consisted of three separate tasks, as follows: review of the state-of-the-art of solar collector corrosion processes; study of corrosion in multimetallic systems; and determination of interaction between different waters and chemical antifreeze additives. Task 1 involved a comprehensive review of published literature concerning corrosion under solar collector operating conditions. The reivew also incorporated data from related technologies, specifically, from research performed on automotive cooling systems, cooling towers, and heat exchangers. Task 2 consisted of determining the corrosion behavior of candidate alloys of construction for solar collectors in different types of aqueous coolants containing various concentrations of corrosive ionic species. Task 3 involved measuring the degradation rates of glycol-based heat-transfer media, and also evaluating the effects of degradation on the corrosion behavior of metallic collector materials.

  3. Erosion–corrosion and corrosion properties of DLC coated low temperature Erosion–corrosion and corrosion properties of DLC coated low temperature

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Christiansen, Thomas; Hilbert, Lisbeth Rischel

    2009-01-01

    of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature...

  4. Corrosion Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Weldingh, Jakob; Olsen, Flemmming Ove

    1997-01-01

    In this paper the corrosion properties of laser welded AISI 316L stainless steel are examined. A number of different welds has been performed to test the influence of the weld parameters of the resulting corrosion properties. It has been chosen to use the potential independent critical pitting...

  5. Factors affecting the corrosivity of pulping liquors

    Science.gov (United States)

    Hazlewood, Patrick Evan

    Increased equipment failures and the resultant increase in unplanned downtime as the result of process optimization programs continue to plague pulp mills. The failures are a result of a lack of understanding of corrosion in the different pulping liquors, specifically the parameters responsible for its adjustment such as the role and identification of inorganic and organic species. The current work investigates the role of inorganic species, namely sodium hydroxide and sodium sulfide, on liquor corrosivity at a range of process conditions beyond those currently experienced in literature. The role of sulfur species, in the activation of corrosion and the ability of hydroxide to passivate carbon steel A516-Gr70, is evaluated with gravimetric and electrochemical methods. The impact of wood chip weathering on process corrosion was also evaluated. Results were used to identify black liquor components, depending on the wood species, which play a significant role in the activation and inhibition of corrosion for carbon steel A516-Gr70 process equipment. Further, the effect of black liquor oxidation on liquor corrosivity was evaluated. Corrosion and stress corrosion cracking performance of selected materials provided information on classes of materials that may be reliably used in aggressive pulping environments.

  6. Biobased polymers for corrosion protection of metals

    Science.gov (United States)

    Anticorrosive biobased polymers were developed in our lab. We isolated an exopolysaccharide produced by a microbe that, when coated on metal substrates, exhibited unique corrosion inhibition. Corrosion is a worldwide problem and impacts the economy, jeopardizes human health and safety, and impedes t...

  7. Inhibitor treatment program for chlorine dioxide corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Edmondson, J.G.; Holder, E.P.

    1991-11-12

    This patent describes a method of inhibiting corrosion by chlorine dioxide in oil field waterflood systems by adding a sufficient amount of a corrosion inhibiting composition. It comprises a phosphonate, a copolymer consisting of repeating units of acrylic acid/allyl hydroxy propyl sulfonate ether, and a permangante.

  8. Aircraft Integral Fuel Tank Corrosion Study

    Science.gov (United States)

    2007-11-02

    biology of Amorphoteca resinae . Materials und Organismen, 6, (3), p. 161, (1971). 8. D. Cabral. Corrosion by microorganisms of jet aircraft integral fuel...the mycelium of the fungus Hormoconis resinae in the MIC of Al alloys. Proc. XI Int. Corrosion Congress, Houston, USA, 5B, p. 3773, (1993). 14. M

  9. Computer-Aided Corrosion Program Management

    Science.gov (United States)

    MacDowell, Louis

    2010-01-01

    This viewgraph presentation reviews Computer-Aided Corrosion Program Management at John F. Kennedy Space Center. The contents include: 1) Corrosion at the Kennedy Space Center (KSC); 2) Requirements and Objectives; 3) Program Description, Background and History; 4) Approach and Implementation; 5) Challenges; 6) Lessons Learned; 7) Successes and Benefits; and 8) Summary and Conclusions.

  10. The dual role of microbes in corrosion

    NARCIS (Netherlands)

    Kip, D.J.; Van Veen, J.A.

    2015-01-01

    Corrosion is the result of a series of chemical, physical and (micro) biological processes leading to the deterioration of materials such as steel and stone. It is a world-wide problem with great societal and economic consequences. Current corrosion control strategies based on chemically produced pr

  11. Dissolution properties of cerium dibutylphosphate corrosion inhibitors

    NARCIS (Netherlands)

    Soestbergen, M. van; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The corrosion inhibitor cerium dibutylphosphate, Ce(dbp)3, prevents corrosion by cerium and dbp deposition at the alkaline cathode and acidic anode respectively. The pH dependent Ce(dbp)3 solubility seems to play an essential role in the inhibition degree. We found that Ce(dbp) 3 scarcely dissolves

  12. Corrosion effects on soda lime glass

    NARCIS (Netherlands)

    Veer, F.A.; Rodichev, Y.M.

    2010-01-01

    Although soda lime glass is the most common used transparent material in architecture, little is known about the corrosion effects on long term strength and the interaction between corrosion and defects. Extensive testing on soda lime bars under different environmental conditions and different degre

  13. Corrosion Behaviour of New Zr Alloys

    DEFF Research Database (Denmark)

    Tolksdorf, E.

    1974-01-01

    Corrosion studies have indicated that the most promising replacements for Zicaloy-2 are ZrCrFe, ZrVFe and probably ZrNbTa, provided they are in their optimized condition. These alloys are conventionally manufactured alloys. An internally oxidized ZrMgO alloy is even superior, from the corrosion...

  14. Electrochemical corrosion measurements on noble electrodeposits

    DEFF Research Database (Denmark)

    Christoffersen, Lasse; Maahn, Ernst Emanuel

    1998-01-01

    Novel electrodeposits are compared with hard chrome and electroless Ni-P with respect to production, corrosion resistance and hardness.......Novel electrodeposits are compared with hard chrome and electroless Ni-P with respect to production, corrosion resistance and hardness....

  15. Geothermal drill pipe corrosion test plan

    Energy Technology Data Exchange (ETDEWEB)

    Caskey, B.C.; Copass, K.S.

    1980-12-01

    Plans are presented for conducting a field test of drill pipe corrosion, comparing air and nitrogen as drilling fluids. This test will provide data for evaluating the potential of reducing geothermal well drilling costs by extending drill pipe life and reducing corrosion control costs. The 10-day test will take place during fall 1980 at the Baca Location in Sandoval County, New Mexico.

  16. Remote computer monitors corrosion protection system

    Energy Technology Data Exchange (ETDEWEB)

    Kendrick, A.

    Effective corrosion protection with electrochemical methods requires some method of routine monitoring that provides reliable data that is free of human error. A test installation of a remote computer control monitoring system for electrochemical corrosion protection is described. The unit can handle up to six channel inputs. Each channel comprises 3 analog signals and 1 digital. The operation of the system is discussed.

  17. The Corrosion and Corrosion Fatigue Behavior of Nickel Based Alloy Weld Overlay and Coextruded Claddings

    Science.gov (United States)

    Stockdale, Andrew

    The use of low NOx boilers in coal fired power plants has resulted in sulfidizing corrosive conditions within the boilers and a reduction in the service lifetime of the waterwall tubes. As a solution to this problem, Ni-based weld overlays are used to provide the necessary corrosion resistance however; they are susceptible to corrosion fatigue. There are several metallurgical factors which give rise to corrosion fatigue that are associated with the localized melting and solidification of the weld overlay process. Coextruded coatings offer the potential for improved corrosion fatigue resistance since coextrusion is a solid state coating process. The corrosion and corrosion fatigue behavior of alloy 622 weld overlays and coextruded claddings was investigated using a Gleeble thermo-mechanical simulator retrofitted with a retort. The experiments were conducted at a constant temperature of 600°C using a simulated combustion gas of N2-10%CO-5%CO2-0.12%H 2S. An alternating stress profile was used with a minimum tensile stress of 0 MPa and a maximum tensile stress of 300 MPa (ten minute fatigue cycles). The results have demonstrated that the Gleeble can be used to successfully simulate the known corrosion fatigue cracking mechanism of Ni-based weld overlays in service. Multilayer corrosion scales developed on each of the claddings that consisted of inner and outer corrosion layers. The scales formed by the outward diffusion of cations and the inward diffusion of sulfur and oxygen anions. The corrosion fatigue behavior was influenced by the surface finish and the crack interactions. The initiation of a large number of corrosion fatigue cracks was not necessarily detrimental to the corrosion fatigue resistance. Finally, the as-received coextruded cladding exhibited the best corrosion fatigue resistance.

  18. General Corrosion and Localized Corrosion of the Drip Shield

    Energy Technology Data Exchange (ETDEWEB)

    F. Hua; K. Mon

    2003-06-24

    The recommended waste package (WP) design is described in BSC (2001a). The design includes a double-wall WP underneath a protective drip shield (DS) (BSC 2003a). The purpose of the process-level models developed in this report is to model dry oxidation (DOX), general corrosion (GC) and localized corrosion (LC) of the DS plate material, which is made of Ti Grade 7. The DS design also includes structural supports fabricated from Ti Grade 24. Degradation of Ti Grade 24 is not considered in this report. The DS provides protection for the waste package outer barrier (WPOB) both as a barrier to seepage water contact and a physical barrier to potential rockfall. This Model Report (MR) serves as a feed to the Integrated Waste Package Degradation Model (IWPD) analyses, and was developed in accordance with the Technical Work Plan (TWP) (BSC 2002a). The models contained in this report serve as a basis to determine whether or not the performance requirements for the DS can be met.

