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Sample records for carburization

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

    Directory of Open Access Journals (Sweden)

    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.

  2. 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.

  3. 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.)

  4. 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.

  5. 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.

  6. Diagnosis of Carburized Degradation in Cracking Tube by Ultrasonic Wave

    International Nuclear Information System (INIS)

    The ultrasonic method, which is well known as non-destructive test method, is widely used to evaluate the material damage caused by degradation practically. However, this method is just used for measuring the crack size and the thickness loss of tube. The purpose of this study is to investigate the applicability of the ultrasonic technique for the evaluation of carburized material and to suggest the correlations between the ultrasonic characteristics and carburized degradation. The miniaturized specimens(40x20x6.3mm) are adopted from the HK-40 (25Cr-20Ni-0.4C) centrifugal cast tube after carburization treatment. Carburization was carried at 1200 .deg. C by the pack method. The results of ultrasonic test present that the longitudinal wave velocity increased with the increase of carburized depth. The correlation between the longitudinal wave velocity and carburization was changed with the density and Young's modulus. Therefore, the average velocity in the materials carburized for 336 hours and the unused one were 5,840 m/s and 5,755 m/s at 5 MHz, respectively. With the obtained results from this study, it can be recognized that the technique using the ultrasonic velocity property is very useful method to evaluate the degree of carburized material non-destructively

  7. 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

  8. 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.

  9. 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.

  10. Carburization of stainless steel furnace tubes

    International Nuclear Information System (INIS)

    Stainless steel containing molybdenum are usually recommended to resist naphtenic acid corrosion in vacuum heaters. In 1993 the original 5Cr-1/2Mo roof tubes of the furnace in a vacuum unit were replaced by stainless steel 316 Ti to minimize tube replacement and increase heater reliability. Unexpectedly, some of the new tubes failed after only three years of service and just one year after undergoing the last inspection. The damage occurred in the form of deep holes and perforations, starting from the outside tube surface on the fireside. Coke build-up occurred due to severe operating conditions, overheating the tubes on the fireside, above 675 Centigrade. Metallographic and Scanning Electron Microscopy (Sem) examination revealed internal and external carburization of the material due to the presence of coke and combustion ashes, respectively. The increase in the skin metal temperature facilitated the diffusion of carbon from these carbon-rich deposits into the low carbon content material (0.023%). Depletion of chromium at the grain boundaries due to the massive formation of chromium carbides, resulted in a severe intergranular corrosion attack by molten salts rich in vanadium and sulfur produced by asphalt burning. Normal operating practice demands the use of steam for the heater tubes to control coke build-up. This practice had been first reduced and then eliminated, during the past two years prior to the failure, because of economic incentives. This paper describes the root cause analysis conducted to account for these premature tube failures. (Author)

  11. The Corrosion Behavior of Carburized Aluminum Using DC Plasma

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    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.

  12. Creep properties of Hastelloy X in a carburizing helium environment

    International Nuclear Information System (INIS)

    In this work, we investigate the environmental effect on the creep behavior of Hastelloy X at 9000C in helium and air. Since helium coolant in HTGR is expected to be carburizing and very weakly oxidizing for most metals, testings were focused on the effect of carburizing and slight oxidation. Carburization decreases secondary creep strain rate and delays tertiary creep initiation. On the other hand, the crack growth rate on the specimen surface is enhanced due to very weak oxidation in helium, therefore the tertiary creep strain rate becomes larger than that in air. The rupture time of Hastelloy X was shorter in helium when compared with in air. Stress versus rupture time curves for both environments do not deviate with each other during up to 5000 hours test, and a ratio of rupture stress in helium to that in air was about 0.9

  13. 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.

  14. 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.

  15. 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.

  16. Carburization of austenitic alloys by gaseous impurities in helium

    International Nuclear Information System (INIS)

    The carburization behavior of Alloy 800H, Inconel Alloy 617 and Hastelloy Alloy X in helium containing various amounts of H2, CO, CH4, H2O and CO2 was studied. Corrosion tests were conducted in a temperature range from 649 to 10000C (1200 to 18320F) for exposure time up to 10,000 h. Four different helium environments, identified as A, B, C, and D, were investigated. Concentrations of gaseous impurities were 1500 μatm H2, 450 μatm CO, 50 μatm CH4 and 50 μatm H2O for Environment A; 200 μatm H2, 100 μatm CO, 20 μatm CH4, 50 μatm H2O and 5 μatm CO2 for Environment B; 500 μatm H2, 50 μatm CO, 50 μatm CH4 and 2O for Environment C; and 500 μatm H2, 50 μatm CO, 50 μatm CH4 and 1.5 μatm H2O for Environment D. Environments A and B were characteristic of high-oxygen potential, while C and D were characteristic of low-oxygen potential. The results showed that the carburization kinetics in low-oxygen potential environments (C and D) were significantly higher, approximately an order of magnitude higher at high temperatures, than those in high-oxygen potential environments (A and B) for all three alloys. Thermodynamic analyses indicated no significant differences in the thermodynamic carburization potential between low- and high-oxygen potential environments. It is thus believed that the enhanced carburization kinetics observed in the low-oxygen potential environments were related to kinetic effects. A qualitatively mechanistic model was proposed to explain the enhanced kinetics. The present results further suggest that controlling the oxygen potential of the service environment can be an effective means of reducing carburization of alloys

  17. 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

  18. 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.

  19. 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...

  20. Fatigue crack propagation in carburized X-2M steel

    Science.gov (United States)

    Averbach, B. L.; Lou, Bingzhe; Pearson, P. K.; Fairchild, R. E.; Bamberger, E. N.

    1985-07-01

    The growth rates of fatigue cracks propagating through the case and into the core have been studied for carburized X-2M steel (0.14 C, 4.91 Cr, 1.31 Mo, 1.34 W, 0.42 V). Fatigue cracks were propagated at constant stress intensities, ΔK, and also at a constant cyclic peak load, and the crack growth rates were observed to pass through a minimum value as the crack traversed the carburized case. The reduction in the crack propagation rates is ascribed to the compressive stresses which were developed in the case, and a pinched clothespin model is used to make an approximate calculation of the effects of internal stress on the crack propagation rates. We define an effective stress intensity, Ke = Ka + Ki, where Ka is the applied stress intensity, Ki = σid{i/1/2}, σi is the internal stress, and di is a characteristic distance associated with the depth of the internal stress field. In our work, a value of di = 11 mm (0.43 inch) fits the data quite well. A good combination of resistance to fatigue crack propagation in the case and fracture toughness in the core can be achieved in carburized X-2M steel, suggesting that this material will be useful in heavy duty gears and in aircraft gas turbine mainshaft bearings operating under high hoop stresses.

  1. Cluster carburizing. Final report, June 1, 1973-May 31, 1979

    International Nuclear Information System (INIS)

    Three major accomplishments of the cluster carburizing program were showing that the hardness of aged and carburized materials could be controlled via the aged structure; developing a new and analytical theory of subscale formation; and characterizing the properties of Ta-Hf alloys with respect to precipitation kinetics and morphology, diffusion kinetics, age hardening, and subscale formation. The first of these verified the cluster carburizing concept, which has potential use in the development of high strength materials. The second has applications in the fields of hot corrosion, oxidation, and high temperature coatings. The third provided necessary background for this study and provided a further understanding of the behavior of refractory metals. Details about the above are contained in this final report as well as comments on the Ta-Hf, TaC-HfC and NbC-HfC phase diagrams, a comparison of hardening in the Nb-Hf and Ta-Hf system, and a discussion of possible future work

  2. Comparative of wear resistance of low carbon steel pack carburizing using different media

    Directory of Open Access Journals (Sweden)

    Kharia Salman Hassan

    2015-01-01

    Full Text Available In this study, various carburizing compounds charcoal, cow bone, CaCO3 were added as energizer for the carburizing compounds in percentage of 10%. To produce another compound to pack carburized mild steel 1020 AISI for investigates the influence of these compounds on wear resistance. Many Cylindrical specimens for the adhesion wear tests were prepared from the used metal with dimensions (10x20mm according to ASTM (G99-04 specifications Three Heat Treatment process namely pack Carburizing Quenching, and Tempering were done. Firstly the mild steels specimens are carburized at 925° C for 2hr as soaking time and slow cooling in furnace then carburizing specimens were re heating to 870 °C for half hr. and water Quenching .Tempering was done at 160°C for 1 hour and air cooled. the Carburized and Tempered mild steels are subjected for different kind of test such as Adhesive Wear Test with pin on desk method, Hardness Test were taken using Vickers micro-hardness tester and optical microscope is used for microstructure examination X-ray diffraction for phases observation. The result showed that all carburizing compound were contributed in increasing wear resistance and the compound of cow bone with 10% CaCO3 as energizer had a carburizing case depth of 2.32 mm which gives the highest wear resistance while charcoal compound gives a case depth of 1.1 mm .The work shows that cow bone can be used as compounds and energizer in pack carburization of mild steel. The hardness profile plot of the 90 wt.% 10% caco3 cow bone carburized mild steel was also higher than the other compositions and this value contributed on improvements of wear resistance.

  3. 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.

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

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    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 .

  5. 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.

  6. 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.

  7. 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.

  8. 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.……

  9. 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°.

  10. 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.

  11. Fatigue crack propagation in carburized high alloy bearing steels

    Science.gov (United States)

    Averbach, B. L.; Lou, Bingzhe; Pearson, P. K.; Fairchild, R. E.; Bamberger, E. N.

    1985-07-01

    Fatigue cracks were propagated through carburized cases in M-50NiL (0.1 C,4 Mo, 4 Cr, 1.3 V, 3.5 Ni) and CBS-1000M (0.1 C, 4.5 Mo, 1 Cr, 0.5 V, 3 Ni) steels at constant stress intensity ranges, ΔK, and at a constant cyclic peak load. Residual compressive stresses of the order of 140 MPa (20 Ksi) were developed in the M-50NiL cases, and in tests carried out at constant ΔK values it was observed that the fatigue crack propagation rates, da/dN, slowed significantly. In some tests, at constant peak loads, cracks were stopped in regions with high compressive stresses. The residual stresses in the cases in CBS-1000M steel were predominantly tensile, probably because of the presence of high retained austenite contents, and da/dN was accelerated in these cases. The effects of residual stress on the fatigue crack propagation rates are interpreted in terms of a pinched clothespin model in which the residual stresses introduce an internal stress intensity, Ki where Ki, = σid{i/1/2} (σi = internal stress, di = characteristic distance associated with the internal stress distribution). The effective stress intensity becomes Ke = Ka + Ki where Ka is the applied stress intensity. Values of Ki were calculated as a function of distance from the surface using experimental measurements of σi and a value of di = 11 mm (0.43 inch). The resultant values of Ke were taken to be equivalent to effective ΔK values, and da/dN was determined at each point from experimental measurements of fatigue crack propagation obtained separately for the case and core materials. A reasonably good fit was obtained with data for crack growth at a constant ΔK and at a constant cyclic peak load. The carburized case depths were approximately 4 mm, and the possible effects associated with the propagation of short cracks were considered. The major effects were observed at crack lengths of about 2 mm, but the contributions of short crack phenomena were considered to be small in these experiments, since the

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

    International Nuclear Information System (INIS)

    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 10-4 s-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 μm. 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-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.

  13. Pulsed ion beam-assisted carburizing of titanium in methane discharge

    International Nuclear Information System (INIS)

    The carburizing of titanium (Ti) is accomplished by utilizing energetic ion pulses of a 1.5 kJ Mather type dense plasma focus (DPF) device operated in methane discharge. X-ray diffraction (XRD) analysis confirms the deposition of polycrystalline titanium carbide (TiC). The samples carburized at lower axial and angular positions show an improved texture for a typical (200)TiC plane. The Williamson–Hall method is employed to estimate average crystallite size and microstrains in the carburized Ti surface. Crystallite size is found to vary from ∼ 50 to 100 nm, depending on the deposition parameters. Microstrains vary with the sample position and hence ion flux, and are converted from tensile to compressive by increasing the flux. The carburizing of Ti is confirmed by two major doublets extending from 300 to 390 cm−1 and from 560 to 620 cm−1 corresponding to acoustic and optical active modes in Raman spectra, respectively. Analyses by scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS) have provided qualitative and quantitative profiles of the carburized surface. The Vickers microhardness of Ti is significantly improved after carburizing. (nuclear physics)

  14. 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.

  15. Carburization of high-temperature materials. Pt. 1

    International Nuclear Information System (INIS)

    Metallic materials often exhibit a change in structure in high temperature applications caused by the penetration of a foreign element and the precipitation of compounds of this element. This change in structure influences the mechanical properties and may be the lifetime-limiting factor. The kinetics of this process can be described by a simple time law only in the case, where certain restrictive conditions are given - for instance an extremely small solubility product for the forming compound. In this work a computation method is presented, which allows a calculation of the reaction progress under more general conditions. The method is based on the solution of differential equations by the use of the finite difference technique. The basic relations are derived from considerations of the processes of diffusion, precipitation and transformation for the case of carburization. The difference between the numerical result and the analytical solution is demonstrated in an example with restrictive conditions, and the possibilities for applications of the method are discussed. (orig.)

  16. 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)

  17. 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.

  18. 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.

  19. 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.

  20. Control and optimization of new patented induction carburizing technology by infrared temperature controlling system

    International Nuclear Information System (INIS)

    The New Induction Carburizing Technology is a simple, short, and inexpensive processing method for metal surface layer properties improving. The Part to be carburized along with an inductive heater are immersed in a liquid active medium and its surface is heated by high-frequency current. Processing time estimates in seconds or minutes only. Thickness, chemical composition, structure and properties of the protective diffusion surface layers can be adjusted for various applications by control and optimization of treatment parameters. It was done by infrared temperature controlling system which peculiarities are explained in this presentation. (author)

  1. Did the First Iron Blacksmiths Learn to Carburize Iron? Part I: Can Iron be Carburized in a Charcoal-Fired Furnace?

    Science.gov (United States)

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

    2016-08-01

    There is debate in the literature on whether or not iron can be carburized by simply inserting an iron bar into a charcoal fire. Experiments are presented here in which wrought iron bars have been held in a cylindrical enclosure filled with burning charcoal produced by air flowing up from tuyeres at the bottom with the bottom end of the bars held in the 900°C-1050°C range for 30 min. The bars carburized to a remarkable extent. Martensite case depths on a water-quenched bar were measured ranging from 0.75 mm at the hot bottom end and dropping to 0.02 mm at a distance of 295 mm (11.6 inches) up the bar. The surface of the bar was file hard over this length with measured surface hardnesses in the 60-65 Rc range.

  2. Carburization behavior of AISI 316LN austenitic stainless steel - Experimental studies and modeling

    Science.gov (United States)

    Sudha, C.; Sivai Bharasi, N.; Anand, R.; Shaikh, H.; Dayal, R. K.; Vijayalakshmi, M.

    2010-07-01

    AISI type 316LN austenitic stainless steel was exposed to flowing sodium at 798 K for 16,000 h in the bi-metallic (BIM) sodium loop. A modified surface layer of 10 μm width having a ferrite structure was detected from X-ray diffraction and electron micro probe based analysis. Beneath the modified surface layer a carburized zone of 60 μm width was identified which was found to consist of M 23C 6 carbides. A mathematical model based on finite difference technique was developed to predict the carburization profiles in sodium exposed austenitic stainless steel. In the computation, effect of only chromium on carbon diffusion was considered. Amount of carbon remaining in solution was determined from the solubility parameter. The predicted profile showed a reasonably good match with the experimental profile. Calculations were extended to simulate the thickness of the carburized layer after exposure to sodium for a period of 40 years. Attempt was also made to predict the carburization profiles based on equilibrium calculations using Dictra and Thermocalc which contain both thermodynamic and kinetic databases for the system under consideration.

  3. Carburization behavior of AISI 316LN austenitic stainless steel - Experimental studies and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Sudha, C. [Physical Metallurgy Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Sivai Bharasi, N. [Corrosion Science and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Anand, R. [Physical Metallurgy Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Shaikh, H., E-mail: hasan@igcar.gov.i [Corrosion Science and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Dayal, R.K. [Corrosion Science and Technology Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); Vijayalakshmi, M. [Physical Metallurgy Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India)

    2010-07-31

    AISI type 316LN austenitic stainless steel was exposed to flowing sodium at 798 K for 16,000 h in the bi-metallic (BIM) sodium loop. A modified surface layer of 10 {mu}m width having a ferrite structure was detected from X-ray diffraction and electron micro probe based analysis. Beneath the modified surface layer a carburized zone of 60 {mu}m width was identified which was found to consist of M{sub 23}C{sub 6} carbides. A mathematical model based on finite difference technique was developed to predict the carburization profiles in sodium exposed austenitic stainless steel. In the computation, effect of only chromium on carbon diffusion was considered. Amount of carbon remaining in solution was determined from the solubility parameter. The predicted profile showed a reasonably good match with the experimental profile. Calculations were extended to simulate the thickness of the carburized layer after exposure to sodium for a period of 40 years. Attempt was also made to predict the carburization profiles based on equilibrium calculations using Dictra and Thermocalc which contain both thermodynamic and kinetic databases for the system under consideration.

  4. RESULTS OF CHARACTERIZATION TESTS OF THE SURFACES OF A COMMERCIALLY CARBURIZED AUSTENITIC STAINLESS STEEL

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, K

    2004-01-07

    A commercial surface carburization treatment that shows promise for hardening the surfaces of the stainless steel target vessel of the Spallation Neutron Source against cavitation erosion and pitting caused by the action of pulsed pressure waves in the liquid mercury target has been investigated. To verify promotional claims for the treatment and to uncover any factors that might be of concern for the integrity of a carburized target vessel, some characterization tests of the nature of the surface layers of carburized austenitic 316LN stainless steel were conducted. The findings support most of the claims. The carburized layer is about 35 {micro}m thick. Its indentation hardness is about five times larger than that of the substrate steel and declines rapidly with depth into the layer. The surface is distorted by the treatment, and the austenite lattice is enlarged. The corrosion resistance of the carburized layer in an acid medium is greater than that for untreated austenite. The layer is not brittle; it is plastically deformable and is quite resistant to cracking during straining. Contrary to the provider's assertations, the maximum carbon content of the layer is much less than 6-7 wt% carbon, and the carbon is not simply contained in supersaturated solid solution; some of it is present in a previously unreported iron carbide phase located at the very surface. Large variations were found in the thickness of the layer, and they signify that controls may be needed to ensure a uniform thickness for treatment of the SNS target vessel. Inclusion stringers and {delta}-ferrite phase embraced in the treated layer are less resistant to chemical attack than the treated austenite. From a cavitation pitting perspective under SNS bombardment, such non-austenitic phases may provide preferential sites for pitting. The shallow depth of the hardened layer will require use of protection measures to avoid mishandling damage to the layer during assembly and installation of a

  5. 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...

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Optimization and control of a plasma carburizing process by means of optical emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rie, K.-T.; Menthe, E.; Woehle, J. [TU Braunschweig (Germany). Inst. fuer Oberflaechentechnik und Plasmatechnische Werkstoffentwicklung

    1998-01-01

    In this work optical emission spectroscopy (OES) is used to characterize the dissociation process of methane in an argon/hydrogen/methane discharge for plasma carburizing. The optical emission spectra of the discharge have been measured as a function of process parameters: discharge voltage, pulse duration and pulse pause time. A correlation between the intensities of hydrocarbon molecules, carbon atoms and ions, and the carbon mass flow model of the carburizing process has been confirmed. The dominant species identified in the spectra used for correlation are excited and ionized carbon atoms, as well as excited carbon and hydrocarbon molecules such as excited CH with a molecular band at 431.42 nm and 314.41 nm, and excited C{sub 2} with molecular band at 501.50 nm. Excited carbon atoms at 493.21 nm and excited carbon ions at 387.17 nm and 426.70 nm are also detected. (orig.) 10 refs.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

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

    International Nuclear Information System (INIS)

    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

  16. 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.

  17. 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.

  18. Optimized Chemical Separation and Measurement by TE TIMS Using Carburized Filaments for Uranium Isotope Ratio Measurements Applied to Plutonium Chronometry.

    Science.gov (United States)

    Sturm, Monika; Richter, Stephan; Aregbe, Yetunde; Wellum, Roger; Prohaska, Thomas

    2016-06-21

    An optimized method is described for U/Pu separation and subsequent measurement of the amount contents of uranium isotopes by total evaporation (TE) TIMS with a double filament setup combined with filament carburization for age determination of plutonium samples. The use of carburized filaments improved the signal behavior for total evaporation TIMS measurements of uranium. Elevated uranium ion formation by passive heating during rhenium signal optimization at the start of the total evaporation measurement procedure was found to be a result from byproducts of the separation procedure deposited on the filament. This was avoided using carburized filaments. Hence, loss of sample before the actual TE data acquisition was prevented, and automated measurement sequences could be accomplished. Furthermore, separation of residual plutonium in the separated uranium fraction was achieved directly on the filament by use of the carburized filaments. Although the analytical approach was originally tailored to achieve reliable results only for the (238)Pu/(234)U, (239)Pu/(235)U, and (240)Pu/(236)U chronometers, the optimization of the procedure additionally allowed the use of the (242)Pu/(238)U isotope amount ratio as a highly sensitive indicator for residual uranium present in the sample, which is not of radiogenic origin. The sample preparation method described in this article has been successfully applied for the age determination of CRM NBS 947 and other sulfate and oxide plutonium samples. PMID:27240571

  19. 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.

  20. 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.

  1. 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

  2. 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.)

  3. Hardness of Carburized Surfaces in 316LN Stainless Steel after Low Temperature Neutron Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Byun, TS

    2005-01-31

    A proprietary surface carburization treatment is being considered to minimize possible cavitation pitting of the inner surfaces of the stainless steel target vessel of the SNS. The treatment gives a large supersaturation of carbon in the surface layers and causes substantial hardening of the surface. To answer the question of whether such a hardened layer will remain hard and stable during neutron irradiation, specimens of the candidate materials were irradiated in the High Flux Isotope Reactor (HFIR) to an atomic displacement level of 1 dpa. Considerable radiation hardening occurred in annealed 316LN stainless steel and 20% cold rolled 316LN stainless steel, and lesser radiation hardening in Kolsterised layers on these materials. These observations coupled with optical microscopy examinations indicate that the carbon-supersaturated layers did not suffer radiation-induced decomposition and softening.

  4. Assessment of Cavitation-Erosion Resistance of 316LN Stainless Steel Following a Nitro-Carburizing Surface Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, Steven J [ORNL

    2009-11-01

    A nitro-carburizing surface treatment known domestically as the Melonite process was applied to type 316LN stainless steel test pieces and exposed to sonication conditions in mercury using a vibratory horn technique. Cavitation-erosion damage was evaluated for extended exposures and compared to other surface treatments on the same substrate alloy. The results indicate that the Melonite process substantially retards weight loss and crater development for extended periods, but gradually is eroded/destroyed leading to exposure of the substrate and cavitation-erosion behavior similar to untreated specimens. Compared with other surface treatments, cavitation-erosion results indicate that specimens treated with Melonite perform similarly to specimens treated with a simple nitriding process. Neither the simple nitriding nor the Melonite treatment is quite as effective as a previously evaluated low temperature carburizing treatment, the latter being about a factor of three better than Melonite in terms of weight loss during sonication in mercury.

  5. Relationship between carburization and zero-applied-stress creep dilation in Alloy 800H and Hastelloy X

    International Nuclear Information System (INIS)

    Typical HTGR candidate alloys can carburize when exposed to simulated service environments. The carbon concentration gradients so formed give rise to internal stresses which could cause dilation. Studies performed with Hastelloy X and Alloy 800H showed that dilations of up to almost 1% can occur at 10000C when carbon pickup is high. Dilation was normally observed only when the carbon increase was >1000 μg/cm2 and ceased when diffusing carbon reached the center of the specimen. (Auth.)

  6. 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.

  7. Effect of Different Inclusions on Mechanical Properties and Machinability of 20NiCrMo Carburizing Steels

    OpenAIRE

    Ånmark, Niclas; Björk, Thomas; Karasev, Andrey; Jönsson, Pär Göran

    2015-01-01

    In modern steelmaking, carburizing steels are often used for production of automotive components with elevated levels of toughness and fatigue strength. This study is focused on the link between the characteristics of non-metallic inclusions in the steel and the machinability of the given steel grades. For this purpose, inclusion characteristics (such as composition, number, size, morphology etc.) in steel samples were determined by common two-dimensional (2D) observations of inclusions on po...

  8. 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.

  9. The Behavior of Phosphorus During Reduction and Carburization of High-Phosphorus Oolitic Hematite with H2 and CH4

    Science.gov (United States)

    Wang, Henghui; Li, Guangqiang; Yang, Jian; Ma, Jianghua; Khan, Babar Shahzad

    2016-06-01

    High-phosphorus oolitic hematite has not been widely utilized due to high content of phosphorus. Ca3(PO4)2 is the main component containing phosphorus in high-phosphorus oolitic hematite. In the present work, the thermodynamics was studied for Ca3(PO4)2 reduction by H2 gas and then carburization by CH4 gas. The results show that phosphorous in Ca3(PO4)2 cannot be reduced from gangue during the reduction of hematite and the formation of iron carbide at the temperature from 923 K to 1073 K (650 °C to 800 °C), in H2 and CH4 atmosphere. Reduction and carburization experiments were carried out. And phosphorus in reduced and carburized specimens was analyzed by EDS and wet chemical method. The results confirmed that phosphorous cannot be reduced during the preparation of iron carbide from this iron ore. So the metallic iron or iron carbide can be prepared without the reduction of phosphorous at relatively low temperature, which can be a new route of utilizing high-phosphorus oolitic hematite. After fine milling-magnetic separation, the 99.47 pct of Fe3C-containing material was recovered, but the dephosphorization rate reached to 19.37 pct only.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.)

  15. 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.

  16. Analysis of Heat Treatment of Carburizing Gear%渗碳齿轮的热处理分析

    Institute of Scientific and Technical Information of China (English)

    刘国虎; 陈羿

    2016-01-01

    渗碳齿轮适合用于工作条件较为繁重、恶劣的汽车、拖拉机的变速箱和后桥中。渗碳钢的工艺性能好,经济上也较合理,所以是较理想的齿轮用钢。渗碳齿轮通常采用渗碳+淬火+低温回火热处理工艺,齿轮表面能获得58~63 HRC 的高硬度。因淬透性较高,齿心部有较高的强度和韧度。该种齿轮的表面耐磨性、抗接触疲劳强度和齿根的抗弯强度及心部的抗冲击能力都高于表面淬火的齿轮。%Carburizing gears are suitable for heavy and bad working conditions with cars and tractors in gearbox and rear axle.The process of this kind of steel is good,and the economy is reasonable,so it is the ideal gear steel.Carburizing gear is usually used for carburizing,quenching,and low temperature back heat treatment process,gear surface can get 58 -63 HRC high hardness.Because of the high degree of quenching,the heart has higher strength and toughness.The gear sur-face wear resistance,resistance to contact fatigue strength and tooth root bending strength of the heart and the anti impact ability are all higher than the surface hardening gear.

  17. The influence of the mechanisms of transfer in carburizing atmospheres on the surface metal layer; Einfluss der Uebertragungsmechanismen von Aufkohlungsatmosphaeren auf die Metallrandschicht

    Energy Technology Data Exchange (ETDEWEB)

    Kuehn, F. [LOI Thermprocess GmbH, Essen (Germany)

    1996-12-01

    The influence of the mechanism of transfer in carburizing atmospheres is discussed using examples of carburization. It became apparent that a direct relationship between mass transfer and the product of partial pressures p{sub CO}xp{sub H2} could not be disproved, since the H{sub 2} content of the atmospheres had not been stated. (orig.) [Deutsch] Der Einfluss der Uebertragungsmechanismen von Aufkohlungsatmosphaeren an Aufkohlungsbeispielen wird diskutiert. Dabei stellte sich heraus, dass die direkte Abhaengigkeit des Stoffueberganges vom Partialdruckprodukt p{sub CO}xp{sub H2} nicht widerlegt werden konnte, zumal der H{sub 2}-Gehalt der Atmosphaeren nicht genannt wurde. (orig.)

  18. 气体渗碳排气过程浅析%Analysing of Discharge Process in Gas Carburizing

    Institute of Scientific and Technical Information of China (English)

    潘一凡; 赵茂程; 王宝平; 於明亮

    2001-01-01

    根据温度、氧电势实测数据及化学平衡原理,对气体渗碳排气过程进行了分析讨论。认为排气阶段的主要作用是零件表面氧化物的还原及消耗降低炉内氧化性气氛的含量,而且升温速度对缩短排气时间有重要影响。这一结论对改进渗碳排气工艺将产生积极的作用。%The paper analyses and discusses discharge processingas carburizing with data of temperatures,oxygen potentials measured and principle of chemical balance.The author thinks that discharging fumes reduce oxide,consume and decrease the content of oxide atmosphere on the surface of the part.And the speed of raising temperature has an important effect on shortening discharge time.The result will take active action on improving discharge techniqus in gas carburizing.

  19. 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.

  20. 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.

  1. Fabrication de carburant synthétique par valorisation du CO2 et de la chaleur nucléaire

    OpenAIRE

    Vibhatavata, Phuangphet,

    2012-01-01

    Ce travail s’inscrit dans le contexte d’un fort accroissement des émissions de gaz à effetde serre au niveau mondial. Une idée est de réutiliser ce CO2 comme matrice de stockageénergétique pour fabriquer un carburant de synthèse en le combinant avec de l’hydrogèneproduit à partir de décomposition de l’eau par apport d’énergie nucléaire ou renouvelable,évitant ainsi le recours au pétrole ou au charbon. Cette idée prend tout son sens dans lecontexte spécifique français où l’électricité, majorit...

  2. 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.

  3. “Colossal” interstitial supersaturation in delta ferrite in stainless steels—I. Low-temperature carburization

    International Nuclear Information System (INIS)

    Low-temperature carburization has been successfully used to surface harden 17-7 precipitation-hardening (PH) and 2205 duplex stainless steels. After carburization, the delta ferrite grains in both alloys near the free surface show a uniform weak contrast under conventional transmission electron microscopy (TEM). Spatially resolved compositional analysis shows that these delta ferrite grains possess enormous carbon contents (as high as 18 at.%) in solid solution, but structurally there is no detectable tetragonality (<5%) or evidence of carbide formation. Near the interface between the interstitially hardened layer and bulk material, weak-contrast plates with significant carbon concentrations were observed in ferrite grains in 17-7 PH stainless steel. A carbon-induced spinodal-like decomposition of delta ferrite to the nanometer-scale Cr-rich and Fe-rich alpha ferrite phases is observed. Carbon is enriched in Cr-rich ferrite due to the high affinity between C and Cr, which introduces lattice mismatch between the Cr-rich and Fe-rich regions. The weak contrast is believed to be the result of overlapping strain fields of these Cr-rich and Fe-rich phases. As the binding energies of carbon interstitials to dislocations in body-centered cubic Fe-based alloys are greater than the binding energy of C to Fe in possible carbides, segregation to dislocation cores is expected. The extremely high dislocation density we observe in high-resolution scanning TEM is consistent with the hypothesis that carbon segregation to dislocation cores effectively delays carbide precipitation and makes possible the “colossal” carbon supersaturation

  4. 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.

  5. 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.

  6. 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.

  7. Sintering of nano-sized WC-Co powders produced by a gas reduction-carburization process

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Gwan-Hyoung [School of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Kang, Shinhoo [School of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)]. E-mail: shinkang@snu.ac.kr

    2006-08-10

    Nanocrystalline cemented tungsten carbide has attracted considerable interests for use in cutting tool because of its superior mechanical properties. In this study, nano-sized powders of mixed WC and Co were prepared from attrition-milled oxides by a gas reduction-carburization process. The effects of compacting pressure, heating schedule, additional ball-milling, and the presence of a grain growth inhibitor on the sintering properties of the nano-sized WC-Co powders were examined. The grain size and phases in WC-Co alloy were clearly affected by compacting pressure. Because of the trapped gases and the lower melting point of the cobalt binder, when a compact of nano-sized WC-Co powder was sintered through a heating schedule with holding steps, the sintered alloy maintained the small size of WC grains without any {eta} phase. In addition, the additional ball-milling improved the microstructure and mechanical properties of the nano-sized WC-Co powder by producing a more uniform distribution of carbon. The addition of VC led to uniformity in microstructure and mechanical properties, even though significant carbon loss occurred.

  8. Sintering of nano-sized WC-Co powders produced by a gas reduction-carburization process

    International Nuclear Information System (INIS)

    Nanocrystalline cemented tungsten carbide has attracted considerable interests for use in cutting tool because of its superior mechanical properties. In this study, nano-sized powders of mixed WC and Co were prepared from attrition-milled oxides by a gas reduction-carburization process. The effects of compacting pressure, heating schedule, additional ball-milling, and the presence of a grain growth inhibitor on the sintering properties of the nano-sized WC-Co powders were examined. The grain size and phases in WC-Co alloy were clearly affected by compacting pressure. Because of the trapped gases and the lower melting point of the cobalt binder, when a compact of nano-sized WC-Co powder was sintered through a heating schedule with holding steps, the sintered alloy maintained the small size of WC grains without any η phase. In addition, the additional ball-milling improved the microstructure and mechanical properties of the nano-sized WC-Co powder by producing a more uniform distribution of carbon. The addition of VC led to uniformity in microstructure and mechanical properties, even though significant carbon loss occurred

  9. Behaviour of Al2O3 scales on Fe-Al and Fe-Ni-Al alloys with small additions of titanium, zirconium, niobium and vanadium on thermal cycling and creep in oxidizing and carburizing atmospheres

    International Nuclear Information System (INIS)

    Aluminium as an alloying element in steels is beneficial for the formation of slow-growing oxide layers at high temperatures. Steels with aluminium as the oxide former are of interest for use in carburizing atmospheres with low O2 partial pressures, e.g. coal gasification or the high temperature nuclear reactor. The behaviour of Al2O3 layers on ferritic and austenitic steels with small additions of titanium, zirconium, niobium and vanadium was studied by measuring radiocarbon penetration in thermal cycling and creep experiments. The oxide layers on the ferritic steels adhered well and were compact with a high carburization resistance. In the creep tests on the austenitic alloys, cracking of the oxide layer and subsequent intergranular oxidation and carburization were observed. (orig.)

  10. 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.

  11. 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.

  12. Low temperature plasma carburizing of AISI 316L austenitic stainless steel and AISI F51 duplex stainless steel Cementação sob plasma à baixa temperatura do aço inoxidável austenítico AISI 316L e do aço inoxidável duplex AISI F51

    OpenAIRE

    Carlos Eduardo Pinedo; André Paulo Tschiptschin

    2013-01-01

    In this work an austenitic AISI 316L and a duplex AISI F51 (EN 1.4462) stainless steel were DC-Plasma carburized at 480ºC, using CH4 as carbon carrier gas. For the austenitic AISI 316L stainless steel, low temperature plasma carburizing induced a strong carbon supersaturation in the austenitic lattice and the formation of carbon expanded austenite (γC) without any precipitation of carbides. The hardness of the carburized AISI 316L steel reached a maximum of 1000 HV due to ∼13 at% c...

  13. 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.

  14. Reaction of uranium and plutonium carbides with nitrogen; Reaction avec l'azote des carbures d'uranium et de plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzelli, R.; Martin, A.; Schickel, R. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-03-01

    Uranium and plutonium carbides react with nitrogen during the grinding process preceding the final sintering. The reaction occurs even in argon atmospheres containing a few percent of residual nitrogen. The resulting contamination is responsible for the appearance of an equivalent quantity of higher carbide in the sintered products; nitrogen remains quantitatively in the monocarbide phase. UC can be transformed completely into nitride under a nitrogen pressure, at a temperature as low as 400 C. The reaction is more sluggish with PuC. The following reactions take places: UC + 0,8 N{sub 2} {yields}> UN{sub 1.60} + C and PuC + 0,5 N{sub 2} {yields} PuN + C. (authors) [French] Les carbures d'uranium et de plutonium reagissent avec l'azote au cours du broyage qui precede le frittage final. Cette reaction est sensible meme sous des atmospheres d'argon ne contenant que quelques pour cent d'azote. Cette contamination se traduit sur les produits frittes par l'apparition d'une quantite equivalente de carbure superieur, l'azote restant fixe quantitativement dans la phase monocarbure. On peut transformer entierement UC en nitrure par action de l'azote sous pression des 400 C. La reaction est plus difficile avec PuC. Les reactions sont les suivantes: UC + 0,8 N{sub 2} {yields} UN{sub 1.60} + C et PuC + 0,5 N{sub 2} {yields} PuN + C.

  15. Reduction of CO{sub 2} emissions by means of process modifications to continuous gas carburization systems; Reduzierung der CO{sub 2}-Emission durch Verfahrensaenderung bei kontinuierlichen Gasaufkohlungsanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Kuehn, F. [LOI Thermprocess GmbH, Essen (Germany)

    1996-12-01

    It is demonstrated that the use of special source-gas atmospheres for gas carburization makes it possible to cut specific CO{sub 2} emissions by around 32%. This is achievable for both shallow and medium carburization depths. The process described can also be used at a furnace temperature of 880 C, at which the direct gas feed process no longer functions. Simultaneous energy-input savings of approx. 25% can also be achieved. (orig.) [Deutsch] Es wird gezeigt, dass bei Einsatz einer speziellen Traegergasatmosphaere fuer die Gasaufkohlung die spezifische CO{sub 2}-Emission um etwa 32% gesenkt werden kann. Das ist bei kleiner bis mittlerer Aufkohlungstiefe moeglich. Das beschriebene Verfahren ist auch bei einer Ofenraumtemperatur von 880 C, bei der das Direktbegasungsverfahren versagt, anwendbar. Gleichzeitig kann der spezifische Energieeinsatz um rund 25% reduziert werden. (orig.)

  16. 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

  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. Stabilization of mixed carbides of uranium-plutonium by zirconium. Part 1.: uranium carbide with small additions of zirconium; Etude de la stabilisation des carbures mixtes d'uranium et de plutonium par addition de zirconium. 1. partie: etude des carbures d'uranium avec de faibles additions de zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Bocker, S. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    Cast carbide samples, being of a high density and purity, are preferable for research purposes, to samples produced by powder metallurgy methods. Samples of uranium carbide with small additions of zirconium (1 to 5 per cent) were cast, as rods, in an arc furnace. A single phase carbide with interesting qualities was produced. As cast, a dendrite structure is observed, which does not disappear, after a treatment at 1900 deg. C during 110 hours. In comparison with uranium monocarbide the compatibility with stainless steel is much improved. The specific heat (between room temperature and 2500 deg. C) is similar to the specific heat of uranium monocarbide. A study of these mixed carbides, but having a part of the uranium replaced by plutonium is under way. (author) [French] Les echantillons de monocarbures obtenus par coulee sont tres interessants pour les recherches experimentales a cause de leur grande purete, de leur densite tres elevee et de la facilite d'obtention des lingots de forme et dimensions variees. On a prepare et coule dans un four a arc des echantillons de carbures d'uranium avec de faibles additions de zirconium (1 a 5 at. pour cent). On obtient ainsi des carbures monophases presentant de meilleures proprietes que le monocarbure d'uranium. A l'etat brut de coulee on observe une structure dendritique qui n'est pas detruite par un traitement thermique de 110 heures a 1900 deg. C. La compatibilite avec l'acier inoxydable 316 (a 925 deg. C pendant 500 heures) est nettement amelioree par rapport a UC. La chaleur specifique (entre la temperature ordinaire et 2500 deg. C) et la densite sont tres peu differentes de celles du monocarbure d'uranium. Une etude concernant les composes U-Pu-Zr-C est actuellement en cours. (auteur)

  19. 渗碳工艺在汽车车身齿轮中的应用%Application of Carburizing Technology in Automotive Gear

    Institute of Scientific and Technical Information of China (English)

    覃莉莉

    2013-01-01

    The practical application of the heat treatment process of carburizing and carbonitriding in automotive gear was experimentally researched.The results show that the process combined with gear hookers can realize the purpose to easily control microstructure and simple operating,and obtain a certain number of surface residual austenite and carbide mixture,enhance the strength and excellent plasticity,ductility of automotive gear,so it also increases the anti-fatigue life.The process is used in practical production to shorten manufacturing cycle,save production cost,improve economic benefits.%实验研究了渗碳及碳氮共渗热处理工艺在汽车齿轮生产中的实用效果.结果表明,该工艺结合齿轮挂具技术,不仅可以实现组织易控、操作简单的目的,还可以获得一定数量的表层残余奥氏体和碳化物的混合物,提高车用齿轮的强度,得到优良的材料塑形和韧性,从而提高了车用齿轮的抗疲劳寿命;该技术应用到实际生产中,缩短制造周期,节约生产成本,提高工厂的经济效益.

  20. 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.

  1. 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.

  2. Carburized Bearing Steel 20Cr2Ni4A Melting with EAF%电弧炉冶炼20Cr2Ni4A渗碳轴承钢

    Institute of Scientific and Technical Information of China (English)

    吴耀光

    2001-01-01

    开发了用10t-EAF熔炼20Cr2Ni4A渗碳轴承钢的工艺过程.结果表明,在合理的试验条件下,能获得电解杂质总量合格的产品,因此,单一电弧炉冶炼是可行的.%The development of the carburized bearing steel 20Cr2Ni4A with 10 t EAF, was introduced. The results show that the fiuishing product, with and lower inclusion content, was producted by the single Electro ARC Furnace.

  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. Étude comparative multiéchelle des mécanismes de frottement et d’usure de carbures cémentés WC-Co

    OpenAIRE

    Yahiaoui, Malik; Paris, Jean-Yves; Denape, Jean; Dourfaye, Alfazazi

    2015-01-01

    Les carbures cémentés WC-Co sont très largement utilisés dans les industries de la coupe des métaux et de l’excavation des roches. De manière générale, le compromis dureté/ténacité remarquable de ces matériaux permet d’obtenir des outils à la fois résistants à l’usure et aux impacts. Chermant et Osterstock [1] ont été les premiers à expliciter des mécanismes entraînant l’usure des WC-Co. Ils ont ainsi expliqué que l’usure des WC-Co se produit principalement suite à des fissurations dans la ph...

  5. Étude Thermodynamique et par Spectrométrie de Masse du Comportement de Poudres de Carbure de Silicium (SiC) à Haute Température

    OpenAIRE

    Honstein, G.

    2009-01-01

    Le carbure de silicium est un matériau bien connu à ce jour, mail il y a des aspects lors de sa fabrication qui sont mal compris. Le but de ce travail est de contribuer à la compréhension des échanges de matière via la phase gazeuse lors de la fabrication de composants en SiC. La procédure expérimentale utilisée est le suivi in situ de l'évolution des pressions de vapeur ou celle des flux évaporés par spectrométrie de masse et de comparer la morphologie et la structure des poudres avant et ap...

  6. 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。

  7. 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.

  8. 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.

  9. 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.

  10. Contribution to the study of U-Ti and U-Pu-Ti carbides; Contribution a l'etude des carbures U-C-Ti et (U, Pu) - C-Ti

    Energy Technology Data Exchange (ETDEWEB)

    Milet, C.A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-07-01

    After having discussed the reasons to use (U,Pu) carbides as fast reactor fuel, we examine the influence of the addition of titanium to these carbides. A preliminary study has been done on the system of U-C-Ti and some properties have been measured such as: density, thermal expansion, electrical resistivity, atmospheric corrosion and compatibility with stainless steel. The systems U-Pu-C-Ti (Pu/U + Pu equal to 15 per cent) and U-C-Ti have been found to be very similar. There exists a two phases region (U,Pu)C + TiC, an eutectic between (U,Pu)C and TiC for approximately 15 at %. The solubilities of U + Pu in TiC and of Ti in (U,Pu)C is less than 1 % at. The addition of titanium does not markedly change thermal expansion coefficients of (U,Pu)C. However the resistance to atmospheric corrosion and compatibility with stainless steel is improved. Thermal conductivity, calculated from electrical resistivity, has increased. On the other side, the density of fissile material is lowered. The combination of (U,Pu)C + TiC seems to be the most promising alloy for application as nuclear fuel. (author) [French] Apres avoir rappele les problemes poses par un combustible pour les reacteurs a neutrons rapides et l'interet des carbures U-Pu-C comme combustible, on examine l'influence de l'addition de titane dans ces carbures. Une etude preliminaire sur le systeme U-C-Ti a ete effectuee et quelques proprietes sont indiquees: densite, coefficients de dilatation, resistivite electrique, tenue a la corrosion atmospherique, compatibilite avec l'acier inoxydable. Le systeme U-Pu-C-Ti (Pu/U + Pu egal a 15 pour cent) presente de grandes analogies avec le systeme U-C-Ti. Il existe un domaine biphase (U,Pu)C + TiC, un eutectique entre (U,Pu)C et TiC pour environ 15 at % Ti; les solubilites de U + Pu clans TiC et de Ti dans (U,Pu)C sont inferieures a 1 at %. Par rapport a la phase (U,Pu)C, l'addition de titane est sans effets importants sur les coefficients de

  11. 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.

  12. Influence of high temperature tempering on retained austenite in carburized 20Cr2Ni4A steel%高温回火对20Cr2Ni4A钢渗碳层中残留奥氏体的影响

    Institute of Scientific and Technical Information of China (English)

    刘永飞; 高啸天; 武占学; 冯小军

    2013-01-01

    The main ways for reducing retained austenite of carburized 20Cr2Ni4A steel are high temperature tempering and cryogenic treatment. The influence of different high temperature tempering on retained austenite in carburized 20Cr2Ni4A steel was researched, especially the tempering time. The results show that after tempering with high tempering temperature at first and then prolonged temper holding time, the hardness of hardened case heat treatment can be over 62 HRC and the microstructure in the case is cryptocrystalline martensite + uniform carbides + small amount of austenite, therefore the surface hardness of parts after carburizing and quenching as well as tempering can meet the requirements.%减少20Cr2Ni4A钢渗碳后残留奥氏体的途径主要有高温回火和深冷处理.研究不同高温回火工艺对20Cr2Ni4A渗碳层中残留奥氏体转变的影响,尤其是高温回火时间的影响.结果表明:采取第一次回火温度高和第二次回火时间长的工艺后进行淬火,表面硬度超过62 HRC,渗层组织为细密的隐针马氏体+均匀的碳化物+较少的残留奥氏体,保证产品渗碳淬火后表面硬度满足了生产需要.

  13. Low temperature plasma carburizing of AISI 316L austenitic stainless steel and AISI F51 duplex stainless steel Cementação sob plasma à baixa temperatura do aço inoxidável austenítico AISI 316L e do aço inoxidável duplex AISI F51

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Pinedo

    2013-06-01

    Full Text Available In this work an austenitic AISI 316L and a duplex AISI F51 (EN 1.4462 stainless steel were DC-Plasma carburized at 480ºC, using CH4 as carbon carrier gas. For the austenitic AISI 316L stainless steel, low temperature plasma carburizing induced a strong carbon supersaturation in the austenitic lattice and the formation of carbon expanded austenite (γC without any precipitation of carbides. The hardness of the carburized AISI 316L steel reached a maximum of 1000 HV due to ∼13 at% carbon supersaturation and expansion of the FCC lattice. For the duplex stainless steel AISI F51, the austenitic grains transformed to carbon expanded austenite (γC, the ferritic grains transformed to carbon expanded ferrite (αC and M23C6 type carbides precipitated in the nitrided case. Hardness of the carburized case of the F51 duplex steel reached 1600 HV due to the combined effects of austenite and ferrite lattice expansion with a fine and dispersed precipitation of M23C6 carbides.O aço inoxidável austenítico AISI 316L e o aço inoxidável duplex AISI F51 (EN 1.4462 foram cementados sob plasma-DC na temperatura de 480ºC, utilizando-se CH4 como gás de arraste. A cementação sob plasma à baixa temperatura conduziu a uma elevada supersaturação do reticulado cristalino em carbono com a formação de austenita expandida(γC, sem a precipitação de carbonetos. A dureza do aço 316L, após a cementação, atingiu um valor máximo de 1000 HV, devido à supersaturação de ∼ 13 at% de carbono e à expansão do reticulado cristalino CFC. Para o aço inoxidável duplex AISI F51, os grãos de austenita se transformaram em austenita expandida pelo carbono e os grãos de ferrita se transformaram para ferrita expandida com a precipitação de carbonetos do tipo M23C6, na camada cementada. A dureza da camada cementada, no aço F51, atingiu 1600HV, devido ao efeito combinado da expansão dos reticulados cristalinos da austenita e da ferrita com a precipitação fina e

  14. 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.

  15. 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

  16. Hot ductility and processing maps of a new secondary hardening carburized steel%新型二次硬化渗碳钢的高温塑性及热加工图

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    利用Gleeble-3800热模拟试验机,对一种新型二次硬化渗碳钢C61进行了高温轴向压缩试验,测得其高温流变曲线,观察了高温变形后的显微组织,获得了该钢的热变形激活能Q为414.84 kJ/mol,建立了试验钢的热变形本构方程,并绘制了其热加工图.结合高温变形后的显微组织和热加工图,确定最优热变形工艺参数为变形温度范围为1050~1100℃,应变速率范围为0.1~1.0 s-1,此时试验钢组织发生了完全动态再结晶,晶粒明显细化,且对应的能量耗散效率达到峰值.%The hot temperature compression behaviors of a new secondary hardening carburized steel-C61 was imple-mented using Gleeble-3800 thermal simulation testing machine. The high temperature flow curve was determined and the microstructures were observed. The activation energy Q of thermal deformation of the testing steel was 414.84 kJ/mol. The thermal deformation equation and the hot processing map were established. The optimal thermal deformation pro-cessing parameters were determined combined with microstructures after high temperature deformation and the hot pro-cessing map. The region of the best thermal deformation temperature ranged from 1050 to 1100℃and strain rates from 0.1 to 1.0 s-1. The behavior of completely dynamic recrystallization could be observed,the grains were refined obvious-ly,and the corresponding energy dissipation efficiency reached the peak.

  17. 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

  18. 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

  19. 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

    OpenAIRE

    Franckowiak S.; Chiche P.; Meyer M.; Bellus F.; Charcosset H.

    2006-01-01

    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 ...

  20. 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

  1. Carburation automobile. Contribution à l' étude d'un dispositif d'injection de GPL en phase gazeuse Automotive Fuel: Research on a New Gas-Phase Lpg Injection System

    Directory of Open Access Journals (Sweden)

    Dubois J. P.

    2006-11-01

    Full Text Available Les systèmes de carburation traditionnels aux GPL (induction donnent lieu à un certain nombre d'insatisfactions dues, en particulier, aux difficultés de réglages et à une adéquation imparfaite entre matériels et véhicules. Le système d'injection gazeuse mis au point comporte : - un débitmètre à volet mesurant le débit d'air admis au moteur; - un doseur, lié mécaniquement au volet, et fournissant le mélange air-gaz prédéterminé. Un dispositif d'ouverture forcée du volet permet, lorsqu'on fonctionne à l'essence, de ne pas perturber les performances du carburateur; - un vaporiseur détendeur à deux étages dont les fonctions essentielles sont : - la prédétente à 1,5 bar; - la détente finale à 250 mbar; - l'enrichissement à haut régime; - la sécurité intégrée en cas d'arrêt moteur; - un module de démarrage à froid évitant l'envahissement liquide du vaporiseur jusqu'à 10°C Les avantages de ce dispositif sont : - l'universalité : le même modèle est utilisé sur tous véhicules de 60 à 130 ch; - l'absence de réglage : seul le ralenti est à ajuster; - la maîtrise du rapport air/gaz à la valeur choisie; - le bon compromis performances/consommations; - la prise en compte des paramètres réels de fonctionnement. Conventional LPG induction systems used for transportation purposes do not usually work satisfactory, in particular due to adjustment difficulties and to unsuitable equipment/vehicle matching. The LPG injection system that has been developed comprises:(aa flap flowmeter measuring the air flow into the- engine;(b a proportioning device mechanically connected to the flap and supplying the predetermined air/gas mixture (a device forcing the flap open keeps carburettor performances the same when running on gasoline;(c a two-stage pressure regulator having the following main functions:- initial expansion down to 1. 5 bar;- final expansion down to 250 mbar;- high-speed enrichment;- built-in safety in case

  2. Carburizer process in electric arc furnaces

    Science.gov (United States)

    Karasev, V. P.; Babichevskii, G. V.; Prokopenko, Ya. Yu.

    2015-06-01

    The behavior of coke and carbon in heating and melting of steel scrap is considered. The efficiency of carbon assimilation in the period of metal melting is estimated for various versions of introduction of a lump carbon-containing material into an EAF charge. The use of a carbon-containing material as an alternative heat source in EAF is analyzed.

  3. 减速机用渗碳齿轮钢18 CrNiM o7-6氧含量和夹杂物的控制%Control of Oxygen Content and Inclusion of Carburizing Gear Steel 18CrNiMo7-6 Used for Reducer

    Institute of Scientific and Technical Information of China (English)

    宋部军; 杨平

    2015-01-01

    渗碳齿轮钢18CrNiMo7-6要求的氧含量非常低,用强脱氧剂铝可以降低氧含量,但用量不当容易造成低倍夹杂。通过对低倍夹杂物成分分析及碳氧平衡关系的分析,摸索出合理喂铝参数,既降低氧含量同时又不造成低倍夹杂物的增加。%Oxygen content is required very low for carburizing gear steel 18CrNiMo7-6 and the strong deoxidizer a-luminum can reduce the oxygen content, but its inappropriate amount can cause macro-inclusion easily.By analyzing the composition of macro-inclusion and the balance relationship between carbon and oxygen, the reasonable aluminum feeding parameter is found to reduce oxygen content and not increase macro-inclusion.

  4. 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

  5. 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

  6. 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

  7. 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

  8. The French market of automotive fuels; Marche francais des carburants

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2003-02-01

    The supermarkets are the main retailers of automotive fuels in France. With a growth of 1.7 point of market share, the supermarkets represented 57.2% of the fuel sales (in volume) in 2001. This performance is due to both their discount policy and their fast development over the whole territory. However, the oil companies have started a counter-offensive policy with new offers of services and more competitive prices. This article summarizes the results of an economic study carried out in July 2002 by Xerfi S.A. using the 2001 fuel sales data and the 2002-2003 vehicle sales forecasts. (J.S.)

  9. Oxidation, carburization and/or sulfidation resistant iron aluminide alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

    2003-08-19

    The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or Zro.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B. .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

  10. Kinetic study of uranium carburization by different carbonated gases

    International Nuclear Information System (INIS)

    The kinetic study of the reaction U + CO2 and U + CO has been performed by a thermogravimetric method on a spherical uranium powder, in temperature ranges respectively from 460 to 690 deg. C and from 570 to 850 deg. C. The reaction with carbon dioxide leads to uranium dioxide. A carbon deposition takes place at the same time. The global reactions is the result of two reactions: U + 2 CO2 → UO2 + 2 CO U + CO2 → UO2 + C The reaction with carbon monoxide leads to a mixture of dioxide UO2, dicarbide UC2 and free carbon. The main reaction can be written. U + CO → 1/2 UO2 + 1/2 UC2 The free carbon results of the disproportionation of the carbon monoxide. A remarkable separation of the two phases UO2 and UC2 can be observed. A mechanism accounting for the phenomenon has been proposed. The two reactions U + CO2 and U + CO begin with a long germination period, after which, the reaction velocity seems to be limited in both cases by the ionic diffusion of oxygen through the uranium dioxide. (author)

  11. 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

  12. Smelting in cupola furnace for re carburization of direct reduction iron (DRI)

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez, J. L.; Tremps, E.; Ruiz-Bustinza, I.; Moron, C.; GarciaGarcia, A.; Robla, J. I.; Gonzalez-Gasca, C.

    2015-07-01

    Herein the synthesis of iron-carbon saturated alloys (foundries) melting in cupola furnaces from direct reduction iron is described. The fundamentals are reviewed and combinations undertaken are discussed along with their results, including conclusions and recommendations for follow up. (Author)

  13. Surface Fatigue Lives of Case-Carburized Gears With an Improved Surface Finish

    Science.gov (United States)

    Krantz, T. L.; Alanou, M. P.; Evans, H. P.; Snidle, R. W.; Krantz, T. L. (Technical Monitor)

    2000-01-01

    Previous research provides qualitative evidence that an improved surface finish can increase the surface fatigue lives of gears. To quantify the influence of surface roughness on life, a set of AISI 93 10 steel gears was provided with a nearmirror finish by superfinishing. The effects of the superfinishing on the quality of the gear tooth surfaces were determined using data from metrology, profilometry, and interferometric microscope inspections. The superfinishing reduced the roughness average by about a factor of 5. The superfinished gears were subjected to surface fatigue testing at 1.71 -GPa (248-ksi) Hertz contact stress, and the data were compared with the NASA Glenn gear fatigue data base. The lives of gears with superfinished teeth were about four times greater compared with the lives of gears with ground teeth but with otherwise similar quality.

  14. Fuels and alternative propulsion in Germany; Les carburants et propulsion alternatifs en Allemagne

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-04-15

    The transportation sector is one of the first responsible of the air pollution in Germany. The kyoto protocol and the european directive led the german Government to set about some measures. To encourage the petroleum industry to develop classical fuels/biofuels mixing, the government exempted from taxes until 2020 the biofuels part. The Government decided also financial incentives for diesel vehicles equipped with particles filters. Among the different fuels, the document presents the advantages and disadvantages of the hydrogen fuels and the hybrid motors. (A.L.B.)

  15. Carbon Coating, Carburization and High Temperature Stability Improvement of Cobalt Nanorods

    OpenAIRE

    Ibrahim, Mona; Marcelot-Garcia, Cécile; Aït Atmane, Kahina; Berrichi, Ekrame; Lacroix, Lise-Marie; Zwick, Antoine; Warot-Fonrose, Bénédicte; Lachaize, Sébastien; Decorse, Philippe; Piquemal, Jean-Yves; Viau, Guillaume

    2013-01-01

    International audience The reactivity of highly crystalline hcp cobalt nanorods (NRs) with organic solvents at high temperature was studied. Cobalt NRs with a mean diameter of 15 nm were first synthesized by the polyol process and then heated at 300 °C in octadecene (ODE), oleylamine (OA) or mixtures of these two solvents. The surface and structural modifications of the Co NRs were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scan...

  16. The technologies for heavy vehicles motors and their fuels; Les technologies des moteurs de vehicules lourds et leurs carburants

    Energy Technology Data Exchange (ETDEWEB)

    Plassat, G.

    2005-07-01

    The heavy vehicles are those the total weight (charged) is more than 3,5 tons. This document provides a comparative and parametric analysis of the main technologies developed for the future buses. A detailed presentation is done for each technique, as the operating principles and the advantages and disadvantages facing the today solution. More particularly the author presents the evolution of the diesel-fuel motor, the motor optimization for specific fuel as the natural gas and the liquefied petroleum gas, the hybrid thermal-electric motor, the hydrogen fuel cells, the biofuels and the de-pollution systems to eliminate the NO{sub X} and the particles. (A.L.B.)

