WorldWideScience

Sample records for carburization

  1. 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

  2. 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

  3. Internal strain measurement of carburized gear by neutron diffraction

    International Nuclear Information System (INIS)

    Internal strain and stress distributions of carburized transmission gear was non destructively measured by neutron diffraction in order to understand deformation behavior after carburizing. The material used in this study was chromium-molybdenum steel, SCM 420 H. The carburized case depth was determined by microscope and measuring hardness distribution. The diffractions from Fe-110 and 211 planes were used, and internal strain was obtained from the lattice spacing change. Reference coupon specimens were cut from the same carburized gear, and then lattice spacing was measured as stress-free one. As the results, the carburized case depths of shift fork groove and dog clutches were relatively deeper than that of gear wheel. From measured axial, radial and hoop residual strains near the internal spline, large tensile residual strain parallel to the axial direction was generated in the shift fork groove. Furthermore, tensile residual strains parallel to the axial and hoop directions were also generated in the gear wheel. Residual strains of carburized gear were found to be not uniform, and be balanced by local deformation through the whole gear including the shift fork groove and dog clutches. (author)

  4. Electrochemical corrosion behavior of the carburized porous TiAl alloy

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-15

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

  5. 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.

  6. 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)

  7. The Corrosion Behavior of Carburized Aluminum Using DC Plasma

    Directory of Open Access Journals (Sweden)

    Somayeh Pirizadhejrandoost

    2012-01-01

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

  8. 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

  9. 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.

  10. 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.

  11. Contribution to the study of gaseous Carburization of Uranium

    International Nuclear Information System (INIS)

    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

  12. 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

  13. 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.

  14. 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...

  15. Zircon Carburation Studies as Intermediate Stage in the Zirconium Fabrication

    International Nuclear Information System (INIS)

    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

  16. 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.

  17. Advances and directions of ion nitriding/carburizing

    Science.gov (United States)

    Spalvins, Talivaldis

    1989-01-01

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

  18. 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

  19. Low Temperature Surface Carburization of Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-12-07

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

  20. 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.

  1. 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.

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

    Directory of Open Access Journals (Sweden)

    Osman ASİ

    2001-02-01

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

  3. 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.……

  4. 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°.

  5. Gas carburization of Inconel 617. Advanced Gas Cooled Reactor Materials Program

    International Nuclear Information System (INIS)

    This report describes the progress in the Advanced Gas Cooled Reactor Materials Program on efforts to produce uniformly carburized specimens of Inconel 617 with different carbon levels. This material will be used to determine the effect of carbon content on the mechanical properties and physical properties important for design and use of components in the primary circuit of an advanced HTGR system. The results of gas carburization and high temperature homogenization heat treatments are discussed. Also described are electron microprobe analysis methods for measuring the carbon gradients in the carburized and homogenized material. Recommendations are given for additional work needed to increase the homogeneity of carburized material and for producing material with uniform carbon concentration. Recommendations for improving the accuracy of the EPMA carbon gradient analyses also are included

  6. 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

  7. Growth Simulation of Spheroidized Carbide in the Carbide-Dispersed Carburizing Process

    Science.gov (United States)

    Tanaka, Kouji; Ikehata, Hideaki; Nakanishi, Koukichi; Nishikawa, Tomoaki

    2008-06-01

    A simulation method that combines one-dimensional (1-D) diffusion models has been proposed for predicting the behaviors of carbide particles dispersed in the carburizing layer of high-carbon chromium steels. The first simulation was set for the heating stage prior to carburizing, using a microscopic model of a spherical carbide and surrounding austenite matrix. This revealed the undissolved status of the carbide even at carburizing temperatures, which was stored as the starting condition of the second simulation. Separately, in a planar model, the macroscopic carbon diffusion during the isothermal carburizing stage was calculated, and time functions of carbon activity were evaluated at the depth of interest. The change in activities was assumed to represent the boundary conditions of the local carbide/austenite region, and thus input to the restored spherical model to do the second simulation of carburizing stage. The simulation method linking these double-scale diffusion calculations has first been implemented using the DICTRA package, and applied to the carbide in multicomponent model steels. The carbide radius as well as volume fraction were successfully predicted for all stages in the carbide-dispersed carburizing (CDC) process. However, minor corrections were necessary because of the decrease in the number density of carbide particles and the discontinuity in carbon activity caused by the use of two different models.

