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Sample records for alliages base nickel

  1. Caractérisation par MET de fissures de corrosion sous contrainte d'alliages à base de nickel : influence de la teneur en chrome et de la chimie du milieu

    OpenAIRE

    Delabrouille, Frédéric

    2004-01-01

    La corrosion sous contrainte (CSC) est un mode de dégradation qui affecte de nombreux alliages au sein des réacteurs à eau sous pression, notamment les alliages base nickel tubes des générateurs de vapeur (GV). La fissuration qu'elle engendre intervient tant du côté primaire que secondaire, en particulier dans des zones où la composition du milieu est mal définie. La sensibilité à la CSC des alliages base nickel dépend de leur teneur en chrome, ce qui a conduit au remplacement de l'alliage 60...

  2. Modélisation de la fissuration à chaud lors du soudage de l'alliage base nickel IN600

    OpenAIRE

    Bouffier, Lionel

    2013-01-01

    La fissuration à chaud de solidification qui est l'un des problèmes majeurs rencontrés dans le cadre du soudage pourrait être préjudiciable à la tenue en service de structures mécano-soudées. Ce phénomène correspond à la formation de fissures en fin de solidification sous l'effet des déformations induites par les contraintes thermiques et le retrait de solidification. Ces travaux de thèse portent sur la modélisation de la fissuration à chaud dans un alliage base nickel en soudage TIG. L'objec...

  3. Etude expérimentale du soudage par laser YAG de l'alliage base nickel Hastelloy X

    OpenAIRE

    Graneix, Jérémie; Béguin, Jean-Denis; Pardeilhan, François; Masri, Talal; Alexis, Joël

    2013-01-01

    Le procédé de soudage laser YAG est envisagé pour remplacer le procédé de soudage TIG manuel pour la réalisation de pièces de turboréacteur en alliage nickel-chrome-molybdène Hastelloy X. Cette étude expérimentale a permis de définir un domaine de soudabilité de cet alliage répondant aux critères spécifiques du secteur aéronautique.

  4. Corrosion généralisée des alliages à base nickel en milieu aqueux à haute température : Apport à la compréhension des mécanismes

    OpenAIRE

    Marchetti-Sillans, Loïc

    2007-01-01

    Les alliages à base nickel, et plus précisément les alliages 600 et 690, sont, en France, les matériaux constitutifs des tubes de générateurs de vapeur (GV) des réacteurs à eau pressurisée (REP). La corrosion généralisée résultant de l'interaction entre ces alliages et le milieu primaire des REP conduit, d'une part, à la formation d'une fine couche passive (environ 10 nm) de produits de corrosion, mais également à la dissolution de cations dans le circuit primaire, ces derniers constituant la...

  5. Etude expérimentale du soudage par laser YAG de l'alliage base nickel Hastelloy X Experimental study of YAG laser welding of nickel base alloy Hastelloy X

    OpenAIRE

    Graneix Jérémie; Beguin Jean-Denis; Pardeilhan François; Masri Talal; Alexis Joël

    2013-01-01

    Le procédé de soudage laser YAG est envisagé pour remplacer le procédé de soudage TIG manuel pour la réalisation de pièces de turboréacteur en alliage nickel-chrome-molybdène Hastelloy X. Cette étude expérimentale a permis de définir un domaine de soudabilité de cet alliage répondant aux critères spécifiques du secteur aéronautique. The YAG laser welding process is contemplated to replace the manual TIG welding process for the production of parts of turbojet in Hastelloy X. This experimental...

  6. Etude expérimentale du soudage par laser YAG de l'alliage base nickel Hastelloy X Experimental study of YAG laser welding of nickel base alloy Hastelloy X

    Directory of Open Access Journals (Sweden)

    Graneix Jérémie

    2013-11-01

    Full Text Available Le procédé de soudage laser YAG est envisagé pour remplacer le procédé de soudage TIG manuel pour la réalisation de pièces de turboréacteur en alliage nickel-chrome-molybdène Hastelloy X. Cette étude expérimentale a permis de définir un domaine de soudabilité de cet alliage répondant aux critères spécifiques du secteur aéronautique. The YAG laser welding process is contemplated to replace the manual TIG welding process for the production of parts of turbojet in Hastelloy X. This experimental study has identified the field of weldability of this alloy to meet the specific requirements of the aerospace industry.

  7. Effet Hall et Magnetisme des Alliages Amorphes Nickel-Zirconium Fabriques Par Pulverisation

    Science.gov (United States)

    Morel, Robert

    Cette these se situe dans le cadre d'une etude des proprietes electroniques et structurales des alliages metalliques amorphes, en cours depuis quelques annees a l'Universite de Montreal. Ce programme nous a entre autres amene a caracteriser la magnetoresistivite et l'effet Hall d'alliages FeZr, CoZr et NiZr, ce qui a permis de mettre en evidence deux caracteristiques de l'effet Hall: Dans les alliages amorphes ferromagnetiques, la resistivite elevee engendre un effet Hall extraordinaire beaucoup plus important que celui enregistre dans les metaux cristallins. La polarisation des spins entrai ne une asymetrie de la diffusion qui, tant dans les phases cristalline et amorphe, est tenue responsable de cette contribution. L'autre particularite du comportement de Hall de ces systemes est le renversement de signe du coefficient de Hall ordinaire, qui passe du negatif au positif dans les echantillons plus riches en zirconium. Dans les metaux cristallins, un modele d'electrons libres predit un signe negatif a moins que la conduction ne soit dominee par les trous. Or, dans un milieu desordonne les memes concepts sont difficilement applicables et de nouvelles theories ont du etre elaborees pour expliquer ce phenomene. Jusqu'a maintenant, l'etude des alliages amorphes nickel-zirconium s'est faite surtout a partir d'echantillons fabriques par trempe sur roue. Malheureusement cette technique ne permet pas la fabrication d'alliages contenant plus de 70% de nickel, a l'exception du seul compose Ni _{90}Zr_{10 }. Pour pallier a cette lacune et etendre nos connaissance a l'ensemble de la gamme de compositions, nous avons fabrique par pulverisation cathodique des echantillons NiZr amorphes--et quelques alliages cristallins tres riches en nickel--couvrant une bonne partie de la gamme interdite par la technique de trempe sur roue. Dans un premier temps, par comparaison avec les resultats connus nous avons mis en evidence les similitudes et les differences entre les alliages obtenus par

  8. Déformation à l'échelle cristallographique d'alliages à base de nickel mono- et polycristallins par choc laser en mode confiné

    Science.gov (United States)

    Forget, P.; Jeandin, M.

    1995-08-01

    The so-called “laser peening” treatment based on laser shock processing has been developed to improve mechanical properties due to work-hardening and formation of residual stresses. When applied to aeronautical Ni-based superalloys, an increase of fatigue resistance is expected. This article deals with deformation resulting from laser shock. The study is centered on the observation of superficial micro-roughness in the impacted zone. Micro-roughness is discussed as resulting from crystallographic changes due to shock process. Various slip phenomena were in particular determined. More generally, superficial heterogeneities in the different parts of the shocked area are discussed in the light of results on release wave propagation and formation of residual stresses. Two Ni-based superalloys, i.e. AM1 single crystal and polycrystalline Inconel718, were used. Le traitement de “grenaillage photonique” par choc laser vise à écrouir un matériau et à y introduire des contraintes résiduelles de compression en vue d'améliorer ses propriétés mécaniques. Dans le cas de superalliages aéronautiques à base de nickel, on attend une augmentation de la tenue en fatigue. On traite ici de la déformation induite par le choc grâce à une étude microstructurale fondée sur l'observation des microreliefs de surface dans la zone traitée. Ceux-ci sont interprétés comme le résultat de l'évolution cristallographique du matériau soumis au choc. Les phénomènes de glissement, sont, en particulier, précisément identifiés. Plus généralement, les hétérogénéités de surface dans les différentes parties de l'impact sont expliquées à la lumière de résultats sur la propagation des ondes de détente de surface et sur la création de contraintes résiduelles. Deux superalliages à base de nickel, l'AM1 monocristallin et l'Inconel 718 polycristallin, ont été étudiés.

  9. Generalized corrosion of nickel base alloys in high temperature aqueous media: a contribution to the comprehension of the mechanisms; Corrosion generalisee des alliages a base nickel en milieu aqueux a haute temperature: apport a la comprehension des mecanismes

    Energy Technology Data Exchange (ETDEWEB)

    Marchetti-Sillans, L

    2007-11-15

    In France, nickel base alloys, such as alloy 600 and alloy 690, are the materials constituting steam generators (SG) tubes of pressurized water reactors (PWR). The generalized corrosion resulting from the interaction between these alloys and the PWR primary media leads, on the one hand, to the formation of a thin protective oxide scale ({approx} 10 nm), and on the other hand, to the release of cations in the primary circuit, which entails an increase of the global radioactivity of this circuit. The goal of this work is to supply some new comprehension elements about nickel base alloys corrosion phenomena in PWR primary media, taking up with underlining the effects of metallurgical and physico-chemical parameters on the nature and the growth mechanisms of the protective oxide scale. In this context, the passive film formed during the exposition of alloys 600, 690 and Ni-30Cr, in conditions simulating the PWR primary media, has been analyzed by a set of characterization techniques (SEM, TEM, PEC and MPEC, XPS). The coupling of these methods leads to a fine description, in terms of nature and structure, of the multilayered oxide forming during the exposition of nickel base alloys in primary media. Thus, the protective part of the oxide scale is composed of a continuous layer of iron and nickel mixed chromite, and Cr{sub 2}O{sub 3} nodules dispersed at the alloy / mixed chromite interface. The study of protective scale growth mechanisms by tracers and markers experiments reveals that the formation of the mixed chromite is the consequence of an anionic mechanism, resulting from short circuits like grain boundaries diffusion. Besides, the impact of alloy surface defects has also been studied, underlining a double effect of this parameter, which influences the short circuits diffusion density in oxide and the formation rate of Cr{sub 2}O{sub 3} nodules. The sum of these results leads to suggest a description of the nickel base alloys corrosion mechanisms in PWR primary

  10. Mechanisms of oxide layer formation and destruction on a chromia former nickel base alloy in HTR environment; Mecanismes de formation et de destruction de la couche d'oxyde sur un alliage chrominoformeur en milieu HTR

    Energy Technology Data Exchange (ETDEWEB)

    Rouillard, F

    2007-10-15

    Haynes 230 alloy which contains 22 wt.% chromium could be a promising candidate material for structures and heat exchangers (maximum operating temperature: 850-950 C) in Very High Temperature Reactors (VHTR). The feasibility demonstration involves to valid its corrosion resistance in the reactor specific environment namely impure helium. The alloys surface reactivity was investigated at temperatures between 850 and 1000 C. We especially focused on the influence of different parameters such as concentrations of impurities in the gas phase (carbon monoxide and methane, water vapour/hydrogen ratio), alloy composition (activities of Cr and C, alloying element contents) and temperature. Two main behaviours have been revealed: the formation of a Cr/Mn rich oxide layer at 900 C and its following reduction at higher temperatures. At 900 C, the water vapour is the main oxidizing gas. However in the initial times, the carbon monoxide reacts at the metal/oxide interface which involves a gaseous transport through the scale; CO mainly oxidizes the minor alloying elements aluminium and silicon. Above a critical temperature TA, the carbon in solution in the alloy reduces chromia. To ascribe the scale destruction, a model is proposed based on thermodynamic interfacial data for the alloy, oxide layer morphology and carbon monoxide partial pressure in helium; the model is then validated regarding experimental results and observations. (author)

  11. TEM characterisation of stress corrosion cracks in nickel based alloys: effect of chromium content and chemistry of environment; Caracterisation par MET de fissures de corrosion sous contrainte d'alliages a base de nickel: influence de la teneur en chrome et de la chimie du milieu

    Energy Technology Data Exchange (ETDEWEB)

    Delabrouille, F

    2004-11-15

    Stress corrosion cracking (SCC) is a damaging mode of alloys used in pressurized water reactors, particularly of nickel based alloys constituting the vapour generator tubes. Cracks appear on both primary and secondary sides of the tubes, and more frequently in locations where the environment is not well defined. SCC sensitivity of nickel based alloys depends of their chromium content, which lead to the replacement of alloy 600 (15 % Cr) by alloy 690 (30 % Cr) but this phenomenon is not yet very well understood. The goal of this thesis is two fold: i) observe the effect of chromium content on corrosion and ii) characterize the effect of environment on the damaging process of GV tubes. For this purpose, one industrial tube and several synthetic alloys - with controlled chromium content - have been studied. Various characterisation techniques were used to study the corrosion products on the surface and within the SCC cracks: SIMS; TEM - FEG: thin foil preparation, HAADF, EELS, EDX. The effect of chromium content and surface preparation on the generalised corrosion was evidenced for synthetic alloys. Moreover, we observed the penetration of oxygen along triple junctions of grain boundaries few micrometers under the free surface. SCC tests show the positive effect of chromium for contents varying from 5 to 30 % wt. Plastic deformation induces a modification of the structure, and thus of the protective character, of the internal chromium rich oxide layer. SCC cracks which developed in different chemical environments were characterised by TEM. The oxides which are formed within the cracks are different from what is observed on the free surface, which reveals a modification of medium and electrochemical conditions in the crack. Finally we were able to evidence some structural characteristics of the corrosion products (in the cracks and on the surface) which turn to be a signature of the chemical environment. (author)

  12. Caractérisation des effets de l'implantation ionique dans les alliages super-élastiques nickel titane par diffraction des rayons X

    Science.gov (United States)

    Pelletier, H.; Muller, D.; Grob, J. J.; Mille, P.; Cornet, A.

    2002-07-01

    the specific properties (shape memory effect and super-elasticity) of NiTi alloys have provided the enabling technology for many groundbreaking applications in the medical and dentistry industries. These applications include everything from the surgical tools to permanent implants. Super-elastic NiTi alloys take advantage of a stress induced martensitic transformation to achieve incredible amounts of flexibility. This last property represents the most interesting aspect of such alloys for restoration procedures. However, recent instrumentation tests have shown brittle rupture of endodontic instruments inside the tooth during preparation of dental root channels.To improve the mechanical properties of NiTi endodontic instruments, argon, nitrogen and boron implantations at different energies and at fixed dose (1.10^{17} at.cm^{-2}) have been used. In this paper, we have investigated the effects on NiTi microstructure, especially the crystalline to amorphous transition induced by ion bombardment, using Grazing Incidence X-ray Diffraction (GIXRD). Nano-indentation tests have also been performed to determine hardness H and elastic modulus E of implanted surfaces as a function of ion species and energy. Le but de cette d'étude est de caractériser les effets de l'implantation ionique sur la microstructure d'un alliage Nickel Titane à l'aide de la diffraction des rayons X en incidence rasante. Nous avons réalisé différents types d'implantation en faisant varier l'espèce implantée (bore, azote, argon) ainsi que l'énergie d'implantation, pour des doses d'implantation de l'ordre de 1.10^{17} at.cm^{-2}. Les résultats des mesures de diffraction sous différents angles d'incidence (0{,}5^circ leq α_ileq 6^circ) ont été corrélés avec les différents profils d'implantation simulés. Des tests de nanoindentation ainsi que des mesures de RBS ont été également réalisés. Après implantation, on observe la formation d'une couche amorphe, conduisant à une

  13. Crystallographic deformation of mono- and polycristalline ni-based superalloys due to laser shock processing in the confined mode; Deformation a l`echelle cristallographique d`alliages a base de nickel mono- et polycristallins par choc laser en mode confine

    Energy Technology Data Exchange (ETDEWEB)

    Forget, P. [Ecole Nationale Superieure des Mines, 75 - Paris (France). Centre des Materiaux; Jeandin, M. [Ecole Nationale Superieure des Mines, 75 - Paris (France). Centre des Materiaux

    1995-08-01

    The so-called ``laser peening`` treatment based on laser shock processing has been developed to improve mechanical properties due to work-hardening and formation of residual stresses. When applied to aeronautical Ni-based superalloys, an increase of fatigue resistance is expected. This article deals with deformation resulting from laser shock. The study is centered on the observation of superficial micro-roughness in the impacted zone. Micro-roughness is discussed as resulting from crystallographic changes due to shock process. Various slip phenomena were in particular determined. More generally, superficial heterogeneities in the different parts of the shocked area are discussed in the light of results on release wave propagation and formation of residual stresses. Two Ni-based superalloys, i.e. AM1 single crystal and polycrystalline Inconel 718, were used. (orig.).

  14. Layered nickel based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Ronning, Filip [Los Alamos National Laboratory; Bauer, Eric D [Los Alamos National Laboratory; Park, Tuson [Los Alamos National Laboratory; Kurita, Nobuyuki [Los Alamos National Laboratory; Klimczuk, T [Los Alamos National Laboratory; Movshovich, R [Los Alamos National Laboratory; Thompson, J D [Los Alamos National Laboratory; Sefat, A S [ORNL; Mandrus, D [ORNL

    2009-01-01

    We review the properties of Ni-based superconductors which contain Ni{sub 2}X{sub 2} (X=As, P, Bi, Si, Ge, B) planes, a common structural element to the recently discovered FeAs superconductors. We also compare the properties ofthe Ni-and Fe-based systems from a perspective ofelectronic structure as well as structure-property relations.

  15. Nickel-base alloys combat corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, D.C. [VDM Technologies Corp., Houston, TX (United States); Herda, W. [Krupp-VDM GmbH, Werdohl (Germany)

    1995-06-01

    The modern chemical process industry must increase production efficiency to remain competitive. Manufacturers typically meet this challenge by utilizing higher temperatures and pressures, and more-corrosive catalysts. At the same time, the industry has to solve the technical and commercial problems resulting from rigid environmental regulations. To overcome these obstacles, new alloys having higher levels of corrosion resistance have been developed. These materials are based on increased understanding of the physical metallurgy of nickel-base alloys, especially the role of alloying elements. Results of many studies have led to innovations in nickel-chromium-molybdenum alloys containing both high and low amounts of nickel. Higher molybdenum and chromium contents, together with nitrogen additions, have opened up an entirely new class of alloys having unique properties. In addition, a new chromium-base, fully wrought super stainless steel shows excellent promise in solving many corrosion problems. These newer alloys have the ability to combat uniform corrosion, localized corrosion, and stress-corrosion cracking in the harsh halogenic environment of the chemical process industry. This article briefly lists some of the major highlights and corrosion data on recent nickel-chromium-molybdenum and nickel-molybdenum alloys, and the development of a chromium-base, wrought super-austenitic alloy known as Nicrofer 3033 (Alloy 33). Some comparisons with existing alloys are presented, along with a few commercial applications.

  16. Etude in situ sous gradient thermique de l’écaillage d’alliages alumino-formeurs et de barrières thermiques aéronautiques

    OpenAIRE

    Sniezewski, Julien

    2008-01-01

    Le phénomène d'écaillage de la couche d'alumine formée à haute température sur l’alliage alumino-formeur PM2000 ou des barrières thermiques aéronautiques de type EB-PVD déposées sur des superalliages base nickel est étudié en utilisant un moyen d'essai spécialement développé au laboratoire. Entièrement automatisé, celui-ci permet de réaliser de longues campagnes de cyclage thermique tout en ayant la particularité d’imposer et de contrôler précisément un gradient de température dans la section...

  17. Simulation de réparation par soudage et billage ultrasonore d’un alliage à base Nickel

    OpenAIRE

    Jun LI

    2011-01-01

    Lors de la réparation d’un défaut, le processus consiste à éliminer la matière dans la zone englobant le défaut, puis à recharger cet affouillement par un dépôt de cordons de soudure, afin de remettre en conformité la pièce en vérifiant les critères de conception. Pourtant la zone rechargée constitue en elle-même un site sensible où le niveau des contraintes résiduelles peut être préjudiciable de par son importance, notamment localement, s’il porte des contraintes de traction. Les risques de ...

  18. Surface Bond Strength in Nickel Based Alloys

    OpenAIRE

    Ramesh, Ganesh; Padmanabhan, T. V.; Ariga, Padma; Joshi, Shalini; Bhuminathan, S.; Vijayaraghavan, Vasantha

    2012-01-01

    Bonding of ceramic to the alloy is essential for the longevity of porcelain fused to metal restorations. Imported alloys used now a days in processing them are not economical. So this study was conducted to evaluate and compare the bond strength of ceramic material to nickel based cost effective Nonferrous Materials Technology Development Center (NFTDC), Hyderabad and Heraenium S, Heraeus Kulzer alloy. An Instron testing machine, which has three-point loading system for the application of loa...

  19. Corrosion properties of plasma deposited nickel and nickel-based alloys

    Czech Academy of Sciences Publication Activity Database

    Voleník, Karel; Pražák, M.; Kalabisová, E.; Kreislová, K.; Had, J.; Neufuss, Karel

    2003-01-01

    Roč. 48, č. 3 (2003), s. 215-226. ISSN 0001-7043 R&D Projects: GA ČR GA106/99/0298 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma deposits, nickel , nickel -based alloys Subject RIV: JK - Corrosion ; Surface Treatment of Materials

  20. Nickel-Based Superalloy Resists Embrittlement by Hydrogen

    Science.gov (United States)

    Lee, Jonathan; Chen, PoShou

    2008-01-01

    A nickel-based superalloy that resists embrittlement by hydrogen more strongly than does nickel alloy 718 has been developed. Nickel alloy 718 is the most widely used superalloy. It has excellent strength and resistance to corrosion as well as acceptably high ductility, and is recognized as the best alloy for many high-temperature applications. However, nickel alloy 718 is susceptible to embrittlement by hydrogen and to delayed failure and reduced tensile properties in gaseous hydrogen. The greater resistance of the present nickel-based superalloy to adverse effects of hydrogen makes this alloy a superior alternative to nickel alloy 718 for applications that involve production, transfer, and storage of hydrogen, thereby potentially contributing to the commercial viability of hydrogen as a clean-burning fuel. The table shows the composition of the present improved nickel-based superalloy in comparison with that of nickel alloy 718. This composition was chosen to obtain high resistance to embrittlement by hydrogen while maintaining high strength and exceptional resistance to oxidation and corrosion. The most novel property of this alloy is that it resists embrittlement by hydrogen while retaining tensile strength greater than 175 kpsi (greater than 1.2 GPa). This alloy exhibits a tensile elongation of more than 20 percent in hydrogen at a pressure of 5 kpsi (approximately equal to 34 MPa) without loss of ductility. This amount of elongation corresponds to 50 percent more ductility than that exhibited by nickel alloy 718 under the same test conditions.

  1. TEXTURE ET ANISOTROPIE PLASTIQUE D'ALLIAGES AI-Li

    OpenAIRE

    MIZERA, Jaroslaw

    1993-01-01

    Le rôle spécifique des éléments d'alliage Li, Zr et Cu dans les alliages A1Li est déterminé en termes de leur influence sur l'évolution de la texture pendant un laminage et de leur incidence sur l'anisotropie plastique. Trois alliages modèles (Al-2,3% Li; Al-2,3% Li-0,1% Zr; Al-2,3%-1,2% Cu-0,1% Zr) sont lamines à chaud et à froid jusqu'à une réduction d'épaisseur de 92%. L'évolution de la texture et l'anisotropie des propriétés mécaniques de ces alliages sont caractérisées systématiquement a...

  2. Theromdynamics of carbon in nickel-based multicomponent solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, D. J.

    1978-04-01

    The activity coefficient of carbon in nickel, nickel-titanium, nickel-titanium-chromium, nickel-titanium-molybdenum and nickel-titanium-molybdenum-chromium alloys has been measured at 900, 1100 and 1215/sup 0/C. The results indicate that carbon obeys Henry's Law over the range studied (0 to 2 at. percent). The literature for the nickel-carbon and iron-carbon systems are reviewed and corrected. For the activity of carbon in iron as a function of composition, a new relationship based on re-evaluation of the thermodynamics of the CO/CO/sub 2/ equilibrium is proposed. Calculations using this relationship reproduce the data to within 2.5 percent, but the accuracy of the calibrating standards used by many investigators to analyze for carbon is at best 5 percent. This explains the lack of agreement between the many precise sets of data. The values of the activity coefficient of carbon in the various solid solutions are used to calculate a set of parameters for the Kohler-Kaufman equation. The calculations indicate that binary interaction energies are not sufficient to describe the thermodynamics of carbon in some of the nickel-based solid solutions. The results of previous workers for carbon in nickel-iron alloys are completely described by inclusion of ternary terms in the Kohler-Kaufman equation. Most of the carbon solid solution at high temperatures in nickel and nickel-titantium alloys precipitates from solution on quenching in water. The precipitate is composed of very small particles (greater than 2.5 nm) of elemental carbon. The results of some preliminary thermomigration experiments are discussed and recommendations for further work are presented.

  3. Thermal and mechanical treatments for nickel and some nickel-base alloys: Effects on mechanical properties

    Science.gov (United States)

    Hall, A. M.; Beuhring, V. F.

    1972-01-01

    This report deals with heat treating and working nickel and nickel-base alloys, and with the effects of these operations on the mechanical properties of the materials. The subjects covered are annealing, solution treating, stress relieving, stress equalizing, age hardening, hot working, cold working, combinations of working and heat treating (often referred to as thermomechanical treating), and properties of the materials at various temperatures. The equipment and procedures used in working the materials are discussed, along with the common problems that may be encountered and the precautions and corrective measures that are available.

  4. Utilisation de procedes de microfabrication pour la realisation de modules thermoelectriques a base d'alliages (Bi,Sb)2(Te,Se)3

    Science.gov (United States)

    Kashi, Siamak

    The production of thermoelectric devices uses nearly handmade techniques as an industry standard. These techniques are not suitable for the fabrication of smaller devices, where thermoelements are shorter than 1 millimetre. Researchers are focusing on how to decrease the height of thermoelements in a device, to the extent of depositing thermoelectric thin films. However, the best thermoelectric performances are obtained on modules fabricated from bulk material. Many tests were made to decrease the overall size of these devices, but until now, they would not permit to obtain the same range of performances as industrial devices. The aim of this project is to use microfabrication processes to obtain high power density thermoelectric devices. The precision obtained with the use of microfabrication techniques and automated methods has the potential to increase the performance and the industrial production of these devices. Fabrication steps were designed and tested in the facilities of the Ecole Polytechnique de Montreal to create hot extruded p-type and n-type (Bi,Sb)2(Te,Se)3 alloy based thermoelectric devices. These steps can be listed in three different categories, surface treatments, microfabrication methods and hot assembly. After cutting, p-type and n-type wafers were polished, underwent electropolishing and chemical etching before a diffusion barrier layer of nickel was deposited. Photolithography printed a pattern on the samples, where tin was then electroplated. A first assembly allowed soldering samples of each conduction type to alumina plates, before cutting the sample to free the thermoelements. A final assembly then created the finished devices by soldering of the two parts containing p-type and n-type thermoelements. The produced devices were functional, validating the designed steps. Electrical characterization of the best modules obtained indicate that the electromotive force is comparable to that of commercial modules under the same conditions

  5. Texture control during laser deposition of nickel-based superalloy

    International Nuclear Information System (INIS)

    A nickel-based superalloy was deposited on a nickel-based superalloy substrate by a laser-aided direct metal deposition process. The age-hardening behavior of the as-deposited clad was studied. The effect of laser beam scanning pattern on dendrite growth morphology was investigated using electron backscatter diffraction. Unidirectional laser beam scanning pattern developed a fiber texture; conversely, a backward and forward scanning pattern developed a rotated cube texture in the deposit. This paper reports a route to produce texture-controlled laser clad on a polycrystalline substrate.

  6. Chromium Activity Measurements in Nickel Based Alloys for Very High Temperature Reactors: Inconel 617, Haynes 230, and Model Alloys

    International Nuclear Information System (INIS)

    The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHXs) of (very) high temperature reactors ((V)-HTRs). The behavior under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra- and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer. The alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow (Rouillard, F., 2007, 'Mecanismes de formation et de destruction de la couche d'oxyde sur un alliage chrominoformeur en milieu HTR, Ph.D. thesis, Ecole des Mines de Saint-Etienne, France). To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T approximate to 1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617, and model alloys 1178, 1181, and 1201. This coupling makes it possible for the thermodynamic equilibrium to be obtained between the vapor phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (I) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared with that of the pure substance (Cr) at the same temperature

  7. Microstructures of nickel-base alloy dissimilar metal welds

    OpenAIRE

    Mouginot, Roman; Hänninen, Hannu

    2013-01-01

    Dissimilar metal welds (DMWs) between low-alloy steels (LAS), stainless steels (SS) and nickel-base alloys are very important in the design of conventional and nuclear power plants (NPPs). They help to reach better performances for high temperature environment but they can promote premature failure of components. Failure is often related to cracking in the heat affected zone of base materials. In this study, a literature review was conducted concerning the behavior of Inconel Ni-base alloy...

  8. Stress corrosion crack tip microstructure in nickel-based alloys

    International Nuclear Information System (INIS)

    Stress corrosion cracking behavior of several nickel-base alloys in high temperature caustic environments has been evaluated. The crack tip and fracture surfaces were examined using Auger/ESCA and Analytical Electron Microscopy (AEM) to determine the near crack tip microstructure and microchemistry. Results showed formation of chromium-rich oxides at or near the crack tip and nickel-rich de-alloying layers away from the crack tip. The stress corrosion resistance of different nickel-base alloys in caustic may be explained by the preferential oxidation and dissolution of different alloying elements at the crack tip. Alloy 600 (UNS N06600) shows good general corrosion and intergranular attack resistance in caustic because of its high nickel content. Thermally treated Alloy 690 (UNS N06690) and Alloy 600 provide good stress corrosion cracking resistance because of high chromium contents along grain boundaries. Alloy 625 (UNS N06625) does not show as good stress corrosion cracking resistance as Alloy 690 or Alloy 600 because of its high molybdenum content

  9. Etude des évolutions microstructurales et comportement mécanique des alliages base nickel 617 et 230 à haute température

    OpenAIRE

    Chomette, Sébastien

    2009-01-01

    Dans le cadre du développement des Réacteurs à Haute Température (RHT), un des systèmes retenus pour la quatrième génération de centrale nucléaire, l’utilisation d’un cycle indirect est envisagée. Ce type d’installation, utilisant de l’hélium comme caloporteur, nécessite un échangeur intermédiaire de chaleur (Intermediate Heat eXchanger, IHX) le plus compact possible entre les circuits primaire et secondaire. Les contraintes imposées par la conception ainsi que les conditions sévères d’utilis...

  10. Stress corrosion cracking of nickel-base alloy weldments

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) of weldments occurs in media such as chloride, hydrofluoric acid, polythionic acid, caustic soda and molten metals. Nickel-base alloys on account of their low SCC are preferred for weldments in the above media. However, the choice of a particular nickel-base alloy depends upon the condition in which they are used. Studies on this aspect are reviewed. In reprocessing plants, Ni-Cr-Mo alloy No6625 and No6455 are found suitable. The Ni-Cr alloy No6600 failed in BWR type reactor due intergranular SCC. The alloy No6690 which has a higher chromium content is immune to intergranular SCC. Reduction of free carbon in the matrix of the weld metal makes it resistant to intergranular SCC. (M.G.B.)

  11. Combined Laser and Mechanical Microdrilling of Nickel-Based Superalloy

    OpenAIRE

    Okasha, Mostafa Mohamed Mahmoud

    2011-01-01

    Drilling is an industrial process in which holes are produced by removal of material. This process is relatively well established for macroscale machining. However, microscale mechanical drilling is a more challenging process, especially in parts made of difficult-to-cut materials such as nickel-based superalloys. Although laser drilling and electrical discharge machining (EDM) have been reported as alternatives, mechanical drilling continues to be widely used for industrial macroscale drilli...

  12. ISOTHERMAL AND THERMOMECHANICAL FATIGUE OF A NICKEL-BASE SUPERALLOY

    OpenAIRE

    Carlos Carvalho Engler-Pinto Júnior; Dirceu Spinelli

    2014-01-01

    Thermal gradients arising during transient regimes of start-up and shutdown operations produce a complex thermal and mechanical fatigue loading which limits the life of turbine blades and other engine components operating at high temperatures. More accurate and reliable assessment under non-isothermal fatigue becomes therefore mandatory. This paper investigates the nickel base superalloy CM 247LC-DS under isothermal low cycle fatigue (LCF) and thermomechanical fatigue (TMF). Test ...

  13. Creep of nickel-base alloys in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Fish, J.S.; Attanasio, S.A.; Krasodomski, H.T.; Wilkening, W.W.; Was, G.S.; Cookson, J.; Yi, Y.

    1999-08-01

    Creep tests were performed to compare the creep behavior of commercial nickel-base alloys as a function of stress, temperature, and the environment. The results support earlier work that showed that low carbon alloys are more susceptible to creep and intergranular cracking than are high carbon alloys. Results also show a smaller influence of a water environment on the creep rate of commercial, creep-resistant alloys compared to high purity alloys.

  14. Nickel-based Nanomaterials for Electrochemical Supercapacitors

    KAUST Repository

    Alhebshi, Nuha A.

    2015-11-02

    The demand for energy storage technologies is rapidly increasing in portable electronics, transportation, and renewable energy systems. Thus, the objective of this research is to develop and enhance the performance of Ni-based electrochemical supercapacitors by optimizing synthesis conditions and design of the electrode materials. Conventional and on-chip supercapacitors were developed with notable performance enhancement. For conventional supercapacitors, a uniform and conformal coating process was developed to deposit Ni(OH)2 nanoflakes on carbon microfibers in-situ by a simple chemical bath deposition at room temperature. The microfibers conformally-coated with Ni(OH)2 make direct physical contacts with essentially every single nanoflakes, leading to more efficient electron transport. Using this strategy, we have achieved devices that exhibit five times higher specific capacitance compared to planar (non-conformal) Ni(OH)2 nanoflakes electrodes prepared by drop casting of Ni(OH)2 on the carbon microfibers (1416 F/g vs. 275 F/g). For on-chip storage applications, microfabricated supercapacitors were developed using a combination of top-down photolithography and bottom-up CBD. The resulting Ni(OH)2 micro-supercapacitors show high-rate redox activity up to 500 V/s and an areal cell capacitance of 16 mF/cm2 corresponding to a volumetric stack capacitance of 325 F/cm3. This volumetric capacitance is 2-fold higher than carbon and metal oxide based micro-supercapacitors. Furthermore, these micro-supercapacitors show a maximum energy density of 21 mWh/cm3, which is superior to the Li-based thin film batteries. To enhance cycling stability, Ni-Cu-OH and Ni-Co-OH ternary electrodes have been prepared with different Ni:Cu and Ni:Co ratios by CBD at room temperature on carbon microfibers. It is observed that the electrodes with Ni:Cu and Ni:Co composition ratio of 100:10 results in an optimum capacitance and cycling stability. For the optimum composition, Ni-Co-OH with

  15. Electrodeposition of nickel-based composite coatings for tribological applications

    OpenAIRE

    He, Yang

    2015-01-01

    The purpose of this research is to study, evaluate, and compare the different electro deposition processes for producing nickel-based composite coatings for application in tribology, including: Ni/BMA luminescent coating, Ni-P/MoS2 and Ni-P/WS2 self-lubricating coatings. In the first part, a new luminescent Ni coating containing an embedded, blue emitting rare-earth mixed metal oxide (BaMgAl11O17:Eu2+) BAM was electrodeposited successfully from an aqueous electrolyte. Two types of surfac...

  16. Microstructure Development in Nickel Base Superalloys during Weld Thermal Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Babu, S.S.; David, S.A.

    2000-04-26

    Welding plays an important role in the economical reuse and reclamation of used and failed nickel base superalloy blades. Previous research on microstructure development during laser beam welding of a single crystal CMSX4 alloy [Ref. l] showed non-equilibrium y/y{prime} microstructure development. In addition, the y{prime} precipitates were found to be irregular in shape and atom probe field ion microscopy illustrated the presence of diffusional concentration profile within the y phase in the as welded condition. To understand the above microstructure characteristics, y{prime} precipitation from y phase was investigated during continuous cooling from solutionizing temperature.

  17. Elevated temperature fretting fatigue of nickel based alloys

    Science.gov (United States)

    Gean, Matthew C.

    This document details the high temperature fretting fatigue of high temperature nickel based alloys common to turbine disk and blade applications. The research consists of three area of focus: Experiments are conducted to determine quantitatively the fretting fatigue lives of advanced nickel based alloys; Analytical tools are developed and used to investigate the fretting fatigue response of the material; Fractographic analysis of the experimental results is used to improve the analytical models employed in the analysis of the experiments. Sixty three fretting fatigue experiments were conducted at 649 °C using a polycrystalline Nickel specimen in contact with directionally solidified and single crystal Nickel pads. Various influences on the fretting fatigue life are investigated. Shot peened Rene' 95 had better fretting fatigue life compared to shot peened Rene' 88. Shot peening produced a 2x increase in life for Rene' 95, but only a marginal improvement in the fretting fatigue life for Rene' 88. Minor cycles in variable amplitude loading produces significant damage to the specimen. Addition of occasional overpeaks in load produces improvements in fretting fatigue life. Contact tractions and stresses are obtained through a variety of available tools. The contact tractions can be efficiently obtained for limited geometries, while FEM can provide the contact tractions for a broader class of problems, but with the cost of increased CPU requirements. Similarly, the subsurface contact stresses can be obtained using the contact tractions as a boundary condition with either a semi-analytical FFT method or FEM. It is found that to calculate contact stresses the FFT was only marginally faster than FEM. The experimental results are combined with the analysis to produce tools that are used to design against fretting fatigue. Fractographic analysis of the fracture surface indicates the nature of the fretting fatigue crack behavior. Interrupted tests were performed to analyze

  18. Urinary levels of nickel and chromium associated with dental restoration by nickel-chromium based alloys

    Institute of Scientific and Technical Information of China (English)

    Bo Chen; Gang Xia; Xin-Ming Cao; Jue Wang; Bi-Yao Xu; Pu Huang; Yue Chen; Qing-Wu Jiang

    2013-01-01

    This paper aims to investigate if the dental restoration of nickel-chromium based alloy (Ni-Cr) leads to the enhanced excretions of Ni and Cr in urine. Seven hundred and ninety-five patients in a dental hospital had single or multiple Ni-Cr alloy restoration recently and 198 controls were recruited to collect information on dental restoration by questionnaire and clinical examination. Urinary concentrations of Ni and Cr from each subject were measure by graphite furnace atomic absorption spectrometry. Compared to the control group, the urinary level of Ni was significantly higher in the patient group of 〈 1 month of the restoration duration, among which higher Ni excretions were found in those with either a higher number of teeth replaced by dental alloys or a higher index of metal crown not covered with the porcelain. Urinary levels of Cr were significantly higher in the three patient groups of 〈1, 1 to 〈3 and 3 to 〈6 months, especially in those with a higher metal crown exposure index. Linear curve estimations showed better relationships between urinary Ni and Cr in patients within 6-month groups. Our data suggested significant increased excretions of urinary Ni and Cr after dental restoration. Potential short- and long-term effects of Ni-Cr alloy restoration need to be investigated.

  19. HIGH CYCLE FATIGUE PROPERTIES OF NICKEL-BASE ALLOY 718

    Institute of Scientific and Technical Information of China (English)

    K.Kobayashi; K.Yamaguchi; M.Hayakawa; M.Kimura

    2004-01-01

    The fatigue properties of nickel-base Alloy 718 with fine- and grain-coarse grains were investigated. In the fine-grain alloy, the fatigue strength normalized by the tensile strengtn was 0.51 at 107 cycles. In contrast, the fatigue strength of the coarse-grain alloy was 0.32 at the same cycles, although the fatigue strengths in the range from 103to 105 cycles are the same for both alloys. The fracture appearances fatigued at around 106 cycles showed internal fractures originating from the flat facets of austenite grains for both alloys. The difference in fatigue strength at 107 cycles between the fine- and coarse-grain alloys could be explained in terms of the sizes of the facets from which the fractures originated.

  20. EBSD study of a hot deformed nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y.C., E-mail: yclin@csu.edu.cn [School of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China); Light Alloy Research Institute of Central South University, Changsha 410083 (China); State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083 (China); Wu, Xian-Yang; Chen, Xiao-Min [School of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China); Light Alloy Research Institute of Central South University, Changsha 410083 (China); Chen, Jian [School of Energy and Power Engineering, Key Laboratory of Efficient and Clean Energy Utilization, Changsha University of Science and Technology, Changsha 410114 (China); Wen, Dong-Xu; Zhang, Jin-Long; Li, Lei-Ting [School of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China); Light Alloy Research Institute of Central South University, Changsha 410083 (China)

    2015-08-15

    Highlights: • Isothermal compressive deformation behaviors of a nickel-based superalloy are studied. • Fraction of low angle grain boundaries decreases with the increase of temperature. • Fraction of low angle grain boundaries decreases with the decrease of strain rate. • Continuous and discontinuous dynamic recrystallizations take place in hot deformation. • Discontinuous dynamic recrystallization is the dominant nucleation mechanism. - Abstract: Hot deformation behaviors of a typical nickel-based superalloy are investigated by isothermal compression tests under the deformation temperature range of 920–1040 °C and strain rate range of 0.001–1 s{sup −1}. Scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) technique and transmission electron microscopy (TEM) are employed to study the evolution of hot deformed microstructures. It is found that the fraction of low angle grain boundaries decreases with the increase of deformation temperature or the decrease of strain rate. This is related to the decrease of dynamic recrystallization degree under the low deformation temperature or high strain rate. The fraction of low angle grain boundaries shows a rapid increase at the relatively small deformation degree, and then a significant decrease due to the progress of dynamic recrystallization (DRX). The microstructural changes indicate that both continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) take place during hot deformation. However, the small fraction of low angle boundaries with 10–15° misorientation indicates that the CDRX plays a minor role on the nucleation of dynamic recrystallization. Discontinuous dynamic recrystallization (DDRX) characterized by grain boundary bulging is the dominant nucleation mechanism for the studied superalloy.

  1. EBSD study of a hot deformed nickel-based superalloy

    International Nuclear Information System (INIS)

    Highlights: • Isothermal compressive deformation behaviors of a nickel-based superalloy are studied. • Fraction of low angle grain boundaries decreases with the increase of temperature. • Fraction of low angle grain boundaries decreases with the decrease of strain rate. • Continuous and discontinuous dynamic recrystallizations take place in hot deformation. • Discontinuous dynamic recrystallization is the dominant nucleation mechanism. - Abstract: Hot deformation behaviors of a typical nickel-based superalloy are investigated by isothermal compression tests under the deformation temperature range of 920–1040 °C and strain rate range of 0.001–1 s−1. Scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) technique and transmission electron microscopy (TEM) are employed to study the evolution of hot deformed microstructures. It is found that the fraction of low angle grain boundaries decreases with the increase of deformation temperature or the decrease of strain rate. This is related to the decrease of dynamic recrystallization degree under the low deformation temperature or high strain rate. The fraction of low angle grain boundaries shows a rapid increase at the relatively small deformation degree, and then a significant decrease due to the progress of dynamic recrystallization (DRX). The microstructural changes indicate that both continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) take place during hot deformation. However, the small fraction of low angle boundaries with 10–15° misorientation indicates that the CDRX plays a minor role on the nucleation of dynamic recrystallization. Discontinuous dynamic recrystallization (DDRX) characterized by grain boundary bulging is the dominant nucleation mechanism for the studied superalloy

  2. Analysis of polyaniline-based nickel electrodes for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Girija, T.C.; Sangaranarayanan, M.V. [Department of Chemistry, Indian Institute of Technology, Chennai 600 036 (India)

    2006-06-01

    Polyaniline is deposited potentiodynamically on a nickel substrate in the presence of p-toluene sulfonic acid and the specific capacitance is estimated. The electrochemical characterisation of the electrode is carried out by means of cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge experiments. The specific capacitance is {approx}4.05x10{sup 2}Fg{sup -1}. This indicates the feasibility of the polyaniline-coated nickel electrode for use in electrochemical supercapacitors. (author)

  3. Thermal stability of protective coatings produced on nickel based superalloy

    Directory of Open Access Journals (Sweden)

    M. Pytel

    2012-04-01

    Full Text Available Purpose: In this paper the results of high temperature cyclic oxidation tests of the protective diffusion coatings were presented. One of the main purposes of this work was to produce three different types of protective coatings by three different methods, i.e. slurry method, vapour phase aluminizing (VPA and chemical vapour deposition (CVD, applied on nickel based René 80 superalloy substrate.Design/methodology/approach: The high temperature cyclic oxidation tests were carried out in 23h cycles at constant temperature 1100°C using Carbolite CWF 1300 chamber furnace. The samples were removed outside and were weighted after each cycle. The microstructure investigations of all kinds of the coatings were conducted by the use of light microscope (Nikon Epiphot 300 and a scanning electron microscope (Hitachi S-3400N. In the analysis influence of each method have been taken into consideration, i.e. especially influence of the kind of process on microstructure, coating thickness, chemical composition, first of all aluminium content (in outer ȕ-NiAl layer so-called additive layer, diffusion layer and substrate. For the chemical composition examination x-ray energy dispersive (EDS method was applied using Thermo equipment.Findings: It was found that the best high cyclic oxidation resistance of coating was obtained using CVD method (the maximal increase of samples weight after 28th cycle was observed, whereas in case of the slurry sample after 3rd and VPA after 5th.Research limitations/implications: The research results will be used in the future in order to increase coating thickness, aluminium content and to produce Pt, Pd, Zr, Hf and Si modified aluminide coatings.Practical implications: The CVD method will be used to coat internal passages of turbine blades, for example to produce modified aluminide bond coats on single crystal nickel based superalloys.Originality/value: Chemical vapour deposition is an unique method which is a “pure method

  4. ISOTHERMAL AND THERMOMECHANICAL FATIGUE OF A NICKEL-BASE SUPERALLOY

    Directory of Open Access Journals (Sweden)

    Carlos Carvalho Engler-Pinto Júnior

    2014-06-01

    Full Text Available Thermal gradients arising during transient regimes of start-up and shutdown operations produce a complex thermal and mechanical fatigue loading which limits the life of turbine blades and other engine components operating at high temperatures. More accurate and reliable assessment under non-isothermal fatigue becomes therefore mandatory. This paper investigates the nickel base superalloy CM 247LC-DS under isothermal low cycle fatigue (LCF and thermomechanical fatigue (TMF. Test temperatures range from 600°C to 1,000°C. The behavior of the alloy is strongly affected by the temperature variation, especially in the 800°C-1,000°C range. The Ramberg-Osgood equation fits very well the observed isothermal behavior for the whole temperature range. The simplified non-isothermal stress-strain model based on linear plasticity proposed to represent the thermo-mechanical fatigue behavior was able to reproduce the observed behavior for both in-phase and out-of-phase TMF cycling.

  5. Property Enrichment of Aged Nickel Base Superalloy Supercast 247A

    Directory of Open Access Journals (Sweden)

    Lavakumar Avala

    2013-12-01

    Full Text Available The commercial nickel-base superalloy Supercast 247A can be used for applications in which is required high mechanical strength and corrosion resistance at elevated temperatures, such as turbine blades and automotive turbocharger rotors. The mechanical properties are totally connected to the morphology, size and distribution of γ' phase and carbides. In order to improve the mechanical properties, the material is subjected to solution and aging heat treatment, to raise the volume fraction of γ' phase in the matrix and to form carbides at grain boundaries. In the present study the Supercast 247A superalloy was remelted and cast to obtain the desired polycrystalline test bars by controlling casting parameters, followed by the investigation of precipitation morphology and mechanical properties with respect to solution treatment and aging treatment. The experimental results show that by well controlled casting parameters the Supercast 247A owns excellent castability to form a superalloy with fine grain structure, resistance to indentation as well as superior strength.

  6. The thermal transient effect on some nickel-based alloys

    International Nuclear Information System (INIS)

    This paper studies two nickel-based alloys after thermal transient tests. Two alloys were tested, namely Inconel 617 (UNS N06617) and Haynes 230 (UNS N06230). These materials are study for to be used in the construction of the steam generators of the future NPP reactors which must operate in severe conditions (high temperature, thermo-mechanical stress, aggressive media). The experiment consisted in thermal transient tests using a few scenarios: fast heating rates (50OC/minute) up to 1,000OC, maintaining this temperature level (0-60 minutes) and slowly/fast cooling. The metallographic analysis consisted in microstructure, micro-hardness determinations and traction tests. The average grain size was determined by linear interception method. The micro hardness was calculated by the relationship from the device technical book. On the traction diagrams the following mechanic characteristics were obtained: breaking resistance (Rm), elongation at rupture (A) and elastic modulus (E). The tested alloys were compared with the received materials. (authors)

  7. A Welding Process Test of Nickel Based Superalloy N06625 and its Composite Plate

    OpenAIRE

    Wen-Chao Zhou; Shan-Hua Xiao; Guo-Qi Luo

    2013-01-01

    Nickel based superalloy N06625 welding quality is directly related to whether to maintain good mechanical properties and excellent corrosion resisting property before welding. The test studies welding process of Nickel based superalloy N066255 and Its Composite Plate. The test results show that, strictly cleaning before welding, the pure argon protection, selecting welding consumables which have reasonable composition and making suitable welding parameters and pertinent operation techniques, ...

  8. Synthetic Microstructure-Based Lifing of Nickel-Based Superalloys

    Science.gov (United States)

    Tucker, Joseph C.

    This work focuses on the root cause of life limiting behavior in Ni-based superalloys for high pressure and temperature turbine disks applications in low cycle fatigue (LCF) by generating statistical volume elements (SVEs) of directly measured 3D microstructures for finite element method (FEM) simulations with crystal plasticity. Synthetic microstructures with experimentally determined microstructurally small fatigue crack (MSFC) weakest link features of as large as (ALA) grains and long annealing twins comprise the test cases. Upper limit truncated log-normal distributions account for the log-normal upper tail departure in grain size distributions of Ni-based superalloys more accurately representing ALA grains. Probability plots quantify the log-normality of grain sizes more effectively than traditional histograms. Twins are inserted into synthetic microstructures according to the coherent Sigma3 orientation relationship. A 3D measured dataset of the Inconel 100 (IN100) validates the Saltykov method stereology technique for estimating 3D grain size distributions from 2D; the 3D grain size distribution mean field and upper tail of IN100 is accurately predicted. The Saltykov method gave 3D grain sizes from a Rene 88 Damage Tolerant (R88DT) 2D dataset resulting in fatigue SVEs of approximately 1.5 million elements and 200 grains from FEM sensitivity studies. Changing mesh resolution minimally impacted global damage response, but converging locally requires significantly higher refinement. Fatigue interrogating FEM studies evolved hot spots in the local MSFC environment in one SVE, but not in another SVE with different crystallographic orientations, suggesting strong 3D full-field neighbor effects. The study revealed a need for slip line length considerations in crystal plasticity to better capture life limiting behavior. The findings point towards strictly limiting the ALA grain size in Ni-based superalloys to extend service life.

  9. Procédé de nitruration d'un alliage de titane superélastique pour des applications biomédicales Nitriding process of a superelastic titanium alloy for biomedical applications

    Directory of Open Access Journals (Sweden)

    Bedouin Yvan

    2013-11-01

    Full Text Available Dans le cadre de ce travail, nous avons mis au point un protocole de nitruration appliqué à un alliage Ti-Nb de type beta, biocompatible et qui présente des propriétés de superélasticité. Cet alliage a ainsi subi un traitement de nitruration en phase gazeuse suivi d'un traitement de recristallisation en phase beta et d'une trempe dans l'eau. Avec ce protocole, l'alliage est nitruré en surface et sa caractéristique superélastique est maintenue. Cet ensemble de propriétés mécaniques peut s'avérer très intéressante pour différentes applications biomédicales. Within the framework of this work, we developed a nitriding process on biocompatible Ti-Nb based beta-type alloy which presents superelastic property. This alloy underwent a nitriding treatment, which was followed by a recrystallization in the beta phase domain before quenching in water. With this protocol, the alloy is thus hardened by the presence of the nitride on the surface while its superelastic characteristic is maintained. This whole of mechanical properties can be very interesting for various biomedical applications.

  10. Fracture mechanics data and modeling of environmental cracking of nickel-base alloys in high temperature water

    International Nuclear Information System (INIS)

    This paper reports on environmental cracking of ductile nickel-base alloys which has occurred both in pressurized water reactors and boiling water reactor components such as pressure-vessel safe ends, weld butters, and filler metals for joining nickel-base alloys or dissimilar metals, and attachment welding pads on pressure vessels. Accurate assessment of the interrelated effects of material, environment, and mechanics on environmental cracking behavior of ductile nickel-base alloys in 288C water

  11. Analyses multi-échelles du comportement en fluage d'alliages de zirconium

    OpenAIRE

    Priser, Mathieu

    2011-01-01

    Les alliages de Zirconium sont utilisés dans l'industrie électronucléaire en tant que matériau de gainage du combustible. Les tubes assurent, entre autres, la fonction de confinement des produits de fission et d'échangeur thermique entre le combustible et le fluide caloporteur du circuit primaire. En service, les alliages sont soumis à des sollicitations thermomécaniques et neutroniques très sévères. La tenue mécanique des crayons combustibles à ces sollicitations constitue un point clé dans ...

  12. Modeling creep behavior in a directionally solidified nickel base superalloy

    Science.gov (United States)

    Ibanez, Alejandro R.

    Directionally solidified (DS) nickel-base superalloys provide significant improvements relative to the limitations inherent to equiaxed materials in the areas of creep resistance, oxidation, and low and high cycle fatigue resistance. Since these materials are being pushed to the limits of their capability in gas turbine applications, accurate mathematical models are needed to predict the service lives of the hot-section components to prevent unscheduled outages due to sudden mechanical failures. The objectives of this study are to perform critical experiments and investigate the high temperature tensile, fracture toughness, creep deformation, creep rupture and creep crack growth behavior of DS GTD111 as well as to apply creep deformation, rupture and crack growth models that will enable the accurate representation of the life times of the DS GTD111 superalloy gas turbine components that are exposed to high temperatures under sustained tensile stresses. The applied models will be capable of accurately representing the creep deformation, rupture and crack growth behavior as a function of stress, time and temperature. The yield strength and fracture toughness behavior with temperature is governed by the gamma particles. The longitudinal direction showed higher ductility and strength than the transverse direction. The TL direction exhibited higher fracture toughness than the LT orientation because the crack follows a more tortuous path. The longitudinal direction showed higher creep ductility, lower minimum strain rates and longer creep rupture times than the transverse direction. The results in the transverse direction were similar to the ones for the equiaxed version of this superalloy. Two models for creep deformation have been evaluated. The power-law model includes a secondary and a tertiary creep term with the primary creep represented by a constant. A theta-projection model has also been evaluated and it appears to provide a more accurate representation of creep

  13. Environmental effects of microstructure stability on nickel-base superalloys

    International Nuclear Information System (INIS)

    Next generation nuclear reactor VHTR (Very High Temperature gas-cooled Reactor) wants to achieve higher thermal efficiency and hydrogen production. IHX (Intermediate Heat eXchanger) will be exposed to the highest temperature condition among lots of structural components. Solid-solution hardening nickel-base superalloys Alloy 617 and Haynes 230 are expected to use for this applications. Studies on oxidation test and time dependent deformation at 900 .deg. C were conducted before. This study is focused on the microstructure evolution and mechanical properties at other temperature ranges. Furthermore, considering heat treatment history especially cooling rate effects on microstructure evolution, those of two superalloys are cooled down to room temperature by air and furnace. Materials behavior at intermediation temperature ranges from 600-900 .deg. C and diffusion bonding condition (1150 .deg. C) were evaluated. Vicker's hardness test and small-size tensile test were carried out for each specimen at room temperature. Hardness number and tensile strength were higher than any other temperature condition at 700 .deg. C due to gamma prime phases for Alloy 617. As the aluminum contents of Haynes 230 is far less than Alloy 617, there is no big difference for Haynes 230 at intermediate temperature ranges. The value of mechanical property of alloys at 1150 .deg. C air cooling condition was severely decreased and fully ductile fracture was detected for both alloys. On the other hand, the values showed the tendency of return to the intermediate temperature ranges when the specimen was slowly cooled down. Characteristic precipitates along the grain boundaries were detected. There was no other singularity up to 700 .deg. C for Alloy 617. However, lots of tiny M23C6 type carbide were formed after 800 .deg. C heat treatment, and those of carbide got bigger and bigger as the heat treatment temperature increased up to 900 .deg. C. For diffusion bonding temperature, grain boundary

  14. Catalysts for ethylene dimerization based on tris-(ethylene)-nickel

    Energy Technology Data Exchange (ETDEWEB)

    Petrushanskaya, N.V.; Kurapova, A.I.; Feldblyum, V.SH.

    1978-01-01

    Tris(ethylene)nickel(0) was synthesized in one stage by reducing nickel di-tert.-butyl benzoate with triethylaluminum in diethyl ether saturated with ethylene. Combinations of the obtained complex with Lewis acids (i.e., boron trifluoride and aluminum halides or alkylhalides) proved to be active catalysts for ethylene oligomerization. The catalytic systems showed maximum activities at BF/sub 3//Ni molar ratio of 3:1 and AlCl/sub 3//Ni ratio of 4:1, with approx. 85% selectivities for butenes at these ratios. The oligomerization products contained 82-98% butenes, including 70-90% n-butenes, up to 14% hexenes, and approx. 3-4% octenes. The over-all yield of oligomers at -30/sup 0/C was twice that at +20/sup 0/C due to the low thermal stability of the catalytic systems. The activity of the cataysts is probably due to the formation by nickel of a paramagnetic complex in which BF/sub 3/ molecules replace ethylene. Tables and spectrum.

  15. Nickel Ion Release from Three Types of Nickel-titanium-based Orthodontic Archwires in the As-received State and After Oral Simulation.

    Science.gov (United States)

    Ramazanzadeh, Barat Ali; Ahrari, Farzaneh; Sabzevari, Berahman; Habibi, Samaneh

    2014-01-01

    Background and aims. This study aimed to investigate release of nickel ion from three types of nickel-titanium-based wires in the as-received state and after immersion in a simulated oral environment. Materials and methods. Forty specimens from each of the single-strand NiTi (Rematitan "Lite"), multi-strand NiTi (SPEED Supercable) and Copper NiTi (Damon Copper NiTi) were selected. Twenty specimens from each type were used in the as-received state and the others were kept in deflected state at 37ºC for 2 months followed by autoclave sterilization. The as-received and recycled wire specimens were immersed in glass bottles containing 1.8 mL of artificial saliva for 28 days and the amount of nickel ion released into the electrolyte was determined using atomic absorption spectrophotometry. Results. The single-strand NiTi released the highest quantity of nickel ion in the as-received state and the multi-strand NiTi showed the highest ion release after oral simulation. The quantity of nickelion released from Damon Copper NiTi was the lowest in both conditions. Oral simulation followed by sterilization did not have a significant influence on nickel ion release from multi-strand NiTi and Damon Copper NiTi wires, but single-strand NiTi released statistically lower quantities of nickel ion after oral simulation. Conclusion. The multi-strand nature of Supercable did not enhance the potential of corrosion after immersion in the simulated oral environment. In vitro use of nickel-titanium-based archwires followed by sterilization did not significantly increase the amount of nickel ion released from these wires. PMID:25093049

  16. On the weldability of grey cast iron using nickel based filler metal

    International Nuclear Information System (INIS)

    Shielded metal arc welding process using nickel based filler metal was used to join grey cast iron. The effect of post weld heat treatment (PWHT) on the microstructure and hardness was studied. PWHT included heating up to 870 oC, holding for 1 h at 870 oC and then furnace cooling. By using nickel based filler metal, formation of hard brittle phase (e.g. carbides and martensite) in the fusion zone is prevented. Before PWHT, heat affected zone exhibited martensitic structure and partially melted zone exhibited white cast iron structure plus martensite. Applied PWHT resulted in the dissolution of martensite in heat affected zone and graphitization and in turn the reduction of partially melted zone hardness. Results showed that welding of grey cast iron with nickel based filler metal and applying PWHT can serve as a solution for cast iron welding problems.

  17. Contributions à l'étude thermomécanique des alliages à mémoire de forme NiTi et à la réalisation par soudage de matériaux architecturés NiTi

    OpenAIRE

    Delobelle, Vincent

    2012-01-01

    Les alliages à mémoire de forme Nickel Titane sont des matériaux aux propriétés remarquablesdues à une transformation martensitique réversible et sont largement utiliséspar l’industrie biomédicale et dans des dispositifs de type actionneurs. La première partiede cette étude porte sur une analyse de leur comportement thermomécanique basée surla réalisation de mesures de champs cinématiques (par corrélation d’images visibles) etthermiques (par caméra infrarouge). Une part importante du travail ...

  18. Ségrégation et précipitation dans les alliages fer-chrome hors et sous irradiation

    OpenAIRE

    Senninger, Oriane

    2013-01-01

    Les alliages fer-chrome présentent des comportements thermodynamiques et cinétiques particuliers liés à leurs propriétés magnétiques. La décomposition de l’alliage par vieillissement thermique a été étudiée dans cette thèse. Pour cela, un modèle cinétique de la décomposition de l’alliage à l’échelle atomique a été développé en modélisant de façon détaillée les propriétés thermodynamiques et de diffusion des espèces chimiques dans l’alliage. L’évolution des propriétés de diffusion des éléments...

  19. Effect of electroless plating nickel treatment on electrode properties of Zr-based AB2 type alloy

    Institute of Scientific and Technical Information of China (English)

    文明芬; 翟玉春; 陈廉; 佟敏; 郑华; 马荣骏

    2001-01-01

    An electroless plating nickel treatment was processed to improve the active behaviors and discharge capacities of Zr-based AB2 alloys. The effects of the nickel coating on the surface appearance, the structure of the alloy powders and the electrode characteristics were investigated. It is found that the Ni-rich layer formed through electroless plating nickel treatment plays an important role on the initial activation property and the discharge capacity of Zr-based alloy. The optimal content of electroless plating nickel is about 15 %, and the discharge capacity of the electrode can be increased to 400mA· h·g 1 after 6 cycles. Although coated nickel is beneficial for quick activation and discharge capacity, excessive electroless plating nickel can result in a decreased discharge capacity.

  20. Soudage homogène MIG de l'alliage d'aluminium 6061 MIG homogeneous welding of 6061 aluminium alloy

    Directory of Open Access Journals (Sweden)

    Benoit Alexandre

    2013-11-01

    Full Text Available Le soudage homogène (métal d'apport identique au métal de base de l'alliage d'aluminium 6061 avec un procédé dit semi-automatique (MIG n'a jamais été reporté jusqu'à maintenant dans la littérature. Nous montrons ici que l'utilisation d'un dérivé du procédé de soudage MIG, le MIG CMT (Cold Metal Transfer permet d'obtenir des cordons de soudures sains (sans fissuration à chaud. De plus des traitements thermiques ont permis de retrouver partiellement ou de restaurer totalement les propriétés de la soudure. Nos résultats sont comparés à des essais de soudage MIG CMT avec le métal d'apport préconisé pour le soudage de l'alliage 6061. The homogeneous welding (same filler metal as base metal of the 6061 aluminium alloy with MIG process has never been reported in the open access literature. This work shows that the CMT (Cold Metal Transfer MIG, a derivative of MIG, allows producing welds without hot-cracking. Moreover, further heat treatments partially increased or fully restore the mechanical properties of the weld. These results are compared with 6061 heterogeneous welds usually met in the industry.

  1. STRESS CORROSION CRACKING OF NICKEL BASE SUPERALLOYS IN AERATED SUPERCRITICAL WATER

    OpenAIRE

    Fournier, L.; Delafosse, David; Bosch, C.; Magnin, Thierry

    2001-01-01

    The stress corrosion cracking behaviour of two nickel base superalloys (A718 and A690) is investigated in aerated supercritical water by means of constant extension rate tensile (CERT) tests at 400°C and 25 MPa. Alloy 718 is observed to be extremely sensitive to intergranular stress corrosion cracking (IGSCC) while alloy 690 is found to be immune to IGSCC. CERT tests are also carried out in air and under vacuum on both alloys at 600°C, i.e. in a temperature domain where nickel base superalloy...

  2. Dopamine biosensor based on surface functionalized nanostructured nickel oxide platform.

    Science.gov (United States)

    Roychoudhury, Appan; Basu, Suddhasatwa; Jha, Sandeep Kumar

    2016-10-15

    A dopamine biosensor has been developed using nickel oxide nanoparticles (NPs) and tyrosinase enzyme conjugate. Nickel oxide (NiO) NPs were synthesized by sol-gel method using anionic surfactant, sodium dodecyl sulphate (SDS), as template to control the size of synthesized nanoparticles. The structural and morphological studies of the prepared NPs were carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. Afterwards, tyrosinase enzyme molecules were adsorbed on NiO NPs surface and enzyme coated NPs were deposited on indium tin oxide (ITO) coated flexible polyethylene terephthalate (PET) substrate by solution casting method. The formation of enzyme-NPs conjugate was investigated by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) techniques and used in selective detection and estimation of neurochemical dopamine by electrochemical method. The fabricated Tyrosinase/NiO/ITO electrode exhibits high sensitivity of 60.2nA/µM in linear detection range (2-100μM) with a detection limit of 1.038μM. The proposed sensor had a response time of 45s, long shelf life (45 days) with good reproducibility and selectivity in presence of interfering substances and was validated with real samples. The tyrosinase enzyme functionalized NiO platform has good bio-sensing efficacy and can be used in detection of other catecholamines and phenolic neurochemicals. PMID:26626970

  3. Effect of hydrogenated low temperature water on fracture toughness of nickel-based weld metals

    International Nuclear Information System (INIS)

    Nickel-based alloys are susceptible to a form of hydrogen embrittlement, Low Temperature Crack Propagation (LTCP), which can cause severe degradation of the fracture resistance of nickel-based alloys. LTCP may occur in low temperature water, with the highest susceptibility reported at about 55 deg C, with high stress and slow loading rate in pre-cracked Ni-based materials. Although LTCP has not been reported in commercial reactors, the susceptibility of different alloys is important to establish. As a part of the Finnish Reactor Safety Program, SAFIR 2010, the effect of hydrogenated Pressurized Water Reactor, PWR, primary water on the LTCP susceptibility of nickel-based weld metals of Alloy 182, 82, 152 and 52 was studied performing J-R-tests at a slow displacement rate in simulated low temperature PWR primary water. The results revealed that Alloy 182 is the most susceptible nickel-based weld metal to LTCP. Pure weld metal specimens were substantially more susceptible to LTCP than the dissimilar metal weld specimens. Pre-exposure to high temperature hydrogenated water did not affect remarkably the fracture toughness of any of the test materials. (orig.)

  4. Photoelectrochemical study of nickel base alloys oxide films formed at high temperature and high pressure water

    Energy Technology Data Exchange (ETDEWEB)

    Marchetti, L. [CEA, DEN, DPC, SCCME, Laboratoire d' Etude de la Corrosion Aqueuse, F-91191 Gif-sur-Yvette (France); Perrin, S., E-mail: steph.perrin@cea.f [CEA, DEN, DPC, SCCME, Laboratoire d' Etude de la Corrosion Aqueuse, F-91191 Gif-sur-Yvette (France); Wouters, Y. [SIMaP, CNRS/INP-Grenoble/UJF F-38402, Saint Martin d' Heres Cedex (France); Martin, F. [CEA, DEN, DPC, SCCME, Laboratoire d' Etude de la Corrosion Aqueuse, F-91191 Gif-sur-Yvette (France); Pijolat, M. [LPMG-UMR CNRS 5148, Centre SPIN, Ecole Nationale Superieure des Mines, 158 Cours Fauriel, F-42023 Saint-Etienne (France)

    2010-07-30

    The oxide film formed on nickel base alloys at high temperature and high pressure water exhibits semi-conducting properties evidenced by photocurrent generation when exposed to monochromatic light. The use of macro- and micro-photoelectrochemical techniques (PEC and MPEC) aims to identify the different semiconductor phases and their distribution in the oxide film. Three different nickel base alloys were corroded in recirculation loop at 325 {sup o}C in pressurised water reactor primary coolant conditions for different exposition durations. PEC experiments on these materials enable to obtain macroscopic energy spectra showing three contributions. The first one, with a band gap around 2.2 eV, was attributed to the presence of nickel hydroxide and/or nickel ferrite. The second one, with a band gap around 3.5 eV, was attributed to Cr{sub 2}O{sub 3}. The last contribution, with a band gap in the range of 4.1-4.5 eV, was attributed to the spinel phase Ni{sub 1-x}Fe{sub x}Cr{sub 2}O{sub 4}. In addition, macroscopic potential spectra recorded at different energies highlight n-type semi-conduction behaviours for both oxides, Cr{sub 2}O{sub 3} and Ni{sub 1-x}Fe{sub x}Cr{sub 2}O{sub 4}. Moreover, MPEC images recorded at different energies exhibit contrasted regions in photocurrent, describing the distribution of nickel hydroxide and/or nickel ferrite and Cr{sub 2}O{sub 3} in the oxide film at a micron scale. It is concluded that PEC techniques represent a sensitive and powerful way to locally analyse the various semiconductor phases in the oxide scale.

  5. Use of atomic force microscopy to quantify slip irreversibility in a nickel-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Risbet, M.; Feaugas, X.; Guillemer-Neel, C.; Clavel, M

    2003-09-15

    Atomic force microscopy was used to study the evolution of surface deformation during cyclic loading in a nickel-base superalloy. Cyclic slip irreversibility has been investigated using quantitative evaluation of extrusion heights and inter-band spacing. This approach is applied to formulate a microscopic crack initiation law, compared to a classical Manson-Coffin relationship.

  6. Use of atomic force microscopy to quantify slip irreversibility in a nickel-base superalloy

    International Nuclear Information System (INIS)

    Atomic force microscopy was used to study the evolution of surface deformation during cyclic loading in a nickel-base superalloy. Cyclic slip irreversibility has been investigated using quantitative evaluation of extrusion heights and inter-band spacing. This approach is applied to formulate a microscopic crack initiation law, compared to a classical Manson-Coffin relationship

  7. New nickel-based bulk metallic glasses with extremely high nickel content

    International Nuclear Information System (INIS)

    The effect of boron addition on glass formation in the Ni70Pd10P20 alloy was investigated. The composition containing 4 at% boron showed an improved glass-forming ability. A glassy Ni70Pd10P16B4 alloy rod with a diameter of 2.5 mm was prepared by a copper mold casting technique. This is the first time that a Ni-based bulk metallic glass with such an extremely high Ni content of 70 at% has been produced. The obtained glassy Ni70Pd10P16B4 alloy exhibited rather good mechanical properties and corrosion resistance.

  8. Synthesis of novel chelating benzimidazole-based carbenes and their nickel(II) complexes: activity in the Kumada coupling reaction

    NARCIS (Netherlands)

    Berding, J.; Lutz, M.; Spek, A.L.; Bouwman, E.

    2009-01-01

    Nickel(II) halide complexes of novel chelating bidentate benzimidazole-based N-heterocyclic carbenes have been prepared from Ni(OAc)2 and bisbenzimidazolium salts. Single-crystal X-ray structure determination on four complexes revealed a cis-geometry on a square-planar nickel center. The complexes a

  9. The metallographic investigation of brazed joints in nickel base alloys using various techniques for the production of contrast

    International Nuclear Information System (INIS)

    Brazing with high melting point nickel base brazing alloys permits distortion-free, high strength joints to be produced in high temperature, high alloy steel and nickel alloys which cannot easily be welded. This method is used for gas turbine parts subject to high thermal stresses and in nuclear engineering. (orig.)