  17. Lattice dynamics of {alpha} boron and of boron carbide; Proprietes vibrationnelles du bore {alpha} et du carbure de bore

    Energy Technology Data Exchange (ETDEWEB)

    Vast, N

    1999-07-01

    The atomic structure and the lattice dynamics of {alpha} boron and of B{sub 4}C boron carbide have been studied by Density Functional Theory (D.F.T.) and Density Functional Perturbation Theory (D.F.P.T.). The bulk moduli of the unit-cell and of the icosahedron have been investigated, and the equation of state at zero temperature has been determined. In {alpha} boron, Raman diffusion and infrared absorption have been studied under pressure, and the theoretical and experimental Grueneisen coefficients have been compared. In boron carbide, inspection of the theoretical and experimental vibrational spectra has led to the determination of the atomic structure of B{sub 4}C. Finally, the effects of isotopic disorder have been modeled by an exact method beyond the mean-field approximation, and the effects onto the Raman lines has been investigated. The method has been applied to isotopic alloys of diamond and germanium. (author)

  18. Fuels production by the thermochemical transformation of the biomass; La production de carburants par transformation thermochimique de la biomasse

    Energy Technology Data Exchange (ETDEWEB)

    Claudet, G. [CEA, 75 - Paris (France)

    2005-07-01

    The biomass is a local and renewable energy source, presenting many advantages. This paper proposes to examine the biomass potential in France, the energy valorization channels (thermochemical chains of thermolysis and gasification) with a special interest for the hydrogen production and the research programs oriented towards the agriculture and the forest. (A.L.B.)

  19. Production de bio-carburants de 3ème génération à partir de microalgues

    OpenAIRE

    Ramirez, Lis,

    2013-01-01

    Given the depletion of fossil fuels and to meet a growing demand for transportation energy, scientists are now turning towards an almost inexhaustible and renewable resource: biomass. As biomass, microalgae represent a potential source of biofuel because they may contain high levels of lipids and hydrocarbons. Their extremely fast growth, the use of CO2 and solar energy for their growth and the absence of competition with traditional agriculture makes microalgae very appealing. Two thermochem...

  20. The sustainable development of transports: the motors and the fuels; Le developpement durable des transports: quels moteurs, quels carburants?

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This panorama 2005 between politicians, industrialists and scientists discussed the following topics: exploration-production activities and markets, refining and petrochemistry, the future world gas market, the petroleum supply and demand, the new petroleum and gas reserves, the today and tomorrow alternative fuels, the biofuels in the world, the hybrid vehicles future, the energy consumption in the transport sector, the road fuels in europe and the increase of diesel fuel, the de-pollution techniques of industrial vehicles. The slides of the interventions are provided. The sheets ''le point sur'' of the year 2005 are also provided. (A.L.B.)

  1. Kinetics of niobium carbide precipitation in ferrite; Cinetiques de precipitation du carbure de niobium dans la ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Gendt, D

    2001-07-01

    The aim of this study is to develop a NbC precipitation modelling in ferrite. This theoretical study is motivated by the fact it considers a ternary system and focus on the concurrence of two different diffusion mechanisms. An experimental study with TEP, SANS and Vickers micro-hardening measurements allows a description of the NbC precipitation kinetics. The mean radius of the precipitates is characterized by TEM observations. To focus on the nucleation stage, we use the Tomographic Atom Probe that analyses, at an atomistic scale, the position of the solute atoms in the matrix. A first model based on the classical nucleation theory and the diffusion-limited growth describes the precipitation of spherical precipitates. To solve the set of equations, we use a numerical algorithm that furnishes an evaluation of the precipitated fraction, the mean radius and the whole size distribution of the particles. The parameters that are the interface energy, the solubility product and the diffusion coefficients are fitted with the data available in the literature and our experimental results. It allows a satisfactory agreement as regards to the simplicity of the model. Monte Carlo simulations are used to describe the evolution of a ternary alloy Fe-Nb-C on a cubic centred rigid lattice with vacancy and interstitial mechanisms. This is realized with an atomistic description of the atoms jumps and their related frequencies. The model parameters are fitted with phase diagrams and diffusion coefficients. For the sake of simplicity, we consider that the precipitation of NbC is totally coherent and we neglect any elastic strain effect. We can observe different kinetic paths: for low supersaturations, we find an expected precipitation of NbC but for higher supersaturations, the very fast diffusivity of carbon atoms conducts to the nucleation of iron carbide particles. We establish that the occurrence of this second phenomenon depends on the vacancy arrival kinetics and can be related to the microstructure of the steel. (author)

  2. Biodegradability of fuel-ethers in environment; Biodegradabilite des ethers-carburants dans l'environnement

    Energy Technology Data Exchange (ETDEWEB)

    Fayolle-Guichard, F.

    2005-04-01

    Fuel ethers (methyl tert-butyl ether or MTBE, ethyl tert-butyl ether or ETBE and tert-amyl methyl ether or TAME have been used as gasoline additives since about twenty years in order to meet the requirements for the octane index and to limit the polluting emission in exhaust pipe gas (unburnt hydrocarbons and carbon monoxide). The high water solubility and the poor biodegradability of these compounds make them pollutants frequently encountered in aquifers. The present manuscript summarizes the knowledge concerning the biodegradability of fuel ethers obtained both at IFP and during collaborations with the Pasteur Institute (Paris), the Biotechnology Research Institute (Montreal, Canada) and the Center for Environmental Biotechnology (University of Tennessee, USA). Rhodococcus ruber IFP 2001 and Mycobacterium austroafricanum IFP 2012, two microorganisms isolated at IFP for their ability to grow, respectively, on ETBE and MTBE, were studied in order to determine the intermediates produced during MTBE and ETBE biodegradation and the enzymes required for each biodegradation step, thus allowing us to propose MTBE and ETBE catabolic pathways. A proteomic approach, from the protein induced during the degradation of ETBE or MTBE to the genes encoding these different enzymes, was carried out. The isolation of such genes is required:1) to use them for help in determining the bio-remediation capacities in polluted aquifers (DNA micro-arrays), 2) to monitor the microorganisms isolated for their degradative capacities during bio-remediation processes (fluorescent in situ hybridization or FISH) and 3) to create new tools for the detection and the quantification of ETBE or MTBE in contaminated aquifers (bio-sensor). The manuscript also describes the different ways for the adaptation of microorganisms to the presence of a xenobiotic compound. (author)

  3. Fuel consumption and CO{sub 2} emissions (Car Labelling); Consommations de carburant et emissions de CO{sub 2} (Car Labelling)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-03-01

    CO{sub 2} is the most important greenhouse gas produced by internal combustion engines. In the framework of the Kyoto protocol, actions have been implemented in the transportation sector for the abatement of vehicles fuel consumption and pollutant emissions. This study presents the 'honors list' established by the French agency of environment and energy mastery (Ademe) of the fuel consumption and CO{sub 2} emissions of gasoline, diesel, LPG, NGV, and hybrid electric-powered vehicles. Results are presented in tables per company and model. These data are compiled and summarized in a last part which presents the key data about the evolution of the French automotive market, the emissions and consumptions of vehicles and the technological evolution of the vehicles and its influence on the fuel consumption. (J.S.)

  4. Status and potential of bio-methane fuel; Etat des lieux et potentiel du biomethane carburant Etude ADEME, AFGNV, ATEE Club Biogaz, GDF SUEZ, IFP, MEEDDAT

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-07-01

    This document first indicates and describes the various bio-methane production processes which can be implemented on a short term (use of organic wastes or effluents), on a medium term (from energetic crops) and on a longer term (gasification). It discusses and assesses the potential production of bio-methane fuel from different sources and processes. It describes the steps of the production of bio-methane fuel from biogas, with notably biogas refinement to produce bio-methane through three processes (de-carbonation, desulfurization, dehydration). Cost productions are assessed. Expected technology advances are evoked. Finally, the authors outline the contribution of bio-methane in the limitation of greenhouse gas emissions in the transport sector

  5. Natural gas - an environmentally friendly fuel for urban vehicles: the smart demonstrator approach; Le gaz naturel, un carburant adapte pour les vehicules urbains: cas du demonstrateur smart

    Energy Technology Data Exchange (ETDEWEB)

    Tilagone, R.; Venturi, S. [Institut Francais du Petrole Lyon, 69 - Vernaison (France); Monnier, G. [Institut Francais du Petrole, 92 - Rueil-Malmaison (France)

    2006-07-01

    The reduction of greenhouse gases emissions remains one of the most important challenges stakes for the next decades involving all energy consumers and especially the industrial actors, although the need to make better use of energy is not appreciated to the same extent by all industrial countries. For the automotive sector, the European car manufacturers' commitment (reduction of the average fuel consumption for new vehicles to 140 grams of CO{sub 2} produced per kilometer by 2008) appears to be a valuable contribution towards meeting the recommendations of the European Commission. A sharp CO{sub 2} emission reduction requires efforts both to reduce vehicle's fuel consumption, and to widen the use of fuel with advantageous molecular hydrogen to carbon (H/C) ratio. Alongside vehicle's optimization itself improving engine efficiency remains the main target. Reduction of engine displacement volume (commonly named down-sizing) is an efficient way to achieve this target. Due to its interesting chemical properties, Natural Gas can be used to achieve low carbon dioxide levels (H/C ratio close to 4), while at the same time maintaining high thermal efficiency through dedicated engine development. The main objective of this project is to confirm (with a dedicated demonstrator vehicle) the high efficiency of CNG fuel when used in urban conditions. The target is to achieve low CO{sub 2} emissions with a maximum level of 90 g/km on the MVEG driving cycle, while keeping pollutant emissions below EURO IV level. The first step was dedicated to CNG specific engine parts design (pistons, connecting rod, crank-shaft, etc.) in order to optimize CNG configuration. During the following steps, the engine has been optimized on a test bench. Valve timing and turbo-charger selection have been optimized in order to obtain the best trade-off in terms of power, consumption and pollutants. The final step has been spent to calibrate the engine, firstly on the test bench and secondly on the vehicle. This work allows coping with EURO IV emissions level with optimized catalyst light-off transient running conditions, drive-ability, etc. (authors)

  6. Croissance localisée par transport VLS de carbure de silicium sur substrats SiC et diamant pour des applications en électronique de puissance

    OpenAIRE

    Vo-Ha, Arthur,

    2014-01-01

    La croissance localisée de SiC dopé p par un mécanisme Vapeur-Liquide-Solide (VLS) a été effectuée sur substrats SiC-4H (0001) 8°off et diamant (100). Pour ce faire, des motifs constitués d'un empilement silicium-aluminium sont fondus puis alimentés en propane. Dans le cas de l'homoépitaxie de SiC-4H, il a été démontré que la quantité limitée de phase liquide initiale entraine une évolution constante des paramètres de croissance en raison de l'appauvrissement graduel en silicium. Il est toute...

  7. Fuel and Electrical Systems Mechanic. Apprenticeship Training Standards = Mecanicien de systemes d'alimentation en carburant et electriques. Normes de formation en apprentissage.

    Science.gov (United States)

    Ontario Ministry of Skills Development, Toronto.

    These training standards for fuel and electrical systems mechanics are intended to be used by apprentice/trainees, instructors, and companies in Ontario, Canada, as a blueprint for training or as a prerequisite for prerequisite for accreditation/certification. The training standards identify skills required for this occupation and its related…

  8. Study of boron carbide evolution under neutron irradiation; Contribution a l'etude de l'evolution du carbure de bore sous irradiation neutronique

    Energy Technology Data Exchange (ETDEWEB)

    Simeone, D. [CEA/Saclay, Dept. de Mecanique et de Technologie (DMT), 91 - Gif-sur-Yvette (France)]|[Universite Blaise Pascal, Clermont-Ferrand II, (CNRS), 63 - Aubiere (France)

    1999-07-01

    Owing to its high neutron efficiency, boron carbide (B{sub 4}C) is used as a neutron absorber in control rods of nuclear plants. Its behaviour under irradiation has been extensively studied for many years. It now seems clear that brittleness of the material induced by the {sup 10}B(n,{alpha}){sup 7}Li capture reaction is due to penny shaped helium bubbles associated to a high strain field around them. However, no model explains the behaviour of the material under neutron irradiation. In order to build such a model, this work uses different techniques: nuclear microprobe X-ray diffraction profile analysis and Raman and Nuclear Magnetic Resonance Spectroscopy to present an evolution model of B{sub 4}C under neutron irradiation. The use of nuclear reactions produced by a nuclear microprobe such as the {sup 7}Li(p,p'{gamma}){sup 7}Li reaction, allows to measure lithium profile in B{sub 4}C pellets irradiated either in Pressurised Water Reactors or in Fast Breeder Reactors. Examining such profiles enables us to describe the migration of lithium atoms out of B{sub 4}C materials under neutron irradiation. The analysis of X-ray diffraction profiles of irradiated B{sub 4}C samples allows us to quantify the concentrations of helium bubbles as well as the strain fields around such bubbles.Furthermore Raman spectroscopy studies of different B{sub 4}C samples lead us to propose that under neutron irradiation. the CBC linear chain disappears. Such a vanishing of this CBC chain. validated by NMR analysis, may explain the penny shaped of helium bubbles inside irradiated B{sub 4}C. (author)

  9. 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.

  10. La production de carburants à partir de biomasse lignocellulosique par voie biologique : état de l’art et perspectives

    Directory of Open Access Journals (Sweden)

    O’Donohue Michael J.

    2008-05-01

    Full Text Available In the current international context, the development of industrial technology that will allow the production of agro-fuels from lignocellulosic biomass is becoming ever more important for society. However, despite over thirty years of research, several hurdles still have to be surmounted before the first industrial facilities begin to produce ethanol. Nevertheless, thanks to its ability to generate innovative, clean and sustainable solutions for industry, biotechnology is now well-poised to provide new solutions aimed at the full exploitation of biomass resources, not only to make fuels, but also a wide range of fine chemicals and products that are required by modern society.

  11. Gear Pre-oxidation Gas Carburizing at Low Temperatrue%齿轮预氧化低温气体渗碳

    Institute of Scientific and Technical Information of China (English)

    余华俐; 杨宾崇

    2004-01-01

    拖拉机齿轮20CrMnTi常规渗碳工艺温度高、能耗大、变形大.采用预氧化低温气体催渗工艺,使齿轮产生更多的活化中心,气氛中碳原子的活性提高,形成高碳势,扩散快,实现了870℃低温气体渗碳,减少了变形.

  12. Organometallic precursors of titanium and vanadium nitride and carbide. Doctoral thesis. Precurseurs organometalliques de nitrure et de carbure de titane et de vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, F.

    1992-06-29

    The author reports on research to produce titanium nitride, titanium carbide, vanadium nitride, and vanadium carbide from organometallic compounds using chemical vapor deposition. He also describes exploratory work to synthesize heterobimetallic complexes of titanium and vanadium, with a view to producing a single precursor of V-Ti-C-N ceramic.

  13. Heterogeneous precipitation of niobium carbide in the ferrite by Monte Carlo simulations; Cinetique de precipitation heterogene du carbure de niobium dans la ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Hin, C

    2005-12-15

    The precipitation of niobium carbides in industrial steels is commonly used to control the recrystallization process or the amount of interstitial atoms in solid solution. It is then important to understand the precipitation kinetics and especially the competition between homogeneous and heterogeneous precipitation, since both of them have been observed experimentally, depending on they alloy composition, microstructure and thermal treatments. We propose Monte Carlo simulations of NbC precipitation in {open_square}-iron, based on a simple atomic description of the main parameters which control the kinetic pathway: - Realistic diffusion properties, with a rapid diffusion of C atoms by interstitial jumps and a slower diffusion of Fe and Nb atoms by vacancy jumps; - A model of grain boundaries which reproduces the segregation properties of Nb and C; - A model of dislocation which interacts with solute atoms through local segregation energies and long range elastic field; - A point defect source which drives the vacancy concentration towards its equilibrium value. Depending on the precipitation conditions, Monte Carlo simulations predict different kinetic behaviors, including a transient precipitation of metastable carbides, an early segregation stage of C, wetting phenomena at grain boundaries and on dislocations and a competition between homogeneous and heterogeneous NbC precipitation. Concerning the last point, we highlight that long range elastic field due to dislocation favors clearly the heterogeneous precipitation on dislocations. To understand this effect, we have developed a heterogeneous nucleation model including the calculation of the local concentration of solute atoms around the dislocation, the change of the solubility limit relative to the solubility limit in bulk and the energy of precipitates in an elastic field. We have concluded that elastic field favors the heterogeneous precipitation through the fall in nucleation barrier. (author)

  14. AISI 304奥氏体不锈钢活性屏离子渗碳%Active Screen Plasma Carburizing of AISI 304 Austenitic Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    王建青; 王璐璐; 赵程

    2010-01-01

    利用活性屏离子热处理技术对AISI 304奥氏体不锈钢进行低温离子渗碳(ASPC)处理,可以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).处理后的奥氏体不锈钢可以在不降低耐蚀性能的基础上大幅度提高不锈钢表面的硬度,并解决了不锈钢直流离子渗碳温度均匀性差,工件存在边缘效应等问题,ASPC渗碳试样表面基本可以保持原色.

  15. Plasma Carburizing of Austenitic Stainless Steel at Low Temperature%奥氏体不锈钢低温离子渗碳

    Institute of Scientific and Technical Information of China (English)

    刘伟; 赵程; 窦百香; 刘春廷; 王建青

    2009-01-01

    为避免奥氏体不锈钢在渗碳过程中析出铬的碳化物而降低其原有的耐蚀性能,开发了低温离子渗碳处理技术.利用低温离子渗碳技术对AISI 316L、AISI 321和AISI 304 三种不同类型的奥氏体不锈钢进行了渗碳处理,并对不锈钢渗碳层组织和性能进行了研究.结果表明,渗碳温度、渗碳时间和基体材料成分对渗碳层的组织和性能都有重要的影响.渗碳温度在400~550 ℃时,AISI 316L和AISI 321不锈钢可以获得无碳化物析出的具有单一γc相结构的渗碳层;XRD分析结果证实了550 ℃是AISI 321和AISI 316L奥氏体不锈钢的临界渗碳温度,500 ℃是AISI 304不锈钢的临界渗碳温度,在此温度以上渗碳时,渗碳层有铬的碳化合物析出; 含有Mo或Ti的奥氏体不锈钢(AISI 316L,AISI 321)和不含Mo或Ti的不锈钢(AISI 304)相比,在400~500 ℃渗碳时可以获得较好的渗碳层.

  16. Analysis of Surface Pockmarks on the Carburized Gear%渗碳齿轮表面"麻点"缺陷分析

    Institute of Scientific and Technical Information of China (English)

    黄丽荣; 顾园; 汤宏智

    2009-01-01

    通过模拟生产工序各个环节的多次试验等方法,对某厂齿轮在热处理过程中产生"麻点"缺陷的原因进行了探析.结果表明,"麻点"产生的主要原因是因为盐浴热处理时加热盐的质量和脱氧操作不当、齿轮渗碳或二次加热时炉内保护气氛氧势高或不均匀及炉罐漏气等,它们都属于不完全氧化所产生的腐蚀.为此,提出了相应的简便的预防方法.

  17. Vieillissement thermique de diodes Schottky en carbure de silicium: validation de l'analyse de défaillance par le cas singulier

    OpenAIRE

    Denis, Patrick; Dherbécourt, Pascal; Latry, Olivier

    2014-01-01

    Des essais de vieillissement en stockage thermique à haute température (240 ̊C) ont été réalisés sur des diodes Schottky en boîtier TO220 du commerce dans des conditions d'utilisation en mode " Uprating " ou " Derating ". Les analyses ont révélé un mécanisme de défaillance combiné, composé d'une vaporisation de l'humidité présente en quantité importante préférentiellement à l'interface résine/semelle, induisant une dégradation libérant de l'espace, et d'un étalement/dérobement de la brasure s...

  18. Motor fuel demand analysis - applied modelling in the European union; Modelisation de la demande de carburant appliquee a l`europe

    Energy Technology Data Exchange (ETDEWEB)

    Chorazewiez, S

    1998-01-19

    Motor fuel demand in Europe amounts to almost half of petroleum products consumption and to thirty percent of total final energy consumption. This study considers, Firstly, the energy policies of different European countries and the ways in which the consumption of motor gasoline and automotive gas oil has developed. Secondly it provides an abstract of demand models in the energy sector, illustrating their specific characteristics. Then it proposes an economic model of automotive fuel consumption, showing motor gasoline and automotive gas oil separately over a period of thirty years (1960-1993) for five main countries in the European Union. Finally, forecasts of consumption of gasoline and diesel up to the year 2020 are given for different scenarios. (author) 330 refs.

  19. Fuel consumption of private cars in France 1988-2006; Consommations de carburants des voitures particulieres en France 1988-2006

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-12-15

    The results of this study come from the exploitation of the 'TNSworldpanel Petrol' inquiry launched in April 1987. This panel follows the consumption of 3300 cars belonging to individuals living in France (company vehicles are excluded). This is the only operation of this scale ever carried out in France. The main results indicate: the continuation of the average consumption decay of individual cars (all kind of fuel considered); a new and significant progress of diesel-fueled vehicles: 57% of the cars purchased by households (50% in 2003, 33% in 1995); a new decay of the total distance covered by households: -1.1% in parallel to the rise of fuel prices. (J.S.)

  20. La consommation de carburant des véhicules à partir d'un découpage atomique des déplacements Fuel Consumption by Vehicles from an Atomic Breakdown of Trips

    Directory of Open Access Journals (Sweden)

    Crauser J. P.

    2006-11-01

    Full Text Available Le calcul de la consommation d'énergie par des véhicules en circulation demande un équipement de capteurs embarqués; cette étude a pour objet de permettre une évaluation assez précise de la consommation sans appareillage. Elle s'appuie pour cela sur une approche nouvelle de l'analyse de la cinématique des déplacements, lesquels sont découpés en constituants élémentaires successifs ou séquences. A partir d'un important fichier de données cinématiques enregistrées sur des véhicules dans leurs conditions usuelles d'utilisation, il a été identifié 4 classes de séquences et 3 règles de successions de séquences au sein des déplacements. Les séquences types apparaissent comme des cycles de conduite représentatifs des conditions de circulation. Connaissant les consommations séquentielles (par mesure embarquée ou sur banc d'essai il devient facile de reconstituer les déplacements et leur consommation avec un simple cumul. La validité de ces résultats a fait l'objet d'une étude approfondie. Calculating power consumption by operating vehicles requires on-board sensors. The aim of this survey is to make a fairly accurate assessment of consumption without equipment. This is based on a new approach to the analysis of trip kinematics by breaking the trips down into successive elementary constituents or sequences. From a large file of kinematic data recorded for the vehicles under actual operating conditions, four classes of sequences were identified along with three rules for sequence succession during trips. Typical sequences appear as driving cycles that are representative of operating conditions. When the sequental consumptions are known (by on-board measurement or on a test bench, it becomes easy to reconstitute the trips and their consumption by a simple cumulation. The validity of these findings has been analyzed in depth.

  1. Irradiation effects and diffusion of fission products (cesium and iodine) in silicon carbide; Effets d'irradiation et diffusion des produits de fission (cesium et iode) dans le carbure de silicium

    Energy Technology Data Exchange (ETDEWEB)

    Audren, A

    2007-03-15

    Silicon carbide is envisaged as a cladding material for the nuclear fuel in the fourth generation reactors. The aim of this work is to study the capacity to retain fission products and the structure evolution of this material under the combined effects of temperature and irradiation. The low energy ion implantations and the incorporation of stable analogues of fission products (Cs and I) in single crystalline 6H-SiC samples were performed by using the ion implanter or the accelerator of the CSNSM. The high energy heavy ion irradiations were made at GANIL. The evolution of the implanted ion profiles and the crystal structure were studied by RBS and Channeling. Complementary information were obtained by using the UV-visible absorption spectroscopy. The low energy ion implantations at room temperature induce a fast structural damage in the crystal. On the other hand, it is possible to attain a small disorder rate in the crystal during implantation by increasing the implantation temperature (600 C). The high energy heavy ion irradiations do not damage the SiC crystals. On the contrary, they cause an annealing of the disorder created by the low energy implantations. The implanted ions (I) do not diffuse during low or high energy ion irradiations at room temperature and at 600 C. However, a diffusion of Cs ions was observed during a post-implantation annealing at 1300 C. At this temperature, the crystal which had an extended amorphous layer starts to recover a single-crystal structure. (author)

  2. The automobile of the future: engine technologies and automotive fuels developed by IFP; l'automobile du futur: les technologies moteurs et carburants developpes par l'IFP

    Energy Technology Data Exchange (ETDEWEB)

    Appert, O.; Pinchon, Ph.

    2004-07-01

    In front of the challenges of climate change and depletion of petroleum reserves, in front of the continuous strengthening of pollution regulations applied to automobile (Euro IV and V) and the advances of R and D, several ways of research can be explored to answer the mobility needs of the coming decades. The IFP takes stock of these topics in this press kit which comprises 11 documents: the synthesis of O. Appert and P. Pinchon's talk about 'the cleaner and multi-energies automobile of the future', the slides of this presentation, the future evolutions of automobiles motorizations, the long-term evolutions of engines/fuels (brief for the Panorama 2004 colloquium), diesel fuel in the USA (brief for the Panorama 2004 colloquium), bio-fuels in Europe (brief for the Panorama 2004 colloquium), diesel pollution abatement: efficient results from the IFP's diesel combustion process 'NADI'(TM), the presentation of the IFP scientific meeting of September 22-23, 2004 'which fuels for low CO{sub 2} engines?', the strategic positioning of IFP in the world energy and environmental context, the brochures 'IFP engines and fuels: a competitive advantage' and 'innovating for a sustainable development in the domain of energy'. (J.S.)

  3. 冲天炉熔炼优质高碳铁液及其增碳机理分析%Processes of Producing Qualified High-Carbon Gray Iron Melt with Cupola Furnace and Analysis on Its Carburizing Mechanism

    Institute of Scientific and Technical Information of China (English)

    杨文涛; 叶建

    2005-01-01

    冲天炉熔制高碳铁液有两种不同工艺途径,传统工艺是依靠加入足够比例的生铁获得,而现代工艺则通过焦碳使铁液充分渗碳获得.通过讨论并比较这两种不同工艺途径,并结合生产实践,提出了冲天炉稳定熔炼优质高碳铁液的工艺控制要点,阐述了冲天炉熔炼过程中铁液依靠焦碳增碳的机理.

  4. 提高渗碳淬火和氮碳共渗件质量的途径%Improvement on the Quality of Gas Carburized-quenched and Gas Nitrocarburized Parts

    Institute of Scientific and Technical Information of China (English)

    李志义

    2007-01-01

    分析了气体渗碳淬火件渗层中非马氏体组织的控制,从气源选择,渗碳机制,天然气质量及其净化,甲醇、氮气和液氨的质量控制,淬火冷却及回火,毛坯的预备热处理等方面论述了提高渗碳淬火件质量的措施,简述了氮碳共渗质量的控制和金相检验方法.

  5. Influence of plasma nitro carburization on fatigue properties in a 4340 steel with different microstructure; Infuencia da nitrocarbonetacao a plasma nas propriedades de fadiga de um aco 4340 com diferentes microestruturas

    Energy Technology Data Exchange (ETDEWEB)

    Ranieri, A.; Hashimoto, T.M. [UNESP, Guaratingueta, SP (Brazil). Faculdade de Engenharia (FEG); Baggio-Scheid, V.H.; Abdalla, A.J., E-mail: abdalla@ieav.cta.b [Departamento de Ciencia e Tecnologia Aeroespacial (IEAv/DCTA), Sao Jose dos Campos, SP (Brazil). Inst. de Estudos Avancados

    2010-07-01

    Three different routes of heat treatments were applied in samples of 4340 steel in order to modify the microstructures and mechanical properties. After this initial treatment was applied a plasma nitrocarburizing thermochemical treatment in a part of the samples, forming a layer of nitride (Fe{sub 4}N and Fe{sub 3}N{sub 2}) of about 10{mu}m, with high hardness, in order to improve the surface characteristics. The layer and microstructure were characterized with X-ray analysis, optical microscopy, confocal laser scanning and hardness test by microindentation. Tensile and fatigue tests show the influence of microstructure formed on the mechanical properties, the microstructure predominantly bainitic phase showed a better combination of ductility, toughness and fatigue life. After treatment nitrocarburizing was observed the effect of tempering, with a reduction in hardness of substrate and tensile strength. In steel with martensitic microstructure the fatigue life decreases. (author)

  6. Elaboration of silicon carbides nano particles (SiC): from the powder synthesis to the sintered ceramic; Elaboration de ceramiques nanostructurees en carbure de silicium (SiC): de la synthese de poudre a la ceramique frittee

    Energy Technology Data Exchange (ETDEWEB)

    Reau, A. [CEA Saclay, Dept. des Materiaux pour le Nucleaire (DEN/DANS/DMN/SRMA), 91 - Gif-sur-Yvette (France)

    2008-07-01

    Materials for the reactor cores of the fourth generation will need materials supporting high temperatures with fast neutrons flux. SiC{sub f}/SiC ceramics are proposed. One of the possible elaboration process is to fill SiC fiber piece with nano particles SiC powder and to strengthen by sintering. The aim of this thesis is to obtain a nano structured SiC ceramic as a reference for the SiC{sub f}/SiC composite development and to study the influence of the fabrication parameters. (A.L.B.)

  7. 42CrMo钢渗碳淬火齿轮弯曲疲劳极限快速测定%Rapid Assay Analysis of Bending Load Capacity Limit on 42CrMo Carburized-quenched Gear

    Institute of Scientific and Technical Information of China (English)

    赵富强; 王铁

    2011-01-01

    针对42CrMo钢生产新齿轮的需要,进行了齿轮弯曲疲劳强度试验.在对该材料进行化学成分分析和硬度检测后,提出基于LOCATI方法进行双齿脉动加载试验.根据试验所得数据,按统计学原理,拟合出S-N曲线,并获得置信度为95%、可靠度为95%的弯曲疲劳极限应力值.为该材料齿轮的弯曲疲劳可靠性设计、有限寿命设计提供了真实的试验依据.%In order to decide whether 42CrMo steel could be selected as gear-material, tests on the bending fatigue strength of gears are analyzed. After taking chemical composition analysis and hardness test of 42CrMo steel, the pulsating loading test based on the Locati method is proposed. Then in terms of the principle of statistics, a fitted N-S curve is obtained by processing the data gained from the test and the bending fatigue limit is achieved with a 95% of both confidence and reliability. They provide the experimental basic data for the gear's reliability design and limited life design.

  8. Theoretical study of silicon carbide under irradiation at the nano scale: classical and ab initio modelling; Etude theorique a l'echelle nanometrique du carbure de silicium sous irradiation: modelisation classique et ab initio

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, G

    2006-10-15

    The behaviour of silicon carbide under irradiation has been studied using classical and ab initio simulations, focusing on the nano scale elementary processes. First, we have been interested in the calculation of threshold displacement energies, which are difficult to determine both experimentally and theoretically, and also the associated Frenkel pairs. In the framework of this thesis, we have carried out simulations in classical and ab initio molecular dynamics. For the classical approach, two types of potentials have been used: the Tersoff potential, which led to non satisfactory results, and a new one which has been developed during this thesis. This potential allows a better modelling of SiC under irradiation than most of the empirical potentials available for SiC. It is based on the EDIP potential, initially developed to describe defects in silicon, that we have generalized to SiC. For the ab initio approach, the feasibility of the calculations has been validated and average energies of 19 eV for the C and 38 eV for the Si sublattices have been determined, close to the values empirically used in the fusion community. The results obtained with the new potential EDIP are globally in agreement with those values. Finally, the elementary processes involved in the crystal recovery have been studied by calculating the stability of the created Frenkel pairs and determining possible recombination mechanisms with the nudged elastic band method. (author)

  9. Opening talk given by M. Dominique Maillard at the professional colloquium of the French federation of fuels; Discours d'ouverture prononce par M. Dominique Maillard au colloque professionnel de la Federation francaise des combustibles et des carburants

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This talk, given by D. Maillard, general director of energy and raw materials, presents first the 2004 world situation of petroleum products in terms of prices and production capacity and the role played by investment funds in this situation. Then, he proposes some short-term actions to be implemented: encouraging investment efforts in exploration-production, preservation of strategic stocks, influencing the consumers behaviour in order to reduce the demand, assigning exceptional financial helps to professionals whose activity is threatened by the rise of petroleum products price. In the last part of his talk, D. Maillard wants to reassure the petroleum products retailers about the evolutions of their profession in this context of prices inflation. The government will harmonize the tax discrepancies between natural gas and gas oil and will ensure the equilibrium between the different forms of trade in the petroleum products sector in order to maintain a sound competition between the small and big retailers. (J.S.)

  10. Développement d’une approche intégrée de PHM – Prognostics and Health Management : Application au Circuit Carburant d’un Turboréacteur

    OpenAIRE

    LAMOUREUX, Benjamin

    2014-01-01

    Pour les constructeurs de moteurs d'avions comme Snecma, la disponibilité est un des enjeux clés de l'avenir. En effet, la limitation des retards et annulations de vols ainsi que la réduction de la fréquence et de la durée des opérations de maintenance pourraient entraîner des économies importantes. Pour accroître la disponibilité, l'outil le plus utilisé actuellement est le "prognostics and health management" (PHM). La première contribution de la thèse est de proposer des cadres terminologiq...

  11. Densification of silicon and zirconium carbides by a new process: spark plasma sintering; Densification des carbures de silicium et de zirconium par un procede innovant: le spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Guillard, F

    2006-12-15

    Materials research for suitable utilization in 4. generation nuclear plants needs new ways to densify testing components. Two carbides, silicon and zirconium carbide seems to be the most suitable choice due to their mechanical, thermal and neutron-transparency properties against next nuclear plant specifications. Nevertheless one main difficulty remains, which is densifying them even at high temperature. Spark Plasma Sintering a new metal-, ceramic- and composite-sintering process has been used to densify both SiC and ZrC. Understanding bases of mass transport mechanisms in SPS have been studied. Composites and interfaces have been processed and analyzed. This manuscript reports original results on SiC and ZrC ceramics sintered with commercial powder started, without additives. (author)

  12. Algogroup: Towards a Shared Vision of the Possible Deployment of Algae to Biofuels Algogroup : vers une vision partagée du possible déploiement de la conversion des algues en carburants

    Directory of Open Access Journals (Sweden)

    Montagne Xavier

    2013-10-01

    Full Text Available A strong interest has been focused from several years on the algae pathway for energy production, especially for transportation fuels called third generation biofuel or G3 biofuel, and mainly from microalgae route, considering it could be a high potential alternative strategy for renewable energy and fuel production. Algae, and especially microalgae, present significant advantages compared with land resources, such as much higher productivity and lack of competition with food applications. Nevertheless, based on current knowledge, the production of an algae biomass for energy remains a difficult target to reach, due to the numerous existing hurdles such as the energetic yield and the economic positioning, without neglecting the environmental and societal aspect. Unlike first generation (GI and a few second generation biofuel (G2 processes, G3 biofuel processes are far from the industrialization step. In 2010, under the initiative of IFP Energies nouvelles, Airbus, Safran, EADS IW and the “Académie des Technologies”, launched a French national study of the potential of the algae sector as resources for the so called G3 biofuel production. This study was called “Algogroup” and led by IFP Energies nouvelles. The objective was to obtain a shared vision of the deployment possibilities. It led to the creation of this Algogroup task force with the previous partners, adding Sofiprotéol, INRA1, IFREMER1, CEVA1 and the Agrimip pole to combine all available knowledge and determine the responses which could be given to the existing questions. The Algogroup objective was to facilitate vision sharing between participating organisations and industrials on the technical improvements, the probabilities of success, the R&D needs and the development perspectives, while paying close attention to the obstacles which have to be alleviated to improve the positioning of the algae pathway. To reach this target, Algogroup has explored several axes, which enabled a thorough analysis of the potentials and limits of the technology: from the species selection to the harvesting (lipid extraction/recovery, including environmental and economical aspects. This paper focuses on some main aspects of the Algogroup study related to economical positioning and environmental terms, specially Life Cycle Analysis (LCA . A large share of the work was dedicated to microalgae, but since it was also considered important to examine the potential role of macroalgae, a specific analysis was conducted on this aspect. It has enabled the group to issue some recommendations such as a need for an integrated approach, need for tools to run comprehensive technico-economic assessments, including co products valorisation. Despite the limited amount of reliable information currently available on the algofuel sectors, especially in terms of environmental balance, numerous challenges still remain to be taken up to make these sectors credible and profitable, both technically, economically and environmentally. On the economic aspect the estimated costs for future microalgae biofuels remain in a very broad range from $2/Gal to $7/Gal. There remains great potential to decrease microalgae oil production costs, but this has to be considered very carefully given the large amount of underlying assumptions. Moreover, as yet underlined, microalgae biofuels are not currently being produced at a commercial scale, thus these are only potential scenarios, which will have to be confirmed. And finally, several technologies can be used to produce microalgae oil and location possibilities are proposed. Another key point is that, in a large majority of scenarios, the economic viability of the pathway relies on the valorisation of what one usually calls co-products. Valorisation of co-products is not considered a valid option in the long-term as no market identified today could absorb the quantities associated to a new fuel market. Besides, environmental studies have demonstrated that the energetic balance was not favourable at present, based on current processes, but the variation range of the results let some space for significant improvements. The balance of greenhouse gas emissions was favourable, and there also the variation range was very wide. As regards the other environmental impact categories, however, the uncertainties are too great to draw any conclusions. Because of the heterogeneity of approaches and results for the development of the algaepathway, we must bear in mind that without reliable and robust assessments of these sectors it will not be possible to direct their technical development sustainably. Macroalgae as a resource for biofuels production are very far from being a commercial reality, but do present some advantages such, for green algae, exhibiting several similarities with current GI and G2 feedstock, being producers of starch and unlignified cellulose. Nevertheless, they also contain other specific compounds. Red and brown macroalgae are currently the most produced species, but their composition calls for the development of new transformation processes. Although technically feasible at lab-scale, the economic viability of such processes is being endangered by the complexity of the processes involved and the numerous steps required as well as by non-technical issues such as competition with other markets like green chemistry. To have a true share of the future fuel mix, macroalgae production needs to be increase by a dozen- time fold. This increase should not be done without social acceptance or at the expenses of the environment. This issue was adressed for microalgae, but data on macroalgae are currently lacking to be able to conduct Life Cycle Assessment (LCA on this very specific environment. There are also additional problems to be taken into account, such as the lack of legislation or conflicts of usage with existing sea activities for example. Potential for high tonnage production seems real, but the challenge is to federate existing actors and new ones to build a new agro-industry. As a conclusion, no true leveraging option, leading to significant breakthroughs has really emerged as a short term solution, but wide spaces for significant improvement could be envisaged and more laboratory and pilot works have to be achieved before being able to move to a higher scale, leading to the first step toward industrial production. Depuis quelques années, un intérêt croissant pour la production d’algues, notamment les micro-algues, pour la production d’énergie a été observé, spécialement pour la production de biocarburants pour le transport routier et aérien, filière que l’on a coutume de qualifier de troisième génération. Les algues et spécialement les micro-algues affichent de nombreux avantages comparés aux ressources terrestres, comme par exemple une productivité nettement plus élevée et l’absence de compétition avec les filières alimentaires. Néanmoins, l’état actuel des connaissances ne conduit pas à penser qu’un développement de la culture de micro-algues pour la production d’énergie soit possible à court-moyen terme en raison de nombreux écueils à lever comme la balance énergétique, le positionnement économique sans oublier les aspects sociétaux et environnementaux. Contrairement aux filières de première génération et certaines filières de seconde génération, les biocarburants de troisième génération sont encore loin de l’industrialisation mais la nécessité de disposer d’une analyse commune et partagée par l’ensemble des acteurs de la filière est nécessaire. Ainsi, en 2010, à l’initiative d’IFP Energies nouvelles, Airbus, Safran, EADS IW, et l’Académie des Technologies ont mis en place un groupe d’étude national dédié à l’étude du potentiel de la filière micro-algues pour la production de biocarburants G3. Ce groupe, nommé Algogroup, piloté par IFP Energies nouvelles a eu comme objectif d’aboutir à une vision partagée d’un possible déploiement de la filière G3. Outre les membres fondateurs, Algogroup a aussi intégré les expertises dans le domaine, de Sofiprotéol, de l’INRA1, de IFREMER1, du CEVA1, de Agrimip ainsi que de nombreux autres laboratoires et industriels. Les travaux menés au sein d’Algogroup ont donc permis de collecter un ensemble de données sur le potentiel et les limites de la filière, la position des industriels et des laboratoires, sur les axes de recherches nécessaires à mettre en oeuvre pour permettre à la filière de se développer. La réflexion a été structurée selon différents thèmes. Les aspects technologiques : quelles souches, quel mode de culture, de récolte, les aspects économiques ainsi que les aspects environnementaux. Ce papier met l’accent sur les résultats d’Algogroup sur le positionnement économique et environnemental des micro-algues. En parallèle, une réflexion sur le potentiel des macro-algues a aussi été conduite au sein d’Algogroup. A ce jour, uniquement un nombre limité de données est accessible pour le secteur des “algocarburants” et s’engager dans la construction d’une telle filière est encore prématuré. Ainsi les résultats provenant d’Algogroup seront de précieuses contributions à l’élaboration d’une feuille de route Algocarburants. Sur un plan économique, les coûts estimés des futurs biocarburants fabriqués à partir de micro-algues s’étaleront dans une fourchette de 2 à 7 $/Gal. Cette situation laisse à penser qu’un large champ de possibilités est envisageable pour réduire le coût de production des huiles algales mais il faut toutefois rester très prudent car les scenarii conduisant à ces diminutions reposent sur des hypothèses qu’il faudra démontrer. En effet, ces scenarii considèrent des technologies et des localisations de production très variables. Un autre point clé des modèles économiques analysés est que dans une large majorité de ces scenarii, la viabilité économique repose sur la valorisation des coproduits. De telles options ne sont pas considérées comme acceptables sur le long terme en raison de l’incertitude qui règne sur les capacités d’absorption par le marché de ces produits lorsqu’ils seront liés à une production en grosses quantités de biocarburants. Considérant le volet environnemental, le travail a démontré que la balance énergétique n’était pas favorable, en se référant aux procédés explorés disponibles. Toutefois, les variations enregistrées laissent la place à des possibilités d’amélioration. Concernant les émissions de gaz à effet de serre, le bilan apparait favorable mais là aussi avec une plage de variations très large. Pour les autres aspects environnementaux, les incertitudes sont trop grandes pour conclure. Par ailleurs, en raison des très grandes hétérogénéités des approches et des résultats publiés pour le développement d’une filière micro-algues, il apparait que sans évaluation fiable et robuste du secteur, il n’est pas possible de considérer à ce jour ledéveloppement des techniques comme totalement compatibles avec les critères de durabilité. Pour les macro-algues, nous sommes encore très loin de pouvoir les considérer comme une ressources pour la production de biocarburants mais celles-ci présentent des avantages, comme pour le cas des algues vertes des similitudes avec les ressources utilisées pour les filières G1 ou G2. Concernant les algues brunes et les algues rouges qui sont aujourd’hui les espèces les plus produites, leurs compositions demandent le développement de nouveaux procédés pour leur valorisation. Bien que ces procédés soient faisables à l’échelle du laboratoire, la viabilité économique à grande échelle est à démontrer en raison de la complexité et du nombre d’étapes requis par ces procédés tout comme la compétition de cette filière avec les autres marchés, comme celui de la chimie verte. Par ailleurs, pour que les macro-algues puissent avoir un réel devenir dans le mix biocarburants, leur production doit être considérablement augmentée. Ce point ne peut être considéré sans avoir évalué l’impact sociétal et environnemental et aujourd’hui peu de données sont accessibles pour bien apprécier ces 2 volets. Enfin, il faudrait bien analyser tous les aspects législatifs liés au développement de culture à gros tonnages en mer. En dépit de ces aspects, le potentiel de production de grosses quantités semble réel. En conclusion, le travail effectué par Algogroup n’a pas fait émerger de réelles ruptures permettant d’envisager un développement à court moyen terme de la filière algocarburants mais des possibilités d’amélioration peuvent être envisagées. Ceci demande de poursuivre les travaux au niveau du laboratoire et à l’échelle du pilote avant de passer à une échelle préindustrielle.

  13. AISI 304奥氏体不锈钢低温离子渗碳工艺优化研究%Process Optimizing about Low Temperature Plasma Carburizing Of AISI 304 Austenitic Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    王建青; 赵程

    2010-01-01

    用正交实验法研究了AISI 304奥氏体不锈钢低温离子渗碳工艺.结果表明.优化后的奥氏体不锈钢低温离子渗碳工艺参数为渗碳温度500℃、C3H8:H2:=1:30、氩气流量20 ml/min、渗碳时间6 h.用优化工艺参数处理的奥氏体不锈钢表面可获得单-的Sc相组织,硬度高达780 HV0.05.

  14. 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.

  15. To break away from fossil fuels : a contribution to solve climatic change and energy security for Quebec; S'affranchir des carburants fossiles : une contribution a la lutte aux changements climatiques et a la securite energetique du Quebec

    Energy Technology Data Exchange (ETDEWEB)

    Bonin, P.; Seguin, H.; Waridel, L.

    2006-06-15

    In response to growing energy demands, Quebec has proposed the construction of 3 deep water terminals to accommodate methane tankers which transport liquefied natural gas (LNG). This paper focused on the proposed Gros Cacouna Port project in the St. Lawrence Seaway which is currently under study and subject to approval. Equiterre, questioned the energy security aspect of the proposal and argued that increasing Quebec's reliance on increasingly expensive energy would decrease energy security. In addition, importation of LNG would bring a clear exit of capital outside the province. Equiterre also argued that reliance on fossil fuels should be decreased in order to mitigate greenhouse gas emissions which contribute to climate change. The organization questioned whether the economic and social need for the proposed project justifies a greater dependency on fossil fuels and the associated impact on the environment and fragile ecosystems of the St. Lawrence. It was suggested that alternative solutions such as renewable energy sources and energy efficiency should be explored in order to promote sustainable development, increase energy security and reduce greenhouse gases. Equiterre argued that Quebec can and must decrease, and even eliminate, its dependence on fossil fuels, including natural gas, for Quebec's economic, social and environmental well-being. For these reasons, Equiterre recommended that the proposed project be rejected, particularly since the project proponents failed to show the real impact that the project would have on Quebec markets. 72 refs., 10 tabs., 21 figs.

  16. 渗碳

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Carbo-Austempering - A new wrinkle?;Carburization Resistance of Austenitic Alloys in CH{sub}4-CO{sub}2-H{sub}2 Gas Mixtures at Elevated Temperatures;Causes of variability in gear fatigue testing; Change of the structure and mechanical properties of carburized layer as a result of its plastic deformation

  17. 渗碳

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    [ 篇名 ] A quantitative alternative to HV test based on hardness-thermal diffusivity carbon-dependent correlation applied to CO{sub}2-1aser annealed or quenched carburized steel,[ 篇名 ] A quantitative alternative to the Vickers hardness test based on a correlation between thermal diffusivity and hardness - applications to laser-hardened carburized steel,[篇名] Air-cooled fans reduce maintenance issues,[ 篇名 ] An evaluation of atmosphere and vacuum carburizing methods for the heat treatment of gears,[篇名] Application of natural gas to vacuum carburizing,[篇名] ASSET, an information system for alloy corrosion in high temperature gases,[ 篇名 ] Bending fatigue life analysis of carburized components using strain life and fracture mechanics approaches。

  18. Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, Steven J [ORNL; Hsu, Julia [Massachusetts Institute of Technology (MIT)

    2010-11-01

    The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.

  19. Effects of WC Particle Size and Co Content on the Graded Structure in Functionally Gradient WC-Co Composites

    Directory of Open Access Journals (Sweden)

    Yuan Yigao

    2016-01-01

    Full Text Available Functionally gradient WC-Co composites having a Co depleted surface zone and not comprising the h phase can be manufactured via carburizing process. During carburizing, besides carburizing process parameters, the microstructural parameters of WC-Co materials, such as WC grain size and Co content, also have significant influences on the formation of Co gradient structure. In this study, the effects of WC particle size and Co content on the gradient structure within gradient hardmetals have been studied, based on a series of carburizing experiments of WC-Co materials with different WC particle sizes and cobalt contents. The results show that both the thickness and the amplitude of the gradients within gradient WC-Co materials increase with increasing initial WC particle size and Co content of WC-Co alloys. The reason for this finding is discussed.

  20. 差动齿轮

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A novel class of intelligent power-assist systems based on differential CVT;Development of high-strength case hardening steel;Development of torque sensing LSD with cone clutch aiming at smaller size and lighter weight;Effect of Core Hardness and Case Depth on Low-Cycle-Impact-Fatigue Property in Carburized Steel;Effect of core hardness and ECD on low-cycle-impact-fatigue property in carburized steel……

  1. Nanostructure-based Processes at the Carbonizing Steels

    Directory of Open Access Journals (Sweden)

    L.I. Roslyakova

    2015-12-01

    Full Text Available The studies of nanostructure-based processes carburizing steels showed that oxidizing atmosphere when carburizing steel contains along with carbon dioxide (CO2 + C = 2CO molecular and atmospheric oxygen (O2 + 2C = 2CO; O + C = CO released from the carbonate ВаСОз during its thermal dissociation. Intensive formation of CO provides high carbonizing ability of carbonate-soot coating and steel.

  2. Surface processing to improve the fatigue resistance of advanced bar steels for automotive applications

    Directory of Open Access Journals (Sweden)

    David K. Matlock

    2005-12-01

    Full Text Available With the development of new steels and processing techniques, there have been corresponding advances in the fatigue performance of automotive components. These advances have led to increased component life and smaller power transfer systems. New processing approaches to enhance the fatigue performance of steels are reviewed with an emphasis on carburizing and deep rolling. Selected examples are presented to illustrate the importance of the base steel properties on the final performance of surface modified materials. Results on carburized gear steels illustrate the dependence of the fatigue behavior on carburizing process control (gas and vacuum carburizing, alloy additions and microstructure. The importance of retained austenite content, case and core grain size as controlled by processing and microalloy additions, extent of intergranular oxidation, and the residual stress profile on fatigue performance is also illustrated. Specific recent results on the use of microalloying elements (e.g. Nb and process history control to limit austenite grain growth at the higher carburizing temperatures associated with vacuum carburizing are highlighted. For crankshaft applications, deep rolling is highlighted, a process to mechanically work fillet surfaces to improve fatigue resistance. The influence of the deformation behavior of the substrate, as characterized by standard tensile and compression tests, on the ability to create desired surface properties and residual stress profiles will be illustrated with data on several new steels of current and future interest for crankshaft applications.

  3. Development and validation of an Eulerian model towards the simulation of fuel injection in internal combustion engines; Developpement et validation d'un modele eulerien en vue de la simulation des jets de carburants dans les moteurs a combustion interne

    Energy Technology Data Exchange (ETDEWEB)

    Truchot, B.

    2005-12-15

    The objective of this work is to develop an Eulerian two phase model to improve the prediction of fuel injection in internal combustion engines, particularly the dense liquid zone close to the nozzle. Lagrangian models, usually used in engine simulations, are based on the assumption of dispersed two phase flows with low liquid volume fraction, which is not fulfilled in the case of direct injection engine technology. Different Eulerian approaches are available in the literature. Physical phenomena that occur near the nozzle and characteristics of each model lead to the choice of a two fluids two pressures model. Several open terms appear in the equations of the model: exchange between the two phases and turbulent correlations. Closures of exchange terms are based on the spherical droplets hypothesis while a RANS approach is adopted to close turbulent correlations. This model has been integrated in the IFP CFD code, IFP-C3D. Several numerical tests and analytical validations (for single and two phase flows) have been then carried out in order to check the correct implementation of equations and the predictivity of the model and closures. Modifications in the turbulent model of the gas have required validations in both the gas phase (flow behind a sudden enlargement) and the liquid phase (pure liquid injection). A two phase mixing layer has been then used to validate the whole model. Finally, injection tests have been achieved under realistic conditions (similar to those encountered in automotive engines) in order to check the feasibility of engine computations using the developed Eulerian approach. These tests have also allowed to check the compatibility of this approach with the specificities of engine simulations (especially mesh movement). (author)

  4. Study of a heat flux generated by shock waves interaction on the fuel injection masts of a supersonic combustion stato-reactor; Etude du flux thermique genere par interaction d`ondes de choc sur les mats d`injection de carburant d`un statoreacteur a combustion supersonique

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, F.

    1996-07-01

    The realisation of hypersonic vehicles induces the resolution of an important number of technological problems bound to the evolution of a body in a very speed medium. The flux can reach the values of Mw/m{sup 2} and such values are reached when an obstacle is introduced in a supersonic flow perturbed by shock waves interferences. That is the subject of the present study. The first part of this report concerns some generalities in the field of flux generated by shock waves interferences, that allows to precise the configuration chosen for this study and the justification of the experimentations. The second part gives the details of the experimentations, their results and their physical interpretation. (N.C.) 25 refs.

  5. Study of irradiation effects in the silicon carbide cubic polytype by photoluminescence and electron spin resonance spectroscopies; Etude des effets d'irradiation dans le polytype cubique du carbure de silicium par les techniques spectroscopiques de photoluminescence et de resonance paramagnetique electronique

    Energy Technology Data Exchange (ETDEWEB)

    Lefevre, J

    2008-01-15

    This experimental work has consisted in the study of point defects induced by an electronic irradiation in the cubic crystallographic structure of silicon carbide with low temperature photoluminescence and electron spin resonance spectroscopies. The first one of these measurement tools has allowed to estimate the displacement threshold energy in the silicon sub-lattice and then to analyze the thermal stability of the irradiation defects in the low temperature range: (10-300 K) and then in the high temperature range: (300-1400 K). Besides, on the base of a recent theoretical model, this thesis has confirmed the proposition of the isolated silicon antisite for the D1 center whose running beyond the nominal running temperature of fission nuclear reactors (generation IV), for which SiC is in part intended, seems to be particularly problematic. Measurements carried out by ESR under lighting have at last allowed to detect a new defect in its metastable spin state S=1, possibly associated to a silicon interstitial configuration. (O.M.)

  6. Behaviour analysis of the fuel injected in the intake manifold of port-injected spark ignition engines: modeling and experimental validation; Analyse du comportement du carburant injecte dans les conduits d`admission des moteurs a allumage commande a injection multipoint: modelisation et validation experimentale

    Energy Technology Data Exchange (ETDEWEB)

    Sches, C.

    1999-01-27

    In order to limit pollutant emissions resulting from transient engine operation, the mastering of mixture formation is essential. In this context, an interactive work was undertaken between a modeling job and an experimental study, to get better understanding of the mechanisms of fuel dynamic behavior in the intake manifold of port-injected spark-ignition engines. The experimental study, elaborated thanks to experimental designs, showed out two essential factors: injection timing and coolant liquid temperature, which act on the fuel dynamic behavior through a second order filter. Then, a phenomenological modeling was established and validated, to analyze the various phenomena influencing mixture formation and to calculate the air/fuel ratio evolutions during transient operation. This program uses the results of a 3D model describing the fuel spray transportation, evaporation and impact on the port walls. The calculation does not need any boundary conditions and the running times are vary satisfactory. We showed that a correct description of the liquid fuel film was necessary to get good prediction of the mixture fuel/air ratio. The spray modeling, which is necessary, can however be kept simple. Future work may develop either in the engine control filed (injection strategies development, optimization of the injection system configuration, ...), or in the theoretical field (better modeling of fuel film displacement or of secondary atomization of the fuel on the intake valve). (author) 79 refs.

  7. Déploiement de la chaîne logistique de l'hydrogène pour le marché des carburants en 2050 :
    Conception et développement d'un outil d'optimisation pour l'analyse de scénarios

    OpenAIRE

    Patay, Emmanuelle

    2008-01-01

    The deployment of a market for hydrogen energy is a new problem, considered by governments, industrials 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 distribu...

  8. NF EN 14214. - Automotive fuels. - Fatty acid methyl esters (FAME) for diesel engines. - Requirements and test methods; NF EN 14214. - Carburants pour automobiles. - Esters methyliques d'acides gras (EMAG) pour moteurs Diesel. - Exigences et methodes d'essais

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-04-01

    This standard specifies requirements and test methods for marketed and delivered fatty acid methyl esters (FAME) to be used either as automotive fuel for diesel engines, at 100% concentration, or as an extender for automotive fuel for diesel engines, in accordance with the requirements of EN 590. At 100% concentration it is applicable to fuel for use in diesel engine vehicles designed or subsequently adapted to run on 100% FAME.

  9. 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.

  10. Properties of point defects either native or induced by irradiation in the 3C and 6H polytypes of silicon carbide determined by positron annihilation and EPR; Proprietes des defauts ponctuels natifs et induits par irradiation dans les polytypes 3C et 6H du carbure de silicium determinees par annihilation de positons et RPE

    Energy Technology Data Exchange (ETDEWEB)

    Kerbiriou, X

    2006-02-15

    Potential applications of silicon carbide (SiC) in micro-electronics have justified many studies on point defects, which play an important role in the electrical compensation. Moreover, this material has many assets to take part in the fissile materials confining in the gas cooled reactors of the future (4. generation). In this thesis, we have used Electronic Paramagnetic Resonance and Positron Annihilation Spectroscopy to study the properties of point defects (nature, size, charge state, migration and agglomeration during annealing), either native or induced by irradiation with various particles (H{sup +}, e{sup -}, carbon ions), in the 3C and 6H polytypes of SiC. The positron annihilation study of native defects in 6H-SiC has shown the presence of a strong concentration of non-vacancy traps of acceptor type, which are not present in the 3C-SiC crystals. The nature of the defects detected after irradiation with low energy electrons (190 keV) depends on the polytype. Indeed, while silicon Frenkel pairs and carbon mono-vacancies are detected in the 6H crystals, only carbon mono-vacancies are detected in the 3C crystals. We propose that these differences concerning the populations of detected point defects result from different values of the silicon displacement threshold energy for the two polytypes (approximately 20 eV for 6H and 25 V for 3C). In addition, the irradiations with 12 MeV protons and 132 MeV carbon ions have created silicon mono-vacancies as well as VSi-VC di-vacancies. Neither the particle (protons or ions carbon), nor the polytype (3C or 6H) influence the nature of the generated defects. Finally the study of the annealing of 6H-SiC monocrystals irradiated with 12 MeV protons have revealed several successive processes. The most original result is the agglomeration of the silicon mono-vacancies with the VSi-VC di-vacancies which leads to the formation of VSi-VC-VSi tri-vacancies. (author)

  11. Low temperature oxidation, co-oxidation and auto-ignition of olefinic and aromatic blending compounds: Experimental study of interactions during the oxidation of a surrogate fuel; Oxydation, co-oxydation et auto-inflammation a basses temperatures d'alcenes et aromatiques types: etude experimentale des interactions au sein d'un carburant-modele

    Energy Technology Data Exchange (ETDEWEB)

    Vanhove, G.

