WorldWideScience

Sample records for biocomposants pour carburants

  1. Synthetic Or Reformulated Fuels: a Challenge for Catalysis Carburants de synthèse ou reformulés : un défi pour la catalyse

    Directory of Open Access Journals (Sweden)

    Courty P.

    2006-12-01

    que les investissements requis soient lourds, notamment pour la production du gaz de synthèse. Les principaux défis, et les voies de progrès correspondantes concernant les catalyseurs et les technologies, sont présentés pour la synthèse Fischer-Tropsch et la reformulation à long terme des carburants. Parmi d'autres, le contrôle de la croissance de chaîne (synthèse Fischer-Tropsch, l'amélioration des produits du FCC : essence et LCO pour le pool Diesel, constituent des défis majeurs pour lesquels des progrès importants en matière de catalyseur et de technologie sont attendus. Enfin, une étude économique ciblée sur la production de carburant Diesel met en lumière la presque identité des coûts de production du carburant Diesel reformulé (ex-mélanges GO de distillation directe et LCO, et du carburant Diesel ex-synthèse Fischer-Tropsch lorsque du gaz naturel à faible coût est disponible. Dans le futur, les distillats moyens ex-synthèse Fischer-Tropsch devraient représenter quelques pour-cent (5-150 Mt des 1700 à 2000 Mt de distillats moyens pour transports, attendus du raffinage. Toutefois, ils constitueront, à terme, une fraction obligatoire du pool carburant Diesel, dans la mesure où les coûts d'investissement de la technologie Fischer-Tropsch diminueront de façon significative.

  2. Accelerated Gas Carburizing (URX Gas Carburizing)

    Institute of Scientific and Technical Information of China (English)

    Yoshikazu Shimosato; Mamoru Kamitani; Hiroyuki Nakatsu

    2004-01-01

    URX gas carburizing is an accelerated gas carburizing method with 50% CO + 50% H2 gas which comes from CH4 gas + CO2 gas. By using this gas composition, the carburizing reaction rate increases to the maximum and the controllability of carbon potential improves. A carbon mass flow rate is the product of the carburizing reaction rate multiplied by the difference of carbon percent between carbon potential of the gas and the carbon content of the surface of treated steel parts. We have obtained excellent results from the experimental tests at our laboratory as mentioned bellow. 1)Carburizing time can be shortened by 40% for 0.5 - 0.9 mm effective case depth. 2) Uniform carburizing case depth 3) Less internal oxidation with the same case depth. We have already developed the new roller hearth type continuous carburizing furnace and the new URX gas generator.

  3. Fuel Penalty Comparison for (Electrically Heated Catalyst Technology Comparaison de l’augmentation de consommation de carburant pour la technologie de catalyseurs chauffés à l’électricité

    Directory of Open Access Journals (Sweden)

    Kessels J. T.B.A.

    2010-03-01

    Full Text Available The conversion efficiency of three way catalytic converters is mainly defined by the temperature range wherein they are operating. Traditionally, ignition retard has been used to reduce the light-off time of the catalyst. This is however associated with a fuel penalty. With increasing vehicle electrification, electrically heating facilities present an alternative, especially for hybrid vehicles. Nevertheless, system complexity of hybrid vehicles prevents engineers to evaluate possible heating technologies and their corresponding fuel penalty with respect to traditional solutions. This paper evaluates the application of an electrically heated catalyst on a hybrid vehicle equipped with a Natural Gas (NG engine. The effect of heating power on light-off time and fuel penalty is determined, using analysis techniques emerging from integrated powertrain control. By means of a case study, the importance of an integral approach is explained by comparing the fuel penalty and conversion efficiency improvement of electric heating with that of ignition retard. In this process, a mix of simulation and test data were combined, forming the foundations for future control developments of a suitable light-off strategy. L’efficacité de conversion des catalyseurs est principalement définie par la gamme de température dans laquelle ils fonctionnent. Un retard du point d’allumage a traditionnellement été utilisé pour réduire le temps d’amorçage du catalyseur. Ceci est cependant associé à une augmentation de la consommation de carburant. Avec l’électrification des véhicules, la possibilité de chauffage électrique représente véritablement une alternative, tout particulièrement pour les véhicules hybrides. Cependant, la complexité des véhicules hybrides rend difficile l’évaluation des technologies de chauffage éventuelles ainsi que l’augmentation de la consommation de carburant associée ; il est aussi difficile de comparer ces r

  4. Quality of carburizers and its influence on carburization process

    Directory of Open Access Journals (Sweden)

    K. Janerka

    2009-07-01

    Full Text Available In the papers issue of production the synthetic cast iron obtaining on the basis of only steel scrap and carburizing materials are presented. Natural graphite, synthetic graphite, anthracite, petroleum coke, foundry coke and charcoal were used to carburization. Examinations covered evaluation of used carburizers taking into account chemical composition; carbon, sulphur and nitrogen content have been analyzed. Obtained effectiveness of carburization with method of inserting carburizing material into charge in solid, were especially taken into considerations. The comparison between mechanical properties (tensile strength and hardness of produced synthetic cast iron and cast iron obtained on the basis of pig iron have been carried out.

  5. Acetylene Vacuum Carburizing

    Institute of Scientific and Technical Information of China (English)

    Hitoshi Iwata

    2004-01-01

    Almost 30 years has passed since the publication of materials on vacuum carburizing technology, and is attracting a great deal of attention as a technology capable of being used as a substitute for gas carburizing technology.However, the technology was not popular except in specific fields. The main reason for this is due to a variety of harmful influences accompanying the sooting problems caused by CH4 or C3H8. We have succeeded in that the occurrence of sooting was suppressed by utilizing acetylene, at extremely low pressure for carburizing (below 1 kPa). This process is now showing the excellent quality and prospects for this technology in terms of quality, economy and safety. At present almost 70 practical mass production furnaces are used in production lines, in Japan and abroad. At this time, we will report summary of the present acetylene vacuum carbufizing process and the actual results obtained by these acetylene vacuum carbufizing furnaces for mass production.

  6. The properties and structure of the carburizers

    Directory of Open Access Journals (Sweden)

    K. Janerka

    2010-01-01

    Full Text Available The results of examinations of the carburizers for foundry industry were presented in the article. The commonly used carburizers were selected for the experiments (anthracite, natural and synthetic graphite, petroleum coke of various grades, cupola coke and charcoal as well. The experiments consist of bulk and standard density, screen analysis (on the basis of it the equivalent diameter was calculated and the microstructure of the carburizers measurements. The chemical composition and basic properties of carburizers were described too.

  7. Effects of carburization time and temperature on the mechanical properties of carburized mild steel, using activated carbon as carburizer

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    Fatai Olufemi Aramide

    2009-01-01

    Full Text Available Due to the complexity of controlling parameters in carburization, there has been relatively little work on process variables during the surface hardening process. This work focuses on the effects of the carburizing temperature and time on the mechanical properties of mild steel carburized with activated carbon, at 850, 900 and 950 ºC, soaked at the carburizing temperature for 15 and 30 minutes, quenched in oil, tempered at 550 ºC and held for 60 minutes. Prior carburization process, standard test samples were prepared from the as received specimen for tensile and impact tests. After carburization process, the test samples were subjected to the standard test and from the data obtained, ultimate tensile strength, engineering strain, impact strength, Youngs' moduli were calculated. The case and core hardness of the carburized tempered samples were measured. It was observed that the mechanical properties of mild steels were found to be strongly influenced by the process of carburization, carburizing temperature and soaking time at carburizing temperature. It was concluded that the optimum combination of mechanical properties is achieved at the carburizing temperature of 900 ºC followed by oil quenching and tempering at 550 ºC.

  8. The rate and effectiveness of carburization to the sort of carburizer

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    K. Janerka

    2007-12-01

    Full Text Available The obtaining of demanded carbon contents during melting the cast iron with bounded pig iron’s portion is important problem for many foundries. There are searched the effective methods and carburizers, which would ensure obtaining of big carbon increases with great repeatability as quick as possible. The aim of presented researches was definition of influence of essential factors characterized the carburization and the sort of carburizer on the rate and effectiveness of process. The cast iron melts are presented only on the basis of steel scrap with the portion of graphitoidal, coke and anthracite carburizers. Two methods of carburization are taken into consideration during the experiments were carried out: the addition of carburizer to charge in solid in the initial period of melting and addition of carburizer on surface of liquid metal . The obtained researches results and their analyze allow to choose the corresponding method and the sort of carburizer. One can state, that the best carburizer is synthetic graphite, if the rate and effectiveness of process is considerate and the best method of carburization in the electric inductive furnace is addition of carburizer to charge in solid. In the subsequent part of researches the analyze of influence of carburizer on the structure of grey cast iron and ductile cast iron. The initial researches has showed the differences in obtained structures of synthetic cast iron melted only on the basis of steel scrap and defined kind of carburizer.

  9. Etude d'un procédé d'hydroliquéfaction du charbon pour la production simultanée de gaz et de carburant . . . . . Studies of a Coal Hydrogenation Process to Produce CO-Currently Gas and Gasoline

    Directory of Open Access Journals (Sweden)

    Franckowiak S.

    2006-11-01

    Full Text Available Un des principaux moyens de réintroduire le charbon dans le marché énergétique français est de le transformer en produits utiles comme le gaz de réseau ou les carburants. Les procédés d'oxyvapogazéification permettent d'obtenir un gaz de synthèse qui peut être ensuite converti en gaz riche ou en produits liquides. L'hydrogénation en phase liquide (ou hydroliquéfaction se présente pour le long terme comme une seconde voie qui offre des avantages spécifiques - taux de conversion du charbon et rendement élevés, - production directe de gaz de substitution (GNS et de carburant, - possibilité d'utilisation d'hydrogène provenant de l'électricité nucléaire. Un programme d'étude a été lancé avec la participation du Gaz de France (GDF, du Centre d'études et de recherches des Charbonnages de France (Cerchar, de l'institut Français du Pétrole (lFP et du Centre National de la Recherche Scientifique (CNRS dans le cadre du Groupe d'Étude de la Conversion du Charbon par Hydrogénation (GECH. Un banc d'essai d'hydroliquéfaction situé au Cerchar, d'un débit de 10 kg/h de mélange charbon-solvant, permet d'obtenir des hydrogénats dans des conditions variées et en présence de divers catalyseurs. L'étude de la valorisation de ces hydrogénats est effectuée dans les laboratoires de l'lFP. Les essais et les études effectués permettent d'envisager la production à volonté du GNS, de carburants ou des deux ensemble. Un modèle d'optimisation a été réalisé au GDF pour étudier et comparer les différentes filières en prenant en compte l'utilisation d'hydrogène d'électrolyse ou d'hydrogène produit sur place à partir du résidu de liquéfaction. One of the main ways to bring coal in the future french energy market is to transform it into valuable products. The oxygen steam gasification processes give a synthesis gas which can be converted into SNG or gasoline in a catalytic stage. The liquid phase hydrogenation process is a

  10. Pack Carburization of Mild Steel, using Pulverized Bone as Carburizer: Optimizing Process Parameters

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    Joseph Olatunde BORODE

    2010-12-01

    Full Text Available Investigation was conducted into the mechanical properties of mild steel subjected to packed carburization treatment using pulverized bone as the carburizer, carburized at 850C, 900C and 950C, soaked at the carburizing temperature for 15 minutes and 30 minutes, quenched in oil and tempered at 550C. Prior carburization process, standard test samples were prepared from the as received specimen for tensile and impact tests. After carburization process, the test samples were subjected to the standard test and from the data obtained, ultimate tensile strength, engineering strain, impact strength, Youngs moduli were calculated. The case and core hardness of the carburized tempered samples were measured. It was observed that the mechanical properties of mild steels were found to be strongly influenced by the process of carburization, carburizing temperature and soaking time at carburizing temperature. It was concluded that the sample carburized at 900C soaked for 15 minutes and the one carburized at 850C soaked for 30 minutes followed by oil quenching and tempering at 550C were better because they showed a trend of hard case with softer core.

  11. The properties and structure of the carburizers

    OpenAIRE

    K. Janerka; J. Jezierski; M. Pawlyta

    2010-01-01

    The results of examinations of the carburizers for foundry industry were presented in the article. The commonly used carburizers were selected for the experiments (anthracite, natural and synthetic graphite, petroleum coke of various grades), cupola coke and charcoal as well. The experiments consist of bulk and standard density, screen analysis (on the basis of it the equivalent diameter was calculated) and the microstructure of the carburizers measurements. The chemical composition and basic...

  12. Vacuum gas carburizing – fate of hydrocarbons

    OpenAIRE

    Khan, Rafi Ullah

    2008-01-01

    This work focuses on gaseous reactive flows in ideal and non-ideal reactors. The objective of this research is the development of models for the numerical simulation of homogeneous reactive flows under vacuum carburizing conditions of steel with propane and acetylene. These models can be used for further investigations of heterogeneous reactions during vacuum carburizing of steel to predict the carbon flux on the complex shaped steel parts to understand and, eventually, optimize the behavior ...

  13. Carburizer Effect on Cast Iron Solidification

    Science.gov (United States)

    Janerka, Krzysztof; Kondracki, Marcin; Jezierski, Jan; Szajnar, Jan; Stawarz, Marcin

    2014-06-01

    This paper presents the effect of carburizing materials on cast iron solidification and crystallization. The studies consisted of cast iron preparation from steel scrap and different carburizers. For a comparison, pig iron was exclusively used in a solid charge. Crystallization analysis revealed the influence of the carburizer material on the crystallization curves as well as differences in the solidification paths of cast iron prepared with the use of different charge materials. The carburizers' influence on undercooling during the eutectic crystallization process was analyzed. The lowest undercooling rate was recorded for the melt with pig iron, then for synthetic graphite, natural graphite, anthracite, and petroleum coke (the highest undercooling rate). So a hypothesis was formulated that eutectic cells are created most effectively with the presence of carbon from pig iron (the highest nucleation potential), and then for the graphite materials (crystallographic similarity with the carbon precipitation in the cast iron). The most difficult eutectic crystallization is for anthracite and petroleum coke (higher undercooling is necessary). This knowledge can be crucial when the foundry plant is going to change the solid charge composition replacing the pig iron by steel scrap and the recarburization process.

  14. Simultaneous oxidation and carburization under oxyfuel conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kranzmann, Axel; Schulz, Wencke [Federal Institute for Materials Research and Testing, Berlin (Germany). Div. V.1 Composition and Microstructure of Engineering Materials; Huenert, Daniela [National Institute for Standards and Technology, Gaithersburg, MD (United States). Group 855.13 Thermodynamics and Kinetics

    2010-06-15

    The combustion of coal in CO{sub 2}-reduced oxyfuel power plants requires creep resistant and corrosion resistant materials which can withstand high temperatures up to 600 C (873 K) and CO{sub 2}-rich atmospheres. Among the heat resistant materials, the 9-12 % chromium steels have been proven to resist high wall temperatures in conventional power plants and are suitable as membrane walls, superheaters and steam piping. During oxyfuel combustion a flue gas is generated which consists mainly of H{sub 2}O (x{sub H{sub 2}}{sub O}=0.3) and CO{sub 2} (x{sub CO{sub 2}}=0.7). The present paper is focused on the corrosion of 9-12 % chromium steels under oxyfuel conditions in a temperature range between 550 C (823 K) and 625 C (898 K). Depending on the chromium content of the 9-12 % chromium steels, carburization of the base material, perlite formation and carbide formation were observed. Alloys with lower chromium content form a non-protective oxide scale with perlite at the scale-alloy interface. Steels with 12 % chromium have a small growing oxide scale with enlarged M{sub 23}C{sub 6} particles at the scale-alloy interface. The carburization of the base material is found to be increased for the 9 % Cr steel. Higher pressure of the flue gas results in the formation of less resistant scales and causes accelerated carburization of the base materials. However, the carburization has an impact on the mechanical properties at the surface and leads to an embrittlement, which is deleterious during thermal cycling. Oxidation kinetics, phase analysis of the scale (transmission electron microscope) and carburization depths (microprobe) of the base materials are presented. (orig.)

  15. AN INVESTIGATION OF RETAINED AUSTENITE CONTENTS IN CARBURIZED SAE 8620 STEEL

    OpenAIRE

    2010-01-01

    ABSTRACT In this study, retained austenite contents in carburized  SAE 8620 (21NiCrMo2) steel were investigated. Carburizing programs were carried out in gas atmosphere at 940°C. X-ray diffraction was used to determine retained austenite contents in the case-hardened microstructures of the carburized specimens. Test results indicated that maximum retained austenite contents at the microstructures of the carburized specimens that carburized 45 minute, 3 h and 5 h carburizing times at ...

  16. Carburizer particle dissolution in liquid cast iron – computer simulation

    Directory of Open Access Journals (Sweden)

    D. Bartocha

    2010-01-01

    Full Text Available In the paper issue of dissolution of carburizing materials (anthracite, petroleum coke and graphite particle in liquid metal and its computer simulation are presented. Relative movement rate of particle and liquid metal and thermophsical properties of carburizing materials (thermal conductivity coefficient, specific heat, thermal diffusivity, density are taken into consideration in calculations. Calculations have been carried out in aspect of metal bath carburization in metallurgical furnaces.

  17. Numerical Simulation on Carburizing and Quenching of Gear Ring

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The carburizing process of the gear ring was simulated by taking into account the practical carburizing and quenching techniques of the gear ring and by solving the diffusion equation. The carbon content distribution in the carburized layer was obtained. Based on the results, the quenching process of the gear ring was then simulated using the metallic thermodynamics and FEM; it was found that the carburization remarkably affects the quenching process.Microstructures and stress distributions of the gear ring in the quenching process were simulated, and the results are confirmed by experiments.

  18. Packed bed carburization of tantalum and tantalum alloy

    Science.gov (United States)

    Lopez, Peter C.; Rodriguez, Patrick J.; Pereyra, Ramiro A.

    1999-01-01

    Packed bed carburization of a tantalum or tantalum alloy object. A method for producing corrosion-resistant tantalum or tantalum alloy objects is described. The method includes the steps of placing the object in contact with a carburizing pack, heating the packed object in vacuum furnace to a temperature whereby carbon from the pack diffuses into the object forming grains with tantalum carbide along the grain boundaries, and etching the surface of the carburized object. This latter step removes tantalum carbides from the surface of the carburized tantalum object while leaving the tantalum carbide along the grain boundaries.

  19. Magnetic Barkhausen Noise in quenched carburized steels

    Energy Technology Data Exchange (ETDEWEB)

    De Campos, M F; Santos, R; Da Silva, F S; Lins, J F C [PUVR- Universidade Federal Fluminense, Av dos Trabalhadores 420, Vila Santa Cecilia, Volta Redonda, RJ, 27255-125 (Brazil); Franco, F A; Ribeiro, S B; Padovese, L R, E-mail: mcampos@metal.eeimvr.uff.br, E-mail: mfdcampo@uol.com.br [Escola Politecnica, Universidade de Sao Paulo, Sao Paulo, SP (Brazil)

    2011-07-06

    Steels with different carbon content, 0.11%C and 0.48%C were submitted to a heat treatment for carburization in the surface. The samples were analyzed after several types of heat treatment, including quenching for producing martensite. The Magnetic Barkhausen Noise (MBN) is directly related to the microstructure. Samples with lower carbon content, have ferrite, a constituent where domain walls can move freely and present higher amplitude in the envelope of MBN. It is also found that the MBN peaks are quite distinct for the samples with martensite, which have lower permeability, and the results suggest that domain rotation contributes as mechanism for reversal of magnetization in martensite. The results also indicate that MBN is very suitable for monitoring the carburizing heat treatment.

  20. Magnetic Barkhausen Noise in quenched carburized steels

    Science.gov (United States)

    de Campos, M. F.; Franco, F. A.; Santos, R.; da Silva, F. S.; Ribeiro, S. B.; Lins, J. F. C.; Padovese, L. R.

    2011-07-01

    Steels with different carbon content, 0.11%C and 0.48%C were submitted to a heat treatment for carburization in the surface. The samples were analyzed after several types of heat treatment, including quenching for producing martensite. The Magnetic Barkhausen Noise (MBN) is directly related to the microstructure. Samples with lower carbon content, have ferrite, a constituent where domain walls can move freely and present higher amplitude in the envelope of MBN. It is also found that the MBN peaks are quite distinct for the samples with martensite, which have lower permeability, and the results suggest that domain rotation contributes as mechanism for reversal of magnetization in martensite. The results also indicate that MBN is very suitable for monitoring the carburizing heat treatment.

  1. Computation of carbon concentration curves in vacuum carburizing of steels

    Science.gov (United States)

    Semenov, M. Yu.; Smirnov, A. E.; Ryzhova, M. Yu.

    2013-05-01

    The boundary conditions of the diffusion problem in parametric form are determined on the basis of an experimental study of formation of carbon-saturated layers in vacuum carburizing. The boundary conditions are applied in a model of a process with cyclic modes of carburizing. Adequacy of the developed model is confirmed.

  2. Gas-Carburizing Kinetics of a Low-Alloy Steel

    Science.gov (United States)

    Nobili, Luca; Cavallotti, Pietro; Pesetti, Mariella

    2010-02-01

    Gas-carburizing kinetics of a low-alloy steel (Pyrowear 53) was investigated by thermogravimetric experiments. Kinetic curves were modeled by adapting the approximate integral method, and the diffusion coefficient of carbon as well as the rate constant of the surface reaction were estimated. These parameters were evaluated after several carburizing procedures, which differ from each other in the surface treatments performed before the carburizing step. It is known that the carbon enrichment is low when this steel is carburized without any pretreatment, and this behavior was found to be related to a low value of carbon diffusivity. The interaction between the selective oxidation of alloying elements by the carburizing atmosphere and carbon diffusion is discussed. The pretreatment procedures investigated in this work consist of different combinations of oxidation, reduction, and grit-blasting processes. The most effective procedures involve oxidation in dry air or oxidation in wet air followed by grit blasting.

  3. Enhancement of Stainless Steel's Mechanical Properties via Carburizing Process

    Science.gov (United States)

    Ahmad, S.; Alias, S. K.; Abdullah, B.; Hafiz Mohd Bakri, Mohd.; Hafizuddin Jumadin, Muhammad; Mat Shah, Muhammad Amir

    2016-11-01

    Carburizing process is a method to disperse carbon into the steel surface in order to enhance its mechanical properties such as hardness and wear resistance. This paper study investigates the effect of carburizing temperature to the carbon dispersion layer in stainless steel. The standard AISI 304 stainless steel was carburized in two different temperatures which were 900°C and 950°C. The effect of carbon dispersion layers were observed and the results indicated that the increasing value of the average dispersion layer from 1.30 mm to 2.74 mm thickness was found to be related to increment of carburizing holding temperature . The increment of carbon thickness layer also resulted in improvement of hardness and tensile strength of carburized stainless steel.

  4. Tribological and corrosion behaviors of carburized AISI 4340 steel

    Science.gov (United States)

    Thong-on, Atcharawadi; Boonruang, Chatdanai

    2016-01-01

    AISI 4340 steel is widely used in automotive and aircraft industries as gear components. In such applications, surface hardening processes such as carburizing are required in order to improve the life time of the components. There are many studies showing the tribological behavior of the carburized steel, but the corrosion behavior has not yet been clarified. This paper reports on both tribological and corrosion behaviors of the carburized AISI 4340 steel. Factor associated with carburizing, such as the quantities of deposited carbon, dissolved carbon, and formed Cr23C6 and Fe3C, affect the tribological and corrosion behaviors of the steel by improving hardness, friction, lubrication, and wear resistance; but corrosion resistance is reduced. The dissolved carbon affects the formation of the oxide layer of the carburized steel, by obstructing the continuous oxide layer formation and by decreasing the chromium content of the steel, leading to the decrease in the corrosion resistance of the steel.

  5. Green fuels, growth engines after petroleum; Les carburants verts, moteurs de la croissance apres le petrole

    Energy Technology Data Exchange (ETDEWEB)

    Mili, Dino

    2010-09-15

    The contribution of the new fuels to a greener environment is important and immediate. Thanks to clean novel technologies and to commercial plant projects in development, companies like Enerkem contribute to satisfy increasing global demand for clean energy. They stimulate local economies by creating jobs in an industry that offers real growth potential. Green fuels will gradually allow us to let go of non sustainable energy sources like oil to adopt a way of life based on sustainable development. They will also allow a shift towards a green economy. [French] La contribution des nouveaux carburants a un environnement plus vert est importante et immediate. Grace a des technologies propres novatrices et a des projets d'sines commerciales en developpement, des entreprises comme Enerkem contribuent a satisfaire a la demande mondiale croissante en energie propre. Elles stimulent les economies locales par la creation d'emplois dans une industrie qui offre un veritable potentiel de croissance. Les carburants verts permettront graduellement de nous affranchir des sources d'energie non renouvelables comme le petrole pour adopter un mode de vie base sur le developpement durable. Ils permettront aussi un virage vers une economie verte.

  6. Bio-energies. The domestic use of wood fuel: the weight of discretion. The urban and industrial wood heating, a growth value. Biomass - electricity - heat, towards a new concept. Bio-gas, a fermenting stake. Bio-components for fuels, foresight and quality. Biomolecules: towards a chemistry of substitution. Wood materials: a concentrate of environment; Les bioenergies. L'usage domestique du bois energie: le poids de la discretion. Le chauffage urbain et industriel au bois, une valeur de croissance. Biomasse - electricite - chaleur, vers un nouveau concept. Le biogaz, un enjeu qui fermente. Biocomposants pour carburants, prevoyance et qualite. Les biomolecules: vers une chimie de substitution. Le bois materiau: un concentre d'environnement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    This dossier presents a status of todays situation of the use of bio-energies in France and of its perspectives of development at the year 2006 vista. Seven aspects of bio-energies are considered: wood fuel, district and industrial heating, biomass production and gasification processes, biogas (methane) production from municipal waste tips, bio-fuels and bio-additives (bio-ethanol, ETBE, colza derived oils, vegetal oil methyl esters), bio-molecules production and valorization as substitutes to petroleum products (lubricants, wetting agents, solvents, polymers, coatings), development of wood materials (environmental advantages: CO{sub 2} immobilization, lower energy needs during fabrication, possible energy valorization at end life). (J.S.)

  7. Evaluation of Carburized and Ground Face Gears

    Science.gov (United States)

    Lewicki, David G.; Handschuh, Robert F.; Heath, Gregory F.; Sheth, Vijay

    1999-01-01

    Experimental durability tests were performed on carburized and ground AIS19310 steel face gears. The tests were in support of a Defense Advanced Research Projects Agency (DARPA) Technology Reinvestment Program (TRP) to enhance face-gear technology. The tests were conducted in the NASA Glenn spiral-bevel-gear/face-gear test facility. Tests were run at 2300 rpm face gear speed and at loads of 64, 76, 88, 100, and 112-percent of the design torque of 377 N-m (3340 in-lb). The carburized and ground face gears demonstrated the required durability when run for ten-million cycles at each of the applied loads. Proper installation was critical for the successful operation of the spur pinions and face gears. A large amount of backlash produced tooth contact patterns that approached the inner-diameter edge of the face-gear tooth. Low backlash produced tooth contact patterns that approached the outer-diameter edge of the face-gear tooth. Measured backlashes in the range of 0.178 to 0.254 mm (0.007 to 0.010 in) produced acceptable tooth contact patterns.

  8. Final Scientific Report - "Novel Steels for High Temperature Carburizing"

    Energy Technology Data Exchange (ETDEWEB)

    McKimpson, Marvin G.; Liu, Tianjun; Maniruzzaman, Md

    2012-07-27

    This program was undertaken to develop a microalloy-modified grade of standard carburizing steel that can successfully exploit the high temperature carburizing capabilities of current commercial low pressure (i.e. 'vacuum') carburizing systems. Such steels can lower the amount of energy required for commercial carburizing operations by reducing the time required for deep-case carburizing operations. The specific technical objective of the work was to demonstrate a carburizing steel composition capable of maintaining a prior austenite grain size no larger than ASTM grain size number 5 after exposure to simulated carburizing conditions of 1050 C for 8 hr. Such thermal exposure should be adequate for producing carburized case depths up to about 2 mm. Such carburizing steels are expected to be attractive for use across a wide range of industries, including the petroleum, chemical, forest products, automotive, mining and industrial equipment industries. They have potential for reducing energy usage during low pressure carburizing by more than 25%, as well as reducing cycle times and process costs substantially. They also have potential for reducing greenhouse gas emissions from existing low pressure carburizing furnaces by more than 25%. High temperature carburizing can be done in most modern low pressure carburizing systems with no additional capital investment. Accordingly, implementing this technology on carburizing furnaces will provide a return on investment significantly greater than 10%. If disseminated throughout the domestic carburizing community, the technology has potential for saving on the order of 23 to 34 trillion BTU/year in industrial energy usage. Under the program, two compositions of microalloyed, coarsening-resistant low alloy carburizing steels were developed, produced and evaluated. After vacuum annealing at 1050oC for 8 hrs and high pressure gas quenching, both steels exhibited a prior austenite ASTM grain size number of 5.0 or finer

  9. Cryogenic Treatment of Carbide-free Bainite Steel After Carburizing

    Directory of Open Access Journals (Sweden)

    SUN Shi-qing

    2017-05-01

    Full Text Available The cryogenic treatment (CT process of carbide-free bainite steel after carburizing was optimized by the method combining thermal magnetic analysis, microhardness analysis and direct reading spectrometric analysis. The results show that cryogenic treatment temperature of the hardened layer should be lower than 134K by measuring thermal magnetic curve of the sample after carburizing at 1193K and air cooling (AC. After cryogenic treatment at 123K and tempering (T at 463K, retained austenite content of the hardened layer is about 12.2% (mass fraction. The near surface layer of carburized steel is hardened dramatically through the cryogenic treatment, and the hardness of near surface layer reaches about 810HV1.0 after low temperature tempering. The distribution of hardness gradient of carburized steel tends to be reasonable.

  10. Computer simulation of carburizers particles heating in liquid metal

    Directory of Open Access Journals (Sweden)

    K. Janerka

    2010-01-01

    Full Text Available In this article are introduced the problems of computer simulation of carburizers particles heating (anthracite, graphite and petroleum coke, which are present in liquid metal. The diameter of particles, their quantity, relative velocity of particles and liquid metal and the thermophysical properties of materials (thermal conductivity, specific heat and thermal diffusivity have been taken into account in calculations. The analysis has been carried out in the aspect of liquid metal carburization in metallurgical furnaces.

  11. Electrochemical corrosion behavior of the carburized porous TiAl alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Cuijiao [Hunan University of Technology, Zhuzhou, Hunan 412000 (China); Yang, Junsheng [Wuhan Polytechnic University, Wuhan, Hubei 430023 (China); He, Yuehui, E-mail: yuehui@mail.csu.edu.cn [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Ming, XingZu [Hunan University of Technology, Zhuzhou, Hunan 412000 (China)

    2015-01-15

    Highlights: • Ti{sub 2}AlC phase forms on porous TiAl alloy in a carburizing atmosphere. • The carburized sample at 1203 K for 10 h has continuous carburized layers. • Carburization can improve corrosion resistance of the porous TiAl alloy. • The passive film of the carburized sample at 1203 K for 10 h is very stable. - Abstract: Carburization was carried out to improve corrosion resistance of porous Ti–46.5 Al (at.%) intermetallic compound. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) were applied to analyze the carburized layers. Electrochemical corrosion behavior of the untreated and the carburized samples were investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and open circuit potential. The results reveal that the continuous and thick carburized layers form after carburization treatment at 1203 K for 10 h, whose main phase is a functional complex ceramic phase, Ti{sub 2}AlC. Carburization can improve corrosion resistance of the porous TiAl alloy. Among the carburized samples, the carburized one at 1203 K for 10 h presents the highest corrosion resistance and has the most stable oxide film.

  12. Mechanical properties of the CO{sub 2} free vacuum carburized in SCM415H

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Jae Hyuk; Ro, Seung Hoon; Lee, Jong Hyung; Lee, Chang Hun; Yang, Seong Hyeon [Kumoh Nat' l Institute of Technology, Gumi (Korea, Republic of)

    2012-09-15

    Vacuum carburizing is supposed to be the superior process to the gas carburizing. However, the vacuum carburizing has the stage in which hydrocarbon gas is supplied into the furnace to be pyrolysis, and consequently the stable heat treatment is hard to achieve due to the soot from the hydrocarbon pyrolysis. Recently, many studies have been made which utilize acetylene gas to overcome this defects. In this paper, the carburizing and the diffusion periods have been selected based on the Harris experimental formula, and the mechanical properties of the vacuum carburized specimen have been compared with those of the gas carburized SCM415H specimen to identify the feasibility of the CO{sub 2} free vacuum carburizing process. The result showed that the vacuum carburized materials used have no oxidization of the grain boundaries, and show the 29.8% higher effective hardness depth and the acceptable tensile strength.

  13. Gradient boride layers formed by diffusion carburizing and laser boriding

    Science.gov (United States)

    Kulka, M.; Makuch, N.; Dziarski, P.; Mikołajczak, D.; Przestacki, D.

    2015-04-01

    Laser boriding, instead of diffusion boriding, was proposed to formation of gradient borocarburized layers. The microstructure and properties of these layers were compared to those-obtained after typical diffusion borocarburizing. First method of treatment consists in diffusion carburizing and laser boriding only. In microstructure three zones are present: laser borided zone, hardened carburized zone and carburized layer without heat treatment. However, the violent decrease in the microhardness was observed below the laser borided zone. Additionally, these layers were characterized by a changeable value of mass wear intensity factor thus by a changeable abrasive wear resistance. Although at the beginning of friction the very low values of mass wear intensity factor Imw were obtained, these values increased during the next stages of friction. It can be caused by the fluctuations in the microhardness of the hardened carburized zone (HAZ). The use of through hardening after carburizing and laser boriding eliminated these fluctuations. Two zones characterized the microstructure of this layer: laser borided zone and hardened carburized zone. Mass wear intensity factor obtained a constant value for this layer and was comparable to that-obtained in case of diffusion borocarburizing and through hardening. Therefore, the diffusion boriding could be replaced by the laser boriding, when the high abrasive wear resistance is required. However, the possibilities of application of laser boriding instead of diffusion process were limited. In case of elements, which needed high fatigue strength, the substitution of diffusion boriding by laser boriding was not advisable. The surface cracks formed during laser re-melting were the reason for relatively quickly first fatigue crack. The preheating of the laser treated surface before laser beam action would prevent the surface cracks and cause the improved fatigue strength. Although the cohesion of laser borided carburized layer was

  14. Analysis of methods of carburizing of gears from heat-resistant steels

    Science.gov (United States)

    Ryzhov, N. M.; Fakhurtdinov, R. S.; Smirnov, A. E.; Fomina, L. P.

    2010-11-01

    Four methods of carburizing are compared with respect to the most significant factor, i.e., stability of maintenance of the specified parameters of carburized layer in hardening of gears from heat-resistant steels. The process advantages of vacuum carburizing (at low pressure) are shown.

  15. Effect of carbon on tribological property of plasma carburized TiAl based alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-ping; TIAN Wen-huai; GUO Chao-li; HE Zhi-yong; XU Zhong

    2006-01-01

    Plasma carburization at two different methane-to-argon gas ratios (5:5 and 6:5) was carried out on the cast TiAl based alloy of Ti-46.5Al-2.5V-1Cr (mole fraction, %) in order to enhance its wear resistance. The results show that after carburization under both carburizing atmospheres, Ti2AlC and TiC are the main carbides in the carburized layer and the value of surface hardness reaches more than HK 822, but for the carburized TiAl treated at CH4-Ar of 5-5, the surface carbon concentration is higher and the carburized depth is slightly thicker than that of alloy carburized at CH4-Ar of 6-5. The result of the ball-on-disk test against hardening-steel counter bodies shows that the wear resistance of the TiAl based alloy carburized under two different carburizing atmospheres is improved compared with non-carburized TiAl. The tribological property is related to the carbon content, and the carburized layer obtained at CH4:Ar of 5:5 possesses a stable friction coefficient, lower volume loss or wear rate and narrow wear scar. The characteristic of the carburized layer was examined by using optical microscopy, glow discharge spectrum and micro-hardness tester.

  16. Materials and Process Design for High-Temperature Carburizing: Integrating Processing and Performance

    Energy Technology Data Exchange (ETDEWEB)

    D. Apelian

    2007-07-23

    The objective of the project is to develop an integrated process for fast, high-temperature carburizing. The new process results in an order of magnitude reduction in cycle time compared to conventional carburizing and represents significant energy savings in addition to a corresponding reduction of scrap associated with distortion free carburizing steels.

  17. Carburizing of Duplex Stainless Steel (DSS) Under Compression Superplastic Deformation

    Science.gov (United States)

    Ahamad, Nor Wahida; Jauhari, Iswadi

    2012-12-01

    A new surface carburizing technique which combines superplastic deformation with superplastic carburizing (SPC) is introduced. SPC was conducted on duplex stainless steel under compression mode at a fixed 0.5 height reduction strain rates ranging from 6.25 × 10-5 to 1 × 10-3 s-1 and temperature ranging from 1173 K to 1248 K (900 °C to 975 °C). The results are compared with those from conventional and non-superplastic carburizing. The results show that thick hard carburized layers are formed at a much faster rate compared with the other two processes. A more gradual hardness transition from the surface to the substrate is also obtained. The highest carburized layer thickness and surface hardness are attained under SPC process at 1248 K (975 °C) and 6.25 × 10-5 s-1 with a value of (218.3 ± 0.5) μm and (1581.0 ± 5.0) HV respectively. Other than that, SPC also has the highest scratch resistance.

  18. The Influence of Carburizing Parameters on Carbon Transfer Coefficient

    Institute of Scientific and Technical Information of China (English)

    Tadeusz Sobusiak

    2004-01-01

    Definition of coefficient of carbon transfer in European Standard (EN 10052) is presented as: "Mass of carbon transferred from carburizing medium into the steel, per unit surface area per second for a unit difference between the carbon potential, and actual surface carbon content".In this paper, a model is presented of carbon transfer from endothermic atmospheres to carbon steel. The carbon transfer coefficient values were determined experimentally by the foil technique and on specimens, taking into account the following parameters: chemical composition of atmospheres, carbon potential, temperature and time of the carburizing process. Some examples of the variation of the carbon transfer coefficient for two steps of the carburizing process,including soaking before quenching, are given, based on results obtained. The effect of carbon transfer coefficient on carbon content at the steel surface is given.

  19. The Corrosion Behavior of Carburized Aluminum Using DC Plasma

    Directory of Open Access Journals (Sweden)

    Somayeh Pirizadhejrandoost

    2012-01-01

    Full Text Available Because of the outstanding properties of aluminum, it is widely used in today's advanced technological world. However, its insufficient wear resistance limits its use for commercial and industrial applications. In this study, we performed DC diode plasma carburizing of aluminum in the gas composition of CH4–H2 (20–80% and at a temperature of about 350°C for 4 and 8 hours. The corrosion properties of the untreated and plasma-carburized samples were evaluated using anodic polarization tests in 3 N HCl solution according to ASTM: G5-94. The metallurgical characteristics were then investigated using XRD and SEM. The results showed that the carburizing process improves the corrosion resistance of treated specimens at low temperature.

  20. Bending Fatigue of Carburized Steel at Very Long Lives

    Science.gov (United States)

    Nelson, D. V.; Long, Z.

    2016-01-01

    The bending fatigue behavior of two carburized steels is investigated for lives between approximately 105 and 108 cycles. Cracks are observed to start at sub-surface inclusions and develop features on fracture surfaces resembling "fish eyes" in appearance. This type of sub-surface cracking tends to govern fatigue strength at long lives. Previous studies of "fish eye" fatigue in carburized steel have been relatively few and have mainly considered failures originating at depths beneath a carburized case, where compressive residual stresses are minimal and hardness values approach those in the core. This study provides fatigue data for cracks originating within cases at various depths where compressive residual stresses are substantial and hardness is much higher than in the core. Fatigue strength is predicted by a simple model, accounting for the influence of residual stresses and hardness values at the different depths at which cracks started. Predictions of fatigue strength are compared with data generated in this study.

  1. Investigation The Mechanical Properties of Carburized Low Carbon Steel

    Directory of Open Access Journals (Sweden)

    Dr. Mohammed Abdulraoof Abdulrazzaq

    2016-09-01

    Full Text Available microstructure, mechanical properties; hardness and wear resistance has been investigated taken different temperatures; (850, 900, and 950 ˚C with constant time (2 hr of carburizing process. The experimental work shows that at carburizing temperature (850 ˚C, the hardness was increases from the inside to outside of specimen from ( 102 to HV 250., while increases for temperatures (900 and 950 ˚C from (105 to 272 HV, and (115 to 192 HV respectively. This experiment also been conducted for wear resistance for harder specimen which was at 950 ˚C carburized sample for three times (2, 4 and, 6 hr and the wear rate was (9.99*10-6 g/m at (2 hr, and for (4 hr it was (12.7*10-6 g/m and at (6 hr it was (15.13*10-6 g/m.

  2. Effects of Carburized Parts on Residual Stresses of Thin-Rimmed Spur Gears with Symmetric Web Arrangements Due to Case-Carburizing

    Institute of Scientific and Technical Information of China (English)

    Kouitsu Miyachika; Wei-Dong Xue; Satoshi Oda; Hidefumi Mada; Hiroshige Fujio

    2004-01-01

    This paper presents a study on effects of carburized parts on residual stresses of thin-rimmed spur gears with symmetric web arrangements due to the case-carburizing. The carbon content of each element of the FEM gear model due to carburizing was obtained according to Vickers hardness Hv - carbon content C% and C% - d (distance from surface)charts. A heat conduction analysis and an elastic-plastic stress analysis during the case-carburizing process of thin-rimmed spur gears with symmetric web arrangements were carried out for various case-carburizing conditions by using the three-dimensional finite element method (3D-FEM) program developed by authors, and then residual stresses were obtained.The effects of the carburized part, the web structure, and the rim thickness on the residual stress were determined.

  3. On the Plasma (ion) Carburized Layer of High Nitrogen Austenitic Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    Y. Ueda; N. Kanayama; K. Ichii; T. Oishi; H. Miyake

    2004-01-01

    The manganese concentration of austenitic stainless steel decreases from the inner layer towards the surface of the plasma (ion) carburized layer due to the evaporation of manganese from the specimen surface. The carbon concentration in the carburized layer is influenced by alloyed elements such as Ct, Ni, Si, and Mo, as well as Nitrogen. This study examined the effects of nitrogen on the properties of the carburized layer of high nitrogen stainless steel. Plasma (ion)carburizing was carried out for 14.4 ks at 1303 K in an atmosphere of CH4+H2 gas mixtures under a pressure of 350 Pa. The plasma carburized layer of the high nitrogen stainless steel was thinner than that of an austentric stainless steel containing no nitrogen. This suggested that the nitrogen raised the activity of carbon in the plasma carburized layer, GDOES measurement indicated that the nitrogen level in the layer did not vary after plasma (ion) carburizing.

  4. Etudes sur la phase carbure de bore. Corrélations propriétés-composition

    OpenAIRE

    1982-01-01

    No english abstract; La connaissance du diagramme de phases bore-carbone, des propriétés physico chimiques et la structure du carbure de bore ont été approfondies. Dans ce but, nous avons mis en œuvre principalement deux méthodes de préparation de nos échantillons : ¤ la fusion au canon à électrons, ¤ la compression à chaud. Il faut noter que nous avons considérablement amélioré cette dernière méthode pour la rendre apte à la préparation en particulier d'échantillons constitués de bore pur ou...

  5. MPPA-SSI12 automated module facility for "liquid" carburizing

    Science.gov (United States)

    Syropyatov, V. Ya.

    2011-10-01

    An automated module facility of model MPPA-SSi12 for making controlled endothermic furnace atmospheres based on carbon-containing liquids is described. The facility is used for batching and feeding process liquids into carburizing shaft electric furnaces with automatic control of the carbon potential by changing the flow of added air.

  6. Contribution of shot peening on carburized or carbonitrided parts

    Science.gov (United States)

    Renaud, P.; Bristiel, P.; Barrallier, L.; Desvignes, M.; Kubler, R.

    2011-01-01

    The main purpose of car manufacturers is to design parts which are light and at the same time very resistant to fatigue efforts. Surface treatments are effective means to deal with this compromise. They bring surface hardness and introduce compressive residual stresses. This experimental study focuses on the influence of shot peening on parts initially treated by carburizing or carbonitriding.

  7. The Effect of Thermo-mechanical Treatment of Substrate Preparation and Carburizing Temperature on The Morphology and Hardness of Carburizing on Low Carbon Steel

    Science.gov (United States)

    Dadan Ramdan, Raden; Adetia, Andra; Suratman, Rochim

    2017-07-01

    Low carbon steel has a lot of applications in daily life because of its excellent properties. Among its excellent properties are good ductility, toughness, formability, and weldability. For the case of application that requires good wear resistant, carbon steel is not sufficient. For this case it is required to increase the hardness of carbon steel, such as by carburizing method. In this method one factor that affects the carburizing layer is metal substrate condition, i.e grain size. Another factor is temperature that could have significant role on the carburized layer characteristics. Therefore the present works focus in the correlation between degree of reduction of cold rolling and carburizing temperature on the carburized layer characteristic. Thermo-mechanical treatment was applied to the specimen with reduction of 0%, 30%, and 80% by mean of rolling before carburizing process. Carburizing processes were carried out at temperature of 850°C, 900°C, and 950°C. Examinations on carburized specimens were conducted by metallography and micro hardness test. The result showed that the specimen of 80% reduction giving the thickest layer and the hardest surface layer. In addition, at temperature of 900°C, the hardest layer was formed with the hardness at 1003 HV. However, the thickest layer was formed at the temperature of 950°C.

  8. Study on Carburizing Kinetics of Low-carbon Steel at High-temperature and Short-term

    Institute of Scientific and Technical Information of China (English)

    Lu Sheng; Xiao Nianxin; Zhang Hailong

    2007-01-01

    In this paper, the carburizing kinetics of low-carbon steel at high-temperature and short-term in liquid cast-iron were studied by metallographic microscope, chemical analysis and so on, and the microstructure of carburized layer was also analyzed. The results show that the carburizing rate of low-carbon steel at high-temperature and short-term is so fast, and the microstructure of carburized layer possess higher carbon content, and cementite, pearlite and ferrite exist in carburized layer structure simultaneously. Besides, the kinetic equations of permeating layer forming have been presented, and the carburizing mechanism was preliminary discussed also.

  9. Double Glow Plasma Hydrogen-free Carburizing on Commercial Purity Titanium

    Institute of Scientific and Technical Information of China (English)

    ZHANG Gaohui; PAN Junde; HE Zhiyong; ZHANG Pingze; GAO Yuan; XU Zhong

    2005-01-01

    A carburized layer with special physical and chemical properties was formed on the surface of commercial purity titanium by a double glow plasma hydrogen-free carburizing technique. High-purity netlike solid graphite was used as a raw material and commercial purity titanium was used as the substrate material. Argon gas was used as the working gas. The carburized layer can be obviously observed under a microscope. X-ray diffraction indicates that TiC phase with higher hardness and dissociate state carbon phase was formed in the carburized layer. The glow discharge spectrum (GDS) analysis shows that the carbon concentration distributes gradiently along the depth of carburized layer. The surface hardness of the substrate increases obviously. The hardness distributes gradiently from the surface to inner of carburized layer. The friction coefficient reduces by more than 1/2, the ratio wear rate decreases by above three orders of magnitude. The wear resistance of the substrate material is improved consumedly.

  10. Graphene Growth via Carburization of Stainless Steel and Application in Energy Storage

    Science.gov (United States)

    2011-01-01

    1697© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.comsmall 2011, 7, No. 12, 1697–1700 1. Introduction Carburization is a...in order to achieve few-layers-thick graphene on stainless steel (SS) substrates. Though the carburization process is similar to the chemi cal...vapor deposition (CVD) tech- nique, which is generally used for growth of graphene on Graphene Growth via Carburization of Stainless Steel and

  11. Hydrogen uptake during Carburizing and Effusion of Hydrogen at Room Temperature and during Tempering

    OpenAIRE

    Khodahami, Maryam

    2013-01-01

    The carburizing atmosphere during the case hardening process contains a large proportion of hydrogen. Due to the rapid diffusion of hydrogen a high amount of hydrogen can be absorbed by the carburizing component. The amount of absorbed hydrogen is dependent on some factors such as for example the carburizing time and component dimensions. Hydrogen diffused in material can then cause hydrogen embrittlement and in some cases cause cracking under a static load. This hydrogen must therefore be re...

  12. Low Temperature Surface Carburization of Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Sunniva R; Heuer, Arthur H; Sikka, Vinod K

    2007-12-07

    Low-temperature colossal supersaturation (LTCSS) is a novel surface hardening method for carburization of austenitic stainless steels (SS) without the precipitation of carbides. The formation of carbides is kinetically suppressed, enabling extremely high or colossal carbon supersaturation. As a result, surface carbon concentrations in excess of 12 at. % are routinely achieved. This treatment increases the surface hardness by a factor of four to five, improving resistance to wear, corrosion, and fatigue, with significant retained ductility. LTCSS is a diffusional surface hardening process that provides a uniform and conformal hardened gradient surface with no risk of delamination or peeling. The treatment retains the austenitic phase and is completely non-magnetic. In addition, because parts are treated at low temperature, they do not distort or change dimensions. During this treatment, carbon diffusion proceeds into the metal at temperatures that constrain substitutional diffusion or mobility between the metal alloy elements. Though immobilized and unable to assemble to form carbides, chromium and similar alloying elements nonetheless draw enormous amounts of carbon into their interstitial spaces. The carbon in the interstitial spaces of the alloy crystals makes the surface harder than ever achieved before by more conventional heat treating or diffusion process. The carbon solid solution manifests a Vickers hardness often exceeding 1000 HV (equivalent to 70 HRC). This project objective was to extend the LTCSS treatment to other austenitic alloys, and to quantify improvements in fatigue, corrosion, and wear resistance. Highlights from the research include the following: • Extension of the applicability of the LTCSS process to a broad range of austenitic and duplex grades of steels • Demonstration of LTCSS ability for a variety of different component shapes and sizes • Detailed microstructural characterization of LTCSS-treated samples of 316L and other alloys

  13. Kinetics and mechanical study of plasma electrolytic carburizing for pure iron

    Science.gov (United States)

    Çavuşlu, F.; Usta, M.

    2011-02-01

    In this work, plasma electrolytic surface carburizing of pure iron in aqueous solution consisting of water, glycerin and NH4Cl was investigated. Surface carburizing was carried out in 20% glycerin solution treated at 750 °C, 800 °C, 900 °C and 950 °C temperatures for 5, 10 and 30 min. The formation of hard carbon-rich layer on the surface of pure iron was confirmed by XRD analysis. Metallographic and SEM studies revealed a rough and dense carburized layer on the surface of the pure iron. Experimental results showed that the thickness of the carburized layers changes with the time and temperature. The average thickness of the carburized layer ranged from 20 to 160 μm. The hardness of the carburized samples decreased with the distance from the surface to the interior of the test material. The average hardness values of the carburized layers on the substrate ranged 550-850 HV, while the hardness of the substrate ranged from 110 HV to 170 HV. The dominant phases formed on the pure iron were found to be a mixture of cementite (Fe3C), martensite (Fe + C) and austenite (FCC iron) confirmed by XRD. Wear resistance in all plasma electrolytic carburized samples is considerably improved in relation to the untreated specimen. After carburizing, surface roughness of the samples was increased. Friction coefficients were also increased because of high surface roughness.

  14. Nomograms to Determine the Controlling Factors in Vacuum-Carburizing Regimes

    Science.gov (United States)

    Semenov, M. Yu.

    2016-09-01

    A method based on computer evaluation of mechanical properties and a mathematical model of vacuum carburizing are used for creating two nomograms, i.e., ( 1 ) for determining the parameters that the carburized layers of gears of steel 16Kh3NVFMB-Sh must have to obtain the required service properties and ( 2 ) for determining the values that the factors in periodic carburizing regimes must have to ensure that the layers have the prescribed parameters. The nomograms are used to determine the factors for two gears that are to undergo vacuum carburizing.

  15. Paraequilibrium Carburization of Duplex and Ferritic Stainless Steels

    Science.gov (United States)

    Michal, G. M.; Gu, X.; Jennings, W. D.; Kahn, H.; Ernst, F.; Heuer, A. H.

    2009-08-01

    AISI 301 and E-BRITE stainless steels were subjected to low-temperature (743 K) carburization experiments using a commercial technology developed for carburization of 316 austenitic stainless steels. The AISI 301 steel contained ~40 vol pct ferrite before carburization but had a fully austenitic hardened case, ~20- μm thick, and a surface carbon concentration of ~8 at. pct after treatment; this “colossal” paraequilibrium carbon supersaturation caused an increase in lattice parameter of ~3 pct. The E-BRITE also developed a hardened case, 12- to 18- μm thick, but underwent a more modest (~0.3 pct) increase in lattice parameter; the surface carbon concentration was ~10 at. pct. While the hardened case on the AISI 301 stainless steel appeared to be single-phase austenite, evidence for carbide formation was apparent in X-ray diffractometer (XRD) scans of the E-BRITE. Paraequilibrium phase diagrams were calculated for both AISI 301 and E-BRITE stainless steels using a CALPHAD compound energy-based interstitial solid solution model. In the low-temperature regime of interest, and based upon measured paraequilibrium carbon solubilities, more negative Cr-carbon interaction parameters for austenite than those in the current CALPHAD data base may be appropriate. A sensitivity analysis involving Cr-carbon interaction parameters for ferrite found a strong dependence of carbon solubility on relatively small changes in the magnitude of these parameters.

  16. Advances and directions of ion nitriding/carburizing

    Science.gov (United States)

    Spalvins, Talivaldis

    1989-01-01

    Ion nitriding and carburizing are plasma activated thermodynamic processes for the production of case hardened surface layers not only for ferrous materials, but also for an increasing number of nonferrous metals. When the treatment variables are properly controlled, the use of nitrogenous or carbonaceous glow discharge medium offers great flexibility in tailoring surface/near-surface properties independently of the bulk properties. The ion nitriding process has reached a high level of maturity and has gained wide industrial acceptance, while the more recently introduced ion carburizing process is rapidly gaining industrial acceptance. The current status of plasma mass transfer mechanisms into the surface regarding the formation of compound and diffusion layers in ion nitriding and carbon build-up ion carburizing is reviewed. In addition, the recent developments in design and construction of advanced equipment for obtaining optimized and controlled case/core properties is summarized. Also, new developments and trends such as duplex plasma treatments and alternatives to dc diode nitriding are highlighted.

  17. Cu-Precipitation Strengthening in Ultrahigh-Strength Carburizing Steels

    Science.gov (United States)

    Tiemens, Benjamin L.; Sachdev, Anil K.; Olson, Gregory B.

    2012-10-01

    Ultrahigh hardness levels greater than 700 VHN can be obtained in secondary hardening carburizing steels but depend on costly Co alloying additions to maximize hardness achieved through M2C-type carbide precipitation strengthening. This study aims to incorporate nanometer-scale bcc Cu precipitates to both provide strength as well as catalyze M2C nucleation in the absence of or with reduced Co. Cu additions of 1.0 and 3.7 wt pct were investigated, using a series of mechanistic models coupled with thermodynamic computational tools to derive final compositions. Thirty-pound experimental heats were cast of each designed alloy, samples of which were carburized and tempered to determine their hardness response. Characterization revealed the successful incorporation of Cu alloying additions into this family of steels, demonstrating a secondary hardening response even in the absence of Co. Matrix strength levels were close to those predicted by design models; however, all four alloys demonstrated a hardness deficit of approximately 200 VHN at the carburized surface, suggesting recalibration of the M2C precipitation strengthening model may be required in these alloys.

  18. The effects of energizer and carburizing temperature and time on mechanical properties of hardened big knives in the pack carburizing process

    Directory of Open Access Journals (Sweden)

    Narongsak Thammachot

    2016-10-01

    Full Text Available The purpose of this research is to study the effects of energizer and carburizing temperature and time on the mechanical properties of hardened big knives in the pack carburizing process. The mechanical properties of carburized and hardened big knives were compared to those of commercial hardened big knives made from leaf-spring steel that were forged, ground and quenched following the traditional forging processes. The experiment was conducted by forging big knives made of low carbon steel (grade AISI 1010. The first group of them was then pack-carburized using 10% by weight of calcium carbonate with 90% by weight of eucalyptus charcoal. The second group used 10% by weight of egg shell with 90% by weight of eucalyptus charcoal. The carburizing temperatures were 900, 950 and 1,000°C, with carburizing times of 30, 60 and 90 minutes followed by air cooling. The austenitizing temperature was 780°C with a holding time of 20 minutes, followed by quenching in water. Finally, the big knives were tempered at 180°C for 1 hour. Micro-Vickers hardness testing, impact testing and microstructure inspection were carried out. The results of this experiment show that the hardness of hardened big knives increased with an increase in the carburizing temperature and time. In contrast, the impact value of carburized steel decreased with an increase in the carburizing temperature and time. The hardness derived from using CaCO3 is slightly harder than that from using egg shell, however, the impact energy is higher when using egg shell, compared to using CaCO3.

  19. Low Temperature Surface Carburization of Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Sunniva R; Heuer, Arthur H; Sikka, Vinod K

    2007-12-07

    Low-temperature colossal supersaturation (LTCSS) is a novel surface hardening method for carburization of austenitic stainless steels (SS) without the precipitation of carbides. The formation of carbides is kinetically suppressed, enabling extremely high or colossal carbon supersaturation. As a result, surface carbon concentrations in excess of 12 at. % are routinely achieved. This treatment increases the surface hardness by a factor of four to five, improving resistance to wear, corrosion, and fatigue, with significant retained ductility. LTCSS is a diffusional surface hardening process that provides a uniform and conformal hardened gradient surface with no risk of delamination or peeling. The treatment retains the austenitic phase and is completely non-magnetic. In addition, because parts are treated at low temperature, they do not distort or change dimensions. During this treatment, carbon diffusion proceeds into the metal at temperatures that constrain substitutional diffusion or mobility between the metal alloy elements. Though immobilized and unable to assemble to form carbides, chromium and similar alloying elements nonetheless draw enormous amounts of carbon into their interstitial spaces. The carbon in the interstitial spaces of the alloy crystals makes the surface harder than ever achieved before by more conventional heat treating or diffusion process. The carbon solid solution manifests a Vickers hardness often exceeding 1000 HV (equivalent to 70 HRC). This project objective was to extend the LTCSS treatment to other austenitic alloys, and to quantify improvements in fatigue, corrosion, and wear resistance. Highlights from the research include the following: • Extension of the applicability of the LTCSS process to a broad range of austenitic and duplex grades of steels • Demonstration of LTCSS ability for a variety of different component shapes and sizes • Detailed microstructural characterization of LTCSS-treated samples of 316L and other alloys

  20. Research on Eddy Current Testing System of the Carburized Layer Depth of 20CrMnTi Steel

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiao-min; LI Na; WU Xin- wen; FANG Hua-bin

    2004-01-01

    In this paper the carbon distribution in the carburized layer of 20CrMnTi steel was studied. The relationship between the depth of a carburized layer and the surface carbon distribution was established. Eddy current testing system of the case depth of this carburized steel was built by using ANSYS software as second development platform.

  1. High temperature carburizing of a stainless steel with uranium carbide

    Energy Technology Data Exchange (ETDEWEB)

    Sar Latin-Small-Letter-Dotless-I kaya, Yueksel, E-mail: sakaya@science.ankara.edu.tr [Ankara University, Faculty of Science, Department of Chemistry, Tandogan, 06100 Ankara (Turkey); Oenal, Mueserref [Ankara University, Faculty of Science, Department of Chemistry, Tandogan, 06100 Ankara (Turkey)

    2012-11-25

    Graphical abstract: Temperature dependence of diffusion coefficient for carbon atoms in steel by carburizing with uranium carbide was found as: D = 2.6 Multiplication-Sign 10{sup -11} exp (-66753/RT) in m{sup 2} s{sup -1} microhardness measurements. Changes in thermodynamic quantities by formation of an activated complex with temperature were obtained as follows: {Delta}H{sup numbersign} = 66741-8.3T J mol{sup -1}, {Delta}C{sub p}{sup numbersign} = 8.3 J K{sup -1} mol{sup -1}, ln K{sup numbersign} = -66741/RT = (8.3/R)lnT-48.3, {Delta}G{sup numbersign} = 66741 + 8.3T lnT + 48.3RT J mol{sup -1}, and {Delta}S{sup numbersign} = -409.9-8.3 lnT in J K{sup -1} mol{sup -1}. Highlights: Black-Right-Pointing-Pointer Diffusion and activated complex theories were applied on the carburizing of steel. Black-Right-Pointing-Pointer Carburizing of steel was investigated by microhardness measurements. Black-Right-Pointing-Pointer Diffusion coefficient of carbon in the steel was determined. Black-Right-Pointing-Pointer Thermodynamic quantities by formation an activated complex were determined. - Abstract: Diffusion theory (DT) and activated complex theory (ACT) were applied to the carburizing process of austenitic stainless steel 1.4988 with uranium carbide by sodium bonding at 773, 873, 973 and 1073 K for 1000 h. Microhardness profiles of the carburized steel specimens were obtained. Diffusion coefficient (D) of carbon atoms into the steel were calculated for each temperature by using the microhardness values instead of the carbon concentrations in the approximate solution of the second Fick's equation. Arrhenius equation for the carburizing process was found as: D = 2.6 Multiplication-Sign 10{sup -11} exp (-66753/RT) in m{sup 2} s{sup -1}. Equilibrium constant (K{sup numbersign}) and enthalpy of activation ({Delta}H{sup numbersign}) for the formation of an activated complex calculated for each temperature from the Eyring equation using the diffusion coefficient instead of the

  2. Acetylene Flow Rate as a Crucial Parameter of Vacuum Carburizing Process of Modern Tool Steels

    Directory of Open Access Journals (Sweden)

    Rokicki P.

    2016-12-01

    Full Text Available Carburizing is one of the most popular and wide used thermo-chemical treatment methods of surface modification of tool steels. It is a process based on carbon diffusive enrichment of the surface material and is applied for elements that are supposed to present higher hardness and wear resistance sustaining core ductility. Typical elements submitted to carburizing process are gears, shafts, pins and bearing elements. In the last years, more and more popular, especially in highly advanced treatment procedures used in the aerospace industry is vacuum carburizing. It is a process based on chemical treatment of the surface in lower pressure, providing much higher uniformity of carburized layer, lower process cost and much lesser negative impact on environment to compare with conventional carburizing methods, as for example gas carburizing in Endo atmosphere. Unfortunately, aerospace industry requires much more detailed description of the phenomena linked to this process method and the literature background shows lack of tests that could confirm fulfilment of all needed requirements and to understand the process itself in much deeper meaning. In the presented paper, authors focused their research on acetylene flow impact on carburized layer characteristic. This is one of the most crucial parameters concerning homogeneity and uniformity of carburized layer properties. That is why, specific process methodology have been planned based on different acetylene flow values, and the surface layer of the steel gears have been investigated in meaning to impact on any possible change in potential properties of the final product.

  3. Cyclic strength of steel 16Kh3NVFBM-Sh (VKS-5) after vacuum carburizing

    Science.gov (United States)

    Ryzhov, N. M.; Fakhurtdinov, R. S.; Smirnov, A. E.

    2010-07-01

    Cyclic strength of steel 16Kh3NVFMB-Sh is studied after vacuum and gas carburizing. It is shown that the fatigue resistance of the steel hardened by the method of vacuum carburizing is higher. The thickness of the layer and the concentration of carbon on the surface at which the cyclic endurance is the highest are determined.

  4. Optimization of the Process of Carburizing and Heat Treatment of Low-Carbon Martensitic Steels

    Science.gov (United States)

    Ivanov, A. S.; Greben'kov, S. K.; Bogdanova, M. V.

    2016-05-01

    Steel 24Kh2G2NMFB is studied after carburizing and different heat treatments. The hardness and microhardness of the surface layer and of the matrix are measured. The content of retained austenite is determined by the method of x-ray diffraction analysis. Heat treatment modes improving the structure of the surface layer after carburizing are suggested.

  5. Sliding wear behaviour of steel carburized using Na2CO3-NaCl

    Directory of Open Access Journals (Sweden)

    Liew Willey Y. H.

    2017-01-01

    Full Text Available Experiments have been carried out to investigate the effect of carburization process on the sliding wear resistance of mild steel. The carburization process was conducted in carbonate salts mixtures of Na2CO3-NaCl. Carburization followed by water quenching resulted in the formation of martensite with a hardness of 900 HV in the subsurface, up to the depth of 400 μm. This hardness value was substantially higher than the non-carburized steel which had a hardness of 520 HV. In the initial stage of sliding in air, abrasive wear and cluster of fine cavities due to adhesion were formed. This was followed by the formation of large-scale fracture at the cavities. The high hardness of the carburized steel reduced the severity of adhesive wear and thus the tendency of the worn surface to fracture.

  6. In Situ Observation for Abnormal Grain Coarsening in Vacuum-Carburizing Process

    Science.gov (United States)

    Yogo, Yasuhiro; Tanaka, Kouji

    2014-06-01

    An in situ observation method was developed to investigate abnormal grain coarsening which occurs around the surface of steel during the vacuum-carburizing process. In this method, diffusion of carbon atoms in the vacuum carburizing was simulated by a cementite and steel diffusion couple. Abnormal grain coarsening, which appeared around the cementite and steel interface, was observed by a confocal scanning laser microscope. With this method, it was observed that when holding time was 60 seconds, the temperature at which the abnormal grain coarsening appeared in a specimen was higher when carburized than the temperature when not carburized. On the contrary, when holding time was 120 seconds, the temperature at which the abnormal grain coarsening appeared in a specimen was 10 K to 20 K lower than that in a non-carburized specimen. The validity of the observed results was confirmed by the calculated NbC fraction using Nb solubility and measured carbon content.