  19. Corrosion Control for Reinforced Concrete,

    Science.gov (United States)

    1983-01-01

    ALUMINATE) (WATER) (CALCIUM HYDROXIDE) (TETRACALCIUM ALUMINATE HYDHtATE) 3C@O-AJ2 03 10.430 * C&SO 4 2H 2 0 = va0A 20 3 C&WS- 2H2O f TRICALCIUM...a rarge of -0.71 to -0.81 volts, referenced to a copper-copper sulfate (Cu/ CuSO4 ) electrode. Both Tomashov 27 and Hausman 28 agree that to prevent...referenced to a Cu/ CuSO4 electrode. Also, corrosion of a corroding rebar can be completely arrested if V the polarization potential of the rebar is

  20. Steam generator corrosion 2007; Dampferzeugerkorrosion 2007

    Energy Technology Data Exchange (ETDEWEB)

    Born, M. (ed.)

    2007-07-01

    Between 8th and 9th November, 2007, SAXONIA Standortentwicklungs- und -verwertungsgesellschaft GmbH (Freiberg, Federal Republic of Germany) performed the 3rd Freiberger discussion conference ''Fireside boiler corrosion''. The topics of the lectures are: (a) Steam generator corrosion - an infinite history (Franz W. Alvert); (b) CFD computations for thermal waste treatment plants - a contribution for the damage recognition and remedy (Klaus Goerner, Thomas Klasen); (c) Experiences with the use of corrosion probes (Siegfried R. Horn, Ferdinand Haider, Barbara Waldmann, Ragnar Warnecke); (d) Use of additives for the limitation of the high temperature chlorine corrosion as an option apart from other measures to the corrosion protection (Wolfgang Spiegel); (e) Current research results and aims of research with respect to chlorine corrosion (Ragnar Warnecke); (f) Systematics of the corrosion phenomena - notes for the enterprise and corrosion protection (Thomas Herzog, Wolfgang Spiegel, Werner Schmidl); (g) Corrosion protection by cladding in steam generators of waste incinerators (Joerg Metschke); (h) Corrosion protection and wear protection by means of thermal spraying in steam generators (Dietmar Bendix); (i) Review of thick film nickelized components as an effective protection against high-temperature corrosion (Johann-Wilhelm Ansey); (j) Fireproof materials for waste incinerators - characteristics and profile of requirement (Johannes Imle); (k) Service life-relevant aspects of fireproof linings in the thermal recycling of waste (Till Osthoevener and Wolfgang Kollenberg); (l) Alternatives to the fireproof material in the heating space (Heino Sinn); (m) Cladding: Inconal 625 contra 686 - Fundamentals / applications in boiler construction and plant construction (Wolfgang Hoffmeister); (n) Thin films as efficient corrosion barriers - thermal spray coating in waste incinerators and biomass firing (Ruediger W. Schuelein, Steffen Hoehne, Friedrich

  1. Alloy formation and chemisorption at Zn/Pt(111) bimetallic surfaces using alkali ISS, XPD, and TPD.

    Science.gov (United States)

    Ho, Chih-Sung; Martono, Eddie; Banerjee, Santanu; Roszell, John; Vohs, John; Koel, Bruce E

    2013-11-21

    Alloy formation and chemisorption at bimetallic surfaces formed by vapor-depositing Zn on a Pt(111) single crystal were investigated primarily by using X-ray photoelectron diffraction (XPD), X-ray photoelectron spectroscopy (XPS), low-energy alkali ion scattering spectroscopy (ALISS), low electron energy diffraction (LEED), and temperature programmed desorption (TPD). A wide range of conditions were investigated to explore whether deposition and annealing of Zn films could produce well-defined, ordered alloy surfaces, similar to those encountered for Sn/Pt(111) surface alloys. These attempts were unsuccessful, although weak, diffuse (2 × 2) spots were observed under special conditions. The particular PtZn bimetallic alloy created by annealing one monolayer of Zn on Pt(111) at 600 K, which has a Zn composition in the surface layer of about 5 at. %, was investigated in detail by using XPD and ALISS. Only a diffuse (1 × 1) pattern was observed from this surface by LEED, suggesting that no long-range, ordered alloy structure was formed. Zn atoms were substitutionally incorporated into the Pt(111) crystal to form a near-surface alloy in which Zn atoms were found to reside primarily in the topmost and second layers. The alloyed Zn atoms in the topmost layer are coplanar with the Pt atoms in the surface layer, without any "buckling" of Zn, that is, displacement in the vertical direction. This result is expected because of the similar size of Pt and Zn, based on previous studies of bimetallic Pt alloys. Zn atoms desorb upon heating rather than diffusing deep into the bulk of the Pt crystal. Temperature programmed desorption (TPD) measurements show that both CO and NO have lower desorption energies on the PtZn alloy surface compared to that on the clean Pt(111) surface.

  2. Remediation of polybrominated diphenyl ethers in soil using Ni/Fe bimetallic nanoparticles: Influencing factors, kinetics and mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yingying [School of Chemistry and Environment, South China Normal University, Guangzhou 51006 (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 51006 (China); Fang, Zhanqiang, E-mail: zhqfang@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 51006 (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 51006 (China); Cheng, Wen [School of Chemistry and Environment, South China Normal University, Guangzhou 51006 (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 51006 (China); Tsang, Pokeung Eric [Department of Science and Environmental Studies, The Hong Kong Institute of Education, Hong Kong 00852 (China); Zhao, Dongye [Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States)

    2014-07-01

    Polybrominated diphenyl ethers (PBDEs) are commonly used as additive flame retardants in all kinds of electronic products. PBDEs are now ubiquitous in the environment, with soil as a major sink, especially in e-waste recycling sites. This study investigated the degradation of decabromodiphenyl ether (BDE209) in a spiked soil using Ni/Fe bimetallic nanoparticles. The results indicated that Ni/Fe bimetallic nanoparticles are able to degrade BDE209 in soil at ambient temperature and the removal efficiency can reach 72% when an initial pH of 5.6 and at a Ni/Fe dosage of 0.03 g/g. A declining trend in degradation was noticed with decreasing Ni loading and increasing of initial BDE209 concentration. The degradation products of BDE209 were analyzed by GC-MS, which showed that the degradation of BDE209 was a process of stepwise debromination from nBr to (n − 1)Br. And a possible debromination pathway was proposed. At last, the degradation process was analyzed as two-step mechanism, mass transfer and reaction. This current study shows the potential ability of Ni/Fe nanoparticles to be used for removal of PBDEs in contaminated soil. - Highlights: • Ni/Fe bimetallic nanoparticles could effectively degradate BDE209 in soil. • The effects of various factors on remediation of BDE209 in soil using Ni/Fe were considered. • The degradation of BDE209 was a process of stepwise debromination from nBr to (n − 1)Br. • A possible debromination pathway and mechanism about removal of BDE209 in soil were proposed.

  3. Material property evaluations of bimetallic welds, stainless steel saw fusion lines, and materials affected by dynamic strain aging

    Energy Technology Data Exchange (ETDEWEB)

    Rudland, D.; Scott, P.; Marschall, C.; Wilkowski, G. [Battelle Memorial Institute, Columbus, OH (United States)

    1997-04-01

    Pipe fracture analyses can often reasonably predict the behavior of flawed piping. However, there are material applications with uncertainties in fracture behavior. This paper summarizes work on three such cases. First, the fracture behavior of bimetallic welds are discussed. The purpose of the study was to determine if current fracture analyses can predict the response of pipe with flaws in bimetallic welds. The weld joined sections of A516 Grade 70 carbon steel to F316 stainless steel. The crack was along the carbon steel base metal to Inconel 182 weld metal fusion line. Material properties from tensile and C(T) specimens were used to predict large pipe response. The major conclusion from the work is that fracture behavior of the weld could be evaluated with reasonable accuracy using properties of the carbon steel pipe and conventional J-estimation analyses. However, results may not be generally true for all bimetallic welds. Second, the toughness of austenitic steel submerged-arc weld (SAW) fusion lines is discussed. During large-scale pipe tests with flaws in the center of the SAW, the crack tended to grow into the fusion line. The fracture toughness of the base metal, the SAW, and the fusion line were determined and compared. The major conclusion reached is that although the fusion line had a higher initiation toughness than the weld metal, the fusion-line J-R curve reached a steady-state value while the SAW J-R curve increased. Last, carbon steel fracture experiments containing circumferential flaws with periods of unstable crack jumps during steady ductile tearing are discussed. These instabilities are believed to be due to dynamic strain aging (DSA). The paper discusses DSA, a screening criteria developed to predict DSA, and the ability of the current J-based methodologies to assess the effect of these crack instabilities. The effect of loading rate on the strength and toughness of several different carbon steel pipes at LWR temperatures is also discussed.

  4. Facile growth of Ag@Pt bimetallic nanorods on electrochemically reduced graphene oxide for an enhanced electrooxidation of hydrazine

    Indian Academy of Sciences (India)

    Jeena S E; Selvaraju T

    2016-03-01

    An efficient transducer was constructed by the direct growth of bimetallic Ag@Pt nanorods (NRDs) on L−tryptophan functionalized electrochemically reduced graphene oxide (L−ERGO) modified electrode using galvanic displacement method for the electrooxidation of hydrazine.Initially, one dimensionalbimetallic Ag@Cu core−shell NRDs were grown on L−ERGO modified electrode by simple seed mediated growth method. Then, the Cu shells at bimetallic NRDs were exchanged by Pt through galvanic displacement method. Accordingly, the synergetic effect produced by the combination of Ag and Pt as NRDs at L−ERGO surface enabled an enhancement in the electrocatalytic efficiency for hydrazine oxidation. L−ERGO supported bimetallic Ag@Pt NRDs were characterised by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and cyclic voltammetric techniques. Finally, the modified electrode was successfully used for the electrooxidation of hydrazine in PB (pH 7.4)with a detection limit of 6*10−7M(SdivN=3). Importantly, the presence of Pt on Ag surface plays a vital role in the electrooxidation of [N2H4] at−0.2 V with an onset potential at−0.5 V where its overpotential has decreased. On the other hand, L−ERGO nanosheets tend to facilitate an effective immobilization of low density Ag seeds (Agseeds) on its surface. Chronoamperometric studies were used to study the linear correlation of [N2H4] between 1 mM and 10 mM. The modified electrode shows a high sensitivity and selectivity for a trace amount of N2H4 in the presence of different interfering cations and anions