    2004-12-15

    The low-temperature (600-900 K) and high-pressure (5-25 bar) oxidation and auto-ignition of the three position isomers of hexene, of binary mixtures of 1-hexene, toluene and iso-octane, and of a surrogate fuel composed of these three compounds were studied in motor conditions using a rapid compression machine. Auto-ignition delay times were measured as long as intermediate products concentrations during the delay. The results show that the oxidation chemistry of the hexenes is very dependent on the position of the double bond inside the molecule, and that strong interactions between the oxidation mechanisms of hydrocarbons in mixtures can occur. The data obtained concerning the surrogate fuel give a good insight into the behaviour of a practical gasoline after an homogeneous charge compression. (author)

  12. Modification in the Microstructure of Mod. 9Cr-1Mo Ferritic Martensitic Steel Exposed to Sodium

    Science.gov (United States)

    Prasanthi, T. N.; Sudha, Cheruvathur; Paul, V. Thomas; Bharasi, N. Sivai; Saroja, S.; Vijayalakshmi, M.

    2014-09-01

    Mod. 9Cr-1Mo is used as the structural material in the steam generator circuit of liquid metal-cooled fast breeder reactors. Microstructural modifications on the surface of this steel are investigated after exposing to flowing sodium at a temperature of 798 K (525 °C) for 16000 hours. Sodium exposure results in the carburization of the ferritic steel up to a depth of ~218 µm from the surface. Electron microprobe analysis revealed the existence of two separate zones with appreciable difference in microchemistry within the carburized layer. Differences in the type, morphology, volume fraction, and microchemistry of the carbides present in the two zones are investigated using analytical transmission electron microscopy. Formation of separate zones within the carburized layer is understood as a combined effect of leaching, diffusion of the alloying elements, and thermal aging. Chromium concentration on the surface in the α-phase suggested possible degradation in the corrosion resistance of the steel. Further, concentration-dependent diffusivities for carbon are determined in the base material and carburized zones using Hall's and den Broeder's methods, respectively. These are given as inputs for simulating the concentration profiles for carbon using numerical computation technique based on finite difference method. Predicted thickness of the carburized zone agrees reasonably well with that of experiment.

  13. 碳化镍钼催化剂的制备及其甲烷干气重整活性%Preparation of a Nickel Molybdenum Carbide Catalyst and Its Activity in the Dry Reforming of Methane

    Institute of Scientific and Technical Information of China (English)

    Taro HIROSE; Yasushi OZAWA; Masatoshi NAGAI

    2011-01-01

    Nickel molybdenum carbide catalysts were prepared and their activities in the CO2 reforming of methane at a low CO2/CH4 reactant ratio were investigated using a microreactor at atmospheric pressure and at 973 K The effect of the catalyst preparation method and the Ni/Mo ratio on the increase in catalyst life and the promotion of catalytic activity were investigated using N2 adsorption, X-ray diffraction,temperature-programmed carburization, temperature-programmed reaction, and a reforming reaction. The 25Ni75Mo catalyst that was carburized at 813 K exhibited the highest hydrogen fonnation ability and gave the least carbon deposition. The incomplete carburization of the Mo oxide species in the catalyst that was carburized at a lower temperature gradually gave a more active carburized species. The NiMoOxCy in the catalyst was more active in hydrogen formation during the dry reforming of methane while β-Mo2C and η-Mo3C2 were less active.

  14. Nanograined WC-Co Composite Powders by Chemical Vapor Synthesis

    Science.gov (United States)

    Ryu, Taegong; Sohn, H. Y.; Han, Gilsoo; Kim, Young-Ugk; Hwang, Kyu Sup; Mena, M.; Fang, Zhigang Z.

    2008-02-01

    Nanograined tungsten carbide (WC) Co composite powders were prepared by a chemical vapor synthesis (CVS) process that has previously been used for preparing the aluminides of titanium and nickel and other metallic and intermetallic powders at the University of Utah. To determine the optimum condition for producing nanograined WC-Co composite powders, the effects of carburization temperature, CH4 to WCl6 ratio, CH4 to H2 ratio, CoCl2 contents, and residence time of WC on the powder composition and particle size were investigated. The reduction and carburization of the vaporized chlorides by CH4-H2 mixtures produced nanograined WC and Co composite powder, which sometimes contained small levels of W2C, W, or the η (Co3W3C) phase. The presence of these incompletely carburized phases can be tolerated because they can be fully carburized during the subsequent sintering process. These phases can also be fully carburized by a separate post-treatment. The products were characterized by using X-ray diffraction (XRD) and a transmission electron microscope (TEM). As a result, nanograined WC-Co composite with the particle size less than 30 nm was obtained.

  15. Characterization of complex (B + C) diffusion layers formed on chromium and nickel-based low-carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Pertek, A.; Kulka, M

    2002-12-30

    Combined surface hardening with boron and carbon was used for low-carbon chromium and nickel-based steels. The microstructure, boron contents, carbon profiles and chosen properties of borided layers produced on the carburized steels have been examined. These complex (B+C) layers are termed borburized layers. The microhardness profiles and wear resistance of these layers have been studied. In the microstructure of the borocarburized layer two zones have been observed: iron borides (FeB+Fe{sub 2}B) and a carburized layer. The depth (70-125 {mu}m) and microhardness (1500-1800 HV) of iron borides zone have been found. The carbon content (1.2-1.94 wt.%) and microhardness (700-950 HV) beneath iron borides zone have been determined. The microhardness gradient in borocarburized layer has been reduced in comparison with the only borided layer. An increase of distance from the surface is accompanied by a decrease of carbon content and microhardness in the carburized zone. The carbon and microhardness profiles of borided, carburized and borocarburized layers have been presented. A positive influence of complex layers (B+C) on the wear resistance was determined. The wear resistance of the borocarburized layer was determined to be greater in comparison with that for only borided or only carburized layers.

  16. Thermodynamic study and methanothermal temperature-programmed reaction synthesis of molybdenum carbide

    Science.gov (United States)

    Roohi, Parham; Alizadeh, Reza; Fatehifar, Esmaeil

    2016-03-01

    Nanostructured molybdenum carbide (Mo2C) was successfully prepared from molybdenum trioxide (MoO3) using methanothermal temperature-programmed reaction. Thermodynamic analysis indicated that in presence of methane, the formation of Mo2C from MoO3 occurs through the path of MoO3 → MoO2 → Mo2C. The carburized MoO3 was characterized using X-ray diffraction (XRD), CHNS/O analysis, Brunauer-Emmett-Teller (BET) analysis, and field-emission scanning electron microscopy (FESEM). At final carburization temperatures of 700 and 800°C and at methane contents ranging from 5vol% to 20vol%, Mo2C was the only solid product observed in the XRD patterns. The results indicated that the effect of methane content on the formation of the carbide phase is substantial compared with the effect of carburization time. Elemental analysis showed that at a final temperature of 700°C, the carbon content of carburized MoO3 is very close to the theoretical carbon mass percentage in Mo2C. At higher carburization temperatures, excess carbon was deposited onto the surface of Mo2C. High-surface-area Mo2C was obtained at extremely low heating rates; this high-surface-area material is a potential electrocatalyst.

  17. Determination of Concentration Dependent Diffusion Coefficients of Carbon in Expanded Austenite

    DEFF Research Database (Denmark)

    Hummelshøj, Thomas Strabo; Christiansen, Thomas; Somers, Marcel A. J.

    2008-01-01

    Abstract. In the present paper various experimental procedures to experimentally determine the concentration dependent diffusion coefficient of carbon in expanded austenite are evaluated. To this end thermogravimetric carburization was simulated for various experimental conditions and the evaluated...... composition dependent diffusivity of carbon derived from the simulated experiments was compared with the input data. The most promising procedure for an accurate determination is shown to be stepwise gaseous carburizing of thin foils in a gaseous atmosphere; the finer the stepsize, the more accurate...... the approximation of the diffusivity. Thermogravimetry was applied to continuously monitor the weight change of thin foils of AISI 316 during carburizing in CO-H2 gas mixtures for one of the simulated experimental procedures....

  18. Synthesis of nanosized tungsten carbide from phenol formaldehyde resin coated precursors

    Institute of Scientific and Technical Information of China (English)

    LUO Ji; GUO Zhimeng; GAO Yuxi; LIN Tao

    2008-01-01

    Nanosized tungsten carbide was synthesized from phenol formaldehyde resin (PF) coated tungsten precursors.The process has three steps in which nanosized tungsten particles were first coated with PF,then the precursors were carburized at 950℃,and finally the carburized powders were treated in flowing wet hydrogen atmosphere at 940℃ to remove the uncombined carbon.The obtained powders were characterizedusing X-ray diffraction analysis (XRD),field-emission scanning electron microscopy (FESEM),small angle X-ray scattering (SAXS),andcombustion-gas-volume method.The results indicated that single-phase WC could be synthesized using excessive PF as carburizer at a muchlower temperature compared with using mixed carbon black.After wet hydrogen treating,the mean size of the obtained WC particles was 94.5nm and the total carbon content was 6.18 wt.%.

  19. Ultrasonic cavitation erosion of a duplex treated 16MnCr5 steel

    Energy Technology Data Exchange (ETDEWEB)

    Mitelea, Ion; Ghera, Christian; Craciunescu, Corneliu M. [Timisoara Univ. (Romania). Dept. of Materials and Manufacturing Engineering; Bordeasu, Ilare [Timisoara Univ. (Romania). Dept. of Mechanical Machines, Equipments and Transportation

    2015-04-15

    Ultrasonic cavitation experiments using a piezoceramic-based apparatus, according to ASTM G32-2010, were performed on heat and thermochemically treated Cr - Mn low alloyed steel samples. The microstructure in annealed, carburized and tempered states as well as following a duplex treatment (carburized, surface induction hardening and tempering) was analyzed before and after the cavitation erosion tests. The results show the advantage of the duplex treatment, with a significant increase of up to 20 times of the cavitation erosion resistance compared to the annealed state and reveal that the main mechanism for surface deterioration is micro-cracking. The observations are important for the improvement of the behaviour for parts used in hydraulic equipment, for which the volume hardening following the carburization can be replaced by cost-efficient surface induction hardening treatments.

  20. Natural gas use in treatment of steel surfaces; Utilizacao de gas natural em tratamento de superficies de aco

    Energy Technology Data Exchange (ETDEWEB)

    Ferraz, Andre Dias; Machado, Antonio Rogerio; Rocha, Ivan; Azevedo, Jorge; Oshiro, Hugo K.; Konishi, Ricardo; Lehmkuhl, Willian [Companhia de Gas de Santa Catarina (SCGAS), Florianopolis, SC (Brazil); Piazza, Walter [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2011-12-21

    The surface treatments of metals, such as carburizing, rely on processing under high temperature in carbon rich atmospheres. The atmosphere is industrially generated using the partial oxidation of a carbon rich fuel, such as propane, butane or methanol. This article reports a study of the production of a carburizing atmosphere for surface treatment of steel from the partial oxidation of natural gas in a catalytic reactor. The reactor studied was a production size reactor with 300 mm of diameter and 1500 mm of length, packed with alumina supported nickel catalyst. The quality of the carburizing gas was evaluated from its carbon potential of the carburizing gas that was calculated from the concentrations of carbon monoxide (CO), carbon dioxide (CO{sub 2}), oxygen (O{sub 2}) and methane (CH{sub 4}) measured at the reactor's exit. The results indicate that CO concentration is very close to equilibrium, while CO{sub 2} is higher and CH{sub 4} is lower. Examining the reactor, the conclusion was that there was an axial temperature gradient, resulting in lower residence time under the required processing temperature. This resulted in smaller decomposition of CH{sub 4} and smaller production of CO{sub 2}. An equilibrium calculation of carbon potential, expressed as weight percent of carbon in iron, was developed to predict the possible optimizations of mixture composition and reactor temperature for a given required carbon potential. Conclusion: it is possible to generate a carburizing atmosphere under well controlled and repeatable conditions for the carbon potentials required for surface carburizing of steels in industrial processing using natural gas and air mixtures. (author)

  1. Effect of Nano Oil Additive Proportions on Friction and Wear Performance of Automotive Materials

    Directory of Open Access Journals (Sweden)

    A. Vadiraj

    2012-03-01

    Full Text Available The effect of nano boric acid and nano copper based engine and transmission oil additives in different volume ratios (1:10, 2:10, and 3:10 on friction and wear performance of cast iron and case carburized gear steel has been investigated. The results show that coefficient of friction increases with increase in volume ratio of engine oil additives and decreases with increasing in volume ratio of transmission oil additives. Cast iron substrate shows higher wear damage than case carburized gear steel. Nano copper additive with crystalline atomic structure shows more severe three body wear compared to boric acid with layered lattice structure.

  2. Flexible Furnace Concepts for Vacuum Heat Treatment Combined with High-pressure Gas Quenching

    Institute of Scientific and Technical Information of China (English)

    Karl Ritter; Stefan Wiebach

    2004-01-01

    IN the past five years the process combination of vacuum hardening, respectively vacuum carburizing with high-pressure gas quenching was successfully introduced to the market, especially in the manufacture of gears. In the meantime furnace concepts for various applications are available to the industry. In the following report three plant varieties are introduced, which differ in process flexibility and throughput. This report also explains criteria for the selection of a furnace in view of the existing application requirements. Besides this a short introduction is given into the vacuum carburizing process and the high-pressure gas quenching technology.

  3. Thermal residual stress analysis of diamond coating on graded cemented carbides

    Institute of Scientific and Technical Information of China (English)

    HUANG Zi-qian; HE Yue-hui; CAI Hai-tao; WU Cong-hai; XIAO Yi-feng; HUANG Bai-yun

    2008-01-01

    Finite element model was developed to analyze thermal residual stress distribution of diamond coating on graded and homogeneous substrates. Graded cemented carbides were formed by carburizing pretreatment to reduce the cobalt content in the surface layer and improve adhesion of diamond coating. The numerical calculation results show that the surface compressive stress of diamond coating is 950 MPa for graded substrate and 1 250 MPa for homogenous substrate, the thermal residual stress decreases by around 24% due to diamond coating. Carburizing pretreatment is good for diamond nucleation rate, and can increase the interface strength between diamond coating and substrate.

  4. Expanded austenite; crystallography and residual stress

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Hummelshøj, Thomas Strabo; Somers, Marcel A. J.

    2009-01-01

    The identity of expanded austenite as developing during low temperature nitriding and/or carburizing of austenitic stainless steel has been under debate since the very first observation of this phase. In the present article recent results obtained with i) homogeneous samples of various uniform co...

  5. Effect of Plastic Pre-straining on Residual Stress and Composition Profiles in Low-Temperature Surface-Hardened Austenitic Stainless Steel

    DEFF Research Database (Denmark)

    Bottoli, Federico; Christiansen, Thomas Lundin; Winther, Grethe;

    2016-01-01

    or nitrocarburized. The residual stress profiles resulting from the thermochemical low-temperature surface treatment were measured. The results indicate high-residual compressive stresses of several GPa’s in the nitrided region, while lower-compressive stresses are produced in the carburized case. Plastic...

  6. Effects of Nitride on the Tribological Properties of the Low Carbon Alloy Steel

    Directory of Open Access Journals (Sweden)

    Yuh-Ping Chang

    2013-01-01

    Full Text Available The technology of composite heat treatment is used popularly for low friction and wear resistance of drive elements. A large number of papers about the heat treatment technology had been proposed. Especially, the nitride treatment has been used widely for the purpose of wear resistance and low friction in the industry. Therefore, the self-developed vertical ball/disk friction tester with the measurement system was used to study the effects of nitride on the tribological properties of the low carbon alloy steel—SCM415— in this study. The experiments were conducted under dry and severe wear conditions. The variations of friction coefficient and surface magnetization were simultaneously recorded during dynamic friction process. After each test, the microstructures of the wear particles were observed and analyzed under a SEM, and the depth of wear track is measured by means of a surface tester. According to the experimental results, the wear resistance of the specimens with carburizing-nitride is significantly larger than the case of nitride-carburizing. Moreover, the surface magnetization was especially larger for the case of nitride-carburizing. As a result, the wear particles always stay in the interfaces and the wear mechanism becomes complex. Therefore, it is necessary to put nitride after carburizing for the composite heat treatments.

  7. Effects of Ceric Oxide Coatings on Materials Performance of 430 Steel in Coal Synthetc Gas

    Energy Technology Data Exchange (ETDEWEB)

    Ziomek-Moroz, M. Jablonski, P

    2011-12-21

    The surfaces of low silicon and aluminum 430 stainless steel (UNS 43000) coupons with and without ceria (CeO2) surface treatment were investigated after exposure to simulated coal syngas based fuel at 800 C. The results indicate a different mechanism of carburization for the ceria treated steel than that for the untreated steel.

  8. High temperature corrosion investigation in an oxyfuel combustion test rig

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Bjurman, M.; Hjörnhede, A;

    2014-01-01

    (perhaps carburized) zone was used as a measure of corrosion rates. The lowest alloyed steel had the highest corrosion rate, and the other austenitic and nickel alloys had much lower corrosion rates. Precipitates in the alloy adjacent the corrosion front were revealed for both Sanicro 28 and C‐276. However...

  9. Le prix du transport : quels impacts sur le comportement des utilisateurs ?

    OpenAIRE

    MADRE,JL

    2004-01-01

    Cet article évoque les problèmes soulevés par l'augmentation du prix du carburant et des transports en commun. Quel est l'impact de ces évolutions sur le budget et les comportements des usagers ? Et comment les maitriser ?

  10. Methods for microwave heat treatment of manufactured components

    Science.gov (United States)

    Ripley, Edward B.

    2010-08-03

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases. The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  11. Microwave heat treating of manufactured components

    Science.gov (United States)

    Ripley, Edward B.

    2007-01-09

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases. The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  12. 淬火

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Phase Formation and Microstructure of Titanium Oxides and Composites Produced by Thermal Plasma Oxidation of Titanium Carbide.Strocture and properties of the hardened carburized layer of low-carbon chromium-nickel steel after quenching in diffcrent media-Part Ⅰ.Experimental setup for thermal fatigue testing of steels for the casting tools.

  13. Lattice expansion of carbon-stabilized expanded austenite

    DEFF Research Database (Denmark)

    Hummelshøj, Thomas Strabo; Christiansen, Thomas; Somers, Marcel A. J.

    2010-01-01

    The lattice parameter of expanded austenite was determined as a function of the content of interstitially dissolved carbon in homogeneous, carburized thin stainless steel foils. For the first time this expansion of the face-centered cubic lattice is determined on unstrained austenite. It is found...

  14. Apparatus with moderating material for microwave heat treatment of manufactured components

    Energy Technology Data Exchange (ETDEWEB)

    Ripley, Edward B. (Knoxville, TN)

    2011-05-10

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  15. Simulation of Case Depth of Cementation Steels According to Fick's Laws%Simulation of Case Depth of Cementation Steels According to Fick's Laws

    Institute of Scientific and Technical Information of China (English)

    S R Elmi Hosseini

    2012-01-01

    The carburizing process is the enrichment of the depth of low carbon steels with carbon. It leads to samples with a combination of high surface hardness and high core toughness and to an impact strength that is required for many engineering parts. The material studied is a low carbon steel. The carbon content is little in this type of steel (wc = 0.2 ~). The calculation of case depth is very important for cementation steels that are hardened in the carburi- zing process. The effective case depth is defined as the perpendicular distance from the surface to a place at which the hardness is HV 550. Nowadays, a great number of studies have been carried out on the simulation of effective case depth, but no studies have been conducted to determine the numerical relation between the total case depth on one hand and the carburizing time and the effective case depth on the other hand. The steel specimens were subjected to graphite powder. Then, they were heat treated at 925 ~C for about 3, 5, 8 and 12 h, respectively. Then, these parts were quenched in oil. To determine the effective case depth, the micr0hardness test was performed on the cross-section of specimens. Plotting the case depth vs carburizing time, the required conditions for obtaining the specified case depth were determined. Also, the comparison between the case depths in numerical solution and the actual position in pack carburizing was performed.

  16. Stress and Composition of Carbon Stabilized Expanded Austenite on Stainless Steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2009-01-01

    Low-temperature gaseous carburizing of stainless steel is associated with a colossal supersaturation of the fcc lattice with carbon, without the development of carbides. This article addresses the simultaneous determination of stress and composition profiles in layers of carbon xpanded austenite...

  17. Hydrogen-oxygen powered internal combustion engine

    Science.gov (United States)

    Cameron, H.; Morgan, N.

    1970-01-01

    Hydrogen at 300 psi and oxygen at 800 psi are injected sequentially into the combustion chamber to form hydrogen-rich mixture. This mode of injection eliminates difficulties of preignition, detonation, etc., encountered with carburated, spark-ignited, hydrogen-air mixtures. Ignition at startup is by means of a palladium catalyst.

  18. Surface hardening of austenitic stainless steels via low-temperature colossal supersaturation

    Science.gov (United States)

    Cao, Yan

    The Swagelok Company has recently developed a low-temperature (470°C) carburization technology for austenitic stainless steels, that increases the surface hardness from 200 to 1200 HV25 without sacrificing corrosion resistance. In order to investigate the microstructural changes responsible for these outstanding properties, bulk specimens, thin foils, and powder specimens of several different low-temperature carburized 316 stainless steels have been studied. XRD studies revealed that the low-temperature carburization of 316 austenitic stainless steels lead to a colossal supersaturation of interstitial carbon in the austenite. While the equilibrium solubility of carbon is 0.03 at% at the carburization temperature of 470°C, high-precision XRD determination of the lattice parameter after carburization indicated a carbon concentration of >10at% in solid solution---a colossal supersaturation! This astonishing result was confirmed by a completely independent experimental method, X-ray photoelectron spectrometry (XPS). Residual stress measurements indicated that low-temperature carburization caused an enormous compressive residual stress of 2 GPa at the surface. The enormous compressive residual stress and a high density of stacking faults caused broadening and shifting of the austenite peaks in X-ray diffraction scans. Analysis of the underlying thermodynamics and kinetics indicate that the key to colossal supersaturation is to kinetically suppress the formation of M23C6. The colossal supersaturation of carbon in the austenite is the dominant feature responsible for the unusual hardness. Only during the extended (>40h) carburization times, M5C 2 carbide (Hagg carbide), instead of M23C6, was observed to form. In addition, TEM studies indicated the presence of a small amount of a second carbide phase, M7C3. The particles of both carbides have the shape of long needles, containing a high density of planar defects normal to the long axis of the needles. The concept of "low

  19. Properties of 15HN Steel after Various Thermo-Chemical Treatments

    Directory of Open Access Journals (Sweden)

    L. Klimek

    2007-07-01

    Full Text Available The aim of conducted research was to find universal steel that may serve to regenerate machine elements by MULTIPLEX method – or cladding of alloy steel and then subjecting to thermo-chemical treatment. This paper presents the results of metallographic examination, hardness distribution and selected tribological properties of vacuum carburized, sulphonitrided and vacuum nitrided layers obtained on 15HN steel. The results demonstrate that on 15HN steel (carburizing steel, nitrided and sulphonitrided layers show good durability and tribological properties. Therefore, it is possible to use it to regenerate machine elements by cladding method and then treat them by different thermo-chemical ways in order to obtain desired properties.

  20. Evaluation of Microstructure and Wear Properties of Ti-6Al-4V Alloy Plasma Carbonized at Different Temperatures

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong; WEI Qiulan; XING Yazhe; JIANG Chaoping; LI Xinghang; ZHAO Zhiyu

    2015-01-01

    Ti-6Al-4V (TC4) alloys were plasma carbonized at different temperatures (900, 950, and 1 000ć) for duration of 3 h. Graphite rod was employed as carbon supplier to avoid the hydrogen brittleness which is ubiquitous in traditional gas carbonizing process. Two distinguished structures including a thin compound layer (carbides layer) and a thick layer with the mixed microstructure of TiC and theα-Ti in carburing layer were formed during carburizing. Furthermore, it was found that the microstructure and the properties of TC4 alloy were signifi cantly related to the carbonizing temperature. The specimen plasma carbonized at 950ć obtained maximum value both in the hardness and wear resistance.

  1. Influence of different thermal treatment in sintered steels base molybdenum

    International Nuclear Information System (INIS)

    Prealloyed steel powders with different amount of Mo-Cu-Ni-C were compacted at 700 MPa and sintered at 1120 degree centigrade in 95% N2 -5% H2. After sinterizing, these materials were treated by carburizing. For materials characterization radial crushing strength were preformed, density was calculated and a complete study of fracture surfaces was carried out using scanning electron microscopy. The results of radial crushing strength show that resistance after carburizing is higher than in sintered materials. The fracture surfaces give an idea of materials briteless and the treatment depth. In sintered materials, a ductil surface was observed, with the characteristic dimples. The fracture surfaces after different treatments show brittleness in the outer zone, while appears a mix of ductil and briteless fracture. (Author) 7 refs

  2. Physical mechanisms of thermal-diffusivity depth-profile generation in a hardened low-alloy Mn, Si, Cr, Mo steel reconstructed by photothermal radiometry

    International Nuclear Information System (INIS)

    It is well established that in hardened steels thermal-diffusivity broadly anticorrelates with microhardness, allowing thermal-wave depth profilometry to be used as a tool to measure microhardness profiles. Nevertheless, the physical mechanisms for this anticorrelation have not been well understood. In this work, the thermal-diffusivity profiles of rough, hardened industrial steels were reconstructed after the elimination of roughness effects from the experimental data. Carburizing and quenching are widely used for the heat treatment of steel components, and it is important to understand their effects on thermal-diffusivity profiles. A thorough examination of the actual mechanism by which thermal-diffusivity depth profiles are affected by first carburizing and then quenching AISI-8620 steels was performed. It was concluded that the variation of thermal diffusivity with depth is dominated by the carbon concentration profile, whereas the absolute value of the thermal diffusivity is a function of microstructure. [copyright] 2001 American Institute of Physics

  3. Influence of different thermal treatment in sintered steels base molybdenum; Influencia de diferentes tratamientos termoquimicos en aceros sinterizados base molibdeno

    Energy Technology Data Exchange (ETDEWEB)

    Candela, N.; Plaza, R.; Ruiz-Amador, D.; Velasco, F.; Torralba, J. M.

    2001-07-01

    Prealloyed steel powders with different amount of Mo-Cu-Ni-C were compacted at 700 MPa and sintered at 1120 degree centigree in 95% N{sub 2} -5% H{sub 2}. After sinterizing, these materials were treated by carburizing. For materials characterization radial crushing strength were preformed, density was calculated and a complete study of fracture surfaces was carried out using scanning electron microscopy. The results of radial crushing strength show that resistance after carburizing is higher than in sintered materials. The fracture surfaces give an idea of materials briteless and the treatment depth. In sintered materials, a ductil surface was observed, with the characteristic dimples. The fracture surfaces after different treatments show brittleness in the outer zone, while appears a mix of ductil and briteless fracture. (Author) 7 refs.

  4. Randschichthärtung von rostfreiem stahl durch Gasnitrierung und Gascarburierung bei niedringen Temperaturen

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A.J.

    2005-01-01

    In the present contribution an overview is given of new scientific and technological achievements on gaseous nitriding and carburizing of austenitic stainless steel at low temperature, i.e. below appr. 723 K for gaseous nitriding and below appr. 823 K for gaseous carburizing. These thermochemical...... treatments are enabled by a newly patented pretreatment, which replaces the passive chromium oxide layer by a very thin catalytic nickel layer. In the subsequent thermochemical treatment carbon and/or nitrogen containing species from the gas mixture dissociate at the Ni-surface. Simultaneously nitrogen...... and carbon atoms are incorporated in the substrate under the development of expanded austenite. Crystallographic data, absorption isotherms, diffusion coefficients and the thermal stability were investigated for homogeneous foils of expanded austenite with different nitrogen contents. Hardness and residual...

  5. XPS, XRD and laser raman analysis of surface modified of 6150 steel substrates for the deposition of thick and adherent diamond-like carbon coatings

    Directory of Open Access Journals (Sweden)

    William de Melo Silva

    2013-06-01

    Full Text Available Although the 6150 steel has an excellent fatigue and impact resistance, it is unsuitable to operate it when the corrosion is a limited factor. We propose here a sequence of steel pre-treatment by carburizing, carbonitriding and nitriding in order to improve the poor adhesion between Diamond Like-Carbon coatings on steel. This sequence is our attempt to reduce the difference between the coefficients of thermal expansion of steel and DLC through the graded interface. This work demonstrates the quantitative analysis of the molecules present at surface using X-ray photoelectron spectroscopy. The crystallographic structures are investigated by X-ray diffraction which shows the formation of carbides and nitride phases. Raman spectroscopy reveals the carburizing surface characteristics where DLC coating is nucleated and grown at the substrate. At the end of the analysis it is possible to verify which molecules and phases are formed on the steel surface interface after each step of pre-treatment.

  6. Out-of-pile chemical compatibility of hyperstoichiometric (Pu0.7U0.3)C with stainless steel cladding and sodium coolant

    International Nuclear Information System (INIS)

    Chemical compatibility experiments of the hitherto unknown fuel (Pu0.7U0.3)C1+x with sodium coolant and SS 316 (20% cold-worked) cladding were carried out at 973 K for 1000 h for its out-of-pile 'proof testing'. Any possible chemical interaction was assessed by metallographic examination and microhardness measurements of SS 316 cladding specimens. Hyperstoichiometric (Pu0.7U0.3)C containing upto 0.7% oxygen and 20% mixed sesquicarbide (M2C3) did not interact at all with sodium and caused insignificant carburization of the SS 316 cladding. Mixed carbide pellets containing high 'O' (≅ 1%) and high M2C3 (≅ 60%) caused clad carburization to a depth of around 90 μm. These experiments generated valuable informations in support of choosing plutonium rich mixed carbide as the driver fuel for the fast breeder test reactor (FBTR). (orig.)

  7. Optimization of Heat Treatment Process for Internal Clutch by Using Taguchi Technique

    Directory of Open Access Journals (Sweden)

    Prof. S. R. Thakare,

    2014-01-01

    Full Text Available Surface engineering and surface engineered materials find wide applications in engineering industries in recent years. Inconsistency in hardness and case depth has resulted in the further optimization of the process variables involved in surface hardening. In the present study, the following operating parameters viz. Carbon potential, holding position, furnace temperature, carburizing time, quenching medium, quenching temperature, quenching time, tempering temperature and tempering time were taken for optimization using the Taguchi and Factorial design of experiment concepts. From the experiments and optimization analysis conducted on EN8 materials it was observed that furnace temperature and quenching time had equal influence in obtaining a better surface integrity of the case hardened components using gas carburizing. In the case of induction hardening process, power potential played a vital role in optimizing the surface hardness and the depth of hardness.

  8. XPS, XRD and laser Raman analysis of surface modified of 6150 steel substrates for the deposition of thick and adherent diamond-like carbon coatings

    Energy Technology Data Exchange (ETDEWEB)

    Silva, William de Melo; Carneiro, Jose Rubens Goncalves, E-mail: williammelosilva@gmail.com [Pontificia Universidade Catolica de Minas Gerais (PUC-MG), Belo Horizonte (Brazil). Dept. de Engenharia Mecanica; Trava-Airoldi, Vladimir Jesus [Associate Laboratory of Sensors and Materials, National Institute for Space Research, Sao Jose dos Campos, SP (Brazil)

    2013-11-01

    Although the 6150 steel has an excellent fatigue and impact resistance, it is unsuitable to operate it when the corrosion is a limited factor. We propose here a sequence of steel pre-treatment by carburizing, carbonitriding and nitriding in order to improve the poor adhesion between Diamond Like-Carbon coatings on steel. This sequence is our attempt to reduce the difference between the coefficients of thermal expansion of steel and DLC through the graded interface. This work demonstrates the quantitative analysis of the molecules present at surface using X-ray photoelectron spectroscopy. The crystallographic structures are investigated by X-ray diffraction which shows the formation of carbides and nitride phases. Raman spectroscopy reveals the carburizing surface characteristics where DLC coating is nucleated and grown at the substrate. At the end of the analysis it is possible to verify which molecules and phases are formed on the steel surface interface after each step of pre-treatment. (author)

  9. Advanced gas-cooled nuclear reactor materials evaluation and development program: corrosion behavior of experimental alloys in controlled-purity helium at temperatures in the 750 to 10500C range

    International Nuclear Information System (INIS)

    A series of 10 experimental alloys (basically Ni-20Cr with addition of one or more of the elements Al, Ti, Si, Nb and Y) has been examined after exposure to controlled purity helium for periods of 1000 to 6000 hours at temperatures of 750 to 10500C. Alloys containing aluminum were particularly susceptible to internal oxidation at the lower temperatures, but at 9500C and above carburization became the dominant corrosive mechanism. The most corrosive resistant alloys were Ni-Cr20 and Ni-Cr containing Si, Ti and Nb. The presence of small amounts of yttrium dramatically promoted the occurrence of carburization, even at temperatures as low as 8500C. 69 figures, 7 tables

  10. TPR and TPD studies of effects of Cu and Ca promotion on Fe-Zn-based Fischer-Tropsch catalysts

    Indian Academy of Sciences (India)

    Olusola O James; Biswajit Chowdhury; Sudip Maity

    2013-05-01

    Temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) were used to study the effects of Cu and Ca promotion on Fe-Zn-based Fischer-Tropsch catalysts. The reduction temperature for Fe2O3 → Fe3O4 was unaffected by Ca addition but decreased when promoted with Cu. Fe-Zn promoted with Cu and Ca showed even much lower reduction temperature for Fe2O3→Fe3O4. Ca promotion enhances carburization and increases surface acidity and basicity of the Fe-Zn oxide precursor. While Cu inhibits carburization and decreases the surface acidity and basicity of the Fe-Zn oxide precursor. The implications of these effects on the application of catalysts for FT are discussed.

  11. Synthesis of titanium carbide by induction plasma reactive spray

    Institute of Scientific and Technical Information of China (English)

    JIANG Xian-Liang(蒋显亮); M.Boulos

    2004-01-01

    A novel method capable of sufficient mixing of titanium powder and methane of carbon source was developed in the synthesis of titanium carbide by induction plasma reactive spray. X-ray diffraction analysis, optical microscopy, scanning electron microscopy, and microhardness test were used to characterize the spray-formed deposit.The experimental results show that both primary carburization of the titanium particles inside the plasma flame and secondary carburization of the growing deposit on high temperature substrate contribute to the forming of titanium carbide. The transitional phase of TiC1-x has the same crystal structure as TiC, but has a slightly low lattice constant. The deposit consists of fine grain structure and large grain structure. The fine grain structure, harder than large grain structure, shows grain boundary fracture.

  12. Extended x-ray absorption fine structure investigation of annealed carbon expanded austenite

    DEFF Research Database (Denmark)

    Oddershede, Jette; Christiansen, Thomas L.; Somers, Marcel A. J.;

    2012-01-01

    Carbon expanded austenite synthesized through carburizing of austenitic stainless steel powder at 380°C was annealed at 470°C and investigated with extended X-ray absorption fine structure (EXAFS) and synchrotron powder diffraction (SPD). SPD showed that the samples consisted of carbon expanded......-carburized in a temperature regime around 470°C. The surface zone is converted into carbon expanded austenite; the high interstitial content of carbon dissolved in the surface results in highly favorable materials properties. In the present article the local atomic environment of (annealed) carbon expanded austenite...... was investigated with EXAFS. Copyright © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim....

  13. Effect of flowing sodium on corrosion and tensile properties of AISI type 316LN stainless steel at 823 K

    International Nuclear Information System (INIS)

    AISI type 316LN stainless steel was exposed to flowing sodium in mass transfer loop (MTL) at 823 K for 16 000 h and then examined for changes in the tensile properties due to the mass transfer and corrosion effects. Comparisons in microstructural and mechanical properties were made between annealed, thermally aged and sodium exposed materials. Microstructural examination of thermally aged and sodium exposed materials revealed precipitation of carbides at the grain boundaries. The sodium exposed samples contained a degraded layer at the surface up to a depth of around 10 μm and a surface carburized layer of about 30 μm. There was about 15% increase in yield strength and a decrease of about 20% in ductility for the sodium exposed material vis-a-vis thermally aged material and this was attributed to carburization effects and microstructural changes

  14. On the Carbon Solubility in Expanded Austenite and Formation of Hägg Carbide in AISI 316 Stainless Steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas L.; Ståhl, Kenny; Brink, Bastian K.;

    2016-01-01

    –420 °C and 465–470 °C, respectively. Hägg carbide (x-M5C2)develops when the carbon content in the expanded austenite exceeds the metastable solubility limit; the transformation of carbon expanded austenite into Hägg carbide occurs irrespective of carburizing temperature in the investigated temperature...... range (380–470 °C). The maximum solubility of carbon in expanded austenite (380 °C) is found to correspond to an occupancy (yC) of 0.220 of the interstitial octahedral sites of the austenite lattice (i.e., 4.74wt%C). Decomposition of Hägg carbide into M7C3 occurs upon prolonged carburizing treatment...

  15. Polymers' surface interactions with molten iron: A theoretical study

    Science.gov (United States)

    Assadi, M. Hussein N.; Sahajwalla, Veena

    2014-10-01

    Environmental concerns are the chief drive for more innovative recycling techniques for end-of-life polymeric products. One attractive option is taking advantage of C and H content of polymeric waste in steelmaking industry. In this work, we examined the interaction of two high production polymers i.e. polyurethane and polysulfide with molten iron using ab initio molecular dynamics simulation. We demonstrate that both polymers can be used as carburizers for molten iron. Additionally, we found that light weight H2 and CHx molecules were released as by-products of the polymer-molten iron interaction. The outcomes of this study will have applications in the carburization of molten iron during ladle metallurgy and waste plastic injection in electric arc furnace.

  16. Low leaded motor gasoline of high knock rating having few pollution effects

    Energy Technology Data Exchange (ETDEWEB)

    Droste, W.; Obenaus, F.; Schoefer, W.

    1975-11-13

    A carburator gasoline has been developed that has a high knock rating and few enviromental pollution effects. The gasoline contains 0.1 to 0.4 g of lead per liter, and up to 20 percent by volume of a mixture made up of 80 to 90 percent by weight methyl-tert.-butyl ether and 20 to 10 percent by weight methanol. Through tests it has been determined that the characteristics (particularly the octane number) of a gasoline having a lead content of 0.15 g/liter and one of the above mentioned additives are better than those of a gasoline with a lead content of 0.4 g/liter, but not containing an additive. The harmful emissions were also lower. In addition, the danger of carburator icing is decreased.

  17. Carbon transport in a bimetallic sodium loop simulating the intermediate heat transport system of a liquid metal fast breeder reactor

    International Nuclear Information System (INIS)

    Carbon transport data from a bimetallic sodium loop simulating the intermediate heat transport system of a Liquid Metal Fast Breeder Reactor are discussed. The results of bulk carbon analyses after 15,000 hours' exposure indicate a pattern of carburization of Type 304 stainless steel foils which is independent of loop sodium temperature. A model based on carbon activity gradients accounting for this behavior is proposed. Data also indicate that carburization of Type 304 stainless steel is a diffusion-controlled process; however, decarburization of the ferritic 2 1/4 Cr-1Mo steel is not. It is proposed that the decarburization of the ferritic steel is controlled by the dissolution of carbides in the steel matrix. The differences in the sodium decarburization behavior of electroslag remelted and vacuum-arc remelted 2 1/4 Cr-1Mo steel are also highlighted

  18. Synthesis and characterization of binder-free Cr{sub 3}C{sub 2} coatings on nickel-based alloys for molten fluoride salt corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Brupbacher, Michael C.; Zhang, Dajie [Department of Materials Science and Engineering, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Buchta, William M. [The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Graybeal, Mark L. [U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Rhim, Yo-Rhin [The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Nagle, Dennis C. [Department of Materials Science and Engineering, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Spicer, James B., E-mail: spicer@jhu.edu [Department of Materials Science and Engineering, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)

    2015-06-15

    Under various conditions, chromium carbides appear to be relatively stable in the presence of molten fluoride salts and this suggests that their use in corrosion resistant coatings for fluoride salt environments could be beneficial. One method for producing these coatings is the carburization of sprayed Cr coatings using methane-containing gaseous precursors. This process has been investigated for the synthesis of binder-free chromium carbide coatings on nickel-based alloy substrates for molten fluoride salt corrosion resistance. The effects of the carburization process on coating microstructure have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS). Both plasma-sprayed and cold-sprayed Cr coatings have been successfully converted to Cr{sub 3}C{sub 2}, with the mechanism of conversion being strongly influenced by the initial porosity in the as-deposited coatings.

  19. Development of Barrier Layers for the Protection of Candidate Alloys in the VHTR

    Energy Technology Data Exchange (ETDEWEB)

    Levi, Carlos G. [Battelle Energy Alliance, LLC, Idaho Falls, ID (United States); Jones, J. Wayne [Battelle Energy Alliance, LLC, Idaho Falls, ID (United States); Pollock, Tresa M. [Battelle Energy Alliance, LLC, Idaho Falls, ID (United States); Was, Gary S. [Battelle Energy Alliance, LLC, Idaho Falls, ID (United States)

    2015-01-22

    The objective of this project was to develop concepts for barrier layers that enable leading candi- date Ni alloys to meet the longer term operating temperature and durability requirements of the VHTR. The concepts were based on alpha alumina as a primary surface barrier, underlay by one or more chemically distinct alloy layers that would promote and sustain the formation of the pro- tective scale. The surface layers must possess stable microstructures that provide resistance to oxidation, de-carburization and/or carburization, as well as durability against relevant forms of thermo-mechanical cycling. The system must also have a self-healing ability to allow endurance for long exposure times at temperatures up to 1000°C.

  20. Effect of incorporation manner of Zr promoter on precipitated ironbased catalysts for Fischer-Tropsch synthesis

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hao-jian; MA Hong-fang; ZHANG Hai-tao; YING Wei-yong; FANG Ding-ye

    2012-01-01

    The promotional effects of Zr on the structure,reduction,carburization and catalytic behavior of precipitated iron-based Fischer-Tropsch synthesis (FTS) catalysts were investigated.The catalysts were characterized by N2 physisorption,temperature-programmed reduction (TPR),and M(o)ssbauer effect spectroscopy (MES) techniques.As revealed by N2 physisorption,Zr decreased the BET surface area and pore volume of the catalyst.The results of TPR and MES show that Zr suppresses the reduction and carburization of Fe catalysts because of the interaction between Fe and Zr.The FTS reaction results indicate that Zr decreases the FTS activity of Fe catalysts but improves the catalysts' stability.In addition,Zr promoter restraines the formation of light hydrocarbons (methane and C2~C4) and shifts the production distribution to the heavy hydrocarbons.

  1. Active carbon supported molybdenum carbides for higher alcohols synthesis from syngas

    DEFF Research Database (Denmark)

    Wu, Qiongxiao; Chiarello, Gian Luca; Christensen, Jakob Munkholt;

    This work provides an investigation of the high pressure CO hydrogenation to higher alcohols on K2CO3 promoted active carbon supported molybdenum carbide. Both activity and selectivity to alcohols over supported molybdenum carbides increased significantly compared to bulk carbides in literatures....... spectroscopy were applied for determining the carburization temperature and evaluating the composition of the carbide clusters of different samples through determinations of the Mo-C and Mo-Mo coordination numbers....

  2. XPS, XRD and laser raman analysis of surface modified of 6150 steel substrates for the deposition of thick and adherent diamond-like carbon coatings

    OpenAIRE

    William de Melo Silva; José Rubens Gonçalves Carneiro; Vladimir Jesus Trava-Airoldi

    2013-01-01

    Although the 6150 steel has an excellent fatigue and impact resistance, it is unsuitable to operate it when the corrosion is a limited factor. We propose here a sequence of steel pre-treatment by carburizing, carbonitriding and nitriding in order to improve the poor adhesion between Diamond Like-Carbon coatings on steel. This sequence is our attempt to reduce the difference between the coefficients of thermal expansion of steel and DLC through the graded interface. This work demonstrates the ...

  3. Growth of bridging carbon nanofibers in cracks formed by heat-treating iron oxide thin sheets in acetylene gas

    OpenAIRE

    Takeshi Hikata; Soichiro Okubo; Yugo Higashi; Teruaki Matsuba; Risa Utsunomiya; Sadahiro Tsurekawa; Katsuhisa Murakami; Jun-ichi Fujita

    2013-01-01

    We produced novel carbon nanofibers (CNFs) by oxidizing high-purity iron foil and then carburizing it in acetylene gas flow. This formed cracks in the heat-treated iron foil with CNFs bridging the two walls of each crack. The CNFs were drawn out from the walls as the crack opened during heat treatment. This will be a new method to grow and arrange carbon nanotubes and nanosheets without using metal nanoparticles or template substrates.

  4. Growth of bridging carbon nanofibers in cracks formed by heat-treating iron oxide thin sheets in acetylene gas

    Directory of Open Access Journals (Sweden)

    Takeshi Hikata

    2013-04-01

    Full Text Available We produced novel carbon nanofibers (CNFs by oxidizing high-purity iron foil and then carburizing it in acetylene gas flow. This formed cracks in the heat-treated iron foil with CNFs bridging the two walls of each crack. The CNFs were drawn out from the walls as the crack opened during heat treatment. This will be a new method to grow and arrange carbon nanotubes and nanosheets without using metal nanoparticles or template substrates.

  5. Nitrocarburising in ammonia-hydrocarbon gas mixtures

    DEFF Research Database (Denmark)

    Pedersen, Hanne; Christiansen, Thomas; Somers, Marcel A. J.

    2010-01-01

    The present work investigates the possibility of nitrocarburising in ammonia-acetylene-hydrogen and ammoniapropene- hydrogen gas mixtures, where unsaturated hydrocarbon gas is the carbon source during nitrocarburising. Consequently, nitrocarburising is carried out in a reducing atmosphere...... and straightforward control of the carburizing and nitriding potentials is in principle possible. The nitrocarburising response of unalloyed (ARMCO) Fe was investigated in a thermobalance during controlled nitrocarburising at 580°C. The “cases” obtained on nitrocarburised iron were characterized by reflected light...

  6. A contribution to the study of the mixed uranium-plutonium mono-carbides containing small quantities of zirconium; Contribution a l'etude du monocarbure d'uranium et de plutonium avec de faibles additions de zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Bocker, S. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1970-03-01

    We have studied a mixed monocarbide, type (U,Pu)C, containing small additions of zirconium for the application as a fast neutron reactor fuel. A preliminary study was conducted on the (U,Zr)C monocarbide (Report CEA-R-3765(1). It was found that small additions of zirconium to the uranium-plutonium monocarbide improve a number of properties such as atmospheric corrosion, the hardness, and particularly the compatibility with 316 stainless steel. However, properties such as the coefficient of expansion and the melting point are only slightly changed. The relative percentage of Pu/U+Pu in the monocarbide was fixed at 20 per cent. Two processes of fabrication were employed: casting in an arc furnace, sintering, carried out after having the hydrides of the metals carburized. The metallurgical results indicate, that the above mentioned fuel might be of interest for fast neutron reactor application. (author) [French] On a etudie un combustible de type carbure (U,Pu)C pour les reacteurs a neutrons rapides. Les recherches preliminaires ont porte sur le carbure (UZr)C (rapport CEA-R-3765(1)). L'addition de faibles quantites de zirconium (3 at. pour cent) au monocarbure (U,Pu)C, ameliore certaines proprietes, commee la tenue a la corrosion atmospherique, la durete et surtout la compatibilite avec l'acier inoxydable X-18 M, Par contre le coefficient de dilatation et la densite sont peu changes. Le rapport Pu/Pu+U etait fixe a 20 pour cent. Deux procedes de fabrication ont ete etudies: l'un par fusion a l'arc, l'autre par frittage a partir de metaux hydrures. Au vu des resultats metallurgiques obtenus le carbure (U,Pu,Zr)C semble presenter un interet certain. (auteur)

  7. WC as a non-platinum hydrogen evolution electrocatalyst for high temperature PEM water electrolysers

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey; Petrushina, Irina; Christensen, Erik;

    2012-01-01

    Tungsten carbide (WC) nanopowder was tested as a non-platinum cathode electrocatalyst for polymer electrolyte membrane (PEM) water electrolysers, operating at elevated temperatures. It was prepared in thermal plasma reactor with confined plasma jet from WO3 precursor in combination with CH4...... carburizing agent. The results of the investigation showed that the activity of tungsten carbide as cathode electrocatalyst increases significantly with temperature and this effect is more pronounced than for platinum, especially, at 150 °C....

  8. 油润滑

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Modeling of the inlet zone in the mixed lubrication situation of cold strip rolling;Fatigue Behavior of ltybrid Ceramic Ball Bearings in Liquid Nitrogen;EHL film thickness limitation theory under a limiting shear stress;Effects of Surlace Roughness on Behaviors of Lubricant Molecules in Ultra-Thin Fihn Lubrication;Effect of slip condition on the contact fatigue strength for pitting of the carburized steel。

  9. Carbon Coating Of Copper By Arc-Discharge Pyrolysis

    Science.gov (United States)

    Ebihara, Ben T.; Jopek, Stanley

    1988-01-01

    Adherent, abrasion-resistant coat deposited with existing equipment. Carbon formed and deposited as coating on copper substrate by pyrolysis of hydrocarbon oil in electrical-arc discharges. Technique for producing carbon deposits on copper accomplished with electrical-discharge-machining equipment used for cutting metals. Applications for new coating technique include the following: solar-energy-collecting devices, coating of metals other than copper with carbon, and carburization of metal surfaces.

  10. Crystal-phase control of molybdenum carbide nanobelts for dehydrogenation of benzyl alcohol.

    Science.gov (United States)

    Li, Zhongcheng; Chen, Chunhui; Zhan, Ensheng; Ta, Na; Li, Yong; Shen, Wenjie

    2014-05-01

    Belt-shaped molybdenum carbides in α- and β-phases were synthesized by reducing and carburizing a nano-sized α-MoO3 precursor with hydrocarbon-hydrogen mixtures at appropriate temperatures; the β-Mo2C nanobelts with a higher fraction of coordinatively unsaturated Mo sites were more active than the α-MoC1-x nanobelts in dehydrogenation of benzyl alcohol to benzaldehyde.

  11. QUALITY CONTROL ON THE AUSTENITIC-BAINITIC DUCTILE IRON GEAR

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    By reasonable casting, spheroidizing , inoculating and heat treating processes to control cupola metallurgy and the lipuid iron chemical compositions, a new kind of austenitic-bainitic ductile iron which can substitute for 20CrMnTi carburizing steel is studied. The gears made by the cast iron are high in quality,low in weight and the production cost is greatly reduced. The mechanical properties of the gear, including wear resistance, fatigue resistance, durability and others, can be greatly improved.

  12. Matériaux photocatalytiques structurés à base de mousses alvéolaires de β-SiC : applications au traitement de l'air

    OpenAIRE

    Masson, Romain

    2012-01-01

    The main objective of this work was to study the potential of three-dimension beta silicon carbide (β-SiC) alveolar foams for use as photocatalyst support, targeting the implementation of structured photocatalytic reactors for air treatment. Medium surface area β-SiC alveolar foams were synthesized according to the Shape Memory Synthesis concept, consisting in the controlled carburization of a preshaped polyurethane foam. First, the degradation of three model pollutants (methylethylketone, am...

  13. La présentation des réglementations de IGH (immeuble de grande hauteur, Skyskrapers, High Rise Building) fran aises

    Institute of Scientific and Technical Information of China (English)

    Wajdi Laroussi; XING Wei

    2014-01-01

    Résumé: Présenter les réglementations IGH fran aises portant sur les exigences et la notion d’évacuation complète, le niveau d’anti-incendie pour les c bles, la réserve du carburant des génératrices, l’application du système informatique etc. Comparer-les avec celles de l’Allemagne et des Etats-unis.

  14. Influence Of Heat Treatment On Duplex Stainless Steel To Study The Material Properties

    OpenAIRE

    Jithin M; Anees Abdul Hameed; Ben Jose; Anush Jacob

    2015-01-01

    Abstract The various heat treatment processes are annealing normalizing hardening tempering spheroidising surface hardening flame and induction hardening nitriding cyaniding carbonitriding carburizing etc Heat treatment on duplex stainless steel is to improve ductility toughness strength hardness and to relieve internal stress developed in the material. Here basically the experiment of hardness test impact test wear test and compression is done to get idea about heat treated duplex stainless ...

  15. Inhibition of coking and metal dusting on conventional alloys by using a nickel-tin intermetallic coating

    OpenAIRE

    Geers, Christine

    2013-01-01

    Coking and Metal Dusting are high temperature corrosion phenomena occurring at 400 to 900°C under highly reducing conditions with low oxygen partial pressures and high carbon activities. Coking is the catalytical deposition of carbon on steels or nickel base alloys. Metal Dusting is a rapid material loss due to massive carburization and graphite precipitation within the metal matrix, causing the loss of integrity. Both phenomena have been investigated for the last fifty years. Metals suscepti...

  16. Extended X-Ray Absorption Fine Structure Investigation of Carbon Stabilized Expanded Austenite and Carbides in Stainless Steel AISI 316

    DEFF Research Database (Denmark)

    Oddershede, Jette; Christiansen, Thomas; Ståhl, Kenny;

    2011-01-01

    Low temperature carburized AISI 316 stainless steel - carbon expanded austenite - was investigated with EXAFS and synchrotron diffraction together with synthesized carbides of the type M3C2, M7C3 and M23C6. It was found that the chemical environment of carbon expanded austenite is not associated...... with any of the investigated carbides, that carbon has a strong affinity for chromium, i.e. short range order, and that carbon is in solid solution....

  17. Bearing fatigue investigation 3

    Science.gov (United States)

    Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

    1982-01-01

    The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

  18. The Study of Heat Treatment Effects on Chromium Carbide Precipitation of 35Cr-45Ni-Nb Alloy for Repairing Furnace Tubes

    Directory of Open Access Journals (Sweden)

    Nakarin Srisuwan

    2016-01-01

    Full Text Available This paper presents a specific kind of failure in ethylene pyrolysis furnace tubes. It considers the case in which the tubes made of 35Cr-45Ni-Nb high temperature alloy failed to carburization, causing creep damage. The investigation found that used tubes became difficult to weld repair due to internal carburized layers of the tube. The microstructure and geochemical component of crystallized carbide at grain boundary of tube specimens were characterized by X-ray diffractometer (XRD, scanning electron microscopy (SEM with back-scattered electrons mode (BSE, and energy dispersive X-ray spectroscopy (EDS. Micro-hardness tests was performed to determine the hardness of the matrix and the compounds of new and used tube material. The testing result indicated that used tubes exhibited a higher hardness and higher degree of carburization compared to those of new tubes. The microstructure of used tubes also revealed coarse chromium carbide precipitation and a continuous carbide lattice at austenite grain boundaries. However, thermal heat treatment applied for developing tube weld repair could result in dissolving or breaking up chromium carbide with a decrease in hardness value. This procedure is recommended to improve the weldability of the 35Cr-45Ni-Nb used tubes alloy.

  19. A Novel Method for Direct Synthesis of WC-Co Nanocomposite Powder

    Science.gov (United States)

    Zhu, M.; Bao, X. Y.; Yang, X. P.; Gu, N. S.; Wang, H.; Zeng, M. Q.; Dai, L. Y.

    2011-09-01

    In this study, a novel method, termed dielectric-barrier-discharge-plasma (DBDP) assisted ball milling and low-temperature carburization, was used to synthesize WC-Co nanocomposite powder. X-ray diffraction, scanning/transmission electron microscopy, and differential scanning calorimetry were used to characterize the microstructure of powders. Starting from W, Co, and graphite powder mixtures, the DBDP-milled W-C-10Co powder exhibited a flakelike morphology with very fine lamellar structure. The WC-Co composite powder was synthesized at 1273 K (1000 °C), which is much lower than the requisite temperature for the conventional carburizing method. The obtained WC-Co composite powder had a nanocomposite microstructure in which fine WC particles were bounded by homogenously distributed Co phase, and the WC crystals had a slablike morphology with a planar size of about 200 nm and <100-nm thickness. The combinational effect of the milling and the plasma in the DBDP milling caused a unique fine flakelike morphology and high-density interfaces in the W-C-10Co powder mixture, which is responsible for the reduced carburization temperature and the nanocomposite structure of WC-Co powder.

  20. Corrosion resistance of kolsterised austenitic 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Abudaia, F. B., E-mail: fabudaia@yahoo.com; Khalil, E. O., E-mail: ekhalil9@yahoo.com; Esehiri, A. F., E-mail: Hope-eseheri@hotmail.co.uk; Daw, K. E., E-mail: Khawladaw@yahoo.com [University of Tripoli Department of Materials and Metallurgical Eng, Tripoli-Libya P.O.Box13589 (Libya)

    2015-03-30

    Austenitic stainless suffers from low wear resistance in applications where rubbing against other surfaces is encountered. This drawback can be overcome by surface treatment such as coating by hard materials. Other treatments such as carburization at relatively low temperature become applicable recently to improve hardness and wear resistance. Carburization heat treatment would only be justified if the corrosion resistance is unaffected. In this work samples of 304 stainless steels treated by colossal supersaturation case carburizing (known as Kolsterising) carried out by Bodycote Company was examined for pitting corrosion resistance at room temperature and at 50 °C. Comparison with results obtained for untreated samples in similar testing conditions show that there is no deterioration in the pitting resistance due to the Kolsterising heat treatment. X ray diffraction patterns obtained for Kolsterising sample showed that peaks correspond to the austenite phase has shifted to lower 2θ values compared with those of the untreated sample. The shift is an indication for expansion of austenite unit cells caused by saturation with diffusing carbon atoms. The XRD of Kolsterising samples also revealed additional peaks appeared in the patterns due to formation of carbides in the kolsterised layer. Examination of these additional peaks showed that these peaks are attributed to a type of carbide known as Hagg carbide Fe{sub 2}C{sub 5}. The absence of carbides that contain chromium means that no Cr depletion occurred in the layer and the corrosion properties are maintained. Surface hardness measurements showed large increase after Kolsterising heat treatment.

  1. BioTfueL Project: Targeting the Development of Second-Generation Biodiesel and Biojet Fuels Le projet BioTfueL : un projet de développement de biogazole et biokérosène de 2 génération

    Directory of Open Access Journals (Sweden)

    Viguié J.-C.