  8. 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)

  9. 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.

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

    Science.gov (United States)

    Kramer, Patrick C.

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

  11. Internal residual strain mapping in carburized chrome molybdenum steel after quenching by neutron strain scanning

    International Nuclear Information System (INIS)

    A hollow circular cylinder specimen with an annular U-notch of chrome molybdenum steel with 0.20 mass% C (SCM420) was carburized in carrier gas and quenched in oil bath. In order to determine the case depth, the specimen was cut off and carbon content and Vickers hardness gradients were measured experimentally near the carburized surface. The residual strain mapping in the interior of carburized cylinder was conducted nondestructively by neutron strain scanning. In this study, the neutron diffraction from Fe-211 plane was used for strain scanning. The neutron wavelength was tuned to 0.1654nm so that diffraction angle became about 90deg. Radial, hoop and axial residual strains were measured by scanning diffracting volume along the axial direction of cylinder specimen. Each residual strain was calculated from lattice spacing change. Unstressed lattice spacing was determined experimentally using reference coupon specimens that were cut from the interior of same carburized cylinder. As a result, the diffraction peak width at half height, FWHM, near the carburized surface was about 3.7 times wider than that of coupon specimens. On the other hand, the most peak widths in the interior equaled to that of coupon specimens. Peak width broadened slightly as the diffracting volume approached the carburized case layer. From the center to the quarter of cylinder specimen, the hoop and axial strains were tensile, and the radial one was compressive in the interior. From the quarter to the edge of the cylinder specimen, the hoop tensile strain increased, radial and axial strains changed to tensile and compressive, respectively. Therefore, the interior of the cylinder specimen was found to be deformed elastically to balance the existence of compressive residual stresses in the carburized case layer. (author)

  12. 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.

  13. 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.)

  14. 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)

  15. 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.

  16. Lattice plane spacing change in hardened layer of chrome molybdenum steel after carburizing and quenching

    International Nuclear Information System (INIS)

    Block specimens of chrome molybdenum steel with 0.20 mass% C, SCM420, were carburized in carrier gas and quenched in oil bath. The hardness and carbon content gradients in the hardened layer were measured experimentally. The carburized surface of one block specimen was gradually removed by electrolytic polishing. Ten thin plates were cut from the total case depth of the other block specimen. An experimental method to determine the stress-free lattice plane spacing of the hardened layer was examined using x-ray and neutron radiations. As a result, the stress-free lattice plane spacing change in the hardened layer could be determined successfully by measuring neutron diffraction peaks from Fe-211 of the thin plates during rotating ±90deg around the specimen axis. Using x-ray, the stress-free lattice plane spacing at the carburized surface could be also determined by measuring the 2θ-sin2ψ diagrams of either removed surface of block specimen or thin plate. However, under the carburized surface, the Kα2 diffraction from the heat-treated eutectoid phase was superimposed on x-ray diffraction peak because the subsurface microstructure was composed of martensitic and heat-treated eutectoid phases. The stress-free lattice plane spacing under the carburized surface could not be determined using x-ray. Furthermore, the stress-free lattice plane spacing of Fe-211 was found to decrease with increasing the distance from the carburized surface and be expressed by the cubic function of the carbon content in the hardened layer. (author)

  17. Influence of carbon content on properties of carburized steel using different quenchants

    International Nuclear Information System (INIS)