  5. TECHNOLOGY FOR OBTAINING BIMETALLIC SHAPING PARTS OF DIE TOOLING USING METHOD OF HIGH-SPEED HOT EXTRUSION

    Directory of Open Access Journals (Sweden)

    I. V. Kachanov

    2014-01-01

    Full Text Available Processes of high-speed shaping changes and especially high-speed hot extrusion create efficient conditions for treatment of weakly plastic and poorly deformable materials which are widely used in tool making facilities. Due to the fact that high-speed stamping provides accurate billets with increased mechanical properties, it can be used as a technological process for manufacturing shaping parts of die tooling parts operating which are subjected to increased loads and wear.The purpose of the paper is to carry out experimental investigations on the possibility to obtain a bimetallic tool where structural steel is considered as a basis of the tool and a working cavity is made of high-alloyed tool steel with its saving up to 90 %. A scheme of loading and geometry of conjugated surfaces of the composite billet have been developed in the paper. Technology for obtaining bimetallic shaping parts of die tooling with deformation at speed of vR = 40-50 m/s and composite billet temperature of T = 1150 °C has been experimentally tested with formation of a compound due to plastic flow of two billet parts on contact surface with removal of surface oxide films.Microstructures of the bimetallic compounds obtained with the help of high-speed hot extrusion method for compositions of structural and high-alloy steels have been investigated and their high quality has been proved during the investigations. Dependences of micro-hardness distribution have been established outbound two- steel contact plane in the zone of connection that are characterized by a minimum micro-hardness value in the connection joint. Availability of more plastic zone in the contact plane contributes to reduction of residual stresses due to their relaxation in this zone and higher joint strength.

  6. Role of the metal in the bonding and properties of bimetallic complexes involving manganese, iron, and cobalt.

    Science.gov (United States)

    Tereniak, Stephen J; Carlson, Rebecca K; Clouston, Laura J; Young, Victor G; Bill, Eckhard; Maurice, Rémi; Chen, Yu-Sheng; Kim, Hyun Jung; Gagliardi, Laura; Lu, Connie C

    2014-02-05

    A multidentate ligand platform is introduced that enables the isolation of both homo- and heterobimetallic complexes of divalent first-row transition metal ions such as Mn(II), Fe(II), and Co(II). By means of a two-step metalation strategy, five bimetallic coordination complexes were synthesized with the general formula M1M2Cl(py3tren), where py3tren is the triply deprotonated form of N,N,N-tris(2-(2-pyridylamino)ethyl)amine. The metal-metal pairings include dicobalt (1), cobalt-iron (2), cobalt-manganese (3), diiron (4), and iron-manganese (5). The bimetallic complexes have been investigated by X-ray diffraction and X-ray anomalous scattering studies, cyclic voltammetry, magnetometry, Mössbauer spectroscopy, UV-vis-NIR spectroscopy, NMR spectroscopy, combustion analyses, inductively coupled plasma optical emission spectrometry, and ab initio quantum chemical methods. Only the diiron chloride complex in this series contains a metal-metal single bond (2.29 Å). The others show weak metal-metal interactions (2.49 to 2.53 Å). The diiron complex is also distinct with a septet ground state, while the other bimetallic species have much lower spin states from S = 0 to S = 1. We propose that the diiron system has delocalized metal-metal bonding electrons, which seems to correlate with a short metal-metal bond and a higher spin state. Multiconfigurational wave function calculations revealed that, indeed, the metal-metal bonding orbitals in the diiron complex are much more delocalized than those of the dicobalt analogue.

  7. Modeling of Corrosion-induced Concrete Damage

    DEFF Research Database (Denmark)

    Thybo, Anna Emilie A.; Michel, Alexander; Stang, Henrik

    2013-01-01

    In the present paper a finite element model is introduced to simulate corrosion-induced damage in concrete. The model takes into account the penetration of corrosion products into the concrete as well as non-uniform formation of corrosion products around the reinforcement. To ac-count for the non......-uniform formation of corrosion products at the concrete/reinforcement interface, a deterministic approach is used. The model gives good estimates of both deformations in the con-crete/reinforcement interface and crack width when compared to experimental data. Further, it is shown that non-uniform deposition...... of corrosion products affects both the time-to cover cracking and the crack width at the concrete surface....

  8. Fuel corrosion processes under waste disposal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Shoesmith, D.W. [Univ. of Western Ontario, Dept. of Chemistry, London, Ontario (Canada)

    1999-09-01

    Under the oxidizing conditions likely to be encountered in the Yucca Mountain Repository, fuel dissolution is a corrosion process involving the coupling of the anodic dissolution of the fuel with the cathodic reduction of oxidants available within the repository. The oxidants potentially available to drive fuel corrosion are environmental oxygen, supplied by the transport through the permeable rock of the mountain and molecular and radical species produced by the radiolysis of available aerated water. The mechanism of these coupled anodic and cathodic reactions is reviewed in detail. While gaps in understanding remain, many kinetic features of these reactions have been studied in considerable detail, and a reasonably justified mechanism for fuel corrosion is available. The corrosion rate is determined primarily by environmental factors rather than the properties of the fuel. Thus, with the exception of increase in rate due to an increase in surface area, pre-oxidation of the fuel has little effect on the corrosion rate.

  9. Inhibition of aluminum corrosion using Opuntia extract

    Energy Technology Data Exchange (ETDEWEB)

    El-Etre, A.Y

    2003-11-01

    The inhibitive action of the mucilage extracted from the modified stems of prickly pears, toward acid corrosion of aluminum, is tested using weight loss, thermometry, hydrogen evolution and polarization techniques. It was found that the extract acts as a good corrosion inhibitor for aluminum corrosion in 2.0 M HCl solution. The inhibition action of the extract was discussed in view of Langmuir adsorption isotherm. It was found that the adsorption of the extract on aluminum surface is a spontaneous process. The inhibition efficiency (IE) increases as the extract concentration is increased. The effect of temperature on the IE was studied. It was found that the presence of extract increases the activation energy of the corrosion reaction. Moreover, the thermodynamic parameters of the adsorption process were calculated. It was found also that the Opuntia extract provides a good protection to aluminum against pitting corrosion in chloride ion containing solutions.

  10. Passive Corrosion Behavior of Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B; Payer, J H

    2006-01-10

    Alloy 22 (N06022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nanometers per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids.

  11. Corrosion of carbon-alloyed iron aluminides

    Indian Academy of Sciences (India)

    M Sen; R Balasubramaniam; A V Ramesh Kumar

    2000-10-01

    The corrosion behaviour of two carbon-alloyed intermetallics of composition Fe–28.1Al–2.1C and Fe–27.5Al–3.7C has been studied and compared with that of binary intermetallics. Potentiodynamic polarization studies indicated that the intermetallics exhibited active–passive behaviour in an acidic solution of pH = 1, whereas they exhibited stable passivity in a buffer solution of pH 8.4. Corrosion rates were also obtained by immersion testing. The variation of corrosion rate as a function of time was similar for both the intermetallics. The variation in corrosion rate as a function of time has been explained based on the observed potentiodynamic polarization behaviour. Scanning electron microscopy of corroded surfaces indicated that the carbon-alloyed intermetallics were susceptible to galvanic corrosion, due to the presence of carbides.

  12. Laser-controllable coatings for corrosion protection.

    Science.gov (United States)

    Skorb, Ekaterina V; Skirtach, Andre G; Sviridov, Dmitry V; Shchukin, Dmitry G; Möhwald, Helmuth

    2009-07-28

    We introduce a novel and versatile approach to the corrosion protection by use of "smart" laser-controllable coating. The main advantage of the proposed technique is that one could terminate the corrosion process by very intensive healing after an appearance of corrosion centers using local laser irradiation. It is also shown that by applying a polyelectrolyte shell with noble metal particles over the mesoporous titania and silica via layer-by-layer assembly it is possible to fabricate micro- and nanoscaled reservoirs, which, being incorporated into the zirconia-organosilica matrix, are responsible for the ability of laser-driven release of the loaded materials (e.g., corrosion inhibitor). Furthermore, the resultant films are highly adhesive and could be easily deposited onto different metallic substrates. Laser-mediated remote release of incorporated corrosion inhibitor (benzotriazole) from engineered mesoporous containers with silver nanoparticles in the container shell is observed in real time on single and multicontainer levels.

  13. Complete corrosion inhibition through graphene defect passivation.

    Science.gov (United States)

    Hsieh, Ya-Ping; Hofmann, Mario; Chang, Kai-Wen; Jhu, Jian Gang; Li, Yuan-Yao; Chen, Kuang Yao; Yang, Chang Chung; Chang, Wen-Sheng; Chen, Li-Chyong

    2014-01-28

    Graphene is expected to enable superior corrosion protection due to its impermeability and chemical inertness. Previous reports, however, demonstrate limited corrosion inhibition and even corrosion enhancement of graphene on metal surfaces. To enable the reliable and complete passivation, the origin of the low inhibition efficiency of graphene was investigated. Combining electrochemical and morphological characterization techniques, nanometer-sized structural defects in chemical vapor deposition grown graphene were found to be the cause for the limited passivation effect. Extremely fast mass transport on the order of meters per second both across and parallel to graphene layers results in an inhibition efficiency of only ∼50% for Cu covered with up to three graphene layers. Through selective passivation of the defects by atomic layer deposition (ALD) an enhanced corrosion protection of more than 99% was achieved, which compares favorably with commercial corrosion protection methods.

  14. Stifling of Crevice Corrosion in Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Mon, K G; Gordon, G M; Rebak, R B

    2005-06-08

    Artificially creviced Alloy 22 (N06022) specimens may be susceptible to crevice corrosion in presence of hot chloride containing solutions. The presence of oxyanions in the electrolyte, especially nitrate, may inhibit the nucleation and growth of crevice corrosion. Constant potential tests were performed using tightly creviced specimens of Alloy 22. It was found that crevice corrosion may initiate when a constant potential above the crevice repassivation potential is applied. It was found that as the crevice corrosion nucleated, the current initially increased but later decreased. The net measured current can be converted into penetration following a power law fit of the experimental data. The average power law coefficient ''n'' was found to be 0.439, suggesting that even under constant applied potential crevice corrosion penetration is diffusion controlled.