    2013-10-01

    Full Text Available 2nd generation biofuels will have an important part to take in the energy transition as far as fuels are concerned. Using non edible biomass, they will avoid any direct competition with food usage. Within 2nd generation biofuels, the BTL route consists in the production of middle distillates (Diesel and jet fuel via gasification and Fischer-Tropsch (FT synthesis. These fuels are called “drop in” fuels; this means that to be used they technically do not request any modification in the vehicle whatever the blending rate with conventional fuels. This route is currently at the pre-industrial phase where demonstration is required. This article presents the BioTfueL project which has been created by Axens, CEA, IFP Energies nouvelles, Sofiprotéol, ThyssenKrupp Uhde and Total. This project is focused on the original concept of co-processing (biomass can be gasified together with fossil feedstock and proposes to develop and demonstrate a full process chain to be commercialized worldwide via licensing. Les biocarburants de 2e génération ont un rôle important à jouer en ce qui concerne le pool carburant dans le cadre de la transition énergétique. Utilisant comme matière première de la biomasse non comestible, ces carburants éviteront toute compétition directe avec un usage alimentaire de cette ressource. Parmi les biocarburants de 2e génération, la voie BTL consiste en la production de distillats moyens (gazole moteur et carburéacteur via gazéification et synthèse Fischer-Tropsch (FT. Ces carburants sont communément appelés des « drop in fuels », ce qui signifie que techniquement ils ne nécessitent aucune modification du véhicule quelque soit leur taux d’incorporation dans les carburants traditionnels. Cette voie entre actuellement en phase préindustrielle pour laquelle une démonstration est nécessaire. Cet article présente le projet BioTfueL qui est porté par Axens, le CEA, IFP Energies nouvelles, Sofiprotéol, Thyssen

  2. 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.)

  3. Softening Behavior of Hardness and Surface Fatigue of Rolling-Sliding Contact in the Case of Developed Alloy Steels

    Science.gov (United States)

    Redda, Daniel Tilahun; Nakanishi, Tsutomu; Deng, Gang

    To get high performance, downsizing and weight saving of the power transmission systems, the improvement of machine elements has been required. In this study, case-carburized gear materials for a high load-carrying capacity were developed. Low-alloyed steels with 1%Cr-0.2%Mo, 1%Cr-0.2%Mo-1%Si and 1%Cr-0.2%Mo-2%Ni (Cr-Mo steel, Cr-Mo-Si steel and Cr-Mo-Ni steel) were melted in a hypoxia vacuum. Test rollers were made of the developed steels, and they were carburized (Type A and Type B), hardened and tempered. Heating retention tests were carried out to investigate the softening behavior of hardness at high heating temperatures in the case of the developed steels. Roller tests were conducted under the rolling-sliding contact and high-load conditions to study the surface fatigue of the developed steels. From the obtained test results, it was found that the softening behavior of surface hardness at high temperatures in the cases of Cr-Mo-Si steel (Type A) and Cr-Mo-Ni steel (Type B) is lower than that in the cases of Cr-Mo steel (Type A) and Cr-Mo steel (Type B). In the cases of Cr-Mo-Si steel (A) and Cr-Mo-Ni steel (B), micro- and small-pitting area ratios are smaller and large-pitting life is longer than those in the cases of Cr-Mo steel(A) and Cr-Mo steel(B) under the same carburizing treatment method and high-load conditions. Furthermore, the relationship between the softening behavior of surface hardness on the heating pattern and the surface fatigue on the rolling-sliding contact of the developed alloy steels was clarified.

  4. In situ auger analysis of surface composition during high fluence ion implantation

    Science.gov (United States)

    Baldwin, D. A.; Sartwell, B. D.; Singer, I. L.

    1985-03-01

    A multi-technique ultrahigh vacuum (UHV) target chamber has been used to perform in situ Auger electron spectroscopic (AES) analysis during ion implantation and AES sputter depth profiling of the substrate within 1-2 min after implantation. Iron was implanted with 150 keV Ti + at a 45° angle of incidence in a target chamber with pressures ranging from 8 × 10 -9 Torr of residual gases up to 1 × 10 -5 Torr of intentionally admitted CO gas. A fluence of ∼1.0 × 10 16cm -2 was needed to sputter away the C-covered air-formed oxide. The implanted Ti reached the surface at the 1 at.% level by ∼1.5 × 10 16cm -2. With increasing fluence, the Ti surface concentration increased to ∼15 at.% at steady-state with a curve shape that was concave downward at all fluences. The surface C concentration was found to be proportional to that of Ti for implants in CO, supporting a vacuum carburization model. Substantial O surface concentration (15-20 at.%) was detected for these runs but depth profiles showed only carburization, not oxidation, of the implanted layer. Even in the best vacuum available (8 × 10 -9Torr), some carburization was observed and was attributed to residual gas absorption. An increase in Ti retained dose with increasing CO pressure has been observed but not yet independently confirmed. The Ti/Fe surface concentration ratio is higher for implants done in CO, and this is discussed in terms of modification of the sputter yield for Ti.

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

    International Nuclear Information System (INIS)

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

  6. 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.

  7. Biocarburants : la Commission propose d’encourager leur utilisation

    Directory of Open Access Journals (Sweden)

    Vermeersch Georges

    2002-01-01

    Full Text Available Depuis longtemps, la Commission, le Parlement et le Conseil encouragent le développement des sources d’énergie renouvelables, et plus particulièrement des biocarburants. Cela s’est traduit, entre autres, par la publication en novembre 2000 d’un livre vert intitulé « Vers une stratégie européenne de sécurité d’approvisionnement énergétique », qui fixe comme objectif, d’ici 2020, le remplacement de 20% des carburants classiques par des carburants de substitution pour le transport routier. Plus récemment, en juin 2001, au sommet de Göteborg, a été souligné le rôle important des biocarburants dans la lutte contre le changement climatique et le développement des énergies propres. Ces encouragements restaient au niveau de la déclaration d’intention faute de moyens administratifs et fiscaux pour bâtir une véritable stratégie. Depuis le 7 novembre 2001, les choses semblent évoluer : en effet, à cette date, le collège des Commissaires a adopté une communication sur les carburants de substitution pour les transports routiers et une série de mesures visant à promouvoir l’utilisation des biocarburants. De plus - et c’est ce qui est fondamental - cette communication était assortie de deux propositions de directives, l’une visant à promouvoir l’utilisation des biocarburants dans les transports, l’autre concernant la possibilité d’appliquer un taux d’accises réduit sur certaines huiles minérales qui contiennent des biocarburants et sur les biocarburants.

  8. Study of the sulfur mechanism on the formation of coke deposition on iron surfaces; Etude des mecanismes d'action du soufre sur le cokage catalytique du fer

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet, F.

    2001-12-01

    The formation of coke deposition which occurs in a range of temperature 500 deg C-650 deg C is a major problem in many chemical and petrochemical processes where hydrocarbons or other strongly carburizing atmospheres are involved. To reduce the rate of coke deposition, sulfur can be added in the gas phase. The topic of this work is to study the sulfur mechanism on the formation of coke deposition on iron surfaces. Firstly, we study the mechanism of graphitic filament formation on reduced and oxidised iron surfaces. A new mechanism of catalytic particle formation is proposed when the surface is initially oxidised. This mechanism is based on thermodynamic, kinetic and structural considerations. The results show that oxide/carbide transitions are involved in the transformation of the oxide layer in catalytic particles. Although the different iron oxides are precursors for the formation of catalytic particles, wustite (FeO) has a better reactivity than magnetite (Fe{sub 3}O{sub 4}) and hematite (Fe{sub 2}O{sub 3}). Sulfur acts on different steps of the coke formation, preventing phase transformations (carburation, graphitization) which occur during the formation of catalytic particles. Sulfur activity required to prevent these transformations changes with the temperature, the chemical state of iron (reduced or oxidised) and the carbon activity in the gas phase. Sulfur/ethylene co-adsorption studies were performed on mono-crystal of iron (110). The results show that sulfur can prevent adsorption and decomposition of this hydrocarbon on metallic surface (Fe) and on magnetite (Fe{sub 3}O{sub 4}). Then, sulfur prevents the reaction leading to the carburation and graphitization of the surface. (author)

  9. Effect of low temperature plasma hardening treatment on microstructure and properties of AISI 420 stainless steel%低温离子硬化处理对 AISI 420不锈钢组织与性能的影响

    Institute of Scientific and Technical Information of China (English)

    杜威; 赵程

    2014-01-01

    研究了低温离子渗氮、离子氮碳共渗和离子渗碳硬化处理对AISI 420马氏体不锈钢的显微组织、表面硬度、耐蚀性、耐磨性的影响。结果表明,离子渗氮、氮碳共渗和离子渗碳处理都可提高马氏体不锈钢的表面硬度;经不同工艺处理后的试样,除500℃×4 h渗氮工艺外,其他不锈钢试样表面的耐蚀性均未出现明显降低,当渗氮温度过高(500℃)时,由于CrN的析出使得渗氮层的耐蚀性显著下降;磨损试验的结果表明,离子渗碳处理后硬化层的耐磨性最佳。%Effect of low temperature plasma nitriding , nitrocarburizing and carburizing on microstructure , surface hardness , corrosion resistance and wear resistance of AISI 420 martensitic stainless steel was investigated . The results show that plasma nitriding , nitrocarburizing and carburizing process can increase the surface hardness .There is no significantly decrease to the corrosion resistance on the surface of Stainless steel treated by different treatment processes except of plasma nitriding at 500℃for 4 h.If the nitriding temperature is higher than 500℃, the corrosion resistance will significantly decline due to the precipitation of CrN .The wear results show that hardened layer of plasma carburizing sample has the best wear resistance .

  10. Bilans énergétiques et environnementaux des systèmes type dans les filières biogaz : Application au traitement des boues résiduaires en France

    OpenAIRE

    ALMANSOUR, Essam; BONNET, Jean-François

    2010-01-01

    Le biogaz constitue, dans l’optique des transports durables, une solution possible pour la production de carburant renouvelable. Les bilans énergétiques et environnementaux doivent être produits et comparés afin d’évaluer les alternatives en bilan global. Pour la France, une filière type décrivant le traitement par méthanisation des boues des stations d’épurations urbaines en France a été définie et étudiée par enquêtes techniques, sous la forme de systèmes type. Le bilan environnemental est ...

  11. Mechanisms of metal dusting corrosion

    DEFF Research Database (Denmark)

    Hummelshøj, Thomas Strabo

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

  12. Evolutions du parc automobile... quelques focus, intervention invitée le 8/1/2013 au Geri DYNAV

    OpenAIRE

    HIVERT, Laurent; Kolli, Zehir

    2013-01-01

    L'équipe de Dest fait une présentation de cadrage au lancement du Geri Dynamique du véhicule. Y sont successivement présentés : les sources et données de cadrage pour le parc des voitures particulières, les grandes tendances récentes, l'équipement et l'usage en lien avec le prix des carburants (vers un 'peak-car' ?), le diesel des années 2000, ainsi que la survie et le renouvellement des véhicules.

  13. Multiscale architectured materials with composition and grain size gradients manufactured using high-pressure torsion

    Science.gov (United States)

    Kang, Ji Yun; Kim, Jung Gi; Park, Hyo Wook; Kim, Hyoung Seop

    2016-05-01

    The concept of multiscale architectured materials is established using composition and grain size gradients. Composition-gradient nanostructured materials are produced from coarse grained interstitial free steels via carburization and high-pressure torsion. Quantitative analyses of the dislocation density using X-ray diffraction and microstructural studies clearly demonstrate the gradients of the dislocation density and grain size. The mechanical properties of the gradient materials are compared with homogeneous nanostructured carbon steel without a composition gradient in an effort to investigate the gradient effect. Based on the above observations, the potential of multiscale architecturing to open a new material property is discussed.

  14. Effect of electrolytes on cataphoretically deposited LaB6 cathodes

    Science.gov (United States)

    Khairnar, Rajendra S.; Joag, D. S.; Kulkarni, S. K.; Nigavekar, A. S.; Kanitkar, P. L.

    1984-09-01

    Various electrolytes were used to deposit LaB6 on carburized tantalum by the cataphoretic method. The effect of four electrolytes viz., HCl, NH4NO3, La(NO3)3, and HNO3 on LaB6 coatings has been investigated. It is observed that use of HCl as an electrolyte provides LaB6 coatings with small grain size, low porosity, good adhesion, and ability to withstand a large number of thermal shocks. These properties make HCl the most suitable electrolyte for cataphoretic deposition of LaB6 for thermionic emission.

  15. Agronomy for sustainable agriculture. A review

    OpenAIRE

    Lichtfouse, Eric; Navarrete, Mireille; Debaeke, Philippe; Souchere, Veronique; Alberola, Caroline; Ménassieu, Josiane

    2009-01-01

    Le développement durable repose sur le principe que nous devons répondre aux besoins présent sans compromettre ceux des générations à venir.[br/] Des gens qui meurent de faim dans les pays pauvres, des obèses dans les pays riches, l’augmentation des prix de la nourriture, le changement climatique, l'augmentation des coûts du carburant et du transport, la mondialisation, la pollution par les pesticides, l'adaptation et la résistance des parasites, la perte de fertilité du sol et le carbone org...

  16. Processing of Nanostructured WC-Co Powders and Sintered Steels

    OpenAIRE

    Zhang, Zongyin

    2003-01-01

    Processing of nanostructured WC-Co and W-Co powders,modelling of Fe-Mn-Si alloy, swelling of Fe-Cu alloy, andmechanical properties and sintering of Fe-Mn-Si steels havebeen studied in the present thesis. W-Co precursors made by chemical synthesis were used toproduce nanostructured WCCo and W-Co powders by calcination,reduction and carburization. The phase constituents in thecalcined powders depend on temperature and atmospheres. Cobaltcan accelerate the reduction rate of the W-Co precursors a...

  17. An introduction to surface alloying of metals

    CERN Document Server

    Hosmani, Santosh S; Goyal, Rajendra Kumar

    2014-01-01

    An Introduction to Surface Alloying of Metals aims to serve as a primer to the basic aspects of surface alloying of metals. The book serves to elucidate fundamentals of surface modification and their engineering applications. The book starts with basics of surface alloying and goes on to cover key surface alloying methods, such as carburizing, nitriding, chromizing, duplex treatment, and the characterization of surface layers. The book will prove useful to students at both the undergraduate and graduate levels, as also to researchers and practitioners looking for a quick introduction to surface alloying.

  18. Multiscale architectured materials with composition and grain size gradients manufactured using high-pressure torsion.

    Science.gov (United States)

    Kang, Ji Yun; Kim, Jung Gi; Park, Hyo Wook; Kim, Hyoung Seop

    2016-05-27

    The concept of multiscale architectured materials is established using composition and grain size gradients. Composition-gradient nanostructured materials are produced from coarse grained interstitial free steels via carburization and high-pressure torsion. Quantitative analyses of the dislocation density using X-ray diffraction and microstructural studies clearly demonstrate the gradients of the dislocation density and grain size. The mechanical properties of the gradient materials are compared with homogeneous nanostructured carbon steel without a composition gradient in an effort to investigate the gradient effect. Based on the above observations, the potential of multiscale architecturing to open a new material property is discussed.

  19. Synthesis of Nanocrystalline α-Mo_2C from Peroxomolybdenum Compounds

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Introduction Considerable attentions have been focused on transition metal carbide because of their numerous valuable properties, particularly of excellent catalysis similar to noble metal[1]. There are many routes[2]to synthesize molybdenum carbide. Among them, the temperature programmed reduction of MoO3 using the mixture of hydrocarbon and hydrogen is the most promising procedure to prepare carbide catalyst. Traditionally, CH4/H2 and C2H6/H2 are the most widely used to be the carburizing resource. ...

  20. Metal-dusting resistance of uncoated and coated iron and nickel base materials against metal-dusting in heat treatment furnaces with carbonaceous atmospheres; Bestaendigkeit von unbeschichteten und beschichteten Eisen- und Nickelbasiswerkstoffen gegenueber Metal-Dusting in Aufkohlanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Kleingries, Mirko; Ackermann, Helen; Lucka, Klaus [OWI Oel-Waerme-Institut GmbH, Aachen (Germany); Hoja, Timo; Mehner, Andeas; Zoch, Hans-Werner [IWT, Stiftung Institut fuer Werkstofftechnik, Bremen (Germany); Altena, Herwig [AICHELIN Ges.m.b.H, Moedling (Austria)

    2010-03-15

    Metal-Dusting is a well-known corrosion problem that occurs in carburizing atmospheres in industrial thermal processing plants. In literature almost no quantitative data on the metal dusting resistance of typical alloys employed in industrial furnaces are available. Therefore, a series of experiments with uncoated and sol gel ZrO{sub 2} coated high temperature materials was conducted in order to quantify their metal dusting behaviour under conditions close to those in case hardening furnaces. The experimental results show a strong influence of the surface conditions on the alloys resistance and a noticeable enhancement of the resistance by sol gel coatings. (orig.)

  1. Alloys for 1000 degree C service in the Next Generation Nuclear Plant NERI 05-0191

    Energy Technology Data Exchange (ETDEWEB)

    Gary S. Was; J.W. Jones; T. Pollock

    2009-01-15

    The objective of the proposed research is to define strategies for the improvement of alloys for structural components, such as the intermediate heat exchanger and primary-to-secondary piping, for service at 1000 degree C in the He environment of the NGNP. Specifically, we will investigate the oxidation/carburization behavior and microstructure stability and how these processes affect creep. While generating this data, the project will also develop a fundamental understanding of how impurities in the He environment affect these degradation processes and how this understanding can be used to develop more useful life prediction methodologies.

  2. 密封箱式多用炉的现状%Application Circumstances of Sealed Multi-purpose Furnace

    Institute of Scientific and Technical Information of China (English)

    吉泽升; 康国华; 赵密

    2001-01-01

    The sealed multi-purpose furnace is widespreadly used heat treatment furnace.The development circumstance of construction,material,carburizing technology and control system of sealed multi-purpose furnace is introduced in this paper.%密封箱式多用炉是当今热处理炉的一个发展趋势,本文介绍了密封箱式多用炉在材料、结构、渗碳和控制等方面的现状。

  3. Kinetics of Hydrocarbon formation in a- C:H Film deposition plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Cal, E. de la; Tabares, F. L.

    1993-07-01

    The formation of C2 and Cp hydrocarbons during the PACVD of a-C:H films from admixtures of methane with H2 and He has been investigated by mass spectrometry under several deposition condition. The time evolution of the observed species indicates that the formation mechanisms of ethylene and acetylene are sensitive to the conditions of the wall during the growing of the film. Acetylene are sensitive to the conditions of the wall during the growing of the film. Acetylene formation was found to be directly related to the formation of the film on top of the carburized metal. (Author) 12 refs.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-08-10

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

  5. MODELISATION DE LA COMBUSTION D'UN SPRAY DANS UN BRULEUR AERONAUTIQUE

    OpenAIRE

    Paulhiac, Damien

    2015-01-01

    La combustion d'hydrocarbures représente encore aujourd'hui une part très majoritaire de la production d'énergie mondiale, en particulier dans la propulsion aérospatiale. La plupart des brûleurs industriels sont alimentés par un carburant sous forme liquide, qui est injecté directement dans la chambre de combustion, ce qui génère une forte interaction entre le spray, l’écoulement turbulent et la zone de combustion. Cette interaction a déjà largement été étudiée, mais certaines questions reste...

  6. Une approche expérimentale sur l’allongement des rotations et l’implantation de bandes enherbées en grandes cultures pour maximiser les services rendus par la biodiversité végétale et microbienne

    OpenAIRE

    Piutti, Séverine; Schneller, Chloé; Guimont, H.-P.; Amiaud, Bernard

    2010-01-01

    Dans le contexte actuel de promotion des cultures énergétiques, le colza a des atouts comme fournisseur de biomasse alternative aux carburants automobiles sous forme de diester par exemple et les surfaces mises en culture ont connu ces dernières années une augmentation très significative. Cependant, le colza est une culture nécessitant une utilisation importante d’intrants notamment phytosanitaires et qui dans un contexte de durabilité des systèmes de culture doit être intégré dans une rotati...

  7. Influence Of Heat Treatment On Duplex Stainless Steel To Study The Material Properties

    Directory of Open Access Journals (Sweden)

    Jithin M

    2015-02-01

    Full Text Available Abstract The various heat treatment processes are annealing normalizing hardening tempering spheroidising surface hardening flame and induction hardening nitriding cyaniding carbonitriding carburizing etc Heat treatment on duplex stainless steel is to improve ductility toughness strength hardness and to relieve internal stress developed in the material. Here basically the experiment of hardness test impact test wear test and compression is done to get idea about heat treated duplex stainless steel which has extensive uses in all industries and scientific research and development fields.

  8. Fiscal 1998 research report. Development of metal forming technology by new energy-saving process (2nd fiscal year); 1998 nendo sho energy gata shin process ni yoru kinzoku seikei gijutsu no kaihatsu (dai 2 nendo)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    Based on computer-aided science possible to estimate phase transformation temperatures affecting fine crystal grain control strongly, this research develops the energy- saving production technology for near-net-shape manufacturing of heat-resistant hard materials such as HSS, TiAl and W, by using the new sintering and bonding technology by texture control, complex carbide dispersion technology and pulse discharge sintering based on phase diagram calculation. In fiscal 1998, study was made on optimum alloy composition and heat treatment condition to obtain high-hardness steel with the performance over that of existing HSS by carbide dispersion carburizing process using conventional gas-carburizing facility, based on the data of phase diagram calculation. As a result, the composition and heat treatment condition necessary to obtain a target hardness of Hv1000 were determined. As the research result in both fiscal 1997 and 1998, 10Mo-5V alloy for HSS including a large amount of Mo and V, and 3.5Mo- 1.5V-3Cr alloy for HSS including less than 6% Mo and V are promising as basic composition for the future R and D. (NEDO)

  9. Influence of steel composition and plastic deformation on the surface properties induced by low temperature thermochemical processing

    DEFF Research Database (Denmark)

    Bottoli, Federico

    Low-temperature thermochemical surface hardening by nitriding, carburizing and nitrocarburizing is used to improve the performance of stainless steels with respect to wear, fatigue and corrosion resistance.The dissolution of nitrogen and/or carbon atoms in the materials surface leads to the forma......Low-temperature thermochemical surface hardening by nitriding, carburizing and nitrocarburizing is used to improve the performance of stainless steels with respect to wear, fatigue and corrosion resistance.The dissolution of nitrogen and/or carbon atoms in the materials surface leads...... products. The activities carried out encompass the study and the characterization of the following aspects: ‐ Influence of plastic deformation prior to the low-temperature thermochemical process ‐ Influence of initial phase composition on the properties and morphology of thenitrided/nitrocarburized surface...... layer ‐ Influence of interstitial alloying on the mechanical properties of stainless steels ‐ Study of the corrosion performance of expanded austenite layer. ‐ Study of compressive residual stresses in expanded austenite and the influence of the material condition prior to nitriding/nitrocarburizing...

  10. Surface Modification of Commercially Pure Titanium by Plasma Nitrocarburizing at Different Temperatures and Duration Process

    Directory of Open Access Journals (Sweden)

    Agung Setyo Darmawan

    2013-02-01

    Full Text Available One of potential metals to be used in biomechanical applications is the commercially pure (cp titanium. This material requires a process to improve the mechanical properties of the surface, because it is relatively soft. The purpose of this study is to determine the effect of plasma nitro carburizing process to cp titanium surface hardness. In this study, cp titanium plasma nitro carburizing process is conducted at different temperatures, i.e., at 350°C for 3, 4, and 5 h, and at 450°C for 2, 3, and 4 h, respectively. Hardness tests are then performed on each specimen. The depth of penetration in the hardness test is also recorded; the microstructure captures are also taken using an optical microscope. The results show that the longer processing time, the higher the hardness value. In higher temperature, the hardness values correspond to the increasing temperature. In terms of the depth direction, there is a reduction in hardness value compared to the raw material.

  11. FY 1998 annual report on the development of plasma-aided surface treatment processes by in-situ controlling (second year); 1997 nendo in-situ seigyo ni yoru plasma riyo hyohi shori process no kaihatsu seika hokokusho (dai 2 nendo)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    This R and D project is aimed at stable production of high-quality, important machine members, which are difficult to sufficiently achieve the required properties by a single material, by carburization while minimizing use of expensive alloy metals, where high-temperature carburizing time is reduced by a plasma-aided system to save energy, and, at the same time, the conventional oil-hardening system is replaced by a He gas cooling/recycling system to solve the environmental problems involved in the former. The exhaust gases released from the plasma-aided system are adequately treated to prevent the problems caused thereby. The conditions of the plasma itself and treated surfaces are sensed in-situ, and the data are fed back to the process controlling system, to keep the treated object stable and high in quality, while minimizing energy consumption. The FY 1998 efforts were directed to studies on methods for sensing the plasma and treated surfaces, and specifications of a mini-plant for the demonstration tests, and to collection of characteristic data for development of some new products to be produced. (NEDO)

  12. Kinetics of the formation of metal binder gradient in WC-Co by carbon diffusion induced liquid migration

    International Nuclear Information System (INIS)

    Cemented tungsten carbide (WC-Co) with a cobalt content gradient from the surface to the bulk of a sintered piece is an example of a functionally graded material, the mechanical properties of which are optimized by the unique gradient microstructure, giving rise to superior combinations of wear resistance vs. fracture toughness. A process for creating such cobalt gradients in WC-Co was developed recently based on heat treatments of fully sintered WC-Co materials in carburizing atmospheres. A study of the kinetics of the process is necessary to fully understand the mechanisms of the process in order to achieve desired or designed gradients. In this paper, a series of carburizing experiments were conducted to examine the effects of key process parameters including temperature, composition of the atmosphere, and time on the overall kinetics of the process. A kinetic model was established to predict the thickness of the gradient as a function of these process variables, enabling the design of functionally graded WC-Co through controlling atmosphere and time.

  13. Kinetics of the formation of metal binder gradient in WC-Co by carbon diffusion induced liquid migration

    Energy Technology Data Exchange (ETDEWEB)

    Guo Jun [Department of Metallurgical Engineering, University of Utah, 135 S. 1460 E. Room 412, Salt Lake City, UT 84112 (United States); Fang, Zhigang Zak, E-mail: zak.fang@utah.edu [Department of Metallurgical Engineering, University of Utah, 135 S. 1460 E. Room 412, Salt Lake City, UT 84112 (United States); Fan Peng; Wang Xu [Department of Metallurgical Engineering, University of Utah, 135 S. 1460 E. Room 412, Salt Lake City, UT 84112 (United States)

    2011-06-15

    Cemented tungsten carbide (WC-Co) with a cobalt content gradient from the surface to the bulk of a sintered piece is an example of a functionally graded material, the mechanical properties of which are optimized by the unique gradient microstructure, giving rise to superior combinations of wear resistance vs. fracture toughness. A process for creating such cobalt gradients in WC-Co was developed recently based on heat treatments of fully sintered WC-Co materials in carburizing atmospheres. A study of the kinetics of the process is necessary to fully understand the mechanisms of the process in order to achieve desired or designed gradients. In this paper, a series of carburizing experiments were conducted to examine the effects of key process parameters including temperature, composition of the atmosphere, and time on the overall kinetics of the process. A kinetic model was established to predict the thickness of the gradient as a function of these process variables, enabling the design of functionally graded WC-Co through controlling atmosphere and time.

  14. Rolling Bearing Steels - A Technical and Historical Perspective

    Science.gov (United States)

    Zaretsky, Erwin V.

    2012-01-01

    Starting about 1920 it becomes easier to track the growth of bearing materials technology. Until 1955, with few exceptions, comparatively little progress was made in this area. AISI 52100 and some carburizing grades (AISI 4320, AISI 9310) were adequate for most applications. The catalyst to quantum advances in high-performance rolling-element bearing steels was the advent of the aircraft gas turbine engine. With improved bearing manufacturing and steel processing together with advanced lubrication technology, the potential improvements in bearing life can be as much as 80 times that attainable in the late 1950s or as much as 400 times that attainable in 1940. This paper summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability. The single most important variable that has significantly increased bearing life and reliability is vacuum processing of bearing steel. Differences between through hardened, case carburized and corrosion resistant steels are discussed. The interrelation of alloy elements and carbides and their effect on bearing life are presented. An equation relating bearing life, steel hardness and temperature is given. Life factors for various steels are suggested and discussed. A relation between compressive residual stress and bearing life is presented. The effects of retained austenite and grain size are discussed.

  15. Prevention of crack initiation in valve bodies under thermal shock

    Energy Technology Data Exchange (ETDEWEB)

    Delmas, J.; Coppolani, P.

    1996-12-01

    On site and testing experience has shown that cracking in valves affects mainly the stellite hardfacing on seats and discs but may also be a concern for valve bodies. Metallurgical investigations conducted by EDF laboratories on many damaged valves have shown that most of the damage had either a chemical, manufacturing, or operating origin with a strong correlation between the origins and the type of damage. The chemical defects were either excess ferritic dilution of stellite or excess carburizing. Excess carburizing leads to a too brittle hardfacing which cracks under excessive stresses induced on the seating surfaces, via the stem, by too high operating thrusts. The same conditions can also induce cracks of the seats in the presence, in the hardfacing, of hidden defects generated during the welding process. Reduction of the number of defects results first from controls during manufacturing, mainly in the thickness of stellite. On the other hand, maintenance must be fitted to the type of defect. In-situ lapping may lead to release of cobalt, resulting in contamination of the circuit. Furthermore, it is ineffectual in the case of a crack through the seating surface, as is often found on globe valves. The use of new technologies of valves with removable seats and cobalt-free alloys solves permanently this kind of problem.

  16. Autogas at Equip'Auto 2001: a very calm vintage; Le GPL a Equip'Auto 2001, un cru bien calme

    Energy Technology Data Exchange (ETDEWEB)

    Valcano, N.

    2001-09-01

    Autogas equipment manufacturers and importers, as well as the other actors in this field will be present in a mitigated atmosphere at the Equip'Auto 2001 Trade Show, at Paris-Nord Villepinte from 16 to 21 October. The market is at slow pace after new regulatory changes and this leads importers and installers/fitters to act in a carefulness way, as the retrofit operation in progress across the country (the fitting of the R67-01 type safety relief valve) amounts today to a large share in installers' activity. Thus, no more than a dozen of booths will show autogas components and technologies. Nevertheless, some brand new products will be exhibited. At the end of August, foreign exhibitors listed were Sahinler Metal (Turkey) and Brecav (Italy). But some brands will be found on importers booths. Cora Auto distributes Tartarini's Etagas system, as does on its side 'la Carburation Gaz'. OMVL and now Landi will be found at France GPL Carburation's. Cofraca, the French arm of Necam-Koltec, will be present, as well as some installers groupings, dispensers manufacturers and Autogas distributors. (authors)

  17. Reduction of FeO in EAF steelmaking slag by blends of metallurgical coke and end-of-life tyre

    Energy Technology Data Exchange (ETDEWEB)

    Dankwah, James R.; Koshy, Pramod; Sahajwalla, Veena [Centre for Sustainable Materials Research and Technology, School of Materials Science and Engineering, University of New South Wales, Sydney, NSW (Australia); O' Kane, Paul [OneSteel Sydney Mill, Rooty Hill, NSW (Australia)

    2012-08-15

    The reduction of FeO-containing slag by blends of metallurgical coke and end-of-life tyres (RT) have been investigated through experiments conducted in a laboratory-scale horizontal tube furnace. Composite pellets of EAF slag (47.1% FeO) with coke, RT, and blends of coke/RT (in four different proportions) were rapidly heated at 1550 C under high purity argon gas and the off gas was continuously analyzed for CO and CO{sub 2}using an online infrared (IR) gas analyzer. The extent of reduction after 10 min, level of carburization and desulfurization, and the total amount of CO{sub 2} emissions were determined for each carbonaceous reductant. The results indicate that the extent of reduction, level of carburization and desulfurization of the reduced metal are significantly improved when coke is blended with RT. Blending of coke with RT resulted in a decrease in direct CO{sub 2} emissions from the reduction reactions. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Application of Empirical Electron Theory of Solids and Molecules to Composition Design of Multi-Component Medium-Low-Alloy Steels

    Institute of Scientific and Technical Information of China (English)

    SHI Juyan; XIE Guisheng

    2012-01-01

    For austenitic octahedral segregation structure units,their pure mathematics statistic distributive probability is calculated by the empirical electron theory (EET) of solids and molecules and K-B formula.The practical distributive probability can be obtained only if the statistic distribution of austenitic octahedral segregation structure units and the interaction of the alloying elements in steel are considered.Based on 8 groups of experimental data of original steels,three empirical formulas revealing relationships between material macromechanics factor (Sm) and tensile strength (σb),or impact energy (Aκ),or hardness (HRC) of multi-component medium-low-alloy steels were established,respectively.Through the three empirical formulas,new supersaturated carburizing steel has been successfully designed and developed.The other 2 groups of the original experimental steels are used as the standard steel for testing the percentage error of the new steel.The results show that the calculated values are well consistent with those of measured ones and the new supersaturated carburized steel can meet the requirements of the die assembly of cold-drawn seamless stainless steel tube of Taiyuan Iron & Steel (Group) Company LTD.

  19. Surface strengthening using a self-protective diffusion paste and its application for ballistic protection of steel plates

    International Nuclear Information System (INIS)

    This paper deals with surface strengthening of steel plates using a self-protective diffusion paste. During the surface strengthening process, a paste containing carbon, boron or similar is applied on the steel surface. In addition to serving as a source for the various diffusion ingredients, the paste protects the steel against contact with the environment, so no packing or gas protection is necessary. Thus, the handling is in general very simple, and the surface strengthening process can be performed in a conventional air furnace. The method provides the same type of surface strengthening that is obtained by more conventional methods. In this work, the main focus will be surface strengthening by carburizing, but also boronizing and boronizing followed by carburizing have been tested out. The methods have been applied to increase the ballistic resistance of the low-strength carbon steel NVE36 (with nominal yield stress of 355 MPa) against impacts from small-arms bullets. An empirical model combining diffusion depth, heat-treatment temperature and soaking time was established on the basis of a series of experimental data. By means of this equation, the various heat-treatment parameters can be predicted when others are chosen. Ballistic perforation tests using 7.62 mm APM2 bullets showed that the low-strength carbon steel after surface strengthening obtained a ballistic limit higher than that of Hardox 400, which is a wear steel with a yield stress of about 1200 MPa.

  20. Study of the first stages of oxidation of a ferritic-martensitic steel Fe-12Cr in CO2

    International Nuclear Information System (INIS)

    In the framework of the development of Sodium Fast Reactors in France, supercritical carbon dioxide integrated in the Brayton cycle is proposed as new cycle energy conversion system to replace current steam generators. Ferritic-Martensitic steels with 9-12 wt% Cr are good candidates for heat exchanger application because they have good mechanical properties up to a temperature of 600 C, a high thermal conductivity, a low coefficient of thermal expansion and a lower cost than that of austenitic steels. However, it has been found that these steels present a high parabolic oxide growth rate and a strong carburization in the temperature and pressure conditions of the SC-CO2 cycle (550 C, 250 bar). This study aims to investigate the influence of different parameters (impurities present in CO2, thermal ramp rate and surface state) on the oxidation mechanism of a Fe-12 Cr steel in CO2 at 550 C. It has been shown that depending on these parameters, a thin protective oxide scale without any strong carburization can be obtained. A model is proposed to explain the experimental results. (author)

  1. Effects of magnetic field intensity on carbon diffusion coefficient in pure iron in γ-Fe temperature region

    Science.gov (United States)

    Wu, Yan; Duan, Guosheng; Zhao, Xiang

    2015-03-01

    Effects of magnetic field intensity on carbon diffusion coefficient in pure iron in the γ-Fe temperature region were investigated using carburizing technology. The carbon penetration profiles from the iron surface to interior were measured by field emission electron probe microanalyzer. The carbon diffusion coefficient in pure iron carburized with different magnetic field intensities was calculated according to the Fick's second law. It was found that the magnetic field intensity could obviously affect the carbon diffusion coefficient in pure iron in the γ-Fe temperature region, and the carbon diffusion coefficient decreased obviously with the enhancement of magnetic field intensity, when the magnetic field intensity was higher than 1 T, the carbon diffusion coefficient in field annealed specimen was less than half of that of the nonfield annealed specimen, further enhancing the magnetic field intensity, the carbon diffusion coefficient basically remains unchanged. The stiffening of lattice due to field-induced magnetic ordering was responsible for an increase in activation barrier for jumping carbon atoms. The greater the magnetic field intensity, the stronger the inhibiting effect of magnetic field on carbon diffusion.

  2. Effect of Manganese Incorporation Manner on an Iron-Based Catalyst for Fischer-Tropsch Synthesis

    Institute of Scientific and Technical Information of China (English)

    Tingzhen Li; Yong Yang; Chenghua Zhang; Zhichao Tao; Haijun Wan; Xia An; Hongwei Xiang; Yongwang Li

    2007-01-01

    A systematic study was undertaken to investigate the effects of the manganese incorporation manner on the textural properties,bulk and surface phase compositions,reduction/carburization behaviors,and surface basicity of an iron-based Fischer-Tropsch synthesis (FTS) catalyst.The catalyst samples were characterized by N2 Physisorption,X-ray photoelectron spectroscopy(XPS),H2(or CO) temperature-programmed reduction(TPR),CO2 temperature-programmed desorption(TPD),and Mossbauer spectroscopy.The FTS performance of the catalysts was studied in a slurry-phase continuously stirred tank reactor(CSTR).The characterization results indicated that the manganese promoter incor-porated by using the coprecipitation method could improve the dispersion of iron oxide,and decrease the size of the iron oxide crystallite.The manganese incorporated with the impregnation method is enriched on the catalyst's surface.The manganese promoter added with the impregnation method suppresses the reduction and carburization of the catalyst in H2,CO,and syngas because of the excessive enrichment of manganese on the catalyst surface.The catalyst added manganese using the coprecipitation method has the highest CO conversion (51.9%) and the lowest selectivity for heavy hydrocarbons(C12+).

  3. Eléments d'analyse du cliquetis et de ses effets Elements for Analyzing Knocking and Its Effects

    Directory of Open Access Journals (Sweden)

    Douaud A.

    2006-11-01

    Full Text Available On présente dans cet article une synthèse des travaux théoriques et expérimentaux relatifs à la génération du cliquetis et à ses effets sur le fonctionnement du moteur. L'apparition du cliquetis est décrite par un mécanisme global de délai d'auto-inflammation. Des exemples d'application portant sur l'identification du délai de carburants quelconques et sur l'optimisation de l'ensemble moteurs-carburants documentent cette approche. Le cliquetis a pour conséquence un accroissement de sollicitations mécaniques et thermiques des parois de la chambre de combustion. Des méthodes et résultats d'investigation de ces phénomènes sont présentés. A synthesis is presented of theoretical and experimental research concerning the generating of knocking and its effects on engine running. The appearance of knocking is described by an overall mechanism of autoignition delay. This approach is documented by applied examples concerning the identification of the delay involved with any type of fuel and the optimizing of engine-fuel systems. Knocking causes an increase in mechanical and thermal stresses on combustion-chamber walls. Investigational methods and results concerning these phenomena are described.

  4. Le Gaz Naturel Véhicule Natural Gas for Vehicles

    Directory of Open Access Journals (Sweden)

    De Chauveron S.

    2006-11-01

    Full Text Available Cet article présente le GNV (Gaz Naturel Véhicule. Le GNV a en effet de sérieux atouts, à la fois comme carburant de substitution et comme carburant propre. Ces atouts sont aussi bien économiques que techniques. La première partie est consacrée aux enjeux du développement du GNV. Les premiers pays utilisateurs ont été ceux qui disposent sur leur sol de ressources de gaz naturel. Aujourd'hui, alors que de nombreux pays doivent faire face à l'inquiétude croissante relative à l'augmentation de la pollution urbaine, le gaz naturel apparaît également comme un carburant propre, permettant de réduire rapidement les émissions de polluants des véhicules. Dans une deuxième partie, nous donnons une description technique sommaire des stations GNV et des véhicules GNV. Il s'agit de familiariser le lecteur avec les quelques spécificités techniques du GNV, par rapport à l'essence et au gazole. On constatera d'ailleurs que les technologies GNV sont très proches des technologies classiques. Enfin, la dernière partie est consacrée aux actions en cours, qui permettront le développement du GNV en France et en Europe : programmes de recherche, réduction des coûts de la filière, actions réglementaires, communication, etc. This article presents compressed natural gas for vehicles (CNG, which can provide considerable advantages both as an alternative fuel and as a clean fuel. These assets are not only economic but also technical. The first part deals with what is at stake in developing natural gas as a motor fuel. The first countries to use CNG were those with natural gas resources in their subsoil. Today, with a large number of countries having to cope with growing concern about increasing urban pollution, natural gas is also seen as a clean fuel that can help cut vehicle pollutant emissions dramatically. In the second part a brief technical description is given of CNG stations and vehicles, with the aim of acquainting the reader with

  5. Experimental determination of phase diagram and modeling: Application to refrigerant mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Coquelet, Christophe; Richon, Dominique [MINES ParisTech, CEP/TEP - Centre Energetique et Procedes, 35 rue St Honore, 77305 Fontainebleau Cedex (France)

    2009-11-15

    Accurate knowledge of phase diagrams is an essential step for optimized chemical engineering design and effective solution of engineering-related problem. As an example of the use of phase diagrams we have selected a topic at global concern which arose upon the discovery of the ozone depletion. In 1987, the Montreal protocol prohibited world-wide use and production of ChloroFluoroCarbons (CFCs) and of HydroChloroFluoroCarbons (HCFCs), while HydroFluoroCarbons (HFCs) were proposed as alternative refrigerants. Thus, the need arose for information required in the optimization of refrigerant production processes, particularly in the field of phase equilibria. These data can provide better evaluation of refrigerant production processes, especially with the aim of reducing global warning effects. In this communication, we present VLE equipments and the obtained phase diagrams concerning several binary systems involving R32, R290, R116, R744, R116, R134a, R227ea and other refrigerants. Cubic equations of state combining with modern mixing rules based on Gibbs excess models are used for the determination of phase diagrams. (author) [French] La connaissance des diagrammes de phases est essentielle, en genie des procedes, pour permettre aux ingenieurs de determiner la meilleure facon de proceder afin de trouver les solutions les plus efficaces et les plus performantes. Comme exemple d'utilisation des diagrammes de phases nous avons choisi le sujet traitant du probleme mondial qui est survenu lorsque le trou dans la couche d'ozone a ete decouvert. Les ChloroFluoroCarbures (CFC's) et HydroChloroFluoroCarbures (HCFC's) ont ete bannis lors du protocole de Montreal en 1987 au profit des HydroFluoroCarbures (HFC's) proposes comme solutions alternatives. Ces derniers ont un pouvoir de rechauffement climatique non negligeable et il est necessaire de disposer du maximum d'informations pour l'optimisation de leurs procedes de fabrication. Nous

  6. Corrosion Issues of High Temperature Reactor Structural Metallic Materials

    International Nuclear Information System (INIS)

    Cooling helium of high temperature reactors (HTRs) is expected to contain a low level of impurities: oxidizing gases and carbon-bearing species. Reference structural materials for pipes and heat exchangers are chromia former nickel base alloys, typically alloys 617 and 230. And as is generally the case in any high temperature process, their long term corrosion resistance relies on the growth of a surface chromium oxide that can act as a barrier against corrosive species. This implies that the HTR environment must allow for oxidation of these alloys to occur, while it remains not too oxidizing against in-core graphite. First, studies on the surface reactivity under various impure helium containing low partial pressures of H2, H2O, CO, and CH4 show that alloys 617 and 230 oxidize in many atmosphere at intermediate temperatures (up to 890-970 degrees C, depending on the exact gas composition). However when heated above a critical temperature, the surface oxide becomes unstable. It was demonstrated that at the scale/alloy interface, the surface oxide interacts with the carbon from the material. These investigations have established an environmental area that promotes oxidation. When exposed in oxidizing HTR helium, alloys 617 and 230 actually develop a sustainable surface scale over thousands of hours. On the other hand, if the scale is destabilized by reaction with the carbon, the oxide is not protective anymore, and the alloy surface interacts with gaseous impurities. In the case of CH4-containing atmospheres, this causes rapid carburization in the form of precipitation of coarse carbides on the surface and in the bulk. Carburization was shown to induce an extensive embrittlement of the alloys. In CH4-free helium mixtures, alloys decarburize with a global loss of carbon and dissolution of the pre-existing carbides. As carbides take part in the alloy strengthening at high temperature, it is expected that decarburization impacts the creep properties. Carburization and

  7. L'introduction des composés oxygénés dans le raffinage : impact et stratégies The Introduction of Oxygenated Compounds in Refining: Impact and Strategies

    Directory of Open Access Journals (Sweden)

    Valais M.

    2006-11-01

    Full Text Available L'addition de composés oxygénés dans les carburants est appelée à se développer dans de nombreux pays. Après les Etats-Unis, le Brésil et la République Fédérale d'Allemagne, la France vient d'autoriser (arrêté du 4 octobre 1983 l'addition de méthanol, éthanol, butanols et méthyl tertio butyl éther dans les carburants. Toutefois cette addition est limitée à des valeurs faibles, de 5 à 10 % en volume, dans le but de maintenir les performances des véhicules du parc actuel. Les résultats présentés ici s'appuient sur une étude de modélisation du raffinage visant à appréhender les différents impacts techniques et économiques de l'addition de ces composés oxygénés dans différents types de raffineries. Cette étude montre que l'intérêt de l'addition de chaque composé oxygéné dépend fortement du type de raffinerie considéré, des conditions d'éthylation, de son taux de p-nétration dans le pool des carburants et de son coût d'accès pour le raffineur. The addition of oxygenated compounds to motor fuels is foreseen to develop in numerous countries. After the United States, Brazil and West Germany, France has just authorized (order of October 4, 1983 the addition of methanol, ethanol, butanols and methyltertiobutylether to fuels. However, this addition is limited to small amounts of 5 to 10% by volume in order to maintain the performances of vehicles now in use. The results described here are based on a computer modeling survey of refining, with the aim of assessing the technical and economic impacts that will result from the addition of such oxygenated compounds in gasoline on different types of refineries. This survey shows that the advantage of adding each oxygenated compound depends greatly on the type of refinery considered, on ethylation conditions, on its rate of penetration in the gasoline pool and on its overall cost for the refiners.

  8. Etude expérimentale du cliquetis à haut régime Experimental Study of Hight-Speed Knocking

    Directory of Open Access Journals (Sweden)

    Guibet J. C.

    2006-11-01

    Full Text Available La première partie de cette étude a consisté à observer et à tenter d'interpréter l'action des conditions de fonctionnement et des paramètres de réglage du moteur sur la tendance au cliquetis à haut régime. On a montré ensuite que les différentes familles chimiques d'hydrocarbures qui constituent les carburants classiques présentent chacune un comportement bien distinct en fonction de la richesse, de la pression et de la température d'admission. On a également étudié l'influence de la teneur en plomb du carburant et du type d'alkyle de plomb employé. Quelques expériences ont été effectuées afin de déterminer l'incidence d'une réduction de un point de taux de compression sur l'exigence en octane à haut régime et sur l'action des caractéristiques de composition du carburant. Enfin, en déterminant le pourcentage de cycles soumis au cliquetis pour différentes avances à l'allumage, il a été possible de fournir quelques indications permettant de mieux caractériser l'intensité du phénomène. The first part of this study consists in observing and trying to interpret the effect of operating conditions and engine tuning parameters on the tendency for high-speed knocking to appear. The different chemical families of the hydrocarbons making up conventional fuels are shown to each have a quite different behavior depending on the fuel-air equivalency ratio and the admission pressure and temperature. The influence of the lead content in the fuel and of the type of lead alkyl used is also studied. Some experiments were performed to determine the influence of a one-point reduction in the compression ratio on the high-speed octane requirement and on the effect of fuel composition properties. Lastly, by determing the percentage of cycles accompanied by knocking at different spark advances, some indications were found for better characterizing the intensity of the phenomenon.

  9. Alimentation des moteurs en mélange homogène pauvre Feeding Homogeneous Lean Mixtures to Engines

    Directory of Open Access Journals (Sweden)

    Rayna B.

    2006-11-01

    Full Text Available Les études effectuées dans le cadre de plusieurs conventions de recherche entre l'Institut de Recherche des Transports (IRT et l'Institut Français du Pétrole (IFP associé à d'autres organismes industriels (Régie Nationale des Usines Renault (RNUR, Solex... ont permis a de caractériser l'influence de la préparation physique du mélange air-carburant sur le fonctionnement de moteurs monocylindre et multicylindre. L'effet sur le rendement d'inégalités de richesse entre les cylindres a été estimé à l'aide d'un modèle mathématique de simulation du moteur à allumage commandé ; b d'analyser les défauts inhérents à certains systèmes d'alimentation actuels et d'expérimenter des techniques différentes de formation du mélange carburé (car-burateur à dépression constante, pulvérisation pneumatique du carburant. Les résultats obtenus ont montré notamment que des améliorations ne peuvent résulter que d'un aménagement d'ensemble de tous les éléments du circuit d'admission Investigations carried out under thé terms of several research agreements involving Institut de Recherche des Transports (IRT and Institut Français du Pétrole (IFP associated with other industrial organizations (Régie Nationale des Usines Renault (RNUR, Solex served ta a Characterize thé influence of thé physical preparation of thé air/fuel mixture on thé operating of single-cylinder and multicylinder engines. The effect on thé efficiency of unequal air/fuel ratios among thé cylindres was evaluated by a mathematical model used ta simulate a spark-ignition engine. b Analyze thé inhérent defects of some fuel-supply systems now used and ta experiment with différent techniques of mixture preparation (constant depression car-burettor, pneumatic fuel spraying. The results obtained show, in particulor, that improvements con be produced only by redesigning all thé parts of thé fuel-supply circuit.

  10. BIOCARBURANTS PSA Peugeot Citroën et les biocarburants

    Directory of Open Access Journals (Sweden)

    Maurer Béatrice

    2002-09-01

    Full Text Available Les biocarburants représentent une filière essentielle pour PSA Peugeot Citroën dans le cadre de la protection de l’environnement, un axe stratégique majeur pour le groupe - de la production de ses véhicules au recyclage, de la qualité de l’air à l’effet de serre et au développement d’énergies renouvelables. Depuis plusieurs années, PSA a intégré la filière huiles végétales/biocarburants dans ses activités pour atteindre ses objectifs globaux d’innovation et de croissance. De nombreuses flottes de véhicules circulent en France avec du gazole contenant 30 % de biocarburant issu des oléagineux : une expérience réussie, qui dure depuis plus de dix ans. Le constructeur est favorable à l’utilisation de biocarburants en mélange dans les carburants pétroliers conventionnels, essence et gazole - une voie qui présente plusieurs avantages : * Un bilan CO2 global favorable (par absorption de CO2 lors de la photosynthèse de la plante-source, qui contribue à limiter « l’effet de serre ». * Une source complémentaire de carburant pour réduire les importations de pétrole (et de gazole. * Un soutien au secteur agricole (débouché supplémentaire, dans le cadre de la valorisation des terres en jachère. Issus de la transformation des céréales ou de la betterave à sucre, ou des plantes oléagineuses comme le colza, le tournesol ou le soja, les biocarburants sont par essence des énergies renouvelables. Outre leur bilan exceptionnellement favorable pour lutter contre l’effet de serre, ces carburants offrent de réelles performances environnementales, en particulier par la réduction des émissions de particules (cas des EMHV.

  11. Compatibility studies on stainless steel type 347 in liquid sodium using a thermal convection loop

    International Nuclear Information System (INIS)

    The corrosion of type 347 stainless steel in flowing liquid sodium was studied in a thermal convection loop fabricated out of type 347 s.s. tubes. Tensile samples of 347 s.s. with various heat-treatment and fabrication histories were located throughout the length of the loop. The average temperatures of the hot and cold legs were respectively 400 and 3000C, and the velocity of sodium was calculated to be about 19 cm/sec. The loop was operated for 8061 hours, after which period it was dismantled for evaluation of the corrosion attack on the specimens as well as on the tubing of the loop. Metallographic examination of the specimens from the hot leg revealed the formation of a ferrite layer up to a thickness of 8 μm. Extensive grain boundary attack and carburization was observed on the specimens from the cold leg. The changes in the tensile properties of the specimens were evaluated. (orig.)

  12. Evaporation behaviour of the ternary uranium plutonium carbides

    International Nuclear Information System (INIS)

    The evaporation behaviour of uranium plutonium carbides (Usub(0.80)Psub(0.20)Csub(1+-x) was studied by a combined application of mass spectrometry, using the uranium isotope U-233, and the Knudsen effusion target collection technique in the temperature range from 15000C to the liquids temperature measured at 24580C and the composition range from C/M = 0.95 to 1.4. High temperature compatibility tests were made with W-cells, carburized Ta and TaC-liners up to 25000C. The influence of oxygen and nitrogen impurities on vapour pressure, and composition changes in continued evaporation of the the mixed carbides were investigated. The effects of plutonium depletion and segregation were studied. (Auth.)

  13. Principes et application de la digestion anaérobie pour la production d'énergie

    OpenAIRE

    Bernet, Nicolas

    2015-01-01

    La digestion anaérobie est un processus naturel par lequel la matière organique est transformée en un biogaz qui contient environ 2/3 de méthane et 1/3 de dioxyde de carbone. Elle résulte de l’activité d’un écosystème microbien anaérobie complexe. Le biogaz est une source d’énergie qui peut être utilisée directement en remplacement du gaz naturel, pour produire de la chaleur et de l’électricité par cogénération ou encore comme carburant pour véhicules. Ainsi, la domestication par l’homme de c...

  14. Improved adherence of sputtered titanium carbide coatings on nickel- and titanium-base alloys

    Science.gov (United States)

    Wheeler, D. R.; Brainard, W. A.

    1979-01-01

    Rene 41 and Ti-6Al-4V alloys were radio frequency sputter coated with titanium carbide by several techniques in order to determine the most effective. Coatings were evaluated in pin-on-disk tests. Surface analysis by X-ray photoelectron spectroscopy was used to relate adherence to interfacial chemistry. For Rene 41, good coating adherence was obtained when a small amount of acetylene was added to the sputtering plasma. The acetylene carburized the alloy surface and resulted in better bonding to the TiC coating. For Ti-6Al-4V, the best adherence and wear protection was obtained when a pure titanium interlayer was used between the coating and the alloy. The interlayer is thought to prevent the formation of a brittle, fracture-prone, aluminum oxide layer.

  15. Development of a Composite Technique for Preconditioning of 41Cr4 Steel Used as Gear Material: Examination of Its Microstructural Characteristics and Properties

    Directory of Open Access Journals (Sweden)

    Jianjun Hu

    2016-01-01

    Full Text Available Commercial 41Cr4 (ISO standard steel was treated by a composite technique. An intermediate layer was introduced firstly at the 41Cr4 steel surface by traditional carburizing and nitriding. Then a hard Cr coating was brush-plated on the intermediate layer. Finally, the coating layer was modified by high current pulsed electron beam (HCPEB, followed by quenching and subsequent tempering treatment. The microstructure, mechanical properties, and fracture behavior were characterized. The results show that a nanocrystalline Cr coating is formed at the 41Cr4 steel surface by the treatment of the new composite technique. Such nanocrystalline Cr coating has acceptable hardness and high corrosion resistance performance, which satisfies the demands of the gears working under high speed and corrosive environment. The composite process proposed in this study is considered as a new prospect method due to the multifunction layer design on the gear surface.

  16. An Experimental Study of Fretting of Gear Teeth

    Science.gov (United States)

    Krantz, Timothy L.

    2008-01-01

    Experiments were conducted to study fretting of gears. The gears were made from case-carburized AISI 9310 alloy to match the material of a flight actuator gearbox of interest. The objective of the testing was to produce damage representative of that observed on flight hardware. The following correlations and observations were noted. The amplitude of dithering motion very strongly influenced the type and magnitude of damage. Sliding amounts on the order of 30% of the width of the line contact were judged to most readily produce fretting damage. There was observed an incubation period on the order of tens-of-thousands of cycles, and the incubation period was influenced by surface roughness, torque, and the motion extent. Fretting damage could be produced for any of the torques tested, and the severity of damage increased slightly with torque. Gear teeth having surface roughness of 0.7-0.8 micrometer were somewhat more resistant to fretting than were smoother surfaces.

  17. Effect of Plastic Pre-straining on Residual Stress and Composition Profiles in Low-Temperature Surface-Hardened Austenitic Stainless Steel

    Science.gov (United States)

    Bottoli, Federico; Christiansen, Thomas L.; Winther, Grethe; Somers, Marcel A. J.

    2016-08-01

    The present work deals with the evaluation of the residual stress profiles in expanded austenite by applying grazing incidence X-ray diffraction (GI-XRD) combined with successive sublayer removal. Annealed and deformed ( ɛ eq=0.5) samples of stable stainless steel EN 1.4369 were nitrided or nitrocarburized. The residual stress profiles resulting from the thermochemical low-temperature surface treatment were measured. The results indicate high-residual compressive stresses of several GPa's in the nitrided region, while lower-compressive stresses are produced in the carburized case. Plastic deformation in the steel prior to thermochemical treatment has a hardly measurable influence on the nitrogen-rich zone, while it has a measurable effect on the stresses and depth of the carbon-rich zone.

  18. Impact of the chemical description on direct numerical simulations and large eddy simulations of turbulent combustion in industrial aero-engines

    OpenAIRE

    Franzelli, Benedetta Giulia

    2011-01-01

    Le développement de nouvelles technologies pour le transport aérien moins polluant est de plus en plus basé sur la simulation numérique, qui nécessite alors une description fiable de la chimie. Pour la plupart des carburants, la description de la combustion nécessite des mécanismes détaillés mais leur utilisation dans une simulation numérique de combustion turbulente est limitée par le coût calcul. Des mécanismes cinétiques réduits et des méthodes de tabulation ont été proposés pour surmonter...

  19. Testing of heating and cooling process of ADI cast iron with use of ATND method

    Directory of Open Access Journals (Sweden)

    A. Białobrzeski

    2008-10-01

    Full Text Available ADI (Austempered Ductile Iron cast iron, owing to its unique combination of high tensile strength and abrasion resistance with very goodplasticity, founds implementation in many branches of industry as a substitute of alloy cast steel and carburized or heat treated steels. Inspite of its solid position among producers and recipients of castings, there are still undertaken studies aimed at perfection of its propertiesand recognition of mechanisms enabling obtaining such properties.The paper presents implementation of thermal-voltage-derivative (ATND method to registration of heating and cooling course of ADIcast iron with EN-GJS-1200-2 grade. ADI cast iron with EN-GJS-1200-2 grade underwent the study. Heat treatment of the cast iron wasperformed in Foundry Institute with use of LT ADI-350/1000 processing line. Results obtained from the testing illustrate in graphic formregistered heating and cooling curves of investigated cast irons obtained with use of the ATND method.