    The problem of creating on of case and core structure and properties of carburized and hardened elements is still present. The analysis of literature showed that using the polymer quenching media to hardened carburized parts with structure martensite-retained austenite, as carbides-martensite - retained austenite is still not known very well. Using as a quenching medium of hardened, water polymer solution let through changing the capacity polymer in solution, circulation and temperature cooling media by watering changes its cooling abilities and let the uniformity of the quenching process. The quenching of elements in water let very often to distortion of brakes of the hardened elements after the carburized and quenching in the oil cannot give these elements the right core structure. In the present work the structure and choice of properties of hardened carburized layers were introduced for chromium and chromium-manganese steel after gas carburizing process (850oC/1-10 h) and direct hardening (center cooling: water polymer solution-polyglycol oxyalkylen) and tempering. The results of investigations permitted of affirm that layer with structure martensite - retained austenite and carbides - martensite - retained austenite produced in process of hardening with polymer solution applying as quenchant give profitable hardness of the element and impact strength of the element with the right layer thickness, the right hardness and microhardness as well as changes in microhardness on section in comparison to layers produced during cooling in water or oil. The results of the mechanical properties of hardened carburized layers created on the chromium-manganese and chromium steels do not show significant differences. (author)

  18. 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)

  19. Effect of pre-oxidization on the cyclic coking and carburizing resistance of HP40 alloy: With and without yttrium modification

    International Nuclear Information System (INIS)

    Highlights: •The integrity oxide layer retards the coking and carburizing process. •The oxide scale changed the carbon deposited mechanism. •Lower coking speed induces lower thermal stress during cyclic carburizing. •Higher pre-oxidation temperature deteriorates the carburizing resistance. •Yttrium addition can sustain the oxide scale integrity during the carburizing. -- Abstract: The pre-oxidation results demonstrate that rare earth elements play an important role on the scale adherence of alloy after the oxidation at elevated temperature. The better scale adherence of the yttrium modified alloy permits a superior cyclic coking and carburizing resistance. This is because the integrity chromia layer, which prevents fast ion diffusion, can retard the outer catalytic coking and the inner carburizing of pre-oxidized alloy. As for the alloy under the cast condition, severe coking and carburization has been detected, which was also observed on the pre-oxidized samples where the scale suffered from severe spalling

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

    International Nuclear Information System (INIS)

    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 M23C6 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.

  1. 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.

  2. 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.

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

    International Nuclear Information System (INIS)

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

  4. Effect of surface layer depth on fatigue life of carburized steel and analysis of fracture proces

    Czech Academy of Sciences Publication Activity Database

    Major, Štěpán; Jakl, L.

    Kazan: Foliant Kazan, 2012 - (Shlyannikov, V.; Goldstein, R.; Makhutov, N.), s. 224-231 ISBN 978-5-905576-18-8. [European conference on fracture /19./. Kazan (RU), 26.08.2012-31.08.2012] Institutional support: RVO:68378297 Keywords : carburization * fatigue life * surface layer Subject RIV: JL - Materials Fatigue, Friction Mechanics

  5. Fatigue life of carburized steel specimens under push-pull loading

    Czech Academy of Sciences Publication Activity Database

    Major, Štěpán; Hubálovský, Š.; Šedivý, J.; Bryscejn, Jan

    2014-01-01

    Roč. 1, č. 1 (2014), s. 99-104. ISSN 2313-0555 Institutional support: RVO:68378297 Keywords : carburizing * fatigue life * sub-surface crack * highstrength steel * push-pull loading Subject RIV: JM - Building Engineering http://www. naun .org/cms.action?id=7631

  6. Nanostructural Evolution of Hard Turning Layers in Carburized Steel

    Science.gov (United States)

    Bedekar, Vikram

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

  7. 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.

  8. 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...

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

    OpenAIRE

    Claudio José Leitão; Paulo Roberto Mei; Rodolfo Libard

    2012-01-01

    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 thermoch...

  10. 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

  11. Laboratory Carburization of Direct-Reduced Iron in CH4-H2-N2 Gas Mixtures, and Comparison with Industrial Samples

    Science.gov (United States)

    He, Yining; Pistorius, P. Chris

    2016-06-01

    Iron ore pellets, reduced with hydrogen, were isothermally carburized in CH4-H2-N2 at 823 K, 923 K, and 1023 K (550 °C, 650 °C, and 750 °C). Temperature strongly affected the total carbon concentration after carburization; significant unbound carbon deposited at the highest temperature. For the range of sizes tested (10 to 12 mm), pellet size did not affect carburization. The variability between pellets was much smaller than for industrial pellets; inhomogeneous gas distribution likely affects carburization under large-scale industrial conditions.