  15. STIFLING OF CREVICE CORROSION IN ALLOY 22

    Energy Technology Data Exchange (ETDEWEB)

    K.G. Mon; G.M. Gordon; R.B. Rebak

    2005-07-01

    Artificially creviced Alloy 22 (N06022) specimens may be susceptible to crevice corrosion in presence of hot chloride containing solutions. The presence of oxyanions in the electrolyte, especially nitrate, may inhibit the nucleation and growth of crevice corrosion. Constant potential tests were performed using tightly creviced specimens of Alloy 22. It was found that crevice corrosion may initiate when a constant potential above the crevice repassivation potential is applied. It was found that as the crevice corrosion nucleated, the current initially increased but later decreased. The net measured current can be converted into penetration following a power law fit of the experimental data. The average power law coefficient ''n'' was found to be 0.439, suggesting that even under constant applied potential, crevice corrosion penetration is diffusion controlled.

  16. Microencapsulation Technologies for Corrosion Protective Coating Applications

    Science.gov (United States)

    Li, Wenyan; Buhrow, Jerry; Jolley, Scott; Calle, Luz; Pearman, Benjamin; Zhang, Xuejun

    2015-01-01

    Microencapsulation technologies for functional smart Coatings for autonomous corrosion control have been a research area of strong emphasis during the last decade. This work concerns the development of pH sensitive micro-containers (microparticles and microcapsules) for autonomous corrosion control. This paper presents an overview of the state-of-the-art in the field of microencapsulation for corrosion control applications, as well as the technical details of the pH sensitive microcontainer approach, such as selection criteria for corrosion indicators and corrosion inhibitors; the development and optimization of encapsulation methods; function evaluation before and after incorporation of the microcontainers into coatings; and further optimization to improve coating compatibility and performance.

  17. Numerical Study of Corrosion Crack Opening

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Frandsen, Henrik Lund; Svensson, Staffan

    2008-01-01

    for the corrosion crack opening. Experiments and theoretical analysis by a numerical method, FEM, support that the relation between the reduction of the reinforcement bar diameter due to corrosion and the corresponding increase in crack width for a given time interval, measured on the surface of a concrete specimen...... is proportional. More recently, the constant of proportionality, the so-called crack-corrosion index, has been studied further with respect to its dependence on the diameter of the reinforcement and the concrete cover. In the present paper the above-mentioned work is presented and extended with more realistic 3D......-models of the cracked concrete beam. The crack-corrosion index is evaluated for a variation of different parameters, i.e. bar diameter, concrete cover, crack length and type of corrosion product. This paper is an extended version of a paper by Thoft-Christensen et al. (2005) presented at the IFIP WG 7.5 Conference...

  18. Catalytic activity of bimetallic catalysts highly sensitive to the atomic composition and phase structure at the nanoscale.

    Science.gov (United States)

    Shan, Shiyao; Petkov, Valeri; Prasai, Binay; Wu, Jinfang; Joseph, Pharrah; Skeete, Zakiya; Kim, Eunjoo; Mott, Derrick; Malis, Oana; Luo, Jin; Zhong, Chuan-Jian

    2015-12-07

    The ability to determine the atomic arrangement in nanoalloy catalysts and reveal the detailed structural features responsible for the catalytically active sites is essential for understanding the correlation between the atomic structure and catalytic properties, enabling the preparation of efficient nanoalloy catalysts by design. Herein we describe a study of CO oxidation over PdCu nanoalloy catalysts focusing on gaining insights into the correlation between the atomic structures and catalytic activity of nanoalloys. PdCu nanoalloys of different bimetallic compositions are synthesized as a model system and are activated by a controlled thermochemical treatment for assessing their catalytic activity. The results show that the catalytic synergy of Pd and Cu species evolves with both the bimetallic nanoalloy composition and temperature of the thermochemical treatment reaching a maximum at a Pd : Cu ratio close to 50 : 50. The nanoalloys are characterized structurally by ex situ and in situ synchrotron X-ray diffraction, including atomic pair distribution function analysis. The structural data show that, depending on the bimetallic composition and treatment temperature, PdCu nanoalloys adopt two different structure types. One features a chemically ordered, body centered cubic (B2) type alloy consisting of two interpenetrating simple cubic lattices, each occupied with Pd or Cu species alone, and the other structure type features a chemically disordered, face-centered cubic (fcc) type of alloy wherein Pd and Cu species are intermixed at random. The catalytic activity for CO oxidation is strongly influenced by the structural features. In particular, it is revealed that the prevalence of chemical disorder in nanoalloys with a Pd : Cu ratio close to 50 : 50 makes them superior catalysts for CO oxidation in comparison with the same nanoalloys of other bimetallic compositions. However, the catalytic synergy can be diminished if the Pd50Cu50 nanoalloys undergo

  19. Synthesis, characterization and antibacterial activity of copper, nickel and bimetallic Cu-Ni nanoparticles for potential use in dental materials

    Institute of Scientific and Technical Information of China (English)

    Liliana Argueta-Figueroa; Raúl A. Morales-Luckie; Rogelio J. Scougall-Vilchis; Oscar F. Olea-Mejía

    2014-01-01

    The antibacterial effect is a desirable property in dental materials. Development of simple methods for the preparation of nanosized metal particles has attracted significant attention because of their future applications due to unusual size-dependent antibacterial properties. Copper (Cu), Nickel (Ni) and bimetallic Cu-Ni nanoparticles were prepared by a simple chemical method and their antibacterial activity was tested against the widely used standard human pathogens Staphylococcus aureus (gram-negative) and Escherichia coli (gram-positive). Additionally, these nanoparticles were tested against the dental pathogen Streptococcus mutans. Our results are promising for potential use in dental materials science.

  20. Buckling of a Shallow Rectangular Bimetallic Shell Subjected to Outer Loads and Temperature and Supported at Four Opposite Points

    Directory of Open Access Journals (Sweden)

    M. Jakomin

    2009-01-01

    Full Text Available We have formulated a geometric non-linear mathematical-physical model of the snap-through of the system of a thin-walled shallow bimetallic translation shell in a homogenous temperature field according to the theory of large displacements, moderate rotations, and small strains of the shell element. The model enables the calculation of the geometric conditions, of shallow translation shells, due to the influences of temperature and mechanical loads. The results are based on the numeric solution of a non-linear system of partial differential equations with boundary conditions according to the finite difference method.

  1. Near-Monodisperse Ni-Cu Bimetallic Nanocrystals of Variable Composition: Controlled Synthesis and Catalytic Activity for H2 Generation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yawen; Huang, Wenyu; Habas, Susan E.; Kuhn, John N.; Grass, Michael E.; Yamada, Yusuke; Yang, Peidong; Somorjai, Gabor A.

    2008-07-22

    Near-monodisperse Ni{sub 1-x}Cu{sub x} (x = 0.2-0.8) bimetallic nanocrystals were synthesized by a one-pot thermolysis approach in oleylamine/1-octadecene, using metal acetylacetonates as precursors. The nanocrystals form large-area 2D superlattices, and display a catalytic synergistic effect in the hydrolysis of NaBH{sub 4} to generate H{sub 2} at x = 0.5 in a strongly basic medium. The Ni{sub 0.5}Cu{sub 0.5} nanocrystals show the lowest activation energy, and also exhibit the highest H{sub 2} generation rate at 298 K.

  2. Synthesis, characterization and antibacterial activity of copper, nickel and bimetallic Cu–Ni nanoparticles for potential use in dental materials

    Directory of Open Access Journals (Sweden)

    Liliana Argueta-Figueroa

    2014-08-01

    Full Text Available The antibacterial effect is a desirable property in dental materials. Development of simple methods for the preparation of nanosized metal particles has attracted significant attention because of their future applications due to unusual size-dependent antibacterial properties. Copper (Cu, Nickel (Ni and bimetallic Cu–Ni nanoparticles were prepared by a simple chemical method and their antibacterial activity was tested against the widely used standard human pathogens Staphylococcus aureus (gram-negative and Escherichia coli (gram-positive. Additionally, these nanoparticles were tested against the dental pathogen Streptococcus mutans. Our results are promising for potential use in dental materials science.

  3. Bimetallic nanoalloys in heterogeneous catalysis of industrially important reactions: synergistic effects and structural organization of active components

    Science.gov (United States)

    Ellert, O. G.; Tsodikov, M. V.; Nikolaev, S. A.; Novotortsev, V. M.

    2014-08-01

    The review is concerned with correlations between the synergistic effects and structural organization of the surface of bimetallic alloys that are used as active components of catalysts for selective hydrogenation of organic compounds and for CO oxidation in hydrogen-rich mixtures. Studies on the preparation of novel highly efficient catalysts using modern theoretical approaches, computer-assisted molecular design and original synthetic procedures are considered. It is shown that introduction of the second metal into the monometallic catalyst and subsequent formation of alloy particles with modified structure of the surface and near-surface layers leads to nonadditive enhancement of catalytic activity and/or selectivity. The bibliography includes 203 references.

  4. Synthesis, Spectroscopy, Thermal Analysis, Electrochemistry and Superoxide Scavenging Activity of a New Bimetallic Copper(II Complex

    Directory of Open Access Journals (Sweden)

    Babita Sarma

    2013-01-01

    Full Text Available A new bimetallic copper(II complex has been synthesized with ligand obtained by the condensation of salicylaldehyde and the amine derived from reduction of nitration product of benzil. The ligand was characterized by 1H NMR and mass spectra, and the binuclear Copper(II complex was characterized by vibrational and electronic spectra, EPR spectra, and magnetic moment measurement. Thermogravimetric analysis study and electrochemical study of the complex were also done. The complex was found to show superoxide dismutase activity.