  20. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    International Nuclear Information System (INIS)

    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB2, silicon carbide SiC and zirconium oxide ZrO2) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms

  1. L'acceptabilité potentielle des voitures électriques : Quelle profitabilité financière pour l'usager privé en Ile-de-France?

    OpenAIRE

    WINDISCH, Elisabeth; Leurent, Fabien

    2012-01-01

    International audience Depuis quelques années, le véhicule électrique (VE) suscite un très important regain d'intérêt, au titre de divers enjeux d'ordre aussi bien écologique (qualité de l'air, bruit, émissions de gaz à effet de serre) qu'économique, pour revitaliser l'industrie automobile et à travers elle la production économique générale, ou encor énergétique, pour réduire la dépendance aux carburants importés. C'est pourquoi les pouvoirs publics promeuvent le développement de la mobili...

  2. PUBLICITE AUTOMOBILE: Impact des propositions de loi DOC 1909/001 & DOC 1910/001

    OpenAIRE

    Ozer, Pierre

    2009-01-01

    Ce rapport d'expertise réalisé à la demande de la Commission de la Santé publique, de l'Environnement et du Renouveau de la Société de la Chambre des Représentants de Belgique et présenté le 26 juin 2009 analyse la publicité automobile via [1] son impact indirect sur les émissions de CO2 du secteur transport; [2] son illégalité flagrante au regard de la Directive européenne 1999/94/CE concernant « la disponibilité d’informations sur la consommation de carburant et les émissions de CO2 à l’int...

  3. Les conditions économiques, matérielles et sociales de l'équipement des ménages en voiture électrique

    OpenAIRE

    Leurent, Fabien; SADEGHIAN, Sahdi; WINDISCH, Elisabeth

    2013-01-01

    La voiture électrique émet moins de polluants et de bruit que la voiture à carburant, et moins de gaz à effet de serre avec le mix énergétique français. Mais pour l'automobiliste, son attractivité financière nécessite un parcours annuel élevé, et ce sous la contrainte d'autonomie de la batterie. De plus le type de véhicule et l'installation de l'équipement de recharge imposent des contraintes matérielles. L'article explore les effets de ces contraintes sur la demande potentielle des ménages ...

  4. OPTIMIZATION OF HEATING OF GEAR WHEEL USING NUMERICAL MODELING

    Directory of Open Access Journals (Sweden)

    Soňa Benešová

    2013-09-01

    Full Text Available Successful heat treating and carburizing of gear wheels for wind turbine gear boxes requires that plastic deformation in the wheel is minimized. Numerical modeling using the DEFORM software was aimed at exploring the effects of the base, on which the gear wheel rests during heating, on the heating process. Homogeneous heating was assumed. It was found that the base heats up more quickly than the workpiece. It is the consequence of the base's shape and volume. As a result, the base expands and slides against the wheel, predominantly at the first heating stage. Later on, it prevents the gear wheel from expanding, causing plastic deformation in the wheel. The findings were used for designing new heating schedules to minimize these undesirable interactions and to reduce the plastic deformation to a negligible magnitude. In addition, this paper presents an example of a practical use of numerical modeling in the DEFORM software.

  5. OPTIMIZATION OF HEATING OF GEAR WHEEL USING NUMERICAL MODELING

    Directory of Open Access Journals (Sweden)

    Sona Benesova

    2013-05-01

    Full Text Available Successful heat treating and carburizing of gear wheels for wind turbine gear boxes requires that plastic deformation in the wheel is minimized. Numerical modeling using the DEFORM software was aimed at exploring the effects of the base, on which the gear wheel rests during heating, on the heating process. Homogeneous heating was assumed. It was found that the base heats up more quickly than the workpiece. It is the consequence of the base's shape and volume. As a result, the base expands and slides against the wheel, predominantly at the first heating stage. Later on, it prevents the gear wheel from expanding, causing plastic deformation in the wheel. The findings were used for designing new heating schedules to minimize these undesirable interactions and to reduce the plastic deformation to a negligible magnitude. In addition, this paper presents an example of a practical use of numerical modeling in the DEFORM software.

  6. Méthodes d’optimisation dynamique de systèmes à plusieurs états pour l'efficacité énergétique automobile

    OpenAIRE

    Maamria, Djamaleddine

    2015-01-01

    La gestion énergétique (EMS) pour véhicules hybrides a pour objectif de déterminer la répartition de puissance entre les différentes sources d'énergie de manière à minimiser la consommation de carburant et/ou les émissions polluantes. L'objectif de cette thèse est de développer un EMS en prenant en compte des températures internes (la température du moteur et/ou la température du système de post-traitement). Dans une première partie et en utilisant une connaissance préalable du cycle de condu...

  7. .sup.100Mo compounds as accelerator targets for production of .sup.99mTc

    Energy Technology Data Exchange (ETDEWEB)

    Richards, Vernal; Lapi, Suzanne

    2016-09-20

    Methods of synthesizing .sup.100Mo.sub.2C and .sup.99mTcO.sub.4.sup.- are disclosed. Methods of .sup.100Mo.sub.2C generation involve thermally carburizing .sup.100MoO.sub.3. Methods of .sup.99mTcO.sub.4 generation involve proton bombardment of .sup.100Mo.sub.2C in a cyclotron. Yields of .sup.99mTcO.sub.4 can be increased by sintering .sup.100Mo.sub.2C prior to bombardment. The methods also include recycling of .sup.100Mo.sub.2C to form .sup.100MoO.sub.3. SPECT images obtained using .sup.99mTcO.sub.4 generated by the disclosed methods are also presented.

  8. Heat treatment process optimization for face gearsbased on deformation and residual stress control

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-zhong; LAN Zhou‡; HOU Liang-wei; ZHAO Hong-pu; ZHONG Yang

    2015-01-01

    In this paper, based on the principle of heat transfer and thermal elastic-plastic theory, the heat treatment process optimization scheme for face gearsis proposed according to the structural characteristics oftheface gear and material properties of 12Cr2Ni4 steel.To simulate the effect of carburizing and quenching process on tooth deformation and residual stress distribution,aheat treatment analysis model of face gearsis established, and the microstructure, stress and deformation of face gear teeth changing with time are analyzed. The simulation results show that face gear tooth hardness increases, tooth surface residual compressive stress increases and tooth deformation decreases after heat treatment process optimization.It is beneficialto improvingthe fatigue strength and performance of face gears.

  9. Visualizing In Situ Microstructure Dependent Crack Tip Stress Distribution in IN-617 Using Nano-mechanical Raman Spectroscopy

    Science.gov (United States)

    Zhang, Yang; Mohanty, Debapriya P.; Tomar, Vikas

    2016-09-01

    Inconel 617 (IN-617) is a solid solution alloy, which is widely used in applications that require high-temperature component operation due to its high-temperature stability and strength as well as strong resistance to oxidation and carburization. The current work focuses on in situ measurements of stress distribution under 3-point bending at elevated temperature in IN-617. A nanomechanical Raman spectroscopy measurement platform was designed and built based on a combination of a customized open Raman spectroscopy (NMRS) system incorporating a motorized scanning and imaging system with a nanomechanical loading platform. Based on the scanning of the crack tip notch area using the NMRS notch tip, stress distribution under applied load with micron-scale resolution for analyzed microstructures is predicted. A finite element method-based formulation to predict crack tip stresses is presented and validated using the presented experimental data.

  10. High temperature oxidation and corrosion behavior of Ni-base superalloy in He environment

    International Nuclear Information System (INIS)

    Ni-base superalloy is considered as a IHX (Intermediate Heat Exchanger) material for VHTR (Very High Temperature Gas-Cooled Reactor). The helium environment in VHTR contains small amounts of impure gases, which cause oxidation, carburization, and decarburization. In this report, we conducted the literature survey about the high temperature behavior of Ni-base superalloys in air and He environments. The basic information of Ni-base superalloy and the basic metal-oxidation theory were briefly stated. The He effect on the corrosion of Ni-base superalloy was also summarized. This works would provide a brief suggestion for the next research topic for the application of Ni-base superalloy to VHTR

  11. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    Energy Technology Data Exchange (ETDEWEB)

    Bashchenko, Lyudmila P., E-mail: luda.baschenko@gmail.com; Gromov, Viktor E., E-mail: gromov@physics.sibsiu.ru; Budovskikh, Evgenii A., E-mail: budovskih-ea@physics.sibsiu.ru; Soskova, Nina A., E-mail: gromov@physics.sibsiu.ru [Siberian State Industrial University, Novokuznetsk, 654007 (Russian Federation); Ivanov, Yurii F., E-mail: yufi55@mail.ru [Institute of High Current Electronics SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB{sub 2}, silicon carbide SiC and zirconium oxide ZrO{sub 2}) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms.

  12. Synthesis of WC-Co nanocomposites using polymer as carbon source

    International Nuclear Information System (INIS)

    Ceramic-metal composites such as WC-Co are attractive for cutting-tool applications as they have high hardness, chemical inertness and resistance to heat. The properties and performance of these composites can be enhanced by keeping the size of the components on a manometer scale. Synthesis of WC-Co nanocomposites generally involves gas-phase carburization. The authors have developed a novel approach in which a polymer precursor such as polyacrylonitrile serves as an in situ source for carbon. The WC-Co nanocomposites formed are characterized by x-ray diffraction and electron microscopy. The synthesis and processing conditions such as firing temperature, time and atmosphere play a critical role in obtaining phase-pure products

  13. Metal corrosion in a supercritical carbon dioxide - liquid sodium power cycle.

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Robert Charles; Conboy, Thomas M.

    2012-02-01

    A liquid sodium cooled fast reactor coupled to a supercritical carbon dioxide Brayton power cycle is a promising combination for the next generation nuclear power production process. For optimum efficiency, a microchannel heat exchanger, constructed by diffusion bonding, can be used for heat transfer from the liquid sodium reactor coolant to the supercritical carbon dioxide. In this work, we have reviewed the literature on corrosion of metals in liquid sodium and carbon dioxide. The main conclusions are (1) pure, dry CO{sub 2} is virtually inert but can be highly corrosive in the presence of even ppm concentrations of water, (2) carburization and decarburization are very significant mechanism for corrosion in liquid sodium especially at high temperature and the mechanism is not well understood, and (3) very little information could be located on corrosion of diffusion bonded metals. Significantly more research is needed in all of these areas.

  14. Modernization and efficiency of heat treatment and heating up plants; Modernisierung und Effizienz von Thermoprozessanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, Peter [LOI Thermprocess GmbH, Essen (Germany); Kuehn, Friedhelm [Ingenieurbuero fuer Waermebehandlung, Industrieoefen und Energieberatung, Muelheim (Germany)

    2010-10-15

    A goal of this contribution is to show, using examples of the thermal heat treatment industry and the thermal processing units used there (Beltype plants, routary hearth, walking hearth, walking beam, pusher type furnaces and gas carburizing plants as well as case hardening plants), which increases in efficiency within and outside of the actual thermal treatment process and the necessary thermal processing units for the order are available today. From the possibilities of the reduction of energy employment resulting from that, a high potential for the discharge of the environment can be derived. The economic effect concerning energy employment and saving possibilities will also be considered. Concluding, examples of case-hardening show which variants of a change of process present themselves partially in the future, in order to achieve substantial production increases and thus energy cost reductions. (orig.)

  15. Determination of minimum admissible thickness of corrosion-resistant coating of nuclear power plant vessels

    International Nuclear Information System (INIS)

    The effect of technological heatings and treatments of the 22K+08Kh18N10T bimetal on diffusion of alloying elements is investigated. The results of investigation are given. Investigations have been carried out in order to determine the minimum admissible thickness of the clad layer of the bimetal produced by explosion welding. It is established that the clad layer with thickness of 3 mm in the two-layer steel, produced by explosion welding, provides the protection of internal surface of the vessel against corrosion. During the production of steam separator for the Chernobylskaya NPS the high technological effectiveness of the bimetal has been found out. Bimetal structure investigation has shown that the thickness of non-carburized austenitic layer in the articles constitutes 1.2 mm. Investigations of Cr and Ni diffusion have shown that these elements diffuse at the depth of 15-2O μm

  16. Preparation and electrocatalytic properties of tungsten carbide electrocatalysts

    Institute of Scientific and Technical Information of China (English)

    马淳安; 张文魁; 成旦红; 周邦新

    2002-01-01

    The tungsten carbide(WC) electrocatalysts with definite phase components and high specific surface area were prepared by gas-solid reduction method. The crystal structure, phase components and electrochemical properties of the as-prepared materials were characterized by XRD, BET(Brunauer Emmett and Teller Procedure) and electrochemical test techniques. It is shown that the tungsten carbide catalysts with definite phase components can be obtained by controlling the carburizing conditions including temperature, gas flowing rate and duration time. The electrocatalysts with the major phase of W2C show higher electrocatalytic activity for the hydrogen evolution reaction. The electrocatalysts with the major phase of WC are suitable to be used as the anodic electrocatalyst for hydrogen anodic oxidation, which exhibit higher hydrogen anodic oxidation electrocatalytic properties in HCl solutions.

  17. Studies on development of new functional natural materials from agricultural products - Technology developments for ceramic powders and materials from rice phytoliths

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Dae Kap; Kim, Yong Ik [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Yoon, Nang Kyu; Seong, Seo Yong [Myongseong Ceramics Com., Taejon (Korea, Republic of); Ryu, Sang Eun [Bae Jae Univ., Taejon (Korea, Republic of); Lee, Jae Chun [Myungji Univ., Seoul (Korea, Republic of)

    1995-08-01

    Based on an estimation of annual rice production of 5.2 million tons, rice husks by-production reaches to 1.17 million tons per year in Korea. Distinguished to other corns, rice contains a lot of Si; 10-20% by weight in rice husks calculated as silica. The aim of this research project is to develop technologies for ceramic powders and materials utilizing the silica in rice husks called phytoliths. In this first year research, researches of the following subjects were performed; material properties of rice husks, milling of rice husks, acid treatments, oxidations at low and high temperatures, sintering and crystalization of amorphous silica, low temperature carburization, formation of silicon carbide whiskers, and brick lightening method using milled rice husks. 11 tabs., 49 figs., 75 refs. (Author).

  18. Substrate Strengthening of CVD Coated Steels

    Institute of Scientific and Technical Information of China (English)

    O.Kessler; M.Heidkamp; F.Hoffmann; P.Mayr

    2004-01-01

    Properties of components and tools can be improved by the combination of coating and heat treatment processes due to the addition of single process advantages and due to the utilization of process interactions. Several low and high alloyed, structural and tool steels (AISI 4140, 52100, H13, A2, D2, etc.) have been treated by CVD-TiN-coating plus laser beam hardening respectively carburizing plus CVD-TiN-coating. Homogeneous, dense TiN-coatings with high hardness,high compressive residual stresses and good adhesion were supported by high strength substrate surfaces. Especially CVD plus laser beam hardening offers the possibility to reduce distortion due to the small heated surface volume.

  19. Carbon Nanomaterials: Surface Structure and Morphology

    Science.gov (United States)

    Mansurov, Z. A.; Shabanova, T. A.; Mofa, N. N.; Glagolev, V. A.

    2014-09-01

    We propose a classification of individual nanoparticles on the basis of the form of the surface and the internal architectural packing for investigations carried out with the help of transmission electron microscopy. The investigated samples contain individual nanoparticles of seven kinds in different ratios: rounded, tubular, fibrous, fi lm, "veil," "active" particles and "particles with regular geometric contours." The classification was made on the basis of an analysis of the results of investigations of the surfaces and internal architectural packing of carbon particles obtained in different physiochemical processes (carbonization, carburizing, arc discharge, mechanochemical treatment, plasma chemistry, and in carbon-containing fl ames). For the source materials, we used waste of farming products and widely distributed mineral raw materials.

  20. Pollution provoquée par le moteur Diesel. Niveaux d'émission. Comparaison avec le moteur à allumage commandé Pollution Caused by Diesel Engines. Emission Levels. Comparison with Spark-Ignition Engines

    Directory of Open Access Journals (Sweden)

    Degobert P.

    2006-11-01

    Full Text Available A partir de l'analyse des différences de modes de combustion allumage commandé et Diesel , cet article compare et explique la nature et les niveaux des différents polluants émis en fonction de leurs mécanismes de formation. Les facteurs d'action au niveau moteur sont examinés, ainsi que l'influence du carburant utilisé. Based on an analysis of the difference between spark-ignition and diesel combustion modes, this article compares and explains the nature and levels of different pollutants emitted as a function of their formation mechanisms. The action factors at the engine> level are examined together with the influence of the fuel used.

  1. Syntheses and growth mechanisms of 3C-SiC nanostructures from carbon and silicon powders.

    Science.gov (United States)

    Zhu, J; Xiong, X; Chen, H T; Wu, X L; Zhang, W C; Chu, Paul K

    2009-11-01

    Cubic silicon carbide (3C-SiC) nanostructures such as needle- and Y-shaped nanowhiskers, smooth and pagoda-shaped nanorods are synthesized on a large scale from activated carbon and silicon powders at 1250 degrees C under atmospheric pressure. The use of ball-milled silicon powders results in the formation of nanowires and nanowhiskers, whereas non-milled silicon powders lead to nanorods together with unreacted silicon powders. Residual oxygen in the growth chamber initiates the carburization reactions which can proceed without further oxygen consumption. The size and morphology of the as-synthesized 3C-SiC nanostructures are observed to be related to the size and morphology of the starting silicon particles. An oxygen-assisted gas-solid model is proposed to explain the observed nanostructures. PMID:19908579

  2. Hardening of the surface layers of commercial pure titanium VT1-0 under combined treatment

    Science.gov (United States)

    Bashchenko, Lyudmila P.; Gromov, Viktor E.; Budovskikh, Evgenii A.; Ivanov, Yurii F.; Soskova, Nina A.

    2015-10-01

    The treatment of VT1-0 titanium samples was carried out by concentrated energy fluxes. The combined treatment included surface carburizing with the joint use of powder samples of compounds with high physical and mechanical properties (namely, titanium diboride TiB2, silicon carbide SiC and zirconium oxide ZrO2) and subsequent electron beam treatment of surface layers formed in electroexplosive treatment. The combined treatment of surface layers resulted in the multifold increase in microhardness, which reduces depending on the depth of hardening zone. After electron-beam treatment, the depth of hardening zone is increased. During electron-beam treatment, the two-layer hardening zone forms.

  3. Finite element analysis of thermal residual stresses at cemented carbide rock drill buttons with cobalt-gradient structure

    Institute of Scientific and Technical Information of China (English)

    HUANG Zi-qian; HE Yue-hui; CAI Hai-tao; XIAO Yi-feng; HUANG Bai-yun

    2008-01-01

    The aim of this study is to apply the concept of functionally graded materials (FGMs) to cemented carbides and to develop high-performance rock drill buttons.Cobalt-gradient structure was introduced to the surface zone of the buttons by carburizing process.Finite element method and XRD measurement were used to decide the distribution of thermal residual stress.Constitutive parameters were determined by constraint factor.Numerical results show that residual stresses of gradient buttons mainly concentrate in cobalt-gradient zone.There is compressive stress in the surface zone and tensile stress in the cobalt-rich zone.The maximum value of surface compressive stress is 180 MPa for WC-6Co cemented carbides.And the numerical results agree with the results of XRD measurement.

  4. STUDY ON REDUCING AND MELTING BEHAVIOR OF MILL SCALE/PETROLEUM COKE BLEND

    Directory of Open Access Journals (Sweden)

    Bruno Deves Flores

    2015-07-01

    Full Text Available Self-reducing tests were carried out under isothermal and non-isothermal condition in a muffle furnace, aiming to assess the reduction and melting of a self-reducing blend of mill scale and petroleum coke (85-15% in weight. The products obtained were analyzed by mass loss and wet analysis. Further investigations for the products from the non-isothermal condition were done by X-ray diffraction, nude eye inspection and carbon analyzer. It was observed that mass loss fraction and metallization degree are directly related and both increase with time and temperature. In the non-isothermal maximum mass loss was achieved in 8 minutes, reaching metallization degrees above 90%. It was observed that the reduction of iron oxide occurs mainly in solid state and the smelting of the samples is directly related to the iron carburization process. Thus, the use of self-reducing mixtures shows a possible way to recycle mill scale.

  5. Evaluation of carbon diffusion in heat treatment of H13 tool steel under different atmospheric conditions

    Directory of Open Access Journals (Sweden)

    Maziar Ramezani

    2015-04-01

    Full Text Available Although the cost of the heat treatment process is only a minor portion of the total production cost, it is arguably the most important and crucial stage on the determination of material quality. In the study of the carbon diffusion in H13 steel during austenitization, a series of heat treatment experiments had been conducted under different atmospheric conditions and length of treatment. Four austenitization atmospheric conditions were studied, i.e., heat treatment without atmospheric control, heat treatment with stainless steel foil wrapping, pack carburization heat treatment and vacuum heat treatment. The results showed that stainless steel foil wrapping could restrict decarburization process, resulting in a constant hardness profile as vacuum heat treatment does. However, the tempering characteristic between these two heat treatment methods is different. Results from the gas nitrided samples showed that the thickness and the hardness of the nitrided layer is independent of the carbon content in H13 steel.

  6. Insights on finite size effects in Ab-initio study of CO adsorption and dissociation on Fe 110 surface

    CERN Document Server

    Chakrabarty, Aurab; Mousseau, Normand; Becquart, Charlotte S; Mellouhi, Fadwa El

    2016-01-01

    Adsorption and dissociation of hydrocarbons on metallic surfaces represent crucial steps to carburization of metal. Here, we use density functional theory total energy calculations with the climbing-image nudged elastic band method to estimate the adsorption energies and dissociation barriers for different CO coverages with surface supercells of different sizes. For the absorption of CO, the contribution from van der Waals interaction in the computation of adsorption parameters is found important in small systems with high CO-coverages. The dissociation process involves carbon insertion into the Fe surface causing a lattice deformation that requires a larger surface system for unrestricted relaxation. We show that, in larger surface systems associated with dilute CO-coverages, the dissociation barrier is significantly decreased. The elastic deformation of the surface is generic and can potentially applicable for all similar metal-hydrocarbon reactions and therefore a dilute coverage is necessary for the simul...

  7. Internal chlorination of Ni-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Berztiss, D.; Hennesen, K.; Grabke, H.J. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    1998-12-31

    In contrast to internal oxidation, sulfidation and carburization, very little information is available regarding internal chlorination, especially diffusion of chlorine in metallic alloys. This paper describes results of experiments on Ni-Cr alloys (<10 wt% Cr) exposed in an atmosphere containing radioactive HCl. The diffusion of chlorine in the alloy can be determined by measurement of residual {beta}-activity from the sample surface. Successively thin layers (0.5-10 {mu}m) of the alloy were removed by lapping and the surface activity was measured to obtain a depth profile. Both single and polycrystalline materials were tested. Through this work it should be determined if there is in fact solubility and diffusion of chlorine in Ni-based alloys as some authors have proposed or if the ingress of chlorine is mainly a grain boundary phenomenon. (orig.)

  8. Abrasive Wear of Digger Tooth Steel

    Directory of Open Access Journals (Sweden)

    Hussein Sarhan sarhan, Nofal Al-Araji, Rateb Issa , Mohammad Alia

    2011-08-01

    Full Text Available The influence of silicon carbide SiC abrasive particles of 20, 30, 40, 50 and60μm size on carburized digger tooth steel was studied. Four types of steel, withdifferent hardness, were tested at two constant linear sliding speeds and undervarious loads of 10, 20, 30, 40 and 50N. Tests were carried out for sliding time of0.5, 1.0, 1.5, 2.0 and 2.5min. Experimental results showed that there wasconsistent reduction in abrasive wear as the hardness of the materials wasincreased. It was found that wear increased with the increase of applied load,linear sliding speed and sliding time. Also, it was noticed that the wear increasedwith increase in abrasive particle size, and the most effective size was 40 μm.SEM observations of the worm surface showed that the cutting and ploughingwere the dominant abrasive wear mechanisms.

  9. Mo2C nanowires and nanoribbons on Si by two-step vapor-phase growth

    Science.gov (United States)

    Tsakalakos, L.; Rahmane, M.; Larsen, M.; Gao, Y.; Denault, L.; Wilson, P.; Balch, J.

    2005-08-01

    Transition-metal carbides in bulk form have historically been of technological interest primarily due to their excellent mechanical and refractory properties. As electronic materials these ceramic compounds are also particularly intriguing in that their electrical resistivity is relatively low compared to other ceramics and shows metallic temperature-dependent behavior. Some compositions also have superconducting transitions temperatures above 10°K. However, the synthesis of such materials in the form of one-dimensional nanostructures, which may be of interest for various nanoelectronic applications, is relatively difficult due to their refractory nature (Tmelt⩾2000°C). Here we report the synthesis of well-defined Mo2C nanowires and ribbons using a two-step approach in which we catalytically grow metal oxide nanostructures followed by in situ carburization. The growth mechanisms, microstructure, and initial electrical property measurements are discussed.

  10. Highly dispersed molybdenum carbide as non-noble electrocatalyst for PEM fuel cells: Performance for CO electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Guil-Lopez, R.; Martinez-Huerta, M.V.; Pena, M.A.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica (CSIC), Marie Curie 2, Cantoblanco, E-28049 Madrid (Spain); Guillen-Villafuerte, O.; Pastor, E. [Departamento de Quimica Fisica, Universidad de La Laguna, Astrofisico Francisco Sanchez s/n, E-38071 La Laguna, Tenerife (Spain)

    2010-08-15

    CO electrooxidation on nanocrystalline molybdenum carbide has been studied through CO stripping measurements using cyclic voltammetry. The active molybdenum carbide was obtained from the carbothermic reduction of really very small molybdenum oxide particles supported on Vulcan XC-72 carbon black (CB). In order to obtain highly dispersed molybdenum carbide particles, low molybdenum loading and control of the carbothermic reduction conditions of CB-supported molybdenum oxide were employed to avoid Mo sintering during the carburization process. This work provides experimental evidence on the CO electrooxidation capability of the Mo carbide phase, which to the best of our knowledge is reported for the first time. The small particle size of carbide electrocatalyst exhibited better performance for CO electrooxidation than the commercial bulk molybdenum carbide sample. (author)

  11. Development of an improved method to perform single particle analysis by TIMS for nuclear safeguards.

    Science.gov (United States)

    Kraiem, M; Richter, S; Kühn, H; Aregbe, Y

    2011-02-28

    A method is described that allows measuring the isotopic composition of small uranium oxide particles (less than 1μm in diameter) for nuclear safeguards purposes. In support to the development of reliable tools for the identification of uranium and plutonium signatures in trace amounts of nuclear materials, improvements in scanning electron microscopy (SEM) and thermal ionization mass spectrometry (TIMS) in combination with filament carburization and multiple ion counting (MIC) detection were investigated. The method that has been set up enables the analysis of single particles by a combination of analytical tools, thus yielding morphological, elemental and isotopic information. Hereby individual particles of certified reference materials (CRMs) containing uranium at femtogram levels were analysed. The results showed that the combination of techniques proposed in this work is suitable for the accurate determination of uranium isotope ratios in single particles with improved capabilities for the minor abundant isotopes. PMID:21296200

  12. Studies on development of new functional natural materials from agricultural products - Technology developments for ceramic powders and materials from rice phytoliths

    International Nuclear Information System (INIS)

    Based on an estimation of annual rice production of 5.2 million tons, rice husks by-production reaches to 1.17 million tons per year in Korea. Distinguished to other corns, rice contains a lot of Si; 10-20% by weight in rice husks calculated as silica. The aim of this research project is to develop technologies for ceramic powders and materials utilizing the silica in rice husks called phytoliths. In this first year research, researches of the following subjects were performed; material properties of rice husks, milling of rice husks, acid treatments, oxidations at low and high temperatures, sintering and crystalization of amorphous silica, low temperature carburization, formation of silicon carbide whiskers, and brick lightening method using milled rice husks. 11 tabs., 49 figs., 75 refs. (Author)

  13. Conversion chimique du gaz naturel Chemical Conversion of Natural Gas

    OpenAIRE

    Chaumette P.

    2006-01-01

    Dans cet article sont passés en revue les travaux de recherche et développement et les procédés existants dans le domaine de la conversion chimique du gaz naturel. Les deux voies possibles, conversion directe du méthane et conversion indirecte, via le gaz de synthèse, sont présentées. Tant la préparation d'hydrocarbures utilisables comme carburants, que celle des composés de bases pour la pétrochimie ou la chimie sont évoquées. L'accent est mis sur l'étape clé du développement de chaque procé...

  14. Fatigue behaviour and fracture mechanism of cryogenically treated En 353 steel

    International Nuclear Information System (INIS)

    An experimental investigation was conducted for a better understanding of fatigue and fracture behaviour of carburized steel used in the manufacture of vehicle transmission elements such as crown wheel and pinion. An attempt was made to study the fatigue strength of En 353 based on failure at 107 cycles after subjecting to three different treatments namely conventional heat treatment, shallow cryogenic treatment and deep cryogenic treatment. Rotating bending fatigue test was performed in air at room temperature for all specimens. Fractured specimen surfaces were examined by scanning electron microscope to identify the mechanism involved during fatigue. The study concludes that shallow and deep cryogenically treated samples show an improvement with an overall fatigue life of 71% and a reduction of 26% over conventionally heat treated samples respectively. The combined presence of retained austenite and fine carbides has resulted in enhanced fatigue strength of shallow cryogenically treated specimens over the conventionally heat treated and deep cryogenically treated specimens.

  15. Spectroscopic signatures of an ordered array of independent Ag heptamers

    International Nuclear Information System (INIS)

    A periodic network of Ag heptamers forms on the carburized W(1 1 0)-R(15 × 12) surface, upon deposition of sub-monolayer amounts of Ag. We investigate the electronic structure and dimensionality of this system by angle-resolved photoemission spectroscopy. The observation of very well-defined Ag 4d-levels confirms the highly ordered growth of size-selected Ag nano-particles on the W(1 1 0)-R(15 × 12) template. The absence of energy dispersion of these states indicates negligible coupling among the Ag heptamers, and points out the local character of the heptamer–substrate interaction. The system can be described as an array of Ag heptamers with fully confined Ag 4d-levels. (paper)

  16. Étude et mise en œuvre de couplage thermoélectrique en vue de l'intensification d'échange de chaleur par morphing électroactif

    OpenAIRE

    Amokrane, Mounir

    2013-01-01

    Le développement et l’utilisation de nouveaux matériaux, tel que le carbure de silicium (SiC) et le nitrure de gallium (GaN), a permis un accroissement sensible des densités d’énergie traitées par les nouveaux composants de l’électronique de puissance, assortie d’une augmentation de leur compacité. Parallèlement à ces progrès technologiques, la généralisation de l’électricité en tant que vecteur d’énergie primaire au sein de systèmes de plus en plus répartis, incluant des moyens de traitemen...

  17. Soudage par explosion thermique sous charge de cermets poreux à base de TiC-Ni sur substrat en acier-comportement tribologique Welding of porous TiC–Ni based cermets on substrate steel by thermal explosion under load-tribological behaviour

    OpenAIRE

    Lemboub Samia; Boudebane Said; Atoui L'hadi

    2013-01-01

    Dans ce travail, nous nous intéressons à l'élaboration de cermets à base de TiC-Ni par dispersion de particules de carbures, oxydes ou borures dans une matrice de nickel, grâce à la technique de l'explosion thermique sous une charge de 20 MPa. La combustion de mélanges actifs (Ti-C-Ni-An où An = Al2O3, MgO, SiC, TiB2, WC), basée sur la réaction de synthèse de TiC (ΔHf298K = −184 kJ/mole), génère des cermets complexes. Un court maintien sous charge du cermet à 1373 K, après l'explosion thermiq...

  18. Nanocrystalline, superhard, ductile ceramic coatings for roller-cone bit bearings

    Energy Technology Data Exchange (ETDEWEB)

    Namavar, F.; Colter, P.; Karimy, H. [Spire Corp., Bedford, MA (United States)] [and others

    1997-12-31

    The established method for construction of roller bits utilizes carburized steel, frequently with inserted metal bearing surfaces. This construction provides the necessary surface hardness while maintaining other desirable properties in the core. Protective coatings are a logical development where enhanced hardness, wear resistance, corrosion resistance, and surface properties are required. The wear properties of geothermal roller-cone bit bearings could be further improved by application of protective ceramic hard coatings consisting of nanometer-sized crystallites. Nanocrystalline protective coatings provide the required combination of hardness and toughness which has not been available thus far using traditional ceramics having larger grains. Increased durability of roller-cone bit bearings will ultimately reduce the cost of drilling geothermal wells through increased durability.

  19. Finishing aeronautical planetary herringbone gear wheels in container vibrating smoothing machine

    Directory of Open Access Journals (Sweden)

    Jacek MICHALSKI

    2015-12-01

    Full Text Available The paper presents the technological process of abrasive-chemical machining wheel bearing surface of the cylindrical herringbone gears planetary gear in vibrating container smoothing machine according to Isotropic Finishing ISF® technology of the REM Chemicals Inc. company. Gear wheels are made of stainless Pyrowear 53 and subjected to carburizing, hardening, cold working and low tempering. The change in value of deviation indicators for the kinematic accuracy, smoothness and geometric structure of the machined surfaces of the gear teeth after smoothing compared with the contoured grinding were analyzed. The findings are different a characteristic performance on the surface of the tooth side along the outline, especially with a higher value at the head of the tooths. This creates a need for appropriate modification of the lateral surface of the teeth in the process of contoured grinding. The results of the mechanical strength of the samples gear wheel after the smoothing process and evaluating the hydrogen embrittlement are presented.

  20. Method of synthesizing bulk transition metal carbide, nitride and phosphide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae Soon; Armstrong, Beth L; Schwartz, Viviane

    2015-04-21

    A method for synthesizing catalyst beads of bulk transmission metal carbides, nitrides and phosphides is provided. The method includes providing an aqueous suspension of transition metal oxide particles in a gel forming base, dropping the suspension into an aqueous solution to form a gel bead matrix, heating the bead to remove the binder, and carburizing, nitriding or phosphiding the bead to form a transition metal carbide, nitride, or phosphide catalyst bead. The method can be tuned for control of porosity, mechanical strength, and dopant content of the beads. The produced catalyst beads are catalytically active, mechanically robust, and suitable for packed-bed reactor applications. The produced catalyst beads are suitable for biomass conversion, petrochemistry, petroleum refining, electrocatalysis, and other applications.

  1. Self-assembly of noble metal monolayers on transition metal carbide nanoparticle catalysts.

    Science.gov (United States)

    Hunt, Sean T; Milina, Maria; Alba-Rubio, Ana C; Hendon, Christopher H; Dumesic, James A; Román-Leshkov, Yuriy

    2016-05-20

    We demonstrated the self-assembly of transition metal carbide nanoparticles coated with atomically thin noble metal monolayers by carburizing mixtures of noble metal salts and transition metal oxides encapsulated in removable silica templates. This approach allows for control of the final core-shell architecture, including particle size, monolayer coverage, and heterometallic composition. Carbon-supported Ti(0.1)W(0.9)C nanoparticles coated with Pt or bimetallic PtRu monolayers exhibited enhanced resistance to sintering and CO poisoning, achieving an order of magnitude increase in specific activity over commercial catalysts for methanol electrooxidation after 10,000 cycles. These core-shell materials provide a new direction to reduce the loading, enhance the activity, and increase the stability of noble metal catalysts.

  2. A Cooperative Activity on Quenching Process Simulation--- Japanese IMS-VHT Project on the Benchmark Analysis and Experiment ---

    Institute of Scientific and Technical Information of China (English)

    Tatsuo Inoue; Youichi Watanabe; Kazuo Okamura; Michiharu Narazaki; Hayato Shichino; Dong-Ying Ju; Hideo Kanamori; Katsumi Ichitani

    2004-01-01

    Japanese IMS-VHT project on the Virtual Heat Treatment tool for monitoring and optimising HT process in relation with the international cooperative programs is briefly introduced. This project motivates to develop virtual tools for computer to optimize the heat treatment condition and to support decision for HT operation by knowledge based database in addition to process simulation. As one of the activities with the cooperation of the Society of Materials Science, Japan and the Japan Society for Heat Treatment, a benchmark project is undergoing. This includes simulation of carburized quenching process of a cylinder, disc, and ring as well as a helical gear by use of common data of materials properties and cooling characteristics by several available simulation programs. A part of the newly obtained results is presented as an interim report.

  3. A state-of-the-art-report on the compatibility of structural materials with sodium

    Energy Technology Data Exchange (ETDEWEB)

    Maeng, Wan Yung; Joo, Kee Nam; Ryoo, Woo Suk; Kang, Yung Hwan [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1993-12-01

    Compatibility of liquid metal reactor structural materials with sodium has been reviewed in terms of corrosion rate, selective leaching, deposition, transport of carbon and radioactivity. Various data show that corrosion rate is dependent on sodium flow rate, temperature and oxygen concentration while carburization is very sensitive to the difference in chemical activities of carbon in sodium and stainless steel materials. Under the sodium environment, tensile and creep strength decrease with increase of exposure rate while fatigue strength increases with time. Data analysis on compatibility of sodium with various candidate liquid metal reactor structural materials confirms that sodium technology has been concentrated on the reduction of deposition rate, increase in thermal and mechanical properties, and improvement of welding component properties. 19 figs., 1 tab., 15 refs. (Author).

  4. Potentiel des moteurs à mélange pauvre face aux moteurs actuels à réglage stoechiométrique : consommation, émissions, exigence en octane The Challenge to Modern Stoichiometric Engines by the Potential Lean-Burn Engine: Consumption, Emissions, Fuel Requirements

    OpenAIRE

    Douaud A. M.; Ecomard A.; Guibet J. C.; Prigent M.

    2006-01-01

    Le moteur à allumage commandé pour application automobile aux États-Unis est généralement dépollué par catalyse trifonctionnelle qui impose un contrôle stoechiométrique du mélange air-carburant. Le contexte européen de 1990 pour la qualité de l'air stimule l'industrie automobile dans ses recherches de solutions techniques performantes. Le moteur à mélange pauvre, performant en consommation, est une solution potentielle si l'émission de NOx peut être maîtrisée par la combustion. Cet objectif n...

  5. 马氏体不锈钢低温表面改性技术研究进展%Research progress of low temperature surface modification technology for martensitic stainless steel

    Institute of Scientific and Technical Information of China (English)

    刘瑞良; 闫牧夫; 乔英杰

    2012-01-01

    综述了马氏体不锈钢的低温表面改性处理技术及其研究进展,重点介绍了马氏体不锈钢低温渗氮、低温渗碳、低温氮碳共渗和离子注入技术,以期为马氏体不锈钢的表面改性提供参考。%Technology and research progress of low temperature surface modification for martensitic stainless steels are reviewed, and the emphases are on low temperature nitriding, low temperature carburizing, low temperature nitrocarburizing as well as ion implantation of martensitic stainless steels, all of which could provide valuable references for surface modification of martensitic stainless steels.

  6. Fatigue and Creep Crack Propagation behaviour of Alloy 617 in the Annealed and Aged Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Julian K. Benz; Richard N. Wright

    2013-10-01

    The crack propagation behaviour of Alloy 617 was studied under various conditions. Elevated temperature fatigue and creep-fatigue crack growth experiments were conducted at 650 and 800 degrees C under constant stress intensity (triangle K) conditions and triangular or trapezoidal waveforms at various frequencies on as-received, aged, and carburized material. Environmental conditions included both laboratory air and characteristic VHTR impure helium. As-received Alloy 617 displayed an increase in the crack growth rate (da/dN) as the frequency was decreased in air which indicated a time-dependent contribution component in fatigue crack propagation. Material aged at 650°C did not display any influence on the fatigue crack growth rates nor the increasing trend of crack growth rate with decreasing frequency even though significant microstructural evolution, including y’ (Ni3Al) after short times, occurred during aging. In contrast, carburized Alloy 617 showed an increase in crack growth rates at all frequencies tested compared to the material in the standard annealed condition. Crack growth studies under quasi-constant K (i.e. creep) conditions were also completed at 650 degrees C and a stress intensity of K = 40 MPa9 (square root)m. The results indicate that crack growth is primarily intergranular and increased creep crack growth rates exist in the impure helium environment when compared to the results in laboratory air. Furthermore, the propagation rates (da/dt) continually increased for the duration of the creep crack growth either due to material aging or evolution of a crack tip creep zone. Finally, fatigue crack propagation tests at 800 degrees C on annealed Alloy 617 indicated that crack propagation rates were higher in air than impure helium at the largest frequencies and lowest stress intensities. The rates in helium, however, eventually surpass the rates in air as the frequency is reduced and the stress intensity is decreased which was not observed at 650

  7. Development Trend and Latest Research Achievements of High Strength Gray Cast Irons Melting Technique%高强度灰铸铁熔炼技术发展趋势及最新研究成果

    Institute of Scientific and Technical Information of China (English)

    逄伟

    2011-01-01

    The development history of the gray cast iron melting was reviewed and considered that improving nucleation capacity of graphite during melting process is the important approach to improve the melting quality. By comparing the test data of HT250 grade gray irons produced with cupola-induction fumace duplex process melting and with induction furnace melting plus carburizing treatment, it was explained that adopting induction furnace melting plus carburizing process can effectively reduce the shrinkage and chilling tendency, decrease the section sensitivity of the gray irons, improve graphite morphology, and increase properties of the material. It was pointed out that due to the improvement of melting process level and the innovation of iron melt treating technique the HT300 grade gray iron has been put into industrial application, and the HT350 and higher grade gray irons also have been reached.%回顾了灰铸铁熔炼技术的发展历史,认为提高熔炼过程中石墨的形核能力是提高熔炼技术的重要途径.通过冲天炉与感应炉双联熔炼和感应炉增碳熔炼HT250材料的对比试验数据,说明采用感应炉增碳工艺可以有效地减轻铁液的收缩和白口倾向,减少灰铸铁的断面敏感性,改善石墨形态,提高材料性能.指出随着熔炼工艺水平的提高和铁液炉前处理技术的创新,HT300材料已产业化应用,HT350及更高牌号的灰铸铁材料也已经能够达到.

  8. Les émissions par perméabilité à travers les canalisations des véhicules automobiles Emissions Due to Permeation Through the Vehicule Fuel Lines

    Directory of Open Access Journals (Sweden)

    Dewimille B.

    2006-12-01

    Full Text Available Un des objectifs de la politique environnementale de l'Union européenne est de réduire les émissions des véhicules automobiles. Les normes Euro 96 et Euro 2000 s'intéressent en particulier aux émissions par évaporation dues à la perméation du carburant à travers les matériaux polymères. Dans ce papier, nous exposons la méthode d'essai des lignes de carburant développée à l'IFP avec PSA et Renault. Nous présentons également des résultats obtenus avec divers types de canalisations et plusieurs fluides d'essai. Au vu de ces résultats et de la sévérité des nouvelles normes, les équipementiers et les fournisseurs de matières doivent développer de nouvelles solutions afin d'améliorer la résistance à la perméation. The aim of the environmental policy of the European Union is to reduce the automotive hydrocarbon emissions. The Euro 96 and future Euro 2000 standards are particularly dealing with the emissions due to fuel permeation through polymeric materials. In this paper, the testing procedure for fuel lines developed at IFP, PSA, and Renault, is described. Results obtained with various types of fuel lines and several fuels are detailed. According to these results and to the new stringent standards, equipment and material suppliers will have to develop new solutions with improved permeation resistance.

  9. 18Cr2Ni4WA齿轮弯曲疲劳试验及基于可靠度的试验数据统计研究%18Cr2Ni4WA GEAR BENDING FATIGUE EXPERIMENT AND EXPERIMENT DATA STATISTICAL ANALYSIS BASED ON RELIABILITY THEORY

    Institute of Scientific and Technical Information of China (English)

    武志斐; 王铁; 张瑞亮; 李威

    2012-01-01

    针对18Cr2Ni4WA渗碳淬火齿轮弯曲疲劳试验,介绍试验方法、试验齿轮、试验机及夹具,说明应力水平确定方法,最后通过失效判据判定失效寿命得出试验点数据,根据试验数据拟合出R-S-N曲线,并对试验数据处理方法进行探索.根据试验数据确定其寿命的威布尔分布,为渗碳淬火齿轮的可靠性定量评估提供一种切实可行的方法,为齿轮可靠性设计提供基础试验数据.%Deal with the bench 18Cr2Ni4WA carburizing and quenching gear bending fatigue experiment, the experimental method,experimental gear, experimental machine and fixture, stress levels are introduced, the experimental sites data obtained from gear failure life, the R-5-N curve is fitted according to experiment data, the experimental sites data processing method is also explored. The Weibull distributing made scientific researches on test gear was put forward and the concrete distributing of bending fatigue life is confirmed. Meanwhile, a faithfully way with reliability analysis of the carburizing and quenching gear is provided. Otherwise, based test data for gear reliability design.

  10. Effects of chromium content and sodium velocity on the compatibility of high-Cr ferritic steels in a sodium environment

    International Nuclear Information System (INIS)

    To obtain fundamental data on the compatibility of high-chromium ferritic steels in sodium, high-purity Fe-0.1C-1Mo-5, 9 or 13Cr ferritic steels were prepared by vacuum melting. Test specimens of these steels which were normalized and tempered and a reference type 316 stainless steel (316 ss) were exposed to two sodium-velocity regions for periods up to 10.8 Ms in a sodium loop system which had a direct resistance main heater and was made of SUS 316. The test temperature, the maximum temperature, of the loop system in this work was 873 K, the oxygen content of sodium was 1 - 2 ppm, and the sodium velocities were about 4.0 and 0.02 m/s. The specimens exposed to the high sodium-velocity region revealed that corrosion loss at a zero downstream position of the three kinds of ferritic steels was smaller than that of the reference 316 ss ; about one fifth for the 5 and 9 %Cr steels and one half for the 13 %Cr steel. The surface analysis showed deposition of Ni that dissolved at upstream for all the ferritic steels, deposition of Cr for the 5 %Cr steel, and selective dissolution of Cr for the 9 and 13 %Cr steels. The ferritic steels without Ni and with less amounts of Cr than the reference 316 ss would result in their smaller corrosion loss than the 316 ss. Transfer of carbon, nitrogen and oxygen was not remarkable, except the carburization of the 5 %Cr steel. The specimens of the three kinds of ferritic steels which were exposed to the low sodium-velocity region revealed much smaller corrosion loss than that in the high velocity region, deposition of both Ni and Cr, and no transfer of carbon, nitrogen and oxygen except for slight carburization of the 13 %Cr steel. (author)

  11. Carbon in sodium - A status review of the U.S.A. R and D work

    International Nuclear Information System (INIS)

    Liquid Metal Fast Breeder Reactors contain several types of steel in primary and secondary sodium systems. Austenitic stainless steels are used for in-core components, valves, heat exchangers, tanks and fuel cladding in primary systems. In power generating plants, the secondary or intermediate heat transport system may contain both austenitic and ferritic steel such as 2-1/4 Cr-l Mo type. Sodium circulating throughout the plant contains a number of impurities, metallic and non-metallic, with the steel interstitial elements carbon, hydrogen and oxygen being of prime importance. These elements can affect corrosion rates and mechanical behavior of materials. In the case of carbon, the sodium provides a transport medium with carburization and decarburization occurring in several parts of a system at rates depending upon temperature and types of steel. The US Sodium Technology R and D programs have investigated the behavior, transport, measurement and control of carbon in sodium. Measurement and control methods for carbon-containing materials which might contaminate the plant systems during reactor operation have also been studied. During the early 1970's, several US laboratories were active in studying carbon solubility, activity in sodium and interstitial transfer using both theoretical and experimental approaches. Modelling studies were done and models were used to predict FFTF and CRBRP materials requirements, component design and plant operating conditions. Over the past several years, carbon work has not been heavily emphasized. Most of the R and D studies have centered on improving chemical analysis methods for measuring active carbon, both by on-line monitors and by metal foil equilibration procedures; and on studies of pump oil-sodium reactions, reaction products, temperature effects and oil leak detection methods. One program at General Electric is investigating carburization-decarburization in a ferritic-austenitic system simulating conditions expected in

  12. The Effect of Mo2C Synthesis and Pretreatment on Catalytic Stability in Oxidative Reforming Environments

    Energy Technology Data Exchange (ETDEWEB)

    Lamont, David C.(8392); Gilligan, Andrew J.(Washington University); Darujati, Anna R S.(Washington State University); Chellappa, Anand S.(WASHINGTON STATE UNIV); Thomson, Wiliam J.(8392)

    2003-07-10

    The role of catalyst pretreatment on the stability of Mo2C catalysts in oxidative reforming environments has been studied. Catalysts were produced by both the temperature programmed reaction (TPR) and a solution-derived (SD) synthesis method, and compared to a low surface area commercial catalyst. Using a variety of techniques, including in situ dynamic X-ray diffraction (DXRD), the effects of various hydrogen pretreatment protocols were evaluated, including catalyst thermal stability, oxidation resistance and susceptibility to coking. The high surface areas produced by the SD synthesis is attributed to the presence of excess synthesis carbon and, whereas the presence of excess synthesis carbon enhances thermal stability, it also appears to accelerate coking. It is pointed out that the lowered oxidation resistance of the high surface area catalysts is due to a combination of smaller crystallite sizes and competitive oxidation of the excess synthesis carbon, which alters the oxidation mechanism. In addition, it was also found that incomplete carburization during TPR synthesis, forms an oxycarbide and its acidity also promotes coking. Hydrogen pretreatment at 700 .C not only removes all excess synthesis carbon, but it also reduces the oxycarbide to Mo, which is easily carburized under reforming conditions. Pretreatment at 600 .C, was largely ineffective and it is concluded that high temperature pretreatment is necessary to form the stoichiometric carbide, which is required for stability during reforming. Both the TPR and SD catalysts pretreated at 700 .C, were found to be stable over a 72 h period, whereas the commercial carbide had almost identical activity but slowly deactivated over the same period, probably because of its low surface area. Finally, labeled isotope experiments revealed that carbon exchange occurs readily with bulk Mo2C at temperatures above 550 .C, lending credence to a reforming redox mechanism.

  13. A selection of the protective atmosphere eliminating the inter-operational copper plating step in the processing of gear wheels

    Directory of Open Access Journals (Sweden)

    Z. Gawroński

    2010-07-01

    Full Text Available Purpose: of this paper is modification of the processing procedures of selected components, which would allow one to eliminate the operations of copper plating and copper strip steps.Design/methodology/approach: Along with its technical advantages, helping to satisfy the customers’ needs, the technology of copper plating has one major disadvantage, comprised of the necessity to use highly toxic solutions, and a subsequent need to dispose the toxic wastes. The process of galvanic copper plating is, therefore, an operation unjustified both on ecological as well as on economical grounds.Findings: Application of a fully controlled and reproducible protective atmosphere in the hardening procedure as a replacement approach for a disadvantageous measure of inter-operational copper plating in the production of gear wheels and pinions.Research limitations/implications: The energetic development in automotive and aviation industries have played a significant role in development of modern multitooling technologies in the production of gear wheels [11-14]. As discussed in the works of Dowes and Cooksey [1], Drug and Ghelec [2], Edenhofer [3-5], Hoffmann [8], working components of the bevel and hypoid gear systems in aerospace and automotive industries are usually made of low carbon steels with the gas carburizing operation used for their hardening.Practical implications: The requirements of the aerospace industry do not permit any structural alterations of the surface layer of the processed parts (oxidizing, carburizing or decarburization.Originality/value: Thanks to the specific modifications presented in this work the following achievements were made: lowering the production costs of gear wheels, improvement of environment protection and work conditions by a partial elimination of toxic chemicals.

  14. Gas-Solid Reaction Route toward the Production of Intermetallics from Their Corresponding Oxide Mixtures

    Directory of Open Access Journals (Sweden)

    Hesham Ahmed

    2016-08-01

    Full Text Available Near-net shape forming of metallic components from metallic powders produced in situ from reduction of corresponding pure metal oxides has not been explored to a large extent. Such a process can be probably termed in short as the “Reduction-Sintering” process. This methodology can be especially effective in producing components containing refractory metals. Additionally, in situ production of metallic powder from complex oxides containing more than one metallic element may result in in situ alloying during reduction, possibly at lower temperatures. With this motivation, in situ reduction of complex oxides mixtures containing more than one metallic element has been investigated intensively over a period of years in the department of materials science, KTH, Sweden. This review highlights the most important features of that investigation. The investigation includes not only synthesis of intermetallics and refractory metals using the gas solid reaction route but also study the reaction kinetics and mechanism. Environmentally friendly gases like H2, CH4 and N2 were used for simultaneous reduction, carburization and nitridation, respectively. Different techniques have been utilized. A thermogravimetric analyzer was used to accurately control the process conditions and obtain reaction kinetics. The fluidized bed technique has been utilized to study the possibility of bulk production of intermetallics compared to milligrams in TGA. Carburization and nitridation of nascent formed intermetallics were successfully carried out. A novel method based on material thermal property was explored to track the reaction progress and estimate the reaction kinetics. This method implies the dynamic measure of thermal diffusivity using laser flash method. These efforts end up with a successful preparation of nanograined intermetallics like Fe-Mo and Ni-W. In addition, it ends up with simultaneous reduction and synthesis of Ni-WN and Ni-WC from their oxide mixtures

  15. Catalytic synthesis of alcoholic fuels for transportation from syngas

    Energy Technology Data Exchange (ETDEWEB)

    Qiongxiao Wu

    2012-12-15

    carbon and reaches a maximum over bulk Mo2C, while the selectivity to methanol follows the opposite trend. The effect of Mo2C loading on the alcohol selectivity at a fixed K/Mo molar ratio of 0.14 could be related to the amount of K2CO3 actually on the active Mo2C phase and the size, structure, and composition of the supported carbide clusters. Unpromoted, active carbon supported Mo2C exhibits a high activity in CO hydrogenation with hydrocarbons as the dominant products. The K2CO3 promoter plays an essential role in directing the selectivity to alcohols rather than to hydrocarbons. The optimum selectivity towards higher alcohols and alcohols in general is obtained at a K/Mo molar ratio of 0.21 over the active carbon supported Mo2C (20 wt %). Combined in situ XAS and XRD have been used to follow directly the carburization process and formation of bulk and supported molybdenum carbides (20 wt % and 40 wt % Mo2C on active carbon). The bulk Mo2C prepared by temperature programmed carburization in flow of 20 mol % CH4 in H2 most likely adopts an orthorhombic structure (a-Mo2C). A two-step mechanism is discovered during the in situ carburization process, composed of the initial reduction of Mo(VI) oxide to Mo(IV) oxide followed by a succeeding conversion to carbide. The necessary carburization temperature is to a significant extent determined by the crystal sizes. A decrease on particle size can initiate the onset of carburization at a lower temperature. (LN)

  16. Analyse de la sensibilité aux paramètres gazoles d'un moteur diesel d'automobile à injection directe Small Direct Injection Diesel Engine Sensitivity to the Diesel Fuel Characteristics

    Directory of Open Access Journals (Sweden)

    Montagne X.

    2006-12-01

    Full Text Available L'étude présentée a été réalisée dans le cadre du GMCL (Groupement Moteur Carburant Lubrifiant, organisme qui réunit des constructeurs d'automobiles, des raffineurs et des additiveurs, avec l'objectif d'examiner la sensibilité d'un moteur Diesel à injection directe d'automobile aux paramètres du gazole. Les partenaires de cette étude sont Elf, IFP, Octel, PSA, Renault et Total. Parmi les solutions technologiques permettant de disposer de convertisseurs d'énergie assurant de faibles niveaux d'émissions de polluants et de consommation, le moteur Diesel se place naturellement en bonne position. Dans ce contexte, on enregistre aujourd'hui l'émergence du moteur Diesel à injection directe pour les véhicules légers en raison de ses performances, notamment en regard de la consommation. Toutefois, cette technologie nécessite une technique d'injection performante, associée à la gestion électronique, demande de l'EGR et un catalyseur d'oxydation afin de régler les problèmes d'émissions polluantes et sonores. Il est donc de première importance de cerner avec précision la sensibilité du moteur Diesel à injection directe aux paramètres carburants afin de tirer le meilleur profit de cette technologie. À partir d'un ensemble de gazoles formulés pour faire varier la composition chimique, l'indice de cétane et la densité, un moteur Audi à injection directe de type 1Z a été testé au banc, dans des conditions standard de réglage (avance à l'injection et taux de gaz recyclés. Cet ensemble de résultats a ainsi permis de démontrer que l'accroissement de l'indice de cétane, la réduction de la densité et de la teneur en polyaromatiques ont une influence positive sensible sur les émissions de CO, d'hydrocarbures imbrûlés, des VOF. En ce qui concerne les émissions de particules, l'indice de cétane semble avoir une influence négative sur la fraction sèche dans certaines conditions. De plus, il apparaît que les

  17. Multi Response Optimization of NOx Emission of a Stationary Diesel Engine Fuelled with Crude Rice Bran Oil Methyl Ester Optimisation à réponses multiples de l’émission de NOx d’un moteur Diesel stationnaire alimenté par de l’ester méthylique d’huile de riz brut

    Directory of Open Access Journals (Sweden)

    Saravanan S.

    2012-05-01

    Full Text Available In the present work, an attempt was made to reduce the NOx emission of crude rice bran oil methyl ester without any considerable increase in smoke density, when used as a fuel in a stationary CI engine. Three factors namely, fuel injection timing, Exhaust Gas Recirculation (EGR and fuel injection pressure were chosen and their combined effect in controlling the NOx emission of a stationary Diesel engine fuelled with crude rice bran oil methyl ester was investigated. Three levels were chosen in each factor and NOx emission, smoke density and brake thermal efficiency were taken as the response variables. Experiments were designed by employing design of experiments method and Taguchi’s L9 orthogonal array was used to conduct the engine tests with different levels of the chosen factors. Multi Response Signal-to-Noise ratio (MRSN was calculated for the response variables and the optimum combination level of factors was obtained simultaneously using Taguchi’s parametric design. Confirmation experiment was conducted for the obtained optimum combination level of factors and the results were compared with normal operating conditions and significant improvement was observed in the response variables. Dans la présente étude, il a été tenté de réduire les émissions de NOx de l'ester méthylique d'huile de riz brut sans accroissement considérable de la densité de fumée lorsqu'il est utilisé comme carburant dans un moteur stationnaire à allumage par compression. Trois facteurs, à savoir le calage d'injection de carburant, le pourcentage de recirculation des gaz d'échappement (EGR ; Exhaust Gas Recirculation et la pression d'injection de carburant ont été choisis, et leur effet combiné a été examiné en matière de maîtrise des émissions de NOx d'un moteur Diesel stationnaire alimenté avec de l'ester méthylique d'huile de riz brut. Trois niveaux ont été choisis pour chaque facteur et les émissions de NOx, la densité de fum

  18. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Akio Ishikawa; Manuel Ojeda; Enrique Iglesia

    2005-09-30

    This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rate, selectivity for feedstocks consisting of synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third reporting period, we improved the catalysts preparation method, which led to Fe-based FT catalysts with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During this fourth reporting period, we have determined the effects of different promoters on catalytic performance. More specifically, we have found that the sequence in which promoters are introduced has a marked positive impact on rates and selectivities. Cu or Ru chemical promoters should be impregnated before K to achieve higher Fischer-Tropsch synthesis rates. The catalyst prepared in this way was evaluated for 240 h, showing a high catalytic activity and stability after an initial period of time necessary for the formation of the active phases. Concurrently, we are studying optimal activation procedures, which involve the reduction and carburization of oxide precursors during the early stages of contact with synthesis gas. Activation at low temperatures (523 K), made possible by optimal introduction of Cu or Ru, leads to lower catalyst surface area than higher activation temperatures, but to higher reaction rates, because such low temperatures avoid concurrent deactivation

  19. Potentiel des moteurs à mélange pauvre face aux moteurs actuels à réglage stoechiométrique : consommation, émissions, exigence en octane The Challenge to Modern Stoichiometric Engines by the Potential Lean-Burn Engine: Consumption, Emissions, Fuel Requirements

    Directory of Open Access Journals (Sweden)

    Douaud A. M.