  7. THE COMPARISON OF THE RESIDUAL STRESSES BETWEEN CARBURIZED AND ONLY QUENCHED STEELS

    Directory of Open Access Journals (Sweden)

    Osman ASİ

    2001-02-01

    Full Text Available In this study, the residual stresses developing in carburized and only quenched steel of SAE 8620 (21NiCrMo2 which is widely used as a carburized steel (shafts, gears etc. was investigated. Carburizing programs was carried out in gas atmosphere for 45 minute at 940 °C. X-ray analysis was used to determine residual stress in the microstructures of the only quenched and carburized specimens. The results of x-ray analysis have shown that while the carburized specimens have a residual compressive stress at the surface -551N/mm 2 , the only quenched specimens have a residual compressive stress at the surface -125 N/mm 2 .

  8. Des changements concevables pour le secteur des transports dans l'objectif "Facteur 4"

    OpenAIRE

    Raux, Charles

    2007-01-01

    Au niveau mondial, les transports consomment 20% de l'énergie, dont 80% dans les transports routiers et 10% dans les transports aériens, et 95% de cette énergie est à base de pétrole. Le secteur des transports est l'un des principaux émetteurs de gaz à effet de serre dans la plupart des pays, et notamment du CO2 issu de la combustion des carburants fossiles. Pour que les transports contribuent significativement à l'objectif du « Facteur 4 » en 2050, trois pistes différentes mais complémentair...

  9. Effect of carburization on electrochemical corrosion behaviours of TiAl alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Cuijiao [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Hunan University of Technology, Zhuzhou, Hunan 412000 (China); He, Yuehui, E-mail: yuehui@mail.csu.edu.cn [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Yang, Junsheng; Nan, Bo; Liu, Xinli [State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

    2013-04-20

    Highlights: ► The functional complex ceramic phase Ti{sub 2}AlC was formed by pack carburizing. ► The anodic polarization curve of the carburized TiAl alloy shows a larger passivation interval (about 1.246 V). ► The polarization resistance of the carburized TiAl alloy is at least seventeen times higher, compared to the untreated TiAl alloy. ► The corroded surface of the carburized TiAl alloy was covered with passive film. -- Abstract: Electrochemical corrosion behaviours of the untreated and the carburized of Ti-46.5Al (mol %) alloy were investigated. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) were applied to characterize the carburized layer. Potentiodynamic polarization curve, electrochemical impedance spectroscopy (EIS) and SEM morphology of the corroded surface were used to evaluate corrosion resistance of both carburized and untreated TiAl alloy in 1 mol/L HCl. The outer layer of the carburized TiAl alloy is a continuous Ti{sub 2}AlC scale. Polarization curve and electrochemical impedance spectroscopy (EIS) of the carburized TiAl alloy present a nobler corrosion potential, a more positive pitting potential and a higher polarization resistance, respectively, compared with the untreated sample. After anodic corrosion or immersion corrosion, a deposited layer can be observed on the surface of the carburized titanium aluminide alloy. By contrast, pitting and crevasse corrosion occur on the surface of the untreated TiAl alloy after anodic corrosion and some corrosion products and slight corrosion appear on the surface of the untreated TiAl alloy after immersion corrosion.

  10. On the genesis of molybdenum carbide phases during reduction-carburization reactions

    Energy Technology Data Exchange (ETDEWEB)

    Guil-Lopez, R., E-mail: rut.guil@icp.csic.es [Grupo de Energia y Quimica Sostenibles, ICP-CSIC, Marie Curie 2, Cantoblanco, 28049-Madrid (Spain); Nieto, E. [Grupo de Energia y Quimica Sostenibles, ICP-CSIC, Marie Curie 2, Cantoblanco, 28049-Madrid (Spain); Departamento de Tecnologia Quimica y Energetica, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, 28933-Mostoles (Spain); Botas, J.A. [Departamento de Tecnologia Quimica y Energetica, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, 28933-Mostoles (Spain); Fierro, J.L.G., E-mail: jlgfierro@icp.csic.es [Grupo de Energia y Quimica Sostenibles, ICP-CSIC, Marie Curie 2, Cantoblanco, 28049-Madrid (Spain)

    2012-06-15

    Molybdenum carbide has been prepared according to the carbothermal reduction method. Carbon black substrate was used as C-source whereas a H{sub 2}-flow was the reducing agent. Two different H{sub 2} consumption steps were identified during the carburization treatment. The low temperature step is related to the reduction of Mo{sup 6+}-to-Mo{sup 4+}, the higher temperature process accounts for the deep reduction of Mo{sup 4+}-to-metal Mo{sup 0} and its subsequent reaction with C to form the Mo-carbide. The influences of the maximum carburization temperature, carburization time, gas hourly space velocity regarding Mo-loading, heating rate and temperature of Ar pre-treatment were analyzed. All these conditions are interrelated to each other. Thus, the carburization process ends at 700 Degree-Sign C when Mo-loading is 10 wt%, however Mo-loading higher than 10 wt% requires higher temperatures. Carburization temperatures up to 800 Degree-Sign C are needed to fulfill Mo-carbide formation with samples containing 50 wt% Mo. Nevertheless, Ar pre-treatment at 550 Degree-Sign C and slow heating rates favor the carburization, thus requiring lower carburization temperatures to reach the same carburization level. - Graphical Abstract: H{sub 2}-consumption profile (TPR) during the molybdenum carburization process, XRD patterns of the reduced Mo-samples after carburization and TEM-micrographs with two different enlargement of the samples with 5, 20 and 50 wt% Mo. Highlights: Black-Right-Pointing-Pointer Control of carburization variables: tailor the reduced/carbide Mo-phases (single/mixture). Black-Right-Pointing-Pointer Mo carburization in two stages: (1) Mo{sup 6+}-Mo{sup 4+}; (2) Mo{sup 4+}-Mo{sup 0} and, at once, MoC. Black-Right-Pointing-Pointer The carburization process is faster than Mo{sup 4+} reduction. Black-Right-Pointing-Pointer XPS probed: reduced Mo particles show core-shell structure. Black-Right-Pointing-Pointer Core: reduced Mo (Mo{sub 2}C, MoO{sub 2} and/or Mo

  11. Plutonium ion emission from carburized rhenium mass spectrometer filaments

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, J.M.; Robertson, D.M.

    1985-01-01

    Physicochemical processes important to the application of thermal emission mass spectrometry were identified and clarified. Effects of filament carbon concentration and temperature on plutonium ion emissions from a carburized rhenium filament were determined. Filament carbon concentration profoundly affected the appearance and duration of an ion signal. A useful ion signal was produced only when the carbon saturation temperature of the filament was exceeded, at which point first-order kinetics were either achieved or closely approached. This paper explains observed ion emission behavior in terms of pausible carbothermic reduction reactions and carbon diffusion processes that direct the course of those reactions. 31 references, 5 figures.

  12. Direct reduction of carburized pre-reduced pellets by microwave heating

    Institute of Scientific and Technical Information of China (English)

    胡兵; 黄柱成; 易凌云; 姜涛

    2014-01-01

    A new iron-making process using carburized pre-reduced iron ore pellets and microwave heating is investigated. The pre-reduced pellets, with a porous structure, and fine particles are carburized homogeneously at 400-650 °C in a CO atmosphere. The carburized carbon not only acts reaction as a reduction agent, but also absorbs microwave in the reduction process. Hence, the carburized pre-reduced pellets can be rapidly reduced by microwave heating. There are three procedures involved in the process, namely, gas-based pre-reduction, low-temperature carburization and deep reduction by microwave heating. Carburized pre-reduced iron ore pellets show a rapid temperature rise that is twice as fast as the results for pre-reduced pellets in the laboratory. This not only improves the efficiency of the microwave heating, but also accelerates the reduction of iron oxides. The temperature of the pre-reduced pellets rises to 1050 °C in 45 min when the carburization rate is 2.02%, and the metallization rate and compressive strength reach 94.24%and 1725 N/pellet, respectively.

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

    Directory of Open Access Journals (Sweden)

    Joffres B.

    2013-10-01

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

  14. A Probabilistic Approach to Examine the Effect of Chemistry Variations on Distortion During Industrial Gas Carburizing

    Science.gov (United States)

    Sahay, Satyam S.; Deshmukh, Vinayak; El-Zein, Mohamad

    2013-07-01

    Industrial carburizing operations have been traditionally simulated for several decades by solving the diffusion equation. However, using this deterministic approach, it is difficult to capture batch-to-batch variations in the properties attributed to process and chemistry variations. In the current study, a probabilistic approach is used to capture the variations in process parameters and alloy chemistry. The advantage of this approach is illustrated through a case study on reduction in distortion variations as well as its absolute value during the carburizing operation. Finally, some of the opportunities and challenges in the carburizing simulation are discussed.

  15. Effect of Rare Earths on Diffusion Coefficient and Transfer Coefficient of Carbon during Carburizing

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The diffusion coefficient of carbon in surface layer of steel-20 rare earth carburized at 880 ℃ and 900 ℃ for 8 h was calculated by substituting the measured layer depths into the diffusion equation. The mathematical model of the transfer coefficient of carbon was deduced based on the kinetics of weight gain during gas carburizing. The calculated results show that the main reason why the gas carburizing process is accelerated is due to the obvious increase in the diffusion coefficient and transfer coefficient of carbon resulted from the addition of RE.

  16. On the Notch Effect in Low Temperature Carburized Stainless Steel under Fatigue

    Directory of Open Access Journals (Sweden)

    Minak G.

    2010-06-01

    Full Text Available The present paper describes the fatigue behaviour of carburized notched AISI 316 austenitic stainless steel specimens. Rotary four point bending fatigue tests have been performed using carburized smooth specimens with two different values of surface rugosity and notched specimen with two different stress concentration factors Kt, of 3.55 and 6.50 and the effects of carburizing on fatigue strength and notch sensitivity were discussed. Results show a general improvement of the fatigue life due to the treatment for all the series with an apparent notch sensitivity lower than one in the case of blunt notches due to secondary effects that were singled out.

  17. On the Notch Effect in Low Temperature Carburized Stainless Steel under Fatigue

    Science.gov (United States)

    Minak, G.

    2010-06-01

    The present paper describes the fatigue behaviour of carburized notched AISI 316 austenitic stainless steel specimens. Rotary four point bending fatigue tests have been performed using carburized smooth specimens with two different values of surface rugosity and notched specimen with two different stress concentration factors Kt, of 3.55 and 6.50 and the effects of carburizing on fatigue strength and notch sensitivity were discussed. Results show a general improvement of the fatigue life due to the treatment for all the series with an apparent notch sensitivity lower than one in the case of blunt notches due to secondary effects that were singled out.

  18. Prix du pétrole : tendances à long terme et enjeux pour les biocarburants

    Directory of Open Access Journals (Sweden)

    Maisonnier Guy

    2013-09-01

    Full Text Available L’identification des grandes tendances et des paramètres critiques de l’évolution du prix du pétrole brut et des carburants est un des éléments avec la question du changement climatique pour définir des politiques publiques en matière de développement de filières de carburants alternatifs dans les transports. Le travail présenté ici essaie de proposer une grille d’analyse dans ce sens à la fois sur l’appréciation du marché à court terme (part des phénomènes géopolitiques et sur les scénarios possibles de long terme. Les notions de prix plancher (basé sur le coût marginal de production et de prix plafond (coût de solutions alternatives ou de substitution sont explicitées comme éléments définissant la fenêtre de variation des prix du pétrole brut sur un marché international. Des scénarios sur les changements possibles de l’offre (par exemple sur les bruts non conventionnels et de la demande (sous contrainte CO2 sont présentés pour évaluer cette fourchette possible : de 80 à 160 $/b en dollar constant. Les scénarios des prix des carburants et particulièrement celui du gazole sont ensuite déduits de cette analyse, à partir desquels sont positionnés les prix des biocarburants (ici issus des huiles végétales et donc les enjeux de leur compétitivité économique hors mécanismes d’incitation.

  19. ARC Code TI: Pour

    Data.gov (United States)

    National Aeronautics and Space Administration — Pour is a general-purpose information service framework designed to accommodate a wide variety of information types with support for high volume, low frequency...

  20. Deformation and fatigue behaviors of carburized automotive gear steel and predictions

    Directory of Open Access Journals (Sweden)

    Bonglae Jo

    2016-07-01

    Full Text Available The fatigue behavior of carburized components such as automotive transmission gears is very complex due to hardness and microstructure difference, residual stresses and multi-axial stress states developed between the case and the core. In addition, automotive gears in service, commonly used in helical type, are actually subjected to complex stress conditions such as bending, torsion, and contact stress states. This study presents experimental and analytical results on deformation behavior of carburized steels, widely used in automotive gears, under cyclic stress conditions including axial and torsion loadings. Axial fatigue tests and rotating bending fatigue tests are also included. Predictions of cyclic deformation and fatigue behaviors of the carburized steel with two-layer model are compared with experimental results. The carburized steel investigated in this study exhibited cyclic softening under both axial loading and torsional loading. Predicted results with simple two-layer model for the cyclic deformation and fatigue behaviors were comparatively similar to the experimental data.

  1. Modeling of Carbon Concentration Profile Development During Both Atmosphere and Low Pressure Carburizing Processes

    Science.gov (United States)

    Wei, Y.; Zhang, L.; Sisson, R. D.

    2013-07-01

    Heat treaters need an effective simulation tool to predict the carburization performance of a variety of steels. The tool is needed to not only predict the carbon profile but also optimize the process in terms of the cycle time and the total cost. CarbToolhas been developed to meet these needs for gas and vacuum carburization. In this article, CarbToolpredictions were compared with industrial experimental results for three types of steels (AISI 8620, 5120, and 4320), heat treated by both gas and vacuum carburizing processes. Based on the agreement of model predictions and experimental results, it is found that CarbToolcould be used to predict the carbon concentration profile for a variety of alloys in both gas and vacuum carburizing processes.

  2. Structure-phase states of the nickel surface layers after electroexplosive carburizing

    Institute of Scientific and Technical Information of China (English)

    Budovskikh; E.; A.; Bagautdinov; A.; Y.; Ivanov; Yu.; F.; Martusevich; E.; V.; Gromov; V.; E.

    2005-01-01

    The layer by layer study of the structure-phase states of the nickel surface layer carburizing with use the phenomena of the electrical explosion has conducted by the method TEM of the fine foils.……

  3. Wettability Modification for Biosurface of Titanium Alloy by Means of Sequential Carburization

    Institute of Scientific and Technical Information of China (English)

    Yong Luo; Shirong Ge; Zhong-min Jin

    2009-01-01

    Microporous titanium carbide coating was successfully synthesized on medical grade titanium alloy by using sequential carburization. Changes in the surface morphology of titanium alloy occasioned by sequential carburization were characterized and the wettability characteristics were quantified. Furthermore, the dispersion forces were calculated and discussed. The results indicate that sequential carburization is an effective way to modify the wettability of titanium alloy. After the carburization the surface dispersion force of titanium alloy increased from 76.5 × 10-3 J·m-2 to 105.5 × 10-3 J·m-2, with an enhancement of 37.9 %. Meanwhile the contact angle of titanium alloy decreased from 83° to 71.5°, indicating a significant improvement of wettability, which is much closer to the optimal water contact angle for cell adhesion of 70°.

  4. Computational Evaluation of Cyclic Strength of Carburized Gears from Heat-Resistant Steels

    Science.gov (United States)

    Semenov, M. Yu.

    2014-11-01

    An advanced model for computing the fatigue bending strength of gears fabricated from a complexly alloyed heat-resistant steel 16Kh3NVFMB-Sh (VKS-5) subjected to vacuum carburizing in acetylene is suggested. The model matches experimental data satisfactorily and has been used to develop a mode for vacuum carburizing of gears from the heat-resistant steel to provide a high fatigue resistance.

  5. Surface properties and activation energy of superplastically carburized duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Ahamad, Nor Wahida, E-mail: wahida_um@yahoo.com [Department of Mechanical and Materials Engineering, Faculty of Engineering, University Malaya, Lembah Pantai, 50603 Kuala Lumpur (Malaysia); Jauhari, Iswadi, E-mail: iswadi@um.edu.my [Department of Mechanical and Materials Engineering, Faculty of Engineering, University Malaya, Lembah Pantai, 50603 Kuala Lumpur (Malaysia); Azis, Sharidah Azuar Abdul, E-mail: sharidah_azuar@yahoo.com [Department of Mechanical and Materials Engineering, Faculty of Engineering, University Malaya, Lembah Pantai, 50603 Kuala Lumpur (Malaysia); Aziz, Nur Hafizah Abd, E-mail: phiza_aziz@yahoo.com [Department of Mechanical and Materials Engineering, Faculty of Engineering, University Malaya, Lembah Pantai, 50603 Kuala Lumpur (Malaysia)

    2010-08-01

    A new surface carburizing technique which combines superplastic phenomenon and carburizing process called superplastic carburizing (SPC) was introduced and compared with conventional carburizing (CC) process. Thermomechanically treated duplex stainless steel (DSS) with a fine grain microstructure that exhibits superplasticity was used as the superplastic material. SPC was carried out at temperatures of 1198-1248 K and a compression rate of 1 x 10{sup -4} s{sup -1} for various durations. Metallographic studies revealed that a carbon layer with a uniform, dense and smooth morphology formed on all carburized specimens. The case depth of the carbon layer was between 50.8 and 159.1 {mu}m. A remarkable increase in surface hardness was observed in the range 389.9-1129.0 HV. Activation energy for SPC was determined as 183.4 kJ mol{sup -1}, which is lower compare to CC process. The results indicate that SPC accelerates the diffusion of carbon atoms into the surface of DSS, thus increasing the thickness of the carburized layer and the surface hardness, at lower activation energy.

  6. Influence of vacuum carburizing treatment on fatigue crack growth characteristic in DSG2

    Directory of Open Access Journals (Sweden)

    K. Nambu

    2015-10-01

    Full Text Available The aim of this research is to clarify the influence of vacuum carburizing on the fatigue-crack progress characteristics of DSG2 steel. The test specimen tempering material (QT material and vacuum carburizing material (VC material has been used. The fatigue-crack progress was examined by subjecting the samples to four-point bending. The loading-capacity fixed experiment was done using a maximum load of Pmax = 4000– 7000 N. The ΔK fixed experiment was done using a load of ΔK = 18–36 MPa√m. The crack progress speed of VC material fell, after the high crack progress speed was shown, and after it showed the minimum, it showed the tendency to go up again. This is considered to be what is depended on the compressive residual stress given to the carburizing layer. From this, it is thinkable that there is a crack progress depression effect in a carburizing layer. In VC material, a carburizing layer has a crack progress depression effect from a plunger-helix bottom to about 2.6 mm, and it turned out that it is larger than an effective carburizing layer. Moreover, in each ΔK, it was shown that depression effect revelation differs and the crack progress process accompanying it was able to be shown typically.

  7. Carbide precipitation in austenitic stainless steel carburized at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, F. [Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106-7204 (United States)]. E-mail: frank.ernst@case.edu; Cao, Y. [Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106-7204 (United States); Michal, G.M. [Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106-7204 (United States); Heuer, A.H. [Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106-7204 (United States)

    2007-04-15

    Low-temperature gas-phase carburization can significantly improve the surface mechanical properties and corrosion resistance of austenitic stainless steel by generating a single-phase 'case' with concentrations of interstitially dissolved carbon exceeding the equilibrium solubility limit by orders of magnitude. Upon prolonged treatment, however, carbides (mostly {chi}, M{sub 5}C{sub 2}) can precipitate and degrade the properties. High-resolution and spatially resolved analytical transmission electron microscopy revealed the precise carbide-austenite orientation relationship, a highly coherent interface, and that precipitation only occurs when (i) the carbon-induced lattice expansion of the austenite has reached a level that substantially reduces volume-misfit stress and (ii) diffusional transport of nickel, chromium, and iron - enhanced by structural defects - can locally reduce the nickel concentration to the solubility limit of nickel in {chi}-carbide.

  8. An investigation of rolling-sliding contact fatigue damage of carburized gear steels

    Science.gov (United States)

    Kramer, Patrick C.

    The goal of this study was to evaluate the differences in RSCF performance between vacuum and gas carburized steels as well as to investigate the evolution of damage (wear and microstructure changes) leading to pitting. Vacuum and gas carburizing was performed on two gear steels (4120 and 4320) at 1010°C. The carburized specimens were tested in the as-carburized condition using a RSCF machine designed and built at the Colorado School of Mines. The tests were conducted at 3.2 GPa nominal Hertzian contact stress, based on pure rolling, 100°C, and using a negative twenty percent slide ratio. Tests were conducted to pitting failure for each condition for a comparison of the average fatigue lives. Pure rolling tests were also conducted, and were suspended at the same number of cycles as the average RSCF life for a comparison of fatigue damage developed by RCF and RSCF. Incremental tests were suspended at 1,000, 10,000, 100,000, and 200,000 cycles for the vacuum carburized steels to evaluate the wear and damage developed during the initial cycles of RSCF testing and to relate the wear and damage to pitting resistance. Incremental damage was not investigated for gas carburizing due to the limited number of available specimens. The vacuum carburized samples showed a decreased pitting fatigue resistance over the gas carburized samples, possibly due to the presence of bainite in the vacuum carburized cases. Pitting was observed to initiate from surface micropitting and microcracking. A microstructural change induced by contact fatigue, butterflies, was shown to contribute to micropitting and microcracking. Incremental testing revealed that the formation of a microcrack preceded and was necessary for the formation of the butterfly features, and that the butterfly features developed between 10,000 and 100,000 cycles. The orientation and depth of butterfly formation was shown to be dependent upon the application of traction stresses from sliding. RSCF butterflies formed

  9. Prediction du transfert thermique parietal pour la chambre de combustion d'une turbine a gaz

    Science.gov (United States)

    Gosselin, Pierre

    Des travaux ont demontre que la temperature de paroi pouvait etre predite avec precision (+/-6 a 10%) pour une chambre de combustion a pleine-echelle. Pour les resultats obtenus d'une autre chambre, aussi identique mais de plus petit diametre, la prediction de temperature de paroi n'offrait pas la meme precision de calcul. Cette etude est limitee aux turbines aeronautiques. L'objectif a ete de reevaluer globalement la prediction de la temperature de paroi d'une chambre de combustion de type GHOST a la lumiere des resultats obtenus des programmes experimentaux, tout en prenant en consideration l'influence des differents types de carburants. Par l'analyse du grand nombre de donnees experimentales, des modifications furent apportees a la methode de prediction utilisee pour les chambres a pleine echelle afin de reduire l'erreur de prediction pour les echelles a 1:2 (basse pression), 1:3 (basse pression) et 1:3 (haute pression). Une modelisation de la chambre de combustion a ete effectuee. L'analyse numerique nous a demontree que le code FLUENT/UNS predisait tres bien l'ecoulement a froid a l'interieur de la chambre de combustion GHOST echelle 1:1. La prediction etait acceptable au niveau des profils de temperature a l'interieur de la chambre. Cependant, une lacune a ete observee au niveau du modele d'evaporation du code.

  10. Holding time effect of pack carburizing on fatigue characteristic of v-notch shaft steel specimens

    Science.gov (United States)

    Supriyono, Jamasri

    2017-06-01

    The objective of this research is to study the effect of the holding times of pack carburizing process on fatigue characteristic of v-notch shaft steel specimens. The carbon source was taken from charcoal of unused mahogany. The holding times were 2, 3 and 4 hours. The fatigue tests were conducted on rotary bending machine. The specimens were made of low carbon steel of 0.17% carbon content. Pack carburizing was conducted to the specimens at 930°C. V-notch was made to present the stress concentration on the specimens. To see the effects of the carburizing in changing the material properties, the micro-structures and hardness tests along the cross sectional area of the specimens were carried out. The results showed that the holding time of the carburizing process influences the fatigue strength of the material. The longer the holding time will be the higher the fatigue strength. The increase of the fatigue strength is due to the carbon content on the surface. It was confirmed by the micro-structures and the hardness tests results. The cross sectional area of carburized material is divided into two zones i.e. surface zone and core zone. The surface zone consists of hypereutectoid, eutectoid, and hypo eutectoid sub-zone. The core zone is the same as raw material. The longer the holding time will be the deeper the surface zone.

  11. The sort of carburization and the quality of obtained cast iron

    Directory of Open Access Journals (Sweden)

    K. Janerka

    2008-12-01

    Full Text Available In the production of cast iron, the pig iron’s amount in charge material is more and more often limited, and replaced by steel scrap. That extorts the necessity of know-how the carburization and one is looking for carburizers, which ensure obtaining big carbon increment as quickly as possible with the high repeatability and the ones which ensure getting the adequate quality of cast iron. The object of presented research was definition of the influence of charge materials’ sort on the structure, course of solidification, and the effectiveness of process. The cast iron melts, which are presented below, are made only on the basis of steel scrap with portion of graphitoidal, coke and anthracite carburizers, which were added to the charge in solid. In the article one compared the carburizers in respect of their structure, chemical constitution and the effectiveness obtained during the carburization of liquid metal. The melting of cast iron, based on the special pig iron, was carried out as well. The course of melts, chemical constitution of obtained cast iron and its structure were presented. The comparison between quality distribution and the volume fraction of graphite in classes of size for the individual melts were achieved and the TDA curves were inserted.

  12. Study On The Effect Of Corrosion Behaviour Of Stainless Steel Before And After Carburizing Heat Treatment

    Science.gov (United States)

    Sulaiman, S. A.; Alias, S. K.; Ahmad, S.; Fauzi, M. H. Mohd; Ahmad, N. N.

    2016-11-01

    This study investigates the effect of corrosion behaviour of stainless steel before and after carburizing process. All samples were prepared based on the testing specification requirement and the chemical compositions of the stainless steel were obtained using spectrometer tester. Samples were then undergoing pack carburizing process by adding 50g of carbon powder as the carburizing agent. Then the samples were heated at 900 °C and 950 °C for 8 hours. To obtain corrosion rate, weight loss test was conducted and the samples were immersed in three different solutions which were distilled water, hydrochloric acid and sodium chloride. Hardness and density test were employed to measure the physical properties of the ASTM 304 stainless steel. The microstructures of all samples were observed using Olympus BX41M optical microscope. The resulting phases after each heat treatment were tested by x-ray diffraction (XRD) tester. The percentage of corrosion values, determined from this technique, showed fairly good agreement. Carburizing process produced a carburizing layer improved mechanical properties and corrosion resistance abilities

  13. Modeling Growth and Dissolution Kinetics of Grain-Boundary Cementite in Cyclic Carburizing

    Science.gov (United States)

    Ikehata, Hideaki; Tanaka, Kouji; Takamiya, Hiroyuki; Mizuno, Hiroyuki; Shimada, Takeyuki

    2013-08-01

    In vacuum carburizing of steels, short-time carburizing is usually followed by a diffusion period to eliminate the filmlike cementite ( θ GB ) grown on the austenite ( γ) grain boundary surface. In order to obtain the θ GB amount during the process, the conventional model estimates the amount of cementite ( θ) with the equilibrium fractions for local C contents within a framework of the finite difference method (FDM), which overestimates the amount of θ GB observed after several minutes of carburizing. In our newly developed model, a parabolic law is assumed for the growth of θ GB and the rate controlling process is considered to be Si diffusion rejected from θ under the isoactivity condition. In contrast, the rate constant for the dissolution of θ GB is considered to be controlled by Cr diffusion of θ. Both rate coefficients ( α) were validated using multicomponent diffusion simulation for the moving velocity of the γ/ θ interface. A one-dimensional (1-D) FDM program calculates an increment of θ GB for all grid points by the updated diffusivities and local equilibrium using coupled CALPHAD software. Predictions of the carbon (C) profile and volume fraction of cementite represent the experimental analysis much better than the existing models, especially for both short-time carburization and the cyclic procedure of carburization and diffusion processes.

  14. Influence of Al on the microstructure and carburization performance of a Ni-based alloy coating

    Energy Technology Data Exchange (ETDEWEB)

    Cangue, Feliciano Jose Ricardo, E-mail: fcangue@yahoo.com [Federal University of Parana, Centro Politecnico, s/n - Bairro Jardim das Americas, Curitiba, Parana, Cx P. 19011, CEP: 81531-990 (Brazil); D' Oliveira, Ana Sofia Climaco Monteiro, E-mail: sofmat@ufpr.br [Mechanical Engineering Department, Federal University of Parana, Centro Politecnico, s/n - Bairro Jardim das Americas, Curitiba, Parana, Cx P. 19011, CEP: 81531-990 (Brazil)

    2010-04-15

    Carburization is a degradation mechanism involving the diffusion of carbon into a metal alloy and its accumulation on the surface. Coke forms on the internal walls of crude oil refining equipment and adversely affects its efficiency and service life. In an attempt to enhance the service life of materials exposed to these aggressive environments, this work investigated the development of a protective coating to reduce the diffusion of carbon into the surfaces of components. Coatings were tailored by mixing the atomized Ni alloy (Hastealloy C) with 5 wt% and 15 wt% Al powders and deposited by Plasma Transferred Arc hardfacing. Pack carburizing was carried out at 650 deg. C and 850 deg. C for 6 h, and temperature stability was tested in an air furnace to evaluate the performance of the coatings. Characterization included measurement of Vickers microhardness profiles and microstructure analysis by optical and scanning electron microscopy and X-ray diffraction. The good weldability of the original Ni-based alloy was not altered by the presence of Al. Richer Al coatings developed ordered aluminide compounds in a Ni matrix and exhibited increased hardness and dilution. Exposure to temperatures of 650 deg. C and 850 deg. C in an air furnace and to a carburizing environment neither compromised coating hardness nor produced a carburizing layer, although carbides were identified at the top surface. Our results will be of benefit in the development of an alternative solution for the protection of components operating in carburizing environments.

  15. DECREASING HEAT TREATMENT COST OF SURFACE HARDENED MACHINE PARTS BY CASE CARBURIZATION

    Directory of Open Access Journals (Sweden)

    Ahmet Çetin CAN

    1997-03-01

    Full Text Available Machine parts are surface hardened to increase fatigue strength and wear resistance. Carburization is the most common surface hardening process in practice. In order to have optimum properties, a machine part must have certain hardness depth. To obtain required hardness depth, the parts must be kept in a carburizing medium at certain temperature for certain time. As the time and temperature is increased hardness depth increases. In practice, carburization temperature is about 930 °C. Machine parts are kept at this temperature for required time depending on required hardness depth. The increase of temperature reduces treatment time, considerably. But, heat treaters do not tend to use high temperatures due to the concern of distortion of parts, and deterioration of mechanical properties. In this study, the increase of temperature for reducing carburization time in salt bath, and consequently change of mechanical properties have been investigated using DIN C20 case carburization steel. As a result of experiments, it was found that mechanical properties were not effected negatively.

  16. Isotope ratio measurements of pg-size plutonium samples using TIMS in combination with "multiple ion counting" and filament carburization

    Science.gov (United States)

    Jakopic, Rozle; Richter, Stephan; Kühn, Heinz; Benedik, Ljudmila; Pihlar, Boris; Aregbe, Yetunde

    2009-01-01

    A sample preparation procedure for isotopic measurements using thermal ionization mass spectrometry (TIMS) was developed which employs the technique of carburization of rhenium filaments. Carburized filaments were prepared in a special vacuum chamber in which the filaments were exposed to benzene vapour as a carbon supply and carburized electrothermally. To find the optimal conditions for the carburization and isotopic measurements using TIMS, the influence of various parameters such as benzene pressure, carburization current and the exposure time were tested. As a result, carburization of the filaments improved the overall efficiency by one order of magnitude. Additionally, a new "multi-dynamic" measurement technique was developed for Pu isotope ratio measurements using a "multiple ion counting" (MIC) system. This technique was combined with filament carburization and applied to the NBL-137 isotopic standard and samples of the NUSIMEP 5 inter-laboratory comparison campaign, which included certified plutonium materials at the ppt-level. The multi-dynamic measurement technique for plutonium, in combination with filament carburization, has been shown to significantly improve the precision and accuracy for isotopic analysis of environmental samples with low-levels of plutonium.

  17. Effect of Carburizing and Hardening Temperature on the Endurance of Forming Dies from Steel R6M5

    Science.gov (United States)

    Stepankin, I. N.; Ken'ko, V. M.; Boiko, A. A.

    2013-07-01

    Results of a study of the effect of carburizing of the forming surfaces of cold upset dies from high-speed steel R6M5 and of the hardening temperature on the structure and properties of the dies are presented. It is shown that the hardness and endurance of the carburized tools can be raised by hardening from lower temperatures.

  18. Evaluation of the carburized surface of steels with Magnetic Barkhausen Noise; Avaliacao de superficie cementada de acos com efeito Barkhausen

    Energy Technology Data Exchange (ETDEWEB)

    Campos, M.F. de; Santos, R.; Silva, F.S. da; Ribeiro, S.B.; Lins, J.F.C., E-mail: mcampos@metal.eeimvr.uff.b [Universidade Federal Fluminense (PUVR/UFF), Volta Redonda, RJ (Brazil). Polo Universitario de Volta Redonda; Franco, F.A.; Padovese, L.R. [Universidade de Sao Paulo (EPUSP), SP (Brazil). Escola Politecnica

    2010-07-01

    Steels with different carbon content, 0.11%C and 0.48%C were submitted to a heat treatment for carburization in the surface. The samples were analyzed in the conditions: normalized, only carburized and carburized and quenched as received. The Magnetic Barkhausen Noise (MBN) was measured in all samples. A better understanding of the relation between microstructure and MBN is of large interest for nondestructive characterization. X-ray diffraction (XRD) has revealed large peak broadening for the samples carburized and quenched, which have martensite. This is due to the high density of dislocations and high internal stress in the martensite. It is also found that the MBN peaks are quite distinct for the samples with martensite, which present nanocrystalline structure. When martensite is present, domain rotation occurs more significantly, reducing the permeability and the MBN envelope signal intensity. MBN is a suitable method for non-destructive evaluation of the quality of the carburization process. (author)

  19. Mathematical modeling and validation of the carburizing of low carbon steels

    Science.gov (United States)

    García Mariaca, A.; Cendales, E. D.; Chamarraví, O.

    2016-02-01

    This paper shows the mathematical modeling of heat and mass transfer in transient state of cylindrical bars of low carbon steel subjected to carburizing process. The model solution for the two phenomena was performed using a one-dimensional analysis in the radius direction, using the numerical method of finite differences; also a sensitivity analysis by varying the coefficient of convective heat transfer (h) is performed. The modeling results show that this carburization steel is strongly dependent on h. These results suggest that if it can increase the value of h in this kind of process could reduce the time of process for this heat treatment. Additionally, an experimental procedure was established by carburization of a steel AISI SAE 1010, which develops cementing solid phase and the specimen steel and micrographic hardness profiles obtained from samples of the specimen analysis was performed, to determine the penetration depth of the carbon and validate this result over the values obtained by the computer model.

  20. The advantages of Low Pressure Carburizing in the Heat Treatment Subcontracting Business

    Institute of Scientific and Technical Information of China (English)

    Guy PRUNEL; Bruno STAUDER

    2004-01-01

    Low Pressure Carburizing (LPC) was introduced in the 90's in the western Europe Heat Treatment business,mainly for in-house applications where it was especially appreciated for carburizing of transmission parts. However the success of the LPC units installed for gears carburizing in the automotive industry has hindered the development of the process in other fields - like subcontracting business -, where its advantages deserve to be enlightened.After a brief review of the principle of the process, the interest of its classical application to transmission parts is described,underlining peculiarly the reduction of the distortion observed when LPC is associated with high pressure gas quenching.Then the less-known advantages of the LPC process, like the high accuracy and reproducibility of the results, the modeling possibility and the simulation easiness, the case-depth uniformity and the full flexibility of the units are considered,showing how they can be beneficial to subcontracting business.

  1. Carbon supersaturation due to paraequilibrium carburization: Stainless steels with greatly improved mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Michal, G.M. [Department of Materials Science and Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106 7204 (United States)]. E-mail: gmm3@case.edu; Ernst, F. [Department of Materials Science and Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106 7204 (United States)]. E-mail: frank.ernst@case.edu; Kahn, H. [Department of Materials Science and Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106 7204 (United States)]. E-mail: harold.kahn@case.edu; Cao, Y. [Department of Materials Science and Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106 7204 (United States); Oba, F. [Department of Materials Science and Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106 7204 (United States); Agarwal, N. [Department of Materials Science and Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106 7204 (United States); Heuer, A.H. [Department of Materials Science and Engineering, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106 7204 (United States)]. E-mail: heuer@case.edu

    2006-04-15

    Low-temperature gas-phase carburization has been used to generate very high surface interstitial carbon contents, up to {approx}12 at.%, in a 316L austenitic stainless steel. The high interstitial content leads to substantial surface hardening (Vickers hardness of {approx}12 GPa, equivalent to Rockwell C of {approx}71.5) with essentially no loss of ductility and with no carbide formation. Residual compressive stresses accompanying the low-temperature carburization enhance the high-cycle fatigue resistance, while the hardening enhances the wear resistance. These remarkable improvements in mechanical properties arise because the carburization is carried out at temperatures where 'paraequilibrium', rather than conventional thermodynamic equilibrium, determines the phase composition; paraequilibrium can be realized under conditions where substitutional solutes such as Cr and Ni are immobile whereas interstitial solutes such as carbon are not.

  2. Effect of Carburization on the Mechanical Properties of Biomedical Grade Titanium Alloys

    Institute of Scientific and Technical Information of China (English)

    Yong Luo; Haibo Jiang; Gang Cheng; Hongtao Liu

    2011-01-01

    Titanium cermets were successfully synthesized on the surface of biomedical grade titanium alloys by using sequential carburization method. The mechanical properties such as hardness, fracture toughness and plasticity were measured to estimate the potential application of titanium cermets. The results show that after carburization the surface hardness of titanium cermets was 778 HV, with a significant improvement of 128% compared with that of titanium alloys. In addition, the fracture toughness of titanium cermets was 21.5×106 Pa·m1/2, much higher than that of other ceramics. Furthermore, the analysis of the loading-unloading curve in the nanoindentation test also indicates that the plasticity of titanium cermet reached 32.1%, a relatively high value which illustrates the combination of the metal and ceramics properties. The results suggest that sequential carburization should be an efficient way to produce titanium cermets with hard surface, high toughness and plasticity.

  3. Numerical Simulation of Reaction-Diffusion during Carburization of HK40 Steel

    Institute of Scientific and Technical Information of China (English)

    Meili ZHU; Qiang XU; Junshan ZHANG

    2003-01-01

    Two types of carbides M23C6 and M7C3 precipitate orderly as carbon concentration in a high Cr-Ni austenitic steel increases during carburization process. The mathematical model that describes diffusion of carbon and the precipitation of M23C6 and M7C3 has been studied. A criterion to judge when the transformation of M23C6 to M7C3 is over and M7C3 precipitates directly has been given in simulated calculation. By applying the model, the carburization of HK40 steel has been calculated by means of finite difference computation techniques. The pack carburization tests for the HK40 steel have been carried out at 1273 K. The comparison between the experimental and the calculated results show acceptable agreement.

  4. Offre pour nos membres

    CERN Multimedia

    Staff Association

    2016-01-01

    Walibi Rhône-Alpes accueille son événement Halloween FreakShow le week-end du 15 et 16 octobre puis tous les jours du 20 octobre au 02 novembre 2016 ! ouverture prolongée jusqu’à 19h et feu d’artifices chaque soir 29, 30 et 31 octobre ! Loup-garou show; 1 labyrinthe; jeu de piste sur le parc (et nombreux lots à gagner); animations (sculpture sur citrouilles et maquillage) et d'autres surpises ! Tarifs pour nos membres : Entrée "Zone terrestre": 23 € au lieu de 29 €. Entrée gratuite pour les enfants de moins de 3 ans, avec accès aux attractions limité. Parking gratuit.

  5. Offre pour nos membres

    CERN Multimedia

    Staff Association

    2016-01-01

    Walibi Rhône-Alpes accueille son événement Halloween FreakShow le week-end du 15 et 16 octobre puis tous les jours du 20 octobre au 02 novembre 2016 ! ouverture prolongée jusqu’à 19h et feu d’artifices chaque soir 29, 30 et 31 octobre ! Loup-garou show; 1 labyrinthe; jeu de piste sur le parc (et nombreux lots à gagner); animations (sculpture sur citrouilles et maquillage) et d'autres surpises ! Tarifs pour nos membres : Entrée "Zone terrestre": 23 € au lieu de 29 €. Entrée gratuite pour les enfants de moins de 3 ans, avec accès aux attractions limité. Parking gratuit.

  6. A numerical model for vacuum carburization of an automotive gear ring

    Science.gov (United States)

    Kim, Dong-Wan; Cho, Yi-Gil; Cho, Hoon-Hwe; Kim, Sung-Hwan; Lee, Won-Beom; Lee, Myoung-Gyu; Han, Heung Nam

    2011-12-01

    A vacuum carburizing-heat treatment of an annulus gear ring is simulated via a carburized predictive finite element model that accounts for both heat transfer and carbon diffusion. Profiles of carbon concentration along the depth of the gear ring were calculated and are congruent with measured values, which were obtained by a glow discharge spectrometer (GDS). While sensitive to carbon content, rigorous observation of the microstructures in the gear ring after heat treatment was attempted by transmission electron microscopy (TEM). The finial various martensitic microstructures in several parts of the gear ring may be well explained on the basis of the calculated carbon concentration.

  7. Influence of vacuum carburizing treatment on fatigue crack growth characteristic in DSG2

    OpenAIRE

    K. Nambu; Egami, N.

    2015-01-01

    The aim of this research is to clarify the influence of vacuum carburizing on the fatigue-crack progress characteristics of DSG2 steel. The test specimen tempering material (QT material) and vacuum carburizing material (VC material) has been used. The fatigue-crack progress was examined by subjecting the samples to four-point bending. The loading-capacity fixed experiment was done using a maximum load of Pmax = 4000– 7000 N. The ΔK fixed experiment was done using a load of ΔK = 18...

  8. The Effect of the Quenching Method on the Deformations Size of Gear Wheels after Vacuum Carburizing

    Directory of Open Access Journals (Sweden)

    Dybowski K.

    2016-06-01

    Full Text Available This paper presents a comparison of the deformations and residual stresses in gear wheels after vacuum carburizing process with quenching in high-pressure nitrogen and oil. The comparison was made on a medium-sized gear wheels, made of AMS6265 (AISI 9310 steel. This steel is applied in the aerospace industry for gears. The study has provided grounds for an assessment of the effect of the method of quenching on the size of deformations. Compared to oil quenching, high-pressure gas quenching following vacuum carburizing resulted in more uniform and smaller deformations.

  9. 圆锥从动齿轮的渗碳工艺探析%Explore and Analysis of Carburization Process for Driven Bevel Gear Carburizing

    Institute of Scientific and Technical Information of China (English)

    马录

    2011-01-01

    通过多次试验,解决了圆锥从动齿轮渗碳后淬火变形及二次压淬时出现的氧化脱碳问题,并提出了合理建议.%The problems of quenching deformation, oxidation and decarburization of driven bevel gear after carburizing and then the second pressure quenching were solved through several experiments, and the reasonable proposal was put forward.

  10. Carburization and heat treatment to cause carbide precipitation in gamma/gamma prime-delta eutectic alloys

    Science.gov (United States)

    Tewari, S. N.; Dreshfield, R. L.

    1977-01-01

    In an attempt to improve their longitudinal shear strength, several directionally solidified eutectic alloy compositions with minor element modifications were pact, carburized, and heat treated to provide selective carbide precipitation at the cell and grain boundaries. The directionally solidified Ni-17.8 Nb-6Cr-2.5Al-3Ta (weight percent) alloy was selected for the shear strength evaluation because it showed the shallowest delta-denuded zone at the carburized surface. The carburization-carbide precipitation treatment, however, did not appear to improve the longitudinal shear strength of the alloy.

  11. Ni-WC composite coatings by carburizing electrodeposited amorphous and nanocrystalline Ni-W alloys

    Science.gov (United States)

    Latif, Saadia; Mehmood, Mazhar; Ahmad, Jamil; Aslam, Muhammad; Ahmed, Maqsood; Zhang, Zhi-dong

    2010-03-01

    In situ formation of tungsten carbide in the matrix of FCC nickel has been achieved by carburizing of the electrodeposited Ni-W alloy coatings. The size of the carbide particles ranges between 100 and 500 nm. The carbide phase is also present in the form of very small precipitates inside the nickel grains. The size of such precipitates is between 10 and 40 nm. The carburizing environment was created by introducing a flowing mixture of vaporized 95.5% alcohol (0.25 ml/min, liquid) and argon (0.5 L/min, gas) into the carburizing furnace. Supersaturated nature of electrodeposited amorphous and nanocrystalline alloys, in addition to high diffusivity, have been attributed for the formation of carbide phase in the deposits at a temperature range of 700-850 °C. The carbide-metal interface is clean and the composite coatings are compact. Hardness values up to about 1100 KHN are achieved. Hardness increases with tungsten content and carburizing temperature.

  12. About Reverted Austenite in Carburized Layers of Low-Carbon Martensitic Steels

    Science.gov (United States)

    Ivanov, A. S.; Bogdanova, M. V.; Vylezhnev, V. P.

    2015-05-01

    Processes of surface hardening in low-carbon martensitic steel 24Kh2G2NMFTB under carburizing and subsequent quenching from the intercritical temperature range are studied. Special features of formation of reverted austenite with high strength and stability are considered.

  13. Experimental Study on Vacuum Carburizing Process for Low-Carbon Alloy Steel

    Science.gov (United States)

    Wei, Shaopeng; Wang, Gang; Zhao, Xianhui; Zhang, Xiaopeng; Rong, Yiming

    2013-10-01

    As a low-carbon alloy steel, 20Cr2Ni4A steel has an excellent mechanical properties. It has been used for producing heavy-duty gears, which require good wear and fatigue resistance. The vacuum carburizing process can improve the quality of gears and extend the service life. In this article, a complete heat-treatment process for 20Cr2Ni4A, with carburizing, tempering, quenching and cryogenic steps involved, was proposed. A numerical method was employed to design the carburizing step. The carburized samples were characterized by analysis of carbon profile, surface-retained austenite content, microstructure, and hardness profile. A good microstructure was obtained with acicular-tempered martensite, less-retained austenite, fine granular-dispersed carbides, and was oxide free. The final surface hardness was 64.2HRC, and the case depth was 0.86 mm, which meet the requirements of products. The relationships among process, performance, and microstructure were investigated to understand the inner connection.

  14. Ni-WC composite coatings by carburizing electrodeposited amorphous and nanocrystalline Ni-W alloys

    Energy Technology Data Exchange (ETDEWEB)

    Latif, Saadia [National Centre for Nanotechnology, Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad 45650 (Pakistan); Mehmood, Mazhar, E-mail: mazhar@pieas.edu.pk [National Centre for Nanotechnology, Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad 45650 (Pakistan); Ahmad, Jamil; Aslam, Muhammad [National Centre for Nanotechnology, Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad 45650 (Pakistan); Ahmed, Maqsood [Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); Zhang Zhidong [Institute of Metals Research, Chinese Academy of Science, Shenyang (China)

    2010-03-01

    In situ formation of tungsten carbide in the matrix of FCC nickel has been achieved by carburizing of the electrodeposited Ni-W alloy coatings. The size of the carbide particles ranges between 100 and 500 nm. The carbide phase is also present in the form of very small precipitates inside the nickel grains. The size of such precipitates is between 10 and 40 nm. The carburizing environment was created by introducing a flowing mixture of vaporized 95.5% alcohol (0.25 ml/min, liquid) and argon (0.5 L/min, gas) into the carburizing furnace. Supersaturated nature of electrodeposited amorphous and nanocrystalline alloys, in addition to high diffusivity, have been attributed for the formation of carbide phase in the deposits at a temperature range of 700-850 deg. C. The carbide-metal interface is clean and the composite coatings are compact. Hardness values up to about 1100 KHN are achieved. Hardness increases with tungsten content and carburizing temperature.

  15. Rolling Contact Fatigue Performances of Carburized and High-C Nanostructured Bainitic Steels

    Directory of Open Access Journals (Sweden)

    Yanhui Wang

    2016-11-01

    Full Text Available In the present work, the nanostructured bainitic microstructures were obtained at the surfaces of a carburized steel and a high-C steel. The rolling contact fatigue (RCF performances of the two alloy steels with the same volume fraction of undissolved carbide were studied under lubrication. Results show that the RCF life of the carburized nanostructured bainitic steel is superior to that of the high-C nanostructured bainitic steel in spite of the chemical composition, phase constituent, plate thickness of bainitic ferrite, hardness, and residual compressive stress value of the contact surfaces of the two steels under roughly similar conditions. The excellent RCF performance of the carburized nanostructured bainitic steel is mainly attributed to the following reasons: finer carbide dispersion distribution in the top surface, the higher residual compressive stress values in the carburized layer, the deeper residual compressive stress layer, the higher work hardening ability, the larger amount of retained austenite transforming into martensite at the surface and the more stable untransformed retained austenite left in the top surface of the steel.

  16. Rolling Contact Fatigue Performances of Carburized and High-C Nanostructured Bainitic Steels.

    Science.gov (United States)

    Wang, Yanhui; Zhang, Fucheng; Yang, Zhinan; Lv, Bo; Zheng, Chunlei

    2016-11-25

    In the present work, the nanostructured bainitic microstructures were obtained at the surfaces of a carburized steel and a high-C steel. The rolling contact fatigue (RCF) performances of the two alloy steels with the same volume fraction of undissolved carbide were studied under lubrication. Results show that the RCF life of the carburized nanostructured bainitic steel is superior to that of the high-C nanostructured bainitic steel in spite of the chemical composition, phase constituent, plate thickness of bainitic ferrite, hardness, and residual compressive stress value of the contact surfaces of the two steels under roughly similar conditions. The excellent RCF performance of the carburized nanostructured bainitic steel is mainly attributed to the following reasons: finer carbide dispersion distribution in the top surface, the higher residual compressive stress values in the carburized layer, the deeper residual compressive stress layer, the higher work hardening ability, the larger amount of retained austenite transforming into martensite at the surface and the more stable untransformed retained austenite left in the top surface of the steel.

  17. Rational Formulation of Alternative Fuels using QSPR Methods: Application to Jet Fuels Développement d’un outil d’aide à la formulation des carburants alternatifs utilisant des méthodes QSPR (Quantitative Structure Property Relationship: application aux carburéacteurs

    Directory of Open Access Journals (Sweden)

    Saldana D.A.

    2013-06-01

    from the literature, from experimental measurements and from molecular simulations for complex molecules. The interest of such models in the selection of molecules can be shown for example by the trade-off between cold flow properties and density of paraffinic compounds. If the carbon chain length is too high, the cold flow properties are compromised. One solution can be to increase branching or incorporate fuel base with good cold flow properties such as naphthenic or aromatic compounds. However, this leads to a decrease in density below the jet fuel specification. Again, using naphthenic of alkyl-aromatic compounds produced from biomass can help. Le développement des carburants alternatifs est en plein essor, notamment dans le domaine aéronautique. Cela se concrétise par la possibilité d’incorporer jusqu’à 50 % de carburants de synthèse de type Fischer- Tropsch (FT ou hydroprocessed esters and fatty acids (HEFA dans du carburéacteur. De même, ces carburants paraffiniques se développent pour le transport terrestre en parallèle des biocarburants à base d’esters ou d’alcool actuellement disponibles. La formulation de ces carburants alternatifs est actuellement basée sur une sélection des produits via des critères physiques. L’atteinte de ces critères se fait souvent par des formulations empiriques et ce type de fonctionnement ne s’avère pas très efficace et montre ses limites. En effet, les carburants alternatifs présentent des propriétés chimiques qui peuvent être différentes en fonction du procédé (répartition n-paraffines/iso-paraffines, longueur de chaîne, ramification, etc. et donc modulable. Ainsi, une nouvelle voie pourrait être envisagée visant à déterminer par le calcul, la molécule (ou le mélange de molécules la plus à même de répondre au cahier des charges du carburant, puis à étudier ou à optimiser les voies de synthèse permettant d’accéder à ces produits. Le travail présenté a pour objectif le d

  18. Enhanced wear and corrosion resistance of plasma electrolytic carburized layer on T8 carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jie; Wang, Bin; Zhang, Yifan; Liu, Run [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Xia, Yuan; Li, Guang [Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Xue, Wenbin, E-mail: xuewb@bnu.edu.cn [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2016-03-01

    A hardening layer of 70 μm on T8 carbon steel was fabricated by plasma electrolytic carburizing (PEC) in glycerol solution at 380 V with 3 min treatment. The discharge process was characterized using optical emission spectroscopy (OES), and the electron temperature in plasma envelope was determined. Meanwhile, diffusion coefficient of carbon was calculated on the basis of carbon concentration profile. The tribological property of carburized steel under dry sliding against ZrO{sub 2} ball was measured by a ball-disc friction and wear tester. The corrosion behaviors were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). It was found that the carburized layer mainly contained α-Fe and Fe{sub 3}C phases with maximum hardness of 620 HV. The PEC treatment significantly decreased the friction coefficient from 0.4 to 0.1. The wear rate of PEC treated steel was about 5.86 × 10{sup −6} mm{sup 3}/N·m, which was less than 1/4 of T8 steel substrate. After PEC treatment, the wear and corrosion resistance of T8 steel were improved. Particularly, the pitting corrosion of steel substrate was obviously suppressed. - Highlights: • Electron temperature in plasma electrolytic carburizing process is determined. • Diffusion coefficient of carbon in PEC is higher than conventional carburizing. • Wear and corrosion resistance of T8 steel are both improved after PEC treatment. • Pitting corrosion of steel substrate is obviously suppressed by PEC treatment.

  19. Mechanical and Metallurgical Evaluation of Carburized, Conventionally and Intensively Quenched Steels

    Science.gov (United States)

    Giordani, T.; Clarke, T. R.; Kwietniewski, C. E. F.; Aronov, M. A.; Kobasko, N. I.; Totten, G. E.

    2013-08-01

    Steels subjected to carburizing, quenching, and tempering are widely used for components that require hardness and superficial mechanical resistance together with good core toughness. Intensive quenching is a method that includes advantages including crack prevention, increased mechanical resistance, and improvement in fatigue performance when subjected to very fast (intensive) cooling. However, achieving these advantages requires the formation of sufficiently high surface compressive residual stresses and fine grains at the core of steel components. If the cooling rate is sufficiently high after intensive quenching, then low-hardenability, killed plain carbon steels may be used instead of higher-cost, low alloy steels because compressive residual stresses are formed at the surface of steel parts. The objective of this study was to compare between carburized non-killed AISI 1020 steel samples, which were not modified by Al that were subsequently conventionally and also intensively quenched to determine the effect of quenching on achieving the necessary formation of fine grain size. For comparison, carburized AISI 8620 steel test specimens were conventionally quenched. After quenching, all test specimens were characterized by metallurgical and mechanical analyses. The results of this study showed that when the two quenching methods were compared for carburized non-killed AISI 1020 steel, intensive quenching method was found to be superior with respect to mechanical and metallurgical properties. When comparing the different steels, it was found that intensively quenched, non-killed, AISI 1020 steel yielded grain sizes which were three times greater than those obtained with conventionally quenched, carburized AISI 8620 steel. Therefore, the benefits of intensive quenching were negated. These results show that plain carbon steels must be modified by Al to make fine grains if intensively quenched plain-carbon steel is to replace alloyed AISI 8620 steel.

  20. Informatique: tous pour un ... projet

    CERN Multimedia

    Delétraz, F; Requin, J-M

    2004-01-01

    "Pour des raisons de coût et d'efficacité, les chercheurs font de plus en plus travailler ensemble des ordinateurs éparpillés sur tous les continents. Pour faire avancer la science, tous les moyens et tous les réseaux sont bons" (1 page)

  1. Nanostructural Evolution of Hard Turning Layers in Carburized Steel

    Science.gov (United States)

    Bedekar, Vikram

    The mechanisms of failure for components subjected to contact fatigue are sensitive to the structure and properties of the material surface. Although, the bulk material properties are determined by the steel making, forming and the heat treatment; the near surface material properties are altered during final material removal processes such as hard turning or grinding. Therefore, the ability to optimize, modulate and predict the near surface properties during final metal removal operations would be extremely useful in the enhancement of service life of a component. Hard machining is known to induce severely deformed layers causing dramatic microstructural transformations. These transformations occur via grain refinement or thermal phenomena depending upon cutting conditions. The aim of this work is to engineer the near surface nanoscale structure and properties during hard turning by altering strain, strain rate, temperature and incoming microstructure. The near surface material transformations due to hard turning were studied on carburized SAE 8620 bearing steel. Variations in parent material microstructures were introduced by altering the retained austenite content. The strain, strain rate and temperature achieved during final metal cutting were altered by varying insert geometry, insert wear and cutting speed. The subsurface evolution was quantified by a series of advanced characterization techniques such as transmission electron microscopy (TEM), glancing angle X-ray diffraction (GAXRD), X-ray stress evaluation and nanoindentation which were coupled with numerical modeling. Results showed that the grain size of the nanocrystalline near surface microstructure can be effectively controlled by altering the insert geometry, insert wear, cutting speed and the incoming microstructure. It was also evident that the near surface retained austenite decreased at lower cutting speed indicating transformation due to plastic deformation, while it increased at higher cutting

  2. 3d Simulation of Di Diesel Combustion and Pollutant Formation Using a Two-Component Reference Fuel Simulation 3D de la combustion et de la formation des polluants dans un moteur Diesel à injection directe en utilisant un carburant de référence à deux composants

    Directory of Open Access Journals (Sweden)

    Barths H.

    2006-12-01

    reference fuels. The contributions of the different reaction paths (thermal, prompt, nitrous, and reburn to the NO formation are shown. Finally, the importance of the mixing process for the prediction of soot emissions is discussed. En séparant calculs aérodynamiques et calculs chimiques, le modèle instationnaire de flamelet permet d'introduire des mécanismes chimiques complets qui comprennent plusieurs centaines de réactions. Ceci est indispensable pour décrire les différents processus qui ont lieu dans un moteur Diesel à injection directe (ID tels que l'auto-inflammation, la fin de la phase de prémélange partiel, la transition vers une combustion diffusive et la formation de polluants tels que les NOx et les suies. Il n'est pas nécessaire de simplifier les taux de réactions hautement non linéaires, d'autre part, la structure complète du processus de combustion est conservée. En utilisant le modèle de type Representative Interaction Flamelet (RIF, l'ensemble monodimensionnel instationnaire d'équations différentielles aux dérivées partielles est résolu en interaction avec le code CFD 3D. La solution ainsi obtenue est couplée avec les flux gazeux et le champ de mélange par l'intermédiaire de plusieurs paramètres dépendant du temps (l'enthalpie, la pression, le taux scalaire de dissipation. En retour, le modèle de flamelet fournit les concentrations moyennes des espèces chimiques, qui sont ensuite exploitées par le code CFD 3D pour calculer les champs de températures et les densités. La densité est nécessaire au code CFD 3D pour déterminer les flux turbulents et le champ de mélange. La formation des polluants est déterminée expérimentalement dans un moteur Diesel Volkswagen DI 1900. Le moteur est alimenté avec du gazole et deux carburants de référence. Un des carburants de référence est du n-décane pur. Le second est un carburant bicomposant formé de 70 % (du volume liquide de n-décane et de 30 % d'alpha-méthylnaphtalène (Idea

  3. EFFECTS OF CARBURIZING AND NITRIDING PROCESSES ON THE COST AND QUALITY OF GEARS PRODUCED WITH AISI 4140 AND 8620 STEELS

    Directory of Open Access Journals (Sweden)

    Claudio José Leitão

    2012-09-01

    Full Text Available This study compares the effects of nitriding and carburizing processes applied to gears subjected to contact stresses below 1300 MPa. The manufacturing cost, as well the depth of hardened layer and the distortion produced by two processes are analyzed. AISI 4140 gears quenched, tempered, liquid and gas nitriding and AISI 8620 gears after liquid carburizing, quenching and tempering are analyzed. The dimensional control of the gears was carried out before and after heat and thermochemical treatments. It is concluded that liquid or gas nitriding processes are about 30% more economical than liquid carburizing an also they reduce the dimensional changes. By the other hand liquid carburizing achieves greater case depth. Liquid nitriding process presents the lowest cost, dimensional changes and case depth.

  4. A study of internal oxidation in carburized steels by glow discharge optical emission spectroscopy and scanning electron microscopy

    CERN Document Server

    An, X; Rainforth, W M; Chen, L

    2003-01-01

    The internal oxidation of Cr-Mn carburizing steel was studied. Internal oxidation was induced using a commercial carburizing process. Sputter erosion coupled with glow discharge optical emission spectroscopy (GDOES) was used to determine the depth profile elemental distribution within the internal oxidation layer (<10 mu m). In addition, scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) studies were carried out on selected sputter eroded surfaces. Oxide type was identified primarily by transmission electron microscopy (TEM). The carburized surface was found to consist of a continuous oxide layer, followed by a complex internal oxidation layer, where Cr and Mn oxides were found to populate grain boundaries in a globular form in the near surface region. At greater depths (5-10 mu m), Si oxides formed as a grain boundary network. The internal oxides (mainly complex oxides) grew quickly during the initial stages of the carburizing process (2 h, 800 deg. C+3 h, 930 deg. C). G...

  5. Formation of carburized layer structure with reverted austenite on low-carbon martensitic steel 12Kh2G2NMFT

    Science.gov (United States)

    Ivanov, A. S.; Bogdanova, M. V.

    2013-03-01

    The structure of surface layer in low-carbon martensitic steel 12Kh2G2NMFT obtained by carburizing followed by high-temperature tempering and quenching from the intercritical temperature range is investigated.

  6. A Comprehensive Numerical Study on Effects of Natural Gas Composition on the Operation of an HCCI Engine Une étude numérique complète sur les effets de la composition du gaz naturel carburant sur le réglage d’un moteur HCCI

    Directory of Open Access Journals (Sweden)

    Jahanian O.

    2011-11-01

    Full Text Available Homogeneous Charge Compression Ignition (HCCI engine is a promising idea to reduce fuel consumption and engine emissions. Natural Gas (NG, usually referred as clean fuel, is an appropriate choice for HCCI engines due to its suitable capability of making homogenous mixture with air. However, varying composition of Natural Gas strongly affects the auto-ignition characteristics of in-cylinder mixture and the performance of the HCCI engine. This paper has focused on the influence of Natural Gas composition on engine operation in HCCI mode. Six different compositions of Natural Gas (including pure methane have been considered to study the engine performance via a thermo-kinetic zero-dimensional model. The simulation code covers the detailed chemical kinetics of Natural Gas combustion, which includes Zeldovich extended mechanism to evaluate NOx emission. Validations have been made using experimental data from other works to ensure the accuracy needed for comparison study. The equivalence ratio and the compression ratio are held constant but the engine speed and mixture initial temperature are changed for comparison study. Results show that the peak value of pressure/temperature of in-cylinder mixture is dependent of fuel Wobbe number. Furthermore, engine gross indicated power is linearly related to fuel Wobbe number. Gross indicated work, gross mean effective pressure, and NOx are the other parameters utilized to compare the performance of engine using different fuel compositions. Le moteur HCCI (Homogeneous Charge Compression Ignition, ou à allumage par compression d’une charge homogène est une idée prometteuse pour réduire la consommation de carburant et les émissions polluantes. Le gaz naturel, considéré généralement comme un carburant propre, est un choix approprié pour les moteurs HCCI en raison de sa capacité à former avec l’air un mélange homogène. Cependant, la composition du gaz naturel influe fortement sur les caract

  7. New Gas Carburizing Method for Minimizing CO2 Emission by Saving Resources and Selective Removal of H2 in Furnace

    Science.gov (United States)

    Mizukoshi, Tomoyuki; Yokoyama, Yujiro; Hoshino, Hideaki; Ishigami, Itsuo; Usui, Tateo

    An attempt has been made to develop a new gas carburizing furnace with the system that discharges H2 gas selectively from the atmosphere in the furnace. Polyimide hollow-fiber membrane filter on the market was selected as a filter that was expected to have good H2 gas permeability and selectivity. The results of the various gas permeability measurements of this filter showed that it had superior H2 gas permeability and selectivity. Using this gas filter module, a new industrial gas carburizing furnace that had ‘H2 gas selective discharging system’ was produced as a trial. Use of this furnace made possible to stabilize the gas carburizing atmosphere in the furnace under the lower carrier gas flow rate condition (below 25% of standard condition). It was confirmed that the carbon concentration profile of the steel carburized with the new carburizing furnace under lower carrier gas flow rate condition was comparable to that of the specimen carburized under standard carrier gas flow rate condition.

  8. Dosage direct des alcools et éthers dans les carburants par chromatographie en phase liquide Direct Measurement of Alcohols and Ethers in Gasohols by Liquid Chromatography

    Directory of Open Access Journals (Sweden)

    Petroff N.

    2006-11-01

    Full Text Available Les différents composés oxygénés potentiels des carburants (alcools jusqu'aux butanols, acétone et éthers en C5 et C6 sont dosés par chromatographie en phase liquide inversée, avec deux qualités d'éluant sur la même colonne (RP 18. L'analyse est faite à 50 °C, avec un détecteur réfractométrique. La limite de sensibilité peut atteindre 100 ppm pour les alcools. The different potential oxygenated compounds in gasolines blended with alcohols up to butanols, acetone and ethers with 5 and 6 carbons are measured by reverse-phase liquid chromatography with two elution systems in the same column (RP 18. Analysis is performed at 50°C with a refractometer as detector. The sensitivity limit can reach 100 ppm for alcohols.