  5. Corrosion protection with eco-friendly inhibitors

    Science.gov (United States)

    Shahid, Muhammad

    2011-12-01

    Corrosion occurs as a result of the interaction of a metal with its environment. The extent of corrosion depends on the type of metal, the existing conditions in the environment and the type of aggressive ions present in the medium. For example, CO3-2 and NO-3 produce an insoluble deposit on the surface of iron, resulting in the isolation of metal and consequent decrease of corrosion. On the other hand, halide ions are adsorbed selectively on the metal surface and prevent formation of the oxide phase on the metal surface, resulting in continuous corrosion. Iron, aluminum and their alloys are widely used, both domestically and industrially. Linear alkylbenzene and linear alkylbenzene sulfonate are commonly used as detergents. They have also been found together in waste water. It is claimed that these chemicals act as inhibitors for stainless steel and aluminum. Release of toxic gases as a result of corrosion in pipelines may lead in certain cases to air pollution and possible health hazards. Therefore, there are two ways to look at the relationship between corrosion and pollution: (i) corrosion of metals and alloys due to environmental pollution and (ii) environmental pollution as a result of corrosion protection. This paper encompasses the two scenarios and possible remedies for various cases, using 'green' inhibitors obtained either from plant extracts or from pharmaceutical compounds. In the present study, the effect of piperacillin sodium as a corrosion inhibitor for mild steel was investigated using a weight-loss method as well as a three-electrode dc electrochemical technique. It was found that the corrosion rate decreased as the concentration of the inhibitor increased up to 9×10-4 M 93% efficiency was exhibited at this concentration.

  6. Co-sputter deposited nickel-copper bimetallic nanoalloy embedded carbon films for electrocatalytic biomarker detection

    Science.gov (United States)

    Shiba, Shunsuke; Kato, Dai; Kamata, Tomoyuki; Niwa, Osamu

    2016-06-01

    We report the fabrication of a nickel (Ni)-copper (Cu) bimetallic nanoalloy (~3 nm) embedded carbon film electrode with the unbalanced magnetron (UBM) co-sputtering technique, which requires only a one-step process at room temperature. Most of each nanoalloy body was firmly embedded in a chemically stable carbon matrix with an atomically flat surface (Ra: 0.21 nm), suppressing the aggregation and/or detachment of the nanoalloy from the electrode surface. The nanoalloy size and composition can be controlled simply by individually controlling the target powers of carbon, Ni and Cu, which also makes it possible to localize the nanoalloys near the electrode surface. This electrode exhibited excellent electrocatalytic activity for d-mannitol, which should be detected with a low detection limit in urine samples for the diagnosis of severe intestinal diseases. With a Ni/Cu ratio of around 64/36, the electrocatalytic current per metal area was 3.4 times larger than that of an alloy film electrode with a similar composition (~70/30). This improved electrocatalytic activity realized higher stability (n = 60, relative standard deviation (RSD): 4.6%) than the alloy film (RSD: 32.2%) as demonstrated by continuous measurements of d-mannitol.We report the fabrication of a nickel (Ni)-copper (Cu) bimetallic nanoalloy (~3 nm) embedded carbon film electrode with the unbalanced magnetron (UBM) co-sputtering technique, which requires only a one-step process at room temperature. Most of each nanoalloy body was firmly embedded in a chemically stable carbon matrix with an atomically flat surface (Ra: 0.21 nm), suppressing the aggregation and/or detachment of the nanoalloy from the electrode surface. The nanoalloy size and composition can be controlled simply by individually controlling the target powers of carbon, Ni and Cu, which also makes it possible to localize the nanoalloys near the electrode surface. This electrode exhibited excellent electrocatalytic activity for d

  7. Migrating corrosion inhibitor blend for reinforced concrete: Part 1 -- Prevention of corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Elsener, B.; Buechler, M.; Stalder, F.; Boehni, H.

    1999-12-01

    The efficiency of a migrating corrosion inhibitor in preventing corrosion of mild steel was investigated in saturated calcium hydroxide (Ca[OH]{sub 2}) solutions and in mortar. The protective effect of the inhibitor against pitting corrosion caused by chloride attack and against uniform corrosion as a result of carbonation was determined. Results showed that high concentrations ({approx}10%) allowed the inhibition of pitting corrosion tritiation in solution containing 1 M/L sodium chloride (NaCl). However, inhibiting properties can be lost by evaporation of the volatile constituent of the inhibitor or by the precipitation of the nonvolatile fraction of the inhibitor in presence of calcium ions. Addition of the inhibitor blend to mortar yielded a retardation of the corrosion initiation in the case of chloride-induced corrosion, but o significant reduction in corrosion rate. No effect was found in carbonated samples, and no influence on the corrosion rate was detected. Additionally, the estimation of the extent of the retarding effect on corrosion initiation on real structures was difficult, as the inhibitor was found to evaporate from the mortar. This evaporation resulted in a loss of inhibiting properties. Hence, the long-term efficiency of the inhibitor could not be guaranteed.

  8. Graphene-bimetallic nanoparticle composites with enhanced electro-catalytic detection of bisphenol A

    Science.gov (United States)

    Pogacean, Florina; Biris, Alexandru R.; Socaci, Crina; Coros, Maria; Magerusan, Lidia; Rosu, Marcela-Corina; Lazar, Mihaela D.; Borodi, Gheorghe; Pruneanu, Stela

    2016-12-01

    This study brings for the first time novel knowledge about the synthesis by catalytic chemical vapor deposition with induction heating of graphene-bimetallic nanoparticle composites (Gr-AuCu and Gr-AgCu) and their morphological and structural characterization by transmission electron microscopy, Raman spectroscopy, and x-ray powder diffraction. Gold electrodes modified with the obtained materials exhibit an enhanced electro-catalytic effect towards one of the most encountered estrogenic disruptive chemicals, bisphenol A (BPA). The BPA behavior in varying pH solutions was investigated using the electrochemical quartz crystal microbalance, which allowed the accurate determination of the number of molecules involved in the oxidation process. The modified electrodes promote the oxidation of BPA at significantly lower potentials (0.66 V) compared to bare gold (0.78 V). In addition, the peak current density recorded with such electrodes greatly exceeded that obtained with bare gold (e.g. one order of magnitude larger, for a Au/Gr-AgCu electrode). The two modified electrodes have low detection limits, of 1.31 × 10-6 M and 1.91 × 10-6 M for Au/Gr-AgCu and Au/Gr-AuCu, respectively. The bare gold electrode has a higher detection limit of 5.1 × 10-6 M. The effect of interfering species (e.g. catechol and 3-nitrophenol) was also investigated. Their presence influenced not only the BPA peak potential, but also the peak current. With both modified electrodes, no peak currents were recorded below 3 × 10-5 M BPA.

  9. How to Determine the Core-Shell Nature in Bimetallic Catalyst Particles?

    Directory of Open Access Journals (Sweden)

    Emma Westsson

    2014-11-01

    Full Text Available Nanometer-sized materials have significantly different chemical and physical properties compared to bulk material. However, these properties do not only depend on the elemental composition but also on the structure, shape, size and arrangement. Hence, it is not only of great importance to develop synthesis routes that enable control over the final structure but also characterization strategies that verify the exact nature of the nanoparticles obtained. Here, we consider the verification of contemporary synthesis strategies for the preparation of bimetallic core-shell particles in particular in relation to potential particle structures, such as partial absence of core, alloying and raspberry-like surface. It is discussed what properties must be investigated in order to fully confirm a covering, pin-hole free shell and which characterization techniques can provide such information. Not uncommonly, characterization strategies of core-shell particles rely heavily on visual imaging like transmission electron microscopy. The strengths and weaknesses of various techniques based on scattering, diffraction, transmission and absorption for investigating core-shell particles are discussed and, in particular, cases where structural ambiguities still remain will be highlighted. Our main conclusion is that for particles with extremely thin or mono-layered shells—i.e., structures outside the limitation of most imaging techniques—other strategies, not involving spectroscopy or imaging, are to be employed. We will provide a specific example of Fe-Pt core-shell particles prepared in bicontinuous microemulsion and point out the difficulties that arise in the characterization process of such particles.

  10. Green synthesis and characterization of Au@Pt core-shell bimetallic nanoparticles using gallic acid

    Science.gov (United States)

    Zhang, Guojun; Zheng, Hongmei; Shen, Ming; Wang, Lei; Wang, Xiaosan

    2015-06-01

    In this study, we developed a facile and benign green synthesis approach for the successful fabrication of well-dispersed urchin-like Au@Pt core-shell nanoparticles (NPs) using gallic acid (GA) as both a reducing and protecting agent. The proposed one-step synthesis exploits the differences in the reduction potentials of AuCl4- and PtCl62-, where the AuCl4- ions are preferentially reduced to Au cores and the PtCl62- ions are then deposited continuously onto the Au core surface as a Pt shell. The as-prepared Au@Pt NPs were characterized by transmission electron microscope (TEM); high-resolution transmission electron microscope (HR-TEM); scanning electron microscope (SEM); UV-vis absorption spectra (UV-vis); X-ray diffraction (XRD); Fourier transmission infrared spectra (FT-IR). We systematically investigated the effects of some experimental parameters on the formation of the Au@Pt NPs, i.e., the reaction temperature, the molar ratios of HAuCl4/H2PtCl6, and the amount of GA. When polyvinylpyrrolidone K-30 (PVP) was used as a protecting agent, the Au@Pt core-shell NPs obtained using this green synthesis method were better dispersed and smaller in size. The as-prepared Au@Pt NPs exhibited better catalytic activity in the reaction where NaBH4 reduced p-nitrophenol to p-aminophenol. However, the results showed that the Au@Pt bimetallic NPs had a lower catalytic activity than the pure Au NPs obtained by the same method, which confirmed the formation of Au@Pt core-shell nanostructures because the active sites on the surfaces of the Au NPs were covered with a Pt shell.