    2006-11-01

    Full Text Available Le moteur à allumage commandé pour application automobile aux États-Unis est généralement dépollué par catalyse trifonctionnelle qui impose un contrôle stoechiométrique du mélange air-carburant. Le contexte européen de 1990 pour la qualité de l'air stimule l'industrie automobile dans ses recherches de solutions techniques performantes. Le moteur à mélange pauvre, performant en consommation, est une solution potentielle si l'émission de NOx peut être maîtrisée par la combustion. Cet objectif nécessite une conception du moteur contrôlant la turbulence et l'hétérogénéité du mélange air + carburant + résiduels pendant la combustion. La longévité de l'adaptation optimale moteur-carburant nécessitera un contrôle électronique de l'allumage et l'utilisation d'additifs détergents. Pour satisfaire les réglementations les plus sévères, les émissions de CO et HC pourront être contrôlées par un simple pot catalytique d'oxydation. Des oxydes de métaux non précieux introduits dans la formule catalytique en addition aux métaux précieux maintiennent la fonction oxydante pendant les transitoires en mélange riche tout en réduisant partiellement les NOx. Une vue d'ensemble de ce concept basé sur des simulations numériques et des résultats expérimentaux de consommation, d'émission, d'exigence en octane, etc. est présentée. Spark-ignition engines for automotive applications in the United States are currently depolluted by a 3-way catalyst that requires air-fuel control at stoichiometry. The 1990 European context for air pollution control is stimulating the automotive industry to search for improved technical solutions. The lean-burn engine is a potential fuel-efficient answer if its combustion can be optimized for low NOx emissions. Achieving this challenging approach requires engine design to control the turbulence and heterogeneity of the air + fuel + residual mixture during combustion. Electronic ignition

  20. Structurally Integrated Coatings for Wear and Corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Beardsley, M. Brad; Sebright, Jason L.

    2008-11-18

    Wear and corrosion of structures cuts across industries and continues to challenge materials scientists and engineers to develop cost effective solutions. Industries typically seek mature technologies that can be implemented for production with rapid or minimal development and have little appetite for the longer-term materials research and development required to solve complex problems. The collaborative work performed in this project addressed the complexity of this problem in a multi-year program that industries would be reluctant to undertake without government partnership. This effort built upon the prior development of Advanced Abrasion Resistant Materials conduct by Caterpillar Inc. under DOE Cooperative Agreement No. DE-FC26-01NT41054. In this referenced work, coatings were developed that exhibited significant wear life improvements over standard carburized heat treated steel in abrasive wear applications. The technology used in this referenced work, arc lamp fusing of thermal spray coatings, was one of the primary technical paths in this work effort. In addition to extending the capability of the coating technology to address corrosion issues, additional competitive coating technologies were evaluated to insure that the best technology was developed to meet the goals of the program. From this, plasma transferred arc (PTA) welding was selected as the second primary technology that was investigated. Specifically, this project developed improved, cost effective surfacing materials and processes for wear and corrosion resistance in both sliding and abrasive wear applications. Materials with wear and corrosion performance improvements that are 4 to 5 times greater than heat treated steels were developed. The materials developed were based on low cost material systems utilizing ferrous substrates and stainless steel type matrix with hard particulates formed from borides and carbides. Affordability was assessed against other competing hard surfacing or coating

  1. Contribution to the study of the (U,Pu)C,N system; Contribution a l'etude du systeme (U,Pu)C,N

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzelli, R. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-07-01

    The reactions of UC, PuC, (U,Pu)C, UC{sub 2} and U(C{sub 1-x}O{sub x}) with nitrogen at moderate temperatures (room temperature to 400 C) are described. The influence of the uptake of nitrogen by the powders necessary to sinter the carbides upon the nature of the final product has been investigated; it has been shown that the sintered carbides are hyper-stoichiometric. The reactions of carbon with UN, PuN and (U,Pu)N has also been studied. Under vacuum, carbon reacts on the nitrides at temperatures as low as 1100 C; nitrogen is replaced by carbon and the final product is a carbonitride. The reaction is: MN + x C {yields} MN{sub 1-x}C{sub x} + x/2N{sub 2}. The reaction is limited and the carbonitrides have a fixed composition in presence of M{sub 2}C{sub 3} or MC{sub 2}; hence it is impossible to produce pure MC using the reaction. The ternary diagram U-C-N, Pu-C-N and (U,Pu)C-N have been drawn. They show clearly that it is possible to obtain single phase carbonitrides in a wide domain of compositions. (author) [French] On decrit les reactions avec l'azote de UC, PuC,(U,Pu)C,UC{sub 2} et U(C{sub 1-x}O{sub x}), par action directe de l'azote a temperature moderee (de l'ambiante a 450 C). On a etudie l'influence de la contamination par l'azote des poudres de carbures necessaires au frittage sur la nature des produits frittes; on a montre que les carbures frittes obtenus sont hyperstoechiometriques. On a etudie parallelement les reactions du carbone avec UN, PuN et (U,Pu)N. Sous vide le carbone reagit sur les nitrures des 1100 C: le carbone se substitue a l'azote; l'azote libere est elimine et le produit final est un carbonitrure. La reaction s'ecrit: MN + x C {yields} MN{sub 1-x}C{sub x} + x/2N{sub 2}. La reaction est limitee et les carbonitrures obtenus ont une composition limite fixe en presence des carbures superieurs M{sub 2}C{sub 3} et MC{sub 2}; il est donc impossible d'obtenir MC pur par cette reaction. Les diagrammes

  2. Etude de la migration des interstitiels dans des austenites Fe, Cr (18), Ni (14) pures et industrielles par irradiation dans un microscope a tres haute tension: Role du carbone et du titane

    Science.gov (United States)

    Housseau, N.; Pelissier, J.

    1983-12-01

    Nous avons étudié le rôle des impurtés (C ou Ti) dans la condensation et la migration des défauts interstitiels. Les échantillons étudiés sont des aciers austénitiques: (a) acier de synthèse de haute pureté (Cr 18, Ni 14, Fe) avec ou sans carbone; (b) acier industriel avec C (800 ppm) ou Ti (0,45%). Les échantillons ont été irradiés dans un microscope à très haute tension aux doses allant de 10 -4 jusqu'à 10 -1 dpa aux températures de 300°C à 400°C. Dans de telles conditions les défauts observés sont des boucles interstitielles. L'étude de la variation de l'épaisseur de la zone dénudée près du bord de la lame mince en fonction de la température nous a permis d'évaluer l'énergie de migration effective de l'interstitiel dans ces alliages. Dans l'austénite de synthèse carburée ou non sa valeur est de 0.8 eV. Dans l'acier industriel au titane carburé ou non on obtient 2.0 eV. Nous n'avons pas observé d'effet lié au carbone. L'examen de la densité de boucles à saturation dans les divers aciers suggère une forte énergie de liaison interstitiel-titane. Cette énergie de liaison, si l'ont admet que le titane est la seule impureté agissante du système, peut être estimée à 1.2 eV.

  3. Influencia de diferentes tratamientos termoquímicos en aceros sinterizados base molibdeno

    Directory of Open Access Journals (Sweden)

    Candela, N.

    2001-04-01

    Full Text Available Prealloyed steel powders with different amount of Mo-Cu-Ni-C were compacted at 700 MPa and sintered at 1120 °C in 95 % N2-5 % H2. After sinterizing, these materials were treated by carburizing. For materials characterization radial crushing strength were preformed, density was calculated and a complete study of fracture surfaces was carried out using scanning electron microscopy. The results of radial crushing strength show that resistance after carburizing is higher than in sintered materials. The fracture surfaces give an idea of materials briteless and the treatment depth. In sintered materials, a dúctil surface was observed, with the characteristic dimples. The fracture surfaces after different treatments show britelessnes in the outer zone, while inside appears a mix of dúctil and briteles fracture.

    Polvos prealeados de aceros con diferentes contenidos de Mo-Cu-Ni -C se compactaron a 700 MPa y se sinterizaron a 1.120 °C en atmósfera de 95 % N2-5 % H2. Después de la sinterización, los materiales se trataron termoquímicamente para su cementación (proceso endogas. Para la caracterización de todos los materiales se realizaron ensayos de compresión del tipo radial crushing strength, se calculó la densidad y se hizo un completo estudio de las superficies de fracturas a través de microscopía electrónica de barrido. Los resultados de resistencia a compresión muestran, después de la cementación, valores superiores a los encontrados en el estado sintetizado. La superficie de fractura da idea de la fragilidad del material y de la profundidad del tratamiento. En estado sintetizado, se observa una superficie de fractura totalmente dúctil, donde aparecen las características cavidades. Las superficies de fractura, tras distintos tipos de cementación, reflejan un comportamiento frágil en el exterior, mientras que el interior aparece una mezcla de fractura dúctil con frágil.

  4. Electrodeposited nickel(3) aluminide base intermetallic coatings and their resistance to high temperature degradation in hydrocarbon cracking environments

    Science.gov (United States)

    Liu, Haifeng

    This research was aimed at developing novel Ni-A1 base intermetallic coatings to protect commercial Fe-Ni-Cr tube alloys from severe corrosive degradation at high temperatures. These alloys are widely used in petrochemical, chemical, and energy conversion industries. The coating process and coating evaluation were the two main aspects of this investigation. A two-step coating processing has been successfully developed to in situ apply pure and CeO2-modified Ni3Al intermetallic coatings onto Fe-Ni-Cr substrates. The process consists of the electrodeposition of Ni-Al and Ni-Al-CeO2 composite coatings from a Watt's nickel bath containing Al and CeO2 particles via a cost-effective electroplating technique and an annealing treatment of the as-plated coatings. It was found that the deposition of Al particles obeyed a Guglielmi model, and that REO particles interfered significantly with the deposition of Al particles. The long-term resistance of pure and CeO2-modified Ni 3A1 coatings to cyclic oxidation, carburization, coke formation, and metal dusting was evaluated in flowing dry air, 2 % CH4-H 2, and CO-H2-H2O respectively. Due to the high porosity, pure and CeO2-dispersed Ni3Al coatings exhibited poor resistance to cyclic oxidation at 850°C. CeO2 improved the spallation resistance of the Ni3Al base coatings during cyclic oxidation at 1050°C. CeO2-dispersed Ni3Al coatings showed better carburization resistance, particularly at 1050°C. Ni 3A1-based coatings. Those CeO2-dispersed were susceptible to coke formation and metal dusting at 650°C. Pre-oxidation improved the resistance of Ni3Al-based coatings to coke formation and metal dusting at 650°C, but the effectiveness depended on the integrity of the induced alumina scale. Special attention was paid to several aspects of coating degradation. These aspects included microstructure changes, degradation mechanisms, coating/substrate interdiffusion, effect of corrosive atmosphere, and effect of CeO2 on coating

  5. Transformation of Sorbitol to Biofuels by Heterogeneous Catalysis: Chemical and Industrial Considerations Transformation du sorbitol en biocarburants par catalyse hétérogène : considérations chimiques et industrielles

    Directory of Open Access Journals (Sweden)

    Vilcocq L.

    2013-05-01

    Full Text Available Decreasing oil supplies and increasing energy demand provide incentives to find alternative fuels. First, the valorisation of edible crops for ethanol and biodiesel production led to first generation biofuels. Nowadays, research is focused on lignocellulosic biomass as a source of renewable carbon (second generation biofuels. Whereas the cellulosic ethanol production is in progress, a new way consisting of the transformation of ex-lignocellulose sugars and polyols towards light hydrocarbons by heterogeneous catalysis in aqueous phase has been recently described. This process is performed under mild conditions (T La raréfaction du pétrole et l’augmentation conjointe de la demande en carburants ont conduit à la recherche de carburants alternatifs. Dans un premier temps, la valorisation de ressources agricoles alimentaires pour la production d’éthanol et de biodiesel a permis de développer les biocarburants de première génération. Aujourd’hui les travaux de recherche s’orientent vers l’utilisation de biomasse lignocellulosique comme source de carbone renouvelable (biocarburants de deuxième génération. Alors que la filière de l’éthanol cellulosique est en plein développement, une nouvelle voie consistant à transformer des sucres et polyols d’origine lignocellulosique en alcanes légers par catalyse hétérogène bifonctionnelle en phase aqueuse a été récemment décrite. Ce procédé s’effectue à basse température et pression modérée (T < 300 °C et P < 50 bar. Il nécessite, d’une part, la formation d’hydrogène par reformage catalytique de carbohydrates en phase aqueuse et, d’autre part, la déshydratation/hydrogénation de polyols conduisant à un alcane par ruptures sélectives des liaisons C-O. Un défi lié à cette thématique réside dans le développement de systèmes catalytiques multifonctionnels stables, actifs et sélectifs dans les conditions de la réaction de transformation. L’objectif de

  6. The Modification of Sodium Polyacrylate Water Solution Cooling Properties by AL2O3

    Directory of Open Access Journals (Sweden)

    Wojciech Gęstwa

    2010-01-01

    Based on cooling curves, it can be concluded that for the water solution of sodium polyacrylate with AL2O3 nanoparticles in comparison to water and 10% polymer water solution lower cooling speed is obtained. The cooling medium containing nanoparticles provides lower cooling speed in the smallest surface austenite occurance (500–600 C in the charts of the CTP for most nonalloy structural steels and low-alloy steels. However lower cooling temperature at the beginning of martensitic transformation causes the formation of smaller internal stresses, leading to smaller dimensional changes and hardening deformation. For the quenching media the wetting angle was appointed by the drop-shape method. These studies showed the best wettability of polymer water solution (sodium polyacrylate with the addition of AL2O3 nanoparticles, whose wetting angle was about 65 degrees. Obtaining the smallest wetting angle for the medium containing nanoparticles suggests that the heat transfer to the cooling medium is larger. This allows slower cooling at the same time ensuring its homogeneity. The obtained values of wetting angle confirm the conclusions drawn on the basis of cooling curves and allowus to conclude that in the case of the heat transfer rate it will have a lower value than for water and 10% polymer water solution. In the research on hardened carburized steel samples C10 and 16MnCr5 surface hardness, impact strength and changes in the size of cracks in Navy C-ring sample are examined. On this basis of the obtained results it can be concluded that polymer water solution with nanoparticles allows to obtain a better impact strength at comparable hardness on the surface. Research on the dimensional changes on the basis of the sample of Navy C-ring also shows small dimensional changes for samples carburized and hardened in 10% polymer water solution with the addition of nanoparticles AL2O3. Smaller dimensional changes were obtained for samples of steel 16MnCr5 thanfar C10. The

  7. Fonctionnement transitoire et controle de la richesse des moteurs à allumage commandé à injection multipoint Transient Operation and Air-Fuel Ratio Control of Spark-Ignition Port-Injected Engines

    Directory of Open Access Journals (Sweden)

    Le Moyne L.

    2006-12-01

    Full Text Available Sur les moteurs à allumage commandé à injection multipoint on observe des désadaptations de richesse lors de fonctionnement transitoire. Ces désadaptations sont dues au dépôt, sous forme de film liquide, du carburant injecté dans le collecteur. Elles peuvent être compensées par une gestion adéquate de la masse injectée. Ainsi, afin d'obtenir la masse de carburant qui maintient la richesse constante, nous avons développé un modèle bidimensionnel des écoulements dans le collecteur au cours du cycle moteur. Ce modèle décrit l'écoulement des gaz frais, des gouttes injectées, des gaz brûlés refoulés vers l'admission et du film sur les parois, sur le principe de la séparation des phases. Nous montrons que le modèle reproduit correctement le signal de richesse et comment il permet de supprimer les désadaptations. La mesure de richesse est faite à l'échappement avec une sonde à oxygène dont nous validons le fonctionnement en transitoire avec une corrélation à la pression maximale du cycle dans le cylindre. Air-fuel ratio excursions are observed on port-injected spark ignition engines during transients. This excursions result from the liquid fuel film deposited on intake port. They can be compensated by controlling the injected fuel mass. In order to have the amount of fuel that keeps air-fuel ratio constant, we have developed a 2D model of flows in the intake port during engine cycle. This separate phases model describes the flow of fresh gases, injected droplets, hot burned gases and film on port walls. We show that the model effectively predicts the equivalence ratio and how it allows to eliminate excursions. Equivalence ratio measures are made with an oxygen sensor which functioning is validated during transients by correlating it to maximal pressure during engine cycle.

  8. On the Optimal Thermal Management of Hybrid-Electric Vehicles with Heat Recovery Systems Sur le thermo-management optimal d’un véhicule électrique hybride avec un système de récupération de chaleur

    Directory of Open Access Journals (Sweden)

    Merz F.

    2012-09-01

    Full Text Available A general framework to combine optimal energy management (powertrain supervisory control and thermal management in Hybrid Electric Vehicles (HEV is presented. A HEV system with engine exhaust aftertreatment and exhaust heat recovery system is simulated under various scenarios, including warm and cold start. Optimal strategies are derived from Pontryagin Minimum Principle (PMP. The concept of fuel equivalent of thermal energy variations – similar to the equivalence factors for battery energy of standard Equivalent Consumption Minimization Strategy (ECMS – is introduced. The PMP-based strategies are compared with a heuristic, rule-based strategy. The benefits in fuel economy and reduction of pollutant emissions that are obtained for several scenarios are very promising. Une approche généralisée pour combiner la gestion de l’énergie (supervision du groupe motopropulseur et le thermo-management dans les véhicules hybrides électriques est proposée. Un système hybride incluant le post-traitement des polluants et un système de récupération de la chaleur à l’échappement du moteur thermique est simulé pour plusieurs scénarii, y compris le cas de départ à froid. Des stratégies de gestion de l’énergie optimales sont dérivées à partir du Principe de Minimum de Pontriaguine (PMP. Inspirée par les facteurs d’équivalence pour la consommation électrique que l’on retrouve dans la stratégie ECMS, la notion d’équivalent en carburant des flux d’énergie thermique est introduite. Les stratégies dérivées du PMP sont comparées avec une stratégie heuristique basée sur des règles. Les bénéfices en termes d’économies de carburant et réduction des émissions polluantes que l’on trouve pour différents scénarii sont encourageantes.

  9. Evaluation of territorial conflicts caused by residential expansion in Bucharest suburban area. Case study: Voluntari City

    Directory of Open Access Journals (Sweden)

    CONSTANTINA ALINA TUDOR

    2011-04-01

    Full Text Available L'évaluation des conflits territoriaux causés par l'expansion résidentielle dans la zone périurbaine de Bucarest. Étude de cas: La ville Voluntari. L’aménagement territorial de l’espace aide les diverses utilisations du terrain à s’associer sans causer des dysfonctionnements ou des conflits. Dans la zone suburbaine de Bucarest les erreurs d’approche dans l’aménagement du territoire ont changé dans ces dernières années sa physionomie, particulièrement grâce au développement imprévu des zones résidentielles. Les conséquences de la consommation accidentelle de l’espace dans la ville Voluntari décrit un espace défavorisé par la complexité des problèmes environnementaux qui apparaissent. À cet effet ont été appliquées des méthodes pour évaluer la taille des conflits territoriaux causés par le développement imprévu des espaces résidentiels dans moins de 15 m des stations de distribution de carburant. Les résultats ont mis en évidence spatialement et quantitativement les zones en conflit, en suggérant l’emplacement imprévu des espaces résidentiels comme la principale conséquence de la création des voisinages incompatibles avec les stations de distribution de carburant. Les conflits territoriaux continuent à croître, leur identification et leur évaluation étant la solution de démarrage de nouvelles stratégies pour une bonne planification de l’espace avec un impact positif sur la qualité de l’environnement et du logement.

  10. Development and kinetic analysis of cobalt gradient formation in WC-Co composites

    Science.gov (United States)

    Guo, Jun

    2011-12-01

    Functionally graded cemented tungsten carbide (FG WC-Co) is one of the main research directions in the field of WC-Co over decades. Although it has long been recognized that FG WC-Co could outperform conventional homogeneous WC-Co owing to its potentially superior combinations of mechanical properties, until recently there has been a lack of effective and economical methods to make such materials. The lack of the technology has prevented the manufacturing and industrial applications of FG WC-Co from becoming a reality. This dissertation is a comprehensive study of an innovative atmosphere heat treatment process for producing FG WC-Co with a surface cobalt compositional gradient. The process exploited a triple phase field in W-C-Co phase diagram among three phases (solid WC, solid Co, and liquid Co) and the dependence of the migration of liquid Co on temperature and carbon content. WC-Co with a graded surface cobalt composition can be achieved by controlling the diffusion of carbon transported from atmosphere during sintering or during postsintering heat treatment. The feasibility of the process was validated by the successful preparations of FG WC-Co via both carburization and decarburization process following conventional liquid phase sintering. A study of the carburization process was undertaken to further understand and quantitatively modeled this process. The effects of key processing parameters (including heat treating temperature, atmosphere, and time) and key materials variables (involving Co content, WC grain size, and addition of grain growth inhibitors) on the formation of Co gradients were examined. Moreover, a carbon-diffusion controlled kinetic model was developed for simulating the formation of the gradient during the process. The parameters involved in this model were determined by thermodynamic calculations and regression-fit of simulation results with experimental data. In summary, this research first demonstrated the principle of the approach

  11. Materials Science Division coal technology eighth quarterly report, July--September 1976. [Gasification plant materials

    Energy Technology Data Exchange (ETDEWEB)

    None

    1976-01-01

    The analysis of ceramic refractories for slagging gasifiers from Run 2, a 500-h test with basic slag, is continuing. Wear measurements were performed on the magnesium zirconate-coated metal specimens that survived the 100-h test of hot, high-velocity char particles at Solar, Inc. These coatings were not uniformly thick, but they did resist the corrosive and erosive attack. The in-situ erosion studies have continued with the development of a convectively-cooled, ultrasonic waveguide and an attachment method that permits fastening of the waveguide directly to existing components. Experimental evaluation of the corrosion behavior of commercial iron- and nickel-base alloys in multicomponent gas mixtures that include CO, CO/sub 2/, H/sub 2/, CH/sub 4/, and H/sub 2/S is in progress. Oxygen-sulfur thermochemical diagrams were used as a basis in the selection of complex gas environments for the experimental program. Scanning-electron-microscope photographs of the cross sections of different alloys after exposure to gas environments with various oxygen, sulfur, and carbon potentials show that the corrosion behavior of commercial alloys in multicomponent gas environments in complex and fundamental processes such as oxidation, sulfidation, and carburization can occur simultaneously with different advancing reaction fronts. Additional failure analysis results are presented.

  12. Contribution to the study of thermal diffusivity of solids; Contribution a l'etude de la diffusivite thermique des solides

    Energy Technology Data Exchange (ETDEWEB)

    Zankel, K. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-07-01

    Angstroem method has been reviewed for its application to measurements of thermal diffusivity and conductivity on short specimens. An apparatus and a technique have been developed for rapid and precise measurements of a large variety of materials, which might also contain heat sources. This technique allows measurements at both high and low temperatures. Stainless steel, nickel and uranium monocarbide specimens were tested and the results of the thermal diffusivity measurements between 50 deg. C and 700 deg. C are presented. (author) [French] L'application de la methode d'Angstroem pour la mesure de la diffusivite et de la conductivite thermique sur des echantillons courts est examinee. Un appareillage est decrit, qui permet non seulement des mesures sur une grande variete de materiaux, mais qui est aussi concu pour des mesures rapides, precises et ou des sources thermiques peuvent etre introduites au sein de l'echantillon. La methode s'adapte egalement aux mesures a basses et hautes temperatures. Des resultats de mesure sur un echantillon en acier inoxydable, en nickel et en carbure d'uranium pour des temperatures comprises entre 50 et 700 deg. C sont reportes. (auteur)

  13. Feasibility Study on the Sodium Compatibility Test for Fuel Cladding of SFR

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jun Hwan; Shin, Sang Hun; Park, Sang Gyu; Ryu, Woo Seog; Kim, Sung Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    A Sodium-cooled Fast Reactor (SFR), a reactor that uses fast neutrons as a fission process, is considered one of the most probable candidates in next-generation reactors because it can maximize the uranium utilization when compared to conventional water reactor. Liquid sodium is used as a coolant in a SFR, because it has superior efficiency of fast neutron economy and high thermal conductivity, which enables a high power core design. However, previous research reported that fuel cladding materials like austenitic and ferritic-martensitic steel (FMS) react sodium coolant so that it results in the loss of the thickness, intergranular attack, and carburization or decarburization process to induce the change of the mechanical property. Fuel cladding, a seamless tube which has approximately 0.5mm in thickness and 3m in length is the component which covers fuel to protect radioactive species from being released. Because of its smaller thickness, the mechanical properties of the cladding are easily affected by the small changes of material property. This paper summarizes the status of sodium-material compatibility facility and proposes the optimal option in the case of the SFR fuel cladding. Previous researches revealed that assessing in-situ mechanical property is important in the case of cladding material owing to its dimensional characteristic. Optimal test method for assessing sodium compatibility of the cladding tube can be proposed that pressurized creep test under the controlled liquid sodium environment.

  14. In situ observation of the formation of TiC from the elements by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, Bjoern [Institut fuer Geowissenschaften, Abteilung Kristallographie, Universitaet Frankfurt, Senckenberganlage 30, D-60054 Frankfurt (Germany)]. E-mail: b.winkler@kristall.uni-frankfurt.de; Wilson, Dan J. [Institut fuer Geowissenschaften, Abteilung Kristallographie, Universitaet Frankfurt, Senckenberganlage 30, D-60054 Frankfurt (Germany); Vogel, Sven C. [Los Alamos National Laboratory, Lujan Center, Mail Stop H805, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Brown, Donald W. [Los Alamos National Laboratory, Lujan Center, Mail Stop H805, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Sisneros, Thomas A. [Los Alamos National Laboratory, Lujan Center, Mail Stop H805, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Milman, Victor [Accelrys Inc., 334 Science Park, Cambridge CB4 0WN (United Kingdom)

    2007-08-30

    In situ neutron diffraction has been employed to investigate the formation of TiC{sub x} from the elements at relatively low temperatures, beginning at T{approx} 1073 deg. K. Slow heating of the mixture of the elements precludes the generation of sufficient heat to induce a self-propagating high temperature synthesis (SHS), reported in the literature for this system. We observe that the reaction starts well before the {alpha} -{beta} transition in Ti occurs, which implies that in this case this transition does not serve as a trigger mechanism for SHS. An extensive coexistence of both polymorphs of titanium suggests that a significant amount of carbon diffuses into the hexagonal {alpha}-Ti lattice and stabilizes it with respect to the cubic {beta}-phase. This is supported by the observation of an anomalous increase of the c-lattice parameter of the {alpha}-Ti lattice above the transition temperature for pure {alpha}-Ti. Density functional theory (DFT) based calculations support this interpretation. The energetics of the carburization of {alpha}-Ti have been obtained from the DFT calculations.

  15. Reactions between sodium and various carbon bearing compounds

    International Nuclear Information System (INIS)

    The presence of carbon bearing materials in liquid sodium is undesirable because of their ability to carburise stainless steel components. It has been demonstrated for example that carbon taken up by stainless steels can affect their mechanical properties and that thinner sectioned material such as fuel cladding and the tubing of intermediate heat exchanger may be more sensitive to such effects. Generally speaking, there are a number of potential carbon sources in reactor systems. Some of the sources such as the graphite in neutron shield rods, boron carbide in control rods and carbide fuels are part of the reactor designs while others such as oil in mechanical pumps arid 'coupling-fluids' used to inspect plant components are associated with the respective operation arid inspection of the plant. In this paper it is intended to discuss in general terms the way these various compounds behave in liquid sodium and to assess what effect their presence will have on the materials of construction in fast reactor systems. The paper also reviews the chemistry of the environment in relation to the types of carburizing species which may exist in sodium systems

  16. Characterization of a Messer – The late-Medieval single-edged sword of Central Europe

    International Nuclear Information System (INIS)

    Metallurgical characterization of a sword blade fragments dating from the second half of the 15th century found in central Slovenia was performed in order to determine its chemical composition, microstructure, microhardness, and to obtain insight into the methods of manufacture of a late-medieval Messer sword. As the artefact was broken, examinations were limited to six very small fragments that were allowed to be removed from the cutting edge, core and the back of the blade. Light optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, energy dispersive X-ray fluorescence spectrometry, differential scanning calorimetry, thermodynamics approach and Vickers micro-hardness tests were employed to analyze the microstructure and mechanical properties. The results show that the sword was manufactured from a single wrought iron billet. The surface of the sword was carburized. No evidence of quenching was found. The ferritic microstructure is concentrated in the core, and the pearlitic in the outer layer of the blade. All metal fragments contained non-metallic inclusions that were derived mostly from slag and some from hammer scale. - Highlights: • A metallurgical characterization of a medieval sword blade has been performed. • The carbon content decreased from the surface to the core of the blade. • The dominant microstructure in the outer layer is pearlite and in the core is ferrite. • The presence of lump shaped and elongated non-metallic inclusions was observed. • The sword was manufactured from a single wrought iron billet

  17. Study of filament performance in heat transfer and hydrogen dissociation in diamond chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Hot-filament chemical vapor deposition (HFCVD) is a promising method for commercial production of diamond films.Filament performance in heat transfer and hydrogen decomposition in reactive environment was investigated. Power consumption by the filament in vacuum, helium and 2% CH4/H2 was experimentally determined in temperature range 1300℃-2200℃. Filament heat transfer mechanism in C-H reactive environment was calculated and analyzed. The result shows that due to surface carburization and slight carbon deposition, radiation in stead of hydrogen dissociation, becomes the largest contributor to power consumption. Filament-surface dissociation of H2 was observed at temperatures below 1873K, demonstrating the feasibility of diamond growth at low filament temperatures. The effective activation energies of hydrogen dissociation on several clean refractory filaments were derived from power consumption data in literatures. They are all lower than that of thermal dissociation of hydrogen, revealing the nature of catalytic dissociation of hydrogen on filament surface. Observation of substrate temperature suggested a weakerrole of atomic hydrogen recombination in heating substrates in C-H environment than in pure hydrogen.

  18. A Hybrid Low Temperature Surface Alloying Process for Austenitic Stainless Steels

    Institute of Scientific and Technical Information of China (English)

    Y. Sun

    2004-01-01

    This paper describes a novel, hybrid process developed to engineer the surfaces of austenitic stainless steels at temperatures below 450℃ for the improvement in wear and corrosion resistance. The process is carried out in the plasma of a glow discharge containing both nitrogen and carbon reactive species, and facilitates the incorporation of both nitrogen and carbon into the austenite surface to form a dual-layer structure comprising a nitrogen-rich layer on top of a carbon-rich layer.Both layers can be precipitation-free at sufficiently low processing temperatures, and contain nitrogen and carbon respectively in supersaturated fcc austenite solid solutions. The resultant hybrid structure offers several advantages over the conventional low temperature nitriding and the newly developed carburizing processes in terms of mechanical and chemical properties, including higher surface hardness, a hardness gradient from the surface towards the layer-core interface, uniform layer thickness, and much enhanced corrosion resistance. This paper discusses the main features of this hybrid process and the various structural and properties characteristics of the resultant engineered surfaces.

  19. Development of Combinatorial Methods for Alloy Design and Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Pharr, George M.; George, Easo P.; Santella, Michael L

    2005-07-01

    powerful technique for rapid structural and chemical characterization of alloy libraries was developed based on high intensity x-radiation available at synchrotron sources such as the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). With the technique, structural and chemical characterization of up to 2500 discrete positions on a library can made in a period of less than 4 hours. Among the parameters that can be measured are the chemical composition, crystal structure, lattice parameters, texture, and grain size. From these, one can also deduce isothermal sections of ternary phase diagrams. The equipment and techniques needed to do this are now in place for use in future combinatorial studies at the ORNL beam line at the APS. In conjunction with the chemical and structural investigations, nanoindentation techniques were developed to investigate the mechanical properties of the combinatorial libraries. The two primary mechanical properties of interest were the elastic modulus, E, and hardness, H, both of which were measured on alloy library surfaces with spatial resolutions of better than 1 m. A nanoindentation testing system at ORNL was programmed to make a series of indentations at specified locations on the library surface and automatically collect and store all the data needed to obtain hardness and modulus as a function of position. Approximately 200 indentations can be made during an overnight run, which allows for mechanical property measurement over a wide range of chemical composition in a relatively short time. Since the materials based on the Fe-Ni-Cr system often find application in highly carburizing and harsh chemical environments, simple techniques were developed to assess the resistance of Fe-Ni-Cr alloy libraries to carburization and corrosion. Alloy libraries were carburized by standard techniques, and the effectiveness of the carburization at various points along the sample surface was assessed by nanoindentation hardness measurement

  20. RESEARCH ABOUT RESULTS REPRODUTIBILITY AND ABRASIVE PARTICLES FRAGMENTATION IN BALL-CRATERING TESTS

    Directory of Open Access Journals (Sweden)

    Ronaldo Câmara Cozza

    2013-06-01

    Full Text Available The micro-abrasive wear tests by rotating ball (crater wear have played an important role in abrasive wear researches. In this type of test, the contact between a specimen and a ball on rotating motion and abrasive particles supplied between these two elements, results in a crater on the specimen, based on which the abrasive wear behaviour is analysed. The purpose of this work is to study results the reprodutibility and the silicon carbide (SiC abrasive particles fragmentation during micro-abrasive wear tests. Tests were conducted with carburized AISI 1010 steel balls and high speed steel specimens, “with” and “without” titanium nitride (TiN coatings. The abrasive slurry was prepared with black silicon carbide (average particle size of 5 µm and distilled water. Grooving abrasion is related with lower reprodutibility results. For the test conditions of this work, no abrasive particles fragmentation was observed, independently of the sliding distance, what is justified, among others factors, by the low normal force applied.

  1. Self reaction behavior of wood flour added coal composite iron ore hot briquettes under a blast furnace simulated heat and load

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, S.; Tanabe, K. [Nagoya Institute of Technology, Nagoya (Japan)

    2009-08-15

    The coal composite iron ore hot briquette made by utilizing thermal plasticity of coal is recently developed as agglomerates without binder, which has several advantages to retain high density and strength during reaction at high temperatures. The charge of this briquette to a blast furnace is expected to enable more effectively higher reaction rates at lower temperatures than usual operation. Moreover, utilization of biomass as carbon neutral is essential to construct a sustainable society permitting to conserve global environment and save resources and energies. In this work, influence of substituting biomass (Cedar wood flour) for one tenth amounts of coal in hot briquettes was examined by carrying out self reaction tests of the briquettes in a N2 gas steam under heat and load in a laboratory scale blast furnace simulator. It was proved that both briquettes with or without biomass could retain an industrial allowable strength beyond 50 kgf/cm2 after reaction, while the addition of biomass enhanced a little more the shrinkage of briquettes in the higher temperatures above 1000{sup o}C. Both gasification of biomass added coal and reduction of iron ore during their reaction were evaluated and it was found that the former rates were a little smaller than the latter as a whole, irrespective of the addition of biomass. Carburization to metallic iron began at nearly 1200 {sup o}C and both briquettes have been melted down at 1400{sup o}C due to nearly carbon saturation in metallic iron with a graphite crucible.

  2. Effect of two synthetic lubricants on life of AISI 9310 spur gears

    Science.gov (United States)

    Townsend, Dennis P.; Shimski, John

    1991-01-01

    Spur-gear fatigue tests were conducted with two lubricants using a single lot of consumable-electrode vacuum-melted (CVM) AISI 9310 spur gears. The gears were case carburized and hardened to Rockwell C60. The gear pitch diameter was 8.89 cm. The lot of gears was divided into two groups, each of which was tested with a different lubricant. The test lubricants can be classified as synthetic polyol-ester-based lubricants. One lubricant was 30 percent more viscous that the other. Both lubricants have similar pressure viscosity coefficients. Test conditions included a bulk gear temperature of 350 K, a maximum Hertz stress of 1.71 GPa at the pitch line, and a speed of 10,000 rpm. The surface fatigue life of gears tested with one lubricant was approximately 2.4 times that for gears tested with the other lubricant. The lubricant with the 30 percent higher viscosity gave a calculated elastohydrodynamic (EHD) film thickness that was 20 percent higher than the other lubricant. This increased EHD film thickness is the most probable reason for the improvement in surface fatigue life of gears tested with this lubricant over gears tested with the less viscous lubricant.

  3. Investigation of chemical characteristics of primary helium gas coolant of HTTR (high temperature engineering test reactor)

    Energy Technology Data Exchange (ETDEWEB)

    Hamamoto, Shimpei, E-mail: hamamoto.shimpei@jaea.go.jp [HTTR Operation Section, Department of HTTR, Japan Atomic Energy Agency, 4002 Narita, Oarai, Higashi-ibaraki, Ibaraki 311-1393 (Japan); Shimazaki, Yosuke [HTTR Reactor Engineering Section, Department of HTTR, Japan Atomic Energy Agency, 4002 Narita, Oarai, Higashi-ibaraki, Ibaraki 311-1393 (Japan); Furusawa, Takayuki; Nemoto, Takahiro; Inoi, Hiroyuki [HTTR Operation Section, Department of HTTR, Japan Atomic Energy Agency, 4002 Narita, Oarai, Higashi-ibaraki, Ibaraki 311-1393 (Japan); Takada, Shoji, E-mail: takada.shoji@jaea.go.jp [HTTR Reactor Engineering Section, Department of HTTR, Japan Atomic Energy Agency, 4002 Narita, Oarai, Higashi-ibaraki, Ibaraki 311-1393 (Japan)

    2014-05-01

    The technical basis of helium gas purification control for HTGRs was established by verifying the design of the Primary Helium Purification System (PHPS) of the HTTR by showing that the measured concentrations of impurities of the primary helium coolant were restricted below the criteria of control to protect the graphite oxidation, and that the carburization atmosphere was maintained to keep intact of metallic high temperature components, in the 30-day continuous operation and the 50-day long-term high temperature operation. The analytical model, which was newly established by improving the conventional method that predicted the impurity concentrations conservatively higher than the measured values, predicted the composition of the impurities such as H{sub 2}, CO, H{sub 2}O and CO{sub 2}, which is determined by the temperature dependency of release of impurities during the rated power operation adequately. In contrast, it was revealed that the measured concentration of H{sub 2}O remarkably decreased while the concentration of CO increased in the primary helium coolant in the long-term high temperature operation.

  4. Temperature Dependence of Nitro-Quenching by Atmospheric-Pressure Plasma

    Science.gov (United States)

    Mitani, Masaki; Ichiki, Ryuta; Iwakiri, Yutaro; Akamine, Shuichi; Kanazawa, Seiji

    2015-09-01

    A lot of techniques exist as the hardening method of steels, such as nitriding, carburizing and quenching. However, low-alloy steels cannot be hardened by nitriding because hardening by nitriding requires nitride precipitates of special alloy elements such as rare metals. Recently, nitro-quenching (NQ) was developed as a new hardening process, where nitrogen invokes martensitic transformation instead of carbon. NQ is adaptable to hardening low-alloy steels because it does not require alloy elements. In industrial NQ, nitrogen diffusion into steel surface is operated in high temperature ammonia gas. As a new technology, we have developed surface hardening of low-alloy steel by NQ using an atmospheric-pressure plasma. Here the pulsed-arc plasma jet with nitrogen/hydrogen gas mixture is sprayed onto steel surface and then water quench the sample. As a result, the surface of low-alloy steel was partially hardened up to 800 Hv by producing iron-nitrogen martensite. However, the hardness profile is considerably non-uniform. We found that the non-uniform hardness profile can be controlled by changing the treatment gap, the gap between the jet nozzle and the sample surface. Eventually, we succeeded in hardening a targeted part of steel by optimizing the treatment gap. Moreover, we propose the mechanism of non-uniform hardness.

  5. Corrosion resistance of Ni-50Cr HVOF coatings on 310S alloy substrates in a metal dusting atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Saaedi, J. [Centre for Advanced Coating Technologies, Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4 (Canada); Department of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Arabi, H.; Mirdamadi, S.; Ghorbani, H. [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Coyle, T.W. [Centre for Advanced Coating Technologies, Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4 (Canada)

    2011-09-15

    Metal dusting attack has been examined after three 168 h cycles on two Ni-50Cr coatings with different microstructures deposited on 310S alloy substrates by the high velocity oxy-fuel (HVOF) thermal-spray process. Metal dusting in uncoated 310S alloy specimens was found to be still in the initiation stage after 504 h of exposure in the 50H{sub 2}:50CO gas environment at 620 C. Dense Ni-50Cr coatings offered suitable resistance to metal dusting. Metal dusting was observed in the 310S substrates adjacent to pores at the interface between the substrate and a porous Ni-50Cr coating. The porosity present in the as-deposited coatings was shown to introduce a large variability into coating performance. Carbon formed by decomposition of the gaseous species accumulated in the surface pores and resulted in the dislodgement of surface splats due to stresses generated by the volume changes. When the corrosive gas atmosphere was able to penetrate through the interconnected pores and reach the coating-substrate interface, the 310S substrate was carburized, metal dusting attack occurred, and the resulting formation of coke in the pores led to local failure of the coating. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Molybdenum Speciation and its Impact on Catalytic Activity during Methane Dehydroaromatization in Zeolite ZSM-5 as Revealed by Operando X-Ray Methods.

    Science.gov (United States)

    Lezcano-González, Inés; Oord, Ramon; Rovezzi, Mauro; Glatzel, Pieter; Botchway, Stanley W; Weckhuysen, Bert M; Beale, Andrew M

    2016-04-18

    Combined high-resolution fluorescence detection X-ray absorption near-edge spectroscopy, X-ray diffraction, and X-ray emission spectroscopy have been employed under operando conditions to obtain detailed new insight into the nature of the Mo species on zeolite ZSM-5 during methane dehydroaromatization. The results show that isolated Mo-oxo species present after calcination are converted by CH4 into metastable MoCx Oy species, which are primarily responsible for C2 Hx /C3 Hx formation. Further carburization leads to MoC3 clusters, whose presence coincides with benzene formation. Both sintering of MoC3 and accumulation of large hydrocarbons on the external surface, evidenced by fluorescence-lifetime imaging microscopy, are principally responsible for the decrease in catalytic performance. These results show the importance of controlling Mo speciation to achieve the desired product formation, which has important implications for realizing the impact of CH4 as a source for platform chemicals. PMID:26990500

  7. Investigation of chemical characteristics of primary helium gas coolant of HTTR (high temperature engineering test reactor)

    International Nuclear Information System (INIS)

    The technical basis of helium gas purification control for HTGRs was established by verifying the design of the Primary Helium Purification System (PHPS) of the HTTR by showing that the measured concentrations of impurities of the primary helium coolant were restricted below the criteria of control to protect the graphite oxidation, and that the carburization atmosphere was maintained to keep intact of metallic high temperature components, in the 30-day continuous operation and the 50-day long-term high temperature operation. The analytical model, which was newly established by improving the conventional method that predicted the impurity concentrations conservatively higher than the measured values, predicted the composition of the impurities such as H2, CO, H2O and CO2, which is determined by the temperature dependency of release of impurities during the rated power operation adequately. In contrast, it was revealed that the measured concentration of H2O remarkably decreased while the concentration of CO increased in the primary helium coolant in the long-term high temperature operation

  8. Effects of cerium and manganese on corrosion of Fe–Cr and Fe–Cr–Ni alloys in Ar–20CO2 gas at 818 °C

    International Nuclear Information System (INIS)

    Highlights: •CO2 gas is more corrosive than dry air for Fe–Cr and Fe–Cr–Ni alloys at 818 °C. •Chromia scale grows faster in CO2 than in air. •Cerium has no significant effect on reducing oxidation rate of the alloys in CO2. •Manganese significantly improves oxidation resistance of Fe–20Cr and Fe–20Cr–20Ni alloys in CO2. -- Abstract: Model alloys Fe–9Cr, Fe–20Cr and Fe–20Cr–20Ni (wt.%) with Ce (0.05%, 0.1%) or Mn (1%, 2%) were exposed to Ar–20CO2 gas at 818 °C. Scales on Fe–9Cr alloys consisted of FeO and FeCr2O4, Fe–20Cr–(Ce) alloys formed only Cr2O3, and Fe–20Cr–(Mn) alloys formed Cr2O3 and MnCr2O4. All Fe–20Cr–20Ni alloys formed Fe3O4, FeCr2O4 and FeNi3. Cerium additions had little effects, but additions of 2% Mn significantly improved oxidation resistance of Fe–20Cr and Fe–20Cr–20Ni alloys. Most alloys also carburized. All alloys developed protective chromium-rich oxide scales in air. Different behavior in the two gases is attributed to faster Cr2O3 scaling rates induced by CO2

  9. Development of Combinatorial Methods for Alloy Design and Optimization

    International Nuclear Information System (INIS)

    rapid structural and chemical characterization of alloy libraries was developed based on high intensity x-radiation available at synchrotron sources such as the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). With the technique, structural and chemical characterization of up to 2500 discrete positions on a library can made in a period of less than 4 hours. Among the parameters that can be measured are the chemical composition, crystal structure, lattice parameters, texture, and grain size. From these, one can also deduce isothermal sections of ternary phase diagrams. The equipment and techniques needed to do this are now in place for use in future combinatorial studies at the ORNL beam line at the APS. In conjunction with the chemical and structural investigations, nanoindentation techniques were developed to investigate the mechanical properties of the combinatorial libraries. The two primary mechanical properties of interest were the elastic modulus, E, and hardness, H, both of which were measured on alloy library surfaces with spatial resolutions of better than 1 m. A nanoindentation testing system at ORNL was programmed to make a series of indentations at specified locations on the library surface and automatically collect and store all the data needed to obtain hardness and modulus as a function of position. Approximately 200 indentations can be made during an overnight run, which allows for mechanical property measurement over a wide range of chemical composition in a relatively short time. Since the materials based on the Fe-Ni-Cr system often find application in highly carburizing and harsh chemical environments, simple techniques were developed to assess the resistance of Fe-Ni-Cr alloy libraries to carburization and corrosion. Alloy libraries were carburized by standard techniques, and the effectiveness of the carburization at various points along the sample surface was assessed by nanoindentation hardness measurement. Corrosion tests were

  10. Silicon effects on formation of EPO oxide coatings on aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L. [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, ON, N9B 3P4 (Canada); Nie, X. [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, ON, N9B 3P4 (Canada)]. E-mail: xnie@uwindsor.ca

    2006-01-03

    Electrolytic plasma processes (EPP) can be used for cleaning, metal-coating, carburizing, nitriding, and oxidizing. Electrolytic plasma oxidizing (EPO) is an advanced technique to deposit thick and hard ceramic coatings on a number of aluminum alloys. However, the EPO treatment on Al-Si alloys with a high Si content has rarely been reported. In this research, an investigation was conducted to clarify the effects of silicon contents on the EPO coating formation, morphology, and composition. Cast hypereutectic 390 alloys ({approx} 17% Si) and hypoeutectic 319 alloys ({approx} 7% Si) were chosen as substrates. The coating morphology, composition, and microstructure of the EPO coatings on those substrates were investigated using scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD). A stylus roughness tester was used for surface roughness measurement. It was found that the EPO process had four stages where each stage was corresponding to various coating surface morphology, composition, and phase structures, characterised by different coating growth mechanisms.

  11. In-situ fabrication of MoSi2/SiC–Mo2C gradient anti-oxidation coating on Mo substrate and the crucial effect of Mo2C barrier layer at high temperature

    International Nuclear Information System (INIS)

    MoSi2/SiC–Mo2C gradient coating on molybdenum was in situ prepared with pack cementation process by two steps: (1) carburizing with graphite powder to obtain a Mo2C layer on Mo substrate, and (2) siliconizing with Si powder to get a composite MoSi2/SiC layer on the upper part of Mo2C layer. The microstructure and elemental distribution in the coating were investigated with scanning electron microscopy (SEM), backscattered electron (BSE), energy dispersive spectroscopy (EDS), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Cyclic oxidation tests (at 500 °C, 1200 °C, 1400 °C and 1600 °C) demonstrated excellent oxidation resistance for the gradient composite coating and the mass loss was only 0.23% in 60 min at 1600 °C. XRD, EPMA, thermal dynamic and phase diagram analyses indicated that the Mo2C barrier layer played the key role in slowing down the diffusion of C and Si toward inner Mo substrate at high temperature and principally this contributed to the excellent anti-oxidation for Mo besides the outer MoSi2/SiC composite layer.

  12. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  13. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Wilkening, D. [Columbia Falls Aluminum Co., 2000 Aluminum Dr., Columbia Falls, MT 59912 (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., P.O. Box 1071, Anaconda, MT 59711 (United States)

    1998-12-31

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{sup TM} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast. (orig.) 18 refs.

  14. Zirconium carbide coating for corium experiments related to water-cooled and sodium-cooled reactors

    Science.gov (United States)

    Plevacova, K.; Journeau, C.; Piluso, P.; Zhdanov, V.; Baklanov, V.; Poirier, J.

    2011-07-01

    Since the TMI and Chernobyl accidents the risk of nuclear severe accident is intensively studied for existing and future reactors. In case of a core melt-down accident in a nuclear reactor, a complex melt, called corium, forms. To be able to perform experiments with prototypic corium materials at high temperature, a coating which resists to different corium melts related to Generation I and II Water Reactors and Generation IV sodium fast reactor was researched in our experimental platforms both in IAE NNC in Kazakhstan and in CEA in France. Zirconium carbide was selected as protective coating for graphite crucibles used in our induction furnaces: VCG-135 and VITI. The method of coating application, called reactive wetting, was developed. Zirconium carbide revealed to resist well to the (U x, Zr y)O 2-z water reactor corium. It has also the advantage not to bring new elements to this chemical system. The coating was then tested with sodium fast reactor corium melts containing steel or absorbers. Undesirable interactions were observed between the coating and these materials, leading to the carburization of the corium ingots. Concerning the resistance of the coating to oxide melts without ZrO 2, the zirconium carbide coating keeps its role of protective barrier with UO 2-Al 2O 3 below 2000 °C but does not resist to a UO 2-Eu 2O 3 mixture.

  15. Effect of Mercury Velocity on Corrosion of Type 316L Stainless Steel in a Thermal Convection Loop

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, SJ

    2001-03-23

    Two 316L thermal convection loops (TCLs) containing several types of 316L specimens circulated mercury continuously for 2000 h at a maximum temperature of 300 C. Each TCL was fitted with a venturi-shaped reduced section near the top of the hot leg for the purpose of locally increasing the Hg velocity. Results suggest that an increase in velocity from about 1.2 m/min (bulk flow) to about 5 mmin (reduced section) had no significant impact on compatibility of 316L with Hg. In addition, various surface treatments such as gold-plating, chemical etching, polishing, and steam cleaning resulted in little or no influence on compatibility of 316L with Hg when compared to nominal mill-annealed/surface-ground material. A sensitizing heat treatment also had little/no effect on compatibility of 316L with Hg for the bulk specimen, although intergranular attack was observed around the specimen holes in each case. It was determined that carburization of the hole area had occurred as a result of the specimen fabrication process potentially rendering the specimens susceptible to corrosion by Hg at these locations. To avoid sensitization-related compatibility issues for SNS components, selection of low carbon grades of stainless steel and control of the fabrication process is recommended.

  16. The experiments for mechanical properties of 20Cr2Ni4 steel and the coefficient definition of constitutive equation

    Science.gov (United States)

    Pang, L.; Liu, G. C.; Lu, J. P.

    2015-12-01

    The 20Cr2Ni4 alloy steel has the properties of high strength, toughness and hardness. It is used in large cross-section carburized parts, such as gears, shafts and components which are required high strength and good toughness. In order to study the static mechanical properties and dynamic mechanical properties of 20Cr2Ni4 steel, the static compression experiment and the Hopkinson Pressure Bar test are conducted. The stress-strain relationship within the scope of 25∼400°C is obtained by experiments, and softening effect of strain rate and strengthening effect of temperature is comprehensively analyzed. The paper has a more comprehensive understanding on mechanical response of 20Cr2Ni4 steel within the scope of 25∼400°C. Based on the experiment data the parameters in Johnson-Cook constitutive equation of 20Cr2Ni4 have been gotten. The research results of this paper lay a foundation for the further applications of 20Cr2Ni4 steel.

  17. A Short Historical Review of Fast Pyrolysis of Biomass Une brève revue historique de la pyrolyse rapide de la biomasse

    Directory of Open Access Journals (Sweden)

    Radlein D.

    2013-10-01

    Full Text Available In this short review, we survey the historical progress of fast pyrolysis technologies for thermochemical liquefaction of biomass to produce so-called "bio-oil". Our focus is on the potential applications of bio-oil as a liquid fuel for heat and power generation. We point out some of the inherent properties of bio-oil that create difficulties standing in the way of these applications. Finally, we take a brief look at some processes that aim to valorize bio-oil by conversion to higher value liquid fuel products. Dans cette revue nous nous proposons de dresser un rappel historique des progrès relatifs aux technologies de liquéfaction thermochimiques par pyrolyse rapide, encore appelée pyrolyse flash, de la biomasse pour produire ce que l’on appelle communément une "bio-huile". Nous insisterons sur ses applications comme combustible liquide pour la production de chaleur et d’électricité. Nous ferons ressortir quelques propriétés spécifiques aux bio-huiles qui peuvent créer des difficultés d’usage. Nous terminerons par un bref aperçu de quelques procédés permettant de valoriser la bio-huile en carburants liquides de plus forte valeur ajoutée.

  18. Sodium effects on mechanical performance and consideration in high temperature structural design for advanced reactors

    International Nuclear Information System (INIS)

    Sodium environmental effects are key limiting factors in the high temperature structural design of advanced sodium-cooled reactors. A guideline is needed to incorporate environmental effects in the ASME design rules to improve the performance reliability over long operating times. This paper summarizes the influence of sodium exposure on mechanical performance of selected austenitic stainless and ferritic/martensitic steels. Focus is on Type 316SS and mod.9Cr-1Mo. The sodium effects were evaluated by comparing the mechanical properties data in air and sodium. Carburization and decarburization were found to be the key factors that determine the tensile and creep properties of the steels. A beneficial effect of sodium exposure on fatigue life was observed under fully reversed cyclic loading in both austenitic stainless steels and ferritic/martensitic steels. However, when hold time was applied during cyclic loading, the fatigue life was significantly reduced. Based on the mechanical performance of the steels in sodium, consideration of sodium effects in high temperature structural design of advanced fast reactors is discussed.

  19. Manufacture technique of bronze-iron bimetallic objects found in M27 of Liangdaicun Site, Hancheng, Shaanxi

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Analysis of the fabrication technology of a bronze knife with an iron blade and a bronze Ge with an iron blade, two copper-iron bimetallic wares, unearthed in M27 of Liangdaicun Site, Hancheng of Shaanxi, is performed in this paper by using metallographic, EPMA and AMS-14C dating methods. The micro-structures of the two samples are typical wrought bloomery iron containing a substantial amount of carbon, which is also called carburized steel, made from bloomery iron by cementation in the solid state. The objects can be dated back to the early Spring and Autumn period. This study provides new evidence for understanding the beginning of iron smelting in China. Most of the early known iron wares of the period between the late Western Zhou Dynasty and the early Spring and Autumn were unearthed in the region at the junction of Henan, Shanxi and Shaanxi, at the middle reaches of the Yellow River, suggesting that this region may likely be one of the earliest centers of iron smelting technology in China and deserves further archaeological research. As early iron products were also discovered in the area of the upper reaches of the Yellow River and in Xinjiang, appropriate attention also should be paid to the relationship between these two areas in terms of the origin of iron smelting.

  20. Study on Surface Engineering of Normalized Steels Subjected To Machine Hardening

    Institute of Scientific and Technical Information of China (English)

    N.Alagurmurthi; K.Palaniradja; V.Soundararajan

    2004-01-01

    Engineering the surfaces of components to improve the life and performance of parts used in automotive and aerospace engineering is the active area of research. Suitable Thermal/Mechanical/Thermo mechanical surface engineerin gtreatments will produce extensive rearrangement of atoms in metals and alloys and corresponding marked variations in Physical, Chemical and Mechanical properties. Among the more important of these treatments are heat treatment processes such as hardening by Quenching, Induction hardening and Case Carburizing which rely on phase transformations to produce desired changes in mechanical properties. Other processes where phase transformation occur are casting, welding and machining etc. [1] Phase transformation may be homogeneous or heterogeneous. Homogeneous involvesrear rangements in the structure of the material taking place simultaneously in all parts of the solid, while the heterogeneous transformation involves structural changes which are more localized. Alternatively they could be called as Isothermal and Nonisothermal transformation. But irrespective of the classification, these transformations alter the structure of the material giving rise to changes in the mechanical and physical properties of the processed material. It is of interest to review some consequences of surface modification in isothermal (Normalizing) and nonisothermal transformations (Machining) of low carbon steels.

  1. Study on Surface Engineering of Normalized Steels Subjected To Machine

    Institute of Scientific and Technical Information of China (English)

    Hardening

    2004-01-01

    Engineering the surfaces of components to improve the life and performance of parts used in automotive and aerospace engineering is the active area of research. Suitable Thermal/Mechanical/Thermo mechanical surface engineering treatments will produce extensive rearrangement of atoms in metals and alloys and corresponding marked variations in Physical, Chemical and Mechanical properties. Among the more important of these treatments are heat treatment processes such as hardening by Quenching, Induction hardening and Case Carburizing which rely on phase transformations to produce desired changes in mechanical properties. Other processes where phase transformation occur are casting, welding and machining etc. [1] Phase transformation may be homogeneous or heterogeneous. Homogeneous involves rearrangements in the structure of the material taking place simultaneously in all parts of the solid, while the heterogeneous transformation involves structural changes which are more localized. Alternatively they could be called as Isothermal and Nonisothermal transformation. But irrespective of the classification, these transformations alter the structure of the material giving rise to changes in the mechanical and physical properties of the processed material. It is of interest to review some consequences of surface modification in isothermal (Normalizing) and nonisothermal transformations (Machining) of low carbon steels.