  12. 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.

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

    Science.gov (United States)

    Wu, Wangping; Jiang, Jinjin; Chen, Zhaofeng

    2016-06-01

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

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

    OpenAIRE

    Masafumi Matsushita

    2011-01-01

    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...

  15. Effect of carburizing on fatigue life of highstrength steel specimen under push-pull loading

    Czech Academy of Sciences Publication Activity Database

    Major, Štěpán; Jakl, V.; Hubálovský, Š.

    Santorini : WSEAS Press, 2014 - (Pshikhopov, V.; Foti, D.), s. 143-146 ISBN 978-1-61804-241-5. [International conference on materials: MATERIALS 2014. Santorini (GR), 17.07. 2014-21.07.2014] Institutional support: RVO:68378297 Keywords : carburizing * fatigue life * sub-surface crack * highstrength steel * push-pull * bending-torsion Subject RIV: JM - Building Engineering http://www.europment.org/library/2014/santorini/bypaper/MECHANICS/MECHANICS-00.pdf

  16. 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.

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

    OpenAIRE

    Verônica Mara Cortez Alves de Oliveira; Mariane Capellari Leite da Silva; Cátia Gisele Pinto; Paulo Atsushi Suzuki; João Paulo Barros Machado; Vanessa Motta Chad; Miguel Justino Ribeiro Barboza

    2015-01-01

    The aim of this study was to investigate the short-time creep behavior of Ti-6Al-4V by plasma carburizing, which was performed at 725 °C for 6 h in a 50% Ar – 45% H2 – 5% CH4 gas mixture. Nano and microhardness testing, optical microscopy, TEM, X-ray diffraction and optical profilometry were used to characterize the samples. Furthermore, short-term creep tests were performed under a constant tensile load in air at 600 °C using a dead-weight-creep-rupture machine. The carburizing treatment res...

  18. 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.

  19. 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.

  20. 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

  1. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1966-07-01

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

  3. Pengaruh Carburizing Dan Nitriding Terhadap Sifat Mekanis Pada Baja Bohler K460, Bohler K110 Knl Extra, Bohler Vcn 150 Dan Hss Untuk Bahan Mata Pisau Pemanen Sawit

    OpenAIRE

    Sahir, Bani

    2014-01-01

    The problem in this research is to carburizing and nitriding using Bohler steel K-460, 150 VCN Bohler steel, steel Bohler K110 KNL EXTRA, and HSS steel, and to analyze the extent to which effect carburizing and nitriding for hardness values, chemical elements and microstructure of materials. The purpose of this research is Seeing whether steel Bohler K460, Bohler steel VCN 150, Bohler steel K110 KNL EXTRA and HSS steel, which has been processed by carburizing and nitriding possess better mech...

  4. Les nouveaux carburants pour l'automobile. Carburants oxygénés : emploi et émissions New Automotive Fuels. Oxygenated Fuels: Their Use and Emissions

    Directory of Open Access Journals (Sweden)

    Guibet J. C.