  9. Evaluation of Process Capability in Gas Carburizing Process to Achieve Quality through Limit Design Concept

    Institute of Scientific and Technical Information of China (English)

    K. Palaniradja; N. Alagumurthi; V. Soundararajan

    2004-01-01

    Steel is the most important metallic material used in industry. This is because of the versatility of its engineering properties under different conditions. In one condition it can be very mild, soft and suitable for any forming operation. In another condition the same steel can be very hard and strong. This versatility is made possible by the different heat treatments that the steel can be subject to. One such treatment is Gas carburizing. This is the most widely used process for surface hardening of low carbon steels. In this method the surface composition of the steel changes by diffusion of carbon and or nitrogen and result in hard outer surface with good wear resistance properties. A striking feature of Gas Carburizing process is that in this process the original toughness and ductility remains unaffected even after heat treatment. 3% nickel chromium case hardened low carbon steels are widely used for critical automotive and machine applications such as rack and pinion, gears, camshaft, valve rocker shafts and axles which requires high fatigue resistance. Fatigue behaviour of case carburized parts depends to a great extent on the correct combination of Hardness Penetration Depth (HPD) and the magnitude of hardness at the surface and beneath the surface with low size and shape distortion. In order to reduce the manufacturing costs in terms of material consumption and elimination of the number of processing steps, the effect of Gas carburizing parameters on the fatigue behaviour should already be considered in the parameter design stage. Therefore it is of importance to optimize the gas carburizing process variables to attain quality products with respect to hardness and case depth. In the present paper, the evaluation of process capability was carried out through a Limit Design Concept called orthogonal array design of experiment. To optimize the process variables the influence of several parameters (Holding time,Carbon potential, Furnace temperature and Quench

  10. LOW PRESSURE CARBURIZING IN A LARGE-CHAMBER DEVICE FOR HIGH-PERFORMANCE AND PRECISION THERMAL TREATMENT OF PARTS OF MECHANICAL GEAR

    Directory of Open Access Journals (Sweden)

    Emilia Wołowiec-Korecka

    2017-03-01

    Full Text Available This paper presents the findings of research of a short-pulse low pressure carburizing technology developed for a new large-chamber furnace for high-performance and precision thermal treatment of parts of mechanical gear. Sections of the article discuss the novel constructions of the device in which parts being carburized flow in a stream, as well as the low-pressure carburizing experiment. The method has been found to yield uniform, even and repeatable carburized layers on typical gear used in automotive industry.

  11. The Influence of Method of Carburizing and Nitrocarburizing on the Microstructure and Properties of Tool Steels

    Institute of Scientific and Technical Information of China (English)

    Tomasz Babul; Natalia Kucharieva; Aleksander Nakonieczny; Jan Senatorski

    2004-01-01

    The paper presents the results of wear and metallography tests of tool steel grades: ASTM A681, Chl2M and Ch12FS per GOST, AMS 6437E i BS X46Cr13, all surface hardened by the Carbo process (carburizing) and by the NiCar process (nitrocarburizing). The thermo-chemical treatment was conducted in powder pack for a duration of 6 h (carburizing)and for 4 h in the case of nitrocarburizing. Factors investigated were: morphology, depth and microhardness of the cases obtained, their microstructure, as well as phase composition. Wear tests were conducted by the three cylinder-cone method.Wear velocity was 0.58 m/s, unit load was 50 MPa and 400Mpa, wear path was 3470 m. Oil SAE30 was applied at the rate of 30 drops per minute.

  12. Ablation behavior of monolayer and multilayer Ir coatings under carburizing and oxidizing oxyacetylene flames

    Science.gov (United States)

    Wu, Wangping; Jiang, Jinjin; Chen, Zhaofeng

    2016-06-01

    Iridium is one of the most promising candidates for protective barrier of refractory materials to endure high service temperature. The multilayer iridium coating was produced by a double glow plasma process on the polished tungsten carbide substrates, compared with monolayer. The ablation behaviors of the monolayer on the unpolished and polished substrates were investigated under carburizing and oxidizing oxyacetylene flames, respectively, at the same time the multilayer coating ablated under oxidizing flames. Multilayer coating was a polycrystalline phase with the preferential (220) orientation. Monolayer on the unpolished substrate had fine coarse grains and some small microcracks were present. Multilayer consisted of columnar grains with some voids between the grains boundaries. The formation of a WIr phase in the as-deposited multilayer was attributed to high deposition temperature. The monolayer could endure high temperature up to 1800 °C in carburizing flame. The substrates could be protected more effectively by multilayer than monolayer at 2000- 2200 °C in oxidizing flame.

  13. Development of Nitrogen-Hydrocarbon Atmospheric Carburizing and Process Control Methods

    Science.gov (United States)

    Wang, Xiaolan; Zurecki, Zbigniew; Sisson, Richard D.

    2013-07-01

    Atmospheric pressure carburizing and neutral carbon potential annealing in nitrogen containing small additions of hydrocarbon gases can offer cost and steel surface quality alternatives to the comparable, endothermic atmosphere, or vacuum operations. An experimental program was conducted for refining real-time process control methods in carburizing of AISI 8620 steel under N2-CH4, N2-C3H8 blends containing <5 vol.% of hydrocarbon gas at 900 and 930 °C. Multiple types of gas analyzers were used to monitor residual concentrations of H2, CO, CO2, H2O, O2, CH4, C3H8, and other hydrocarbons inside furnace. A modified shim stock technique was additionally evaluated for correlation with gas analysis and diffusional modeling using measured carbon mass flux values (g/cm2/s). Results of this evaluation work are presented.

  14. Modeling of numerical simulation and experimental verification for carburizing-nitriding quenching process

    Institute of Scientific and Technical Information of China (English)

    R. MUKAI; T. MATSUMOTO; JU Dong-ying; T. SUZUKI; H. SAITO; Y. ITO

    2006-01-01

    A model considering quantitative effects of diffused carbon and nitrogen gradients and kinetics of phase transformation is presented to examine metallo-thermo-mechanical behavior during carburized and nitrided quenching. Coupled simulation of diffusion,phase transformation and stress/strain provides the final distribution of carbon and nitrogen contents as well as residual stress and distortion. Effects of both transformation and lattice expansion induced by carbon and nitrogen absorption were introduced into calculating the evolution of the internal stress and strain. In order to verify the method and the results,the simulated distributions of carbon and nitrogen content and residual stress/strain of a ring model during carburized and nitrided quenching were compared with the measured data.

  15. Surface carburizing of Ti-6Al-4V alloy by laser melting

    Science.gov (United States)

    Saleh, A. F.; Abboud, J. H.; Benyounis, K. Y.

    2010-03-01

    Surface carburizing of a Ti-6Al-4V alloy using laser melting has been investigated experimentally, with the aim of increasing surface hardness and hence improving related properties such as wear and erosion resistance. The surface of the material was coated with graphite prior to laser irradiation. Carburizing was achieved by a laser alloying mechanism, which includes melting the substrate and dissolution of the graphite in the liquid state. Two different types of lasers were used: (i) a continuous wave CO 2 (CW CO 2) laser with a maximum power of 3 kW, and (ii) a pulsating Nd-YAG laser with a maximum power per pulse of 100 W. Optical microscopy, scanning electron microscopy, EDS-analysis, and X-ray diffraction were carried out to analyze the microstructure and identify phases of the carburized layers. The results show that the carburized layers produced by CW CO 2 and Nd-YAG lasers are macroscopically homogeneous and have gradient features. The microstructures consisted of TiC crystals in the matrix of α'-Ti. The TiC crystals are either in the form of particles or dendrites. The depths to which these layers extend ranged from about 0.2-0.5 mm, depending on the treatment parameters. The volume fraction of the dendrites was found to decrease with increasing laser power or increasing traverse speed. Microhardness has been found to be directly related to the volume fraction and the size of the TiC phase. It increased to a value ranging from 500 to 800 Hv as compared to 350 Hv for the as-received substrate.

  16. Characteristic Features of Nanoscale Сarbide Inclusions Nucleation and Growth When Carburizing Steels

    Directory of Open Access Journals (Sweden)

    L.I. Roslyakova

    1990-01-01

    Full Text Available Thermodynamic calculations of the free energy of the formation of cementite type nanoscale carbides in supersaturated austenite alloyed with chromium and manganese are presented. It is shown that when carburizing steel, chromium stabilizing cementite facilitates its separation, in the form of dispersed inclusions. Manganese stabilizes cementite much weaker than chromium, though facilitates the growth of carbide inclusions due to the formation of the intermediate ε-phase at a reduced carbon content.

  17. RJJ-75-9TG井式气体渗碳炉工艺渗碳软件的应用%RJJ-75-9TG pit gas carburizing furnace carburizing process software applications

    Institute of Scientific and Technical Information of China (English)

    王海成

    2014-01-01

    选用北京培特公司技术开发的HT8002AC 井式炉渗碳/碳氮共渗工艺过程计算机控制系统,技术改进2台RJJ-75-9TG 井式气体渗碳炉的渗碳控制系统,实现计算机对整个工艺渗碳全过程的模拟控制,并时刻跟踪和修正现场设备参数的动态变化。提升了渗碳件的产品质量,确保汉德公司两到三年之内的自制件,能够达到国际出口标准。%Selection of Beijing tissue culture technology development company HT8002AC pit furnace carburizing / carbonitriding process computer control systems, technical improvements 2 RJJ-75-9TG pit gas carburizing carburizing furnace control system, the entire computer analog control the whole process of carburizing process and time tracking and dynamic correction field device parameters. Improve product quality carburizing, ensuring homemade pieces Hande within two to three years to reach the international export standards.

  18. The effects of pack carburizing using charcoal of unused mahogany on fatigue characteristic of v-notch shaft steel specimens

    Science.gov (United States)

    Supriyono, Jamasri

    2017-04-01

    The aim of this research is to study the fatigue characteristic of v-notch shaft steel specimens before and after pack carburizing. The carbon source is taken from charcoal of unused mahogany. The fatigue test is conducted on rotary bending machine. The specimens are made of low carbon steel of 0.17% carbon content. Pack carburizing is conducted to the specimens at 930°C. V-notch is made to present the stress concentration factor on the specimens. To see the effects of the carburizing in changing the material properties, micro-structures before and after carburizingare looked and micro hardness measurements along the cross sectional area are carried out. The results show that the carburizing process increases fatigue strength of the material. The micro-structures of the raw material are ferrite and pearlite. The carburized material is divided into two zones i.e. surface zone and core zone. The surface zone consists of hypereutectoid, eutectoid, and hypoeutectoid sub-zone. The core zone is the same as raw material

  19. Effect of carburizing temperature and time on mechanical properties of AISI/SAE 1020 steel using carbonized palm kernel shell

    Directory of Open Access Journals (Sweden)

    Olanike M. OLUWAFEMI

    2015-12-01

    Full Text Available The effects of varied carburizing temperatures and holding time on the mechanical properties of AISI/SAE1020 steel have been investigated. Standard test samples prepared from the steel sample were subjected to pack hardening process using carbonized palm kernel shell as a carburizer at 800°, 850°, 900° and 950°C and held for 60, 90 and 120 minutes, quenched in oil and temper at 500°C for 60 minutes. After pack hardening process, the test samples were subjected to tensile, impact and hardness tests. and from the data obtained Ultimate tensile strength (UTS and impact strength were calculated, the case and the core hardness of the carburized samples were taken and optical microscope was also used to observe the micro structural features of the case hardened, quenched and tempered samples. It was observed that at 800°, 850° and 900°C, the UTS and the micro hardness initially reduces to minimum and then increased as the carburizing temperature increased, but at 950°C, it was observed that the UTS increases with increase in holding time. It was concluded that the optimum combination of mechanical properties is achieved at the carburizing temperature of 950°C soaked for 120 minutes followed by oil quenching and tempered at 500°C for 60 minutes.

  20. Damage prediction of HP40Nb steel with coupled creep and carburization based on the continuum damage mechanics

    Institute of Scientific and Technical Information of China (English)

    Limin SHEN; Jianming GONG; Yong JIANG; Luyang GENG

    2012-01-01

    HP40Nb steel,used as a candidate material for ethylene cracking furnace tube,suffers creep and carburization damage from the complex environment of high temperature,high carbon potential and low oxygen partial pressure,and they lead to failure of the furnace tubes ahead of designed life.In order to investigate damage evolution under the complex condition,coupled creep damage and carburization damage constitutive equations were developed according to continuum damage mechanics theory.Based on the finite element ABAQUS code,user subroutines were developed for analyzing damage evolution of ethylene furnace tube under the action of coupled creepcarburization.The results show that carburization accelerates the damage process dramatically,damage value reaches the critical value along the inner surface after serving for 75,000 h under the action of creep-carburization,meanwhile the damage value is only 0.53 along the outer surface after operating the same time under the action of creep alone,which means that microcracks are generated along the inner surface under the action of coupled creep-carburization,fracture begins along the outer surface of tube under the action of creep alone.

  1. Optimization of Modes of Vacuum Carburizing of Gears from Heat-Resistant Steel VKS-7 on the Basis of Computational Design

    Science.gov (United States)

    Semenov, M. Yu.; Smirnov, A. E.; Fakhurtdinov, R. S.; Ospennikova, O. G.; Gromov, V. I.

    2015-05-01

    Mathematical simulation is used to develop modes of vacuum carburizing providing the specified level of operating properties in high-load gears from steel VKS-7. The computed values of the operating properties are compared to experimental data obtained by testing check pieces subjected to vacuum carburizing by the modes developed.

  2. Influence of Surface Carburization of Machinable Ceramics on Its Pulsed Flashover Characteristics in Vacuum%Influence of Surface Carburization of Machinable Ceramics on Its Pulsed Flashover Characteristics in Vacuum

    Institute of Scientific and Technical Information of China (English)

    郑楠; 黄学增; 穆海宝; 张冠军

    2011-01-01

    For pulsed power devices, surface flashover phenomena across solid insulators greatly restrict their overall performance. In recent decades, much attention has been paid on enhancing the surface electric withstanding strength of insulators, and it is found that surface treatment of material is useful to improve the surface flashover voltage. The carburization treatment is employed to modify the surface components of newly-developed machinable ceramics (MC) materials. A series of MC samples with different glucose solution concentration (0%, 10%, 20%, 30% and 40%) are prepared by chemical reactions for surface carburization modification, and their surface fiashover characteristics are investigated under pulsed voltage in vacuum. It is found that the surface carburization treatment greatly modifies the surface resistivity of MCs and hence the flashover behaviors. Based on the reduction of surface resistivity and the secondary electron emission avalanche (SEEA) theory, the adjustment of flashover withstanding ability can be reasonably explained.

  3. Dvorak. Concerto pour violoncelle / Francis Dresel

    Index Scriptorium Estoniae

    Dresel, Francis

    1992-01-01

    Uuest heliplaadist "Dvorak. Concerto pour violoncelle; Schumann: Concerto pour violoncelle. Orchestre Symphonique d'Estonie, Orchestre Symphonique de la Radio TV d'URSS, Neeme Järvi" Vogue "Archives Sovietiques" 651033 1978

  4. Dvorak. Concerto pour violoncelle / Francis Dresel

    Index Scriptorium Estoniae

    Dresel, Francis

    1992-01-01

    Uuest heliplaadist "Dvorak. Concerto pour violoncelle; Schumann: Concerto pour violoncelle. Orchestre Symphonique d'Estonie, Orchestre Symphonique de la Radio TV d'URSS, Neeme Järvi" Vogue "Archives Sovietiques" 651033 1978

  5. 气体渗碳CAD软件的试验验证%Experimental Verification of CAD Software for Gas Carburizing

    Institute of Scientific and Technical Information of China (English)

    孙炳超; 张戈; 钱初钧; 田禾; 沙云卿

    2001-01-01

    According to technical requirement of 1.2mm and 1.4mm carburizing depth, steel 20CrMnTi and 20CrMo test pieces were carburized in Unicase furnace with a gas carburizing dynamic control CAD system.The results show that this system has a powerful function and control exactly,the deviation of surface carbon concentration is less than 0.05%(weight),carbon concentration gradient curve in carburized layer is smooth and shows “S” shape,the deviation of carburizing depth is less than 0.05mm when the carburizing depth is 1.2mm or 1.4mm.The experimental results are fit well with that designed by software system.%用20CrMnTi和20CrMo钢制的试样,根据渗碳层深度分别为1.2mm和1.4mm的齿轮的技术要求,在装备有气体渗碳动态碳势控制CAD软件的渗碳炉上分别进行了试验,对模拟结果进行了验证,证实了该软件功能强劲、控制准确。其表面碳浓度(质量分数)偏差<0.05%;渗层内的碳浓度梯度曲线平滑,呈“S”型平台分布;渗层深度为1.2mm和1.4mm时,渗层深度的偏差<0.05mm。用该软件设计的渗碳工艺与实际检测结果能很好地吻合。

  6. When It Rains, It Pours

    Science.gov (United States)

    Mills, Linda

    2012-01-01

    "It's raining, it's pouring, the old man is snoring!" "The itsy, bitsy spider crawled up the waterspout, down came the rain and washed the spider out. Out came the sun and dried up all the rain, and the itsy, bitsy spider went up the spout again." What do children's nursery rhymes have to do with the school library? The author begins by telling a…

  7. When It Rains, It Pours

    Science.gov (United States)

    Mills, Linda

    2012-01-01

    "It's raining, it's pouring, the old man is snoring!" "The itsy, bitsy spider crawled up the waterspout, down came the rain and washed the spider out. Out came the sun and dried up all the rain, and the itsy, bitsy spider went up the spout again." What do children's nursery rhymes have to do with the school library? The author begins by telling a…

  8. Élaboration de nanostructures à une dimension à base de carbure de silicium

    OpenAIRE

    Ollivier, Maelig

    2013-01-01

    Le carbure de silicium est pressenti comme un matériau prometteur dans plusieurs domaines de l’électronique tels que la nano-électronique, l’électronique de puissance ou les capteurs travaillant en milieux hostiles (hautes températures, milieux corrosifs, milieux biologiques) du fait de ses propriétés physicochimiques supérieures à celles du silicium, notamment. Cependant, parmi les différentes méthodes d’élaboration par voie descendante ou ascendante permettant de fabriquer des nano-objets à...

  9. Control of heat-resistant steel carburized layer structure. Part I

    Science.gov (United States)

    Semenov, M. Yu.

    2013-09-01

    A physical model of carbide formation with vacuum carburizing is developed with the aim of controlling complexly-alloyed steel diffusion layer structure, taking account of excess phase formation of both the cementite type, and special carbides. A mathematical model is developed on the basis of the physical model adopted, adequate for experimental results. Analysis of calculated results is used as a basis for demonstrating the effect on carbide formation of alloying with chromium and strong carbide-forming elements, and also production factors.

  10. Modelling of the carburizing and quenching process applied to caterpillar track bushings

    Science.gov (United States)

    Ferro, P.; Bonollo, F.

    2014-03-01

    The carburizing-quenching process applied to caterpillar track bushings was studied by means of experimental and numerical analyses. The numerical model was developed on the basis of the real cycle. The purpose of this work is to predict the carbon profiles, microstructural phase changes, hardness and residual stress that occur during quenching using finite element techniques. Good agreement was obtained between the experimental and numerical results in terms of carbon diffusion and hardness profiles. The Sysweld® numerical code was used to perform the simulations.

  11. Evaluation des performances du transistor MOS de puissance sur carbure de silicium. Compromis résistance passante, tenue en tension et vitesse de commutation

    Science.gov (United States)

    Beydoun, B.; Rossel, P.; Tranduc, H.; Charitat, G.

    1994-08-01

    The DC trade-off " ON resistance versus voltage capability " is determined for the SiC multicellular Power MOSFET transistor. First, this limit is analytically calculated for the bulk material. Then, the influence of the size of the MOSFET cell is considered. Under dynamic condition, the switching behaviour is simulated and analysed. We confirm that the DC performances of the SiC device are better than those of Si structures. From a dynamic point of view, a degradation can or not occur depending upon the voltage capability of the considered device. The degradation is due to the drain-gate Miller capacitance increase with the drain doping value. On détermine le compromis statique "résistance passante — tenue en tension" des transistors MOS de puissance multicellulaires sur carbure de silicium. Cette limite est d'abord calculée analytiquement pour le matériau volumique. L'influence de la taille des cellules du transistor MOS est ensuite prise en compte. Au niveau dynamique, la commutation résistive est également simulée. On confirme que les performances statiques de composants SiC sont potentiellement meilleures que celles de leurs homologues Si. D'un point de vue dynamique, on montre que selon la tenue en tension considérée, une dégradation du temps de commutation peut ou non apparaître. Celle-ci est expliquée par l'accroissement de la capacité drain-grille corrélative à l'augmentation de dopage.

  12. Catalytic Effect of Cerium Oxide on Carburization of Steel%氧化铈在钢表面气相渗碳时的催化作用

    Institute of Scientific and Technical Information of China (English)

    袁泽喜; 谭平; 余宗森; 徐庭栋

    2001-01-01

    Comparing the kinetics of gas carburization of steel 20 with the carburization agent containing cerium oxide or without it,it is found that cerium oxide in carburant can accelerate carburizing process greatly,which almost has the same effect at 850℃ and 910℃.This effect is accomplished by catalyzing mechanism of cerium oxide.RE in steel can also accelerate carburizing process,but its effect is less than RE in carburant. RE in steel can improve the catalysis of RE in carburant.%在20钢气相渗碳时对比了渗剂中加入CeO2或不加CeO2时的渗碳动力学,发现在渗剂中加入CeO2可以显著加快渗碳速率。稀土催渗剂的效果在850℃和910℃基本相同。认为CeO2加速渗碳的机制是催化。冶炼时在钢中加入的稀土对渗碳也起加速作用,但作用小于渗剂中的稀土。它还可以增强渗剂中稀土的催渗作用。

  13. 20CrMnMo钢稀土渗碳研究%Study on RE Carburizing of 20CrMnMo Steel

    Institute of Scientific and Technical Information of China (English)

    徐建军; 杜晓东

    2012-01-01

    RE carburization was carried out on 20CrMnMo steel. The carburizing kinetics of carburizing depth was dealed with, the microstructure of the carburized layer was observed, the hardness and abrasion resistance of the carburized layer were examined. The results show that a large amount of dispersed granular carbides precipitated in the carburized layer of 20CrMnMo steel RE carburized. The microstructure of surface layer after directly quenching consists of acicular martensite, fine granular carbides and a little residual austenite. The test results showed 10 persent improvement in hardness, 32 persent improvement in abrasion resistance,The touching fatigue life is sharply improved too.%采用稀土渗碳工艺对20CrMnMo钢进行渗碳处理,研究了渗层增厚的动力学、渗碳层组织和性能.结果表明:稀土渗碳层中沉淀析出了大量弥散分布的粒状碳化物,淬火后表层组织为针状马氏体、大量细小颗粒碳化物、少量残余奥氏体.渗碳层的硬度与传统工艺相比提高了10%,耐磨性提高了32%,接触疲劳寿命也有大幅提高.

  14. Analysis on microstructure of carburized layer in cast-iron molten bath carburized 20 steel%20钢铸铁浴渗碳渗层组织的分析

    Institute of Scientific and Technical Information of China (English)

    刘建华; 湛岩; 张瑞军; 于升学; 杨雪梅

    2001-01-01

    The microstructure of carburized layer in 20 steel cast-iron molten bath carburized at different temperature and time was studied in the paper.The research results show that the microstructure of carburized layer which is at 130~150μm from the surface is cementite+pearlite+ferrite,when specimen immevsed for 30s in 1270℃;the micvostruchre of carburized layer which is at 0~120μm from the surface is cementite+pearlite,and bar carbides is obtained in the base.%本文探讨了20钢在铸铁浴中经不同温度及时间渗碳的渗层组织。结果表明,试样在1270℃的铸铁浴中保留30秒,距表面130~150μm处,其渗层组织为渗碳体+珠光体+铁素体;试样在1300℃的铸铁浴中保留30秒,距表面0~120μm处,其渗层组织为渗碳体+珠光体,且在基体上形成棒条状的碳化物。

  15. 低碳钢固体渗碳的实验与研究%Experiment and Research on Solid-carburizing for Low Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    廖西平

    2012-01-01

    The experiment of solid-carburizing process on 20 steel and 20CrMoV steel has been fully developed, which includes preparatory heat-treatment, carburizing craft, metallographic structure, the final heat- treatment, etc. This experiment analyzed the factors of carburizing coating and hardness, and the basic law and technology of solid- carburizing process have been worked out. The experiment has proved that solid- carburizing craft has several advantages such as simple process, easily to operate and control, low cost, and without special devices. The solid- carburizing product completely meets conventional requirement. However, solid-carburizing process has its disadvantages such as thin carburizing coating and too long total operating time, thus solid- carburizing only fits for the production of single-piece on small scale.%对20、20CrMoV钢的固体渗碳进行了较全面的实验及研究,包括钢的预备热处理、渗碳工艺、金相组织、最终热处理等;分析了渗碳层、硬度的影响因素,并总结摸索出固体渗碳的基本规律和工艺技术;实验证明:固体渗碳工艺简单、操作简单、成本低廉,不需要专门设备;渗碳件在性能上完全能够达到常规渗碳的要求,但固体渗碳的渗碳层偏薄,时间较长,只能适应单件、小批量的生产。

  16. Visualisation of Gasoline and Exhaust Gases Distribution in a 4-Valve Si Engine; Effects of Stratification on Combustion and Pollutants Visualisation de la répartition du carburant et des gaz brûlés dans un moteur à 4 soupapes à allumage commandé ; effet de la stratification sur la combustion et les polluants

    Directory of Open Access Journals (Sweden)

    Deschamps B.

    2006-12-01

    Full Text Available sAn indirect method to map the burned gases in SI engine has been developed. It is based on visualisation by Laser Induced Fluorescence of the unburned mixture seeded with biacetyl. Both internally and externally recirculated burned gases are monitored. This diagnostic is complementary to the LIF technique applied to measure the gasoline distribution. These LIF gasoline and burned gases measurements are applied in a 4-valve optical access SI engine for a large range of operating conditions. These include variations of both fuel injection and burned gas recirculation modes causing different types of stratification leading to very distinct heat release and exhaust emissions characteristics. Tumble level and spark location are also modified. The observation of the actual stratification in the engine forms a sound basis explanation of the engine performance. Parameters allowing an optimisation of NOx and HC levels can be inferred, and in particular the effectiveness of recirculation and fuel injection strategies. The conclusions are confirmed by measurements in a single engine cylinder conventional head with the same geometry. Une méthode indirecte pour cartographier les gaz brûlés dans un moteur à allumage commandé a été développée. Elle est fondée sur une visualisation à partir de la fluorescence induite par laser (LIF du mélange air-carburant non brûlé et ensemencé avec du biacétyl. Les gaz brûlés provenant à la fois des recirculations internes et externes sont observés. Ce type de diagnostic est complémentaire des techniques de LIF utilisées pour observer la distribution du carburant. Ces mesures de concentration sont réalisées dans un moteur à 4 soupapes avec accès optiques, pour une gamme étendue de conditions opératoires. Celles-ci comprennent des variations des modes d'injection du carburant et des modes de recirculation des gaz brûlés, provoquant ainsi différents types de stratifications qui correspondent

  17. Development of a carburizing and quenching simulation tool: numerical simulations of rings and gears

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, C.; Godlman, P.; Rangaswamy, P. [and others

    1996-10-01

    The ability to accurately calculate temperatures, stresses and metallurgical transformations in a single calculation or in a sequence of calculations is the key to prediction of distortion, residual stress and phase distribution in quench hardened automotive parts. Successful predictions in turn rely on the adequacy of the input data to the calculational procedure. These data include mechanical and thermal properties of the alloy phases over the range of temperature and strain rates experienced during the heat treat process, the mathematical description of the transformation kinetics, and the accuracy of the heat transfer boundary conditions. In this presentation we describe a calculational procedure using the ABAQUS{sup (1)} finite element code that simulates a carburizing and quench heat treat cycle for automotive gears. The calculational procedure features a numerically efficient 2-phase constitutive model, developed as part of the NCMS-Heat Treatment Distortion Prediction program, to represent transformational plasticity effects for the austenite/martensite Deformation together with refined finite element meshes to capture the steep gradients in stress and composition near the gear surfaces. The calculational procedure is illustrated on carburizing and quenching of a thick ring and comparison of model predictions for distortion, phase distribution, and residual stress with experimental measurements are discussed. Included in this model study is an investigation of the sensitivity of the predictions to mesh refinement.

  18. Formation of nanocrystalline layers by surface severe plastic deformation and pulsed plasma electrolytic carburizing.

    Science.gov (United States)

    Aliofkhazraei, M; Rouhaghdam, A Sabour

    2010-07-01

    Surfaces of various kinds of metallic materials spheres were treated by nanocrystalline surface severe plastic deformation and then pulsed nanocrystalline plasma electrolytic carburizing to study nanocrystalline substrate effect on formation and nano-hardness of hard nanocrystalline layer. The surface layers of the metallic materials developed by the nanocrystalline surface severe plastic deformation were characterized by means of high resolution scanning electron microscope. Nearly equiaxed nanocrystals with grain sizes ranging from 15 to 90 nm were observed in the near surface regions of all metallic materials, which are low carbon steel and commercially pure titanium. The effect of substrate nanocrystallization on growth kinetics and hardness of formed nanocrystalline carbide layer was studied with the means of figure analysis and nanohardness tests. Figure analysis show the length to diameter ratio and distribution curve of nanocrystals and it has been found that the achieved properties of hard layer (growth rate, nano-hardness, nanostructure...) are related to these factors. It was also clarified that these techniques and surface nanocrystallization can be easily achieved in most of metallic materials. Results indicate that the resultant hardened carburized layers exhibited excellent hardness profile. Investigation of the layer characteristics showed strong dependence followed from the treatment experimental parameters as well as the shape of nanocrystals.

  19. Boronization and Carburization of Superplastic Stainless Steel and Titanium-Based Alloys

    Directory of Open Access Journals (Sweden)

    Masafumi Matsushita

    2011-07-01

    Full Text Available Bronization and carburization of fine-grain superplastic stainless steel is reviewed, and new experimental results for fine grain Ti88.5Al4.5V3Fe2Mo2 are reported. In superplastic duplex stainless steel, the diffusion of carbon and boron is faster than in non-superplastic duplex stainless steel. Further, diffusion is activated by uniaxial compressive stress. Moreover, non-superplastic duplex stainless steel shows typical grain boundary diffusion; however, inner grain diffusion is confirmed in superplastic stainless steel. The presence of Fe and Cr carbides or borides is confirmed by X-ray diffraction, which indicates that the diffused carbon and boron react with the Fe and Cr in superplastic stainless steel. The Vickers hardness of the carburized and boronized layers is similar to that achieved with other surface treatments such as electro-deposition. Diffusion of boron into the superplastic Ti88.5Al4.5V3Fe2Mo2 alloy was investigated. The hardness of the surface exposed to boron powder can be increased by annealing above the superplastic temperature. However, the Vickers hardness is lower than that of Ti boride.

  20. Analyses of quenching process during turn-off of plasma electrolytic carburizing on carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jie; Liu, Run [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Xue, Wenbin, E-mail: xuewb@bnu.edu.cn [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Wang, Bin; Jin, Xiaoyue; Du, Jiancheng [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2014-10-15

    Highlights: • Cooling rate of carburized steel at the end of PEC treatment is measured. • The quench hardening in the fast or slow turn-off mode hardly takes place. • Decrease of the surface roughness during slow turn-off process is found. • A slow turn-off mode is recommended to replace the conventional turn-off mode. - Abstract: Plasma electrolytic carburizing (PEC) under different turn-off modes was employed to fabricate a hardening layer on carbon steel in glycerol solution without stirring at 380 V for 3 min. The quenching process in fast turn-off mode or slow turn-off mode of power supply was discussed. The temperature in the interior of steel and electron temperature in plasma discharge envelope during the quenching process were evaluated. It was found that the cooling rates of PEC samples in both turn-off modes were below 20 °C/s, because the vapor film boiling around the steel sample reduced the cooling rate greatly in terms of Leidenfrost effect. Thus the quench hardening hardly took place, though the slow turn-off mode slightly decreased the surface roughness of PEC steel. At the end of PEC treatment, the fast turn-off mode used widely at present cannot enhance the surface hardness by quench hardening, and the slow turn-off mode was recommended in order to protect the electronic devices against a large current surge.

  1. Analysis of Hardened Depth Variability, Process Potential, and Measurement Error in Case Carburized Components

    Science.gov (United States)

    Rowan, Olga K.; Keil, Gary D.; Clements, Tom E.

    2014-12-01

    Hardened depth (effective case depth) measurement is one of the most commonly used methods for carburizing performance evaluation. Variation in direct hardened depth measurements is routinely assumed to represent the heat treat process variation without properly correcting for the large uncertainty frequently observed in industrial laboratory measurements. These measurement uncertainties may also invalidate application of statistical control requirements on hardened depth. Gage R&R studies were conducted at three different laboratories on shallow and deep case carburized components. The primary objectives were to understand the magnitude of the measurement uncertainty and heat treat process variability, and to evaluate practical applicability of statistical control methods to metallurgical quality assessment. It was found that ~75% of the overall hardened depth variation is attributed to the measurement error resulting from the accuracy limitation of microhardness equipment and the linear interpolation technique. The measurement error was found to be proportional to the hardened depth magnitude and may reach ~0.2 mm uncertainty at 1.3 mm nominal depth and ~0.8 mm uncertainty at 3.2mm depth. A case study was discussed to explain a methodology for analyzing a large body of hardened depth information, determination of the measurement error, and calculation of the true heat treat process variation.

  2. Contribution to the study of gaseous Carburization of Uranium; Contribucion al estudio de la Carburacion gaesosa del uranio

    Energy Technology Data Exchange (ETDEWEB)

    Esteban Hernandez, J. A.; Jimenez Moreno, J. M.; Villota Ruiz, P. de

    1966-07-01

    Thermal decomposition of uranium hydride powder obtained by hydrogenation of uranium turnings is studied on the first part of this paper. Carburization of the uranium hydride or metallic uranium powder with methane is studied in the second part. A method of uranium monocarbide fabrication under static atmosphere is described. On this method hydrogen is removed by means of an uranium getter. (Author) 6 refs.

  3. Comparison of CaCO3 from Natural Sources and Artificial Carbonates as Activators of Solid-Phase Carburizing of Low-Carbon Steel

    Science.gov (United States)

    González-Angeles, A.; López-Cuevas, J.; Pitalúa-Díaz, N.

    2013-11-01

    The process of solid-phase carburizing of steel with the use of carbonates of different origin including chemical reagents, limestone and oyster shells is studied. The highest microhardness is obtained in the case of SrCO3, wheres Na2CO3 is shown to be the cheapest and most economically expedient carbonate. A good carburized layer can be obtained using a mixture of limestone and oyster shells.

  4. The efficiency of different types of wood charcoal on increasing carbon content on surfaces of low carbon steel in the pack carburizing process

    Directory of Open Access Journals (Sweden)

    Narongsak Thammachot

    2014-09-01

    Full Text Available The purpose of this research is to compare the efficiency of five types of wood charcoal, eucalyptus, coconut shell, tamarind, bamboo and cassava root in increasing carbon content on surfaces of low carbon steel by the pack carburizing process. The experiment for pack carburized low carbon steel (grade AISI 1020 was conducted by using the different wood charcoals as carburizers, mixed with 10% limestone (by weight as the energizer. The carburizing temperature of 950°C, and carburizing times of 2, 4 and 6 hours were used in the experiment. After grinding, the specimens in each case were checked for carbon content by optical emission spectroscopy. Micro-Vickers hardness testing and microstructure inspections were carried out. The results of the experiment showed that the efficiency of eucalyptus charcoal as the carburizer (for increasing carbon content on surfaces of low carbon steel was higher than that of tamarind, cassava root, coconut shell and bamboo charcoals. The averages for carbon content were: 1.16, 1.06, 0.97, 0.83 and 0.77% respectively.

  5. Development and application of intelligent vacuum carburizing and quenching furnace%智能型真空渗碳淬火炉研制及应用

    Institute of Scientific and Technical Information of China (English)

    孙强; 胡东彪; 杨建军; 李宝军; 封亮

    2012-01-01

    Intelligent vacuum carburizing and quenching furnace with a powerful computer control system and expert system,according to workpiece material properties and the diffusion layer requirements automatically generated the initial parameters of vacuum carburizing process,solves the problems of vacuum carburizing carbon black,tar pollution and carburized layer uniformity and improves production stability and quality consistency,vacuum carburized to achieve intelligent automated production,improves quality of cementation,has been used successfully in the aviation industry carburizing high alloy steel and stainless steel.%智能型真空渗碳淬火炉具有功能强大的计算机控制系统和专家系统,可以根据工件材料特性和渗层要求等初始参数自动生成真空渗碳工艺,解决了困扰真空渗碳碳黑、焦油污染和渗层均匀性问题,提高了生产稳定性和质量一致性,实现真空渗碳淬火的智能化自动生产,提高了渗碳质量,已成功用于航空工业中高合金钢和不锈钢的渗碳。

  6. Influence of the Inclusion Shape on the Rolling Contact Fatigue Life of Carburized Steels

    Science.gov (United States)

    Neishi, Yutaka; Makino, Taizo; Matsui, Naoki; Matsumoto, Hitoshi; Higashida, Masashi; Ambai, Hidetaka

    2013-05-01

    It has been well known that the flaking failure in rolling contact fatigue (RCF) originates from nonmetallic inclusions in steels, and their apparent size is one of the important factors affecting RCF life. However, the influence of inclusion shape on the RCF life has not been fully clarified. In this study, attention was paid to the influence of the inclusion shape on the RCF life. This was evaluated by using carburized JIS-SCM420 (SAE4320) steels that contained two different shapes of MnS—stringer type and spheroidized type—as inclusions. Sectional observations were made to investigate the relation between the occurrence of shear crack in the subsurface and the shape of MnS. It was found that the RCF life was well correlated with the length of MnS projected to the load axis, and the initiation of shear crack in subsurface was accelerated as the length of MnS increased.

  7. Carburization of austenitic and ferritic alloys in hydrocarbon environments at high temperature

    Directory of Open Access Journals (Sweden)

    Serna, A.

    2003-12-01

    Full Text Available The technical and industrial aspects of high temperature corrosion of materials exposed to a variety of aggressive environments have significant importance. These environments include combustion product gases and hydrocarbon gases with low oxygen potentials and high carbon potentials. In the refinery and petrochemical industries, austenitic and ferritic alloys are usually used for tubes in fired furnaces. The temperature range for exposure of austenitic alloys is 800-1100 °C, and for ferritic alloys 500-700 °C, with carbon activities ac > 1 in many cases. In both applications, the carburization process involves carbon (coke deposition on the inner diameter, carbon absorption at the metal surface, diffusion of carbon inside the alloy, and precipitation and transformation of carbides to a depth increasing with service. The overall kinetics of the internal carburization are approximately parabolic, controlled by carbon diffusion and carbide precipitation. Ferritic alloys exhibit gross but uniform carburization while non-uniform intragranular and grain-boundary carburization is observed in austenitic alloys.

    La corrosión a alta temperatura, tal como la carburación de materiales expuestos a una amplia variedad de ambientes agresivos, tiene especial importancia desde el punto de vista técnico e industrial. Estos ambientes incluyen productos de combustión, gases e hidrocarburos con bajo potencial de oxígeno y alto potencial de carbono. En las industrias de refinación y petroquímica, las aleaciones austeníticas y ferríticas se utilizan en tuberías de hornos. El rango de temperatura de exposición para aleaciones austeníticas está entre 800-1.100°C y para aleaciones ferríticas está entre 500-700°C, con actividades de carbono ac>1 en algunos casos. En tuberías con ambas aleaciones, el proceso de carburación incluye deposición de carbón (coque en el diámetro interno, absorción de carbono en la superficie

  8. Nitrocarburizing with independently-controlled nitriding and carburizing potentials; Nitrocarburieren mit unabhaengig geregeltem Nitrier- und Carburierpotenzial

    Energy Technology Data Exchange (ETDEWEB)

    Winter, K.M. [PROCESS-ELECTRONIC GmbH, Heiningen (Germany)

    2006-05-15

    Nitrocarburizing, a short-cycle nitriding, is a well-known heat treatment for improving corrosion and wear resistance of work pieces. In contrast to long-cycle nitriding, where nitrogen diffuses into the steel surface to achieve a case depth similar to carburizing, nitrocarburizing over saturates the surface with nitrogen and carbon in order to change the iron alpha structure into gamma prime (Fe{sub 4}N) and later into epsilon (Fe{sub 2-3}[NC]). The hexagonal closed-packed epsilon has a very low friction and a high chemical resistance. This article will show the influence of different compositions in N and C created using a standard industrial pit-type furnace equipped with a control system capable of measuring and controlling K{sub N} and K{sub C} independently and at the same time. (orig.)

  9. Reference measurements in a carburizing atmosphere. Pt. 1; Referenzmessungen in der Aufkohlungsatmosphaere. T. 1

    Energy Technology Data Exchange (ETDEWEB)

    Mikulovic, Dzo; Ehmeier, Florian [MESA Electronic GmbH, Geretsried (Germany); Zivanovic, Dragan [Nis Univ. (RS). Fakultaet fuer Elektrotechnik; MESA Electronic GmbH, Nis (RS)

    2010-06-15

    The most important parameters for control of carburizing process are the temperature and the C-potential of atmosphere. Temperature normally is measured by means of thermocouples. For control of C-potential measurement of oxygen partial pressure of furnace atmosphere by in-situ O{sub 2}-probes and Lambda probes became accepted. The thermocouples as well as the probes for measurement of residual oxygen gradually lose in accuracy. Therefore reference measurements for adjustment of temperature and C-potential are essential for an exact control. Within this article the reasons for incorrect measurements with thermocouples and O{sub 2}-probes, respectively L-probes will be explained. The appropriate reference measurements for correction of these faults are also described. Furthermore it is explained what has to be observed with these reference measurements and which information is given thereby about furnace atmosphere, especially with the gas analysis by means of a gas analyzer. (orig.)

  10. Control of Heat-Resistant Steel Carburized Layer Structure. Part II

    Science.gov (United States)

    Semenov, M. Yu.

    2013-09-01

    In the first part of the article, published in the previous issue of this journal, on the basis of studying features of the process a physical and mathematical model is presented of carbide formation during heat-resistant steel vacuum carburizing based on the example of VKS-5. In the second part of this article on the basis of analyzing the calculation model physical features are presented for formation of cementite type carbide phase taking account of steel VKS-5 alloying with chromium and nickel, and also temperature. Simultaneously, features of special molybdenum, tungsten, vanadium and niobium carbide formation are considered. The expediency of increasing chromium content in a new generation of heat-resistant steels alloyed with nickel is substantiated.

  11. Surface fatigue life of CBN and vitreous ground carburized and hardened AISI 9310 spur gears

    Science.gov (United States)

    Townsend, Dennis P.; Patel, P. R.

    1988-01-01

    Spur gear surface endurance tests were conducted to investigate CBN ground AISI 9310 spur gears for use in aircraft applications, to determine their endurance characteristics and to compare the results with the endurance of standard vitreous ground AISI 9310 spur gears. Tests were conducted with VIM-VAR AISI 9310 carburized and hardened gears that were finish ground with either CBN or vitreous grinding methods. Test conditions were an inlet oil temeprature of 320 K (116 F), an outlet oil temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. The CBN ground gears exhibited a surface fatigue life that was slightly better than the vitreous ground gears. The subsurface residual stress of the CBN ground gears was approximately the same as that for the standard vitreous ground gears for the CBN grinding method used.

  12. Modeling of acetylene pyrolysis under steel vacuum carburizing conditions in a tubular flow reactor.

    Science.gov (United States)

    Khan, Rafi Ullah; Bajohr, Siegfried; Graf, Frank; Reimert, Rainer

    2007-03-02

    In the present work, the pyrolysis of acetylene was studied under steel vacuum carburizing conditions in a tubular flow reactor. The pyrolysis temperature ranged from 650 degrees C to 1050 degrees C. The partial pressure of acetylene in the feed mixture was 10 and 20 mbar, respectively, while the rest of the mixture consisted of nitrogen. The total pressure of the mixture was 1.6 bar. A kinetic mechanism which consists of seven species and nine reactions has been used in the commercial computational fluid dynamics (CFD) software Fluent. The species transport and reaction model of Fluent was used in the simulations. A comparison of simulated and experimental results is presented in this paper.

  13. Rolling Contact Fatigue Properties of SAE 8620 Steel after Case Carburizing

    Institute of Scientific and Technical Information of China (English)

    Yan-guang CAO; Le XU; Gou-qiang ZHANG; Jie SHI; Mao-qiu WANG

    2016-01-01

    Rolling contact fatigue (RCF)properties of SAE 8620 steel after case carburizing have been investigated under two contact stresses of 4·0 and 5·5 GPa.Results show that the RCF life ranges from 2·5×106 to 3×107 cycles un-der the contact stress of 5·5 GPa,while it can be more than 1×108 cycles under the contact stress of 4·0 GPa.The rated fatigue life L10 (lives with the 10% failure)is also drastically shortened from 9·8×106 to 5·4×105 cycles when the contact stress is increased from 4·0 to 5·5 GPa.Theoretical calculations and fractographs show that the maximum shear stress and the contact area increase with increasing the contact stress,making RCF tend to occur earlier.

  14. Thermoelectric generating system attached to a carburizing furnace at Komatsu Ltd., Awazu Plant

    Science.gov (United States)

    Kaibe, H.; Makino, K.; Kajihara, T.; Fujimoto, S.; Hachiuma, H.

    2012-06-01

    At the end of October 2009, KELK Ltd. started a field test of the thermoelectric generation system at a carburizing furnace of Komatsu Ltd., Awazu Plant. Residual carburizing gas based on CO, H2 and N2 is burned resulting that 20-30 kW range of flame constantly heats up the hot side of TEG. A single unit of TEG consists of 16 of the Bi-Te thermo-modules, each of which has a size of 50 × 50 × 4.2 mm3 and can generate 24W under the circumstance of 280 °C and 30 °C of hot side and cold side temperature, respectively [1]. 16 modules are separated into 4 groups and they are connected electrically depending on design concept, namely in case of focusing on reliability, parallel connection are used and in case of on simplicity and high-voltage transmission, series connection is preferably employed. The module is being life-time tested at various conditions. For instance, 10,000 of heat cycling under the hot side temperature between 250 and 50 °C with a constant cold side temperature at 30 °C gives within a few percent degrade. Both buck-and booster-type DC/DC converters controlled by one chip computer were set up and Maximum Power Point Tracking (MPPT) was well facilitated to search for the maximum output power depending on the hot and cold temperature. The electric output power from the 16 modules is summed up to charge 4 lead storage batteries (12V-65Ah) and then through DC/AC inverters electricity goes to LED light tubes inside the factory. 214 W can be generated and 180 W is delivered to the batteries.

  15. 渗碳气体对201奥氏体不锈钢低温离子渗碳效果的影响%Effect of Carburizing Gases on Low Temperature Plasma Carburization of 201 Austenitic Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    王宇; 赵程

    2012-01-01

    用不同的渗碳气体对201奥氏体不锈钢进行了低温离子渗碳(DCPC)处理.实验证明,甲烷和乙炔均可在不锈钢表面形成一层无碳化铬析出的碳的过饱和固溶体(Sc相),使其表面的硬度和耐蚀性均有较大幅度的提高.但用甲烷作为渗碳气体处理的不锈钢表面有一层黑膜,破坏了不锈钢原有的光泽;而用乙炔作为渗碳气体不仅可以获得较为光亮的表面色泽,同时其硬度和耐蚀性也有进一步的提高.%The low temperature plasma carburization (DCPC) of 201 austenitic stainless steel has been done by using different carburizing gases. The results show that CH4 and C2 H2 can form a layer of carbon supersaturated solid solution (i. e. the Sc phase) on the steel surface without chromium carbide precipitation, so the surface hardness and corrosion resistance are greatly improved. But a layer of black film will form on the metal surface when CH4 is used as carburizing gases, which will destroy the original luster of stainless steel, when C2 H2 is used as carburizing gases, not only bright surface luster can be obtained, but also the hardness and corrosion resistance can be greatly improved.

  16. The carbide M{sub 7}C{sub 3} in low-temperature-carburized austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, Frank, E-mail: frank.ernst@cwru.edu [Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106-7204 (United States); Li, Dingqiang; Kahn, Harold; Michal, Gary M.; Heuer, Arthur H. [Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106-7204 (United States)

    2011-04-15

    Prolonged low-temperature gas-phase carburization of AISI 316L-type austenitic stainless steel can cause intragranular precipitation of the carbide M{sub 7}C{sub 3} (M: randomly dispersed Fe, Cr, Ni). Transmission electron microscopy revealed that the carbide particles have the shape of needles. They grow by a ledge-migration mechanism and in a crystallographic orientation relationship to the austenite matrix that enables highly coherent interphase interfaces. A small solubility limit of Ni in the carbide and restricted Ni diffusivity at the processing temperature leads to Ni pileup around the particles and may explain the extreme aspect ratio of the particle shape. These characteristics closely resemble what has been observed earlier for precipitates of M{sub 5}C{sub 2} under slightly different processing conditions and can be rationalized by considering the particular constraints imposed by carburization at low temperature.

  17. Carbon diffusion and phase transformations during gas carburizing of high-alloyed stainless steels: Experimental study and theoretical modeling

    Science.gov (United States)

    Turpin, T.; Dulcy, J.; Gantois, M.

    2005-10-01

    Gas carburizing of high-alloyed stainless steels increases surface hardness, as well as the overall mechanical characteristics of the surface. The growth of chromium-rich carbides during carbon transfer into the steel causes precipitation hardening in the surface, but decreases the chromium content in solid solution. In order to maintain a good corrosion resistance in the carburized layer, the stainless steel composition and the carburizing process need to be optimized. To limit the experimental work, a methodology using software for modeling the thermodynamic and kinetic properties in order to simulate carbon diffusion and phase transformations during gas carburizing is presented. Thermodynamic calculations are initially used to find the optimum parameters ( T, carbon wt pct, etc.) in order to maintain the highest Cr and Mo contents in the austenitic solid solution. In a second step, kinetic calculations using the diffusion-controlled transformations (DICTRA) software are used to predict how the amount of the different phases varies and how the carbon profile in the steel changes as a function of time during the process. Experimental carbon profiles were determined using a wavelength-dispersive spectrometer for electron-probe microanalysis (WDS-EPMA), while carbide compositions were measured by energy-dispersive spectroscopy_X (EDS_X) analyses. A good agreement between calculated and experimental values was observed for the Fe-13Cr-5Co-3Ni-2Mo-0.07C and the Fe-12Cr-2Ni-2Mo-0.12C (wt pct) martensitic stainless steels at 955 °C and 980 °C.

  18. Tribotechnical and Energy Assessment of Parts of Working Members of Cultivating Machines After Carburizing and Laser Hardening

    Science.gov (United States)

    Pyndak, V. I.; Novikov, A. E.

    2016-07-01

    Results of experimental studies of low-carbon steel 20 and high-carbon steels of types 70 and 65G after carburizing, heat treatment and laser hardening are presented. The variation of the microhardness of the surface layers of the steels and of their wear resistance due to different variants of hardening is determined. Optimum modes of treatment aimed at raising the strength and wear resistance are suggested for the steels used for working members of cultivating machines.

  19. The Synergy of the Surface Layer after Carburizing of Tool Steel as a Measure of Operational Quality

    Directory of Open Access Journals (Sweden)

    Wencel, Z.

    2007-01-01

    Full Text Available In the paper the results of the investigation on surface layer of carburized X150CrMoV12-1 tool steel are presented. Abrasive wearing of the surface was determined according the ASTM G77-98 method. The microstructure of the matrix and distribution of carbides were observed in a Scanning Electron Microscope (SEM. A correlation between the investigated parameters (microstructure/carbides distribution was found.

  20. Hard Chromium Electroplating and Improvement the Properties by the Thermo Chemical Treatments (Solid Carburizing of Low Carbon Steel

    Directory of Open Access Journals (Sweden)

    Ahmed Salloum Abbas

    2009-01-01

    Full Text Available In this research the hard chromium electroplating process, which is one of the common methods of overlay coating was used, by using chromium acid as source of chromium and sulphuric acid as catalyst since the ratio between chromic acid and sulphuric acid is (100 : 1 consequently. Plating process was made by applying current of density (40 Amp / dm2 and the range of solution temperature was (50 – 55oC with different time periods (1-5 hr. A low carbon steel type (Ck15 was used as substrate for hard chromium electroplating. Solid carburization was carried out for hard chromium plating specimen at temperature (925oC with time duration (2 hr to be followed with quenching and tempering. The phase analysis was conducted by using X– ray diffraction. The examination results show that the chromium carbides in plating layer were (Cr23C6, Cr7C3. The microhardness of hard chromium plating specimen was measured, and the results show that the high hardness was about (907HV. After solid carburization the hardness values increase and the results show that the higher hardness for chromium plating layer on low carbon steel surface was (1276 HV. Wear apparatus type (Pin on Disc was used to study dry sliding wear properties of low carbon steel (As received and hard chromium plating specimens and solid carburized. The effect of applied normal load on wear rate was studied with weighting method using five normal loads (5, 10, 15, 20, 25 N at constant sliding speed (2.198 m / sec. The results reveal that the wear rate increases with the increasing of applied normal load. A good improvement in wear resistance was noticed for hard chromium plating specimens as compared with substrate specimen. It was also seen that, the improvement in wear resistance was (94% as compared with substrate metal when carburizing treatment is carried out on hard chromium plating specimens.

  1. Study of the 1.25Cr-1Mo-0.25V steel microstructure after a carburization phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Simonetti, S., E-mail: ssimonet@uns.edu.ar [Departamento de Fisica, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Departamentos de Ciencias Basicas e Ingenieria Mecanica, Universidad Tecnologica Nacional, 11 de Abril 461, 8000 Bahia Blanca (Argentina); Lanz, C. [Departamento de Ingenieria, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Brizuela, G.; Juan, A. [Departamento de Fisica, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina)

    2010-08-20

    We studied the changes in the structure and carbide particle size in 1.25Cr-1Mo-0.25V steel under 600 deg. C and 168 MPa, after 4000 h service. We used microscopy and microanalysis techniques to analyze the carbide particles. We performed a complementary theoretical study on the chemical bonding and electronic structure of the carbide-Fe matrix interaction. The results contribute to the understanding of the changes in the alloy microstructure caused by the carburization phenomenon.

  2. Use of Ethanol/Diesel Blend and Advanced Calibration Methods to Satisfy Euro 5 Emission Standards without DPF Utilisation d’un carburant Diesel éthanolé à l’aide de méthodes de calibration avancées afin de satisfaire les normes Euro 5 sans filtre à particules

    Directory of Open Access Journals (Sweden)

    Magand S.

    2011-11-01

    innovative calibration methods, based on the simultaneous optimisation of engine basic settings and cold correction maps, are introduced in order to better suit to the new formulation impact on combustion and catalyst light-off and to drop off engine-out unburned hydrocarbons and carbon monoxide emissions. This stage allows pushing forward the work on test bed facilities in order to reduce the amount of vehicle tests. Tests on a chassis dynamometer are only used to validate the engine test bed results and to perform final tuning of cold correction maps. This alternative blend shows potential to achieve Euro 5 standard with Euro 4 Diesel vehicle configuration, without any hardware modification and without a Diesel particulate filter in the exhaust line. Such an innovative fuel formulation seems to be an interesting answer to the trade-off in the forthcoming years between cost and emissions reduction to achieve sustainable mobility. The presented calibration methods and tools allow to fully take advantage of this alternative fuel in a reduced time scale. L’utilisation des biocarburants s’est développée durant ces dernières années de façon importante afin de diversifier les sources d’énergies et de limiter la hausse des émissions de gaz à effet de serre du secteur des transports. L’un des carburants renouvelables les plus adaptés à une production de masse est l’éthanol. Celui-ci est aujourd’hui principalement utilisé dans les moteurs à allumage commandé, alors que la part des véhicules Diesel sur le marché européen est de l’ordre de 60 %. Ce constat nous a incité à proposer une formulation innovante utilisant de l’éthanol pour les applications Diesel. Les principaux verrous technologiques pour cette utilisation sont la miscibilité, la température d’éclair, la lubrification ou encore l’indice de cétane. Des travaux ont été réalisés pour optimiser la formulation contenant de l’éthanol, des biodiesels de première et seconde g

  3. Enhanced wear and fatigue properties of Ti-6Al-4V alloy modified by plasma carburizing/CrN coating.

    Science.gov (United States)

    Park, Y G; Wey, M Y; Hong, S I

    2007-05-01

    In this study, a newly developed duplex coating method incorporating plasma carburization and CrN coating was applied to Ti-6Al-4V and its effects on the wear resistance and fatigue life were investigated. The carburized layer with approximately150 microm in depth and CrN coating film with 7.5 microm in thickness were formed after duplex coating. Hard carbide particles such as TiC And V(4)C(3) were formed in the carburized layer. XRD diffraction pattern analysis revealed that CrN film had predominant [111] and [200] textures. The hardness (Hv) was significantly improved up to about 1,960 after duplex coating while the hardness value of original Ti-6Al-4V was 402. The threshold load for the modification and/or failure of CrN coating was measured to be 32 N using the acoustic emission technique. The wear resistance and fatigue life of duplex-coated Ti-6Al-4V improved significantly compared to those of un-treated specimen. The enhanced wear resistance can be attributed to the excellent adhesion and improved hardness of CrN coating film for the duplex-coated Ti-6Al-4V. The initiation of fatigue cracks is likely to be retarded by the presence of hard and strong layers on the surface, resulting in the enhanced fatigue life.

  4. Evaluation of Important Factors Affecting Quench Distortion of Carburized Hypoid Gear with Shaft by Using Computer Simulation Methods

    Institute of Scientific and Technical Information of China (English)

    Tsuyoshi Sugimoto; Youichi Watanabe

    2004-01-01

    To minimize quenching distortion and dispersion, carburizing and quenching process conditions must be optimized; this includes the parts racking design used for quenching. We investigated some factors affecting carburized quenching distortion with an experiment using a hypoid gear having a shaft and with numerical simulation methods. The experimental results and those obtained from simulation were generally in agreement. Focusing on the surface temperature distribution in the gear, we studied quenching distortion characteristics in terms of changes in tooth profile and helix deviation. In our experiments, distortions occur during quenching in 373 K oil after austenitized temperature treatments conducted with various attitudes. We calculated the distortions by simulating the carburized oil-quenching process for the hypoid gear. Our results show large differences between the cooling rates of the tooth toe, middle section, and heel edges,and these greatly influence the change in tooth profile and helix deviation. We found that reducing the differences in temperatures on the gear surfaces during quenching is most important for minimizing the quench distortion of the hypoid gear.

  5. The Effect of Surface Finish on Low-Temperature Acetylene-Based Carburization of 316L Austenitic Stainless Steel

    Science.gov (United States)

    Ge, Yindong; Ernst, Frank; Kahn, Harold; Heuer, Arthur H.

    2014-12-01

    We observed a strong influence of surface finish on the efficacy of low-temperature acetylene-based carburization of AISI 316L austenitic stainless steel. Steel coupons were prepared with different surface finishes prior to carburization, from P400 SiC grit paper to 1- µm-diameter-diamond-paste. The samples with the finer surface finish developed a thicker "case" (a carbon-rich hardened surface layer) and a larger surface carbon concentration. Transmission electron microscopy revealed that the differences arose mainly from the nature of the deformation-induced disturbed layer on the steel surface. A thick (>400 nm) disturbed layer consisting of nano-crystalline grains (≈10 nm diameter) inhibits acetylene-based carburization. The experimental observations can be explained by assuming that during machining or coarse polishing, the surface oxide layer is broken up and becomes incorporated into the deformation-induced disturbed layer. The incorporated oxide-rich films retard or completely prevent the ingress of carbon into the stainless steel.

  6. Experimental method for characterization of fatigue behaviour of carburized layers; Pruefkonzept zur experimentellen Bestimmung des Ermuedungsverhaltens von einsatzgehaerteten Werkstoffzustaenden

    Energy Technology Data Exchange (ETDEWEB)

    Kleemann, Andreas; Thumser, Rayk; Kleemann, Susanne; Winge, Joerg; Gerth, Uwe [Bauhaus Univ. Weimar (Germany). Materialforschungs- und -pruefanstalt

    2011-07-01

    Fatigue data of material states with different carbon contents are necessary for calculation of carburized parts. Experimental results on the correlation of local material structure and local endurance are not available. Up to now only carburized notched specimens and components have been investigated. In this investigation a new tube specimen with homogenous carbon content in the wall resulting from carburization process was developed. Carbon contents of 0.18 %, 0.40 %, 0.55 % und 0.70 % in the thin wall tube specimen have been tested. Specimens were loaded with cyclic internal and monotonic external pressures. Special test rig with two pressure intensifier is introduced. With the aid of the cyclic internal and constant external pressure the whole Haigh-diagram with ratios of pressure or stress of R = {infinity} until R = 0.5 could be covered. Main load direction in the tube specimen is perpendicular to the steel rods axis. Results obtained for the used 20MnCrB5 steel grade show the same endurance limit for different carbon contents or hardness, respectively, and are significantly affected by big non-metallic inclusions. (orig.)

  7. Laws of alloyed cementite particles nucleation during heat-resistant steels carburizing

    Directory of Open Access Journals (Sweden)

    M. Yu. Semenov

    2014-01-01

    Full Text Available The article considers a problem analyzing a nucleation of cementite type carbides in carburized heat-resistant steels for the turbofan engines gear wheels.The verification of previously hypothesized mechanism of dislocation nucleation particles chromium-alloyed cementite during process of carburizing was accepted as an objective of the work.As a methodological basis of this paper were accepted the numerical experiments based on the kinetic theory of nucleation, as well as on the known results of experimental studies.According to the kinetic theory of nucleation, a new phase in the solid solutions take place in the defects of the crystal structure of the metal such as inter-grain boundaries and dislocations clusters. A principle feature of the inter-grain boundary mechanism of nucleation is formation of carbide lattice. It is of great practical interest because the cementite lattice drops mechanical properties of hardened parts.According to the experimental studies, the average chromium concentration in the alloyed cementite twice exceeds its Cr content in the heat-resistant steels. Furthermore, the areas of abnormally high (more than ten times in comparison with the average content chromium concentration in cementite have been experimentally revealed.Numerical experiments have revealed that the nucleation of cementite particles alloyed with chromium (chromium concentration of 3% or more occurs, mainly, by the dislocation mechanism on the concentration fluctuations of the alloying element. According to calculations, an obligatory prerequisite to start an active nucleation process of new phase in the solid solution is a local increase of the chromium concentration up to 40%.Despite the lack of physical prerequisites for the formation of chromium precipitates, this phenomenon is explained by a strong chemical affinity of chromium and carbon, causing diffusion of chromium atoms in the region of the carbon atoms clusters. The formation of carbon

  8. Non-vacuum electron-beam carburizing and surface hardening of mild steel

    Energy Technology Data Exchange (ETDEWEB)

    Bataev, I.A., E-mail: ivanbataev@ngs.ru [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Golkovskii, M.G., E-mail: M.G.Golkovski@inp.nsk.su [Budker Institute of Nuclear Physics SB RAS, Lavrentieva Prospect 11, 630090 Novosibirsk (Russian Federation); Losinskaya, A.A., E-mail: anna.losinskaya@mail.ru [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Bataev, A.A., E-mail: bataev@adm.nstu.ru [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Popelyukh, A.I., E-mail: aip13@mail.ru [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Hassel, T., E-mail: hassel@iw.uni-hannover.de [Leibniz University, Welfengarten 1, 30167 Hannover (Germany); Golovin, D.D., E-mail: ddgolovin@yandex.ru [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation)

    2014-12-15

    Highlights: • Steel specimens were carburized by non-vacuum electron-beam cladding. • The depth of the clad layers reached 2.6 mm. • The cladding rate was 1.8 m{sup 2}/h, the quenching rate 12.6 m{sup 2}/h. • The microhardness of the quenched and tempered layers reached 8 GPa. - Abstract: In this paper, we study the structure, microhardness, and tribological properties of surface layers of mild (0.19% C) steel, which was formed by electron-beam cladding with an iron–graphite powder mixture followed by quenching and tempering. A 1.4 MeV electron beam that was extracted into air was used. Cladding of steel with the iron–graphite mixture at a beam current of 24 and 26 mA formed a hypoeutectic cast iron layer (2.19% C) and a hypereutectoid steel (1.57% C) layer, which were 2.0 and 2.6 mm thick, respectively. The microhardness of the surface-quenched and tempered steel and cast iron layers was 7 and 8 GPa, respectively. Electron-beam quenching of the surface layers of hypoeutectic cast iron was accompanied with multiple cracking. During the quenching of the 1.57% C steel layer, crack formation was not observed. In friction tests against fixed and loose abrasive particles, the surface layers of hypereutectoid steel and hypoeutectic cast iron that were produced by electron-beam cladding and quenching had lower wear rates than mild steel after pack carburizing, quenching, and tempering. In the sliding wear tests, the cast iron clad layer, which was subjected to electron-beam quenching and tempering, exhibited the highest wear resistance. Electron-beam treatment can be used to harden local areas of large workpieces. It is reasonable to treat clad layers of high-carbon steel with electron-beam quenching and tempering. To prevent multiple cracking, white cast iron layers should not be quenched.

  9. Catalyseurs à base de cobalt supportés sur carbure de silicium et nano-carbones pour la synthèse de Fischer-Tropsch

    OpenAIRE

    Liu, Yuefeng

    2013-01-01

    The Fischer-Tropsch synthesis (FTS) is a key technology to transform the synthesis gas (2H2 + CO) into liquid hydrocarbons as the basic chemical feedstock. It can be found that the cobalt active sites supported on the materials with high thermal conductivity, opened structure is necessary to accelerate FTS synthesis process in the development of industry catalysts.In this work, a new hierarchical support consisting of α-Al2O3, which is homogeneously covered by a layer of carbon nanotubes, is ...