  11. Improved debromination of polybrominated diphenyl ethers by bimetallic iron-silver nanoparticles coupled with microwave energy

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Si [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Yang, Shaogui, E-mail: yangdlut@126.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Sun, Cheng, E-mail: envidean@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Gu, Ji-Dong [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong (China)

    2012-07-01

    This study focused on the enhanced debromination of decabromodiphenyl ether (BDE-209) and 2,2 Prime ,4,4 Prime -tetrabromodiphenyl ether (BDE-47) by Fe-Ag nano-particles under microwave radiation (Fe-Ag/MW). Fe-Ag bimetallic nano-particles were synthesized by reductive deposition of Ag on nano-iron and characterized with a number of techniques, including BET, XRD, TEM and XPS. Approximately 97% of BDE-209 or 78% of BDE-47 were rapidly transformed to its degradation products within 8 min in the Fe-Ag/MW system. The dehalogenation efficiency of polybrominated diphenyl ethers (PBDEs) was enhanced apparently by microwave radiation. Moreover, the microwave thermal energy played a significant role in accelerating the degradation reactions. Compared with nano-iron alone, the deposition of Ag also increased the rates of degradation. GC-MS and LC-MS/MS analyses of PBDEs' degradation products reveals that the possible degradation pathway proceeds through stepwise debromination from [n]-bromo- to [n-1]-bromo-DE, with bromine being substituted by hydrogen sequentially. Di- to nona-brominated congeners were formed during BDE-209 reduction, while diphenyl ether to tri-BDEs were observed during BDE-47 degradation. These results suggest that PBDEs can be debrominated rapidly by the innovative processes that may be environmentally friendly in applications. - Highlights: Black-Right-Pointing-Pointer The Fe-Ag nanoparticles with a core-shell structure were successfully prepared. Black-Right-Pointing-Pointer A highly efficient technology for debromination of PBDEs by Fe-Ag/MW was investigated. Black-Right-Pointing-Pointer The effect of bromine's number on the stability against reduction of PBDEs was explored. Black-Right-Pointing-Pointer The role of MW energy and Ag in the reactivity of the Fe-Ag/MW system was demonstrated. Black-Right-Pointing-Pointer The possible degradation pathways of BDE-209 and BDE-47 were proposed.

  12. 49 CFR 192.475 - Internal corrosion control: General.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control: General. 192.475... Control § 192.475 Internal corrosion control: General. (a) Corrosive gas may not be transported by... taken to minimize internal corrosion. (b) Whenever any pipe is removed from a pipeline for any...

  13. 49 CFR 193.2631 - Internal corrosion control.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control. 193.2631 Section 193... GAS FACILITIES: FEDERAL SAFETY STANDARDS Maintenance § 193.2631 Internal corrosion control. Each component that is subject to internal corrosive attack must be protected from internal corrosion by—...

  14. Atmospheric Corrosivity at Australian and Overseas Airbases and Airports

    Science.gov (United States)

    2014-07-01

    protective coating systems and corrosion inhibitor treatments deteriorate and become less effective. The CLIMAT environmental corrosion test has...UNCLASSIFIED UNCLASSIFIED Atmospheric Corrosivity at Australian and Overseas Airbases and Airports J C Bitcon Maritime...Division Defence Science and Technology Organisation DSTO-TN-1320 ABSTRACT Atmospheric corrosivity at 25 airbases and airports in Australia

  15. 46 CFR 154.412 - Cargo tank corrosion allowance.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo tank corrosion allowance. 154.412 Section 154.412... Containment Systems § 154.412 Cargo tank corrosion allowance. A cargo tank must be designed with a corrosion...) carries a cargo that corrodes the tank material. Note: Corrosion allowance for independent tank type C...

  16. 49 CFR 193.2627 - Atmospheric corrosion control.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Atmospheric corrosion control. 193.2627 Section... LIQUEFIED NATURAL GAS FACILITIES: FEDERAL SAFETY STANDARDS Maintenance § 193.2627 Atmospheric corrosion... atmospheric corrosion by— (a) Material that has been designed and selected to resist the corrosive...

  17. Corrosion damage evolution and residual strength of corroded aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Youhong Zhang; Guozhi Lv; Hui Wang; Bomei Si; Yueliang Cheng

    2008-01-01

    The LY12CZ aluminum alloy specimens were eurroded under the conditions of different test temperatures and exposure durations. After corrosion exposure, fatigue tests were performed. Scanning electron microscopy and optical microscope analyses on corrosion damage were carried out. The definition of surface corrosion damage ratio was provided to describe the extent of surface corrosion damage. On the basis of the measured data sets of the corrosion damage ratio, the probabilistic model of corrosion damage evolution was built. The corrosion damage decreased the fatigue life by a factor of about 1.25 to 2.38 and the prediction method of residual strength of the corroded structure was presented.

  18. A Calculation Model for Corrosion Cracking in RC Structures

    Institute of Scientific and Technical Information of China (English)

    Xu Gang; Wei Jun; Zhang Keqiang; Zhou Xiwu

    2007-01-01

    A novel calculation model is proposed aiming at the problem of concrete cover cracking induced by reinforcement corrosion. In this article, the relationship between the corrosion depth of the bar and the thickness of the rust layer is established. By deducing the radial displacement expression of concrete, the formula for corrosion depth and corrosion pressure before cracking is proposed. The crack depth of cover in accordance with the maximum corrosion pressure is deduced; furthermore, the corrosion depth and corrosion pressure at the cracking time are obtained. Finally, the theoretical model is validated by several experiments, and the calculated values agree well with the experiment results.

  19. Corrosion inhibitors for intermediate cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Falk, I.; Suhr, L.

    1985-04-01

    The selected inhibitors were tested for heat and radiation stability and corrosion protection on the bench scale. Based on the results from these tests two of the products were selected, Bycoguard 81 and Bycoguard MP4S for continuing corrosion tests in an autoclave loop at 90 degrees C and 120 degrees C. Oxygen saturated deionized water with an addition of 1 ppm chloride was recirculated in the loop. Samples of copper and carbon steel were exposed to the water in the autoclave for periods up to 10 weeks. The purpose of this project was to find a substitute for hydrazine and chromates. Besides good corrosion protection qualities the toxic and environmental effect of the inhibitors should be minimal. The investigation has shown that the copper inhibitor BTA (benzotriazole) loses its corrosion protection qualities at a water temperature of 120 degrees C. The protection effects at 90 degrees C were satisfactory for both of the materials. The corrosion rates measured were 0.01 mm/y or less for the copper and carbon steel samples. The environment in the autoclave during the testing was more corrosive than is to be found in intermediate cooling systems. Due to the low corrosion rates measured the two inhibitors are to be recommended as alternatives to hydrazine and chromates.

  20. Mesoporous silica nanoparticles for active corrosion protection.

    Science.gov (United States)

    Borisova, Dimitriya; Möhwald, Helmuth; Shchukin, Dmitry G

    2011-03-22

    This work presents the synthesis of monodisperse, mesoporous silica nanoparticles and their application as nanocontainers loaded with corrosion inhibitor (1H-benzotriazole (BTA)) and embedded in hybrid SiOx/ZrOx sol-gel coating for the corrosion protection of aluminum alloy. The developed porous system of mechanically stable silica nanoparticles exhibits high surface area (∼1000 m2·g(-1)), narrow pore size distribution (d∼3 nm), and large pore volume (∼1 mL·g(-1)). As a result, a sufficiently high uptake and storage of the corrosion inhibitor in the mesoporous nanocontainers was achieved. The successful embedding and homogeneous distribution of the BTA-loaded monodisperse silica nanocontainers in the passive anticorrosive SiOx/ZrOx film improve the wet corrosion resistance of the aluminum alloy AA2024 in 0.1 M sodium chloride solution. The enhanced corrosion protection of this newly developed active system in comparison to the passive sol-gel coating was observed during a simulated corrosion process by the scanning vibrating electrode technique (SVET). These results, as well as the controlled pH-dependent release of BTA from the mesoporous silica nanocontainers without additional polyelectrolyte shell, suggest an inhibitor release triggered by the corrosion process leading to a self-healing effect.

  1. Marine atmospheric corrosion of carbon steels

    Energy Technology Data Exchange (ETDEWEB)

    Morcillo, M.; Alcantara, J.; Diaz, I.; Chico, B.; Simancas, J.; Fuente, D. de la

    2015-07-01

    Basic research on marine atmospheric corrosion of carbon steels is a relatively young scientific field and there continue to be great gaps in this area of knowledge. The presence of akaganeite in the corrosion products that form on steel when it is exposed to marine atmospheres leads to a notable increase in the corrosion rate. This work addresses the following issues: (a) environmental conditions necessary for akaganeite formation; (b) characterisation of akaganeite in the corrosion products formed; (c) corrosion mechanisms of carbon steel in marine atmospheres; (d) exfoliation of rust layers formed in highly aggressive marine atmospheres; (e) long-term corrosion rate prediction; and (f) behaviour of weathering steels. Field research has been carried out at Cabo Vilano wind farm (Camarinas, Galicia) in a wide range of atmospheric salinities and laboratory work involving the use of conventional atmospheric corrosion techniques and near-surface and bulk sensitive analytical techniques: scanning electron microscopy (SEM)/energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Mossbauer spectroscopy and SEM/μRaman spectroscopy. (Author)

  2. Recent Natural Corrosion Inhibitors for Mild Steel: An Overview

    Directory of Open Access Journals (Sweden)

    Marko Chigondo

    2016-01-01

    Full Text Available Traditionally, reduction of corrosion has been managed by various methods including cathodic protection, process control, reduction of the metal impurity content, and application of surface treatment techniques, as well as incorporation of suitable alloys. However, the use of corrosion inhibitors has proven to be the easiest and cheapest method for corrosion protection and prevention in acidic media. These inhibitors slow down the corrosion rate and thus prevent monetary losses due to metallic corrosion on industrial vessels, equipment, or surfaces. Inorganic and organic inhibitors are toxic and costly and thus recent focus has been turned to develop environmentally benign methods for corrosion retardation. Many researchers have recently focused on corrosion prevention methods using green inhibitors for mild steel in acidic solutions to mimic industrial processes. This paper provides an overview of types of corrosion, corrosion process, and mainly recent work done on the application of natural plant extracts as corrosion inhibitors for mild steel.

  3. A STUDY OF CORROSION AND STRESS CORROSION CRACKING OF CARBON STEEL NUCLEAR WASTE STORAGE TANKS

    Energy Technology Data Exchange (ETDEWEB)

    BOOMER, K.D.