  2. In-situ fabrication of MoSi2/SiC-Mo2C gradient anti-oxidation coating on Mo substrate and the crucial effect of Mo2C barrier layer at high temperature

    Science.gov (United States)

    Liu, Jun; Gong, Qianming; Shao, Yang; Zhuang, Daming; Liang, Ji

    2014-07-01

    MoSi2/SiC-Mo2C gradient coating on molybdenum was in situ prepared with pack cementation process by two steps: (1) carburizing with graphite powder to obtain a Mo2C layer on Mo substrate, and (2) siliconizing with Si powder to get a composite MoSi2/SiC layer on the upper part of Mo2C layer. The microstructure and elemental distribution in the coating were investigated with scanning electron microscopy (SEM), back scattered electron (BSE), energy dispersive spectroscopy (EDS), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Cyclic oxidation tests (at 500 °C, 1200 °C, 1400 °C and 1600 °C) demonstrated excellent oxidation resistance for the gradient composite coating and the mass loss was only 0.23% in 60 min at 1600 °C. XRD, EPMA, thermal dynamic and phase diagram analyses indicated that the Mo2C barrier layer played the key role in slowing down the diffusion of C and Si toward inner Mo substrate at high temperature and principally this contributed to the excellent anti-oxidation for Mo besides the outer MoSi2/SiC composite layer.

  3. Effect of Carbon Sources on the Catalytic Performance of Ni/β-Mo2C.

    Science.gov (United States)

    Zeng, Li-Zhen; Zhao, Shao-Fei; Li, Wei-Shan

    2015-06-01

    In this paper, Ni/β-Mo2C(S) and Ni/β-Mo2C(G) were prepared from solution-derived precursor with two different carbon sources (starch and glucose) and tested as anodic noble-metal-free catalysts in air-cathode microbial fuel cells (MFCs). The carburized catalyst samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET). The activity of the electrocatalyst towards the oxidation of several common microbial fermentation products (formate, lactate, and ethanol) was studied for MFC based on Klebsiella pneumoniae conditions. The composite MFC anodes were fabricated, and their catalytic behavior was investigated. With different carbon sources, the crystalline structure does not change and the crystallinity and surface area increase. The electrocatalytic experiments show that the Ni/β-Mo2C(G) gives the better bio- and electrocatalytic performance than Ni/β-Mo2C(S) due to its higher crystallinity and BET surface area.

  4. Optical characterization of polished Mo2C foil.

    Science.gov (United States)

    Grimes, Jacob; Geerts, W.; Bandyopadhyay, A.; Gutierrez; Radican, K.; Rivera, N.; Holland, P.; Givens, J.; Oyama, Ted

    2003-03-01

    Mo_2C has been in use by industry for a number of years, however its optical properties are previously uncharacterized with no reports of experimentally obtained values for the refraction index(n) and extinction coefficient(k). Toward the goal of identifying the values for these properties several tests are performed on a Molybdenum foil carburized in a stream of 20 molar CH4 in H2 at 1373K. The surface of the sample is polished to an optically flat finish using several diamond disks in an Allied High Tech polisher. X-ray data shows that the remaining surface material is Mo_2C. Ψ and Δ are measured with a Variable Angle Spectroscopic Ellipsometer from 190 to 1700nm. Then n, k, and reflectance are calculated using FilmWizard. The spectra for refraction, extinction, and reflectance of Mo_2C differ greatly from those reported for Mo. Generally they exhibit a quasi-linear character increasing with wavelength with structures in the red and blue parts of the spectra.

  5. Cu-Mo2C/MCM-41: An Efficient Catalyst for the Selective Synthesis of Methanol from CO2

    Directory of Open Access Journals (Sweden)

    Xiaoran Liu

    2016-05-01

    Full Text Available Supported molybdenum carbide (yMo2C/M41 and Cu-promoted molybdenum carbide, using a mechanical mixing and co-impregnation method (xCuyMo2C/M41-M and xCuyMo2C/M41-I on a mesoporous molecular sieve MCM-41, were prepared by temperature-programmed carburization method in a CO/H2 atmosphere at 1073 K, and their catalytic performances were tested for CO2 hydrogenation to form methanol. Both catalysts, which were promoted by Cu, exhibited higher catalytic activity. In comparison to 20Cu20Mo2C/M41-M, the 20Cu20Mo2C/M41-I catalyst exhibited a stronger synergistic effect between Cu and Mo2C on the catalyst surface, which resulted in a higher selectivity for methanol in the CO2 hydrogenation reaction. Under the optimal reaction conditions, the highest selectivity (63% for methanol was obtained at a CO2 conversion of 8.8% over the 20Cu20Mo2C/M41-I catalyst.

  6. Post irradiation examinations of 84F-10A capsule containing uranium-plutonium mixed carbide fuels

    International Nuclear Information System (INIS)

    Two fuel pins filled with uranium-plutonium mixed carbide pellets having different stoichiometry, (U,Pu)C1.0 and (U,Pu)C1.1, were encapsulated in 84F-10A and irradiated in JMTR up to 3.0%FIMA at a peak linear power of 59kW/m. The capsule cooled for ∼4 months was transported to Reactor Fuel Examination Facility and subjected to non-destructive and destructive post irradiation examinations. It was found from the radial cross sections of fuel pins that the helium gap between the pellets and the cladding tube was completely closed. At the central part of the fuel pellets the number of small pores was decreased and the grain growth was observed compared with the outer zone. (U,Pu)C1.1 pellets showed higher fission gas release ratio than (U,Pu)C1.0 pellets because the former had relatively high open porosity. Although slight carburization was observed near the inner surface of cladding tube the interaction did not affect the fuel performance itself. (author)

  7. Reason Analysis and Prevention Methods of Longitudinal Cracking in Shaft Gear%轴齿轮纵裂原因分析及预防措施

    Institute of Scientific and Technical Information of China (English)

    王培科

    2011-01-01

    轴齿轮在渗碳淬火后发生纵裂,通过宏观分析、成分化验、金相检验及硬度测试等方法对纵裂的原因进行了分析.结果表明:带状组织、渗碳层有网状碳化物、大量残余奥氏体及粗大的针状马氏体是导致轴发生纵裂的主要原因.为此,提出了预防措施.%The longitudinal cracking reason of shaft gear were analyzed by means of macro examination, chemical composition analysis, metallographic examination and hardness rest The results indicate that banded structure, network carbide of carburized layer, great quantity of retained austenite and typical coarse needle martensite are all main reasons for longitudinal crack of the shaft gear. Suggestion for producing the shaft gear are proposed for further research.

  8. Various categories of defects after surface alloying induced by high current pulsed electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Dian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Tang, Guangze, E-mail: oaktang@hit.edu.cn [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Gu, Le [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, Mingren [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-10-01

    Highlights: • Four kinds of defects are found during surface alloying by high current electron beam. • Exploring the mechanism how these defects appear after irradiation. • Increasing pulsing cycles will help to get good surface quality. • Choosing proper energy density will increase surface quality. - Abstract: High current pulsed electron beam (HCPEB) is an attractive advanced materials processing method which could highly increase the mechanical properties and corrosion resistance. However, how to eliminate different kinds of defects during irradiation by HCPEB especially in condition of adding new elements is a challenging task. In the present research, the titanium and TaNb-TiW composite films was deposited on the carburizing steel (SAE9310 steel) by DC magnetron sputtering before irradiation. The process of surface alloying was induced by HCPEB with pulse duration of 2.5 μs and energy density ranging from 3 to 9 J/cm{sup 2}. Investigation of the microstructure indicated that there were several forms of defects after irradiation, such as surface unwetting, surface eruption, micro-cracks and layering. How the defects formed was explained by the results of electron microscopy and energy dispersive spectroscopy. The results also revealed that proper energy density (∼6 J/cm{sup 2}) and multi-number of irradiation (≥50 times) contributed to high quality of alloyed layers after irradiation.

  9. Effect of simulated HTGR primary circuit helium on properties of structural alloys

    International Nuclear Information System (INIS)

    The effect of exposure to simulated HTGR primary circuit helium (400 μatm H2/2 μatm H2O/40 μatm CO/0.2 μ atm CO2/20 μatm CH4 in He at 2 atm total pressure) on the properties of structural alloys is studied over the temperature range of 750 to 10500C (1382 to 19220F). Creep-rupture testing is being performed using both single specimen and multispecimen equipment. Specimens are also being exposed unstressed for post-exposure evaluation of oxidation, thermal aging effects and carburization and for evaluating changes in tensile, impact and fatigue properties due to exposure. Some air tests are being performed for comparison. The results to date (exposure times to approximately 10,000 hours) are discussed for a variety of wrought iron- and nickel-based austentic alloys, cast nickel-based alloys, and oxide dispersion strengthened alloys. It generally appears that the environmental effect is significant only in the highest temperature range: thermal aging appears to be the cause of most of the changes seen during lower temperature exposures accomplished to date

  10. Computational Modeling Develops Ultra-Hard Steel

    Science.gov (United States)

    2007-01-01

    Glenn Research Center's Mechanical Components Branch developed a spiral bevel or face gear test rig for testing thermal behavior, surface fatigue, strain, vibration, and noise; a full-scale, 500-horsepower helicopter main-rotor transmission testing stand; a gear rig that allows fundamental studies of the dynamic behavior of gear systems and gear noise; and a high-speed helical gear test for analyzing thermal behavior for rotorcraft. The test rig provides accelerated fatigue life testing for standard spur gears at speeds of up to 10,000 rotations per minute. The test rig enables engineers to investigate the effects of materials, heat treat, shot peen, lubricants, and other factors on the gear's performance. QuesTek Innovations LLC, based in Evanston, Illinois, recently developed a carburized, martensitic gear steel with an ultra-hard case using its computational design methodology, but needed to verify surface fatigue, lifecycle performance, and overall reliability. The Battelle Memorial Institute introduced the company to researchers at Glenn's Mechanical Components Branch and facilitated a partnership allowing researchers at the NASA Center to conduct spur gear fatigue testing for the company. Testing revealed that QuesTek's gear steel outperforms the current state-of-the-art alloys used for aviation gears in contact fatigue by almost 300 percent. With the confidence and credibility provided by the NASA testing, QuesTek is commercializing two new steel alloys. Uses for this new class of steel are limitless in areas that demand exceptional strength for high throughput applications.

  11. Rolling element fatigue testing of gear materials

    Science.gov (United States)

    Nahm, A. H.

    1978-01-01

    Rolling element fatigue lives of nine alloys were evaluated in Rolling Contact (RC) rigs. Test conditions included a Hertzian stress at 4,826 MPa (700 ksi), a rolling speed of 6.23 m/sec (245 in/sec.). Tests were run with a Type I oil (MIL-L-7808G) at room temperature. B-10 lives (10% failure rate) of alloys were compared versus reference alloys, VIM-VAR AISI M-50 and VAR AISI 9310. Six case carburizing alloys (AISI 9310, CBS600, CBS1000M, EX00014, Vasco X-2 and EX00053) and three through-hardening alloys (AISI M-50, VascoMax 350 and Vasco Matrix 2 evaluated, showed RCF performance inferior or equivalent to that of AISI 9310 and AISI M-50. It was also found that the effects of vacuum melting processes, different tempering temperatures, freezing cycle during heat treating, shot peening, gold plating and chrome plating employed in the present investigation did not significantly affect RCF life.

  12. Molybdenum Speciation and its Impact on Catalytic Activity during Methane Dehydroaromatization in Zeolite ZSM-5 as Revealed by Operando X-Ray Methods.

    Science.gov (United States)

    Lezcano-González, Inés; Oord, Ramon; Rovezzi, Mauro; Glatzel, Pieter; Botchway, Stanley W; Weckhuysen, Bert M; Beale, Andrew M

    2016-04-18

    Combined high-resolution fluorescence detection X-ray absorption near-edge spectroscopy, X-ray diffraction, and X-ray emission spectroscopy have been employed under operando conditions to obtain detailed new insight into the nature of the Mo species on zeolite ZSM-5 during methane dehydroaromatization. The results show that isolated Mo-oxo species present after calcination are converted by CH4 into metastable MoCx Oy species, which are primarily responsible for C2 Hx /C3 Hx formation. Further carburization leads to MoC3 clusters, whose presence coincides with benzene formation. Both sintering of MoC3 and accumulation of large hydrocarbons on the external surface, evidenced by fluorescence-lifetime imaging microscopy, are principally responsible for the decrease in catalytic performance. These results show the importance of controlling Mo speciation to achieve the desired product formation, which has important implications for realizing the impact of CH4 as a source for platform chemicals.

  13. Characterization of a Messer – The late-Medieval single-edged sword of Central Europe

    Energy Technology Data Exchange (ETDEWEB)

    Fajfar, Peter; Medved, Jožef; Klančnik, Grega [Department of Materials and Metallurgy, Faculty of Natural Sciences and Engineering, University of Ljubljana, Aškerčeva cesta 12, SI-1000 Ljubljana (Slovenia); Lazar, Tomaž [National Museum of Slovenia, Prešernova cesta 20, SI-1000 Ljubljana (Slovenia); Nečemer, Marijan [Jožef Stefan Institut, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Mrvar, Primož, E-mail: primoz.mrvar@omm.ntf.uni-lj.si [Department of Materials and Metallurgy, Faculty of Natural Sciences and Engineering, University of Ljubljana, Aškerčeva cesta 12, SI-1000 Ljubljana (Slovenia)

    2013-12-15

    Metallurgical characterization of a sword blade fragments dating from the second half of the 15th century found in central Slovenia was performed in order to determine its chemical composition, microstructure, microhardness, and to obtain insight into the methods of manufacture of a late-medieval Messer sword. As the artefact was broken, examinations were limited to six very small fragments that were allowed to be removed from the cutting edge, core and the back of the blade. Light optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, energy dispersive X-ray fluorescence spectrometry, differential scanning calorimetry, thermodynamics approach and Vickers micro-hardness tests were employed to analyze the microstructure and mechanical properties. The results show that the sword was manufactured from a single wrought iron billet. The surface of the sword was carburized. No evidence of quenching was found. The ferritic microstructure is concentrated in the core, and the pearlitic in the outer layer of the blade. All metal fragments contained non-metallic inclusions that were derived mostly from slag and some from hammer scale. - Highlights: • A metallurgical characterization of a medieval sword blade has been performed. • The carbon content decreased from the surface to the core of the blade. • The dominant microstructure in the outer layer is pearlite and in the core is ferrite. • The presence of lump shaped and elongated non-metallic inclusions was observed. • The sword was manufactured from a single wrought iron billet.

  14. Ultrasmall and phase-pure W2C nanoparticles for efficient electrocatalytic and photoelectrochemical hydrogen evolution

    Science.gov (United States)

    Gong, Qiufang; Wang, Yu; Hu, Qi; Zhou, Jigang; Feng, Renfei; Duchesne, Paul N.; Zhang, Peng; Chen, Fengjiao; Han, Na; Li, Yafei; Jin, Chuanhong; Li, Yanguang; Lee, Shuit-Tong

    2016-01-01

    Earlier research has been primarily focused on WC as one of the most promising earth-abundant electrocatalysts for hydrogen evolution reaction (HER), whereas the other compound in this carbide family—W2C—has received far less attention. Our theoretical calculations suggest that such a focus is misplaced and W2C is potentially more HER-active than WC. Nevertheless, the preparation of phase pure and sintering-free W2C nanostructures represents a formidable challenge. Here we develop an improved carburization method and successfully prepare ultrasmall and phase-pure W2C nanoparticles. When evaluated for HER electrocatalysis, W2C nanoparticles exhibit a small onset overpotential of 50 mV, a Tafel slope of 45 mV dec−1 and outstanding long-term cycling stability, which are dramatically improved over all existing WC-based materials. In addition, the integration of W2C nanoparticles with p-type Si nanowires enables highly active and sustainable solar-driven hydrogen production. Our results highlight the great potential of this traditionally non-popular material in HER electrocatalysis. PMID:27752046

  15. 表面处理技术在机械加工中的应用%Application of Surface Treatment Technology in the Mechanical Processing

    Institute of Scientific and Technical Information of China (English)

    李继红; 乔正阳; 乔奇光; 马尚龙; 裘磊

    2013-01-01

    以带小孔的测量座为例,针对其加工精度高、淬火硬度需达55HRC的要求,鉴于普通的切削加工因某些结构和形状而受到限制,采用了“小孔处镀铜防渗碳→渗碳淬火→小孔加工”的方法,实现了在普通设备上采用常用刀具和切削手段即可满足测量座加工要求的目的.将表面处理技术应用于机加工艺中,可以解决机加工艺中的某些难题.%For the measurement base with small hole,it needs processing of high-precision and quenching hardness of 55 HRC.Ordinary cutting work is trapped in some of the specific structure and shape.The process of "anticarburizing copper plating-carburizing and quenching-small-hole machining" was used meeting the requirements of measurement base processed by common equipment using commonly used cutter and cutting.Some problems of machining process can be solved with application of surface treatment technology in the mechanical processing.

  16. Archaeometric study on minting dies produced under papal rule in Ferrara

    Science.gov (United States)

    Monticelli, Cecilia; Balbo, Andrea; Vaccaro, Carmela; Gulinelli, Maria Teresa; Garagnani, Gian Luca

    2013-12-01

    In the Civic Museum of Palazzo Schifanoia in Ferrara, a collection of 1104 coin striking tools is stored. Among these, eight steel dies produced from the 2nd decade of the seventeenth to the half of the eighteenth century, representative of the whole period of activity of the papal mint in Ferrara, have been chosen and studied. In that period, while important innovations in the coin minting technique were introduced in Europe, Ferrara declined from the rank of ducal mint to that of peripheral minting center of the highly centralized Papal States. The dies have been characterized by metallographic, chemical, and microhardness investigations. The results suggest that the dies were obtained by a manual smithing technique consisting in hammer hot forging. The die quality improved with time. In fact, in the period 1619-1622, a hardening treatment for the engraved die end consisting in a simple local carburization coexisted with a more efficient production method, based on the application of a proper final heat treatment. This treatment induced a graded microstructure from the engraved end, with a hard martensitic or bainitic structure, to the opposite end, with a tough ferritic/pearlitic structure. From 1675 onward, the latter production method was applied on all the studied dies. The chemical analysis of the alloys suggest that they were likely obtained from iron ores with a common provenance, while the analysis of the slag inclusions suggests the adoption of a direct method of ironmaking throughout the activity period of the mint.

  17. Determination of the material properties of the different cultivator shares

    Directory of Open Access Journals (Sweden)

    Ebubekir ALTUNTAŞ

    2013-06-01

    Full Text Available In this study, chemical analysis, pulling, hardness test results and spectral analysis of the different cultivator shares of cultivator producers in Amasya and Çorum provinces were evaluated and test results were compared with relevant Turkish Standards. For experiments, the cultivator shares were choosen randomly from A,B, C and D cultivator producers and classified. Chemical analysis revealed SAE 1030, C60, C30 tempered stell types and C10 carburizing steel materials respectively for A, B, C and D cultivator shares. Spectral analysis indicated that cultivator were mainly included medium-carbon steels. All cultivar shares failed to meet recommended Rockwell hardness value of 49 HRC. While the highest hardness was observed in A-1 and C-1 narrow shares with 39.1 HRC, the lowest value was seen in D-2 duck-foot share with 72.88 HRB. According to pulling tests, cultivator shares were found to be complying with relevant reference values indicated in standards.

  18. Scalable production of Cu@C composites for cross-coupling catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Lijuan [Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China); Ming, Hai, E-mail: lunaticmh@163.com [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China)

    2015-10-15

    Highlights: • Cu@C core–shell composite was prepared by reduction of [Cu(NH{sub 3}){sub 4}]{sup 2+} with glucose. • The carbon shell in Cu@C can be tuned to the different degree of carbonization. • The Cu@C composites were utilized to catalyze the C−N cross coupling reaction. • The catalytic ability of Cu@C depends on the degree of shell-carbonization. - Abstract: A novel Cu@C core–shell microstructure was prepared by reduction of [Cu(NH{sub 3}){sub 4}]{sup 2+} with glucose using a mild hydrothermal process. The carbon shell of such Cu@C composite can be tuned to different carbonization degrees just through varying the calcination conditions. The structural properties of as-prepared Cu@C were investigated in detail by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron micrographs (TEM) and Raman spectra. In addition, these Cu@C composites were firstly used to catalyze the C−N cross coupling of amines with iodobenzene. Among them, the catalytic ability of Cu@C composites increased as their surface carbon’s carburization degree improved.

  19. Corrosion Behavior of Surface-treated Ferritic/Martensitic Steel in Liquid Sodium Environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, JeongHyeon; Lee, Jung Ki; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of); Shin, Sang Hun [KAERI, Daejeon (Korea, Republic of)

    2015-10-15

    Their compatibility with sodium is one of issues especially dissolution, chemical reaction, and carbon transfer with impurities, which degraded the mechanical properties. The compatibility of cladding and structural materials with sodium has to be carefully investigated, as sodium could promote corrosion of cladding and structural materials in two ways. One is produced by the dissolution of alloy constituents into the sodium, and the other is produced through a chemical reaction with impurities (especially oxygen and carbon) in the sodium environment. Gr.92 is known as compatible in sodium environment because this steel possesses excellent properties. For instance, Gr.92 has high creep and tensile strength, low thermal expansion coefficient. In the Ultra-long Cycle Fast Reactor (UCFR) which is developed in UNIST, however, cladding is exposed long-term in high temperature liquid sodium environment. So, it is very important to investigate the corrosion-related behavior such as surface corrosion rate, carburization, decarburization and mechanical properties for its operation time. In this study, as-received and surface-treated Gr.92 specimen in the oxygen-saturated liquid sodium were examined at high temperature for 300h. The impedance results reveal the information for the corrosion behavior in liquid sodium. Also, microstructure results reveal the information for the maintenance of coating and role of coating.

  20. ECOLOGICAL CONTROL EQUIPMENT AND TECHNOLOGY OF UNDERWATER VEGETATION DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    V. TITINSCHNEIDER

    2013-12-01

    Full Text Available The excess of aquatic submerse vegetation development carries to the reduction of the real rearing area for the piscicultural material from the production farms and allow nestling of the ichthyophages bird species that decrease the fish production. Aquatic submerse vegetation stumble the utilization of aquatic zones for recreation and also wright function of basins utilized for the electric energy production, of micro electricity works through obstruction of the dams grid. The control of the aquatic submerse vegetation development, for Myriophyllum verticillatum, Ceratophyllum submersum, Urticularia vulgaris, Potamogeton natans, Nimphoides peltata species it is accomplish through the removing of some parts of these, preferably with all the stump system. Usually, these its accomplish with the floating equipments fit up with the thermic engines and the propulsion and governating elements who have harm over the fish and some others aquatic organisms through the noise, the displacing a large quality of water caused of propulsion systems and through the noxes elimination (flue, carburant trails, etc.. These technologies reside from the evacuation of the aquatic submerse vegetation and the stump systems of these with the help of an adjustable rake, hang up from the coast by a rope, wrapped to a drummer, who is trained by a motto-propeller group with a small installed power.

  1. Evaluation of Tensile Property of Austenitic Alloys Exposed to High-Temperature S-CO{sub 2} Environment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyunmyung; Lee, Ho Jung; Jang, Changheui [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-12-15

    Super-critical CO{sub 2} (S-CO{sub 2}) Brayton cycle has been considered to replace the current steam Rankine cycle in Sodium-cooled Fast Reactor (SFR) in order to improve the inherent safety and thermal efficiency. Several austenitic alloys are considered as the structural materials for high temperature S-CO{sub 2} environment. Microstructural change after long-term exposure to high temperature S-CO{sub 2} environment could affect to the mechanical properties. In this study, candidate materials (austenitic stainless steels and Alloy 800HT) were exposed to S-CO{sub 2} to assess oxidation resistance and the change in tensile properties. Loss of ductility was observed for some austenitic stainless steels even after 250 h exposure. The contribution of S-CO{sub 2} environment on such changes was analyzed based on the characterization of the surface oxide and carburization of the materials in which 316H and 800H showed different oxidation behaviors.

  2. Évaluation du poids socio-économique et environnemental de la filière biodiesel en France

    Directory of Open Access Journals (Sweden)

    Raes Thierry

    2013-09-01

    Full Text Available La filière EMHV (ester méthylique d’huile végétale ou biodiesel poursuit une expansion continue en France depuis près de 20 ans et a pris un essor particulier à partir de 2008 suite à la fixation d’objectifs d’incorporation de biodiesel dans les carburants. Cette étude a été menée afin d’évaluer l’impact socio-économique et environnemental de la filière EMHV en France en 2010 et de comparer cet impact à celui de la filière diesel en France en 2010. L’approche retenue est une évaluation de la filière sur l’ensemble de la chaîne de valeur afin de quantifier les valeurs caractéristiques économiques (valeur ajoutée, surplus économique global, emploi et les externalités environnementales. Elle donne une image de la filière française en 2010.

  3. Welding metallurgy of nickel alloys in gas turbine components

    Energy Technology Data Exchange (ETDEWEB)

    Lingenfelter, A. C., LLNL

    1997-05-21

    Materials for gas turbine engines are required to meet a wide range of temperature and stress application requirements. These alloys exhibit a combination of creep resistance, creep rupture strength, yield and tensile strength over a wide temperature range, resistance to environmental attack (including oxidation, nitridation, sulphidation and carburization), fatigue and thermal fatigue resistance, metallurgical stability and useful thermal expansion characteristics. These properties are exhibited by a series of solid-solution-strengthened and precipitation-hardened nickel, iron and cobalt alloys. The properties needed to meet the turbine engine requirements have been achieved by specific alloy additions, by heat treatment and by thermal mechanical processing. A thorough understanding of the metallurgy and metallurgical processing of these materials is imperative in order to successfully fusion weld them. This same basic understanding is required for repair of a component with the added dimension of the potential effects of thermal cycling and environmental exposure the component will have endured in service. This article will explore the potential problems in joining and repair welding these materials.

  4. Facile Route to Prepare TaC,NbC and WC Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    DU Yinxiao; LEI Ming; YANG Hui; WANG Xuefei

    2008-01-01

    By a novel solid-state reaction process using amorphous C3N4 (a-C3N4) and transition metal oxides as starting reagents,cubic TaC,NbC and hexagonal WC nanoparticles were successfully synthesized at 1150 ℃.The products were characterized by power X-ray diffraction (XRD),field-emission scanning electron microscope (FE-SEM),energy-dispersive X-ray spectroscopy (EDX),transmission electron microscopy (TEM) and high-resolution TEM (HRTEM).The experimental resuits show that a-C3N4 obtained by the reaction between C3N3Cl3 and Li3N is a highly efficient carburation reagent and the transition metal oxides are completely transformed into the corresponding metal carbide nanoparticles at 1150 ℃,respectively,which is significantly lower than that reported for the traditional preparation of carbides,typically> 1600 ℃.The TaC,NbC and WC nanoparticles are found to have an average particle size of 10 nm,15 nm and 8 nm by TEM observation,respectively.

  5. 高强度钢的超高周疲劳裂纹扩展模型研究%THE MODEL OF VHCF CRACK PROPAGATION FOR HIGH STRENGTH STEEL

    Institute of Scientific and Technical Information of China (English)

    黄志勇; 陈伟; 吴铁鹰

    2011-01-01

    当疲劳寿命在106或107周时,W(o)hler S-N曲线被看作渐近于水平轴,107的疲劳强度被看成是疲劳极限.现代应用要求延长零件的工作寿命,实际齿轮部件应用超过107循环的疲劳失效.论文应用压电超声疲劳试验机对经过热处理和渗碳处理后的低铬合金钢材料进行研究,采用红外摄像仪观测试件表面的温度场随疲劳裂纹萌生和扩展的过程.试验条件是室温,应力比为0.1(R=0.1),频率为20 kHz.通过对表面渗碳处理后试件的断口分析,探讨表面渗碳处理、微观结构和与杂质有关的断裂机理,根据Paris公式建立超高周疲劳裂纹扩展模型.对裂纹扩展过程中裂纹尖端的塑性区的分析结果,结合传热学原理,建立热耗散模型,有限元方法的数值解结果较好地符合红外摄像仪的观测的试验结果.%When fatigue life is beyond 106 or 107 , the W(O)hler S-N curve was always considered to be asymptotic in horizontal axis,but the fatigue behaviour over 107 cycles can not be neglected. Carburized process hardens surface of structure parts in order to improve wear and fatigue resistance. A piezoelectric gigacycle fatigue machine is employed to the tests in VHCF regime with 20 kHz frequency and at stress ratio R=0.1 ,room temperature. The effects of heat and carburized treatment on VHCF fatigue strength are investigated by test method. The infrared camera is applied to study the energy dissipation during the tests after calibration by blackbody. The cycle of crack initiation can be determined by the temperature increasing within several cycles near end of test. Through Scanning Electron Microscopy (SEM) analysis, the mainly parameters have been obtained to model the Crack Propagation (CP) based on Paris law,which permits estimating energy dissipation whose power and position are variable with crack propagation. The temperature distribution and evolution of specimen surface can be calculated by the numerical method

  6. Impact environnemental d'une désulfuration poussée des gazoles Environmental Impact of Gaz Oil Desulfurization

    Directory of Open Access Journals (Sweden)

    Armengol C.

    2006-11-01

    Full Text Available En une dizaine d'années, le diesel a connu un développement spectaculaire sur les marchés automobile français et européen et pourrait atteindre, en 1995, la moitié des immatriculations de véhicules particuliers en France et le quart en Europe de l'Ouest. Cette situation n'est évidemment pas sans poser de problèmes. Problèmes environnementaux puisque le moteur diesel est une source plus importante d'émissions d'oxydes d'azote et de particules que le convertisseur essence, mais également au niveau de l'industrie du raffinage qui, en France, n'est plus en mesure de satisfaire la demande en gazole. De plus, à compter du 1er octobre 1996, la teneur en soufre du gazole routier ne devra pas excéder 0,05 %, conformément aux nouvelles spécifications européennes. Cette perspective de production de carburants fortement désulfurés va affecter directement l'équilibre en hydrogène de la raffinerie et donc les autoconsommations et les émissions de CO2. L'objectif de cette étude est de mesurer l'impact sur l'environnement d'une réduction de la teneur en soufre des gazoles de 0,3 à 0,05 %. Le bilan est réalisé sur l'ensemble de la filière énergétique, depuis l'extraction du pétrole jusqu'à la combustion du carburant dans le moteur. Les gains et les pertes en termes de pollution locale ou globale sont évalués suivant la nature de l'hydrogène utilisé (oxydation partielle de résidus sous vide ou de charbon, reformage à la vapeur de gaz naturel ou de naphta électrolyse et la nature de la charge à traiter (gazole straight run ou light cycle oil lors de l'hydrodésulfuration. Over the past decade, diesel had made large advances in the French and European automobile markets. In 1995, diesel could account for half of all private vehicle registrations in France, and a quarter in Western Europe. This situation inevitably raises a number of problems : environmental problems, because the diesel engine emits more nitrogen oxides and

  7. Reactive boundary layers in metallic rolling contacts

    International Nuclear Information System (INIS)

    thorough investigation into the effects of residual austenite on the properties of this material. The high-performance alternative steels, 36NiCrMoV1-5-7 (hot working steel) and 45SiCrMo6 (spring steel), were heat treated as recommended by their respective manufacturers, and were not case-hardened. The selection of materials with and materials without case-hardening allows for an investigation into whether or not case-hardening is even necessary to deliver acceptable friction behaviour and wear performance. Elemental analyses were conducted by multiple methods to ensure accurate results. Residual austenite contents of the steels and the depth profiles of residual stresses were determined by X-Ray diffraction (XRD), for 20MnCr5 ranging from approximately 6 - 14 vol.%, and under 2 vol.% for the alternative alloys. Hardness profiles were taken from the testing surfaces into the material core. The carburization of 20MnCr5 led to higher hardness and the greater concentration of carbon in the carburization zone more representative of a hardened SAE E52100, or 100Cr6/102Cr6, than of a non-case-hardened 20MnCr5. Residual stresses from machining and case-hardening were measured directly at the sample surface. The high-performance steels fulfilled manufacturer expectations in terms of elemental content, with hardness values between 50 - 55 HRC and strongly martensitic microstructure character. With characterization of the chosen materials complete, the materials could then be subjected to pre-conditioning. The first pre-conditioning method involved targeted generation of cold work hardening as induced boundary layers to protect the contact zone against wear. Work hardening was identified both by variations in residual stress profiles, i.e. the introduction of beneficial compressive residual stresses, and hardness increases in the contact zone, providing enhanced wear resistance. Parameters for work hardening were further optimized to reduce damage to the surface substrates of the

  8. Uso de etanol carburado en motores Diesel

    Directory of Open Access Journals (Sweden)

    Rodríguez Luis Arnoby

    1990-06-01

    Full Text Available Este trabajo se ejecutó en el Taller de Maquinaria Agrícola de la Facultad de Ciencias Agropecuarias de la Universidad Nacional de Colombia, Seccional Palmira. Un motor diesel de 2 cilindros, 1260 cm3 y relación de comprensión 23:1, fue alimentado mediante un sistema dual formado por el sistema de inyección para ACPM y un sistema de carburación para etanol y mezclas etanol-agua. En primer término se varió el avance de la inyección entre 18 y 26° APMS(Antes de Punto Muerto Superior con el fin de determinar el avance óptimo de inyección en el motor original y el motor alimentado con el sistema dual. Con base en el punto de máxima potencia, se seleccionaron 20 y 22" como avances óptimos. En la segunda prueba, al operar el motor con carga y velocidad variables y alimentarlo con cuatro combustibles (ACPM, etanol y mezclas etanol- agua con 20 y 40 % agua, se incrementaron la velocidad en 10% la potencia máxima en 6.5% ; y el torque máximo en 3.73%, desde el motor original al sistema dual alimentado con la mezcla carburada de 40% agua. La mayor sustitución de combustible se presentó a alta velocidad donde se reemplazó hasta el 32 % de ACPM por etanol. Solo a alta velocidad se justifica la sobrealimentación con etanol carburado. En este rango se presentaron aumentos de potencia, velocidad, par torsor y sustitución de combustible.This work was performed in the Agricultural Mechanics Shop of the Universidad Nacional of Colombia in Palmira. A two-cylinder, 1260 cm3 diesel engine with a compression ratio of 23:1 was fueled by a dual system formed by its injection system for diesel oil and a carburation system for ethanol and ethanol-water blends. In a first test, m e injection advance was varied between 18 and 26 o BTDC (Before Top Dead Center to determine the optimum injection advance in the original engine and the engine fueled with the dual system. According to the maximum power point, 20 and 22° BTDC were selected as the optimum

  9. Technical analysis of failure of catalyst support of reformer furnace tube of a hydrogen generation unit%制氢装置转化炉炉管催化剂支托失效分析

    Institute of Scientific and Technical Information of China (English)

    齐庆轩; 冯岩

    2012-01-01

    The damages of catalyst support of reformer furnace tubes of No. 1 hydrogen generation unit in SINOPEC Shijiazhuang Refining & Chemical Co. , Ltd. in two maintenances were introduced. The composition analysis of catalyst support, the study on the macroscopic photo, the analysis of damaged surface of catalyst support of Incoloy800H, the metallographic analysis, energy dispersion spectrum (EDS) analysis, and scanning electron microscope analysis of support' s section area as well as study on the anti-caburization performances of Cr25Ni20 and Incoloy800H materials have concluded the following: The damages of catalyst support was caused by surface carburization of catalyst support material under high temperature in the presence of hydrogen, which led to phase changes of material surface structure, material stratification, loosening and bulging of surface material structure, large amount of micro-crackings in grain boundary at surface area and eduction of large amount of carbides. All these will reduce the ductility and plasticity of material. Therefore, it is difficult for the catalyst support to restore its original state after thermal expansion, which explains why there are some bulges on the tube of failed support. The anti-carburization performance is greatly improved after application of Cr25Ni20 steel material.%对两次检修中所发现的中国石油化工股份有限公司石家庄炼化分公司l号制氢装置转化炉炉管催化剂支托出现损坏的情况做了介绍,并对两种批次的催化剂支托进行了成分分析,对使用Incoloy800H材料、损坏严重的催化剂支托表面宏观照片进行了分析,对损伤支托的横截面进行金相、电镜及能谱检验分析.通过对Cr25Ni20和lncoloy800H两种材料的抗渗碳能力的比较,得出了以下结论:催化剂支托损伤的原因是材料在含氢高温环境下发生了表面渗碳现象,直接导致材料表面组织相变、材料分层、表现材料组织疏松和隆起,

  10. Preparation and study of the nitrides and mixed carbide-nitrides of uranium and of plutonium; Preparation et etude des nitrures et carbonitrures d'uranium et de plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Anselin, F. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-06-01

    , avec ou sans additif de frittage. On a observe un effet benefique, mais non reproductible, de traces d'oxyde. Les meilleurs resultats ont ete obtenus pour UN pur, a 1600 C (96 pour cent de la densite theorique) a condition d'utiliser une poudre bien caracterisee. Le critere utilise est la largeur integrale des raies de diffraction X. Les composes UN et PuN sont entierement miscibles avec les carbures correspondants. Ceci permet de preparer par diffusion en phase solide, vers 1400 C, des carbonitrures de formule generale (U,Pu) (C,N). Le frittage de ces carbonitrures s'apparente a celui des carbures, si la teneur en azote est faible; en particulier le nickel est un additif de frittage efficace. Pour les teneurs elevees, le frittage est comparable a celui des nitrures purs.

  11. Synthesis and photoluminescence properties of in-situ synthesized core–shell (m-VC@C) nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Mahajan, Mani [School of Physics and Materials Science, Thapar University, Patiala 147004 (India); Lalla, N.P. [UGC-DAE Consortium for Scientific Research, University Campus, Indore 452017 (India); Singh, K. [School of Physics and Materials Science, Thapar University, Patiala 147004 (India); Pandey, O.P., E-mail: oppandey@thapar.edu [School of Physics and Materials Science, Thapar University, Patiala 147004 (India)

    2015-06-15

    Core–shell structure of mesoporous vanadium carbide nanoparticles encapsulated with carbon layers (m-VC@C) have been successfully synthesized by single-step, non-toxic and economical route. The texture, morphology and optical properties of the obtained product were studied by various characterization techniques. X-ray diffraction analysis shows that the optimization of reaction time facilitates the reduction process of the precursor and hence carburization. High resolution transmission electron microscopy analysis reveals that the synthesized vanadium carbide nanoparticles with average size of 30–40 nm were encapsulated in 20–22 layers of carbon. High thermal stability of the obtained product was found at high temperatures. N{sub 2} adsorption/desorption isotherm shows that the sample has a specific surface area of 62.4560 m{sup 2}/g and pore volume 0.30 cm{sup 3}/g with pore size in the mesoporous range (3–14 nm). The formation mechanism of carbide and carbon layer has been explained on the basis of experimental results. The as-obtained m-VC@C shows good absorption and luminescence properties. Its application in photocatalytic degradation of the organic pollutant has been studied. - Highlights: • VC@C nanocomposite has been synthesized using in situ chemical-reduction route. • The synthesis of VC@C powder through this technique is our first reporting. • The VC@C is stable at higher temperatures than the reported ones. • PL emission intensity shows that the VC@C is luminescent material.

  12. Investigation of Contact Fatigue of High Strength Steel Gears Subjected to Surface Treatment

    Science.gov (United States)

    Dimitrov, L.; Michalopoulos, D.; Apostolopoulos, Ch. Alk.; Neshkov, T. D.

    2009-10-01

    In this paper the contact fatigue resistance of gearwheel teeth, subjected to shot-peening treatment, was investigated experimentally and analytically. The main objective was the evaluation and prediction of fatigue crack initiation, propagation, direction, and rate. A specially designed experimental rig was used to test a number of spur gears with the following characteristics: (a) unhardened, thermally untreated unpeened surfaces, (b) thermally treated unpeened surfaces, (c) unhardened peened surfaces, and (d) thermally treated peened surfaces. The theoretical model assumed initiation and propagation of surface cracks of gears operating in the elastohydrodynamic lubrication regime while loading was due to simultaneous rolling and sliding. Finite element modeling was used for the calculation of the stress field at the gear teeth. Comparison of the experimental and analytical results showed considerable improvement in the contact fatigue strength of thermally treated gear teeth and especially those that underwent shot peening, which increased surface durability. The residual stresses induced by shot peening are mainly effective in stopping microcrack propagation. When shot peening is applied on thermally untreated gear teeth surface, it increases the contact fatigue life of the material by 17% at 7 × 105 loading cycles. If shot peening is applied on carburized gear teeth surfaces, it increases the surface fatigue life by approximately 8% at 106 cycles. Contact fatigue and eventual pitting are treated as a normal consequence of the operation of machine elements. To study this failure process different types of testing machines have been designed. The purpose of this paper is the presentation and evaluation of a new design experimental rig for studying contact fatigue damage of gear teeth subjected to different load patterns.

  13. Comparison of mechanical and corrosion behaviour of Alloy 800 H and the new alloy AC 66

    International Nuclear Information System (INIS)

    In coal gasification plants based on nuclear process heat, materials are subjected to high temperature corrosion in process gas atmosphere at 750 to 900 deg. C. The process gas consists of steam, CO, CH4, CO2 and, depending on the gasified coal, low or high H2S-concentrations. The service problems can be divided as follows: 1. Gas-metal interaction: (a) high temperature corrosion; (b) sulphidation; (c) carburization; (d) internal oxidation or internal sulphidation. 2. Ash (slag)-metal interaction: (a) corrosion in molten salts; (b) erosion. 3. Mechanical loading: (a) embrittlement; (b) thermal fluctuations/strain fluctuations; (c) low cycle fatigue; (d) high temperature creep. Therefore materials for heat exchangers must be resistant to these types of high temperature corrosion and they should also have adequate creep rupture strength. Some commercial alloys and various model alloys were exposed to a process gas atmosphere to determine the corrosion behaviour and also stressed mechanically to investigate the interaction of high temperature creep behaviour and corrosion. The tests were carried out for a total period of 10,000 h and specimens were taken out after periods of 1000, 3000, 5000 and 10,000 h. A programme for the development of alloys was started with the aim of optimizing the chemical composition resulting in a good high temperature corrosion resistance and adequate mechanical properties, particularly high creep strength. However, the material must be such that it can be deformed to tubes. Compared with Incoloy 800, one of the new and optimized model alloys (30-32% Ni, 25-27% Cr, and Ce, Fe-balance) exhibits a very good corrosion resistance even when sulphur rich coal is gasified. The creep rupture strength at 900 deg. C is in the range of the creep strength for Incoloy 800. 29 figs

  14. The effects of laser surface modification on the microstructure and properties of gas-nitrided 42CrMo4 steel

    Science.gov (United States)

    Kulka, M.; Panfil, D.; Michalski, J.; Wach, P.

    2016-08-01

    Gas nitriding, together with gas carburizing and gas carbonitriding, was the most commonly used thermochemical treatment, resulting in many advantageous properties: high hardness, enhanced corrosion resistance, considerably improved wear resistance and fatigue strength. However, an unfavorable increase in the thickness of compound layer (ε+γ‧) close to the surface was observed after conventional gas nitriding. This was the reason for undesirable embrittlement and flaking. Therefore, a controlled gas nitriding was developed, reducing the thickness of compound layer. In this study, laser modification with or without re-melting was carried out after the controlled gas nitriding in order to change microstructure and to improve wear resistance. The effects of laser beam power on the dimensions of simple laser tracks were analyzed. It enabled to control the obtained microstructure and to select the laser processing parameters during producing the multiple tracks. Such a treatment was necessary to investigate wear resistance. Laser re-melting resulted in dissolving the majority of nitrides as well as in producing the martensitic structure in re-melted and heat-affected zones. This treatment required argon shielding in order to protect the surface against uncontrolled oxidation. Laser heat treatment without re-melting caused a modification of ε nitrides which became less porous and more compact. Simultaneously, it provided heat-affected zone with the partially martensitic structure of increased hardness below compound zone. Argon shielding was not necessary in this case because of the resistance of nitrides to oxidation during rapid heating and cooling. All the laser-modified layers, irrespective if the nitrided layer was re-melted or not, were characterized by the improved wear resistance compared to the typical gas-nitrided layer.

  15. Review on physical metallurgical factors of surface hardening heat treatment for gears%对齿轮表面硬化热处理物理”金因素的评述

    Institute of Scientific and Technical Information of China (English)

    陈国民

    2015-01-01

    In order to increase loading capacity and service life of transmission gears, surface hardening processes are now widely used, so as to get high surface hardness and core toughness, thereby gaining comprehensive mechanical properties.Relationship of physical metallurgical factors and their characteristics of the hardening case, matrix and transition zone of the carburizing, nitriding and induction hardening gears and the service condition, stress state, as well as heat treatment process is analyzed, and finally puts forward some improving suggestion.%为了提高齿轮的承载能力和使用寿命,普遍采用表面硬化热处理工艺,以得到高的表面硬度(强度)和良好的心部韧性,从而获得强韧结合的综合力学性能。显然,要研究齿轮的强度,首先就应当研究硬化层及心部的强度特性及其影响因素。本文就齿轮渗碳、渗氮及感应淬火的硬化层、心部基体及过渡区的物理冶金因素与齿轮的服役条件、受力状况及热处理工艺的关系进行了分析,并提出一些改进建议。

  16. 某微型车变速器齿轮断齿失效分析%Broken tooth failure analysis of transmission gear

    Institute of Scientific and Technical Information of China (English)

    李强; 汪辉; 陈启略

    2014-01-01

    For a mini-car road tests appear in the third gear transmission gear breakage problem by observing the fracture gear and chemical composition, hardness, microstructure inspection and scanning electron microscopy (SEM), the results showed that the third gear fracture is fatigue fracture, fatigue source is located at the root of the tooth, where the surface remained deep cutting marks. By repeating bending stress and stress concentration cause fatigue fracture. For the reason of the gear failure, improving the treatment time and improve the depth of the carburized layer and other measures to avoid the occurrence of a gear breakage.%针对某微型车在道路试验中出现的变速器三档齿轮断裂的问题,通过对断裂齿轮的断口观察及化学成分、硬度、金相组织的检验及扫描电镜分析(SEM),结果表明,三档齿轮断裂为疲劳断裂,疲劳源位于齿根处,此处表面残留着较深切削刀痕,由多次重复的弯曲应力和应力集中造成疲劳断裂。针对齿轮失效原因,采用改进热处理工艺时间及渗碳层深度等措施,避免了齿轮断裂现象的发生。

  17. Failure Analysis on Fracture of Automobile Gearbox Output Shafts%汽车变速箱输出轴断裂失效分析

    Institute of Scientific and Technical Information of China (English)

    周洪涛; 崔兰芳; 李洪; 孙献国; 张磊

    2016-01-01

    针对某汽车变速箱输出轴断裂失效问题,运用失效分析方法,开展了宏观痕迹分析、断口分析、化学成分分析、金相检验,硬度测试及氢含量测定.结果表明:汽车变速箱输出轴断裂为延迟断裂,输出轴尾部螺纹处表面渗碳层较高硬度的回火马氏体组织为延迟断裂提供"必要条件",这与螺纹处局部处理工艺的控制不合理相关;一定的外加静拉应力、自身残余应力和氢含量为延迟断裂的"充分条件".最后提出了改进与预防措施.%Aiming at the fracture failure of an automobile gearbox output shaft,the failure analysis was done to the output shaft through macroscopic trace analysis, fracture analysis, chemical composition analysis, metallographic examination,hardness test and hydrogen content test.The results show that the fracture of the gearbox output shaft was a kind of delayed fracture.The tempering martensite structure with high hardness of the carburized layer in the threaded end of the output shaft provideds 'necessary condition'for the delayed fracture, which was caused by the inappropriate local processing of the screw thread.And a certain foreign static tensile stress,its own residual stress and hydrogen content provided'sufficient condition'for the delayed fracture.Finally, some improving and preventive measures were put forward.

  18. Hydrogen and carbon interaction in a FeNi alloy with a vacancy

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Estela; Jasen, Paula; Juan, Alfredo [Departamento de Fisica, Universidad Nacional del Sur, Bahia Blanca (Argentina); Gonzalez, Gabriel [Departamento de Ingenieria Mecanica, Facultad Regional Bahia Blanca, Universidad Tecnologica Nacional, Bahia Blanca (Argentina); Moro, Lilian [Departamento de Fisica, Universidad Nacional del Sur, Bahia Blanca (Argentina); Departamento de Ingenieria Mecanica, Facultad Regional Bahia Blanca, Universidad Tecnologica Nacional, Bahia Blanca (Argentina)

    2009-06-15

    The bonding of hydrogen and carbon to Fe and Ni in a 50:50 alloy is analysed using density functional calculations. The changes in the electronic structure of a L1{sub 0} alloy upon C and H introduction at a vacancy region are addressed and a comparison with H or C in pure metals is drawn. H in bulk FeNi alloy with a vacancy locates at a tetrahedral site shifted towards the vacancy. Instead, C prefers an octahedral site (Fe based). The vacancy acts as strong traps of both C and H. Fe-Ni atoms are initially more strongly bonded to each other due to the vacancy formation. Consequently, the Fe-Fe, Fe-Ni and Ni-Ni bond strengths are diminished as new metal-C or metal-H bonds are formed. The most affected bond is the Fe-Ni, whose overlap population decreases by 72%. An analysis of the orbital interaction reveals that the Fe-H bonding involves mainly the Fe 4s, H 1s and Ni 4s orbitals. In the case of the sequential absorption, the C-H interaction is almost zero at a distance of 2.72A. The main interactions of these interstitials are developed with either Fe or Ni. We also consider the absorption sequence (H first or C first) and its influence on the electronic structure. Our results could be relevant to understand some steps of the carburization process during thermal cracking operations where hydrogen atoms are present. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Effect of sodium environment on the creep-rupture and low-cycle fatigue behavior of austenitic stainless steels

    International Nuclear Information System (INIS)

    Austenitic stainless steels used for in-core structural components, piping, valves, and the intermediate heat exchanger in Liquid-Metal Fast-Breeder Reactors (LMFBRs) are subjected to sodium at elevated temperatures and to complex stress conditions. As a result, the materials can undergo compositional and microstructural changes as well as mechanical deformation by creep and cyclic fatigue processes. Information is presented on the creep-rupture and low-cycle fatigue behavior of Types 304 and 316 stainless steel in the solution-annealed condition and after long-term exposure to flowing sodium. The nonmetallic impurity-element concentrations in the sodium were controlled at levels similar to those in EBR-II primary sodium. Strain-time relationships developed from the experimental creep data were used to generate isochronous stress-creep strain curves as functions of sodium-exposure time and temperature. The low-cycle fatigue data were used to obtain relationships between plastic strain range and cycles-to-failure based on the Coffin-Manson formalism and a damage-rate approach developed at ANL. An analysis of the cyclic stress-strain behavior of the materials showed that the strain-hardening rates for the sodium-exposed steels were larger than those for the annealed material. However, the sodium-exposed specimens showed significant softening, as evidenced by the lower stress at half the fatigue life. Microstructural information obtained from the different specimens suggests that crack initiation is more difficult in the long-term sodium-exposed specimens when compared with the solution-annealed material. Based on the expected carbon concentrations in LMFBR primary system sodium, moderate carburization of the austenitic stainless steels will not degrade the mechanical properties to a significant extent, and therefore, will not limit the performance of out-of-core components

  20. Theoretical and experimental study of multilayers interferential reflectors for neutrons: SUPERMIRRORS

    International Nuclear Information System (INIS)

    The aim of this study was the realization of (Ni-Ti) supermirror neutron guides which have good performances both optically and morphologically. To achieve this, we closed in gradually to evaluate better fundamental and technological problems. In the beginning, the study was oriented towards decoupling the effects of the different defects in the (Ni-Ti) multilayer and to tackle them one by one. In the first part, we present the classical neutrons guides and their limits and compare them with the supermirror guides and their advantages. Next, we describe the neutron optics formalism in analogy with electromagnetic classical optics, in particular X ray radiation. We have essentially employed the Grazing Angle Neutron Reflectometry technique for the investigation of our samples. These experimental results have been complemented by those of other surface investigation techniques: -optical, magnetic, electronic and ionic ones. The results were in almost overall agreement. More precisely, the neutron reflectivity profiles were treated by using the Abeles matrix formalism for an electromagnetic wave in S polarized state. In the third time, we present the whole of the experimental results obtained. The combination of the latter two effects (hydrogenation of titanium and carburation of nickel) which has not yet been achieved constitutes a direct continuation of this work. This could improve even further both the neutron reflectivity and the critical angle by coupling Mezei-Dagleish and Hayter-Mook stacks. A simulation has shown that a stack of this type consists of 15 bilayers (NixC-TiH2) has the same reflectivity as a stack of 60 bilayers (Ni-Ti). (author)

  1. Effect of Al2O3 Binder on the Precipitated Iron-Based Catalysts for Fischer-Tropsch Synthesis

    Institute of Scientific and Technical Information of China (English)

    Hai-Jun Wan; Bao-Shan Wu; Xia An; Ting-Zhen Li; Zhi-Chao Tao; Hong-Wei Xiang; Yong-Wang Li

    2007-01-01

    A series of iron-based Fischer-Tropsch synthesis (FTS) catalysts incorporated with Al2O3 binder were prepared by the combination of co-precipitation and spray drying technology. The catalyst samples were characterized by using N2 physical adsorption, temperature-programmed reduction/desorption (TPR/TPD) and M(o)ssbauer effect spectroscopy (MES) methods. The characterization results indicated that the BET surface area increases with increasing Al2O3 content and passes through a maximum at the Al2O3/Fe ratio of 10/100 (weight basis). After the point, it decreases with further increase in Al2O3 content. The incorporation of Al2O3 binder was found to weaken the surface basicity and suppress the reduction and carburization of iron-based catalysts probably due to the strong K-Al2O3 and Fe-Al2O3 interactions. Furthermore, the H2 adsorption ability of the catalysts is enhanced with increasing Al2O3 content. The FTS performances of the catalysts were tested in a slurry-phase continuously stirred tank reactor (CSTR) under the reaction conditions of 260 ℃, 1.5 MPa, 1000 h-1 and molar ratio of H2/CO 0.67 for 200 h. The results showed that the addition of small amounts of Al2O3 affects the activity of iron-based catalysts to a little extent. However, with further increase of Al2O3 content, the FTS activity and water gas shift reaction (WGS) activity are decreased severely. The addition of appropriate Al2O3 do not affect the product selectivity, but the catalysts incorporated with large amounts of Al2O3 have higher selectivity for light hydrocarbons and lower selectivity for heavy hydrocarbons.

  2. Study of Manganese Promoter on a Precipitated Iron-Based Catalyst for Fischer-Tropsch Synthesis

    Institute of Scientific and Technical Information of China (English)

    Zhichao Tao; Yong Yang; Chenghua Zhang; Tingzhe Li; Mingyue Ding; Hongwei Xiang; Yongwang Li

    2007-01-01

    The effects of Manganese (Mn) incorporation on a precipitated iron-based Fischer-Tropsch synthesis (FTS) catalyst were investigated using N2 physical adsorption,air differential thermal analysis (DTA),H2 temperature-programmed reduction(TPR),and Mossbauer spectroscopy.The FTS performances of the catalysts were tested in a slurry phase reactor.The characterization results indicated thatMn increased the surface area of the catalyst,and improved the dispersion of α-Fe2O3 and reduced its crystallite size as a result of the high dispersion effect of Mn and the Fe-Mn interaction.The Fe-Mn interaction also suppressed the reduction of α-Fe2O3 to Fe3O4,stabilized the FeO phase,and(or)decreased the caxburization degree of the catalysts in the H2 and syngas reduction processes.In addition,incorporated Mn decreased the initial catalyst activity,but improved the catalyst stability because Mn restrained the reoxidation of iron carbides to FeaO4,and improved further carburization of the catalysts.Manganese suppressed the formation of CH4 and increased the selectivity to light olefins(C2=-4),but it had little effect on the selectivities to heavy(C5+)hydrocarbons.All these results indicated that the strong Fe-Mn interaction suppressed the chemisorptive effect of the Mn as all electronic promoter,to some extent,in the precipitated iron-manganese catalyst system.

  3. A geographical method to assess technological hazards.The example of the storage and the distribution of the fuel oils in the urban region of Ile-de-France

    Directory of Open Access Journals (Sweden)

    Sandrine Glatron

    2001-07-01

    Full Text Available Les risques technologiques majeurs sont pris en compte dans la planification urbaine par le biais d’une limitation de l’usage des sols autour des établissements dangereux, car le niveau du risque dépend en grande partie de l’occupation des sols. Dans les régions à forte densité urbaine, cette restriction justifie la volonté du planificateur de délocaliser les établissements dangereux. Mais c’est faire peu de cas des éventuels transferts de risques vers un autre maillon de la chaîne industrielle : le transport des matières dangereuses. Avec l’aide d’un SIG, qui décrit précisément l’usage des sols, une méthode est développée pour comparer les risques- site (autour d’un établissement industriel dangereux et les risques-transport (le long du parcours des véhicules livrant les matières dangereuses. Cette méthode permet de comptabiliser les dommages survenant à l’intérieur des espaces potentiellement touchés par les conséquences d’un accident et de travailler à l’échelle régionale (aire de chalandise. Il autorise les calculs réitérés d’où la possibilité de simuler les risques pour différentes implantations d’un établissement dangereux et, ainsi, de vérifier la pertinence des propositions de délocalisation. Le stockage et la distribution par la route des carburants ont été pris comme exemple car ils concernent de vastes régions urbaines comme l’Ile-de-France.

  4. Conversion chimique du gaz naturel Chemical Conversion of Natural Gas

    Directory of Open Access Journals (Sweden)

    Chaumette P.

    2006-11-01

    Full Text Available Dans cet article sont passés en revue les travaux de recherche et développement et les procédés existants dans le domaine de la conversion chimique du gaz naturel. Les deux voies possibles, conversion directe du méthane et conversion indirecte, via le gaz de synthèse, sont présentées. Tant la préparation d'hydrocarbures utilisables comme carburants, que celle des composés de bases pour la pétrochimie ou la chimie sont évoquées. L'accent est mis sur l'étape clé du développement de chaque procédé qui, selon le produit visé, consiste en la mise au point d'un nouveau système catalytique, en un changement de la technologie du réacteur, ou en la mise au point d'une section fractionnement moins complexe. This article reviews the research and development work and the existing processes in the area of chemical conversion of natural gas. The two possible methods, direct conversion of methane and indirect conversion via synthesis gas, are discussed. The preparation of hydrocarbons that can be used as fuels and the production of building blocks for the petrochemical and chemical industries are both dealt with. The accent is placed on the key step in developing each process. Depending on the target product, this key step consists in working out a new catalytic system, changing reactor technology or engineering a less complex fractionation section.