  10. The World's Largest Steel Casting Poured Successfully

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ The world's largest steel casting -- the upper beam (or the top head) for free forging oil hydraulic press with a 18,000-ton force capacity, was poured successfully by CITIC Heavy Machinery Co., Ltd. (CITICHM) on May 22, 2008. This head piece is 11.95 meters long, 3.8 meters wide, 4.59 meters high and about 520 tons in gross weight. Pouring is the most important and critical step during its manufacturing process. The production of this huge casting requires about 830 tons of refined molten steel from 10 smelting furnaces and pouring with six ladles into the mold cavity at one time, which made it currently the world's largest steel casting poured and the most one-time molten steel organized.

  11. 1Cr11Ni2W2MoV不锈钢气体渗碳工艺%Gas Carburizing Process for 1Cr11Ni2W2MoV Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    杨亚宁; 张波; 卢华

    2011-01-01

    介绍了1Cr11Ni2W2MoV不锈钢在多用炉中低温气体渗碳的方法,解决了该材料低温渗碳层不均匀的问题.结果表明:零件渗碳前经吹砂或磷化,渗碳时通人NH,能够保证渗碳层均匀.%The gas carburizing process at low temperature in multi-furnace for 1Cr11Ni2W2MoV stainless steel was introduced.The problem of non uniform carburizing coating was solved.The results show that the carburized case uniformity can be ensured through sand blasting or phosphating before carburizing, and NH3 is filled during carburizing.

  12. The wetting behaviour of silver on carbon, pure and carburized nickel, cobalt and molybdenum substrates

    Energy Technology Data Exchange (ETDEWEB)

    Hula, Robert C., E-mail: robert.hula@tuwien.ac.at [Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/164, A-1060 Wien (Austria); Edtmaier, Christian; Holzweber, Markus; Hutter, Herbert [Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/164, A-1060 Wien (Austria); Eisenmenger-Sittner, Christoph [Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A 1040 Wien (Austria)

    2010-05-01

    Properties such as thermal and electrical conductivity or the expansion behaviour of silver matrix composites with carbon based inclusions are strongly affected by the contact angle between carbon and silver. In order to promote wetting of carbon, insertion of metallic interlayers such as nickel, cobalt or molybdenum is a feasible approach. This paper presents contact angle measurements done with the sessile drop method on carbon substrates (glassy carbon, polycrystalline graphite) and on pure nickel, cobalt and molybdenum foils. The ability of these interlayer elements to lower the high contact angles of silver on glassy carbon (117 deg.) and polycrystalline graphite (124 deg.) under vacuum conditions was verified. Unlike nickel (30 deg.) and cobalt (26 deg.), molybdenum (107 deg.) nevertheless was not wettable by liquid silver (at 1273 K) under vacuum conditions. ToF-SIMS was used to identify oxygen on the surface, causing higher contact angles than expected. After oxide reduction a contact angle of 18 deg. on molybdenum was detected. Furthermore, the influence of carbon diffusion on the contact angle was investigated by gas phase carburization of the metal foils. ToF-SIMS and XRD identified dissolved carbon (Ni, Co) and carbide formation (Mo). However, only nickel and cobalt showed a slight decrease of the contact angle due to carbon uptake.

  13. Monitoring preparation and phase transitions of carburized W(1 1 0) by reflectance difference spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, Magdalena [Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck (Austria); Memmel, Norbert, E-mail: norbert.memmel@uibk.ac.at [Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck (Austria); Bertel, Erminald [Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck (Austria); Denk, Mariella; Hohage, Michael; Zeppenfeld, Peter [Institute of Experimental Physics, Johannes Kepler University Linz, Altenbergerstr. 69, A-4040 Linz (Austria)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Real-time in situ monitoring of W(1 1 0) surface cleaning. Black-Right-Pointing-Pointer Real-time in situ monitoring of carburazation kinetics on W(1 1 0) by RDS. Black-Right-Pointing-Pointer Phase transformation R(15 Multiplication-Sign 3)-C/W(1 1 0)-R(15 Multiplication-Sign 12)-C/W(1 1 0) studied by RDS, AES and LEED. - Abstract: Reflectance difference spectroscopy (RDS) is applied to follow in situ the preparation of clean and carburized W(1 1 0) surfaces and to study the temperature-induced transition between the R(15 Multiplication-Sign 3) and R(15 Multiplication-Sign 12) carbon/tungsten surface phases. RDS data for this transition are compared to data obtained from Auger-electron spectroscopy and low-energy electron diffraction. All techniques reveal that this transition, occurring around 1870 K, is reversible with a small hysteresis, indicating a first-order-like behaviour. The present results also prove a high surface sensitivity of RDS, which is attributed to the excitation of electronic p-like surface resonances of W(1 1 0).

  14. Enhancing the wear resistance of case carburized steel (En 353) by cryogenic treatment

    Science.gov (United States)

    Bensely, A.; Prabhakaran, A.; Mohan Lal, D.; Nagarajan, G.

    2005-12-01

    All mechanical components that undergo sliding or rolling contact are subject to some degree of wear. So wear is an important tribological phenomenon while studying the failure of components. The observed frequent failure of crown and pinion due to wear and fatigue lead to this study on effect of cryogenic treatment on the wear resistance of case carburized steel (En 353). This paper deals with the pin on disk wear test without lubrication as per ASTM standard, designation: G 99-95A. The test was carried out for three different load conditions and seven sliding speeds for the samples, which has undergone three different treatment conditions namely conventional heat treatment (CHT), shallow cryogenic treatment (SCT) and deep cryogenic treatment (DCT). It has been found that the wear resistance has been considerably increased due to shallow cryogenic treatment and deep cryogenic treatment includes much more improvement in wear resistance when compared to conventional heat treatment. Also it is concluded that for better wear resistance, it is advisable to go for deep cryogenic treatment. The results are consistent with the previous studies reported in the literature on cryogenic treatments for other materials.

  15. Austenite Grain Growth and Precipitate Evolution in a Carburizing Steel with Combined Niobium and Molybdenum Additions

    Science.gov (United States)

    Enloe, Charles M.; Findley, Kip O.; Speer, John G.

    2015-11-01

    Austenite grain growth and microalloy precipitate size and composition evolution during thermal processing were investigated in a carburizing steel containing various additions of niobium and molybdenum. Molybdenum delayed the onset of abnormal austenite grain growth and reduced the coarsening of niobium-rich precipitates during isothermal soaking at 1323 K, 1373 K, and 1423 K (1050 °C, 1100 °C, and 1150 °C). Possible mechanisms for the retardation of niobium-rich precipitate coarsening in austenite due to molybdenum are considered. The amount of Nb in solution and in precipitates at 1373 K (1100 °C) did not vary over the holding times evaluated. In contrast, the amount of molybdenum in (Nb,Mo)C precipitates decreased with time, due to rejection of Mo into austenite and/or dissolution of fine Mo-rich precipitates. In hot-rolled alloys, soaking in the austenite regime resulted in coarsening of the niobium-rich precipitates at a rate that exceeded that predicted by the Lifshitz-Slyozov-Wagner relation for volume-diffusion-controlled coarsening. This behavior is attributed to an initial bimodal precipitate size distribution in hot-rolled alloys that results in accelerated coarsening rates during soaking. Modification of the initial precipitate size distribution by thermal processing significantly lowered precipitate coarsening rates during soaking and delayed the associated onset of abnormal austenite grain growth.

  16. Pitting and Bending Fatigue Evaluations of a New Case-Carburized Gear Steel

    Science.gov (United States)

    Krantz, Timothy; Tufts, Brian

    2007-01-01

    The power density of a gearbox is an important consideration for many applications and is especially important for gearboxes used on aircraft. One approach to improving power density of gearing is to improve the steel properties by design of the alloy. The alloy tested in this work was designed to be case-carburized with surface hardness of Rockwell C66 after hardening. Test gear performance was evaluated using surface fatigue tests and single-tooth bending fatigue tests. The performance of gears made from the new alloy was compared to the performance of gears made from two alloys currently used for aviation gearing. The new alloy exhibited significantly better performance in surface fatigue testing, demonstrating the value of the improved properties in the case layer. However, the alloy exhibited lesser performance in single-tooth bending fatigue testing. The fracture toughness of the tested gears was insufficient for use in aircraft applications as judged by the behavior exhibited during the single tooth bending tests. This study quantified the performance of the new alloy and has provided guidance for the design and development of next generation gear steels.

  17. Analyses of quenching process during turn-off of plasma electrolytic carburizing on carbon steel

    Science.gov (United States)

    Wu, Jie; Liu, Run; Xue, Wenbin; Wang, Bin; Jin, Xiaoyue; Du, Jiancheng

    2014-10-01

    Plasma electrolytic carburizing (PEC) under different turn-off modes was employed to fabricate a hardening layer on carbon steel in glycerol solution without stirring at 380 V for 3 min. The quenching process in fast turn-off mode or slow turn-off mode of power supply was discussed. The temperature in the interior of steel and electron temperature in plasma discharge envelope during the quenching process were evaluated. It was found that the cooling rates of PEC samples in both turn-off modes were below 20 °C/s, because the vapor film boiling around the steel sample reduced the cooling rate greatly in terms of Leidenfrost effect. Thus the quench hardening hardly took place, though the slow turn-off mode slightly decreased the surface roughness of PEC steel. At the end of PEC treatment, the fast turn-off mode used widely at present cannot enhance the surface hardness by quench hardening, and the slow turn-off mode was recommended in order to protect the electronic devices against a large current surge.

  18. A metastable chromium carbide powder obtained by carburization of a metastable chromium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Loubiere, S. [Univ. Paul-Sabatier, Toulouse (France). Lab. de Chimie des Materiaux Inorganique; Laurent, C. [Univ. Paul-Sabatier, Toulouse (France). Lab. de Chimie des Materiaux Inorganique; Bonino, J.P. [Univ. Paul-Sabatier, Toulouse (France). Lab. de Chimie des Materiaux Inorganique; Rousset, A. [Univ. Paul-Sabatier, Toulouse (France). Lab. de Chimie des Materiaux Inorganique

    1996-10-15

    A metastable Cr{sub 3}C{sub 2-x} carbide powder is prepared by carburization of a metastable chromium oxide in H{sub 2}-CH{sub 4} atmosphere under the appropriate conditions (temperature, dwell time and CH{sub 4} content). A very high specific surface area (greater than 210 m{sup 2} g{sup -1}) of the starting oxide is necessary to avoid the formation of the sole stable Cr{sub 3}C{sub 2} phase. The transformation from the stable Cr{sub 3}C{sub 2} to the metastable Cr{sub 3}C{sub 2-x} is observed for the first time. The driving force could be an epitaxial effect between Cr{sub 3}C{sub 2-x} and the surrounding graphite layer. This is consistent with the observation that the formation of graphite layers by CH{sub 4} cracking is easier in the Cr{sub 3}C{sub 2-x}-containing powders. (orig.)

  19. Calibration of eddy current carburization measurements in ethylene production tubes using ion beam analysis

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, K J [Materials Performance Technologies, Industrial Research Ltd, PO Box 31-310, Lower Hutt (New Zealand); Trompetter, W J [Rafter Laboratory, Institute of Geological and Nuclear Sciences, PO Box 31-312, Lower Hutt (New Zealand)

    2004-02-07

    Nuclear reaction analysis using a {sup 12}C(d, p{sub 0}){sup 13}C reaction and a {sup 16}O(d, p{sub 1}){sup 17}O reaction, with 1.02 MeV deuterons in an accelerator microprobe, has been used to produce quantitative linescans of the carbon and oxygen levels in ex-service ethylene pyrolysis tubes of HPM, HK40 and Manaurite XM alloy. Particle induced x-ray emission in the ion beam microprobe and energy dispersive analysis of x-rays in a scanning electron microscope were used for linescans of the heavier elements (Cr, Ni, Fe, Si and Ti). The composition linescans were used to calibrate the response and accuracy of an eddy current probe system for measuring carburization near the inner surface of the tubes. The influence of the ferromagnetic outer oxide surface layers has been clarified. A two-dimensional ANSYS finite element model (FEM) was used for interpretation of the eddy current scans. Good correlation was obtained between the ion beam analysis results, the impedance scans and the FEM.

  20. Calibration of eddy current carburization measurements in ethylene production tubes using ion beam analysis

    Science.gov (United States)

    Stevens, K. J.; Trompetter, W. J.

    2004-02-01

    Nuclear reaction analysis using a 12C(d, p0)13C reaction and a 16O(d, p1)17O reaction, with 1.02 MeV deuterons in an accelerator microprobe, has been used to produce quantitative linescans of the carbon and oxygen levels in ex-service ethylene pyrolysis tubes of HPM, HK40 and Manaurite XM alloy. Particle induced x-ray emission in the ion beam microprobe and energy dispersive analysis of x-rays in a scanning electron microscope were used for linescans of the heavier elements (Cr, Ni, Fe, Si and Ti). The composition linescans were used to calibrate the response and accuracy of an eddy current probe system for measuring carburization near the inner surface of the tubes. The influence of the ferromagnetic outer oxide surface layers has been clarified. A two-dimensional ANSYS finite element model (FEM) was used for interpretation of the eddy current scans. Good correlation was obtained between the ion beam analysis results, the impedance scans and the FEM.

  1. Carburization of tungsten filaments in a hot-wire chemical vapor deposition process using 1,1,3,3-tetramethyl-1,3-disilacyclobutane.

    Science.gov (United States)

    Tong, L; Shi, Y J

    2009-09-01

    The alloying of tungsten filament when using 1,1,3,3-tetramethyl-1,3-disilacyclobutane (TMDSCB) in a hot-wire chemical vapor deposition reactor was systematically studied by scanning electron microscopy, Auger electron spectroscopy, analysis of the power consumed by the filament, and in situ mass spectrometric measurements of the gas-phase species produced in the process. Only carburization of the W filament was observed. The carburization is mainly caused by the interaction of methyl radicals with the filament. Graphite as well as both WC and W2C alloys can form on the filament surface, depending on the filament temperatures and source gas pressures. Both WC and graphite are converted to W2C with the diffusion of C into the filament. It is shown that filament carburization affects the consumption rate of the source gas and the intensities of gas-phase reaction products. Gas-phase reactions dominate at T or = 1800 degrees C.

  2. Design method of hardened depth for carburized gear%渗碳齿轮硬化层深度设计方法

    Institute of Scientific and Technical Information of China (English)

    肖伟中; 刘忠明; 袁玉鹏

    2014-01-01

    Based on the calculating method of contact strength , the shear stress distribution along the depth direction of gear surface was calculated, from the relationship of shear stress and shear strength , the lowest hardness distribution curve for carburized gear was obtained . Based on the lowest hardness distribution curve , the hardness distribution for carburized gears was designed , and the available hardened depth of carburized gears was obtained .%基于接触强度计算方法,计算出了齿轮沿齿面深度方向的剪切应力分布,通过剪切应力与剪切强度的关系,得到了渗碳齿轮最低要求的硬度分布曲线,在此基础上,设计出了齿轮硬化层硬度分布,得到有效硬化层深度。

  3. Research on Parts Process of V-shape Slot Carburizing Quenching%V型槽渗碳淬火零件加工工艺研究

    Institute of Scientific and Technical Information of China (English)

    陈惠娟; 黄玉方; 梁壮; 王健

    2012-01-01

    通过对V型槽渗碳淬火类零件的特性及加工难点的分析,研究V型槽渗碳淬火类零件的工艺总方案及加工工艺.主要针对2种不同结构类型的V型槽渗碳淬火类零件的加工工艺及加工过程进行分析,探讨V型槽渗碳淬火零件的特殊加工方法.通过对V型槽渗碳淬火类零件的生产加工和加工过程中的工艺改进与完善,摸索到了加工V型槽渗碳淬火零件的一些经验,供大家参考.%By analyzing the characteristics of V-shape slot carburizing quenching parts and the difficulties of processing, the paper mainly focused on the general plan and processing technology of the V-shape slot carburizing quenching parts. By analyzing parts processing technology and processing procedure of two different structures of the V-shape slot carburizing quenching, the paper discussed the specific processing method of the V-shape slot carburizing quenching parts. By making improvements and perfection of the production processing and the process technology of the V-shape slot carburizing quenching parts, we have got some experiences from the processing of the V-shape slot carburizing quenching parts for your reference.

  4. Did the First Iron Blacksmiths Learn to Carburize Iron? Part II: Experiments Showing That it is Very Likely That They Did

    Science.gov (United States)

    Verhoeven, J. D.; Pendray, A. H.; Dauksch, W. E.

    2016-08-01

    Results of short-time carburizing of wrought iron in a charcoal-fired furnace present strong evidence that our earliest blacksmith ancestors probably discovered how to carburize their bloomery iron and produced cutting and scraping tools superior to bronze tools shortly after they had learned to make this iron in the 1200-900 BC time period. Their bloomery iron needed to be forged to make useful tools and it seems likely that at least some of them heated the iron to the forging temperature in charcoal burning in their bloomery furnaces, the same arrangement as used here.

  5. Non-vacuum electron-beam carburizing and surface hardening of mild steel

    Science.gov (United States)

    Bataev, I. A.; Golkovskii, M. G.; Losinskaya, A. A.; Bataev, A. A.; Popelyukh, A. I.; Hassel, T.; Golovin, D. D.

    2014-12-01

    In this paper, we study the structure, microhardness, and tribological properties of surface layers of mild (0.19% C) steel, which was formed by electron-beam cladding with an iron-graphite powder mixture followed by quenching and tempering. A 1.4 MeV electron beam that was extracted into air was used. Cladding of steel with the iron-graphite mixture at a beam current of 24 and 26 mA formed a hypoeutectic cast iron layer (2.19% C) and a hypereutectoid steel (1.57% C) layer, which were 2.0 and 2.6 mm thick, respectively. The microhardness of the surface-quenched and tempered steel and cast iron layers was 7 and 8 GPa, respectively. Electron-beam quenching of the surface layers of hypoeutectic cast iron was accompanied with multiple cracking. During the quenching of the 1.57% C steel layer, crack formation was not observed. In friction tests against fixed and loose abrasive particles, the surface layers of hypereutectoid steel and hypoeutectic cast iron that were produced by electron-beam cladding and quenching had lower wear rates than mild steel after pack carburizing, quenching, and tempering. In the sliding wear tests, the cast iron clad layer, which was subjected to electron-beam quenching and tempering, exhibited the highest wear resistance. Electron-beam treatment can be used to harden local areas of large workpieces. It is reasonable to treat clad layers of high-carbon steel with electron-beam quenching and tempering. To prevent multiple cracking, white cast iron layers should not be quenched.

  6. Short-term creep properties of Ti-6Al-4V alloy subjected to surface plasma carburizing process

    Directory of Open Access Journals (Sweden)

    Verônica Mara Cortez Alves de Oliveira

    2015-10-01

    Full Text Available The aim of this study was to investigate the short-time creep behavior of Ti-6Al-4V by plasma carburizing, which was performed at 725 °C for 6 h in a 50% Ar – 45% H2 – 5% CH4 gas mixture. Nano and microhardness testing, optical microscopy, TEM, X-ray diffraction and optical profilometry were used to characterize the samples. Furthermore, short-term creep tests were performed under a constant tensile load in air at 600 °C using a dead-weight-creep-rupture machine. The carburizing treatment resulted in a compound layer measuring approximately 1.7 μm in thickness with a hardness of 815 HV and a composition of TiC0.66. The creep properties of the “Widmanstätten + carburized” specimens were improved relative to those of untreated specimens. TEM and fracture analysis indicated creep deformation process attributed mainly to α phase deformation and fracture by intergranular decohesion.

  7. Study of Effect of Quenching Deformation Influenced by 17CrNiMo6 Gear Shaft of Carburization

    Science.gov (United States)

    Pang, Zirui; Yu, Shenjun; Xu, Jinwu

    The 17CrNiMo6 steel is mainly used for the gear shaft of large modulus in many fields of heavy industry such as mining, transit, hoist, forging and so on[1]. The size of addendum circle and common normal line is changed a lot beyond the tolerance because of the long time of carburizing process and the out-of-step structural stress and thermal stress during the quenching process. And thus the posterior grinding efficiency and quality are influenced. In the paper comparison and analysis of the deformation affected by solid and hollow gear shafts were done and the methods of simulation and practice were both used. The results are as follows: the deformation of gear shaft was small before and after carburizing while that of gear shaft was large before and after quenching because of different cooling velocity, structure and hardness of each position. And the deformation of hollow was much smaller than that of solid. Therefore, if the hollow gear shaft is used, the waste of material will be decreased, and finishing cost will be reduced, and thus the technology of heat treatment will be optimized.

  8. Single-step thermal carburization synthesis of supported molybdenum carbides from molybdenum-containing methyl-silica

    Institute of Scientific and Technical Information of China (English)

    Juan Zou; Minglin Xiang; Bo Hou; Dong Wu; Yuhan Sun

    2011-01-01

    A novel synthesis route to obtain highly dispersed molybdenum carbides in porous silica is described. The synthesis was carried out by a single-step heat treatment of molybdenum-containing and methyl-modified silica (Mo-M-SiO2) in argon atmosphere at 973 K. Mo-M-SiO2 precursor was facilely obtained via a one-pot synthesis route, using (NH4)6Mo7O24·4H2O (AHM) as molybdenum sources and polymethylhydrosiloxane (PMHS) as silica sources at the initial synthetic step. The optimal C/Mo molar ratio in reaction system for complete carburization of molybdenum species was 7. The carburization process of molybdenum species followed a nontopotactic route involving a MoO2 intermediate phase, which was evidenced by XRD, N2 adsorption-desorption and in situ XPS. Formation mechanism of Mo-M-SiO2 precursor was also proposed by observation of the reaction between AHM and PMHS with TEM. Furthermore, by adding TEOS into silica sources and adjusting TEOS/PMHS mass ratio, crystal phase of molybdenum carbides transferred fromβ-Mo2C to α-MoC1-x, and SiO2 structure changed from microporous to micro/mesoporous. Catalytic performances of samples were tested using CO hydrogenation as a probe reaction. The supported molybdenum carbides exhibited high selectivity for higher alcohol synthesis compared with bulkβ-Mo2C and α-MoC1-x.

  9. TiC nanocrystal formation from carburization of laser-grown Ti/O/C nanopowders for nanostructured ceramics.

    Science.gov (United States)

    Leconte, Y; Maskrot, H; Herlin-Boime, N; Porterat, D; Reynaud, C; Gierlotka, S; Swiderska-Sroda, A; Vicens, J

    2006-01-12

    Refractory carbide ceramics (TiC and ZrC) raise interest as promising materials for high-temperature applications such as structural materials for the future generation of nuclear reactors. In this context, nanostructured ceramics are expected to exhibit improved thermomechanical properties as well as better behavior under irradiation when compared to conventional materials. It is therefore necessary to synthesize carbide nanocrystals of such materials to elaborate the ceramics. We report here the formation study of TiC nanocrystals through the direct carburization of Ti/O/C nanopowders grown by laser pyrolysis. A spray of titanium tetraisopropoxide was laser pyrolyzed with ethylene as the sensitizer, leading to Ti/O/C nanopowders with various C contents controlled by the synthesis conditions. Annealing treatments performed on these nanopowders under an inert atmosphere without any C addition enabled the formation of TiC grains through the carburization of the oxide phase by free C incorporated during the synthesis. The powders were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The final TiC grain size was about 80 nm, and the grains were monocrystalline. The influence of the free C content on the grain growth during the annealing step, together with its effects on the densification of the ceramics after sintering by high-pressure flash sintering, was examined. A 93% densification was finally achieved.

  10. The Proper Process Parameter of Brush Copperplating and the Minimun Thickness of Copper Film for Prevention of Carburization%防渗碳刷镀镀铜的工艺参数及镀层厚度选择

    Institute of Scientific and Technical Information of China (English)

    谢辅洲; 王桂芳; 郑玉丽

    2001-01-01

    In this paper, the effects of process parameter of brush copperplating on the copper film for prevention of carburization were studied; the relation between the time of carburization and the minimun thickness of copper film for prevention of carburization was established.%研究了用刷镀镀铜防渗碳时的工艺参数对镀层防渗碳效果的影响,及渗碳时间与防渗碳所需的最小镀层厚度之间的关系。

  11. Silica-templated synthesis of ordered mesoporous tungsten carbide/graphitic carbon composites with nanocrystalline walls and high surface areas via a temperature-programmed carburization route.

    Science.gov (United States)

    Wu, Zhangxiong; Yang, Yunxia; Gu, Dong; Li, Qiang; Feng, Dan; Chen, Zhenxia; Tu, Bo; Webley, Paul A; Zhao, Dongyuan

    2009-12-01

    Ordered mesostructured tungsten carbide and graphitic carbon composites (WC/C) with nanocrystalline walls are fabricated for the first time by a temperature-programmed carburization approach with phosphotungstic acid (PTA) as a precursor and mesoporous silica materials as hard templates. The mesostructure, crystal phase, and amount of deposited graphitic carbon can be conveniently tuned by controlling the silica template (SBA-15 or KIT-6), carburizing temperature (700-1000 degrees C), the PTA-loading amount, and the carburizing atmosphere (CH(4) or a CH(4)/H(2) mixture). A high level of deposited carbon is favorable for connecting and stabilizing the WC nanocrystallites to achieve high mesostructural regularity, as well as promoting the carburization reaction. Meanwhile, large pore sizes and high mesoporosity of the silica templates can promote WC-phase formation. These novel, ordered, mesoporous WC/C nanocomposites with high surface areas (74-169 m(2) g(-1)), large pore volumes (0.14-0.17 cm(3) g(-1)), narrow pore-size distributions (centered at about 3 nm), and very good oxidation resistance (up to 750 degrees C) have potential applications in fuel-cell catalysts and nanodevices.

  12. INFLUENCE OF THE THERMAL PROCESS STAGE ON THE SIZE OF VALID GRAIN OF CONSTRUCTIONAL CARBURIZED STEEL GRADE 20CHN3A

    Directory of Open Access Journals (Sweden)

    S. P. Rudenko

    2016-01-01

    Full Text Available Results of studies of the kinetics of changes in actual grains during technological process at different stages of the manufacture of parts with the use of a universal metallographic etchant to identify borders of valid grains in rolling and stamping in carburizing layers and core parts made of alloy structure steel grades are presented.

  13. Effect of the Content of Retained Austenite and Grain Size on the Fatigue Bending Strength of Steels Carburized in a Low-Pressure Atmosphere

    Science.gov (United States)

    Kula, P.; Dybowski, K.; Lipa, S.; Januszewicz, B.; Pietrasik, R.; Atraszkiewicz, R.; Wołowiec, E.

    2014-11-01

    The effect of the content of retained austenite and of the initial austenite grain size on high-cycle fatigue of two low-alloy steels 16MnCr5 and 17CrNi6-6 after carburizing in a low-pressure atmosphere (acetylene, ethylene and hydrogen) and subsequent high-pressure gas quenching is investigated.

  14. PM Axial Flux Machine Design for Hybrid Traction Conception d’une machine à flux axial à aimants permanents pour la traction hybride

    Directory of Open Access Journals (Sweden)

    de la Barrière O.

    2009-11-01

    Full Text Available the best ways in order to reduce fuel consumption for vehicles. It consists of associating an electric motor next to the classical thermal machine. In this embedded system, the efficiency and the torque per unit mass are very important. So it seems to be a good idea to use a permanent magnet synchronous machine, which is recognized for satisfying these two objectives. Since the allocated volume is rather flat, axial flux topologies are interesting. This paper’s goal is to propose an optimal first design method for such structures, given the allocated volume and the machine requirements. La traction hybride semble actuellement un des moyens les plus prometteurs pour réduire la consommation de carburant des véhicules. Ce procédé consiste à associer un moteur électrique au moteur thermique traditionnel. Pour une telle application embarquée, le rendement, ainsi que le couple massique, sont des critères de conception de première importance. Dans ce contexte, le recours à une machine synchrone à aimants permanents, reconnue pour satisfaire ces deux critères, semble être approprié. Vu que le volume alloué à la machine électrique est de forme discoïde, les topologies à flux axial semblent les plus intéressantes. L’objectif de cet article est de proposer une méthodologie de pré-dimensionnement de tels actionneurs, en ayant fixé au préalable le volume maximal permis ainsi que le cahier des charges de la machine.

  15. Utilisation des huiles végétales et de leurs produits de transestérification comme carburants Diesel Use of Vegetable Oils and Their Transesterification Products As Diesel Fuels

    Directory of Open Access Journals (Sweden)

    Gateau P.

    2006-11-01

    Full Text Available L'utilisation d'huiles végétales et de leurs dérivés comme carburants Diesel a fait l'objet, depuis 1981, de plusieurs études financées par l'Agence Française pour la Maîtrise de l'Energie (AFME et réalisées par l'institut Français du Pétrole (lFP en collaboration avec Elf Renault, le Centre d'Etudes et d'Expérimentation du Machinisme Agricole Tropical (CEEMAT et l'institut de Recherches pour les Huiles et Oléagineux (IRHO. Ce document rassemble les résultats obtenus au banc d'essai sur plusieurs types de moteurs représentant un assez large éventail d'applications, depuis le motoculteur utilisé en agriculture africaine jusqu'au moteur classique de tracteur ou de camion. Deux types de produits ont été examinés : les huiles végétales elles-mêmes employées pures ou en mélange au gazole, et les esters méthyliques de ces huiles utilisés tels quels. Lors d'un fonctionnement de courte durée les huiles aussi bien que les esters conduisent globalement à un fonctionnement satisfaisant du moteur; les pertes de performances par rapport au gazole restent modérées voire imperceptibles. Les seuls problèmes dans ce cas concernent la mise en oeuvre, difficile avec les huiles en raison de leur très forte viscosité, beaucoup plus aisée avec les esters. En endurance, l'inconvénient majeur des huiles végétales et de leurs dérivés concerne la formation de dépôts au nez des injecteurs. Sur les moteurs rustiques à préchambre (type Hatz ce phénomène reste limité puisqu'il a été possible de conduire, sans incident, un ensemble d'essais d'endurance de 1100 h avec différents types d'huiles pures (arachide, coton, palme. Sur les moteurs à Injection directe la formation de dépôts constitue une très sérieuse contrainte puisqu'elle conduit pratiquement à proscrire l'utilisation d'huiles même en mélange (25 ou 50 % dans le gazole. Les esters peuvent alors être proposés à condition qu'un certain nombre de pr

  16. Study on Structure and Corrosion Resistance Analysis of Carburizing Organization of Austenitic Stainless Steel%奥氏体不锈钢渗碳层的组织及耐蚀强化性能研究

    Institute of Scientific and Technical Information of China (English)

    李朋; 潘邻; 张良界; 杨闽红; 朱云峰; 马飞; 王成虎

    2013-01-01

    针对常规渗碳工艺会削弱奥氏体不锈钢耐蚀性的问题,通过对现有气体渗碳技术进行改进,采用前处理活化、降低渗碳温度的方法,实现了奥氏体不锈钢渗碳兼顾表面强度与耐蚀性能的目标.采用该工艺对AISI304和AISI316奥氏体不锈钢进行渗碳处理,并分析渗层组织和性能,结果表明,在470℃条件下,AISI316不锈钢经气体渗碳处理后,渗碳层具有优异的耐蚀强化性能.%In view of the conventional carburization weakening austenitic stainless steel corrosion resistance problem,based on the existing gas carburizing technology was improved,using pretreatment activation,carburizing temperature reduction methods,realized the austenitic stainless steel carburized surface strength and corrosion resistant properties of the target.Using this process on AISI304,AISI316 austenitic stainless steel carburizing processing,and get the austenitic stainless steel for low temperature carburizing organization performance carries on the analysis and research,research shows that under the condition of 470 ℃,AISI316 stainless steel carburization treated by low temperature gas carburizing layer has excellent corrosion resistance improved performance.

  17. 渗碳温度对22Si2MnCrNi2MoA钢渗碳层的影响%Influence of carburizing temperature on microstructure and properties of carburized layers of a 22Si2MnCrNi2MoA steel

    Institute of Scientific and Technical Information of China (English)

    黄斌; 朱洪武; 杨忠; 周乐育; 刘雅政

    2013-01-01

    Influence of carburizing temperature on carburized layers of a 22Si2MnCrNi2MoA steel solid-carburized was studied by OM,SEM,XRD and hardness measurements.The relationship between carburizing temperature and carbon concentration,micro-hardness and retained austenite of the carburized layers were examined.The results indicate that with the carburizing temperature increasing for carburizing time of 6 h,the carbon concentration of the carburized layers gradually increases,and the distribution gradient of the carbon concentration gets smoother.The relationship between the micro-hardness of the carburized layers and carbon concentration obeys normal distribution.It is recommended that the surface carbon concentration of the carburized steel should be controlled in the range of 0.80% and 0.90% in order to obtain martensite microstructure with high hardness.When the surface carbon concentration is more than 0.80%-0.90%,aging treatment for a long time or deep cryogenic treatment are required to remove retained austenite in the carburized layers.%通过固体渗碳试验研究了加热温度对钎具用钢22Si2MnCrNi2MoA渗碳层的影响,分析了渗碳温度-碳浓度-显微硬度-残留奥氏体的关系以及残留奥氏体的控制措施.结果表明:当渗碳时间为6h时,随着渗碳温度的升高,渗碳层的碳浓度逐渐增加,碳浓度分布梯度越来越平缓.22Si2MnCrNi2MoA钢渗碳层的显微硬度-碳浓度关系符合正态分布.在渗碳处理过程中,为了使渗碳表层获得硬度很高的马氏体组织,22Si2MnCrNi2MoA钢渗碳层表面碳浓度应该控制在0.80% ~0.90%之间.当表面碳浓度超过0.80%~0.90%时,渗碳完成后需采取后续的工艺措施来消除已经存在的残留奥氏体,如采用长时间自然时效或深冷处理等.

  18. Microstructure and Cavitation Erosion Properties of Ceramic Coatings Fabricated on Ti-6Al-4V Alloy by Pack Carburizing

    Science.gov (United States)

    Li, Haibin; Cui, Zhenduo; Li, Zhaoyang; Zhu, Shengli; Yang, Xianjin

    2014-08-01

    In this study, Ti-6Al-4V alloy was processed by pack carburizing to improve the cavitation erosion behavior. X-ray diffraction and scanning-electron microscopy (SEM) analysis showed that a uniform and crack-free ceramic coating formed on the surface of the treated samples. The coating layer comprised primary TiC and less oxide. Cavitation erosion experiment results indicated that the treated samples have the factor of 3.44 to 6.68 increase in cavitation erosion resistance ( R e) as compared with the as-received sample. The ceramic coatings with high hardness and good metallurgical bonding were responsible for the enhanced cavitation erosion properties. When the coatings were treated at condition of high temperature and/or long time, the R e was enervated due to the thin oxide film formed at the outermost surface. Cavitation erosion mechanism for the coatings was characterized as brittle mode by SEM observation of the worn surfaces.

  19. Monitoring preparation and phase transitions of carburized W(1 1 0) by reflectance difference spectroscopy.

    Science.gov (United States)

    Bachmann, Magdalena; Memmel, Norbert; Bertel, Erminald; Denk, Mariella; Hohage, Michael; Zeppenfeld, Peter

    2012-10-01

    Reflectance difference spectroscopy (RDS) is applied to follow in situ the preparation of clean and carburized W(1 1 0) surfaces and to study the temperature-induced transition between the R(15 × 3) and R(15 × 12) carbon/tungsten surface phases. RDS data for this transition are compared to data obtained from Auger-electron spectroscopy and low-energy electron diffraction. All techniques reveal that this transition, occurring around 1870 K, is reversible with a small hysteresis, indicating a first-order-like behaviour. The present results also prove a high surface sensitivity of RDS, which is attributed to the excitation of electronic p-like surface resonances of W(1 1 0).

  20. Porous molybdenum carbide nano-octahedrons synthesized via confined carburization in metal-organic frameworks for efficient hydrogen production.

    Science.gov (United States)

    Wu, Hao Bin; Xia, Bao Yu; Yu, Le; Yu, Xin-Yao; Lou, Xiong Wen David

    2015-03-11

    Electrochemical water splitting has been considered as a promising approach to produce clean and sustainable hydrogen fuel. However, the lack of high-performance and low-cost electrocatalysts for hydrogen evolution reaction hinders the large-scale application. As a new class of porous materials with tunable structure and composition, metal-organic frameworks have been considered as promising candidates to synthesize various functional materials. Here we demonstrate a metal-organic frameworks-assisted strategy for synthesizing nanostructured transition metal carbides based on the confined carburization in metal-organic frameworks matrix. Starting from a compound consisting of copper-based metal-organic frameworks host and molybdenum-based polyoxometalates guest, mesoporous molybdenum carbide nano-octahedrons composed of ultrafine nanocrystallites are successfully prepared as a proof of concept, which exhibit remarkable electrocatalytic performance for hydrogen production from both acidic and basic solutions. The present study provides some guidelines for the design and synthesis of nanostructured electrocatalysts.

  1. Alcool : carburant du corps-machine (à écrire

    Directory of Open Access Journals (Sweden)

    Sophie Dubois

    2009-09-01

    Full Text Available De prime abord, il peut paraître banal d’envisager l’œuvre de Victor-Lévy Beaulieu sous l’angle de l’aliénation. En effet, maints critiques – dont Jacques Pelletier – ont déjà démontré que les personnages beaulieusiens sont « des êtres excessifs, pour ainsi dire des fous » ou des « figures pitoyables exprimant et symbolisant la condition d’aliénation, de dépossession, de déculturation sociale et historique du Canada français et l’abandon, la mollesse, la passivité avec lesquelles on peut la s...

  2. A Statistical Treatment of Bioassay Pour Fractions

    Science.gov (United States)

    Barengoltz, Jack; Hughes, David W.

    2014-01-01

    The binomial probability distribution is used to treat the statistics of a microbiological sample that is split into two parts, with only one part evaluated for spore count. One wishes to estimate the total number of spores in the sample based on the counts obtained from the part that is evaluated (pour fraction). Formally, the binomial distribution is recharacterized as a function of the observed counts (successes), with the total number (trials) an unknown. The pour fraction is the probability of success per spore (trial). This distribution must be renormalized in terms of the total number. Finally, the new renormalized distribution is integrated and mathematically inverted to yield the maximum estimate of the total number as a function of a desired level of confidence ( P(fraction. The extension to recovery efficiency corrections is also presented. Now the product of recovery efficiency and pour fraction may be small enough that the likely value may be much larger than the usual calculation: the number of spores divided by that product. The use of this analysis would not be limited to microbiological data.

  3. Precise gas carburizing quenching process of 18 Cr2 Ni4 WA steel bushes%18Cr2Ni4WA钢衬套的精密气体渗碳淬火热处理

    Institute of Scientific and Technical Information of China (English)

    李锋; 王新宇; 李世键; 韩培培; 于浩

    2016-01-01

    The influence of precise gas carburizing and isothermal quenching process on carburized layer hardness , depth and the microstructure of 18Cr2Ni4WA steel was studied .The results show that the carburized layer depth increases with the increasing of the total holding time, but the hardness profile becomes flat gradually .The longer of strong carburizing time , the deeper of carburized depth with the same total holding time .The longer of strong carburizing time , the lower of surface hardness with the same diffusion carburizing time .The optimized precise heat treatment process consists of holding temperature at 910 ℃, by carbon potential of strong carburizing stage at 1.20%and holding for 3 h, and then by carbon potential of diffusion stage at 0.80%and holding for 1 h,and then isothermally quenched in nitrate bath.With this optimized process , the typical carburized depth of (1.2 ±0.1) mm with favorable microstructure distribution is obtained . The process has been successfully applied in bushes production with satisfactory requirement of carburized depth , hardness profile and microstructure .%研究了精密气体渗碳等温淬火工艺对18Cr2Ni4WA钢渗层硬度、深度及显微组织的影响。结果表明,随着总渗碳保温时间的延长,渗层深度增加,但硬度曲线变得平缓;在相同总保温时间的情况下,强渗时间越长,渗层越深;而当扩散时间相同时,强渗时间越长,淬火后表层的硬度较低。优化的精密气体渗碳工艺为:保温温度均为910℃,强渗阶段碳势1.20%,保温3 h;扩散阶段碳势0.80%,保温1 h,渗碳后进行等温淬火,可以获得(1.2±0.1) mm渗层深度。渗碳淬火后渗层组织良好。该工艺成功应用于衬套零件的实际生产,满足了设计要求。

  4. 钛表面辉光无氢渗碳动力学与耐蚀性能研究%Study on Kinetics and Corrosion Resistance of Plasma Non-hydrogen Carburizing on Titanium Surface

    Institute of Scientific and Technical Information of China (English)

    华云峰; 李争显; 杨浩; 王宝云; 王彦峰; 姬寿长; 罗小峰; 杜继红

    2012-01-01

    C.P.Ti TA2 was carburized by double-glow plasma non-hydrogen carburizing technique. The carburizing kinetics was studied. The corrosion resistance of the carburized samples was evaluated in 3.5%NaCl and 80%H2SO4 water solution at 25 ℃. The results show that the thickness of carburized layer increases with increasing carburizing temperature and time. The relationship between the diffusion coefficient of carbon in carburized layer and the carburizing temperature accords with the Arrhenius manner. The value of diffusion activation energy is 13.6 kJ/mol (0.14 eV). The carburized sample has better corrosion resistance than Ti-0.2Pd and C.P.Ti. The corrosion rate of carburized layer is 0.00048 and 2.118 mm/a in 3.5%NaCl and 80%H2SO4 water solution, which is 77% and 50% of that of Ti-0.2Pd and 13% and 11% of that of C.P.Ti under the same condition, respectively.%采用辉光无氢渗碳方法,在工业纯钛TA2表面制备渗碳层,研究辉光无氢渗碳动力学以及渗碳试样在25℃、3.5% NaCl水溶液和25℃、80% H2SO4水溶液中的耐蚀性能.结果表明,渗碳层厚度随渗碳温度与时间的增加而增加,碳在渗碳层中的扩散系数与绝对温度之间符合Arrhenius关系式,扩散活化能为13.6 kJ/mol (0.14 eV).渗碳试样在25℃3.5% NaCl、80% H2SO4水溶液中的腐蚀速率分别为0.000 48 mm/a、2.118 mm/a,分别是Ti-0.2Pd的77%、50%,分别是TA2的13%、11%,耐蚀性能得到显著提高.

  5. Creep behavior of plasma carburized Ti-6Al-4V alloy; Comportamento em fluencia da liga Ti-6Al-4V carbonetada por plasma

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Veronica Mara Cortez Alves de; Barboza, Miguel Justino Ribeiro; Silva, Mariane Capellari Leite da; Pinto, Catia Gisele; Suzuki, Paulo Atsushi [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia; Reis, Danieli Aparecida Pereira; Piorino Neto, Francisco [Instituto de Aeronautica e Espaco (IAE/DCTA), Sao Jose dos Campos, SP (Brazil); Machado, Joao Paulo B. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil)

    2010-07-01

    This paper aims to evaluate the effect of plasma carburizing on the Ti-6Al-4V alloy submitted to creep tests. The results showed that the alloy Ti-6Al-4V had a hardness of 334 ± 18 HV. After treatment thermochemical by plasma, was observed the formation of a layer of average thickness of 1,5 μm and hardness of 809 ± 79 HV due to the presence of TiC phase identified by X-ray diffraction. The treatment increased the values of average roughness of 1,28 to 2,02 μm. The creep properties of carburized specimens were improved in comparison with those of the uncarburized Ti-6Al-4V alloy. (author)

  6. 关于真空炉渗碳过程的初步试验研究%Preliminary experimental study about vacuum furnace carburizing process

    Institute of Scientific and Technical Information of China (English)

    黄晓辉; 于滢

    2013-01-01

    通过对SG13Cr4Mo4Ni4V钢真空渗碳过程的主要影响因素进行试验分析,初步摸索了各工艺参数之间的关系,为提高该钢种真空渗碳热处理质量提供了试验数据。%Through test analysis on main affecting factors of vacuum carburizing process of SG13Cr4Ni4V steel, the relationship between the process parameters was tried to ifnd out initially in order to provide test data for improving the quality of the steel vacuum carburizing heat treatment.

  7. 拖拉机齿轮的稀土低温渗碳%Low-temperature Carburizing with Rare Earth Elements for Tractor Gears

    Institute of Scientific and Technical Information of China (English)

    樊湘芳

    2001-01-01

    介绍了稀土低温渗碳工艺在拖拉机齿轮上的应用。通过具体的数据说明该工艺实施的方便性和节能效果。通过试验得出稀土低温渗碳工艺用于井式气体渗碳炉,生产周期可缩短15%,齿轮的质量也有所提高。%The application of low-temperature carburizing with rare earth elements for tractor gears is presented in this paper.The convenience and energy saving of the technology is demonstrated in details.It is concluded that by applying rare-earth low-temperature carburizing in pit-type furnace the production period can be shorten by 15 percent and the quality of the gears is improved.

  8. Quantitatively pouring draft beer dispenser; Teiryo chushutsu nama beer dispenser

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-01-10

    Suppressing bubble generation and quantitatively pouring more stably were the large problem in draft beer or sparking liquor vending. Therefore, bubbling mechanism in draft beer was analyzed, and pouring valve and beer dispensing system were optimized to have developed a beer dispenser generating little bubbles when dispensing. Its major features are as follows: (1) a valve was developed that branches liquid and bubbles without disturbing the beer flow, thus realizing stable pouring; (2) a beer mug tray drive was developed that prevents after-drips of bubbles from entering into another mug, thus realizing stable pouring; (3) the button operated rinsing function and the pouring valve removing and attaching structure facilitate washing work; and (4) the additional pouring function and the copying function facilitate setting of the dispensing volume. (translated by NEDO)

  9. Effects of niobium additions on the structure, depth, and austenite grain size of the case of carburized 0.07% C steels

    Science.gov (United States)

    Islam, M. A.; Bepari, M. M. A.

    1996-10-01

    Carbon (0.07%) steel samples containing about 0.04% Nb singly and in combination with nitrogen were carburized in a natural Titas gas atmosphere at a temperature of 1223 K (950 °C) and a pressure of about 0.10 MPa for 1/2 to 4 h, followed by slow cooling in the furnace. Their microstructures were studied by optical microscopy. The austenite grain size of the case and the case depths were determined on baseline samples of low-carbon steels and also on niobium and (Nb + N) microalloyed steel samples. It was found that, when compared to the baseline steel, niobium alone or in combination with nitrogen decreased the thickness of cementite network near the surface of the carburized case of the steels. However, niobium in combination with nitrogen was more effective than niobium in reducing the thickness of cementite network. Niobium with or without nitrogen inhibited the formation of Widmanstätten cementite plates at grain boundaries and within the grains near the surface in the hypereutectoid zone of the case. It was also revealed that, when compared to the baseline steel, niobium decreased the case depth of the carburized steels, but that niobium with nitrogen is more effective than niobium alone in reducing the case depth. Niobium as niobium carbide (NbC) and niobium in the presence of nitrogen as niobium carbonitride, [Nb(C,N)] particles refined the austenite grain size of the carburized case, but Nb(C,N) was more effective than NbC in inhibiting austenite grain growth.

  10. Zircon Carburation Studies as Intermediate Stage in the Zirconium Fabrication; Estudios encaminados a la carburacion del circon como etapa intermedia en la obtencion de circonio

    Energy Technology Data Exchange (ETDEWEB)

    Almagro Huertas, V.; Saenz de Tejada Gonzalez, L.; Lopez Rodriguez, M.

    1963-07-01

    Zirconium carbide and carbonitride mixtures were obtained by Kroll's method.Reaction products have been identified by micrography and X-ray diffraction analysis. The optimum graphite content in the initial charge for the carburation reaction has been studied. zirconium, silicon and carbon content in the final product has been controlled as a function of current in the furnace and reaction time.Further chlorination of the final product was performed successfully. (Author) 16 refs.

  11. Experimental Study and Computer Simulation on Multicomponent Diffusion in Multiphase Dispersions During Solid Carburizing of HP40Nb and KHR45A Alloys

    Science.gov (United States)

    Zhao, Yanping; Gong, Jianming; Wang, Xiaowei; Shen, Limin; Li, Qingnan

    2015-10-01

    To simulate solid carburizing processes of HP40Nb and KHR45A alloys at 1273 K and 1373 K (1000 °C and 1100 °C), Thermo-Calc (Thermo-Calc Software, Inc., Stockholm, Sweden) and DICTRA (Thermo-Calc Software, Inc.) software analyses were performed. A model to treat multicomponent diffusion in multiphase dispersions was applied, where carbides are assumed to be distributed in face-centered cubic matrix and diffusion only occurs in the matrix. The time-dependent carbon flux determined by weight gain measurement was used as boundary condition in diffusion simulations. The calculated carbides are NbC, M23C6, and M7C3 ("M" stands for metal atoms), where M23C6 first precipitates, then M7C3 appears as carbon increases, and NbC covers the largest area of carbon content. The results show that carburization resistance is much better for KHR45A than HP40Nb due to the addition of elements (Si, Cr, Ni, and Nb). Microhardness measurements were also conducted to obtain the carburized case depths, and the results agreed well with the predicted calculations.

  12. 剪毛机支架体渗碳工艺的优化%The Optimum of Carburize Industrial Art on Shearing Machine Frame Foundation

    Institute of Scientific and Technical Information of China (English)

    吐尔逊·斯地克; 熊辉林

    2011-01-01

    By the shearing machine frame foundation with its material (number 08 steel), using solid-state carburize method, the carburize industrial art, organization and property have been studied in order to provide reasonable theoretical foundation for increasing resistance to wear of carburize layers. From test the optimal version has been reached in heating temperature of 950℃, insulated time of 4 h, catalyst proportion of 30%.%本文以剪毛机支架体材料08钢为研究对像,采用固体渗碳法,对渗碳的工艺,组织和性能进行研究,为提高渗碳层的耐磨性提供可靠的理论依据.通过试验得出加热温度为950℃,保温时间为6 h,催渗剂比例为30%的最优方案.

  13. Application of Carburization Technique in Nodular Iron Production%增碳技术在球墨铸铁生产中的应用

    Institute of Scientific and Technical Information of China (English)

    蒋毓良

    2011-01-01

    简单介绍了增碳剂的类型及选用原则;对影响增碳剂增碳率和增碳作用的因素进行了分析,指出在球墨铸铁生产中,应用增碳及铁液预处理工艺,可减少铁液杂质元素和有害元素的含量,降低炉料遗传性影响,增加石墨球数,改善球化率,提高材料的力学性能.%The sorts of carburizer and their selection and usage principle were introduced briefly. The factors influencing the carburizing rate and carburizing effect were analyzed. It was pointed out that application of carhurizing procesa and preconditioning process in the nodular iron production makes it possible to reduce content of the impurity elements and harmful elements. decrease the heredity effect of the melting charges, increase nodule count, improve nodularity and improve material mechanical properties.

  14. 齿轮激光淬火和渗碳淬火的经济性比较%Economic Comparison of Laser-hardened Gear and Carburized Gear

    Institute of Scientific and Technical Information of China (English)

    张欣; 郭子峰

    2014-01-01

    激光淬火是齿轮表面硬化的一个新工艺,与渗碳淬火相比,具有变形小等特点,具有广阔的应用前景。针对齿轮激光淬火和渗碳淬火两种不同工艺,从材料、工艺流程、制造成本等方面进行了比较,结果表明:齿轮激光淬火比渗碳淬火更加经济。%Laser hardening is a new method for surface hardening of gear tooth. It characteristics of little deformation after hardening compared with carburized gears, which can be widely used in the industries. According to the two dif-ferent heat treatments of gears, laser hardening and carburizing, the base materials, manufacturing process and produc-tion cost of two different hardened-gears are compared. The research results show that laser-hardened gears are eco-nomical compared to carburized gears.

  15. The effect of pouring time on the dimensional stability of casts made from conventional and extended-pour irreversible hydrocolloids by 3D modelling

    Directory of Open Access Journals (Sweden)

    Hasan Ö. Gümüş

    2015-09-01

    Conclusion: All of the conventional and extended-pour impression materials tested in this study can be poured up to 24 hours with accuracy, if impressions are correctly stored. Extended-pour impression materials (ColorChange, Hydrogum 5, and Hydrocolor 5 can be poured up to 120 hours, if stored correctly.

  16. Carburization of W- and Re-rich Ni-based alloys in impure helium at 1000 {sup o}C

    Energy Technology Data Exchange (ETDEWEB)

    Adharapurapu, Raghavendra R., E-mail: araghav@gmail.co [Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Kumar, Deepak; Zhu Jun [Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Pollock, Tresa M. [Materials Department, University of California, Santa Barbara, CA 93106 (United States)

    2011-01-15

    Research highlights: This work investigates the surface and bulk stability of W- and Re-rich Ni-based alloys under carburizing/oxidizing conditions (1000 {sup o}C) in order to understand the fundamental mechanisms of material degradation due to impurities in helium environment of the very high temperature helium-cooled reactor (VHTR). Depending on the alloy composition, carbides of type M{sub 6}C, M{sub 7}C{sub 3} or M{sub 23}C{sub 6} were observed, with a maximum carbon pickup between 0.06 and 0.12 wt.%. Alloys with high W content exhibited M{sub 6}C type carbides, whereas high Cr and low W alloys formed Cr-rich M{sub 23}C{sub 6} carbides. High additions of Re stabilized the M{sub 23}C{sub 6} phase due to its high solubility in these chromium-rich carbides. A continuous film of contiguous carbides (M{sub 6}C and M{sub 23}C{sub 6}) was observed in the grain boundaries; this is likely to be detrimental to the ductility and creep properties. During the first 50 h exposure, carbides were observed on the alloy surface as well as in the bulk with carbides precipitating in the grain interior and on the grain boundary. The (transient) surface carbides oxidized after prolonged exposure (100-225 h) forming stable Cr{sub 2}O{sub 3} oxide on the alloy surface. The work is particularly relevant to the development of strategies towards improvement of Ni-based alloys for intermediate heat exchangers (IHX) for service at 1000 {sup o}C in impure-He environment of the Next Generation Nuclear Plant (NGNP). - Abstract: The surface and microstructure stability of experimental W- and Re-rich Ni-based alloys in an impure-helium environment containing only CO and CO{sub 2} as impurities (ppm level) have been investigated at 1000 {sup o}C. All the alloys carburized during 50 h of exposure, and, depending on the alloy composition, different carbides of the type M{sub 6}C, M{sub 7}C{sub 3} and M{sub 23}C{sub 6} formed on the alloy surface, in grain interiors and at grain boundaries

  17. A statistical treatment of bioassay pour fractions

    Science.gov (United States)

    Barengoltz, Jack; Hughes, David

    A bioassay is a method for estimating the number of bacterial spores on a spacecraft surface for the purpose of demonstrating compliance with planetary protection (PP) requirements (Ref. 1). The details of the process may be seen in the appropriate PP document (e.g., for NASA, Ref. 2). In general, the surface is mechanically sampled with a damp sterile swab or wipe. The completion of the process is colony formation in a growth medium in a plate (Petri dish); the colonies are counted. Consider a set of samples from randomly selected, known areas of one spacecraft surface, for simplicity. One may calculate the mean and standard deviation of the bioburden density, which is the ratio of counts to area sampled. The standard deviation represents an estimate of the variation from place to place of the true bioburden density commingled with the precision of the individual sample counts. The accuracy of individual sample results depends on the equipment used, the collection method, and the culturing method. One aspect that greatly influences the result is the pour fraction, which is the quantity of fluid added to the plates divided by the total fluid used in extracting spores from the sampling equipment. In an analysis of a single sample’s counts due to the pour fraction, one seeks to answer the question: What is the probability that if a certain number of spores are counted with a known pour fraction, that there are an additional number of spores in the part of the rinse not poured. This is given for specific values by the binomial distribution density, where detection (of culturable spores) is success and the probability of success is the pour fraction. A special summation over the binomial distribution, equivalent to adding for all possible values of the true total number of spores, is performed. This distribution when normalized will almost yield the desired quantity. It is the probability that the additional number of spores does not exceed a certain value. Of course

  18. Application of PT9800 software to optimization of carburizing process for heavy-duty locomotive gear%PT9800软件在重载机车齿轮渗碳工艺优化中的应用

    Institute of Scientific and Technical Information of China (English)

    文超; 董雯; 谭小明; 王晓华

    2012-01-01

    利用PT9800软件进行了两段式渗碳工艺强扩比的模拟计算,据此优化了重载机车齿轮渗碳工艺并节省了20%的工艺时间。相应的验证试验也获得了满意的渗层金相组织、硬度梯度和预期的渗碳层深度,证明了PT9800计算的准确性,从而为渗碳工艺强扩比的合理选择和优化提供了依据。%The carburizing-diffusion ratio of two-stage carburizing technology was simulated by using PT9800 software.According to this simulation calculation,the carburizing process for heavy-duty locomotive gear was optimized and the process time was saved 20%.The expected microstructure,hardness distribution and case depth of the carburized layer were obtained by the relevant experiments,it is approved the reasonability and accuracy of PT9800 software,and provides evidence for choice and optimization of the carburizing-diffusion ratio.

  19. Equilibration of plain carbon and alloy steels with endothermic carburizing atmospheres: Part II. Oxidation of plain carbon and Armco steels during carburizing at 1000 °C and 1038 °C

    Science.gov (United States)

    Hwang, Jong-Il; Jhee, Tae-Gu; Kim, Young-Kyu; Hwang, Tae-Young

    2010-10-01

    Carbon contents by the weight gain of AISI type 1010 steel foils equilibrated with CO-CO2 mixtures at 1000 °C were 0.03 wt.% to 0.07 wt.% higher than those by chemical analysis at carbon potentials of 0.2 wt.%C to 0.7 wt.%C. The lower the carbon potential, the bigger the difference became. This difference of 0.05 wt.% to 0.08 wt.% was also measured when the same materials were equilibrated with CO-CO2 mixtures at 1038 °C at carbon potentials below 0.4 wt.%C. Oxygen analyses of these equilibrated steel foils confirmed that those differences of 0.03 wt.% to 0.07 wt.% and 0.05 wt.% to 0.08 wt.% were mainly due to the selective oxidation of manganese. When Armco steels and type 1010 steels were equilibrated simultaneously with endothermic-base carburizing atmospheres at 1038 °C, oxidation was negligible and the carbon contents of the both steels were identical at carbon potentials of 0.2 wt.%C to 1.4 wt.%C.

  20. Three-Dimensional (3-D) Atom Probe Tomography of a Cu-Precipitation-Strengthened, Ultrahigh-Strength Carburized Steel

    Science.gov (United States)

    Tiemens, Benjamin L.; Sachdev, Anil K.; Mishra, Raja K.; Olson, Gregory B.

    2012-10-01

    In an effort to reduce material cost, experimental steel alloys were developed that incorporated Cu precipitation in lieu of costly Co alloying additions in secondary hardening carburizing gear steels. This work utilizes three-dimensional atom probe tomography to study one of these prototype alloys and quantify the nanoscale dispersions of body-centered cubic (bcc) Cu and M2C alloy carbides used to strengthen these steels. The temporal evolution of precipitate, size, morphology, and interprecipitate interactions were studied for various tempering times. Findings suggest that Cu precipitation does act as a catalyst for heterogeneous nucleation of M2C carbides at relatively high hardness levels; however, the resultant volume fraction of strengthening carbides was noticeably less than that predicted by thermodynamic equilibrium calculations, indicating a reduced potency compared with Co-assisted precipitation. Microstructural information such as precipitate size and volume fraction was measured at the peak hardness condition and successfully used to recalibrate alloy design models for subsequent alloy design iterations.

  1. EBSD analysis of tungsten-filament carburization during the hot-wire CVD of multi-walled carbon nanotubes.

    Science.gov (United States)

    Oliphant, Clive J; Arendse, Christopher J; Camagu, Sigqibo T; Swart, Hendrik

    2014-02-01

    Filament condition during hot-wire chemical vapor deposition conditions of multi-walled carbon nanotubes is a major concern for a stable deposition process. We report on the novel application of electron backscatter diffraction to characterize the carburization of tungsten filaments. During the synthesis, the W-filaments transform to W2C and WC. W-carbide growth followed a parabolic behavior corresponding to the diffusion of C as the rate-determining step. The grain size of W, W2C, and WC increases with longer exposure time and increasing filament temperature. The grain size of the recrystallizing W-core and W2C phase grows from the perimeter inwardly and this phenomenon is enhanced at filament temperatures in excess of 1,400°C. Cracks appear at filament temperatures >1,600°C, accompanied by a reduction in the filament operational lifetime. The increase of the W2C and recrystallized W-core grain size from the perimeter inwardly is ascribed to a thermal gradient within the filament, which in turn influences the hardness measurements and crack formation.

  2. 井式炉渗碳工艺过程控制SE-607系统的应用%Application of carburizing process control system SE-607 for pit-type furnace

    Institute of Scientific and Technical Information of China (English)

    景晖

    2011-01-01

    The application case in Hangzhou Advance Gearbox Group Co.,Ltd.,of SE-607 pit-type furnace carburizing control system that was developed and researched by STANGE Electronic GmbH was introduced for the construction of hardware and software,carburizing workmanship,working principle of carbon potential regulation,carburizing process simulation and computer monitoring system.%以德国斯坦格电气有限公司设计制造的SE-607井式炉渗碳工艺过程控制系统在杭州前进齿轮箱厂的项目应用为实例,对该过程控制系统的软硬件结构、渗碳工艺、碳势控制原理、渗碳扩散模拟模块及上位机监控系统的组成进行介绍。

  3. Pour une Écologie des Somatiques?

    Directory of Open Access Journals (Sweden)

    Isabelle

    2014-12-01

    Full Text Available Ce texte traite de la parenté conceptuelle et théorique entre Somatiques et Écologie scientifique. Après une définition de la notion scientifique d’écologie, il s’attache à définir trois notions clés de l’écologie: celle de potentiel, qui permet de décrire de façon innovante le modèle de relation entre sujet et environnement au sein des Somatiques, et celles de diversité et de réciprocité, à partir desquelles l’article se veut une invitation et un programme à penser l’intégration des Somatiques au paradigme écologique scientifique, et en appelle aux acteurs somatiques pour transformer leurs pratiques selon une éthique environnementale.

  4. A lunguistica pour ses quarante ans

    Directory of Open Access Journals (Sweden)

    Ludvik Horvat Le Doyen

    2000-12-01

    Full Text Available En tant que doyen de la Faculté des Lettres de l'Universite de Ljubljana, j'ai l'honneur d'introduire le volume qui celebre les quarante ans de publication de cette revue linguistique. La parution de la revue conçua à l' origine comme supplàment pour la linguistique non slave de la revue Slavistična revija (dont la renommée était déjà affirmée, eut lieu en 1958. Ses inspirateurs, ses fondateurs et ses premiers directeurs, auxquels nous gardons une profonde reconnaissance, furent l'italianiste Stanko Škerlj et le latiniste Milan Grošelj, professeurs de notre Faculté. Des sa quatrieme année ce modeste supplement devint revue autonome, telle que nous la connaissons aujourd'hui.

  5. 奥氏体不锈钢低温气体渗碳的组织性能%Structure and Properties of Anti-corrosion Carburized Layers in Austenitic Stainless Steels

    Institute of Scientific and Technical Information of China (English)

    李朋; 潘邻; 张良界; 杨闽红; 朱云峰; 马飞

    2013-01-01

    Low temperature carburizing process, such as salt bath carburizing and plasma carburizing can improve the surface strength of the austenite stainless steel, but reduce the corrosion resistant performance. A gas carburizing technology at low temperature was developed, which can both improve the surface strength and corrosion resistant performance. 304 and 316 austenitic stainless steel were carburized by low temperature carburizing process, and the hardness and performance was analized. The results show that the surface strength enhances, however, the corrosion resistance reduces with the temperature increase. The austenitic stainless steel shows good strength and corrosion resistance under the condition of 470 ℃.%低温盐浴渗碳、等离子渗碳等低温渗碳工艺在提高奥氏体不锈钢表面强度的同时,会降低其耐蚀性能.为克服上述缺陷,开发了一种高效兼顾表面强度与耐蚀性能的表面强化工艺的低温气体渗碳技术.采用该工艺对304、316奥氏体不锈钢进行渗碳处理,并对得到的奥氏体不锈钢低温渗碳组织性能进行分析.结果表明,随着温度升高,试样表面强度提高,而腐蚀性能下降.470℃是兼顾强化与耐蚀性能的低温气体渗碳工艺参数.

  6. Carburizing Inspection of Cracking Furnace Tube Using Magnetic Hysteresis Non-Destructive Evaluation Technique%磁滞无损评估技术在裂解炉管渗碳检测中的应用

    Institute of Scientific and Technical Information of China (English)

    刘德宇; 王宁辉; 张国庆; 李国瑞

    2015-01-01

    Large tube type fuel heating furnaces are important and essential equipments, with a wide range of applications in the petroleum and chemical industry, in which the failure modes of furnace tubes are mostly caused by carburizing. To estimate the effect of magnetic hysteresis non-destructive evaluation technique on carburizing inspection, both new and the three-years-service cracking furnace tubes were performed carburizing test. Different carburized depth of tubes were got and their coercivity was tested. The results showed that there is a good relationship between the coercivity and carburized case depth, which would be a great potential applications in the carburizing inspection of tube.%大型管式燃料加热炉是石油化工企业里广泛应用且必不可少的重要设备,其中炉管的失效大多由渗碳引起。为了评价磁滞无损评估技术在渗碳层厚度检测中应用的有效性,对未服役和服役3年的裂解炉炉管进行渗碳实验,得到不同渗碳层厚度的炉管,并采集磁滞参数矫顽力,结果表明,矫顽力与渗碳层厚度具有很好的对应关系,在炉管渗碳检测中具有很大的应用前景。

  7. 汽车零部件丙烷气体渗碳时气氛净化工艺及效果%Atmosphere Purification Technology and Effect of Gas Carburizing for Automobile Spare Parts

    Institute of Scientific and Technical Information of China (English)

    张道于; 张铁军

    2013-01-01

    采用分子筛作为净化剂,可使渗碳气氛中的水分稳定地控制在较低水平.采用净化后的丙烷气体渗碳,产品质量得到明显提高,生产成本显著下降.%Using molecular sieve as the purifying agent, water in the carburizing atmosphere can be stably controlled at a lower level. Using purified propane gas carburizing, the product quality can be significantly improved, production costs decrease significantly.