    2007-08-21

    The Hanford reservation Tank Farms in Washington State has 177 underground storage tanks that contain approximately 50 million gallons of liquid legacy radioactive waste from cold war plutonium production. These tanks will continue to store waste until it is treated and disposed. These nuclear wastes were converted to highly alkaline pH wastes to protect the carbon steel storage tanks from corrosion. However, the carbon steel is still susceptible to localized corrosion and stress corrosion cracking. The waste chemistry varies from tank to tank, and contains various combinations of hydroxide, nitrate, nitrite, chloride, carbonate, aluminate and other species. The effect of each of these species and any synergistic effects on localized corrosion and stress corrosion cracking of carbon steel have been investigated with electrochemical polarization, slow strain rate, and crack growth rate testing. The effect of solution chemistry, pH, temperature and applied potential are all considered and their role in the corrosion behavior will be discussed.

  4. Slurry Chemical Corrosion and Galvanic Corrosion during Copper Chemical Mechanical Polishing

    Science.gov (United States)

    Kondo, Seiichi; Sakuma, Noriyuki; Homma, Yoshio; Ohashi, Naofumi

    2000-11-01

    Copper (Cu) corrosion during chemical mechanical polishing (CMP) was controlled in order to improve the Cu damascene interconnect process. Slurry chemical corrosion was found to be enhanced when the slurry was diluted by deionized (DI) water during rinsing just after CMP@. Since the corrosion inhibitor, benzotriazole (BTA), reduces the Cu removal rate, adding it to the rinse solution prevents chemical corrosion more effectively than adding it to the slurry. On the other hand, galvanic corrosion occurs at the interface between Cu and the barrier metal, and it can be prevented by selecting appropriate barrier metals. Because the difference between the electrochemical potentials of Cu and the barrier metal is small in the slurry, refractory metals such as Ta, TaN, and TiN were found to be appropriate barrier metals. On the other hand, W, WN, and Ti have large potential differences, so galvanic corrosion was clearly observed when Cu/W damascene interconnects were fabricated.

  5. Real time corrosion monitoring in atmosphere using automated battery driven corrosion loggers

    DEFF Research Database (Denmark)

    Prosek, T.; Kouril, M.; Hilbert, Lisbeth Rischel

    2008-01-01

    A logger enabling continuous measurement of corrosion rate of selected metals in indoor and outdoor atmospheres has been developed. Principle of the measurement method is based on the increasing electrical resistance of a measuring element made of the material concerned as its cross-sectional area...... diminishes due to corrosion. Zinc, iron, copper and nickel sensors at several thicknesses are available. Sensitivity of the corrosion measurement varies from 1 to 10 nm depending on the type and thickness of the sensor. Changes in the air corrosivity can be thus detected within hours or even tens of minutes....... The logger lifetime in medium corrosive environments is designed to be 2 years with full autonomy. Data on the sensor corrosion rate are available any time through GPRS connection or by a non-contact inductive reading without the need of retracting the logger from the exposure site....

  6. Facile and Rapid Synthesis of Ultrafine PtPd Bimetallic Nanoparticles and Their High Performance toward Methanol Electrooxidation

    Directory of Open Access Journals (Sweden)

    Tiantian Xia

    2014-01-01

    Full Text Available Uniform and sub-10 nm size bimetallic PtPd nanoparticles (NPs have been synthesized via a simple and facile method without using any surfactants at an ambient temperature. As a green and clean reductive agent, ascorbic acid (AA was employed for the coreduction of K2PtCl4 and K2PdCl4 in aqueous solution. The morphology, composition, and structure of PtPd NPs had been characterized by transmission electron microscopy (TEM, field emission high resolution transmission electron microscopy (FE-HRTEM, energy dispersive spectroscopy (EDS, X-ray diffraction (XRD, and X-ray photoelectron spectroscope (XPS. Comparing with both the monometallic Pt and Pd, the as-prepared alloy nanoparticles show superior electrocatalytic activity and better tolerance against poisoning by intermediates generated during methanol electrooxidation, which makes them a promising electrocatalysts for direct methanol fuel cells (DMFCs. Meanwhile, the green and simple approach could be easily extended to the manufacture of bimetallic or trimetallic alloy nanomaterials.

  7. Rational design of Mg-Al mixed oxide-supported bimetallic catalysts for dry reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Tsyganok, Andrey I. [Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, D' Iorio Hall, 10 Marie Curie Street, Ottawa, Ont. (Canada); Inaba, Mieko [Natural Gas Technology Development Team, Teikoku Oil Co., 9-23-30 Kitakarasuyama, Setagaya-ku, Tokyo 157-0061 (Japan); Tsunoda, Tatsuo; Uchida, Kunio; Suzuki, Kunio; Hayakawa, Takashi [Institute for Materials and Chemical Process, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565 (Japan); Takehira, Katsuomi [Department of Applied Chemistry, Faculty of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan)

    2005-09-18

    A novel synthetic strategy for preparing bimetallic Ru-M (M=Cr, Fe, Co, Ni and Cu) catalysts, supported on Mg-Al mixed oxide, has been introduced. It was based on a 'memory effect', i.e. on the ability of Mg-Al mixed oxide to reconstruct a layered structure upon rehydration with an aqueous solution. By repeated calcinations-rehydration cycles, layered double hydroxide (LDH) precursors of catalysts containing two different metals were synthesized. Bimetallic catalysts were then generated (1) in situ from LDH under methane reforming reaction conditions and (2) from mixed metal oxides obtained by preliminary LDH calcination. Among all the LDH-derived catalysts, a Ru{sup 0.1%}-Ni{sup 5.0%}/MgAlO{sub x} sample revealed the highest activity and selectivity to syngas, a suitable durability and a low coking capacity. A promoting effect of ruthenium on catalytic function of supported nickel was demonstrated. Preliminary LDH calcination was shown to markedly affect the catalytic activity of the derived catalysts and especially their coking properties.

  8. EXAFS Peaks and TPR Characterizing Bimetallic Interactions: Effects of Impregnation Methods on the Structure of Pt-Ru/C Catalysts

    Directory of Open Access Journals (Sweden)

    Nan-Yu Chen

    2014-01-01

    Full Text Available To investigate bimetallic interactions, Pt-Ru/C catalysts were prepared by coimpregnation (Pt-Ruco/C and successive impregnation (Ru-Ptse/C, while Pt/C, Ru/C, and reduced Pt-Rublack were used as reference. Those samples were characterized by XAS and TPR. When Pt(absorber-Ru(backscatter phase-and-amplitude correction is applied to Fourier transformed (FT EXAFS of Pt-Rublack at Pt edge, the characteristic peak of Pt-Ru interactions appears at 2.70 Å´, whereas, when Pt-Pt correction is applied, the peak appears at about 2.5 Å´. Detailed EXAFS analysis for Pt-Ruco/C and Pt-Ruse/C confirms the nature of the characteristic peak and further indicates that the interactions can semiquantitatively be determined by the relative intensity between Pt-Ru and Pt-Pt characteristic peaks. This simple method in determining bimetallic interaction can be extended to characterize Pt-Pd/γ-Al2O3. However, for Pt-Re/γ-Al2O3, Pt-Re interactions cannot be determined by the method because of the overlap of Pt-Pt and Pt-Re characteristic peaks due to similar phase functions.

  9. Reaction pathways of furfural, furfuryl alcohol and 2-methylfuran on Cu(111) and NiCu bimetallic surfaces

    Science.gov (United States)

    Xiong, Ke; Wan, Weiming; Chen, Jingguang G.

    2016-10-01

    Hydrodeoxygenation (HDO) is an important reaction for converting biomass-derived furfural to value-added 2-methylfuran, which is a promising fuel additive. In this work, the HDO of furfural to produce 2-methylfuran occurred on the NiCu bimetallic surfaces prepared on either Ni(111) or Cu(111). The reaction pathways of furfural were investigated on Cu(111) and Ni/Cu(111) surfaces using density functional theory (DFT) calculations, temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) experiments. These studies provided mechanistic insights into the effects of bimetallic formation on enhancing the HDO activity. Specifically, furfural weakly adsorbed on Cu(111), while it strongly adsorbed on Ni/Cu(111) through an η2(C,O) configuration, which led to the HDO of furfural on Ni/Cu(111). The ability to dissociate H2 on Ni/Cu(111) is also an important factor for enhancing the HDO activity over Cu(111).

  10. In situ biosynthesis of Ag, Au and bimetallic nanoparticles using Piper pedicellatum C.DC: green chemistry approach.

    Science.gov (United States)

    Tamuly, Chandan; Hazarika, Moushumi; Borah, Sarat Ch; Das, Manash R; Boruah, Manas P

    2013-02-01

    The synthesis of Ag, Au and Ag-Au bimetallic nanoparticles using Piper pedicellatum C.DC leaf extract is demonstrated here. The rapid formation of stable Ag and Au nanoparticles has been found using P. pedicellatum C.DC leaf extract in aqueous medium at normal atmospheric condition. Competitive reduction of Ag(+) and Au(3+) ions present simultaneously in solution during exposure to P. pedicellatum C.DC leaf extract leads to the synthesis of bimetallic Ag-Au nanoparticles in solution. Transmission electron microscopy (TEM) analysis revealed that the Ag nanoparticles predominantly form spherical in shape with the size range of 2.0±0.5-30.0±1.2 nm. In case of Au nanoparticles, the particles are spherical in shape along with few triangular, hexagonal and pentagonal shaped nanoparticles also observed. X-ray diffraction (XRD) studies revealed that the nanoparticles were face centered cubic (fcc) in shape. Fourier transform infrared spectroscopy (FTIR) showed nanoparticles were capped with plant compounds. The chemical constituents, viz. catechin, gallic acid, courmaric acid and protocatechuic acid of the leaf extract were identified which may act as a reducing, stabilizing and capping agent. The expected reaction mechanism in the formation of Ag and Au nanoparticles is also reported.

  11. Production of mono- and bimetallic nanoparticles of noble metals by pyrolysis of organic extracts on silicon dioxide

    Science.gov (United States)

    Serga, V.; Kulikova, L.; Cvetkov, A.; Krumina, A.; Kodols, M.; Chornaja, S.; Dubencovs, K.; Sproge, E.