  10. Nickel-base alloy forgings for advanced high temperature power plants

    Energy Technology Data Exchange (ETDEWEB)

    Donth, B.; Diwo, A.; Blaes, N.; Bokelmann, D. [Saarschmiede GmbH Freiformschmiede, Voelklingen (Germany)

    2008-07-01

    The strong efforts to reduce the CO{sub 2} emissions lead to the demand for improved thermal efficiency of coal fired power plants. An increased thermal efficiency can be realised by higher steam temperatures and pressures in the boiler and the turbine. The European development aims for steam temperatures of 700 C which requires the development and use of new materials and also associated process technology for large components. Temperatures of 700 C and above are too high for the application of ferritic steels and therefore only Nickel-Base Alloys can fulfill the required material properties. In particular the Nickel-Base Alloy A617 is the most candidate alloy on which was focused the investigation and development in several German and European programs during the last 10 years. The goal is to verify and improve the attainable material properties and ultrasonic detectability of large Alloy 617 forgings for turbine rotors and boiler parts. For many years Saarschmiede has been manufacturing nickel and cobalt alloys and is participating the research programs by developing the manufacturing routes for large turbine rotor forgings up to a maximum diameter of 1000 mm as well as for forged tubes and valve parts for the boiler side. The experiences in manufacturing and testing of very large forgings made from nickel base alloys for 700 C steam power plants are reported. (orig.)

  11. Understanding and predicting the behaviour of silver base neutron absorbers under irradiations; Comprehension et prediction du comportement sous irradiation neutronique d`alliages absorbants a base d`argent

    Energy Technology Data Exchange (ETDEWEB)

    Desgranges, C

    1998-12-31

    The effect of neutron irradiation induced transmutations on the swelling of AgInCd (AIC) alloys used as neutron absorber in the control rods of Pressurized Water Reactors has been studied both experimentally and theoretically. Effective atomic volumes have been determined in synthetic AgCdInSn alloys with various compositions and containing fcc and hc phases, representative of irradiated AIC (Sn is a transmutation product). Swelling is shown to result first from the transmutation of Ag into Cd and of In into Sn, both with larger effective volume than the mother atom, and second from grain boundaries precipitation of s still less dense hc phase when solid solubility of transmuted products is exceeded. For both fcc and hc phases, we have determined profiles at the temperatures in the vicinity of the operating temperature. Unusual characteristics of second phase growth at grain boundaries induced by transmutations are identified on a simple binary alloy model: kinetics is controlled by irradiation temperature which scales diffusivities and flux which scales transmutation rates, as well as by the grain size in the underlying matrix. To address the AgInCdSn alloys, a novel technique is proposed to model diffusion in multicomponent alloys. It is based on a linearization of a simple atomistic model. With a single set of parameters, for each phase, our model well reproduces our interdiffusion measurements in quaternary alloys as well as existing interdiffusion experiments in binary alloys. Finally this diffusion model implemented with a moving interface algorithm is used to model the growth of the second phase induced by transmutation in the AIC under irradiation. (authors) 74 refs.

  12. Nickel Dermatitis - Nickel Excretion

    DEFF Research Database (Denmark)

    Menné, T.; Thorboe, A.

    1976-01-01

    Nickel excretion in urine in four females -sensitive to nickel with an intermittent dyshidrotic eruption was measured with flameless atomic absorption. Excretion of nickel was found to be increased in association with outbreaks of vesicles. The results support the idea that the chronic condition ...

  13. Nickel Ion Release from Three Types of Nickel-titanium-based Orthodontic Archwires in the As-received State and After Oral Simulation

    OpenAIRE

    Barat Ali Ramazanzadeh; Farzaneh Ahrari; Berahman Sabzevari; Samaneh Habibi

    2014-01-01

    Background and aims. This study aimed to investigate release of nickel ion from three types of nickel-titanium-based wires in the as-received state and after immersion in a simulated oral environment. Materials and methods. Forty specimens from each of the single-strand NiTi (Rematitan “Lite”), multi-strand NiTi (SPEED Supercable) and Copper NiTi (Damon Copper NiTi) were selected. Twenty specimens from each type were used in the as-received state and the others were kept in deflec...

  14. Metallographic examination of TD-nickel base alloys

    International Nuclear Information System (INIS)

    To observe the microstructures in TD-nickel-chromium (TD--NiCr), standard Ni-etch (92 percent HCl, 3 percent HNO3, 5 percent H2SO4), chromic acid and oxalic acid solutions were found unsatisfactory chemical etches. However, an electrochemical etch consisting of six parts ethanol, one part H2SO4 and twenty-one parts H2O delineated the grains when the etching voltage was five volts. The efficiency of this etch decreased dramatically with the increasing grain size. It was later found that a thermal-oxidation etch produced better detail of grain boundaries and had excellent etching behavior over the entire range of grain sizes of TD-NiCr produced (0.001 mm to 0.5 mm). The etching procedure was that of placing a polished specimen of TD--NiCr in a preheated furnace at 6000C for times of 5 to 10 min. A selective oxidation of the grain boundaries occurred. For grain sizes greater than about 0.05 mm, some heat tinting was noted which aided in grain observations. No microstructural changes were found as a result of this thermal etching technique. (U.S.)

  15. Research on CMT welding of nickel-based alloy with stainless steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Cold Metal Transfer (CMT) welding technique is a new welding technique introduced by Fronius company. CMT welding of nickel-based alloy with stainless steel was carried out using CuSi3 filler wire in this paper. Effects of welding parameters, including welding current, welding speed, etc, on weld surface appearance were tested. Microstructure and mechanical properties of CMT weld were studied. The results show that the thickness of interface reaction layer of the nickel-based alloy is 14.3μm, which is only 4.33% of base material. The weld is made up of two phases,α-copper and iron-based solid solution. Rupture occurs initially at the welded seam near the edge of stainless steel in shear test. The maximum shear strength of the CuSi3 welded joint is 184.9MPa.

  16. 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)

  17. Low Cycle Fatigue and Thermo-Mechanical Fatigue of Uncoated and Coated Nickel-Base Superalloys

    OpenAIRE

    Stekovic, Svjetlana

    2007-01-01

    High strength nickel-base superalloys have been used in turbine blades for many years because of their superior performance at high temperatures. In such environments superalloys have limited oxidation and corrosion resistance and to solve this problem, protective coatings are deposited on the surface. The positive effect of coatings is based on protecting the surface zone in contact with hot gas atmosphere with a thermodynamically stable oxide layer that acts as a diffusion barrier. During s...

  18. High gas velocity oxidation and hot corrosion testing of oxide dispersion-strengthened nickel-base alloys

    Science.gov (United States)

    Deadmore, D. L.; Lowell, C. E.

    1975-01-01

    Several oxide dispersion strengthened (ODS) nickel-base alloys were tested in high velocity gases for cyclic oxidation resistance at temperatures to 1200 C and times to 500 hours and for hot corrosion resistance at 900 C for 200 hours. Nickel-chromium-aluminum ODS alloys were found to have superior resistance to oxidation and hot corrosion when compared to bare and coated nickel-chromium ODS alloys. The best of the alloys tested had compositions of nickel - 15.5 to 16 weight percent chromium with aluminum weight percents between 4.5 and 5.0. All of the nickel-chromium-aluminum ODS materials experienced small weight losses (less than 16 mg/sq cm).

  19. Qualification of new filler metal made of high chromium content nickel base alloy

    International Nuclear Information System (INIS)

    A study has been carried out by EDF and FRAMATOME in the context of the French Association for design and manufacturing rules of nuclear power boiler's equipment, to research then qualify filler metals dedicated to the welding of the new nickel base including 30 % chromium alloy components of PWR. The aim is to assess their weldability and their stress corrosion behaviour in the conditions prevailing in the primary cooling system of PWR and to compare with products generally used. Moreover, numerous qualification tests have been carried out to verify that such metals meet the criteria accepted in the RCC-M code. Results allowed to qualify some filler metals made of nickel base alloy of qualify equivalent to the one of NC30Fe including 30 % chromium base metals. These metals are at present time used in manufacturing. (authors). 5 figs

  20. Modification Approach of Fuzzy Logic Model for Predicting of Cutting Force When Machining Nickel Based Hastelloy C-276

    OpenAIRE

    BASIM A. KHIDHIR; Bashir Mohamed; Mahmoud A.A. Younis

    2010-01-01

    Problem statement: Most Nickel based Hastelloy C-276 is a difficult-to-machine material because of its low thermal diffusive property and high strength at high temperature. Machinability consideration of nickel based Hastelloy C-276 in turning operations has been carried out using ceramic inserts under dry conditions. Approach: This study described a modification approach applied to a fuzzy logic based model for predicting cutting force where the machining parameters for c...

  1. Minimizing the bimetallic bending for cryogenic metal optics based on electroless nickel

    Science.gov (United States)

    Kinast, Jan; Hilpert, Enrico; Lange, Nicolas; Gebhardt, Andreas; Rohloff, Ralf-Rainer; Risse, Stefan; Eberhardt, Ramona; Tünnermann, Andreas

    2014-07-01

    Ultra-precise metal optics are key components of sophisticated scientific instruments in astronomy and space applications. Especially for cryogenic applications, a detailed knowledge and the control of the coefficient of thermal expansion (CTE) of the used materials are essential. Reflective optical components in IR- and NIR-instruments primarily consist of the aluminum alloy Al6061. The achievable micro-roughness of diamond machined and directly polished Al6061 does not fulfill the requirements for applications in the visible spectral range. Electroless nickel enables the reduction of the mirror surface roughness to the sub-nm range by polishing. To minimize the associated disadvantageous bimetallic effect, a novel material combination for cryogenic mirrors based on electroless nickel and hypereutectic aluminum-silicon is investigated. An increasing silicon content of the aluminum material decreases the CTE in the temperature range to be considered. This paper shows the CTE for aluminum materials containing about 42 wt% silicon (AlSi42) and for electroless nickel with a phosphorous content ranging from 10.5 to 13 %. The CTE differ to about 0.5 × 10-6 K-1 in a temperature range from -185 °C (LN2) to 100 °C. Besides, the correlations between the chemical compositions of aluminum-silicon materials and electroless nickel are shown. A metrology setup for cryo-interferometry was developed to analyze the remaining and reversible shape deviation at cryogenic temperatures. Changes could be caused by different CTE, mounting forces and residual stress conditions. In the electroless nickel layer, the resulting shape deviation can be preshaped by deterministic correction processes such as magnetorheological finishing (MRF) at room temperature.

  2. FSW : UN PROCEDE DE SOUDAGE POUR LES ALLIAGES D'ALUMINIUM DE FONDERIE

    OpenAIRE

    ZIMMER-CHEVRET, Sandra; GUYOMARD, Claude; Langlois, Laurent; BIGOT, Régis; Martin, Patrick

    2009-01-01

    L'étude présentée concerne la réalisation d'un démonstrateur mettant en évidence le potentiel du procédé de soudage par friction malaxage ( FSW) pour la reconception et la réalisation de pièce en alliages d'aluminium de fonderie. Le potentiel du FSW vient en grande partie du fait que la matière n'atteint pas la fusion lors de l'élaboration de la soudure. Ceci permet notamment de souder des alliages sensibles à la fissuration à chaud et de réaliser des assemblages hétérogènes. La reconception ...

  3. FSW : UN PROCEDE DE SOUDAGE POUR LES ALLIAGES D’ALUMINIUM DE FONDERIE

    OpenAIRE

    ZIMMER-CHEVRET, Sandra; LAYE, Julien; GUYOMARD, Claude; Langlois, Laurent; BIGOT, Régis; Martin, Patrick

    2009-01-01

    L’étude présentée concerne la réalisation d’un démonstrateur mettant en évidence le potentiel du procédé de soudage par friction malaxage ( FSW) pour la reconception et la réalisation de pièce en alliages d’aluminium de fonderie. Le potentiel du FSW vient en grande partie du fait que la matière n’atteint pas la fusion lors de l’élaboration de la soudure. Ceci permet notamment de souder des alliages sensibles à la fissuration à chaud et de réaliser des assemblages hétérogènes. La reconception ...

  4. Atomic force microscopy imaging to measure precipitate volume fraction in nickel-based superalloys

    International Nuclear Information System (INIS)

    In nickel-based superalloys, quantitative analysis of scanning electron microscopy images fails in providing accurate microstructural data, whereas more efficient techniques are very time-consuming. As an alternative approach, the authors propose to perform quantitative analysis of atomic force microscopy images of polished/etched surfaces (quantitative microprofilometry). This permits the measurement of microstructural parameters and the depth of etching, which is the main source of measurement bias. Thus, nonbiased estimations can be obtained by extrapolation of the measurements up to zero etching depth. In this article, the authors used this approach to estimate the volume fraction of γ' precipitates in a nickel-based superalloy single crystal. Atomic force microscopy images of samples etched for different times show definition, homogeneity, and contrast high enough to perform image analysis. The result after extrapolation is in very good agreement with volume fraction values available from published reports

  5. An investigation into cracking in nickel-base superalloy repair welds

    OpenAIRE

    Rush, M. T.; Colegrove, Paul A.; Zhang, Z; Courtot, B.

    2010-01-01

    The nickel-base superalloy Rene 80 is considered very susceptible to liquation and strain-age cracking. Material in the solutionised condition is welded using the Cold Metal Transfer, or CMT process (with ductile filler alloy) and autogenously using a laser. Grain size is shown to have a significant effect on cracking. Using the CMT, welding power is shown to have high significance on the level of cracking, whereas welding speed has little effect. When welding using the lase...

  6. RESIDUAL STRESS IN NICKEL BASE SUPER ALLOY UDIMET 720 FOR DIFFERENT SURFACE CONDITIONS

    OpenAIRE

    B.R.SRIDHAR,; S.RAMACHANDRA,; U.CHANDRASEKAR

    2011-01-01

    Nickel base super alloy Udimet 720 finds applications in gas turbine engine components like discs, shafts and blades. These components rotate at high speeds in a gas turbine engine and consequently experience both high cycle fatigue (HCF) and low cycle fatigue (LCF) due to dynamic loads and temperatures. Since residual stress affects both HCF and LCF properties, study of residual stress for varying surface conditions for this alloy assumes significance. Specimens extracted from a forging were...

  7. Mechanism of beneficial effect of tantalum in hot corrosion of nickel-base superalloys

    Science.gov (United States)

    Fryburg, G. C.; Stearns, C. A.; Kohl, F. J.

    1977-01-01

    X-ray diffraction and electron microprobe analyses were used to examine a prominent NaTaO3 pattern formed in a number of nickel-base superalloys. It is found that a beneficial effect of tantalum with respect to hot corrosion attack arises from the ability of Ta2O5 to tie up Na2O and prevent the formation of a molten Na2MoO4 phase.

  8. Simulation and experiments of ultrasonic propagation in nickel-based alloy weldments

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In order to obtain good understanding of complicated beam propagation behaviors in nickel-based alloy weldments, ray tracing simulation is established to predict the ultrasonic beam path in a special welded structure of dissimilar steels. Also experimental examinations are carried out to measure the ultrasonic beam paths in the weldment. Then comparisons of the modeling predictions with experimental results are presented to reveal the complicated beam propagation behaviors.

  9. Characterisation of an Advanced Nickel Based Superalloy Post Cold Work by Swaging

    Directory of Open Access Journals (Sweden)

    Martin R. Bache

    2016-03-01

    Full Text Available Cylindrical bars of the advanced nickel based superalloy RR1000 were subjected to swaging to induce approximately 30% cold work. Grain size analysis demonstrated a distinct modification to the microstructure whilst electron back scattered diffraction (EBSD measurements confirmed the evolution of a relatively strong <111> texture parallel with the longitudinal bar axis. Intragranular strain damage was identified. The effects of the swaging on bulk mechanical properties are illustrated across a range of test temperatures.

  10. Corrosion behavior of iron and nickel base alloys under solid oxide fuel cell exposure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ziomek-Moroz, M.; Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.

    2006-03-01

    Topography and phase composition of the scales formed on commercial ferritic stainless steels and experimental low CTE nickel-based alloys were studied in atmospheres simulating solid oxide fuel cell (SOFC) environments. The materials were studied under dual environment conditions with air on one side of the sample and carbon monoxide on the other side at 750°C. Surface characterization techniques, such as scanning electron microscopy and X-ray diffraction analysis were used in this study.

  11. Polyaniline-based nickel electrodes for electrochemical supercapacitors-Influence of Triton X-100

    Energy Technology Data Exchange (ETDEWEB)

    Girija, T.C.; Sangaranarayanan, M.V. [Department of Chemistry, Indian Institute of Technology, Madras 600 036 (India)

    2006-09-22

    The influence of Triton X-100 in enhancing the capacitance of polyaniline-based nickel electrodes is reported. Cyclic voltammetric experiments, galvanostatic charge-discharge studies and impedance analysis were carried out in order to investigate the applicability of the system as an electrochemical supercapacitor. A qualitative interpretation of the enhancement is provided. Fourier transform infrared (FTIR), X-ray diffraction and scanning electron microscopy techniques were employed for characterization of the electrode. (author)

  12. A concept for the EQ coating system for nickel-based superalloys

    Science.gov (United States)

    Kawagishi, K.; Sato, A.; Harada, H.

    2008-07-01

    Nickel-based single-crystal superalloys with high concentrations of refractory elements are prone to generate a diffusion layer called a secondary reaction zone (SRZ) beneath their bond coating during long exposure to high temperatures. The SRZ causes a reduction of the load-bearing cross section and it is detrimental to the creep properties of thin-walled turbine airfoils. In this study, a new bond coat system, “EQ coating,” which is thermodynamically stable and suppresses SRZ has been proposed. Diffusion couples of coating materials and substrate alloys were made and heat treated at 1,100°C for 300 h and 1,000 h. Cyclic oxidation examinations were carried out at 1,100°C in air and the oxidation properties of EQ coating materials were discussed. High-velocity frame-sprayed EQ coatings designed for second-generation nickel-based superalloys were deposited on fourth-and fifth-generation nickel-based superalloys, and the stability of the microstructure at the interface and creep property of the coating system were investigated.

  13. THE ROLE OF NIOBIUM IN NICKEL-BASED SUPERALLOYS AND CHARACTERIZATION OF PM ALLOY EP741NP

    Institute of Scientific and Technical Information of China (English)

    T. Carneiro; J. Radavich; D. Furrer

    2005-01-01

    The role of niobium in nickel-based superalloys is reviewed. The importance of niobium as a strengthener is discussed. New developments in nickel-based superalloys are also briefly mentioned, including some results that show improved resistance to sulfidation by niobium. Research results from a current program on the role of niobium in the Russian powder metallurgy alloy EP741NP are presented. Future research plans on the role of niobium in superalloys are also discussed.

  14. Solid phase extraction of ultra trace amounts of Nickel (II) using Schiff's base AImmobilized on SDS-coated Alumina

    International Nuclear Information System (INIS)

    The purpose of this research was introducing a new sorbent for preconcentration of nickel ion from aqueous sample solution. Sodium dodecy sulfate, as a surfactant, makes ad micelle on the surface of substrate, γ-alumina. This allows the metal complexing agent, Schiff's A, to be immobilized in to hydrocarbon cores of the ad micelles. This assemble, as a chelating sorbent, has made the separation and preconcentration of nickel ion possible. In the present work, a column of alumina modified with sodium dodecyl sulfate and Schiff's base A was prepared for the preconcentration of trace nickel from water samples for a flame atomic absorption spectroscopy determination under the optimized conditions. (p H=6.5 flow rate, 30 ml/min) nickel (II) was retained on the column. The nickel collected on the column was eluted with 5 ml of 1 M nitric acid. Recovery was greater than 98%. A concentration factor of 200 can be achieved by passing 1000 ml of sample through the column. The relative standard deviation (10 replicate analysis) at the 100 ng ml1 level for nickel was 2.4% and the corresponding limit of detection (based on 30) was 0.03 ngm1. The method was applied to the determination of nickel in wasted and mineral waters

  15. Study of alumina-trichite reinforcement of a nickel-based matric by means of powder metallurgy

    Science.gov (United States)

    Walder, A.; Hivert, A.

    1982-01-01

    Research was conducted on reinforcing nickel based matrices with alumina trichites by using powder metallurgy. Alumina trichites previously coated with nickel are magnetically aligned. The felt obtained is then sintered under a light pressure at a temperature just below the melting point of nickel. The halogenated atmosphere technique makes it possible to incorporate a large number of additive elements such as chromium, titanium, zirconium, tantalum, niobium, aluminum, etc. It does not appear that going from laboratory scale to a semi-industrial scale in production would create any major problems.

  16. Corrosion and mechanical property at high temperature of nickel based alloy for VHTR

    International Nuclear Information System (INIS)

    Using a very high temperature reactor (VHTR), it is conceptually and practically possible to generate highly efficient electricity and produce massive hydrogen among generation IV nuclear power plants. The structural material for an intermediate heat exchanger (IHX) is exposed to high temperature of up to 950 .deg. C. In this harsh environment, nickel-based alloys such as Alloy 617 and Haynes 230 are considered as promising candidate materials for IHX material owing to their excellent creep resistances at high temperature. However, high-temperature degradation cannot be avoided even for nickel-based alloy. Helium which inevitably includes impurities such as H2, CH4, H2O and CO is used as a coolant in a VHTR. Material degradation is aggravated by corrosion under an impure helium environment, which is one of the main obstacles to overcome for the application and successful long-term operation of a VHTR. A review of the thermodynamics indicates which reactions are available on the surface of the materials among oxidation, carburization and decarburization, but it does not give US the kinetic preference. This kinetic preference can induce localized corrosion, kinetic irreversibility and long-term material instability leading to material degradation. In addition to a long-term corrosion test under a VHTR coolant environment, the development of new alloys superior to commercial nickel-based alloy also give way to the successful establishment of a VHTR. Commercial nickel-based wrought alloy is strengthened by a solid solution and precipitation hardening mechanism in a wide temperature range of 500 to 900 .deg. C. The γ' significantly contributes to the strengthening by locking dislocation motion by an antiphase boundary at an intermediate temperature range of 700 to 800 .deg. C, but is no longer stable above this temperature range. However, the material for an IHX needs to fulfill the mechanical property requirements in a narrow and very high temperature range of 850 to

  17. Polymer nanocomposites based on polyamide 12 filled with nickel and copper nanoparticles

    Science.gov (United States)

    Shapoval, E. S.; Zuev, V. V.

    2014-05-01

    The method for producing nanoscale nickel particles (particle diameter 20-30 nm) protected from oxidation thin carbon shell (1-2 nm) was developed. The polymer nanocomposites based on PA 12 matrix filled with filled with 0.1 to 1 wt. % nickel nanoparticles were synthesized by in situ polymerization. The tensile properties of polymer composites (Young's modulus, ultimate strength) were increased on 15-20% compared to the neat polymer. Also this article reports the findings of an investigation of a synthetic route for a synthesis a size-controllable molecularly capped copper nanoparticles. At using copper nanoparticles as filler the mechanical properties became worse by about 5-10% as compared PA12. Thus, needs the search of optimal way to modification of PA 12 matrix with copper nanoparticles.

  18. Rare-earth oxides promoted nickel based catalysts for steam reforming

    International Nuclear Information System (INIS)

    Full text: The effect of ceria, samaria and praseodymia as promoters for nickel based catalysts for the steam reforming of methane has been studied. The catalysts, prepared by a two-step impregnation method, showed significant enhancement of activity for methane steam reforming. The activity increased linearly with increased loading of the rare-earth oxides. The positive effect of the rare-earth oxides on the steam reforming activity decreased as CeO2>Pr2O3>Sm2O3. The ceria-containing catalysts exhibited excellent anti-coking ability comparable to that of advanced commercial catalysts. This was explained in terms of the larger adsorption of water on the surface of ceria and the resulting relatively high rates of carbon gasification. The selectivity of the nickel-ceria catalysts to hydrogen and carbon dioxide production during methane steam re-forming was also significantly improved due to the increase of importance of the water gas shift reaction

  19. Functional nickel-based deposits synthesized by focused beam induced processing

    Science.gov (United States)

    Córdoba, R.; Barcones, B.; Roelfsema, E.; Verheijen, M. A.; Mulders, J. J. L.; Trompenaars, P. H. F.; Koopmans, B.

    2016-02-01

    Functional nanostructures fabricated by focused electron/ion beam induced processing (FEBIP/FIBIP) open a promising route for applications in nanoelectronics. Such developments rely on the exploration of new advanced materials. We report here the successful fabrication of nickel-based deposits by FEBIP/FIBIP using bis(methyl cyclopentadienyl)nickel as a precursor. In particular, binary compounds such as nickel oxide (NiO) are synthesized by using an in situ two-step process at room temperature. By this method, as-grown Ni deposits transform into homogeneous NiO deposits using focused electron beam irradiation under O2 flux. This procedure is effective in producing highly pure NiO deposits with resistivity of 2000 Ωcm and a polycrystalline structure with face-centred cubic lattice and grains of 5 nm. We demonstrate that systems based on NiO deposits displaying resistance switching and an exchange-bias effect could be grown by FEBIP using optimized parameters. Our results provide a breakthrough towards using these techniques for the fabrication of functional nanodevices.

  20. Elaboration et caractérisation d'alliages de type Ti-Nb-X (X = O, N pour des applications biomédicales Synthesis and characterisation of Ti-Nb-X (X = O, N alloys for biomedical application

    Directory of Open Access Journals (Sweden)

    Ramarolahy A.

    2013-11-01

    Full Text Available Dans cette étude, trois alliages de titane β-métastables de composition Ti-27Nb, Ti-24Nb-0.5N et Ti-24Nb-0.5O ont été élaborés par fusion. Ces trois alliages présentent des propriétés superélastiques lors des essais de traction. Des essais de traction in-situ sous rayonnement synchrotron nous ont permis de monter que cette superélasticité est due à une transformation martensitique réversible β → α” bien connue pour deux alliages alors que celui contenant de l'oxygène présente un comportement moins conventionnel. Les températures caractéristiques (MS, MF de la transformation martensitique β (austénite vers α” (martensite et celles (AS, AF de la transformation inverse α” vers β ont aussi été déterminées par des essais mécaniques dynamiques. Ces températures caractéristiques augmentent linéairement avec la contrainte externe et cette augmentation suit la relation de Clausius Clapeyron. Ti-Nb based alloys are well known to their good mechanical properties, shape memory effect, superelasticity, as well as good biocompatibility. Our study is focused on the improvement of their mechanical properties by adding alloying element such as oxygen or nitrogen. Superelasticity was drastically improved by addition of a few amount (0.5 at % of oxygen or nitrogen. Martensitic transformation between the β parent phase (austenite and α” product phase (martensite, responsible for the superelastic property, has been extensively studied by Dynamic Mechanical Analysis (DMA and in-situ tensile test under X-ray synchrotron diffraction.

  1. Examination of nickel alloys and welded joints made from nickel-based alloy. Challenge for ultrasonic testing

    International Nuclear Information System (INIS)

    Nickel alloys and in particular welds of nickel alloy provide a special challenge for ultrasonic testing. Increased scattering at the relatively large grains resulting in a reduction of the signal-to-noise ratio. In welds and cast materials added that form during solidification columnar grains which are oriented in the preferred direction depending on the cooling conditions. Thereby, the elastic anisotropy of the material makes macroscopically noticeable and affects the ultrasound propagation. Thus, in particular the detection of small defects and the distinction between reflections from imperfections and interfering signals like reflections at interfaces, backscattering from the grain structure or indications are significantly more difficult. This article shows a few examples of the challenges of simple components such as pipelines to the testing with ultrasound.

  2. Soudage homogène MIG de l'alliage d'aluminium 6061 MIG homogeneous welding of 6061 aluminium alloy

    OpenAIRE

    Benoit Alexandre; Paillard Pascal; Baudin Thierry; Mottin Jean-Baptiste

    2013-01-01

    Le soudage homogène (métal d'apport identique au métal de base) de l'alliage d'aluminium 6061 avec un procédé dit semi-automatique (MIG) n'a jamais été reporté jusqu'à maintenant dans la littérature. Nous montrons ici que l'utilisation d'un dérivé du procédé de soudage MIG, le MIG CMT (Cold Metal Transfer) permet d'obtenir des cordons de soudures sains (sans fissuration à chaud). De plus des traitements thermiques ont permis de retrouver partiellement ou de restaurer totalement les propriétés...

  3. Nickel laterites, origin and climate

    OpenAIRE

    Thorne, Robert L.

    2011-01-01

    Nickel laterites account for ?40 % of global nickel production and contain 60 % of the world's total land based nickel resources. Despite the importance of these deposits published studies, detailing their morphology and formation processes are relatively few and the interaction of variables responsible for the formation of different nickel laterites are poorly understood. To better understand the process of nickel laterite formation, the Caldag and Bitincke paleodeposits were studied and...

  4. Diffusion parameters of the γ/γ' phase boundary in nickel base alloy

    International Nuclear Information System (INIS)

    The description and results of investigations into a mass-spectrometer for the study of fast gas phase processes are presented. The mass spectrometer consists of a system of preparing a gaseous mixture, a reactor, a system of sample introduction from a reactor in the ionization region; the system of differential pumping-out; ion sources with the ionization with an electron shock; a 180-degree magnetic analyzer; ionoelectron optic converter, the registration system. The fast action of the device is 10-5 s. The maximum pressure in the reactor is 1.3x104 Pa in the range of ionization and 1.3x10-4 Pa - in the analyzer. The distance between the intake top to the beginning of the Diffusion coefficients of 63Ni radioactive isotope on the boundaries of γ/γ' phases in a heat-resisting nickel base alloy, are measured. The diagram of the method of measuring the diffusion coefficients, is presented. Using the methods of autoradiography, 63Ni distribution in the grain volume is investigated. It is shown that inhomogeneity of grain distribution is connected with increased diffusion permeability of γ/γ' phase boundaries. The temperature dependence of nickel diffusion coefficient in the volume and γ/γ' phase boundaries, is given. It is noted that in the range of 700-1000 deg C nickel diffusion coefficients in γ/γ' phase boundaries are 2-3 orders higher than the value of diffusion coefficient in the phase volume. The activation energy of nickel diffusion in boundaries of γ/γ' phases E and preexponential multiplier D01:E1=70000 cal/mol and D01=5x102 cm2/s, are determined according to the temperature dependence of diffusion coefficients

  5. Combined thermodynamic study of nickel-base alloys. Progress report

    International Nuclear Information System (INIS)

    Achievements during this period are the following: (1) initiation of a high-temperature study of the Ni-Ta system using the galvanic cell technique, (2) emf study of high-temperature thermodynamics in the Ni-Mo system, (3) measured heat capacity data on ordered and disordered Ni4Mo, (4) heat capacities of Ni and disordered Ni3Fe, and (5) computer correlation of thermodynamic and phase diagram data in binary Ni-base alloys

  6. Interactions Hydrogène - Plasticité dans le Nickel et ses Alliages

    OpenAIRE

    Girardin, Gouenou

    2004-01-01

    Nous évaluons les différentes contributions des interactions hydrogène-dislocations sur la plasticité de matériaux cfc hydrogènes afin d'alimenter des modèles prédictifs d'endommagement par corrosion sous contrainte. Par des essais de vieillissement, nous quantifions la contribution positive a la contrainte d'écoulement du traînage des atmosphères de solutés par les dislocations. Nous démontrons le rôle du transport de l'hydrogène par les dislocations dans le mécanisme de fragilisation. Nous ...

  7. Oxidation induced phase transformations and lifetime limits of chromia forming nickel base alloy 625

    OpenAIRE

    Chyrkin, Anton

    2011-01-01

    For its high creep resistance the commercial nickel-base alloy 625 relies on solid solution strengthening in combination with precipitation hardening by formation of delta-Ni3Nb and (Ni,Mo,Si)6C precipitates during high-temperature service. In oxidizing environments the alloy forms a slow growing, continuous chromia layer on the material surface which protects the alloy against rapid oxidation attack. The growth of the chromia base oxide scale results during exposure at 900–1000°C in oxidatio...

  8. Numerical modelling of precipitation of topologically close-packed phases in nickel-base superalloys

    International Nuclear Information System (INIS)

    A new mesoscale model was developed to understand the precipitation sequence of topologically close-packed (TCP) phases in single-crystal nickel-base superalloys. Nucleation and growth phenomena are described in detail. The model allows the multicomponent, multiphase and multiparticle calculation of TCP phase volume fractions and size distributions from supersaturated solid solution to thermodynamic equilibrium. It is based on the numerical Kampmann-Wagner method and applies CALPHAD (ThermoCalc) and DICTRA methodology for thermodynamics and diffusion. The capabilities of the simulations are demonstrated by the prediction of the size distributions of TCP phases and comparison with experimental data.

  9. Numerical modelling of precipitation of topologically close-packed phases in nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Rettig, R., E-mail: ralf.rettig@ww.uni-erlangen.de [Institute of Science and Technology of Metals, Department of Materials Science and Engineering, University of Erlangen, Martensstr. 5, 91058 Erlangen (Germany); Singer, R.F. [Institute of Science and Technology of Metals, Department of Materials Science and Engineering, University of Erlangen, Martensstr. 5, 91058 Erlangen (Germany)

    2011-01-15

    A new mesoscale model was developed to understand the precipitation sequence of topologically close-packed (TCP) phases in single-crystal nickel-base superalloys. Nucleation and growth phenomena are described in detail. The model allows the multicomponent, multiphase and multiparticle calculation of TCP phase volume fractions and size distributions from supersaturated solid solution to thermodynamic equilibrium. It is based on the numerical Kampmann-Wagner method and applies CALPHAD (ThermoCalc) and DICTRA methodology for thermodynamics and diffusion. The capabilities of the simulations are demonstrated by the prediction of the size distributions of TCP phases and comparison with experimental data.

  10. Potassium Sodium Niobate-Based Lead-Free Piezoelectric Multilayer Ceramics Co-Fired with Nickel Electrodes

    Directory of Open Access Journals (Sweden)

    Shinichiro Kawada

    2015-11-01

    Full Text Available Although lead-free piezoelectric ceramics have been extensively studied, many problems must still be overcome before they are suitable for practical use. One of the main problems is fabricating a multilayer structure, and one solution attracting growing interest is the use of lead-free multilayer piezoelectric ceramics. The paper reviews work that has been done by the authors on lead-free alkali niobate-based multilayer piezoelectric ceramics co-fired with nickel inner electrodes. Nickel inner electrodes have many advantages, such as high electromigration resistance, high interfacial strength with ceramics, and greater cost effectiveness than silver palladium inner electrodes. However, widely used lead zirconate titanate-based ceramics cannot be co-fired with nickel inner electrodes, and silver palladium inner electrodes are usually used for lead zirconate titanate-based piezoelectric ceramics. A possible alternative is lead-free ceramics co-fired with nickel inner electrodes. We have thus been developing lead-free alkali niobate-based multilayer ceramics co-fired with nickel inner electrodes. The normalized electric-field-induced thickness strain (Smax/Emax of a representative alkali niobate-based multilayer ceramic structure with nickel inner electrodes was 360 pm/V, where Smax denotes the maximum strain and Emax denotes the maximum electric field. This value is about half that for the lead zirconate titanate-based ceramics that are widely used. However, a comparable value can be obtained by stacking more ceramic layers with smaller thicknesses. In the paper, the compositional design and process used to co-fire lead-free ceramics with nickel inner electrodes are introduced, and their piezoelectric properties and reliabilities are shown. Recent advances are introduced, and future development is discussed.

  11. Isothermal Low Cycle Fatigue of Uncoated and Coated Nickel-Base Superalloys

    International Nuclear Information System (INIS)

    High strength nickel-base superalloys have been used in turbine blades for many years because of their superior performance at high temperatures. However, the superalloys have limited oxidation and corrosion resistance and to solve this problem, protective coatings are deposited on the surface of the superalloys. The positive effect of coatings is based on protecting the surface zone in contact with hot gas atmosphere with elements like aluminium, chromium, which form a thermodynamically stable oxide layer that acts as a diffusion barrier to slow down the reaction between the substrate material and the aggressive environment. There are also other degradation mechanisms that affect nickel-base superalloys such as aging of microstructure, fatigue and creep. Long-term aging in metallic coating results in the changes of mechanical properties due to the significant interdiffusion of the main alloying elements between substrate and coatings. However, application of the coatings has mechanical side effects, the significance of which is not yet fully investigated. This work covers a study on the fatigue behaviour of a polycrystalline, IN792. and two single crystal nickel-base superalloys, CMSX-4 and SCB, coated with three different coatings. an overlay coating AMDRY997, a platinum aluminide modified diffusion coating RT22 and an innovative coating with an interdiffusion harrier of NiW called IC1, under low cycle fatigue loading conditions. Both low cycle fatigue properties, cyclic strain and stress response and fracture behaviour of the uncoated, coated and long-term aged coated specimens are presented. The main conclusions are that at 500 deg C the presence of the coatings have, in most cases, reduced the fatigue lives of the nickel-base substrates while at 900 deg C the coatings do improve the fatigue lives of the superalloys except RT22 coated on some superalloys and under certain test conditions. The reduction of the fatigue life at 500 deg C can be related to early

  12. Morphological evolution of γ precipitates in a nickel-based superalloy during various solution treatments

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The morphological evolution of the γ' phase in nickel-based superalloy жc6y during various solution heat treatments was investigated. The significant changes of the γ' precipitates were observed in the solution-treated samples. The coarsening and dissolution of γ' phase simulta-neously occurred at intermediate temperatures. In some areas, the primary precipitates became blunt and the adjacent ones were intercon-nected with each other via a diffuse neck, indicating a coarsening process of the primary γ' popu...

  13. Effect of cold work on initiation stage crack growth rate of nickel based alloys

    International Nuclear Information System (INIS)

    To investigate the effect of cold work on initiation stage crack growth rates of nickel based alloy, initiation stage crack growth rates were measured for simulated PWR primary water conditions using flat type specimens which were prepared from three different heats of alloy 600 and then 20 and 40% cold worked. Almost all data showed the stress had an increasing linear dependency on crack growth rate ; however there was some scattering of data and some materials showed a different tendency. Since yield strength was increased by cold work, for the same stress, the initiation stage crack growth rates were restrained or were not changed significantly by cold work. (author)

  14. SOLIDIFICATION OF NICKEL-BASED SINGLE CRYSTAL SUPERALLOY BY ELECTRIC FIELD

    Institute of Scientific and Technical Information of China (English)

    Y.S. Yang; X.H. Feng; G.F. Cheng; Y.J. Li; Z.Q. Hu

    2005-01-01

    The crystal growth of a nickel-based single crystal superalloy DD3 was researched via controlled directional solidification under the action of a DC electric field. The cellular or dendrite spacing of the single crystal superalloy is refined and microsegregation of alloying elements Al,Ti, Mo and W, is reduced by the electric field. The electric field decreases the interface stability and reduces the critical growth rate of the cellular-dendritic translation because of Thomson effect and Joule heating. The precipitation of the γ' phase is more uniform and the size of the γ'phase is smaller with the electric field than that without the electric field.

  15. XPS analysis of zinc injection effects on general corrosion of nickel-base alloy 690

    International Nuclear Information System (INIS)

    The effects of zinc addition on behaviors of general corrosion behaviors of nickel-base alloy 690 were investigated in simulated PWR primary water. After exposed in solutions with zinc concentration of o and 50 ppb for 1500 h, oxide films developed on surface of specimens were analyzed by using XPS. The result shows that Zn partly replaces Ni and Fe in NiCr2O4 and FeCr2O4 in the inner oxide layer and forms ZnCr2O4. (authors)

  16. Analyze the test methods for intergranular corrosion-resistance of nickel-based alloys 690

    International Nuclear Information System (INIS)

    The corrosion resistance effective of steam generator heat tubing in PWR nuclear power build highly demanding and direct impact on the reliability of the nuclear power unit to the technical performance and safety. Nickel-based Alloy 690 is the best material for nuclear SG heat tubing. Heat of the damage is caused by various types of corrosion, mainly is intergranular corrosion and stress corrosion cracking. Tests to verify the stability of heat transfer performance and application reliability. Analyze the chemical and electrochemical immersion (EPR) corrosion methods to provide the basic theory for experimental verification of the stability and engineering applications reliability of heat transfer. (authors)

  17. Precipitate Contribution to the Acoustic Nonlinearity in Nickel-Based Superalloy

    Institute of Scientific and Technical Information of China (English)

    Chung-Seok KIM; Cliff J.LISSENDEN

    2009-01-01

    The influence of γ' precipitate on the acoustic nonlinearity is investigated for a nickel-based superalloy,which is subjected to creep deformation.During creep deformation,the cuboidal γ' precipitate is preferentially coarsened in a direction perpendicular to the applied stress axis.The length and shape factor of the γ' precipitate increase with creep time.The increase of relative acoustic nonlinearity with increasing fraction of creep life is discussed in relation to the rafting of γ' precipitate,which is closely related to the scattering and distortion of the acoustic wave.

  18. Investigations of carbon diffusion and carbide formation in nickel-based alloys

    International Nuclear Information System (INIS)

    The present thesis describes the carburization behaviour of nickel based alloys in heavily carburizing environments. The mechanisms of carbon diffusion and carbide precipitation in NiCr alloys with and without ternary additions of iron, cobalt or molybdenum have been investigated. Using the results of carburization experiments, a mathematical model which describes carbon diffusion and carbide formation, was developed. The simulation of the carburization process was carried out by an iterative calculation of the local thermodynamic equilibrium in the alloy. An accurate description of the carbon profiles as a function of time became possible by using a finite-difference calculation. (orig.)

  19. Ion irradiation induced disappearance of dislocations in a nickel-based alloy

    Science.gov (United States)

    Chen, H. C.; Li, D. H.; Lui, R. D.; Huang, H. F.; Li, J. J.; Lei, G. H.; Huang, Q.; Bao, L. M.; Yan, L.; Zhou, X. T.; Zhu, Z. Y.

    2016-06-01

    Under Xe ion irradiation, the microstructural evolution of a nickel based alloy, Hastelloy N (US N10003), was studied. The intrinsic dislocations are decorated with irradiation induced interstitial loops and/or clusters. Moreover, the intrinsic dislocations density reduces as the irradiation damage increases. The disappearance of the intrinsic dislocations is ascribed to the dislocations climb to the free surface by the absorption of interstitials under the ion irradiation. Moreover, the in situ annealing experiment reveals that the small interstitial loops and/or clusters induced by the ion irradiation are stable below 600 °C.

  20. Highly efficient electrochemical hydrogen evolution based on nickel diselenide nanowall film

    Science.gov (United States)

    Tang, Chun; Xie, Lisi; Sun, Xuping; Asiri, Abdullah M.; He, Yuquan

    2016-05-01

    In this letter, we report on hydrothermal growth of nickel diselenide nanowall film on carbon cloth (NiSe2 NW/CC) through topotactic transformation from a Ni(OH)2 precursor based on anion exchange reactions. When tested as an integrated 3D hydrogen-evolving cathode in strongly acidic media, NiSe2 NW/CC exhibits outstanding catalytic activity superior to its powder counterpart and strong long-term durability. It displays 10 and 100 mA cm‑2 at overpotentials of 145 and 183 mV, respectively, with its catalytic activity being retained for 40 h.

  1. Characterisation of oxidation and oxide layers of nickel-base superalloys at high temperature

    International Nuclear Information System (INIS)

    Nickel-base superalloys are considered as materials for several key components in a very high temperature gas-cooled reactor. The high temperature properties of those alloys such as creep and creep-fatigue strongly depend on characteristics of surface oxide layer. Therefore, in the present study, the oxidation behaviours of several nickel-base superalloys such as Alloy 617, Haynes 214 and Haynes 230 were investigated at 900 deg C and 1100 deg C in air and helium environments. Also, to understand the surface oxidation process, oxide layers were analysed by XRD, XPS and EDX. The results showed that the oxidation behaviours were strongly depended on the stability of the surface oxides. In case of Alloy 617 and Haynes 230, Cr2O3 was dominantly formed on the surface, and the weight increased significantly due to oxidation at the initial stage, but followed by a decrease due to volatilization of Cr2O3 layer, especially at 1100 deg C. Also, the partitioning of other minor alloying elements into the surface layer was observed but disappeared after long-term exposure. On the other hand, after forming transient phases like NiO and NiCr2O4, stable α-Al2O3 layer was dominantly formed later on the surface of Haynes 214, and the weight gain eventually reached to plateau. Based on the weight loss measurement and XRD analysis, the oxidation resistance of the alloys was discussed. (authors)

  2. Dendritic growth and crystalline quality of nickel-base single grains

    Science.gov (United States)

    Siredey, Nathalie; Boufoussi, M'Bareck; Denis, Sabine; Lacaze, Jacques

    1993-05-01

    It is a usual observation that subgrains exist in nickel-base single grain components solidified by the lost wax process. The associated misorientations are generally small, but they can eventually lead to casting defects in the case of highly complex mold shapes. This work presents an attempt to relate the formation of subgrain boundaries with the development of the dendritic solidification microstructure. Experimental investigations have been undertaken on cast components made of AM1 nickel-base superalloy designed for high temperature turbine blades. Single grains were obtained by means of a grain selector at the bottom of each part. Metallographic observations have been made to characterize the dendritic array, together with gamma diffraction to measure the crystalline quality of the material and X-ray topography for mapping of misorientations on a dendritic scale. Small misorientations between dendrite stems have been found at the upper end of the selector which lead to the formation of subgrains. Moreover, during the growth process, the total mosaicity of the material increases, firstly as a consequence of an increase in the misorientations between subgrains, and secondly because of a decrease of the internal quality of each subgrain. It is proposed that misorientations are due to thermomechanical stresses which build up during λ' precipitation at temperatures slightly below the solidus temperature of the alloy.

  3. Dendritic growth and crystalline quality of nickel-base single grains

    Energy Technology Data Exchange (ETDEWEB)

    Siredey, N. (Lab. de Science et Genie des Materiaux Metalliques, Ecole des Mines, 54 - Nancy (France)); Boufoussi, M.B. (Lab. de Science et Genie des Materiaux Metalliques, Ecole des Mines, 54 - Nancy (France)); Denis, S. (Lab. de Science et Genie des Materiaux Metalliques, Ecole des Mines, 54 - Nancy (France)); Lacaze, J. (Lab. de Science et Genie des Materiaux Metalliques, Ecole des Mines, 54 - Nancy (France))

    1993-05-01

    It is a usual observation that subgrains exist in nickel-base single grain components solidified by the lost wax process. The association misorientations are generally small, but they can eventually lead to casting defects in the case of highly complex mold shapes. This work presents and attempt to relate the formation of subgrain boundaries with the development of the dendritic solidification microstructure. Experimental investigations have been undertaken on cast components made of AM1 nickel-base superalloy designed for high temperature turbine blades. Single grains were obtained by means of a grain selector at the bottom of each part. Metallographic observations have been made to characterize the dendritic array, together with gamma diffraction to measure the crystalline quality of the material and X-ray topography for mapping of misorientations on a dendritic scale. Small misorientations between dendrite stems have been found at the upper end of the selector which lead to the formation of subgrains. Moreover, during the growth process, the total mosaicity of the material increases, firstly as a consequence of an increase in the misorientations between subgrains, and secondly because of the decrease of the internal quality of each subgrain. It is proposed that misorientations are due to thermomechanical stresses which build up during [gamma]' precipitation at temperatures slightly below the solidus temperature of the alloy. (orig.)

  4. Synergistic effect of rhenium and ruthenium in nickel-based single-crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Yu, X.X. [Department of Physics, Tsinghua University, Beijing 100084 (China); Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Wang, C.Y., E-mail: cywang@mail.tsinghua.edu.cn [Department of Physics, Tsinghua University, Beijing 100084 (China); Central Iron and Steel Research Institute, Beijing 100081 (China); Zhang, X.N. [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Yan, P. [Central Iron and Steel Research Institute, Beijing 100081 (China); Zhang, Z., E-mail: zezhang@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2014-01-05

    Highlights: • Re and Ru synergistic effects in nickel-based superalloys are investigated. • The Al site occupation of Re atom in the γ′ phase is observed directly. • The addition of Ru results in the repartitioning of Re to γ phase. -- Abstract: The microstructures of ternary Ni–Al–Re and quaternary Ni–Al–Re–Ru single-crystal alloys were investigated at atomic and electronic levels to clarify the synergistic effect of Re and Ru in nickel-based single-crystal superalloys. In the Ni–Al–Re alloy, it was directly observed that Re atom occupied the Al site of γ′ phase. In the Ni–Al–Re–Ru alloy, the mechanisms of Re repartition between γ and γ′ phases were proposed. In the dendritic cores, high concentrations of Re exceeded the solubility limit of γ′ phase and partitioned to γ phase, which led to the homogenization. In the interdendritic regions, Ru resulted in the repartitioning of Re to γ phase which was proved by transmission electron microscopy and first-principles calculations.

  5. Numerical modeling of microstructure evolution during laser additive manufacturing of a nickel-based superalloy

    International Nuclear Information System (INIS)

    A multi-scale model that combines the finite element method and stochastic analysis is developed to simulate the evolution of the microstructure of an Nb-bearing nickel-based superalloy during laser additive manufacturing solidification. Through the use of this model, the nucleation and growth of dendrites, the segregation of niobium (Nb) and the formation of Laves phase particles during the solidification are investigated to provide the relationship between the solidification conditions and the resultant microstructure, especially in the morphology of Laves phase particles. The study shows that small equiaxed dendrite arm spacing under a high cooling rate and low temperature gradient to growth rate (G/R) ratio is beneficial for forming discrete Laves phase particles. In contrast, large columnar dendrite arm spacing under a low cooling rate and high G/R ratio tends to produce continuously distributed coarse Laves phase particles, which are known to be detrimental to mechanical properties. In addition, the improvement of hot cracking resistance by controlling the morphology of Laves phase particles is discussed by analyzing the cracking pattern and microstructure in the laser deposited material. This work provides valuable understanding of solidification microstructure development in Nb-bearing nickel-based superalloys, like IN 718, during laser additive manufacturing and constitutes a fundamental basis for controlling the microstructure to minimize the formation of deleterious Laves phase particles

  6. Corrosion testing of nickel base superalloys and coatings with molten sulphates at 9000C

    International Nuclear Information System (INIS)

    The work refers to the application of electrochemical testing procedures on the corrosion properties of different commercial nickel base superalloys. This included the following alloys: IN 738 LC, IN 939, Nimonic 81, Nimonic 90, IN 713 LC, IN 792 5 A, IN 100, IN 853, IN 617, Nimonic 105, B 1925, N 33 Hastelloy X, Mar M 246, Mar M 421, Mar M 432, IN 671, Nicrofer 7520, IN 800. Beside a short galvanostatic test with subsequent metallographic measurement of the resulting corrosion damage, potential/current density curves and potential/time curves were taken from selected alloys. In all cases the corrodent was a melt of (Nasub(0.9), Ksub(0.1))2SO4 at 9000C. Thermogravimetric tests were run for comparison of three alloys (IN 738 LC, IN 939, IN 713 LC). The existence of ranges of passivation and induction periods could be established. The galvanostatic corrosion test was also applied to the testing of two different coatings (S 57 and LDC2) on IN 738 LC and Mar M246 or IN 100. In all cases scale compounds and intermetallics in coatings were analyzed by XRD. The electrochemical test for nickel base superalloys is a useful tool for a quick ranking of alloys. For the assessment of coatings more work will be necessary. (orig.)

  7. Solid particle erosion of steels and nickel based alloys candidates for USC steam turbine blading

    Energy Technology Data Exchange (ETDEWEB)

    Cernuschi, Federico; Guardamagna, Cristina; Lorenzoni, Lorenzo [ERSE SpA, Milan (Italy); Robba, Davide [CESI, Milan (Italy)

    2010-07-01

    The main objective of COST536 Action is to develop highly efficient steam power plant with low emissions, from innovative alloy development to validation of component integrity. In this perspective, to improve the operating efficiency, materials capable of withstanding higher operating temperatures are required. For the manufacturing of components for steam power plants with higher efficiency steels and nickel-based alloys with improved oxidation resistance and creep strength at temperature as high as 650 C - 700 C have to be developed. Candidate alloys for manufacturing high pressure steam turbine diaphragms, buckets, radial seals and control valves should exhibit, among other properties, a good resistance at the erosion phenomena induced by hard solid particles. Ferric oxide (magnetite) scales cause SPE by exfoliating from boiler tubes and steam pipes (mainly super-heaters and re-heaters) and being transported within the steam flow to the turbine. In order to comparatively study the erosion behaviour of different materials in relatively short times, an accelerated experimental simulation of the erosion phenomena must be carried out. Among different techniques to induce erosion on material targets, the use of an air jet tester is well recognised to be one of the most valid and reliable. In this work the results of SPE comparative tests performed at high temperatures (550 C, 600 C and 650 C) at different impaction angles on some steels and nickel based alloys samples are reported. (orig.)

  8. Prediction of recrystallisation in single crystal nickel-based superalloys during investment casting

    Directory of Open Access Journals (Sweden)

    Panwisawas Chinnapat

    2014-01-01

    Full Text Available Production of gas turbines for jet propulsion and power generation requires the manufacture of turbine blades from single crystal nickel-based superalloys, most typically using investment casting. During the necessary subsequent solution heat treatment, the formation of recrystallised grains can occur. The introduction of grain boundaries into a single crystal component is potentially detrimental to performance, and therefore manufacturing processes and/or component geometries should be designed to prevent their occurrence. If the boundaries have very low strength, they can degrade the creep and fatigue properties. The root cause for recrystallisation is microscale plasticity caused by differential thermal contraction of metal, mould and core; when the plastic deformation is sufficiently large, recrystallisation takes place. In this work, numerical and thermo-mechanical modelling is carried out, with the aim of establishing computational methods by which recrystallisation during the heat treatment of single crystal nickel-based superalloys can be predicted and prevented prior to their occurrence. Elasto-plastic law is used to predict the plastic strain necessary for recrystallisation. The modelling result shows that recrystallisation is most likely to occur following 1.5–2.5% plastic strain applied at temperatures between 1000 ∘C and 1300 ∘C; this is validated with tensile tests at these elevated temperatures. This emphasises that high temperature deformation is more damaging than low temperature deformation.

  9. Influence of Ta content on hot corrosion behaviour of a directionally solidified nickel base superalloy

    International Nuclear Information System (INIS)

    Highlights: • Three nickel-base superalloys containing different Ta content were subjected to Na2SO4-induced hot corrosion. • Ta improved the hot corrosion resistance. • Ta decreased the diffusion rate of alloying elements. • Ta promoted the formation of (Cr, Ti)TaO4 layer. - Abstract: Hot corrosion behaviour of a directionally solidified nickel base superalloy with different tantalum (Ta) addition in fused sodium sulphate (Na2SO4) under an oxidizing atmosphere at 900 °C has been studied. It was shown that the hot corrosion resistance was improved by increasing of Ta content. The hot corrosion kinetics of the alloy with lower Ta content deviated from parabolic law after 60 h corrosion test, whereas the corrosion kinetics of the alloy with high Ta content followed the parabolic law before 60 h and with less mass change afterwards. A detailed microstructure study using scanning electron microscopy (SEM) equipped with an energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD) was performed to investigate the corrosion products and mechanisms. The beneficial effect of Ta was found to be resulted from a Ta-enriched (Cr, Ti)TaO4 layer inside the corrosion scale, which led to the retarding of the element diffusion so as to decrease the hot corrosion kinetics

  10. Studies on nickel base superalloys for nuclear high level waste storage application

    International Nuclear Information System (INIS)

    Traditional austenitic stainless steels like 304L are widely used in the nuclear industries for waste storage but they are susceptible to sensitization in the welded zones and also suffer from pitting corrosion in chloride containing medium. In order to minimize these problems austenitic nickel base alloys stand as an alternative due to its better corrosion resistance thermal conductivity and good metallurgical properties. In the present investigation, the corrosion behavior and surface investigation of three nickel based superalloys (Alloy 600, Alloy 690 and Alloy 693) are carried out in as-received and heat treated condition, in simulated nuclear high level waste medium. Electrochemical studies were carried out in 3M HNO3 containing simulated high level waste, using potentiodynamic anodic polarization and electrochemical impedance spectroscopy technique. In order to investigate the passive film formed under simulated high level waste medium, X-ray photoelectron spectroscopy (XPS) study was carried out. The passive film was found to consist of a mixed oxide of Ni-Cr-Fe, for the Alloy 690 and Alloy 693 in simulated high level waste whereas for Alloy 600 it was only oxides of Cr. In all the conditions, Alloy 690 was found to possess superior corrosion resistance compared to Alloy, followed by Alloy 600 in simulated high level waste medium. (author)

  11. Optical modeling of nickel-base alloys oxidized in pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Clair, A. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon cedex (France); Foucault, M.; Calonne, O. [Areva ANP, Centre Technique Departement Corrosion-Chimie, 30 Bd de l' industrie, BP 181, 71205 Le Creusot (France); Finot, E., E-mail: Eric.Finot@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon cedex (France)

    2012-10-01

    The knowledge of the aging process involved in the primary water of pressurized water reactor entails investigating a mixed growth mechanism in the corrosion of nickel-base alloys. A mixed growth induces an anionic inner oxide and a cationic diffusion parallel to a dissolution-precipitation process forms the outer zone. The in situ monitoring of the oxidation kinetics requires the modeling of the oxide layer stratification with the full knowledge of the optical constants related to each component. Here, we report the dielectric constants of the alloys 600 and 690 measured by spectroscopic ellipsometry and fitted to a Drude-Lorentz model. A robust optical stratification model was determined using focused ion beam cross-section of thin foils examined by transmission electron microscopy. Dielectric constants of the inner oxide layer depleted in chromium were assimilated to those of the nickel thin film. The optical constants of both the spinels and extern layer were determined. - Highlights: Black-Right-Pointing-Pointer Spectroscopic ellipsometry of Ni-base alloy oxidation in pressurized water reactor Black-Right-Pointing-Pointer Measurements of the dielectric constants of the alloys Black-Right-Pointing-Pointer Optical simulation of the mixed oxidation process using a three stack model Black-Right-Pointing-Pointer Scattered crystallites cationic outer layer; linear Ni-gradient bottom layer Black-Right-Pointing-Pointer Determination of the refractive index of the spinel and the Cr{sub 2}O{sub 3} layers.

  12. Straining electrode behavior and corrosion resistance of nickel base alloys in high temperature acidic solution

    International Nuclear Information System (INIS)

    Repassivation behavior and IGA resistance of nickel base alloys containing 0∼30 wt% chromium was investigated in high temperature acid sulfate solution. (1) The repassivation rate was increased with increasing chromium content. And so the amounts of charge caused by the metal dissolution were decreased with increasing chromium content. (2) Mill-annealed Alloy 600 suffered IGA at low pH environment below about 3.5 at the fixed potentials above the corrosion potential in 10%Na2SO4+H2SO4 solution at 598K. On the other hand, thermally-treated Alloy 690 was hard to occur IGA at low pH environments which mill-annealed Alloy 600 occurred IGA. (3) It was considered that the reason, why nickel base alloys containing high chromium content such as Alloy 690 (60%Ni-30%Cr-10%Fe) had high IGA/SCC resistance in high temperature acidic solution containing sulfate ion, is due to both the promotion of the repassivation and the suppression of the film dissolution by the formation of the dense chromium oxide film

  13. Modeling of self-controlling hyperthermia based on nickel alloy ferrofluids: Proposition of new nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Delavari, H. Hamid, E-mail: Hamid.delavari@gmail.com [Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Azadi Avenue, 145888-9694 Tehran (Iran, Islamic Republic of); Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden); Madaah Hosseini, Hamid R. [Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Azadi Avenue, 145888-9694 Tehran (Iran, Islamic Republic of); Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, 145888-9694 Tehran (Iran, Islamic Republic of); Wolff, Max, E-mail: Max.wolff@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden)

    2013-06-15

    In order to provide sufficient heat without overheating healthy tissue in magnetic fluid hyperthermia (MFH), a careful design of the magnetic properties of nanoparticles is essential. We perform a systematic calculation of magnetic properties of Ni-alloy nanoparticles. Stoner–Wohlfarth model based theories (SWMBTs) are considered and the linear response theory (LRT) is used to extract the hysteresis loop of nickel alloy nanoparticles in alternating magnetic fields. It is demonstrated that in the safe range of magnetic field intensity and frequency the LRT cannot be used for the calculation of the area in the hysteresis for magnetic fields relevant for hyperthermia. The best composition and particle size for self-controlling hyperthermia with nickel alloys is determined based on SWMBTs. It is concluded that Ni–V and Ni–Zn are good candidates for self-controlling hyperthermia. - Highlights: ► Systematic calculation of magnetic properties of Ni-alloy NPs with composition has been performed. ► Optimum composition and particle size for self-controlling hyperthermia (SCH) have been determined. ► Ni–V and Ni–Zn nanoparticles are more appropriate candidates for SCH.

  14. Investigation of the isothermal precipitation behaviour of nickel-base alloys using electrochemical phase extraction

    International Nuclear Information System (INIS)

    Electrochemical phase extraction methods have been developed empirically for the selective separation of the precipitates in metallic materials. A detailed description of the process has been undertaken to allow optimization for various nickel-base alloys. For this part of the investigation, 16 model alloys were prepared as test electrodes and the electrolyte composition was varied over a wide range. The results enabled a series of effects to be explained on the basis of electrochemical data. The large number of test parameters limited the scope of the preliminary experiments and the range of model alloys used. In the nickel-base alloys, titanium carbo-nitride and primary M6C precipitates were identified. During isothermal ageing, M23C6 (except in Alloy KSN), Ni3Al (in INCONEL 617), Laves phases (in Hastelloy X and INCONEL 617), M12C (in HASTELLOY X and INCONEL 617) and α-tungsten (in the tungsten-containing alloys) were precipitated. The precipitation behaviour changed in the alloys investigated from intracrystalline to intercrystalline with increasing ageing temperature. The intracrystalline secondary precipitations affect the microhardness, structure and the solid-solution lattice. (orig.)

  15. Microstructure of the Nickel-Base Superalloy CMSX-4 Fabricated by Selective Electron Beam Melting

    Science.gov (United States)

    Ramsperger, Markus; Singer, Robert F.; Körner, Carolin

    2016-03-01

    Powder bed-based additive manufacturing (AM) processes are characterized by very high-temperature gradients and solidification rates. These conditions lead to microstructures orders of magnitude smaller than in conventional casting processes. Especially in the field of high performance alloys, like nickel-base superalloys, this opens new opportunities for homogenization and alloy development. Nevertheless, the high susceptibility to cracking of precipitation-hardenable superalloys is a challenge for AM. In this study, electron beam-based AM is used to fabricate samples from gas-atomized pre-alloyed CMSX-4 powder. The influence of the processing strategy on crack formation is investigated. The samples are characterized by optical and SEM microscopy and analyzed by microprobe analysis. Differential scanning calorimetry is used to demonstrate the effect of the fine microstructure on characteristic temperatures. In addition, in situ heat treatment effects are investigated.

  16. Embrittlement of nickel-, cobalt-, and iron-base superalloys by exposure to hydrogen

    Science.gov (United States)

    Gray, H. R.

    1975-01-01

    Five nickel-base alloys (Inconel 718, Udimet 700, Rene 41, Hastelloy X, and TD-NiCr), one cobalt-base alloy (L-605), and an iron-base alloy (A-286) were exposed in hydrogen at 0.1 MN/sq m (15 psi) at several temperatures in the range from 430 to 980 C for as long as 1000 hours. These alloys were embrittled to varying degrees by such exposures in hydrogen. Embrittlement was found to be: (1) sensitive to strain rate, (2) reversible, (3) caused by large concentrations of absorbed hydrogen, and (4) not associated with any detectable microstructural changes in the alloys. These observations are consistent with a mechanism of internal reversible hydrogen embrittlement.

  17. Thermodynamic Considerations of Contamination by Alloying Elements of Remelted End-of-Life Nickel- and Cobalt-Based Superalloys

    Science.gov (United States)

    Lu, Xin; Matsubae, Kazuyo; Nakajima, Kenichi; Nakamura, Shinichiro; Nagasaka, Tetsuya

    2016-06-01

    Cobalt and nickel are high-value commodity metals and are mostly used in the form of highly alloyed materials. The alloying elements used may cause contamination problems during recycling. To ensure maximum resource efficiency, an understanding of the removability of these alloying elements and the controllability of some of the primary alloying elements is essential with respect to the recycling of end-of-life (EoL) nickel- and cobalt-based superalloys by remelting. In this study, the distribution behaviors of approximately 30 elements that are usually present in EoL nickel- and cobalt-based superalloys in the solvent metal (nickel, cobalt, or nickel-cobalt alloy), oxide slag, and gas phases during the remelting were quantitatively evaluated using a thermodynamic approach. The results showed that most of the alloying elements can be removed either in the slag phase or into the gas phase. However, the removal of copper, tin, arsenic, and antimony by remelting is difficult, and they remain as tramp elements during the recycling. On the other hand, the distribution tendencies of iron, molybdenum, and tungsten can be controlled by changing the remelting conditions. To increase the resource efficiency of recycling, preventing contamination by the tramp elements and identifying the alloying compositions of EoL superalloys are significantly essential, which will require the development of efficient prior alloy-sorting systems and advanced separation technologies.

  18. Chemical extraction of refractory inclusions from iron- and nickel-base alloys

    International Nuclear Information System (INIS)

    Most iron- and nickel-base alloys contain certain refractory inclusions, which affect the physical properties of the alloy. Carbides are the predominant inclusion, but oxides, nitrides, sulfides, borides, and phosphides may also be present. A chemical extraction has been developed which effectively separates these inclusions from the matrix without the application of an external potential. The refractory inclusions are quantitatively extracted by chemical dissolution of the matrix at 250C with a solution 0.9 M in copper(II) potassium chloride and hydrochloric acid. The reagent also contains 0.1 M tartaric acid to avoid contamination of the insoluble inclusion with matrix hydrolysis products. The chemical extractant is identified as the Berzelius reagent. The solvent is a general reagent for the isolation of most refractory phases: carbides, nitrides, phosphides, sulfides, oxides, and certain intermetallic compounds. The reagent dissolves alloys which are predominantly aluminum, cobalt, copper, iron, nickel, or zinc. The separation requires up to 24 hours to dissolve the alloys' matrix

  19. Study of negatronic device based on amorphous carbon/nickel nanocomposite

    International Nuclear Information System (INIS)

    Composite based on pyrogallol and formaldehyde (PF) reached by NiO nanoparticles has been prepared using sol–gel method to obtain negatronic PF/Ni devices. The obtained materials were subjected to heat treatment under inert atmosphere at 650 °C for 2 h. The X-ray diffraction analysis (XRD) shows that PF sample was composed of amorphous material while PF/Ni XRD spectra exhibited the presence of metallic nickel characteristic lines. The transmission electron microscopy (TEM) images indicate that PF sample was formed by homogenous material, and metallic nickel nanoparticles sized around 30 nm were dispersed in the PF/Ni nanocomposite. dc I(V) characteristics indicate a symmetric and non-linear behavior and the presence of negative differential resistance (RDN) phase in the PF/Ni sample. The dc conductivity (σdc) can be explained by Variable Range Hopping (3D-VRH) conduction model in both samples. The ac conductance shows the dominance of hopping conduction mechanism in PF sample; however, the Correlated Barrier Hopping (CBH) model seems to be dominant in the PF/Ni nanocomposite. The Nyquist plots were used to identify an equivalent circuit with the aim to study the possible contribution of the grains and boundary grains to the samples conductivities.

  20. Effect of Crystal Orientation on Analysis of Single-Crystal, Nickel-Based Turbine Blade Superalloys

    Science.gov (United States)

    Swanson, G. R.; Arakere, N. K.

    2000-01-01

    High-cycle fatigue-induced failures in turbine and turbopump blades is a pervasive problem. Single-crystal nickel turbine blades are used because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities. Single-crystal materials have highly orthotropic properties making the position of the crystal lattice relative to the part geometry a significant and complicating factor. A fatigue failure criterion based on the maximum shear stress amplitude on the 24 octahedral and 6 cube slip systems is presented for single-crystal nickel superalloys (FCC crystal). This criterion greatly reduces the scatter in uniaxial fatigue data for PWA 1493 at 1,200 F in air. Additionally, single-crystal turbine blades used in the Space Shuttle main engine high pressure fuel turbopump/alternate turbopump are modeled using a three-dimensional finite element (FE) model. This model accounts for material orthotrophy and crystal orientation. Fatigue life of the blade tip is computed using FE stress results and the failure criterion that was developed. Stress analysis results in the blade attachment region are also presented. Results demonstrate that control of crystallographic orientation has the potential to significantly increase a component's resistance to fatigue crack growth without adding additional weight or cost.

  1. ADSORPTION PROPERTIES OF NICKEL-BASED MAGNETIC ACTIVATED CARBON PREPARED BY PD-FREE ELECTROLESS PLATING

    Directory of Open Access Journals (Sweden)

    Boyang Jia

    2011-02-01

    Full Text Available Nickel-based magnetic activated carbon was synthesized from coconut shell activated carbon by electroless plating with palladium-free activation. The effect of plating solution volume on metallic ratio and adsorption capacity were evaluated. The effect of metallic ratio on specific area, pore volume, and magnetic properties were investigated. The morphologies of activated carbon before and after plating were observed by SEM, and the composition of the layer was analyzed by EDS analysis. The results showed that the metallic ratio was increased with the increase of the plating solution volume. The magnetic activated carbon showed high adsorption capacity for methylene blue and a high iodine number. Those values reached 142.5 mg/g and 1035 mg/g, respectively. The specific area and pore volume decreased from 943 m2/g to 859 m2/g and 0.462 ml/g to 0.417 ml/g, respectively. And the layer was more compact and continuous when the metallic ratio reached 16.37 wt.%. In the layer, there was about 97 wt.% nickel and 3 wt.% phosphorus, which indicates that the layer was a low-phosphorus one. At the same time, magnetism was enhanced, making the product suitable for some special applications.

  2. Synthesis of nickel-based skeletal catalyst for an alkaline electrolyzer

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, W.M.; Fernandez, A.M. [Universidad Nacional Autonoma de Mexico, Centro de Investigacion en Energia, Av. Xochicalco s/n, Col. Centro, 62580 Temixco, Morelos (Mexico); Cano, U. [Gerencia de Energias No Convencionales, Instituto de Investigaciones Electricas (IIE), Av. Reforma 113, Col. Palmira 62490, Cuernavaca, Mor. (Mexico); Sandoval J, A. [Instituto de Investigaciones Nucleares, Carretera Mexico-Toluca S/N (Km. 36.5), La Marquesa, Ocoyoacac, Mexico C.P.

    2010-08-15

    A method for preparing Nickel-based skeletal catalyst as well as its characterization is reported. The catalyst has an intended use as a cathode in alkaline electrolysis. Skeletal catalyst electrodes were synthesized from equal weights (50% each) of aluminum and nickel powders. The catalyst was prepared with metal powders which were melted in an induction oven, allowing the alloy to solidify at room temperature to obtain the thermodynamically-stable phases of the alloy. Samples from the resulting alloy went through a leaching process in an alkaline solution using two different leaching times. After leaching, porous and amorphous electrodes were obtained and then subjected to a slow oxidative stage to avoid ignition. The structure, composition, morphology and electrochemical characteristics of the electrodes were studied. The leached samples showed a high exchange current density indicating that are good catalysts for the Hydrogen Evolution Reaction (HER), a property enhanced by the adsorption of hydrogen during the leaching process which facilitated the hydrogen reduction overall reaction. (author)

  3. Properties of large Li ion cells using a nickel based mixed oxide

    Science.gov (United States)

    Broussely, M.; Blanchard, Ph; Biensan, Ph; Planchat, J. P.; Nechev, K.; Staniewicz, R. J.

    The possible use of LiNiO 2 similar to LiCoO 2, as a positive material in rechargeable lithium batteries was recognized 20 years ago and starting 10 years later, many research studies led to material improvement through substitution of some of the nickel ions by other metallic ions. These modifications improve the thermal stability at high charge level or overcharge, as well as cycling and storage properties. Commercial material is now available at large industrial scale, which allows its use in big "industrial" Li ion batteries. Using low cost raw material (Ni), it is expected to be cost competitive with the manganese based systems usually mentioned as low cost on the total cell $/Wh basis. Providing higher energy density, and demonstrating excellent behavior on storage and extended cycle life, LiNiO 2 has definite advantages over the manganese system. Thanks to their properties, these batteries have demonstrated their ability to be used in lot of applications, either for transportation or standby. Their light weight makes them attractive for powering satellites. Although safety improvements are always desirable for all non-aqueous batteries using flammable organic electrolytes, suitable battery designs allow the systems to reach the acceptable level of safety required by many users. Beside the largely distributed lead acid and nickel cadmium batteries, Li ion will found its place in the "industrial batteries" market, in a proportion directly linked to its future cost reduction.