  8. Novel Additive for Particulate Trap Regeneration Un nouvel additif pour la régénération des filtres à particules diesels

    Directory of Open Access Journals (Sweden)

    Bergonzini L.

    2006-12-01

    Full Text Available One of the most promising ways to insure the periodic regeneration of a particulate trap, consists to additise the fuel with organometallic compounds. The present paper deals with a novel alkali product, able to promote natural regenerations, for exhaust temperatures as low as 200°C, and treatment rates as low as 5 ppm. Tests have been carried out on a soot reactor and on an engine bench with various trap locations in the exhaust showing that the regeneration occurrence depends on temperature, soot mass loaded inside the porous structure, engine conditions. A complete trap cleaning still needs gas temperatures up to 400°C, which can be encountered for high load conditions of the engine. Une des voies les plus prometteuses pour la régénération des filtres à particules diesels consiste à additiver le carburant avec des composés organo-métalliques. Cet article s'intéresse à un nouveau dérivé alcalin, capable de favoriser des régénérations spontanées pour des températures à l'échappement descendant jusqu'à 200°C, et pour des teneurs en métal aussi faibles que 5 ppm. Des essais ont été réalisés sur un réacteur à suies et sur un moteur au banc, avec différentes localisations des filtres à l'échappement, montrant que le déclenchement de la régénération dépend de la température, de la masse de suie accumulée dans les structures poreuses et des conditions opératoires du moteur. Le nettoyage complet du filtre nécessite encore des températures de gaz supérieures à 400°C, qui peuvent être atteintes lors des fonctionnements à fortes charges du moteur.

  9. The concrete technology of post pouring zone of raft foundation of Hongyun Building B tower

    Science.gov (United States)

    Yin, Suhua; Yu, Liu; Wu, Yanli; Zhao, Ying

    2017-08-01

    The foundation of Hongyun building B tower is made of raft board foundation which is 3300mm in the thickness concreted pouring amount of large and the late poured band in the pouring settlement formed. The temperature of the pouring settlement was controlled in order to prevent the crack of the construction of the late poured band. The steel of post pouring band was designed and monitorred. The quality of post pouring band quality is guaranteed in the raft concrete foundation of Hongyun Building B tower.

  10. The effect of molybdenum on niobium, titanium carbonitride precipitate evolution and grain refinement in high-temperature vacuum carburizing alloys

    Science.gov (United States)

    Enloe, Charles M.

    Existing commercial carburizing alloys can be processed at higher temperatures and shorter processing times utilizing vacuum carburizing due to the suppression of intergranular oxidation. To provide resistance to undesired grain coarsening at these elevated temperatures and associated reduction in fatigue performance, microalloyed steel variants have been developed which employ fine Ti- and Nb-carbonitrides to suppress grain growth. Grain coarsening resistance is believed to be limited by the coarsening resistance of the precipitates themselves at high temperature, so further alloy/processing developments to enhance microalloy precipitate coarsening resistance based on a greater mechanistic understanding of solute interaction with microalloy precipitates would be beneficial. Molybdenum is known to affect microalloy precipitate evolution during processing in ferrite and austenite, but a unified explanation of the role of Mo in precipitate evolution is still lacking. Accordingly, the effect of molybdenum on microalloy precipitate size and composition evolutions and the associated onset of abnormal grain growth in austenite was investigated in Mo-bearing and Mo-free, Nb,Ti-microalloyed SAE 4120 steels. Molybdenum additions of 0.30 wt pct to alloys containing Nb additions of 0.05 and 0.10 wt pct Nb delayed the onset of abnormal grain growth in hot-rolled alloys reheated and soaked at 1050 °C and 1100 °C. The coarsening rate of microalloy precipitates was also reduced in Mo-bearing alloys relative to Mo-free alloys during isothermal soaking at 1050 °C, 1100 °C, and 1150 °C. The observed microalloy precipitate coarsening rates exceeded those predicted by the Lifshitz-Slyozov-Wagner relation for volume-diffusion-controlled coarsening, which is attributed to an initial bimodal precipitate size distribution prior to reheating to elevated temperature. Heat-treatments of hot-rolled alloys (tempering and solutionizing) prior to reheating to elevated temperature in

  11. Effect of mass transfer limitations on catalyst performance during reduction and carburization of iron based Fischer-Tropsch synthesis catalysts

    Institute of Scientific and Technical Information of China (English)

    Akbar; Zamaniyan; Yadollah; Mortazavi; Abbas; Ali; Khodadadi; Ali; Nakhaei; Pour

    2013-01-01

    Existence of intraparticle mass transfer limitations under typical Fischer-Tropsch synthesis has been reported previously,but there is no suitable study on the existence of intraparticle diffusion limitations under pretreatment steps (reduction and activation) and their effect on catalytic performance for iron based catalysts.In this study,Fe-Cu-La-SiO2 catalysts were prepared by co-precipitation method.To investigate the intraparticle mass transfer limitation under reduction,activation and reaction steps,and its effect on catalytic performance,catalyst pellets with different sizes of 6,3,1 and 0.5 mm have been prepared.All catalysts were calcined,pretreated and tested under similar conditions.The catalysts were activated in hydrogen (5%H2in N2) at 450℃ for 3 h and exposed to syngas (H2/CO=1) at 270℃ and atmospheric pressure for 40 h.Afterwards,FTS reaction tests were performed for approximately 120 h to reach steady state conditions at 290℃,17 bar and a feed flow (syngas H2/CO=1) rate of 3 L/h (STP).Using small pellets resulted in higher CO conversion,FT reaction rate and C5+ productivity as compared with larger pellets.The small pellets reached steady state conditions just 20 h after starting the reaction.Whereas for larger pellets,CO conversion,FT reaction rate and C5+ productivity increased gradually,and reached steady state and maximum values after 120 h of operation.The results illustrate that mass transfer limitations exist not only for FTS reaction but also for the reduction and carburization steps which lead to various phase formation through catalyst activation.Also the results indicate that some effects of mass transfer limitations in activation step,can be compensated in the reaction step.The results can be used for better design of iron based catalyst to improve the process economy.

  12. Images du Mage, images pour le Mage

    Directory of Open Access Journals (Sweden)

    Daniel GREGORIO

    2007-01-01

    Full Text Available Les œuvres d’Alphonse X proposent diverses représentations du mage, qui en font, tour à tour, l’ennemi ou l’allié de la religion chrétienne. Il est vrai que parfois, comme le montre l’histoire de Simon le magicien, la pratique de la magie implique un commerce direct et néfaste avec les forces infernales. Néanmoins, les personnages de Merlin et des Rois Mages, tels qu’ils sont présentés par Alphonse X, démontrent que magie et religion peuvent cohabiter, à condition toutefois que le mage croit en la virginité de Marie et en l’Incarnation et que sa pratique magique soit bénéfique pour la communauté. Ce bénéfice requiert parfois la reconstruction de l’univers quotidien ; pour ce faire, le magicien doit savoir quand et comment utiliser des objets et des pentacles, qui lui permettront de soumettre les forces surnaturelles. Il doit donc posséder une connaissance approfondie du monde naturel et des esprits qui, conjuguée à sa foi religieuse, l’empêchera de tomber dans la démonolâtrie.Las obras alfonsíes proponen diversas aproximaciones al personaje del mago, generalmente considerado como un ser antagónico del hombre religioso. Es cierto que en algunas ocasiones, como ocurre con Simón el mago, la práctica de las artes mágicas significa un trato directo y nefasto con las fuerzas infernales. Sin embargo, personajes como Merlín o los Reyes Magos, tal y como los describe Alfonso X, subrayan una posible cohabitación entre magia y religión sin que la práctica de la una signifique la exclusión de la otra. Sólo hay que cumplir con dos condiciones : creer en la virginidad de María y que Dios se hizo hombre, y proporcionar a la comunidad un beneficio claro. Este beneficio requiere en ocasiones remodelar lo cotidiano, utilizando objetos y pentáculos, en circunstancias extremadamente determinadas, lo que implica un conocimiento exhaustivo tanto del mundo natural como del simbólico y de los espíritus. Es este

  13. Decodeurs rapides pour codes topologiques quantiques

    Science.gov (United States)

    Duclos-Cianci, Guillaume

    L'encodage topologique de l'information quantique a attire beaucoup d'attention, car c'est un modele qui semble propice a resister aux erreurs locales. Tout d'abord, le modele du calcul topologique est base sur la statistique anyonique non-Abelienne universelle et sur son controle. Des anyons indesirables peuvent apparaitre soudainement, en raison de fluctuations thermiques ou de processus virtuels. La presence de ces anyons peut corrompre l'information encodee, il est necessaire de les eliminer: la correction consiste a fusionner les defauts tout en preservant la topologie du systeme. Ensuite, dans le cas des codes topologiques, on doit aussi proteger l'information encodee dans la topologie. En effet, dans ces systemes, on n'a acces qu'a une fraction de l'information decrivant l'erreur. Elle est recueillie par des mesures et peut etre interpretee en termes de particules. Ces defauts peuplent le code et doivent etre annihiles adequatement dans le but de preserver l'information encodee. Dans ce memoire, nous proposons un algorithme efficace, appele decodeur, pouvant etre utilise dans les deux contextes decrits ci-haut. Pour y parvenir, cet algorithme s'inspire de methodes de renormalisation et de propagation de croyance. Il est exponentiellement plus rapide que les methodes deja existantes, etant de complexite O (ℓ2 log ℓ) en serie et, si on parallelise, O (log ℓ) en temps, contre O (ℓ6) pour les autres decodeurs. Le temps etant le facteur limitant dans le probleme du decodage, cette caracteristique est primordiale. De plus, il tolere une plus grande amplitude de bruit que les methodes existantes; il possede un seuil de ˜ 16.5% sur le canal depolarisant surpassant le seuil deja etabli de ˜ 15.5%. Finalement, il est plus versatile. En effet, en etant limite au code de Kitaev, on ne savait pas decoder les codes topologiques de maniere generale (e.g. codes de couleur). Or, le decodeur propose dans ce memoire peut traiter la grande classe des codes

  14. Transfert radiatif numerique pour un code SPH

    Science.gov (United States)

    Viau, Joseph Edmour Serge

    2001-03-01

    Le besoin de reproduire la formation d'etoiles par simulations numeriques s'est fait de plus en plus present au cours des 30 dernieres annees. Depuis Larson (1968), les codes de simulations n'ont eu de cesse de s'ameliorer. D'ailleurs, en 1977, Lucy introduit une autre methode de calcul venant concurrencer la methode par grille. Cette nouvelle facon de calculer utilise en effet des points a defaut d'utiliser des grilles, ce qui est une bien meilleure adaptation aux calculs d'un effondrement gravitationnel. Il restait cependant le probleme d'ajouter le transfert radiatif a un tel code. Malgre la proposition de Brookshaw (1984), qui nous montre une formule permettant d'ajouter le transfert radiatif sous la forme SPH tout en evitant la double sommation genante qu'elle implique, aucun code SPH a ce jour ne contient un transfert radiatif satisfaisant. Cette these presente pour la premiere fois un code SPH muni d'un transfert radiatif adequat. Toutes les difficultes ont pu etre surmontees afin d'obtenir finalement le transfert radiatif "vrai" qui survient dans l'effondrement d'un nuage moleculaire. Pour verifier l'integrite de nos resultats, une comparaison avec le nonisothermal test case de Boss & Myhill (1993) nous revele un resultat fort satisfaisant. En plus de suivre fidelement la courbe de l'evolution de la temperature centrale en fonction de la densite centrale, notre code est exempt de toutes les anomalies rencontrees par les codes par grille. Le test du cas de la conduction thermique nous a lui aussi servit a verifier la fiabilite de notre code. La aussi les resultats sont fort satisfaisants. Faisant suite a ces resultats, le code fut utilise dans deux situations reelles de recherche, ce qui nous a permis de demontrer les nombreuses possibilites que nous donne notre nouveau code. Dans un premier temps, nous avons tudie le comportement de la temperature dans un disque d'accretion durant son evolution. Ensuite nous avons refait en partie une experience de Bonnell

  15. legumineuses arborescentes pour la gestion durable des terroirs ...

    African Journals Online (AJOL)

    AISA

    Species were been selected in plantation following their origin. Acacia mangium, Acacia .... Les études sylvicoles ont eu pour objectif d'identifier des ...... I. Biomass and productivity. ... Firewood crops. Shrub and Tree Species For Energy.

  16. ALGORITHME POUR LE CALCUL DES COURBURES GENERALISEES

    Directory of Open Access Journals (Sweden)

    K MEZAGHCHA

    2004-06-01

    Full Text Available On sait qu’une courbe algébrique standard  d'équation f(x, y =0 admet un nombre fini de branches (nombre inférieur à l'ordre de f , dont les paramètrages peuvent être obtenus en particulier à partir de la décomposition de Goze itérée. On aimerait calculer  leur courbure généralisée sans les déterminer explicitement, la notion de courbure généralisée ayant fait l’objet d’un travail, publié dans les comptes rendus de l’Université de Cagliari (Italie [12]. Dans cet article, on se propose d'établir à cet effet un algorithme qui donnera à partir seulement des coefficients de f, la liste exhaustive des courbures généralisées de toutes les branches réelles. L’article se termine par la donnée d’un exemple pour montrer l’efficacité de l’algorithme proposé.

  17. Un ticket pour la liberté

    Directory of Open Access Journals (Sweden)

    Nabil Mouline

    2014-07-01

    Full Text Available Pour diverses raisons, l’industrie cinématographique égyptienne a connu des changements profonds au début des années 2000. L’une des conséquences les plus palpables a été la production de manière volontaire ou involontaire de films contestataires dans la mesure où ils essaient de remettre en cause le discours dominant et de lever le tabou sur plusieurs questions sociopolitiques. Cela a fait du produit filmique non seulement un document d’archive qui reflète l’état de la société mais également un outil efficace de soft influence et de mobilisation qui a participé à la création d’une communauté imaginée dont une partie est passée à l’action le 25 janvier 2011. C’est l’ambition de cet article que de lever le voile sur ce double rôle du cinéma entre 2001 et 2010 en s’appuyant sur un large échantillon de films à grand succès.

  18. 潜水渣浆泵的设计及应用研究%Study on Testing Method of Carburizing Gears for Heavy Duty Trucks

    Institute of Scientific and Technical Information of China (English)

    张海平; 赵玉刚; 孟祥炎

    2012-01-01

    Driving gears are key components to ensure the running safety of automobiles, and the tests of the mierostrueture properties of gears are the important guarantee of its quality eontrol. Aiming at earburized gears for heavy duty trucks, the paper in detail studied the testing methods and demand of the chemical composition, microstructure, carbide rating, retained austenite and martensite rating, carburizing quenching effectively hardening depth, surface and core hardness. The results can provide a reference basis the design, manufacturing and test of carburizing gears for heavy duty trucks.%渣浆泵是固液混合物管道输送的核心部件,由于设计和材质方面的缺陷,我国目前应用的大部分渣浆泵不同程度存在运行效率较低和使用寿命短的问题。本文设计的潜水式渣浆泵通过采用先进的水力模型、合理选用耐磨材料和加工工艺,其抽渣运行效率大幅度提高、使用寿命也得到延长。

  19. Study On the Tribological Behavior of the Arc-added Glow Discharge Plasma Non-hydrogen Carburization On Titanium Alloy Surfaces

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei; ZHAHGYue-fei; Liu Yu; TANG Bin; PAN Jun-de

    2004-01-01

    This paper introduces a new titanium alloys surface strengthening treatment by using the arc-added glow discharge plasmas non-hydrogen carburization technique. High purity and high strength graphite is selected as cooling cathode arc source for supplying carbon atoms and particle, which migrate to the titanium alloy(Ti6Al4V) surface and form modified layer. Thus, the hydrogen embrittlement is avoided while the tribological behavior of the titanium alloy surface is improved in the respects of anti-friction and anti-wear ability. The tribological behavior of the modified layer under dry sliding against SAE52100 steel was evaluated on a ball-on-disc test rig. The results showed that the modified layer obtained a thickness of 30μm at 980℃, 30minutes. The microhardness of the Ti6A14V alloy surface attained 936 HV, which was much larger than that of the Ti6A14V alloy. The Ti6A14V alloy was characterized by adhesion wear and scuffing under dry sliding against the steel, while the surface modified layer experienced much abated adhesion wear and scuffing under the same testing condition. This could be attributed to the carbon element with different modalities exists in the modified layer.The modified layer showed good friction-reducing and fair anti-wear ability in dry sliding against the steel. Using the SEM,XRD and XPS, the phase structure and morphology of the carburization modified layer was analyzed.

  20. Effect of tensile stress on the formation of S-phase during low-temperature plasma carburizing of 316L foil

    Energy Technology Data Exchange (ETDEWEB)

    Li Wei [School of Metallurgy and Materials, University of Birmingham, B15 2TT (United Kingdom); Li Xiaoying, E-mail: X.LI.1@bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, B15 2TT (United Kingdom); Dong Hanshan [School of Metallurgy and Materials, University of Birmingham, B15 2TT (United Kingdom)

    2011-08-15

    Low-temperature plasma carburizing of austenitic stainless steel can produce a carbon-supersaturated austenite layer, the 'S-phase', on the surface, which has high hardness, excellent wear and fatigue properties, and good corrosion resistance. Although the S-phase was discovered some years ago, the basic understanding of S-phase formation remains incomplete. In this paper, the effect of tensile stresses (0-80 MPa) on the formation and stability of S-phase during carburizing of 316L stainless steel foils at 400, 425 and 450 deg. C for 10 h has been investigated for the first time. The microstructures were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy and the mechanical properties were evaluated by microhardness and tensile tests. The results showed that the in situ applied tensile stress effectively thickened S-phase layers. The calculated activation energy for carbon diffusion in 316L was reduced from 142.76 to 133.91 kJ mol{sup -1} when a tensile stress of 40 MPa was applied. However, chromium carbides were formed in the outmost surface when the tensile stress exceeded 40 MPa. The results are discussed and explained through appropriate thermodynamic calculations.

  1. Enhanced Droplet Erosion Resistance of Laser Treated Nano Structured TWAS and Plasma Ion Nitro-Carburized Coatings for High Rating Steam Turbine Components

    Science.gov (United States)

    Pant, B. K.; Arya, Vivek; Mann, B. S.

    2010-09-01

    This article deals with surface modification of twin wire arc sprayed (TWAS) and plasma ion nitro-carburized X10CrNiMoV1222 steel using high power diode laser (HPDL) to overcome water droplet erosion occurring in low pressure steam turbine (LPST) bypass valves and LPST moving blades used in high rating conventional, critical, and super critical thermal power plants. The materials commonly used for high rating steam turbines blading are X10CrNiMoV1222 steel and Ti6Al4V titanium alloy. The HPDL surface treatment on TWAS coated X10CrNiMoV1222 steel as well as on plasma ion nitro-carburized steel has improved water droplet resistance manifolds. This may be due to combination of increased hardness and toughness as well as the formation of fine grained structure due to rapid heating and cooling rates associated with the laser surface treatment. The water droplet erosion test results along with their damage mechanism are reported in this article.

  2. Selection and Application of DT-CA-09 Type Carburant and the Experimental Results Analysis%DT-CA-09型增碳剂的选用及实验分析

    Institute of Scientific and Technical Information of China (English)

    徐桂洪; 张行河

    2011-01-01

    使用中频电炉熔炼合成铸铁,必须采用增碳技术,以保证铁液中碳含量在工艺要求的范围内.在中频电炉熔炼新工艺中,根据增碳剂分类及增碳原理,结合电炉熔炼对增碳剂的要求,选用了国产DT-CA-09型增碳剂.实验证明,所选用增碳剂可满足目前中频电炉熔炼工艺需求.%Melting synthetic cast iron with the medium frequency furnace it is necessary to adopt carburet ion technology to ensure that carbon content of liquid iron is meet the limits of particular foundry technology. According to the classification of carburant and principle of carburetion, combined with the requirements of carburant in electric furnace melting, the domestic DT-CA-09 type carburant was chosen in the new technology of the medium frequency electric furnace melting, and experiments proved that the selected carburant can meet the demands of current electric furnace melting technology.

  3. Deux comparatismes pour une anthropologie historique

    Directory of Open Access Journals (Sweden)

    Pierre-Olivier Dittmar

    2010-06-01

    Full Text Available Malgré des appels répétés depuis plus d’un siècle de la part des historiens, le comparatisme, qui est un élément majeur de l’anthropologie, demeure très peu pratiqué. Ce rejet est ici analysé comme un refus d’une quête des invariants de l’homme qui aboutirait à des résultats an-historiques. Un autre comparatisme est cependant possible, qui instrumentalise la confrontation des univers pour mieux relever les différences. C’est les conditions et les avantages d’une telle pratique qui sont ici exposés, à partir de l’exemple des tabous alimentaires.Despite the repeated calls by some historians for more than a century, many seldom practice a major element of anthropology: comparativism. This paper will analyze this rejection as a refusal to investigate the constants of the human experience that lead to a-historical conclusions. However, another kind of comparativism is possible, one that examines the contrast between cultures in order to better understand their differences. Using the case of dietary taboos, this paper will look at the conditions and advantages of such a practice.Nonostante i molteplici appelli da più di un secolo da parte degli storici, il comparatismo, che costituisce un elemento fondamentale dell’antropologia, è ancora oggi troppo poco spesso praticato. Si proporrà di interpretare questo rifiuto come un rifiuto della ricerca di invarianti umane che condurrebbe a risultati a-storici. Un’altra forma di comparatismo è nondimeno possibile, una forma precisamente che ricorre al confronto di universi diversi per meglio comprenderne le difference reciproche. L’articolo espone le condizioni e i vantaggi di questa metodologia di ricerca, a partire dall’esempio degli interdetti alimentari.

  4. 金相法测定钢渗碳层的有效硬化层深度%Depth Measurement of Carburized and Available Layer of Steel with Metallographic Method

    Institute of Scientific and Technical Information of China (English)

    伞晶超; 顾园

    2012-01-01

    Through experiment of carburize a set of 20CrMnMo steel samples, comparison between carburized layer of annealing with metallographic method and hardened layer depth with micro hardness basing on the national standard. According to measure result, carburized layer depth is the same to availability hardened layer depth which is set out quenching with metallographic method on annealing equilibrium, then it can be concluded that annealing equilibrium equivalent to the quenching carburized availability hardened layer depth, use metallographic microscope in existence to determine the carburized availability hardened layer.%通过对渗碳钢20CrMnMo试样渗碳后,用金相法检测退火状态的渗碳层与根据国家新标准用显微硬度计测定渗碳有效硬化层深度进行对比.根据测定的结果,用金相法以退火后的平衡组织,在显微镜下测定共析以上的渗层深与用显微硬度计测定的淬火状态的渗碳有效硬化层深基本上是一致的,从而推断可用金相法以退火状态的平衡组织在显微镜下测定共析以上的组织深度等效为渗碳后淬火状态的有效硬化层深度,从而以利用炉前现有设备金相显微镜来进行渗碳有效硬化层的测定.

  5. Guide pour la conception des dispositifs de franchissement des barrages pour les poissons migrateurs

    Directory of Open Access Journals (Sweden)

    LARINIER M.

    1983-10-01

    Full Text Available L'auteur rappelle dans cette note les principes de base devant guider le projeteur lors de la conception des ouvrages de franchissement de barrages ou d'obstacles pour les poissons migrateurs. L'accent est mis sur l'importance de la situation et de l'attractivité de ces ouvrages. Les principes de fonctionnement et les critères de dimensionnement des différents types de passes (passes à bassins successifs, passes à ralentisseurs, écluses et ascenseurs sont évoqués. Dans la dernière partie sont recensés les éléments à prendre en compte lors de l'établissement d'un projet de passe.

  6. Quelle cible pour le service à rendre ? Proposition pour un changement de paradigme

    OpenAIRE

    Bercot, Régine

    2014-01-01

    National audience; Les précédentes contributions ont montré que la qualité du service est liée aux modalités de sa construction, ce qui conduit pour l’améliorer à prendre en compte le travail de ceux qui le rendent concrètement et qui peuvent l’ajuster aux diverses situations rencontrées. Nous partirons aussi du constat selon lequel la définition d’un service rendu fait rarement l’objet d’un débat organisé. La thèse que nous développerons ici vient en appui de ces précédentes remarques. Nous ...

  7. Ablation laser pour la microélectronique plastique

    Science.gov (United States)

    Alloncle, A.-P.; Thomas, B.; Grojo, D.; Delaporte, Ph.; Sentis, M.; Sanaur, S.; Barret, M.; Collot, Ph.

    2006-12-01

    La microélectronique plastique connaît un développement sans précédent dans le domaine de la recherche. Cette étude s'intéresse à l'utilisation des lasers impulsionnels pour la réalisation de composants organiques sur supports souples. Les deux aspects plus particulièrement étudiés sont d'une part la gravure de polymère pour réaliser un canal entre la source et le drain, et d'autre part le développement d'un procédéde dépôt appelé LIFT pour Laser Induced Forward Transfer. Ce dernier pourrait notamment permettre dedéposer des composés organiques non solubles.

  8. Proposals for Solutions to Problems Related to the Use of F-34 (SFP) and High Sulphur Diesel on Ground Equipment Using Advanced Reduction Emission Technologies (Propositions de solutions aux problemes lies a l’utilisation de F-34 (SFP) et de diesel a haute teneur en soufre pour le materiel terrestre disposant de technologies avancees de reduction des emissions)

    Science.gov (United States)

    2008-09-01

    avancées de réduction des émissions (RTO-TM-AVT-ET-073) Synthèse Lors de sa réunion 2005, le Groupe de travail AC/112 de l’OTAN sur les carburants et les...émissions nécessitent l’utilisation de carburants à faible teneur en soufre (LSF). Le F-34 utilisé en vertu de la Politique du carburant unique de l’OTAN...Single Fuel Policy, ou SFP) est un carburant à haute teneur en soufre, en comparaison des carburants diesels européens et américains conformes aux

  9. Dispersants in an organic medium: synthesis and physicochemical study of dispersants for fuels and lubricants; Dispersants en milieu organique: synthese et etude physicochimique de dispersants pour carburants et lubrifiants

    Energy Technology Data Exchange (ETDEWEB)

    Dubois-Clochard, M.C.

    1998-11-19

    Carbonaceous deposits coming from the fuel and the lubricant are known to form over time at critical locations in an engine. In general, the deposits have an adverse effect on four functional areas which are the fuel metering system, the intake system, the lubrication system and the combustion chambers. These deposits can degrade vehicle performance and drive-ability, reduce fuel economy, increase fuel consumption and pollutant emissions and may lead to the destruction of the engine. In order to remedy these problems, detergent-dispersant additives are used in fuels and lubricants to avoid or decrease deposit adhesion on metallic surfaces and prevent from deposit aggregation. These products are mainly polymer surfactants and in this work, poly-iso-butenyl-succinimide of different structures have been studied. Firstly, 'comb like' polymers have been synthesized. Then they have been compared to classical di-bloc additives in terms of performance and action mechanism. These additives are adsorbed from their hydrophilic polyamine part on the acidic functions of the carbon black surface chosen as an engine deposit model and on the aluminium oxide function of an aluminium powder chosen as an engine wall model. The adsorption increases with temperature on the two solids. Their affinity with the solid surface increases with the length of the hydrophilic part. In the same way, changing the di-bloc structure for a comb like one lead to a better adsorption. At low concentration, it has been shown that the adsorption phenomenon was irreversible, due to the polymer structure of the polar part. Depending on the space required by the hydrophilic part on the solid surface, a more of less dense monolayer is formed. At higher concentrations, an important increase of the adsorbed amount appears. This phenomenon is totally reversible showing that the interactions additive / additive are weak. The dispersing efficiency of a comb like structure is better than a di-bloc one as the hydrophilic parts are forced to huddle together, decreasing the solid surface required and enhancing the stretching of hydrophobic parts. (author) 136 refs.

  10. Développement d'un réacteur intensifié en Carbure de Silicium pour la transposition en continu de réactions d'hydrosilylation

    OpenAIRE

    Fustier, Céline

    2012-01-01

    De nos jours, les limites du réacteur batch, outil conventionnel de l'industrie de la chimie fine, en termes de transfert thermique et de transfert de matière, conduisent à envisager le passage en continu de réactions dont les problématiques d'exothermie et de rapidité rendent leur industrialisation difficile. Les réacteurs-échangeurs compacts sont un exemple de technologies intensifiées continues alliant les performances d'un échangeur de chaleur couplées à un bon mélange ainsi qu'à un compo...

  11. Elaboration of massive silicon carbide monocrystals for power electronics applications. Reduction of the density of defects; Elaboration de monocristaux de carbure de silicium massifs pour l'electronique de puissance - reduction de la densite de defauts

    Energy Technology Data Exchange (ETDEWEB)

    Moulin, C. [CEA Grenoble, LETI, 38 - Grenoble (France)

    2001-07-01

    Thanks to its exceptional physical properties, SiC is a semiconductor material of prime importance for average and high power, high frequency and high temperature electronic applications. However, the SiC technology requires large diameter substrates (50 mm) with a density of micro-defects (micro-pipes or micro-tubes) lower than 10/cm{sup 2}. The present study deals with the reduction of the defects density in massive SiC crystals elaborated using a modified version of Lely's method. The method consists in the sublimation of a SiC powder and to the condensation of vapor species onto a SiC monocrystal germ. A thermal gradient is established between the powder and the germ which favors the transport of species from the powder to the germ. A study of the crystals characteristics and of the growth properties has permitted to identify the sensible parameters and to significantly improve the quality of the obtained crystals. Short note. (J.S.)

  12. Carburizing plasma in a low temperature austenitic stainless steel AISI 304; Cementacao a plasma em baixa temperatura de um aco inoxidavel austenitico AISI 304

    Energy Technology Data Exchange (ETDEWEB)

    Mota, W.T.; Ramos, F.D.; Rocha, R.C.; Barcelos, M.V.; Barcelos, M.A., E-mail: welber.tmota@gmail.com [Instituto Federal do Espirito Santo (IFES), ES (Brazil)

    2014-07-01

    The industrial use of thermochemical treatment assisted by the cold plasma has been widely employed in recent years, mainly oriented to the excellent results obtained in the surface modification of engineering materials, when compared to more traditional methods. In this work, we studied the plasma carburizing low temperature steel AISI 304 mechanical parts used in construction. The thermochemical treatment was performed at a fixed gas atmosphere 7% CH{sub 4} (g) and 93 % H{sub 2} (g), 350 ° C and times of 1, 3 and 5 hours. Samples being tested for Vickers hardness, abrasive microwear, microstructure evaluation by optical microscopy and SEM and X-ray diffraction. The results show significant improvement in surface hardness, wear resistance and good formation of expanded austenite layer and no identifiers peaks of carbides. The results achieved are due to diffusion/adsorption of carbon present in the gaseous atmosphere to the evaluated samples. (author)

  13. 基于ANSYS的渗碳齿轮动力学分析%Dynamics Analysis of Carburized Gear Based on ANSYS

    Institute of Scientific and Technical Information of China (English)

    高伟

    2014-01-01

    Setting carburized gear as the research object, considering the traditional computing the stress distribution, and based on ANSYS software platform, this paper does the finite element modeling and dynamic analysis, the result provides a theoretical basis to improve reliability of gear, which is of great significance to ensure the safety of production.%本文以渗碳齿轮为研究对象,针对传统计算无应力分布等情况,以Ansys软件为平台,对其进行了有限元建模,动力学分析,其结果对齿轮提高可靠性提供了理论基础,对保证安全生产有十分重要的意义。

  14. Effects of Vacuum-Carburizing Conditions on Surface-Hardened Layer Properties of Transformation-Induced Plasticity-Aided Martensitic Steel

    Directory of Open Access Journals (Sweden)

    Koh-ichi Sugimoto

    2017-08-01

    Full Text Available The effects of carbon potential in vacuum-carburization on the surface-hardened layer properties of the 0.2%C-1.5%Si-1.5%Mn-1.0%Cr-0.05%Nb transformation-induced plasticity-aided martensitic steel were investigated for the fabrication of precision gears. The volume fraction of retained austenite and hardness in the surface hardened layer of the steel increased with increasing carbon potential. Subsequent fine-particle peening enhanced the hardness and the compressive residual stress via severe plastic deformation and strain-induced martensite transformation, especially under a high carbon potential. The severe plastic deformation mainly contributed to increased hardness and compressive residual stress and the contribution of the strain-induced martensitic transformation was relatively small.

  15. Algorithmes et architectures pour ordinateurs quantiques supraconducteurs

    Science.gov (United States)

    Blais, A.

    2003-09-01

    'utilisation de qubits basés sur les jonctions Josephson. On présente entre autres une approche originale pour l'interaction entre qubits. Cette approche est très générale puisqu'elle peut être appliquée à différents designs de qubits. Finalement, on s'intéresse à la lecture des qubits supraconducteurs de flux. Le détecteur suggéré ici a l'avantage de pouvoir être découplé du qubit lorsqu'il n'y a pas de mesure en cours.

  16. Hydrogen Effect on Coke Removal and Catalytic Performance in Pre-Carburization and Methane Dehydro-Aromatization Reaction on Mo/HZSM-5

    Institute of Scientific and Technical Information of China (English)

    Hongtao Ma; Ryoichi Kojima; Satoshi Kikuchi; Masaru Ichikawa

    2005-01-01

    In this study,the effects of pre-carburization of catalyst,hydrogen addition to methane feed and the space velocity of methane on the catalytic performance in methane to benzene (MTB) reaction were discussed in detail over Mo/HZSM-5 catalyst at 1023 K and 0.3 MPa. Compared with the non-precarburized catalyst,the Mo catalyst pre-carburized under the flow of CH4+4H2 at 973 K was found to have the higher activity and better stability. Further 6% H2 addition to the methane feed suppressed the aromatic type of coke formation effectively,and improved the stability of catalyst markedly,moreover gave a much longer reaction life of catalyst (53 h at 1023 K and 5400 ml/(g·h)) and much more formation amounts of benzene and hydrogen. With increase of methane space velocity,both the naphthalene formation selectivity and the coke formation selectivity were decreased by the shortened contact time;the benzene formation selectivity and total formation amount before the complete deactivation of catalyst were increased ly,while the total naphthalene and coke formation amounts did not change much.At high methane space velocity (≥5400 ml/(g·h)),a new middle temperature coke derived from the high temperature aromatic coke was formed on the catalyst; all the coke formed could be burnt off at lower temperature in oxygen,compared with those obtained at low space velocity. Considering the benzene formation amount and catalyst stability together,5400 ml/(g·h) was proved to be the most efficient methane space velocity for benzene production.

  17. Utilisation de produits organiques oxygénés comme carburants et combustibles dans les moteurs. Deuxième partie : Les différentes filières d'obtention des carburols. Analyse technico-économique Using Oxygenated Organic Products As Fuels in Engines. Part Two: Different Systems for Producing Alcohol Fuels. Technico-Economic Analysis

    Directory of Open Access Journals (Sweden)

    Chauvel A.

    2006-11-01

    Full Text Available Parmi les produits à même d'être substitués aux hydrocarbures pour la constitution des carburants, les composés organiques oxygénés occupent une place prépondérante à cause de leurs caractéristiques favorables à la combustion dans les moteurs, qu'ils soient employés purs ou mélangés (seuls ou à plusieurs aux hydrocarbures, constituants des carburants classiques. Dans cet article, ces composés oxygénés sont désignés sous le nom de carburols. Alors que l'objet de la première partie de l'étude a été d'examiner les conséquences techniques de l'emploi de ces produits sur les circuits de distribution et le fonctionnement des véhicules, il s'agit dans la présente partie d'analyser les caractéristiques technico-économiques de leur fabrication. En particulier, on y aborde successivement les points suivants : - disponibilités en matières premières : ressources fossiles et végétales ; - analyse technique des divers modes d'obtention - analyse économique ; - programmes nationaux. Among products that can be substituted for hydrocarbons for producing fuels, oxygenated organic compounds occupy a preponderant position because of their favorable characteristics for combustion in engines whether they are used in a pure form or in mixtures (alone or severally with hydrocarbons which are used to make up conventional fuels. In this article these oxygenated compounds are given the name carburols (alcohol fuels. Whereas the aim of Part 1 was to examine the technical consequences of using such products in distribution circuits and for vehicle operating, Part 2 is an analysis of the technico-economic aspects of manufacturing them. In particular, the following points are taken up successively: (a availabilities of raw materials. fossil and vegetebal resources; (b technical analysis of various production methods; (c economic analysis; (d national programs. Depending on the amounts involved, a distinction is made among alternative

  18. Comparaison de quelques techniques d'extraction pour l ...

    African Journals Online (AJOL)

    SARAH

    13 nov. 2015 ... machine s'est réduit à une (1) personne contre deux (2) personnes pour la manipulation de la .... Design, fabrication and performance evaluation of an improved cassava mash sifter. Journal of. Agriculture and Veterinary ...

  19. Analysis of the DWPF glass pouring system using neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Calloway, T.B. Jr.; Jantzen, C.M. [Westinghouse Savannah River Co., Aiken, SC (United States). Savannah River Technology Center; Medich, L.; Spennato, N. [Pavillion Technologies, Inc., Austin, TX (United States)

    1997-08-05

    Neural networks were used to determine the sensitivity of 39 selected Melter/Melter Off Gas and Melter Feed System process parameters as related to the Defense Waste Processing Facility (DWPF) Melter Pour Spout Pressure during the overall analysis and resolution of the DWPF glass production and pouring issues. Two different commercial neural network software packages were used for this analysis. Models were developed and used to determine the critical parameters which accurately describe the DWPF Pour Spout Pressure. The model created using a low-end software package has a root mean square error of {+-} 0.35 inwc (< 2% of the instrument`s measured range, R{sup 2} = 0.77) with respect to the plant data used to validate and test the model. The model created using a high-end software package has a R{sub 2} = 0.97 with respect to the plant data used to validate and test the model. The models developed for this application identified the key process parameters which contribute to the control of the DWPF Melter Pour Spout pressure during glass pouring operations. The relative contribution and ranking of the selected parameters was determined using the modeling software. Neural network computing software was determined to be a cost-effective software tool for process engineers performing troubleshooting and system performance monitoring activities. In remote high-level waste processing environments, neural network software is especially useful as a replacement for sensors which have failed and are costly to replace. The software can be used to accurately model critical remotely installed plant instrumentation. When the instrumentation fails, the software can be used to provide a soft sensor to replace the actual sensor, thereby decreasing the overall operating cost. Additionally, neural network software tools require very little training and are especially useful in mining or selecting critical variables from the vast amounts of data collected from process computers.

  20. High temperature corrosion of 9Cr-1Mo ferritic steel P91 modified, in oxidizing-carburizing atmospheres; Corrosion a temperatura alta del acero ferritico 9Cr-1Mo modificado P91, en atmosferas simuladas oxidantes-carburantes

    Energy Technology Data Exchange (ETDEWEB)

    Pena-Ballesteros, D. Y.; Vazquez-Quintero, C.; Laverde-Catano, D.; Serna, G.

    2012-11-01

    High temperature corrosion in processing units of the chemical, petrochemical, and thermoelectric carbochemical is of high interest, due to the costs generated by sudden failures caused by deterioration in the mechanical properties of metals, being the carburization of the metallic matrix the most important corrosion mechanism resulting in loss of ductility and creep resistance. In this research a 9Cr-1Mo modified steel P91 was exposed to simulated atmospheres oxidant-fuel gas mixtures simultaneous in equilibrium of CO, CO{sub 2}, CH{sub 4}, H{sub 2}O and H{sub 2}, similar to those produced in the refining industry, at temperatures between 550 and 750 degree centigrade. The microstructural evolution of the metal matrix was analyzed, also the growth, evolution and behavior of oxide layers and carburized, establishing the mechanism of deterioration of the material and the extent of damage for times exceeding 700 h of exposure. (Author) 21 refs.

  1. 重型汽车用渗碳齿轮检验方法的分析研究%Study on Testing Method of Carburizing Gears for Heavy Duty Trucks

    Institute of Scientific and Technical Information of China (English)

    张红梅; 郝爽; 孟丽

    2012-01-01

    变速器和车桥等部件中的传动齿轮是保证汽车行驶安全的核心部件,齿轮的组织性能的检验是其质量控制的重要保证。本文就重型汽车渗碳齿轮的化学成分、金相组织、碳化物评级、残余奥氏体和马氏体评级、渗碳淬火有效硬化层深、表面和心部硬度等检验方法和要求进行了详细的研究分析,可为重型汽车用渗碳齿轮的设计、制造及检验提供参考依据。%Driving gears are key components to ensure the running safety of automobiles, and the tests of the mierostrueture properties of gears are the important guarantee of its quality eontrol. Aiming at carburized gears for heavy duty trucks, the paper in detail studied the testing methods and demand of the chemical composition, mierostrueture, carbide rating, retained anstenite and martensite rating, carburizing quenching effectively hardening depth, surface and core hardness. The results can provide a reference basis the design, manufacturing and test of carburizing gears for heavy duty trucks.

  2. 高合金钢过饱和固体渗碳的计算机模拟%Computer Simulation of Super-saturated Solid Carburization of High Alloy Steels

    Institute of Scientific and Technical Information of China (English)

    叶健松; 匡琦; 戚正风

    2001-01-01

    The process of super-saturated carburization of high alloy steels was discussed,and the corresponding mathematical model was presented.The carbon profile of carburized layer for 3Cr13 and Cr10 with solid carburization is simulated by computer.The simulation result is basically agreement with the experimental one.This testifies that the mathematical model and method are feasible.%本文讨论了高合金钢过饱和渗碳过程,提出了计算高合金钢固体渗碳的碳浓度分布的数学模型,以此模型对3Cr13和Cr10固体渗碳的碳浓度分布进行了计算机模拟。模拟结果与相应的实验结果基本吻合,表明了本文的数学模型及方法是可行的。

  3. 奥氏体不锈钢低温气体渗碳过程中温度对渗碳层的影响%Effect of temperature on low-temperature gas carburized layer of austenitic stainless steel

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      利用扫描电镜、电子探针、显微硬度计、CS电化学工作站研究AISI316奥氏体不锈钢经低温气体渗碳处理后渗碳层显微组织及力学特性的变化。结果表明,在450,470,500℃温度条件下,在AISI316奥氏体不锈钢表面获得10~33μm的硬化层,随温度的不同,渗层深度、硬度梯度、耐蚀性能呈现不同的变化规律。%Microstructure and mechanical properties of low⁃temperature gas carburized layer of AISI316 austenitic stainless steel were investigated by means of scanning electron microscopy(SEM),micro hardness tester,CS electrochemical workstation. The experimental results indicate that the thickness of hardened layer is within the range of 10 to 33 μm,when AISI316 austenitic stainless steel is carburized at 450,470,500 ℃. With the variation of carburizing temperature,different case depth,hardness gradient and corrosion resistance are observed in the steel.

  4. 铝氮比对轿车用渗碳钢晶粒混晶的影响%INFLUENCE OF ALUMINUM-NITROGEN RATE ON MIXEDG RAIN STRU CTURE OF20 MnCr 5 CARBURIZING STEEL FOR CAR

    Institute of Scientific and Technical Information of China (English)

    齐建军; 李绍杰

    2015-01-01

    在转炉长流程生产工艺条件下,研究了铝含量、氮含量和铝氮比对轿车用20MnCr5渗碳钢晶粒度混晶的影响。结果表明,在规定的热处理工艺条件下,20MnCr5渗碳齿轮钢产生混晶的主要原因是钢中氮含量偏低。当20MnCr5钢中铝含量≥00.25%且铝氮比≥3时,可以达到轿车渗碳钢对奥氏体晶粒度的要求。%It is researched the influence of contents of aluminum and nitrogen and their proportion on mixed grain size of 20MnCr5 carburizing steel for cars in long process of converter.The result shows that under the specified heat treatment process, the main reason for mixed grain in 20MnCr5 carburizing gear steel is too low nitrogen content in steel.The demand of car carburizing steel for austenite brain size can be met if the a-luminum content not being lower than 0.025%and aluminum-nitrogen proportoi n notb eing smallert han 3.

  5. Quel contrôle de gestion pour les startups ?

    OpenAIRE

    Meyssonnier, François

    2015-01-01

    Une étude de huit PME fondées sur la science permet d’identifier les spécificités du contrôle de gestion des startups. Dans les startups émergentes le dirigeant n’utilise que des linéaments de contrôle de gestion essentiellement pour développer son approche cognitive du business model. Dans les startups en croissance le contrôle de gestion a un rôle de garde-fou et les outils de pilotage de la performance sont utilisés essentiellement de façon interactive et pour la prévision. Les principaux ...

  6. Influence of delayed pouring on irreversible hydrocolloid properties

    OpenAIRE

    Stéfani Becker Rodrigues; Carolina Rocha Augusto; Vicente Castelo Branco Leitune; Susana Maria Werner Samuel; Fabrício Mezzomo Collares

    2012-01-01

    The aim of this study was to evaluate the physical properties of irreversible hydrocolloid materials poured immediately and after different storage periods. Four alginates were tested: Color Change (Cavex); Hydrogum (Zhermack); Hydrogum 5 (Zhermack); and Hydro Print Premium (Coltene). Their physical properties, including the recovery from deformation (n = 3), compressive strength (n = 3), and detail reproduction and gypsum compatibility (n = 3), were analyzed according to ANSI/ ADA specificat...

  7. Influence of delayed pouring on irreversible hydrocolloid properties

    Directory of Open Access Journals (Sweden)

    Stéfani Becker Rodrigues

    2012-10-01

    Full Text Available The aim of this study was to evaluate the physical properties of irreversible hydrocolloid materials poured immediately and after different storage periods. Four alginates were tested: Color Change (Cavex; Hydrogum (Zhermack; Hydrogum 5 (Zhermack; and Hydro Print Premium (Coltene. Their physical properties, including the recovery from deformation (n = 3, compressive strength (n = 3, and detail reproduction and gypsum compatibility (n = 3, were analyzed according to ANSI/ADA specification no. 18. Specimens were stored at 23ºC and humidity and were then poured with gypsum immediately and after 1, 2, 3, 4, and 5 days. The data were analyzed by two-way analysis of variance (ANOVA and Tukey's test at p < 0.05. All of the alginate impression materials tested exhibited detail reproduction and gypsum compatibility at all times. Hydro Print Premium and Hydrogum 5 showed recovery from deformation, as established by ANSI/ADA specification no. 18, after 5 days of storage. As the storage time increased, the compressive strength values also increased. Considering the properties of compounds' recovery from deformation, compressive strength, and detail reproduction and gypsum compatibility, irreversible hydrocolloids should be poured immediately.

  8. Big Bang pour le grand public - French version only

    CERN Multimedia

    2004-01-01

    Pour commémorer les 50 ans du CERN et l'année de la physique en 2005, la section de physique de l'Université de Genève ouvre une fois de plus ses portes aux non initiés et organise une série de conférences de vulgarisation scientifique. La première conférence, le 7 décembre prochain aura pour thème le Big-Bang et les observations qui corroborent cette théorie. Le Professeur Georges Meylan, Directeur du Laboratoire d'Astrophysique de l'EPFL, donnera cette conférence destinée à tous les publics. Chacune des conférences débutera par une démonstration de détection de rayons cosmiques dans l'auditoire et l'utilisation de ces signaux venus du fond de l'univers pour créer une ?musique cosmique', en collaboration avec le Professeur Ellberger et Nikolai Mihailov du conservatoire de musique de Genève. Ces processus cosmiques étant aléatoires, chacun de ces concerts sera unique. Les preuves observationnelles du Big Bang par le Professeur Georges Meylan Directeur du Laboratoire d'Astrophysique ...

  9. Logistique ST-HM pour le projet LHC

    CERN Document Server

    Prodon, S

    2002-01-01

    Ce papier a pour objectif de présenter la structure mise en place au sein du groupe ST-HM pour assurer la logistique d'installation du projet LHC. L'aspect traèabilité sera tout d'abord évoqué avec notamment la mise en place d'outils informatiques tels que le formulaire EDH de demande d'intervention transport-manutention et le système SIRIAC de suivi et de validation des transports réalisés. Ces développements informatiques s'intègrent dans le cadre plus général des modalités de traèabilité des équipements établies en collaboration avec le groupe SL/MR, chargé de la gestion des espaces pour le projet LHC. Les procédures proprement dites de transport des équipements feront l'objet d'un développement particulier. Leur processus d'élaboration sera détaillé : des premières réunions d'information jusqu'à la validation finale par les trois parties (demandeur, groupe ST-HM et contractant ST-HM). L'intégration de ces documents dans la logistique générale ST-HM de planification des ressou...

  10. Éléments finis pour les fluides incompressibles

    CERN Document Server

    Azaïez, Mejdi; Mund, Ernest

    2011-01-01

    Cet ouvrage présente l'ensemble des concepts et méthodes nécessaires à la modélisation numérique par éléments finis du comportement des fluides visqueux newtoniens incompressibles. Après un bref rappel des équations de base et des modèles simplifiés, il expose en détail les techniques d'approximation de ces équations par éléments finis pour les dépendances spatiale et temporelle (problèmes de diffusion, d'advection-diffusion et de transport). Une attention toute particulière est portée à la discrétisation spatiale des équations de Stokes et aux algorithmes temporels pour la simulation numérique directe des équations de Navier-Stokes. Un chapitre ancillaire résume les méthodes de résolution des systèmes algébriques de grande taille à structure creuse, caractéristiques des méthodes d'éléments finis. L'exposé clair, didactique et progressif offre un contenu équilibré entre théorie et pratique. Ce manuel constitue ainsi une référence indispensable pour les étudiants de ma...

  11. Influence of delayed pouring on irreversible hydrocolloid properties.

    Science.gov (United States)

    Rodrigues, Stéfani Becker; Augusto, Carolina Rocha; Leitune, Vicente Castelo Branco; Samuel, Susana Maria Werner; Collares, Fabrício Mezzomo

    2012-01-01

    The aim of this study was to evaluate the physical properties of irreversible hydrocolloid materials poured immediately and after different storage periods. Four alginates were tested: Color Change (Cavex); Hydrogum (Zhermack); Hydrogum 5 (Zhermack); and Hydro Print Premium (Coltene). Their physical properties, including the recovery from deformation (n = 3), compressive strength (n = 3), and detail reproduction and gypsum compatibility (n = 3), were analyzed according to ANSI/ADA specification no. 18. Specimens were stored at 23ºC and humidity and were then poured with gypsum immediately and after 1, 2, 3, 4, and 5 days. The data were analyzed by two-way analysis of variance (ANOVA) and Tukey's test at p < 0.05. All of the alginate impression materials tested exhibited detail reproduction and gypsum compatibility at all times. Hydro Print Premium and Hydrogum 5 showed recovery from deformation, as established by ANSI/ADA specification no. 18, after 5 days of storage. As the storage time increased, the compressive strength values also increased. Considering the properties of compounds' recovery from deformation, compressive strength, and detail reproduction and gypsum compatibility, irreversible hydrocolloids should be poured immediately.

  12. In-service testing of Ni{sub 3}Al coupons and trays in carburizing furnaces at Delphi Saginaw. CRADA final report

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Santella, M.L.; Viswanathan, S.; Swindeman, R.W. [Oak Ridge National Lab., TN (United States); Chatterjee, M. [General Motors Corporaion, Saginaw Division (United States)

    1998-08-01

    This Cooperative Research and Development Agreement (CRADA) report deals with the development of nickel aluminide alloy for improved longer life heat-resistant fixture assemblies for batch and continuous pusher carburizing furnaces. The nickel aluminide development was compared in both coupon and component testing with the currently used Fe-Ni-Cr heat-resisting alloy known as HU. The specific goals of the CRADA were: (1) casting process development, (2) characterization and possible modification of the alloy composition to optimize its manufacturing ability and performance under typical furnace operating conditions, and (3) testing and evaluation of specimens and prototype fixtures. In support of the CRADA objectives, coupons of nickel aluminide and the HU alloy were installed in both batch and pusher furnaces. The coupons were taken from two silicon levels and contained welds made with two different filler compositions (IC-221LA and IC-221W). Both nickel-aluminide and HU coupons were removed from the batch and pusher carburizing furnace at time intervals ranging from one month to one year. The exposed coupons were cut and mounted for metallographic, hardness, and microprobe analysis. The results of the microstructural analysis have been transmitted to General Motors Corporation, Saginaw Division (Delphi Saginaw) through reports that were presented at periodic CRADA review meetings. Based on coupon testing and verification of the coupon results with the testing of trays, Delphi Saginaw moved forward with the use of six additional trays in a batch furnace and two assemblies in a pusher furnace. Fifty percent of the trays and fixtures are in the as-cast condition and the remaining trays and fixtures are in the preoxidized condition. The successful operating experience of two assemblies in the pusher furnace for nearly a year formed the basis for a production run of 63 more assemblies. The production run required melting of 94 heats weighing 500 lb. each. Twenty

  13. Tubin, Eduard. Sonate pour violon et piano dans le mode phrygien / Pierre Gervasoni

    Index Scriptorium Estoniae

    Gervasoni, Pierre

    1995-01-01

    Uuest heliplaadist "Tubin, Eduard. Sonate pour violon et piano dans le mode phrygien. Ballade pour piano en forme de Chaconne sur un theme de Mart Saar. Sonate pour saxophone alto et piano. Le Chant des soldats enrepli. Ave Maria. Societe Chorale Estudiantine de Lund, Neeme Järvi. BIS-CD 269, distribution Harmonia Mundi (CD: 161 F), 1984/85.TT: 1h 03'46"

  14. Tubin, Eduard. Sonate pour violon et piano dans le mode phrygien / Pierre Gervasoni

    Index Scriptorium Estoniae

    Gervasoni, Pierre

    1995-01-01

    Uuest heliplaadist "Tubin, Eduard. Sonate pour violon et piano dans le mode phrygien. Ballade pour piano en forme de Chaconne sur un theme de Mart Saar. Sonate pour saxophone alto et piano. Le Chant des soldats enrepli. Ave Maria. Societe Chorale Estudiantine de Lund, Neeme Järvi. BIS-CD 269, distribution Harmonia Mundi (CD: 161 F), 1984/85.TT: 1h 03'46"

  15. Bien écrire en affaires savoir rédiger pour être lu et convaincre

    CERN Document Server

    Berrou, Jean-Paul

    1991-01-01

    Ce qu'il faut savoir pour bien rédiger ses écrits professionnels au travers d'une démarche méthodique pour bien organiser sa pensée en vue d'écrire efficacement, de conseils et de techniques pour être compris à coup sûr et être lu jusqu'au bout avec intérêt. Agrémenté de nombreux exemples concrets.

  16. Proposition d'attribution d'un contrat pour la fourniture d'aimants correcteurs a bobines decapolaires et octopolaires pour les aimants dipolaires supraconducteurs du LHC

    CERN Document Server

    1999-01-01

    Le présent document concerne l'attribution d'un contrat pour la fourniture de 616 aimants correcteurs à bobines décapolaires et octopolaires pour les aimants dipolaires supraconducteurs du LHC, avec une option pour fournir au maximum le même nombre d'aimants supplémentaires des mêmes types. A la suite d'une étude de marché (MS-2540/LHC/LHC) effectuée auprès de 39 entreprises dans treize Etats membres et deux entreprises au Japon, un appel d'offres (IT-2736/LHC/LHC) a été adressé le 24 juin 1999 à neuf entreprises dans six Etats membres et deux entreprises au Japon. A la date de clôture, le CERN avait reçu cinq offres. Il est demandé au Comité des finances d'approuver la négociation d'un contrat avec l'entreprise TESLA ENGINEERING (UK) pour la fourniture de 616 aimants correcteurs à bobines décapolaires et octopolaires pour les aimants dipolaires supraconducteurs à double ouverture du LHC, pour un montant total de 2 219 229 francs suisses, révisable pour les livraisons contractuelles pos...

  17. Hydraulic Hybrid Propulsion for Heavy Vehicles: Combining the Simulation and Engine-In-the-Loop Techniques to Maximize the Fuel Economy and Emission Benefits Propulsion hybride hydraulique des poids lourds : une approche alliant les techniques de simulation et d’« Engine-In-the-loop » (EIL afin de maximiser les économies de carburant et les avantages en termes d’émissions

    Directory of Open Access Journals (Sweden)

    Filipi Z.

    2009-09-01

    échauffement climatique fournissent une forte motivation pour le développement de moyens de propulsion véhiculaires économes. Pour les camions, cette tâche est particulièrement difficile à accomplir du fait d’importantes contraintes de taille et de poids. L’hybridation est la seule approche qui puisse déboucher sur des progrès importants à court et moyen termes. En particulier, la configuration “hybride série” découple le moteur thermique des roues et permet une flexibilité complète dans le contrôle des points de fonctionnement moteur. De plus, la conversion et le stockage de l’énergie hydraulique fournissent une densité de puissance et un rendement excellents. Le défi technologique tient à la faible densité d’énergie de l’accumulateur hydraulique, et met en avant l’importance particulière du développement du gestionnaire de l’énergie. Il est communément admis qu’il faut maintenir le moteur au point de rendement maximum mais, si l’objectif ultime en terme énergétique consiste à optimiser drastiquement le rendement du moteur, ceci induit des phases transitoires fréquentes causant pour des moteurs diesels des effets opposés tant sur l’émission de particules que sur l’agrément de conduite. Par conséquent, nous proposons une méthodologie pour le superviseur d’énergie d’un système hybride, qui prend en compte 2 objectifs : la réduction de consommation et la réduction des émissions polluantes. Les économies de carburant sont prises en compte par une approche fondée sur la simulation, alors que l’étude de l’impact des phases transitoires du moteur sur les émissions de particules, est fondée sur un dispositif expérimental combinant modèles temps réel et moteur réel – l’EIL (Engine-In-the-Loop. Le dispositif EIL confirme que le contrôle de la répartition énergétique thermique/hydraulique de l’état de charge des batteries (SOC présente des avantages certains sur celui basé sur l’approche de contr

  18. L'ASILE AU MAGHREB : QUELLE RECONNAISSANCE POUR LES ...

    African Journals Online (AJOL)

    Administrateur

    le droit algérien en matière d'asile et d'examiner la politique algérienne de l'asile ... économiques par une prise en charge internationale de la part du HCR, ces deux .... Affaires Etrangères, Justice, Travail, Intérieur. Pour les exilés ...... relations réifiées, il y a l'existence fixée vers le monde de l'interaction qui représente la ...

  19. Dessiner ses plans avec QCad le DAO pour tous

    CERN Document Server

    Pascual, André

    2009-01-01

    Logiciel libre de dessin assisté par ordinateur (DAO), QCad permet d'établi dans tous les domaines (architecture dessin industriel, schématique...) de plans rigoureux et normalisés dans un format compris par l'ensemble des logiciels de graphisme. Bien plus accessible qu'AutoCAD en termes de simplicité d'utilisation (et de prix!), il fonctionne sous Windows et Mac OS X aussi bien que sous Linux et allie convivialité et productivité pour convenir au néophyte comme au dessinateur plus aguerri.

  20. Perception pour la robotique mobile en environnement humain

    OpenAIRE

    Lerasle, Frédéric

    2008-01-01

    Ce mémoire d'habilitation à diriger les recherches porte sur la perception et la compréhension conjointe de l'espace et du milieu par un robot cognitif autonome. Dans ce contexte, la démarche consiste ici à intégrer des percepts multiples et incertains à tous les niveaux de la perception à partir de capteurs visuels embarqués. Ces travaux se structurent en deux thèmes. Le premier thème se focalise sur la perception de l'espace pour la navigation autonome en milieu intérieur. Nos travaux antér...

  1. L’adaptation pour le sous-titrage

    OpenAIRE

    2014-01-01

    Rapide tour d’horizon du monde du sous-titrage pour présenter les différentes facettes de la profession, les principaux enjeux et difficultés d’une traduction qui doit faire cohabiter le texte avec les dialogues originaux. Le but étant de faire prendre conscience au public cinéphile et aux différents acteurs du monde de l’image de l’importance de l’adaptation cinématographique. Vuelo de pájaro sobre el mundo del subtitulado con el objeto de presentar las diferentes facetas de la profesión,...

  2. Anticoking Coatings for High Temperature Petrochemical Reactors Revêtements pour réacteurs pétrochimiques à cokage réduit

    Directory of Open Access Journals (Sweden)

    Ropital F.

    2006-12-01

    Full Text Available Coke deposition is a major problem for several refinery and petrochemical processes, among which steam cracking for ethylene production. Decreasing coking rates will reduce decoking frequency and will also decrease heat transfer degradation. For these processes, a means of reducing coking phenomena is the application of anticoking coatings on the reactor walls. For this purpose a methodology was developed under a CEC Brite-Euram project with steam cracking as the main application. A first selection of the coatings and their techniques of deposition was performed according to their composition (non catalytic compounds, their resistance to carburization and oxidation and also according to the nature of the substrate. The feasibility of coating deposition was studied for small diameter furnace tubes and the techniques were perfected in particular with respect to the physicochemical characterization of the coatings and their resistance during thermal cycling and coking-decoking cycles. For the thermal cycling and the coking evaluation, industrial conditions were reproduced as closely as possible. For coking tests, a microreactor with complete mixing of the gas phase was developed for temperatures up to 950°C. The coking behavior of the coated samples was compared with conventional refractory alloys: reduction of the coking rate by a factor of 3 was measured with the most promising coating. This work was completed by the kinetic modelling of coking on uncoated materials. La formation de coke est un problème crucial pour de nombreux procédés pétrochimiques. Ralentir le cokage permet de réduire la fréquence des décokages et de limiter la dégradation du transfert thermique. Un des moyens envisageables pour réduire le cokage est le dépôt d'un revêtement à la paroi de ces réacteurs. La mise au point de tels revêtements a fait l'objet d'un projet de recherche européen Brite-Euram, pour lequel le vapocraquage a été la principale

  3. Deployment of hydrogen supply chain for fuel market in 2050: Design and development of a decision support system for scenarios analysis; Deploiement de la chaine logistique de l'hydrogene pour le marche des carburants en 2050: Conception et developpement d'un outil d'optimisation pour l'analyse de scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Patay, E.

    2008-07-15

    The deployment of a market for hydrogen energy is a new problem, considered by governments, industrialists and scientists to meet global targets of greenhouse gases emissions reduction and to ensure security in energy supply. In this context, the optimization problem of scheduling the deployment until 2050 of the hydrogen supply chain for fuel market throughout a country has been the object of our study. We get support of Air Liquide Company, his experience and experts in production and distribution of industrial hydrogen, to build an approach to the problem meeting the requirements of an industrial context. After defining and characterizing the optimization problem through a systemic analysis of the distribution infrastructure, we proposed a method suited to its resolution. Monte Carlo simulations enabled us to develop cost functions. Then we developed a heuristic algorithm for approximate optimization of these cost functions. Our approach has necessitated the definition of simulation rules, a design of experiment and a regression method, as well as a heuristic algorithm adapted to the structure of the problem. The specification, development and use of software tools have helped to validate the chosen methodology for the optimization of the uncertain problem of our study. The scenario of evolution has created a reference to validate the model and provide some analysis for early studies of deployment. (author)

  4. L'auto adaptation à des mélanges essence/alcool utilisés comme carburant automobile: le moteur souple The Self-Adapting of Gasoline/Alcohol Mixtures Used As Automotive Fuel: the Flexible Engine

    Directory of Open Access Journals (Sweden)

    Dorbon M.

    2006-11-01

    Full Text Available Le moteur souple est un moteur susceptible d'être alimenté par des carburants constitués de mélanges d'une essence classique et d'un alcool léger (méthanol ou éthanol; si la concentration de chacun des composants de ces mélanges varie, les réglages nécessaires au bon fonctionnement du véhicule se font automatiquement. Dans cet article, sont tout d'abord exposées les propriétés caractéristiques en tant que carburant automobile de l'un de ces alcools légers, le méthanol. Puis viennent les descriptions des dispositifs qui font le moteur souple c'est-à-dire d'une part les systèmes de reconnaissance du carburant et d'autre part les appareillages susceptibles de modifier les réglages du moteur (alimentation et allumage en fonction de la qualité du mélange consommé. A flexible engine is one capable of running on fuels consisting of mixtures of conventional gasoline and a light alcohol (methanol or ethanol. If the concentration of each of these components of such mixtures varies, the tuning required for the proper running of the vehicle takes place automatically. This article begins by describing the characteristic properties of one of these light alcohols (methanol as an automotive fuel. Then the equipment is described that makes an engine flexible, i. e. both the fuel recognition systems and the equipment capable of changing engine tuning (feed and ignition as a function of the quality of the mixture burned.