    2006-11-01

    Full Text Available A la lumière de résultats nouveaux obtenus à l'IFP et de publications récentes sur le sujet, on étudie les principales répercussions de l'emploi de carburants oxygénés sur les émissions de polluants à l'échapement et sur les risques possibles associés à la manipulation des produits. Les polluants examinés sont les alkyles de plomb, l'oxyde de carbone, les oxydes d'azote, les produits imbrûlés, les aldéhydes et les hydrocarbures aromatiques polynucléaires. Les émissions de fumées et de particules solides par les moteurs diesel font aussi l'objet de quelques commentaires. On aborde également les problèmes de pertes par évaporation et on fournit quelques informations sur la toxicité des alcools et des aldéhydes. L'étude fait apparaître un besoin réel de nouvelles recherches dans le domaine, mais elle indique déjà que l'emploi de produits organiques oxygénés comme carburants ne devrait pas changer l'ordre de grandeur des niveaux de polluants. In the light of new results from IFP and recent publications on the subject, this article examines the main repercussions of the use of oxygenated fuelss on pollutant exhauts emissions and on possible risks associated with the handling of products. The pollutants examined are lead alkyls, carbon monoxide, nitrogen oxides, unburned products, aldehydes and polynuclear aromatic hydrocarbons. Emissions of smoke and solid particles by diesel engines are also the subject of various comments. Likewise, the article takes up the problem of losses by evaporation, and some information is provided on the toxicity of alcohols and aldehydes. This study reveals the real need for further research in the field, but it already shows that the use of oxygenated organic products as fuels should not bring about much change in the order of magnitude of pollutant levels.

  5. 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

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

    International Nuclear Information System (INIS)

    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 m2/h, the quenching rate 12.6 m2/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

  7. 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.

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

    Directory of Open Access Journals (Sweden)

    Wencel, Z.

    2007-01-01

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

  9. 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...

  10. 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.)

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Evaluation of carburization and decarburization behavior of Fe-9Cr-Mo ferritic steels in sodium environment

    International Nuclear Information System (INIS)

    Carburization and decarburization behavior in sodium have been examined for Fe-9Cr-Mo ferritic steels exposure to flowing sodium with containing 0.0049, 0.016 and 0.16 wppm carbon at temperature between 723 and 873 K. The Fe-9Cr-Mo ferritic steels were more resistant to carbon transfer than 2 1/4Cr-1Mo steel. The carbon transfer and its gradient in Fe-9Cr-Mo ferritic steels was closely related with carbon concentration in sodium, and carburization and decarburization behavior depended on the sodium conditions. In the case of the application of Mod. 9Cr-1Mo steel to heat transfer tubes of steam generator of LMFBR, carburization behavior was observed on the conditions that sodium inlet temperature was 778K and carbon concentration in sodium was 0.01∼0.10 wppm. The mean carbon contents of heat transfer tubes after the operation of the steam generator for 200,000 h were estimated to be about 0.103∼0.148 wt% comparing with initial carbon contents of 0.10 wt%. Consequently it is expected that high-temperature strength of Mod. 9Cr-1Mo steel would retain sufficient strength and ductility for such operating conditions. (author)

  16. The Effects of CO2 Pressure on Corrosion and Carburization Behaviors of Chromia-forming Austenitic Alloys

    International Nuclear Information System (INIS)

    By applying S-CO2 cycle to SFR, the inherent safety could be improved by alleviating the concern of explosive reaction between high temperature steam and liquid sodium as well as increased thermal efficiency at 500-550 .deg. C compared to helium Brayton cycle. Meanwhile, from the material point of view, a compatibility such as corrosion and carburization of candidate materials in S-CO2 environment should be evaluated to assure the long-term integrity of IHX. It has been previously reported that Ni-base alloys and high-Cr Fe-base austenitic alloys showed a good corrosion resistance by the formation of thin chromia layer while carburization behaviors of those materials were not properly investigated. Corrosion and carburization behaviors of three chromia-forming austenitic alloys (Ni-base alloys and Alloy 800HT) were evaluated in S-CO2 (200 bar) and CO2 (1 bar) environment at 550.650 .deg. C for 1000 h. For all test materials, a good corrosion resistance was exhibited by the formation of thin chromia (Cr2O3) with small amount of minor oxides such as Mn1.5Cr1.5O4, Al2O3, and TiO2

  17. 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.