  4. Corrosion of aluminium, stainless steels and AISI 680 nickel alloy in nitrogen-based fuels

    Energy Technology Data Exchange (ETDEWEB)

    Kap, I.; Starostin, M.; Shter, G.E.; Grader, G.S. [Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa (Israel)

    2012-07-15

    Nitrogen-based compounds can potentially be used as alternative non-carbon or low-carbon fuels. Nevertheless, the corrosion of construction materials at high temperatures and pressures in the presence of such fuel has not been reported yet. This work is focused on the corrosion of AISI Al 6061, 1005 carbon steel (CS), 304, 316L, 310 austenitic stainless steels (SS) and 680 nickel alloy in highly concentrated water solution of ammonium nitrate and urea (ANU). The corrosion at 50 C and ambient pressure and at 350 C and 20 bar was investigated to simulate storage and working conditions. Sodium chloride was added to the fuel (0-5 wt%) to simulate industrial fertilizers and accelerated corrosion environment. Heavy corrosion of CS was observed in ANU solution at 50 C, while Al 6061, 304 and 316L SS showed high resistance both to uniform and pitting corrosion in ANU containing 1% of sodium chloride. Addition of 5% sodium chloride caused pitting of Al 6061 but had no influence on the corrosion of SS. Tests in ANU at 350 C and 20 bar showed pitting on SS 304 and 316L and 680 nickel alloy. The highest corrosion resistance was found for SS 310 due to formation of stable oxide film on its surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Magnetic and elastic anisotropy in magnetorheological elastomers using nickel-based nanoparticles and nanochains

    Energy Technology Data Exchange (ETDEWEB)

    Landa, Romina A.; Soledad Antonel, Paula; Ruiz, Mariano M.; Negri, R. Martín, E-mail: rmn@qi.fcen.uba.ar [Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Instituto de Química Física de Materiales, Ambiente y Energía (INQUIMAE), Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, C1428EGA Buenos Aires (Argentina); Perez, Oscar E. [Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (Argentina); Butera, Alejandro [Centro Atómico Bariloche (Comisión Nacional de Energía Atómica. Argentina) and Instituto Balseiro, Universidad Nacional de Cuyo, Mendoza (Argentina); Jorge, Guillermo [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina); Oliveira, Cristiano L. P. [Grupo de Fluidos Complexos, Instituto de Física, Universidade de São Paulo, São Paulo (Brazil)

    2013-12-07

    Nickel (Ni) based nanoparticles and nanochains were incorporated as fillers in polydimethylsiloxane (PDMS) elastomers and then these mixtures were thermally cured in the presence of a uniform magnetic field. In this way, macroscopically structured-anisotropic PDMS-Ni based magnetorheological composites were obtained with the formation of pseudo-chains-like structures (referred as needles) oriented in the direction of the applied magnetic field when curing. Nanoparticles were synthesized at room temperature, under air ambient atmosphere (open air, atmospheric pressure) and then calcined at 400 °C (in air atmosphere also). The size distribution was obtained by fitting Small Angle X-ray Scattering (SAXS) experiments with a polydisperse hard spheres model and a Schulz-Zimm distribution, obtaining a size distribution centered at (10.0 ± 0.6) nm with polydispersivity given by σ = (8.0 ± 0.2) nm. The SAXS, X-ray powder diffraction, and Transmission Electron Microscope (TEM) experiments are consistent with single crystal nanoparticles of spherical shape (average particle diameter obtained by TEM: (12 ± 1) nm). Nickel-based nanochains (average diameter: 360 nm; average length: 3 μm, obtained by Scanning Electron Microscopy; aspect ratio = length/diameter ∼ 10) were obtained at 85 °C and ambient atmosphere (open air, atmospheric pressure). The magnetic properties of Ni-based nanoparticles and nanochains at room temperature are compared and discussed in terms of surface and size effects. Both Ni-based nanoparticles and nanochains were used as fillers for obtaining the PDMS structured magnetorheological composites, observing the presence of oriented needles. Magnetization curves, ferromagnetic resonance (FMR) spectra, and strain-stress curves of low filler's loading composites (2% w/w of fillers) were determined as functions of the relative orientation with respect to the needles. The results indicate that even at low loadings it is

  6. Magnetic and elastic anisotropy in magnetorheological elastomers using nickel-based nanoparticles and nanochains

    International Nuclear Information System (INIS)

    Nickel (Ni) based nanoparticles and nanochains were incorporated as fillers in polydimethylsiloxane (PDMS) elastomers and then these mixtures were thermally cured in the presence of a uniform magnetic field. In this way, macroscopically structured-anisotropic PDMS-Ni based magnetorheological composites were obtained with the formation of pseudo-chains-like structures (referred as needles) oriented in the direction of the applied magnetic field when curing. Nanoparticles were synthesized at room temperature, under air ambient atmosphere (open air, atmospheric pressure) and then calcined at 400 °C (in air atmosphere also). The size distribution was obtained by fitting Small Angle X-ray Scattering (SAXS) experiments with a polydisperse hard spheres model and a Schulz-Zimm distribution, obtaining a size distribution centered at (10.0 ± 0.6) nm with polydispersivity given by σ = (8.0 ± 0.2) nm. The SAXS, X-ray powder diffraction, and Transmission Electron Microscope (TEM) experiments are consistent with single crystal nanoparticles of spherical shape (average particle diameter obtained by TEM: (12 ± 1) nm). Nickel-based nanochains (average diameter: 360 nm; average length: 3 μm, obtained by Scanning Electron Microscopy; aspect ratio = length/diameter ∼ 10) were obtained at 85 °C and ambient atmosphere (open air, atmospheric pressure). The magnetic properties of Ni-based nanoparticles and nanochains at room temperature are compared and discussed in terms of surface and size effects. Both Ni-based nanoparticles and nanochains were used as fillers for obtaining the PDMS structured magnetorheological composites, observing the presence of oriented needles. Magnetization curves, ferromagnetic resonance (FMR) spectra, and strain-stress curves of low filler's loading composites (2% w/w of fillers) were determined as functions of the relative orientation with respect to the needles. The results indicate that even at low loadings it is

  7. Multiaxial creep damage constitutive relationship for nickel-base single crystal superalloys based on the microstructural assessment and application

    International Nuclear Information System (INIS)

    Full text: A multiaxial creep damage constitutive relationship has been presented for nickel-base single crystal superalloys, which takes the microstructural assessment into consideration. It consists of three parts. In the first part, based on the relief of interfacial energy density by dislocation generation at the gamma prime γ' interfaces, a rafting prediction criterion has been developed for nickel-base single crystals under multiaxial stresses. The diagrams of rafting have been presented, and confirmed by experimental results. The rafting processes have been analyzed quantitatively by the relief of interfacial energy. The criterion has been related to study the creep life behavior. The example of creep life analysis shows that the criterion can be correlated satisfactorily to the crystallographic orientation dependence of creep behavior. In the second part, based on the microstructural assessment, a two-state-variable crystallographic creep damage constitutive equation has been presented. The constitutive equation takes into consideration of the rafting-derafting and the damage of the voids simultaneously. With the uniaxial creep experimental data, the constitutive equation can model the creep damage of nickel-base single crystal superalloys, especially the dependence of the creep behavior on the crystallographic orientation. The third part is applications of the constitutive equation. The constitutive equation has been implemented as a user subroutine umat into ABAQUS. The creep experiments of double shear specimens have been carried out to validate the constitutive equation. There is a good agreement between the finite element analytical results and experiment results. The distributions of damage in the double shear creep specimens are given out. (author)

  8. Skeletal Amorphous Nickel Based Alloy Catalysts and Magnetically Stabilized Bed Hydrogenation Technology

    Institute of Scientific and Technical Information of China (English)

    Min Enze

    2004-01-01

    Looking toward 21 century, smaller, cleaner and more energy-efficient technology will be an important trend in the development of chemical industry. In light of the new process requirements,a number of technology breakthroughs have occurred. One of these discoveries, the magnetically stabilized bed (MSB), has been proven a powerful process for intensification. Since its initial research in the late 1980's at Research Institute of Petroleum Processing (RIPP), the MSB technology and related catalytic material have matured rapidly through an intensive research and engineering program, primarily focused on its scaling-up.In this paper, we report the discovery of a novel skeletal amorphous nickel-based alloy and its use in magnetically stabilized bed (MSB). Amorphous alloys are new kinds of catalytic materials with short-range order but long-range disorder structure. In comparison with Raney Ni, the skeletal amorphous nickel-based alloy has an increasingly higher activity in the hydrogenation of reactive groups and compounds including nitro, nitrile, olefin, acetylene, aromatics, etc. Up to now, the amorphous nickel based alloy catalysts, SRNA series catalyst, one with high Ni ratio have been commercially manufactured more than four year. The new SRNA catalyst has been successfully implemented for hydrogenation applications in slurry reactor at Balin Petrochemical, SINOPEC.SRNA catalyst with further improvement in catalytic activity and stability raise its relative stability to 2~4 times of that of conventional catalyst. In the course of the long-cycle operation of SRNA-4 the excellent catalyst activity and stability can bring about such advantage as low reaction temperature, good selectivity and low catalyst resumption.Magnetically stabilized bed (MSB), a fluidized bed of magnetizable particles by applying a spatially uniform and time-invariant magnetic field oriented axially relative to the fluidizing fluid flow, had many advantages such as the low pressure drop and

  9. Analysis of high-temperature creep deformation in a polycrystalline nickel-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Soula, A.; Renollet, Y.; Boivin, D.; Pouchou, J.-L. [Office National d' Etudes et de Recherches Aerospatiales (ONERA), BP 72, 29 avenue de la Division Leclerc, 92322 Chatillon Cedex (France); Locq, D., E-mail: didier.locq@onera.fr [Office National d' Etudes et de Recherches Aerospatiales (ONERA), BP 72, 29 avenue de la Division Leclerc, 92322 Chatillon Cedex (France); Caron, P. [Office National d' Etudes et de Recherches Aerospatiales (ONERA), BP 72, 29 avenue de la Division Leclerc, 92322 Chatillon Cedex (France); Brechet, Y. [Laboratoire de Thermodynamique et de Physico-Chimie Metallurgiques (LTPCM), INPG, Domaine Universitaire, BP 75, 38 402 St Martin d' Heres Cedex (France)

    2009-06-15

    A new quantitative method has been developed for the analysis of the high-temperature creep deformation of polycrystalline nickel-base superalloys. Local deformation was measured by means of microextensometry using ceramic square grids deposited on flat specimens thanks to an electron lithography technique. The efficiency of this method has been proved for tensile creep tests performed under vacuum at 750 deg. C and 525 MPa on the NR6 superalloy and for a wide range of creep strains. This study revealed localization of deformation at grain boundaries and slip bands within the grains. A specific analysis method based on image correlation was developed to quantify the local strain fields. Electron back-scatter diffraction analysis showed that grain boundary sliding is mainly concentrated at general grain boundaries.

  10. Validation of nondestructive testing technology of nickel base alloys welded joints

    International Nuclear Information System (INIS)

    This report summarized modification items of 'ultrasonic testing guide for in-service inspection of light-water type nuclear power plant components' (JEAG4207-2004) for ultrasonic testing method of dissimilar metal welded joints of vessel nozzle and safe end, on the base of basic test using simulated real size test specimen with EDM notch and accuracy confirmation test using real size test specimen with simulated SCC for nickel base alloy welded joints, and their explanatory notes on defect detect ability, measurement accuracy of indication length, scatter of measured values, setting of basic sensitivity of longitudinal wave, scanning direction, and detection test results of EDM notch crossing welded joint, selection of scanning condition and detection test results of defect crossing safe end dissimilar welded joints, were attached. As for circumferential direction scanning (for defect crossing welded joints), 45 - 60 degree variable longitudinal refraction angle beam probe was chosen. (T. Tanaka)

  11. Laser Shock Processing of an Austenitic Stainless Steel and a Nickel-base Superalloy

    Institute of Scientific and Technical Information of China (English)

    Huaming WANG; Xijun SUN; Xiaoxuan LI

    2003-01-01

    An austenitic stainless steel 1Cr18Ni9Ti and a solid solution-strengthened Ni-base superalloy GH30 were shock processed usinga Q-switched pulsed Nd-glass laser. Microstructure, hardness and residual stress of the laser shock processed surface wereinvestigated as functions of laser processing parameters. Results show that high density of dislocations and fine deformationtwins are produced in the laser shock processed surface layers in both the austenitic stainless steel and the nickel-base superalloy.Extensive strain-induced martensite was also observed in the laser shock processed zone of the austenitic steel. The hardnessof the laser shock processed surface was significantly enhanced and compressive stress as high as 400 MPa was produced inthe laser shock processed surface.

  12. The microstructure of heat-treated nickel-based superalloy 718Plus

    International Nuclear Information System (INIS)

    The microstructure of thermally aged nickel-based 718Plus superalloy is investigated using transmission electron microscopy (TEM). Solution annealing at 980 °C for 30 min is followed by either the standard quenching to room temperature or quenching directly to 788 °C, before isothermal aging at 788 °C for four hours. Micro-hardness and yield strength are measured to compare the effects of the two variations. The size and phase fraction of γ′ precipitates are measured using dark-field TEM and related to the hardness and yield strength through a theoretical model based on coherency and antiphase boundary effects. A population of very small sub-precipitates is observed and the larger γ′ precipitates are investigated in detail using high resolution scanning TEM to reveal information about the chemical ordering

  13. Stereological characterization of γ' phase precipitation in CMSX-6 monocrystalline nickel-base superalloy

    International Nuclear Information System (INIS)

    The purpose of this investigation was to study in detail the means to quantitatively evaluate γ' phase precipitation. Many of the mechanical properties of superalloys are directly influenced by the presence of the γ' (gamma prime) precipitate phase dispersed in a γ matrix phase. The γ' precipitates act as effective barriers to dislocation motion and restrict plastic deformation, particularly at high temperatures. Due to this, it is essential to accurately quantify the γ' precipitate size, volume fraction and distribution. Investigations based on quantitative metallography and image analysis were performed on a monocrystalline nickel-base superalloy taking into consideration various γ' precipitate sizes present in that alloy microstructure. The authors of the present paper propose a new method of quantifying the total volume fraction of the γ' phase applying images of the microstructure with γ' phase precipitates registered using light microscopy, scanning electron microscopy (at two different magnifications) and scanning transmission electron microscopy.

  14. Knitted radar absorbing materials (RAM) based on nickel-cobalt magnetic materials

    Science.gov (United States)

    Teber, Ahmet; Unver, Ibrahim; Kavas, Huseyin; Aktas, Bekir; Bansal, Rajeev

    2016-05-01

    There has been a long-standing interest in the development of flexible, lightweight, thin, and reconfigurable radar absorbing materials (RAM) for military applications such as camouflaging ground-based hardware against airborne radar observation. The use of polymeric Polyacrylonitrile (PAN) fabrics as a host matrix for magnetic metal nano-particles (either at the yarn-stage or after weaving the fabric) for shielding and absorbing applications has been described in the literature. In our experimental investigation, the relative concentrations of Nickel and Cobalt as well as the coating time are varied with a view to optimizing the microwave absorption characteristics of the resulting PAN-based composite material in the radar-frequency bands (X, Ku, and K). It is found that the PAN samples with the shortest coating time have the best return losses (under -20 dB return loss over a moderate bandwidth).

  15. Rafting in single crystal nickel-base superalloys — An overview

    Indian Academy of Sciences (India)

    M Kamaraj

    2003-02-01

    Currently nickel-base single crystal (SX) superalloys are considered for the manufacture of critical components such as turbine blades, vanes etc., for aircraft engines as well as land-based power generation applications. Microstructure and high temperature mechanical properties are the major factors controlling the performance of SX superalloys. Rafting is an important phenomenon in these alloys which occurs during high temperature creep. It is essential to understand the rafting mechanism, and its characteristics on high temperature properties before considering the advanced applications. In this review article, the thermodynamic driving force for rafting with and without stress is explained. The nature and influence of rafting on creep properties including pre-rafted conditions are discussed. In addition, the effect of stress state on $\\gamma /\\gamma'$ rafting, kinetics and morphological evolution are discussed with the recent experimental results.

  16. Tensile properties of a nickel-base alloy subjected to surface severe plastic deformation

    International Nuclear Information System (INIS)

    A surface severe plastic deformation (S2PD) method has been applied to bulk specimens of HASTELLOY C-2000 alloy, a nickel-base alloy. The mechanical properties of the processed C-2000 alloy were determined via tensile tests and Vickers hardness measurements, whereas the microstructure was characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The improved tensile strength was related to the nanostructure at the surface region, the residual compressive stresses, and the work-hardened surface layer, all of which resulted from the S2PD process. To understand the contributions of these three factors, finite element modeling was performed. It was found that the improved tensile strength could be interpreted based on the contributions of nano-grains, residual stresses, and work hardening

  17. p-Type dye-sensitized solar cell based on nickel oxide photocathode with or without Li doping

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hui-Tzu; Mishra, D.K. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China); Chen, Peter [Department of Photonics, National Cheng Kung University, Tainan, Taiwan (China); Ting, Jyh-Ming, E-mail: jting@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China)

    2014-01-25

    Highlights: • Microwave-assisted hydrothermal synthesis of NiO nanostructures with Li-doping at low temperature. • p-Type dye-sensitized solar cell based on NiO photocathode. • Study on the effect of Li doping concentration on the cell performance. -- Abstract: Nickel oxide (NiO) nanostructures are synthesized using a microwave-assisted hydrothermal method. The hydrothermal bath has a solution of nickel salt mixed with precipitating agent. During the synthesis the microwave temperature, the concentration of nickel salt and precipitating agent along with the pH of the reaction solutions are changed and different morphologies of nickel oxide are obtained. The resulting nickel oxide nanostructures are characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller method and X-ray photoelectron spectroscopy. Thus formed NiO has been used as a photocathode in dye-sensitized solar cell. Lithium doped NiO showed better IPCE as well as solar to electrical conversion efficiency than the undoped NiO.

  18. Experimental Design for Evaluation of Co-extruded Refractory Metal/Nickel Base Superalloy Joints

    Energy Technology Data Exchange (ETDEWEB)

    ME Petrichek

    2005-12-16

    Prior to the restructuring of the Prometheus Program, the NRPCT was tasked with delivering a nuclear space reactor. Potential NRPCT nuclear space reactor designs for the Prometheus Project required dissimilar materials to be in contact with each other while operating at extreme temperatures under irradiation. As a result of the high reactor core temperatures, refractory metals were the primary candidates for many of the reactor structural and cladding components. They included the tantalum-base alloys ASTAR-811C and Ta-10W, the niobium-base alloy FS-85, and the molybdenum base alloys Moly 41-47.5 Rhenium. The refractory metals were to be joined to candidate nickel base alloys such as Haynes 230, Alloy 617, or Nimonic PE 16 either within the core if the nickel-base alloys were ultimately selected to form the outer core barrel, or at a location exterior to the core if the nickel-base alloys were limited to components exterior to the core. To support the need for dissimilar metal joints in the Prometheus Project, a co-extrusion experiment was proposed. There are several potential methods for the formation of dissimilar metal joints, including explosive bonding, friction stir welding, plasma spray, inertia welding, HIP, and co-extrusion. Most of these joining methods are not viable options because they result in the immediate formation of brittle intermetallics. Upon cooling, intermetallics form in the weld fusion zone between the joined metals. Because brittle intermetallics do not form during the initial bonding process associated with HIP, co-extrusion, and explosive bonding, these three joining procedures are preferred for forming dissimilar metal joints. In reference to a Westinghouse Astronuclear Laboratory report done under a NASA sponsored program, joints that were fabricated between similar materials via explosive bonding had strengths that were directly affected by the width of the diffusion barrier. It was determined that the diffusion zone should not exceed

  19. Experimental Design for Evaluation of Co-extruded Refractory Metal/Nickel Base Superalloy Joints

    International Nuclear Information System (INIS)

    Prior to the restructuring of the Prometheus Program, the NRPCT was tasked with delivering a nuclear space reactor. Potential NRPCT nuclear space reactor designs for the Prometheus Project required dissimilar materials to be in contact with each other while operating at extreme temperatures under irradiation. As a result of the high reactor core temperatures, refractory metals were the primary candidates for many of the reactor structural and cladding components. They included the tantalum-base alloys ASTAR-811C and Ta-10W, the niobium-base alloy FS-85, and the molybdenum base alloys Moly 41-47.5 Rhenium. The refractory metals were to be joined to candidate nickel base alloys such as Haynes 230, Alloy 617, or Nimonic PE 16 either within the core if the nickel-base alloys were ultimately selected to form the outer core barrel, or at a location exterior to the core if the nickel-base alloys were limited to components exterior to the core. To support the need for dissimilar metal joints in the Prometheus Project, a co-extrusion experiment was proposed. There are several potential methods for the formation of dissimilar metal joints, including explosive bonding, friction stir welding, plasma spray, inertia welding, HIP, and co-extrusion. Most of these joining methods are not viable options because they result in the immediate formation of brittle intermetallics. Upon cooling, intermetallics form in the weld fusion zone between the joined metals. Because brittle intermetallics do not form during the initial bonding process associated with HIP, co-extrusion, and explosive bonding, these three joining procedures are preferred for forming dissimilar metal joints. In reference to a Westinghouse Astronuclear Laboratory report done under a NASA sponsored program, joints that were fabricated between similar materials via explosive bonding had strengths that were directly affected by the width of the diffusion barrier. It was determined that the diffusion zone should not exceed

  20. Relationship of heat treatment-mechanical properties of nickel base superalloys

    International Nuclear Information System (INIS)

    The nickel-base superalloys have high strength, excellent corrosion resistant, and good creep and fatigue resistance. These alloy improved properties at high temperature derive their mechanical and creep behavior on γ precipitate morphology, and the evolution of such morphology during different heat treatment conditions. The main microstructural variable of Nickel-based superalloys, responsible for the mechanical properties are: a) amount and morphology of precipitates; b) size and shape of grains; and c) carbide distribution. In this work, a Nickel-base superalloy Nimonic 80A, modified little with Zr prepared by melting and casting practices of materials electrolytic in vacuum-induction melting (VIM) type Balzers, to obtain five alloys different and ingots of 2 Kg and 1 Kg, with composition in weight % of Nimonic 80-A is: Ni = bal (76.66), C = 0.01, Cr = 19.83, Fe = 2.4, Mn = 0.17, Si 0.47, Al = 0.19, Zr = 0.4. The solidification process is made in a steel mold. After having realized four thermal treatments, the most representative microstructures there were obtained. The results from tensile tests performed on Instron Servohydraulic testing systems at uniaxial dynamic testing, at constant speeds to ,0.2 cm/min, were: the yield strength, the ultimate strength value, percentage elongation and area reduction. Creep tests were performed at in stress of 90 and 129 MPa, at a temperature of 600 and 680 Centigrades at different times and width of specimen of 1 mm. The alloys were analyzed by MEB(JEOL 35CF) at different magnifications. The nucleation and growth of intergranular cavities during creep of alloy Nimonic M3, were investigated. One sample was deformed in creep at 129 MPa and 680 Centigrades during 110 hs. Creep samples were annealing heat treated at 800 Centigrades, during 7 days. After a careful sample preparation procedure, 3100 of cavities were measured in the sample . The cavity size distributions in the sample were obtained. The cavity growth rate, was

  1. Misorientation related microstructure at the grain boundary in a nickel-based single crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ming; Zhuo, Longchao [National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Laboratory of Advanced Materials (MOE), Tsinghua University, Beijing 100084 (China); Liu, Zhanli [Applied Mechanics Lab, School of Aerospace, Tsinghua University, Beijing 100084 (China); Lu, Xiaogang [School of Materials Science and Engineering, Shanghai University, Shanghai (China); Shi, Zhenxue; Li, Jiarong [Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Zhu, Jing, E-mail: jzhu@mail.tsinghua.edu.cn [National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Laboratory of Advanced Materials (MOE), Tsinghua University, Beijing 100084 (China)

    2015-07-29

    The mechanical properties of nickel-based single crystal superalloys deteriorate with increasing misorientation, thus the finished product rate of the casting of single crystal turbine airfoils may be reduced due to the formation of grain boundaries especially when the misorientation angle exceeds to some extent. To this day, evolution of the microstructures at the grain boundaries with misorientation and the relationship between the microstructures and the mechanical properties are still unclear. In this work a detailed characterization of the misorientation related microstructure at the grain boundary in DD6 single crystal superalloy has been carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques; the elemental distribution at the grain boundaries has been analyzed by energy dispersive (EDS) X-ray mapping; and the effect of precipitation of μ phases at the grain boundary on the mechanical property has been evaluated by finite element calculation. It is shown that the proportion of γ phase at the grain boundaries decreases, while the proportion of γ′ phase at the grain boundaries increases with increasing misorientation; the μ phase is precipitated at the grain boundaries when the misorientation angle exceeds about 10° and thus it could lead to a dramatic deterioration of the mechanical properties, as well as that the enrichment of Re and W gradually disappears as the misorientation angle increases. All these factors may result in the degradation of the mechanical properties at the grain boundaries as the misorientation increases. Furthermore, the finite element calculation confirms that precipitation of μ phases at the grain boundary is responsible for the significant deterioration of the mechanical properties when the misorientation exceeds about 10°. This work provides a physical imaging of the microstructure for understanding the relationship between the mechanical properties and the misorientation

  2. Oxidation characteristics of nickel-base superalloys at high temperature in air and helium atmospheres

    International Nuclear Information System (INIS)

    Nickel-base superalloys are considered as materials for piping and structural materials in a very high temperature gas cooled reactor (VHTR). They are subjected to the environmental degradation caused by a continuous process for oxidation due to small amount of impurities in He coolant during long term operation. In the present study, the oxidation behaviors of several nickel-base superalloys such as Alloy-617, Haynes-214 and Haynes-230 in particular, were studied at the temperature of 900 and 1100 C degrees in air, and in the high purity He environment. Oxide layers were analyzed by SEM (Scanning Electron Microscope) and EDX (Energy Dispersive X-ray analysis). The differences in oxidation behaviors of these alloys were mainly caused by different protective oxide layers on surface. In the case of Alloy-617 and Haynes-230, Cr2O3 layer formed on the surface which is not stable at 1100 C degrees. Therefore, the weight increased significantly due to oxidation at the initial stage, which followed by a decrease due to the scaling and volatilization of Cr2O3 layer. On the other hand, since Haynes-214 has mainly Al2O3 oxide layer on surface which is more stable and has more dense structure at higher temperature, the weight gain eventually reaches to parabolic. Microstructural characteristics of internal carbides and carbide depletion zone were analyzed. With oxidation time, continuous grain boundary carbides of M23C6 type were getting thin or it disappeared partially. Especially, carbides on grain boundary disappeared entirely below oxide layer (carbide depletion zone). It was getting wide with oxidation time. For Haynes-214, the size of carbide depletion zone was smaller than other alloys because Al2O3 layer acted as a diffusion layer prevented effectively the penetration of oxygen into base metal. (authors)

  3. Low temperature crack propagation of nickel-based weld metals in hydrogenated PWR primary water

    International Nuclear Information System (INIS)

    The effect of hydrogenated PWR primary water on the Low Temperature Crack Propagation (LTCP) susceptibility of nickel-based weld metals Alloy 182, 82, 152 and 52 was studied performing J-R tests at a slow displacement rate in simulated low temperature PWR primary water. When tested in an environment with high hydrogen content (100 cm3 H2/kg H2O), all the studied materials showed a remarkable decrease in the fracture toughness (JIC or JQ) values compared with the air test results. Alloy 182 showed the lowest average fracture toughness values in each test environment. The results obtained at a lower hydrogen content (∼ 30 cm3 H2/kg H2O) suggest, that Alloy 182 is the most susceptible nickel-based weld metal to LTCP, especially at low hydrogen contents. Intergranular cracking was predominant when the JIC value was low. Test results of pure weld metal Alloys 182 and 52 were also compared with the results of dissimilar metal weld (DMW) specimens of Alloy 182 and 52. The pure weld metals were substantially more susceptible to LTCP than the DMW specimens. Pre-exposure to high temperature hydrogenated water did not affect the fracture toughness of any of the test materials. The degradation in toughness is assumed to be caused by a hydrogen-induced intergranular cracking mechanism, where the precipitates in the weld metals acting as hydrogen trapping sites play an important role. The LTCP susceptibility of the studied alloys is discussed based on the present hydrogen embrittlement mechanisms. (authors)

  4. Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

    Science.gov (United States)

    Arakere, N. K.; Swanson, G.

    2002-01-01

    High cycle fatigue (HCF) induced failures in aircraft gas turbine and rocket engine turbopump blades is a pervasive problem. Single crystal nickel turbine blades are being utilized in rocket engine turbopumps and jet engines throughout industry because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493, PWA 1484, RENE' N-5 and CMSX-4. These alloys play an important role in commercial, military and space propulsion systems. Single crystal materials have highly orthotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. The failure modes of single crystal turbine blades are complicated to predict due to the material orthotropy and variations in crystal orientations. Fatigue life estimation of single crystal turbine blades represents an important aspect of durability assessment. It is therefore of practical interest to develop effective fatigue failure criteria for single crystal nickel alloys and to investigate the effects of variation of primary and secondary crystal orientation on fatigue life. A fatigue failure criterion based on the maximum shear stress amplitude /Delta(sub tau)(sub max))] on the 24 octahedral and 6 cube slip systems, is presented for single crystal nickel superalloys (FCC crystal). This criterion reduces the scatter in uniaxial LCF test data considerably for PWA 1493 at 1200 F in air. Additionally, single crystal turbine blades used in the alternate advanced high-pressure fuel turbopump (AHPFTP/AT) are modeled using a large-scale three-dimensional finite element model. This finite element model is capable of accounting for material orthotrophy and variation in primary and secondary crystal orientation. Effects of variation in crystal orientation on blade stress response are studied based on 297

  5. Low cycle fatigue damage in nickel-base superalloy single crystals at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fleury, E. (Centre des Materiaux P.M. Fourt, Ecole des Mines, 91 Evry (France)); Remy, L. (Centre des Materiaux P.M. Fourt, Ecole des Mines, 91 Evry (France))

    1993-08-15

    Low cycle fatigue tests on AM1 nickel-base superalloy single crystals were conducted under axial strain control at 650, 950 and 1100 C. The behaviour of the 001 orientation was investigated at the three temperatures, that of the 111, 101 and 213 specimens was studied at the two lower temperatures. The orientation dependence of fatigue life-total strain range curves was mainly due to variations in Young's modulus with orientation. Most cracks grow in stage II mode whatever the temperature. Cracks nucleate at micropores and in the interior of specimens at low temperatures; surface cracks induced by oxidation are dominant at high temperatures and low strain ranges. Most of fatigue life is spent in microcrack growth. (orig.)

  6. Behavior of nickel-base superalloy single crystals under thermal-mechanical fatigue

    Science.gov (United States)

    Fleury, E.; Rémy, L.

    1994-12-01

    The thermal-mechanical fatigue behavior of AM1 nickel-base superalloy single crystals is studied using a cycle from 600 °C to 1100 °C. It is found to be strongly dependent on crystallo-graphic orientation, which leads to different shapes of the stress-strain hysteresis loops. The cyclic stress-strain response is influenced by variation in Young’s modulus, flow stress, and cyclic hardening with temperature for every crystallographic orientation. The thermalmechanical fatigue life is mainly spent in crack growth. Two main crack-initiation mechanisms occur, depending on the mechanical strain range. Oxidation-induced cracking is the dominant damage mechanism in the lifetime of interest for turbine blades.

  7. Behavior of nickel-base superalloy single crystals under thermal-mechanical fatigue

    Energy Technology Data Exchange (ETDEWEB)

    Fleury, E.: Remy, L. (Ecole des Mines de Paris (France). Centre des Materiaux)

    1994-01-01

    The thermal-mechanical fatigue behavior of AM1 nickel-base superalloy single crystals is studied using a cycle from 600[degree]C to 1,100[degree]C. It is found to be strongly dependent on crystallographic orientation, which leads to different shapes of the stress-strain hysteresis loops. The cyclic stress-strain response is influenced by variation in Young's modulus, flow stress, and cyclic hardening with temperature for every crystallographic orientation. The thermal-mechanical fatigue life is mainly spent in crack growth. Two main crack-initiation mechanisms occur, depending on the mechanical strain range. Oxidation-induced cracking is the dominant damage mechanism in the lifetime of interest for turbine blades.

  8. Creep behaviour at 760 C of two nickel-based single crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Diologent, F.; Caron, P. [ONERA, Chatillon (France)

    2003-07-01

    Creep tests have been performed at 760 C and 840 MPa on the AM1 and MC-NG nickel-based single crystal superalloys suited for gas turbine blade applications. The stress rupture life of MC-NG is slightly longer than that of AM1 but the creep behaviours of the two alloys are very different. Clear relationships have been established between the operative deformation mechanisms and the primary creep behaviours. Occurrence of these different deformation mechanisms is discussed by taking into account the effects of various parameters such as the Orowan stress, the {gamma}/{gamma}' lattice mismatch, the stacking fault energy and the solid solution strengthening of the {gamma} matrix. (orig.)

  9. Grain growth and intergranular carbide precipitation in nickel-base alloy 690

    International Nuclear Information System (INIS)

    The grain growth and precipitation behavior of intergranular carbides in Nickel-base alloy 690 were studied through microscopic equipment. The experimental grain growth data showed a classical growth equation, and carbon atoms in solid solution were found to have a strong drag effect on grain boundary migration. The precipitation of intergranular carbides, identified as Cr-rich M23C6, was retarded (or suppressed) on the low angle grain boundaries and the special boundaries expressed by the coincidence site lattice model, compared to that on the random high angle grain boundaries. The results of intergranular M23C6 carbide precipitation are explained in terms of the influence of grain boundary energy. (orig.)

  10. RESIDUAL STRESS IN NICKEL BASE SUPER ALLOY UDIMET 720 FOR DIFFERENT SURFACE CONDITIONS

    Directory of Open Access Journals (Sweden)

    B.R.SRIDHAR,

    2011-01-01

    Full Text Available Nickel base super alloy Udimet 720 finds applications in gas turbine engine components like discs, shafts and blades. These components rotate at high speeds in a gas turbine engine and consequently experience both high cycle fatigue (HCF and low cycle fatigue (LCF due to dynamic loads and temperatures. Since residual stress affects both HCF and LCF properties, study of residual stress for varying surface conditions for this alloy assumes significance. Specimens extracted from a forging were subjected to different surface conditions such as emery polishing, shot peening to different intensities after emery polishing and thermal stress relief after shot peening. Surface residual stresses were measured by X ray Diffraction technique. Changes in the magnitude of residual stresscould be attributed to corresponding changes in surface conditions and the accompanying surface cold work.

  11. Green Compact Temperature Evolution during Current-Activated Tip-Based Sintering (CATS of Nickel

    Directory of Open Access Journals (Sweden)

    Khaled Morsi

    2013-04-01

    Full Text Available Current-activated tip-based sintering (CATS is a novel process where spark plasma sintering conditions are applied through an electrically conducting tip on a locally controlled area on a green powder compact/bed. The localization of electric current in CATS allows for unique temporal and spatial current and temperature distributions within the tip and powder compact. In this paper, special experimental setups were used to monitor the temperature profiles in the tip and at multiple locations on the surface of nickel powder compacts. A variation in the initial green density was found to have a significant effect on the maximum temperature in the tip as well as the temperature distribution across the powder compact. In general, the lowest green density specimens displayed the best conditions for localized densification. The concept of effective current density is introduced and results are discussed in relation to the densification parameter.

  12. Efficient Electrochemical Water Splitting Catalyzed by Electrodeposited Nickel Diselenide Nanoparticles Based Film.

    Science.gov (United States)

    Pu, Zonghua; Luo, Yonglan; Asiri, Abdullah M; Sun, Xuping

    2016-02-01

    In this contribution, we demonstrate that electrodeposited nickel diselenide nanoparticles based film on conductive Ti plate (NiSe2/Ti) is an efficient and robust electrode to catalyze both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in basic media. Electrochemical experiments show this electrode affords 10 mA cm(-2) at HER overpotential of 96 mV and 20 mA cm(-2) at OER overpotential of 295 mV with strong durability in 1.0 M KOH. The corresponding two-electrode alkaline water electrolyzer requires a cell voltage of only 1.66 V to achieve 10 mA cm(-2) water-splitting current. This development provides us an attractive non-noble-metal catalyst toward overall water splitting applications. PMID:26824878

  13. Nickel oxide nanoparticle-based method for simultaneous harvesting and disruption of microalgal cells.

    Science.gov (United States)

    Huang, Wen-Can; Kim, Jong-Duk

    2016-10-01

    Microalgae biodiesel is considered one of the most promising renewable fuels. However, the high cost of the downstream process is a major barrier to large-scale microalgal lipid production. In this study, a novel approach based on nickel oxide nanoparticles (NiO NPs) was developed and its effectiveness for simultaneous harvesting and cell disruption in microalgal lipid production was determined. NiO NPs exhibited a microalgal harvesting efficiency of 98.75% in 1min at pH 7. Moreover, after treating with NiO NPs for 96h, the lipid extraction efficiency of microalgae (with 80% water content) reached 91.08% and was 208.37% compared to that without NiO treatment. This approach is simple and does not necessitate drying; furthermore, no equipment with high energy consumption was required. PMID:27481468

  14. Nitriding behavior of nickel-based superalloys at 1273 K and above

    International Nuclear Information System (INIS)

    The corrosion behavior of four nickel-based superalloys, Inconel 617, Incoloy 800h, Haynes 230, and Hastelloy X, was studied in various nitrogen-containing atmospheres in the temperature range between 1273 and 1523 K. Inner and outer oxidation, inner nitriding, and decarburization were observed. Aluminum, titanium, and chromium nitrides were found after annealing in pure nitrogen and in N2/Ar/H2 atmosphere. Chromium and tungsten carbides disappeared. Instead of these carbides, a chromium and tungsten-rich phase was formed at the grain boundaries. Under these conditions, Incoloy 800h shows the highest and Haynes 230 the lowest corrosion susceptibility. The type of corrosion products and the kinetics of their formation will be described. The suitability of these alloys for application in the intermediate heat exchanger and in the nitrogen atmospheres of the second cooling circuit will be discussed

  15. Electrochemical polarisation studies on plasma-sprayed nickel-based superalloy

    Science.gov (United States)

    Khan, M. Adam

    2015-08-01

    The plasma-sprayed NiCr-Cr2O3 and Al2O3-40 % TiO2 powders are deposited as coating on nickel-based superalloy. The electrochemical polarisation studies were carried out with 1.0 M H2SO4 solution as a corrosive medium. The corrosion current density of the coated sample was found to be decreased and exhibits better corrosion resistance than bare metal. The characterisation studies on the exposed sample result reveal that the bare metal has undergone severe intergranular attack and segregation on austenitic phase. The corrosion products formed are in the form of sulphides, and contribution of sulphur was noticed through EDS analysis.

  16. Dynamic precipitation of nickel-based superalloys undergoing severe deformation below the solvus temperature

    Energy Technology Data Exchange (ETDEWEB)

    Nowotnik, Andrzej; Rokicki, Pawel; Mrowka-Nowotnik, Grazyna; Sieniawski, Jan [Rzeszow Univ. of Technology (Poland). Dept. of Material Science

    2015-07-15

    The authors performed uniaxial compression tests of nickel-based superalloys: single crystal CMSX-4, also precipitation hardened; Inconel 718 and X750, at temperatures below the γ' solvus, in order to study the effect of temperature and strain rate on their flow stress and microstructural development. On the basis of the obtained flow stress values, the activation energy of a high-temperature deformation process was estimated. Microstructural observations of the deformed samples at high temperatures, previously solution heat treated and aged CMSX-4 and Inconel alloys revealed non-uniform deformation effects. Distribution of either molybdenum- or niobium-rich carbides was found to be affected by localized flow within the investigated strain range at relatively low deformation temperatures, 720-850 C. Microstructural examination of the alloys also showed that shear banding and cavity growth were responsible for the decrease in flow stress and a specimen fracture at larger strains.

  17. Micromechanisms of fatigue crack growth in a forged Inconel 718 nickel-based superalloy

    International Nuclear Information System (INIS)

    The micromechanisms of fatigue crack propagation in a forged, polycrystalline IN 718 nickel-based superalloy are evaluated. Fracture modes under cyclic loading were established by scanning electron microscopy analysis. The results of the fractographic analysis are presented on a fracture mechanism map that shows the dependence of fracture modes on the maximum stress intensity factor, Kmax, and the stress intensity factor range, ΔK. Plastic deformation associated with fatigue crack growth was studied using transmission electron microscopy. The effects of ΔK and Kmax on the mechanisms of fatigue crack growth in this alloy are discussed within the context of a two-parameter crack growth law. Possible extensions to the Paris law are also proposed for crack growth in the near-threshold and high ΔK regimes. (orig.)

  18. Fabrication of directional solidification components of nickel-base superalloys by laser metal forming

    Institute of Scientific and Technical Information of China (English)

    Liping Feng; Weidong Huang; Darong Chen; Xin Lin; Haiou Yang

    2004-01-01

    Straight plates, hollow columns, ear-like blade tips, twist plates with directional solidification microstructure made of Rene 95 superalloys were successfully fabricated on Nickel-base superalloy and DD3 substrates, respectively. The processing conditions for production of the parts with corresponding shapes were obtained. The fabrication precision was high and the components were compact. The solidification microstructure of the parts was analyzed by optical microscopy. The results show that the solidification microstructure is composed of columnar dendrites, by epitaxial growth onto the directional solidification substrates. The crystallography orientation of the parts was parallel to that of the substrates. The primary arm spacing was about 10 μm, which is in the range of superfine dendrites, and the secondary arm was small or even degenerated. It is concluded that the laser metal forming technique provides a method to manufacture directional solidification components.

  19. Creep-fatigue interaction properties of nickel-based superalloy 617

    Institute of Scientific and Technical Information of China (English)

    Kazuo KOBAYASHI; Masao HAYAKAWA; Megumi KIMURA

    2011-01-01

    High-temperature fatigue properties were investigated for a nickel-based superalloy 617 as a typical candidate material for high-temperature components using an advanced ultra super critical (A-USC) power plant. Creep-fatigue data obtained by strain-controlled tests at 700 ℃ was analyzed for the superailoy 617 focused on position of hold at peak strain in comparison with continuously cycled tests. The fatigue life was the shortest with the hold tensile strain wave, which showed mainly intergranular fracture appearance. The life was the longest with symmetrical triangular wave which fractured from the specimen surface, while the wave with the hold compressive strain showed partially intergranular fracture appearance and the life was middle in the both waves. In this study, it is discussed with the creep-fatigue interaction for the superalloy 617.

  20. Tensile behavior of nickel-base single-crystal superalloy DD6

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Xinhong, E-mail: xiongxh@whut.edu.cn [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Quan, Dunmiao; Dai, Pengdan; Wang, Zhiping [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Zhang, Qiaoxin [School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070 (China); Yue, Zhufeng [School of Mechanics Civil Engineering and Architecture, Northwestern Polytechnical University, Xi' an 710072 (China)

    2015-06-11

    Tensile behavior of the nickel-base single-crystal superalloy DD6 was studied from room temperature to 1020 °C. The plate specimens were along [001] orientation parallel to the loading axis in tension. The microstructures on the surface and fracture morphology were investigated after tensile test to rupture by scanning electron microscopy (SEM). The results of the present investigation indicate that the yield strength at 650 °C is superior to that at room temperature, 850 °C and 1020 °C. Low ductility and serrated flow in stress–strain curves were also observed at 650 °C. The microstructures on the surface of the plate specimens and fracture morphology observation indicated that localized slip which resulted in glide plane decohesion caused the low ductility of DD6 alloy.

  1. Microprocessor based protecting and monitoring system for transformer of electric furnace in nickel smelting process

    Institute of Scientific and Technical Information of China (English)

    廖力清; 曾可; 凌玉华; 杨欣荣; 陈燕辉

    2001-01-01

    In nickel smelting process, the working conditions and surroundings for the transformer of electric furnace are worse than general electric power transformer. It is difficult to meet the requirements on reliability and safety by the conventional centralized control protection. With the development of microcomputer and field-bus technology, it is necessary to design a new type of protection and monitoring system for transformer of electric furnace. A microprocessor-based protection and monitoring system was described, which uses the embedded high performance microprocessor 87C196KC20 as its most important micro-controller unit & the technology of CAN (Controller Area Network) making it a fully distributed microcomputer system not only to perform all sorts of the transformer protection and function of automatic coinciding and communicate with the monitoring host, but also to carry with it the function of protecting, measuring, and fault diagnosis for transformer of electric furnace.

  2. Creep-Fatigue Crack Growth Interaction in Nickel Base Supper Alloy

    Directory of Open Access Journals (Sweden)

    F. Djavanroodi

    2008-01-01

    Full Text Available Most engineering components which operate at elevated temperatures are subjected to non-steady loading during service. This paper describes the current fracture mechanics concepts that are employed to predict cracking of Nickel base supper alloy materials at high temperatures under low and high frequency cyclic loading. A model for predicting creep crack growth in terms of C* and the creep uniaxial ductility is presented at low frequency and at high frequency power law relation is used to predict the crack growth rate. When dealing with creep/fatigue interaction a simple cumulative damage concept with fractography evidence is used to predict the crack growth rate. It is shown that these models give good agreement with the experimental results.

  3. Cyclic deformation behavior of a nickel-base superalloy under fatigue loading

    International Nuclear Information System (INIS)

    Highlights: • The fatigue property of the alloy was analyzed. • The prediction of fatigue life was proposed. • The effects of strain amplitudes on cycle deformation behavior were analyzed. • The low cycle fatigue mechanism was discussed. • The nature of cycle deformation behaviors during fatigue process was discussed. - Abstract: Total strain-controlled low cycle fatigue (LCF) tests of a nickel-base superalloy were performed at 650 °C. Combined with fatigue test data, cyclic deformation behaviors of the alloy were analyzed. Fatigue cycle life decreases significantly with the increasing total strain amplitude. The cyclic hardening and cyclic softening phenomena occur during the LCF process, which are associated with the total strain amplitude. Fracture morphologies and dislocation characteristics were observed through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The combined effects of brittle fracture and ductile fracture are the main LCF fracture mechanism of the alloy

  4. Internal nitridation of nickel-base alloys; Innere Nitrierung von Nickelbasis-Legierungen

    Energy Technology Data Exchange (ETDEWEB)

    Krupp, U.; Christ, H.J. [Siegen Univ. (Gesamthochschule) (Germany). Inst. fuer Werkstofftechnik

    1998-12-31

    The chromuim concentration is the crucial variable in nitridation processes in nickel-base alloys. Extensive nitridation experiments with various specimen alloys of the system Ni-Cr-Al-Ti have shown that the Cr itself starts to form nitrides as from elevated initial concentrations of about 10 to 20 weight%, (depending on temperature), but that lower concentrations have an earlier effect in that they induce a considerable increase in the N-solubility of the nickel-base alloys. This causes an accelerated nitridation attack on the alloying elements Ti and Al. Apart from experimental detection and analysis, the phenomenon of internal nitridation could be described as well by means of a mathematical model calculating the diffusion with the finite-differences method and determining the precipitation thermodynamics by way of integrated equilibrium calculations. (orig./CB) [Deutsch] Im Verlauf der Hochtemperaturkorrosion von Nickelbasis-Superlegierungen kann durch beanspruchungsbedingte Schaedigungen der Oxiddeckschicht ein Verlust der Schutzwirkung erfolgen und als Konsequenz Stickstoff aus der Atmosphaere in den Werkstoff eindringen. Der eindiffundierende Stickstoff bildet vor allem mit den Legierungselementen Al, Cr und Ti Nitridausscheidungen, die zu einer relativ rasch fortschreitenden Schaedigung fuehren koennen. Eine bedeutende Rolle bei diesen Nitrierungsprozessen in Nickelbasislegierungen spielt die Cr-Konzentration in der Legierung. So ergaben umfangreiche Nitrierungsexperimente an verschiedenen Modellegierungen des Systems Ni-Cr-Al-Ti, dass Cr zwar selbst erst ab Ausgangskonzentrationen von ca. 10-20 Gew.% (abhaengig von der Temperatur) Nitride bildet, allerdings bereits bei geringen Konzentrationen die N-Loeslichkeit von Nickelbasis-Legierungen entscheidend erhoeht. Dies hat zur Folge, dass es zu einem beschleunigten Nitrierungsangriff auf die Legierungselemente Ti und Al kommt. Neben den experimentellen Untersuchungen konnte das Phaenomen der inneren

  5. Effects of cyclic stress and temperature on oxidation damage of a nickel-based superalloy

    International Nuclear Information System (INIS)

    Highlights: → FIB shows the formation of surface oxide scales and internal micro-voids. → Oxidation damage at 800 deg. C is much more severe than that at 700 deg. C and 750 deg. C. → Cyclic stress enhances the extent of oxidation damage at 750 deg. C and above. → Enrichment of Cr and Ti, as well as lower Ni and Co levels, in the surface oxides. → Penetration of oxygen into the material and internal oxidation are evidenced. - Abstract: Oxidation damage, combined with fatigue, is a concern for nickel-based superalloys utilised as disc rotors in high pressure compressor and turbine of aero-engines. A study has been carried out for a nickel-based alloy RR1000, which includes cyclic experiments at selected temperatures (700-800 deg. C) and microscopy examination using focused ion beam (FIB). The results suggest that the major mechanism of oxidation damage consists of the formation of surface oxide scales and internal micro-voids and oxide particles beneath the oxide scales, which become more severe with the increase of temperature. Applying a cyclic stress does not change the nature of oxidation damage but tends to enhance the extent of oxidation damage for temperatures at 750 deg. C and 800 deg. C. The influence of cyclic stress on oxidation damage appears to be insignificant at 700 deg. C, indicating a combined effect of cyclic stress and temperature. Further energy-dispersive X-ray spectrometry (EDXS) analyses show the enrichment of Cr and Ti, together with lower Ni and Co levels, in the surface oxide scales, suggesting the formation of brittle Cr2O3, TiO2, NiO and Co3O4 oxides on the specimen surface. Penetration of oxygen into the material and associated internal oxidation, which leads to further material embrittlement and associated failure, are evidenced from both secondary ion imaging and EDXS analyses.

  6. Stress corrosion cracking of nickel base alloys in PWR primary water

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) of nickel base alloys and associated weld metals in primary water is one of the major concerns for pressurized water reactors (PWR). Since the 90's, highly cold-worked stainless steels (non-sensitized) were also found to be susceptible to SCC in PWR primary water ([1], [2], [3]). In the context of the life extension of pressurized water reactors, laboratory studies are performed in order to evaluate the SCC behaviour of components made of nickel base alloys and of stainless steels. Some examples of these laboratory studies performed at CEA will be given in the talk. This presentation deals with both initiation and propagation of stress corrosion cracks. The aims of these studies is, on one hand, to obtain more data regarding initiation time or crack growth rate and, one the other hand, to improve our knowledge of the SCC mechanisms. The aim of these approaches is to model SCC and to predict components life duration. Crack growth rate (CGR) tests on Alloy 82 with and without post weld heat treatment are performed in PWR primary water (Figure 1). The heat treatment seems to be highly beneficial by decreasing the CGR. This result could be explained by the effect of thermal treatment on the grain boundary nano-scopic precipitation in Alloy 82 [4]. The susceptibility to SCC of cold worked austenitic stainless steels is also studied. It is shown that for a given cold-working procedure, SCC susceptibility increases with increasing cold-work ([2], [5]). Despite the fact that the SCC behaviour of Alloy 600 has been widely studied for many years, recent laboratory experiments and analysis ([6], [7], [8]) showed that oxygen diffusion is not a rate-limiting step in the SCC mechanism and that chromium diffusion in the bulk close the crack tip could be a key parameter. (authors)

  7. NICKEL HYDROXIDES

    Energy Technology Data Exchange (ETDEWEB)

    MCBREEN,J.

    1997-11-01

    Nickel hydroxides have been used as the active material in the positive electrodes of several alkaline batteries for over a century. These materials continue to attract a lot of attention because of the commercial importance of nickel-cadmium and nickel-metal hydride batteries. This review gives a brief overview of the structure of nickel hydroxide battery electrodes and a more detailed review of the solid state chemistry and electrochemistry of the electrode materials. Emphasis is on work done since 1989.

  8. Substructure based modeling of nickel single crystals cycled at low plastic strain amplitudes

    Science.gov (United States)

    Zhou, Dong

    In this dissertation a meso-scale, substructure-based, composite single crystal model is fully developed from the simple uniaxial model to the 3-D finite element method (FEM) model with explicit substructures and further with substructure evolution parameters, to simulate the completely reversed, strain controlled, low plastic strain amplitude cyclic deformation of nickel single crystals. Rate-dependent viscoplasticity and Armstrong-Frederick type kinematic hardening rules are applied to substructures on slip systems in the model to describe the kinematic hardening behavior of crystals. Three explicit substructure components are assumed in the composite single crystal model, namely "loop patches" and "channels" which are aligned in parallel in a "vein matrix," and persistent slip bands (PSBs) connected in series with the vein matrix. A magnetic domain rotation model is presented to describe the reverse magnetostriction of single crystal nickel. Kinematic hardening parameters are obtained by fitting responses to experimental data in the uniaxial model, and the validity of uniaxial assumption is verified in the 3-D FEM model with explicit substructures. With information gathered from experiments, all control parameters in the model including hardening parameters, volume fraction of loop patches and PSBs, and variation of Young's modulus etc. are correlated to cumulative plastic strain and/or plastic strain amplitude; and the whole cyclic deformation history of single crystal nickel at low plastic strain amplitudes is simulated in the uniaxial model. Then these parameters are implanted in the 3-D FEM model to simulate the formation of PSB bands. A resolved shear stress criterion is set to trigger the formation of PSBs, and stress perturbation in the specimen is obtained by several elements assigned with PSB material properties a priori. Displacement increment, plastic strain amplitude control and overall stress-strain monitor and output are carried out in the user

  9. Caractérisation d'un alliage 2024-T3 assemblé par friction-malaxage

    OpenAIRE

    JEMAL, Nejah; MASSE, Jean-Eric; LANGLOIS, Laurent; TCHERNIAEFF, Serge; GIROT, Franck

    2010-01-01

    Le procédé Friction Stir Welding qui peut se traduire en français par friction malaxage a été inventé par le TWI de Cambridge en 1991. La soudure est réalisée par apport de chaleur provoqué par le frottement d'un outil en rotation et mis en pression sur la pièce. Ce procédé intéresse les utilisateurs d'alliages légers car, sans passer par la fusion, il permet le soudage d'alliages à haute résistance, jusque là inutilisables en raison de leur soudabilité difficile avec les procédés traditionne...

  10. Caractérisation d'un alliage 2024-T3 assemblé par friction-malaxage

    OpenAIRE

    JEMAL, Nejah; MASSE, Jean-Eric; LANGLOIS, Laurent; TCHERNIAEFF, Serge; GIROT, Franck

    2010-01-01

    Le procédé Friction Stir Welding qui peut se traduire en français par friction malaxage a été inventé par le TWI de Cambridge en 1991. La soudure est réalisée par apport de chaleur provoqué par le frottement d’un outil en rotation et mis en pression sur la pièce. Ce procédé intéresse les utilisateurs d’alliages légers car, sans passer par la fusion, il permet le soudage d’alliages à haute résistance, jusque là inutilisables en raison de leur soudabilité difficile avec les procédés traditionne...

  11. DNA binding, BSA interaction and SOD activity of two new nickel(II) complexes with glutamine Schiff base ligands.

    Science.gov (United States)

    Wei, Qiang; Dong, Jianfang; Zhao, Peiran; Li, Manman; Cheng, Fengling; Kong, Jinming; Li, Lianzhi

    2016-08-01

    Two hexacoordinated octahedral nickel(II) complexes, [Ni(o-van-gln)(phen)(H2O)](1) and [Ni(sal-gln)(phen)(H2O)](2) [o-van-gln=a Schiff base derived from o-vanillin and glutamine, sal-gln=a Schiff base derived from salicylaldehyde and glutamine, phen=1,10-phenanthroline], have been synthesized and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. X-ray studies showed that nickel atoms of both 1 and 2 exhibit distorted NiN3O3 octahedral geometry. In each crystal, intermolecular hydrogen bonds form a two-dimensional network structure. DNA-binding properties of these two nickel(II) complexes were investigated by using UV-Vis absorption, fluorescence, circular dichroism (CD) spectroscopies and viscosity measurements. Results indicated that the two complexes can bind to calf thymus DNA (CT-DNA) via an intercalative mode, and complex 1 exhibits higher interaction with CT-DNA than complex 2. Furthermore, the interactions between the nickel(II) complexes with bovine serum albumin (BSA) have been studied by spectroscopies. The results indicated that both complexes could quench the intrinsic fluorescence of BSA in a static quenching process. The binding constants (Kb) and the numbers of binding sites (n) obtained are 1.10×10(5)M(-1) and 1.05 for complex 1 and 5.05×10(4)M(-1) and 0.997 for complex 2, respectively. Site-selective competitive binding investigation indicated that the binding sites of both the complexes are located in site I of sub-domains IIA of BSA. Assay of superoxide dismutase (SOD) activity of the nickel(II) complexes revealed that they exhibit significant superoxide scavenging activity with IC50=3.4×10(-5)M for complex 1 and 4.3×10(-5)M for complex 2, respectively. PMID:27295415

  12. Combination of Asymmetric Supercapacitor Utilizing Activated Carbon and Nickel Oxide with Cobalt Polypyridyl-Based Dye-Sensitized Solar Cell

    International Nuclear Information System (INIS)

    Highlights: • Dye Solar Cell and supercapacitor are integrated into a single device capable of generation and storage of energy. • The solar cell part of the device utilizes the Co-based electrolyte and nickel/PEDOT counter electrode. • A cobalt-doped nickel oxide together with activated carbon is used in the capacitor part of the device. • The integrated photocapacitor is characterized by the capacitance of 32 F g−1 and the total efficiency of 0.6%. - Abstract: A dye-sensitized solar cell (DSC) based on the metal-free organic sensitizer and the cobalt (II, III) polypyridyl electrolyte was integrated here within an asymmetric supercapacitor utilizing cobalt-doped nickel oxide and activated carbon as positive and negative electrodes, respectively. A low cost nickel foil served as intermediate (auxiliary) bifunctional electrode separating two parts of the device and permitting the DSC electrolyte regeneration at one side and charge storage within cobalt-doped nickel oxide at the other. The main purpose of the research was to develop an integrated photocapacitor system capable of both energy generation and its further storage. Following irradiation at the 100 mW cm−2 level, the solar cell generated an open-circuit voltage of 0.8 V and short-circuit current of 8 mA cm−2 which corresponds to energy conversion efficiency of 4.9%. It was further shown that upon integration with asymmetric supercapacitor, the photogenerated energy was directly injected into porous charge storage electrodes thus resulting in specific capacitance of 32 F g−1 and energy density of 2.3 Wh kg−1. The coulumbic and total (energy conversion and charge storage) efficiency of photocapacitor were equal to 54% and 0.6%, respectively

  13. Restoration and Thermal Stability Investigation of Intermetllic Phase in Exposed Nickel Base Superalloy Udimet 500 Turbine Blades

    OpenAIRE

    Wangyao, P.; J. Zrnik; Mamuzić, I.; Polsilapa, S.; Klaijumrang, S.

    2007-01-01

    The Udimet 500 nickel base superalloy blade exposed for 50000 hours in land base gas turbine working conditions faced the structure degradation. Six different heat treatments procedures have been applied (the blades were exposed at 900 °C and 1000 °C for different periods with maximum hold of 2500 hours) to rejuvenate the degraded structure. Metallographic work was performed, generally, aging at both temperatures modify the gamma prime size, morphology and distribution characteristics substan...

  14. Near-surface residual stresses and microstructural changes after turning of a nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Schlauer, Christian

    2003-07-01

    Nickel-based superalloys are precipitation hardened alloys with complex compositions. They are used in aircraft engines and land-based gas turbines in load bearing structural components that are exposed to high temperatures. Failure mechanisms in this environment are high and low cycle fatigue, creep, and corrosion. During manufacturing, residual stresses are often introduced into the material due to inhomogeneous plastic deformations, both intentionally and unintentionally. One such manufacturing process is metal cutting, which introduces residual stresses in the surface layer. The stress state in the near-surface zone of components is of special interest as the surface often experiences peak loads and cracks have their starting point there. In this thesis, near-surface residual stress distributions and microstructural changes are studied in the nickel-based superalloy Inconel 718 for two different turning operations, face grooving and facing. Process variables are in both cases cutting speed and feed that have been varied between (10 and 1200) m/min and (0.01 and 0.5) mm, respectively. The first turning technique face grooving, which gives cutting conditions similar to orthogonal cutting, showed a clear dependency of the residual stresses on the cutting speed. The tensile stress at the surface, the maximum compressive stress below the surface, and the thickness of the affected layer increase with increasing cutting speed. The tensile stresses are constrained to a thin surface layer and compressive residual stresses below the surface dominate the depth profile of the residual stresses. Only at low cutting speed, residual stresses were largely avoided. The second turning technique facing confirmed the dependency of the residual stresses on the cutting speed and revealed a similar dependency on the feed. Microstructural investigations of near-surface cross-sections by means of transmission electron microscopy showed a zone where the grains had undergone plastic

  15. EIS pitting temperature determination of A182 nickel based alloy in simulated BWR environment containing dilute seawater

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Stable pitting events in function of the temperature are monitored by electrochemical impedance spectroscopy. • The pitting temperature for the nickel based alloy A182 in solution containing 450 ppm Cl− is defined as above 160 °C. • The presented method can be applied for others passive alloys as stainless steel in solution containing aggressive anions. - Abstract: A method based on electrochemical impedance spectroscopy (EIS) measurements to monitor the pitting temperature of passive alloys in a given media is developed in this communication. The pitting corrosion behavior of the nickel based alloy 182 in water containing 450 ppm by weight of chloride is presented in this study. The analysis of the EIS fit parameters from the proposed equivalent electrical circuit allows to determine the temperature from which stable pitting event occurs at open circuit potential. For the A182 sample this temperature is measured above 160 °C

  16. Elucidation of behavior of sulfur on nickel-based hot gas cleaning catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Hepola, Jouko [VTT Energy, Energy Production Technologies, Espoo (Finland); McCarty, Jon; Wong, Victor [Catalytica, Inc., Mountain View, CA (United States); Krishnan, Gopala [SRI International, Menlo Park, CA (United States)

    1999-03-08

    A closed-loop gas-recirculation system was used to measure the isosteric heat of sulfur chemisorption on supported nickel catalysts in hot gas cleaning conditions of gasification gas. During sulfur adsorption, reconstruction of the catalysts occurred. In addition, probably the enormous increase in surface diffusion due to sulfur adsorption on some nickel catalysts with high flow rates resulted in melt formation of adsorbed species on the surfaces of catalyst particles. Heat of sulfur adsorption on nickel decreased when sulfur coverage was increased. However, the enthalpy of adsorption decreased even below the heat of formation of bulk Ni{sub 3}S{sub 2}, indicating most likely multi-layer or subsurface sulfur formation on catalyst surfaces. The structural properties of the catalysts had a great influence on sulfur adsorption behavior. The effect of sulfur on ammonia decomposition in synthetic gasification gas tests was explained by the change of heat of sulfur chemisorption on nickel

  17. Effets d'environnements sur la rupture des alliages de Zr en milieu nucléaire

    Science.gov (United States)

    Yvon, P.; Lemaignan, C.

    2003-03-01

    Les alliages de zirconium sont essentiellement utilisés dans les réacteurs nucléaires modérés et refroidis à l'eau. Absorbant peu les neutrons thermiques, ils sont choisis pour réaliser divers éléments de structure et les tubes de gainage. Formant la première barrière, leur intégrité doit donc être garantie parfaitement. Diverses sollicitations liées à l'irradiation peuvent cependant conduire à développer une fissuration dans ces composants critiques. On présente dans cette revue l'impact des phénomènes suivants : - une fragilisation, lors de la déformation à froid, liée à la présence d'hydures dont la formation est associée à l'oxydation de l'alliage, - la création de produits de fission, dont l'iode, dans l'UO2, responsable d'un phénomène de corrosion sous contrainte, - une modification de la microstructure de l'alliage, avec, entre autres, formation de boucles de dislocations obtenues par condensation des défauts ponctuels, ce dernier point induisant une localisation de la déformation et une réduction de la déformation à rupture.

  18. ANISOTROPIE MAGNETIQUE PERPENDICULAIRE DES COUCHES MINCES EPITAXIEES D'ALLIAGES ORDONNES FePd

    OpenAIRE

    Géhanno, Véronique

    1997-01-01

    Nous avons étudié l'anisotropie magnétique perpendiculaire résultant de la mise en ordre chimique de type L10, dans des couches minces d'alliage FePd élaborées en Epitaxie par Jets Moléculaires. Différentes procédures d'élaboration ont été mises en oeuvre : - la codéposition à température ambiante, éventuellement suivie d'un recuit ; - la codéposition à 350°C ; - le dépôt alterné de couches atomiques Fe et Pd, contrôlé par le temps de dépôt ou par les oscillations RHEED. La structure des alli...

  19. Soudage d'alliages d'aluminium par la technologie Friction Stir Welding Bobbin Tool

    OpenAIRE

    Guerin, Baptiste jean patrice,

    2010-01-01

    Dans le domaine des matériaux métalliques, les techniques d’assemblage par soudageconduisent à des réductions de masse et de coûts importantes susceptibles d’intéresserles industries aéronautiques. Néanmoins, les procédés de soudage classiquespar fusion ne s’appliquent pas aux dernières générations d’alliages d’aluminium aéronautiques.Dans ce contexte, le procédé de soudage Friction Stir Welding présentedes atouts considérables, de nature à rendre compétitives les structures métalliquesface à...

  20. The effect of carbon on the metallography of a nickel base removable partial denture casting alloy.

    Science.gov (United States)

    Lewis, A J

    1979-04-01

    This study has demonstrated the pattern of carbide development associated with progressive increases in carbon content in a series of six nickel chromium alloys. The carbon content is critical since it influences the production and distribution of carbides, which have been shown to alter the mechanical properties, of the nickel chromium alloys, that are dependent upon the development of gamma prime. Furthermore, it has been shown that the attainment of suitable strength is invariably associated with an unacceptable level of ductility. PMID:288385

  1. Effects of the Helium Environment on Degradation of Nickel-Base Superalloys

    International Nuclear Information System (INIS)

    The test results from nickel-base superalloys at 900 .deg. C showed that stable oxide layers were built up in the air conditions and its oxidation resistance was excellent. Haynes 230 formed multi-oxide layers such as MnCr2O4 and Cr2O3. Owing to the outermost MnCr2O4 which is a kind of spinel structure, oxidation resistance become better because it makes the oxygen diffusion difficult. On the other hand, Alloy 617 formed multi-oxide layers such as NiO, NiCr2O4, and Cr2O3. The outermost layers, NiO and NiCr2O4, could not carry out protective oxide layers because of its microscopic coarse structure. The test results from the both nickel-base superalloys at 1100 .deg. C showed that inner Cr2O3 oxide layer was exposed to the severe environment because of the spallation of the outermost oxide layer. In other words, oxidation resistance become poor on account of unstable oxide layers at high temperature. In the impure helium environments with very low oxygen activities such as He-H2O-CO-CO2 and He-H2-H2O-CO-CO2-CH4, a Cr2O3 layer, TiO2 ridges on grain boundaries, and isolated MnCr2O4 grains on top of the Cr2O3 layer were formed for Alloy 617, while a Cr2O3 inner layer and a MnCr2O4 outer layer were formed for Haynes 230. Mn depletion induced by forming MnCr2O4 was an important factor to increase oxidation resistance of Haynes 230 which resulted in the change in oxidation kinetics. A dense MnCr2O4 oxide layer was grown in impure helium environments for Haynes 230, while quasi-columnar MnCr2O4 grains were grown in air, which resulted in the better oxidation resistance in impure helium environments

  2. Effects of the Helium Environment on Degradation of Nickel-Base Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Jang, C. H.; Kim, D. J.; Datta, D.; Kim, M. W.; Kwon, J. H.; Arief, A.; Cho, J. Y. [KAIST, Daejeon (Korea, Republic of)

    2009-10-15

    The test results from nickel-base superalloys at 900 .deg. C showed that stable oxide layers were built up in the air conditions and its oxidation resistance was excellent. Haynes 230 formed multi-oxide layers such as MnCr{sub 2}O{sub 4} and Cr{sub 2}O{sub 3}. Owing to the outermost MnCr{sub 2}O{sub 4} which is a kind of spinel structure, oxidation resistance become better because it makes the oxygen diffusion difficult. On the other hand, Alloy 617 formed multi-oxide layers such as NiO, NiCr{sub 2}O{sub 4}, and Cr{sub 2}O{sub 3}. The outermost layers, NiO and NiCr{sub 2}O{sub 4}, could not carry out protective oxide layers because of its microscopic coarse structure. The test results from the both nickel-base superalloys at 1100 .deg. C showed that inner Cr{sub 2}O{sub 3} oxide layer was exposed to the severe environment because of the spallation of the outermost oxide layer. In other words, oxidation resistance become poor on account of unstable oxide layers at high temperature. In the impure helium environments with very low oxygen activities such as He-H{sub 2}O-CO-CO{sub 2} and He-H2-H{sub 2}O-CO-CO{sub 2}-CH{sub 4}, a Cr{sub 2}O{sub 3} layer, TiO{sub 2} ridges on grain boundaries, and isolated MnCr{sub 2}O{sub 4} grains on top of the Cr{sub 2}O{sub 3} layer were formed for Alloy 617, while a Cr{sub 2}O{sub 3} inner layer and a MnCr{sub 2}O{sub 4} outer layer were formed for Haynes 230. Mn depletion induced by forming MnCr{sub 2}O{sub 4} was an important factor to increase oxidation resistance of Haynes 230 which resulted in the change in oxidation kinetics. A dense MnCr{sub 2}O{sub 4} oxide layer was grown in impure helium environments for Haynes 230, while quasi-columnar MnCr{sub 2}O{sub 4} grains were grown in air, which resulted in the better oxidation resistance in impure helium environments

  3. Temperature dependence of the structural order in the {gamma}{prime} phase of nickel base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Royer, A. [European Synchrotron Radiation Facility, Grenoble (France); Bastie, P. [Univ. Joseph Fourier Grenoble 1-CNRS, Saint-Martin-d`Heres (France). Lab. de Spectrometrie Physique; Veron, M. [LTPCM, Saint-Martin-d`Heres (France)

    1999-03-19

    Single crystal nickel base superalloys are used for the high-temperature parts of aircraft engines like turbine blades. Their good mechanical properties at high temperature are related to the precipitation of an ordered {gamma}{prime} phase which induces a structural hardening of the material. The {gamma}{prime} phase has an ordered L1{sub 2} structure while the {gamma} matrix is disordered and has a FCC structure. The volume fraction of f{gamma}{prime} of the {gamma}{prime} phase evolves with the temperature and a complete solutionizing occurs above 1,280 C in the AM1 superalloy. The {gamma}{prime} phase of Ni based superalloys is usually analyzed through its prototype Ni{sub 3}Al. As the Ni{sub 3}Al structure remains totally ordered up to temperature very close to the melting point, it is commonly assumed in superalloys that the {gamma}{prime} phase precipitates are fully ordered up to their solutionizing and that the volume fraction of the precipitates is equivalent to the volume fraction of the ordered phase. However, in superalloys, it is difficult to separate experimentally the effects related to the solutionizing of the precipitates from those due to a possible partial disordering of the {gamma}{prime} phase and this assumption has not been verified yet. The aim of this paper is to study the structural order in the {gamma}{prime} phase of a superalloy.