  5. 低碳中铬钢渗碳层的耐磨粒磨损性能研究%Study on Abrasive Wear-Resistance of Carburized Low-carbon Medium-chromium Steel

    Institute of Scientific and Technical Information of China (English)

    张黔; 孙小华; 李朝志

    2001-01-01

    The microstructure and abrasive wear-resistence of carburized layer of low-carbon medium-chromiun steel.compered with cemented 20 steel and Cr12Mo1V steel,was investigated.Carburized layer of 1Cr6Si2Mo steel contains large number of fine carbide(2.5~3.0 μm),which size smaller than that one of Cr12Mo1V.The wear-resistence of 1Cr6Si2Mo steel after carburizing and queching is obviously better than that of 20 steel.but less than that of Cr12Mo1V steel by vacuum heat treatment.%对低碳中铬钢(1Cr6Si2Mo)固体法稀土渗碳层的组织和耐磨性能与渗碳20钢及淬火Cr12Mo1V钢进行了对比试验研究。1Cr6Si2Mo钢的渗碳层内含有大量粒度为2.5~3.0 μm、弥散分布的铬碳化物,其尺寸比Cr12Mo1V钢中的共晶碳化物小。渗碳淬火后的1Cr6Si2Mo钢试样耐磨粒磨损性能大大优于渗碳淬火后的20钢,但不及真空热处理的Cr12Mo1V。

  6. Conception d'un circuit d'etouffement pour photodiodes a avalanche en mode geiger pour integration heterogene 3d

    Science.gov (United States)

    Boisvert, Alexandre

    Le Groupe de Recherche en Appareillage Medical de Sherbrooke (GRAMS) travaille actuellement sur un programme de recherche portant sur des photodiodes a avalanche mono-photoniques (PAMP) operees en mode Geiger en vue d'une application a la tomographie d'emission par positrons (TEP). Pour operer dans ce mode; la PAMP, ou SPAD selon l'acronyme anglais (Single Photon Avalanche Diode), requiert un circuit d'etouffement (CE) pour, d'une part, arreter l'avalanche pouvant causer sa destruction et, d'autre part. la reinitialiser en mode d'attente d'un nouveau photon. Le role de ce CE comprend egalement une electronique de communication vers les etages de traitement avance de signaux. La performance temporelle optimale du CE est realisee lorsqu'il est juxtapose a la PAMP. Cependant, cela entraine une reduction de la surface photosensible ; un element crucial en imagerie. L'integration 3D, a base d'interconnexions verticales, offre une solution elegante et performante a cette problematique par l'empilement de circuits integres possedant differentes fonctions (PAMP, CE et traitement avance de signaux). Dans l'approche proposee, des circuits d'etouffement de 50 pm x 50 pm realises sur une technologie CMOS 130 mn 3D Tezzaron, contenant chacun 112 transistors, sont matrices afin de correspondre a une matrice de PAMP localisee sur une couche electronique superieure. Chaque circuit d'etouffement possede une gigue temporelle de 7,47 ps RMS selon des simulations faites avec le logiciel Cadence. Le CE a la flexibilite d'ajuster les temps d'etouffement et de recharge pour la PAMP tout en presentant une faible consommation de puissance (~ 0,33 mW a 33 Mcps). La conception du PAMP necessite de supporter des tensions superieures aux 3,3 V de la technologie. Pour repondre a ce probleme, des transistors a drain etendu (DEMOS) ont ete realises. En raison de retards de production par Ies fabricants, les circuits n'ont pu etre testes physiquement par des mesures. Les resultats de ce memoire

  7. Bouger pour la sante - Dr Per Bo Mahler

    CERN Document Server

    CERN. Geneva

    2012-01-01

    Le mouvement est un facteur fondamental dans l’évolution de l’être humain : il répond grandement à ses besoins fondamentaux. Or, la littérature scientifique ne s’est intéressée réellement à l’activité physique (AP) que dans les années 1990. La journée mondiale de la santé en 2002 a passablement contribué à la reconnaissance de l’AP en tant que déterminant de la santé, dans les pays industrialisés tout comme dans les pays en développement. La littérature est unanime sur les bienfaits de l’AP modérée. Il est admis aujourd’hui que la sédentarité est un facteur de risque égal ou supérieur au tabagisme. Les recommandations : une heure d’activité physique modérée par jour pour les enfants et au moins 150 minutes d’activité modérée ou 75 minutes d’activité vigoureuse par semaine pour les adultes. Malgré cela, une grande proportion de la population reste insuffisamment active. On observe des différences conséquentes selon l’âge, le ...

  8. Soudage des aciers pour application mécanique

    CERN Document Server

    Deveaux, Dominique

    2016-01-01

    Ce guide détermine les bonnes pratiques pour comprendre les risques d’une forme d’assemblage multimatériaux : celui par soudage de nuances à forte teneur en carbone avec des éléments en acier de construction. Dans un premier temps, le rapport passe en revue l’examen des avaries sur des assemblages soudés pour l’application mécanique mettant en cause les aciers. Fissuration par fatigue, rupture fragile, rupture ductile, fissuration à chaud ou à froid sont autant de causes qui seront analysées. Dans un deuxième temps, il se concentre sur la conception des joints soudés. Du choix des nuances à la tenue vis-à-vis de la rupture fragile en passant par l’analyse en fatigue des assemblages soudés, c’est l’ensemble de la problématique qui est pris en compte.

  9. Mesurer la pauvreté pour l’éliminer

    Directory of Open Access Journals (Sweden)

    Julien Damon

    2012-01-01

    Full Text Available En 2000, l’ONU a établi des Objectifs du millénaire pour le développement, visant notamment à réduire de moitié l’extrême pauvreté d’ici 2015. En 2000, l’Union européenne a lancé sa stratégie dite de Lisbonne, contenant une invitation à « donner un élan décisif à l’élimination de la pauvreté » à l’horizon 2010. Depuis 2007, la France s’est fixé un objectif de réduction d’un tiers de la pauvreté, sur cinq ans. Ce volontarisme politique appelle, dans les trois cas, une élaboration technique afin de définir et décrire la pauvreté. À ces trois échelles française, européenne, internationale, les modes d’approche et de décompte ne sont pas les mêmes. Pour autant, ce qui les rassemble est plus important que ce qui les différencie.

  10. [On the polymerization of pour type resin (author's transl)].

    Science.gov (United States)

    Nagata, K; Hirasawa, T; Masuhara, E

    1976-05-01

    The initial polymerization point and the polymerization progress have been observed on powder-liquid pour type acrylic resin and one-liquid pour type acrylic resin. The results are as follows: 1. In case of un-heating at the bottom of powder liquid resin, in the former stage the polymerization makes the regular progress from the bottom part to the upper of the mould, but in the latter stage it does some irregular one. In case of heating at the bottom, at first it shows a better regular progress as in the case of un-heating. 2. In case of un-heating at the bottom of one-liquid resin, in the first stage the polymerization makes the regular progress from the bottom part of the resin and at the same time from its middle of the mould, and then to the upper part and the sprue part. In case of heating at the bottom, it begins just from the heated part, then it goes quite regularly to the middle, the upper, and the sprue part, and lastly the polymerization shrinkage concentrates exclusively at the sprue part.

  11. Geneva University - Les catégories pour la physique

    CERN Multimedia

    Université de Genève

    2012-01-01

    GENEVA UNIVERSITY Ecole de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92   Lundi 27 février 2012 17h00 - Auditoire Stueckelberg « Les catégories pour la physique » Marc Lachièze-Rey AstroParticule et Cosmologie Université Paris 7 Diderot, Paris La théorie des catégories est un vaste domaine des mathématiques, que l'on peut comparer à la théorie des ensembles avec une dimension de plus. De nombreuses théories et théorèmes sont (re-)formulés dans ce cadre et certains mathématiciens songent à l'utiliser ce pour refonder la totalité des mathématiques. Catégories et foncteurs (morphismes entr...

  12. Les mesures de métrologie pour le CLIC

    CERN Document Server

    Cherif, A

    2008-01-01

    Le projet CLIC est en tout point un défi technique majeur ; c?est le cas également pour la mesure dimensionnelle. Quels sont les équipements et les méthodes qui permettent de caractériser les pièces avec une incertitude de mesure aussi réduite que possible, vu les tolérances micrométriques imposées ? Afin de répondre à cette question, une veille technologique a été maintenue sur une longue période. Les acteurs relevants ont été contactés pour bénéficier d?une ouverture sur les dernières avancées dans le domaine. Différentes techniques ont été étudiées et comparées telles que la digitalisation, la tomographie X, la mesure tridimensionnelle. L'assemblage de haute précision des composants est aussi primordial. Sa mise en ?uvre sous un microscope optique ou à l'aide d'une machine tridimensionnelle est en cours d?étude. L'exposé traitera aussi de la mesure de rugosité, un domaine où nous disposons de moyens adaptés aux exigences spécifiques du projet.

  13. Quelle analyse pour les pronoms clitiques du cadien ?

    Directory of Open Access Journals (Sweden)

    Girard Francine

    2012-07-01

    Full Text Available Depuis les travaux de Perlmutter (1971, Kayne (1975 et Zwicky (1977, les pronoms clitiques des langues romanes en général et du français en particulier ont fait l’objet d’une recherche intense. Ces travaux, en ce qui concerne le français, se sont d’abord concentrés sur le français standard ou de référence (FR avant de se tourner dans les années 1990 vers des variétés de français parlés informels (FPI tels que celui de l’Hexagone (Zribi-Hertz, 1994, du Québec (Roberge,1990 et Auger,1995 ou encore du français pied-noir (Roberge, 1990, l’accent étant mis le plus souvent sur les pronoms sujets. Deux approches principales se dégagent de ces recherches sur le français, l’une traitant les pronoms clitiques comme des arguments et l’autre, commes des affixes flexionnels du verbe. Nous présenterons ici les pronoms clitiques sujets et objets du français cadien, une variété de français parlée dans le sud-ouest de la Louisiane, sur un territoire dénommé Acadiana, un triangle ayant pour base la côte du Golfe du Mexique et pour sommet, la paroisse d’Avoyelles. Les pronoms clitiques de cette variété de français essentiellement orale, dérivée de dialectes du Grand- Ouest, Poitou principalement (Bodin, 1987, arborent un certain nombre de particularismes qui en font un terrain d’étude intéressant de la variation dans ce domaine en français. Nous verrons que l’examen des données cadiennes révèle que les deux approches principales mentionnées ci-dessus pour le français s’avèrent inadéquates pour rendre compte des pronoms clitiques de cette variété dont le comportement se distingue à la fois de ceux du FR et des FPI même s’il partage plus de traits communs avec ces derniers. Nous montrerons pour conclure que, si les pronoms clitiques cadiens semblent bien impliqués dans un processus de grammaticalisation en direction du statut d’affixes marqueurs d’accord, ils présentent plusieurs traits dont

  14. Session du Conseil du CERN : le ministre britannique, Robert Jackson, souligne l'intérêt de on pays pour l'avenir du CERN : décisions du Conseil pour la mise en oeuvre des recommandations du Comité d'évaluation du CERN: départ anticipé pour 200 membres au moins du personnel - mise à jour de la méthode de calcule pour les contributions des Etats Membres au budget

    CERN Multimedia

    CERN Press Office. Geneva

    1988-01-01

    Session du Conseil du CERN : le ministre britannique, Robert Jackson, souligne l'intérêt de on pays pour l'avenir du CERN : décisions du Conseil pour la mise en oeuvre des recommandations du Comité d'évaluation du CERN: départ anticipé pour 200 membres au moins du personnel - mise à jour de la méthode de calcule pour les contributions des Etats Membres au budget

  15. Energy and Exergy Balances for Modern Diesel and Gasoline Engines Bilans d’énergie et d’exergie pour des moteurs Diesel et essence récents

    Directory of Open Access Journals (Sweden)

    Bourhis G.

    2009-11-01

    ée réduite, à faible frottement, et le second un moteur Diesel à injection directe à rampe commune, également de cylindrée réduite. Pour chacun de ces deux moteurs, à l’aide de données expérimentales obtenues sur banc moteur, deux bilans d’énergie et d’exergie ont été effectués pour deux points de fonctionnement à charge partielle, représentatifs du cycle NEDC. Dans le cas du moteur Diesel, le travail effectif, représentant environ 30 % et 55 % de l’énergie introduite dans la chambre de combustion, est perdu (sous forme de chaleur, et plus spécifiquement dans les gaz d’échappement, l’eau de refroidissement et l’huile. Mais, lorsque l’on considère le bilan d’exergie, seulement 12 % de l’exergie totale introduite par l’intermédiaire du carburant peut être récupérée afin de produire un travail utile. Dans l’hypothèse d’un rendement de récupération de 25 %, le rendement du moteur Diesel pourrait être augmenté de 10 %. Dans le cas du moteur essence, l’augmentation de rendement pourrait même atteindre 15 %.

  16. Dessiner son parcours professionnel, pour en tirer des enseignements

    Directory of Open Access Journals (Sweden)

    Pascale Corten-Gualtieri

    2011-02-01

    Full Text Available Dans le cadre de la formation continue pour des enseignants du supérieur, une activité d’expression visuelle a soutenu une posture réflexive à propos du développement professionnel de chacun. Il a été demandé aux enseignants de dessiner leur parcours professionnel en le comparant à un parcours routier. Ce dessin a ensuite servi de support aux enseignants pour dégager les leviers et les freins de leur développement professionnel, puis pour clarifier leur(s perspective(s d’évolution professionnelle. Cadrage théorique et échanges en binômes ont enrichi ce regard distancié. L’ensemble de ces activités constitue une préparation efficace et motivante à la rédaction d’un portfolio dans lequel l’enseignant analyse ses pratiques et son développement professionnels. Cet article décrit le cadre théorique et les modalités de cet ensemble d’activités ; il analyse ensuite les résultats obtenus, essentiellement à partir de l’étude du corpus de dessins réalisés par les enseignants, et d’une enquête d’évaluation réalisée auprès de ceux-ci.A recent visual creative activity carried out during a continuous education programme for teachers in higher education enhances reflective practice regarding professional development. Teachers were asked to draw their professional path as they would draw a route map. On the basis of this drawing, they were able to highlight the levers and obstacles in their professional development and then clarify their perspectives in terms of professional growth. This analysis was emphasized using a theoretical framework and exchanges in teams of two. All activities comprised an effective and stimulating preparation for writing a portfolio in which the teachers analyzed their professional practices and development. This article describes the theoretical framework and methods used during these activities; it then analyzes the results obtained based on the study of the various drawings made

  17. Caracterisation thermique de modules de refroidissement pour la photovoltaique concentree

    Science.gov (United States)

    Collin, Louis-Michel

    Pour rentabiliser la technologie des cellules solaires, une reduction du cout d'exploitation et de fabrication est necessaire. L'utilisation de materiaux photovoltaiques a un impact appreciable sur le prix final par quantite d'energie produite. Une technologie en developpement consiste a concentrer la lumiere sur les cellules solaires afin de reduire cette quantite de materiaux. Or, concentrer la lumiere augmente la temperature de la cellule et diminue ainsi son efficacite. Il faut donc assurer a la cellule un refroidissement efficace. La charge thermique a evacuer de la cellule passe au travers du recepteur, soit la composante soutenant physiquement la cellule. Le recepteur transmet le flux thermique de la cellule a un systeme de refroidissement. L'ensemble recepteur-systeme de refroidissement se nomme module de refroidissement. Habituellement, la surface du recepteur est plus grande que celle de la cellule. La chaleur se propage donc lateralement dans le recepteur au fur et a mesure qu'elle traverse le recepteur. Une telle propagation de la chaleur fournit une plus grande surface effective, reduisant la resistance thermique apparente des interfaces thermiques et du systeme de refroidissement en aval vers le module de refroidissement. Actuellement, aucune installation ni methode ne semble exister afin de caracteriser les performances thermiques des recepteurs. Ce projet traite d'une nouvelle technique de caracterisation pour definir la diffusion thermique du recepteur a l'interieur d'un module de refroidissement. Des indices de performance sont issus de resistances thermiques mesurees experimentalement sur les modules. Une plateforme de caracterisation est realisee afin de mesurer experimentalement les criteres de performance. Cette plateforme injecte un flux thermique controle sur une zone localisee de la surface superieure du recepteur. L'injection de chaleur remplace le flux thermique normalement fourni par la cellule. Un systeme de refroidissement est installe

  18. Pour une histoire de la Géochimie

    OpenAIRE

    Letolle, René

    1996-01-01

    International audience; Le Larousse du vingtième Siècle définit ainsi la Géochimie : "Ensemble des études chimiques qui se rapportent à l'écorce terrestre". Cette définition, reprise pour l'essentiel par les dictionnaires plus récents, reste globalement valable, à ceci près que l'objet de cette science s'est étendu depuis longtemps (et bien avant 1930), à d'autres sphères terrestres que l'"écorce", et que la définition s'est affinée et élargie. Ce n'est plus "l'ensemble des études" : publier ...

  19. The effect of surface wettability on inertial pouring flows

    CERN Document Server

    Bouwhuis, Wilco

    2015-01-01

    A liquid poured from a curved solid surface can separate as a steady jet or sheet, or trickle down along the solid surface. It was shown by Duez et al. [Phys. Rev. Lett. 104, 084503 (2010)] that surface wettability controls the separation of an inertial flow from a solid surface to an unexpected degree, which was further motivated by an inertial-capillary adhesion model. In this paper we extend the analysis by a control volume calculation that takes into account the velocity profile within the flowing layer, supported by Boundary Integral potential flow simulations, and the detailed capillary forces induced by the local curvatures of the sheet. Our analysis captures the appearance of a critical Weber number below which no steady separated solutions can be sustained. We investigate the dependence of the critical Weber number on the wettability and sharpness of the edge of the curved solid, and recover the key experimental trends.

  20. Enveloppe hybride pour bâtiment économe

    OpenAIRE

    Joussellin, Florence; Faure, Xavier; Johannes, Kévyn; Pierson, Patrick; Quénard, Daniel

    2008-01-01

    National audience; Pour réduire les consommations énergétiques dans les bâtiments, des solutions passives ont été développées en augmentant fortement l'isolation des parois extérieures. Un des moyens d'améliorer l'efficacité énergétique du bâti est de concevoir des façades multifonctionnelles qui permettent de capter les énergies disponibles localement : c'est le principe des enveloppes hybrides, capable à la fois d'isoler, de protéger, mais aussi de capter, stocker, transporter l'énergie. L'...

  1. Soft drink "pouring rights": marketing empty calories to children.

    Science.gov (United States)

    Nestle, M

    2000-01-01

    Healthy People 2010 objectives call for meals and snacks served in schools to contribute to overall diets that meet federal dietary guidelines. Sales in schools of foods and drinks high in calories and low in nutrients undermine this health objective, as well as participation in the more nutritious, federally sponsored, school lunch programs. Competitive foods also undermine nutrition information taught in the classroom. Lucrative contracts between school districts and soft drink companies for exclusive rights to sell one brand are the latest development in the increasing commercialization of school food. These contracts, intended to elicit brand loyalty among young children who have a lifetime of purchases ahead of them, are especially questionable because they place schools in the position of "pushing" soft drink consumption. "Pouring rights" contracts deserve attention from public health professionals concerned about the nutritional quality of children's diets.

  2. Une interface gestuelle pour l'apprentissage de la rythmique

    OpenAIRE

    Kamp, Jean-François; Ménier, Gildas; Gibet, Sylvie

    2012-01-01

    Session "Atelier IHMA"; National audience; Le système pédagogique d'apprentissage de la rythmique que nous présentons dans ce papier relève à la fois de l'interaction gestuelle et de l'instrument de musique virtuel. Il utilise le gant de données CyberGlove® comme modalité en entrée pour piloter une application musicale d'enregistrement, de production et de modification de sons de percussion. Le papier présente les principes de base du système qui consiste à générer des sons de percussion par ...

  3. QUEL AVENIR POUR LA FINANCE ISLAMIQUE EN TUNISIE ?

    OpenAIRE

    AJILI, WISSEM; GARA, ZEINEB BEN

    2013-01-01

    RESUME: L’article a pour objectif de déterminer les facteurs explicatifs de la réticence (ou non) des tunisiens vis-à-visde la finance islamique et d’apprécier le potentiel de développement d’un système financier islamique en Tunisie sur le moyen-long terme. Ainsi, sur la base d’une étude exploratoire menée conjointement auprès des professionnels de la finance conventionnelle et islamique et des ménages, plusieurs facteurs de réticence ont été identifiés. Néanmoins, tandis que les professionn...

  4. Quel gestion de carrière pour quels seniors ?

    OpenAIRE

    Carrer, Leslie-Anne

    2007-01-01

    Ce document pose un des aspects de l'objet de la recherche.; Document LEST. Séminaire de thèse; Plus de 30 années de dispositifs divers pour favoriser le départ des plus anciens auront eu des conséquences importantes sur la façon dont les dirigeants d'entreprises considèrent leurs salariés les plus âgés. Les divers recours aux préretraites ont non seulement constitué une catégorie de jeunes retraités actifs, mais ils ont aussi contribué à créer une image du travailleur vieillissant bien spéci...

  5. Pour une autre lecture de la guerre de Gaza

    Directory of Open Access Journals (Sweden)

    Jean-François Legrain

    2009-02-01

    Full Text Available En décalage avec les idées reçues habituellement, l'Auteur propose une relecture de l'offensive l’armée israélienne dans la bande de Gaza (27 décembre 2008-21 janvier 2009 tant des justifications de son déclenchement avancées par le gouvernement israélien que sur l’approche de son bilan menée en termes de victoire palestinienne. Considérant qu'elle s'inscrit dans une logique israélienne consistant à tout mettre en œuvre pour repousser sine die tout accord sur le fond avec les Palestiniens, il suggère que la force réelle ou alléguée de Hamas est utilisée par le gouvernement israélien pour justifier auprès de la communauté internationale en termes de lutte contre le terrorisme une politique en réalité visant à détruire toute institutionnalisation du nationalisme palestinien.This article is an attempt to explore new schemes for the full understandig of what was the challenge in the last war in Gaza’s Strip. Between December 27th and January 21st nothing less than 1330 people died while 5450 others remained injuried on the Palestinian side. Ten Israeli soldiers and three civilians died in the meantime. This article is an interpretation of the Israeli way of managing the image of the Palestinian resistance movment in years, through the Muslim Brothers, FATHA, and now Hamas, as a danger for democracy and the western world. The figure of the trouble maker is used in order to justify a long term conflict which end Israel is the only country capable to put an end to.

  6. Entre science et subsistance : quel avenir pour les chercheurs africains ?

    Directory of Open Access Journals (Sweden)

    Gaillard Jacques

    2002-11-01

    Full Text Available Peu d’études empiriques sur l’état de la science en Afrique sont aujourd’hui disponibles dans l’important corpus des écrits sur la science et la technologie en Afrique. Fondé sur les résultats d’une étude financée par la Commission Européenne, le Ministère des Affaires Étrangères (MAE et l’Institut de Recherche pour le Développement (IRD, cet article tente de faire le point sur la réalité aujourd’hui du métier de chercheur en Afrique. Si les activités scientifiques et techniques se sont institutionnalisées et professionnalisées en Afrique au cours des trente dernières années, les efforts déployés n’ont pas été suffisants pour créer, à moyen ou long terme, une dynamique durable de production scientifique et de reproduction des communautés scientifiques. La situation aujourd’hui est critique dans de nombreux pays de l’Afrique Médiane (Afrique sub-saharienne hors Afrique du Sud qui subissent une dégradation des systèmes scientifiques et techniques et des conditions de l’exercice du métier de chercheur. Les résultats des études empiriques présentés dans cet article donnent non seulement une image vivante de la condition de chercheur sur le continent, mais contribuent à poser un diagnostic en terme d’urgence politique.

  7. 1Cr11Ni2W2MoV钢渗碳层中孪晶组织形成原因及对性能的影响%Twin forming reason in carburized layer and its effect on mechanical properties of 1Cr11Ni2W2MoV steel

    Institute of Scientific and Technical Information of China (English)

    刘松

    2011-01-01

    Twin forming reason in carburized layer of 1Cr11Ni2W2MoV steel and its effect on the mechanical properties were investigated with microstructure observation,fracture examination,micro hardness test and EDS analysis.The results show that the twin forming reason is related with the lower carbon potential and higher carburizing temperature.The twin existing in carburized layer changes the fracture mode and results in the brittleness increase, and it should be regarded as defect in carburized layer of 1Cr11Ni2W2MoV steel.%采用显微组织观察、断口形貌分析、显微硬度测试和能谱分析,对1Cr11Ni2W2MoV钢渗碳层中孪晶组织形成原因及其对性能的影响进行了研究.结果表明,1Cr11Ni2W2MoV钢渗碳层中出现孪晶的原因可能与渗碳时工件周围碳势较低,且渗碳温度较高有关;渗碳层中孪晶组织的存在,使其断裂模式发生改变,脆性增加,应视为缺陷组织.

  8. Etude du revenu de l'acier z 10 CDNbV0902 (type 9% Cr, 2% Mo + Nb,V) envisage pour la realisation de certains composants des reacteurs a neutrons rapides

    Science.gov (United States)

    Pelletier, M.; Vilar, R. M.; Cizeron, G.

    1982-02-01

    Après trempe depuis 1100°C, l'acier étudié est formé de ferrite stable à haute température et de martensite. Au cours de revenus anisothermes, la phase martensitique est le siège de la précipitation successive de carbures des types M 3C, M 7C 3 et M 2C, ces deux derniers étant responsables d'un durcissement secondaire significatif. Aux températures plus élevées, ces carbures se dissolvent tandis qu'apparaissent des carbures des types M 23C 6 et M 6C. La phase ferritique initialement sursaturée est, par ailleurs, le siège d'une précipitation de carbures des types M 2C et M 23C 6.

  9. Liste des intrants 2010 Intrants pour l'agriculture biologique en Suisse

    OpenAIRE

    Speiser, Bernhard; Tamm, Lucius; Berner, Alfred; Maurer, Veronika; Chevillat, Véronique; Schneider, Claudia; Walkenhorst, Michael

    2010-01-01

    La liste des intrants contient tous les produits phytosanitaires, les engrais, les substrats du commerce, les produits de lutte contre les mouches des étables, les agents d’ensilage, les aliments minéraux et complémentaires, les produits pour la désinfection des stabulations et les produits contre les maladies des abeilles autorisés pour l’agriculture biologique. Cette liste est contraignante pour les producteurs de Bio Suisse. Sur les fermes Bio Suisse, seuls les produits mentionnés sont aut...

  10. Vers un instrumentarium pour les modèles musicaux CORDIS-ANIMA

    OpenAIRE

    Tache, Olivier; Cadoz, Claude

    2009-01-01

    Session: "Plates-formes pour la diffusion et pour la creation"; National audience; La modélisation physique propose un changement de paradigme dans l'Informatique Musicale, en se concentrant sur la modélisation de corps sonores virtuels plutôt que sur la modélisation des sons eux-mêmes. Elle conduit à reconsidérer en profondeur la relation entre le musicien et l'ordinateur, aussi bien au niveau conceptuel que pratique, en particulier lorsqu'il s'agit pour le musicien ou le compositeur de prat...

  11. Un imageur radar pour la perception et la caractérisation en milieu naturel

    OpenAIRE

    Rouveure, R.; Faure, P; Monod, M.O.

    2010-01-01

    National audience; Le processus de perception demeure un point critique pour les applications en environnement extérieur. Le radar hyperfréquence offre dans ce contexte un potentiel important car il permet de résoudre certaines limitations des capteurs optiques (laser, vision). Un capteur de ce type, nommé K2Pi, a été conçu pour des applications de cartographie de l'environnement. Le radar est associé à l'algorithme R SLAM, développé pour dessiner les cartes radar. La carte radar globale est ...

  12. Essai de caractérisation sous pression de panneaux en composites pour structures marines

    OpenAIRE

    Reichard, R

    1992-01-01

    Les essais traditionnels sur panneaux sandwich FRP utilisant une charge uniaxiale fournissent des données intéressantes pour les concepteurs de structure, mais ces essais ne conviennent pas bien pour les stratifiés renforcés multiaxiaux ou sandwichs. Les stratifiés sandwichs sont en général utilisés pour accroître les propriétés en flexion d'un panneau. Les essais en flexion des poutres sandwichs ne prennent pas en compte les effets de membrane de panneau qui peuvent être importants. Un certa...

  13. Fabrication de transistors monoelectroniques pour la detection de charge

    Science.gov (United States)

    Richard, Jean-Philippe

    Le transistor monoelectro'nique (SET) est un candidat que l'on croyait avoir la capacite de remplacer le transistor des circuits integres actuel (MOSFET). Pour des raisons de faible gain en voltage, d'impedance de sortie elevee et de sensibilite aux fluctuations de charges, il est considere aujourd'hui qu'un hybride tirant profit des deux technologies est plus avantageux. En exploitant sa lacune d'etre sensible aux variations de charge, le SET est davantage utilise dans des applications ou la detection de charge s'avere indispensable, notamment dans les domaines de la bio-detection et de l'informatique quantique. Ce memoire presente une etude du transistor monoelectronique utilise en tant que detecteur de charge. La methode de fabrication est basee sur le procede nanodamascene developpe par Dubuc et al. [11] permettant au transistor monoelectronique de fonctionner a temperature ambiante. La temperature d'operation etant intimement liee a la geometrie du SET, la cle du procede nanodamascene reside dans le polissage chimico-mecanique (CMP) permettant de reduire l'epaisseur des SET jusqu'a des valeurs de quelques nanametres. Dans ce projet de maitrise, nous avons cependant opte pour que le SET soit opere a temperature cryogenique. Une faible temperature d'operation permet le relachement des contraintes de dimensions des dispositifs. En considerant les variations de procedes normales pouvant survenir lors de la fabrication, la temperature d'operation maximale calculee en conception s'etend de 27 K a 90 K, soit une energie de charge de 78 meV a 23 meV. Le gain du detecteur de charge etant dependant de la distance de couplage, les resultats de simulations demontrent que cette distance doit etre de 200 nm pour que la detection de charge soit optimale. Les designs concus sont ensuite fabriques sur substrat d'oxyde de silicium. Les resultats de fabrication de SET temoignent de la robustesse du procede nanodamascene. En effet, les dimensions atteintes experimentalement s

  14. Quelle source pour la lithographie dans l'EUV ?

    Science.gov (United States)

    Ceccotti, T.

    2005-06-01

    L'impressionnante évolution des performances des circuits intégrés (CI) ces trente dernières années, répond à la désormais célèbre loi de Moore. Selon la prédiction faite en 1975 par le co-fondateur d'Intel Gordon Moore et qui n'a jamais été contredite, le nombre de transistors dans un CI allait doubler tous les 18mois. De simple intuition, la loi de Moore est devenue un impératif à respecter pour l'industrie des CI et des semi-conducteurs en général. La continuité dans les années à venir d'une telle progression technologique permettrait à ce secteur économique de garder, voire augmenter, toute son importance actuelle. Augmenter le nombre des transistors dans les CI signifie principalement réduire leur taille caractéristique de gravure et par conséquent la longueur d'onde utilisée. Depuis 2000, la lithographie dans l'extrême ultraviolet (EUVL) à 13.5 nm est considérée comme la plus prometteuse parmi les technologies appelées à remplacer la lithographie actuelle qui utilise du rayonnement laser à 193 nm comme source de lumière. La réalisation d'une machine lithographique industrielle utilisant du rayonnement EUV nécessite la résolution de nombreux problèmes technologiques qui font, depuis des années, l'objet de plusieurs programmes de recherche dans le monde. Une attention toute particulière est portée à la source de rayonnement EUVcar ses caractéristiques, notamment de puissance et de propreté, vont décider du succès ou pas de l'EUVL. Le cahier des charges d'une source EUV, les différents approches pour y répondre ainsi que leurs limites seront présentés ainsi qu'un état de l'art des performances des sources actuelles.

  15. Influence of technique and pouring time on dimensional stability of polyvinyl siloxane and polyether impressions.

    Science.gov (United States)

    Gomez-Polo, Miguel; Celemin, Alicia; del Rio, Jaime; Sanchez, Andres

    2012-01-01

    This study aimed to determine how impression technique and pouring time affect casts obtained using polyvinyl siloxane (PVS) and polyether (PE) impressions. A total of 480 impressions were taken using three techniques: single-step (SS), two-step (TS), and two-step with a spacer (TSS). Impressions were poured after 1 and 24 hours and 7 and 14 days. Significant differences (P < .01) were found between the TS technique and the SS and TSS methods as well as between PE and PVS (P < .01) in terms of the effects of pouring time. SS and TSS yielded similar dimensional results, while greater dimensional change was induced with TS. PE impressions had to be poured no later than 7 days after preparation to ensure dimensional stability.

  16. Ivermectin excreted in cattle dung after subcutaneous injection or pour-on treatment

    DEFF Research Database (Denmark)

    Sommer, C.; Steffansen, B.; Nielsen, B. Overgaard

    1992-01-01

    Heifers were treated with the recommended doses of ivermectin: 0.2 mg/kg bw by subcutaneous injection or 0.5 mg/kg bw by pour-on. An analytic procedure is described and used for the detection of ivermectin residues excreted in dung. A large amount of the higher pour-on dose was excreted during...... the first five days after dosing due to a more rapid distribution to intestinal contents. Later faecal concentrations after the pour-on treatment were lower than those found after subcutaneous injection. No degradation of ivermectin was detected in pats exposed in the field for up to 45 days. Ivermectin......-29 days after subcutaneous injection treatment, but only inhibited in dung deposited up to 13-14 days after pour-on treatment. The numbers of Nematocera larvae were not affected. In a laboratory bioassay the Diptera Musca autumnalis DeGeer and Haematobia irritans (Linnaeus) suffered higher mortality...

  17. Innovation au sens large. Une étude pour la mesure de l’innovation.

    NARCIS (Netherlands)

    Pauwels, Fernando; Cortese, Valter; Martinez, Esteban; Forrier, Anneleen; Van Hootegem, Geert; Van Ruysseveldt, Joris; Manshoven, Joke; Teirlinck, Peter

    2010-01-01

    L’innovation est considérée en général comme l’un des facteurs les plus importants pour la compétitivité des entreprises et pour la stimulation de la croissance économique et de l’emploi. Il va de soi que la mise en oeuvre d’une politique d’innovation efficiente est basée sur l’identification des

  18. L'eau en Franche-Comté: deux cartes pour poser des questions

    Directory of Open Access Journals (Sweden)

    Daniel JOLY

    1993-12-01

    Full Text Available Quatre couches d’information d’une banque de données ont été croisées pour fournir deux cartes prospectives. Elles montrent les zones qui poseront de plus en plus de problèmes pour la qualité de l’eau et les rejets non contrôlés.

  19. Ecrire pour quoi faire ? : lettres, comptes rendus, résumés de textes

    CERN Document Server

    Grabner, Cécile

    1981-01-01

    Pour tous ceux, adultes et adolescents, qui veulent vaincre leurs difficultés d'expression écrite dans leur vie quotidienne professionnelle ou scolaire, écrire pour quoi faire ? lettres comptes rendus résumés de textes est un outil de travail à utiliser en formation de groupe ou en formation autonome en fonction du niveau et du rythme personnels.

  20. [Studies on the pour type resin for denture. (II) Curing shrinkage (author's transl)].

    Science.gov (United States)

    Nagata, K

    1976-09-01

    This study was to investigate the influence of concentration of crossliniking agents in the monomer and pressure applied on the curing shrinkage in pour type resins. A pressure could improve the dimentional accuracy in both case of the syrup and the power-liquid type resins, on the other hand crosslinking agents gave adversed effect on the dimentional accuracy of the pour type resins, especially on that of the group.

  1. [Studies on the pour type resin for denture. (I) Mechanical properties (author's transl)].

    Science.gov (United States)

    Nagata, K

    1976-09-01

    The influence of crosslinking agents in syrup type resins on the several mechanical properties was studied. These data were compared with those commercially available heat-curing resin and powder-liquid pour type resins. Addition of 2 to 3 mol% of crosslinking agents to the syrup gave best results, which were between those of the heat-curing resin and the powder-liquid pour type resin.

  2. Innovation au sens large. Une étude pour la mesure de l’innovation.

    NARCIS (Netherlands)

    Pauwels, Fernando; Cortese, Valter; Martinez, Esteban; Forrier, Anneleen; Van Hootegem, Geert; Van Ruysseveldt, Joris; Manshoven, Joke; Teirlinck, Peter

    2010-01-01

    L’innovation est considérée en général comme l’un des facteurs les plus importants pour la compétitivité des entreprises et pour la stimulation de la croissance économique et de l’emploi. Il va de soi que la mise en oeuvre d’une politique d’innovation efficiente est basée sur l’identification des di

  3. Etude pilote pour l’utilisation de la Kinect V2 pour l’évaluation motrice des maladies neuromusculaires. Cas de la MFM.

    OpenAIRE

    Coton, Justine; Veytizou, Julien; Martinat, Jonathan; Barra, Kevin; THOMANN, Guillaume; Villeneuve, François

    2015-01-01

    International audience; Cet article propose d'évaluer la possibilité d'utiliser un capteur de mouvement grand public pour aider les kinésithérapeutes dans l'évaluation des capacités motrices. L'outil proposé utilise le capteur Kinect pour enregistrer les mouvements du patient et les analyses à l'aide de logique floue suivant les critères du protocole médical MFM. Dans cette étude pilote, il a été testé sur 3 patients.

  4. Accuracy of Multiple Pour Cast from Various Elastomer Impression Methods.

    Science.gov (United States)

    Haralur, Satheesh B; Saad Toman, Majed; Ali Al-Shahrani, Abdullah; Ali Al-Qarni, Abdullah

    2016-01-01

    The accurate duplicate cast obtained from a single impression reduces the profession clinical time, patient inconvenience, and extra material cost. The stainless steel working cast model assembly consisting of two abutments and one pontic area was fabricated. Two sets of six each custom aluminum trays were fabricated, with five mm spacer and two mm spacer. The impression methods evaluated during the study were additional silicone putty reline (two steps), heavy-light body (one step), monophase (one step), and polyether (one step). Type IV gypsum casts were poured at the interval of one hour, 12 hours, 24 hours, and 48 hours. The resultant cast was measured with traveling microscope for the comparative dimensional accuracy. The data obtained were subjected to Analysis of Variance test at significance level impression techniques had the percentage of variation for the height -0.36 to -0.97%, while diameter was increased by 0.40-0.90%. The values for one-step heavy-light body impression dies, additional silicone monophase impressions, and polyether were -0.73 to -1.21%, -1.34%, and -1.46% for the height and 0.50-0.80%, 1.20%, and -1.30% for the width, respectively.

  5. Accuracy of Multiple Pour Cast from Various Elastomer Impression Methods

    Directory of Open Access Journals (Sweden)

    Satheesh B. Haralur

    2016-01-01

    Full Text Available The accurate duplicate cast obtained from a single impression reduces the profession clinical time, patient inconvenience, and extra material cost. The stainless steel working cast model assembly consisting of two abutments and one pontic area was fabricated. Two sets of six each custom aluminum trays were fabricated, with five mm spacer and two mm spacer. The impression methods evaluated during the study were additional silicone putty reline (two steps, heavy-light body (one step, monophase (one step, and polyether (one step. Type IV gypsum casts were poured at the interval of one hour, 12 hours, 24 hours, and 48 hours. The resultant cast was measured with traveling microscope for the comparative dimensional accuracy. The data obtained were subjected to Analysis of Variance test at significance level <0.05. The die obtained from two-step putty reline impression techniques had the percentage of variation for the height −0.36 to −0.97%, while diameter was increased by 0.40–0.90%. The values for one-step heavy-light body impression dies, additional silicone monophase impressions, and polyether were −0.73 to −1.21%, −1.34%, and −1.46% for the height and 0.50–0.80%, 1.20%, and −1.30% for the width, respectively.

  6. Informations pour les retraités - French version only

    CERN Document Server

    Ph. Bernard

    2004-01-01

    Chers Collègues, Vous avez été nombreux à accepter l'invitation du Directeur général pour notre matinée du 15 octobre. Nous sommes très heureux de pouvoir accueillir tous ceux qui ont répondu à cette invitation. La réunion se tiendra dans l'Amphitéâtre principal et sera transmise par télévision dans la Salle du Conseil et dans les 4 salles de réunion du bât. 40 (40-S2-A01, 40-S2-B01, 40-S2-C01, 40-S2-D01). Elle commencera à 9 heures précises et nous vous prions de venir bien avant afin que tous puissent trouver leurs places dans les différentes salles. Nous répéterons cette information dans les prochains Bulletins et vous donnerons de plus amples détails si possible. Ph. Bernard Président, Comité du GAC

  7. Le CERN, chance ou risque pour Genève

    CERN Document Server

    Maiani, Luciano; Wenninger, Horst; CERN. Geneva

    1998-01-01

    Le CERN, Chance ou Risque pour Gen?ve? D?bat public contradictoire organis? avec le soutien de la Tribune de Gen?ve Lieu: Salle II, CICG,15 Rue de Varemb?. Date: Lundi 19 octobre 1998, 20h00 D?roulement de la soir?e: 1. Ouverture M. Ren? KÏchlin, Pr?sident du Grand Conseil M. Luciano Maiani, Directeur g?n?ral d?sign? du CERN 2. Introduction: Un regard critique sur le CERN (? d?signer) Le projet LHC (Manfred Buhler Broglin CERN) 3. D?bat th?matique men? par le mod?rateur (Marco Cattaneo, r?dacteur en chef de la Tribune de Gen?ve) entre trois representants de lÕopinion publique (Ren? Longet, d?put? socialiste; Yves de Pr?ville, physicien; Jacques Mirenowicz, chercheur) et trois repr?sentants du Cern (Horst Wenninger, Directeur de la Recherche/Technique, CERN; Manfred Buhler Broglin, Administra-teur du projet LHC, CERN; Maurice Bourquin, Professeur de Physique ? l'Universit? de Gen?ve et D?l?gu? de la Suisse au Conseil du CERN). Les th?mes abord?s seront: Ð A quoi sert le CERN? Ð Quel est lÕimpact ?conomiqu...

  8. Le Web pour enseigner par projets et favoriser la collaboration

    Directory of Open Access Journals (Sweden)

    Sylvie Ratté

    2004-01-01

    Full Text Available L’utilisation du Web présentée dans cet article vient appuyer une démarche pédagogique fondée sur le partage des savoirs. Dans le contexte d’une simulation industrielle, les étudiants d’un cours de programmation avancée doivent apprendre à partager leur expertise, à communiquer clairement leurs questions, à décrire des problèmes et à faire face à des retournements inattendus. Le Web devient un espace de collaboration pour diffuser les requêtes d’un client fictif, les directives, les travaux préliminaires et les ententes. Les résultats obtenus tendent à suggérer que cette approche globale force l’étudiant à mieux planifier, l’invite à mieux formuler et décrire les problèmes, augmente le niveau de collaboration et facilite la production d’analogies. Un système facilitant la logistique entourant la revue par les pairs (récupération des travaux, construction d’une grille d’évaluation et diffusion des résultats est également présenté.

  9. Pour une approche discursive des politiques publiques environnementales

    Directory of Open Access Journals (Sweden)

    Alice Baillat

    2015-01-01

    Full Text Available Depuis la montée des préoccupations environnementales au début des années 1970, relatives notamment à la gestion des territoires et des ressources naturelles, et plus récemment aux impacts du changement climatique sur les sociétés humaines, l’environnement n’a cessé de faire l’objet de nombreux débats politiques et scientifiques. Les questions environnementales ont ainsi engendré des réseaux d’influence et des interactions entre acteurs de nature et d’échelles différentes, porteurs d’intérêts divergents et parfois même contradictoires. Combinée à l’extrême technicité des questions en jeu, cette multiplicité d’échelles et d’acteurs tend à brouiller les cartes des débats environnementaux. Le changement climatique, la protection de la biodiversité ou la désertification constituent autant d’exemples pour lesquels l’identification des causes et des solutions présente une grande complexité scientifique et technique...

  10. The influence of surface microstructure and chemical composition on corrosion behaviour in fuel-grade bio-ethanol of low-alloy steel modified by plasma nitro-carburizing and post-oxidizing

    Science.gov (United States)

    Boniatti, Rosiana; Bandeira, Aline L.; Crespi, Ângela E.; Aguzzoli, Cesar; Baumvol, Israel J. R.; Figueroa, Carlos A.

    2013-09-01

    The interaction of bio-ethanol on steel surfaces modified by plasma-assisted diffusion technologies is studied for the first time. The influence of surface microstructure and chemical composition on corrosion behaviour of AISI 4140 low-alloy steel in fuel-grade bio-ethanol was investigated. The steel surfaces were modified by plasma nitro-carburizing followed plasma oxidizing. X-ray diffraction, scanning electron microscopy, optical microscopy, X-ray dispersive spectroscopy, and glow-discharge optical emission spectroscopy were used to characterize the modified surface before and after immersion tests in bio-ethanol up to 77 days. The main corrosion mechanism is pit formation. The pit density and pit size were measured in order to quantify the corrosion resistance which was found to depend more strongly on microstructure and morphology of the oxide layer than on its thickness. The best corrosion protection was observed for samples post-oxidized at 480 °C and 90 min.

  11. Friction and wear properties of double glow plasma carburized layer of Ti2AlNb base O phase alloy%Ti2AlNb基O相合金双辉等离子渗碳层摩擦磨损性能

    Institute of Scientific and Technical Information of China (English)

    杨晶晶; 缪强; 梁文萍; 李龙; 任蓓蕾; 朱丹阳

    2013-01-01

    Double glow plasma carburized layer was carried out on the surface of Ti2AlNb base O phase alloy to improve its wear-resistance.The microstructure,element distribution,phases,hardness and wear resistance of the carburized layer were analyzed by SEM,EDS,XRD,hardness tester and friction wear testing machine.The results show that a carburized layer is formed about 30 μn,and surface hardness of the carburized layer is 1053-V0.1 and it gradually decreases along the depth.The general friction coefficient of the carhnrized layer and matrix is 0.4 and 0.75,respectively.The specific wear rate of carburized layer is 1/17 of the matrix.The wear resistance of Ti2AlNb base O phase alloy is improved significantly by plasma carburizing.%利用双层辉光等离子表面合金化技术在Ti2AlNb基O相合金表面进行渗碳处理,采用SEM、EDS、XRD、硬度仪及摩擦磨损试验机对其组织成分、元素分布、相组成、硬度及耐磨性能进行研究.结果表明,在Ti2AlNb基O相合金表面形成了约30μm的渗碳层,渗碳层表面硬度为1053 HV0.1,且硬度随渗层厚度梯度递减.渗碳层和基体平均摩擦因数分别为0.4和0.75,渗碳层比磨损率为基体比磨损率的1/17.双层辉光等离子渗碳技术明显提高了Ti2A1Nb基O相合金的耐磨性.

  12. 20CrMnMo钢渗碳齿轮磨削裂纹成因分析%Causes Analysis on Grinding Cracks of 20CrMnMo Steel Carburized Gears

    Institute of Scientific and Technical Information of China (English)

    孙胜伟; 宋亚虎; 刘铁山; 史向阳; 赵学谦

    2016-01-01

    采用化学成分分析、金相分析、显微硬度测试以及残余应力测定等方法对某 2 0 CrMnMo钢渗碳齿轮磨削裂纹产生原因进行了分析.结果表明:该齿轮产生磨削裂纹主要是由于磨削过程中表面产生严重的二次淬火烧伤和回火烧伤,二次淬火烧伤的次表面及边缘回火烧伤区硬度大幅下降及表面受拉应力,两者共同作用下产生了磨削裂纹;另外,渗碳层中存在针状马氏体和大量残余奥氏体,增加了齿轮磨削开裂的敏感性,这是齿轮产生磨削裂纹的另一个重要原因.%The forming reasons for grinding cracks of 20CrMnMo steel carburized gears were analyzed by means of chemical composition analysis,metallographic examination,microhardness test and residual stress test. The results show that the main reasons for the grinding cracks were secondary quenching burn and tempering burn on the gear surface during grinding.Grinding cracks were caused by the combined effects of serious decline in hardness and surface tensile stress at the subsurface of the secondary quenching burn area and the edge tempering burn area.Besides,the grinding cracking sensitivity was increased due to the acicular martensite and massive retained austenite existing in the carburized layer,which was also an important reason for the grinding cracks.

  13. 12CrNi3A凸轮轴渗碳激光强化复合处理工艺%The Intensification and Recombination Treatment of Carburization Laser of Cam Shaft 12CrNi3A

    Institute of Scientific and Technical Information of China (English)

    胡佳英

    2001-01-01

    he technique for the intensification and recombination treatment of carburization laser of cam shaft 12CrNi3A have been studied in this paper.The tests results show that,with using the carburization technique to increase the carbon density of surface and through the reasonable and effective technology of laser quenching treatment an ideal and uniform harden quench surfaceis obtained.The hardness of surface has been strengthened.The wear resistance and fatigue strength resistance of cam shaft has been enhanced.The problem of abrasive failure of cam shaft has also been resolved. It is a new attempt to develop and apply the technology of laser surface heat treating.%对12CrNi3A凸轮轴渗碳激光强化复合处理进行了研究。研究结果表明,采取表面渗碳工艺增加表层的碳浓度,并通过采用合理有效的激光淬火处理工艺,获得理想的淬硬层分布,提高了表层的硬度,增强了凸轮轴表面的耐磨性和抗疲劳强度,解决了凸轮轴磨损失效问题,是开发和应用激光表面热处理技术的一个新的尝试。

  14. Innovations en vaccinologie: enjeux et perspectives pour l’Afrique

    Science.gov (United States)

    Diop, Doudou; Sanicas, Melvin

    2017-01-01

    La vaccination est incontestablement l’une des interventions de santé publique les plus efficaces et les plus rentables qui soient. Les vaccins continuent de révolutionner notre capacité à prévenir les maladies et à améliorer la santé. Avec toutes les avancées technologiques, nous sommes en mesure d’étendre les avantages des vaccins à plus de gens et de fournir une meilleure protection contre les maladies infectieuses mortelles. Toutefois, avec le développement incessant de nouvelles souches microbiennes à travers le monde, la recherche en vaccinologie se doit d’innover continuellement. D’énormes progrès ont été réalisés pour améliorer la couverture vaccinale et introduire de nouveaux vaccins en Afrique. De nouveaux types de vaccins associés à des outils de vectorisation, d’administration et de délivrance spécifiques mais aussi des adjuvants susceptibles de moduler finement la réponse immunitaire sont attendus dans le futur. En Afrique, il est nécessaire de développer une approche régionale afin de répondre efficacement aux nombreux défis. Une meilleure information, la formation des personnels de santé en vaccinologie et des recherches bien ciblées sont les clés des futurs accomplissements dans le domaine. PMID:28690749

  15. Le théâtre dans la ville: pour une histoire sociale des représentations dramatiques.

    NARCIS (Netherlands)

    Bonicel, M.; Lavéant, K.

    2010-01-01

    Pour évaluer à sa juste mesure la place et l’influence du théâtre comme phénomène social à la fin du Moyen Âge, il faut opérer un retour aux sources historiques, encore trop rarement étudiées pour cerner les cultures dramatiques. Quelles sources sont disponibles pour contribuer à l’histoire du théât

  16. Preparation of semi-solid aluminum alloy slurry poured through a water-cooled serpentine channel

    Science.gov (United States)

    Chen, Zheng-Zhou; Mao, Wei-Min; Wu, Zong-Chuang

    2012-01-01

    A water-cooled serpentine channel pouring process was invented to produce semi-solid A356 aluminum alloy slurry for rheocasting, and the effects of pouring temperature and circulating cooling water flux on the microstructure of the slurry were investigated. The results show that at the pouring temperature of 640-680°C and the circulating cooling water flux of 0.9 m3/h, the semi-solid A356 aluminum alloy slurry with spherical primary α(Al) grains can be obtained, whose shape factors are between 0.78 and 0.86 and the grain diameter can reach 48-68 μm. When the pouring temperatures are at 660-680°C, only a very thin solidified shell remains inside the serpentine channel and can be removed easily. When the serpentine channel is cooled with circulating water, the microstructure of the semi-solid slurry can be improved, and the serpentine channel is quickly cooled to room temperature after the completion of one pouring. In terms of the productivity of the special equipment, the water-cooled serpentine channel is economical and efficient.

  17. Dispositifs semi-conducteurs pour biodetection photonique et imagerie hyperspectrale

    Science.gov (United States)

    Lepage, Dominic

    La creation d'un microsysteme d'analyse biochimique, capable de livrer des diagnostics preliminaires sur la quantification d'elements pathogenes, est un defi multidisciplinaire ayant un impact potentiel important sur la majorite des activites humaines en sante et securite. En effet, un dispositif integre, peu dispendieux et livrant des resultats facilement interpretables, permettrait une vulgarisation des capacites de biodetection a travers differents domaines d'applications societaires et industriels. Le present document se concentre sur l'integration monolithique d'une methode de biocaracterisation dans le but de generer un transducteur miniaturise et efficace, element central d'un microsysteme de detection. Le projet de recherche ici presente vise l'etude de l'applicabilite d'un capteur plasmonique integre par l'entremise de nanostructures semi-conductrices aux proprietes quantiques et luminescentes. L'approche presentee est globale; c'est-a-dire qu'on vise a repondre aux questions fondamentales impliquant la comprehension des phenomenes photoniques, le developpement et la fabrication des dispositifs, les methodes de caracterisations possibles ainsi que l'application d'un transducteur SPR integre a la biodetection. En d'autres termes : dans quelles circonstances et comment un transducteur plasmonique integre doit-il etre realise pour l'application a la detection delocalisee d'elements pathogenes? Dans le but d'engendrer un instrument simple a l'echelle de l'usager, l'integration de la connaissance a l'echelle du design est donc effectuee. Ainsi, des capteurs plasmoniques monolithiques sont concus a l'aide de modeles theoriques ici presentes. Un instrument de mesure hyperspectrale conjuguee permettant de cartographier directement la relation de dispersion des plasmons diffractes a ete construit et teste. Cet instrument est employe a la cartographie d'elements de diffusion. Finalement, une demonstration du fonctionnement du dispositif, appliquee a la

  18. La renaissance du temps pour en finir avec la crise de la physique

    CERN Document Server

    Smolin, Lee

    2014-01-01

    La question du Temps est au coeur de toutes les problématiques scientifiques, de la cosmologie à la mécanique quantique. L’un des plus grands physiciens d’aujourd’hui, Lee Smolin, expose sa conception du Temps et ses implications sur la perception de notre environnement. Le Temps est-il une illusion qui cache une vérité éternelle, ou une réalité physique de notre Univers ? Lee Smolin opte pour la réalité du Temps, s’opposant en cela à la majorité des penseurs, physiciens ou philosophes, inspirés pour les uns par la théorie de la Relativité d’Einstein et pour les autres par les idées platoniciennes.

  19. Une plate-forme collaborative pour le développement professionnel des enseignants

    OpenAIRE

    Condamines, Thierry

    2011-01-01

    Le présent document propose un modèle de plate-forme pour le développement professionnel des enseignants. A partir d’une étude d’échanges entre enseignants sur des forums, nous examinons deux facettes de l'échange des connaissances, le partage d’expériences (pratiques usuelles) et les échanges pour résoudre un problème. Pour les pratiques usuelles d'enseignement nous utilisons un paradigme tâche/méthode où l’enseignant est amené à décrire les tâches qu’il réalise et la méthode qu’il utilise p...

  20. Toxicite des Elements Metalliques Dissous pour les Larves d'Organismes Marins: Donnees Bibliographiques.

    OpenAIRE

    Deslous-paoli, Jean-marc

    1981-01-01

    Une synthèse bibliographique sur la toxicité des éléments métalliques dissous pour des larves d'organismes marins, et plus particulièrement pour des larves de bivalves d'intérêt commercial, a été réalisée pour dix métaux. Par ordre de toxicité, ce sont les sels organiques d'étain, le mercure, l'argent, le cuivre, le zinc, le nickel, le plomb, le cadmium, le chrome et le manganèse. D'autre part, des problèmes de synergie entre métaux, température et salinité ont été abordés, ainsi que l'action...

  1. Determination of Time and Temperature Profiles in a Poured Earth Heat Transfer Process

    Directory of Open Access Journals (Sweden)

    Edgardo Jonathan Suarez-Dominguez

    2015-01-01

    Full Text Available Poured earth is a current alternative in architecture that could provide a solution for building in places with low -income populations because it uses earth located in the surrounding medium. There are several characteristics of the material that must be studied, including thermal conductivity, mainly atregions with extreme climates due to intervening in comfort levels of users. Because of this it is necessary to have mathematical models to predict the heat flux temperature and in turn along poured earth elements for further design. In this paper a non-stationary model for heat flow in a poured earth wall is proposed to describe non stationary flux in it. It was found that the model created engages over 95% for more representative case found at Mexico.

  2. Enhanced wear and fatigue properties of Ti-6Al-4V alloy modified by plasma carburizing/CrN coating%通过等离子渗碳/CrN覆层改性处理提高Ti-6Al-4V合金的耐磨性和抗疲劳特性

    Institute of Scientific and Technical Information of China (English)

    魏明镛

    2005-01-01

    In this study, a newly developed duplex coating method incorporating plasma carburization and CrN coating was applied to Ti-6Al-4V and its effects on the wear resistance and fatigue life were investigated. The carburized layer with approximately150 μm in depth and CrN coating film with 7.5μm in thickness were formed after duplex coating. Hard carbide particles such as TiC And V4 C3 were formed in the carburized layer. XRD diffraction pattern analysis revealed that CrN film had predominant [111] and [200] textures. The hardness (Hv) was significantly improved up to about 1960 after duplex coating while the hardness value of original Ti-6Al-4V was 402. The threshold load for the modification and/or failure of CrN coating was measured to be 32 N using the acoustic emission technique. The wear resistance and fatigue life of duplex coated Ti-6Al-4V improved significantly compared to those of un-treated specimen. The enhanced wear resistance can be attributed to the excellent adhesion and improved hardness of CrN coating film for the duplex coated Ti-6Al-4V. The initiation of fatigue cracks is likely to be retarded by the presence of hard and strong layers on the surface, resulting in the enhanced fatigue life.

  3. Un avenir ouvert pour une sociologie revisitée

    Directory of Open Access Journals (Sweden)

    Liliane Voyé

    2012-05-01

    Full Text Available Si l’on peut louer le souci de réflexivité qui anime la sociologie, il convient toutefois de dépasser ce stade du questionnement pour arriver à développer une sociologie moins inquiète d’elle-même. Les raisons de ce malaise sont diverses. Outre l’absence d’accord « sur un socle élémentaire de compétences exigibles » (François Dubet et Alain Caillé, la spécificité de son champ et de ses apports, comparée, par exemple, à l’histoire ou à la géographie, serait aussi une exigence importante, dont la rencontre la rendrait moins fragile. La question des méthodes qu’elle emploie mériterait également l’attention car celles-ci peuvent pécher par leurs faiblesses mais aussi parfois par leurs excès. L’objet même que se donne la sociologie appelle lui aussi une réflexion : la sociologie n’est pas du travail social frotté de science. Pourquoi dès lors privilégier l’étude des « problèmes sociaux » au sens courant du terme et ne pas s’intéresser aussi aux populations sans problème ou tout au moins se considérant comme telles ? Comme en médecine, les personnes saines aident à comprendre les maladies. À une époque où les changements se multiplient dans tous les domaines, la sociologie doit s’atteler à peaufiner sa conceptualisation et à repenser ses paradigmes, pour assumer pleinement son rôle social.An Open Future for a Revisited SociologyIf we can praise the concern for reflexivity that drives sociology, it should however go beyond the stage of questioning in order to develop a sociology that is less worried about itself. The reasons for this discomfort are various. Besides the lack of agreement « on the basis of elementary required skills » (François Dubet et Alain Caillé, the specificity of its field and its contributions, compared for example to history or geography, should also be an important requirement whose meeting would make it less fragile. The question of its methods

  4. Le partenariat en recherche: un véhicule pour atteindre les plus hauts sommets.

    Science.gov (United States)

    Gélinas, Isabelle

    2016-10-01

    Les partenariats en ergothérapie entre les praticiens et les chercheurs sont importants pour produire des connaissances pertinentes pour la pratique clinique et pour favoriser la pratique fondée sur les données probantes au sein de la profession. BUT: Dans ce discours Muriel Driver, l'auteure discute des raisons pour lesquelles nous devons favoriser la participation des praticiens à la recherche et elle examine les conditions essentielles à la réussite des partenariats de recherche en collaboration. QUESTIONS CLÉS: Les partenariats de collaboration peuvent réduire les obstacles empêchant les praticiens de participer à la recherche et permettre de veiller à ce que les initiatives de recherche soient plus pertinentes pour la pratique clinique. Les facteurs clés pour établir et maintenir des partenariats significatifs sont la présence de conditions préalables et favorables au partenariat en lien avec le contexte, de même que l'utilisation de principes directeurs axés sur la vision, les valeurs, la confiance, la communication, le partage du pouvoir et les interactions. CONSÉQUENCES: Plusieurs des facteurs identifiés comme étant favorables à la réussite d'un partenariat de collaboration correspondent aux rôles fondamentaux des ergothérapeutes et témoignent de nos valeurs professionnelles. La prise en compte de ces facteurs lors de l'établissement de collaborations de recherche permettrait d'accroître les probabilités de réussite. © CAOT 2016.

  5. Penser les métropoles pour les « individus » ?

    Directory of Open Access Journals (Sweden)

    Marc Dumont

    2006-03-01

    Full Text Available Les instruments dont on dispose aujourd’hui pour décrire et expliquer les réalités métropolitaines contemporaines ne sont pas entièrement satisfaisants : ils ne permettent pas toujours d’identifier les vraies questions qui se présentent à ceux qui produisent la ville. Partant de ce constat, le sociologue Alain Bourdin synthétise dans son nouvel essai des réflexions issues de sa pratique de recherche et de dialogue avec le monde des institutions, pour y proposer une lecture de la ...

  6. Modèles de choix discrets pour la reconnaissance des expressions faciales statiques

    OpenAIRE

    Danalet, Antonin

    2007-01-01

    Ce projet de semestre présente l’utilisation des modèles de choix discret pour construire un modèle de perception des expressions faciales statiques potentiellement utilisable pour la reconnaissance et la classification de ces expressions. La description de ces expressions s’inspire du système Facial Action Coding System (FACS) de Paul Ekman, basé sur une analyse anatomique de l’action faciale. L’ensemble de choix contient 6 expressions faciales universelles plus l’expression neutre. Chaque a...

  7. STUDI PERBANDINGAN PERFORMANCE ALGORITMA HEURISTIK POUR TERHADAP MIXED INTEGER PROGRAMMING DALAM MENYELESAIKAN PENJADWALAN FLOWSHOP

    Directory of Open Access Journals (Sweden)

    Tessa Vanina Soetanto

    2004-01-01

    Full Text Available This paper presents a study about new heuristic algorithm performance compared to Mixed Integer Programming (MIP method in solving flowshop scheduling problem to reach minimum makespan. Performance appraisal is based on Efficiency Index (EI, Relative Error (RE and Elapsed Runtime. Abstract in Bahasa Indonesia : Makalah ini menyajikan penelitian tentang performance algoritma heuristik Pour terhadap metode Mixed Integer Programming (MIP dalam menyelesaikan masalah penjadwalan flowshop dengan tujuan meminimalkan makespan. Penilaian performance dilakukan berdasarkan nilai Efficiency Index (EI, Relative Error (RE dan Elapsed Runtime. Kata kunci: flowshop, makespan, algoritma heuristik Pour, Mixed Integer Programming.

  8. L'action des Parcs Naturels Régionaux pour un tourisme durable

    OpenAIRE

    Marsat, J.B.

    2014-01-01

    / Les Parcs naturels régionaux français agissent pour le développement durable y compris dans le domaine du tourisme, ce qui met en jeu les acteurs des sphères touristique, environnementale, et territoriale. L'analyse part de l'autonomie stratégique des PNR et rend compte de leurs options : s'engager plus ou moins dans l'action pour le tourisme, recourir aux outils comme le marquage des prestations (marque parc), et ou la mise en réseau des prestataires. La Charte du tourisme durable dans les...

  9. Application du système immunitaire artificiel pour la reconnaissance des chiffres

    OpenAIRE

    Khelil, Hiba; Benyettou, Abdelkader; Belaïd, Abdel

    2008-01-01

    International audience; La reconnaissance automatique de l'écriture occupe un espace important dans la recherche scientifique car elle offre une facilité d'utilisation dans différents domaines d'application : domaine bancaire, postal, le e-commerce... De nombreuses méthodes ont été utilisées pour la reconnaissance d'écriture, dans cet article nous présenterons des méthodes inspirées du système immunitaire naturel que nous appliquerons pour la reconnaissance des chiffres.Des résultats satisfai...

  10. Les véhicules électriques pour le transport de fret urbain

    OpenAIRE

    Eléonora MORGANTI; Dablanc, Laetitia

    2013-01-01

    Le transport routier constitue le mode dominant pour le transport de marchandises en ville, avec en moyenne 90% du tonnage de marchandises transporté par la route. La plupart de ces opérations sont réalisées par des camionnettes et des fourgons diesel et provoquent des externalités négatives telles que la congestion, la pollution de l'air et le bruit. Ces dernières années, les administrations publiques ont défini des politiques pour encourager les opérateurs de transport urbain à remplacer le...

  11. LE RISQUE DE LIQUIDITE POUR UNE BANQUE ISLAMIQUE : ENJEUX ET GESTION

    OpenAIRE

    KHOUTEM, BEN JEDIDIA; MOULDI, JLASSI

    2013-01-01

    La liquidité est une question cruciale pour les banques islamiques. L’enjeu de la liquidité et sa gestion présentent des défis pour ces banques. D’abord, les banques islamiques sont exposées au risque de liquidité3 dans un contexte de faiblesses structurelles du système financier qui pèsent sur leur solvabilité et leur liquidité (Sundararajan and Errico, 2002 ; Salman, 2004 ; El-Hawary et al, 2007 ; Akkizidis et Khandelwal, 2008, Al-Muharrami et Hardy, 2013). En fait, la plupart des banques i...