  18. Modeling of distortions after carburization and quenching processes of large gears

    International Nuclear Information System (INIS)

    A new finite element model is developed to predict the deformations, stresses, phase compositions and carbon concentration gradients that arise as a consequence of the physical processes involved in a carburization and quenching process of a large steel gear. Firstly, the diffusion of carbon at elevated temperatures in the austenitic range is studied in a diffusion model. Secondly, the calculated carbon concentration distribution is used as an input for a model that couples the thermal, metallographic and mechanical effects during the quenching process and calculates the evolution of the temperature, phase composition and deformation history at any point in the gear. Two effects typical for oil quenching of large gears are incorporated in the model. The first is the influence of the gear's own weight while hanging on chains before, during and after entering the quench bath. The second is the three-dimensional effect that it takes time between the moment the gear enters the oil quenching bath and the moment when the gear is fully immersed. The non-uniform temperature distribution over the gear's axis causes a non-homogeneous plastic deformation. A diffusion-thermo-metallo-mechanical model that takes these effects into account is compared with a model that does not. The results show that these effects should be incorporated. (paper)

  19. 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.

  20. Application of carbon supported NiMo carburized catalyst to fuel cell anode electrocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Izhar, S.; Otsuka, S.; Nagai, M. [Tokyo Univ. of Agriculture and Technology, Tokyo (Japan). Graduate School of Bio-applications and Systems Engineering

    2008-01-15

    The fabrication of polymer electrolyte fuel cells using platinum (Pt) base catalysts is a challenge due to the high cost of Pt and the potential for carbon monoxide poisoning. Transition metal carbides are highly regarded as a material substitute because of their high conductivity, high activity in hydrogenolysis reactions and high resistance to poisoning of the catalyst. A study was conducted in which nickel (Ni) molybdenum (Mo)/Ketjen carbon (KC) carbides were prepared with various Ni compositions and carburization temperatures. XRD, temperature programmed reduction and the cyclic voltammetric method were used to evaluate these catalysts through comparative evaluations with a Pt/C catalyst. The Ni-Mo/KC catalysts were evaluated for their electrocatalytic activity using a H{sub 2}O{sub 2} single stack cell and a 3-electrode cell in order to identify the active species. Cyclic voltammetry measurements indicated that the Ni-Mo/KC carbide catalysts have a high activity towards the anodic electrooxidation of hydrogen. The activity was attributed to the amorphous Ni-Mo carbide measured by XRD and temperature programmed reduction techniques. It was concluded that bimetallic carbides can reduce the manufacturing cost of fuel cells and are therefore a suitable material for Pt/C catalysts. 17 refs., 3 tabs., 7 figs.

  1. Application of carbon supported base metal carburized catalyst to fuel cell electrocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Izhar, S.; Otsuka, S.; Nagai, M. [Tokyo Univ. of Agriculture and Technology, Tokyo (Japan). Graduate School of Bio-applications and Systems Engineering

    2006-07-01

    Due to the high cost and potential for carbon monoxide poisoning, polymer electrolyte fuel cells using platinum (Pt) base catalysts pose serious problems. Transition metal carbides are highly regarded because of their high conductivity, high activity in hydrogenolysis reactions and high resistance to poisoning of the catalyst. A study was conducted in which nickel (Ni) molybdenum (Mo)/Ketjen carbon (KC) carbides were prepared with various Ni compositions and carburization temperatures. XRD, TPR and the cyclic voltammetric method were used to evaluate these catalysts through comparative evaluations with a Pt/C catalyst. These Ni-Mo/KC catalysts were evaluated for their electrocatalytic activity using a H{sub 2}O{sub 2} single stack cell and a 3-electrode cell in order to identify the active species. It was found that Ni{sub 0.5}Mo{sub 0.5} carbided at 873 K achieved the current density of 17 per cent of the Pt/C catalyst. Cyclic voltammetry measurements indicated that the Ni-Mo/KC carbide catalysts have a high activity towards the anodic electrooxidation of hydrogen. The activity is due to the amorphous Ni-Mo carbide measured by XRD and TPR. It was concluded that bimetallic carbides can reduce the manufacturing cost of fuel cells and are therefore a suitable material for Pt/C catalysts.

  2. 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.