  4. Microstructural evolution of a nickel-based superalloy during hot deformation

    International Nuclear Information System (INIS)

    Highlights: • Deformation parameters have significant influences on the grain microstructure. • The dislocation substructure is also very sensitive to the deformation parameters. • The bulging of initial grain boundaries is the main nucleation mechanism of DRX. • The complete DRX domains are determined by DRX volume fractions contour map. - Abstract: Hot compressive tests of a nickel-based superalloy are performed under the strain rate range of 0.001–1 s−1 and deformation temperature range of 920–1040 °C. Optical microscopy (OM) and transmission electron microscopy (TEM) are employed to investigate the evolution of dynamic recrystallized (DRX) grain and dislocation substructure. It is found that the effects of deformation degree, strain rate and deformation temperature on DRX grain are significant. When the deformation degree or temperature is increased, the number of DRX grains rapidly increases. But, the increase of strain rate reduces the number of DRX grains. The dislocation substructure is also very sensitive to the deformation degree, strain rate and deformation temperature. With the increase of deformation degree, the evolution of dislocation substructure can be characterized as: high dislocation density → dislocation network → subgrain → DRX grain. Under high deformation temperatures or low strain rates, the dislocation substructure can be easily annihilated and rearranged because of the occurrence of DRX. Based on the evaluated DRX volume fractions, the contour map is constructed to optimize the hot deformation parameters

  5. Correlations between electrochemical mechanisms and growth of ceria based coatings onto nickel substrates

    International Nuclear Information System (INIS)

    Highlights: ► Correlations between the electrochemical curves and the growth mechanisms were demonstrated. ► Similar composition of the deposited layers but strong morphological differences. ► Great influence of the composition and surface condition upon transient stages of deposition. ► Need of an incubation time for the precipitation to occur was underlined in the very first minutes. ► Contribution of nitrate reduction to electrogeneration of bases was disregarded. -- Abstract: Cathodic electrosynthesis of cerium-containing films onto model Ni and both raw and aluminized nickel-based superalloy was investigated from concentrated aqueous solutions of cerium nitrate at room temperature. The correlations between the electrochemical features and the microstructure of the resulting layers were established. Polarization curves revealed that transient deposition stages were the most critical as both composition and surface condition of the substrate strongly influenced the nucleation and growth processes and the final morphology of the coatings. SEM/EDS analyses showed that the films initially developed in a homogeneous manner onto raw substrates whereas nuclei grew mainly onto grain boundaries of aluminized samples before covering the grains. Quick growth kinetics led to oxygen defective deposits composed of a mixture of hydrated cerium oxide/hydroxide incorporating carbonates and trapped nitrates due to incomplete reactions

  6. Flaw evaluation technologies for dissimilar metal welds of nickel based alloy

    International Nuclear Information System (INIS)

    Stress Corrosion Cracking (SCC), which occurs in a dissimilar metal weld between a shroud support made of nickel based alloy and a reactor pressure vessel made of low alloy steel in BWR plant, is concerned to induce propagation into the pressure vessel wall thickness. No experience of propagating the crack into the pressure vessel base metal has been reported in both Japan and overseas until now. However, it is necessary to study possibility and evaluation method concerning propagation into the pressure vessel by SCC crack, in order to ensure the safety of Nuclear Power Plants. This safety assessment started for the purpose of preparing evaluation method and collecting data, in order to serve technical examination of the consensus standard and to cross-check of utility's periodic inspections by regulatory body. The residue stress in the weld joint was analyzed in detail by FEM code and compared with the past test results, and further adequacy of analysis model was discussed. (author)

  7. CO2/H2 Methanation Reactivity of Nickel Oxide Based Catalyst Prepared from Different Nickel Salt Precursors

    International Nuclear Information System (INIS)

    The catalytic activity of NiO based catalyst prepared from different salt precursors of acetate, nitrate and sulphate salts were investigated towards CO2/H2 methanation reaction, in order to study the effect of type of precursor on the reactivity of the catalyst prepared. Results obtained showed that the NiO based catalyst prepared from nitrate precursor gave highest catalytic activity with 80.03% methanation of CO2 at 500 deg. C of the reaction temperature. Characterization techniques such as FTIR, XRD and SEM were carried out to see the effect of various physical properties of the NiO based catalyst obtained from different salts precursors used, which contributed in a good CO2/H2 methanation reactivity of the catalyst.

  8. Ferrous sulfate based low temperature synthesis and magnetic properties of nickel ferrite nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tejabhiram, Y., E-mail: tejabhiram@gmail.com [Nanotechnology Research Center, SRM University, SRM Nagar, Kattankulathur, Kancheepuram District, TN 603203 (India); Pradeep, R. [Department of Physics and Nanotechnology, SRM University, SRM Nagar, Kattankulathur, Kancheepuram District, TN 603203 (India); Helen, A.T.; Gopalakrishnan, C. [Nanotechnology Research Center, SRM University, SRM Nagar, Kattankulathur, Kancheepuram District, TN 603203 (India); Ramasamy, C. [Department of Pharmacy Practice, SRM University, SRM Nagar, Kattankulathur, Kancheepuram District, TN 603203 (India)

    2014-12-15

    Highlights: • Novel low temperature synthesis of nickel ferrite nanoparticles. • Comparison with two conventional synthesis techniques including hydrothermal method. • XRD results confirm the formation of crystalline nickel ferrites at 110 °C. • Superparamagnetic particles with applications in drug delivery and hyperthermia. • Magnetic properties superior to conventional methods found in new process. - Abstract: We report a simple, low temperature and surfactant free co-precipitation method for the preparation of nickel ferrite nanostructures using ferrous sulfate as the iron precursor. The products obtained from this method were compared for their physical properties with nickel ferrites produced through conventional co-precipitation and hydrothermal methods which used ferric nitrate as the iron precursor. X-ray diffraction analysis confirmed the synthesis of single phase inverse spinel nanocrystalline nickel ferrites at temperature as low as 110 °C in the low temperature method. Electron microscopy analysis on the samples revealed the formation of nearly spherical nanostructures in the size range of 20–30 nm which are comparable to other conventional methods. Vibrating sample magnetometer measurements showed the formation of superparamagnetic particles with high magnetic saturation 41.3 emu/g which corresponds well with conventional synthesis methods. The spontaneous synthesis of the nickel ferrite nanoparticles by the low temperature synthesis method was attributed to the presence of 0.808 kJ mol{sup −1} of excess Gibbs free energy due to ferrous sulfate precursor.

  9. Etude du nickel fritté au SPS et de l’écrouissage du Fe-3%Si GO

    OpenAIRE

    Molina Martínez, Gonzalo

    2011-01-01

    Les objectifs de ce projet consistent à caractériser deux types de matériaux métalliques. La première partie porte sur le frittage d’une poudre de nickel pure par Spark Plasma Sintering (SPS) et la seconde s’intéresse à la microstructure ainsi qu’aux propriétés mécaniques d’un alliage de fer –silicium (Fe-3%Si). Le nickel est un élément chimique fortement connu et utilisé depuis plus de vingt siècles. Il ne se trouve pas sous forme de minéral pur dans la nature. Pour en obtenir, il faut l’...

  10. Relationship between heat treatment, microstructure and creep rupture behavior of the nickel-base cast alloy IN 100

    International Nuclear Information System (INIS)

    The nickel-base cast alloy IN 100 is used for turbine blades for service in the temperature range above 800deg C. On account of the high proportion of the γ'-precipitation hardening phase of more than 50% IN 100 belongs the top group of high-temperature nickel-base superalloys. It is reported on investigations with IN 100 in order to better understand the casting-specific, large property variations and to define and to optimize the creep characteristics and the creep to rupture properties through variation of the γ'-precipitation hardening phase. It is explained how cast initial state, heat-treatment, microstructure, and the creep to rupture strength are linked with each other. (orig.)

  11. On Post-Weld Heat Treatment of a Single Crystal Nickel-Based Superalloy Joint by Linear Friction Welding

    Directory of Open Access Journals (Sweden)

    T. J. Ma

    2015-09-01

    Full Text Available Three types of post-weld heat treatment (PWHT, i.e. solution treatment + primary aging + secondary aging (I, secondary aging (II, and primary aging + secondary aging (III, were applied to a single crystal nickel-based superalloy joint made with linear friction welding (LFW. The results show that the grains in the thermomechanically affected zone (TMAZ coarsen seriously and the primary γ' phase in the TMAZ precipitates unevenly after PWHT I. The primary γ' phase in the TMAZ and weld zone (WZ precipitates insufficiently and fine granular secondary γ' phase is observed in the matrix after PWHT II. After PWHT III, the primary γ' phase precipitates more sufficiently and evenly compared to PWHTs I and II. Moreover, the grains in the TMAZ have not coarsened seriously and fine granular secondary γ' phase is not found after PWHT III. PWHT III seems more suitable to the LFWed single crystal nickel-based superalloy joints when performing PWHT.

  12. Investigation of Creep Feed Grinding Parameters and Heat treatment Effects on the Nickel-base Superalloys

    Institute of Scientific and Technical Information of China (English)

    Hasan Jamshidi; Sayed Ali Sadough Vanini; Alireza Attari

    2004-01-01

    The Nickel base Superalloys are the most famous complicated and useable of Superalloys to make hot zone components of the gas turbines. The complicated dimensional tolerances, specially at the root of the blade show importance of grinding processes at the production of blades root. The prediction of the effect of machining parameters on the soundness of component surface strengthening for reaching to a suitable surface finishing and avoiding from crack formation at the work part during machining operation often is not easy and feasible so needs to more industrial investigation.This research is about frame 5 blade designed by GE and made from Superalloy IN738LC has been investigated. The formation of a plastically deformed and heat affected zone during grinding of Superalloy IN738LC with a high depth of cut but slow work speed (creep feed grinding) was investigated. Parameters such as work speed, depth of cut and radial dressing speed have been considered as variables and their effects have been studied. During experimental performed, the voltage and current of motor measured and power and special energy calculated.Some samples heat-treated (of the 1176℃ for 1 hr under neutral argon gas and cooling rate of 15℃/min up to 537℃ and then air cooling) to study grains recrystallization. Other samples have been created from the roots of blades and then coated by Nickel to measure boundary layer micro-hardness. The results show that increasing work speed leads to increasing the use power. Increasing the depth of cut, by increasing material removal rate, and the radial dressing speed, by decreasing power, lead to decreasing special energy. The temperature created by grinding lead to decreasing plastic deformation and boundary layer formation. When the radial dressing speed changes from 1 to 0.6 μm/rev and other parameters are kept unchanged the roughness of surface increases and the special energy decreases. Sufficient dressing is very essential in limiting the width

  13. Influence de l’irradiation et de la radiolyse sur la vitesse et les mécanismes de corrosion des alliages de zirconium

    OpenAIRE

    Verlet, Romain

    2015-01-01

    Le combustible nucléaire des Réacteurs à Eau sous Pression (REP), sous forme de pastilles d’oxyde d’uranium UO2 (ou MOx), est confiné dans un gainage en alliage de zirconium. Ce gainage est très important car il représente la première barrière de confinement contre la dissémination des produits de fission, générés par la réaction nucléaire, vers le milieu extérieur. La corrosion par le milieu primaire des alliages de zirconium, en particulier l’alliage Zircaloy-4, est un des facteurs limitant...

  14. Contribution a l'étude expérimentale et numérique du soudage laser : application aux alliages de magnésium

    OpenAIRE

    BELHADJ, Asma

    2009-01-01

    Ce travail s'intéresse à l'étude du soudage par faisceau laser de l'alliage de magnésium de désignation AM60. Il concerne un volet expérimental et un autre numérique. L'étude expérimentale vise l'investigation des conséquences métallurgiques et mécaniques du procédé sur l'alliage utilisé et la validation des résultats numériques du modèle thermique développé. En premier lieu, une étude paramétrique a permis de déterminer les paramètres du soudage par faisceau laser CO2 de plaques en alliage A...

  15. Modélisation et simulation de la structure de solidification dans les superalliages base-nickel : application AM1

    OpenAIRE

    Ben Hamouda, Haithem

    2012-01-01

    AM1 is a nickel-based superalloy that Snecma relies on to elaborate single crystal turbine blades having complex geometry and high resistance to extreme conditions of temperature and pressure. However, controlling heat flux during solidification process is difficult because of many reasons such as the complex geometry, the way of clustering parts and the superalloy solidification kinetics. Consequently, stray grain nucleation can occur in the undercooling liquid. Therefore, it is important to...

  16. Crack initiation and propagation induced by inclusions in a nickel-base P/M superalloy under fatigue load

    Institute of Scientific and Technical Information of China (English)

    ZENG Yanping; ZHANG Maicang; DONG Jianxin; ZHANG Lina; XIE Xishan

    2005-01-01

    In situ fatigue tests in special designed SEM were conducted to trace the whole process of crack initiation and propagation till to fracture in nickel-base P/M superalloy seeded inclusions. The experimental results show that non-metallic inclusions can induce crack initiation. When the inclusion size is larger than the critical one, the crack can propagate as the main crack that induces the specimen to fracture. As a result, the LCF life of the specimen decreases.

  17. Optimization of Weld Bead Parameters of Nickel Based Overlay Deposited by Plasma Transferred Arc Surfacing with Adequacy Test

    OpenAIRE

    Bhaskarananda Dasgupta; Pinaky Bhadury

    2014-01-01

    Plasma Transferred Arc surfacing is a kind of Plasma Transferred Arc Welding process. Plasma Transferred Arc surfacing (PTA) is increasingly used in applications where enhancement of wear, corrosion and heat resistance of materials surface is required. The shape of weld bead geometry affected by the PTA Welding process parameters is an indication of the quality of the weld. In this paper the analysis and optimization of weld bead parameters, during deposition of a Nickel based...

  18. PREPARATION OF MICROWAVE ABSORBING NICKEL-BASED ACTIVATED CARBON BY ELECTROLESS PLATING WITH PALLADIUM-FREE ACTIVATION

    OpenAIRE

    Boyang Jia; Lijuan Wang

    2010-01-01

    Nickel-based activated carbon was prepared from coconut shell activated carbon by electroless plating with palladium-free activation. The materials were characterized by scanning electron microscopy (SEM), X-ray energy dispersion spectroscopy (EDS), vibrating sample magnetometry (VSM), and vector network analyzer, respectively. The results show that the surface of the activated carbon was covered by a Ni-P coating, which was uniform, compact, and continuous and had an obvious metallic sheen. ...

  19. Damage in nickel base superalloy: Influence of local parameters measured by electron backscattered diffraction and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Risbet, M. [Laboratoire Roberval, UMR 6253 UTC-CNRS, Universite de Technologie de Compiegne, BP 20529-60205 Compiegne cedex (France)], E-mail: marion.risbet@utc.fr; Feaugas, X. [Laboratoire d' Etude des Materiaux en Milieux Agressifs, EA 3127, Universite de La Rochelle, 17000 La Rochelle cedex (France); Guillemer-Neel, C. [Laboratoire de Technologies Innovantes, EA 3899, IUT Genie Mecanique d' Amiens, 80025 Amiens Cedex (France); Clavel, M. [Laboratoire Mecanique des Sols, Structures et Materiaux, UMR 8579 CNRS, Ecole Centrale Paris, 92295 Chatenay-Malabry Cedex (France)

    2009-03-15

    The low-cycle fatigue behaviour of a nickel-based superalloy has been investigated with regard to its surface damage features. This alloy endures localized plastic deformation confined in slip bands emerging as extrusions. The correlations between damage, grain orientation, the Schmid factor of slip systems and the height of extrusions have been questioned. It is proved here that reaching a critical height value is not a sufficient condition for an extrusion to induce the apparition of a transgranular crack.

  20. Damage in nickel base superalloy: Influence of local parameters measured by electron backscattered diffraction and atomic force microscopy

    International Nuclear Information System (INIS)

    The low-cycle fatigue behaviour of a nickel-based superalloy has been investigated with regard to its surface damage features. This alloy endures localized plastic deformation confined in slip bands emerging as extrusions. The correlations between damage, grain orientation, the Schmid factor of slip systems and the height of extrusions have been questioned. It is proved here that reaching a critical height value is not a sufficient condition for an extrusion to induce the apparition of a transgranular crack

  1. Thermomechanical fatigue behavior of coated and bare nickel-based superalloy single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chataigner, E.; Remy, L.

    1996-12-31

    The thermal-mechanical fatigue behavior of chromium-aluminum coated [001] single crystals of AM1, a nickel-base superalloy for turbine blades, is studied using a diamond shape cycle from 600 to 1,100 C. Comparison with bare specimens does not show any significant difference in thermal-mechanical fatigue nor in isothermal low cycle fatigue at high temperature. Metallographic observations on fracture surfaces and longitudinal sections of specimens tested to fatigue life or to a definite fraction of expected life have shown that the major crack tends to initiate from casting micropores in the sub-surface area very early in bare and coated specimens, under low cycle fatigue or thermal-mechanical fatigue. But the interaction between oxidation and fatigue cracking seems to play a major role. A simple model proposed by Reuchet and Remy has been identified for this single crystal superalloy. Its application to the life prediction under low cycle fatigue and thermal-mechanical fatigue for bare and coated single crystals with different orientations is shown.

  2. Methane Decomposition into Carbon Fibers over Coprecipitated Nickel-Based Catalysts

    Institute of Scientific and Technical Information of China (English)

    Yan Ju; Fengyi Li; Renzhong Wei

    2005-01-01

    Decomposition of methane in the presence of coprecipitated nickel-based catalysts to produce carbon fibers was investigated. The reaction was studied in the temperature range of 773 K to 1073 K.At 1023 K, the catalytic activities of three catalysts kept high at the initial period and then decreased with the reaction time. The lifetimes of Ni-Cu-Al and Ni-La-Al catalysts are longer than that of Ni-Al catalyst. With three catalysts, the yield of carbon fibers was very low at 773 K. The yield of carbon fibers for Ni-La-Al catalyst was more than those for Ni-Al and Ni-Cu-Al catalysts. For Ni-La-Al catalyst, the elevation of temperature from 873 K up to 1073 K led gradually to an increase in the yield of carbon fibers.XRD studies on the Ni-La-Al catalyst indicate that La2NiO4 was formed. The formation of La2NiO4 is responsible for the increase in the catalytic lifetime and the yield of carbon fibers synthesized on Ni-La-Al at 773-1073 K. Carbon fibers synthesized on Ni-Al catalyst are thin, long carbon nanotubes. There are bamboo-shaped carbon fibers synthesized on Ni-Cu-Al catalyst. Carbon fibers synthesized on Ni-La-Al catalyst have large hollow core, thin wall and good graphitization.

  3. Effect of tube-electrode inner diameter on electrochemical discharge machining of nickel-based superalloy

    Directory of Open Access Journals (Sweden)

    Zhang Yan

    2016-08-01

    Full Text Available Nickel-based superalloys are widely employed in modern aircraft engines because of their excellent material characteristics, particularly in the fabrication of film cooling holes. However, the high machining requirement of a large number of film cooling holes can be extremely challenging. The hybrid machining technique of tube electrode high-speed electrochemical discharge drilling (TEHECDD has been considered as a promising method for the production of film cooling holes. Compared with any single machining process, this hybrid technique requires the removal of more complex machining by-products, including debris produced in the electrical discharge machining process and hydroxide and bubbles generated in the electrochemical machining process. These by-products significantly affect the machining efficiency and surface quality of the machined products. In this study, tube electrodes in different inner diameters are designed and fabricated, and the effects of inner diameter on the machining efficiency and surface quality of TEHECDD are investigated. The results show that larger inner diameters could effectively improve the flushing condition and facilitate the removal of machining by-products. Therefore, higher material removal efficiency, surface quality, and electrode wear rate could be achieved by increasing the inner diameter of the tube electrode.

  4. Finite element process modelling of inertia friction welding advanced nickel-based superalloy

    International Nuclear Information System (INIS)

    A sequentially coupled thermal and mechanical finite element (FE) model has been developed to describe inertia friction welding (IFW) using the DEFORM 8.2 package. All modelling and experimental work was undertaken on inertia friction welds made from RR1000, which is an advanced high γ' content nickel-based superalloy. The accuracy of the thermal predictions has been assessed by an analysis of γ' distribution across the weld region as compared to those recorded during prescribed thermal simulations, while the mechanical model has been validated by comparing predicted and measured upsets and weld pressures. Finally the residual stress predictions have been compared against measurements (by neutron diffraction). In all cases excellent agreement was found between predicted and experimental data. This exercise revealed that the clamping forces applied during the welding process may have a strong influence on the axial stress field. The validated model was then used to study the effect of welding pressure on material flow, thermal history and residual stresses. The work shows that with increasing weld pressure the width of the heat-affected zone (HAZ) is reduced, while the peak temperature and strain rate is increased. In addition the peak stresses in the hoop direction near the weldline were found to be largely unaffected by the weld pressure. However, for lower welding pressures a broader high tensile hoop stress region was found in accordance with the increased HAZ.

  5. TEMPERATURE EFFECT ON LOW-CYCLE FATIGUE BEHAVIOR OF NICKEL-BASED SINGLE CRYSTALLINE SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    Xianfeng Ma; Huiji Shi; Jialin Gu; Zhaoxi Wang; Harald Harders; Thomas Malow

    2008-01-01

    The low-cycle fatigue (LCF) behavior of a nickel-based single crystal superalloy with [001] orientation was studied at an intermediate temperature of To℃ and a higher temper ature of To + 250℃ under a constant low strain rate of 10-3 s-1 in ambient atmosphere.The superalloy exhibited cyclic tension-compression asymmetry which is dependent on the temper ature and applied strain amplitude.Analysis on the fracture surfaces showed that the surface and subsurface casting mieropores were the major crack initiation sites.Interior Ta-rich carbides were frequently observed in all specimens.Two distinct types of fracture were suggested by frac togaphy.One type was characterized by Mode-Ⅰ cracking with a microscopically rough surface at To + 250℃.Whereas the other type at lower temperature To℃ favored either one or several of the octahedral {111} planes,in contrast to the normal Mode-Ⅰ growth mode typically observed at low loading frequencies (several Hz).The failure mechanisms for two cracking modes are shearing of γ' precipitates together with the matrix at To℃ and cracking confined in the matrix and the γ/γ'interface at To + 250℃.

  6. Electrochemical Deposition of Thick Iron Oxide Films on Nickel Based Superalloy Substrates

    International Nuclear Information System (INIS)

    Iron oxide films have been grown on two nickel-chromium-based superalloys, Inconel 600 and 690, by cathodic electrodeposition from an alkaline Fe(III)-Triethanolamine electrolytic solution. The deposition mechanism has been studied by combining thermodynamic calculations, linear sweep voltammetry and the quartz crystal microbalance techniques. Films have been grown at constant potential ranging between −1.01 and −1.30 V versus the saturated calomel electrode (SCE). They have been thoroughly characterized by scanning electron microscopy, focused ion beam, magnetometry and X-ray diffraction. Magnetite (Fe3O4) is deposited between −1.01 and −1.09 V vs. SCE. Between −1.10 and −1.20 V vs. SCE a dual layered structure composed of a dense inner layer and a porous outer thick layer is obtained. These duplex structures are shown to be mainly composed of magnetite and contain some maghemite. Below −1.20 V vs.SCE, a dense metallic iron layer is deposited. We have defined experimental protocol parameters to grow dense, highly crystallized, adhesive, magnetite films with controlled thicknesses up 50 μm. These magnetite films show a high saturation magnetization of 91.6 emu g−1 and a small coercivity of 40 Oe

  7. Studies on the hot corrosion of a nickel-base superalloy, Udimet 700

    Science.gov (United States)

    Misra, A. K.

    1986-01-01

    The hot corrosion of a nickel-base superalloy, Udimet 700, was studied in the temperture range of 884 to 965 C and with different amounts of Na2SO4. Two different modes of degradation were identified: (1) formation of Na2MoO4-MoO3 melt and fluxing by this melt, and (2) formation of large interconnected sulfides. The dissolution of Cr2O3, TiO2 in the Na2SO4 melt does not play a significnt role in the overall corrosion process. The conditions for the formation of massive interconnected sulfides were identified and a mechanism of degradation due to sulfide formation is described. The formation of Na2MoO4-MoO3 melt requires an induction period and various physiochemical processes during the induction period were identified. The factors affecting the length of the induction period were also examined. The melt penetration through the oxide appears to be the prime mode of degradation whether the degradation is due to the formation of sulfides or the formation of the Na2MoO4-MoO3 melt.

  8. Radiographical determination of internal stresses in the nickel base superalloy SRR 99

    International Nuclear Information System (INIS)

    Examinations are presented of local lattice parameters and internal stresses determined therefrom, in the single crystalline, γ'-hardened nickel base superalloy SRR 99. Specimens of this aircraft turbine blade alloy were investivated in undeformed state and after high temperature creep deformation with the aid of a two-crystal diffractometer with negligible instrumental X-ray line broadening between room temperature and deformation temperatures fromm 750 C to 1050 C. From the X-ray line profiles, the lattice constants of the phase γ and γ', the bad fitting of lattices and the elastical lattice distortions were determined. From these elastical strains, the deformation-induced and the thermally induced, far reaching internal stresses can be calculate, and extrapolations can be made to the local shearing stresses, effective in the phases, and consequently on the deformation mechanisms. In addition, the results are compared with the data of supplementing transmission electron-microscopical examinations (illustration of dislocation networks and deflection in the convergent electron beam (CBED)). (orig.)

  9. Effects of neutron irradiation on deformation behavior of nickel-base fastener alloys

    International Nuclear Information System (INIS)

    This paper presents the effects of neutron irradiation on the fracture behavior and deformation microstructure of high-strength nickel-base alloy fastener materials, Alloy X-750 and Alloy 625. Alloy X-750 in the HTH condition, and Alloy 625 in the direct aged condition were irradiated to a fluence of 2.4x1020 n/cm2 at 264 C in the Advanced Test Reactor. Deformation structures at low strains were examined. It was previously shown that Alloy X-750 undergoes hardening, a significant degradation in ductility and an increase in intergranular fracture. In contrast, Alloy 625 had shown softening with a concomitant increase in ductility and transgranular failure after irradiation. The deformation microstructures of the two alloys were also different. Alloy X-750 deformed by a planar slip mechanism with fine microcracks forming at the intersections of slip bands with grain boundaries. Alloy 625 showed much more homogeneous deformation with fine, closely spaced slip bands and an absence of microcracks. The mechanism(s) of irradiation assisted stress corrosion cracking (IASCC) are discussed

  10. Fatigue-crack propagation response of two nickel-base alloys in a liquid sodium environment

    International Nuclear Information System (INIS)

    The elevated temperature fatigue-crack propagation response of Inconel 600 and Inconel 718 was characterized within a linear-elastic fracture mechanics framework in air and low-oxygen liquid sodium environments. The crack growth rates of both nickel-base alloys tested in liquid sodium were found to be considerably lower than those obtained in air. This enhanced fatigue resistance in sodium was attributed to the very low oxygen content in the inert sodium environment. Electron fractographic examination of the Inconel 600 and Inconel 718 fatigue fracture surfaces revealed that operative crack growth mechanisms were dependent on the prevailing stress intensity level. Under low growth rate conditions, Inconel 600 and Inconel 718 fracture surfaces exhibited a faceted, crystallographic morphology in both air and sodium environments. In the higher growth rate regime, fatigue striations were observed; however, striations formed in sodium were rather ill-defined. These indistinct striations were attributed to the absence of oxygen in the liquid sodium environment. Striation spacing measurements were found to be in excellent agreement with macroscopic growth rates in both environments

  11. Characterization of a microfluidic microbial fuel cell as a power generator based on a nickel electrode.

    Science.gov (United States)

    Mardanpour, Mohammad Mahdi; Yaghmaei, Soheila

    2016-05-15

    This study reports the fabrication of a microfluidic microbial fuel cell (MFC) using nickel as a novel alternative for conventional electrodes and a non-phatogenic strain of Escherichia coli as the biocatalyst. The feasibility of a microfluidic MFC as an efficient power generator for production of bioelectricity from glucose and urea as organic substrates in human blood and urine for implantable medical devices (IMDs) was investigated. A maximum open circuit potential of 459 mV was achieved for the batch-fed microfluidic MFC. During continuous mode operation, a maximum power density of 104 Wm(-3) was obtained with nutrient broth. For the glucose-fed microfluidic MFC, the maximum power density of 5.2 μW cm(-2) obtained in this study is significantly greater than the power densities reported previously for microsized MFCs and glucose fuel cells. The maximum power density of 14 Wm(-3) obtained using urea indicates the successful performance of a microfluidic MFC using human excreta. It features high power density, self-regeneration, waste management and a low production cost (<$1), which suggest it as a promising alternative to conventional power supplies for IMDs. The performance of the microfluidic MFC as a power supply was characterized based on polarization behavior and cell potential in different substrates, operational modes, and concentrations. PMID:26720922

  12. Corrosion and Sliding Properties of the Nickel-Based Alloys for the Valve Seats Application

    International Nuclear Information System (INIS)

    This paper describes the experiments of the corrosion and the sliding tests of the nickel-based alloys for the gate valve seating materials used at high pressure and temperature. The general corrosion rates and IGC susceptibility are tested in pressurized water at 533 K and 575 k and in Strauss test solution. The sliding tests have been done in pressurized water at 293 k, 473 K and 573 k. The alloys containing above 10% chromium may have the anti-corrosion properties that could be applied to the valve seats for the power plants. The good sliding performance and the good pressure tightness are obtained when the disc specimens that have hardness 500 to 600 Hv combined with the seat specimens that have hardness 250 to 410 Hv containing about 40 percent of iron. The large size gate valves sliding tests have certified the test results. The anti-wear properties of the seat alloy and the anti-IGC susceptibility of the disc alloy could be improved by the addition of silicon and niobium, respectively

  13. Effects of neutron irradiation on deformation behavior of nickel-base fastener alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bajaj, R.; Mills, W.J.; Kammenzind, B.F.; Burke, M.G.

    1999-07-01

    This paper presents the effects of neutron irradiation on the fracture behavior and deformation microstructure of high-strength nickel-base alloy fastener materials, Alloy X-750 and Alloy 625. Alloy X-750 in the HTH condition, and Alloy 625 in the direct aged condition were irradiated to a fluence of 2.4x10{sup 20} n/cm{sup 2} at 264 C in the Advanced Test Reactor. Deformation structures at low strains were examined. It was previously shown that Alloy X-750 undergoes hardening, a significant degradation in ductility and an increase in intergranular fracture. In contrast, Alloy 625 had shown softening with a concomitant increase in ductility and transgranular failure after irradiation. The deformation microstructures of the two alloys were also different. Alloy X-750 deformed by a planar slip mechanism with fine microcracks forming at the intersections of slip bands with grain boundaries. Alloy 625 showed much more homogeneous deformation with fine, closely spaced slip bands and an absence of microcracks. The mechanism(s) of irradiation assisted stress corrosion cracking (IASCC) are discussed.

  14. Development of composites based on lithium manganese nickel oxide and electroactive polymers

    International Nuclear Information System (INIS)

    A new composite cathode-active material based on lithium manganese nickel oxide (LiMn2-xNixO4), poly(2,5-dimercapto-1,3,4-thiadiazole) (PDMcT) and polyaniline (PAni) was synthesized. The formation of the uniform and well-connected polymer film on the surface of LiMn2-xNixO4 particles was confirmed by Fourier-transform infrared spectra (FT-IR) and scanning electronic micrographs (SEM). The amounts of each constituent cannot be separately determined by thermogravimetric analysis (TGA). By galvanostatic charge-discharge tests, the PAni/PDMcT/LiMn2-xNixO4 composite showed a better electrochemical performance than each single component (PAni, PDMcT and LiMn2-xNixO4) and binary composites (PAni/LiMn2-xNixO4 and PDMcT/LiMn2-xNixO4). The electrical conductivity of the ternary composite reached 11.9 S cm-1 and an initial discharge capacity of 305 mAh g-1 was obtained. After 10 cycles, the coulombic efficiency and retention capacity was 99% and 90%, respectively. All results indicate a synergic effect among the materials in the composite

  15. Microstructural evolution and castability prediction in newly designed modern third-generation nickel-based superalloys

    Science.gov (United States)

    Naffakh-Moosavy, Homam

    2016-05-01

    The present research aims to establish a quantitative relation between microstructure and chemical composition (i.e., Ti, Al, and Nb) of newly designed nickel-based superalloys. This research attempts to identify an optimum microstructure at which the minimum quantities of γ/γ' and γ/γ″ compounds are achieved and the best castability is predicted. The results demonstrate that the highest quantity of intermetallic eutectics (i.e., 41.5wt%) is formed at 9.8wt% (Ti + Al). A significant quantity of intermetallics formed in superalloy 1 (with a composition of γ - 9.8wt% (Ti + Al)), which can deteriorate its castability. The type and morphology of the eutectics changed and the amount considerably decreased with decreasing Ti + Al content in superalloy 2 (with a composition of γ - 7.6wt% (Ti + Al), 1.5wt% Nb). Thus, it is predicted that the castability would improve for superalloy 2. The same trend was observed for superalloy 4 (with a composition of γ - 3.7wt% (Ti + Al), 4.4wt% Nb). This means that the amount of Laves increases with increasing Nb (to 4.4wt%) and decreasing Ti + Al (to 3.7wt%) in superalloy 4. The best castability was predicted for superalloy 3 (with a composition of γ - 5.7wt% (Ti + Al), 2.8wt% Nb).

  16. Tensile behaviors and deformation mechanisms of a nickel-base single crystal superalloy at different temperatures

    International Nuclear Information System (INIS)

    The tensile behaviors of an experimental nickel-base single crystal superalloy have been studied from room temperature to 1100 °C. Obvious work hardening during the tensile tests from room temperature to 760 °C has been observed. In contrast, at 900 °C and 1000 °C only a slight work hardening occurs. Furthermore, by using transmission electron microscopy (TEM), the microstructures of the alloy after tensile tests at various temperatures have been investigated. Detailed analysis demonstrates the stacking faults (SFs) presented in the γ matrix at room temperature, 600 °C and 760 °C, which were seldom reported previously. These stacking faults are responsible for the appearance of stress jump (named steps) on the stress–strain curves. On the other hand, these stacking faults effectively prevent slipping of the dislocations and have a great contribution to work hardening. Apart from that, the stacking faults in γ' precipitates from room temperature to 900 °C have also been observed. The interfacial dislocation networks at 1000 °C and 1100 °C cause a weak resistance to the slip dislocations because of the high flow stress. The a/3<121> and a/2<011> type dislocations are of vital importance for plastic deformation and rupture of the experimental alloy. At last, the relation between deformation mechanisms and tensile behaviors has been reasonably explained

  17. Fatigue life and fatigue crack growth of the ods nickel-base superalloy PM 1000

    International Nuclear Information System (INIS)

    Fatigue crack growth (FCG) and fatigue life (LCF and HCF) of the oxide dispersion strengthened (ODS) nickel-base superalloy PM 1000 have been studied at 850 oC on strongly textured bar (GAR=10) and sheet material (GAR=4). Specimens were prepared with their axis parallel to the and (sheet only) directions, resp. The fatigue tests were performed under total strain control in the LCF regime and under stress control for HW and FCG testing. In the HW range, shorter lives were observed with specimens as compared to ones. The opposite is true in the LCF range where longer lives are found in -specimens. In fatigue crack growth studies, the threshold values obtained for FCG in direction are higher than those of direction. This finding is in accordance with the orientation dependence of Young's modulus and strength level. In order to evaluate the potential of additional γ'-hardening, PM 3030 has been included into our investigations. At 850 oC, a coarse elongated grained variant (GAR>100 showed much better HW properties than PM 1000. (author)

  18. Inner and outer pressure forming of nickel based super-alloy thin-walled part with variable diameter sections

    Institute of Scientific and Technical Information of China (English)

    WANG Zhong-jin; GAO Tie-jun

    2008-01-01

    A novel forming method of nickel based super-alloy thin-walled part with variable diameter sections was proposed by using inner and outer pressure with the visco-elasto-plastic pressure-carrying medium at room temperature, and the principle of the method was provided. Experiments and FE simulations were carried out to analyze the deformation characteristics for the part with larger variable diameter ratio (35%). The results show that visco-elasto-plastic pressure-carrying medium can meet the requirements of the room-temperature deformation condition for nickel based super-alloy sheet. The inner and outer pressure forming with the visco-elasto-plastic pressure-carrying medium can meet the requirements of dimensional accuracy for the thin-walled part with variable diameter sections. The thinning of wall-thickness is less than 4%. This method provides a new approach for near-net shape forming of nickel based super-alloy thin-walled parts with variable diameter sections.

  19. The Effects of Stress Triaxiality, Temperature and Strain Rate on the Fracture Characteristics of a Nickel-Base Superalloy

    Science.gov (United States)

    Wang, Jianjun; Guo, Weiguo; Guo, Jin; Wang, Ziang; Lu, Shengli

    2016-04-01

    In this work, to study the effects of stress triaxiality, temperature, and strain rate on the fracture behaviors of a single-crystal Nickel-base superalloy, a series of experiments over a temperature range of 293 to 1373 K, strain rate range of 0.001 to 4000/s, and stress triaxiality range of -0.6 to 1.1 are conducted. Anomalous peak of stress is noticed in the yield stress versus temperature curves, and strain rate effect on the anomalous peak of yield stress is analyzed. The anomalous peak shifts to higher temperature as the strain rate increases. Then the effects of stress triaxiality, temperature, and strain rate on its fracture behaviors, including strain to fracture, path of crack propagation, and fracture surface, are observed and analyzed. A valley of the fracture strain is formed in the fracture strain versus temperature curve over the selected temperature range. The micrograph of fracture surface is largely dependent on the temperature, stress triaxiality, and strain rate. Finally, the original Johnson-Cook (J-C) fracture criterion cannot describe the effect of stress triaxiality and temperature on the fracture behaviors of single-crystal Nickel-base superalloy. A modified J-C fracture criterion is developed, which takes the anomalous stress triaxiality and temperature effects on the fracture behaviors of single-crystal Nickel-base superalloy into account.

  20. The Effects of Stress Triaxiality, Temperature and Strain Rate on the Fracture Characteristics of a Nickel-Base Superalloy

    Science.gov (United States)

    Wang, Jianjun; Guo, Weiguo; Guo, Jin; Wang, Ziang; Lu, Shengli

    2016-05-01

    In this work, to study the effects of stress triaxiality, temperature, and strain rate on the fracture behaviors of a single-crystal Nickel-base superalloy, a series of experiments over a temperature range of 293 to 1373 K, strain rate range of 0.001 to 4000/s, and stress triaxiality range of -0.6 to 1.1 are conducted. Anomalous peak of stress is noticed in the yield stress versus temperature curves, and strain rate effect on the anomalous peak of yield stress is analyzed. The anomalous peak shifts to higher temperature as the strain rate increases. Then the effects of stress triaxiality, temperature, and strain rate on its fracture behaviors, including strain to fracture, path of crack propagation, and fracture surface, are observed and analyzed. A valley of the fracture strain is formed in the fracture strain versus temperature curve over the selected temperature range. The micrograph of fracture surface is largely dependent on the temperature, stress triaxiality, and strain rate. Finally, the original Johnson-Cook (J-C) fracture criterion cannot describe the effect of stress triaxiality and temperature on the fracture behaviors of single-crystal Nickel-base superalloy. A modified J-C fracture criterion is developed, which takes the anomalous stress triaxiality and temperature effects on the fracture behaviors of single-crystal Nickel-base superalloy into account.

  1. Hot isostatic pressing process to rejuvenate serviced cast nickel base superalloy IN738 turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Wangyao, P. [Chulalongkorn Univ., Bangkok (TH). Metallurgy and Materials Science Research Institute (MMRI); Zrnik, J. [Technical Univ. of Kosice (Czech Republic). Dept. of Materials Science; Polsilapa, S. [Kasetsart Univ., Bangkok (Thailand). Dept. of Materials Engineering, Engineering Faculty; Nisaratanaporn, E. [Chulalongkorn Univ., Bangkok (Thailand). Dept. of Metallurgy Engineering, Engineering Faculty; Homkrajai, W. [Electricity Generating Authority of Thailand (EGAT), Nonthaburi (Thailand)

    2006-07-01

    Many of land base gas turbines for power plants are already long-time operating and lots of efforts were brought to evaluate the remnant life of turbine components. The aims is to assess the actual conditions of the material used for critical components are sustainable with respect to remaining life judgement. The present work provides information on land-base gas turbine first-stage turbine blade structure degradation due to long-term thermomechanical and environmental exposure. The virgin blade was of cast and heat treated nickel base superalloy IN 738 and prior examination it was exposed more than 70 000 hours at turbine inlet temperature, operating by Electricity Generating Authority of Thailand (EGAT) company. The pieces, differently localized along the blade, were cut off for microstructural analyses, which were performed using light and scanning electron microscopy. After long-term service the gamma prime coarsening, re-precipitation of finer gamma prime precipitates and grain boundary carbide precipitates dissolving were observed. The most degraded microstructure was found at top part of trailing edge and at the middle leading edge of blade where small cracks, pores and nests of voids were observed. In order to find proper condition to recover the microstructure the attempt of rejuvenation involving hot isostatic pressing (HIP) followed by standard heat treatment of IN 738 alloy was employed to pieces of the blade. The series of HIP treatments at two different temperatures and at different holds have been conducted. This process appeared to be successful in healing of micro voids and pores in interior of blade, but no restoration of surface defects was observed. Increasing the HIP temperature and extending the HIP time higher efficiency for micro voids and porosity closing were observed. (orig.)

  2. Thermo-mechanical fatigue behavior of a single crystal nickel-based superalloy

    International Nuclear Information System (INIS)

    Highlights: → The thermo-mechanical fatigue life of OP TMF is shorter than that of IP TMF. This is mainly attributed to the maximum tensile stress level at the minimum temperature. → Under out-of-phase condition, damage is controlled by oxidation. While under in-phase condition, damage is controlled by creep. → In terms of the fracture surface and microstructural evolution under different conditions, deformation and damage mechanisms are explained based on the relative contribution of oxidation, creep and fatigue. - Abstract: Thermo-mechanical fatigue (TMF) behavior in a oriented nickel-based single crystal superalloy was investigated under different cycles of strain and temperature. Fracture surface and microstructural evolution were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. It was found that the fatigue lives under in-phase (IP) TMF were longer than those of out-of-phase (OP) TMF, and the maximum tensile stress level was concluded to be the lifetime-limiting factor. Compared to isothermal low-cycle fatigue (LCF) lives obtained under the maximum temperature 900 deg. C, thermo-mechanical fatigue lifetime was much shorter. This result indicates that varying temperature superimposed mechanical strain greatly reduces the fatigue lifetime of superalloys. Based on observation of fracture surface and microstructure evolution, it was concluded that creep is the dominant damage mechanism under IP-TMF condition and oxidation causes shorter lifetime for OP-TMF tests. The similarities and differences in the changes of γ' morphology during in-phase (IP) and out-of-phase (OP) TMF tests were also discussed.

  3. Caractérisation et compréhension du comportement en corrosion de structures en alliage d'aluminium-cuivre-lithium 2050 assemblées par Friction Stir Welding (FSW)

    OpenAIRE

    Proton, Vincent

    2012-01-01

    A l'heure où les matériaux composites prennent une part toujours plus importante dans les structures aéronautiques, l'utilisation de l'alliage d'aluminium-lithium 2050 assemblé par Friction Stir Welding (FSW) est envisagé pour remplacer les structures rivetées en alliages d'aluminium traditionnels. L'objectif global de ce travail de thèse était d'étudier le comportement en corrosion et en corrosion sous contrainte de joints soudés FSW de l'alliage d'aluminium-lithium 2050 mais aussi l'influen...

  4. Genèse des microstructures lors du soudage par friction malaxage d'alliages d'aluminium de la série 2000 & 5000 et comportement mécanique résultant

    OpenAIRE

    Genevois, Cécile

    2004-01-01

    L'alliage 2024 (Al-Cu-Mg) est utilisé dans le cadre de l'allègement des structures de transport. Cependant, cet alliage est difficilement soudable par voie classique. Le soudage par friction malaxage (FSW) est un nouveau procédé permettant l'assemblage à l'état solide et donc de supprimer les défauts liés à la solidification. A travers cette étude, les microstructures de soudures FSW de cet alliage ont été finement caractérisées par SAXS, DSC, MET, MEB, EBSD et microscopie optique. Afin de me...

  5. Etude des méthodes d’ingénierie de bandes par les alliages semiconducteurs et leur rôle en photovoltaïque.

    OpenAIRE

    HAMIDI, Hocine

    2015-01-01

    L’ingénierie des bandes par les alliages semiconducteurs a ouvert une boite de pandore pour les chercheurs, puisqu’il est possible avec cette technique d’atteindre n’importe quelle bande interdite en partant seulement de deux ou trois matériaux semiconducteurs purs. Le coefficient stoechiométrique de l’alliage semiconducteur s’avère être un paramètre clé dans cette ingénierie, et plusieurs applications ont pu voir le jour grâce à cette technique, surtout dans le domaine opto-électronique (las...

  6. Development of dispersive liquid-liquid microextraction based on solidification of floating organic drop for the determination of trace nickel.

    Science.gov (United States)

    Wang, Yukun; Zhang, Jingwen; Zhao, Bin; Du, Xin; Ma, Jingjun; Li, Jingci

    2011-12-01

    A liquid-phase microextraction technique was developed using dispersive liquid-liquid microextraction based on solidification of floating organic drop combined with flame atomic absorption spectrometry, for the extraction and determination of trace amounts of nickel in water samples. Microextraction efficiency factors, such as the type and volume of extraction and dispersive solvents, pH, extraction time, the chelating agent amount, and ionic strength, were investigated and optimized. Under optimum conditions, the calibration graph was linear in the range of 4.23-250 μg L(-1) with a detection limit of 1.27 μg L(-1). The relative standard deviation for ten replicate measurements of 10 and 100 μg L(-1) of nickel were 3.21% and 2.55%, respectively. The proposed method was assessed through the analysis of certified reference water or recovery experiments. PMID:21598026

  7. The French regulatory experience and views on nickel-base alloy PWSCC prevention and treatment

    International Nuclear Information System (INIS)

    This paper presents the experience feedback and views of the French Regulatory Authority (ASN) and of the technical support institute (IRSN) on PWSCC prevention since the initiation in 1989 of the 'Inconel Zones Review' requested by ASN to Electricite de France (EDF), the national operator of a fleet of 58 PWRs. This proactive requirement, launched before the discovery, in September 1991, of the only CRDM nozzle leak in France, on Bugey unit 3, was then triggered by the recurrence of many alloy 600 rapid degradations and leaks, world wide, and also in France in the late 1980's, particularly on steam generator tubes and on some pressurizer penetrations. Thus, the ASN requested that EDF, perform a comprehensive (generic) proactive assessment on all the nickel-base alloy components and parts of the main primary circuits, which of course included vessel head penetrations and bottom vessel head penetrations, and some other zones as a first priority. This proactive 'review' did, a minima, include the following tasks and actions: - Update and complete, by an extensive R and D program, the understanding and characterization of the Ni base alloys prone to PWSCC, - Analyze the various materials, metallurgical features, mechanical stresses, and physicochemical conditions of the parts exposed to primary water, in order to predict the occurrence of PWSCC initiation and propagation, - Provide a prioritization of the zones to be inspected, - Implement by improved NDE techniques a practical inspection program on the 58 PWRs, - Prepare and implement any needed mitigation actions as a result of the components conditions assessment. The present paper relates the main features of the French regulatory experience over more than 13 years and recalls the main principles of the assessment, which were applied by ASN. These principles, which are formalized in the current regulation rules revised in 1999, are briefly listed hereunder: - It is based on avoiding and preventing any leaking on

  8. Metallographic examination of TD-nickel base alloys. [thermal and chemical etching technique evaluation

    Science.gov (United States)

    Kane, R. D.; Petrovic, J. J.; Ebert, L. J.

    1975-01-01

    Techniques are evaluated for chemical, electrochemical, and thermal etching of thoria dispersed (TD) nickel alloys. An electrochemical etch is described which yielded good results only for large grain sizes of TD-nickel. Two types of thermal etches are assessed for TD-nickel: an oxidation etch and vacuum annealing of a polished specimen to produce an etch. It is shown that the first etch was somewhat dependent on sample orientation with respect to the processing direction, the second technique was not sensitive to specimen orientation or grain size, and neither method appear to alter the innate grain structure when the materials were fully annealed prior to etching. An electrochemical etch is described which was used to observe the microstructures in TD-NiCr, and a thermal-oxidation etch is shown to produce better detail of grain boundaries and to have excellent etching behavior over the entire range of grain sizes of the sample.

  9. Effect of palladium diffusion in coatings deposited on the nickel based superalloy

    Directory of Open Access Journals (Sweden)

    M. Zagula-Yavorska

    2011-12-01

    Full Text Available Purpose: In this paper the effect of palladium diffusion in coatings deposited on the surface of nickel based superalloy was evaluated.Design/methodology/approach: The palladium coatings 3 and 7 μm thick were deposited by the electroplating process on Inconel 713 LC Ni-base superalloy. The heat treatment of electroplated coatings at the temperature 1050°C for 2 h under argon atmosphere was performed. The microstructure investigations of the heat treated coatings were conduced by the use of optical microscope (Nikon Epiphot 300 and a scanning electron microscope (Hitachi S-3400N equipped with an Energy Dispersive Spectroscope EDS (VOYAGER of NORAN INSTRUMENTS. The phase composition was identified by X-ray (ARL X’TRAX diffractometer. The surface roughness parameter - Ra of heat treated coatings was evaluated by Perthometer S2 MAHR equipment.Findings: The microstructure of 3 µm thick palladium electroplated coating after diffusion treatment consists of three phases: AlPd2, Ni3Al, Ni0,52Pd0,475. The increase of palladium thickness from 3 to 7 μm does not influence the phase composition of heat treated coatings. Heat treatment of palladium electroplating coatings increases the surface roughness parameter Ra.Research limitations/implications: The results will be used in the future investigations to explain the influence of palladium on the oxidation resistance of aluminide coatings.Practical implications: The palladium electroplating coatings after heat treatment and aluminizing process may be used as an alternative to platinum modified aluminide coatings as coatings for turbine blades of aircraft engines.Originality/value: The paper includes the results of microstructure and surface roughness investigations of palladium electroplating coatings 3 and 7 µm thick after diffusion treatment. Inconel 713 LC; Palladium electroplating; Diffusion treatment; Surface roughness

  10. Sintering and microstructure evolution of columnar nickel-based superalloy sheets prepared by EB-PVD

    International Nuclear Information System (INIS)

    Research highlights: → EB-PVD technology is commonly used to deposit thermal barrier coatings (TBCs) and columnar structure is commonly seen in EB-PVD condensates. The unique columnar structure can provide outstanding resistance against thermal shock and mechanical strains for TBCs. However, a number of researchers have found that the columnar structure can affect the mechanical properties of EB-PVD alloy thin sheet significantly. As yet, works on how to reduce this kind of effects are seldom done. In the present article, we tried to reveal the sintering effects on microstructure evolution and mechanical properties of columnar Ni-based superalloy sheet. The results suggests that after sintering, the columnar structure degrades. Degradation depends on sintering temperature and time. Both the ultimate tensile strength and the elongation percentage are effectively improved after sintering. - Abstract: A ∼0.15 mm-thick columnar nickel-based superalloy sheet was obtained by electron beam physical vapor deposition (EB-PVD). The as-deposited alloy sheet was sintered at different conditions. The microstructure of the specimens before and after sintering was characterized by using scanning electron microscopy. An X'Pert texture facility was used to determine the crystallographic orientation of the as-deposited alloy sheet. The phase transformation was investigated by X-ray diffraction. Tensile tests were conducted at room temperature on as-deposited and sintered specimens. The results show that the as-deposited sheet is composed of typical columnar structures. After sintering, however, the columnar structure degrades. The degradation depends on sintering temperature and time. Both the ultimate tensile strength and the elongation percentage are effectively improved after sintering.

  11. X-ray residual stress measurement on weld metal of nickel based alloy

    International Nuclear Information System (INIS)

    Residual stress on the weld metal of nickel based alloy was evaluated through x-ray diffraction and metallurgical study of the microstructure. Weld metal specimens were prepared from Alloy182 (JIS DNiCrFe-3) and Alloy132 (JIS DNiCrFe-1J) deposited on a steel plate. X-ray diffraction results show a strong [100] preferred orientation nearly normal to the surface of the weld metal. Crystallographic consideration predicts that dominant 311 diffractions appear around 25.2 and 72.5 degrees of ψ angle. For each diffraction, the peak shift was measured at the ψ angle showing the maximum diffraction intensity, using the side-inclination method (ψ-goniometer method) with a Mn x-ray tube and a PSPC (position sensitive proportional counter). The residual stress was determined by the peak shifts according to the two tilt method. The x-ray stress constant, K, on Alloy182 was determined experimentally. The depth profile of the residual stress was measured on the ground specimens with and without laser peening. Tensile residual stress due to the grinding work is observed in the surface layer of the unpeened specimen; however it changes to compressive after laser peening. The overall behavior of the depth profile of laser peened material agrees well with that of Alloy600 base metal measured in the previous studies, where the compressive residual stress with several hundred MPa at the surface gradually decreases and reaches to around 0 MPa at the depth of about 1 mm. (author)

  12. Generalized corrosion of nickel base alloys in high temperature aqueous media: a contribution to the comprehension of the mechanisms

    International Nuclear Information System (INIS)

    In France, nickel base alloys, such as alloy 600 and alloy 690, are the materials constituting steam generators (SG) tubes of pressurized water reactors (PWR). The generalized corrosion resulting from the interaction between these alloys and the PWR primary media leads, on the one hand, to the formation of a thin protective oxide scale (∼ 10 nm), and on the other hand, to the release of cations in the primary circuit, which entails an increase of the global radioactivity of this circuit. The goal of this work is to supply some new comprehension elements about nickel base alloys corrosion phenomena in PWR primary media, taking up with underlining the effects of metallurgical and physico-chemical parameters on the nature and the growth mechanisms of the protective oxide scale. In this context, the passive film formed during the exposition of alloys 600, 690 and Ni-30Cr, in conditions simulating the PWR primary media, has been analyzed by a set of characterization techniques (SEM, TEM, PEC and MPEC, XPS). The coupling of these methods leads to a fine description, in terms of nature and structure, of the multilayered oxide forming during the exposition of nickel base alloys in primary media. Thus, the protective part of the oxide scale is composed of a continuous layer of iron and nickel mixed chromite, and Cr2O3 nodules dispersed at the alloy / mixed chromite interface. The study of protective scale growth mechanisms by tracers and markers experiments reveals that the formation of the mixed chromite is the consequence of an anionic mechanism, resulting from short circuits like grain boundaries diffusion. Besides, the impact of alloy surface defects has also been studied, underlining a double effect of this parameter, which influences the short circuits diffusion density in oxide and the formation rate of Cr2O3 nodules. The sum of these results leads to suggest a description of the nickel base alloys corrosion mechanisms in PWR primary media and to tackle some

  13. A study of graphene films synthesized on nickel substrates: existence and origin of small-base-area peaks

    International Nuclear Information System (INIS)

    Large-area graphene films, synthesized by the chemical vapor deposition (CVD) method, have the potential to be used as electrodes. However, the electrical properties of CVD-synthesized graphene films fall short of the best results obtained for graphene films prepared by other methods. Therefore, it is important to understand the reason why these electrical properties are inferior to improve the applicability of CVD-grown graphene films. Here, we show that CVD-grown graphene films on nickel substrates contain many small-base-area (SBA) peaks that scatter conducting electrons, thereby decreasing the Hall mobility of charges in the films. These SBA peaks were induced by small peaks on the nickel surface and are likely composed of amorphous carbon. The formation of these SBA peaks on graphene films was successfully suppressed by controlling the surface morphology of the nickel substrate. These findings may be useful for the development of a CVD synthesis method that is capable of producing better quality graphene films with large areas.

  14. Highly sensitive nonenzymatic glucose sensor based on nickel nanoparticle-attapulgite-reduced graphene oxide-modified glassy carbon electrode.

    Science.gov (United States)

    Shen, Zongxu; Gao, Wenyu; Li, Pei; Wang, Xiaofang; Zheng, Qing; Wu, Hao; Ma, Yuehui; Guan, Weijun; Wu, Songmei; Yu, Yu; Ding, Kejian

    2016-10-01

    In this article, a fast and sensitive nonenzymatic glucose sensor is reported utilizing a glassy carbon electrode modified by synthesizing nanocomposites of nickel nanoparticle-attapulgite-reduced graphene oxide (Ni NPs/ATP/RGO). A facile one-step electrochemical co-deposition approach is adopted to synthesize Ni NPs-ATP-RGO nanocomposites via electrochemical reduction of mixed precursor solution containing graphene oxide (GO), attapulgite (ATP) and nickel cations (Ni(2+)) at the cathode potentials. This strategy results in simultaneous depositions of ATP, cathodic reduction of Ni(2+) into nickel nanoparticles under acidic conditions, and in situ reduction of GO. The as-prepared NiNPs/ATP/RGO-based glucose sensor exhibits outstanding performance for enzymeless glucose sensing with sensitivity (1414.4 μAmM(-1)cm(-2)), linear range (1-710μM) and detection limit (0.37μM). What is more, the sensor has excellent stability and selectivity against common interferences in real sample. PMID:27474298

  15. Comparative coarsening kinetics of gamma prime precipitates in nickel and cobalt base superalloys

    Science.gov (United States)

    Meher, Subhashish

    The increasing technological need to push service conditions of structural materials to higher temperatures has motivated the development of several alloy systems. Among them, superalloys are an excellent candidate for high temperature applications because of their ability to form coherent ordered precipitates, which enable the retention of high strength close to their melting temperature. The accelerated kinetics of solute diffusion, with or without an added component of mechanical stress, leads to coarsening of the precipitates, and results in microstructural degradation, limiting the durability of the materials. Hence, the coarsening of precipitates has been a classical research problem for these alloys in service. The prolonged hunt for an alternative of nickel base superalloys with superior traits has gained hope after the recent discovery of Co-Al-W based alloys, which readily form high temperature gamma' precipitates, similar to Ni base superalloys. In the present study, coarsening behavior of gamma' precipitates in Co-10Al-10W (at. %) has been carried out at 800°C and 900°C. This study has, for the first time, obtained critical coarsening parameters in cobalt-base alloys. Apart from this, it has incorporated atomic scale compositional information across the gamma/gamma' interfaces into classical Cahn-Hilliard model for a better model of coarsening kinetics. The coarsening study of gamma' precipitates in Ni-14Al-7 Cr (at. %) has shown the importance of temporal evolution of the compositional width of the gamma/gamma' interfaces to the coarsening kinetics of gamma' precipitates. This study has introduced a novel, reproducible characterization method of crystallographic study of ordered phase by coupling of orientation microscopy with atom probe tomography (APT). Along with the detailed analysis of field evaporation behaviors of Ni and Co superalloys in APT, the present study determines the site occupancy of various solutes within ordered gamma' precipitates

  16. Microstructural indicators of transition mechanisms in time-dependent fatigue crack growth in nickel base superalloys

    Science.gov (United States)

    Heeter, Ann E.

    Gas turbine engines are an important part of power generation in modern society, especially in the field of aerospace. Aerospace engines are design to last approximately 30 years and the engine components must be designed to survive for the life of the engine or to be replaced at regular intervals to ensure consumer safety. Fatigue crack growth analysis is a vital component of design for an aerospace component. Crack growth modeling and design methods date back to an origin around 1950 with a high rate of accuracy. The new generation of aerospace engines is designed to be efficient as possible and require higher operating temperatures than ever seen before in previous generations. These higher temperatures place more stringent requirements on the material crack growth performance under creep and time dependent conditions. Typically the types of components which are subject to these requirements are rotating disk components which are made from advanced materials such as nickel base superalloys. Traditionally crack growth models have looked at high temperature crack growth purely as a function of temperature and assumed that all crack growth was either controlled by a cycle dependent or time dependent mechanism. This new analysis is trying to evaluate the transition between cycle-dependent and time-dependent mechanism and the microstructural markers that characterize this transitional behavior. The physical indications include both the fracture surface morphology as well as the shape of the crack front. The research will evaluate whether crack tunneling occurs and whether it consistently predicts a transition from cycle-dependent crack growth to time-dependent crack growth. The study is part of a larger research program trying to include the effects of geometry, mission profile and environmental effects, in addition to temperature effects, as a part of the overall crack growth system. The outcome will provide evidence for various transition types and correlate those

  17. Dynamic recrystallization behavior of a γ′-hardened nickel-based superalloy during hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongbin; Zhang, Kaifeng [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Jiang, Shaosong, E-mail: jiangshaosong@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhou, Haiping [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhao, Changhong; Yang, Xiaoli [Fushun Special Steel Co. Ltd, Fushun 113000 (China)

    2015-02-25

    Highlights: • The relationship between the peak stress and stable DRX grain size has been expressed by a power law function. • The effect of CDRX characterized by progressive subgrain rotation became weaker with the increasing deformation temperature. • The effect of DDRX became stronger with the increasing strain for the alloy deformed at 1160 °C/0.1 s{sup −1}. • The fraction of twin boundaries is closely related to the deformation temperature and strain. - Abstract: The hot deformation behavior of a γ′-hardened nickel-based superalloy was investigated by means of isothermal compression tests in the temperature range of 1010–1210 °C with a strain rate of 0.1 s{sup −1}. The electron backscatter diffraction (EBSD) technique and transmission electron microscope (TEM) were employed to investigate the effect of deformation temperature and strain on the microstructure evolution and nucleation mechanisms of dynamic recrystallization (DRX). Microstructure observations revealed that the size and volume fraction of DRX grains increased with the increasing temperature. A power exponent relationship was obtained between the stable DRX grain size and the peak stress. Additionally, it was found that the effect of CDRX characterized by progressive subgrain rotation became weaker with the increasing deformation temperature, and DDRX was the operating nucleation mechanism of DRX at higher deformation temperature. On the other hand, the effect of DDRX became stronger with the increasing strain, and CDRX can only be considered as an assistant nucleation mechanism of DRX at the later stage of deformation for the alloy deformed at 1160 °C. Nucleation of DRX can also be activated by the twinning formation. Hence, particular attention was also paid to the evolution of twin boundaries during hot deformation.

  18. Dynamic recrystallization behavior of a γ′-hardened nickel-based superalloy during hot deformation

    International Nuclear Information System (INIS)

    Highlights: • The relationship between the peak stress and stable DRX grain size has been expressed by a power law function. • The effect of CDRX characterized by progressive subgrain rotation became weaker with the increasing deformation temperature. • The effect of DDRX became stronger with the increasing strain for the alloy deformed at 1160 °C/0.1 s−1. • The fraction of twin boundaries is closely related to the deformation temperature and strain. - Abstract: The hot deformation behavior of a γ′-hardened nickel-based superalloy was investigated by means of isothermal compression tests in the temperature range of 1010–1210 °C with a strain rate of 0.1 s−1. The electron backscatter diffraction (EBSD) technique and transmission electron microscope (TEM) were employed to investigate the effect of deformation temperature and strain on the microstructure evolution and nucleation mechanisms of dynamic recrystallization (DRX). Microstructure observations revealed that the size and volume fraction of DRX grains increased with the increasing temperature. A power exponent relationship was obtained between the stable DRX grain size and the peak stress. Additionally, it was found that the effect of CDRX characterized by progressive subgrain rotation became weaker with the increasing deformation temperature, and DDRX was the operating nucleation mechanism of DRX at higher deformation temperature. On the other hand, the effect of DDRX became stronger with the increasing strain, and CDRX can only be considered as an assistant nucleation mechanism of DRX at the later stage of deformation for the alloy deformed at 1160 °C. Nucleation of DRX can also be activated by the twinning formation. Hence, particular attention was also paid to the evolution of twin boundaries during hot deformation

  19. Results from investigations with an instrumented impact machine on a molybdenum base alloy, nickel base alloys, and Incoloy 800

    International Nuclear Information System (INIS)

    Experiments were performed on the molybdenum base alloy TZM, the nickel base alloys Nimocast 713 LC, Inconel 625, Nimonic 86, Hastelloy S, and the iron base alloy Incoloy 800 with an instrumented impact machine. The results are discussed in terms of absorbed impact energies and dynamic fracture toughness. In all cases the agreement between the energy determined by the dial reading and the energy determined by the integration of the load vs. load point displacement diagram was excellent. A procedure for the determination of the dynamic fracture toughness for load vs. load point displacement diagrams exhibiting high oscillations using an averaged curve is proposed. Using this procedure a pronounced influence of the experiments with tup and chisel (5.0 m/s and 0.1 m/s respectively) on the dynamic fracture toughness is not detectable. Using half the drop height, i.e. halving the total energy, lowers the dynamic fracture toughness values for these types of alloys. Low absorbed impact energies are often combined with high fracture toughness values. In these cases there is no or only a small reserve in deformation and/or stable crack growth. (Auth.)

  20. Fatigue crack initiation in nickel-based superalloys studied by microstructure-based FE modeling and scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Fried M.

    2014-01-01

    Full Text Available In this work stage I crack initiation in polycrystalline nickel-based superalloys is investigated by analyzing anisotropic mechanical properties, local stress concentrations and plastic deformation on the microstructural length scale. The grain structure in the gauge section of fatigue specimens was characterized by EBSD. Based on the measured data, a microstructure-based FE model could be established to simulate the strain and stress distribution in the specimens during the first loading cycle of a fatigue test. The results were in fairly good agreement with experimentally measured local strains. Furthermore, the onset of plastic deformation was predicted by identifying shear stress maxima in the microstructure, presumably leading to activation of slip systems. Measurement of plastic deformation and observation of slip traces in the respective regions of the microstructure confirmed the predicted slip activity. The close relation between micro-plasticity, formation of slip traces and stage I crack initiation was demonstrated by SEM surface analyses of fatigued specimens and an in-situ fatigue test in a large chamber SEM.

  1. Adhesion strength of nickel and zinc coatings with copper base electroplated in conditions of external stimulation by laser irradiance

    Directory of Open Access Journals (Sweden)

    V. V. Dudkina

    2013-04-01

    Full Text Available Purpose. The investigation of laser irradiance influence on the adhesion strength of nickel and zinc coatings with copper base and the research of initial stages of crystallization for nickel and zinc films. Methodology. Electrodeposition of nickel and zinc films from the standard sulphate electrolyte solutions was carried out on the laser-electrolytic installations, built on the basis of gas discharge CO2-laser and solid ruby laser KVANT-12. The adhesion strength of metal coatings with copper base are defined not only qualitatively using the method of meshing and by means of multiple bending, but also quantitatively by means of indention of diamond pyramid into the border line between coating and base of the side section. Spectrum microanalysis of the element composition of the border line “film and base” is carried out using the electronic microscope REMMA-102-02. Findings. Laser irradiance application of the cathode region in the process of electroplating of metal coatings enables the adhesion strength improvement of coating with the base. Experimental results of adhesive strength of the films and the spectrum analysis of the element composition for the border line between film and base showed that during laser-assisted electroplating the diffusion interaction between coating elements and the base metal surface takes place. As a result of this interaction the coating metal diffuses into the base metal, forming transition diffused layer, which enhances the improvement of adhesion strength of the coatings with the base. Originality. It is found out that ion energy increase in the double electric layer during interaction with laser irradiance affects cathode supersaturation at the stage of crystallization. Hence, it also affects the penetration depth of electroplated material ions into the base metal, which leads to the adhesion strength enhancement. Practical value. On the basis of research results obtained during the laser

  2. Restoration and Thermal Stability Investigation of Intermetllic Phase in Exposed Nickel Base Superalloy Udimet 500 Turbine Blades

    Directory of Open Access Journals (Sweden)

    Wangyao, P.

    2007-01-01

    Full Text Available The Udimet 500 nickel base superalloy blade exposed for 50000 hours in land base gas turbine working conditions faced the structure degradation. Six different heat treatments procedures have been applied (the blades were exposed at 900 °C and 1000 °C for different periods with maximum hold of 2500 hours to rejuvenate the degraded structure. Metallographic work was performed, generally, aging at both temperatures modify the gamma prime size, morphology and distribution characteristics substantially. The volume fraction of secondary gamma prime decreased with increasing aging time.

  3. High temperature corrosion of nickel-base alloys in environments containing alkali sulphate

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Rachel; Flyg, Jesper; Caddeo, Sophie [Corrosion and Metals Research Institute, KIMAB, Stockholm (Sweden); Karlsson, Fredrik [Siemens Industrial Turbomachinery, Finspong (Sweden)

    2007-02-15

    This work is directed towards producing data to assist in lifetime assessment of components in gas turbines run in severely polluted industrial environments where the main corrosive species is SO{sub 2}, which can condense to form alkali sulphates. Corrosion rates have been measured for the base materials, in order to assess the worst-case scenario, in which cracks or other damage has occurred to the protective coating. The information is expected to be of value to manufacturers, owners and inspectors of gas turbines. Six nickel-base superalloys were subject to thermal cycles of 160 hours duration, and 0.8mg/cm{sup 2} of 20 mol % Na{sub 2}SO{sub 4} + 80mol% K{sub 2}SO{sub 4} was applied before each cycle. The test temperatures were 850 deg C and 900 deg C, with maximum test durations of 24 cycles and 12 cycles respectively. The metal loss was assessed by metallography of cross sections and the sulphidation attack was found to be very uneven. Mass change data indicated that the corrosion process was largely linear in character, and probability plots and estimations of the propagation rate of corrosion based on the linear growth assumption were produced. The performance of the alloys increased with increasing chromium content. The single crystal materials CMSX4 and MD2 showed such high corrosion rates that their use in severely contaminated industrial environments is considered inadvisable. The best performance was shown by Inconel 939 and Inconel 6203, so that even if cracks occur in the protective coating, a reasonable remaining lifetime can be expected for these materials. Sulphide formation occurred at the reaction front in all cases and mixed sulphides such as Ta-Ni or Ti-Nb sulphides were often present. The work has news value since very little long-term data is currently available for materials performance in severely sulphidising environments. The project goals in terms of exposures and metrology have been fully realised. Contributions have been made to the

  4. Modification Approach of Fuzzy Logic Model for Predicting of Cutting Force When Machining Nickel Based Hastelloy C-276

    Directory of Open Access Journals (Sweden)

    Basim A. Khidhir

    2010-01-01

    Full Text Available Problem statement: Most Nickel based Hastelloy C-276 is a difficult-to-machine material because of its low thermal diffusive property and high strength at high temperature. Machinability consideration of nickel based Hastelloy C-276 in turning operations has been carried out using ceramic inserts under dry conditions. Approach: This study described a modification approach applied to a fuzzy logic based model for predicting cutting force where the machining parameters for cutting speed ranges, feed rate, depth of cut and approach angle are not overlapping. For this study, data were selected depending on the design of experiments. Response surface methodology was applied to predict the cutting force and to examine the fuzzy logic based model. Results: The modification approach fuzzy logic based model produced the cutting force data providing good correlation with response surface data. In this situation the cutting force data were superimposed and results were adjusted according to their own ranges. Conclusion: A review of literatures on optimization techniques revealed that there were, in particular, successful industrial applications of design of experiment-based approaches for optimal settings of process variables.

  5. Fabrication of paper-based devices by lacquer spraying method for the determination of nickel (II) ion in waste water.