  12. Analysis Of The Sludge Batch 7b (Macrobatch 9) DWPF Pour Stream Glass Sample

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, F. C.; Crawford, C. L.; Pareizs, J. M.

    2013-11-18

    The Defense Waste Processing Facility (DWPF) began processing Sludge Batch 7b (SB7b), also referred to as Macrobatch 9 (MB9), in January 2012. SB7b is a blend of the heel of Tank 40 from Sludge Batch 7a (SB7a) and the SB7b material that was transferred to Tank 40 from Tank 51. SB7b was processed using Frit 418. During processing of each sludge batch, the DWPF is required to take at least one glass sample to meet the objectives of the Glass Product Control Program (GPCP), which is governed by the DWPF Waste Form Compliance Plan, and to complete the necessary Production Records so that the final glass product may be disposed of at a Federal Repository. Two pour stream glass samples were collected while processing SB7b. The samples were transferred to the Savannah River National Laboratory (SRNL) where one was analyzed and the other was archived. The following conclusions were drawn from the analytical results provided in this report: The sum of oxides for the official SB7b pour stream glass is within the Product Composition Control System (PCCS) limits (95-105 wt%); The average calculated Waste Dilution Factor (WDF) for SB7b is 2.3. In general, the measured radionuclide content of the official SB7b pour stream glass is in good agreement with the calculated values from the Tank 40 dried sludge results from the SB7b Waste Acceptance Program Specification (WAPS) sample; As in previous pour stream samples, ruthenium and rhodium inclusions were detected by Scanning Electron Microscopy-Electron Dispersive Spectroscopy (SEM-EDS) in the SB7b pour stream sample; The Product Consistency Test (PCT) results indicate that the official SB7b pour stream glass meets the waste acceptance criteria for durability with a normalized boron release of 0.8 g/L, which is an order of magnitude less than the Environmental Assessment (EA) glass; The measured density of the SB7b pour stream glass was 2.70 g/cm{sup 3}; The Fe{sup 2+}/ΣFe ratio of the SB7b pour stream samples was 0.07.

  13. Community Cleaning Services : une alliance hybride pour l'assainissement urbain

    Directory of Open Access Journals (Sweden)

    Tatiana Thieme

    2012-01-01

    Full Text Available Cet article vise à analyser les trois phases de développement de l’initiative Community Cleaning Service, soutenu par SC Johnson dans les bidonvilles de Nairorib. Après le lancement du BoP Protocol, puis le développement d’un système de micro-franchise, CCS est devenue une entreprise sociale à but non lucratif. On observe dans ces trois phases les relations complexes qui se tissent, ausi bien pour l’entreprise que pour les micro-franchisés, entre aide et marché.

  14. Active Control of Engine Dynamics (Le controle actif pour la dynamique des moteurs)

    Science.gov (United States)

    2002-11-01

    actif , associé à des capteurs sans fil et à des actionneurs répartis, est appelé à jouer un rôle habilitant dans le développement futur des...SEINE CEDEX, FRANCE RTO EDUCATIONAL NOTES 20 Active Control of Engine Dynamics (Le contrôle actif pour la dynamique des moteurs) The material in this...Control of Engine Dynamics (Le contrôle actif pour la dynamique des moteurs) The material in this publication was assembled to Support a RTO/VKI

  15. ANALYSIS OF DWPF SLUDGE BATCH 7A (MACROBATCH 8) POUR STREAM SAMPLES

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, F.

    2012-05-01

    The Defense Waste Processing Facility (DWPF) began processing Sludge Batch 7a (SB7a), also referred to as Macrobatch 8 (MB8), in June 2011. SB7a is a blend of the heel of Tank 40 from Sludge Batch 6 (SB6) and the SB7a material that was transferred to Tank 40 from Tank 51. SB7a was processed using Frit 418. During processing of each sludge batch, the DWPF is required to take at least one glass sample to meet the objectives of the Glass Product Control Program (GPCP), which is governed by the DWPF Waste Compliance Plan, and to complete the necessary Production Records so that the final glass product may be disposed of at a Federal Repository. Three pour stream glass samples and two Melter Feed Tank (MFT) slurry samples were collected while processing SB7a. These additional samples were taken during SB7a to understand the impact of antifoam and the melter bubblers on glass redox chemistry. The samples were transferred to the Savannah River National Laboratory (SRNL) where they were analyzed. The following conclusions were drawn from the analytical results provided in this report: (1) The sum of oxides for the official SB7a pour stream glass is within the Product Composition Control System (PCCS) limits (95-105 wt%). (2) The average calculated Waste Dilution Factor (WDF) for SB7a is 2.3. In general, the measured radionuclide content of the official SB7a pour stream glass is in good agreement with the calculated values from the Tank 40 dried sludge results from the SB7a Waste Acceptance Program Specification (WAPS) sample. (3) As in previous pour stream samples, ruthenium and rhodium inclusions were detected by Scanning Electron Microscopy-Electron Dispersive Spectroscopy (SEM-EDS) in the official SB7a pour stream sample. (4) The Product Consistency Test (PCT) results indicate that the official SB7a pour stream glass meets the waste acceptance criteria for durability with a normalized boron release of 0.64 g/L, which is an order of magnitude less than the Environmental

  16. Analyse du développement du tourisme pour tous dans le Val d’Anniviers

    OpenAIRE

    Rossier, Sandrine; Margot-Cattin, Pierre

    2015-01-01

    Cette étude vise à offrir une image actuelle du développement du tourisme pour tous dans le Val d’Anniviers. Cette activité touristique permet aux destinations de proposer leur offre à un public très large. S’adressant tout d’abord à une clientèle en situation de handicap, le tourisme pour tous peut également bénéficier à toute personne ayant des besoins particuliers en termes d’accessibilité. Son implantation dans une région touristique exige de franchir un certain nombre de barrières. Quell...

  17. Des terres pour l’agro-industrie internationale ? Un dilemme pour la politique foncière malgache

    Directory of Open Access Journals (Sweden)

    André Teyssier

    2010-02-01

    Full Text Available Les manœuvres d’appropriation foncière à grande échelle tentées fin 2008 par les entreprises Daewoo Logistics et Varun International, largement relayées par les médias et dénoncées par diverses organisations, ont participé à la déstabilisation du gouvernement Ravalomanana. Les montages de ces deux grands projets agro-industriels ont suivi des trajectoires différentes, l’un choisissant de contrôler d’immenses superficies par bail emphytéotique, l’autre privilégiant des formes de contractualisation de la production, mais tous deux ont été abandonnés face à des mouvements de contestation basés sur l’inaliénabilité de la « terre des ancêtres ». Le rejet de ces projets d’envergure encore inédite et en partie tournés vers des cultures d’exportation est compréhensible tant les retombées économiques et sociales paraissaient incertaines. Madagascar ne saurait néanmoins se priver d’investissements dans le secteur agricole, mais des choix de développement, orientés par une meilleure connaissance des processus en cours, restent à opérer en toute transparence, afin de combiner développement de l’agro-business et promotion des exploitations familiales. Pour l’instant, ces incertitudes marquent une politique foncière qui, même rénovée, hésite entre la formalisation de droits sur le sol au profit du plus grand nombre grâce à une décentralisation de la gestion foncière et l’octroi de vastes espaces à des firmes internationales suivant des procédures accélérées.

  18. NooJ, un outil TAL pour l'enseignement des langues. Application pour l'étude de la morphologie lexicale en FLE

    Directory of Open Access Journals (Sweden)

    Max Silberztein

    2005-12-01

    Full Text Available NooJ est un système de traitement de corpus – reprenant et améliorant les fonctionnalités d'INTEX – conçu pour l'enseignement des langues et de la linguistique. NooJ intègre des outils de traitement automatique du langage qui offrent à l'enseignant des possibilités de traiter un corpus, et des procédures de recherche, de test, et d'entraînement pour l'étudiant. Nous présentons ici un exemple d'application de NooJ à l'enseignement du français langue étrangère, qui reprend quelques activités sur l'étude de la morphologie lexicale.

  19. High Power Electric Propulsion System for NEP (systemes propulsifs electriques de forte puissance pour propulsion nucleo-electrique)

    Science.gov (United States)

    2005-07-13

    1 SYSTEMES PROPULSIFS ELECTRIQUES DE FORTE PUISSANCE POUR PROPULSION NUCLEO- ELECTRIQUE HIGH POWER ELECTRIC PROPULSION SYSTEM FOR NEP...Christophe R. KOPPEL*, Olivier DUCHEMIN*, Dominique VALENTIAN** Snecma, Groupe Safran, Division Moteurs Spatiaux, *Site de Villaroche Nord...REPORT DATE 13 JUL 2005 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Systemes Propulsifs Electriques De Forte Puissance Pour

  20. Is the glass half full or half empty? How to reverse the effect of glass elongation on the volume poured.

    Directory of Open Access Journals (Sweden)

    Simone R Caljouw

    Full Text Available To reduce the volume of drinks and the risk of overconsumption, health professionals recommend the use of tall skinny instead of short wide glasses. Yet the results of the present study contradict this health advice. Participants who generously filled up a glass with lemonade served 9% more in tall narrow compared with short wide glasses (p<0.05. In addition, when pouring a small amount (i.e., a shot, participants poured 3% more in a short wide than in a tall narrow glass (p<0.05. Elongation may bias the perceived volume that is poured but also the perceived volume of the free space in the glass. We hypothesised that shifting attention from the bottom to the brim of the glass when filling it close to capacity might reverse the glass elongation effect on the quantity poured. This hypothesis was tested, by investigating two pouring tasks that differed in the required focus of attention. When the instruction was to match a reference volume, participants poured more liquid in the short wide compared with the tall narrow glass (p<0.05. The effect of glass elongation on poured volume was the opposite when the instruction was to leave space in the glasses for the reference volume. It seems likely that task and individual factors affect the pourer's viewing strategy and thus may determine the direction of the glass elongation effect on the volume poured.

  1. Europe CERN recherche - Pret de 300 millions d'euros de la BEI pour l'accelerateur de particules

    CERN Multimedia

    2002-01-01

    "La Banque europeenne d'investissement (BEI) va preter 300 millions d'euros pour financer la phase finale de la construction du grand accelerateur de particules LHC (Large Hadron Collider) du CERN, a indique jeudi l'organisation europeenne pour la recherche nucleaire" (1/2 page).

  2. Modeling of mould cavity filling process with cast iron in Lost Foam method Part 2. Mathematical model – Pouring rate

    Directory of Open Access Journals (Sweden)

    T. Pacyniak

    2008-08-01

    Full Text Available In this work pouring rate equation for cast iron in lost foam process was shown. For description of this phenomenon the motion dynamic equation was used. Pressure affecting the liquid cast iron surface was described using Bernoulli formulae. Numerical simulation results were analyzed with respect to permeability, refractory coating thickness and foamed polystyrene pattern density influence on pouring rate.

  3. Guide pour la rédaction de cahiers des charges pour la sous-traitance en mécano-soudage

    CERN Document Server

    Cheminat, Olivier

    2016-01-01

    Ce rapport est principalement dédié aux rédacteurs de cahiers des charges lors de sous-traitance en soudage. Le choix de faire sous-traiter une fabrication et le choix du sous-traitant revêtent une triple dimension technique, économique et stratégique. Un sous-traitant n'est pas un simple fournisseur ; il est un véritable partenaire technique pour le donneur d'ordre qui lui confie la réalisation d'un produit qu'il a lui-même conçu. La sous-traitance nécessite alors, outre un audit préalable du partenaire, un suivi en continu, à distance, et une communication entre le donneur d'ordre et le sous-traitant. Le cahier des charges est un des éléments de cette communication. C'est un outil essentiel, notamment lorsque le marché est soumis à des normes, imposées par contrat entre le donneur d'ordre et le sous-traitant. Ce présent document est un guide pour la rédaction du document de consultation, afin d'être le plus précis et exhaustif possible, mais il ne saurait être utilisé pour établi...

  4. Mode-bifurcation upon pouring water into a cup that depends on the shape of the cup

    Science.gov (United States)

    Nakata, Satoshi; Yamada, Akiko; Kitahata, Hiroyuki

    2005-05-01

    Mode-bifurcation that included hysteresis was investigated when water was poured into a cup via a water faucet. Three modes, i.e., accumulation flow (mode I), scattering flow (mode II), and open and shut oscillatory flow (mode III), could be produced by laterally changing the distance between the center of the cup and the landing point of water poured at a constant flow rate. Hysteresis in mode-bifurcation was observed when the distance was changed depending on the initial location of the water poured into the cup. Pendulum flow was also observed when water was poured into a shallow cell. The essential features of this mode-switching were reproduced by a numerical calculation as a function of the landing point of the poured water using two-variable (the size of the water hollow and the pressure on the water surface) differential equations that included the nature of reversed flow.

  5. EVALUATION OF THE IMPACT OF THIN POURS ON SALTSTONE PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Cozzi, A.; Langton, C.; Fox, K.

    2012-10-02

    The proposed Saltstone Disposal Unit 6 (SDU6) is a larger structure than the SDU4 cells and larger than the disposal units (SDU2, SDU3, and SDU5) currently in use or under construction. The additional capacity provided by SDU6 is desired to reduce life cycle costs and support site accelerated closure goals. The larger size of the planned SDU6 could result in saltstone being placed in thinner lifts as the unit is filled. This study was performed to determine whether thinner layers of saltstone negatively impact the performance of the waste form. A larger number of cold joints could potentially result in increased drying, salt deposition, and surface oxidation. A matrix of samples was prepared to simulate thin pours ranging from 0.5 to 6 inches thick. Each sample was cured for at least 28 days prior to further characterization. Leachability results showed that there is no obvious impact of the number of grout layers on the Leachability Index values for Na and NO{sub 3}. The concentrations of Cr, NO{sub 2}, and C{sub 2}O{sub 4} were below detection limits for all of the leachates. No attempt was made to evaluate the oxidation of these samples since no measureable Cr was leached, although this would appear to indicate that Cr in the samples remained reduced for cold joints with surfaces exposed for approximately four days. The results of hydraulic conductivity measurements showed that the number of cold joints in the samples did not have a significant impact on the measured values for the vertical lift orientation (i.e., when the flow path is perpendicular to the cold joints). For the horizontal lift orientation (i.e., when the flow path is parallel to the cold joints), the number of cold joints in the samples also did not appear to have a significant impact on hydraulic conductivity. The measured hydraulic conductivity was faster when the flow path was parallel to the cold joints as compared to when the flow path was perpendicular to the cold joints. Percolation

  6. 缩短渗碳周期与强烈淬火相结合的节能热处理技术%Energy Savings Using a Combination of Carburizing Cycle Reduction and Intensive Quenching

    Institute of Scientific and Technical Information of China (English)

    Lauralice C. F. Canale; Eduardo Merheb; Jo(a)o C. Vendramim; George E. Totten

    2007-01-01

    在热处理行业,人们一直在探索降低生产成本、节约能源和减少环境污染的方法.汽车制造业在这方面将是大有作为的,其中包括:大幅度缩短渗碳时间,以节能和降低生产成本;开发新型淬火剂替代易燃、有毒的矿物油基淬火剂.采用非易燃的对环境友好的水基淬火剂进行强烈淬火(IQ)是达到这些目标的途径之一.此外,IQ还能使渗碳的扩散时间缩短50%或更多.本文论述了巴西圣保罗大学、巴西Combustol公司以及美国强烈淬火公司合作进行的采用一种强烈淬火工艺成功达到上述目标的研究成果.从长远看,这些成果对热处理工业将具有重要意义.%There is an ongoing interest in the heat treatment industry to identify methods of reducing production cost, energy consumption and to reduce environmental impact of heat treatment practices and materials. Automobile industry offers a number of opportunities in this regard including: reduction of substantial carburizing times which would result in substantial energy savings and reduction in production costs due to shorter processing times and the potential replacement of flammable and relatively toxic petroleum-based quenchants. One way of achieving these goals is to use intensive quenching processes (IQ) which utilize non-flammable and environmentally benign aqueous-based quenchants. Furthermore, IQ offers the potential of significantly reducing total carburizing diffusion times by 50%, or more. This paper will discuss the results of a collaborative study conducted by the University of Sao Paulo at Sao Carlos, Combustol, and Intensive Quenching Technologies to utilize an IQ process to successfully achieve the afore mentioned goals. These results are potentially of major importance to the heat treatment industry.

  7. Actualités en matière antique: pour Emmanuèle Baumgartner

    Directory of Open Access Journals (Sweden)

    Carlos Pérez Varela

    2007-04-01

    Full Text Available À propos de l’œuvre de Laurence Harf-Lancner, Laurence Mathey-Maille et Michelle Szkilnik (2006: Conter de Troie et d'Alexandre: pour Emmanuèle Baumgartner (Paris, Editions Presses Sorbonne Nouvelle, 308 pp., 12 pl., ISBN 2878543599.

  8. Quelques conditions pour une sémiotique de la cartographie

    Directory of Open Access Journals (Sweden)

    Gaëtan DESMARAIS

    1986-06-01

    Full Text Available La cartographie, satisfaisant aux cinq conditions empruntées à Hjelmslev et étudiées ici en détail pour rendre compte de sa structure, fonctionne bien comme un langage. On peut donc l'aborder selon les méthodes de la sémiologie.

  9. Procédés de production d'aliments non conventionnels pour porcs à ...

    African Journals Online (AJOL)

    SARAH

    30 juil. 2013 ... rendre plus disponible des aliments pour les animaux d'élevage, particulièrement les ... Processes of production of nonconventional food for pig containing mangoes residues and .... Le présent article décrit la mise au point.

  10. 54 Évaluation de la qualité des eaux souterraines pour l'utilisation ...

    African Journals Online (AJOL)

    AKA BOKO

    souterraine sont développées pour l'approvisionnement en eau potable, ..... Ecnologia de la intrusion de agua de mar en acuiferos costeros : paises .... des aquifères régionaux par la combinaison des SIG, de la géophysique et de la ...

  11. Topical (pour-on) ivermectin in the treatment of canine scabies.

    OpenAIRE

    Paradis, M.; de Jaham, C; Pagé, N

    1997-01-01

    The efficacy of a pour-on formulation of ivermectin at 500 micrograms/kg body weight applied on the dorsum on days 1 and 15 was evaluated in 90 dogs from a shelter, naturally infested with Sarcoptes scabiei. This very practical form of treatment was successful in eradicating scabies from this shelter.

  12. quelques elements pour un bilan d'un demi siecle de politiques ...

    African Journals Online (AJOL)

    Musette

    lecture prospective de la problématique agricole et rurale en Algérie. Pour le présent ... alimentaire ou encore de l'évolution des rendements et de l'exploi- ..... cultivables, la pratique des terres "au repos" concerne encore presque la moitié ...

  13. FORMATION 2005 Pour L'Afrique SURLA TECHNIQUE DES PETITES CENTRALES HYDRO-ELECTRIQUES

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    “Le stage de formation 2005 por l'Afrique sur la technique de petites centrales hydro-electrique”est subventionnte par le Gouvernement Chinois specialement pour les pays en voie de developpement,dans le cadre de l'aide aux pays en voie de developpement.Charge par le Ministere chinois du Commerce,

  14. Beethoven, Ludwig van: Concerto pour violon op. 61 / Jean-Michel Molkhou

    Index Scriptorium Estoniae

    Molkhou, Jean-Michel

    1997-01-01

    Uuest heliplaadist "Beethoven, Ludwig van: Concerto pour violon op. 61 (cadence Schnittke). Les 2 Romances op. 40 et 50. Orchestre Symphonique National d'Estonie, Arvo Volmer" Globe GLO 5155, distribution Talis (CD:153F). 1996. TT:1h 01'56"

  15. Le moteur Diesel et son carburant. Principaux problèmes et solutions potentielles Diesel Engines and Their Fuel. The Leading Problems and Potential Solutions

    Directory of Open Access Journals (Sweden)

    Eyzat P.

    2006-11-01

    Full Text Available Après avoir rappelé les tendances récentes françaises et européennes relatives au développement du moteur Diesel et à la demande en gazole, on examine les principales caractéristiques contraignantes : comportement à froid, indice de cétane, tendance à l'encrassement des injecteurs. On présente diverses techniques ou projets de procédure permettant de progresser dans une meilleure connaissance de certains incidents (blocage des filtres en hiver, accroissement des émissions de bruit et de polluants avec des injecteurs encrassés. On décrit enfin les possibilités et les contraintes du raffinage pour fournir un gazole susceptible de satisfaire les divers utilisateurs. L'emploi d'additifs et la distribution de deux qualités de gazole constituent des moyens d'action possibles. After reviewing recent French and European trends concerning the development of diesel engines and the demand for diesel oil, this article examines the leading constraints : cold behavior, cetane number, tendency of injector fouling. Different techniques or possible procedures are described for gaining a better understanding of various incidents (filter plugging in winter, increase in noise and pollutant emissions with fouled injectors. The article concludes by describing the possibilities and constraints of refining for supplying diesel oil capable of meeting the needs of different users. The use of additives and the distribution of two qualities of diesel oil are possible means of action.

  16. Clinical and parasitological evaluation of pour-on fluazuron and ivermectin for treating canine demodicosis

    Directory of Open Access Journals (Sweden)

    Clarissa P. Souza

    2014-11-01

    Full Text Available The objective of the study was to evaluate the efficacy of pour-on formulations of fluazuron and ivermectin in different therapeutic protocols for treatment of demodicosis by means of quantifying mites with skin scraping, histological and clinical evaluation in dogs. Eighteen dogs with skin scrapings positive for Demodex canis were evaluated, divided into three groups. All the animals were treated every 14 days, completing 6 treatments for each animal (days 0, 14, 28, 42, 56 and 70. In group 1, pour-on 2.5% fluazuron was used at the dose of 20mg/kg; in the group 2 pour-on 2.5% fluazuron at a dose of 20 mg/kg in association with pour-on 0.5% ivermectin at the dose of 0.6mg/kg; and in group 3, pour-on 0.5% ivermectin alone was used, at the dose of 0.6mg/kg. The treatment was evaluated and monitored through skin scrapings and clinical follow-up of the lesions every 14 days for 84 days, and through histopathological examination at the end of each treatment protocol. The success rate was defined as the percentage of dogs in each group that had negative skin scrapings after the treatment: this was 16.67% for group 1, and 50% for groups 2 and 3. The reduction in mite counts reached effectiveness of 67.66%, 88.99% and 84.29% for groups 1, 2 and 3 respectively. The Wilcoxon test showed that there was a significant difference between the number of mites before and after treatment in groups 2 and 3. The histopathological examination revealed that only group 1 showed no significant difference in the intensity of infestation between days 0 and 84. Clinically, there was no significant difference between the evaluation before and after treatment in the three groups. pour-on 2.5% fluazuron and pour-on 0.5% ivermectin were not effective for treating canine demodicosis, either in association or as single therapy, when applied every 14 days for a period of 70 days. Quantification of mites using skin scrapings and histological evaluation proved to be ineffective

  17. Transformation a Echelle Fixe et Groupe de Renormalisation pour les Objets Fractals et Multifractals

    Science.gov (United States)

    Tremblay, Real

    Dans un premier temps, la description mathematique des fractals et des multifractais est resumee. Une description de quelques-uns des principaux systemes ou apparaissent des spectres d'exposants multifractals est presentee. L'accent est mis sur deux archetypes, le modele de percolation et le modele de rupture dielectrique. Un modele original de cascade multifractale avec interactions inspire des modeles phenomenologiques de la turbulence est presente et son spectre d'exposants calcule analytiquement. Ce travail elargit la classe de modeles pour lesquels on connait le spectre d'exposants exactement. Dans la seconde partie, on trouve une analyse critique de la transformation a echelle fixe. Sont discutees plus particulierement les proprietes que doivent posseder les diagrammes de base pour obtenir une transformation invariante d'echelle. Les differentes hypotheses arbitraires de la theorie sont mises en evidence. L'une de ces hypotheses concerne le traitement auto-coherent des conditions aux frontieres. Considerant cette hypothese comme valable, la theorie utilise la distribution de trous dans un ensemble de Cantor aleatoire. Un calcul exact de cette distribution est donne ici. Enfin, en troisieme et dernier lieu, on retrouve une analyse exhaustive du probleme du crossover dans le modele de percolation avec une resistance non-nulle pour les liens normalement isolants. A l'aide du groupe de renormalisation de Migdal-Kadanoff, on montre qu'il existe un seul exposant de crossover et une seule longueur de coherence. D'autres longueurs de correlation peuvent etre definies, mais elles demeurent dans un rapport fixe le long des axes propres du groupe de renormalisation. La multifractalite est donc, pour ce modele et ceux qui peuvent etre formules de facon analogue, compatible avec l'existence d'une seule longueur de coherence. Ces resultats sont d'application directe pour les proprietes electriques des milieux desordonnes.

  18. Démarche pour le choix et/ou la conception d'un moyen de soudage par FSW

    OpenAIRE

    ZIMMER-CHEVRET, Sandra; LANGLOIS, Laurent; LAYE, Julien; Goussain, Jean-Claude; Martin, Patrick; Bigot, Régis

    2009-01-01

    National audience; Les travaux de recherches présentés concernent l'industrialisation du procédé de soudage par friction malaxage, également appelé Friction Stir Welding (FSW). L'objectif est de fournir des outils aux industriels pour choisir et qualifier une machine pour leurs applications de FSW. Cet article présente une méthodologie pour qualifier et / ou concevoir les moyens de soudage adaptés à une application donnée. La démarche de qualification repose sur l'étude géométrique des pièces...

  19. Discussion on the late poured band construction of architectural engineering%建筑工程后浇带施工探讨

    Institute of Scientific and Technical Information of China (English)

    郭计军

    2009-01-01

    The paper started from the late poured band function, the late poured band construction attentions were illustrated. The late poured hand construction measures were introduced from late poured band pouring time, cross section form and treating method, steel bar collection and protection, concrete .selection and pouring, follow plate erection and removal, therefore made the late poured band play role better.%从后浇带的作用出发,阐述了后浇带施工的注意事项,并从后浇带的浇筑时间、断面形式及处理方法、钢筋配置与防护、混凝土选料与浇筑、模板的支拆等方面介绍了后浇带的施工措施,从而使后浇带更好地发挥作用.

  20. ANALYSIS OF DWPF SLUDGE BATCH 6 (MACROBATCH 7) POUR STREAM GLASS SAMPLES

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, F.

    2012-01-20

    The Defense Waste Processing Facility (DWPF) began processing Sludge Batch 6 (SB6), also referred to as Macrobatch 7 (MB7), in June 2010. SB6 is a blend of the heel of Tank 40 from Sludge Batch 5 (SB5), H-Canyon Np transfers and SB6 that was transferred to Tank 40 from Tank 51.1 SB6 was processed using Frit 418. Sludge is received into the DWPF Chemical Processing Cell (CPC) and is processed through the Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator Tank (SME). The treated sludge slurry is then transferred to the Melter Feed Tank (MFT) and fed to the melter. During processing of each sludge batch, the DWPF is required to take at least one glass sample to meet the objectives of the Glass Product Control Program (GPCP) and to complete the necessary Production Records so that the final glass product may be disposed of at a Federal Repository. The DWPF requested various analyses of radioactive glass samples obtained from the melter pour stream during processing of SB6 as well as reduction/oxidation (REDOX) analysis of MFT samples to determine the impact of Argon bubbling. Sample analysis followed the Task Technical and Quality Assurance Plan (TTQAP) and an Analytical Study Plan (ASP). Four Pour Stream (PS) glass samples and two MFT slurry samples were delivered to the Savannah River National Laboratory (SRNL) from the DWPF. Table 1-1 lists the sample information for each pour stream glass sample. SB6 PS3 (S03472) was selected as the official pour stream sample for SB6 and full analysis was requested. This report details the visual observations of the as-received SB6 PS No.3 glass sample as well as results for the chemical composition, Product Consistency Test (PCT), radionuclide content, noble metals, and glass density. REDOX results will be provided for all four pour stream samples and vitrified samples of MFT-558 and MFT-568A. Where appropriate, data from other pour stream samples will be provided.

  1. Proposition d'élaboration d'un tableau de bord pour le service financier de la commune de Nyon

    OpenAIRE

    Araujo, Sara da Silva; Tuberosa, Jean

    2016-01-01

    De nos jours, la notion de chiffres est très présente, ce qui amène le désir de tout établissement à connaître les résultats de son activité en temps réel, afin de prendre des mesures correctrices pour atteindre les objectifs qu’elle s’est fixés. Pour cela la mise en place d’un outil est nécessaire, ma proposition pour répondre à ce besoin est le tableau de bord. Pour mettre en place cet outil, des analyses de l’environnement, de la stratégie et des risques sont nécessaires. De plus la défini...

  2. Effects of pouring temperature and slurry viscosity on heat transfer and surface roughness in lost foam casting

    Science.gov (United States)

    Shayganpour, A.; Idris, M. H.; Izman, S.; Farahany, S.

    2012-06-01

    The effects of pouring temperature and slurry viscosity in terms of heat transfer on surface roughness during lost foam casting (LFC) of LM6 alloy were investigated experimentally. Heat transfer of molten materials is an important factors to changes the microstructure which is considered in the present study. It is primarily dependent on the pouring temperature, casting thickness, mould material, mould temperature and surrounding medium. The pouring temperature changed from 700 to740°C and slurry viscosity altered from 20 to 36 sec. A full 2-level factorial design experimental technique was used to identify the significant factors that effect on surface roughness of castings. The results show that surface roughness improved by lower pouring temperature, whereas slurry viscosity has less influence on the quality of surface.

  3. Prokofiev: Cantate pour le 20e anniversaire de la revolution d'Octobre op. 74 / Pierre-E. Barbier

    Index Scriptorium Estoniae

    Barbier, Pierre-E.

    1992-01-01

    Uuest heliplaadist "Prokofiev: Cantate pour le 20e anniversaire de la revolution d'Octobre op. 74. La Fleur de pierre op. 118 (extraits). Gennadi Rojdestvenski, Philharmonia Chorus and Orchestra, Neeme Järvi" CHAN 9095

  4. Mise en place d’un réseau de capteurs sans fil pour l’irrigation intelligente

    OpenAIRE

    BOUZIDI, Zeyneb; BENAMEUR, Amina

    2012-01-01

    Les réseaux de capteurs sont des réseaux formés d’un grand nombre de noeuds capteurs qui se collaborent entre eux pour fournir un service bien déterminé. Cependant l’impossibilité d’une intervention humaine, a poussé les utilisateurs à s’intéresser à ces réseaux pour la surveillance et la sécurité de l’environnement ainsi la collection des données. Dans ce mémoire nous présentons une approche pour mettre en place un réseau de capteurs pour détection des zones sèches et les irriguer par la sui...

  5. Prokofiev: Cantate pour le 20e anniversaire de la revolution d'Octobre op. 74 / Pierre-E. Barbier

    Index Scriptorium Estoniae

    Barbier, Pierre-E.

    1992-01-01

    Uuest heliplaadist "Prokofiev: Cantate pour le 20e anniversaire de la revolution d'Octobre op. 74. La Fleur de pierre op. 118 (extraits). Gennadi Rojdestvenski, Philharmonia Chorus and Orchestra, Neeme Järvi" CHAN 9095

  6. Antibiorésistance : quelle stratégie pour l'ANMV à trois ans ?

    OpenAIRE

    Moulin, Gérard; Orand, Jean-Pierre

    2013-01-01

    L'Anses via son Agence nationale du médicament vétérinaire (ANMV)94 a pour mission d'évaluer, selon les réglementations nationale et européenne en vigueur, les risques liés aux médicaments vétérinaires. Elle est notamment responsable de : La délivrance des autorisations administratives relatives au médicament vétérinaire ; La surveillance des effets indésirables des médicaments vétérinaires (dont les vaccins) utilisés pour la prophylaxie, le diagnostic ou le traitement des maladies animales, ...

  7. Art, Music and Religious Experience in Libation Pouring of Akan Religion

    Directory of Open Access Journals (Sweden)

    Desmond Ayim-Aboagye

    1996-01-01

    Full Text Available The Akans of Ghana are traditionally accustomed to celebrating different rituals which are enshrined in their cultural life. Libation pouring, which accompanies the celebration of great rituals, amidst the subsidence of the sound of music and dance, can display a special art in religion. The primary objective of this paper is to examine libation as a ritual experience, and in so doing to draw attention to its art forms and relevance as regards the psychological significance for the Akan society which practises it. What beliefs connect the pouring of libation in Akan society? What are the occasions for practising this ritual? Are there some distinctions in the artistic prayer of libation? These questions lead directly to the proposition which states that libation is able to generate some forms of religious experience. It is then argued that libation ritual has psychological consequences beneficial to the group and the individual who privately engages in it.

  8. CREATION DE VALEUR : QUELS RISQUES POUR DES CENTRES DE PROFIT ? LE CAS AIR FRANCE

    OpenAIRE

    Lesobre, Thomas

    2000-01-01

    International audience; Avec l'ouverture du capital et la refonte des schémas de gestion, une réflexion s'est engagée pour introduire la création de valeur au sein des trois métiers d'Air France. Cependant, ce sont actuellement des centres de profit : au-delà de leur compte de résultat, il faut donc répartir les éléments bilantiels ; or, la seule construction de l'EVA, et de sa déclinaison pour des fins de gestion interne, est un risque majeur de crédibilité et de conflit.

  9. Etude comparative des consommables pour le dosage des endotoxines bactériennes chez deux fournisseurs

    OpenAIRE

    Tall, Mamadou-Lamine; Guilli, Taoufik; Renaud, J.; Ducarre, B; Koog, N.; Bador, M.; Diouf, E; Pirot, Fabrice; Pivot, Christine

    2013-01-01

    Les endotoxines bactériennes (EB) sont des pyrogènes, leur recherche est obligatoire pour certains produits pharmaceutiques. La Pharmacie à Usage Intérieur (PUI) réalise en moyenne 3600 dosages des EB par an selon la méthode colorimétrique cinétique. Le temps de réaction enzymatique pour cette méthode cinétique est fortement impacté par la qualité de ces consommables. L'objectif est de comparer l'effet des réactifs sur le dosage des EB chez 2 fournisseurs (A et B) et l'impact financier relati...

  10. RHEOCASTING OF A356 ALLOY BY LOW SUPERHEAT POURING WITH A SHEARING FIELD

    Institute of Scientific and Technical Information of China (English)

    H.M. Guo; X.J. Yang; B. Hu

    2006-01-01

    A novel semi-solid slurry-making process was developed, which was a controlled nucleation and growth technique using a specially designed rotational barrel. Experimental study was undertaken to investigate the effects of pouring temperature and rotation speed of barrel on the microstructure of A356 alloy. Localized rapid cooling, combined with vigorous mixing during the initial stage of solidification enhanced wall nucleation and nuclei survival. High nuclei density combined with a much gradual cooling afterwards led to the formation of the near-ideal semi-solidslurry under a large processing window for the pouring temperature. Primary phase presented in mean equivalent diameter of 50-70μm and shape factor of 0.812-0.847, and featured zero-entrapped eutectic.

  11. Création d'un tableau de bord pour l'Archive ouverte UNIGE

    OpenAIRE

    Pella, Cédric; Ruch, Patrick

    2010-01-01

    Le mandat qui fonde ce travail est la création d’un tableau de bord pour le pilotage à long terme du projet Archive ouverte UNIGE. Derrière ce nom, se cache le dépôt d’archives électroniques de l’Université de Genève. Les objectifs généraux suivants ont été identifiés pour mener à bien le mandat : Connaître les enjeux et les orientations stratégiques de l’Archive ouverte UNIGE. Identifier des indicateurs adaptés aux services liés à des ressources numériques. Déterminer quels indicateurs sont ...

  12. Spotify quel avenir pour le géant de la musique en streaming ?

    CERN Document Server

    Bouillot, Charlotte; Cadiat, Anne-Christine

    2015-01-01

    Un guide pratique et accessible pour tout savoir sur Spotify et ses créateurs passionnés Avec plus de 60 millions d'utilisateurs actifs à travers le monde en fin d'année 2014, Spotify est de loin l'acteur incontournable de l'écoute de musique en streaming. Mais que sait-on réellement de l'entreprise et des moyens qu'elle met en œuvre pour proposer à l'auditeur ses morceaux préférés ? Quelles sont les clés de la réussite de cet acteur qui a révolutionné la manière de consommer la musique ? D'ailleurs, l'entreprise est-elle véritablement rentable ?  Ce livre vous aidera à :        Comprendre la

  13. Nanomatériaux pour la catalyse : le spray a le vent en poupe

    OpenAIRE

    Sanchez, Clement

    2010-01-01

    Clément Sanchez, directeur de l’équipe « Matériaux hybrides » (UMR 7574) du laboratoire de Chimie de la matière condensée Les zéolithes, catalyseurs à base d’alumino-silicates utilisés actuellement pour le raffinage du pétrole, présentent un réseau de micropores de diamètre généralement inférieur à 1nm. Seules de petites molécules peuvent pénétrer dans le réseau pour être efficacement transformées : on cherche donc, depuis plus de 40 ans, à augmenter la taille des pores des catalyseurs tout e...

  14. Numerical Study of Impingement Location of Liquid Jet Poured from a Tilting Ladle with Lip Spout

    Science.gov (United States)

    Castilla, R.; Gamez-Montero, P. J.; Raush, G.; Khamashta, M.; Codina, E.

    2017-04-01

    A new approach for simulating liquid poured from a tilting lip spout is presented, using neither a dynamic mesh nor the moving solid solution method. In this case only the tilting ladle is moving, so we propose to rotate the gravitational acceleration at an angular velocity prescribed by a geometrical and dynamical calculation to keep the poured flow rate constant. This angular velocity is applied to modify the orientation of the gravity vector in computational fluid dynamics (CFD) simulations using the OpenFOAM® toolbox. Also, fictitious forces are considered. The modified solver is used to calculate the impingement location for six spout geometries and compare the jet dispersion there. This method could offer an inexpensive tool to calculate optimal spout geometries to reduce sprue size in the metal casting industry.

  15. The identification of pouring conditions of cast iron to sand moulds

    Directory of Open Access Journals (Sweden)

    B. Borowiecki

    2008-04-01

    Full Text Available The structure and properties of the castings in cast iron put on spheroidization depend especially on the pouring conditions. Decisive factor of local castings properties can be the flow ability of liquid metal in sand mould, which depends not only on chemical constitutions but also on temperature and velocity of pouring. The parameter, which take into consideration various factors is a substitute rheological parameter θ proposed in early author’s papers [1, 2]. The parameter determined in fluidity test can be used to calculation of thickness of rheological boundary layer metal in gating system channel and in casting. The identification a thermal properties of sand mould material has been require of investigation proposed in literature [3, 4]. In the article presented also the experimental of measurement results of metal levels in piezometers located on the horizontal cross gate.

  16. Écrire pour vivre, vivre pour écrire: un récit autobiographique au Brésil

    Directory of Open Access Journals (Sweden)

    Maria Luisa Scaramella

    2010-02-01

    Full Text Available Cet article traite du rôle de l’écriture autobiografique dans la vie de Maura Lopes Cançado. Maura a écrit un livre, l´Hospice c´est Dieu, espèce de journal intime autobiographique publiée en 1965 au Brésil. Maura commence sa carrière en écrivant des contes pour le Jornal do Brasil, en 1958, dans le supplément littéraire. Son désir pour être reconnue donne lieu à des crises de nerfs, le conduisant à s´interner en hopitaux psychiatriques. Son livre est le fruit de ses nombreux internements, il fournit un portrait de sa condition: la patiente qui subit les pratiques d´une institution psychiatrique violente et décadente; l´individu qui puise dans l´écriture autobiographique son lien le plus profond avec la vie, son fil d´Ariane, qui le tire du labyrinthe. Cette écriture marquée par la souffrance, sert de pont entre Maura et le monde. Si écrire est le fil qui le relie à la vie, à l’autre, à la société, à mesure que Maura s´éloigne de l´écriture, son histoire devient tragique. Le je et l’autre s´éloignent.

  17. Rénovation des amplificateurs Radiofréquence Linac1 pour l’expérience MICE

    CERN Document Server

    Giguet, JM

    2010-01-01

    Deux amplificateurs type Linac1 de 1958 ont été rénovés et modifiés pour être utilisés en fonctionnement pulsé à haute puissance pour l’expérience MICE au Laboratoire de Daresbury UK). Cette solution a permis d’avoir des unités capables de fournir les puissances demandées avec un investissement réduit.

  18. Effect of storage time of extended-pour and conventional alginate impressions on dimensional accuracy of casts.

    Directory of Open Access Journals (Sweden)

    Ahmad Rohanian

    2014-12-01

    Full Text Available Some manufacturers claim to have produced new irreversible hydro-colloids that are able to maintain their dimensional stability during storage. The present study evaluated the effect of storage time on dimensional stability of three alginates: Hydrogum 5, Tropicalgin and Alginoplast.In this experimental in-vitro trial, a total of 90 alginate impressions were made from a Dentoform model using Hydrogum 5, Tropicalgin and Alginoplast alginates. The impressions were stored in a sealed plastic bag without a damp paper towel for 0, 24, 48, 72 and 120 hours and then poured with type III dental stone. Cross-arch (facial of 6 to facial of 6 on the opposite side and antero-posterior (distal of right first molar to the ipsilateral central incisor measurements were made with a digital caliper on the casts. Data were analyzed by two-way and one-way ANOVA and Tukey's post-hoc test (P<0.05.Alginate type and the pouring time significantly affected the dimensional stability of alginate impressions (both Ps<0.001. Pouring of Hydrogum 5 impressions can be delayed for up to 120 hours without significant dimensional changes. Alginoplast impressions may be poured after 72 hours, but Tropicalgin should be poured immediately and the storage time should not be more than 24 hours.Immediate pouring of alginate impressions provides the highest accuracy in reproducing the teeth and adjacent tissues; however, this study demonstrated that pouring may be delayed for up to five days using extended-pour (Hydrogum 5 alginates.

  19. Accuracy of Gypsum Casts after Different Impression Techniques and Double Pouring.

    Science.gov (United States)

    Silva, Stephania Caroline Rodolfo; Messias, Aion Mangino; Abi-Rached, Filipe de Oliveira; de Souza, Raphael Freitas; Reis, José Maurício Dos Santos Nunes

    2016-01-01

    This study evaluated the accuracy of gypsum casts after different impression techniques and double pouring. Ten patients were selected and for each one it was obtained 5 partial putty/wash impressions with vinyl polysiloxane (VPS) material from teeth #13 to #16 with partial metal stock trays. The following techniques were performed: (1) one-step; two-step relief with: (2) PVC film; (3) slow-speed tungsten carbide bur and scalpel blade, (4) small movements of the tray and (5) without relief-negative control. The impressions were disinfected with 0.5% sodium hypochlorite for 10 minutes and stored during 110 and 230 minutes for the first and second pouring, respectively, with type IV gypsum. Three intra-oral lateral photographs of each patient were taken using a tripod and a customized radiographic positioner. The images were imported into ImageJ software and the total area of the buccal surface from teeth #13 to #16 was measured. A 4.0% coefficient of variance was criterion for using these measurements as Baseline values. The casts were photographed and analyzed using the same standardization for the clinical images. The area (mm2) obtained from the difference between the measurements of each gypsum cast and the Baseline value of the respective patient were calculated and analyzed by repeated-measures two way-ANOVA and Mauchly's Sphericity test (α = 0.05). No significant effect was observed for Impression technique (P = 0.23), Second pouring (P = 0.99) and their interaction (P = 0.25). The impression techniques and double pouring did not influence the accuracy of the gypsum casts.

  20. OGM Diffusion des OGM et impact pour les agriculteurs : quels sont les liens ?

    Directory of Open Access Journals (Sweden)

    Lemarie Stéphane

    2001-05-01

    Full Text Available Les OGM actuellement sur le marché présentent des innovations sur des fonctions de protection des plantes. Selon les problèmes de protection des plantes, les gains des agriculteurs liés à l’adoption des OGM sont très variables. Cette hétérogénéité pose d’importants problèmes méthodologiques pour pouvoir estimer correctement la distribution des gains pour l’ensemble des agriculteurs. Une synthèse de plusieurs études américaines est réalisée ici et met bien en évidence la diversité des méthodes utilisées, chacune d’elles présentant ses avantages et ses limites. Globalement, si la diffusion des OGM est un fait indéniable, les études ne permettent pas de tirer des conclusions aussi nettes quant à l’impact des OGM pour tous les agriculteurs qui adoptent ces produits, et cela en particulier pour le soja. Cette absence de conclusion s’explique en grande partie par la difficulté à mesurer certains facteurs qui influencent le comportement d’adoption, comme par exemple la simplification de la conduite des cultures. En contrepartie, il faut noter que les études présentées ici ne prennent pas en compte un certain nombre d’effets indirects qui peuvent faire diminuer les gains des agriculteurs.

  1. Des saints pour la fiction, des saints face à l’Histoire

    Directory of Open Access Journals (Sweden)

    Aude Bonord

    2008-12-01

    Full Text Available Pourquoi des écrivains non confessionnels (Joseph Delteil, Blaise Cendrars, Christian Bobin, Sylvie Germain, Claude Louis-Combet ont-ils choisi de réécrire des vies de saints au XXe siècle ? Le parti pris est surprenant à plusieurs titres. L’hagiographie est un genre historique et religieux, terrain a priori réservé aux historiens, aux ecclésiastiques ou aux écrivains catholiques. De plus, à la fin du siècle, l’hagiographie est sortie du champ littéraire avec la disparition du groupe des écrivains catholiques. Curieusement, nos auteurs vont s’inscrire dans ces décalages non seulement pour définir leur place par rapport à l’hagiographe traditionnel mais aussi pour s’approprier le genre. Amorces fictionnelles et objets de rêveries poétiques, les vies de saints sont soumises à la fantaisie littéraire de ces auteurs au statut improbable. Dans un dialogue avec les sources allant du jeu à la contestation, les écrivains utilisent l’intertexte hagiographique, et notamment son système narratif, pour s’évader dans le merveilleux mais encore pour penser leur époque. En effet, si éloignée de la réalité contemporaine soit-elle en apparence, l’hagiographie joue à la fois un rôle de contrepoint et de reflet du présent. La confrontation avec ces récits surgis du passé permet alors aux auteurs de repenser la marche de l’Histoire et l’inscription de l’Homme dans le temps.

  2. Mesures magnétiques du dipôle BHN 45 pour le projet AD

    CERN Document Server

    Cornuet, D; CERN. Geneva. SPS and LEP Division

    1999-01-01

    La machine AC (Antiproton Collector) transformée en machine de décélérationd'antiprotons est appelée AD (Antiproton Decelerator). Pour vérifierle comportement de la machine à basse énergie et pendant la décélération, des mesures magnétiques ont été entreprises sur l'un des dipôles, le BHN 45.

  3. Un accumulateur echangeur de chaleur hybride pour la gestion simultanee des energies solaire et electrique

    Science.gov (United States)

    Ait Hammou, Zouhair

    Cette etude porte sur la conception d'un accumulateur echangeur de chaleur hybride (AECH) pour la gestion simultanee des energies solaire et electrique. Un modele mathematique reposant sur les equations de conservation de la quantite d'energie est expose. Il est developpe pour tester differents materiaux de stockage, entre autres, les materiaux a changement de phase (solide/liquide) et les materiaux de stockage sensible. Un code de calcul est mis en eeuvre sur ordinateur, puis valide a l'aide des resultats analytiques et numeriques de la litterature. En parallele, un prototype experimental a echelle reduite est concu au laboratoire afin de valider le code de calcul. Des simulations sont effectuees pour etudier les effets des parametres de conception et des materiaux de stockage sur le comportement thermique de l'AECH et sur la consommation d'energie electrique. Les resultats des simulations sur quatre mois d'hiver montrent que la paraffine n-octadecane et l'acide caprique sont deux candidats souhaitables pour le stockage d'energie destine au chauffage des habitats. L'utilisation de ces deux materiaux dans l'AECH permet de reduire la consommation d'energie electrique de 32% et d'aplanir le probleme de pointe electrique puisque 90% de l'energie electrique est consommee durant les heures creuses. En plus, en adoptant un tarif preferentiel, le calcul des couts lies a la consommation d'energie electrique montre que le consommateur adoptant ce systeme beneficie d'une reduction de 50% de la facture d'electricite.

  4. La correspondance de Langlands locale p-adique pour GL_2(Q_p)

    CERN Document Server

    Berger, Laurent

    2010-01-01

    La correspondance de Langlands locale p-adique pour GL_2(Q_p) est une bijection entre certaines representations de dimension 2 de Gal(Q_p^bar/Q_p) et certaines representations de GL_2(Q_p). Cette bijection peut en fait etre construite en utilisant la theorie des (phi,Gamma)-modules et des resultats d'analyse p-adique. On deduit alors des proprietes de cette construction quelques applications interessantes en arithmetique.

  5. Utilisation du langage signal pour l'etude d'algorithmes de traitement du Signal electrocardiographique

    OpenAIRE

    Médigue, Claire; Clairambault, Jean; Kauffmann, François; Sorine, Michel; Cursi-Dascalova, Lilia

    1992-01-01

    Projet SOSSO; Pour etudier la maturation du Systeme Nerveux Autonome (SNA) chez les nouveaux nes, on analyse la Variabilite du Rythme Cardiaque (VRC), en relation avec d'autres informations biologiques telles que les changements de stades de sommeil. La VRC est calculee par la Transformee de Fourier a Court Terme dans trois bandes de frequence : la haute frequence, refletant le controle para sympathique seul et liee au cycle respiratoire ; les moyenne et basse frequences, refletant a la fois ...

  6. A new portable vibrator for plaster pouring: effect on the marginal fit at cylinder-abutment

    Directory of Open Access Journals (Sweden)

    Pâmela Cândida Aires Ribas de Andrade

    2012-10-01

    Full Text Available OBJECTIVE: The aim of this study was to test a new portable vibrator for plaster pouring (developed for this purpose, comparing the effect of its use on the accuracy of working cast of implant-supported restorations to the conventional vibrator. MATERIAL AND METHODS: From a master cast with 2 implants, 30 transfer moldings were made randomly and divided into three groups: Group I (GI: pouring performed in an outsourced dental laboratory with conventional plaster vibrator (10 casts, Group II (GII: pouring performed in the laboratory of the Federal University of Santa Catarina (UFSC with conventional plaster vibrator (10 casts and Group III (GIII: pouring performed with the portable vibrator fabricated for this study (10 casts. The position of the analogue and marginal adaptation of the infrastructure were verified by testing the single screw on the master model and on the working model. The measurement of misfit was blindly performed with a precision microscope and analyzing unit, Quadra-Check 200. The data were statistically analyzed by analysis of variance (ANOVA and the Holm-Sidak test (α=0.05. RESULTS: Means±standard deviations were as follows: GI: 19.19±4.73 µm; GII: 21.72±5.41 µm; GIII: 13.5±2.39 µm (P<0.05, with GIII significantly lower as compared to the other groups. CONCLUSION: Within the limitations of this study, it was concluded that a greater accuracy of working cast was achieved when a portable vibrator was used for casting molds.

  7. Développement d'une source EUV plasma laser pour la micro-lithographie

    Science.gov (United States)

    Segers, M.; Bougeard, M.; Caprin, E.; Ceccotti, T.; Chichmanian, F.; Descamps, D.; Haltebourg, P.; Hergott, J.-F.; Hulin, S.; Normand, D.; Schmidt, M.; Sublemontier, O.

    2003-06-01

    Le Groupe des Applications Plasma (GAP) du CEA à Saclay participe au projet national PREUVE du Réseau Micro- et Nano-Technologies. Ce projet a été lancé fin 1999 pour réunir et développer les compétences en France sur la lithographie dans l'extrême ultraviolet (LEUV). Au sein de PREUVE, notre objectif a été le développement d'une source plasma laser dans I'EUV autour de 13nm afin de contribuer à la réalisation d'un premier banc d'essai pour la lithographie (BEL) en Europe. Afin de réaliser cette source, nous utilisons un plasma émetteur qui est produit par l'interaction d'un laser de type Nd :YAG sur un jet de gouttelettes de xénon. A la fin du projet PREUVE, cette source satisfait les principales spécifications et répond en particulier aux besoins en flux de photons EUV pour réaliser des tests d'insolation EUV avec le banc d'essai. Suite à ces résultats prometteurs, nous démarrons actuellement un projet industriel EXULITE avec nos partenaires du CEA, d'Alcatel et de Thalès sur le développement d'une source EUV de puissance pour des machines de lithographie de production. Ce projet se terminera en 2005.

  8. Investigation of the Pour Point Depression Ability of Polyalkyl Acrylate Additives After Sonication

    Science.gov (United States)

    Volkova, G. I.; Anufriev, R. V.; Yudina, N. V.; Tchaikovskaya, O. N.

    2016-12-01

    Effect of ultrasonic treatment on the molecular parameters of polymeric additives based on polyalkyl acrylate is investigated. The viscosity, temperature, and energy characteristics of high-wax crude oil and solutions of petroleum wax in decane and aviation fuel TS-1 in the presence of initial and ultrasonified additives are determined. Results obtained indicate that the pour point depression ability of the additives is not reduced after treatment in an ultrasonic field.

  9. Utilisation de produits organiques oxygénés comme carburants et combustibles dans les moteurs. Première partie : Aspects techniques de l'utilisation sur moteur Using Oxygenated Organics Products As Fuels in Engines. Part One: Technical Aspects of Use in Engines

    Directory of Open Access Journals (Sweden)

    Guibet J. C.

    2006-11-01

    Full Text Available L'étude consiste à examiner les principales incidences techniques de l'emploi de produits organiques oxygénés (alcools, ethers. . . comme carburants et combustibles dans les moteurs à allumage commandé et diesel. On a tenté d'établir une synthèse des études très nombreuses réalisées sur ce sujet surtout depuis les cinq dernières années. On a considéré une large variété de produits (méthanol, éthanol, autres alcools, éthers organiques, systèmes acétono-butyliques. . . utilisés tels quels ou en mélange dans les produits pétroliers classiques. Des techniques particulières comme la carburation catalytique, la fumigation ou la double injection ont également été examinées. This article examines the main technical impacts of using oxygenated organic products (alcohols, ethers, etc. as fuels in spark-ignition and diesel engines. An attempt is made to provide a synthesis of the enormous volume of research that has been done on this subject, especially in the last five years. A wide variety of products is considered (methanol, ethanol, other alcohols, organic ethers, butyl-acetone systems, etc. , used either unblended or blended with conventional petroleum produtcs. Special techniques such as catalytic carburation, fumigation or dual injection are also examined.

  10. Effect of Pouring Time and Storage Temperature on Dimensional Stability of Casts Made from Irreversible Hydrocolloid

    Directory of Open Access Journals (Sweden)

    M. Farzin

    2010-12-01

    Full Text Available Objective: The aim of this study was to evaluate the dimensional stability of casts made from an alginate impression material poured immediately and stored after specific periods.Materials and Methods: The common alginate used in Iran (Super; Iralgin, Golchai Co.,Tehran, Iran was tested. A master model was mounted on a special device and used to obtain the impressions. These impressions were stored at 23°C (SD=1 and 4°C (SD=1 in100% relative humidity, then poured with gypsum immediately and again after 12, 25, 45 and 60 minutes. The casts were measured with a traveling microscope with the precision of 0.5 micrometer.Results: The dimensional stability of the alginate and impressions were both significantly time and temperature dependent. The impressions were dimensionally stable significantly until 12 minutes of storage at room temperature and until 45 minutes of storage at 4°C(SD=1.Conclusion: The dimensional stability of the alginate impressions was influenced by the storage time and environment temperature, but a humid environment and 4°C (SD=1temperature may delay the pouring.

  11. Le sponsoring politique : un défi et espoir pour la communication politique

    Directory of Open Access Journals (Sweden)

    H. Zouabi

    2017-03-01

    Full Text Available Dans le monde économique géré par la concurrence acharnée et exacerbée, l’entreprise tend à développer et diversifier ses moyens de communication et profiter des changements de l’environnement. En effet, à côté des médias traditionnels, l’entreprise s’appuie sur d’autres moyens de communication à savoir le sponsoring. Aujourd’hui le sponsoring est un moyen efficace dans la stratégie de communication des entreprises. Il ne cesse de se développer dans tous les domaines à savoir le sport, la culture, la santé, la politique, etc. Toutefois, les recherches spécialisées, professionnelles et académiques sur le sponsoring politique sont très limitées. C’est pourquoi cette recherche a été proposée. L’objectif de cet article est donc d’explorer le sponsoring politique comme un défi et espoir pour la communication politique. Les résultats de cette recherche montrent que les entreprises considèrent le sponsoring comme étant une variable stratégique. Pour le sponsoring politique, l’attitude des entreprises enquêtées varie largement en fonction de leur perception des risques et de leurs attentes pour les marques.

  12. Effects of Moulding Sand Permeability and Pouring Temperatures on Properties of Cast 6061 Aluminium Alloy

    Directory of Open Access Journals (Sweden)

    Olawale Olarewaju Ajibola

    2015-01-01

    Full Text Available Effects of moulding sand permeabilities prepared from the combinations of four proportions of coarse and fine particle size mixtures and pouring temperatures varied from 700, 750, and 800 (±10°C were studied on the hardness, porosity, strength, and microstructure of cast aluminium pistons used in hydraulic brake master cylinder. Three sand moulds were prepared from each of the 80 : 20, 60 : 40, 40 : 60, and 20 : 80 ratios. The surfaces and microstructures of cast samples were examined using high resolution microscopic camera, metallurgical microscope with digital camera, and scanning electron microscope with EDX facilities. The best of the metallurgical properties were obtained from the combination of 80 : 20 coarse-fine sand ratio and 750 ± 10°C pouring temperature using as MgFeSi inoculant. An 8 : 25 ratio of coarse to fine grained eutectic aluminium alloy was obtained with enhanced metallographic properties. The cast alloy poured at 750 ± 1°C has a large number of fine grain formations assuming broom-resembling structures as shown in the 100 µm size SEM image.

  13. Dispositif hybride pour un cours de grammaire en français langue seconde

    Directory of Open Access Journals (Sweden)

    Isabelle Lecoin

    2014-01-01

    Full Text Available Cet article décrit un projet-pilote pour la conception et la prestation d’un cours hybride de grammaire en français langue seconde (FLS. La recherche- action menée sur deux années consécutives en milieu universitaire canadien visait à faciliter l’intégration des technologies dans les cours de langue. Nous rendons compte de cette initiative, d’une part, en décrivant les composantes de notre design pédagogique et, d’autre part, en faisant une analyse des tendances émergeant de questionnaires administrés aux deux cohortes d’apprenants concernant cette première expérience de cours hybride dans notre faculté. Nous discutons de la valeur ajoutée, mais tout autant des enjeux d’un tel dispositif pour l’enseignement et l’apprentissage de la grammaire. Nous terminons avec des recommandations pour améliorer son design et sa gestion.

  14. Acaricide efficiency of amitraz / cypermethrin and abamectin pour-on preparations in game

    Directory of Open Access Journals (Sweden)

    J.S. Van der Merwe

    2005-09-01

    Full Text Available The efficacy of an amitraz / cypermethrin pour-on preparation (1 % w/v each was tested against natural tick infestations of buffaloes, eland and blesbok in three separate trials. The eland were also treated with a 0.02 % abamectin (w/v acaricidal pour-on preparation. The amitraz / cypermethrin pour-on was effective against Amblyomma hebraeum, Rhipicephalus evertsi evertsi, Rhipicephalus appendiculatus and Hyalomma marginatum rufipes on the buffaloes. Both acaricides were effective against R. appendiculatus and Rhipicephalus (Boophilus decoloratus in the eland. The amitraz / cypermethrin acaricide was effective against R. (Boophilus decoloratus in the blesbok. Ticks can cause damage to the skins, secondary infections, abscesses, anaemia, loss of condition, tick toxicosis and act as vectors of infectious diseases. Introduction of hosts and / or ticks from endemic to non-endemic areas because of translocation of game, may lead to severe losses. The pouron acaricides tested were effective against natural tick infestations and should always be used according to the manufacturer's instructions and efficacy claims.

  15. Acaricide efficiency of amitraz/cypermethrin and abamectin pour-on preparations in game.

    Science.gov (United States)

    Van Der Merwe, J S; Smit, F J; Durand, A M; Krüger, L P; Michael, L M

    2005-12-01

    The efficacy of an amitraz/cypermethrin pour-on preparation (1% w/v each) was tested against natural tick infestations of buffaloes, eland and blesbok in three separate trials. The eland were also treated with a 0.02% abamectin (w/v) acaricidal pour-on preparation. The amitraz/cypermethrin pour-on was effective against Amblyomma hebraeum, Rhipicephalus evertsi evertsi, Rhipicephalus appendiculatus and Hyalomma marginatum rufipes on the buffaloes. Both acaricides were effective against R. appendiculatus and Rhipicephalus (Boophilus) decoloratus in the eland. The amitraz/cypermethrin acaricide was effective against R. (Boophilus) decoloratus in the blesbok. Ticks can cause damage to the skins, secondary infections, abscesses, anaemia, loss of condition, tick toxicosis and act as vectors of infectious diseases. Introduction of hosts and/or ticks from endemic to non-endemic areas because of translocation of game, may lead to severe losses. The pouron acaricides tested were effective against natural tick infestations and should always be used according to the manufacturer's instructions and efficacy claims.

  16. Microstructural characteristics of in situ Mg2Si/Al-Si composite by low superheat pouring

    Directory of Open Access Journals (Sweden)

    Wu Xiaofeng

    2013-09-01

    Full Text Available To control the morphology and size of the primary and eutectic Mg2Si phases in in situ Mg2Si/Al-Si composite and achieve a feasible and reliable technique to produce appropriate feedstock for the thixo-casting and rheo-casting of this type of material, three Al-Si matrix composites reinforced by 5wt.%, 9wt.% and 17wt.% Mg2Si with hypoeutectic, eutectic and hypereutectic compositions were prepared by the low superheat pouring (LSP process. The effects of the pouring temperature (superheat on the morphology and size distribution of primary phases (primary α-Al and Mg2Si, binary (α-Al + Mg2Si eutectic cell and eutectic Mg2Si were investigated. The experimental results show that low pouring temperature (superheat not only refines the grain structure of the primary α-Al and binary (α-Al + Mg2Si eutectic cell in three composites and promotes the formation of more non-dendritic structural semi-solid metal (SSM slurry of these phases; but also refines the primary and eutectic Mg2Si phases, which seems to be attributed to the creation of an ideal condition for the nucleation and the acquisition of a high survival of nuclei caused by the LSP process.

  17. Contribution à la modélisation des convertisseurs statiques pour la simulation à topologie variable

    Science.gov (United States)

    Sahraoui, Omar; Gerbaud, Laurent; Normand, Olivier; Roudet, James

    1993-06-01

    This paper presents a simple and structured method of static converter modelling with variable topology, for the simulation of controlled converter-machine drives. The methodology is based on the notion of switching cells which enables a modular decomposition of converters in structures easy to be studied and henceforth called independent converter legs. These independent legs will be stored in libraries (algorithms or programs, and models) in order to be re-used for the study of other converters. Cet article propose une méthode simple et structurée pour la modélisation des convertisseurs statiques par des modèles à topologie variable, en vue de la simulation d'associations machine-convertisseur-commande complètes. Cette démarche s'appuie sur la notion de cellule de commutation pour permettre de dégager une décomposition modulaire du convertisseur en structures élémentaires, faciles à étudier, qui seront appelées bras indépendants. Ces derniers sont stockés en bibliothèque (sous forme d'algorithme ou programme, et sous forme de modèle), pour être réutilisés dans l'étude d'autres convertisseurs.

  18. Boites de distribution pour l'alimentation eléctrique du LHC

    CERN Document Server

    Folch, R; CERN. Geneva. TS Department

    2004-01-01

    En tant qu'unité d'engineering mécanique et matériaux, le groupe MME est en charge de la conception et des dossiers de spécification des DFBA, DFBL & DFBM (Electrical Distribution Feed Boxes) du LHC. Ces équipements complexes ont pour fonction principale l'alimentation électrique de puissance des aimants de la machine. Au total 34 types de DFB différents seront nécessaires, comportant quelque 1200 amenées de courant supraconductrices et résistives de 120 A à 13000 A. Pour les besoins urgents du test dans le secteur 7-8 du LHC, le groupe a été également sollicité pour réaliser les dossiers des plans de fabrication, fabriquer et assembler 2 versions de DFBA (la DFBAN et la DFBAO), ainsi que les amenées de courant correspondantes d'ici mai 2005. Cette opération requiert l'utilisation de nombreuses compétences du groupe. Plus de 500 plans de fabrication seront produits et plusieurs spécifications techniques seront établies. Une collaboration rapprochée entre le bureau d'étude et l'équi...

  19. Leadership et confiance développer le capital humain pour des organisations performantes

    CERN Document Server

    Duluc, Alain

    2003-01-01

    Aujourd'hui, l'encadrement des hommes consiste à tirer le meilleur parti de soi-même et des autres pour contribuer au développement de la performance. Ce type de leadership repose sur des valeurs telle qu'honnêteté, confiance, exemplarité, etc. Cet ouvrage propose une définition opérationnelle de ces valeurs et une façon de les mettre en ouvre. Il repose sur les méthodes et outils de développement personnel et organisationnel, élaborés par Will Schutz, un thérapeute américain. Sommaire : La complexité, nouveau passage des entreprises; Développer la confiance et la dimension humaine pour faire face à la complexité; Quelle forme de leadership pour demain?; Développer la confiance dans l'entreprise; La connaissance de soi et des autres, premier pas vers la confiance.