  5. Etude du comportement chimique des additifs dispersants sur les surfaces métalliques. Réaction des fonctions amide sur l'alumine Study of the Chemical Behavior of Dispersant Additives on Metal Surfaces. Reaction of Amide Functions on Aluminum

    Directory of Open Access Journals (Sweden)

    Nechtschein J.

    2006-11-01

    Full Text Available Ce travail a pour objet la mise en évidence des réactions chimiques qui apparaissent entre les fonctions amides qui entrent dans la constitution de nombreuses formules de dispersants pour carburants et lubrifiants et la surface de l'aluminium. On montre que la réaction des amides sur la surface de l'alumine s'opère en deux étapes: La première étape, ou étape de chimisorption, fait intervenir les sites de Lewis et les groupements OH voisins de l'alumine pour fixer la fonction amide par le groupement carbonyle (liaison acide-base de Lewis et par l'azote (liaison hydrogène. La deuxième étape, ou étape d'hydrolyse, conduit à la formation d'un carboxylate de surface et d'une amine. The aim of this study was to analyze the chemical reactions that appear between the amide functions entering into the composition of numerous dispersant formulas for fuels and lubricants and the surface of aluminum. The reactions of amides on an aluminum surface is shown to take place in two stages. The first stage, or chemisorption stage, involves Lewis sites and the OH groups next to the aluminum oxide sa as to fix the amide function by the carbonyl group (Lewis acid-basic bonds and by nitrogen (hydrogen bond. The second stage, or hydrolysis stage, leads to the formation of a surface carboxylate and an amine.

  6. Water–gas shift catalysis over transition metals supported on molybdenum carbide

    Energy Technology Data Exchange (ETDEWEB)

    Kaiwalya, Sabnis D; Cui, Yanran; Akatay, M. Cem; Shekhar, Mayank; Lee, Wen-Sheng; Miller, Jeffrey T.; Delgass, W. Nicholas; Ribeiro, Fabio

    2015-11-01

    We report here that WGS rates per total surface area at 120 degrees C, 7% CO, 22% H2O, 8.5% CO2, 37% H-2 for Pt, Au, Pd and Ni supported over MO2C were 4-8 times higher than those of the commercial Cu/ZnO/Al2O3 catalyst. In agreement with previous literature, the WGS rate per total moles of Pt over Pt/MO2C at 120 degrees C has been shown to be higher than on any Pt/Metal oxide catalyst. We have made use of systematic changes in the apparent kinetic parameters with various admetals (decrease in apparent CO order and apparent activation energy and increase in apparent H2O order compared to unpromoted MO2C) to conclude that the function of the rate-promoting admetals is to enhance the relative surface concentration of the adsorbed CO, thereby leading to a promotion in the WGS rate per total surface area of the catalyst. Temperature programmed desorption of CO was used to show that the CO adsorption properties of MO2C were modified by the various admetals by creating new metallic sites. In situ X-ray absorption on Pt and Au and STEM-EELS experiments showed that the supported Au nanoparticles over MO2C decrease in average particle size from similar to 9 nm to 3 nm after a 600 degrees C carburization pretreatment. Pt was also shown to have assumed a stable structure at 600 degrees C in the form of a Pt-Mo alloy. We suggest that MO2C can be used to synthesize thermally robust supported metal catalysts.

  7. Diameter-Specific Growth of Semiconducting SWNT Arrays Using Uniform Mo2C Solid Catalyst.

    Science.gov (United States)

    Zhang, Shuchen; Tong, Lianming; Hu, Yue; Kang, Lixing; Zhang, Jin

    2015-07-22

    Semiconducting single-walled nanotube (s-SWNT) arrays with specific diameters are urgently demanded in the applications in nanoelectronic devices. Herein, we reported that by using uniform Mo2C solid catalyst, aligned s-SWNT (∼90%) arrays with narrow-diameter distribution (∼85% between 1.0 and 1.3 nm) on quartz substrate can be obtained. Mo2C nanoparticles with monodisperse sizes were prepared by using molybdenum oxide-based giant clusters, (NH4)42[Mo132O372(H3CCOO)30(H2O)72]·10H3CCOONH4·300H2O(Mo132), as the precursor that was carburized by a gas mixture of C2H5OH/H2 during a temperature-programmed reduction. In this approach, the formation of volatile MoO3 was inhibited due to the annealing and reduction at a low temperature. As a result, uniform Mo2C nanoparticles are formed, and their narrow size-dispersion strictly determines the diameter distribution of SWNTs. During the growth process, Mo2C selectively catalyzes the scission of C-O bonds of ethanol molecules, and the resultant absorbed oxygen (Oads) preferentially etches metallic SWNTs (m-SWNTs), leading to the high-yield of s-SWNTs. Raman spectroscopic analysis showed that most of the s-SWNTs can be identified as (14, 4), (13, 6), or (10, 9) tubes. Our findings open up the possibility of the chirality-controlled growth of aligned-SWNTs using uniform carbide nanoparticles as solid catalysts for practical nanoelectronics applications.

  8. In Situ FT-IR Spectroscopic Studies of CO Adsorption on Fresh Mo2C/Al2O3 Catalyst.

    Science.gov (United States)

    Wu, Weicheng; Wu, Zili; Liang, Changhai; Chen, Xiaowei; Ying, Pinliang; Li, Can

    2003-07-24

    The surface sites of supported molybdenum carbide catalyst derived from different synthesis stages have been studied by in situ FT-IR spectroscopy using CO as the probe molecule. Adsorbed CO on the reduced passivated Mo2C/Al2O3 catalyst gives a main band at 2180 cm(-1), which can be assigned to linearly adsorbed CO on Mo(4+) sites. The IR results show that the surface of reduced passivated sample is dominated by molybdenum oxycarbide. However, a characteristic IR band at 2054 cm(-1) was observed for the adsorbed CO on MoO3/Al2O3 carburized with CH4/H2 mixture at 1033 K (fresh Mo2C/Al2O3), which can be assigned to linearly adsorbed CO on Mo(δ+) (0 Mo2C/Al2O3. Unlike adsorbed CO on reduced passivated Mo2C/Al2O3 catalyst, the IR spectra of adsorbed CO on fresh Mo2C/Al2O3 shows similarity to that on some of the group VIII metals (such as Pt and Pd), suggesting that fresh carbide resembles noble metals. To study the stability of Mo2C catalyst during H2 treatment and find proper conditions to remove the deposited carbon species, H2 treatment of fresh Mo2C/Al2O3 catalyst at different temperatures was conducted. Partial amounts of carbon atoms in Mo2C along with some surface-deposited carbon species can be removed by the H2 treatment even at 450 K. Both the surface-deposited carbon species and carbon atoms in carbide can be extensively removed at temperatures above 873 K.

  9. Surface and subsurface oxidation of Mo2C/Mo(100): low-energy ion-scattering, auger electron, angle-resolved X-ray photoelectron, and mass spectroscopy studies.

    Science.gov (United States)

    Ovári, László; Kiss, János; Farkas, Arnold P; Solymosi, Frigyes

    2005-03-17

    The interaction of oxygen with a carburized Mo(100) surface was investigated at different temperatures (300-1000 K). The different information depths of low-energy ion-scattering (LEIS) spectroscopy, with topmost layer sensitivity, Auger electron spectroscopy (AES), and angle-resolved X-ray photoelectron spectroscopy (ARXPS) allowed us to discriminate between reactions on the topmost layer and subsurface transformations. According to ARXPS measurements, a carbide overlayer was prepared by the high-temperature decomposition of C(2)H(4) on Mo(100), and the carbon distribution proved to be homogeneous with a Mo(2)C stoichiometry down to the information depth of XPS. O(2) adsorbs dissociatively on the carbide layer at room temperature. One part of the chemisorbed oxygen is bound to both C and Mo sites, indicated by LEIS. Another fraction of oxygen atoms probably resides in the hollow sites not occupied by C. The removal of C from the outermost layer by O(2), in the form of CO, detected by mass spectroscopy (MS), was observed at 500-600 K. The carbon-depleted first layer is able to adsorb more oxygen compared to the Mo(2)C/Mo(100) surface. Applying higher doses of O(2) at 800 K results in the inward diffusion of O and the partial oxidation of Mo atoms. This process, however, is not accompanied by the removal of C from subsurface sites. The depletion of C from the bulk starts only at 900 K (as shown by MS, AES, and XPS), very probably by the diffusion of C to the surface followed by its reaction with oxygen. At T(ads) = 1000 K, the carbon content of the sample, down to the information depth of XPS, decreased further, accompanied by the attenuation of the C concentration gradient and a substantially decreased amount of oxygen.

  10. High temperature corrosion of metals

    International Nuclear Information System (INIS)

    This paper covers three main topics: 1. high temperature oxidation of metals and alloys, 2. corrosion in sulfur containing environments and 3. structural changes caused by corrosion. The following 21 subjects are discussed: Influence of implanted yttrium and lanthanum on the oxidation behaviour of beta-NiA1; influence of reactive elements on the adherence and protective properties of alumina scales; problems related to the application of very fine markers in studying the mechanism of thin scale formation; oxidation behaviour of chromia forming Co-Cr-Al alloys with or without reactive element additions; growth and properties of chromia-scales on high-temperature alloys; quantification of the depletion zone in high temperature alloys after oxidation in process gas; effects of HC1 and of N2 in the oxidation of Fe-20Cr; investigation under nuclear safety aspects of Zircaloy-4 oxidation kinetics at high temperatures in air; on the sulfide corrosion of metallic materials; high temperature sulfide corrosion of Mn, Nb and Nb-Si alloys; corrosion behaviour or NiCrAl-based alloys in air and air-SO2 gas mixtures; sulfidation of cobalt at high temperatures; preoxidation for sulfidation protection; fireside corrosion and application of additives in electric utility boilers; transport properties of scales with complex defect structures; observations of whiskers and pyramids during high temperature corrosion of iron in SO2; corrosion and creep of alloy 800H under simulated coal gasification conditions; microstructural changes of HK 40 cast alloy caused by exploitation in tubes in steam reformer installation; microstructural changes during exposure in corrosive environments and their effect on mechanical properties; coatings against carburization; mathematical modeling of carbon diffusion and carbide precipitation in Ni-Cr-based alloys. (MM)

  11. Carbon formation and metal dusting in hot-gas cleanup systems of coal gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; DeVan, H.J.; Judkins, R.R. [and others

    1995-06-01

    The product gas resulting from the partial oxidation of carboniferous materials in a gasifier consists predominantly of CO, CO{sub 2}, H{sub 2}, H{sub 2}O, CH{sub 4}, and, for air-blown units, N{sub 2} in various proportions at temperatures ranging from about 400 to 1000{degree}C. Depending on the source of the fuel, smaller concentrations of H{sub 2}S, COS, and NH{sub 3} can also be present. The gas phase is typically characterized by high carbon and sulfur, but low oxygen, activities and, consequently, severe degradation of the structural and functional materials used in the gasifier can occur. Therefore, there are numerous concerns about materials performance in coal gasification systems, particularly at the present time when demonstration-scale projects are in or nearing the construction and operation phases. This study focused on the subset of materials degradation phenomena resulting from carbon formation and carburization processes, which are related to potential operating problems in certain gasification components and subsystems. More specifically, it examined the current state of knowledge regarding carbon deposition and a carbon-related degradation phemonenon known as metal dusting as they affect the long-term operation of the gas clean-up equipment downstream of the gasifier and addressed possible means to mitigate the degradation processes. These effects would be primarily associated with the filtering and cooling of coal-derived fuel gases from the gasifier exit temperature to as low as 400{degree}C. However, some of the consideratins are sufficiently general to cover conditions relevant to other parts of gasification systems.

  12. Recent Developments in Simulations of Internal Flows in High Pressure Swirl Injectors Progrès récents dans la simulation des écoulements dans les injecteurs haute pression à swirl

    Directory of Open Access Journals (Sweden)

    Ren W. M.

    2006-12-01

    Full Text Available As far as design of direct injection spark ignited engine is concerned, the fuel injector is a key component for success. Internal flow simulation is the best adapted tool for the design of the internal geometry of the injector. First, simulations of the internal flow will be discussed, especially transient stages of an injection event as well as the prediction of the fuel characteristics at the nozzle exit. Second, a coupling between internal flow calculations and instability model in order to predict initial spray characteristics will be suggested. L'injecteur est un des éléments clés dans la conception des moteurs essence à injection directe. La modélisation de l'écoulement dans l'injecteur guide la conception de la géométrie interne. Dans une première partie, les aspects de cette modélisation seront soulevés, à savoir, l'écoulement transitoire en début et fin d'injection, ainsi que la prédiction des caractéristiques du carburant à la sortie de l'injecteur qui va conditionner les caractéristiques du spray. Dans une deuxième partie, nous évoquerons les théories d'instabilités à l'origine de la formation des sprays, ainsi que l'approche employée pour prédire les caractéristiques des gouttes générées.

  13. The influence of welding and post heat treatment parameters on the diffusion and precipitation processes in dissimilar metal joints of a 1% and a 12% Cr-steel

    International Nuclear Information System (INIS)

    The influences of different weld metals, welding processes and post weld heat treatments (PWHT) on mechanical properties, carbon diffusion and precipitation processes were investigated by studying dissimilar metal welds between the cast steel GS-17 CrMoV 5 11 (1% Cr) and the steel X 20 CrMoV 12 1 (12% Cr). By means of tensile and impact tests, metallographic investigation, hardness measurements, electron beam X-ray microanalysis and transmission electron microscope examination changes in the welded joints were shown after different PWHT's as well as after creep tests. It was found that the joint with a 5% CrMoV-weld metal shows higher yield and rupture strength than the joint with a 12% CrMoV-weld metal. With increasing heat input during PWHT the strength decreases for both welds, but always remains higher than the values of the base materials. During PWTH as well as during service at elevated temperatures carbon diffuses from the lower chromium material to the higher chromium material. Width and carbon concentration of the carburized and decarburized zones depend on the heat input. A simple diffusion model was developed to describe the carbon profile for any annealing time and temperature. The consequence of the decarburization is a microstructural change in the heat effected zone of the cast steel. During longer annealing the fine M2C-carbides dissolve and coarse M6C-crbides form, resulting in a lower creep ductility of this zone. (orig.) With 19 refs., 15 tabs., 104 figs

  14. Nanodiamond for tuning the properties of energetic composites.

    Science.gov (United States)

    Pichot, Vincent; Comet, Marc; Miesch, Julien; Spitzer, Denis

    2015-12-30

    Bismuth oxide (Bi2O3) particles were coated by detonation nanodiamonds. The resulting nanocomposite materials were mixed with an aluminum nanopowder (≈ 100 nm) to prepare nanothermites, with reduced sensitivity to friction and electrostatic discharge (ESD). The use of nanodiamond for this purpose is reported here for the first time. Their numerous qualities such as their small size, antifriction properties and thermal conductivity make them ideal candidates. Small amounts of detonation nanodiamonds allow obtaining impressive desensitization, making thus modified Bi2O3/Al nanothermite safe to handle. A composition containing around 1 wt.% of nanodiamond has a sensitivity threshold to friction superior to 100 N instead of 5 N for the thermite without nanodiamond. Furthermore, the sensitivity threshold to electrostatic discharge increases to 20 times when the nanodiamond content reaches 1.8 wt.%. The antifriction properties of nanodiamond limit the scratching of Bi2O3 surface by Al particles. The desensitization to ESD is observed for a sufficient coverage of the oxide particles (1.8 wt.% of ND), which restrains the effect of the melt dispersion mechanism of aluminum and prevents the mixing of the oxidizing and the reducing parts of the composites. A good reactivity of the thermite could be maintained for nanodiamond content up to 2.6 wt.%. The carburizing of aluminum coming on contact with nanodiamond during the thermite reaction could be evidenced by X-ray Diffraction and calorimetry measurements and also participates to the desensitization of the nanothermite. This kind of desensitization by using detonation nanodiamond can also be applied to other nanothermites having low sensitivity threshold to friction and ESD. PMID:26184802

  15. Sodium quality control; French developments from Rapsodie to EFR

    International Nuclear Information System (INIS)

    In order to operate in reliable and safe conditions a Sodium Fast Reactor, it is necessary to master the quality of the coolant. The chemical control of sodium is performed versus the different chemical compounds : oxygen (corrosion control), hydrogen (detection of the sodium-water reaction), and to a less degree carbon (carburization, decarburization phenomena). Moreover, other detrimental effects could be avoided: plugging of narrow sections, loss of heat transfer efficiency in heat exchangers, contamination and dosimetry,...Oxygen and moisture are introduced mainly during handling operations; hydrogen is due to aqueous corrosion of the Steam Generator Unit and thermal decomposition of hydrazine, used to control the oxygen content in the water. The purification of oxygen and hydrogen is performed satisfactorily thanks to cold traps and mainly because of the fact that the solubilities are nearly nil for temperatures close to the fusion point, i.e. 97.8oC. This paper deals with the developments of the purification systems for the primary and intermediate circuits of a SFR. Basis studies were carried out to understand the basic mechanisms of crystallization of sodium oxide and sodium hydride and to establish their respective nucleation and growth kinetics. Then, new concepts were developed for Phenix, Superphenix and EFR in order to provide high efficiency, large filling rate and reliability in operation. The methodology of development, based on calculations, tests on mock-up, will be addressed. Thanks to these developments, sodium purification was never considered as a key issue during steady state operation and purification campaigns necessary to deal with the main pollutions ie sodium-water reaction or air ingress. The sodium purification always allowed to fulfil the operational requirements. (author)

  16. Fabrication of a tantalum-clad tungsten target for LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, A.T., E-mail: atnelson@lanl.gov [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); O' Toole, J.A.; Valicenti, R.A. [Accelerator Operations and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Maloy, S.A. [Civilian Nuclear Program Office, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2012-12-15

    Development of a solid state bonding technique suitable to clad tungsten targets with tantalum was completed to improve operation of the Los Alamos Neutron Science Centers spallation target. Significant deterioration of conventional bare tungsten targets has historically resulted in transfer of tungsten into the cooling system through corrosion resulting in increased radioactivity outside the target and reduction of delivered neutron flux. The fabrication method chosen to join the tantalum cladding to the tungsten was hot isostatic pressing (HIP) given the geometry constraints of a cylindrical assembly and previous success demonstrated at KENS. Nominal HIP parameters of 1500 Degree-Sign C, 200 MPa, and 3 h were selected based upon previous work. Development of the process included significant surface engineering controls and characterization given tantalums propensity for oxide and carbide formation at high temperatures. In addition to rigorous acid cleaning implemented at each step of the fabrication process, a three layer tantalum foil gettering system was devised such that any free oxygen and carbon impurities contained in the argon gas within the HIP vessel was mitigated to the extent possible before coming into contact with the tantalum cladding. The result of the numerous controls and refined techniques was negligible coarsening of the native Ta{sub 2}O{sub 5} surface oxide, no measureable oxygen diffusion into the tantalum bulk, and no detectable carburization despite use of argon containing up to 5 ppm oxygen and up to 40 ppm total CO, CO{sub 2}, or organic contaminants. Post bond characterization of the interface revealed continuous bonding with a few microns of species interdiffusion.

  17. Fabrication of a tantalum-clad tungsten target for LANSCE

    Science.gov (United States)

    Nelson, A. T.; O'Toole, J. A.; Valicenti, R. A.; Maloy, S. A.

    2012-12-01

    Development of a solid state bonding technique suitable to clad tungsten targets with tantalum was completed to improve operation of the Los Alamos Neutron Science Centers spallation target. Significant deterioration of conventional bare tungsten targets has historically resulted in transfer of tungsten into the cooling system through corrosion resulting in increased radioactivity outside the target and reduction of delivered neutron flux. The fabrication method chosen to join the tantalum cladding to the tungsten was hot isostatic pressing (HIP) given the geometry constraints of a cylindrical assembly and previous success demonstrated at KENS. Nominal HIP parameters of 1500 °C, 200 MPa, and 3 h were selected based upon previous work. Development of the process included significant surface engineering controls and characterization given tantalums propensity for oxide and carbide formation at high temperatures. In addition to rigorous acid cleaning implemented at each step of the fabrication process, a three layer tantalum foil gettering system was devised such that any free oxygen and carbon impurities contained in the argon gas within the HIP vessel was mitigated to the extent possible before coming into contact with the tantalum cladding. The result of the numerous controls and refined techniques was negligible coarsening of the native Ta2O5 surface oxide, no measureable oxygen diffusion into the tantalum bulk, and no detectable carburization despite use of argon containing up to 5 ppm oxygen and up to 40 ppm total CO, CO2, or organic contaminants. Post bond characterization of the interface revealed continuous bonding with a few microns of species interdiffusion.

  18. Insights on finite size effects in ab initio study of CO adsorption and dissociation on Fe 110 surface

    Science.gov (United States)

    Chakrabarty, Aurab; Bouhali, Othmane; Mousseau, Normand; Becquart, Charlotte S.; El-Mellouhi, Fedwa

    2016-08-01

    Adsorption and dissociation of hydrocarbons on metallic surfaces represent crucial steps on the path to carburization, eventually leading to dusting corrosion. While adsorption of CO molecules on Fe surface is a barrier-less exothermic process, this is not the case for the dissociation of CO into C and O adatoms and the diffusion of C beneath the surface that are found to be associated with large energy barriers. In practice, these barriers can be affected by numerous factors that combine to favour the CO-Fe reaction such as the abundance of CO and other hydrocarbons as well as the presence of structural defects. From a numerical point of view, studying these factors is challenging and a step-by-step approach is necessary to assess, in particular, the influence of the finite box size on the reaction parameters for adsorption and dissociation of CO on metal surfaces. Here, we use density functional theory (DFT) total energy calculations with the climbing-image nudged elastic band method to estimate the adsorption energies and dissociation barriers for different CO coverages with surface supercells of different sizes. We further compute the effect of periodic boundary condition for DFT calculations and find that the contribution from van der Waals interaction in the computation of adsorption parameters is important as they contribute to correcting the finite-size error in small systems. The dissociation process involves carbon insertion into the Fe surface causing a lattice deformation that requires a larger surface system for unrestricted relaxation. We show that, in the larger surface systems associated with dilute CO-coverages, C-insertion is energetically more favourable, leading to a significant decrease in the dissociation barrier. This observation suggests that a large surface system with dilute coverage is necessary for all similar metal-hydrocarbon reactions in order to study their fundamental electronic mechanisms, as an isolated phenomenon, free from

  19. Electrochemical Impedance Response of the surface treated FMS in Liquid Sodium Environment

    International Nuclear Information System (INIS)

    HT9 and Gr.92 are known as compatible in sodium environment because the usual refueling time of SFRs is designed about 54 months. It is very important to investigate the corrosion-related behavior such as surface corrosion rate, carburization, decarburization and mechanical properties for its operation time. SiC and Si3N4 CVD coating for decarburization barrier on the surface of FMS is considered in this study. The decarburization process where dissolved carbon near the specimen surface disused in to the liquid sodium. This process can originate from the difference between dissolved carbon in the material and liquid sodium. A compatibility test the cladding tube revealed that a decrease of the mechanical property instigated by the aging proves governed the whole mechanical property. To monitor the corrosion behavior of these candidate materials in sodium environment, Electrochemical Impedance Spectroscopy (EIS) method is first introduced and investigated in this study. The compatibility of cladding and structural materials with sodium has to be carefully investigated, as sodium could promote corrosion of cladding and structural materials in two ways. One is produced by the dissolution of alloy constituents into the sodium, and the other is produced through a chemical reaction with impurities (especially oxygen and carbon) in the sodium environment. EIS test with pre-oxidized Gr. 92 specimen in 200 .deg. C liquid sodium environment was carried out in this study. A clear Nyquist and Bode plots were obtained in liquid metal environment and the resistance of sodium and the oxide, and the capacitance of the oxide were measured from this result

  20. Laser Surface Treatment of Hydro and Thermal Power Plant Components and Their Coatings: A Review and Recent Findings

    Science.gov (United States)

    Mann, B. S.

    2015-11-01

    High-power diode laser (HPDL) surface modification of hydro and thermal power plant components is of the utmost importance to minimize their damages occurring due to cavitation erosion, water droplet erosion, and particle erosion (CE, WDE, and PE). Special emphasis is given on the HPDL surface treatment of martensitic and precipitate-hardened stainless steels, Ti6Al4V alloy, plasma ion nitro-carburized layers, high pressure high velocity oxy-fuel and twin-wire arc sprayed coatings. WDE test results of all these materials and coatings in `untreated' and `HPDL- treated at 1550 °C' conditions, up to 8.55 million cycles, are already available. Their WDE testing was further continued up to 10.43 million cycles. The X20Cr13 and X10CrNiMoV1222, the most common martensitic stainless steels used in hydro and thermal power plants, were HPDL surface treated at higher temperature (1650 °C) and their WDE test results were also obtained up to 10.43 million cycles. It is observed that the increased HPDL surface temperature from 1550 to 1650 °C has resulted in significant improvement in their WDE resistances because of increased martensitic (ά) phase at higher temperature. After conducting long-range WDE tests, the correlation of CE, WDE, and PE resistances of these materials and protective coatings with their mechanical properties such as fracture toughness and microhardness product, ultimate resilience, modified resilience, and ultimate modified resilience has been reviewed and discussed. One of the edges of a 500 MW low pressure steam turbine moving blade (X10CrNiMoV1222 stainless steel) was HPDL surface treated at 1550 °C and its radii of curvatures and deflections were measured. These were compared with the data available earlier from a flat rectangular sample of similar composition and identical HPDL surface temperature.

  1. Electrochemical Impedance Response of the surface treated FMS in Liquid Sodium Environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Hyeon; Shin, Sang Hun; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-05-15

    HT9 and Gr.92 are known as compatible in sodium environment because the usual refueling time of SFRs is designed about 54 months. It is very important to investigate the corrosion-related behavior such as surface corrosion rate, carburization, decarburization and mechanical properties for its operation time. SiC and Si{sub 3}N{sub 4} CVD coating for decarburization barrier on the surface of FMS is considered in this study. The decarburization process where dissolved carbon near the specimen surface disused in to the liquid sodium. This process can originate from the difference between dissolved carbon in the material and liquid sodium. A compatibility test the cladding tube revealed that a decrease of the mechanical property instigated by the aging proves governed the whole mechanical property. To monitor the corrosion behavior of these candidate materials in sodium environment, Electrochemical Impedance Spectroscopy (EIS) method is first introduced and investigated in this study. The compatibility of cladding and structural materials with sodium has to be carefully investigated, as sodium could promote corrosion of cladding and structural materials in two ways. One is produced by the dissolution of alloy constituents into the sodium, and the other is produced through a chemical reaction with impurities (especially oxygen and carbon) in the sodium environment. EIS test with pre-oxidized Gr. 92 specimen in 200 .deg. C liquid sodium environment was carried out in this study. A clear Nyquist and Bode plots were obtained in liquid metal environment and the resistance of sodium and the oxide, and the capacitance of the oxide were measured from this result.

  2. Final Technical Report: Intensive Quenching Technology for Heat Treating and Forging Industries

    Energy Technology Data Exchange (ETDEWEB)

    Aronov, Michael A.

    2005-12-21

    standard dies by at least 50%. Dies provided by an AST customer, made of plain carbon 1045 steel and used for pellet manufacturing outperformed the standard dies by more than 100%. Concrete crusher liner wear plates provided by an EHT customer and made of 1045 steel, had the same surface hardness as the plates made of more expensive, pre-hardened high alloy HARDOX-500 material supplied by a Swedish company and used currently by the EHT customer. The 1045 material intensively quenched wear plates are currently in the field. Concrete block molding machine wear plates provided by an IQT customer and made of 8620 steel were processed at the AST production IQ system using a 40% reduced carburization cycle. An effective case depth in the intensively quenched wear plates was the same as in the standard, oil quenched parts. Base keys provided by an EHT customer and made of 8620 steel were processed using a 40% reduced carburization cycle. The intensively quenched parts showed the same performance as standard parts. IQT introduced the IQ process in heat treat practices of three commercial heat-treating shops: Akron Steel Treating Co., Summit Heat Treating Co. and Euclid Heat Treating Co. CWRU conducted a material characterization study for a variety of steels to develop a database to support changing/modification of recognized standards for quenching steel parts. IQT conducted a series of IQ workshops, published seven technical papers and participated in ASM Heat Treating Society conference and exposition and in Furnace North America Show. IQT designed and built a fully automated new IQ system installed at the Center for Intensive Quenching. This system includes the following major components: a stand-alone 1,900-gallon IQ water system, a 24'' x 24'' atmosphere pit furnace, and an automated load transfer mechanism. IQT established a ''Center for Intensive Quenching'' at the AST facilities. The 4,000 square feet Center includes the following

  3. Hydrogen and Nitrogen Control in Ladle and Casting Operations

    Energy Technology Data Exchange (ETDEWEB)

    Richard J. Fruehan; Siddhartha Misra

    2005-01-15

    In recent years there has been an increasing demand to reduce and control the amount of dissolved gases in steel. Hydrogen and nitrogen are two of the most important gases which when dissolved in liquid steel affect its properties significantly. Several steelmaking additions have been investigated in this research for their effect on the hydrogen and nitrogen content of steels. It has been established that calcium hydroxide (hydrated lime) acts as a source of hydrogen. Carburizers, such as metallurgical coke, were found to result in no hydrogen pickup when added to liquid steel. Addition of petroleum coke, on the other hand, increased the hydrogen content of liquid steel. Ferroalloy such as medium carbon ferromanganese when added to the liquid iron was found to increase its nitrogen content, the increase being proportional to the amount of ferroalloy added. Similarly, addition of pitch coke, which had a significant nitrogen impurity, increased the nitrogen content of liquid iron. A mathematical model was developed to quantify the absorption of nitrogen and hydrogen from the air bubbles entrained during tapping of liquid steel. During the bottom stirring of liquid metal in a ladle, the inert gas escaping from the top displaces the slag layer and often forms an open eye. The absorption of atmospheric nitrogen through the spout eye was estimated for different slag thickness and gas flow rate. The ultimate goal of this research was to develop a comprehensive set of equations which could predict the nitrogen and hydrogen pickup from their various sources. Estimates of hydrogen and nitrogen pickup during the steel transfer operations such as tapping and ladle stirring and the predicted pickup from steelmaking additions were integrated into empirical equations. The comprehensive model is designed to predict the gas pickup under varying operating conditions such as the metal oxygen and sulfur content, the total tapping or stirring time, the stirring gas flow rate and the

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

    International Nuclear Information System (INIS)

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

  5. Summary of Studies of Aging and Environmental Effects on Inconel 617 and Haynes 230

    International Nuclear Information System (INIS)

    A number of very high temperature helium-cooled reactors have been built and operated for extended periods. The helium coolant in the primary circuit has been found to contain low levels of impurities after steady-state operation that can lead to an environmental degradation of the high temperature alloys used for internals and heat exchangers. Depending on the impurity concentration and the temperature, high temperature alloys can undergo oxidation, carburization, or decarburization. The concentration of H2O and CO is of particular interest because they essentially control the oxygen partial pressure and carbon activity, respectively. The optimum coolant chemistry for long-term stability of high temperature alloys is slightly oxidizing and results in formation of a tenacious and protective Cr2O3 scale. The most critical metallic component of the Next Generation Nuclear Plant (NGNP) is the heat exchanger. Inconel 617 is the primary candidate alloy for this application because of its superior creep resistance. The mechanisms of environmental interaction between this alloy and prototype Very High Temperature Reactor (VHTR) helium chemistries have been extensively studied. A modified type of Ellingham diagram that maps the ranges of carbon activity and oxygen partial pressure that result in each of the degradation mechanisms has been developed. The NGNP materials program has designed and built three test loops to extend previous studies on environmental effects of prototype impure helium on Inconel 617 by increasing temperatures and using test coupons that incorporate fusion welds in controlled impurity experiments. In addition, parallel studies have been initiated with a less well-characterized alloy, Haynes 230. The goal of this work is to determine the range of gas chemistries that give rise to stable oxide formation for these alloys at temperatures up to 1000 C. Stability of the microstructure and properties of Inconel 617 and Haynes 230 after extended exposure to

  6. 09 CuPCrNi-A与316 L异种钢的焊接工艺及接头组织性能研究%Research on welding process and microstructure and properties of welded joint of 09 CuPCrNi-A and 316 L dissimilar steel

    Institute of Scientific and Technical Information of China (English)

    周方明; 程瑞强; 吴兴祥; 朱正祥

    2016-01-01

    The dissimilar steel(09CuPCrNi-A and 316L)of SCR device of the marine diesel engine was welded by FCAW method.When the dissimilar steel is welded,there are the following problems:the welded metal easi-ly produces hot crack during the process of welding because of the different thermal conductivity and linear ex-pansion coefficient;the hardness of the weld increases and the toughness of the weld decreases which is caused by carburization;during the face bend test,the crack appears at the fusion area of low alloy steel due to decar-burization;flux cored wire welding due to the groove design is not appropriate,easy to cause the slag.The inap-propriate groove design is easy to cause the slag problem when it is welded by FCAW.In this paper,a reasona-ble welding process plan which is designed based on the analysis of weldability of weathering steel 09 CuPCrNi-A and stainless steel 316L,has made the joint qualified.The mechanical properties and microstructure analysis show that the welding process can meet the requirements of products and the welding procedure has been applied to practical production.%异种钢焊接时由于热导率和线膨胀系数不同,焊接时容易产生热裂纹;由于焊缝增碳,使焊缝硬度增加,韧性下降;低合金钢熔合区脱碳,面弯时在低合金钢熔合区产生裂纹;药芯焊丝焊接时如坡口设计不合适,则易导致夹渣。为避免以上异常情况,文中采用FCAW焊接方法,对船用柴油机SCR装置用异种钢(09CuPCrNi-A与316L)进行焊接,设计合理的焊接工艺方案,得到合格焊接接头。通过力学性能和显微组织分析,证明该焊接工艺能够满足产品要求,并在实际生产中得到了应用。

  7. Damage Analyses of Reformer Tubes in SRT-IV-HS Furnace%SRT-IV-HS型裂解炉管损伤分析

    Institute of Scientific and Technical Information of China (English)

    李若平; 方鲁晋

    2001-01-01

    通过现场测试和实验室试验,研究了SRT-IV-HS炉管的损伤失效形式。结果表明:高温渗碳、热冲击开裂和蠕变是造成炉管失效的主要原因。当炉管长期在高温下工作时,介质中的碳会渗入到显微组织中,这不仅使材料脆化,而且使渗碳表面产生残余应力,导致炉管开裂。热冲击是由于炉管在某些部位温度变化大,炉管和结焦物的热膨胀系数不同,而产生较大的温差应力,使炉管产生裂纹。高温蠕变损伤是由于过热引起的,过热使金相组织内部产生蠕变空洞,在热应力下空洞扩展连接而形成蠕变裂纹。根据失效损伤分析,提出了防止炉管损伤并延长其使用寿命的6条措施。%By means of spot inspections and experiments in the laboratory,the damage types of tubes HP40Nb in SRT-IV-HS furnace has been researched. The resul ts show t hat carburizing, hot attack and creep at high temperature are main factors to ma ke the tubes usable. The carbon in the media w ill diffuse in microstructure, which not only embrittles the tubes, but also pro duces the residual stresses on their surface. For these reasons, the tubes crack . Because of large temperature differences in some local tubes and different expa nsion coefficients, large stresses of temperature difference are produced and br ings about cracking in tubes. Creep damage is mainly caused by superheat. Becaus e of superheat, creep cavities are formed inside microstructure, under heat stres s condition, growth and join of cavities induce creep cracking. Acoording to dam age analyses, six kinds of measures are proposed to provent tubes from fai lure and to elongate tube lifetime.

  8. Effect of Diffuser and Volute on Turbocharger Centrifugal Compressor Stability and Performance: Experimental Study Effet du diffuseur et de la volute sur la performance et la stabilité d’un compresseur centrifuge de suralimentation: étude expérimentale

    Directory of Open Access Journals (Sweden)

    Mohtar H.

    2011-11-01

    Full Text Available Engine downsizing is potentially one of the most effective strategies being explored to improve fuel economy. A main problem of downsizing using a turbocharger is the small range of stable functioning of the turbocharger centrifugal compressor at high boost pressures. Several techniques were studied to increase the compressor operating range without sacrificing the compressor efficiency. This paper presents the effect of delaying diffuser stability on the compressor performance and surge line. Two different techniques were investigated, these are grooved and pinched diffuser. Moreover, the effect on retracting volute tongue on compressor performance is also studied. Pinched diffuser shifted surge line to low flow rates, while dropping pressure through compressor. On the other hand, some interesting results were obtained when using grooved diffuser, these are pressure increase at high flow rates, and choke line shift to high flow rates. While retracting volute tongue was interesting in improving compressor efficiency, and pressure lines at high speed. Le “downsizing” moteur est potentiellement l’une des stratégies les plus efficaces pour baisser la consommation carburant. Un problème majeur du “downsizing” à l’aide d’un turbocompresseur est la petite plage de fonctionnement stable du compresseur centrifuge à haute pression de suralimentation. Plusieurs techniques ont été étudiées pour augmenter la plage de fonctionnement du compresseur, sans sacrifier le rendement du compresseur. Cet article présente l’effet de la stabilisation du diffuseur sur la performance du compresseur et la ligne de pompage. Deux techniques différentes ont été étudiées, les sillons et le pincement diffuseur. De plus, l’effet de la diminution du bec de la volute sur les performances du compresseur a également été étudié. Le pincement du diffuseur a déplacé la ligne de pompage pour de faibles débits. Ce déplacement a été accompagn

  9. Evaluation of Butanol–Gasoline Blends in a Port Fuel-injection, Spark-Ignition Engine Évaluation de mélange butanol-essence dans un moteur à allumage commandé à injection indirecte

    Directory of Open Access Journals (Sweden)

    Dernotte J.

    2009-11-01

    Full Text Available This paper assesses different butanol–gasoline blends used in a port fuel-injection, spark-ignition engine to quantify the influence of butanol addition on the emission of unburned hydrocarbons, carbon monoxide, and nitrogen oxide. Furthermore, in-cylinder pressure was measured to quantify combustion stability and to compare the ignition delay and fully developed turbulent combustion phases as given by 0%–10% and 10%–90% Mass Fraction Burned (MFB. The main findings are: 1 a 40% butanol/60% gasoline blend by volume (B40 minimizes HC emissions; 2 no significant change in NOx emissions were observed, with the exception of the 80% butanol/20% gasoline blend; 3 the addition of butanol improves combustion stability as measured by the COV of IMEP; 4 butanol added to gasoline reduces ignition delay (0%–10% MFB; and 5 the specific fuel consumption of B40 blend is within 10% of that of pure gasoline for stoichiometric mixture. Cet article évalue le potentiel de l’utilisation de différents mélanges butanolessence dans un moteur à allumage commandé à injection indirecte afin de quantifier l’influence de l’ajout de butanol sur les émissions des hydrocarbures imbrûlés (HC, le monoxyde de carbone (CO et les oxydes d’azote (NOx. De plus, l’influence sur la stabilité de combustion, le délai d’inflammation et sur la durée de la phase de combustion turbulente développée y sont également présentés. Les principaux résultats: 1 un mélange de 40% butanol et 60% essence (B40 par volume diminue les émissions de HC; 2 aucun effet significatif sur les émissions de NOx n’a été observé à l’exception du mélange 80% butanol/20% essence; 3 l’ajout de butanol améliore la stabilité de combustion ; 4 l’ajout de butanol réduit le délai d’inflammation, quantifié par la durée pour consommer 10% de masse de gaz frais; et 5 la consommation spécifique de carburant pour un mélange stoechiométrique de B40 est 10% sup

  10. Etude des phenomenes de penetration des especes chimiques dans les revetements cathodiques des cuves d'electrolyse de l'aluminium

    Science.gov (United States)

    Brisson, Pierre-Yves

    Cette these decrit l'etude effectuee sur les phenomenes d'insertion du sodium et de penetration du bain electrolytique dans les revetements cathodiques des cuves d'electrolyse de l'aluminium. L'etude fut effectuee a l'aide d'un montage permettant d'effectuer l'electrolyse en laboratoire. Trois types de revetement cathodiques furent etudies : des blocs semi-graphitique, des blocs graphitiques et des blocs graphitises. L'insertion du sodium dans les trois differents types de blocs fut etudiee a l'aide de la spectrometrie des photoelectrons X (XPS). L'analyse a permis de mettre en evidence deux formes de sodium dans l'anthracite et la phase liante des materiaux semi-graphitiques et graphitiques, indiquant qu'une fraction du sodium se retrouve sous forme adsorbee dans les micropores des materiaux alors que l'autre fraction est inseree dans la structure cristalline du carbone. Dans les phases graphitiques (materiaux graphitises et graphitiques), seuls les micropores sont occupes par le sodium Ce resultat explique la tendance observee selon laquelle l'ajout de graphite dans les blocs permet d'abaisser le gonflement sodique. Les mecanismes de penetration du bain dans le reseau poreux des materiaux furent etudies en microscopie electronique et en diffraction des rayons X sur des echantillons apres differents temps d'electrolyses et en variant l'atmosphere (soit sous argon ou sous azote). Ces analyses ont permis d'identifier le mecanisme conduisant a la mouillabilite du bain sur le carbone en fonction de l'atmosphere entourant l'electrolyse. Ainsi, sous azote, la formation de NaCN dans les pores des materiaux par reactions entre le sodium et l'azote permet une mouillabilite accrue du bain alors qu'en absence d'azote (sous argon), le carbure d'aluminium, formes a la surface des pores, joue un role similaire. Dans ce dernier cas, la penetration du bain est moins rapide etant donnee la necessite de toujours amener des especes contenant de l'aluminium en tete du front de

  11. Control Oriented Model of a Variable Geometry Turbocharger in an Engine with Two EGR Loops Modélisation de compresseur à géométrie variable dédiée au contrôle pour un moteur avec deux boucles EGR

    Directory of Open Access Journals (Sweden)

    Chauvin J.

    2011-09-01

    Full Text Available In order to make modern Diesel engines cleaner and more fuel efficient, their air systems architecture become more and more complex. The control strategies of these systems must take account of the multiple components interactions with minimal calibration effort required. In this context, model based techniques are very attractive. In this paper, we propose a control oriented model of a variable geometry turbocharger in an architecture with two Exhaust Gas Recirculation (EGR loops: High Pressure (HP and Low Pressure (LP. This model is implemented in a basic control strategy and evaluated experimentally during tests with LP or HP EGR. The results show that the choice of EGR circuit has a high influence on the turbocharger actuator position, but that this effect is well taken into account in the proposed model. Afin de rendre les moteurs Diesel modernes plus propres et plus économes en carburant, l’architecture de la boucle d’air est de plus en plus complexe. Les stratégies de contrôle doivent tenir compte des interactions entre les dynamiques et doivent être facilement calibrables. Dans ce contexte, l’utilisation de modèle reposant sur des principes physiques est très adaptée. Dans cet article, nous proposons un modèle d’un turbocompresseur à géométrie variable dans une architecture à deux boucles de recirculation des gaz d’échappement (EGR : haute pression (HP et basse pression (BP. Ce modèle est la composante principale d’une stratégie de contrôle et est évalué expérimentalement lors d’essais avec de l’EGR basse pression et de l’EGR haute pression. Les résultats montrent que le choix du circuit EGR a une grande influence sur la position de l’actionneur turbocompresseur, mais que cet effet est bien pris en compte dans le modèle proposé.

  12. Preparation of K doped Ni/β-Mo2C and its performance for CO hydrogenation%K改性Ni/β-Mo2C催化剂用于CO加氢反应研究

    Institute of Scientific and Technical Information of China (English)

    赵立红; 闫捷; 魏灵朝; 蒋元力; 房克功; 孙予罕

    2015-01-01

    采用溶胶凝胶法及程序升温碳化法制备了K改性的Ni/β-Mo2C催化剂,通过XRD、N2吸附-脱附分析和TEM等手段表征了催化剂的织构特征。考察了K含量对Ni/β-Mo2C催化剂CO加氢合成低碳醇反应性能的影响。实验结果表明:K改性Ni/β-Mo2C具有较高的CO加氢反应活性,产物以C1-4烷烃为主;适量K助剂的引入能大大提高催化剂的比表面积,有利于提高催化剂的合成低碳醇能力;过量K助剂的引入降低了催化剂的比表面积且与Mo形成了惰性的K2MoO4,降低了催化剂的活性。%K doped Ni/β-Mo2C catalysts were prepared by sol-gel method and temperature programmed carburization method, and their structure and morphology were characterized by XRD, BET and TEM. The effect of K amount on the catalytic behavior of the catalysts for hydrogenation of CO to higher alcohols was investigated in a fixed bed reactor. The results showed that the K doped Ni/β-Mo2C catalysts exhibited high activity for CO hydrogenation reaction and C1-4 alkanes were the main products. The addition of an appropriate amount of K could greatly increased the surface area of the Ni/β-Mo2C catalysts and enhanced both activity and selectivity towards C2 + alcohols. However, when an excessive amount of K was added, the surface area of the catalysts decreased and inert K2MoO4 was formed, which resulted in the decrease of the catalytic activity.

  13. Influence of K content on performance of nano-structured K/Fe/β-Mo2C catalysts in CO hydrogenation%K含量对纳米K/Fe/β-Mo2C催化剂CO加氢反应性能的影响

    Institute of Scientific and Technical Information of China (English)

    赵立红; 闫捷; 房克功; 魏灵朝; 蒋元力; 孙予罕

    2014-01-01

    Abastract: A series of nano-sized K/Fe/β-Mo2C catalysts were prepared by a modified sol-gel method followed by a temperature-programmed carburization process under argon flow. The effects of K on the texture properties, structure and catalytic performance of the catalysts were investigated. The results showed that the introduction of K increased β-Mo2C particle size of the catalysts, and the addition of proper content of K could improve the surface area, the CO hydrogenation activity and the selectivity to higher alcohols of the catalysts. However, when excessive K was added, the inert K2MoO4 and/or K2Mo2O7 would be formed on the surface of the catalysts, which resulted in that part of the active species were covered and the catalytic activity and selectivity of higher alcohols were decreased.%以柠檬酸(CA)为络合剂,采用溶胶-凝胶法制备了K/Fe/β-Mo2C催化剂前驱体,将该前驱体在Ar气氛下程序升温碳化制备了纳米尺寸的K/Fe/β-Mo2C催化剂。考察了K含量对K/Fe/β-Mo2C催化剂织构及CO加氢反应性能的影响。结果表明,K助剂的引入促进了催化剂中β-Mo2C晶粒的长大,适量的K提高了催化剂的比表面积,提高了催化剂的活性和低碳醇选择性,但是过量K助剂的引入在催化剂表面形成了惰性的K2MoO4和K2Mo2O7,覆盖了部分活性中心,降低了催化剂的活性和低碳醇选择性。

  14. Deposit formation by 20 % (V/V) FAME fuels in premix burner systems; Ablagerungsbildung durch 20% (V/V) FAME-Brennstoffe in Vormischbrennersystemen

    Energy Technology Data Exchange (ETDEWEB)

    Jaschinski, Christian; Rheinberg, Oliver van [OWI Oel-Waerme-Institut GmbH, Aachen (Germany); RWTH Aachen (Germany). An-Institut

    2012-09-15

    In the domestic heating market the development and use of fuels with an increasing share of biogenic or alternative fuels is propagated. Due to the fact, that modern fuel oil burner feature a complex carburation techniques and combustion, changes on the fuel properties and composition can lead to increased emissions or deposit formation therein. Furthermore, the different fuel properties may result in decreased storage stability, which has to be evaluated before introducing them into the market. The scope of the project was to investigate the performance of low-sulfur domestic heating oil (DHO) with up to 20 % v/v FAME on the storage stability and on the use in oil-fired heating systems. The project was split into two major parts. The first part covered a two-year storage of the fuels including sampling and analysis of the fuels every half year. The analysis was conducted according to DIN 51603-1 for the pure DHO and according to DIN SPEC 51603-6 for the blends. It has been shown, that low sulphur domestic heating oil with up to 20 % (V/V) of FAME after two years of storage fits the parameter of the corresponding standards. Furthermore, a new testing method, called 'DGMK-714' derived from the PetroOxy-test (EN 16091) has been defined. With this method for the determination of oxidation stability the fuels can be characterized being comparable to the standardized testing methods of modified Rancimat or PetroOxy. The higher sample volume of the method allows further analysis of the fuel sample after testing for characterization of the fuels. The second part of the project investigated the deposit formation tendencies of the fuels in an idealized testing apparatus and in three different kinds of oil burners. Using the idealized testing apparatus proved an increased tendency of deposit formation during evaporation for an increasing FAME content. However, this tendency could not be observed in the three commercial oil-fired heating systems. A precise fuel

  15. Nanoporous, Metal Carbide, Surface Diffusion Membranes for High Temperature Hydrogen Separations

    Energy Technology Data Exchange (ETDEWEB)

    Way, J.; Wolden, Colin

    2013-09-30

    Colorado School of Mines (CSM) developed high temperature, hydrogen permeable membranes that contain no platinum group metals with the goal of separating hydrogen from gas mixtures representative of gasification of carbon feedstocks such as coal or biomass in order to meet DOE NETL 2015 hydrogen membrane performance targets. We employed a dual synthesis strategy centered on transition metal carbides. In the first approach, novel, high temperature, surface diffusion membranes based on nanoporous Mo{sub 2}C were fabricated on ceramic supports. These were produced in a two step process that consisted of molybdenum oxide deposition followed by thermal carburization. Our best Mo{sub 2}C surface diffusion membrane achieved a pure hydrogen flux of 367 SCFH/ft{sup 2} at a feed pressure of only 20 psig. The highest H{sub 2}/N{sub 2} selectivity obtained with this approach was 4.9. A transport model using “dusty gas” theory was derived to describe the hydrogen transport in the Mo{sub 2}C coated, surface diffusion membranes. The second class of membranes developed were dense metal foils of BCC metals such as vanadium coated with thin (< 60 nm) Mo{sub 2}C catalyst layers. We have fabricated a Mo{sub 2}C/V composite membrane that in pure gas testing delivered a H{sub 2} flux of 238 SCFH/ft{sup 2} at 600 °C and 100 psig, with no detectable He permeance. This exceeds the 2010 DOE Target flux. This flux is 2.8 times that of pure Pd at the same membrane thickness and test conditions and over 79% of the 2015 flux target. In mixed gas testing we achieved a permeate purity of ≥99.99%, satisfying the permeate purity milestone, but the hydrogen permeance was low, ~0.2 SCFH/ft{sup 2}.psi. However, during testing of a Mo{sub 2}C coated Pd alloy membrane with DOE 1 feed gas mixture a hydrogen permeance of >2 SCFH/ft{sup 2}.psi was obtained which was stable during the entire test, meeting the permeance associated with the 2010 DOE target flux. Lastly, the Mo{sub 2}C/V composite

  16. Certified reference materials and reference methods for nuclear safeguards and security.

    Science.gov (United States)

    Jakopič, R; Sturm, M; Kraiem, M; Richter, S; Aregbe, Y

    2013-11-01

    have therefore reached high level of attention for safeguards authorities. Furthermore, IRMM initiated and coordinated the development of a Modified Total Evaporation (MTE) technique for accurate abundance ratio measurements of the "minor" isotope-amount ratios of uranium and plutonium in nuclear material and, in combination with a multi-dynamic measurement technique and filament carburization, in environmental samples. Currently IRMM is engaged in a study on the development of plutonium reference materials for "age dating", i.e. determination of the time elapsed since the last separation of plutonium from its daughter nuclides. The decay of a radioactive parent isotope and the build-up of a corresponding amount of daughter nuclide serve as chronometer to calculate the age of a nuclear material. There are no such certified reference materials available yet. PMID:23507450

  17. Perspectives d'amélioration du rendement à très faible charge des moteurs d'automobile Prospects for Lmprovinq the Very-Low-Load Efficiency of Automotive Engines

    Directory of Open Access Journals (Sweden)

    Douaud A.

    2006-11-01

    Full Text Available Le mauvais rendement énergétique des véhicules utilisés à très faible charge (circulation urbaine, vitesses limitées provient entre autres des combustions non optimales. Celles-ci sont de plusieurs types : combustion lente et/ou tardive, ratés de propagation. L'acquisition de cycles de pression au moyen du système DIGITAP développé à l'In-titut Français du Pétrole (IFP est décrite et le calcul instantané du travail cycle-à-cycle permet de définir un critère de stabilité de fonctionnement du moteur. L'analyse thermodynamique des cycles montre que la composition du mélange air + carburant + gaz résiduels, trop proche des limites de propagabilité de flamme, est à l'origine des phénomènes observés. Des voies d'action portant sur les gaz résiduels, la turbulence et les paramètres du système d'allumage sont dégagées et permettent des améliorations importantes du rendement. The poor energy efficiency of vehicles used at very low engine load (urban traffic, limited speeds comes from non-optimum combustion, among other causes. Such combustion may be of several types, i. e. slow and/or late combustion, propagation misfiring. The recording of pressure cycles by the DIGITAP system developed at Institut Français du Pétrole (IFP is described, and the instantaneous computing of the cycle-to-cycle work enables a stability criterion for engine operating to be described. The thermodynamic analysis of the cycles shows that the composition of the air + fuel + residuel gas mixture which is too close to flame propagation limits is at the origin of the phenomena observed. Methods of action concerning residual gases, turbulence and the parameters of the ignition system are determined and make for great improvements in efficiency and stability for such types of running.

  18. Deposition technology and properties of diamond-like carbon thin film on tappet%发动机挺柱沉积类金刚石薄膜的工艺及性能

    Institute of Scientific and Technical Information of China (English)

    黄平; 张营营; 张斌; 范梅梅; 李兴杰; 强力

    2013-01-01

    采用磁控溅射法,以Cr、Ti和石墨为靶材,Ar、N2和CH4为溅射气体,在材料为20CrMo的发动机挺柱上利用多层梯度复合技术沉积了低摩擦类金刚石(DLC)薄膜复合层CrTi/CrTiN/CrTiC/DLC.该薄膜复合层的纳米压痕硬度高达13 GPa,结合力为50 N,表面粗糙度为0.398 nm.在SRV-IV微动摩擦磨损试验机上进行耐磨损试验后,DLC复合薄膜挺柱的磨损率为渗碳挺柱的1/6.该研究技术具有自主知识产权,实现了挺柱批量化覆膜加工,并有望在发动机主要摩擦副上推广应用.%A low-friction multilayered diamond-like carbon (DLC) film with gradient structure of CrTi/CrTiN/CrTiC/DLC was deposited on tappet made of 20CrMo by magnetron sputtering of Cr,Ti,and graphite targets in Ar/N2/CH4 atmosphere.The composite thin film features hardness up to 13 GPa,bonding strength 50 N,and surface roughness 0.398 nm.The wear rate of the sputtered tappet is 1/6 of that of a carburized one after testing by SRV-IV fretting tribometer.The bulk thin film processing of tappets by using the technology with independent intellectual property rights has been realized,showing a promising use in manufacturing main friction couples of engines.

  19. Mo-Based Zeolite Catalysts and Oxygen-Free Methane Aromatization%Mo基分子筛催化剂及甲烷无氧芳构化

    Institute of Scientific and Technical Information of China (English)

    胥月兵; 陆江银; 王吉德; 张战国

    2011-01-01

    Among the investigated catalysts, the Mo-based zeolite catalysts showed the highest catalytic activity. These catalysts were systematically discussed on MoOx structure and its location in zeolite, the active Mo species and its carburization in the induction period. The issues on intermediates, the bi-functional reaction mechanism and catalyst deactivation with coke were also discussed. The effect of preparation method, calcination temperature and time, Mo loading, ratio of SiO2 to Al2O3 and the catalyst pretreatment in reaction on the catalytic performance of Mo-based catalyst were demonstrated. Then the ways to improve the catalyst activity and reaction stability were comprehensively introduced, pointing out that the catalyst was always deactivated due to coke and needed regeneration. At last according to our research results the discussion and analysis in the view of engineering technology for methane dehydroaromatization were given, and some problems needed to be solved were put forward.%本文综述了甲烷无氧芳构化反应及Mo基分子筛催化剂的研究进展.在众多的催化剂中以Mo基分子筛催化性能最佳.概括了催化剂中关于MoOz前躯体结构和其在分子筛中落位,Mo2C物种和诱导期等;讨论了反应中涉及的中间产物、双功能机理以及催化剂失活等问题;归纳了催化剂制备过程中制备方法、焙烧温度与时间、Mo载量和分子筛硅铝比以及催化剂预处理对反应活性的影响;综述了提高催化剂催化性能和反应性能的各种方法,并对其分析,同时介绍了两种催化剂再生方法.最后,依据本实验室研究进展,对甲烷芳构化从工艺角度进行一些可行性讨论,并提出相关问题和展望.

  20. Soudage par explosion thermique sous charge de cermets poreux à base de TiC-Ni sur substrat en acier-comportement tribologique Welding of porous TiC–Ni based cermets on substrate steel by thermal explosion under load-tribological behaviour

    Directory of Open Access Journals (Sweden)

    Lemboub Samia

    2013-11-01

    Full Text Available Dans ce travail, nous nous intéressons à l'élaboration de cermets à base de TiC-Ni par dispersion de particules de carbures, oxydes ou borures dans une matrice de nickel, grâce à la technique de l'explosion thermique sous une charge de 20 MPa. La combustion de mélanges actifs (Ti-C-Ni-An où An = Al2O3, MgO, SiC, TiB2, WC, basée sur la réaction de synthèse de TiC (ΔHf298K = −184 kJ/mole, génère des cermets complexes. Un court maintien sous charge du cermet à 1373 K, après l'explosion thermique, permet son soudage sur un substrat en acier XC55. Les cermets obtenus dans ces conditions demeurent poreux et conservent une porosité de l'ordre de 25–35 %. La densité relative du cermet, sa dureté et son comportement tribologique, dépendront de la nature de l'addition dans les mélanges de départ. Porous TiC-Ni based cermets were obtained by dispersion of carbides, oxides or borides particles in a nickel matrix thanks to the thermal explosion technique realized under a load of 20 MPa. The combustion of active mixtures (Ti-C-Ni-An where An = Al2O3, MgO, SiC, TiB2 or WC based on the titanium carbide reaction synthesis (ΔHf = −184 kJ/mol, generates porous complex cermets. After the thermal explosion, a short maintenance under load at 1373 K of the combustion product, allows at the same time the cermets welding on a carbon steel substrate. The obtained cermets under these conditions preserve a porosity of about 25–35%. The relative density, hardness and tribological behaviour of the complex cermets depend on the additions nature (An in the starting mixtures.