    Science.gov (United States)

    Nurak, Thara; Praphairaksit, Narong; Chailapakul, Orawon

    2013-09-30

    A spraying method with lacquer was developed for the fabrication of paper-based devices. A patterned iron mask was initially placed on a filter paper and held tightly attached by a magnetic plate placed on the opposite side. After that, acrylic lacquer was sprayed on the filter paper to create a hydrophobic area while the hydrophilic area was protected with the iron mask. The optimal conditions for the fabrication of this device were studied including lacquer type and particle retention efficiency of filter paper. Gloss spray lacquer and filter paper No. 4 were chosen as optimal lacquer type and particle retention efficiency of filter paper, respectively. To evaluate its efficiency, the paper-based devices were used to determine nickel using electrochemical detection. Cu-enhancer solution was employed to increase sensitivity of nickel determination with the optimal concentration of 4.5 ppm. Under the optimal conditions, linear range was observed in the range of 1-50 ppm with a coefficient of determination of 0.9971. The limit of detection (LOD) and the limit of quantitation (LOQ) were found to be 0.5 and 1.97 ppm, respectively. Moreover, these paper-based devices coupled with electrochemical detection were applied to determine nickel in waste water of a jewelry factory and compared to those obtained with inductively coupled plasma optical emission spectrometry (ICP-OES). The results indicated that there were no significant variations between this proposed method (4.15±0.043 ppm) and the ICP-OES method (4.06±0.013 ppm). Therefore, this spraying method was found to be an excellent alternative for the fabrication of paper-based devices due to its ease of use, affordability and simplicity. PMID:23953473

  6. Brazing of inconel 600 and SUS304 stainless steel with used of rapidly solidified nickel-base brazing foil

    Energy Technology Data Exchange (ETDEWEB)

    Miyazawa, Yasuyuki; Ariga, Tadashi (Tokai Univ., Tokyo (Japan))

    1992-05-01

    In this study, the clad material which have been brazed with the nickel-base heat resistant alloy; Inconel 600 on AISI304 stainless steel has been produced by the brazing using three types of nickel-base brazing foils. The three types of nickel-base brazing foils are 7Cr(4.5Si-7.0Cr-3.0B-3.0Fe-Ni bal.), 5Cr(4.5Si-5.0Cr-3.0B-3.0Fe-Ni bal.) and 10Cr(4.5Si-10.0Cr-3.0B-3.0Fe-Ni bal.). Brazing was done in an electrical resistant furnace in an argon gas atmosphere. The brazing temperatures employed in this study were 1050, 1100, 1150, 1200 and 1250degC and the brazing times were 10, 30, 60 and 120 min for all types of brazing foils. The property of the joint was estimated by the mechanical properties, microstructures and distributions of the elements which were investigated by SEM and EPMA. The brazed joint was obtained for all of brazing conditions in this study. The shear strength of the specimen increased with increasing brazing time except at 1050degC. At 1050degC, the shear strength of the specimen was not influenced by brazing time. In this case, the break of the specimen during the shear test occurred in the brazed layer. At 1250degC, the value of 450 MPa was obtained as the maximum shear strength in this study; the break of the specimen occurred in the base metal. The shear strength of the specimen increased with increasing brazing temperature. The shear strength of the specimen increased with increasing chromium content in the brazing foil to 7 mass%. (J.P.N.).

  7. Brazing of inconel 600 and SUS304 stainless steel with used of rapidly solidified nickel-base brazing foil

    International Nuclear Information System (INIS)

    In this study, the clad material which have been brazed with the nickel-base heat resistant alloy; Inconel 600 on AISI304 stainless steel has been produced by the brazing using three types of nickel-base brazing foils. The three types of nickel-base brazing foils are 7Cr(4.5Si-7.0Cr-3.0B-3.0Fe-Ni bal.), 5Cr(4.5Si-5.0Cr-3.0B-3.0Fe-Ni bal.) and 10Cr(4.5Si-10.0Cr-3.0B-3.0Fe-Ni bal.). Brazing was done in an electrical resistant furnace in an argon gas atmosphere. The brazing temperatures employed in this study were 1050, 1100, 1150, 1200 and 1250degC and the brazing times were 10, 30, 60 and 120 min for all types of brazing foils. The property of the joint was estimated by the mechanical properties, microstructures and distributions of the elements which were investigated by SEM and EPMA. The brazed joint was obtained for all of brazing conditions in this study. The shear strength of the specimen increased with increasing brazing time except at 1050degC. At 1050degC, the shear strength of the specimen was not influenced by brazing time. In this case, the break of the specimen during the shear test occurred in the brazed layer. At 1250degC, the value of 450 MPa was obtained as the maximum shear strength in this study; the break of the specimen occurred in the base metal. The shear strength of the specimen increased with increasing brazing temperature. The shear strength of the specimen increased with increasing chromium content in the brazing foil to 7 mass%. (J.P.N.)

  8. Fatigue properties of nickel-base high temperature alloys for HTGRs

    International Nuclear Information System (INIS)

    A series of strain controlled low-cycle fatigue tests were conducted at temperatures ranging from room temperature (RT) to 900 deg. C on nickel-base high-temperature alloys, namely Hastelloy X and its modified versions Hastelloy XR and Hastelloy XR-II, which are candidate alloys for HTGR applications. The tests were conducted in the simulated HTGR helium environment with the exception of those conducted in air at RT. In those tests the examination was made on the effects of strain rate, hold time, aging and test temperature on fatigue properties. Decreasing the strain rate led to notable decreases in the fatigue life. Based on the stress-strain curves and the crack morphology, it was suggested that a considerable contribution of creep damage was included at lower strain rates. In the experiments with the trapezoidal strain waveform with different holding types, the fatigue life was found to be reduced most effectively in tensile hold-time experiments. From the observations of the crack morphology the strain holding in the compressive side was suggested to play the role of suppressing the initiation and the growth of internal cracks and/or cavities, and to cause crack branching. The fatigue lives of the aged (900 deg. C, 1000h) specimens were shorter than those of the solution annealed ones at test temperatures ranging from RT to 700 deg. C. The tendency became more pronounced under higher strain range conditions. The reduction in the fatigue life due to aging treatment, observed through the tests conducted at and below 700 deg. C, was closely related with the loss of tensile ductility, which was attributed to the precipitation of M6C carbide along the grain boundaries which occurred during the aging. Fractographic features and crack morphology of the aged specimens fatigued at and below 700 deg. C were of brittle nature relative to those of the solution annealed ones fatigued in the same temperature range. The fatigue lives estimated from the tensile properties

  9. Synthesis and characterization of nanostructured electrocatalysts based on nickel and tin for hydrogen peroxide electrogeneration

    International Nuclear Information System (INIS)

    Highlights: • 9% SnNi/C 6:1 was the best choice for H2O2 electrogeneration among all materials. • 9% SnNi/C 6:1 transferred 2.2 electrons and had a H2O2 percentage efficiency of 88%. • X-ray diffraction analysis identified a phase for 9% SnNi/C 6:1 (Ni3Sn4). • Ni3Sn4 is a structure tolerant of defects that can increase oxygen diffusion. -- Abstract: This work describes both the preparation and the characterization of nanostructured materials based on tin and nickel. Composite materials of SnNi/C were prepared by the polymeric precursor method and were supported on Vulcan XC-72R, which is a high surface area carbon, for a comparative study. Three proportions on carbon were evaluated: 6%, 9% and 13%. Binary materials were prepared varying the atomic ratios of Sn and Ni at 6:1, 3:1, 1:1, 1:3 and 1:6 for each percentage composition tested. The materials were characterized by X-ray diffraction to determine the mean crystallites sizes of the important phases for the catalytic process, such as Ni3Sn, Ni3Sn2 and Ni3Sn4, and by energy dispersive spectroscopy (EDS) measurements to determine the percentage composition of the material with highest catalytic activity. The results showed that the binary material prepared with 9% metal load at a ratio of 6:1 Sn:Ni was the best material for H2O2 electrogeneration. This material showed the highest ring current, which was a consequence of the highest amount of H2O2 production having a ring current higher than that obtained for the ORR for Vulcan carbon. The best electrocatalyst transferred 2.2 electrons in the ORR with an 88% yield of H2O2, while the Vulcan carbon, which is the reference material for the 2-electron transfer reaction, produced just a 63% yield of H2O2. Thus, based on these results, 9% Sn:Ni (6:1) is a promising material to be used in H2O2 electrogeneration and in AOPs. This result is likely due to the presence of acid oxygen-containing species on carbon and to the large defect concentration in Ni3Sn4 lattice

  10. Competing fatigue mechanisms in Nickel-base superalloy Rene 88DT

    Science.gov (United States)

    Chang, Paul N.

    Nickel base superalloys exhibit superior high temperature mechanical properties required for aircraft engine components. It has been known that the processing of these alloys by the powder metallurgy route introduces inclusions inside the material. The presence of such inclusions often leads to competing failure modes in fatigue that is described by a step-wise or two distinct S-N curves involving both the surface and internally-initiated cracks, resulting in large uncertainties of fatigue life. A clear understanding of such behavior is yet to be established. The principal objective of this research is to examine the effect of inclusions on the extent of fatigue failure competition from surface and internal initiators at two different specimen test volumes. Experimental fatigue testing has been performed to explore how the presence of inclusions affects the competing fatigue failure modes. In addition, how the competing failure modes will behave with changes in the specimen size was also studied. Two groups of material each with two different specimen sizes were used in this study. It has been shown that the two crack initiation mechanisms occurred in the small unseeded Rene 88DT specimens tested at 650ºC over the stress range tested. Additionally, the fatigue lives were reduced with increase in specimen volume. All fatigue failures in seeded material occurred due to crack initiations from the seeded inclusions. In the fatigue life of seeded material, two competing and separate S-N curves were found in small test volume, whereas, in the large test volume, the regions were separated by a "step" in S-N curve. It has been found that the largest inclusion size observed in metallographic surfaces was smaller than the size determined from the fatigue failure origin. An analysis method based on extreme value statistics developed by Murakami was used to predict the largest size of inclusion in the test volume. The results of this study clearly show that competition for

  11. Electrooxidation of formaldehyde based on nickel-palladium modified ordered mesoporous silicon.

    Science.gov (United States)

    Miao, Fengjuan; Tao, Bairui

    2013-04-01

    Nickel and palladium nanoparticles were finely dispersed on ordered mesoporous silicon microchannels plate (MCP) by electroless plating. The structure and composition of the resulting Ni-Pd/Si MCP were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The electrocatalystic properties of Ni-Pd/Si MCP electrode for formaldehyde oxidation have been investigated by cyclic voltammetry. The results show that Ni-Pd/Si MCP has a higher catalytic activity and better steady-state behavior for formaldehyde oxidation. This may be attributed to the synergistic property of high dispersion of Nickel and Palladium nanoparticles and particular properties of mesoporous Si MCP. The present study shows a promising choice of Ni-Pd nanoparticles supported by mesoporous silicon as effective electrocatalyst for formaldehyde electrooxidation in alkaline medium. The results imply that the Ni-Pd/Si MCP nanocomposite has good potential application in formaldehyde fuel cells and sensors. PMID:23763207

  12. Influence of Chromium and Molybdenum on the Corrosion of Nickel Based Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, J R; Gray, J; Szmodis, A W; Orme, C A

    2005-08-02

    The addition of chromium and molybdenum to nickel creates alloys with exceptional corrosion resistance in a diverse range of environments. This study examines the complementary roles of Cr and Mo in Ni alloy passivation. Four nickel alloys with varying amounts of chromium and molybdenum were studied in 1 molar salt solutions over a broad pH range. The passive corrosion and breakdown behavior of the alloys suggests that chromium is the primary element influencing general corrosion resistance. The breakdown potential was nearly independent of molybdenum content, while the repassivation potential is strongly dependant on the molybdenum content. This indicates that chromium plays a strong role in maintaining the passivity of the alloy, while molybdenum acts to stabilize the passive film after a localized breakdown event.

  13. Investigation of the final stages of solidification and eutectic phase formation in Re and Ru containing nickel-base superalloys

    Science.gov (United States)

    Heckl, A.; Rettig, R.; Cenanovic, S.; Göken, M.; Singer, R. F.

    2010-07-01

    The microstructure resulting from the final stages of solidification—commonly referred to as eutectic islands—has been analysed in detail for three nickel-base superalloys containing Re and Ru. Focused ion beam 3-D reconstruction and EBSD-analysis were used to clarify the origin of different eutectic structure types. One common type of parent 3-D eutectic structure was identified. The solidification process of the final solidifying liquid has been further investigated by electron probe microanalysis mappings along with DICTRA simulations. Two models for diffusion controlled phase transformations are shown to present a fair description of the solidification sequence.

  14. EELS analysis of the nitrogen content of carbide particles in a commercial γ′-strengthened nickel-base superalloy

    International Nuclear Information System (INIS)

    Carbide particles contribute to the high strength of nickel-base superalloys. It is a long standing question whether these carbide particles contain nitrogen. Here we examine the nitrogen content of the titanium–molybdenum-carbide in the commercial superalloy NIMONIC PE16 using a combination of electron energy loss spectroscopy (EELS) with energy dispersive X-ray (EDX) analysis. Careful examination of the molybdenum M3- and M2-edges, which overlap with the nitrogen K-edge, leads to an upper limit for the nitrogen content of the carbide: 1.8 at.%

  15. Microstructural stability of a nickel-based alloy overlay on a 2.25Cr1Mo steel substrate

    OpenAIRE

    Saghafifar, Hassan

    2011-01-01

    Ni-based superalloy weld overlays are widely used in electricity generating plants to significantly reduce high temperature corrosion problems of ferritic steel components under service conditions. Welding a nickel alloy similar to IN625 onto the outer bore of a 2.25Cr1Mo steel tube enhances its service life as a superheater tube in the highly corrosive environment of a Waste-to-Energy boiler. For the purposes of studying the effects of high temperature service on the microstructure of this l...

  16. The French safety authority's view on stress corrosion cracking of nickel-based alloy components

    International Nuclear Information System (INIS)

    The sensitivity of some nickel-based alloys to stress corrosion cracking (SCC) has been known for several years: experiments conducted in 1959 at CEA (French atomic research centre) showed that SCC can appear in alloy 600 under primary water chemical conditions. In nuclear power plants (NPPs), stress corrosion induced cracks have been detected since 1971 in steam generator (SG) tubes. In France, they were first detected in 1980. This made it clear that SCC of alloy 600 was also possible out of laboratories and led to an important inservice inspection and maintenance programme, including the replacement of some SGs, and to many research studies. Though, till the late 1980's, SCC had only been detected on SG tubes. In France, the detection of SCC on pressurizer nozzles in 1989 and on reactor pressure vessel heads in 1991 demonstrated that all alloy 600 components could be concerned. Following the request of the French safety authority and under its control, the French utility EDF started a comprehensive review of all components of the main primary system (MPS) made with alloy 600. For each, the risk of SCC was evaluated and taken into account in the definition of in-service inspection programmes.This article aims at presenting the situation about fifteen years later. The paper has the following contents: The French regulatory approach; Review of alloy 600 components in French NPPs; The situation in 2005; Future issues. One concludes that the alloy 600 issues have been teaching many things to the French safety authority for fifteen years. First, material degradations exist and even good design and good manufacturing are not guarantees that nothing will happen during operation. The only way to detect those degradations is to have an adequate in-service inspection programme. This programme can rely on scientific analyses. But it must also include sample checks otherwise unknown phenomena have little chance to be detected before they lead to an incident. The hydraulic

  17. Glow discharge mass spectrometric analysis of nickel-based heat-resisting alloys

    International Nuclear Information System (INIS)

    GD-MS analysis of nickel-based heat-resisting alloys has been performed using a VG 9000 glow discharge (GD) mass spectrometer. Concentrations of not only alloying elements (Al, Si, Ti, V, Cr, Mn, Fe, Co, Cu, Y, Nb, Mo and W) but also trace elements (B, C, Mg, P, S, Zn, Ga, As, Zr, Cd, Sn, Sb, Te, Pb and Bi) were successfully determined in disk shaped samples. The examination of spectral interference confirmed the following. The influence of manganese argide (55Mn40Ar+) on the ion beam intensity of 95Mo+ was negligible because manganese content of the alloys is usually less than 1 mass%. Mass spectra of 31P+ and 32S+ may be affected by the spectral interference of 62Ni2+ and 64Ni2+, respectively, due to the matrix element. However, these ion species were sufficiently separated at the mass resolution 5000 (m/Δm, at 5% peak height) used in this study. Relative sensitivity factors (RSFs) were determined by analyzing standard reference materials: JAERI CRMs, a NIST SRM, a BS CRM, BCS CRMs and the alloys prepared in our Institute. The average RSF-values obtained for Ni=1 were 0.436 for Al, 0.826 for Si, 0.281 for Ti, 0.375 for V, 1.480 for Cr, 1.122 for Mn, 0.754 for Fe, 0.653 for Co, 3.321 for Cu, 0.303 for Y, 0.436 for Nb, 0.862 for Mo, 0.935 for Ta and 1.052 for W. The analytical accuracy (σd) obtained was comparable to that of FP-XRF analysis, except for chromium and iron determinations. Relative standard deviations (RSDs) of five replicate measurements were within about 2.5%, except for phosphorus (P; 0.003 mass%, RSD; 3.31%) and sulfur (S; 0.005 mass%, RSD; 3.08%). GD-MS analytical values for ODS MA6000 alloy were obtained using a RSF correction program, and the values were in good agreement with those obtained by FP-XRF and by chemical analysis (author)

  18. Recycling of spent nickel-cadmium batteries based on bioleaching process

    International Nuclear Information System (INIS)

    Only 1-2 percent of discarded dry batteries are recovered in China. It is necessary to find an economic and environmentally friendly process to recycle dry batteries in this developing country. Bioleaching is one of the few techniques applicable for the recovery of the toxic metals from hazardous spent batteries. Its principle is the microbial production of sulphuric acid and simultaneous leaching of metals. In this study, a system consisting of a bioreactor, settling tank and leaching reactor was developed to leach metals from nickel-cadmium batteries. Indigenous thiobacilli, proliferated by using nutritive elements in sewage sludge and elemental sulphur as substrates, was employed in the bioreactor to produce sulphuric acid. The overflow from the bioreactor was conducted into the settling tank. The supernatant in the settling tank was conducted into the leaching reactor, which contained the anode and cathodic electrodes obtained from nickel-cadmium batteries. The results showed that this system was valid to leach metals from nickel-cadmium batteries, and that the sludge drained from the bottom of the settling tank could satisfy the requirements of environmental protection agencies regarding agricultural use

  19. Tuneable magneto-optical metamaterials based on photonic resonances in nickel nanorod arrays

    International Nuclear Information System (INIS)

    We investigate the magneto-optical properties of a nanostructured metamaterial comprised of arrays of nickel nanorods embedded in an anodized aluminum oxide template. The rods are grown using a self-assembly bottom-up technique that provides a uniform, quasi-hexagonal array over a large area, quickly and at low cost. The tuneability of the magneto-optic response of the material is investigated by varying the nanorod dimensions: diameter, length and inter-rod spacing as well as the overall thickness of the template. It is demonstrated that the system acts as a sub-wavelength light trap with enhanced magneto-optical properties occurring at reflectivity minima corresponding to photonic resonances of the metamaterial. Changes in dimensions of the nickel rods on the order of tens of nanometers cause a spectral blue-shift in the peak magneto-optical response of 270 nm in the visible range. A plasmonic enhancement is also observed at lower wavelengths, which becomes increasingly damped with larger diameters and increased volume fraction of nickel inclusions. This type of structure has potential applications in high density magneto-optical data storage (up to 1011–12 rods per square inch), ultrafast magneto-plasmonic switching and optical components for telecommunications. (papers)

  20. Modeling of abnormal mechanical properties of nickel-based single crystal superalloy by three-dimensional discrete dislocation dynamics

    International Nuclear Information System (INIS)

    Unlike common single crystals, the nickel-based single crystal superalloy shows surprisingly anomalous flow strength (i.e. with the increase of temperature, the yield strength first increases to a peak value and then decreases) and tension–compression (TC) asymmetry. A comprehensive three-dimensional discrete dislocation dynamics (3D-DDD) procedure was developed to model these abnormal mechanical properties. For this purpose, a series of complicated dynamic evolution details of Kear–Wilsdorf (KW) locks, which are closely related to the flow strength anomaly and TC asymmetry, were incorporated into this 3D-DDD framework. Moreover, the activation of the cubic slip system, which is the origin of the decrease in yield strength with increasing temperature at relatively high temperatures, was especially taken into account by introducing a competition criterion between the unlocking of the KW locks and the activation of the cubic slip system. To test our framework, a series of 3D-DDD simulations were performed on a representative volume cell model with a cuboidal Ni3Al precipitate phase embedded in a nickel matrix. Results show that the present 3D-DDD procedure can successfully capture the dynamic evolution of KW locks, the flow strength anomaly and TC asymmetry. Then, the underlying dislocation mechanisms leading to these abnormal mechanical responses were investigated and discussed in detail. Finally, a cyclic deformation of the nickel-based single crystal superalloy was modeled by using the present DDD model, with a special focus on the influence of KW locks on the Bauschinger effect and cyclic softening. (paper)

  1. Modeling of abnormal mechanical properties of nickel-based single crystal superalloy by three-dimensional discrete dislocation dynamics

    Science.gov (United States)

    Yang, Hui; Li, Zhenhuan; Huang, Minsheng

    2014-12-01

    Unlike common single crystals, the nickel-based single crystal superalloy shows surprisingly anomalous flow strength (i.e. with the increase of temperature, the yield strength first increases to a peak value and then decreases) and tension-compression (TC) asymmetry. A comprehensive three-dimensional discrete dislocation dynamics (3D-DDD) procedure was developed to model these abnormal mechanical properties. For this purpose, a series of complicated dynamic evolution details of Kear-Wilsdorf (KW) locks, which are closely related to the flow strength anomaly and TC asymmetry, were incorporated into this 3D-DDD framework. Moreover, the activation of the cubic slip system, which is the origin of the decrease in yield strength with increasing temperature at relatively high temperatures, was especially taken into account by introducing a competition criterion between the unlocking of the KW locks and the activation of the cubic slip system. To test our framework, a series of 3D-DDD simulations were performed on a representative volume cell model with a cuboidal Ni3Al precipitate phase embedded in a nickel matrix. Results show that the present 3D-DDD procedure can successfully capture the dynamic evolution of KW locks, the flow strength anomaly and TC asymmetry. Then, the underlying dislocation mechanisms leading to these abnormal mechanical responses were investigated and discussed in detail. Finally, a cyclic deformation of the nickel-based single crystal superalloy was modeled by using the present DDD model, with a special focus on the influence of KW locks on the Bauschinger effect and cyclic softening.

  2. Facile synthesis of Co2P via the reduction of phosphate with KBH4 for nickel-based rechargeable batteries

    International Nuclear Information System (INIS)

    Highlights: • We report a new way to prepare Co2P for nickel-based rechargeable batteries. • The reversible discharge capacity of Co2P is about 244 mAh g−1. • Co2P exhibits attractive cycle stability and rate capability. - Abstract: Crystalline Co2P is synthesized via a green and effective method based on the reduction of phosphate with KBH4. Various analytical techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy-dispersive spectroscopy instrument are employed to characterize the obtained Co2P. Moreover, it is electrochemically used as an anode material for nickel-based rechargeable batteries and compared with amorphous Co–P prepared by chemical reduction. Co2P electrode presents superior electrochemical properties such as discharge capacities, cycle stability, and rate capability to Co–P electrode. The reversible discharge capacity of Co2P electrode is about 244.1 mAh g−1 at 100 mA g−1 which can be retained after 200 cycles. Co2P electrode also shows promising high rate performance. Furthermore, cyclic voltammogram illustrates that the reversible electrochemical capacity of Co2P electrode is attributed to the redox of Co/Co(OH)2. Electrochemical impedance spectroscopy displays that the charge transfer resistance of Co2P electrode is smaller than that of Co–P electrode

  3. Pulse reversal plating of nickel alloys

    DEFF Research Database (Denmark)

    Tang, Peter Torben

    2007-01-01

    ), internal stress and material distribution are even more important. With baths based upon nickel chloride, and nickel and cobalt chlorides, pulse reversal plating of both pure nickel and nickel-cobalt alloys has been used to fabricate tools for microinjection moulding. Pulse reversal plating of ternary soft...... magnetic alloys, comprising 45-65%Co, 15-35%Fe and 15-35%Ni, is also reported....

  4. Storage and characterization of the hydrogen in mixed oxides on base of cerium-nickel and zirconium or the aluminium

    International Nuclear Information System (INIS)

    The mixed oxides based on cerium-nickel and zirconium or aluminium are able to store large quantities of hydrogen, To determine nature, reactivity and properties of hydrogen species (spill-over, direct desorption), the solid were studied by different physicochemical techniques in the dried, calcined and partially reduced states: XRD, porosity, TGA, TPR, TPA, TPD, chemical titration and inelastic neutron scattering (INS). Solids are mainly meso-porous with a common pore size at 4 nm, They are constituted of CeO2 phase, Ce-Ni or Ce-Ni-Zr solid solution and of Ni(OH)2 in the dried state and NiO in the calcined state. The Ni species are in various environments and the strong interactions between the cations in solid solution and at different particles interface influence their reducibility and the creation of anionic vacancies. Activation in H2 in temperature is determining for hydrogen storage in the solid while calcination step is not necessary. INS Analyses evidence that the hydrogen species inserted during treatment in H2 are H+(OH-), hydride H- and H* (metallic nickel) species, present in various chemical environments, in particular for hydride species. All kinds of hydrogen species participate to the reaction during the chemical titration in agreement with the proposed hydrogenation mechanism. The study of the adsorption of hydrogen shows that this step is fast and in quantity of the same order as that measured by chemical titration. The direct desorption of H2 is very low, linked to the presence of hydrogen in interaction with metallic nickel (H*-.). Desorption of water is also observed, in parallel, corresponding to the elimination of groups. The hydride species are not desorbed. These various observations allow connecting hydrogen species properties with their localization in the structure and to model active sites. (author)

  5. Co2/ H2 Menthanate on nickel oxide based catalyst doped with various elements for the purification of natural gas

    International Nuclear Information System (INIS)

    Nickel possess characteristics similar to noble metals, apart from being easily deactivated by carbon deposition and poisoning. In this study, the activity of prepared nickel based catalysts doped with selected elements (Mg, Zr, Mo, Mn, Co, Fe, and Cu) that were presumed to help nickel active sites has been investigated for the CO2 elimination in the presence of H2 in the hopes for a menthanate reaction. With the addition of lanthanide series as co-dopant in the catalyst, the synthesized catalysts were tested for its catalytic activity and reproducibility by FTIR spectroscopy. It was found that only several elements can boost CO2 elimination, namely magnesium, cobalt and ferum, with cobalt showing the highest conversion for both ratios, Ni/ Co/ Pr 60:30:10 and 60:10:30. Furthermore, Ni/ Co/ Pr with the ratio of 60:30:10 was proven superior as it yielded highest CH4 in the lowest conversion temperature of approximately 350 degree Celsius. Further characterization on Ni/ Co/ Pr with the ratio of 60:30:10 showed the supremacy towards the conversion of CO2 to CH4. Single point BET analysis showed that Ni/ Co/ Pr did not have any changes in the surface area, as it did not adsorb CO2. This statement is in agreement with the XRD and EDX results obtained whereby there are no traces of carbon deposition. From TPD results showed CO2 desorption peaks at low and high temperature indicated intermediate bonding of CO2 on the surface of the catalyst. This shows the presence of dopant will result in the enhancement of CO2 elimination to a 100 %. (author)

  6. Microstructure and mechanical properties of Ir-Ta coatings on nickel-base single-crystal superalloy TMS-75

    International Nuclear Information System (INIS)

    In the present study, a methodology for the controlled addition of tantalum in iridium--alloy coatings prepared by dc magnetron sputtering from a composite target has been proposed. Ir-Ta coatings with 16.2, 23.9, 40.7, and 65.1 at. % Ta were deposited at 573 K on the oriented nickel-base single-crystal superalloy, TMS-75, by suitably selecting the ratio of the surface area of the iridium target to the surface area of the tantalum target on the basis of reported values of the sputtering yield of the respective elements. The microstructural analysis indicates that pure coatings of iridium and tantalum form polycrystalline films with rms roughness of ∼5 nm, while the Ir-Ta coatings form a nanocrystalline structure whose crystallite size and rms roughness decrease with the increase in tantalum content. Measurement of mechanical properties using the nanoindentation technique shows that the Young's modulus and hardness of the coatings generally decrease with the increase in the tantalum content. However, there is a peaking of hardness in the composition range 16.2-23.9 at. % tantalum. This could be due to the formation of the nanocrystalline Ir3Ta phase. The data on the mechanical properties are presented to explore the possibility of using Ir-Ta as an oxidation-resistant material on nickel-base single-crystal superalloy

  7. Influence of cooling rate on the development of multiple generations of γ' precipitates in a commercial nickel base superalloy

    International Nuclear Information System (INIS)

    The compositional and microstructural evolution of different generations of γ' precipitates during the continuous cooling of a commercial nickel base superalloy, Rene88DT, has been characterized by three dimensional atom probe tomography coupled with energy-filtered transmission electron microscopy studies. After solutionizing in the single γ phase field, continuous cooling at a very high rate results in a monomodal size distribution of γ' precipitates with a high nucleation density and non-equilibrium compositions. In contrast, a relatively slower cooling rate (∼ 24 deg. C/min) results in a multi-modal size distribution of γ' precipitates with the larger first generation primary precipitates exhibiting close to equilibrium composition, along with the smaller scale secondary γ' precipitates, exhibiting non-equilibrium composition (excess of Co and Cr, depleted in Al and Ti). The composition of the γ matrix near these precipitates also exhibits similar trends with the composition being closer to equilibrium near the primary precipitates as compared to the secondary precipitates. - Highlights: → Effect of cooling rate on the precipitation of γ' particles in commercial nickel base superalloy. → Couples EFTEM and 3DAP studies to determine the composition and morphology of γ' precipitates. → Determination of near and far field compositional variations within the gamma matrix leading to subsequent precipitation.

  8. Theoretical investigation of the mechanism of tritiated methane dehydrogenation reaction using nickel-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Liang; Li, Jiamao; Deng, Bing; Yang, Yong; Wang, Heyi [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Li, Weiyi [School of Physics and Chemistry, Xihua University, Chengdu 610065 (China); Li, Shuo, E-mail: lishuo@cqut.edu.cn [School of Chemical Engineering, Chongqing University of Technology, Chongqing 400054 (China); Tan, Zhaoyi, E-mail: tanzhaoyi@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2015-06-15

    Graphical abstract: - Highlights: • Four-step dehydrogenation of CT{sub 4} catalyzed by Ni to form Ni–C by releasing T{sub 2}. • The process of Ni + CT{sub 4} → NiCT{sub 2} + T{sub 2} is more achievable than that of NiCT{sub 2} → NiC + T{sub 2}. • TNiCT → T{sub 2}NiC step is the RDS with the rate constant of k = 2.8 × 10{sup 13} exp(−313,136/RT). • The hydrogen isotope effect value of k{sub H}/k{sub T} is 2.94, and k{sub D}/k{sub T} is 1.39. • CH{sub 4} and CD{sub 4} dehydrogenations are likely to occur, accompanied by the CT{sub 4} cracking. - Abstract: The mechanism of tritiated methane dehydrogenation reaction catalyzed by nickel-based catalyst was investigated in detail by density functional theory (DFT) at the B3LYP/[6-311++G(d, p), SDD] level. The computational results indicated that the dehydrogenation of tritiated methane is endothermic. The decomposition of tritiated methane catalyzed by Ni to form Ni-based carbon (Ni–C) after a four-step dehydrogenation companied with releasing tritium. After the first and second dehydrogenation steps, Ni + CT{sub 4} formed NiCT{sub 2}. After the third and fourth dehydrogenation steps, NiCT{sub 2} formed NiC. The first and second steps of dehydrogenation occurred on both the singlet and triplet states, and the lowest energy route is Ni + CT{sub 4} → {sup 1}COM → {sup 1}TS1 → {sup 3}IM1 → {sup 3}TS2 → {sup 3}IM2. The third and fourth steps of dehydrogenation occurred on both the singlet and quintet states, and the minimum energy reaction pathway appeared to be IM3 → {sup 1}TS4 → {sup 5}IM4 → {sup 5}TS5 → {sup 5}IM5 → {sup 5}pro + T{sub 2}. The fourth step of dehydrogenation TNiCT → T{sub 2}NiC was the rate-determining step of the entire reaction with the rate constant of k{sub 2} = 2.8 × 10{sup 13} exp(−313,136/RT) (in cm{sup 3} mol{sup −1} s{sup −1}), and its activation energy barrier was calculated to be 51.8 kcal/mol. The Ni-catalyzed CH{sub 4} and CD{sub 4} cracking

  9. Microstructural evolutions and mechanical behaviour of the nickel based alloys 617 and 230 at high temperature

    International Nuclear Information System (INIS)

    High Temperature Reactors (HTR), is one of the innovative nuclear reactor designed to be inherently safer than previous generation and to produce minimal waste. The most critical metallic component in that type of reactor is the Intermediate Heat exchanger (IHX). The constraints imposed by the conception and the severe operational conditions (high temperature of 850 C to 950 C, lifetime of 20,000 h) have guided the IHX material selection toward two solid solution nickel base alloys, the Inconel 617 and the Haynes 230. Inconel 617 is the primary candidate alloy thanks to its good high temperature mechanical and corrosion properties and the large data base developed in previous programs. However, its high cobalt content has to be considered as an issue (nuclear activation). The more recent alloy Haynes 230, in which most of the cobalt has been replaced by tungsten, present characteristics similar to the 617 alloy. The objective of this thesis is to study the high temperature mechanical behaviour of both alloys in relation with their microstructural evolutions. The as received microstructural observations have revealed primary carbides (M6C). Most of this precipitates are evenly distributed in the materials. Few M23C6 secondary carbides are observed in both alloys in the as received state. Thermal ageing treatments at 850 C lead to an important M23C6 precipitation on slip lines and at grain boundaries. The size of this carbides increases and their number decreases with increasing ageing duration. The intragranular precipitation of secondary carbides at 950 C is more limited and the intergranular evolution more important than at 850 C. The microstructural observations and the hardness evolution of both alloys show that the main microstructural evolutions occur before 1,000 h at both studied temperatures. The mechanical properties of the Inconel 617 and the Haynes 230 have been studied using tensile, creep, fatigue and relaxation-fatigue tests. Particularly, the

  10. Stability, carbon resistance, and reactivity toward autothermal reforming of nickel on ceria-based supports

    International Nuclear Information System (INIS)

    'Full text:' Solid Oxide Fuel Cell (SOFC) normally requires a reformer unit, where the fuel such as natural gas, methane, methanol, or ethanol can be reformed to hydrogen before introducing to the main part of fuel cell. Nickel on commercial supports such as Al2O3, MgO, ZrO2 has been widely reported to be used as the reforming catalyst commercially. Carbon formation and catalyst deactivation are always the main problems of using this type of catalyst. It is well established that CeO2 and CeO2-ZrO2 have been applied as the catalysts in a wide variety of reactions involving oxidation or partial oxidation of hydrocarbons (e.g. automotive catalysis). In order to quantify the performance of nickel on CeO2 and CeO2-ZrO2 supports for reformer application, the stabilities toward methane steam reforming and the carbon formation resistance were studied. After 18 hours, nickel on CeO2-ZrO2 with the Ce/Zr ratio of 3/1 presented the best performance in term of stability and activity. It also provided excellent resistance toward carbon formation compared to commercial Ni/Al2O3. The autothermal reforming of methane over Ni catalyst on CeO2 and CeO2-ZrO2 supports were also investigated. Ni/Ce-ZrO2 with the Ce/ Zr ratio of 3/1 also showed the best performance. The kinetics of this reaction was also studied. In the temperature range of 750-900C, the reaction order in methane was always closed to 1. The catalyst showed a slight positive effect of hydrogen and a negative effect of steam on the steam reforming rate. The addition of oxygen increased the steam reforming rate. However, the productions of CO and H2 decreased with increasing oxygen partial pressure. (author)

  11. Nanostructured hybrid composites based on fullerene C60 and nickel - synthesis, structural properties and development

    Czech Academy of Sciences Publication Activity Database

    Vacík, Jiří; Lavrentiev, Vasyl; Vorlíček, Vladimír; Bačáková, Lucie; Narumi, K.

    Taipei : IAMS Academia Sinica, 2008. s. 251-251. ISBN N. [New Diamond and Nano Carbons /2./ - NDNC 2008. 26.05.2008-29.05.2008, Taipei] R&D Projects: GA ČR(CZ) GA204/06/0225; GA AV ČR(CZ) KAN400480701; GA AV ČR(CZ) KAN101120701 Institutional research plan: CEZ:AV0Z50110509; CEZ:AV0Z10480505; CEZ:AV0Z10100520 Keywords : spo2 * nickel * fullerene composite * spectroscopy Subject RIV: EI - Biotechnology ; Bionics

  12. Surface engineering technologies of refractory nickel-based alloy components with intense pulsed electron beams

    International Nuclear Information System (INIS)

    The present paper reviews the results of investigations dedicated by the application of intense pulsed electron beams for surface processing of compressor and turbine blades of aircraft engines. The high energy density (w=1-50 J/cm2) of these short-pulsed (τ=1-20 μs) beams (with a diameter of d=6-10 cm and an energy of E=100-150 keV) exhibits a good prospect of their introduction into aircraft engine building for surface smoothing and strengthening of compressor and turbine blades from titanium and nickel alloys. (authors)

  13. Synthesis, characterization, single crystal X-ray determination, fluorescence and electrochemical studies of new dinuclear nickel(II) and oxovanadium(IV) complexes containing double Schiff base ligands

    Science.gov (United States)

    Shafaatian, Bita; Ozbakzaei, Zahra; Notash, Behrouz; Rezvani, S. Ahmad

    2015-04-01

    A series of new bimetallic complexes of nickel(II) and vanadium(IV) have been synthesized by the reaction of the new double bidentate Schiff base ligands with nickel acetate and vanadyl acetylacetonate in 1:1 M ratio. In nickel and also vanadyl complexes the ligands were coordinated to the metals via the imine N and enolic O atoms. The complexes have been found to possess 1:1 metals to ligands stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The nickel and vanadyl complexes exhibited distorted square planar and square pyramidal coordination geometries, respectively. The emission spectra of the ligands and their complexes were studied in methanol. Electrochemical properties of the ligands and their metal complexes were also investigated in DMSO solvent at 150 mV s-1 scan rate. The ligands and metal complexes showed both quasi-reversible and irreversible processes at this scan rate. The Schiff bases and their complexes have been characterized by FT-IR, 1H NMR, UV/Vis spectroscopies, elemental analysis and conductometry. The crystal structure of the nickel complex has been determined by single crystal X-ray diffraction.

  14. The impact of carbon on single crystal nickel-base superalloys: Carbide behavior and alloy performance

    Science.gov (United States)

    Wasson, Andrew Jay

    Advanced single crystal nickel-base superalloys are prone to the formation of casting grain defects, which hinders their practical implementation in large gas turbine components. Additions of carbon (C) have recently been identified as a means of reducing grain defects, but the full impact of C on single crystal superalloy behavior is not entirely understood. A study was conducted to determine the effects of C and other minor elemental additions on the behavior of CMSX-4, a commercially relevant 2nd generation single crystal superalloy. Baseline CMSX-4 and three alloy modifications (CMSX-4 + 0.05 wt. % C, CMSX-4 + 0.05 wt. % C and 68 ppm boron (B), and CMSX-4 + 0.05 wt. % C and 23 ppm nitrogen (N)) were heat treated before being tested in high temperature creep and high cycle fatigue (HCF). Select samples were subjected to long term thermal exposure (1000 °C/1000 hrs) to assess microstructural stability. The C modifications resulted in significant differences in microstructure and alloy performance as compared to the baseline. These variations were generally attributed to the behavior of carbide phases in the alloy modifications. The C modification and the C+B modification, which both exhibited script carbide networks, were 25% more effective than the C+N modification (small blocky carbides) and 10% more effective than the baseline at preventing grain defects in cast bars. All C-modified alloys exhibited reduced as-cast gamma/gamma' eutectic and increased casting porosity as compared to baseline CMSX-4. The higher levels of porosity (volume fractions 0.002 - 0.005 greater than the baseline) were attributed to carbides blocking molten fluid flow during the final stages of solidification. Although the minor additions resulted in reduced solidus temperature by up to 16 °C, all alloys were successfully heat treated without incipient melting by modifying commercial heat treatment schedules. In the B-containing alloy, heat treatment resulted in the transformation of

  15. Fixed time integration-emission spectrochemical analysis of nickel-base alloys and heat resisting steels for minor amount of elements

    International Nuclear Information System (INIS)

    The emission spectrochemical analysis of nickel-base alloys and heat resisting steels by the fixed time integration method has been developed. Nickel contents of 9 to 76% in the samples were examined in this study. For such samples, the internal standard method was inadequate, while the fixed time integration method gave good accuracy in the determination of minor elements in these samples. Elements analysed were C, P, S, B, Si, Ta, Co, Fe, Mn, Nb, Cu, Ti, Zr and Al. At first, ternary alloys containing a constant amount of cobalt (0.5, 1.0, 3.0, 6.0, 10.0, or 20.0%) with changing amounts of nickel and iron were prepared in order to examine the effect of nickel and iron content on the determination of these elements. It was found that the samples should be classified to two groups according to the nickel content, that is one group corresponding to 9 - 60% nickel and the other to 60 - 76%, and calibration curves had to be made separately. The equations of calibration curves were given in the regression lines of the first order in the determination of minor elements. For correcting the effect of neighbouring lines, coefficients of correction were derived by the multiple regression analysis. The relation between the sensitivity of analysis and the coefficient of correction was examined. As the sensitivity, the gradient of calibration curves was chosen, and it was observed that there was a linear correlation between the gradient and the partial regression coefficient. After all, the relation of hyperbola was concluded to exist between the gradient and the coefficient of correction in the determination of most elements. The gradients of calibration curves in the two groups were almost the same, but the gradients of the group containing more amount of nickel were a little larger than those of the other. (author)

  16. MeCrAl coatings obtained by arc PVD and pack cementation processes on nickel base superalloys

    International Nuclear Information System (INIS)

    The paper presents the results of researches on obtaining and structure of high temperature resistance coatings on superalloys. The coatings were deposited on nickel and nickel base superalloys in two stages. During the first stage, the NiCr and NiCrHf coatings were obtained by arc-PVD method. Basic technology, bias, arc current, rotation, parameters of deposition of NiCr and MeCrHf coatings were defined. The high efficiency of deposition of both single and two sources was observed. The targets were made by vacuum melting and machining. An influence of targets chemical composition on coating structure and chemical coatings composition was described. The second stage was made by pack cementation HTLA (high temperature low activity) on 1323 K chromoaluminizing process. These arc-PVD and diffusion (pack cementation) connected processes permitted to obtain MeCrAl and MeCrAlHf type of coatings. The morphology, structure and microchemical composition were characterized by scanning electron microscopy, X-ray microanalysis, energy dispersive X-ray spectroscopy and X-ray diffraction methods. (orig.)

  17. Performance of a combined capacitor based on ultrafine nickel oxide/carbon nanotubes composite electrodes

    Institute of Scientific and Technical Information of China (English)

    Xiaofeng Wang; Yanqiu Cao; Yiqiang Lu; Qiqian Sha; Ji Liang

    2004-01-01

    A new sol-gel process for the preparation of ultrafine nickel hydroxide electrode materials was developed. The composite electrodes consisting of carbon nanotubes and Ni(OH)2 were developed by mixing the hydroxide and carbon nanotubes together in different mass ratios. In order to enhance energy density, a combined type pseudocapacitor/electric double layer capacitor was considered and its electrochemical properties were characterized by cyclic voltammetry and dc charge/discharge test. The combined capacitor shows excellent capacitor behavior with an operating voltage up to 1.6 V in KOH aqueous electrolyte. Stable charge/discharge behaviors were observed with much higher specific capacitance values of 24 F/g compared with that of EDLC (12F/g) by introducing 60% Ni(OH)2 in the anode material. By using the modified anode of a Ni(OH)2/carbon nanotubes composite electrode, the specific capacitance of the cell was less sensitive to discharge current density compared with that of the capacitor employing pure nickel hydroxide as anode. The combined capacitor in this study exhibits high energy density and stable power characteristics.

  18. Magnetoliposomes based on nickel/silica core/shell nanoparticles: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Ana Rita O.; Gomes, I.T.; Almeida, Bernardo G. [Centro de Física (CFUM), Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Araújo, J.P. [IFIMUP/IN – Instituto de Nanociência e Nanotecnologia, R. Campo Alegre, 4169-007 Porto (Portugal); Castanheira, Elisabete M.S. [Centro de Física (CFUM), Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Coutinho, Paulo J.G., E-mail: pcoutinho@fisica.uminho.pt [Centro de Física (CFUM), Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2014-12-15

    In the present work, nickel magnetic nanoparticles with diameters lower than 100 nm, with and without silica shell, were synthesized by microheterogeneous templating. The magnetic properties of the nanoparticles show a typical ferromagnetic behavior with a coercive field of 80 Oe. Dry magnetoliposomes (DMLs) with diameter between 58 nm and 76 nm were obtained from the synthesis of nanoparticles in the presence of a lipid or surfactant layer, and aqueous magnetoliposomes (AMLs) were obtained by encapsulation of the nanoparticles in liposomes. FRET (Förster resonance energy transfer) experiments were performed to study the non-specific interactions between aqueous magnetoliposomes and giant unilamellar vesicles (GUVs), as models of cell membranes. It was possible to detect membrane fusion between GUVs and AMLs containing both NBD-C{sub 6}-HPC (donor) and the dye Nile Red (acceptor). - Highlights: • Magnetic nickel nanoparticles were synthesized in microheterogeneous media. • The nanoparticles were covered with a silica shell to improve biocompatibility. • Aqueous and dry magnetoliposomes were prepared, the latter with diameter around 70 nm. • Membrane fusion between magnetoliposomes and models of cell membranes was detected by FRET.

  19. Magnetoliposomes based on nickel/silica core/shell nanoparticles: Synthesis and characterization

    International Nuclear Information System (INIS)

    In the present work, nickel magnetic nanoparticles with diameters lower than 100 nm, with and without silica shell, were synthesized by microheterogeneous templating. The magnetic properties of the nanoparticles show a typical ferromagnetic behavior with a coercive field of 80 Oe. Dry magnetoliposomes (DMLs) with diameter between 58 nm and 76 nm were obtained from the synthesis of nanoparticles in the presence of a lipid or surfactant layer, and aqueous magnetoliposomes (AMLs) were obtained by encapsulation of the nanoparticles in liposomes. FRET (Förster resonance energy transfer) experiments were performed to study the non-specific interactions between aqueous magnetoliposomes and giant unilamellar vesicles (GUVs), as models of cell membranes. It was possible to detect membrane fusion between GUVs and AMLs containing both NBD-C6-HPC (donor) and the dye Nile Red (acceptor). - Highlights: • Magnetic nickel nanoparticles were synthesized in microheterogeneous media. • The nanoparticles were covered with a silica shell to improve biocompatibility. • Aqueous and dry magnetoliposomes were prepared, the latter with diameter around 70 nm. • Membrane fusion between magnetoliposomes and models of cell membranes was detected by FRET

  20. Nickel-based gadolinium alloy for neutron adsorption application in ram packages

    International Nuclear Information System (INIS)

    This paper will outline the results of a metallurgical development program that is investigating the alloying of gadolinium into a nickel-chromium-molybdenum alloy matrix. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section and low solubility in the expected U.S. repository environment. The nickel-chromium-molybdenum alloy family was chosen for its known corrosion performance, mechanical properties, and weldability. The workflow of this program includes chemical composition definition, primary and secondary melting studies, ingot conversion processes, properties testing, and national consensus codes and standards work. The microstructural investigation of these alloys shows that the gadolinium addition is not soluble in the primary austenite metallurgical phase and is present in the alloy as gadolinium-rich second phase. This is similar to what is observed in a stainless steel alloyed with boron. The mechanical strength values are similar to those expected for commercial Ni-Cr-Mo alloys. The alloys have been corrosion tested in simulated Yucca Mountain aqueous chemistries with acceptable results. The initial results of weldability tests have also been acceptable. Neutronic testing in a moderated critical array has generated favorable results. An American Society for Testing and Materials material specification has been issued for the alloy and a Code Case has been submitted to the American Society of Mechanical Engineers for code qualification. The ultimate goal is acceptance of the alloy for use at the Yucca Mountain repository

  1. Nickel foam-based manganese dioxide-carbon nanotube composite electrodes for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jun; Zhitomirsky, Igor [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario (Canada); Yang, Quan Min [Inco Technical Services, Mississauga, Ontario (Canada)

    2008-12-01

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 {mu}m and a diameter of about 2-4 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of slurries of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNTs) into porous nickel foam current collectors. In the composite electrodes, MWCNT formed a secondary conductivity network within the nickel foam cells. Obtained composite electrodes, containing 0-20 wt.% MWCNT with total mass loading of 40 mg cm{sup -2}, showed a capacitive behavior in the 0.1-0.5 M Na{sub 2}SO{sub 4} solutions. The highest specific capacitance (SC) of 155 F g{sup -1} was obtained at a scan rate of 2 mV s{sup -1} in the 0.5 M Na{sub 2}SO{sub 4} solutions. The SC increased with increasing MWCNT content in the composite materials and increasing Na{sub 2}SO{sub 4} concentration in the solutions and decreased with increasing scan rate. (author)

  2. Nickel foam-based manganese dioxide-carbon nanotube composite electrodes for electrochemical supercapacitors

    Science.gov (United States)

    Li, Jun; Yang, Quan Min; Zhitomirsky, Igor

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 2-4 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of slurries of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNTs) into porous nickel foam current collectors. In the composite electrodes, MWCNT formed a secondary conductivity network within the nickel foam cells. Obtained composite electrodes, containing 0-20 wt.% MWCNT with total mass loading of 40 mg cm -2, showed a capacitive behavior in the 0.1-0.5 M Na 2SO 4 solutions. The highest specific capacitance (SC) of 155 F g -1 was obtained at a scan rate of 2 mV s -1 in the 0.5 M Na 2SO 4 solutions. The SC increased with increasing MWCNT content in the composite materials and increasing Na 2SO 4 concentration in the solutions and decreased with increasing scan rate.

  3. Kinetics of passivation of a nickel-base alloy in high temperature water

    International Nuclear Information System (INIS)

    The kinetics of passivation and the composition of the surface oxide layer, in high temperature and high pressure water, of a nickel-chromium-iron alloy (Alloy 600) have been investigated by X-ray Photoelectron Spectroscopy (XPS). The samples have been exposed for short (0.4 - 8.2 min) and longer (0 - 400 hours) time periods to high temperature (325 deg. C) and high pressure water (containing boron and lithium) under controlled hydrogen pressure. The experiments were performed in two types of autoclaves: a novel autoclave dedicated to short time periods and a classic static autoclave for the longer exposures. In the initial stage of passivation, a continuous ultra-thin layer of chromium oxide (Cr2O3) is rapidly formed on the surface with an external layer of chromium hydroxide. For longer times of passivation, the oxide layer is in a duplex form with an internal chromium oxide layer and an external layer of nickel hydroxide. The growth of the internal Cr2O3 oxide layer has been fitted by three classical models (parabolic, logarithmic and inverse logarithmic laws) for the short passivation times, and the growth curves have been extrapolated to longer passivation periods. The comparison with the experimental results reveals that the kinetics of passivation of Alloy 600 in high temperature and high pressure water, for passivation times up to 400 hours, is well fitted by a logarithmic growth law. (authors)

  4. Kinetics of passivation of a nickel-base alloy in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Machet, A. [Laboratoire de Physico-Chimie des Surfaces, CNRS-ENSCP (UMR 7045), Ecole Nationale Superieure de Chimie de Paris, Universite Pierre et Marie Curie, F-75231 Paris cedex 05 (France)]|[Framatome ANP, Tour AREVA, F-92084 Paris-la-Defense (France); Galtayries, A.; Zanna, S.; Marcus, P. [Laboratoire de Physico-Chimie des Surfaces, CNRS-ENSCP (UMR 7045), Ecole Nationale Superieure de Chimie de Paris, Universite Pierre et Marie Curie, F-75231 Paris cedex 05 (France); Jolivet, P.; Scott, P. [Framatome ANP, Tour AREVA, F-92084 Paris-la-Defense (France); Foucault, M.; Combrade, P. [Framatome ANP, Centre Technique, F-71205 Le Creusot (France)

    2004-07-01

    The kinetics of passivation and the composition of the surface oxide layer, in high temperature and high pressure water, of a nickel-chromium-iron alloy (Alloy 600) have been investigated by X-ray Photoelectron Spectroscopy (XPS). The samples have been exposed for short (0.4 - 8.2 min) and longer (0 - 400 hours) time periods to high temperature (325 deg. C) and high pressure water (containing boron and lithium) under controlled hydrogen pressure. The experiments were performed in two types of autoclaves: a novel autoclave dedicated to short time periods and a classic static autoclave for the longer exposures. In the initial stage of passivation, a continuous ultra-thin layer of chromium oxide (Cr{sub 2}O{sub 3}) is rapidly formed on the surface with an external layer of chromium hydroxide. For longer times of passivation, the oxide layer is in a duplex form with an internal chromium oxide layer and an external layer of nickel hydroxide. The growth of the internal Cr{sub 2}O{sub 3} oxide layer has been fitted by three classical models (parabolic, logarithmic and inverse logarithmic laws) for the short passivation times, and the growth curves have been extrapolated to longer passivation periods. The comparison with the experimental results reveals that the kinetics of passivation of Alloy 600 in high temperature and high pressure water, for passivation times up to 400 hours, is well fitted by a logarithmic growth law. (authors)

  5. NUMERICAL STUDY OF THE NOTCH EFFECT ON THE CREEP BEHAVIOR AND LIFE OF NICKEL-BASE SINGLE CRYSTAL SUPERALLOYS

    Institute of Scientific and Technical Information of China (English)

    Q.M. Yu; Z.F. Yue

    2004-01-01

    Numerical calculations of creep damage development and life behavior of circular notched specimens of nickel-base single crystal had been performed. The creep stress distributions depend on the specimen geometry. For a small notch radius, von Mises stress has an especial distribution. The damage distribution is greatly influenced by the notch depth, notch radius as well as notch type. The creep crack initiation place is different for each notched specimen. The characteristics of notch strengthening and notch weakening depend on the notch radius and notch type. For the same notch type,the creep rupture lives decrease with the decreasing of notch radius. A creep life model has been presented for the multiaxial stress states based on the crystallographic slip system theory.

  6. Surface Reaction Kinetics of Steam- and CO2-Reforming as Well as Oxidation of Methane over Nickel-Based Catalysts

    Directory of Open Access Journals (Sweden)

    Karla Herrera Delgado

    2015-05-01

    Full Text Available An experimental and kinetic modeling study on the Ni-catalyzed conversion of methane under oxidative and reforming conditions is presented. The numerical model is based on a surface reaction mechanism consisting of 52 elementary-step like reactions with 14 surface and six gas-phase species. Reactions for the conversion of methane with oxygen, steam, and CO2 as well as methanation, water-gas shift reaction and carbon formation via Boudouard reaction are included. The mechanism is implemented in a one-dimensional flow field description of a fixed bed reactor. The model is evaluated by comparison of numerical simulations with data derived from isothermal experiments in a flow reactor over a powdered nickel-based catalyst using varying inlet gas compositions and operating temperatures. Furthermore, the influence of hydrogen and water as co-feed on methane dry reforming with CO2 is also investigated.

  7. Evidence of multimicrometric coherent γ' precipitates in a hot-forged γ-γ' nickel-based superalloy.

    Science.gov (United States)

    Charpagne, M-A; Vennéguès, P; Billot, T; Franchet, J-M; Bozzolo, N

    2016-07-01

    This paper demonstrates the existence of large γ' precipitates (several micrometres in diameter) that are coherent with their surrounding matrix grain in a commercial γ-γ' nickel-based superalloy. The use of combined energy dispersive X-ray spectrometry and electron backscattered diffraction (EBSD) analyses allowed for revealing that surprising feature, which was then confirmed by transmission electron microscopy (TEM). Coherency for such large second-phase particles is supported by a very low crystal lattice misfit between the two phases, which was confirmed thanks to X-ray diffractograms and TEM selected area electron diffraction patterns. Dynamic recrystallization of polycrystalline γ-γ' nickel-based superalloys has been extensively studied in terms of mechanisms and kinetics. As in many materials with low stacking fault energy, under forging conditions, the main softening mechanism is discontinuous dynamic recrystallization. This mechanism occurs with preferential nucleation on the grain boundaries of the deformed matrix. The latter is then being consumed by the growth of the newly formed grains of low energy and by nucleation that keeps generating new grains. In the case of sub-solvus forging, large γ' particles usually pin the migrating boundaries and thus limit grain growth to a size which is determined by the distribution of second-phase particles, in good agreement with the Smith-Zener model. Under particular circumstances, the driving force associated with the difference in stored energy between the growing grains and the matrix can be large enough that the pinning forces can be overcome, and some grains can then reach much larger grain sizes. In the latter exceptional case, some intragranular primary γ' particles can be observed, although they are almost exclusively located on grain boundaries and triple junctions otherwise. In both cases, primary precipitates have no special orientation relationship with the surrounding matrix grain(s). This

  8. Synthesis and Crystal Structure Determination of a Nickel(II Complex of an Acyclic Pentadentate (N5 Mono Schiff Base Ligand

    Directory of Open Access Journals (Sweden)

    R. V. Parish

    2001-10-01

    Full Text Available The asymmetrical tripodal tetraamine ligand N[(CH23NH2]2[(CH22NH2] (ppe was condensed with 2-acetylpyridine in the presence of nickel(II ion. In ethanolwater solution the reaction stops after the first stage of condensation, and a new nickel(II complex of an acyclic pentadentate (N5 mono Schiff base ligand was obtained. X-ray structure analysis of the resulting complex, [Ni(ppe-py(H2O](ClO42, indicates that condensation with 2-acetylpyridine is at the propylene chain of ppe. The geometry around the nickel ion is distorted octahedral in which the sixth co-ordination group is a solvent molecule.

  9. Low cycle fatigue life of two nickel-base casting alloys in a hydrogen environment. [for high-pressure oxidizer turbopump turbine nozzles

    Science.gov (United States)

    Cooper, R. A.

    1976-01-01

    Samples of two nickel-base casting alloys, Mar-M-246 (a Martin Company alloy) and 713LC (a low-carbon modification of the alloy 713C developed by International Nickel Company) were tested as candidate materials for the high-pressure fuel and high-pressure oxidizer turbopump turbine nozzles. The samples were subjected to tensile tests and to low cycle fatigue tests in high-pressure hydrogen to study the influence of the hydrogen environment. The Mar-M-246 material was found to have a three times higher cyclic life in hydrogen than the 713LC alloy, and was selected as the nozzle material.

  10. Mechanism of strontium sorption by the mixed nickel-potassium ferrocyanide based on hydrated titanium dioxide

    International Nuclear Information System (INIS)

    The influence of surface modification of hydrated titanium dioxide (HTD) by mixed nickel-potassium ferrocyanide (NPF) phase on its selectivity for strontium and mechanism of strontium sorption was studied. It was shown that NPF-HTD sorbent possesses the same selectivity for strontium as the HTD sorbent, but higher static exchange capacity (SEC). The Henry distribution coefficient of strontium from a tap water with pH 7.8 ± 0.1 was 10(3.0±0.3) L kg-1; the SEC, calculated according to Langmuir's isotherm, was 140 mg g-1. Kinetic studies have shown that strontium sorption is limited by both internal and external diffusion as well as by the rate of chemical transformation of the NPF-HTD sorbent. (author)

  11. CO hydrogenation on nickel-based catalysts: Effects of copper addition

    Energy Technology Data Exchange (ETDEWEB)

    Agnelli, M.; Mirodatos, C.

    2000-05-15

    The effect of copper addition on the catalytic properties of silica-supported nickel catalysts for the reaction of CO hydrogenation in the temperature range of 200--500 C has been investigated. Different effects, positive or negative, depending on the temperature and the copper content, are described and explained. At low temperature (230 C), the addition of low copper content prevents the loss of the active surface by sintering without inhibiting the rate of CO hydrogenation too much. At high temperatures (450 C), high copper content is necessary to limit the accumulation of poisonous carbon products, but at the expense of CO conversion. On the basis of the various kinetic and morphologic effects of copper addition, an advanced description of the CO hydrogenation mechanism is also provided, assuming an active site formed by 2--3 adjacent Ni atoms, whatever the temperature or the copper content may be.

  12. Electron microscopy study of the deactivation of nickel based catalysts for bio oil hydrodeoxygenation

    DEFF Research Database (Denmark)

    Gardini, Diego; Mortensen, Peter Mølgaard; Carvalho, Hudson W. P.;

    2014-01-01

    Hydrodeoxygenation (HDO) is proposed as an efficient way to remove oxygen in bio-oil, improving its quality as a more sustainable alternative to conventional fuels in terms of CO2 neutrality and relative short production cycle [1]. Ni and Ni-MoS2 nanoparticles supported on ZrO2 show potential as...... study of this element through STEM-EDX. Moreover, nickel sintering was observed in the KCl poisoned sample and was ascribed once again to the formation of mobile Ni-Cl species upon reaction of HCl with surface oxides [4]. Furthermore, environmental transmission electron microscopy (ETEM) has been used...... high-pressure (100 bar) catalysts for purification of bio-oil by HDO. However, the catalysts deactivate in presence of sulfur, chlorine and potassium species, which are all naturally occurring in real bio-oil. The deactivation mechanisms of the Ni/ZrO2 have been investigated through scanning...

  13. Microfabricated nickel-based electrodes for high-power battery applications

    International Nuclear Information System (INIS)

    High-surface area, three-dimensional (3D) microstructures are designed and fabricated by the sequential electroplating of sacrificial and structural layers in a photoresist mold. A conformal coating of electrochemically deposited nickel hydroxide (Ni(OH)2) films on these MEMS-enabled multilayer structures enabled the formation of functional electrodes for electrochemical energy storage devices. The characterization of the electrodes is performed galvanostatically at various charge and discharge rates. Electrodes with a varying number of laminations are shown to yield areal capacities from 0.1 to 5.2 mAh cm–2. Power characteristics of the electrodes are determined by applying ultra-high charge rates of up to 120 C. At this high charge rate, the electrode is able to deliver 90% of its capacity. (paper)

  14. Synthesis, characterization and DNA cleavage activity of nickel(II adducts with aromatic heterocyclic bases

    Directory of Open Access Journals (Sweden)

    G. H. PHILIP

    2010-01-01

    Full Text Available Mixed ligand complexes of nickel(II with 2,4-dihydroxyaceto-phenone oxime (DAPO and 2,4-dihydroxybenzophenone oxime (DBPO as primary ligands, and pyridine (Py and imidazole (Im as secondary ligands were synthesized and characterized by molar conductivity, magnetic moments measurements, as well as by electronic, IR, and 1H-NMR spectroscopy. Electrochemical studies were performed by cyclic voltammetry. The active signals are assignable to the NiIII/II and NiII/I redox couples. The binding interactions between the metal complexes and calf thymus DNA were investigated by absorption and thermal denaturation. The cleavage activity of the complexes was determined using double-stranded pBR322 circular plasmid DNA by gel electrophoresis. All complexes showed increased nuclease activity in the presence of the oxidant H2O2. The nuclease activities of mixed ligand complexes were compared with those of the parent copper(II complexes.

  15. Nickel based alloys as electrocatalysts for oxygen evolution from alkaline solutions. [Metal--air batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lu, P.W.T.; Srinivasan, S.

    1977-01-01

    The slowness of the oxygen evolution reaction is one of the main reasons for significant energy losses in water electrolysis cells and secondary air--metal batteries. To date, data on the kinetics of this reaction on alloys and intermetallic compounds are sparse. In this work, mechanically polished alloys of nickel with Ir, Ru or W and Ni--Ti intermetallic compounds were studied as oxygen electrodes. Since the oxygen evolution reaction always takes place on oxide-film covered surfaces, the nature of oxide films formed on these alloys were investigated using cyclic voltametric techniques. Steady-state potentiostatic and slow potentiodynamic (at 0.1 mV/s) methods were employed to obtain the electrode kinetic parameters for the oxygen evolution reaction in 30 wt. percent KOH at 80/sup 0/C, the conditions normally used in water electrolysis cells. The peaks for the formation or reduction of oxygen-containing layers appearing on the pure metals are not always found on the alloys. The maximum decreases in oxygen overpotential at an apparent current density of 20 mA cm/sup -2/ (as compared with that on Ni) were found for the alloys of 50Ni--50Ir and 75Ni--25Ru and the intermetallic compound Ni/sub 3/Ti, these decreases being about 40, 30, and 20 mV, respectively. On the long-term polarization in the potential region of oxygen evolution, the oxygen-containing layers on Ni--Ir or Ni--Ru alloys are essentially composed of nickel oxides instead of true mixed oxide films of two components. The present work confirms that, possibly because of coverage by oxide films, there is no direct dependence of the electrocatalytic activities of the alloys on their electronic properties. 11 figures, 1 table.

  16. Laboratory studies of the corrosion of nickel-based alloys by pure calcium sulfate -- Influence of environmental factors

    Energy Technology Data Exchange (ETDEWEB)

    Pomeroy, M.J.; Farhat, A.; McHale, P. [Univ. of Limerick (Ireland). Dept. of Materials Science and Technology

    1998-12-31

    Several nickel-based alloys and for comparison purposes, iron- and cobalt-based alloys have been coated with 8--10{micro}m Analar calcium sulfate and exposed in three types of external environments at a temperature of 850 C. Results from experiments in which the coated coupons were totally immersed in lightly compacted Analar-grade calcium sulfate powder and exposed in air for 144 hours showed that they underwent sulfidation-oxidation corrosion. Control experiments with no coating resulted in the formation of oxides alone, confirming that the presence of a compact calcium sulfate overlay was crucial to the development of the conditions necessary to cause sulfidation-oxidation corrosion. Relative extents of corrosion for the alloys showed distinct similarities with those observed in pilot scale coal-fired fluidized bed combustion systems. This fact together with the observation that corrosion morphologies for the alloys tested were similar to those observed in operating systems, demonstrates that the laboratory test method developed in this work is a suitable screening test for alloys with suitable mechanical properties for this industrial application. Subsequent sets of experiments at the same temperature, in which coated coupon surfaces were exposed to a synthetic flue gas containing 0.2% by volume sulfur dioxide for 144 hours, gave results which showed that sulfur exhaustion from the coating did not occur in the air environment. Thus, corrosion morphologies and extents of corrosion for the two different environments were effectively the same. The effect of substoichiometric conditions on the corrosion of the coated alloys was investigated by immersing the coupons in a calcium sulfate covered with finely divided carbon to give a sulfate to carbon mole ratio of 1:2. After 24 hours exposure at 85O C, significant corrosion of the nickel-based alloys occurred. The greater degree of corrosive attack can be attributed to the high partial pressures of sulfur vapor which

  17. Mononuclear thiocyanate containing nickel(II) and binuclear azido bridged nickel(II) complexes of N4-coordinate pyrazole based ligand: Syntheses, structures and magnetic properties

    Science.gov (United States)

    Solanki, Ankita; Monfort, Montserrat; Kumar, Sujit Baran

    2013-10-01

    Two mononuclear nickel(II) complexes [NiL1(NCS)2] (1) and [NiL2(NCS)2] (2) and two azido bridged binuclear nickel(II) complexes [Ni(()2()2] (3) and [Ni(()2()2] (4), where L1, L2, L1‧ and L2‧ are N,N-diethyl-N‧,N‧-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine (L1), N,N-bis((1H-pyrazol-1-yl)methyl)-N‧,N‧-diethylethane-1,2-diamine (L2), N,N-diethyl-N‧-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine (L1‧) and N-((1H-pyrazol-1-yl)methyl)-N‧,N‧-diethylethane-1,2-diamine (L2‧) have been synthesized and characterized by microanalyses and physico-chemical methods. Single crystal X-ray diffraction analyses revealed that complexes 1 and 2 are mononuclear NCS- containing Ni(II) complex with octahedral geometry and complexes 3 and 4 are end-on (μ-1,1) azido bridged binuclear Ni(II) complexes with distorted octahedral geometry. Variable temperature magnetic studies of the complexes 3 and 4 display ferromagnetic interaction with J values 19 and 32 cm-1, respectively.

  18. Colourimetric and fluorescent detection of oxalate in water by a new macrocycle-based dinuclear nickel complex: a remarkable red shift of the fluorescence band†

    Science.gov (United States)

    Rhaman, Md Mhahabubur; Fronczek, Frank R.; Powell, Douglas R.; Hossain, Md. Alamgir

    2014-01-01

    A new macrocycle-based dinuclear nickel chemosensor selectively binds oxalate anions both in solution and the solid state, displaying a remarkable red shift of the fluorescence band with a visible colour change in water at physiological pH in the presence of an external dye. PMID:24419223

  19. Colourimetric and fluorescent detection of oxalate in water by a new macrocycle-based dinuclear nickel complex: a remarkable red shift of the fluorescence band.

    Science.gov (United States)

    Rhaman, Md Mhahabubur; Fronczek, Frank R; Powell, Douglas R; Hossain, Md Alamgir

    2014-03-28

    A new macrocycle-based dinuclear nickel chemosensor selectively binds oxalate anions both in solution and the solid state, displaying a remarkable red shift of the fluorescence band with a visible colour change in water at physiological pH in the presence of an external dye. PMID:24419223

  20. Colourimetric and fluorescent detection of oxalate in water by a new macrocycle-based dinuclear nickel complex: a remarkable red shift of the fluorescence band†

    OpenAIRE

    Rhaman, Md Mhahabubur; Fronczek, Frank R.; Powell, Douglas R.; Hossain, Md. Alamgir

    2014-01-01

    A new macrocycle-based dinuclear nickel chemosensor selectively binds oxalate anions both in solution and the solid state, displaying a remarkable red shift of the fluorescence band with a visible colour change in water at physiological pH in the presence of an external dye.