    2013-12-01

    In the present work the influence of the tri-n-octylammonium (Oct3NH+) salt anion (PtCl62-, PdCl42-, AuCl4-) nature on the phase composition and mean size of crystallites of the extract pyrolysis products on the SiO2 nanopowder has been studied. The XRD phase analysis of the composites (metal loading 2.4 wt.%) made under the same conditions, at the pyrolysis of Pt- and Au-containing extracts has shown the formation of nanoparticles of Pt (dPt = 15 nm) and Au (dAu = 33 nm), respectively. The end-product of the pyrolysis of the Pd-containing extract has an admixture phase of PdO along with the main metal phase (dPd = 21 nm). At the preparation of bimetallic particles (Pt-Pd, Pt-Au, Pd-Au) on the SiO2 nanopowder it has been found that the nanoparticles of the PtPd alloy, Pt and Au or Pd and Au nanoparticles are the products of the thermal decomposition of two-component mixtures of extracts. The investigation of catalytic properties of the produced composites in the reaction of glycerol oxidation by molecular oxygen in alkaline aqueous solutions has shown that all bimetallic composites exhibit catalytic activity in contrast to monometallic ones.

  12. A facile reflux procedure to increase active surface sites form highly active and durable supported palladium@platinum bimetallic nanodendrites

    Science.gov (United States)

    Wang, Qin; Li, Yingjun; Liu, Baocang; Xu, Guangran; Zhang, Geng; Zhao, Qi; Zhang, Jun

    2015-11-01

    A series of well-dispersed bimetallic Pd@Pt nanodendrites uniformly supported on XC-72 carbon black are fabricated by using different capping agents. These capping agents are essential for the branched morphology control. However, the surfactant adsorbed on the nanodendrites surface blocks the access of reactant molecules to the active surface sites, and the catalytic activities of these bimetallic nanodendrites are significantly restricted. Herein, a facile reflux procedure to effectively remove the capping agent molecules without significantly affecting their sizes is reported for activating supported nanocatalysts. More significantly, the structure and morphology of the nanodendrites can also be retained, enhancing the numbers of active surface sites, catalytic activity and stability toward methanol and ethanol electro-oxidation reactions. The as-obtained hot water reflux-treated Pd@Pt/C catalyst manifests superior catalytic activity and stability both in terms of surface and mass specific activities, as compared to the untreated catalysts and the commercial Pt/C and Pd/C catalysts. We anticipate that this effective and facile removal method has more general applicability to highly active nanocatalysts prepared with various surfactants, and should lead to improvements in environmental protection and energy production.

  13. A facile strategy to synthesize bimetallic Au/Ag nanocomposite film by layer-by-layer assembly technique

    Science.gov (United States)

    Zhang, Li; Wang, Cong; Zhang, Yi

    2012-05-01

    A facile strategy has been developed for the preparation of bimetallic gold-silver (Au-Ag) nanocomposite films by alternating absorption of poly-(ethyleneimine)-silver ions and Au onto substrates and subsequent reduction of the silver ions. The composition, micro-structure and properties of the {PEI-Ag/Au}n nanocomposite films were characterized by ultraviolet visible spectroscopy (UV-vis), transmisson electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), surface enhanced Raman scattering (SERS) and cyclic voltammetry (CV). The UV-vis characteristic absorbances of {PEI-Ag/Au}n nanocomposite thin film increase almost linear with the number of bilayers, which indicates a process of uniform assembling. Appearance of a double plasmon bands in the visible region and the lack of apparent core-shell structures in the TEM images confirm the formation of bimetallic Au-Ag nanoparticles. The result of XPS also demonstrates the existence of Ag and Au nanoparticles in the nanocomposite films. TEM and FESEM images show that these Ag and Au nanoparticles in the films possess sphere structure with the size of 20-25 nm. The resulting {PEI-Ag/Au}n films inherit the properties from both the metal Ag and Au, which exhibits a unique performance in SERS and electrocatalytic activities to the oxidation of dopamine. As a result, the {PEI-Ag/Au}n films are more attractive compared to {PEI-Ag/PSS}n and {PEI/Au}n films.

  14. Waste of cleaning emulsion sewage as inhibitors of steel corrosion

    Science.gov (United States)

    Fazullin, D. D.; Mavrin, G. V.; Shaikhiev, I. G.

    2016-06-01

    The article describes the corrosion test of steel of the brand 20 in the stratal water. To increase corrosion resistance as a corrosion inhibitor the concentrate waste emulsion of the mark "Incam- 1" was provided. The article presents studies of the corrosion rate with different dosages of corrosion inhibitor in the stratal water. Based on these research results are revealed that the degree of protection of steel is 27% at a dosage of 3.8 g / dm3.

  15. Assessment of Commercial Corrosion Inhibiting Admixtures for Reinforced Concrete

    OpenAIRE

    Brown, Michael Carey

    1999-01-01

    Corrosion of reinforcing steel in concrete exposed to chloride-laden environments is a well-known and documented phenomenon. The need for cost effective systems for protection against corrosion has become increasingly clear since the first observations of severe corrosion damage to interstate bridges in the 1960's. As one potential solution to the mounting problem of corrosion deterioration of structures, corrosion-inhibiting admixtures have been researched and introduced into service. ...

  16. Solid phase metallurgy strategy to sub-5 nm Au-Pd and Ni-Pd bimetallic nanoparticles with controlled redox properties.

    Science.gov (United States)

    Tang, Yu; Xu, Shaodan; Dai, Yihu; Yan, Xiaoqing; Li, Renhong; Xiao, Liping; Fan, Jie

    2014-01-07

    A solid phase metallurgy strategy is applied to synthesize Au-Pd and Ni-Pd bimetallic nanoparticles (BMNPs) with a tight sub-5 nm particle size distribution. The near-surface elemental composition and redox properties of Au-Pd BMNPs can be well tailored, which leads to an optimized catalytic performance in n-hexane combustion.

  17. Green synthesis of silver, gold and silver/gold bimetallic nanoparticles using the Gloriosa superba leaf extract and their antibacterial and antibiofilm activities.

    Science.gov (United States)

    Gopinath, Kasi; Kumaraguru, Shanmugasundaram; Bhakyaraj, Kasi; Mohan, Subramanian; Venkatesh, Kunga Sukumaran; Esakkirajan, Masanam; Kaleeswarran, Periyannan; Alharbi, Naiyf S; Kadaikunnan, Shine; Govindarajan, Marimuthu; Benelli, Giovanni; Arumugam, Ayyakannu

    2016-12-01

    The green fabrication of metal nanoparticles using botanical extracts is gaining increasing research attention in nanotechnology, since it does not require high energy inputs or the production of highly toxic chemical byproducts. Here, silver (Ag), gold (Au) and their bimetallic (Ag/Au) nanoparticles (NPs) were green synthesized using the Gloriosa superba aqueous leaf extract. Metal NPs were studied by spectroscopic (UV-visible spectroscopy, fluorescence spectroscopy, FT-IR spectroscopy, XRD and EDX) and microscopic (AFM and TEM) analysis. AFM and TEM showed that Ag and Au NPs had triangular and spherical morphologies, with an average size of 20 nm. Bimetallic Ag/Au NPs showed spherical shapes with an average size of 10 nm. Ag and Ag/Au bimetallic NPs showed high antibacterial and antibiofilm activities towards Gram-positive and Gram-negative bacteria. Overall, the proposed synthesis route of Ag, Au and Ag/Au bimetallic NPs can be exploited by the pharmaceutical industry to develop drugs effective in the fight against microbic infections.

  18. Standard practice for evaluation of disbonding of bimetallic stainless alloy/steel plate for use in high-pressure, high-temperature refinery hydrogen service

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2001-01-01

    1.1 This practice covers a procedure for the evaluation of disbonding of bimetallic stainless alloy/steel plate for use in refinery high-pressure/high-temperature (HP/HT) gaseous hydrogen service. It includes procedures to (1) produce suitable laboratory test specimens, (2) obtain hydrogen charging conditions in the laboratory that are similar to those found in refinery HP/HT hydrogen gas service for evaluation of bimetallic specimens exposed to these environments, and (3) perform analysis of the test data. The purpose of this practice is to allow for comparison of data among test laboratories on the resistance of bimetallic stainless alloy/steels to hydrogen-induced disbonding (HID). 1.2 This practice applies primarily to bimetallic products fabricated by weld overlay of stainless alloy onto a steel substrate. Most of the information developed using this practice has been obtained for such materials. The procedures described herein, may also be appropriate for evaluation of hot roll bonded, explosive bonded...

  19. Numerical modelling of corrosion - Theoretical backgrounds -

    Energy Technology Data Exchange (ETDEWEB)

    Warkus, J.; Raupach, M. [ibac, RWTH Aachen (Germany); Gulikers, J. [Ministry of Transport, Rijkswaterstaat, Bouwdienst, Utrecht (Netherlands)

    2006-08-15

    During recent years research projects with different approaches have been carried out to develop models which are suitable to assess the metal removal rate in case of reinforcement corrosion. Some of them are based on empirical methods and correlate the corrosion rate to parameters like concrete resistivity, temperature and relative humidity. Another type of model is based on a quantification of the ongoing electrochemical processes. In this paper the theoretical backgrounds and mathematical descriptions of reinforcement corrosion with regard to a numerical modelling are presented and discussed. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  20. A Localised Corrosion Cell for Industrial Applications

    DEFF Research Database (Denmark)

    Andersen, A.; Hilbert, Lisbeth Rischel; Jansen, P.

    2003-01-01

    The LOCORR-CELL™ developed by FORCE TECHNOLOGY is an electrochemical cell for industrial applications estimating localised corrosion. The cell is constructed in a carbon steel casing for direct mounting into the system. It is based on an oxygen concentration element reflecting the interaction...... between the environment formed under a deposit or in a crevice. The essential feature of the method is that it reflects the influence of oxygen content, conductivity and temperature as well as the influence of corrosion inhibitors, MIC and other effects that have an effect on localised corrosion under...