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

    International Nuclear Information System (INIS)

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

  4. A Preliminary Model for the Carburization of Stainless Steel at High Temperatures in Sodium Containing Carbon at Unit Activity

    International Nuclear Information System (INIS)

    The problem of mass transport of carbon due to carbon activity gradients in sodium systems where part of the circuit is constructed in stainless steel and part in ferritic steel is one of practical importance. The use of low-alloy steels in the evaporator section of secondary circuits is attractive from the cost point of view, and should give freedom from worry on stress corrosion phenomena on the water side. Loss of carbon from an unstabilized low -alloy steel would, however, modify its mechanical properties, and lead to carburization of high-temperature austenitic components of the circuit, again with possibly adverse effects on mechanical properties. No satisfactory model of the kinetics of carburization of stainless steel exists, and this paper is a preliminary attempt to provide one. It is assumed that at the surface of the specimen exposed to sodium the equilibrium level of carbon will be set by the carbon activity of the external medium, and that there will be a carbon activity gradient extending inwards to the as yet unaffected matrix, with the growth of the thickness of the carburizing zone being controlled by the diffusion of carbon down the activity gradient. Within this zone, chromium-rich carbide will tend to precipitate to bring the local level of dissolved chromium into equilibrium with the local carbon activity, as required by the composition of the carbide, and the law of mass action. A simple diffusion model is set up on this basis and, with the aid of experimental data on carbon pick-up, values for the diffusion coefficient of carbon are calculated which are in reasonable agreement with extrapolated values for carbon diffusion in chromium-free austenite. Earlier models have tacitly assumed homogeneous carbon diffusion through the affected layer and this is believed to be incorrect for reasons that are stated. (author)

  5. 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.)

  6. Carburants de substitution : orientations et recherches françaises Synthetic Fuels: French Orientation and Research

    Directory of Open Access Journals (Sweden)

    Guibet J. C.

    2006-11-01

    Full Text Available Le programme d'études et de recherches entrepris en France, depuis 1981, dans le domaine des carburants de substitution, porte à la fois sur l'examen des techniques d'obtention et sur les modalités d'utilisation de ces produits. Les travaux concernent essentiellement le méthanol, le système acétono-butylique et, pour les moteurs Diesel, les dérivés d'huiles végétales. On prévoit, dans une première phase, l'incorporation de faibles proportions - moins de 10 % - de produits organiques oxygénés dans le supercarburant sans modifier les spécifications du produit ni les conditions de réglage des véhicules. D'autres études sont effectuées sur des mélanges à teneur moyenne ou élevée en méthanol (30, 50 ou 90 % afin d'examiner les meilleures voies possibles pour une substitution plus importante. The research undertaken in France since 1981 in the field of alternative fuels includes both the ways of producing and the ways of using such products. These research projects mainly concern methanol, butanol-acetone system and, for diesel engines, vegetable-oil derivatives. In the first phase, plans are being made to incorporate small proportions (less then 10% of oxygenated organic products in premium gasoline without modifying either the specifications of the product or vehicle tuning conditions. Other research is being done on mixtures with a moderate or high methanol content (30, 50 or 90% so as to examine the best possible methods for substituting larger amounts.

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

    Science.gov (United States)

    Pang, Zirui; Yu, Shenjun; Xu, Jinwu

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

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

    Directory of Open Access Journals (Sweden)

    Verônica Mara Cortez Alves de Oliveira

    2015-10-01

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

  9. 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...

  10. “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

  11. 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.

  12. 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.

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

    Science.gov (United States)

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

    2015-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Courty P.