  1. Stereological characterization of the γ' particles in a nickel base superalloy: Comparison between transmission electron microscopy and atomic force microscopy techniques

    International Nuclear Information System (INIS)

    Critical comparison of transmission electron microscopy and atomic force microscopy techniques was provided concerning size measurements of γ' precipitates in a nickel-base superalloy. The divergence between results is explained in terms of the resolution limit for atomic force microscopy, linked both to the tip dimension and the diameter of the investigated particles

  2. Influence of dynamic strain aging on the near-threshold fatigue crack growth behavior of a new single crystal nickel-based superalloy

    International Nuclear Information System (INIS)

    In recent years, the design requirements of advanced gas turbine engines have led to the development of directionally solidified single crystal nickel-based superalloys. Among these alloys, CMSX-4 is a new second-generation single crystal nickel-based superalloy containing rhenium. This alloy has been developed from the first-generation CMSX alloys. It has superior hot corrosion resistance and higher creep-rupture strength than first-generation single crystal nickel-based superalloys and is an attractive candidate for complex components that require continuous exposure to very high temperatures. Due to its potential applications in turbine blades, rotors and nuclear reactors, etc., the fatigue crack growth rate (FCGR) and fatigue threshold (FT) data of this material are extremely important for safe life prediction as well as failure safe design at elevated temperatures. Preliminary studies by these authors have indicated that this material is probably undergoing dynamic strain aging (DSA) in the temperature range of 260 to 800 C. However, the effect of DSA on FCGR and FT is not well known or established for single crystal nickel-based superalloys. The objective of this investigation was to determine the effect of DSA on FCGR and FT of CMSX-4 at the temperature range of 650 and 800 C

  3. The effect of microstructure on the creep behavior of a low rhenium-containing single crystal nickel-based superalloy

    International Nuclear Information System (INIS)

    A low rhenium-containing single crystal nickel-based superalloy designated DD6 with different γ′ morphologies induced by discrepant aging treatments crept at 1100 °C/137 MPa and 850 °C/660 MPa. The test results and TEM observations showed that creep mechanism varies with microstructure and test temperature. For creep at 1100 °C/137 MPa, the dislocation network on γ/γ′ interface plays a key role in prolonging creep life. The sample with the lager cubical γ′ precipitate got the longest rupture life. For creep at 850 °C/660 MPa, the morphology of γ′ phase and the width of the γ channels dominate the deformation behavior. The sample with smaller γ′ particles and narrower γ channel exhibited the highest creep life due to the inhomogeneous activations of multiple 〈112〉 {111} slip systems

  4. Kinetics and mechanism of reaction between water vapor, carbon monoxide and a chromia-forming nickel base alloy

    International Nuclear Information System (INIS)

    The kinetic aspects of the competitive reaction of CO and H2O in the formation of chromia layer on a nickel base alloy at high temperature were studied by thermogravimetry combined to gas phase chromatography. It was shown that competitive adsorption occurred between both molecules and that whatever P(CO)/P(H2O) ratio, CO mainly reacted in the first instants of oxidation and H2O became the main long-term oxidant species. After an interfacial and diffusion mixed kinetic regime, the long-term oxidation rate was parabolic and did not depend on the water vapor content in the gas phase. The oxidation kinetics was well described by considering that the rate limiting step was the outwards diffusion of interstitial chromium cations in the oxide layer. (authors)

  5. Synthesis and magnetic properties of a 1-D helical chain derived from a Nickel-Sodium Schiff base complex

    Indian Academy of Sciences (India)

    Apoorva Upadhyay; Chinmoy Das; Shaik Nagul Meera; Stuart K Langley; Keith S Murray; Maheswaran Shanmugam

    2014-09-01

    The reaction of the deprotonated form of the Schiff base ligand; (E)-2-methoxy-6-((phenylimino) methyl)phenol (L) with nickel chloride hydrate results in the formation of the 1-dimentional coordination polymer; Na[Ni(L)2(OMe)(MeOH)] (1). The structure was determined via single crystal X-ray diffraction measurements. A careful analysis of the complex shows that the polymer exists as a helical structure, where the helicity is brought about by the presence of an alkali metal ion which is observed for the first time. Moreover the helical structure in 1 is maintained predominantly through covalent bond rather than supramolecular interactions. Direct current magnetic susceptibility measurement suggests that complex 1 obeys the Curie law. The fitting of magnetic data using the PHI software package yields parameters of = 1, = 2.26 and = +4.51 (or = −7.24cm-1) for 1.

  6. Oxide-layer formation and stability on a nickel-base alloy in impure helium at high temperature

    International Nuclear Information System (INIS)

    The corrosion behavior in impure helium of Haynes 230, a nickel base alloy candidate for heat exchangers in Very High Temperature Reactors (VHTR), has been investigated. The study focused on the formation and the subsequent destruction of the surface oxide layer at 900 C and 980 C. In-situ gas-phase analysis coupled to post-exposure surface analyses showed that a chromium-rich surface oxide formed on Haynes 230 at 900 C but was unstable above a critical temperature TA: the chromium-rich oxide reacted with carbon in solution in the alloy to produce chromium and CO(g). The effect of carbon monoxide partial pressure in the gas phase as well as the influence of chromium and carbon activities in the alloy on TA are discussed taking thermodynamics and kinetics aspects into account. (authors)

  7. Influence of cubic boron nitride grinding on the fatigue strengths of carbon steels and a nickel-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Kawagoishi, N.; Chen, Q.; Kondo, E. [Kagoshima Univ. (Japan). Faculty of Engineering; Goto, M. [Oita Univ. (Japan). Faculty of Engineering; Nisitani, H. [Kyushu Sangyo Univ., Fukuoka (Japan). Faculty of Engineering

    1999-04-01

    The influence of cubic boron nitride (CBN) grinding on fatigue strength was investigated on an annealed carbon steel, a quenched and tempered carbon steel at room temperature, and a nickel-base superalloy, Inconel 718, at room temperature and 500 C. The results were discussed from several viewpoints, including surface roughness, residual stress, and work hardening or softening due to CBN grinding. The fatigue strength increased upon CBN grinding at room temperature, primarily because of the generation of compressive residual stress in the surface region. However, in the case of Inconel 718, this marked increase in the fatigue strength tended to disappear at the elevated temperature due to the release of compressive residual stress and the decrease of crack growth resistance at an elevated temperature.

  8. Effects of silicon on the oxidation, hot-corrosion, and mechanical behavior of two cast nickel-base superalloys

    Science.gov (United States)

    Miner, R. V., Jr.

    1977-01-01

    Cast specimens of nickel-base superalloys 713C and Mar-M200 with nominal additions of 0, 0.5, and 1 wt% Si were evaluated for oxidation and corrosion resistance, tensile and stress-rupture properties, microstructure, and phase relations. Results are compared with those of an earlier study of the effects of Si in B-1900. Si had similar effects on all three superalloys. It improves oxidation resistance but the improvement in 713C and Mar-M200 was considerably less than in B-1900. Hot-corrosion resistance is also improved somewhat. Si is, however, detrimental to mechanical properties, in particular, rupture strength and tensile ductility. Si has two obvious microstructural effects. It increases the amount of gamma-prime precipitated in eutectic nodules and promotes a Mo(Ni,Si)2 Laves phase in the alloys containing Mo. These microstructural effects do not appear responsible for the degradation of mechanical properties, however.

  9. Corrosion characterisation of laser beam and tungsten inert gas weldment of nickel base alloys: Micro-cell technique

    International Nuclear Information System (INIS)

    Highlights: • Grain matrix showed better corrosion resistance than grain boundary. • Microcell studies showed distinct corrosion behaviour of individual regions of weldment. • TIG welding resulted in increased stable anodic current density on weld fusion zone. • LB welding resulted in high stable anodic current density for heat affected zone. - Abstract: The electrochemical studies using micro-cell technique gave new understanding of electrochemical behaviour of nickel base alloys in solution annealed and welded conditions. The welding simulated regions depicted varied micro structural features. In case of tungsten inert gas (TIG) weldments, the weld fusion zone (WFZ) showed least corrosion resistance among all other regions. For laser beam (LB) weldments it was the heat-affected zone (HAZ) that showed comparatively high stable anodic current density. The high heat input of TIG welding resulted in slower heat dissipation hence increased carbide precipitation and segregation in WFZ resulting in high stable anodic current density

  10. Hot corrosion studies of four nickel-base superalloys - B-1900, NASA-TRW VIA, 713C and IN738

    Science.gov (United States)

    Fryburg, G. C.; Kohl, F. J.; Stearns, C. A.

    1976-01-01

    The susceptibility to hot corrosion of four nickel-base superalloys has been studied at 900 and 1000 C in one atmosphere of slowly flowing oxygen. Hot corrosion was induced by coating the samples with known doses of Na2SO4 and oxidizing the coated samples isothermally on a sensitive microbalance. In order of decending susceptibility to hot corrosion, these alloys were ranked: B-1900, 713C, NASA-TRW VIA, IN738. This order corresponds to the order of decreasing molybdenum content of the alloys. Chemical evidence for B-1900 indicates that hot corrosion is instigated by acid fluxing of the protective Al2O3 coating by MoO3.

  11. Hot corrosion studies of four nickel-base superalloys: B-1900, NASA-TRW VIA, 713C and IN738

    Science.gov (United States)

    Fryburg, G. C.; Kohl, F. J.; Stearns, C. A.

    1976-01-01

    The susceptibility to hot corrosion of four nickel base superalloys has been studied at 900 deg and 1000 deg C in one atmosphere of slowly flowing oxygen. Hot corrosion was induced by coating the samples with known doses of NaSO4 and oxidizing the coated samples isothermally on a sensitive microbalance. In general, the order of susceptibility found was: B-1900 is greater than 713C is greater than NASA-TRW VIA and is greater than IN738. This order corresponds to the order of decreasing molybdenum content of the alloys. Chemical evidence for B-1900 indicates that hot corrosion is instigated by acid fluxing of the protective Al2O3 coating by MoO3.

  12. The Investigation of Active Sites on Nickel Oxide Based Catalysts towards the In-situ Reactions of Methanation and Desulfurization

    OpenAIRE

    Wan Azelee Wan Abu Bakar; Mohd. Yusuf Othman; Rusmidah Ali; Ching Kuan Yong; Susilawati Toemen

    2009-01-01

    Supported nickel oxide based catalysts of Fe/ Co/ Ni (10: 30: 60)-Al2O3 and Pr/ Co/ Ni (5: 35: 60)-Al2O3 that were prepared by wetness impregnation method showed potential catalysts for the in-situ reactions of H2S desulfurization and CO2 methanation from ambient temperature up to 300 oC.  X-ray Photoelectron Spectroscopy revealed Ni2O3 and Fe3O4 as the surface active components on the Fe/ Co/ Ni (10: 30: 60)-Al2O3 catalyst, while Ni2O3 and Co3O4 on the Pr/ Co/ Ni (5: 35: 60)-Al2O3 catalyst. ...

  13. Study of the cyclic softening of an under-aged gamma'-precipitated nickel-base superalloy (Waspaloy)

    Energy Technology Data Exchange (ETDEWEB)

    Risbet, M.; Feaugas, X.; Clavel, M. [Universite de Technologie de Compiegne (France). Lab. Roberval

    2001-09-01

    This study deals with the cyclic behaviour at room temperature of a nickel-base superalloy, strengthened by shearable {gamma}' precipitates. A special attention is paid to the influence of the controlled plastic strain {epsilon}{sub a}. Whatever {epsilon}{sub a}, a softening of the stress amplitude follows the first cycles hardening stage. This phenomenon is discussed in terms of back and effective stress evolutions. The decreasing of the total stress amplitude is mainly carried by the kinematic stress lowering, except for the lowest plastic strain level (0.05%), where the isotropic stress decreasing predominates. With the help of dislocations features, the internal stress is analyzed as a consequence of simultaneous activation of several slip systems. (orig.)

  14. Study of the cyclic softening of an under-aged gamma'-precipitated nickel-base superalloy (Waspaloy)

    International Nuclear Information System (INIS)

    This study deals with the cyclic behaviour at room temperature of a nickel-base superalloy, strengthened by shearable γ' precipitates. A special attention is paid to the influence of the controlled plastic strain εa. Whatever εa, a softening of the stress amplitude follows the first cycles hardening stage. This phenomenon is discussed in terms of back and effective stress evolutions. The decreasing of the total stress amplitude is mainly carried by the kinematic stress lowering, except for the lowest plastic strain level (0.05%), where the isotropic stress decreasing predominates. With the help of dislocations features, the internal stress is analyzed as a consequence of simultaneous activation of several slip systems. (orig.)

  15. Lifing the thermo-mechanical fatigue (TMF behaviour of the polycrystalline nickel-based superalloy RR1000

    Directory of Open Access Journals (Sweden)

    Jones Jonathan

    2014-01-01

    Full Text Available Microstructural damage and subsequent failures resulting from thermo-mechanical fatigue (TMF loading within the temperature range 300–700 ∘C are investigated for the polycrystalline nickel superalloy, RR1000. Strain controlled TMF experiments were conducted over various mechanical strain ranges, encompassing assorted phase angles, using hollow cylindrical test pieces. The paper explores two scenarios; the first where the mechanical strain range is held constant and comparisons of the fatigue life are made for different phase angle tests, and secondly, the difference between the behaviour of In-phase (IP and − 180 ∘ Out-Of-Phase (OOP tests over a variety of applied strain ranges. It is shown that different lifing approaches are currently required for the two scenarios, with a mean stress based approach being more applicable in the first case, whereas a Basquin-type model proves more appropriate in the second.

  16. Effects of aging in high temperature helium environments on room temperature tensile properties of nickel-base superalloys

    International Nuclear Information System (INIS)

    Research highlights: → Haynes 230 is susceptible to carburization, but Alloy 617 to decarburization and inter-granular oxidation. → Decarburization of Nickel-base superalloys can be accelerated in impure helium with H2. → Aging heat treatment causes inter-granular fracture primarily along inter-granular oxide and grain boundary carbides, which results in the loss of ductility. → Thin-plate specimen of Alloy 617 tends to favor failure by glide plane fracture when it is heavily decarburized. - Abstract: The influence of high temperature aging treatment on room temperature tensile properties of wrought nickel-base superalloys Alloy 617 and Haynes 230 was investigated. A significant decrease in elongation was observed for Alloy 617 exposed to a heavily oxidizing and decarburizing condition because of coarsening of grain boundary carbides and extensive inter-granular oxidation. On the other hand, Haynes 230 showed much lower ductility when exposed to a heavily carburizing condition, especially at 1000 deg. C because extensive carburization occurred due to a reaction with tungsten. Considerable loss of ductility for Alloy 617 and Haynes 230 was also observed in He-H2-H2O-CO-CO2-CH4 and He-H2O-CO-CO2 environments, which were the slightly oxidizing and decarburizing conditions. Loss of ductility was predominantly associated with brittle inter-granular cracking, while the extent of loss of ductility decreased depending on the decarburization depth. Decarburization was observed more extensively in helium with H2-H2O-CO-CO2-CH4 than helium with H2O-CO-CO2, and for Alloy 617 than for Haynes 230. Finally, the role of H2 in accelerating decarburization is discussed.

  17. Modeling the initiation of Primary Water Stress Corrosion Cracking in nickel base alloys 182 and 82 of Pressurized Water Reactors

    International Nuclear Information System (INIS)

    Nickel base welds are widely used to assemble components of the primary circuit of Pressurized Water Reactors (PWR) plants. International experience shows an increasing number of Stress Corrosion Cracks (SCC) in nickel base welds 182 and 82 which motivates the development of models predicting the time to SCC initiation for these materials. SCC involves several parameters such as materials, mechanics or environment interacting together. The goal of this study is to have a better understanding of the physical mechanisms occurring at grains boundaries involved in SCC. In-situ tensile test carried out on oxidized alloy 182 evidenced dispersion in the susceptibility to corrosion of grain boundaries. Moreover, the correlation between oxidation and cracking coupled with micro-mechanical simulations on synthetic polycrystalline aggregate, allowed to propose a cracking criterion of oxidized grain boundaries which is defined by both critical oxidation depth and local stress level. Due to the key role of intergranular oxidation in SCC and since significant dispersion is observed between grain boundaries, oxidation tests were performed on alloys 182 and 82 in order to model the intergranular oxidation kinetics as a function of chromium carbides precipitation, temperature and dissolved hydrogen content. The model allows statistical analyses and is embedded in a local initiation model. In this model, SCC initiation is defined by the cracking of the intergranular oxide and is followed by slow and fast crack growth until the crack depth reaches a given value. Simplifying assumptions were necessary to identify laws used in the SCC model. However, these laws will be useful to determine experimental conditions of future investigations carried out to improve the calibration used parameters. (author)

  18. Fatigue crack growth behavior of a new single crystal nickel-based superalloy (CMSX-4) at 650 C

    International Nuclear Information System (INIS)

    CMSX-4 is a recently developed rhenium containing single crystal nickel-based superalloy. This alloy has potential applications in many critical high-temperature applications such as turbine blades, rotors, nuclear reactors, etc. The fatigue crack growth rate and the fatigue threshold data of this material is extremely important for accurate life prediction, as well as failure safe design, at elevated temperatures. In this paper, the fatigue crack growth behavior of CMSX-4 has been studied at 650 C. The investigation also examined the influence of γ' precipitates (size and distribution) on the near-threshold fatigue crack growth rate and the fatigue threshold. The influence of load ratio on the fatigue crack growth rate and the fatigue threshold was also examined. Detailed fractographic studies were carried out to determine the crack growth mechanism in fatigue in the threshold region. Compact tension specimens were prepared from the single crystal nickel-based superalloy CMSX-4 with [001] orientation as the tensile loading axis direction. These specimens were given three different heat treatments to produce three different γ' precipitate sizes and distributions. Fatigue crack growth behavior of these specimens was studied at 650 C in air. The results of the present investigation indicate that the near-threshold fatigue crack growth rate decreases and that the fatigue threshold increases with an increase in the γ' precipitate size at 650 C. The fatigue threshold decreased linearly with an increase in load ratio. Fractographs at 650 C show a stage 2 type of crack growth along {100} type of crystal planes in the threshold region, and along {111} type of crystal planes in the high ΔK region

  19. Influence of element Re on lattice misfits and stress rupture properties of single crystal nickel-based superalloys

    International Nuclear Information System (INIS)

    By means of the measurement of XRD curves and SEM, TEM observation, an investigation has been made into the influence of the element Re on lattice misfits and stress rupture properties of single crystal nickel-based superalloys. Results show that the bigger lattice parameters and misfit appear in 2% Re as-cast single crystal nickel-based superalloy due to the composition segregation and non-homogeneous distribution of the γ' phase in size. After the alloy is fully heat treated, the cubical γ' phase is coherently precipitated in the γ matrix phase, and the parameters and misfit of γ', γ phases decreases slightly. During the stress/stress-free aging, the coarsening of γ' phase occurs and the dislocation networks appear in the interfaces of the γ'/γ phases, which increases slightly the parameters and misfit of γ', γ phases. Compared to the γ matrix phase, the γ' phase has a smaller thermal dilation coefficient due to the smaller thermal capacity and the stronger combined force between the atoms, which increases the misfit between the parameters of γ' and γ phases in the alloy at the elevated temperature. The parameters of γ', γ phases in the alloys increase with the element Re content, and compared with the parameter of γ phase, the one of γ' phase increases to a bigger extent. Therefore, the misfits and mismatch stress of the γ'/γ interfaces in the alloys decrease with the increase of the element Re content, which reduces the rafted rate of γ' phase during stress aging and improves the stress rupture life of the alloys in the ranges of high temperature.

  20. Solidification characteristics and segregation behaviour of nickel-base-superalloys in dependence of different rhenium and ruthenium contents

    Energy Technology Data Exchange (ETDEWEB)

    Heckl, A.; Rettig, R.; Singer, R. [Erlangen Univ. (Germany). Lehrstuhl WTM

    2008-07-01

    Technical application like turbines in power plants are determined by high temperature materials, which can sustain severe thermal and mechanical stresses under extreme conditions. The state of the art is defined by Nickel-Base-Superalloys, as they combine high mechanical fatigue and creep strength, long-term phase stability and good corrosion resistance up to very high homologous temperatures. Systematic alloy development to increase the turbine gas inlet temperature is fundamental for a continuous efficiency improvement, which simultaneously leads to a cost decrease of energy production, as well as lower CO2- emissions. The alloying element Rhenium (Re) is reported in the literature to a strong solid solution strengthener which promotes higher tensile strength as well as better creep properties. However, it also deteriorates the segregation behaviour during solidification which becomes a major problem with more demanding heat treatment processes in modern alloys. The inhomogeneous Re distribution promotes the formation of brittle topological-closedpacked (TCP) phases, which in turn can deteriorate the mechanical properties of the material. Additions of Ruthenium (Ru) appear to be advantageous through stabilization of the microstructure with respect to TCP-phase formation but also by reducing the degree to which Re partitions during solidification. The investigation of 12 Nickel-Base-Superalloys with different Re and Ru contents in the present paper allows to more fully characterize the influence of Re and Ru on the solidification process, segregation behaviour and mechanical properties of the material. Moreover, the results are compared with calculated prediction using ThermoCalc to verify the reliability of thermodynamic simulations. (orig.)

  1. TEM characterisation of stress corrosion cracks in nickel based alloys: effect of chromium content and chemistry of environment

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) is a damaging mode of alloys used in pressurized water reactors, particularly of nickel based alloys constituting the vapour generator tubes. Cracks appear on both primary and secondary sides of the tubes, and more frequently in locations where the environment is not well defined. SCC sensitivity of nickel based alloys depends of their chromium content, which lead to the replacement of alloy 600 (15 % Cr) by alloy 690 (30 % Cr) but this phenomenon is not yet very well understood. The goal of this thesis is two fold: i) observe the effect of chromium content on corrosion and ii) characterize the effect of environment on the damaging process of GV tubes. For this purpose, one industrial tube and several synthetic alloys - with controlled chromium content - have been studied. Various characterisation techniques were used to study the corrosion products on the surface and within the SCC cracks: SIMS; TEM - FEG: thin foil preparation, HAADF, EELS, EDX. The effect of chromium content and surface preparation on the generalised corrosion was evidenced for synthetic alloys. Moreover, we observed the penetration of oxygen along triple junctions of grain boundaries few micrometers under the free surface. SCC tests show the positive effect of chromium for contents varying from 5 to 30 % wt. Plastic deformation induces a modification of the structure, and thus of the protective character, of the internal chromium rich oxide layer. SCC cracks which developed in different chemical environments were characterised by TEM. The oxides which are formed within the cracks are different from what is observed on the free surface, which reveals a modification of medium and electrochemical conditions in the crack. Finally we were able to evidence some structural characteristics of the corrosion products (in the cracks and on the surface) which turn to be a signature of the chemical environment. (author)

  2. Xinjiang Nickel Production Topped 10,000 tonnes, with the Potential to Become the Second Largest Production Base in China

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>On December 26, 2012, as forklifts shipped the 10000th tonne of nickel plate into the finished product warehouse of Xinjiang Nonferrous Group Fukang Smelting Plant, Xinjiang’s annual production of electrolytic nickel for the first time topped 10,000 tonnes. This also laid down solid

  3. Spectrophotometric determination of zirconium in nickel-base alloys with Arsenazo III after separation by froth flotation

    International Nuclear Information System (INIS)

    0.02-0.1% of zirconium can be determined in nickel alloys by spectrophotometry with Arsenazo III after its separation from the sample solution by means of froth flotation using Arsenazo III and Zephiramine. Nickel, chromium and iron do not interfere. Analysis of standard alloys yielded a standard deviation of 2.2%. (orig.)

  4. Influence de la microstructure lors d'essais de fissuration à chaud d'alliage d'aluminium 6061 en soudage TIG

    OpenAIRE

    Niel, Aurélie; Deschaux-Beaume, Frédéric; Bordreuil, Cyril; Fras, Gilles

    2010-01-01

    Dans le but de réduire la consommation d'énergie, les constructeurs travaillent sur l'emploi de matériaux légers, comme les alliages d'aluminium, pour diminuer le poids des véhicules. Ces modifications imposent une amélioration constante des procédés de fabrication, en particulier en soudage. L'accroissement des vitesses de soudage sur les alliages d'aluminium provoque l'apparition de défauts tels que la fissuration à chaud. La compréhension de ce phénomène est un problème complexe faisant in...

  5. A highly sensitive nonenzymatic glucose sensor based on multi-walled carbon nanotubes decorated with nickel and copper nanoparticles

    International Nuclear Information System (INIS)

    Novel nickel and copper nanoparticles decorated multi-walled carbon nanotubes (Ni/Cu/MWCNT) have been successfully fabricated for sensitive nonenzymatic glucose detection by the sequential electro-deposition of nickel and copper nanoparticles (NPs) on an MWCNT-modified electrode. X-ray diffraction (XRD) and atomic force microscopy (AFM) analyses reveal that the Ni and Cu NPs were successfully deposited on the MWCNTs in this hybrid composite. The electrode shows good activity towards glucose oxidation with low over-potential and a current response that is 2.5–20 times greater than that obtained using Ni/GCE, Cu/GCE, Ni/Cu/GCE, Ni/MWCNT/GCE, and Cu/MWCNT/GCE. The optimised conditions based on current response are a Ni:Cu ratio of 1:1 and pH 13. Amperometry (Eapp. = +0.575 V) indicates a short response time of 1 s; two specific linear ranges of 2.5 × 10−8–8 × 10−4 M and 2 × 10−3–8 × 10−3 M, with high sensitivities of 2633 μA mM−1 cm−2 and 2437 μA mM−1 cm−2, respectively; and a low detection limit of 2.5 × 10−8 M (S/N = 3). This electrode can effectively analyse glucose concentration in human serum samples, avoiding interference, and is a promising nonenzymatic glucose sensor due to its low overpotential, high sensitivity, good selectivity, good stability, fast response, and low cost

  6. Spectrographic determination of silicon in uranium-carbon-silicon alloys; Le dosage spectrographique du silicium dans les alliages uranium-carbone-silicium

    Energy Technology Data Exchange (ETDEWEB)

    Spitz, J.P.; Chazee, J.J.; Tran Van, D.; Desforges, F. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1966-04-01

    The use of a spark excitation under a controlled argon atmosphere enables the spectrographic determination of silicon in uranium-carbon-silicon alloys. The method presented here is rapid and its accuracy is most satisfactory. (authors) [French] L'utilisation d'une excitation par etincelle sous biosphere controlee d'argon permet le dosage spectrographique du silicium dans les alliages uranium-carbone-silicium. La methode proposee est rapide et sa precision tres satisfaisante. (auteurs)

  7. Synthesis, Electrochemical, Spectroscopic, Antimicrobial, and Superoxide Dismutase Activity of Nickel (II Complexes with Bidentate Schiff Bases

    Directory of Open Access Journals (Sweden)

    R. N. Patel

    2013-01-01

    Full Text Available Five new nickel (II complexes, namely, [Ni(L12](ClO42(1; [Ni(L22](ClO42(2; [Ni(L32](ClO42(3; [Ni(L42](ClO42(4; [Ni(L52](ClO42(5, where L1 = benzoylhydrazide; L2 = N-[(1-1-(2-methylphenylethylidene]benzohydrazide; L3=N-[(1-1-(4-methylphenylethylidene]benzohydrazide; L4=N-[(1-1-(2-methoxyphenylethylidene]benzohydrazide; L5 = N-[(1-1-(4-methoxy-phenylethylidene]benzohydrazide, have been synthesized and characterized by various physicochemical and spectroscopic techniques. The synthesized complexes are stable powders, insoluble in common organic solvents such as ethanol, benzene, carbon tetrachloride, chloroform, and diethyl ether, and are nonelectrolytes. The magnetic and spectroscopic data indicate a distorted square planar geometry for all complexes. The superoxide dismutase activity of these complexes has been measured and discussed. Antibacterial and antifungal properties of these complexes were also tested.

  8. Conversion of waste cooking oil to jet biofuel with nickel-based mesoporous zeolite Y catalyst.

    Science.gov (United States)

    Li, Tao; Cheng, Jun; Huang, Rui; Zhou, Junhu; Cen, Kefa

    2015-12-01

    Three types of zeolites (Meso-Y, SAPO-34, and HY) loaded with nickel were used to convert waste cooking oil to jet biofuel. Mesoporous zeolite Y exhibited a high jet range alkane selectivity of 53% and a proper jet range aromatic hydrocarbon selectivity of 13.4% in liquid fuel products. Reaction temperature was optimized to produce quality jet biofuel. Zeolite Meso-Y exhibited a high jet range alkane yield of 40.5% and a low jet range aromatic hydrocarbon yield of 11.3% from waste cooking oil at 400°C. The reaction pathway for converting waste cooking oil to jet biofuel was proposed. Experimental results showed that waste cooking oil mainly deoxygenated to heptadecane (C17H36) and pentadecane (C15H30) through the decarbonylation pathway for the first 3h. Long chain alkanes cracked into jet range alkanes (C8-C16). Cycloalkanes and aromatic hydrocarbons were produced through cyclization and dehydrogenation pathways. PMID:26342341

  9. Study of the corrosion of nickel base alloys in molten fluorides medium

    International Nuclear Information System (INIS)

    The aim of this work is to study the corrosion mechanisms of nickel and its alloys in molten fluoride media. In a first part, the behaviour of the pure alloy metals has been studied (Ni, Mo, W, Fe and Cr) in three different salts mixtures: LiF-NaF, LiF-CaF2 and LiF-AlF3 in a temperature range of 700-1000 C. An experimental assembly allowing the implementation of electrochemical methods has been fabricated and validated. Linear scanning volt-amperometry has been used for studying the corrosion reactions of metals. It has then been possible to obtain intensity-potential curves and to determine the currents and corrosion potentials by the plotting of Tafel straight lines. These experimental results have finely been interpreted in considering the thermodynamic data accessible in literature (potential-oxo-acidity diagrams of metals in salts built from HSC Chemistry 5.1) and the influence of temperature and the nature of the bath have been estimated. (O.M.)

  10. Nickel Based Coatings Containing TiN Nanoparticles Prepared by Ultrasonic-Electrodeposition Technology

    Directory of Open Access Journals (Sweden)

    Yong Wang

    2013-07-01

    Full Text Available In order to enhance the surface properties of steel substrates, nano Ni-TiN composite coatings were prepared using ultrasonic-electrodeposition technology in this study. The effects of ultrasonic on composite coatings were studied. The X-Ray Diffraction (XRD study had been utilized to detect the crystalline and amorphous characteristics of Ni-TiN composite coatings. The surface morphology and metallurgical structure of composite coatings were observed with Scanning Electron Microscope (SEM and High Respective Transmission Electron Microscope (HRTEM. Finally the corrosion resistance was tested. The results show that the ultrasonic has greatly effects on TiN nanoparticles in composite coatings. And the introduction of ultrasonic and TiN particles cause the nickel grains to become fine. The average grain diameter of TiN particles is 30 nm. The Ni grain is measured approximately 60 nm. The test of corrosion resistance shows the nano Ni-TiN composite coating is proved with good corrosion resistance. The corrosion rate of 45 steel is about 5 times than that of Ni-TiN composite coating and the corrosion rate of Ni coating is above thrice than that of Ni-TiN composite coating.

  11. Long-period structures in gold-copper alloys; Structures a longues periodes dans les alliages or-cuivre

    Energy Technology Data Exchange (ETDEWEB)

    Jehanno, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    We first proceed to reevaluation of the gold-copper equilibrium diagram for alloys between Au{sub 20}Cu{sub 80} and Au{sub 65}Cu{sub 35}. The identification of the various phases was performed by X-rays diffraction on quenched polycrystalline samples. We next study the structure of the phase AuCuII. X-ray data collected from bulk single crystals show that this long-period structure must be described with the help of two correlated periodic functions: an 'order function' and a 'displacement function'. The 'order function' conciliates the non-integer value of the period with its rigorous definition. The 'displacement function' accounts for the dis-symmetries of the observed intensities for the antiphase homologous reflections as the appearance of satellites around the fundamental reflections. These two functions are remarkably well defined at long distance in carefully annealed samples and, in some conditions, can be obtained independently. We observe that the improvement of the degree of order increases the 'modulation of position'. In the case of non stoichiometric alloys, the excess of gold atoms (gold rich alloys) is distributed at random whereas the excess of copper (copper rich alloys) is distributed in a preferential manner close to the antiphase boundaries. (author) [French] Nous procedons, tout d'abord, a une reevaluation du diagramme d'equilibre des alliages or-cuivre compris entre Au{sub 20}Cu{sub 80} et Au{sub 65}Cu{sub 35}. L'identification des differentes phases s'est faite par diffraction de rayons X sur des echantillons polycristallins trempes. Nous etudions ensuite, aux rayons X, la structure de la phase AuCuII. Les donnees rassemblees sur monocristaux massifs indiquent que cette structure a longue periode doit etre decrite a l'aide de deux fonctions periodiques correlees: une fonction d'ordre et une fonction de deplacement des atomes. La fonction d'ordre concilie le

  12. Modélisation numérique de la diffusion-corrosion des alliages de zirconium

    OpenAIRE

    Zumpicchiat, Guillaume

    2015-01-01

    Dans les réacteurs à Eau Pressurisée (REP), les pastilles d’uranium sont isolées de l’eau du circuit primaire par des gaines en alliages de zirconium (Zy-4, M5, ZIRLO). Ces gaines jouent un rôle crucial en termes de sureté car elles sont la première barrière de confinement des produits de fission. En conditions nominales d’utilisation, la corrosion des gaines induite par l’environnement du circuit primaire (320 °C, 155 bars, présence de lithium et de bore) se traduit par l’oxydation du zircon...

  13. Examination of nickel alloys and welded joints made from nickel-based alloy. Challenge for ultrasonic testing; Pruefung von Nickellegierungen und Schweissnaehten aus Nickellegierungen. Herausforderung fuer die Ultraschallpruefung

    Energy Technology Data Exchange (ETDEWEB)

    Dugan, Sandra; Wagner, Sabine [Stuttgart Univ. (Germany). Materialpruefungsanstalt

    2015-07-01

    Nickel alloys and in particular welds of nickel alloy provide a special challenge for ultrasonic testing. Increased scattering at the relatively large grains resulting in a reduction of the signal-to-noise ratio. In welds and cast materials added that form during solidification columnar grains which are oriented in the preferred direction depending on the cooling conditions. Thereby, the elastic anisotropy of the material makes macroscopically noticeable and affects the ultrasound propagation. Thus, in particular the detection of small defects and the distinction between reflections from imperfections and interfering signals like reflections at interfaces, backscattering from the grain structure or indications are significantly more difficult. This article shows a few examples of the challenges of simple components such as pipelines to the testing with ultrasound. [German] Um dem staendig steigendem Energiebedarf gerecht zu werden und dennoch eine Reduzierung der Emissionen insbesondere von CO{sub 2} zu erreichen, sind weltweit Bestrebungen im Gange, die Effizienz fossil befeuerter Dampfkraftwerke zu steigern. Dies kann durch Erhoehung der Dampfparameter Druck und Temperatur umgesetzt werden. Dies erfordert wiederum den Einsatz neuer Werkstoffe, die den besonderen Anforderungen in Bezug auf Festigkeit und Verformungsbestaendigkeit bei Temperaturen bis 700 C sowie Korrosion und Oxidation genuegen. Hier stehen Nickellegierungen besonders im Fokus der zahlreichen Untersuchungen zum Werkstoffverhalten unter den besonderen Beanspruchungen. Neben den Werkstoffeigenschaften an sich ist auch die Fertigungsqualitaet der Halbzeuge und Schweissnaehte von entscheidender Bedeutung fuer einen langfristig sicheren und wirtschaftlichen Betrieb der Anlagen. Hier spielt die zerstoerungsfreie Pruefung (ZfP) zur Qualitaetssicherung im Rahmen der Herstellung sowie bei Wiederkehrenden Pruefungen im Betrieb eine wichtige Rolle. Fuer die Pruefung des Volumens und der inneren Oberflaechen

  14. Laser Clad Nickel Based Superalloys: Microstructure Evolution And High Temperature Oxidation Studies

    Science.gov (United States)

    Sircar, S.; Ribaudo, C.; Mazumder, J.

    1988-10-01

    Application of alloy coatings with superior oxidation resistance at elevated temperatures (1200°C) on superalloy components is of interest at present. There is a general consensus that the addition of rare earths such as hafnium (Hf) to these alloys has a pronounced effect on their performance. An in situ laser cladding technique was used to produce Ni-Al-Cr-Hf alloys on a nickel alloy substrate. Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), and Scanning Transmission Electron Microscope (STEM) attached with Energy Dispersive X-ray (EDX) analyzers were employed for microstructural evolution studies of alloys produced during the laser cladding process. The microstructure of these alloys mainly consists of dendrites of Y' of the Ni3Al type with about 11-14 wt% Hf and an interdendritic eutectic phase. Electron microscopy in the dendritic zones reveals ordered domains whose morphology depends on laser cladding process parameters. Variation in these parameters produced only subtle changes in the composition and cell spacing of the dendritic phase. The eutectic constituent consists of a Hf-rich phase and a Hf-lean phase in an alternating lamellar structure. Convergent beam diffraction and x-ray spectroscopy techniques were used to characterize the constituents. A possible phase transformation sequence has been suggested. Differential Thermal Analysis (DTA) work indicates that the Y' dissolution temperature for the claddings is at least as high as the substrate material (Rene 80). Single cycle oxidation tests of eight hours at 1200°C in slowly flowing air reveal that the claddings have a lower weight gain rate than the substrate itself. Microchemistry and microstructure of the oxidized samples are examined using SEM attached with EDX and Auger Electron Spectroscopic (AES) techniques. The improvement in the oxidation resistance is believed to be at least partially due to the mechanical pegging between alumina coated hafnia protrusions and the

  15. "Smart" nickel oxide based core–shell nanoparticles for combined chemo and photodynamic cancer therapy

    Directory of Open Access Journals (Sweden)

    Bano S

    2016-07-01

    Full Text Available Shazia Bano,1–3,* Samina Nazir,2,* Saeeda Munir,3 Mohamed Fahad AlAjmi,4 Muhammad Afzal,1 Kehkashan Mazhar3 1Department of Physics, The Islamia University of Bahawalpur, 2Nanosciences and Technology Department, National Centre for Physics, Islamabad, 3Institute of Biomedical and Genetic Engineering, Islamabad, Pakistan; 4College of Pharmacy, King Saud University, Riyadh, Kingdom of Saudi Arabia *These authors contributed equally to this work Abstract: We report “smart” nickel oxide nanoparticles (NOPs as multimodal cancer therapy agent. Water-dispersible and light-sensitive NiO core was synthesized with folic acid (FA connected bovine serum albumin (BSA shell on entrapped doxorubicin (DOX. The entrapped drug from NOP-DOX@BSA-FA was released in a sustained way (64 hours, pH=5.5, dark conditions while a robust release was found under red light exposure (in 1/2 hour under λmax=655 nm, 50 mW/cm2, at pH=5.5. The cell viability, thiobarbituric acid reactive substances and diphenylisobenzofuran assays conducted under light and dark conditions revealed a high photodynamic therapy potential of our construct. Furthermore, we found that the combined effect of DOX and NOPs from NOP-DOX@BSA-FA resulted in cell death approximately eightfold high compared to free DOX. We propose that NOP-DOX@BSA-FA is a potential photodynamic therapy agent and a collective drug delivery system for the systemic administration of cancer chemotherapeutics resulting in combination therapy. Keywords: light-triggered drug release, cancer, bovine serum albumin, multi-model therapy

  16. Structural evaluation of a nickel base super alloy metal foam via NDE and finite element

    Science.gov (United States)

    Abdul-Aziz, Ali; Abumeri, G.; Garg, Mohit; Young, P. G.

    2008-03-01

    Cellular materials are known to be useful in the application of designing light but stiff structures. This applies to various components used in various industries such as rotorcraft blades, car bodies or portable electronic devices. Structural application of the metal foam is typically confined to light weight sandwich panels, made up of thin solid face sheets and a metallic foam core. The resulting high-stiffness structure is lighter than that constructed only out of the solid metal material. The face sheets carry the applied in-plane and bending loads and the role of the foam core is separate the face sheets to carry some of the shear stresses, while remaining integral with the face sheet. Many challenges relating to the fabrication and testing of these metal foam panels continue to exist due to some mechanical properties falling short of their theoretical potential. Hence in this study, a detailed three dimensional foam structure is generated using series of 2D Computer Tomography (CT) scans, on Haynes 25 metal foam. Series of the 2D images are utilized to construct a high precision solid model including all the fine details within the metal foam as detected by the CT scanning technique. Subsequently, a finite element analysis is then performed on an as fabricated metal foam microstructures to evaluate the foam structural durability and behavior under tensile and compressive loading conditions. The analysis includes a progressive failure analysis (PFA) using GENOA code to further assess the damage initiation, propagation, and failure. The open cell metal foam material is a cobalt-nickel-chromium-tungsten alloy that combines excellent high-temperature strength with good resistance to oxidizing environments up to 1800 °F (980 °C) for prolonged exposures. The foam is formed by a powder metallurgy process with an approximate 100 pores per inch (PPI).

  17. Resistivity-Microstructure Relationships in Nickel Base Superalloys Used in Gas Turbine Engines for Power Generation and as Interconnects in Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Gerhardt, Rosario A.

    2012-02-20

    This report summarizes the results accomplished during this 3-year with funds from this grant. The most important new contribution was the development of a microstructural model, based on analysis of the small angle scattering spectra that can relate the measured electrical resistivity to the precipitate population present in a nickel base superalloy in a quantitative way. A total of 24 research articles were published or were in press at the time the final report was written.

  18. Multi-objective constrained design of nickel-base superalloys using data mining- and thermodynamics-driven genetic algorithms

    Science.gov (United States)

    Menou, Edern; Ramstein, Gérard; Bertrand, Emmanuel; Tancret, Franck

    2016-06-01

    A new computational framework for systematic and optimal alloy design is introduced. It is based on a multi-objective genetic algorithm which allows (i) the screening of vast compositional ranges and (ii) the optimisation of the performance of novel alloys. Alloys performance is evaluated on the basis of their predicted constitutional and thermomechanical properties. To this end, the CALPHAD method is used for assessing equilibrium characteristics (such as constitution, stability or processability) while Gaussian processes provide an estimate of thermomechanical properties (such as tensile strength or creep resistance), based on a multi-variable non-linear regression of existing data. These three independently well-assessed tools were unified within a single C++ routine. The method was applied to the design of affordable nickel-base superalloys for service in power plants, providing numerous candidates with superior expected microstructural stability and strength. An overview of the metallurgy of optimised alloys, as well as two detailed examples of optimal alloys, suggest that improvements over current commercial alloys are achievable at lower costs.

  19. Hole mobility modulation of solution-processed nickel oxide thin-film transistor based on high-k dielectric

    Science.gov (United States)

    Liu, Ao; Liu, Guoxia; Zhu, Huihui; Shin, Byoungchul; Fortunato, Elvira; Martins, Rodrigo; Shan, Fukai

    2016-06-01

    Solution-processed p-type oxide semiconductors have recently attracted increasing interests for the applications in low-cost optoelectronic devices and low-power consumption complementary metal-oxide-semiconductor circuits. In this work, p-type nickel oxide (NiOx) thin films were prepared using low-temperature solution process and integrated as the channel layer in thin-film transistors (TFTs). The electrical properties of NiOx TFTs, together with the characteristics of NiOx thin films, were systematically investigated as a function of annealing temperature. By introducing aqueous high-k aluminum oxide (Al2O3) gate dielectric, the electrical performance of NiOx TFT was improved significantly compared with those based on SiO2 dielectric. Particularly, the hole mobility was found to be 60 times enhancement, quantitatively from 0.07 to 4.4 cm2/V s, which is mainly beneficial from the high areal capacitance of the Al2O3 dielectric and high-quality NiOx/Al2O3 interface. This simple solution-based method for producing p-type oxide TFTs is promising for next-generation oxide-based electronic applications.

  20. Nickel-based alloy/austenitic stainless steel dissimilar weld properties prediction on asymmetric distribution of laser energy

    Science.gov (United States)

    Zhou, Siyu; Ma, Guangyi; Chai, Dongsheng; Niu, Fangyong; Dong, Jinfei; Wu, Dongjiang; Zou, Helin

    2016-07-01

    A properties prediction method of Nickel-based alloy (C-276)/austenitic stainless steel (304) dissimilar weld was proposed and validated based on the asymmetric distribution of laser energy. Via the dilution level DC-276 (the ratio of the melted C-276 alloy), the relations between the weld properties and the energy offset ratio EC-276 (the ratio of the irradiated energy on the C-276 alloy) were built, and the effects of EC-276 on the microstructure, mechanical properties and corrosion resistance of dissimilar welds were analyzed. The element distribution Cweld and EC-276 accorded with the lever rule due to the strong convention of the molten pool. Based on the lever rule, it could be predicted that the microstructure mostly consists of γ phase in each weld, the δ-ferrite phase formation was inhibited and the intermetallic phase (P, μ) formation was promoted with the increase of EC-276. The ultimate tensile strength σb of the weld joint could be predicted by the monotonically increasing cubic polynomial model stemming from the strengthening of elements Mo and W. The corrosion potential U, corrosion current density I in the active region and EC-276 also met the cubic polynomial equations, and the corrosion resistance of the dissimilar weld was enhanced with the increasing EC-276, mainly because the element Mo could help form a steady passive film which will resist the Cl- ingress.

  1. The potential link between high angle grain boundary morphology and grain boundary deformation in a nickel-based superalloy

    International Nuclear Information System (INIS)

    Focused ion beam (FIB) based serial sectioning was utilized to characterize the morphology of two high angle grain boundaries (HAGB) in a nickel based superalloy, one that experienced grain boundary sliding (GBS) and the other experienced strain accumulation, during elevated temperature constant stress loading conditions. A custom script was utilized to serial section and collect ion-induced secondary electron images from the FIB-SEM system. The MATLAB based MIPARTM software was utilized to align, segment and reconstruct 3D volumes from the sectioned images. Analysis of the 3D data indicates that the HAGB that exhibited GBS had microscale curvature that was planar in nature, and local serrations on the order of ±150 nm. In contrast, the HAGB that exhibited strain accumulation was not planar and had local serrations an order of magnitude greater than the other grain boundary. It is hypothesized that the serrations and the local grain boundary network are key factors in determining which grain boundaries experience GBS during creep deformation

  2. Etude de la transformation martensitique et des mécanismes de déformation se produisant dans l’alliage superélastique Ti-24Nb-4Zr-8Sn

    OpenAIRE

    Yang, Yang

    2015-01-01

    Les alliages de titane sont actuellement très utilisés comme implants orthopédiques de part leurs bonnes propriétés mécaniques, leur bonne résistance à la corrosion ainsi que leur excellente biocompatibilité. Cependant, l’alliage Ti-6Al-4V qui est le plus utilisé présente un module d'élasticité élevé (110GPa), ce qui peut provoquer le phénomène de « stress shielding » et finalement causer l’échec de l’implantation. De plus, l’utilisation à long terme de ce type d’alliage est remise en questio...

  3. Comportement en corrosion d'un alliage d'aluminium cuivre-lithium AW2050 : couplage environnement, microstructure, et état de contrainte du matériau

    OpenAIRE

    Guérin, Mathilde

    2014-01-01

    Les problématiques de corrosion restent un sujet d'étude majeur lorsqu'il s'agit d'améliorer les propriétés des alliages pour structures aéronautiques. Dans le cadre de ce travail, le comportement en corrosion d'un alliage AW2050 de type Al-Cu-Li-X est étudié. L'analyse du couplage entre les microstructures caractéristiques de cet alliage et l'environnement agressif constitue un point central de l'étude. Le travail réalisé a permis d'identifier les facteurs de premier ordre parmi les paramètr...

  4. Étude de l'influence des défauts de soudage sur le comportement plastique et la durée de vie en fatigue de soudures par friction-malaxage d'un alliage Al-Cu-Li

    OpenAIRE

    Le Jolu, Thomas

    2011-01-01

    Dans un but de réduction de poids des avions, un alliage Al-Cu-Li (2198-T8) assemblé par friction-malaxage est envisagé par les avionneurs pour des applications de type fuselage et intrados de l'aile. L'objectif de cette étude est de déterminer le comportement en fatigue des soudures par friction-malaxage et l'influence de certains défauts de soudage pour une durée de vie de l'ordre de 105 cycles. Pour cela le matériau de base, des soudures réalisées pleine tôle (sans défaut), des soudures co...

  5. Optimization of Weld Bead Parameters of Nickel Based Overlay Deposited by Plasma Transferred Arc Surfacing with Adequacy Test

    Directory of Open Access Journals (Sweden)

    Bhaskarananda Dasgupta

    2014-07-01

    Full Text Available Plasma Transferred Arc surfacing is a kind of Plasma Transferred Arc Welding process. Plasma Transferred Arc surfacing (PTA is increasingly used in applications where enhancement of wear, corrosion and heat resistance of materials surface is required. The shape of weld bead geometry affected by the PTA Welding process parameters is an indication of the quality of the weld. In this paper the analysis and optimization of weld bead parameters, during deposition of a Nickel based alloy Colmonoy on stainless steel plate by plasma transferred arc surfacing, are made and values of process parameters to produce optimal weld bead geometry are estimated. The experiments are conducted based on a five input process parameters and mathematical models are developed using multiple regression technique. The direct effects of input process parameters on weld bead geometry are discussed using graphs. Finally, optimization of the weld bead parameters, that is minimization of penetration and maximization of reinforcement and weld bead width, are made with a view to economize the input process parameters to achieve the desirable welding joint.

  6. PREPARATION OF MICROWAVE ABSORBING NICKEL-BASED ACTIVATED CARBON BY ELECTROLESS PLATING WITH PALLADIUM-FREE ACTIVATION

    Directory of Open Access Journals (Sweden)

    Boyang Jia

    2010-08-01

    Full Text Available Nickel-based activated carbon was prepared from coconut shell activated carbon by electroless plating with palladium-free activation. The materials were characterized by scanning electron microscopy (SEM, X-ray energy dispersion spectroscopy (EDS, vibrating sample magnetometry (VSM, and vector network analyzer, respectively. The results show that the surface of the activated carbon was covered by a Ni-P coating, which was uniform, compact, and continuous and had an obvious metallic sheen. The content of P and Ni was 2.73% and 97.27% in the coating. Compared with the untreated activated carbon, the real permeability μ′ and imaginary permeability μ″ of Ni-based activated carbon became greater, whereas the real permittivity ε′ and imaginary permittivity ε″ became smaller. Also, the plated activated carbon was magnetic, making it suitable for some special applications. In general, the method reported here might be a feasible procedure to coat activated carbon with other magnetic metals, which may find application in various areas.

  7. Influence of orientation and temperature on the fatigue crack growth of a nickel-based directionally solidified superalloy

    International Nuclear Information System (INIS)

    Fatigue crack growth (FCG) behaviors of a widely used nickel-based directionally solidified (DS) superalloy have been investigated. Standard compact tension (CT) specimens in longitudinal, transverse and diagonal directions are cast and tested at 25 °C, 600 °C and 850 °C to reveal the orientation and temperature dependence. The post-test fractography is observed through scanning electron microscope (SEM) and optical microscope (OM) to understand the underlying mechanism responsible for the fracture modes. Results indicate that cracks in all three orientations exhibit a similar propagating behavior, while the temperature shows a significant effect on the crack propagation regardless of the influence of orientation. It has been found that a higher temperature leads to a faster propagation rate in the initial stage due to the cyclic softening response of materials. However, the FCG rates of specimens at lower temperature speed up more rapidly and exceed those at higher temperature in the following stage. This is attributed to the crack closure effect induced by the oxidation at a much higher temperature. Therefore, a new model based on thermal activation is proposed to get a better ability for the FCG rate prediction of the DS superalloy under different temperatures

  8. Influence of orientation and temperature on the fatigue crack growth of a nickel-based directionally solidified superalloy

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiaohua [AML, School of Aerospace, Tsinghua University, Beijing 100084 (China); Zhang, Yangyang [Beijing Institute of Space Launch Technology, Beijing 100084 (China); Shi, Huiji, E-mail: shihj@mail.tsinghua.edu.cn [AML, School of Aerospace, Tsinghua University, Beijing 100084 (China); Gu, Jialin [Department of Material Science, Tsinghua University, Beijing 100084 (China); Li, Changpeng [Corporate Technology, Siemens Ltd. (China); Kadau, Kai [Siemens Energy Inc., Charlotte (United States); Luesebrink, Oliver [Siemens Power Generation, Mulheim an der Ruhr (Germany)

    2014-11-17

    Fatigue crack growth (FCG) behaviors of a widely used nickel-based directionally solidified (DS) superalloy have been investigated. Standard compact tension (CT) specimens in longitudinal, transverse and diagonal directions are cast and tested at 25 °C, 600 °C and 850 °C to reveal the orientation and temperature dependence. The post-test fractography is observed through scanning electron microscope (SEM) and optical microscope (OM) to understand the underlying mechanism responsible for the fracture modes. Results indicate that cracks in all three orientations exhibit a similar propagating behavior, while the temperature shows a significant effect on the crack propagation regardless of the influence of orientation. It has been found that a higher temperature leads to a faster propagation rate in the initial stage due to the cyclic softening response of materials. However, the FCG rates of specimens at lower temperature speed up more rapidly and exceed those at higher temperature in the following stage. This is attributed to the crack closure effect induced by the oxidation at a much higher temperature. Therefore, a new model based on thermal activation is proposed to get a better ability for the FCG rate prediction of the DS superalloy under different temperatures.

  9. The electrochemical corrosion behavior of austenitic alloys, cobalt or nickel based super alloys, structurally hardened martensitic, Inconel, zircaloy, super austenitic, duplex and of Ni-Cr or NTi deposits in tritiated water. 3 volumes; Comportement electrochimique a la corrosion d`alliages austenitiques, superalliages base cobalt ou nickel, martensitiques a durcissement structural, inconel, zircaloy, superaustenitiques et duplex, de depots Ni-Cr et NTi en eau tritiee. 3 volumes

    Energy Technology Data Exchange (ETDEWEB)

    Bellanger, G.

    1994-12-31

    The redox potential of {sup 3} H{sub 2}O, as well as the corrosion potentials in this medium are found, abnormally, in the trans-passive region. This is completely different from the behavior in the chemical industry or in the water in nuclear powers. With such behavior, there will be breakdowns of the protective oxide layers, and in the presence of chloride there will be immediate pitting. The steels that are most resistant to this behavior are the super austenitic and super Duplex. To avoid corrosion, another solution is to decompose the radiolytic products by imposing a slight reducing potential. Corrosion inhibitors, which are stable in tritiated water, can be used. (author). 69 refs., 421 figs., tabs.

  10. Nanoscale nickel oxide/nickel heterostructures for active hydrogen evolution electrocatalysis.

    Science.gov (United States)

    Gong, Ming; Zhou, Wu; Tsai, Mon-Che; Zhou, Jigang; Guan, Mingyun; Lin, Meng-Chang; Zhang, Bo; Hu, Yongfeng; Wang, Di-Yan; Yang, Jiang; Pennycook, Stephen J; Hwang, Bing-Joe; Dai, Hongjie

    2014-01-01

    Active, stable and cost-effective electrocatalysts are a key to water splitting for hydrogen production through electrolysis or photoelectrochemistry. Here we report nanoscale nickel oxide/nickel heterostructures formed on carbon nanotube sidewalls as highly effective electrocatalysts for hydrogen evolution reaction with activity similar to platinum. Partially reduced nickel interfaced with nickel oxide results from thermal decomposition of nickel hydroxide precursors bonded to carbon nanotube sidewalls. The metal ion-carbon nanotube interactions impede complete reduction and Ostwald ripening of nickel species into the less hydrogen evolution reaction active pure nickel phase. A water electrolyzer that achieves ~20 mA cm(-2) at a voltage of 1.5 V, and which may be operated by a single-cell alkaline battery, is fabricated using cheap, non-precious metal-based electrocatalysts. PMID:25146255

  11. Selection of etching methods of primary carbides in MAR-M247 nickel-base superalloy for computer-aided quantitative metallography

    International Nuclear Information System (INIS)

    The usefulness of various etching methods for revealing the structure of MAR-M247 nickel-base superalloy and image acquisition methods were analyzed from a desire to estimate primary carbides quantitatively. The analysis was carried out on images registered using light and scanning electron microscopes. The analyzed images contained a complete range of primary carbides occurring in the matrix and on the grain boundaries of MAR-M247 alloy

  12. Redox switching and oxygen evolution at hydrous oxyhydroxide modified nickel electrodes in aqueous alkaline solution: effect of hydrous oxide thickness and base concentration

    OpenAIRE

    Lyons, Michael

    2012-01-01

    Outstanding issues regarding the film formation, the redox switching reaction and the oxygen evolution reaction (OER) electrocatalytic behaviour of multi-cycled nickel oxy-hydroxide films in aqueous alkaline solution have been discussed. The oxide is grown using a repetitive potential multi-cycling technique, and the mechanism of the latter hydrous oxide formation process has been discussed. A duplex layer model of the oxide/solution interphase region is proposed. The acid/base behaviour of t...

  13. Hot Corrosion Behaviour of Detonation Gun Sprayed Al2O3-40TiO2 Coating on Nickel Based Superalloys at 900°C

    OpenAIRE

    N. K. Mishra; Naveen Kumar; S. B. Mishra

    2014-01-01

    Hot corrosion is the major degradation mechanism of failure of boiler and gas turbine components. These failures occur because of the usage of wide range of fuels such as, coal and oil at the elevated temperatures. Nickel based superalloys having excellent mechanical strength and creep resistance at elevated temperature are used under such environment but they lack resistance to hot corrosion at high temperature. To overcome these problems hot corrosion resistant coatings are deposited on the...

  14. Microstructural Changes of a Creep-Damaged Nickel-Based K002 Superalloy Containing Hf Element under Different HIP Temperatures

    Science.gov (United States)

    Wang, Xiaomeng; Zhou, Yu; Dong, Jian; Wang, Tianyou; Zhao, Zihua; Zhang, Zheng

    2016-02-01

    Effects of hot isostatic pressing (HIP) temperature on the microstructural evolution of a nickel-based K002 superalloy containing Hf element after long-term service were investigated using three different soaking temperatures during HIP. The degraded γ' precipitates represented coarse and irregular morphology after long-term service. These γ' precipitates still were of coarse and irregular shape, but the size and volume fraction of γ' precipitates were markedly reduced under HIP condition of 1,190°C/200 MPa/4 h, indicating that the γ' precipitates were experiencing a dissolution process. Meanwhile, the concentrically oriented N-type γ' rafting structure around the cavities was formed. With HIP temperature increase to 1,220°C and 1,250°C, the small-sized, cubic and regular γ' precipitates were re-precipitated, and the concentrically oriented γ' structure vanished. The unstable morphology induced by the nucleation and growth of γ matrix was found near the creep cavities, indicating that the solute atoms diffused inward the creep-induced cavities during HIP. However, at HIP temperature of 1,220°C and 1,250°C, a large number of blocky MC(2)-type carbides containing amounts of Hf elements were precipitated, demonstrating that HIP treatment at higher temperatures can result in the formation of a large number of blocky MC(2)-type carbides.

  15. High-temperature measurements of lattice parameters and internal stresses of a creep-deformed monocrystalline nickel-base superalloy

    Science.gov (United States)

    Biermann, Horst; Strehler, Marcus; Mughrabi, Haël

    1996-04-01

    High-temperature X-ray line profile measurements were performed to maximal temperatures of 1050 °C on samples of the nickel-base superalloy SRR 99. The samples with rod axes near the [001] direction were investigated in the initially undeformed state and after creep deformation at different temperatures and stresses. For the measurements of the (002) and (020) line profiles, a special X-ray double crystal diffractometer with negligible line broadening was used which was equipped with a high-temperature vacuum chamber. The line profiles were evaluated for the lattice parameters of the matrix phase γ and the precipitated γ' phase and for values of the lattice mismatch parallel and perpendicular to the stress axis, respectively, which were found to be different. Elastic, tetragonal distortions of the phases γ and γ' could be determined between room temperature and about 900 °C. These distortions are thermally induced due to the different thermal expansion coefficients of the two phases and deformation induced due to interfacial dislocation networks which were built up during deformation. At the high temperatures of the X-ray measurements, at least partial recovery of the deformation-induced internal stresses occurred, depending on the temperature of the X-ray measurements. The results are discussed and compared with data obtained by complementary techniques.

  16. Dendrite-Free Nanocrystalline Zinc Electrodeposition from an Ionic Liquid Containing Nickel Triflate for Rechargeable Zn-Based Batteries.

    Science.gov (United States)

    Liu, Zhen; Cui, Tong; Pulletikurthi, Giridhar; Lahiri, Abhishek; Carstens, Timo; Olschewski, Mark; Endres, Frank

    2016-02-01

    Metallic zinc is a promising anode material for rechargeable Zn-based batteries. However, the dendritic growth of zinc has prevented practical applications. Herein it is demonstrated that dendrite-free zinc deposits with a nanocrystalline structure can be obtained by using nickel triflate as an additive in a zinc triflate containing ionic liquid. The formation of a thin layer of Zn-Ni alloy (η- and γ-phases) on the surface and in the initial stages of deposition along with the formation of an interfacial layer on the electrode strongly affect the nucleation and growth of zinc. A well-defined and uniform nanocrystalline zinc deposit with particle sizes of about 25 nm was obtained in the presence of Ni(II) . Further, it is shown that the nanocrystalline Zn exhibits a high cycling stability even after 50 deposition/stripping cycles. This strategy of introducing an inorganic metal salt in ionic liquid electrolytes can be considered as an efficient way to obtain dendrite-free zinc. PMID:26822484

  17. Re-formation and re-crystallisation behaviour of γ'-free ODS nickel-based alloy PM 1000

    International Nuclear Information System (INIS)

    The aim of this work was the examination of the coarse grain recrystallisation of the γ-free ODS nickel-based alloy PM 1000 depending on the various parameters due to the processing during heat treatment. After isotropic hot compacting (HIP) of the mechanically alloyed powder, one observes a homogeneous sub-microscopic fine grain structure which can coarsen during high temperature heat treatment, due to sufficiently high driving force from the grain boundary energy via abnormal grain growth to 600 times its size. The setting of the elongated high temperature resistant recrystallisation structure is, however, not connected with this. The dependence of the sucess of re-crystallisation on the re-forming parameters (re-forming temperature and degree of re-forming) was shown by a socalled re-forming card. In order to achieve re-crystallisation to a coarse and aligned grain structure, apart from a certain absolute minimum degree of re-forming, the re-forming must occur within a defined temperature window. The factor which considerably affects the grain size of the re-crystallisation structure which is finally achievable via heat treatment, is the primary grain size of the re-forming structure. After setting a corresponding re-forming fine structure by choosing suitable re-forming parameters, the alloy PM 1000 can be successfully converted into a coarse-grained heat-resistant re-crystallisation structure via isothermal heat treatment. (MM)

  18. Arrhenius-Type Constitutive Model for High Temperature Flow Stress in a Nickel-Based Corrosion-Resistant Alloy

    Science.gov (United States)

    Wang, L.; Liu, F.; Cheng, J. J.; Zuo, Q.; Chen, C. F.

    2016-04-01

    Hot deformation behavior of Nickel-based corrosion-resistant alloy (N08028) was studied in compression tests conducted in the temperature range of 1050-1200 °C and the strain rate range of 0.001-1 s-1. The flow stress behavior and microstructural evolution were observed during the hot deformation process. The results show that the flow stress increases with deformation temperature decreasing and strain rate increasing, and that the deformation activation energy ( Q) is not a constant but increases with strain rate increasing at a given strain, which is closely related with dislocation movement. On this basis, a revised strain-dependent hyperbolic sine constitutive model was established, which considered that the "material constants" in the original model vary as functions of the strain and strain rate. The flow curves of N08028 alloy predicted by the proposed model are in good agreement with the experimental results, which indicates that the revised constitutive model can estimate precisely the flow curves of N08028 alloy.

  19. Effects of Solutioning on the Dissolution and Coarsening of γ' Precipitates in a Nickel-Based Superalloy

    Science.gov (United States)

    Wang, Xiaomeng; Zhou, Yu; Zhao, Zihua; Zhang, Zheng

    2015-04-01

    The dissolution and the coarsening of the γ' precipitates in a nickel-based superalloy GTD-111 solutionized under various solution heat treatment conditions were investigated. The γ' solvus temperature for the GTD-111 superalloy was about 1180.79 °C obtained by differential scanning calorimetry test. The dissolution and the coarsening of γ' in the dendrite core were simultaneously observed, but the γ' precipitates in the interdendritics only occurred to coarsen under the condition of 1125 °C/2 h. The γ' dissolution, including dendrite core and interdendritics, gradually played a dominant role in the competition between the dissolution and the coarsening of γ' during the solutioning with the increase of solution temperature and holding time, indicating that the elastic strain field of the alloy gradually reduced. The solution condition of 1225 °C/6 h or 1250 °C/2 h was the optimal solutioning schedule than the other schedules. For a lower solution temperature, the volume fraction of primary γ' precipitates can faster reach its equilibrium value which is larger than that for a higher solution temperature. With the increase of holding time, the γ' dissolution rate continuously decreased, and the dissolution activation energy of γ' gradually increased.

  20. Effect of B, Zr, and C on Hot Tearing of a Directionally Solidified Nickel-Based Superalloy

    Science.gov (United States)

    Grodzki, J.; Hartmann, N.; Rettig, R.; Affeldt, E.; Singer, R. F.

    2016-06-01

    The effect of the minor elements B, Zr, and C on the castability of a Nickel-based γ'-strengthened superalloy has been investigated. Tube-like specimens were prepared by directional solidification where the rigid ceramic core leads to hoop stresses and grain boundary cracking. It was found that an important improvement in castability can be achieved by adjusting the minor elemental composition. Too low C (≤0.15 pct) and too high B and Zr contents (≥0.05 pct) lead to material that is very prone to solidification cracking and should be avoided. The results cannot be rationalized on the basis of the current models for solidification cracking. Instead, pronounced hot tearing is observed to occur at high amounts of γ/ γ'-eutectic and high Zr contents. The critical film stage where dendrites at the end of solidification do not touch and are separated by thin liquid films must be avoided. How Zr promotes the film stage will be discussed in the paper.

  1. Deformation twinning and twinning-related fracture in nickel-base single-crystal superalloys during thermomechanical fatigue cycling

    International Nuclear Information System (INIS)

    Thermomechanical fatigue (TMF) tests in four 〈0 0 1〉-oriented nickel-base single-crystal superalloys were studied with the aid of microstructural investigation. Three experimental observation methods – optical microscopy, scanning electron microscope and transmission electron microscopy – were combined to obtain new insights into the microstructural and fractographic characteristics after TMF cycling with and without a compressive hold time. After the TMF cycling, the fracture surface shows different fractographic characteristics due to the introduction of the hold time. Fundamental differences in the crack propagation mechanisms have also been discovered under the influence of the compressive hold time. Without a compressive hold time, the crack propagates inwards perpendicular to the axial stress with the aid of oxidation. During the propagation, the crack reaches the twinning plate and propagates rapidly along it with the aid of the stress field at the crack tip. There appear to be obvious steps at this propagation stage. With a compressive hold time, the crack could only propagate in approximately one twinning plate. It appears in only one crystallographic fracture plane. Due to a few deformation twins being formed in this section, the crack propagation path may change to run along other twinning plates

  2. Localized recrystallization during creep in nickel-based superalloys GTD444 and René N5

    International Nuclear Information System (INIS)

    Creep damage mechanisms in two nickel-based superalloys, directionally solidified (DS) GTD444 and single crystal (SX) René N5, crept at high temperature (982 °C) and low stress (179–206 MPa), have been studied. Electron backscatter diffraction analyses showed localized dynamic recrystallization in specimens crept to high strain levels and to final fracture. Recrystallization was observed around clusters of carbides and creep cavities, and was less common in areas away from the fracture surface. The average recrystallized grain diameter was 0.71 μm, which, after 50 h at 982 °C, had grown to an average of ∼2.31 μm. Growth of the recrystallized grains occurred by the dissolution of the γ′ precipitates at the interface followed by discontinuous precipitation to relieve supersaturation. To consider the influence of localized recrystallization on macroscopic creep rates, a model for recrystallization-accelerated tertiary creep was developed. The model predicts that the axial strain rate increases by approximately one order of magnitude from the onset of recrystallization to rupture, comparing favorably to the experimentally measured accelerations in strain rate in the tertiary creep regime from 180 h to rupture. The observation of localized dynamic recrystallization provides new insight into the damage processes that occur in the tertiary creep regime

  3. Effect of Notches on Creep-Fatigue Behavior of a P/M Nickel-Based Superalloy

    Science.gov (United States)

    Telesman, Jack; Gabb, Timothy P.; Ghosn, Louis J.; Gayda, John, Jr.

    2015-01-01

    A study was performed to determine and model the effect of high temperature dwells on notched low cycle fatigue (NLCF) and notch stress rupture behavior of a fine grain LSHR powder metallurgy (PM) nickel-based superalloy. It was shown that a 90 second dwell applied at the minimum stress (min dwell) was considerably more detrimental to the NLCF lives than similar dwell applied at the maximum stress (max dwell). The short min dwell NLCF lives were shown to be caused by growth of small oxide blisters which caused preferential cracking when coupled with high concentrated notch root stresses. The cyclic max dwell notch tests failed mostly by a creep accumulation, not by fatigue, with the crack origin shifting internally to a substantial distance away from the notch root. The classical von Mises plastic flow model was unable to match the experimental results while the hydrostatic stress profile generated using the Drucker-Prager plasticity flow model was consistent with the experimental findings. The max dwell NLCF and notch stress rupture tests exhibited substantial creep notch strengthening. The triaxial Bridgman effective stress parameter was able to account for the notch strengthening by collapsing the notched and uniform gage geometry test data into a singular grouping.

  4. Effects of microstructure on high temperature dwell fatigue crack growth in a coarse grain PM nickel based superalloy

    International Nuclear Information System (INIS)

    The influence of microstructure on the dwell fatigue crack growth behaviour of an advanced nickel-based superalloy was investigated at a temperature of 700 °C. Microstructural variations were induced by heat treatment variables: different cooling rates of quenching from super-solvus solution heat treatment, 0.7 and 1.8 °C s−1, and an addition of a high temperature stabilisation heat treatment (2 h at 857 °C) between the solution treatment and the final ageing treatment. With a one hour dwell introduced at the peak load of the fatigue cycle, such different microstructural conditions can lead to a difference of up to two orders of magnitude in crack growth rates in air, when compared to those obtained under baseline fatigue loading. By performing such dwell fatigue and baseline fatigue tests in vacuum, it is confirmed that such increases in crack growth rates under dwell fatigue loading in air are mainly environmentally related. Transmission electron microscopy (TEM) was utilised to analyse both crack tip oxides and associated deformation mechanisms in the matrix. A novel mechanism taking into account competing interactions of crack tip oxidation (leading to increases in crack growth rates) and stress relaxation (leading to decreases in crack growth rates) is outlined

  5. Carbide precipitation in nickel-base model alloys and its influence on the ductility and fracture bahaviour at room temperature

    International Nuclear Information System (INIS)

    The influence of carburization with internal carbide formation on the room temperature tensile properties was determined for nickel-base model alloys of different composition. The relationship between carbide volume fraction and the loss of ductility was systematically investigated. The embrittlement was found to be severe for volume fractions greater than about 0.03 if the carbides were formed principally on grain and twin boundaries. Cracks were propagated unhindered in the continuous, grain boundary carbide films formed in alloys containing Cr or Mo and caused intergranular fracture with rupture elongations of similar magnitude to that of the carbide phase itself. Grain boundary carbide precipitates which were not continuous led to less severe ductility loss. Intracrystalline carbide precipitates as found in the W or Nb containing alloys reduced the ductility only slightly compared with grain boundary carbides in alloys of similar carbon content because the linkage of pores was prevented by the presence of ductile matrix between the pores. The fracture of individual intragranular carbides as well as of connected carbide plates was interpreted using the parallel loaded, two phase structure model. The form of the relationship between the 0.2% proof stress and the carbide volume fraction was qualitatively described using a rule of mixtures. The rule of mixtures could not however satisfactorily describe the tensile strength and the true rupture elongation without consideration of crack growth by linkage of pores between fractured carbide particles. (orig.)

  6. Mechanistic study on SCC propagation of welded nickel based alloy. Evaluation of material characteristics on corrosion and stress condition

    International Nuclear Information System (INIS)

    Stress corrosion cracking (SCC) of nickel based alloy has been reported in pressurized water reactors. To increase reliability of components, mechanistic studies for primary water SCC on Alloy 600 and their weld were carried out. In this study, characteristic of corrosion, internal oxidation, creep and hydrogen embrittlement phenomena, which might have correlate to SCC were examined to clarify their mechanism. As a result: (1) it was shown that the inner oxide film on both metals were less than 10nm. And the grain boundary precipitates that mainly Cr7C3 in Alloy 600 were insoluble to high temperature water. (2) Internal oxidation along grain boundaries were observed in several micro meters on both Alloy 600 and 132. (3) Grain boundary creep of Alloy 600 at 475degC in air and creep deformation on both Alloy 600 and 132 at 360degC were observed although in condition without water. Furthermore, (4) increasing of hydrogen concentration near a fracture region was confirmed by slow strain rate technique test. It was assumed that these four characteristic might influence the SCC propagation mutually. (author)

  7. ESCA study of oxidation and hot corrosion of nickel-base superalloys. [Electron Spectroscopy for Chemical Analysis

    Science.gov (United States)

    Smith, S. R.; Carter, W. J., III; Mateescu, G. D.; Kohl, F. J.; Fryburg, G. C.; Stearns, C. A.