  20. Effect of pouring temperature on fractal dimension of primary phase morphology in semi-solid A356 alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Zheng; MAO Wei-min; LIU Xiao-mei

    2009-01-01

    The fractal dimensions of primary phase morphology in semi-solid A356 alloy prepared by low superheat pouring and slightly electromagnetic stirring were calculated, and the effect of pouring temperature on fractal dimension of primary phase morphology in semi-solid A356 alloy was researched. The results indicate that it is feasible to prepare semisolid A356 alloy slurry by low superheat pouring and slightly electromagnetic stirring, and there is an important effect of pouring temperature on the morphology and the grain size of the primary phase in semi-solid A356 alloy, in which the reduction of pouring temperature can obviously improve grain size and shape factor of primary phase in semi-solid A356 alloy under the condition of a certain stirring power. The primary phase morphology of semi-solid A356 alloy prepared by low superheat pouring and slightly electromagnetic stirring can be characterized by fractal dimension, and the primary phase morphology obtained by the different processing parameters has the different fractal dimensions. Solidification of semi-solid alloy is a course of change in fractal dimension.

  1. Interface of components with large ratio of altitude to diameter formed by laminated pouring and accumulated liquid forging technology

    Institute of Scientific and Technical Information of China (English)

    姜巨福; 罗守靖; 王迎

    2003-01-01

    Based on the experiment of laminated pouring and accumulated liquid forging of 2A12 aluminum alloy,interface bonding of formed component with large altitude to dimeter ratio of altitude to diameter was investigated by means of SEM and Instron tensile tester.The results show that the method of laminated pouring and accumulated liquid forging can be used for forming components with large ratio.Pouring temperature,reheated temperature of die,pressure,pouring layers and standing time are all important technique parameters that influence the mechanical properties.When pouring temperature is 740℃,reheated temperature of die is 480℃,pressure is 500 kN,pouring layers are three and standing time is 5s,the mechanical properties of interface are the optimum ones,microstructure is equiaxed crystal and tensile fracture has character of dimple.There are three kinds of bonding,which are melting bonding,part melting bonding and mechanical bonding.And the interface of the melting bonding possesses the best mechanical properties.

  2. Proposition d'attribution de deux contrats pour la fourniture de fils supraconducteurs destines aux aimants de correction du LHC

    CERN Document Server

    1999-01-01

    Le présent document concerne l'attribution de deux contrats pour la fourniture de fils supraconducteurs émaillés de quatre types différents (fil 1, fil 2, fil 3 et fil 4) destinés aux aimants de correction du LHC. Un appel d'offres (IT-2649/LHC/LHC) a été adressé le 13 juillet 1999 à quatre entreprises dans quatre Etats membres, trois entreprises au Japon et trois entreprises aux Etats-Unis. A la date de clôture, le CERN avait reçu cinq offres. Il est demandé au Comité des finances d'approuver la négociation de deux contrats: 1. d'une part avec IGC (USA) pour la fourniture de fils supraconducteurs 1 et 2 destinés aux aimants de correction du LHC pour un prix total net de 996 074 dollars des Etats-Unis, non révisable, avec une option pour la fourniture de fils 1 et 2 supplémentaires représentant 20% de la quantité initiale pour un prix total net de 199 215 dollars des Etats-Unis, révisable, ce qui porte le montant total à 1 195 289 dollars US, révisable pour l'option. Au taux de change in...

  3. 耐热钢HP40Nb的中温粉末法渗铝及其抗渗碳特性%Pack aluminizing at moderate temperature on HP40Nb heat-resistant steel and its anti-carburization behaviour

    Institute of Scientific and Technical Information of China (English)

    潘建伟; 谢飞; 孙力; 焦世辉; 翟建祥

    2012-01-01

    Pack aluminizing at temperature of 800-900 ℃ was investigated on HP40Nb heat-resistant steel with a media composed of master alloy of Fe-Al powder as Al supplier,NH4Cl as activator and SiC as filler.The anti-carburizing behaviour of the treated specimen was studied by employing an intensified pack carburization test.The results show that the aluminizing case has high surface quality and adheres very well with the substrate.The case is mainly composed of a deposition zone and a following transition zone.The thickness of the case is thinner than that by higher temperature aluminizing.Direct current field has few influence on the types of phase structure of the aluminized cases,while it can enhance the aluminizing rate at 800 ℃ by nearly 7 times.The aluminized cases studied show excellent anti-carburization ability in the intensified carburization test at 1000 ℃.%以铝铁为供铝剂、氯化氨为活化剂、碳化硅为填充剂,研究了耐热钢HP40Nb在800~900℃间的粉末法渗铝特性,采用固体强化渗碳方式来研究不同状态试样的抗渗碳能力。研究表明:渗层表面质量很高,渗层与基体结合良好,渗层主要由沉积区和过渡区两部分组成,较之高温渗铝,渗层厚度较薄;采用直流电场增强法对HP40Nb粉末法渗铝渗层相组成种类影响不大,但能使其800℃时的渗铝速度提高近7倍。所试验渗铝层在1000℃强化渗碳条件下表现出优良的抗渗碳特性。

  4. Économie d'un procédé d'hydrolyse enzymatique et fermentation de la paille de blé pour la production d'alcool carburant Economics of a Process for Producing Alcohol Fuels by Enzymatic Hydrolysis and Fermentation of Wheat Straw

    Directory of Open Access Journals (Sweden)

    Arlie J. P.

    2006-11-01

    Full Text Available Après définition des grandes lignes d'un procédé de base d'hydrolyse-fermentation de la paille de blé, l'analyse de sensibilité montre que le rendement de l'hydrolyse a une grande importance sur les bilans énergétique et économique. Des rendements de l'ordre de 85 % permettent d'obtenir des valeurs d'investissement par tonne de pétrole économisée tout à fait comparables à celles obtenues par d'autres techniques de valorisation de la biomasse en alcool, telle la synthèse du méthanol obtenu après gazéification du bois à l'oxygène. The basic features of a process for production from cereal straw of an acetone-butanol mixture for use as a gasoline substitute are described. They include pretreatment and enzymatic hydrolysis of the substrate followed by fermentation of the sugars produced. A cost evaluation based on the performances of a reference process is presented. Then, an analysis of the sensitivity of the cost price of the process to the variation of the important parameters such as production capacity, enzyme productivity, hydrolysis yield is carried out. The energy balance of the process is presented.

  5. On the Use of Genetic Algorithm to Optimize the On-board Energy Management of a Hybrid Solar Vehicle De l’usage de l’algorithme génétique pour l’optimisation de la gestion de l’énergie embarquée d’un véhicule hybride solaire

    Directory of Open Access Journals (Sweden)

    Sorrentino M.

    2010-09-01

    conventionnelles en cas d’utilisation intermittente en ville (voiture urbaine. Ils ont également démontré que les voitures VHS étaient réalisables d’un point de vue économique dans un avenir proche. Grâce au groupe motopropulseur en série adopté pour le prototype de VHS, une utilisation intermittente du Moteur à Combustion Interne (MCI alimentant le générateur électrique est possible, évitant ainsi un fonctionnement du moteur en charge partielle peu efficace. La meilleure trajectoire de puissance du MCI est déterminée par l’optimisation de l’algorithme génétique, responsable de la consommation de carburant et de l’état de charge de la batterie, en prenant également en compte la contribution solaire en mode de stationnement. La configuration expérimentale utilisée pour l’enregistrement des données, la surveillance et le contrôle du prototype en temps réel est également présentée, de même que les résultats obtenus au cours des différents essais routiers abordés.

  6. ALLER + INFINITIF ET SES TRADUISANTS EN ITALIEN : REMARQUES POUR UNE NOUVELLE CATEGORISATION DE LA PERIPHRASE

    Directory of Open Access Journals (Sweden)

    Alida SILLETTI

    2013-05-01

    Full Text Available Cette recherche porte sur la périphrase aller + infinitif en français contemporain et ses traduisants en italien. Les études les plus récentes (dont Vet, 2007 en la matière mettent en évidence une nouvelle catégorisation de la périphrase, notamment comme temps verbal à part entière (Vetters, Lière, 2009. Il est donc possible de situer aller au milieu d’un continuum temporel, entre le présent pro futuro et le futur simple flexionnel, pour signifier le futur temporel verbal en français (Silletti, sous presse. Ces études insistent également sur le fait que, au niveau sémantique, aller exprimerait un futur proche du moment de l’énonciation en termes de certitude de la part du locuteur (Provôt, Desclés, Vinzerich, 2010 plutôt qu’en termes d’immédiateté temporelle. Grâce à notre expérience d’enseignement de la traduction français - italien pour italophones nous avons remarqué que la traduction d’aller posait quelques problèmes. Selon nous, deux facteurs expliquent cette difficulté : d’une part, le manque d’une périphrase fonctionnellement proche d’aller en italien ; d’autre part, un traitement non homogène d’aller. C’est pourquoi nous analyserons d’abord la nouvelle catégorisation d’aller en français ; puis nous proposerons les exemples d’aller tirés de notre corpus. Celui-ci est constitué de quatre textes français contemporains et de leurs traduisants italiens proposés par 250 étudiants. Ensuite, nous ferons état du traitement d’aller au sein de cinq grammaires d’apprentissage du français pour italophones. Notre but consistera à évaluer les choix des étudiants en les rapportant aux co(ntextes d’occurrences d’aller. Suite à ce travail d’évaluation, nous tenterons d’exposer une nouvelle catégorisation d’aller pour les grammaires d’apprentissage du français pour italophones. Celle-ci devrait tenir compte de plusieurs paramètres et y intégrer les nouvelles

  7. Elaboration de nouvelles approches micromecaniques pour l'optimisation des performances mecaniques des materiaux heterogenes

    Science.gov (United States)

    Aboutajeddine, Ahmed

    Les modeles micromecaniques de transition d'echelles qui permettent de determiner les proprietes effectives des materiaux heterogenes a partir de la microstructure sont consideres dans ce travail. L'objectif est la prise en compte de la presence d'une interphase entre la matrice et le renforcement dans les modeles micromecaniques classiques, de meme que la reconsideration des approximations de base de ces modeles, afin de traiter les materiaux multiphasiques. Un nouveau modele micromecanique est alors propose pour tenir compte de la presence d'une interphase elastique mince lors de la determination des proprietes effectives. Ce modele a ete construit grace a l'apport de l'equation integrale, des operateurs interfaciaux de Hill et de la methode de Mori-Tanaka. Les expressions obtenues pour les modules globaux et les champs dans l'enrobage sont de nature analytique. L'approximation de base de ce modele est amelioree par la suite dans un nouveau modele qui s'interesse aux inclusions enrobees avec un enrobage mince ou epais. La resolution utilisee s'appuie sur une double homogeneisation realisee au niveau de l'inclusion enrobee et du materiau. Cette nouvelle demarche, permettra d'apprehender completement les implications des approximations de la modelisation. Les resultats obtenus sont exploites par la suite dans la solution de l'assemblage de Hashin. Ainsi, plusieurs modeles micromecaniques classiques d'origines differentes se voient unifier et rattacher, dans ce travail, a la representation geometrique de Hashin. En plus de pouvoir apprecier completement la pertinence de l'approximation de chaque modele dans cette vision unique, l'extension correcte de ces modeles aux materiaux multiphasiques est rendue possible. Plusieurs modeles analytiques et explicites sont alors proposee suivant des solutions de differents ordres de l'assemblage de Hashin. L'un des modeles explicite apparait comme une correction directe du modele de Mori-Tanaka, dans les cas ou celui ci echoue a

  8. Instrumentation pour la spectroscopie laser sur faisceau d'ions rapides

    Science.gov (United States)

    Bazin, Marc

    Devant l'emergence des technologies exploitant l'infiniment petit, la spectroscopie atomique et moleculaire devient de plus en plus incontournable pour comprendre precisement les mecanismes quantiques impliques dans l'interaction des molecules. C'est le cas notamment de la nanotechnologie, de la dynamique reactionnelle des gaz a effet de serre ou simplement de l'identification des molecules constituant certains objets de l'astrophysique. Bien qu'un travail considerable soit deja accompli pour comprendre la dissociation ou la formation des molecules simples, il reste a vaincre la complexite des mecanismes impliques lorsque les molecules possedent plus de trois noyaux. Parmi les rares techniques de spectroscopie a tres haute resolution (jusqu'a la structure hyperfine), la spectroscopie laser sur faisceaux d'ions rapides est une methode experimentale eprouvee depuis trois decennies environ. Cette methode spectroscopique fournit des resultats comptant parmi les meilleurs pour obtenir des constantes moleculaires precises et permettre la reduction du spectre moleculaire. Une particularite remarquable de notre instrument est la possibilite d'enregistrer le signal de fragmentation moleculaire par laser via les etats de predissociation de la molecule etudiee. Notre contribution a ete d'ameliorer et de moderniser l'equipement existant. Nous avons augmente la resolution spectrale de notre instrument. Nous avons atteint notre principal objectif, a savoir, la possibilite d'acquerir des spectres selon deux modes : par detection du signal synchronisee sur le faisceau laser module en frequence ou par detection du signal directement par comptage. Cette derniere methode est une premiere sur ce type d'instrument et son principal interet a ete d'obtenir une meilleure mesure de l'elargissement de raie. Nous sommes parvenus a mettre clairement en evidence l'elargissement de raie avec la puissance laser en utilisant la methode de detection par comptage direct. La fluorescence induite par

  9. Le marché des composés oxygénés dans le secteur des carburants The Market for Oxygen Compounds in the Fuel Sector

    Directory of Open Access Journals (Sweden)

    Meyer C.

    2006-11-01

    Full Text Available Le marché mondial des composés oxygénés, utilisés en mélange avec les carburants comme promoteurs d'octane, présente une expansion importante. On constate que le développement de ce marché se fait par les éthers aux dépens des alcools. Toutefois, la demande de méthanol reste soutenue, du fait que c'est une des matières premières de la synthèse du MTBE. On observe parallèlement des fluctuations importantes de la valorisation de ces composés qui, après avoir atteint en 1988 et début 1989 des niveaux jamais observés jusqu'alors, est revenue ensuite à des valeurs plus habituelles. Peut-on estimer comment ces tendances vont évoluer dans l'avenir ? C'est ce qui va être examiné dans les pages qui suivent. The world market for oxygen compounds used in a blend with fuels as octane promoters has been expanding rapidly in the last two years. This market has been growing via ethers at the expense of alcohols. However, the demand for methanol continues because it is one of the raw materials for MTBE synthesis. At the same time, the upgrading of these compounds has been increasing and has reached its highest level ever. Will these trends continue in the future? This is the topic dealt with by this article.

  10. Tourisme pour tous: et les bisses valaisans? : évaluation de la qualité d'accessibilité de 6 bisses pour personnes en fauteuil roulant

    OpenAIRE

    Allimann, Natacha; Margot-Cattin, Pierre

    2012-01-01

    Ce travail tente d’établir un nouveau lien entre tourisme et handicap. L’étude se consacre particulièrement au handicap moteur et à la région du Valais. La première raison de visiter le Valais est la randonnée pédestre. Parallèlement, les 70'000 personnes handicapées en Suisse sont un public-cible non négligeable pour les prestataires du tourisme. C’est pourquoi il est intéressant d’allier ce public-cible aux chemins de randonnée valaisans et plus particulièrement aux bisses. La première étap...

  11. Les diverses formes pour la compensation dans la protection juridique de l’environnement: un défi pour l’épistémologie juridique

    Directory of Open Access Journals (Sweden)

    Gabriela G B Lima

    2014-01-01

    Full Text Available La compensation est un outil d’adaptation entre différents intérêts. Par rapport à l’environnement, il existe une diversité de formes qui appliquent de façon différente l’une de l’autre, la technique de la compensation. Autrement dit, des situations juridiques différentes appliquent la compensation comme une façon de régler un enjeu: on peut la trouver dans la forme d’indemnisation, comme dans de cas de la Fonderie du Trail et la Commission de Compensation des Nations Unies; de réglementation d’un dommage futur, étant une compensation ex ante facto, comme dans le cas de la Convention de Ramsar; et par des voies juridiques qui incitent le comportement privé à travers l’usage de certains outils de marché, comme les Mécanismes de Dèveloppement Propre, ou dans le domaine du droit national, la compensation de la biodiversité française, la «mitigation banking» américaine, la «Servidão Ambiental» Brésilienne, et l’écocompensation chinoise, entre autres. Le défi épistémologique se présente dans la diversité de sources, ainsi que d’acteurs et de domaines d’action dans le cadre juridique environnemental, en y exigeant un élargissement de la vision du droit étatique. Il s’agit aussi d’intégrer une interprétation systémique pour le rapport entre les systèmes juridiques, écologiques et économiques concernés. Il est possible d’utiliser quelques outils comme le pluralisme juridique, la théorie des systèmes et l’analyse économique du droit de l’environnement. Les concepts de corégulation et autorégulation peuvent aussi aider dans cet élargissement. D’ailleurs, des limites sont nécessaires pour l’équilibre entre la mise en oeuvre des intérêts écologiques et économiques. Ces limites sont données par le droit, par l’interprétation systémique, par l’État et par un renforcement de la responsabilité des entités privées. L’analyse presente d’abord les caract

  12. Genesis 3 - Plate forme pour la création musicale à l'aide des modèles physiques CORDIS-ANIMA

    OpenAIRE

    Castagné, Nicolas; Cadoz, Claude

    2009-01-01

    Session: " Plates-formes pour la diffusion et pour la création "; National audience; GENESIS3 est une toute nouvelle version de l'environnement GENESIS pour la création musicale à l'aide les modèles physiques masse-interaction CORDIS-ANIMA. Elle a été conçue avec un recul de plus de dix années sur l'ancienne version et ses utilisations. Nous profitons de la sortie de GENESIS3 pour présenter une analyse du " paradigme logiciel " porté par GENESIS, en particulier en ce qui concerne les fonction...

  13. Placement et accueil en institution pour des personnes cérébo-lésées: l'exemple de Valais de Cœur

    OpenAIRE

    Caloz, Coralie; Staub, Pauline; Antonin-Tattini, Véronique

    2014-01-01

    Un placement et une entrée en institution peuvent être des étapes difficiles pour la personne concernée. L’éducateur devrait être informé du processus de placement pour pouvoir accompagner au mieux la personne dans cette démarche. De plus, l’accueil d’un nouvel arrivant est une étape provoquant des changements. Les premières impressions sur un nouveau lieu de vie peuvent être déterminantes pour la suite du placement. Il est donc important de trouver de bonnes pistes pour que l’institution et ...

  14. Plasma Sprayed Pour Tubes and Other Melt Handling Components for Use in Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, David; Rieken, Joel; Heidloff, Andy; Besser, Matthew; Anderson, Iver

    2011-04-01

    Ames Laboratory has successfully used plasma sprayed ceramic components made from yttria stabilized zirconia as melt pouring tubes for gas atomization for many years. These tubes have proven to be strong, thermal shock resistant and versatile. Various configurations are possible both internally and externally. Accurate dimensions are achieved internally with a machined fugitive graphite mandrel and externally by diamond grinding. The previous study of the effect of spray parameters on density was extended to determine the effect of the resulting density on the thermal shock characteristics on down-quenching and up-quenching. Encouraging results also prompted investigation of the use of plasma spraying as a method to construct a melt pour exit stopper that is mechanically robust, thermal shock resistant, and not susceptible to attack by reactive melt additions. The Ames Laboratory operates two close-coupled high pressure gas atomizers. These two atomizers are designed to produce fine and coarse spherical metal powders (5{mu} to 500{mu} diameter) of many different metals and alloys. The systems vary in size, but generally the smaller atomizer can produce up to 5 kg of powder whereas the larger can produce up to 25 kg depending on the charge form and density. In order to make powders of such varying compositions, it is necessary to have melt systems capable of heating and containing the liquid charge to the desired superheat temperature prior to pouring through the atomization nozzle. For some metals and alloys this is not a problem; however for some more reactive and/or high melting materials this can pose unique challenges. Figure 1 is a schematic that illustrates the atomization system and its components.

  15. Surveiller et classer : deux chantiers pour une recherche urbaine critique

    Directory of Open Access Journals (Sweden)

    Fabrice Bardet

    2010-07-01

    Full Text Available Après avoir navigué entre deux continents, Bernard Jouve s’était donné pour ambition de développer, au sein du monde académique français, une pensée critique sur la ville inspirée de la recherche urbaine nord-américaine et de diffuser ces réflexions au sein du monde social. Ce goût pour les analyses critiques sur le « fait urbain » a constitué, sous son impulsion, un élément fédérateur pour l’équipe de recherche lyonnaise qu’il a dirigée au cours des dernières années. A travers des exemples tirés de nos travaux sur les classements de ville et la surveillance, on montre qu’il en demeure aujourd’hui encore un important fil conducteur.Bernard Jouve lived a rich experience between two different academic worlds. That is the principle reason why he aimed to develop a critical thought on urban changes and cities in the midst of French academic world. Further, he wanted to spread these analysis inspired by North-American urban research among actors playing a role in urban policies. For the research team that he managed in Lyon for these last years, this interest became, and remains, a unifier element.

  16. Du vent pour scier le marbre : le moulin de Biot à Félines

    Directory of Open Access Journals (Sweden)

    Sandrine Claude

    2012-09-01

    Full Text Available Au cœur des Causses, à quelques kilomètres à l’est de Félines en Minervois, un moulin à scier le marbre s’insère dans une zone d’extraction du marbre griotte : on y en repère plusieurs carrières et sondages d’exploitation, des habitations de carriers et un chemin de charroi pour les blocs dégrossis. Le moulin, qui se dresse sur un socle artificiel aménagé en bordure d’une éminence naturelle, est entièrement réalisé à partir des déchets de taille de la carrière contiguë. Surprenante est ici l’utilisation de l’énergie éolienne pour activer le mécanisme, aujourd’hui disparu, des scies lisses qui entraînent du sable et, par abrasion, débitent des plaques de marbre d’une épaisseur comprise entre 1,5 et 2,5 cm : ce mode d’actionnement fait la spécificité et tout l’intérêt du moulin de Félines. Tout aussi étonnant est le silence des archives qui ne permet aujourd’hui d’avancer aucune datation précise pour cet ensemble dont les auteurs signalent l’état de ruine en 1892 ; seuls des indices d’ordre toponymique trahissent sinon une construction, du moins une utilisation du moulin au milieu du xixe siècle.

  17. Des interfaces intelligentes pour les modèles de gisements Intelligent Interfaces for Reservoir Models

    Directory of Open Access Journals (Sweden)

    Zucchini P.

    2006-11-01

    Full Text Available Les codes de simulation numérique nécessitent souvent l'entrée de données nombreuses et variées. Nous présentons un programme interactif d'aide à la constitution d'un jeu de données pour un modèle de simulation de l'évolution des fluides dans un gisement d'hydrocarbures pendant son exploitation. Nous avons utilisé un moteur d'inférences et un générateur d'écrans de saisie pour écrire cette interface. Cette approche comporte de nombreux avantages concernant la qualité du logiciel produit : fiabilité, extensibilité, facilité d'utilisation, etc. L'utilisation combinée de règles d'expertise et d'un langage orienté objet offre de nouvelles perspectives qui sont étudiées. En conclusion, nous proposons l'extension de cette démarche pour développer une interface commune aux logiciels en Exploration - Production. Numerical simulation software often needs many input data having different natures. This article describes an interactive software that is of help in building the input data fill needed by oil reservoir simulators. A professional inference engine has been used to build this interface. This approach offers many advantages concerning the quality of the software produced, i. e. reliability, extensibility, user friendliness, etc. New prospects opened up by the mixed use of expertise rules and object-oriented languages are pointed out. The conclusion emphasizes the extension of this approach to the development of a common interface for exploration-production software.

  18. Plasma Sprayed Pour Tubes and Other Melt Handling Components for Use in Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, David; Rieken, Joel; Heidloff, Andy; Besser, Matthew; Anderson, Iver

    2011-04-01

    Ames Laboratory has successfully used plasma sprayed ceramic components made from yttria stabilized zirconia as melt pouring tubes for gas atomization for many years. These tubes have proven to be strong, thermal shock resistant and versatile. Various configurations are possible both internally and externally. Accurate dimensions are achieved internally with a machined fugitive graphite mandrel and externally by diamond grinding. The previous study of the effect of spray parameters on density was extended to determine the effect of the resulting density on the thermal shock characteristics on down-quenching and up-quenching. Encouraging results also prompted investigation of the use of plasma spraying as a method to construct a melt pour exit stopper that is mechanically robust, thermal shock resistant, and not susceptible to attack by reactive melt additions. The Ames Laboratory operates two close-coupled high pressure gas atomizers. These two atomizers are designed to produce fine and coarse spherical metal powders (5{mu} to 500{mu} diameter) of many different metals and alloys. The systems vary in size, but generally the smaller atomizer can produce up to 5 kg of powder whereas the larger can produce up to 25 kg depending on the charge form and density. In order to make powders of such varying compositions, it is necessary to have melt systems capable of heating and containing the liquid charge to the desired superheat temperature prior to pouring through the atomization nozzle. For some metals and alloys this is not a problem; however for some more reactive and/or high melting materials this can pose unique challenges. Figure 1 is a schematic that illustrates the atomization system and its components.

  19. Philippe Poirrier (dir.), Pour une histoire des politiques culturelles dans le monde (1945-2011)

    OpenAIRE

    Girel, Sylvia

    2012-01-01

    L’ouvrage collectif édité sous la direction de Philippe Poirrier, Pour une histoire des politiques culturelles dans le monde, 1945-2011, vient prendre place dans un domaine de recherche (les politiques culturelles) où les publications sont aussi nombreuses que riches et variées, mais où aucune jusqu’alors ne proposait un tel panorama comparatif, engageant d’une part à mieux connaître la diversité des modèles, programmes et dispositifs élaborés dans différents pays, mais surtout permettant une...

  20. CARACTERISATION ET ETALONNAGE DES DYNAMOMETRES A SIX COMPOSANTES POUR TORSEUR ASSOCIE A UN SYSTEME DE FORCES

    OpenAIRE

    Couétard, Yves

    2000-01-01

    To deal with force systems, cinematics, kinetics and small displacement, the solid mechanics exploits the "torseur" model. We give a quantification of this notion through the elaboration of a metrology device : • a six components dynamometer. A spatial standardisation follows the study and allows to quantify the uncertainty of measurement of this device; La mécanique du solide exploite largement le modèle "torseur" pour traiter les systèmes de forces, la cinématique, la cinétique et les petit...

  1. Modélisation biophysique pour la prévision du recrutement

    OpenAIRE

    Allain, Gwenhael

    2004-01-01

    Les populations exploitées par la pêche sont dépendantes du recrutement (nombre de jeunes poissons constituant la nouvelle classe d'âge annuelle) pour assurer leur renouvellement. Le recrutement varie en relation avec l'hydroclimat, phénomène à l'origine de fluctuations importantes des stocks, qui peuvent amplifier les effets de l'exploitation. La prévision du recrutement requiert des outils d'océanographie halieutique plus fiables que les analyses de corrélation à grande échelle entre abo...

  2. Quelle autodétermination pour les personnes en situation de handicap en institution ?

    OpenAIRE

    2014-01-01

    Cette recherche a pour thème principal l’autodétermination des personnes en situation de handicap. Elle s’intéresse plus particulièrement aux moyens permettant de favoriser l’autodétermination de ces personnes en institution. Elle est composée de plusieurs parties distinctes. Tout d’abord, sont expliquées la question de recherche ainsi que les principales hypothèses qui guident ce travail. Ensuite, une partie théorique traitant des thèmes de l’autodétermination, du handicap, de l’accompagneme...

  3. RALF : une plate-forme de radio logicielle mutualisée pour la formation

    OpenAIRE

    2015-01-01

    En raison de son caractère pluridisciplinaire et de sa flexibilité, la radio logicielle constitue un excellent outil pédagogique. Le projet "RAdio Logicielle pour la Formation" (RALF) vise à promouvoir cet outil au sein des formations d'ingénierie de l'université de Toulouse. Au cours de cette présentation, nous aborderons les principaux défis pédagogiques soulevés par RALF : rendre la radio logicielle accessible à tous les niveaux de formation, capitaliser des ressources documentaires et péd...

  4. Insecticide and Repellent Mixture Pour-On Protects Cattle against Animal Trypanosomosis

    Science.gov (United States)

    Abdoulmoumini, Mamoudou; Zoli, Andre; Cene, Bylah; Adakal, Hassane; Bouyer, Jérémy

    2016-01-01

    Background African animal trypanosomosis (AAT), transmitted by tsetse flies and tick-borne diseases are the main constraints to livestock production in sub-Saharan Africa. Vector control methods such as pour-on offer individual protection against ticks but not against tsetse so far, for which protection has always been communal, through a reduction of their density. The latter requires the treatment of a large part of the herd in a given landscape and is not instantaneous. Methodology/Principal Findings Two prospective surveys were conducted to evaluate the efficacy and persistence of a pour-on formulation composed of cypermetrhin, chlorpyrifos, piperonyl butoxid and citronella (Vectoclor, CEVA Santé Animal). In experimental conditions, tsetse flies were exposed to treated and control cattle. Flies knockdown and engorgement rates were determined and the product persistence was assessed as the time for these parameters to drop below 50% (T50). T50 was 37 days (95%CI: [33–41] days) and 46 days (95%CI: [39–56] days) for the knockdown and engorgement rates respectively. In field conditions, two cattle herds were monitored following a case-control experimental design, in the Adamaoua region of Cameroon. One herd was treated once with Vectoclor pour-on (treated group) and the second used as a control group (not treated). Ticks infestation rate, trypanosomosis prevalence and packed-cell volume were measured over the two months following treatment. The treatment was highly effective against ticks with a complete elimination three days after application in the treated group. Trypanosomosis prevalence was also significantly reduced during the study (by 4, P<0.001) and PCV of the treated group increased significantly in the same time (P<0.001), contrary to the control group. Conclusions/Significance The protection of this new pour-on against tsetse bites and trypanosomosis is demonstrated here for the first time. Moreover, this insecticide and repellent mixture offer a

  5. Construire le web de données pour les sciences humaines et sociales

    OpenAIRE

    Pouyllau, Stéphane; Kilouchi, Shadia

    2009-01-01

    Les fonds documentaires et plus largement les données sources pour la recherche dans les Sciences humaines et sociales (SHS) ont commencé à prendre le tournant du numérique, de plus en plus de données, servant à faire de la recherche en SHS, sont nativement numériques. Il s'agit de mettre en œuvre une importante politique de conservation et de diffusion numérique des fonds, acquis la plupart du temps sur fonds publics depuis plus de 40 ans. Cela implique de la numérisation, de la re-documenta...

  6. Images d’Abd el-Kader : pièces pour un bicentenaire

    OpenAIRE

    Pouillon, François

    2011-01-01

    Lorsque mon ami Bruno Étienne me demanda de collaborer, pour la partie iconographique, à la fabrication du volume sur Abd el-Kader qui lui avait été commandé dans la collection « Découvertes Gallimard », j’acceptais avec enthousiasme. La possibilité de combiner sur une seule page des documents hétéroclites, la large place laissée aux commentaires permettant de donner sens à cette confrontation, me parurent ouvrir à un travail particulièrement pertinent sur l’image d’un grand homme inscrit dan...

  7. 浇筑水下混凝土灌注桩的质量控制要点%The quality control key points of pouring underwater concrete pouring pile

    Institute of Scientific and Technical Information of China (English)

    张向阳

    2015-01-01

    Based on the analysis on advantages and disadvantages of underwater concrete pouring pile,this paper discussed the underwater con-crete pouring pile construction technology key points from the impact holing,reinforcement cage decentralization,concrete pouring and other as-pects,and proposed improvement recommendations for deficiencies in construction,so as to ensure the piling quality.%在分析水下混凝土灌注桩施工优缺点的基础上,从冲击成孔、钢筋笼下放、混凝土灌注等方面探讨了水下混凝土灌注桩施工技术的要点,并对施工中的不足之处提出了改进建议,以保证成桩的质量。

  8. Dans quelle mesure l’athéisme est-il inacceptable pour l’auteur du Theophrastus redivivus et pour Spinoza ?

    Directory of Open Access Journals (Sweden)

    Nicole Gengoux

    2012-09-01

    Full Text Available Un problème posé par le Theophrastus redivivus, traité anonyme achevé en 1659, matérialiste et athée (au sens actuel du terme, est que l’auteur tout en critiquant radicalement la croyance en dieu, affirme qu’il faut chasser l’athéisme de la cité. Son athéisme est pourtant « pensable » : non seulement le mot n’est pas anachronique pour le xviie siècle, comme le pensent de nombreux commentateurs, mais le traité lui-même fait la généalogie de la croyance tout en exposant un système de pensée cohérent qui se passe de dieu.Le rejet du terme « athéisme » est d’ordre moral et social car il désigne celui qui se laisse entraîner par ses instincts. L’auteur nous prévient, en quelque sorte, que ce n’est pas parce qu’il nie les dieux qu’il n’est pas respectueux des lois. Cependant, l’« inacceptabilité » du terme « athée » a aussi un sens plus profond : comment, en effet, concilier l’ordre social et l’absence d’un Bien et d’un Mal absolus ? Certes le traité propose une solution purement naturelle en fondant la morale sur l’amour de soi, mais comment le faire comprendre ? C’est peu « acceptable » au sens de « compréhensible ».Nous pouvons distinguer des degrés d’inacceptabilité : l’amoralisme théorique paraît plus inacceptable, encore, que l’affirmation de l’inexistence de dieu, parce qu’il risque d’entraîner la désobéissance civile : c’est cette dernière qui constitue l’inacceptable absolu, pour notre Anonyme comme pour les lecteurs. Une conséquence paradoxale est que la thèse de l’imposture des religions est peut-être, pour des raisons politiques, moins inacceptable que cet amoralisme et surtout que le constat par l’Anonyme de l’inefficacité totale des religions. Enfin, les choses pouvant être dites plus ou moins haut, l’acceptabilité suppose plus de complicité et d’hypocrisie de la part du lecteur que nous aurions tendance

  9. Simulation temps réel pour la gestion des flux énergétiques dans l'habitat

    OpenAIRE

    Missaoui, Rim; Warkozek, Ghaith; Abras, Shadi; Ploix, Stéphane; Bacha, Seddik

    2010-01-01

    National audience; Le secteur de bâtiment représente 43% de la consommation totale du pays en énergie primaire. Pour cette raison, le bâtiment est considéré comme un énorme gisement potentiel d'économies d'énergie, d'où l'existence de nombreux travaux de recherche sur ce thème. Parmi ces derniers travaux, le projet ANR Multisol a proposé une solution pour la gestion des flux énergétique dans le bâtiment en gérant les équipements du système bâtiment. Or, pour valider des algorithmes de pilotag...

  10. Coefficient d'ajustement pour des processus de risque dans des contextes de dépendance

    OpenAIRE

    Cossette, Hélène; Marceau, Etienne; Maume-Deschamps, Véronique

    2009-01-01

    International audience; Nous étudions le coefficient d'ajustement de la théorie de la ruine dans un contexte de dépendance temporelle. Le coefficient d'ajustement, pour des données indépendantes a étudié par de nombreux auteurs. Nous utilisons ici la définition de Müller et Pflug pour des variables dépendantes. Nous construisons un estimateur consitant de ce coefficient dans un cadre de dépendance faible général. Pour des cas particuliers ayant un sens en théorie de la ruine / actuariat, nous...

  11. Nouvelle stratégie pour l'amélioration de la brillance d'une source VUV nanoseconde

    Science.gov (United States)

    Chénais, S.; Castex, M.-C.

    2006-10-01

    Nous présentons une technique simple pour améliorer d'un à deux ordres de grandeur l'énergie d'un rayonnement cohérent à 125 nm, obtenu par somme de fréquence résonante dans une vapeur de mercure à température ambiante. En focalisant sur la surface de mercure un laser ArF à 193 nm, le signal VUV est multiplié par 6, facteur qui peut s'élever jusqu'à ˜ 60 lorsque l'intensité des faisceaux fondamentaux est réduite. Cette expérience de validation ouvre de nombreuses opportunités d'amélioration pour une source VUV de forte brillance, applicable à la nanostructuration de matériaux pour l'optique.

  12. Efficacy of oral, injectable and pour-on formulations of moxidectin against gastrointestinal nematodes in cattle in New Zealand.

    Science.gov (United States)

    Leathwick, D M; Miller, C M

    2013-01-31

    The efficacy of moxidectin administered by different routes, against naturally acquired infections of gastrointestinal nematode parasites of cattle, was compared using faecal egg count reduction tests on 14 commercial farms throughout New Zealand. On each farm, groups of 15 calves were sampled for faecal nematode egg count and then treated with ivermectin administered orally, or with moxidectin administered either by the oral, subcutaneous injection or topical (pour-on) route. Samples were again collected 14 days after treatment and efficacy was calculated as the percentage reduction in-group mean egg count between the pre- and post-treatment samples. In addition, efficacy was calculated for individual animals, in order to compare the variability of the different treatments. On four farms untreated control groups were run and five animals from each of the control and all of the moxidectin-treated groups were bled over time to estimate plasma-moxidectin concentrations. Averaged across all tests, the reduction in faecal egg count was significantly greater after treatment with moxidectin oral (91.1%) than following treatment with moxidectin injection (55.5%) or with moxidectin pour-on (51.3%). Low efficacies were invariably against Cooperia oncophora. The oral treatments were significantly less variable in efficacy than the injection and pour-on treatments. Moxidectin concentrations in plasma were highest following subcutaneous injection and lowest following pour-on administration. Plasma levels following oral administration were intermediate, being significantly lower than post-injection and significantly higher than post-pour-on. There was no evidence of transfer of moxidectin to untreated animals through licking. Based on these results, along with those of other studies, it is proposed that oral administration of macrocyclic lactone anthelmintics results in higher concentrations of active reaching the target worms in the gastrointestinal tract than following either

  13. CERN Technical Training 2005: MAGNE-05 : Magnétisme pour l'électrotechnique

    CERN Multimedia

    Davide Vitè

    2005-01-01

    CERN Technical Training 2005: Learning for the LHC ! MAGNE-05 : Magnétisme pour l'électrotechnique Phénomènes magnétiques, matériaux et applications. MAGNE-05 est un cours dans le cadre du programme de l'Enseignement technique qui s'adresse aux personnes souhaitant découvrir, améliorer ou remettre à niveau leurs connaissances en magnétisme. Le cours est donné au CERN par la société CEDRAT Technologies basée à Meylan (France). La participation est ouverte à l'ensemble du personnel technique et scientifique nécessitant une formation en magnétisme dans le cadre de leurs activités professionnelles, courantes ou futures. Une importante économie par participant est réalisée par rapport aux frais nécessaires pour suivre la même formation sur le site de...

  14. CERN Technical Training 2005: MAGNE-05 : Magnétisme pour l'électrotechnique

    CERN Multimedia

    Davide Vitè

    2005-01-01

    CERN Technical Training 2005: Learning for the LHC ! MAGNE-05 : Magnétisme pour l'électrotechnique Phénomènes magnétiques, matériaux et applications. MAGNE-05 est un cours dans le cadre du programme de l'Enseignement technique qui s'adresse aux personnes souhaitant découvrir, améliorer ou remettre à niveau leurs connaissances en magnétisme. Le cours est donné au CERN par la société CEDRAT Technologies basée à Meylan (France). La participation est ouverte à l'ensemble du personnel technique et scientifique ayant besoin d'une formation en magnétisme dans le cadre de leurs activités professionnelles actuelles ou futures. Une importante économie par participant est réalisée par rapport aux frais nécessaires pour suivre la même formation sur le site de CEDRAT e...

  15. French literary language studies : Pour une anthropologie de la « langue française »

    Directory of Open Access Journals (Sweden)

    Alexandru Matei

    2014-12-01

    Full Text Available Les French Studies peuvent être pensées en tant qu’un type particulier d’agencement et d’encadrement d’éléments culturels français. Elles présentent deux caractéristiques définitoires : leur lieu de production n’est pas la France, mais le monde anglo-saxon, notamment les Etats-Unis et, en tant que production discursive portant cette marque d’origine, elles dispensent souvent de la pratique intensive de la langue française. C’est ce qui nous amène, en tant que suite possible aux recherches de Gilles Philippe, à proposer les French Literary Language Studies ayant pour objet la « langue littéraire » des espaces français et francophones, et pour méthode un croisement de sémiologie barthésienne, d’analyse thématique et d’histoire littéraire.

  16. Clef biblique pour coffre-for(t intérieur

    Directory of Open Access Journals (Sweden)

    Anne-Cécile Pottier-Thoby

    2002-11-01

    Full Text Available Pour cet écrivain américain francophone, la bibliothèque était un one man's land, un espace habité par une solitude que Julien Green cultivait et telle qu'il se sentait un peu chez lui dans tous les lieux de ce genre, effaçant ainsi la frontière entre espace privé et public. Éternel promeneur, inépuisable voyageur, ses chers livres ne le quittaient jamais. La bibliothèque reste pour Julien Green un lieu chargé de sens, un espace de conflagration où genèse et Apocalypse se répondent, où mort et [co]-naissance se rejoignent, un lieu hors du temps où la nostalgie des origines est plus prégnante, un de ces endroits où dieu et Diable se disputent le cœur d'un mortel.

  17. Logistique de transport pour le projet LHC enseignements des premiers secteurs

    CERN Document Server

    Prodon, S

    2003-01-01

    Ce papier dresse un premier bilan de la logistique de transport mise en place pour l'installation du LHC. Les moyens de planification mis en oeuvre seront tout d'abord évoqués avec notamment les réunions avec les groupes utilisateurs, l'élaboration de procédures de transport, la génération de listings d'articles à transporter ou encore l'établissement d'un planning des ressources. Cependant, les premiers travaux d'installation du LHC ont fait apparaître des divergences importantes entre le planning logistique établi et la réalité du terrain. Ces écarts seront analysés, qu'il s'agisse de différences sur le volume de matériel à acheminer, d'opérations non planifiées, de changements de plannings entraînant de longues et délicates traversées de chantiers ou de manque de planification des besoins en personnel dans certaines zones. Tous ces enseignements acquis au cours des premiers travaux devraient permettre de dégager des voies d'amélioration à mettre en place pour les prochains secteur...

  18. Guide pour la construction d'ensembles mécano-soudés conception - fabrication

    CERN Document Server

    Jubin, Laurent

    2016-01-01

    Le milieu des assemblages soudés dans la construction d’ensembles mécanosoudés et dans le secteur du levage et de la manutention a vu son environnement normatif évoluer de manière significative ces derniers temps. Les normes françaises NF E83-100 et NF E52-109, qui régissaient le secteur, ont été annulées, et les acteurs doivent dorénavant se conformer aux normes européennes ou internationales. Pour autant, ces normes françaises présentaient les règles de l’art en la matière et des aspects « métiers » utiles aux bureaux d’études, aux services méthodes et fabrications ainsi qu’aux sous-traitants du secteur, à qui elles servaient de références. C’est donc l’objet du présent rapport que de valoriser ces aspects « métiers », complétés par des retours d’expériences précis, tout en renvoyant aux textes européens et internationaux sur les aspects normatifs, leurs évolutions et leurs mises à jour. Ce rapport (9Q282) a pour but de conseiller les concepteurs et fabrica...

  19. Synthesis by Solution Polymerization of Polybehenyl Acrylate as Pour Point Depressant for Crude Oil

    Institute of Scientific and Technical Information of China (English)

    Song Zhaozheng; Ge Jijiang

    2004-01-01

    Behenyl acrylate is a kind of highly efficient pour point depressants. In order to promote the application of the pour pint depressant in transportation of crude oils, polybehenyl acrylate was synthesized by solution polymerization. These conclusions can be drawn from the experimental results that the sequence of chain transfer constants of four solvents is arranged in the following decreasing order: carbon tetrachloride (6.0×10-5)>chloroform (2.8×10-5)>methylbenzene (2.5×10-5)>tetrachloroethane (1.6×10-5). The average molecular weight of polybehenyl acrylate mainly depends on the chain transfer constant of the solvents. However, if the monomer conversion was higher than 35%, an abnormal phenomenon occurred, resulting in higher average molecular weight of polybehenyl acrylate obtained in methylbenzene solution compared to that obtained in tetrachloroethane solution. It was attributed to the influence of gelation on the average molecular weight of polybehenyl acrylate, which was stronger than the impact of chain transfer in methylbenzene.

  20. Le bureau d'études TS/CV/BE pour les besoins du projet LHC

    CERN Document Server

    Martel, C

    2004-01-01

    Le bureau d'études TS/CV/BE propose un appui technique personnalisé aux différentes sections du groupe TS/CV, responsables des projets liés aussi bien à la machine LHC, ses zones expérimentales, que d'autres projets associés. L'équipe, constituée historiquement et exclusivement de personnel d'entreprise extérieure, dispose d'un effectif variable, adapté à des besoins planifiés. Le choix d'utiliser les mêmes logiciels de CAO que la communauté du CERN, a limité la proportion de spécialistes au sein de l'équipe. Une méthodologie particulière a donc été mise en place pour satisfaire les demandes, tout en faisant face à l'étendue et à la complexité des installations de ventilation et de refroidissement. Des compétences externes spécialisées sont également sollicitées, au cas par cas, pour optimiser les coûts de fonctionnement.

  1. Hacking interdit découvrez les techniques des hackers pour mieux vous protéger

    CERN Document Server

    Gomez-Urbina, Alexandre

    2010-01-01

    Aujourd'hui, impossible de surfer sur Internet sans protection efficace ! Mais même avec des logiciels appropriés, nul n'est à l'abri du danger ! Virus, usurpations d'adresse IP, troyens, intrusions dans votre système, attaques par phishing : l'imagination des pirates est sans limite ! La seule solution est de vous protéger efficacement et pour cela, un moyen : connaître les techniques des hackers pour mieux déjouer leurs pièges ! Un internaute averti en vaut deux !

  2. Projet CrisFis : vers des solutions non crissantes de freins à disque haute-puissance pour le ferroviaire

    OpenAIRE

    2006-01-01

    La prise en compte des nuisances occasionnées par les systèmes de freinage sur l'environnement, la sécurité et la qualité de vie nécessite l'émergence d'actions technologiques nouvelles. Des solutions technologiques issues de la compréhension et de la modélisation des phénomènes physiques tels que le crissement peuvent maintenant être développés. Ce projet PREDIT-ADEME a pour but de traiter conjointement les aspects crissement et fissuration des freins à disques haute puissance pour le transp...

  3. Matériaux pour la dépollution des gaz d'échappement automobile

    Science.gov (United States)

    Mouaddib-Moral, N.; Gauthier, C.

    2002-04-01

    Les premières législations antipollution ont été mises en place suite à la détection, aux Etats Unis plus particulièrement en Californie, du smog photochimique et des pluies acides, néfastes pour la faune et la flore. Les estimations de la contribution de l'automobile aux émissions de composés, considérés comme précurseurs de ces phénomènes, ont été suffisantes pour provoquer la mise en place de normes draconiennes en matière d'émissions automobiles. Les matériaux catalytiques ont été évalués en tant que solution possible pour réduire les émissions à l'échappement. En Europe, l'utilisation des catalyseurs trois voies a été généralisée sur les véhicules essence fonctionnant à richesse stoechiométrique à partir de 1993. Une nouvelle génération de catalyseurs appelée piège à oxydes d'azote (NOx) est maintenant nécessaire pour le post-traitement des gaz d'échappement des motorisations à essence fonctionnant en mélange pauvre (combustion en présence d'un excès d'oxygène) pour diminuer la consommation et par conséquent réduire les émissions du CO2 connu pour son impact sur l'effet de serre. La dépollution des moteurs diesel via un catalyseur d'oxydation a été généralisée en Europe depuis 1996. La sévérisation des normes européennes impose pour les moteurs diesel le recours à des matériaux spécifiques pour le traitement des oxydes d'azotes et des particules par l'intermédiaire de filtres à particules dont l'efficacité de filtration est supérieure à 95%, mais doivent subir des régénérations périodiques.

  4. Un marketing générateur de contenus pour l’univers transmédia

    OpenAIRE

    Laurichesse, Hélène

    2015-01-01

    Hélène Laurichesse met en avant le phénomène de brand content et d’advertainment pour expliquer l’hybridité des contenus entre marketing et narration transmédia. À travers de nombreux exemples tirés du cinéma, de la télévision et des marques, elle montre comment les stratégies de transmedia storytelling sont réinvesties pour raconter des histoires et des univers comme des marques.

  5. Advances in Components for Active and Passive Airborne Sensors (Progres des Composants pour les Systemes des Detection Active et Passive Aeroportes)

    Science.gov (United States)

    1990-09-01

    At Ebectronique Serge Dassault do rda- los fibres pouvont 8tre pliios pour les antennes lisor des conceptions "tol~rantes aux variations TI3R-4 de...Les fibres peuvent inc 8tre un coinpo- ront donc on 616ment critique pour 1’efficacit6 sari essentiel des "peaux intelligentes " des des avions de

  6. Manufacture technique of semi-solid slurry of hypoeutectic Al-Si alloy by low superheat pouring and weak electromagnetic stirring

    Institute of Scientific and Technical Information of China (English)

    LIU Zheng; MAO Wei-ming; ZHAO Zheng-duo

    2006-01-01

    The semi-solid slurry of hypoeutectic Al-Si alloy was manufactured by low superheat pouring and weak electromagnetic stirring. The effects of pouring temperature and stirring power on the semi-solid slurry making process were investigated. The results indicate that the semi-solid slurry to satisfy rheocasting requirement can be made by a combination of low superheat pouring and weak electromagnetic stirring. The pouring temperature (or superheat) and the stirring power significantly affect the morphology and the size of primary α-Al, while there is no obvious effect of the stirring time on primary α-Al. Compared with the samples made by low superheat pouring without stirring, the nucleation rate,particle morphology and grain size of primary α-Al in A356 Al alloy are markedly improved by a process of applying both low superheat pouring and weak electromagnetic stirring. Under the condition of weak electromagnetic stirring applied, the pouring temperature with low superheat can be equivalerttly to reach the effectiveness obtained from the even lower pouring temperature without stirring.

  7. Manufacture technique of semi-solid slurry of hypoeutectic Al-Si alloy by low superheat pouring and weak electromagnetic stirring

    Directory of Open Access Journals (Sweden)

    LIU Zheng

    2006-05-01

    Full Text Available The semi-solid slurry of hypoeutectic Al-Si alloy was manufactured by low superheat pouring and weak electromagnetic stirring. The effects of pouring temperature and stirring power on the semi-solid slurry making process were investigated. The results indicate that the semi-solid slurry to satisfy rheocasting requirement can be made by a combination of low superheat pouring and weak electromagnetic stirring. The pouring temperature (or superheat and the stirring power significantly affect the morphology and the size of primary α-Al, while there is no obvious effect of the stirring time on primary α-Al. Compared with the samples made by low superheat pouring without stirring, the nucleation rate, particle morphology and grain size of primary α-Al in A356 Al alloy are markedly improved by a process of applying both low superheat pouring and weak electromagnetic stirring. Under the condition of weak electromagnetic stirring applied, the pouring temperature with low superheat can be equivalently to reach the effectiveness obtained from the even lower pouring temperature without stirring.

  8. Relationship between the Composition of Polymer of n-Alkyl Substituted Acrylate and Vinyl Amine and Their Performance on Pour Point Depression

    Institute of Scientific and Technical Information of China (English)

    Jiang Qingzhe; Luo Fangmin; Song Zhaozheng; Ke Ming

    2005-01-01

    Polymer of n-alkyl substituted acrylate (PA) with the alkyl side chains C16- 30 were synthesized.Their crystallinity, solubility and effect on pour point depression were studied. Results showed that only carbon atoms located far away from polar groups of PA pour point depressants participated in crystallization.When the number of carbon atoms that participated in crystallization is about three fourths of the average carbon number of wax in crude, the effect of PA is the best. The molecular weight distribution of PA pour point depressant has little influence on the effect of pour point depression, and the average molecular weight of PA in the range of (1.5- 2.2)× 104 shows the best effect. The introduction of polar groups into the molecule of PA can improve its performance. However, a too high content of polar groups in PA would cause deterioration, and even lead to loss of PA's performance for pour point depression.

  9. Quels dispositifs de conseil pour l’agriculture familiale marocaine ? Réflexions pour une démarche de conception des dispositifs de conseil.

    Directory of Open Access Journals (Sweden)

    Patrick Dugué

    2014-03-01

    Full Text Available Dans le cadre de sa politique agricole actuelle structurée autour du Plan Maroc vert, L’Etat a engagé une réforme en profondeur du conseil agricole, service qui était essentiellement assuré par les Centres des Travaux et les Centres de Mise en Valeur. La Nouvelle Stratégie du Conseil Agricole prône d’associer aux services publics de conseil agricole des structures privées qui seront agréées par les pouvoirs publics. Sur la base de travaux de recherche et d’expertise, cet article aborde la diversification de l’offre de conseil (conseil technique mais aussi conseil de gestion pour les exploitations et les organisations professionnelles agricoles, conseil administratif et juridique, … et des publics cibles (chefs d’exploitations, les autres actifs familiaux, les responsables et salariés des organisations professionnelles agricoles, …. Il suggère de prendre en considération d’autres opérateurs actuels ou potentiels du conseil comme les agrofournisseurs, les organisations professionnelles agricoles bien structurées et les agro-industries. Au-delà de ces propositions, l’article aborde les principes d’une démarche générique de conception de dispositifs de conseil utile à tous les acteurs au niveau local, régional ou national.

  10. D’une problématique locale-frontalière à un enjeu binational : le cas de la contrebande transfrontalière de carburants entre la Colombie et le Venezuela

    Directory of Open Access Journals (Sweden)

    Amanda Andrade Benitez

    2011-10-01

    Full Text Available Cet article propose d’appréhender le processus d’inscription de la question de la contrebande transfrontalière de carburants dans l’agenda d’intégration binational entre la Colombie et le Venezuela. Peu de travaux s’intéressent à ce sujet qui est habituellement abordé dans une perspective de politique intérieure et non pas extérieure. Notre étude s’inscrit dans le cadre théorique de la « mise en agenda » traitée par Cobb et Elders (1983 et des travaux de Jones et Baumgartner (2005 sur l’évolution de l’agenda politique après l’introduction de nouveaux enjeux. Elle vise à comprendre la manière dont la contrebande de carburants trouve une place dans l’agenda d’intégration énergétique bilatéral et devient un enjeu de coopération entre les deux pays. Les effets économiques de la contrebande ainsi que ses conséquences sur la sécurité de la frontière ont été des facteurs déterminants dans la signature d’un accord entre les deux pays. Les agences énergétiques de Colombie et du Venezuela ont été les acteurs privilégiés du processus d’inscription du problème dans l’agenda d’intégration entre les deux pays.This article analyzes the gradual inclusion of the illegal oil trade in the binational integration agenda between Venezuela and Colombia. Few scholars have focused on this question, which is generally examined through the prism of domestic –not foreign– policy. This study borrows from Cobb and Elders’ (1983 agenda setting theory and its development by Jones and Baumgartner (2005 on the evolution of political agendas following the incorporation of new issues. The purpose is to understand the ways in which illegal oil trade found its place in the bilateral energy integration agenda and became the subject of cooperation between Venezuela and Colombia. The economic effects of this illegal traffic along with its consequences on border security were crucial factors in the signing of a

  11. 奥氏体不锈钢低温渗碳硬化处理后的化学亮化处理%Chemical Brightening Treatment of Austenitic Stainless Steel after Low-temperature Plasma Carburizing

    Institute of Scientific and Technical Information of China (English)

    王扬亚; 赵程

    2016-01-01

    目的 研究一种化学方法对经过低温离子渗碳后的奥氏体不锈钢表面进行亮化处理. 方法 采用酸洗(草酸180~200 g/L,硫脲10~15 g/L,OP-10 10~15 mL/L,温度为70 ℃,时间为3 min)、除积炭(邻二氯苯610 g/L,水30 g/L,氢氧化钠20 g/L,油酸100 g/L,甲酚240 g/L,处理温度为70 ℃,在超声波中清洗120 min)、碱洗(氢氧化钠110 g/L,碳酸钠110 g/L,高锰酸钾50 g/L,溶液温度为70℃,在超声波中清洗30 min.)、再酸洗(草酸180~200 g/L,硫脲10~15 g/L,OP-10 10~15 mL/L,溶液温度为70 ℃,在超声波中清洗1 min)的化学处理过程,对低温离子渗碳硬化处理后的316 L奥氏体不锈钢表面进行亮化处理,并对亮化处理前后硬化层的组织结构、厚度、硬度及耐蚀性能进行比较. 结果 硬化处理后的不锈钢经过化学亮化处理过程,就可以比较彻底地去除硬化层表面的黑膜,恢复不锈钢的本色. 结论 化学表面亮化处理后,不锈钢渗硬化层的损失量比较小,去除黑膜后的不锈钢表面表现出很好的耐蚀性能.%Objective To study the method of chemical brightening treatment for austenitic stainless steel after low-temperature plasma carburizing. Methods This paper adopted chemical treatment method to brighten the surface of the carburized 316L austen-ite stainless steel. The chemical treatments included acid-washing(180~200 g/L of oxalic acid,10~15 g/L of thiourea, 10~15 mL/L of OP-10,the temperature was 70 ℃, the time was 3 minutes), removing accumulated carbon (610 g/L of orthodichlorobe-zene,30 g/L of water,20 g/L of sodium hydroxide,100 g/L of oleic acid, 240 g/L of cresol, the temperature was 70℃, ultrosonic cleaning for 120 minutes), alkali-washing (110 g/L of sodium hydroxide,110 g/L of sodium carbonate,50 g/L of potassium per-manganate, the temperature was 70 ℃, ultrosonic cleaning for 30 minutes) and acid-washing (180~200 g/L of oxalic acid,10~15 g/L of thiourea, 10~15 mL/L of OP-10, the temperature was

  12. Hernie inguinale en Afrique subsaharienne: quelle place pour la technique de Shouldice?

    Science.gov (United States)

    Traoré, Drissa; Diarra, Lasseny; Coulibaly, Bréhima; Bengaly, Brehima; Togola, Birama; Traoré, Alhassane; Traoré, Hamady; Ongoïba, Nouhoum; Sissoko, Filifing; Koumaré, Abdel Karim

    2015-01-01

    L'objectif était d’étudier l'aspect épidémio-clinique et thérapeutique de la hernie inguinale selon la technique de Shouldice. Nous avons réalisé une étude rétrospective, portant sur les patients opérés pour hernie inguinale selon la technique de Shouldice dans le service de chirurgie B du CHU du Point G, Bamako, Mali. Il a été enregistré 225patients opérés selon la technique de Shouldice. L’âge moyen était de 49 ans +/- 17,7. Il y avait 90,7% (204) hommes soit un sex-ratio de 9,7. Les cultivateurs, les ménagères et les ouvriers ont représenté 51,1% (115). Dans 75,2% (169) les patients ont consulté pour tuméfaction inguinale. En pré opératoire, la hernie était compliquée chez 82 (36,4%) patients dont 24 cas de récidive. L’étranglement herniaire a été la principale complication pré opératoire 58,5% (48/82). Les suites opératoires à un an ont été simples chez 94,2%(210) des patients; elles étaient marquées par 8 cas de récidive, 4 cas de névralgie, 2 cas d'atrophie testiculaire, 1 cas de chéloïde. La technique de Shouldice est la technique de choix pour la cure de la hernie inguinale dans les pays en voie de développement à cause du bon résultat et son coût peu onéreux par rapport aux autres techniques utilisant des dispositifs médicaux. PMID:26664551

  13. Proposition de Mesures Magnétiques pour le Projet AD (hormis les dipôles de correction)

    CERN Document Server

    Cornuet, D

    1997-01-01

    Pour le projet AD (Antiproton Decelerator), c'est la machine AC (Antiproton Collector) qui va être utilisée. Mais il s'agit non plus de fonctionner à courant constant (correspondant à 3,57 GeV/c) mais de décélérer le faisceau d'antiprotons à courant variable et stabilisation sur différents paliers décroissants (3,57 GeV/c, 2 GeV/c, 300 MeV/c pour le refroidissement) afin d'éjecter à basse énergie (correspondant à 100 MeV/c). Les aimants de la machine AC avaient été shimmés et optimisés pour 3,57 GeV/c (références 1 et 2). Dans ce nouveau contexte de la machine AD, il convient de vérifier si un compromis des shimmings existants ne doit pas être trouvé pour obtenir une homogénéité de champ à toutes énergies. Il faut vérifier aussi que les courants de Foucault induits dans les chambres à vide rectangulaires ne perturbent pas la qualité de champ. La possibilité d'utiliser des sondes NMR comme marqueurs de train B est aussi étudiée.

  14. Cycles optimaux pour des lignes de traitement de surface à trois cuves avec marges infinies ou nulles

    OpenAIRE

    2002-01-01

    National audience; Dans cette communication, nous démontrons que, pour une ligne de traitements de surface comportant trois cuves, les cycles optimaux sont des 1-cycles ou des 2-cycles, si les tolérances sur les durées de trempe sont nulles ou infinies et les temps de trempe minimaux égaux.

  15. "Tele Pour Tous" in Rural Ivory Coast: Audience, Impact, Perceptions: Report of Two Surveys Conducted in January and April, 1977.

    Science.gov (United States)

    Etaix, Mireille; Lenglet, Frans

    This report presents the results of two surveys conducted in January and April 1977 in the Ivory Coast to assess the impact of the "Tele Pour Tous" programs on rural audiences in terms of awareness, learning, and action. Descriptions of the socio-economic characteristics of the audience and their viewing patterns were sought, and…

  16. Sécurité informatique ethical hacking : apprendre l'attaque pour mieux se défendre

    CERN Document Server

    ACISSI

    2009-01-01

    Ce livre sur la sécurité informatique (et le ethical hacking) s'adresse à tout utilisateur d'ordinateur sensibilisé au concept de la sécurité informatique. Il a pour objectif d'initier le lecteur aux techniques des attaquants pour lui apprendre comment se défendre. ACISSI (Audit, Conseil, Installation et Sécurisation des Systèmes d'Information) est une association à but non lucratif qui forme et conseille, depuis plusieurs années, sur les enjeux de la sécurité informatique. Les auteurs de ce livre sont bien sûr membres actifs de l'association, chacun détenteur d'une spécialité, et forment une équipe de personnes de conviction qui se donnent pour mission de rendre la sécurité informatique accessible à tous : ""apprendre l'attaque pour mieux se défendre"" est leur adage. Hackers blancs dans l'âme, ils ouvrent au lecteur les portes de la connaissance underground. Aperçu de la table des matières : Introduction et Définitions - La méthodologie d'une attaque - Le Social Engineering - Les ...

  17. S'appuyer sur l'ergonomie pour concevoir une machine directive "Machines" 2006/42/CE

    CERN Document Server

    Bossard, Pascale; Grandjacques, Benoît; Seitier, Sylvie; Thibault, Jean-François

    2012-01-01

    L'ergonomie est désormais au centre des préoccupations dès lors qu'il s'agit de concevoir des machines. Pour le législateur, très alerte vis-à-vis de cette problématique, l'objectif est avant tout d'aboutir à une meilleure préservation de la santé et de la sécurité des opérateurs. Cet ouvrage, oeuvre commune du Cetim, de la FIM et de l'Anact, a pour objectif de mettre à disposition une méthode commune qui intègre à la fois prévention, notamment des facteurs de pénibilité, réglementation, normalisation et ergonomie. Une publication inédite mêlant deux approches pour une méthodologie commune : celle de l'ingénieur industriel oeuvrant pour l'intégration de la sécurité des machines et la vision d'une agence nationale intervenant dans le domaine de l'amélioration des conditions de travail, en particulier de l'ergonomie.

  18. Mesures magnétiques des quadripôles QDW37 et QFW40 pour le projet AD

    CERN Document Server

    Chritin, R

    2000-01-01

    Pour le AD (Antiproton Decelerator) c'est la machine AC (Antiproton Collector) qui est utilisée. Mais il s'agit non plus de fonctionner à courant constant, correspondant à 3.57 GeV/c (voir réf. 3) mais de décélérer le faisceau d'antiprotons à courant variable et stabilisation sur différents paliers (voir ref. 6) décroissants (3.57 GeV/c, 2 GeV/c, 300 GeV/c pour le refroidissement) afin d'éjecter à basse énergie correspondant à 100 MeV/c (voir ref. 4).Les aimants de la machine AC avaient été shimmés et optimisés pour 3.57 GeV/c (Réf. [1, 2, 3]).Dans ce nouveau contexte de la machine AD, il convient de vérifier comment varie l'homogénéité des gradients et des sextupôles aux différentes énergies.Cette note décrit ces vérifications effectuées sur deux quadripôles type WSS (pour Wide Strong Sextupole) à savoir QDW37 à 17 spires / pôle et QFW40 à 20 spires / pôle.

  19. Implementering af ny instruks for forebyggelse af Post Operativ Urin Retention (POUR) i forhold til den hoftealloplastik opererede patient

    DEFF Research Database (Denmark)

    Bagger, Bettan; Bech Hansen, Anette; Hørdam, Britta

    2013-01-01

    Pro-hip www.prohip.eu har til formål at evidensbasere den rehabiliterende sygepleje til hoftepatienten i forhold til indsatsområderne; ernæring, urinretention/UVI, delir og tryksår. På baggrund af flere erfaringer med forekomst af POUR hos den hoftealloplastik opererede patient på Næstved Hospital...

  20. "Paraffin wax-overlay of pour plate", a method for the isolation and enumeration of purple non-sulfur bacteria.

    Science.gov (United States)

    Archana, A; Sasikala, Ch; Ramana, Ch V; Arunasri, K

    2004-12-01

    A modification of pour plate technique with an overlay of wax was used for isolation and enumeration of purple non-sulfur bacteria (PNSB) with equal efficiency as that of agar shake culture. The total count of PNSB ranged from 10(5)-10(8) CFU g dry soil(-1) and belonged to the genera of Rhodobacter, Rhodopseudomonas, Rhodocista and Rubrivivax.