    1980-01-01

    A study of the high-temperature oxidation and Na2SO4-induced hot corrosion of nickel-base superalloys has been accomplished by using ESCA to determine the surface composition of the oxidized or corroded samples. Oxidation was carried out at 900 or 1000 C in slowly flowing O2 for samples of B-1900, NASA-TRW VIA, 713C, and IN-738. Hot corrosion of B-1900 was induced by applying a coating of Na2SO4 to preoxidized samples, then heating to 900 C in slowly flowing O2. For oxidized samples, the predominant type of scale formed by each superalloy showed a marked surface enrichment of Ti. For corroded samples, the transfer of significant amounts of material from the oxide layer to the surface of the salt layer was observed before the onset of rapidly accelerating weight gain. Marked changes in surface composition coincided with the beginning of accelerating corrosion, the most striking of which were a tenfold decrease in the sulfur to sodium ratio and an increase in the Cr(VI) to Cr(III) ratio.

  8. Hydrogen diffusion and solution at high temperatures in 316L stainless steel and nickel-base heat-resistant alloys

    International Nuclear Information System (INIS)

    Hydrogen-permeation behaviors of 316L stainless steel, Inconel 600, Inconel 750, Nimonic 80A and Hastelloy X at 873 K-1173 K have been investigated under a pressure range of 0.1 MPa-0.7 MPa by using a gas-flow system. Measurements have been carried out by use of a helium-carrier-gas method. It has been proved that this method is good for examining transient-permeation behaviors as well as steady-state permeation if the instrumental time-lag is taken into account. Diffusivity and solubility of hydrogen for the alloys are derived from the transient and steady-state permeation. The γ'-precipitation strengthened alloys - Inconel 750 and Nimonic 80A - show a larger activation energy of diffusion and a smaller solution heat than the other nickel-base alloys. This result is ascribed to the trapping effect due to titanium in the former alloys, i.e. solute titanium atoms and/or γ'-precipitations. (orig.)

  9. Analyzing the effect of cutting parameters on surface roughness and tool wear when machining nickel based hastelloy - 276

    International Nuclear Information System (INIS)

    Machining parameters has an important factor on tool wear and surface finish, for that the manufacturers need to obtain optimal operating parameters with a minimum set of experiments as well as minimizing the simulations in order to reduce machining set up costs. The cutting speed is one of the most important cutting parameter to evaluate, it clearly most influences on one hand, tool life, tool stability, and cutting process quality, and on the other hand controls production flow. Due to more demanding manufacturing systems, the requirements for reliable technological information have increased. For a reliable analysis in cutting, the cutting zone (tip insert-workpiece-chip system) as the mechanics of cutting in this area are very complicated, the chip is formed in the shear plane (entrance the shear zone) and is shape in the sliding plane. The temperature contributed in the primary shear, chamfer and sticking, sliding zones are expressed as a function of unknown shear angle on the rake face and temperature modified flow stress in each zone. The experiments were carried out on a CNC lathe and surface finish and tool tip wear are measured in process. Machining experiments are conducted. Reasonable agreement is observed under turning with high depth of cut. Results of this research help to guide the design of new cutting tool materials and the studies on evaluation of machining parameters to further advance the productivity of nickel based alloy Hastelloy - 276 machining.

  10. Stacking structures and electrode performances of rare earth-Mg-Ni-based alloys for advanced nickel-metal hydride battery

    International Nuclear Information System (INIS)

    Rare earth-Mg-Ni-based alloys with stacking structures consisting of AB5 unit (CaCu5-type structure) and A2B4 unit (Laves structure) have received attention as negative electrode materials for advanced nickel-metal hydride (Ni-MH) battery. These alloy materials are very attractive because of high hydrogen storage capacity, low cobalt content and moderate plateau pressure, but have some difficulty to control the phase abundance and electrode performances. In this paper, relationship among composition, phase abundance, and electrochemical properties was investigated. Structural analysis was done using synchrotron X-ray diffraction patterns. In alloys such as La0.8Mg0.2Ni3.4-x-yCo0.3(MnAl)x (0 ≤ x ≤ 0.4), phase abundance was drastically changed with increasing amount of Mn and Al. In the range of 0.1 5Co19-type (5:19H) or rhombohedral 1:4R phases were dominant. The Rietveld analysis suggested that Mg occupies La sites in A2B4 unit, and Al has tendency to occupy Ni sites between A2B4 unit and AB5 unit or between AB5 units in these types of phases. The developed alloys showed higher discharge capacity by 20% than the conventional one at a 0.2 C discharge rate

  11. Effect of composites based nickel foam anode in microbial fuel cell using Acetobacter aceti and Gluconobacter roseus as a biocatalysts.

    Science.gov (United States)

    Karthikeyan, Rengasamy; Krishnaraj, Navanietha; Selvam, Ammaiyappan; Wong, Jonathan Woon-Chung; Lee, Patrick K H; Leung, Michael K H; Berchmans, Sheela

    2016-10-01

    This study explores the use of materials such as chitosan (chit), polyaniline (PANI) and titanium carbide (TC) as anode materials for microbial fuel cells. Nickel foam (NF) was used as the base anode substrate. Four different types of anodes (NF, NF/PANI, NF/PANI/TC, NF/PANI/TC/Chit) are thus prepared and used in batch type microbial fuel cells operated with a mixed consortium of Acetobacter aceti and Gluconobacter roseus as the biocatalysts and bad wine as a feedstock. A maximum power density of 18.8Wm(-3) (≈2.3 times higher than NF) was obtained in the case of the anode modified with a composite of PANI/TC/Chit. The MFCs running under a constant external resistance of (50Ω) yielded 14.7% coulombic efficiency with a maximum chemical oxygen demand (COD) removal of 87-93%. The overall results suggest that the catalytic materials embedded in the chitosan matrix show the best performance and have potentials for further development. PMID:26970695

  12. Effect of Specific Energy Input on Microstructure and Mechanical Properties of Nickel-Base Intermetallic Alloy Deposited by Laser Cladding

    Science.gov (United States)

    Awasthi, Reena; Kumar, Santosh; Chandra, Kamlesh; Vishwanadh, B.; Kishore, R.; Viswanadham, C. S.; Srivastava, D.; Dey, G. K.

    2012-12-01

    This article describes the microstructural features and mechanical properties of nickel-base intermetallic alloy laser-clad layers on stainless steel-316 L substrate, with specific attention on the effect of laser-specific energy input (defined as the energy required per unit of the clad mass, kJ/g) on the microstructure and properties of the clad layer, keeping the other laser-cladding parameters same. Defect-free clad layers were observed, in which various solidified zones could be distinguished: planar crystallization near the substrate/clad interface, followed by cellular and dendritic morphology towards the surface of the clad layer. The clad layers were characterized by the presence of a hard molybdenum-rich hexagonal close-packed (hcp) intermetallic Laves phase dispersed in a relatively softer face-centered cubic (fcc) gamma solid solution or a fine lamellar eutectic phase mixture of an intermetallic Laves phase and gamma solid solution. The microstructure and properties of the clad layers showed a strong correlation with the laser-specific energy input. As the specific energy input increased, the dilution of the clad layer increased and the microstructure changed from a hypereutectic structure (with a compact dispersion of characteristic primary hard intermetallic Laves phase in eutectic phase mixture) to near eutectic or hypoeutectic structure (with reduced fraction of primary hard intermetallic Laves phase) with a corresponding decrease in the clad layer hardness.

  13. Analysis of shot-peening and residual stress relaxation in the nickel-based superalloy RR1000

    International Nuclear Information System (INIS)

    This work assesses the residual stress relaxation of the nickel-based alloy RR1000 due to thermal exposure and dwell-fatigue loading. A number of different characterization methods, including X-ray residual stress analysis, electron back-scattered diffraction, microhardness testing and focused ion beam secondary electron imaging, contributed to a detailed study of the shot-peened region. Thermal exposure at 700 °C resulted in a large reduction in the residual stresses and work-hardening effects in the alloy, but the subsurface remained in a beneficial compressive state. Oxidizing environments caused recrystallization in the near surface, but did not affect the residual stress-relaxation behaviour. Dwell-fatigue loading caused the residual stresses to return to approximately zero at nearly all depths. This work forms part of an ongoing investigation to determine the effects of shot-peening in this alloy with the motivation to improve the fatigue and oxidation resistance at 700 °C

  14. C-O relations of the extremely low carbon austenitic stainless steels and nickel base high alloys in vacuum induction melting

    International Nuclear Information System (INIS)

    It is well known that in vacuum-melted austenitic stainless steel and nickel base alloy, the impurities of minute amounts affect adversely the corrosion resistance and high temperature strength. Therefore the materials of high quality, such as those in extremely low carbon range below 0.01%, are required in nuclear and chemical plants. In this study, austenitic stainless steel such as SUS 308, 309 and 316 and nickel base alloy such as Ni-20 Cr-2.6 Nb and Ni-20 Mo-3W were melted in a 200 kg vacuum induction furnace, and the behaviors of C and O during the refining were investigated, also the thermodynamical analysis was performed. For comparison, pure iron was studied at the same time. The amounts of C and O were reduced from the beginning of melting through intensive boiling period, and when quiescent period was reached, the equilibrium relation of C and O was able to be applied also to the case of austenitic stainless steel. In case of the nickel base alloy, it was presumed that the relation of C and O in quiescent period of molten alloy was near the equilibrium state. The partial pressure of CO in the stainless steel was low as compared with the pure iron, because the effect of refractory material to the oxygen potential of molten steel is different according to the steel composition. (auth.)

  15. Microstructural, mechanical and weldability assessments of the dissimilar welds between γ′- and γ″-strengthened nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Naffakh Moosavy, Homam, E-mail: homam_naffakh@iust.ac.ir [School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Tehran 16846-13114 (Iran, Islamic Republic of); Aboutalebi, Mohammad-Reza; Seyedein, Seyed Hossein [School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Tehran 16846-13114 (Iran, Islamic Republic of); Mapelli, Carlo [Dipartimento di Meccanica, Politecnico di Milano, Via La Massa 34, Milan 20156 (Italy)

    2013-08-15

    Dissimilar welding of γ′- and γ″-strengthened nickel-base superalloys has been investigated to identify the relationship between the microstructure of the welds and the resultant mechanical and weldability characteristics. γ′-Strengthened nickel-base Alloy 500 and γ″-strengthened nickel-base Alloy 718 were used for dissimilar welding. Gas tungsten arc welding operations were utilized for performing the autogenous dissimilar welding. Alloy 500 and Alloy 718 base metals showed various types of phases, carbides, intermetallics and eutectics in their microstructure. The results for Alloy 500 weld metal showed severe segregation of titanium to the interdendritic regions. The Alloy 718 weld metal compositional analysis confirmed the substantial role of Nb in the formation of low-melting eutectic-type morphologies which can reduce the weldability. The microstructure of dissimilar weld metal with dilution level of 65% wt.% displayed semi-developed dendritic structure. The less segregation and less formation of low-melting eutectic structures caused to less susceptibility of the dissimilar weld metal to the solidification cracking. This result was confirmed by analytic modeling achievements. Dissolution of γ″-Ni{sub 3}Nb precipitations took place in the Alloy 718 heat-affected zone leading to sharp decline of the microhardness in this region. Remelted and resolidified regions were observed in the partially-melted zone of Alloy 500 and Alloy 718. Nevertheless, no solidification and liquation cracking happened in the dissimilar welds. Finally, this was concluded that dissimilar welding of γ′- and γ″-strengthened nickel-base superalloys can successfully be performed. - Highlights: • Dissimilar welding of γ′- and γ″-strengthened nickel-base superalloys is studied. • Microstructural, mechanical and weldability aspects of the welds are assessed. • Microstructure of welds, bases and heat-affected zones is characterized in detail. • The type

  16. Physics-based simulation modeling and optimization of microstructural changes induced by machining and selective laser melting processes in titanium and nickel based alloys

    Science.gov (United States)

    Arisoy, Yigit Muzaffer

    Manufacturing processes may significantly affect the quality of resultant surfaces and structural integrity of the metal end products. Controlling manufacturing process induced changes to the product's surface integrity may improve the fatigue life and overall reliability of the end product. The goal of this study is to model the phenomena that result in microstructural alterations and improve the surface integrity of the manufactured parts by utilizing physics-based process simulations and other computational methods. Two different (both conventional and advanced) manufacturing processes; i.e. machining of Titanium and Nickel-based alloys and selective laser melting of Nickel-based powder alloys are studied. 3D Finite Element (FE) process simulations are developed and experimental data that validates these process simulation models are generated to compare against predictions. Computational process modeling and optimization have been performed for machining induced microstructure that includes; i) predicting recrystallization and grain size using FE simulations and the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model, ii) predicting microhardness using non-linear regression models and the Random Forests method, and iii) multi-objective machining optimization for minimizing microstructural changes. Experimental analysis and computational process modeling of selective laser melting have been also conducted including; i) microstructural analysis of grain sizes and growth directions using SEM imaging and machine learning algorithms, ii) analysis of thermal imaging for spattering, heating/cooling rates and meltpool size, iii) predicting thermal field, meltpool size, and growth directions via thermal gradients using 3D FE simulations, iv) predicting localized solidification using the Phase Field method. These computational process models and predictive models, once utilized by industry to optimize process parameters, have the ultimate potential to improve performance of

  17. Development of a first-order kinetics-based model for the adsorption of nickel onto peat

    Institute of Scientific and Technical Information of China (English)

    LIU Zhi-rong; CHEN Xiao-song; ZHOU Li-min; WEI Peng

    2009-01-01

    The use of peat for the removal of nickel from aqueous solutions has been investigated at various pH values by means of static conditions. The present research shows that the ability of Ni to hind to peat increases as the pH value increases. The solutions reach adsorption equilibrium rapidly. A reasonable kinetic model, first-order in nickel concentration, has been developed and fitted to the adsorption of nickel (Ⅱ) onto peat. The first-order model provides a good correlation to the experimental data. The characteristic parameters of the Langmuir isotherm were determined at various temperatures. The relationship between kinetics and equilibrium isotherms was established through the forward- and backward-rate-constants, k and k2, and the equilibrium constant, K.

  18. Effect of Alloy 625 Buffer Layer on Hardfacing of Modified 9Cr-1Mo Steel Using Nickel Base Hardfacing Alloy

    Science.gov (United States)

    Chakraborty, Gopa; Das, C. R.; Albert, S. K.; Bhaduri, A. K.; Murugesan, S.; Dasgupta, Arup

    2016-04-01

    Dashpot piston, made up of modified 9Cr-1Mo steel, is a part of diverse safety rod used for safe shutdown of a nuclear reactor. This component was hardfaced using nickel base AWS ER NiCr-B alloy and extensive cracking was experienced during direct deposition of this alloy on dashpot piston. Cracking reduced considerably and the component was successfully hardfaced by application of Inconel 625 as buffer layer prior to hardface deposition. Hence, a separate study was undertaken to investigate the role of buffer layer in reducing the cracking and on the microstructure of the hardfaced deposit. Results indicate that in the direct deposition of hardfacing alloy on modified 9Cr-1Mo steel, both heat-affected zone (HAZ) formed and the deposit layer are hard making the thickness of the hard layer formed equal to combined thickness of both HAZ and deposit. This hard layer is unable to absorb thermal stresses resulting in the cracking of the deposit. By providing a buffer layer of Alloy 625 followed by a post-weld heat treatment, HAZ formed in the modified 9Cr-1Mo steel is effectively tempered, and HAZ formed during the subsequent deposition of the hardfacing alloy over the Alloy 625 buffer layer is almost completely confined to Alloy 625, which does not harden. This reduces the cracking susceptibility of the deposit. Further, unlike in the case of direct deposition on modified 9Cr-1Mo steel, dilution of the deposit by Ni-base buffer layer does not alter the hardness of the deposit and desired hardness on the deposit surface could be achieved even with lower thickness of the deposit. This gives an option for reducing the recommended thickness of the deposit, which can also reduce the risk of cracking.

  19. Advanced defect characterization via electron microscopy and its application to cyclically deformed nickel-based superalloy R104

    Science.gov (United States)

    Phillips, Patrick J.

    Ni-based superalloys continue to be used in the hot sections of turbine engines due to their superior high temperature properties and retained strength. The present document will focus specifically on the polycrystalline alloy R104, and the deformation substructure observed during and following cyclic mechanical testing. Both low cycle fatigue (LCF) and sustained peak low cycle fatigue (SPLCF) tests are considered. Two chapters on electron microscopy technique development follow a brief introduction on general properties of Nickel superalloys. Almost exclusively, scanning transmission electron microscopy (STEM) was performed for defect characterization. Furthermore, through a systematic study of STEM-based diffraction contrast methods, including experimental and computational results, STEM is presented as a valid means of defect analysis. The second chapter in this set also uses STEM, but in a non-traditional setting: the microscope is configured for high resolution imaging, i.e., the sample is aligned along a low index zone axis and a large convergence angle is used. In this low angle annular dark field (LAADF) mode, an annular detector accepts low-angle scattering, which allows one to obtain atomic resolution images while retaining defect contrast. Both techniques described in these two chapters were used extensively throughout this research. The remaining chapters discuss the application of the microscopy techniques developed in the proceeding chapters to cyclically deformed specimens of R104. Both interrupted and failed samples were deformed in LCF at 427°C and 704°C, and interrupted SPLCF samples were tested at 704 and 760°C. The deformation mechanisms observed will be discussed at length in this document. In general, dislocation activity dominates under LCF conditions while stacking faults and stacking fault ribbons are most prominent under SPLCF conditions. Time and temperature components will be discussed in regards to the operative mechanisms. A point

  20. Lubricating Properties of Ceramic-Bonded Calcium Fluoride Coatings on Nickel-Base Alloys from 75 to 1900 deg F

    Science.gov (United States)

    Sliney, Harold E.

    1962-01-01

    The endurance life and the friction coefficient of ceramic-bonded calcium fluoride (CaF2) coatings on nickel-base alloys were determined at temperatures from 75 F to 1900 F. The specimen configuration consisted of a hemispherical rider (3/16-in. rad.) sliding against the flat surface of a rotating disk. Increasing the ambient temperature (up to 1500 F) or the sliding velocity generally reduced the friction coefficient and improved coating life. Base-metal selection was critical above 1500 F. For instance, cast Inconel sliding against coated Inconel X was lubricated effectively to 1500 F, but at 1600 F severe blistering of the coatings occurred. However, good lubrication and adherence were obtained for Rene 41 sliding against coated Rene 41 at temperatures up to 1900 F; no blisters developed, coating wear life was fairly good, and the rider wear rate was significantly lower than for the unlubricated metals. Friction coefficients were 0.12 at 1500 F, 0.15 at 1700 F, and 0.17 at 1800 F and 1900 F. Because of its ready availability, Inconel X appears to be the preferred substrate alloy for applications in which the temperature does not exceed 1500 F. Rene 41 would have to be used in applications involving higher temperatures. Improved coating life was derived by either preoxidizing the substrate metals prior to the coating application or by applying a very thin (less than 0.0002 in.) burnished and sintered overlay to the surface of the coating. Preoxidation did not affect the friction coefficient. The overlay generally resulted in a higher friction coefficient than that obtained without the overlay. The combination of both modifications resulted in longer coating life and in friction coefficients intermediate between those obtained with either modification alone.

  1. A Modular, Energy-Based Approach to the Development of Nickel Containing Molecular Electrocatalysts for Hydrogen Production and Oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, Wendy J.; Helm, Monte L.; DuBois, Daniel L.

    2013-08-01

    This review discusses the development of molecular electrocatalysts for H2 production and oxidation based on nickel. A modular approach is used in which the structure of the catalyst is divided into first second and outer coordination spheres. The first coordination sphere consists of the ligands bound directly to the metal center, and this coordination sphere can be used to control such factors as the presence or absence of vacant coordination sites, redox potentials, hydride acceptor abilities and other important thermodynamic parameters. The second coordination sphere is defined as functional groups such as pendant acids or bases that can interact with bound substrates such as H2 molecules and hydride ligands, but that do not form strong bonds with the metal center. These functional groups can play diverse roles such as assisting the heterolytic cleavage of H2, controlling intra- and intermolecular proton transfer reactions, and provide a physical pathway for coupling proton and electron transfer reactions. By controlling both the hydride donor/acceptor ability of the catalysts using the first coordination sphere and the proton acceptor/donor abilities of the functional groups in the second coordination sphere, catalysts can be designed that are biased toward H2 production, H2 oxidation, or that are bidirectional (catalyzing both H2 oxidation and production). The outer coordination sphere is defined as that portion of the catalytic system that are not in the first and second coordination spheres. This coordination sphere can assist in the delivery of protons and electrons to and from the catalytically active site, thereby adding another important avenue for controlling catalytic activity. Many features of these simple catalytic systems are good models for enzymes and they provide the opportunity to probe certain aspects of catalysis that may be difficult in enzymes themselves, but that can provide insights into enzyme function and reactivity.

  2. Temperature dependent lattice misfit in nickel-base superalloys - Simulation and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Neumeier, Steffen; Goeken, Mathias [Lehrstuhl fuer Allgemeine Werkstoffeigenschaften, Universitaet Erlangen-Nuernberg, Erlangen (Germany)

    2011-07-01

    Ni-base superalloys are widely used in high temperature applications like jet engines and land-based turbines, because of their excellent high temperature properties. They derive their excellent high temperature strength and creep resistance from the presence of a high volume fraction of Ni{sub 3}Al {gamma}{sup '} precipitates (L1{sub 2} structure), which are embedded coherently within the face centred cubic (A1) {gamma} matrix. The magnitude and sign of the lattice misfit between {gamma} and {gamma}{sup '} are important parameters affecting the microstructural evolution and high temperature strength of Ni-base superalloys. Therefore the knowledge of the lattice misfit at application temperature is of great importance. In this study the lattice misfit of several 1{sup st}, 2{sup nd} and 4{sup th} generation Ni-base superalloys in dependence of temperature has been measured by means of HRXRD and compared with lattice misfit simulations based on thermodynamic calculations. The influence of the thermal expansion coefficients and the change in the chemical composition of both {gamma} and {gamma}{sup '} due to the {gamma}{sup '} dissolution with increasing temperature has been taking into account. The experimentally measured {gamma} and {gamma}{sup '} lattice parameters could be reproduced by the simulation and the {gamma}/{gamma}{sup '} lattice misfit could be reasonably predicted.

  3. Synthesis and Application of Zeolite-encapsulated Nickel Schiff-base Complex

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Transition-metal complex-catalyzed oxidation of organic substrates with molecular oxygen is gaining importance as a viable alternative to the environmentally hazardous metal-oxide-based reagents. The complexes have received much attention recently due to the potential application of these complexes as oxidation catalysts for the oxidation of alkene, enolizable, aldehydes and other organic substrates. Recent studies of our group showed that metal complexes catalyzed the oxidation of organic substrates selectively in the presence of molecular oxygen 1,5. Here, it is reported that zeolite-encapsulated Ni (I) Schiff-base complex exhibit a catalytic activity and selectivity for the oxidation of styrene.

  4. Étude de défaut trouvé dans des tubes centrifugés de stellite 6B

    OpenAIRE

    Villar Echeverría, Alejandro

    2014-01-01

    Les superalliages sont des alliages employés pour travailler à hautes températures tout en maintenant stabilité dimensionnelle et résistance mécanique et à la corrosion. Ils sont utilisés dans les domaines de l'aéronautique, l’industrie navale et médicale entre autres. Parmi les différents types de superalliages existants (base nickel, base cobalt et base nickel-fer), on travaillera dans cette étude avec des superalliages base cobalt. Ces alliages sont connus communément sous le nom de Stelli...

  5. Iminopyridine-Based Cobalt(II and Nickel(II Complexes: Synthesis, Characterization, and Their Catalytic Behaviors for 1,3-Butadiene Polymerization

    Directory of Open Access Journals (Sweden)

    Quanquan Dai

    2016-01-01

    Full Text Available A series of iminopyridine ligated Co(II (1a–7a and Ni(II (1b–7b complexes were synthesized. The structures of complexes 3a, 4a, 5a, 7a, 5b, and 6b were determined by X-ray crystallographic analyses. Complex 3a formed a chloro-bridged dimer, whereas 4a, 5a, and 7a, having a substituent (4a, 5a: CH3; 7a: Br at the 6-position of pyridine, producing the solid structures with a single ligand coordinated to the central metal. The nickel atom in complex 5b features distorted trigonal-bipyramidal geometry with one THF molecule ligating to the metal center. All the complexes activated by ethylaluminum sesquichloride (EASC were evaluated in 1,3-butadiene polymerization. The catalytic activity and selectivity were significantly influenced by the ligand structure and central metal. Comparing with the nickel complexes, the cobalt complexes exhibited higher catalytic activity and cis-1,4-selectivity. For both the cobalt and nickel complexes, the aldimine-based complexes showed higher catalyst activity than their ketimine counterparts.

  6. Nickel-based xerogel catalysts: Synthesis via fast sol-gel method and application in catalytic hydrogenation of p-nitrophenol to p-aminophenol

    Science.gov (United States)

    Feng, Jin; Wang, Qiang; Fan, Dongliang; Ma, Lirong; Jiang, Deli; Xie, Jimin; Zhu, Jianjun

    2016-09-01

    In order to investigate the roles of three-dimensional network structure and calcium on Ni catalysts, the Ni, Ni-Al2O3, Ni-Ca-Al2O3 xerogel catalysts were successfully synthesized via the fast sol-gel process and chemical reduction method. The crystal structure of three different catalysts was observed with X-ray powder diffraction (XRD). Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and nitrogen adsorption-desorption were employed to investigate the role of network structure of xerogel catalysts and the size distribution of Ni nanoparticles. The catalyst composition was determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) measurement and energy-dispersive X-ray spectroscopy (EDS). Temperature-programmed reduction (TPR) experiments were carried out to investigate the reducibility of nickel species and the interaction between nickel species and alumina. The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over the prepared nickel-based xerogel catalysts. The conversion of p-nitrophenol was monitored by UV spectrophotometry and high performance liquid chromatography (HPLC). The results show that the catalysts are highly selective for the conversion of p-nitrophenol to p-aminophenol and the order of catalytic activities of the catalysts is Ni < Ni-Al2O3 < Ni-Ca-Al2O3. The catalysts were recycled and were used to evaluate the reutilization.

  7. Equilibrium partition ratios, densities, and transport phenomena in nickel-base superalloys

    Science.gov (United States)

    Sung, Pil Kyung

    To simulate transport phenomena, macrosegregation and segregation defects known as "freckles" during directional solidification of Ni-base superalloys, numerical modeling can be used; hence it is essential to have reasonably accurate values of the thermodynamic and transport properties for the alloys. In this research, therefore, the equilibrium partition ratios of the solutes in the Ni-Al-Ta-Cr quaternary system, as a model alloy, were measured, and the solid- and liquid-densities in Ni-base superalloys. were estimated. Also, the importance of these properties on the sensitivity of the results of numerical simulations was studied. The partition ratios apply to equilibria between melts and gamma-phase in the range of 1615 K to 1694 K, and it was found that the equilibrium partition ratio of Ta varies from approximately 0.6 at dilute Ta to 0.85 at 17 wt.% Ta. For the same range of Ta-contents, the partition ratios of Al and Cr vary much less and range from about 0.92 to 0.96. In addition to the partition ratios, the liquidus temperatures of the liquid in equilibrium with gamma in the Ni-Al-Ta-Cr system were estimated with a multidimensional regression analysis. To calculate the densities of solid Ni-base superalloys as functions of temperature and composition, lattice parameters at 20°C and coefficients of thermal expansion (CTEs) were estimated by combining available data. The CTEs calculated from the regressions result in densities that are within 0.5% error or less for seventeen alloys. To estimate the densities of liquid Ni-base superalloys, the densities and temperature coefficients of density of the liquid transition-metals, which are used as alloy elements in Ni-base superalloys, were applied to a simple correlation. By using this approach, the estimates of the liquid densities of five Ni-base superalloys agree with the measured values to +/-2.5%. Finally, the importance of using reasonably accurate estimates of the transport properties was illustrated by

  8. High Energy Storage Mg-based amorphous alloys for nickel-metal hydride battery

    International Nuclear Information System (INIS)

    Full text: Mg-based hydrogen storage alloys possess very high hydrogen absorption capacity (For example, Mg2NiH4 contains 3.6 wt.% of hydrogen). Magnesium is also abundant in nature, light in weight and low in cost. As a result, magnesium alloys have become the subject of increasing research world-wide. For a long period, it was thought that Mg-based alloy-hydrogen systems needed to be operated at high temperature (over 250 deg C) and under high hydrogen pressure. However, in recent years, some research work was successfully done to improve the hydrogen absorption kinetics of Mg2Ni by mechanical grinding and alloying. Some nano and amorphous structured Mg2Ni alloys could absorb hydrogen even at room temperature. Our research results show that it is possible to use Mg2Ni-type alloys as promising materials for increasing the negative electrode capacity of Ni-MH batteries because the theoretical discharge capacity of Mg2Ni alloy is approximately 1000 mAh/g, much higher than that of the main commercial LaNi5 alloy (which has a capacity of only about 370 mAh/g). Mg-based alloy electrodes were manufactured by a powder metallurgical technique or a induction melting method followed by ball milling with Ni and/or other metal powders. The discharge capacities of the Mg-based alloy electrodes were significantly improved by ball milling. An amorphous structure is a key factor in order to achieve high discharge capacities. The figure below shows the ball milled amorphous Mg-based alloy electrodes have very high discharge capacities by comparison with crystalline Mg2Ni alloys or commercial AB5 alloy

  9. Characterization of nickel-based microlattice materials with structural hierarchy from the nanometer to the millimeter scale

    International Nuclear Information System (INIS)

    Novel nickel-based microlattice materials with structural hierarchy spanning three different length scales (nm, μm, mm) are characterized microstructurally and mechanically. These materials are produced by plating a sacrificial template obtained by self-propagating photopolymer waveguide prototyping. Ni–P films with a thickness of 120 nm to 3 μm are deposited by electroless plating, whereas thicker films (5–26 μm) are obtained by subsequent electrodeposition of a pure Ni layer. This results in cellular materials spanning three orders of magnitude in relative density, from 0.01% to 8.5%. The thin electroless Ni–P films have ultra-fine grain size (7 nm) and a yield strength of ∼2.5 GPa, whereas the thicker electrodeposited Ni films exhibit a much broader distribution with average grain size of 116 nm and strong (1 0 0) texture in the plating direction, resulting in a yield strength of ∼1 GPa. Uniaxial compression experiments reveal two distinct mechanical responses. At ultra-low densities (<0.1%), these lattices exhibit nearly full recovery after strains up to more than 50%, and damping coefficients an order of magnitude larger than for conventional Ni foams. At higher densities (0.1–10%), the compression behavior is fully plastic, similar to traditional cellular metals. A simple mechanical analysis reveals that the transition occurs when the thickness-to-diameter ratio of the truss elements is of the order of the yield strain of the material, in agreement with experimental observations. Optical and electron imaging of deformed lattices show that the deformation largely localizes around the nodes. In the ultra-light regime, the microlattice materials are stiffer and stronger than any existing alternative.

  10. Constitutive modeling and failure mechanisms of anisotropic tensile and creep behaviors of nickel-base directionally solidified superalloy

    International Nuclear Information System (INIS)

    Highlights: ► Propose a modified Chaboche model to describe mechanical behavior of DS superalloy. ► Use an explicit integration method to achieve FEM calculation of the constitutive model. ► Develop a new grouping optimization method to identify the material parameters. ► Study the fracture mechanisms of tensile and creep specimens of DS superalloy. -- Abstract: A transversely isotropic continuum elasto-viscoplasticity model is formulated to capture the tensile and creep behaviors of a directionally solidified (DS) nickel-base superalloy. A fourth-order tensor is introduced to model material anisotropy. The Kachanov damage evolution equation is coupled with stress tensor to improve capability of modeling creep deformation. This model is implemented as an ABAQUS user material (UMAT) subroutine using a self-adaptive explicit integration scheme. A grouping optimization strategy is employed to identify the material parameters by fitting experimental curves of isothermal tension and creep loading at high temperature. Failure mechanisms are investigated by observing the fracture morphology by means of Scanning Electron Microscope (SEM) with the Energy Dispersive X-ray Spectrometer (EDXS). The results obtained showed that Chaboche constitutive model coupled with anisotropy and creep damage was able to characterize the rate-dependent anisotropic tensile and creep behaviors of DS superalloy and the simulation results agreed well with the experimental data. The tensile fracture surface of DS superalloy mainly contained a mixture of large cleavage planes and small amount of dimples. Meanwhile, the creep fracture mechanism of DS superalloy at 760 and 850 °C was transgranular fracture induced by the dimple accumulation. The morphology of the dimples and non-metallic inclusions at 760 °C was different from that at 850 °C.

  11. Relationships between Microstructural Parameters and Time-Dependent Mechanical Properties of a New Nickel-Based Superalloy AD730™

    Directory of Open Access Journals (Sweden)

    Louis Thébaud

    2015-11-01

    Full Text Available High temperature creep and dwell-fatigue properties of the new nickel-based superalloy AD730™ have been investigated. Three microstructures have been studied in creep (850 °C and 700 °C and dwell-fatigue (700 °C stress control with trapezoidal signals, and dwell times ranging from 1 s to 3600 s: a coarse grains microstructure, a fine grains one, and single crystalline samples. The aim of this study is to assess the influence of the grain size on creep and creep-fatigue properties. It is demonstrated that fine and coarse grains microstructures perform similarly in creep at 700 °C, showing that the creep properties at this temperature are controlled by the intragranular precipitation. Moreover, both the coarse grains and the fine grains microstructures show changes in creep deformation mechanisms depending on the applied stress in creep at 700 °C. At higher creep temperatures, the coarse grains microstructure performs better and almost no effect is observed by suppressing grain boundaries. During dwell-fatigue tests at 700 °C, a clear effect of the mechanical cycling has been evidenced on the time to failure on both the coarse and the fine grains microstructures. At high applied stresses, a beneficial effect of the cyclic unloading to the lifetime has been observed whereas at lower applied stresses, mechanical cycling is detrimental compared to the pure creep lifetime due to the development of a fatigue damage. Complex creep-fatigue interactions are hence clearly evidenced and they depend on the pure creep behavior reference.

  12. Ethylene glycol as a new sustainable fuel for solid oxide fuel cells with conventional nickel-based anodes

    International Nuclear Information System (INIS)

    Highlights: • Ethylene glycol could be used as a sustainable fuel for solid oxide fuel cells. • Ethylene glycol was beneficial in suppressing coke formation on Ni anode. • A high power output of 1200 mW cm−2 was obtained with ethylene glycol at 750 °C. • An excellent operational stability was obtained with ethylene glycol fuel. - Abstract: In this study, renewable ethylene glycol (EG) was exploited as a potential fuel for solid oxide fuel cells (SOFCs) with conventional nickel yttria-stabilized zirconia (Ni–YSZ) cermet anodes for sustainable electric power generation. Carbon deposition behaviors over Ni–YSZ anodes under different carbon-containing atmospheres such as EG, glycerol, ethanol and methane were characterized through thermodynamic prediction, oxygen-temperature programmed oxidation and SEM–EDX analysis. EG was observed to be better than acetic acid and glycerol and much better than methane and ethanol in terms of carbon deposition. A calculation of the open-circuit voltages of EG-fueled SOFCs suggested that EG is a suitable fuel for SOFCs. A maximum power output of 1200 mW cm−2 at 750 °C was obtained from a cell operating on EG-steam fuel, which is only a little lower than that from a cell based on hydrogen fuel. The cell was further operated stably on an EG-steam gas mixture for 200 h with no apparent performance degradation, carbon deposition over the anode, Ni agglomeration, or change in the morphology of the anodes. The current study confirmed the practical applicability of EG as a direct fuel for SOFCs, which may have a great effect on future energy systems

  13. Stress dependence of the Hall coefficient of a nickel-base superalloy

    Science.gov (United States)

    Kosaka, Daigo; Frishman, Anatoli; Nakagawa, Norio

    2016-02-01

    This paper reports on the Hall Effect and their stress dependence, observed experimentally on the superalloy Inconel® 718. The work is motivated by the desire to develop a nondestructive method of characterizing the near-surface protective residual stress in metals. Our approach is based on Hall Effect measurements, because it is anticipated that these measurements are less contaminated by cold work and other effects than conductivity-based measurements such as eddy current. The challenge is that, in metals, the Hall coefficient is very small. To achieve the required sensitivity, the Hall coefficient was measured with an AC injected current and an AC magnetic field. The measurements were performed on a thin film sample. The Hall coefficient was found to be positive, and varies proportionally to the applied tension. The proportionality coefficient is significantly larger than estimated from the volumetric effect in a free carrier model.

  14. Hydrothermal processing of nickel containing biomining or bioremediation biomass

    Energy Technology Data Exchange (ETDEWEB)

    Clercq, M. le; Adschiri, Tadafumi; Arai, Kunio [Tohoku Univ., Sendai (Japan). Dept. of Chemical Engineering

    2001-07-01

    The feasibility of recovering nickel and producing biofuels from nickel containing biomining or bioremediation biomass by a hydrothermal process has been investigated. Experiments were concerned with the reactions of nickel and biomass containing solutions (model solutions and an extract of Berkheya coddii) in hot compressed water between 200 and 375{sup o}C at 25 MPa. We found that in this temperature range nickel is soluble in aqueous solutions containing histidine, an amino acid present in high concentrations in nickel accumulators. The thermal decomposition products of the biomass reduce the histidine complexed nickel ions to metallic nickel. This reduction proceeds on metallic surfaces, and the nickel is deposited on the surface of the metal as a nickel or nickel/char layer. No added reducing agent such as hydrogen is required. An extract of the nickel bioaccumulator B. coddii and total biomass of B. coddii behaved similarly to our model solutions. Based on our results we propose a three-step hydrothermal process for the recovery of nickel and biofuel form nickel containing biomass. (Author)

  15. Structural state of irradiated solid solutions on iron-chromium-nickel and iron-chromium bases

    International Nuclear Information System (INIS)

    Base on the analysis of experimental and literature data on structural state of irradiated solid solutions (alloys Fe - 7.5 Cr - 35 Ni, KhN60B, Fe - 45 Ni, Fe - 3.5 Mn and steels Kh18n10t, Kh16n15m3b) a conclusion is made that homogeneous solid solutions under irradiation transform, as a rule, into a heterogeneous state. Several models which explain this radiation-induced transition are under consideration

  16. Green Compact Temperature Evolution during Current-Activated Tip-Based Sintering (CATS) of Nickel

    OpenAIRE

    Khaled Morsi; Samuel K. Kassegne; Ahmed El Desouky; Kee S. Moon

    2013-01-01

    Current-activated tip-based sintering (CATS) is a novel process where spark plasma sintering conditions are applied through an electrically conducting tip on a locally controlled area on a green powder compact/bed. The localization of electric current in CATS allows for unique temporal and spatial current and temperature distributions within the tip and powder compact. In this paper, special experimental setups were used to monitor the temperature profiles in the tip and at multiple locations...

  17. Nickel based alloys compatibility with fuel salts for molten salt reactor with thorium and uranium support

    International Nuclear Information System (INIS)

    R and D on molten salt reactors (MSR) in Europe are concentrated now on fast/intermediate spectrum concepts which were recognised as long-term alternative to solid fuelled fast reactors due to their attractive features: strong negative feedback coefficients, easy in-service inspection, and simplified fuel cycle. For high-temperature MSR corrosion of the metallic container alloy in primary circuit is the primary concern. Key problem receiving current attention include surface fissures in Ni-based alloys probably arising from fission product tellurium attack. This paper summarises results of corrosion tests conducted recently to study effect of oxidation state in selected fuel salts on tellurium attack and to develop means of controlling tellurium cracking in the special Ni - based alloys recently developed for large power units: molten salt actinide recycler and transmuter (MOSART) and molten salt fast reactor (MSFR). Tellurium corrosion of Ni-based alloys was tested in the temperature range from 730 deg. C up to 800 deg. C in stressed and unloaded conditions with fuel LiF-BeF2-UF4 and LiF-BeF2-ThF4-UF4 salt mixtures at different [U(IV)]/[U(III)] ratios from 0.7 up to 500. Following Russian and French Ni-based alloys (in mass%): HN80M-VI (Mo-12, Cr-7.6, Nb-1.5), HN80MTY (Mo-13, Cr-6.8, Al-1.1, Ti-0.9), HN80MTW (Mo-9.4, Cr-7.0, Ti-1.7, W-5.5) and EM-721 (W-25.2, Cr-5.7, Ti-0.17) were used for the study in the corrosion facility. The HN80MTY alloy has shown the best resistance against Te cracking and after test mechanical properties. (authors)

  18. Corrosion of ferritic-martensitic steels and nickel-based alloys in supercritical water

    Science.gov (United States)

    Ren, Xiaowei

    The corrosion behavior of ferritic/martensitic (F/M) steels and Ni-based alloys in supercritical water (SCW) has been studied due to their potential applications in future nuclear reactor systems, fossil fuel power plants and waste treatment processes. 9˜12% chromium ferritic/martensitic steels exhibit good radiation resistance and stress corrosion cracking resistance. Ni-based alloys with an austenitic face-centered cubic (FCC) structure are designed to retain good mechanical strength and corrosion/oxidation resistance at elevated temperatures. Corrosion tests were carried out at three temperatures, 360°C, 500°C and 600°C, with two dissolved oxygen contents, 25 ppb and 2 ppm for up to 3000 hours. Alloys modified by grain refinement and reactive element addition were also investigated to determine their ability to improve the corrosion resistance in SCW. A duplex oxide structure was observed in the F/M steels after exposure to 25 ppb oxygen SCW, including an outer oxide layer with columnar magnetite grains and an inner oxide layer constituted of a mixture of spinel and ferrite phases in an equiaxed grain structure. An additional outermost hematite layer formed in the SCW-exposed samples when the oxygen content was increased to 2 ppm. Weight gain in the F/M steels increased with exposure temperatures and times, and followed parabolic growth kinetics in most of the samples. In Ni-based alloys after exposure to SCW, general corrosion and pitting corrosion were observed, and intergranular corrosion was found when exposed at 600°C due to formation of a local healing layer. The general oxide structure on the Ni-based alloys was characterized as NiO/Spinel/(CrxFe 1-x)2O3/(Fe,Ni). No change in oxidation mechanism was observed in crossing the critical point despite the large change in water properties. Corrosion resistance of the F/M steels was significantly improved by plasma-based yttrium surface treatment because of restrained outward diffusion of iron by the

  19. Nickel cadmium batteries. 1977-June, 1980 (citations from the NTIS Data Base). Report for 1977-Jun 80

    Energy Technology Data Exchange (ETDEWEB)

    Cavagnaro, D.M.

    1980-07-01

    The design, fabrication, components, testing, and assembly of nickel cadmium batteries are covered in the bibliography. The majority of these citations deal with the development of power supplies for aircraft and spacecraft. (This updated bibliography contains 135 abstracts, 19 of which are new entries to the previous edition.)

  20. Electrodeposited nickel(3) aluminide base intermetallic coatings and their resistance to high temperature degradation in hydrocarbon cracking environments

    Science.gov (United States)

    Liu, Haifeng

    This research was aimed at developing novel Ni-A1 base intermetallic coatings to protect commercial Fe-Ni-Cr tube alloys from severe corrosive degradation at high temperatures. These alloys are widely used in petrochemical, chemical, and energy conversion industries. The coating process and coating evaluation were the two main aspects of this investigation. A two-step coating processing has been successfully developed to in situ apply pure and CeO2-modified Ni3Al intermetallic coatings onto Fe-Ni-Cr substrates. The process consists of the electrodeposition of Ni-Al and Ni-Al-CeO2 composite coatings from a Watt's nickel bath containing Al and CeO2 particles via a cost-effective electroplating technique and an annealing treatment of the as-plated coatings. It was found that the deposition of Al particles obeyed a Guglielmi model, and that REO particles interfered significantly with the deposition of Al particles. The long-term resistance of pure and CeO2-modified Ni 3A1 coatings to cyclic oxidation, carburization, coke formation, and metal dusting was evaluated in flowing dry air, 2 % CH4-H 2, and CO-H2-H2O respectively. Due to the high porosity, pure and CeO2-dispersed Ni3Al coatings exhibited poor resistance to cyclic oxidation at 850°C. CeO2 improved the spallation resistance of the Ni3Al base coatings during cyclic oxidation at 1050°C. CeO2-dispersed Ni3Al coatings showed better carburization resistance, particularly at 1050°C. Ni 3A1-based coatings. Those CeO2-dispersed were susceptible to coke formation and metal dusting at 650°C. Pre-oxidation improved the resistance of Ni3Al-based coatings to coke formation and metal dusting at 650°C, but the effectiveness depended on the integrity of the induced alumina scale. Special attention was paid to several aspects of coating degradation. These aspects included microstructure changes, degradation mechanisms, coating/substrate interdiffusion, effect of corrosive atmosphere, and effect of CeO2 on coating

  1. Homogenizing a Nickel-Based Superalloy: Thermodynamic and Kinetic Simulation and Experimental Results

    Energy Technology Data Exchange (ETDEWEB)

    Paul D. Jablonski; Christopher J. Cowen

    2009-03-01

    If the chemical inhomogeneity profile is known a priori, kinetic modeling software such as diffusion-controlled transformations (DICTRA) can be used to model the homogenization kinetics of an alloy. In this study, the Scheil module within the Thermo-Calc software was used to predict the as-cast segregation present within the Ni-based superalloy Nimonic 105. The segregation profiles were read into DICTRA to refine the homogenization heat treatment of this alloy. The thermodynamic and kinetic modeling of the computationally predicted heat treatment and microstructure, and subsequent experimental verification on a real casting of Nimonic 105, are presented.

  2. Low cycle fatigue life of two nickel-base casting alloys in a hydrogen environment

    International Nuclear Information System (INIS)

    Results of low cycle fatigue tests on alloy Mar-M-246 and Inconel 713 are presented. Based on the limited data, it was concluded that the Mar-M-246 material had a cyclic life in hydrogen that averaged three times higher than the alloy 713LC material for similar strain ranges. The hydrogen environment reduced life for both materials. The life reduction was more than an order of magnitude for the 713LC material. Porosity content of the cast specimens was as expected and was an important factor governing low cycle fatigue life

  3. Evolution of Grain Selection in Spiral Selector during Directional Solidification of Nickel-base Superalloys

    Institute of Scientific and Technical Information of China (English)

    Xiangbin Meng; Jinguo Li; Tao Jin; Xiaofeng Sun; Changbo Sun; Zhuangqi Hu

    2011-01-01

    The process of grain selection in the spiral selector was investigated by both a ProCAST simulation based on a cellular automaton finite element (CAFE) model and experimental confirmation. The results show that the height of starter block, the spiral diameter and initial angle play an important role in grain selection. The dimension of selector should be maintained in a stable range to optimize the grain orientation and select a single crystal efficiently. A selector which can efficiently select a single crystal had been successfully designed. Grain orientation fluctuation in the spiral part was also studied by means of the variation of thermal condition.

  4. Transient liquid phase bonding of titanium-, iron- and nickel-based alloys

    Science.gov (United States)

    Rahman, A. H. M. Esfakur

    The operating temperature of land-based gas turbines and jet engines are ever-increasing to increase the efficiency, decrease the emissions and minimize the cost. Within the engines, complex-shaped parts experience extreme temperature, fatigue and corrosion conditions. Ti-based, Ni-based and Fe-based alloys are commonly used in gas turbines and jet engines depending on the temperatures of different sections. Although those alloys have superior mechanical, high temperature and corrosion properties, severe operating conditions cause fast degradation and failure of the components. Repair of these components could reduce lifecycle costs. Unfortunately, conventional fusion welding is not very attractive, because Ti reacts very easily with oxygen and nitrogen at high temperatures, Ni-based superalloys show heat affected zone (HAZ) cracking, and stainless steels show intergranular corrosion and knife-line attack. On the other hand, transient liquid phase (TLP) bonding method has been considered as preferred joining method for those types of alloys. During the initial phase of the current work commercially pure Ti, Fe and Ni were diffusion bonded using commercially available interlayer materials. Commercially pure Ti (Ti-grade 2) has been diffusion bonded using silver and copper interlayers and without any interlayer. With a silver (Ag) interlayer, different intermetallics (AgTi, AgTi2) appeared in the joint centerline microstructure. While with a Cu interlayer eutectic mixtures and Ti-Cu solid solutions appeared in the joint centerline. The maximum tensile strengths achieved were 160 MPa, 502 MPa, and 382 MPa when Ag, Cu and no interlayers were used, respectively. Commercially pure Fe (cp-Fe) was diffusion bonded using Cu (25 m) and Au-12Ge eutectic interlayer (100 microm). Cu diffused predominantly along austenite grain boundaries in all bonding conditions. Residual interlayers appeared at lower bonding temperature and time, however, voids were observed in the joint

  5. Environmentally Assisted Cracking of Nickel Alloys - A Review

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R

    2004-07-12

    Nickel can dissolve a large amount of alloying elements while still maintaining its austenitic structure. That is, nickel based alloys can be tailored for specific applications. The family of nickel alloys is large, from high temperature alloys (HTA) to corrosion resistant alloys (CRA). In general, CRA are less susceptible to environmentally assisted cracking (EAC) than stainless steels. The environments where nickel alloys suffer EAC are limited and generally avoidable by design. These environments include wet hydrofluoric acid and hot concentrated alkalis. Not all nickel alloys are equally susceptible to cracking in these environments. For example, commercially pure nickel is less susceptible to EAC in hot concentrated alkalis than nickel alloyed with chromium (Cr) and molybdenum (Mo). The susceptibility of nickel alloys to EAC is discussed by family of alloys.

  6. Comparison of brazed joints made with BNi-1 and BNi-7 nickel-base brazing alloys

    Directory of Open Access Journals (Sweden)

    Zorc, Borut

    2000-04-01

    Full Text Available Kinetics of the processes are different with different types of brazing alloys. Precipitation processes in the parent metal close to the brazing gap are of great importance. They control the mechanical properties of the joint area when the brittle eutectic has disappeared from the gap. A comparative study of brazed joints on austenitic stainless alloys made with BNi-7 (Ni-P type and BNi-1 (Ni-Si-B type brazing alloys was made. Brazing alloys containing phosphorus behave in a different manner to those containing boron.

    Las aleaciones de níquel se producen mediante tres sistemas de aleación: Ni-P, Ni-Si y Ni-B. Durante las reacciones metalúrgicas con el metal de base, la eutéctica frágil en la separación soldada puede transformarse en la solución dúctil-sólida con todas aleaciones. La cinética del proceso varía según el tipo de aleación. Los procesos de precipitación en el metal de base cerca de la separación soldada son de mucha importancia, ya que controlan las propiedades mecánicas de la área de unión después de desaparecer la eutéctica frágil de la separación. Se ha hecho un análisis comparativo de uniones soldadas en aleaciones austeníticas inoxidables realizadas con aleaciones BNi-7 (tipo Ni-P y BNi-1 (tipo Ni-Si-B. Las aleaciones que contienen fósforo se comportan de una manera diferente, tanto con el cambio de la eutéctica a la solución sólida, como con los procesos de precipitación en el metal de base cerca de la unión soldada.

  7. Crack initiation modeling of a directionally-solidified nickel-base superalloy

    Science.gov (United States)

    Gordon, Ali Page

    Combustion gas turbine components designed for application in electric power generation equipment are subject to periodic replacement as a result of cracking, damage, and mechanical property degeneration that render them unsafe for continued operation. In view of the significant costs associated with inspecting, servicing, and replacing damaged components, there has been much interest in developing models that not only predict service life, but also estimate the evolved microstructural state of the material. This thesis explains manifestations of microstructural damage mechanisms that facilitate fatigue crack nucleation in a newly-developed directionally-solidified (DS) Ni-base superalloy components exposed to elevated temperatures and high stresses. In this study, models were developed and validated for damage and life prediction using DS GTD-111 as the subject material. This material, proprietary to General Electric Energy, has a chemical composition and grain structure designed to withstand creep damage occurring in the first and second stage blades of gas-powered turbines. The service conditions in these components, which generally exceed 600°C, facilitate the onset of one or more damage mechanisms related to fatigue, creep, or environment. The study was divided into an empirical phase, which consisted of experimentally simulating service conditions in fatigue specimens, and a modeling phase, which entailed numerically simulating the stress-strain response of the material. Experiments have been carried out to simulate a variety of thermal, mechanical, and environmental operating conditions endured by longitudinally (L) and transversely (T) oriented DS GTD-111. Both in-phase and out-of-phase thermo-mechanical fatigue tests were conducted. In some cases, tests in extreme environments/temperatures were needed to isolate one or at most two of the mechanisms causing damage. Microstructural examinations were carried out via SEM and optical microscopy. A continuum

  8. Syntheses and Supramolecular Structures of Two Nickel(Ⅱ) Compounds Based on Two Thiosemicarbazone Ligands

    Institute of Scientific and Technical Information of China (English)

    LI Cheng-juan; FENG Ze-jing; ZHAO Xiao-juan; WANG Su-na; DOU Jian-min

    2013-01-01

    Two new compounds,[Ni2(L1)(Py)6]Py·CH3OH(1) and [Ni3(L2)2(Py)4]·2DMF(2)(H4L1=N,N'-bisalicylbisthiocarbamide; H3L2=3-hydroxyl-2-naphthalene thiosemicarbazide; Py=pyridine; DMF=dimethyl fumarate),based upon two thiosemicarbazone ligands have been obtained and characterized by elemental analysis,Fourier transform infrared(FTIR) and X-ray diffraction(XRD).Compound 1 possesses a binuclear cluster,in which the bisalicylbisthiocarbamide acts as a hexadentate bridge.Compound 2 exhibits a linear trinuclear cluster with the triply-deprotonated ligand acting as pentadentate bridge.C—H…O,C—H…π and C—H…S weak interactions further link these molecules to form interesting supramolecular networks.

  9. Helium and hydrogen effects on the embrittlement of iron- and nickel-based alloys

    International Nuclear Information System (INIS)

    The influence of helium and hydrogen on the mechanical properties of austenitic and martensitic steels is illustrated by reviewing some recent results mainly obtained by using the light ion simulation technique. They include: (a) A comparison of the creep rupture behaviour of implanted 316L, 1.4970 and 1.4971 steels at 873 K and a tentative explanation of the differnt embrittlement mechanisms which is based on microstructural information. (b) Some general features of helium embrittlement in fatigue and crack growth of 316L steel which can be deduced from the scarce experimental data in this area. (c) Some preliminary results on the effect of implanted hydrogen on tensile properties of 316L and 1.4914 stel at low temperatures. (orig.)

  10. Novel pyridyl based azo-derivative for the selective and colorimetric detection of nickel(II)

    Science.gov (United States)

    Biswas, Sujan; Acharyya, Samik; Sarkar, Deblina; Gharami, Saswati; Mondal, Tapan Kumar

    2016-04-01

    A highly sensitive and selective pyridyl based colorimetric chemosensor (H2L) for the efficient detection of Ni2 + has been reported. The synthesized chemosensor H2L is highly efficient in detecting Ni2 + even in the presence of other metal ions that commonly co-exist with Ni2 +. H2L also shows distinct color change from green to deep red visible under naked eye due to specific binding with Ni2 +. This color change is due to formation of a new band at 510 nm upon gradual addition of Ni2 +. The association constant has been found to be 1.27 × 105 M- 1 with limit of detection (LOD) of 8.3 × 10- 7 M. Electronic structure of the H2L-Ni2 + complex and sensing mechanism have been interpreted theoretically by DFT and TDDFT calculations.

  11. Fiber laser cladding of nickel-based alloy on cast iron

    Science.gov (United States)

    Arias-González, F.; del Val, J.; Comesaña, R.; Penide, J.; Lusquiños, F.; Quintero, F.; Riveiro, A.; Boutinguiza, M.; Pou, J.

    2016-06-01

    Gray cast iron is a ferrous alloy characterized by a carbon-rich phase in form of lamellar graphite in an iron matrix while ductile cast iron presents a carbon-rich phase in form of spheroidal graphite. Graphite presents a higher laser beam absorption than iron matrix and its morphology has also a strong influence on thermal conductivity of the material. The laser cladding process of cast iron is complicated by its heterogeneous microstructure which generates non-homogeneous thermal fields. In this research work, a comparison between different types of cast iron substrates (with different graphite morphology) has been carried out to analyze its impact on the process results. A fiber laser was used to generate a NiCrBSi coating over flat substrates of gray cast iron (EN-GJL-250) and nodular cast iron (EN-GJS-400-15). The relationship between processing parameters (laser irradiance and scanning speed) and geometry of a single laser track was examined. Moreover, microstructure and composition were studied by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD). The hardness and elastic modulus were analyzed by means of micro- and nanoindentation. A hardfacing coating was generated by fiber laser cladding. Suitable processing parameters to generate the Ni-based alloy coating were determined. For the same processing parameters, gray cast iron samples present higher dilution than cast iron samples. The elastic modulus is similar for the coating and the substrate, while the Ni-based coating obtained presents a significantly superior hardness than cast iron.

  12. Hot corrosion behavior of platinum-modified nickel- and cobalt-based alloys and coatings

    Science.gov (United States)

    Deodeshmukh, Vinay Prakash

    High temperature degradation by hot corrosion (650-1000°C) and/or oxidation (>1000°C) can severely reduce the longevity of advanced gas turbine engine components. The protection of high-temperature components against hot corrosion or oxidation is typically conferred by the application of either a diffusion or overlay metallic coating that is able to form a continuous, adherent, and slow-growing oxide scale. There are currently no coatings that provide adequate protection to both hot corrosion and oxidation. Indeed, there is a particular need for such protective coatings because many advanced aero, marine, and industrial gas-turbines operate in both hot corrosion and oxidation regimes in their duty cycle. Recent work at Iowa State University (ISU) has showed that a wide range Pt+Hf-modified gamma'-Ni3Al + gamma-Ni alloy compositions form a very adherent and slow-growing Al 2O3 scale. In fact, the results reported suggest that Pt+Hf-modified gamma' + gamma coatings offer a viable superior alternative to beta-NiAl(Pt)-based coatings. The main thrust of this study was to assess and establish optimum target gamma' + gamma coating compositions for extending the service life of high-temperature gas turbine components exposed to hot corrosion and oxidation conditions. Both high temperature hot-corrosion (HTHC-900°C) and low temperature hot-corrosion (LTHC-705°C) behaviors of the Pt+Hf-modified gamma' + gamma alloys were assessed. The salt used to bring about hot corrosion was Na 2SO4. Quite interestingly, it was found that the HTHC resistance of gamma' + gamma alloys improved with up to about 10 at.% Pt addition, but then decreased significantly with increasing Pt content up to 30 at.% (the maximum level studied); however, under LTHC conditions the resistance of gamma' + gamma alloys improved with increasing Pt content up to 30 at.%. To further improve hot corrosion resistance of Pt+Hf-modified gamma' + gamma alloys, the effects of systematic additions of Cr, Si, and

  13. Growth Stresses in Thermally Grown Oxides on Nickel-Based Single-Crystal Alloys

    Science.gov (United States)

    Rettberg, Luke H.; Laux, Britta; He, Ming Y.; Hovis, David; Heuer, Arthur H.; Pollock, Tresa M.

    2016-03-01

    Growth stresses that develop in α-Al2O3 scale that form during isothermal oxidation of three Ni-based single crystal alloys have been studied to elucidate their role in coating and substrate degradation at elevated temperatures. Piezospectroscopy measurements at room temperature indicate large room temperature compressive stresses in the oxides formed at 1255 K or 1366 K (982 °C or 1093 °C) on the alloys, ranging from a high of 4.8 GPa for René N4 at 1366 K (1093 °C) to a low of 3.8 GPa for René N5 at 1255 K (982 °C). Finite element modeling of each of these systems to account for differences in coefficients of thermal expansion of the oxide and substrate indicates growth strains in the range from 0.21 to 0.44 pct at the oxidation temperature, which is an order of magnitude higher than the growth strains measured in the oxides on intermetallic coatings that are typically applied to these superalloys. The magnitudes of the growth strains do not scale with the parabolic oxidation rate constants measured for the alloys. Significant spatial inhomogeneities in the growth stresses were observed, due to (i) the presence of dendritic segregation and (ii) large carbides in the material that locally disrupts the structure of the oxide scale. The implications of these observations for failure during cyclic oxidation, fatigue cycling, and alloy design are considered.

  14. High temperature oxidation and electrochemical investigations on nickel-base alloys

    International Nuclear Information System (INIS)

    This study examined high-temperature oxidation behavior of different Ni-base alloys. In addition, electrochemical characterization of the alloy's corrosion behavior was carried out, including comparison of the properties of native passive films grown at room temperature and high temperature oxide scales. PWA 1483 (single-crystalline Ni-base superalloy) and model alloys Ni-Cr-X (where X is either Co or Al) were oxidized at 800 and 900 C in air for different time periods. The superalloy showed the best oxidation behavior at both temperatures, which might be due to the fact that the oxidation growth function is subparabolic for the model alloys and parabolic for the superalloy at 800 C. At higher temperatures, changes in the kinetics are induced, as the oxides grow faster, thus only PWA 1483 growth follows the parabolic law. Different scales in a typical sandwich form were detected, with the inner layer comprised of mostly Cr2O3, the middle layer was mixture of different oxides and spinels, depending on the alloying elements, and the oxide at the interface oxygen/oxide was found to be NiO. The influence of sample preparation could also be shown, as rougher surfaces change the oxidation kinetics from parabolic and subparabolic for polished samples to linear. The influence of moisture on the oxidation behavior of the 2nd generation single crystal Ni-base superalloys (PWA 1484, PWA 1487, CMSX 4, Rene N5 and Rene N5+) was studied at 1000 C after 100 h oxidation period. It was found that the moisture increased the oxidation rate and mostly the transient oxides growth rate. The water vapor content in air also influenced the behavior of these alloys, as they showed a higher mass gain in air + 30% water vapor than in air + 10% water vapor. The alloys PWA 1484 and CMSX 4 showed respectively the worst and best behavior in all the studied atmospheres. The addition of reactive elements, such as Yttrium, Hafnium and Lanthanum is likely to enhance the oxidation behavior of PWA 1487

  15. Laser cladding of nickel base alloy on SS316L for improved wear and corrosion behaviour

    International Nuclear Information System (INIS)

    Laser cladding by an Nd:YAG laser was employed to deposit Ni base alloy (Ni-Mo-Cr-Si) on stainless steel-316 L substrate. The resulting defect-free clad with minimum dilution of the substrate was characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and Vickers microhardness test. Dry sliding wear of the cladding and the substrate was evaluated using a ball-on-plate reciprocating wear tester against different counter bodies (WC and 52100 Cr steel). The reciprocating sliding wear resistance of the coating was evaluated as a function of the normal load, keeping the sliding amplitude and sliding speed constant. Wear mechanisms were analyzed by observation of wear track morphology using SEM-EDS. The electrochemical corrosion behavior of clad layer was studied in reducing environment (HCl) to estimate the general corrosion resistance of the laser clad layer in comparison with the substrate SS-316L. The clad layer showed higher wear resistance under reducing condition than that of the substrate material stainless steel 316L. (author)

  16. CH₃NH₃PbI₃-based planar solar cells with magnetron-sputtered nickel oxide.

    Science.gov (United States)

    Cui, Jin; Meng, Fanping; Zhang, Hua; Cao, Kun; Yuan, Huailiang; Cheng, Yibing; Huang, Feng; Wang, Mingkui

    2014-12-24

    Herein we report an investigation of a CH3NH3PbI3 planar solar cell, showing significant power conversion efficiency (PCE) improvement from 4.88% to 6.13% by introducing a homogeneous and uniform NiO blocking interlayer fabricated with the reactive magnetron sputtering method. The sputtered NiO layer exhibits enhanced crystallization, high transmittance, and uniform surface morphology as well as a preferred in-plane orientation of the (200) plane. The PCE of the sputtered-NiO-based perovskite p-i-n planar solar cell can be further promoted to 9.83% when a homogeneous and dense perovskite layer is formed with solvent-engineering technology, showing an impressive open circuit voltage of 1.10 V. This is about 33% higher than that of devices using the conventional spray pyrolysis of NiO onto a transparent conducting glass. These results highlight the importance of a morphology- and crystallization-compatible interlayer toward a high-performance inverted perovskite planar solar cell. PMID:25426540

  17. Characterization of wear mechanism by tribo-corrosion of nickel base alloys

    International Nuclear Information System (INIS)

    Some components of nuclear power plants, as steam generator tubes are made from Ni base alloys. These components are exposed to severe environment of high temperature and high pressure and submitted to contact mechanical stresses. These Ni - based alloys properties are determined by their ability to form on their surface an inner protective barrier film mainly composed of Cr2O3. The steam generator tubes are among the most difficult components to maintain, on the hand, because of their safety importance and secondly, the exchange tubes are subject to various degradation mechanisms, because of the harsh conditions of work. Wear by tribo-corrosion is a physicochemical aging mechanism which occurs in the management of the nuclear power plants life time. Tribo-corrosion is an irreversible process which involves mechanical and chemical / electrochemical interactions between surfaces in relative motion, in the presence of a corrosive environment. The goal of this study was to quantify in terms of quantity and quality the wear generated by tribo-corrosion process on Ni - Cr model alloys. Two model alloys: Ni -15Cr and Ni -30Cr were used to highlight, evaluate and compare the influence of the chromium content on the formation of the protective oxide layer and the role played by the latter one on the kinetics and mechanisms of wear by tribo-corrosion. The tribo-corrosion experiments were performed by using a pin-on-disc tribometer under controlled electrochemical conditions in LiOH - H3BO3 solution. The corrosion - wear degradation of the protective layer during continuous and intermittent unidirectional sliding tests was investigated by a three-stage tribo-corrosion protocol. In the first stage, electrochemical techniques (open circuit potential measurements and electrochemical impedance measurements) were used without applying unidirectional sliding to monitor and evaluate the characteristics of protective oxide layer formed on the surface of the two model alloys. In the

  18. Effects of Microstructural Parameters on Creep of Nickel-Base Superalloy Single Crystals

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Nathal, Michael V.

    2013-01-01

    Microstructure-sensitive creep models have been developed for Ni-base superalloy single crystals. Creep rupture testing was conducted on fourteen single crystal alloys at two applied stress levels at each of two temperatures, 982 and 1093 C. The variation in creep lives among the different alloys could be explained with regression models containing relatively few microstructural parameters. At 982 C, gamma-gamma prime lattice mismatch, gamma prime volume fraction, and initial gamma prime size were statistically significant in explaining the creep rupture lives. At 1093 C, only lattice mismatch and gamma prime volume fraction were significant. These models could explain from 84 to 94 percent of the variation in creep lives, depending on test condition. Longer creep lives were associated with alloys having more negative lattice mismatch, lower gamma prime volume fractions, and finer gamma prime sizes. The gamma-gamma prime lattice mismatch exhibited the strongest influence of all the microstructural parameters at both temperatures. Although a majority of the alloys in this study were stable with respect to topologically close packed (TCP) phases, it appeared that up to approximately 2 vol% TCP phase did not affect the 1093 C creep lives under applied stresses that produced lives of approximately 200 to 300 h. In contrast, TCP phase contents of approximately 2 vol% were detrimental at lower applied stresses where creep lives were longer. A regression model was also developed for the as-heat treated initial gamma prime size; this model showed that gamma prime solvus temperature, gamma-gamma prime lattice mismatch, and bulk Re content were all statistically significant.

  19. Coupling between Re segregation and γ/γ′ interfacial dislocations during high-temperature, low-stress creep of a nickel-based single-crystal superalloy

    International Nuclear Information System (INIS)

    The synergistic action of local elemental distribution, and in particular Re doping, with interfacial dislocations at the γ/γ′ interface is still one of the most considered and unclear issues during creep of nickel-based single-crystal superalloys. In order to investigate this problem, a detailed characterization of interfacial dislocations in a DD6 superalloy after creep loading for 12 h at high temperature and low stress was carried out using transmission electron microscopy and high-angle annular dark field scanning transmission electron microscopy techniques. In addition, the local elemental distribution near dislocation core regions was determined by energy dispersive X-ray spectroscopy (EDS) mapping. It was found for the first time that three types of interfacial protrusions are formed at the γ/γ′ interface after creep loading for 12 h under conditions of high temperature and low stress and demonstrated that the formation of these features originates from dislocation motion. Additionally, EDS mapping provides evidence for co-segregation of Re with Cr and Co at the tip of the protrusions. Based on this, a model concerning dislocation core structure and dislocation climb was proposed to explain the different morphology of the protrusions. The observations highlight the importance of the coupling between Re segregation and γ/γ′ interfacial dislocations for improving creep properties in nickel-based superalloys. The results of the study will be beneficial for the design of new high-temperature materials and for understanding the origin of the effect of Re additions in nickel-based single-crystal superalloys

  20. Optimisation des proprietes fonctionnelles des alliages a memoire de forme suite a l'application de traitements thermomecaniques

    Science.gov (United States)

    Demers, Vincent

    L'objectif de ce projet est de determiner les conditions de laminage et la temperature de traitement thermique maximisant les proprietes fonctionnelles de l'alliage a memoire de forme Ti-Ni. Les specimens sont caracterises par des mesures de calorimetrie, de microscopie optique, de gene ration de contrainte, de deformation recuperable et des essais mecaniques. Pour un cycle unique, l'utilisation d'un taux d'ecrouissage e=1.5 obtenu avec l'application d'une force de tension FT = 0.1sigma y et d'une huile minerale resulte en un echantillon droit, sans microfissure et qui apres un recuit a 400°C, produit un materiau nanostructure manifestant des proprietes fonctionnelles deux fois plus grandes que le meme materiau ayant une structure polygonisee. Pour des cycles repetes, les memes conditions de laminage sont valables mais le niveau de deformation optimal est situe entre e=0.75-2, et depend particulierement du mode de sollicitation, du niveau de stabilisation et du nombre de cycles a la rupture requis par l'application.

  1. High Temperature Oxidation of Nickel-based Cermet Coatings Composed of Al2O3 and TiO2 Nanosized Particles

    Science.gov (United States)

    Farrokhzad, M. A.; Khan, T. I.

    2014-09-01

    New technological challenges in oil production require materials that can resist high temperature oxidation. In-Situ Combustion (ISC) oil production technique is a new method that uses injection of air and ignition techniques to reduce the viscosity of bitumen in a reservoir and as a result crude bitumen can be produced and extracted from the reservoir. During the in-situ combustion process, production pipes and other mechanical components can be exposed to air-like gaseous environments at extreme temperatures as high as 700 °C. To protect or reduce the surface degradation of pipes and mechanical components used in in-situ combustion, the use of nickel-based ceramic-metallic (cermet) coating produced by co-electrodeposition of nanosized Al2O3 and TiO2 have been suggested and earlier research on these coatings have shown promising oxidation resistance against atmospheric oxygen and combustion gases at elevated temperatures. Co-electrodeposition of nickel-based cermet coatings is a low-cost method that has the benefit of allowing both internal and external surfaces of pipes and components to be coated during a single electroplating process. Research has shown that the volume fraction of dispersed nanosized Al2O3 and TiO2 particles in the nickel matrix which affects the oxidation resistance of the coating can be controlled by the concentration of these particles in the electrolyte solution, as well as the applied current density during electrodeposition. This paper investigates the high temperature oxidation behaviour of novel nanostructured cermet coatings composed of two types of dispersed nanosized ceramic particles (Al2O3 and TiO2) in a nickel matrix and produced by coelectrodeposition technique as a function of the concentration of these particles in the electrolyte solution and applied current density. For this purpose, high temperature oxidation tests were conducted in dry air for 96 hours at 700 °C to obtain mass changes (per unit of area) at specific time

  2. Mathematical modelling of brittle phase precipitation in complex ruthenium containing nickel-based superalloys

    International Nuclear Information System (INIS)

    A new model has been developed in this work which is capable of simulating the precipitation kinetics of brittle phases, especially TCP-phases (topologically close packed phases) in ruthenium containing superalloys. The model simultaneously simulates the nucleation and the growth stage of precipitation for any number of precipitating phases. The CALPHAD method (Calculation of Phase Diagrams) is employed to calculate thermodynamic properties, such as the driving force or phase compositions in equilibrium. For calculation of diffusion coefficients, kinetic mobility databases which are also based on the CALPHAD-method are used. The model is fully capable of handling multicomponent effects, which are common in complex superalloys. Metastable phases can be treated and will automatically be dissolved if they get unstable. As the model is based on the general CALPHAD method, it can be applied to a broad range of precipitation processes in different alloys as long as the relevant thermodynamic and kinetic databases are available. The developed model proves that the TCP-phases precipitate in a sequence of phases. The first phase that is often formed is the metastable σ-phase because it has the lowest interface energy due to low-energy planes at the interface between matrix and precipitate. After several hundred hours the stable μ- and P-phases start to precipitate by nucleating at the σ-phase which is energetically favourable. During the growth of these stable phases the sigma-phase is continuously dissolved. It can be shown by thermodynamic CALPHAD calculations that the sigma-phase has a lower Gibbs free enthalpy than the μ- and P-phase. All required parameters of the model, such as interface energy and nucleate densities, have been estimated. The mechanisms of suppression of TCP-phase precipitation in the presence of ruthenium in superalloys were investigated with the newly developed model. It is shown by the simulations that ruthenium mostly affects the nucleation

  3. Enhanced Performance of Flexible Dye-Sensitized Solar Cell based on Nickel Sulfide/Polyaniline/Titanium Counter Electrode

    International Nuclear Information System (INIS)

    Much higher photovoltaic performance of flexible dye-sensitized solar cell with NiS/PANI/Ti counter electrode as well as that of Pt configuration device. - Highlights: • The NiS/PANI/Ti composite were first time prepared and employed as counter electrode (CE) for Pt-free flexible DSSC. • The NiS/PANI/Ti CE showed great electrocatalytic ability and low resistance of 1.48 ± 0.02 Ω · cm2 for I–/I3–electrolyte. • The power conversion efficiency of the FDSSC reached 7.35% based on the NiS/PANI/Ti CE. - Abstract: A novel titanium foil substrate strategy for the synthesis of high electrocatalytic activity nickel sulfide/polyaniline/titanium (NiS/PANI/Ti) composite film with one-dimensional (1D) net-work structure by using an in situ electropolymerization route, and proposed as platinum (Pt)-free counter electrode (CE) catalyst for flexible dye-sensitized solar cells (FDSSCs). The photovoltaic performance of the FDSSC based on the NiS/PANI/Ti CE exhibits Jsc of 14.56 mA · cm−2, Voc of 0.743 V, FF of 0.68, and corresponding to the η of 7.35%, much higher photoelectric conversion efficiency than that of Pt/Ti CE (6.24%). The NiS/PANI/Ti CE with 1D net-work structure is characterized by using the scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel polarization plots. The NiS/PANI/Ti CE presents multiple functions, i.e., excellent conductivity, great electrocatalytic ability for iodine/triiodine, and lower charge transfer resistance of 1.48 ± 0.02 Ω · cm2 compared to the Pt/Ti electrode (2.25 ± 0.02 Ω · cm2). The photocurrent-photovoltage (J-V) character curves are further used to calculate theoretical short-current densities and open-circuit voltage of the devices. Therefore, the NiS/PANI/Ti CE with 1D net-work structure can be considered as a promising and efficient CE for FDSSCs

  4. Zinc and nickel removal in limestone based treatment of acid mine drainage: The relative role of adsorption and co-precipitation

    International Nuclear Information System (INIS)

    Highlights: • Limestone treatment of mining impacted water was simulated in batch reactors. • Zinc and nickel removals were quantified/characterized with a sequential extraction. • Removals were described with a surface complexation and a surface precipitation model. • Extraction/modeling results imply mechanisms beyond adsorption dominate metal removal. - Abstract: Mining influenced water may contain high metal and sulfate loads, and have low pH (acid mine drainage). Removal of these metals prior to environmental discharge is critical to maintain ecosystem vitality. Limestone based passive treatment systems are commonly used for pH neutralization. The same conditions that lead to pH neutralization may also remove a substantial amount of metals from solution, but the connection between treatment conditions and metal removal are not well understood. In this study, zinc and nickel removals are quantified in batch reactor simulated limestone treatment of acid mine drainage. The resulting solid phase is characterized with a sequential extraction procedure, and the removals are interpreted using surface complexation and surface precipitation models. Zinc and nickel removals are closely linked to the initial iron concentration in the mine water, but are also affected by pH, alkalinity, calcium and sulfate concentrations. The surface complexation model was based on literature descriptions of hydrous ferric oxide. In order to obtain a sufficient fit to the data, the surface site density was increased to an unrealistically high value. Uptake data was also fit to an existing surface precipitation model. The values used are similar to those found in previous studies. Both models indicate that adsorption is not the dominant removal process in the treatment system. Using adsorption only models will generally underpredict metal removals within limestone based treatment systems

  5. Fireside corrosion of nickel base alloys in future 700 C coal fired power plants; Rauchgasseitige Korrosion von Nickelbasislegierungen fuer zukuenftige 700 C-Dampfkraftwerke

    Energy Technology Data Exchange (ETDEWEB)

    Luettschwager, Frank

    2011-09-27

    Coal is still the most important energy source in Germany. In 2009 it produced 42.9 % of the overall German electrical power. Coal is available world-wide in large quantities and can be delivered economically. One of the possible ways to reduce CO{sub 2} pollution is the increase of efficiency of coal fired power plants, which requires steam conditions of up to 700 C - 730 C and 350 bar. Because many German power units will reach the end of their technical lifespan in a few years or the following decade, one will have the possibility to build up modern types of power plants with increased efficiency of more than 50 %. Some international standards (European Pressure Equipment Directive or ASME Boiler and Pressure Vessel Code) require 100 000 hour creep rupture strength of 100 MPa at 750 C. Therefore, nickel base alloys are in the focus of material qualification processes. Nickel base alloys are well investigated due to their hot corrosion behaviour. It is known that sodium sulphate may generate hot corrosion on those alloys at temperatures above its melting point of 884 C. On nickel base alloys an eutectic mixture of nickel sulphate and sodium sulphate with a melting point of 671 C can be generated, which leads to accelerated corrosion. This work examines, whether the high amount of sulphur and alkali metals will induce hot corrosion at the estimated working temperature on devices manufactured from nickel base alloy. Two synthetic coal ash deposits, according to the chemical composition of hard coal and lignite, and typical flue gases with and without sulphur dioxide were blended of pure agents. The reactions of the deposits with heater tubes' materials and synthetic flue gases are examined in the temperature range from 650 C to 800 C and different time ranges up to 2000 hours. The corroded specimen are examined with SEM/EDX to identify relevant corrosion products and determine the corrosivity of deposited compounds. Deposits increase the corrosion rate of

  6. Highly active and durable methanol oxidation electrocatalyst based on the synergy of platinum–nickel hydroxide–graphene

    Science.gov (United States)

    Huang, Wenjing; Wang, Hongtao; Zhou, Jigang; Wang, Jian; Duchesne, Paul N.; Muir, David; Zhang, Peng; Han, Na; Zhao, Feipeng; Zeng, Min; Zhong, Jun; Jin, Chuanhong; Li, Yanguang; Lee, Shuit-Tong; Dai, Hongjie

    2015-01-01

    Active and durable electrocatalysts for methanol oxidation reaction are of critical importance to the commercial viability of direct methanol fuel cell technology. Unfortunately, current methanol oxidation electrocatalysts fall far short of expectations and suffer from rapid activity degradation. Here we report platinum–nickel hydroxide–graphene ternary hybrids as a possible solution to this long-standing issue. The incorporation of highly defective nickel hydroxide nanostructures is believed to play the decisive role in promoting the dissociative adsorption of water molecules and subsequent oxidative removal of carbonaceous poison on neighbouring platinum sites. As a result, the ternary hybrids exhibit exceptional activity and durability towards efficient methanol oxidation reaction. Under periodic reactivations, the hybrids can endure at least 500,000 s with negligible activity loss, which is, to the best of our knowledge, two to three orders of magnitude longer than all available electrocatalysts. PMID:26602295

  7. Highly active and durable methanol oxidation electrocatalyst based on the synergy of platinum-nickel hydroxide-graphene.

    Science.gov (United States)

    Huang, Wenjing; Wang, Hongtao; Zhou, Jigang; Wang, Jian; Duchesne, Paul N; Muir, David; Zhang, Peng; Han, Na; Zhao, Feipeng; Zeng, Min; Zhong, Jun; Jin, Chuanhong; Li, Yanguang; Lee, Shuit-Tong; Dai, Hongjie

    2015-01-01

    Active and durable electrocatalysts for methanol oxidation reaction are of critical importance to the commercial viability of direct methanol fuel cell technology. Unfortunately, current methanol oxidation electrocatalysts fall far short of expectations and suffer from rapid activity degradation. Here we report platinum-nickel hydroxide-graphene ternary hybrids as a possible solution to this long-standing issue. The incorporation of highly defective nickel hydroxide nanostructures is believed to play the decisive role in promoting the dissociative adsorption of water molecules and subsequent oxidative removal of carbonaceous poison on neighbouring platinum sites. As a result, the ternary hybrids exhibit exceptional activity and durability towards efficient methanol oxidation reaction. Under periodic reactivations, the hybrids can endure at least 500,000 s with negligible activity loss, which is, to the best of our knowledge, two to three orders of magnitude longer than all available electrocatalysts. PMID:26602295

  8. G-quadruplex vs. duplex-DNA binding of nickel(II) and zinc(II) Schiff base complexes.

    Science.gov (United States)

    Bonsignore, Riccardo; Terenzi, Alessio; Spinello, Angelo; Martorana, Annamaria; Lauria, Antonino; Almerico, Anna Maria; Keppler, Bernhard K; Barone, Giampaolo

    2016-08-01

    Novel nickel(II) (1) and zinc(II) (2) complexes of a Salen-like ligand, carrying a pyrimidine ring on the N,N' bridge, were synthesized and characterized. Their interaction with duplex and G-quadruplex DNA was investigated in aqueous solution through UV-visible absorption, circular dichroism and viscometry measurements. The results obtained point out that, while the zinc(II) complex does not interact with both duplex and G-quadruplex DNA, the nickel(II) complex 1 binds preferentially to G-quadruplex respect to duplex-DNA, with values of the DNA-binding constants, Kb, 2.6×10(5)M(-1) and 3.5×10(4)M(-1), respectively. Molecular dynamics simulations provided an atomic level model of the top-stacking binding occurring between 1 and hTelo (a 22-mer sequence oligonucleotide) in G-quadruplex conformation. PMID:27230387

  9. Highly active and durable methanol oxidation electrocatalyst based on the synergy of platinum-nickel hydroxide-graphene

    Science.gov (United States)

    Huang, Wenjing; Wang, Hongtao; Zhou, Jigang; Wang, Jian; Duchesne, Paul N.; Muir, David; Zhang, Peng; Han, Na; Zhao, Feipeng; Zeng, Min; Zhong, Jun; Jin, Chuanhong; Li, Yanguang; Lee, Shuit-Tong; Dai, Hongjie

    2015-11-01

    Active and durable electrocatalysts for methanol oxidation reaction are of critical importance to the commercial viability of direct methanol fuel cell technology. Unfortunately, current methanol oxidation electrocatalysts fall far short of expectations and suffer from rapid activity degradation. Here we report platinum-nickel hydroxide-graphene ternary hybrids as a possible solution to this long-standing issue. The incorporation of highly defective nickel hydroxide nanostructures is believed to play the decisive role in promoting the dissociative adsorption of water molecules and subsequent oxidative removal of carbonaceous poison on neighbouring platinum sites. As a result, the ternary hybrids exhibit exceptional activity and durability towards efficient methanol oxidation reaction. Under periodic reactivations, the hybrids can endure at least 500,000 s with negligible activity loss, which is, to the best of our knowledge, two to three orders of magnitude longer than all available electrocatalysts.

  10. The creep behaviour of single-crystal turbine blade alloys basing on nickel SC 16 with [011] orientation; Das Kriechverhalten der einkristallinen Nickelbasisturbinenschaufellegierung SC 16 MIT [011]-Orientierung

    Energy Technology Data Exchange (ETDEWEB)

    Klingelhoeffer, H.; Chrzanowski, U.; Kraemer, E.; Frenz, H.; Ziebs, J. [Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany)

    1997-12-31

    This paper describes the creep behaviour of single-crystal turbine blade alloys basing on nickel SC 16 compared to the material IN 738 LC while submitted to creep strain. The creep properties of samples with [011] and [001]-orientation are compared with each other. (orig./MM) [Deutsch] In der vorliegenden Arbeit wird das Kriechverhalten der einkristallinen Nickelbasissuperlegierung SC 16 im Vergleich zum Werkstoff IN 738 LC unter Kriechbeanspruchung dargestellt. Dabei werden die Kriecheigenschaften von Proben mit [011]- und [001]-Orientierung gegenuebergestellt. (orig./MM)

  11. Oxidation of a chromia-forming nickel base alloy at high temperature in mixed diluted CO/H2O atmospheres

    OpenAIRE

    Rouillard, Fabien; Cabet, Céline; Wolski, Krzysztof; Pijolat, Michèle

    2009-01-01

    Corrosion of a chromia-forming nickel base alloy, Haynes 230_, has been investigated under impure helium containing a few Pa of CO and H2O at 900 °C. It has been found that this alloy reacts simultaneously with CO and H2O. Oxidation by CO has been revealed to occur mainly in the first hours. CO diffuses through the scale via short-circuit pathways and oxidizes Al, Cr and Si at the oxide/metal interface. Kinetics of CO oxidation has been investigated and several rate limiting steps are propose...

  12. A magnetic investigation of phase transitions for metal-hydrogen systems based on nickel by means of computer-aided data acquisition

    International Nuclear Information System (INIS)

    In the present thesis the magnetic behaviour of Nickel-based metal-hydrogen systems is investigated in relation to its background in metal physics, in order to get information on the formation and the decomposition of metal-hydrogen phases. The magnetic investigations are performed at the systems Ni-Cu-H and Ni-Cr-H with Cu up to 40 at% and Cr up to 7 at%. The differential susceptibility is measured during hydration and decomposition of hydrides and the connection between magnetic moment and hydrogen concentration is discussed. (BHO)

  13. Evaluation of gamma prime volume fractions and lattice misfits in a nickel base superalloy using the external standard X-ray diffraction method

    International Nuclear Information System (INIS)

    The unconstrained lattice parameters and volume fractions of γ' for a low misfit nickel based superalloy were evaluated using X-ray diffraction techniques. Extraction techniques were used to provide unconstrained γ' powders for both water quenched and slow cooled samples that were aged at 760 deg. C for 0, 25, 50, 100, and 200 h. The external standard method was used to determine the volume fraction for the unaged water quenched sample and the slow cooled sample aged for 200 h. These two extremes in processing conditions provided an increase in the total volume fraction of γ'.

  14. Thermodynamic Possibilities of Pure Hydrogen Production by a Nickel or Cobalt-based Redox Chemical Looping Process at Lower Temperatures.

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Karel; Pohořelý, Michael; Wieczorek, K.; Baxter, D.; Schosger, J.P.

    Bratislava: Slovak Society of Chemical Engineering, 2007 - (Markoš, J.; Štefuca, V.), s. 241 ISBN 978-80-227-2640-5. [International Conference of Slovak Society of Chemical Engineering /34./. Tatranské Matliare (SK), 21.05.2007-25.05.2007] Institutional research plan: CEZ:AV0Z40720504 Keywords : hydrogen * nickel * cobalt Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  15. High temperature corrosion of iron-base and nickel-base alloys for hydrogen production apparatus by thermochemical method in H2O+SO3 atmosphere

    International Nuclear Information System (INIS)

    Corrosion tests for ten iron-base and nickel-base alloys at 850degC for 1000h in H2O + SO3 atmosphere were carried out to obtain data for selection of candidate container materials in the thermochemical process which produces hydrogen from water by use of iodine and sulfur as circulating materials. The following results were obtained: (1) Oxidation, spallation of corrosion film, uniform corrosion and grain boundary penetration composed of internal oxidation and sulfuration occur in this atmosphere and the corrosion proceeds by grain boundary penetration. (2) SUS304, SUS316 and Hastelloy C276 are inferior in corrosion resistance and SUS329J4L is superior among ten alloys used in this experiment. Alloys such as Alloy 800H and Hastelloy XR show intermediate corrosion resistance. (3) Oxide films of alloys containing iron and chromium are mostly composed of outer iron-oxide and inner chromium-oxide. Sulfur concentrates at scale/metal interfaces and grain boundary penetration portions, and sulfides form. (4) Corrosion in this atmosphere could be expressed using the parabolic law between the grain boundary penetration depth and time. It is considered that causes of the apparently observed parabolic law were a high concentration of SO3 and change of the gas composition caused by catalytic action of the corrosion film formed with the progress of corrosion. (author)

  16. Microstructure evolution and FEM analysis of a [0 1 1] oriented single crystal nickel-based superalloy during compressive creep

    International Nuclear Information System (INIS)

    Highlights: ► We study microstructure evolution of [0 1 1] SC superalloy during compressive creep. ► We analyze the γ′ phase evolution regularity with the aid of finite element method. ► We constitute the γ′ phase existence mode in three-dimensional space during creep. ► Compressive strain may repel Al, Ti atoms to promote directional growth of γ′ phase. ► Driving forces of elements diffusion and γ′ phase directional growth are investigated. -- Abstract: By means of the stress–strain finite element method (FEM) in elastic–plastic regime, the influences of the applied stress on the distribution of von Mises stress and evolution of shape regularity of γ′ phase in a [0 1 1] oriented single crystal nickel-based superalloy are investigated. Results show that, after full heat treatment, the microstructure of [0 1 1] oriented single crystal superalloy consists of the cuboidal γ′ phase embedded coherently in the γ matrix phase, and on (1 0 0) plane aligned regularly at angle of 45° relative to the [0 1 1] orientation. During compressive creep, the cuboidal γ′ phase is transformed into the mesh-like lamellar rafted structure on (1 0 0) plane. Therefore, the changes of the lattice strain, the strain energy density and interfacial energy are thought to be the driving forces of the element diffusion and γ′ phase directional growth. During compressive creep, the lattice contraction occurs on (1 0 0) plane of the cuboidal γ′ phase along [0 0 1] and [0 1 0] directions, whose extruding effect may repel Al, Ti atoms with bigger radius. Therefore, the expanding strain of lattices along [1 0 0] direction on (0 1 0) and (0 0 1) planes of the cuboidal γ′ phase may trap Al, Ti atoms to promote the directional growth of γ′ phase on (1 0 0) plane along [0 0 1] and [0 1 0] directions, which is thought to be the main reason for the γ′ phase growing directionally into the mesh-like lamellar structure

  17. Nickel and titanium nanoboride composite coating

    Science.gov (United States)

    Efimova, K. A.; Galevsky, G. V.; Rudneva, V. V.; Kozyrev, N. A.; Orshanskaya, E. G.

    2015-09-01

    Electrodeposition conditions, structural-physical and mechanical properties (microhardness, cohesion with a base, wear resistance, corrosion currents) of electroplated composite coatings on the base of nickel with nano and micro-powders of titanium boride are investigated. It has been found out that electro-crystallization of nickel with boride nanoparticles is the cause of coating formation with structural fragments of small sizes, low porosity and improved physical and mechanical properties. Titanium nano-boride is a component of composite coating, as well as an effective modifier of nickel matrix. Nano-boride of the electrolyte improves efficiency of the latter due to increased permissible upper limit of the cathodic current density.

  18. Corrosion behavior of Haynes {sup registered} 230 {sup registered} nickel-based super-alloys for integrated coal gasification combined cycle syngas plants. A plant exposure study

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sungkyu; Lee, Jieun; Kang, Suk-Hwan; Lee, Seung-Jong; Yun, Yongseung [Institute for Advanced Engineering (IAE), Gyeonggi-do (Korea, Republic of). Plant Engineering Center; Kim, Min Jung [Sungkyunkwan Univ, Gyeonggi-do (Korea, Republic of). Advanced Materials Technology Research Center

    2015-07-01

    The corrosion behavior of commercially available Haynes {sup registered} 230 {sup registered} nickel-based alloy samples was investigated by exposure to coal-gasifying integrated coal gasification combined cycle pilot plant facilities affiliated with the Institute for Advanced Engineering (2.005 MPa and 160-300 C). The morphological and microstructural analyses of the exposed samples were conducted using scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis on the external surface of the recovered corrosion test samples to obtain information of the corrosion scale. These analyses based on the pre- and post-exposure corrosion test samples combined with thermodynamic Ellingham-Pourbaix stability diagrams provided preliminary insight into the mechanism of the observed corrosion behavior prevailing in the piping materials that connected the particulate removal unit and water scrubber of the integrated coal gasification combined cycle pilot plant. Uniform material wastage was observed after 46 hours of operation, and a preliminary corrosion mechanism was suggested: the observed material waste and corrosion behavior of the Haynes {sup registered} 230 {sup registered} nickel-based alloy samples cut off from the coal syngas integrated coal gasification combined cycle plant were explained by the formation of discontinuous (complex) oxide phases and subsequent chlorine-induced active oxidation under the predominantly reducing environment encountered. This contribution continues the already published studies of the Fe-Ni-Cr-Co alloy Haynes {sup registered} 556 {sup registered}.

  19. Corrosion behavior of Haynes registered 230 registered nickel-based super-alloys for integrated coal gasification combined cycle syngas plants. A plant exposure study

    International Nuclear Information System (INIS)

    The corrosion behavior of commercially available Haynes registered 230 registered nickel-based alloy samples was investigated by exposure to coal-gasifying integrated coal gasification combined cycle pilot plant facilities affiliated with the Institute for Advanced Engineering (2.005 MPa and 160-300 C). The morphological and microstructural analyses of the exposed samples were conducted using scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis on the external surface of the recovered corrosion test samples to obtain information of the corrosion scale. These analyses based on the pre- and post-exposure corrosion test samples combined with thermodynamic Ellingham-Pourbaix stability diagrams provided preliminary insight into the mechanism of the observed corrosion behavior prevailing in the piping materials that connected the particulate removal unit and water scrubber of the integrated coal gasification combined cycle pilot plant. Uniform material wastage was observed after 46 hours of operation, and a preliminary corrosion mechanism was suggested: the observed material waste and corrosion behavior of the Haynes registered 230 registered nickel-based alloy samples cut off from the coal syngas integrated coal gasification combined cycle plant were explained by the formation of discontinuous (complex) oxide phases and subsequent chlorine-induced active oxidation under the predominantly reducing environment encountered. This contribution continues the already published studies of the Fe-Ni-Cr-Co alloy Haynes registered 556 registered.

  20. Design of a rotary reactor for chemical-looping combustion. Part 2: Comparison of copper-, nickel-, and iron-based oxygen carriers

    KAUST Repository

    Zhao, Zhenlong

    2014-04-01

    Chemical-looping combustion (CLC) is a novel and promising option for several applications including carbon capture (CC), fuel reforming, H 2 generation, etc. Previous studies demonstrated the feasibility of performing CLC in a novel rotary design with micro-channel structures. Part 1 of this series studied the fundamentals of the reactor design and proposed a comprehensive design procedure, enabling a systematic methodology of designing and evaluating the rotary CLC reactor with different OCs and operating conditions. This paper presents the application of the methodology to the designs with three commonly used OCs, i.e., copper, nickel, and iron. The physical properties and the reactivities of the three OCs are compared at operating conditions suitable for the rotary CLC. Nickel has the highest reduction rate, but relatively slow oxidation reactivity while the iron reduction rate is most sensitive to the fuel concentration. The design parameters and the operating conditions for the three OCs are selected, following the strategies proposed in Part 1, and the performances are evaluated using a one-dimensional plug-flow model developed previously. The simulations show that for all OCs, complete fuel conversion and high carbon separation efficiency can be achieved at periodic stationary state with reasonable operational stabilities. The nickel-based design includes the smallest dimensions because of its fast reduction rate. The operation of nickel case is mainly limited to the slow oxidation rate, and hence a relatively large share of air sector is used. The iron-based design has the largest size, due to its slow reduction reactivity near the exit or in the fuel purge sector where the fuel concentration is low. The gas flow temperature increases monotonically for all the cases, and is mainly determined by the solid temperature. In the periodic state, the local temperature variation is within 40 K and the thermal distortion is limited. The design of the rotary CLC is

  1. X-ray photoelectron spectroscopy study of nickel and nickel-base alloy surface alterations in simulated hot corrosion conditions with emphasis on eventual application to turbine blade corrosion

    Science.gov (United States)

    Mateescu, G. D.; Smith, S. R.

    1979-01-01

    Research on the high temperature oxidation and Na2SO4 induced hot corrosion of some nickel base superalloys was accomplished by using ESCA to determine the surface composition of the oxidized or corroded samples. Oxidation was carried out at 900 or 1000 C in slowly flowing O2 for samples of B-1900, NASA-TRW VIA, 713C, and IN-738. Oxidation times ranged from 0.5 to 100 hr. Hot corrosion of B-1900 was induced applying a coating of Na2SO4 to peroxidized samples, the heating to 900 C in slowly flowing O2. For oxidized samples, the predominant type of scale formed by each superalloy was determined, and a marked surface enrichment of Ti was found in each case. For corroded samples, the transfer of significant amounts of material from the oxide layer to the surface of the salt layer was observed to occur long before the onset of accelerating weight-gain. Changes in surface composition were observed to coincide with the beginning of accelerating corrosion, the most striking of which was a tenfold decrease in the sulfur to sodium ration and an increase in the Cr(VI) ratio.

  2. Characterisation of γ' precipitates in a single crystal nickel base superalloy SC16 using SEM, TEM and SANS as complimentary measuring tools

    International Nuclear Information System (INIS)

    Characterisation of the microstructure in nickel base superalloys is important for understanding and predicting the behaviour of these complex alloys. Large particle sizes of γ' precipitates in modern alloys, their regular arrangement in periodic arrays in the γ matrix and the complexity of the microstructure evolving under deformation at high temperatures, pose serious challenge to the precise characterisation of the microstructure. This necessitates the use of complementary measuring tools e.g. X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM), optical metallography etc. Small angle neutron scattering (SANS) is a useful modern technique, used to characterise fine precipitates and inhomogenities (< 50 nm) in materials. So far, established methodology does not exist for using SANS to characterise large particles like γ' precipitates in superalloys. In this paper we develop a model to analyse SANS intensity profiles from large (∼ 400 nm) γ' precipitates and together with the help of complementary methods such as SEM and TEM, characterise them in a single crystal nickel base alloy SC16. (orig.)

  3. Covalent functionalization of multi-wall carbon nanotubes (MWNTs) by nickel(II) Schiff-base complex: Synthesis, characterization and liquid phase oxidation of phenol with hydrogen peroxide

    International Nuclear Information System (INIS)

    The chemical modification of multi-wall carbon nanotubes (MWNTs) is an emerging area in material science. In the present study, hydroxyl functionalized nickel(II) Schiff-base has been covalently anchored on modified MWNTs. The new modified MWNTs have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron (XPS), thermal analysis, UV-vis, diffuse reflectance (DRS), FT-IR spectroscopy and elemental analysis. The results suggest that the symmetrical Schiff-base; N,N'-bis(4-hydroxysalicylidene)-ethylene-1,2-diamine; H2[(OH)2-salen]; is a bivalent anion with tetradentate N2O2 donors derived from the phenolic oxygen and azomethine nitrogen. The formula was found to be [Ni((OH)2-salen)] for the 1:1 non-electrolytic complex. Multi-wall carbon nanotubes covalently anchored nickel(II) complex ([Ni((OH)2-salen)]-MWNTs) catalyze the oxidation of phenol with H2O2. Oxidation of phenol catalyzed by this complex gave catechol and hydroquinone as major products. A suitable reaction condition has been optimized for [Ni((OH)2-salen)]MWNTs by considering the effect of various parameters such as reaction time and amount of oxidant, different solvents, concentration of substrate, etc. for the maximum transformation of phenol

  4. Covalent functionalization of multi-wall carbon nanotubes (MWNTs) by nickel(II) Schiff-base complex: Synthesis, characterization and liquid phase oxidation of phenol with hydrogen peroxide

    Science.gov (United States)

    Salavati-Niasari, Masoud; Bazarganipour, Mehdi

    2008-12-01

    The chemical modification of multi-wall carbon nanotubes (MWNTs) is an emerging area in material science. In the present study, hydroxyl functionalized nickel(II) Schiff-base has been covalently anchored on modified MWNTs. The new modified MWNTs have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron (XPS), thermal analysis, UV-vis, diffuse reflectance (DRS), FT-IR spectroscopy and elemental analysis. The results suggest that the symmetrical Schiff-base; N, N'-bis(4-hydroxysalicylidene)-ethylene-1,2-diamine; H 2[(OH) 2-salen]; is a bivalent anion with tetradentate N 2O 2 donors derived from the phenolic oxygen and azomethine nitrogen. The formula was found to be [Ni((OH) 2-salen)] for the 1:1 non-electrolytic complex. Multi-wall carbon nanotubes covalently anchored nickel(II) complex ([Ni((OH) 2-salen)]@MWNTs) catalyze the oxidation of phenol with H 2O 2. Oxidation of phenol catalyzed by this complex gave catechol and hydroquinone as major products. A suitable reaction condition has been optimized for [Ni((OH) 2-salen)]@MWNTs by considering the effect of various parameters such as reaction time and amount of oxidant, different solvents, concentration of substrate, etc. for the maximum transformation of phenol.

  5. Oxidation and mechanical behaviors of solid-solution hardening nickel-base superalloys in high temperature helium environments

    International Nuclear Information System (INIS)

    Solid-solution hardening nickel-base superalloys Alloy 617 and Haynes 230 were examined for VHTR intermediate heat exchanger applications. This study focused on high temperature oxidation and aging degradation and how they affected low temperature embrittlement and creep behaviors at high temperatures. Oxidation tests and aging heat treatment were carried out at 900 .deg. C and 1000 .deg. C in impure helium environments that contained H2, H2O, CO, CO2, and CH4 in order to simulate VHTR coolant chemistry. The oxidation kinetics of the alloys followed the parabolic law of oxidation in all cases. In impure helium environments that had very low oxygen activity, a Cr2O3 layer, TiO2 ridges on the grain boundaries, and isolated MnCr2O4 grains on top of the Cr2O3 layer were formed for Alloy 617, while a Cr2O3 inner layer and a NiO outer layer were formed in air with high oxygen activity due to the different thermodynamics. For Haynes 230, a Cr2O3 inner layer and a protective MnCr2O4 outer layer formed, which increased the oxidation resistance. The oxidation kinetics of Haynes 230 was changed by Mn depletion at the initial stage of oxidation. A dense MnCr2O4 oxide layer grew on top of a Cr2O3 layer in impure helium environments for Haynes 230, while quasi-columnar MnCr2O4 grains grew in air, which resulted in a better oxidation resistance for the impure helium environments. Cellular Cr2O3 oxides for Alloy 617 and MnCr2O4 whiskers/platelets for Haynes 230 were formed in impure helium at 900 .deg. C due to the more rapid dissociation of water vapor and CO2 molecules compared to the oxygen molecules. The formation of irregular oxides are believed to have been due to a VLS mechanism based on the appearance of droplets on the tips of the whiskers, the formation of which was more preferential on the vertex of MnCr2O4 crystals. The effect of a small amount of CH4 and H2 on the oxidation kinetics of the alloys was insignificant. In slightly oxidizing and decarburizing environments

  6. On the stability of oxides formed under BWR conditions: some observations on a stainless steel and nickel-base alloys

    International Nuclear Information System (INIS)

    a misleading conclusion. Corrosion of reactor materials is more appropriately considered to be a kinetic-controlled process in which some rate-limiting process may determine how fast the materials corrode and what corrosion products they actually form. For such a system thermodynamic prediction would not be successful and an experimental study on the oxides actually formed in a reactor system is necessary. Because fuel CRUD is highly radioactive and oxide films formed on reactor materials are generally thin, there has been a limited success in their structural characterizations. In recent years high resolution electron microscopy has become readily available for nuclear industries with which much more details about fuel CRUD and the oxide films can be further explored. In this paper, we summarize some of our recent advancements in structural characterization of fuel CRUD and oxide films formed on a stainless steel of type 316L and some nickel-base alloys (Alloys X-750, 82, 182, 52 M and 152) that have been exposed either in reactor water environments or in a laboratory loop under simulated BWR conditions. Based on these observations, the stability of various formed oxides is discussed to shed some light on the possible correlations between corrosion rate, and oxide film microstructures and water chemistry effects. (authors)

  7. Investigation and growth of nickel coatings for electrical contact applications

    OpenAIRE

    Fawakhiri, Maria

    2009-01-01

    Nickel based coatings were deposited on copper substrates by two different sputtering techniques from a nickel alloy based target. The substrates used were commercially available copper based substrates for low duty electrical contacts. The coatings were analyzed and evaluated as copper diffusion barriers for electrical contact applications. In addition two types of commercially available electroplated nickel coatings (referred to as type A electroplated coatings and type B electroplated coat...

  8. Novel Approach to Tar Removal from Biomass Producer Gas by Means of a Nickel-based Catalyst

    Czech Academy of Sciences Publication Activity Database

    Vosecký, Martin; Kameníková, Petra; Pohořelý, Michael; Skoblia, Sergej; Punčochář, Miroslav

    Beijing : Tsingua University Press, 2009 - (Yue, G.; Zhang, H.; Zhao, C.; Luo, Z.), s. 740-746 ISBN 978-7-302-20146-5. [International Conference on Fluidized Bed Combustion /20./. Xi’an (CN), 18.05.2009-21.05.2009] R&D Projects: GA ČR(CZ) GA104/07/0977; GA MŠk 2B08048 Institutional research plan: CEZ:AV0Z40720504 Keywords : catalytic tar removal * nickel catalyst * biomass gasification Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://ww.fbc2009.org

  9. Contribution to the study of the hydrogen-deuterium exchange in presence of a catalyst based on nickel oxide

    International Nuclear Information System (INIS)

    This research thesis focuses on the study of the mechanism of the hydrogen-deuterium isotopic exchange reaction upon the contact with a nickel oxide which is either pure or containing other cations like lithium or gallium. The coupling of the reaction system with a chromatographic loop allows the study of the exchange reaction kinetics in a simple and straightforward way. After a presentation of the experimental techniques and materials the author reports the study of hydrogen chemisorption which allowed the identification of different adsorption mechanisms with respect to the temperature. She reports a kinetic study of hydrogen-deuterium exchange at different temperatures (-78 and -196 C)

  10. Welding of stainless and nickel based materials in the chemical industry. Consumables and procedures. Soldadura de aceros inoxidables y de materiales de base niquel en la industria quimica. Consumibles y procedimientos

    Energy Technology Data Exchange (ETDEWEB)

    Stromberg, J.; Budgifvars, S. (The ESA Grouo, Geoteborg (Sweden))

    1994-01-01

    In the chemical and petrochemical process industry a large range of various stainless and nickel based materials are used to meet high demands on corrosion resistance for optimum service performance. These materials include standard stainless steels, duplex and super duplex steels, super austenitic steels and nickel based alloys. Many components are being welded in the construction stage or may later on have to be repaired by welding. The design of components also often calls for joining or cladding of dissimilar materials to optimize the use of the material properties and for economical reasons to reduce the amount of expensive materials. Consumables and procedures have been developed to give weld metals to match the corrosion and strength requirements of the materials. There is a wide selection of MM electrodes with different coatings available and new types of stainless flux cored wires are being introduced. Especially for cladding of large surfaces the submerged arc strip cladding process offer high productivity solutions. (Author) 6 ref.

  11. Contaminated nickel scrap processing

    International Nuclear Information System (INIS)

    The DOE will soon choose between treating contaminated nickel scrap as a legacy waste and developing high-volume nickel decontamination processes. In addition to reducing the volume of legacy wastes, a decontamination process could make 200,000 tons of this strategic metal available for domestic use. Contaminants in DOE nickel scrap include 234Th, 234Pa, 137Cs, 239Pu (trace), 60Co, U, 99Tc, and 237Np (trace). This report reviews several industrial-scale processes -- electrorefining, electrowinning, vapormetallurgy, and leaching -- used for the purification of nickel. Conventional nickel electrolysis processes are particularly attractive because they use side-stream purification of process solutions to improve the purity of nickel metal. Additionally, nickel purification by electrolysis is effective in a variety of electrolyte systems, including sulfate, chloride, and nitrate. Conventional electrorefining processes typically use a mixed electrolyte which includes sulfate, chloride, and borate. The use of an electrorefining or electrowinning system for scrap nickel recovery could be combined effectively with a variety of processes, including cementation, solvent extraction, ion exchange, complex-formation, and surface sorption, developed for uranium and transuranic purification. Selected processes were reviewed and evaluated for use in nickel side-stream purification. 80 refs

  12. Study of superficial films and of electrochemical behaviour of some nickel base alloys and titanium base alloys in solution representation of granitic, argillaceous and salted ground waters

    International Nuclear Information System (INIS)

    The corrosion behaviour of the stainless steels 304, 316 Ti, 25Cr-20Ni-Mo-Ti, nickel base alloys Hastelloy C4, Inconel 625, Incoloy 800, Ti and Ti-0.2% Pd alloy has been studied in the aerated or deaerated solutions at 200C and 900C whose compositions are representative of interstitial ground waters: granitic or clay waters or salt brine. The electrochemical techniques used are voltametry, polarization resistance and complexe impedance measurements. Electrochemical data show the respective influence of the parameters such as temperature, solution composition and dissolved oxygen, addition of soluble species chloride, fluoride, sulfide and carbonates, on which depend the corrosion current density, the passivation and the pitting potential. The inhibition efficiency of carbonate and bicarbonate activities against pitting corrosion is determined. In clay water at 900C, Ti and Ti-Pd show very high passivation aptitude and a broad passive potential range. Alloying Pd increases cathodic overpotential and also transpassive potential. It makes the alloy less sensitive to the temperature effect. Optical Glow Discharge Spectra show three parts in the composition depth profiles of surface films on alloys. XPS and SIMS spectrometry analyses are also carried out. Electron microscopy observation shows that passive films formed on Ti and Ti-Pd alloy have amorphous structure. Analysis of the alloy constituents dissolved in solutions, by radioactivation in neutrons, gives the order of magnitude of the Ni base alloy corrosion rates in various media. It also points out the preferential dissolution of alloying iron and in certain cases of chromium

  13. Microfibrous nickel substrates and electrodes for battery system applications

    Science.gov (United States)

    Zhu, Wenhua H.; Durben, Peter J.; Tatarchuk, Bruce J.

    The use of microfibrous nickel substrates is advantageous for increasing the surface area available for the deposition of active material and reducing the substrate weight and consequently, yields a higher specific capacity for nickel hydroxide electrodes. Porous, microfiber-based nickel substrates were produced by sintering a composite preform. The preforms, consisting of nickel fibers with diameters as small as 2 μm and cellulose fibers, were formed using a papermaking process. The fabricated nickel electrodes that included a supporting nickel mesh in the substrate tested in a 26% KOH half-cell delivered a specific capacity of more than 250 mAh/g of the electrode weight (i.e. fibrous substrate, nickel mesh, and active material) at a 1.0 C discharge rate. An Auburn electrode without a nickel mesh tested in the same half-cell attained a higher specific capacity of 268 mAh/g at a 1.37 C discharge rate. The substrates used in these electrodes had porosities of 95-97%, and greatly improved the specific capacity of the nickel electrode. With the use of the microfibrous electrode, improved specific energies of nickel-based cell and battery designs are possible. When assembled in a nickel-hydrogen (Ni-H 2) boilerplate cell, the specific capacity of nearly 230 mAh/g was observed for the nickel electrode at a 0.5 C rate during the 127th cycle test. The results of high specific capacity and quick rise in utilization of microfibrous nickel hydroxide electrodes make these electrodes good candidates for significantly improving the energy density and performance of nickel-hydrogen cells.

  14. Surface Characterization and Mechanical Properties' Evaluation of Boride-Dispersed Nickel-Based Coatings Deposited on Copper Through Thermal Spray Routes

    Science.gov (United States)

    Sharma, Prashant; Majumdar, Jyotsna Dutta

    2012-09-01

    The present study concerns understanding the microstructures and wear resistance of nickel-based alloy (Ni 68.4, Cr 17, B 3.9, Si 4.9, and Fe 5.8) coatings on copper developed by flame spraying and high-velocity oxy-fuel (HVOF) coating techniques. The microstructure of flame spray deposition consists of predominantly equiaxed γ-Ni grains, refined Ni3B precipitates, and Ni2.9Cr0.7Fe0.36 phase. On the other hand, HVOF spray deposition reduces the porosity content significantly in the presence of very fine (with average precipitate size varying from μm to nm range) borides (chromium boride, Cr2B; and nickel boride, Ni3B) in γ-Ni matrix. The microhardness of the HVOF-sprayed and flame-sprayed surfaces were improved to 935 VHN and 251 VHN, respectively as compared with 82 VHN of the as-received substrate. Wear resistance property against WC indenter was also improved in deposited layers with a maximum improvement in HVOF spray deposition. The mechanism of wear was investigated.

  15. Quantitative experimental determination of the solid solution hardening potential of rhenium, tungsten and molybdenum in single-crystal nickel-based superalloys

    International Nuclear Information System (INIS)

    The solid-solution hardening potential of the refractory elements rhenium, tungsten and molybdenum in the matrix of single-crystal nickel-based superalloys was experimentally quantified. Single-phase alloys with the composition of the nickel solid-solution matrix of superalloys were cast as single crystals, and tested in creep at 980 °C and 30–75 MPa. The use of single-phase single-crystalline material ensures very clean data because no grain boundary or particle strengthening effects interfere with the solid-solution hardening. This makes it possible to quantify the amount of rhenium, tungsten and molybdenum necessary to reduce the creep rate by a factor of 10. Rhenium is more than two times more effective for matrix strengthening than either tungsten or molybdenum. The existence of rhenium clusters as a possible reason for the strong strengthening effect is excluded as a result of atom probe tomography measurements. If the partitioning coefficient of rhenium, tungsten and molybdenum between the γ matrix and the γ′ precipitates is taken into account, the effectiveness of the alloying elements in two-phase superalloys can be calculated and the rhenium effect can be explained

  16. Iron (III Ion Sensor Based on the Seedless Grown ZnO Nanorods in 3 Dimensions Using Nickel Foam Substrate

    Directory of Open Access Journals (Sweden)

    Mazhar Ali Abbasi

    2013-01-01

    Full Text Available In the present work, the seedless, highly aligned and vertical ZnO nanorods in 3 dimensions (3D were grown on the nickel foam substrate. The seedless grown ZnO nanorods were characterised by field emission scanning electron microscopy (FESEM, high resolution transmission electron microscopy (HRTEM, and X-ray diffraction (XRD techniques. The characterised seedless ZnO nanorods in 3D on nickel foam were highly dense, perpendicular to substrate, grown along the (002 crystal plane, and also composed of single crystal. In addition to this, these seedless ZnO nanorods were functionalized with trans-dinitro-dibenzo-18-6 crown ether, a selective iron (III ion ionophore, along with other components of membrane composition such as polyvinyl chloride (PVC, 2-nitopentylphenyl ether as plasticizer (NPPE, and tetrabutyl ammonium tetraphenylborate (TBATPB as conductivity increaser. The sensor electrode has shown high linearity with a wide range of detection of iron (III ion concentrations from 0.005 mM to 100 mM. The low limit of detection of the proposed ion selective electrode was found to be 0.001 mM. The proposed sensor also described high storage stability, selectivity, reproducibility, and repeatability and a quick response time of less than 10 s.

  17. Performance improvement of pasted nickel electrodes with multi-wall carbon nanotubes for rechargeable nickel batteries

    International Nuclear Information System (INIS)

    Carbon nanotubes (CNTs) were employed as a functional additive to improve the electrochemical performance of pasted nickel-foam electrodes for rechargeable nickel-based batteries. The nickel electrodes were prepared with spherical β-Ni(OH)2 powder as the active material and various amounts of CNTs as additives. Galvanostatic charge/discharge cycling tests showed that in comparison with the electrode without CNTs, the pasted nickel electrode with added CNTs exhibited better electrochemical properties in the chargeability, specific discharge capacity, active material utilization, discharge voltage, high-rate capability and cycling stability. Meanwhile, the CNT addition also lowered the packing density of Ni(OH)2 particles in the three-dimensional porous nickel-foam substrate, which could lead to the decrease in the active material loading and discharge capacity of the electrode. Hence, the amount of CNTs added to Ni(OH)2 should be optimized to obtain a high-performance nickel electrode, and an optimum amount of CNT addition was found to be 3 wt.%. The superior electrochemical performance of the nickel electrode with CNTs could be attributed to lower electrochemical impedance and less γ-NiOOH formed during charge/discharge cycling, as indicated by electrochemical impedance spectroscopy and X-ray diffraction analyses. Thus, it was an effective method to improve the electrochemical properties of pasted nickel electrodes by adding an appropriate amount of CNTs to spherical Ni(OH)2 as the active material

  18. Intergranular tellurium cracking of nickel-based alloys in molten Li, Be, Th, U/F salt mixture

    Science.gov (United States)

    Ignatiev, Victor; Surenkov, Alexander; Gnidoy, Ivan; Kulakov, Alexander; Uglov, Vadim; Vasiliev, Alexander; Presniakov, Mikhail

    2013-09-01

    In Russia, R&D on Molten Salt Reactor (MSR) are concentrated now on fast/intermediate spectrum concepts which were recognized as long term alternative to solid fueled fast reactors due to their attractive features: strong negative feedback coefficients, easy in-service inspection, and simplified fuel cycle. For high-temperature MSR corrosion of the metallic container alloy in primary circuit is the primary concern. Key problem receiving current attention include surface fissures in Ni-based alloys probably arising from fission product tellurium attack. This paper summarizes results of corrosion tests conducted recently to study effect of oxidation state in selected fuel salt on tellurium attack and to develop means of controlling tellurium cracking in the special Ni-based alloys recently developed for molten salt actinide recycler and tranforming (MOSART) system. Tellurium corrosion of Ni-based alloys was tested at temperatures up to 750 °C in stressed and unloaded conditions in molten LiF-BeF2 salt mixture fueled by about 20 mol% of ThF4 and 2 mol% of UF4 at different [U(IV)]/[U(III)] ratios: 0.7, 4, 20, 100 and 500. Following Ni-based alloys (in mass%): HN80М-VI (Mo—12, Cr—7.6, Nb—1.5), HN80МТY (Mo—13, Cr—6.8, Al—1.1, Ti—0.9), HN80МТW (Mo—9.4, Cr—7.0, Ti—1.7, W—5.5) and ЕМ-721 (W—25.2, Cr—5.7, Ti—0.17) were used for the study in the corrosion facility. If the redox state the fuel salt is characterized by uranium ratio [U(IV)]/[U(III)] construction alloys and carbon, are formed. In the melt with [U(IV)]/[U(III)] = 500 in all of the alloys tested the tellurium IGC took place. The HN80MTY alloy shows the maximum resistance to tellurium IGC. The intensity of tellurium IGC of the alloy (the K parameter) is by 3-5 times lower as compared to other alloys. The EM-721 alloy has the minimal resistance to tellurium IGC (K = 9200 pc m/cm, the depth of cracks is up to 434 μm). The studies have shown, that the intensity of the nickel alloys

  19. Potentials of manufacture and repair of nickel base turbine components used in aero engines and power plants by laser metal deposition and laser drilling

    Institute of Scientific and Technical Information of China (English)

    I.Kelbassa; K.Walther; L.Trippe; W.Meiners; C.Over

    2007-01-01

    High pressure turbine (HPT) parts like blades and vanes with integrated cooling channels are challenging concerning overhaul and repair.So far damaged parts have to be replaced by the operator.The aim is to design and implement a refurbishment process chain to avoid scrapping of used parts.This process chain implies three different laser applications 1.Direct Laser Forming (DLF),2.Laser Metal Deposition (LMD) and 3.Laser Drilling (LD).The laser processing was extended in the last years towards application near materials like Nickel and Titanium base alloys.Concerning LMD and DLF the achieved results are investigated regarding macro and micro structure,hardness,defects (e.g.cracks,bonding defects,porosity) and contamination with atmospheric elements (e.g.O, N,C and H) are presented for Titanium alloys like Ti-6Al-4V,Ti-6246 and Ti-17 as well as for Nickel base alloys like Inconel 718 and Rene 80.Suitable process parameters are presented with the achieved static (tensile) and dynamic mechanical properties (HCF) and compared to those of heat treated raw materials.One innovative solution (manufacturing case) is to fabricate the small and complex shaped geometrical elements by LMD and/or DLF.By LMD these elements are built-up directly.With DLF the elements are manufactured separately in the DLF machine and connected by a subsequent joining technique with the large parts.With DLF small complex shaped parts like combustor swirlers,HPT blades and vanes with internal cooling channels are manufactured completely.LMD and DLF can be used in combination with subsequent LD.Depending on the application two different drilling techniques by dominant melt ejection-percussion drilling and trepanning-are classified and characterised.The drilling techniques are exemplarily presented for stainless steel and nickel base alloys (diameter 0.2~0.6 mm,aspect ratio<30,inclination up to 60°) using pulsed laser radiation (Nd:YAG,1064 nm,0.5~1 ms).The experimental results of coaxial

  20. Intégration des alliages d'aluminium dans le câblage électrique automobile : procédés de mise en forme, microstructure et durabilité

    OpenAIRE

    Laurino, Adrien

    2012-01-01

    Cette thèse s'inscrit dans un programme de développement technologique de la Société LEONI. Ce programme de recherche a pour principal objectif de disposer, à l'issue des trois années de l'étude, d'un panel de connaissances scientifiques le plus pertinent possible sur la durabilité des alliages d'aluminium dans des environnements caractéristiques d'un faisceau électrique automobile. Il s'agit, à terme, d'intégrer, à l'échelle industrielle, l'aluminium ou l'un de ses alliages dans les câblages...

  1. Evolution de l'état de précipitation dans un alliage Al-Zn-Mg lors de traitements thermiques anisothermes et dans la zone affectée thermiquement de joints soudés

    OpenAIRE

    Nicolas, Myriam

    2002-01-01

    Le soudage des alliages Al-Zn-Mg est de plus en plus utilisé dans l'industrie du transport. Les variations brutales de température induites par le soudage à l'arc provoquent des modifications importantes de la microstructure dans la zone dite affectée thermiquement.Cette étude porte sur l'évolution de la précipitation suite à ce procédé de l'alliage 7108.50 présentant différentes microstructures initiales. Une caractérisation fine des précipités durcissants dans la zone affectée thermiquement...

  2. Colorimetric Humidity and Solvent Recognition Based on a Cation-Exchange Clay Mineral Incorporating Nickel(II)-Chelate Complexes.

    Science.gov (United States)

    Hosokawa, Hitoshi; Mochida, Tomoyuki

    2015-12-01

    Solvatochromic nickel(II) complexes with diketonato and diamine ligands were incorporated into a saponite clay by ion exchange, and their colorimetric humidity- and solvent-recognition properties were investigated. These powders exhibit color change from red to blue-green depending on humidity, and the detection range can be controlled by modifying the metal complex. The humidity response takes advantage of the humidity-dependent water content in clay and the coordination of water molecules to the metal complex in equilibrium. The addition of organic solvents to the powders causes a color change to occur, varying from red to blue-green depending on the donor number of the solvent, thereby enabling solvent recognition. In the clay, the affinity of less sterically hindered complexes to water or solvent molecules is decreased compared with that in solution because the cationic complexes interact with the anionic layers in the clay. Incorporating diethylene glycol into the materials produced thermochromic powders. PMID:26542108

  3. Surface modification by sulfated zirconia on high-capacity nickel-based cathode materials for Li-ion batteries

    International Nuclear Information System (INIS)

    Highlights: • Sulfated zirconia is successfully synthesized and uniformly coated onto a nickel-rich layered lithium oxide. • The electrochemical properties of the sulfated-zirconia-coated LiNi0.8Co0.1Mn0.1O2 electrode are greatly improved. • Sulfated zirconia coating is effective in reducing side reactions between the active materials and electrolyte. • Sulfated zirconia coating contributes to forming a more stable solid electrolyte interphase layer on the cathode surface. - ABSTRACT: Sulfated zirconia was successfully synthesized and uniformly coated onto a nickel-rich layered lithium oxide (LiNi0.8Co0.1Mn0.1O2), and investigated with a view to its potential use as a cathode material in Li-ion batteries. The uniformity of this sulfated zirconia coating was confirmed through electron microscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy. Furthermore, the electrochemical properties of the sulfated-zirconia-coated LiNi0.8Co0.1Mn0.1O2 electrode were found to be greatly improved compared to those of pristine LiNi0.8Co0.1Mn0.1O2 and zirconia-coated LiNi0.8Co0.1Mn0.1O2, especially at elevated temperature (60 °C). These results are directly attributed to the sulfated zirconia coating, which is effective in reducing side reactions by preventing direct contact between the active materials and electrolyte solutions, as well as forming a more stable solid electrolyte interphase (SEI) layer on the active material surface

  4. Facile synthesis of Co{sub 2}P via the reduction of phosphate with KBH{sub 4} for nickel-based rechargeable batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yaping [School of Material Science and Engineering, Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang 212013 (China); Wang, Yijing, E-mail: wangyj@nankai.edu.cn [Institute of New Energy Material Chemistry, The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Key Laboratory of Advanced Energy Materials Chemistry (MOE), Nankai University, Tianjin 300071 (China); Li, Huanhuan, E-mail: lihh@mail.ujs.edu.cn [Automotive Engineering Research Institute, Jiangsu University, Zhenjiang 212013 (China); Liu, Zongtao; Zhang, Lili [School of Material Science and Engineering, Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang 212013 (China); Jiang, Haobin [Automotive Engineering Research Institute, Jiangsu University, Zhenjiang 212013 (China); Zhou, Ming; Li, Baojia [School of Material Science and Engineering, Center for Photon Manufacturing Science and Technology, Jiangsu University, Zhenjiang 212013 (China); Ren, Naifei [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-02-25

    Highlights: • We report a new way to prepare Co{sub 2}P for nickel-based rechargeable batteries. • The reversible discharge capacity of Co{sub 2}P is about 244 mAh g{sup −1}. • Co{sub 2}P exhibits attractive cycle stability and rate capability. - Abstract: Crystalline Co{sub 2}P is synthesized via a green and effective method based on the reduction of phosphate with KBH{sub 4}. Various analytical techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy-dispersive spectroscopy instrument are employed to characterize the obtained Co{sub 2}P. Moreover, it is electrochemically used as an anode material for nickel-based rechargeable batteries and compared with amorphous Co–P prepared by chemical reduction. Co{sub 2}P electrode presents superior electrochemical properties such as discharge capacities, cycle stability, and rate capability to Co–P electrode. The reversible discharge capacity of Co{sub 2}P electrode is about 244.1 mAh g{sup −1} at 100 mA g{sup −1} which can be retained after 200 cycles. Co{sub 2}P electrode also shows promising high rate performance. Furthermore, cyclic voltammogram illustrates that the reversible electrochemical capacity of Co{sub 2}P electrode is attributed to the redox of Co/Co(OH){sub 2}. Electrochemical impedance spectroscopy displays that the charge transfer resistance of Co{sub 2}P electrode is smaller than that of Co–P electrode.

  5. Modélisation thermodynamique du comportement cyclique d'alliages à mémoire de forme TiNi et CuZnAl sollicités en traction ondulée

    OpenAIRE

    Bourbon, G.; Lexcellent, C.

    1994-01-01

    L'extension au cas cyclique, d'un modèle de comportement pseudoélastique d'alliages à mémoire de forme (A.M.F.), mis au point par Raniecki, Lexcellent et Tanaka, ne pose pas de problème. La forme des boucles d'hystérésis permet une identification plus fiable des paramètres thermodynamiques pour le Ti Ni que pour le Cu Zn Al.

  6. Hot gas corrosion and creep strength of a nickel base alloy in close-to-operating conditions at 750 to 9500C

    International Nuclear Information System (INIS)

    Creep rupture tests of the nickel base alloy Rene-41 in JP4 hot gas steam and in air atmosphere show a significant decrease in the creep strength. Dotations of the hot gas with synthetic sea salt cause a more extensive decrease of the creep strength. Metallographic, scanning electron microscopic and microanalytical investigations yield comparable structure conditions and protective layer configurations under the stress of air and exhaustion gas atmosphere. The creep behaviour shows characterizing dependence of the surrounding medium. Within corrosive atmosphere there is no stationary region at the creep curves. Components of the power fuel diffuse into the material and cause ductile grain boundery coverings, which cause premature break of the material. By means of Auger microanalysis increased concentrations of sulphur could be proved in regions close to the surface. (orig.)

  7. Development of a high-sensitivity plasticizer sensor based on a quartz crystal microbalance modified with a nanostructured nickel hydroxide film

    International Nuclear Information System (INIS)

    Nanostructured nickel hydroxide (nano-Ni(OH)2) was synthesized at a low temperature without annealing. Accordingly, a plasticizer sensor based on a quartz crystal microbalance (QCM) modified with the nano-Ni(OH)2 sensing film was fabricated to detect dibutyl phthalate (DBP) and its relative film thickness was optimized. The sensor worked at room temperature and exhibited a high sensitivity of 4.91 Hz ppb−1 to DBP in a low concentration range of 5–20 ppb, and an ultra-low detection limit of 5 ppb was achieved. In addition, the sensor maintained good repeatability as well as stability shown by the experimental data. The responses to five possible interferences and four other plasticizers were also measured, which indicated the excellent selectivity of the sensor and its potential use in monitoring plasticizers in a gaseous state. (paper)

  8. The effect of heat treatment on the micro-structure and the mechanical properties of high-temperature nickel-base-superalloys

    International Nuclear Information System (INIS)

    General review of heat treatment applied to high-temperature nickel-base-superalloys as a function of the volume percent of the γ'-phase. Heat treatment schedule. γ'-morphology and γ'-distribution as well as their effect on mechanical properties. Values obtained from tensile tests up to 1,0000C. Results obtained from creep tests. Limitation for the heat treatment of alloys having an unstable γ'-phase. Alloys X 5 NiCrTi 26 15, ATS 270 (approximately INCO 718), NiCr 20 TiAl, NiCr 20 Co 18 Ti, ATS 342 (approximately Waspaloy), ATS 354 (approximately Udimet 520), NiCo 20 Cr 15 MoAlTi, ATS 382 (approximately Udimet 710), ATS 381-G (approximately Mar M 246), FIS 145 and ATS 391-G (aproximately IN 100). (orig.)

  9. Influence of grain size and heat treatment on the microstructure and mechanical properties of the nickel-base superalloy U 720 LI

    Energy Technology Data Exchange (ETDEWEB)

    Torster, F.; Baumeister, G.; Albrecht, J.; Luetjering, G. [Technische Univ. Hamburg-Harburg, Hamburg (Germany); Helm, D.; Daeubler, M.A. [MTU Motoren- und Turbinen Union Muenchen GmbH, Muenchen (Germany)

    1997-08-30

    The purpose of the current investigation was to develop an optimized balance between creep resistance and LCF-strength of U 720 LI, a high-strength nickel-base superalloy. While a fine grain size is beneficial for improved LCF-strength, it is detrimental to high-temperature creep resistance. Therefore, microstructures with medium grain sizes in the range of 50-150 {mu}m were produced by appropriate recrystallization treatments. The coarse grain size showed improved creep resistance and lower yield stress as well as a tendency for lower LCF-strength. By increasing the amount of fine {gamma}`-precipitates by modified aging treatments, it was possible to increase the yield stress considerably with a concomitant increase in creep strength. (orig.) 4 refs.

  10. Effect of minor carbon additions on the high-temperature creep behavior of a single-crystal nickel-based superalloy

    International Nuclear Information System (INIS)

    Different amounts of carbon were added to a single-crystal nickel-based superalloy. The microstructural evolution of these alloys before and after high-temperature creep tests was investigated by employing scanning electron microscopy and transmission electron microscopy. Upon increasing the carbon contents, the volume fraction and diameter of the carbides increased gradually: however, the creep lives of the alloys increased slightly at first and subsequently decreased. The formation of second-phase particles, such as the nano-sized M23C6, blocky and needle-shaped μ phase, was observed in the creep samples, which was closely related to the high-temperature creep behaviors. - Highlights: • Creep behaviors of alloys with different amounts of carbon were investigated. • The creep rupture lives increased and later decreased with more carbon. • Second-phase particles were responsible for the different creep behaviors

  11. Synthesis and characterization of binder-free Cr3C2 coatings on nickel-based alloys for molten fluoride salt corrosion resistance

    Science.gov (United States)

    Brupbacher, Michael C.; Zhang, Dajie; Buchta, William M.; Graybeal, Mark L.; Rhim, Yo-Rhin; Nagle, Dennis C.; Spicer, James B.

    2015-06-01

    Under various conditions, chromium carbides appear to be relatively stable in the presence of molten fluoride salts and this suggests that their use in corrosion resistant coatings for fluoride salt environments could be beneficial. One method for producing these coatings is the carburization of sprayed Cr coatings using methane-containing gaseous precursors. This process has been investigated for the synthesis of binder-free chromium carbide coatings on nickel-based alloy substrates for molten fluoride salt corrosion resistance. The effects of the carburization process on coating microstructure have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS). Both plasma-sprayed and cold-sprayed Cr coatings have been successfully converted to Cr3C2, with the mechanism of conversion being strongly influenced by the initial porosity in the as-deposited coatings.

  12. Synthesis and characterization of binder-free Cr3C2 coatings on nickel-based alloys for molten fluoride salt corrosion resistance

    International Nuclear Information System (INIS)

    Under various conditions, chromium carbides appear to be relatively stable in the presence of molten fluoride salts and this suggests that their use in corrosion resistant coatings for fluoride salt environments could be beneficial. One method for producing these coatings is the carburization of sprayed Cr coatings using methane-containing gaseous precursors. This process has been investigated for the synthesis of binder-free chromium carbide coatings on nickel-based alloy substrates for molten fluoride salt corrosion resistance. The effects of the carburization process on coating microstructure have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS). Both plasma-sprayed and cold-sprayed Cr coatings have been successfully converted to Cr3C2, with the mechanism of conversion being strongly influenced by the initial porosity in the as-deposited coatings

  13. Synthesis and characterization of binder-free Cr{sub 3}C{sub 2} coatings on nickel-based alloys for molten fluoride salt corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Brupbacher, Michael C.; Zhang, Dajie [Department of Materials Science and Engineering, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Buchta, William M. [The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Graybeal, Mark L. [U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Rhim, Yo-Rhin [The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Nagle, Dennis C. [Department of Materials Science and Engineering, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Spicer, James B., E-mail: spicer@jhu.edu [Department of Materials Science and Engineering, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)

    2015-06-15

    Under various conditions, chromium carbides appear to be relatively stable in the presence of molten fluoride salts and this suggests that their use in corrosion resistant coatings for fluoride salt environments could be beneficial. One method for producing these coatings is the carburization of sprayed Cr coatings using methane-containing gaseous precursors. This process has been investigated for the synthesis of binder-free chromium carbide coatings on nickel-based alloy substrates for molten fluoride salt corrosion resistance. The effects of the carburization process on coating microstructure have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS). Both plasma-sprayed and cold-sprayed Cr coatings have been successfully converted to Cr{sub 3}C{sub 2}, with the mechanism of conversion being strongly influenced by the initial porosity in the as-deposited coatings.

  14. Effects of sol-gel method and lanthanum addition on catalytic performances of nickel-based catalysts for methane reforming with carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    LI Xiancai; HU Quanhong; YANG Yifeng; CHEN Juanrong; LAI Zhihua

    2008-01-01

    The nickel-based catalysts were prepared by the sol-gel method and used for the CH4 reforming with CO2. The effects of the sol-gel method on the specific surface area, catalytic activity, desorption, and reduction performances of catalysts were investigated with BET, TPR, and TPD. Compared with the catalyst prepared by the impregnation method, the results indicated that the catalysts prepared by the sol-gel method had larger specific surface area, showing higher catalytic activities and exhibiting perfect desorption and reduction per-formances. In addition, the modification effects of adding La were studied, and it was found that the 0.75NLBT catalyst constituted of 5wt.%Ni-0.75wt.%La was optimal.

  15. MÉCANISMES DE FORMATION ET DE DESTRUCTION DE LA COUCHE D'OXYDE SUR UN ALLIAGE CHROMINOFORMEUR EN MILIEU HTR

    OpenAIRE

    Rouillard, Fabien

    2007-01-01

    Le superalliage à 22%mas. en chrome, Haynes 230®, est un matériau candidat pour les échangeurs de chaleur (température maximale 850°C-950°C) des Réacteurs à Caloporteur Gaz, également appelés HTRs (High Temperature Reactors). Dans l'optique de valider les performances de cet alliage, il faut garantir sa résistance à la corrosion dans l'environnement d'hélium impur de ces réacteurs. Dans cet objectif, la réactivité de surface de l'Haynes 230® a été examinée à des températures comprises entre 8...

  16. Alliage antiferromagnétique MnPt : croissance, propriétés magnétiques et structurales

    OpenAIRE

    Borme, Jérôme

    2006-01-01

    La croissance par épitaxie par jets moléculaires de bicouches MnPt/Pt (100) a été étudiée. L'alliage MnPt, de structure chimiquement ordonnée L10 , a été élaboré par codépôt et par dépôt couche par couche. Le codépôt conduit à une structure bivariée d'axes d'anisotropie dans le plan de la couche. Le dépôt couche par couche conduit à une orientation préférentielle de l'axe d'anisotropie perpendiculaire à la couche. La structure magnétique de ces deux types de dépôts a été caractérisée. Des bic...

  17. Effects of Preparation Methods on Nickel-Based Catalysts%制备方法对镍系催化剂的影响

    Institute of Scientific and Technical Information of China (English)

    王丹; 周清华; 王冰; 张文成

    2015-01-01

    Nickel-based catalysts were prepared through conventional impregnation,conventional deposition,hydrothermal impregnation and hydrothermal deposition separately,and were characterized by means of XRD,H2-TPR,UV-Vis DRS and HR-TEM. The nickel-based catalyst prepared through the hydrothermal deposition had suitable NiO particle size and high NiO dispersity on the catalyst surface. The hydrogenation activities of the catalysts were evaluated using octanol with 5.4%(w) octenal as feedstock. The evaluation results indicated that the nickel-based catalyst prepared by the hydrothermal deposition method had higher hydrogenation activity. The nickel catalyst prepared by the hydrothermal deposition method was evaluated with industrial octanol with 13.7%(w) octenal as feedstock for 500 h. Under the conditions of H2 pressure 3.0 MPa,reaction temperature 120℃, LHSV 1.0 h-1 and volume ratio of hydrogen to oil 300∶1,the octenal conversion reached more than 99.9% and the selectivity to octanol was between 91.1%-92.4%. The catalyst has good stability.%分别采用常规浸渍法、常规共沉淀法、水热浸渍法、水热沉积法制备了Ni/Al2O3催化剂,并对催化剂进行了XRD, H2-TPR,UV-Vis DRS,HR-TEM表征;采用辛烯醛含量为5.42%(w)的辛醇原料对4种催化剂的加氢活性进行了评价;以辛烯醛含量为13.7%(w)的工业辛醇为原料对水热沉积法制备的催化剂进行500 h稳定性的考察。表征结果显示,水热沉积法制备的催化剂表面NiO粒子大小适宜,促进了NiO在催化剂表面的高度分散。加氢活性评价结果表明,水热沉积法制备的催化剂具有较高的活性。稳定性实验结果表明,在H2压力3.0 MPa、反应温度120℃、液态空速1.0 h-1、H2与原料的体积比300∶1的条件下,辛烯醛转化率大于99.9%,辛醇选择性为91.1%~92.4%,该催化剂具有较高的稳定性。

  18. A Simple Spectrofluorimetric Method Based on Quenching of a Nickel(II)-Phthalocyanine Complex to Determine Iron (III).

    Science.gov (United States)

    Çağlar, Yasemin; Saka, Ece Tuğba; Alp, Hakan; Kantekin, Halit; Ocak, Ümmühan; Ocak, Miraç

    2016-07-01

    A new nickel(II)-phthalocyanine complex (NiPc) was synthesized and used as a fluorescent ligand in determination of iron in real samples. The NiPc compound, when excited at 350 nm, decreases of emission with increases of the iron(III) concentration at 425 nm were used analytical response in a modified standard addition method. The method was validated by analyzing two certified reference materials (CRM-SA-C Sandy Soil C and Mixed Polish Herbs (INCT-MPH-2). Food and drug samples were digested in a closed microwave system using nitric acid and hydrogen peroxide. Therefore, all iron in the samples converted to iron(III) ion. These solutions were used directly in determination of iron(III) ion. No cleanup or enrichment of the solutions was required. The calibration graph was linear until 14.00 μg mL(-1). Detection limit and quantification limit were 1.29 μg mL(-1) and 3.88 μg mL(-1), respectively. The method provided accurate results for the majority of the food samples tested, including spanich, dill, mint, purslane, rocket, red lentils, dry beans and two iron medicinal tablets. Also, the high recovery (95.6 %) was obtained for a fortified stream water sample. The simple and cost-effective method is suitable for monitoring total iron concentration in foods and drug samples. PMID:27256284

  19. The role of intergranular chromium carbides on intergranular oxidation of nickel based alloys in pressurized water reactors primary water

    Science.gov (United States)

    Gaslain, F. O. M.; Le, H. T.; Duhamel, C.; Guerre, C.; Laghoutaris, P.

    2016-02-01

    Alloy 600 is used in pressurized water reactors (PWRs) but is susceptible to primary water stress corrosion cracking (PWSCC). Intergranular chromium carbides have been found beneficial to reduce PWSCC. Focussed ion beam coupled with scanning electron microscopy (FIB/SEM) 3D tomography has been used to reconstruct the morphology of grain boundary oxide penetrations and their interaction with intergranular Cr carbides in Alloy 600 subjected to a PWR environment. In presence of intergranular Cr carbides, the intergranular oxide penetrations are less deep but larger than without carbide. However, the intergranular oxide volumes normalized by the grain boundary length for both samples are similar, which suggest that intergranular oxidation growth rate is not affected by carbides. Analytical transmission electron microscopy (TEM) shows that the intergranular oxide consists mainly in a spinel-type oxide containing nickel and chromium, except in the vicinity of Cr carbides where Cr2O3 was evidenced. The formation of chromium oxide may explain the lower intergranular oxide depth observed in grain boundaries containing Cr carbides.

  20. Glow Discharge Plasma-Assisted Preparation of Nickel-Based Catalyst for Carbon Dioxide Reforming of Methane

    Institute of Scientific and Technical Information of China (English)

    Fang Guo; Wei Chu; Jun-qiang Xu; Lin Zhong

    2008-01-01

    A plasma-assisted method was employed to prepare Ni/γ-Al2O3 catalyst for carbon dioxide reforming of methane reaction. The novel catalyst possessed higher activity and better coke-suppression performance than those of the conventional calcination catalyst. To achieve the same CH4 conversion, the conventional catalyst needed higher reaction temperature, about 50 ℃ higher than that of the N2 plasma-treated catalyst.After the evaluation test, the deactivation rate of the novel catalyst was 1.7%, compared with 15.2% for the conventional catalyst. Different from the characterization results of the calcined catalyst, a smaller average pore diameter and a higher specific surface area were obtained for the plasma-treated catalyst.The variations of the reduction peak temperatures and areas indicated that the catalyst reducibility was promoted by plasma assistance. The dispersion of nickel was also remarkably improved, which was helpful for controlling the ensemble size of metal atoms on the catalyst surface. The modification effect of plasmaassisted preparation on the surface property of alumina supported catalyst was speculated to account for the concentration increase of absorbed CO2. An enhancement of CO2 adsorption was propitious to the inhibition of carbon formation. The coke amount deposited on plasma treated catalyst was much smaller than that on the conventional catalyst.