    2006-12-01

    Full Text Available Despite comparative figures for wordwide crude oil and natural gas proven reserves, present time contribution of syngas chemistry to motorfuels remains marginal when the refining industry is faced to main constraints: market demand evolution, stringent specifications and environmental issues. Actually natural gas upgrading via syngas chemistry yields key products (e. g. methanol among which clean motorfuels (ethers, FT products should develop despite the huge investments required, mostly for syngas production. Main challenges and corresponding issues for catalysts and related technologies are identified for Fischer-Tropsch synthesis and motorfuels long-term reformulation. Among other, mastering the chain-growth (FT synthesis improving the FCC products: gasoline, and LCO for Diesel pool. All these issues need significant progresses in catalyst and technology to be solved. Lastly, our economical study, focused on Diesel-fuel production, shows up that clean diesel (from SR-LCO mixtures and FT Diesel reach similar production costs when cheap NG is available. In the future, FT middle distillates should amount to a few percent (5-150 Mt of the 1700-2000 Mt of transport middle distillates expected from oil refining. However they should more and more be a compulsory part of diesel pool if the level of investment for an FT process continues to decrease significantly. Malgré des réserves prouvées en pétrole et en gaz du même ordre de grandeur, la contribution de la chimie du gaz de synthèse à la production de carburants reste marginale, alors que l'industrie du raffinage est confrontée à des contraintes majeures : évolution de la demande, durcissement des spécifications des produits et contraintes environnementales. Cependant, la conversion chimique du gaz, via la chimie du gaz de synthèse, fournit des produits stratégiques (e. g. méthanol parmi lesquels les carburants propres (éthers, produits Fischer-Tropsch devraient se développer, bien

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

    Science.gov (United States)

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

    2014-02-01

    Filament condition during hot-wire chemical vapor deposition conditions of multi-walled carbon nanotubes is a major concern for a stable deposition process. We report on the novel application of electron backscatter diffraction to characterize the carburization of tungsten filaments. During the synthesis, the W-filaments transform to W2C and WC. W-carbide growth followed a parabolic behavior corresponding to the diffusion of C as the rate-determining step. The grain size of W, W2C, and WC increases with longer exposure time and increasing filament temperature. The grain size of the recrystallizing W-core and W2C phase grows from the perimeter inwardly and this phenomenon is enhanced at filament temperatures in excess of 1,400°C. Cracks appear at filament temperatures >1,600°C, accompanied by a reduction in the filament operational lifetime. The increase of the W2C and recrystallized W-core grain size from the perimeter inwardly is ascribed to a thermal gradient within the filament, which in turn influences the hardness measurements and crack formation. PMID:24423105

  16. 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.

  17. 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

  18. 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.)

  19. 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.

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

    International Nuclear Information System (INIS)

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

  1. 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...

  2. Effets d'irradiation et diffusion des produits de fission (césium et iode) dans le carbure de silicium

    OpenAIRE

    Audren, Aurégane

    2007-01-01

    Le carbure de silicium est un matériau envisagé pour le conditionnement du combustible dans les réacteurs de quatrième génération. Ce travail a pour objectif d'étudier la capacité de confinement des produits de fission et l'évolution de la structure de ce matériau sous les effets combinés de la température et du rayonnement. Les implantations d'ions de basse énergie et l'incorporation d'analogues stables de produits de fission (Cs et I) dans des monocristaux de 6H-SiC ont été réalisées sur l'...

  3. Irradiation aux ions des carbures ZrC et TiC. Effets des pertes d'énergie électronique et nucléaire.

    OpenAIRE

    Pellegrino, Stéphanie

    2015-01-01

    Cette étude est orientée sur les céramiques réfractaires des métaux de transition, comme le carbure de titane et de zirconium, envisagées pour leurs caractéristiques de résistance en conditions extrêmes. Ces céramiques seraient soumises à différentes sources d'irradiation (les neutrons, les produits de fission, les désintégrations alpha) dans les futurs réacteurs de génération IV. Les rayonnements rencontrés en réacteur peuvent être simulés par des irradiations externes à l'aide d'accélérateu...

  4. 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.

  5. Evaluation of crack growth behavior and probabilistic S–N characteristics of carburized Cr–Mn–Si steel with multiple failure modes

    International Nuclear Information System (INIS)

    Highlights: • The stepwise S–N characteristics only for interior induced failure was observed. • The interior crack growth behavior with threshold conditions in different stages was clarified. • The distribution characteristics of test data in transition failure region was evaluated. • A model for evaluating the probabilistic S–N curve with multiple failure modes was developed. - Abstract: The unexpected failures of case-hardened steels in long life regime have been a critical issue in modern engineering design. In this study, the failure behavior of a carburized Cr–Mn–Si steel under very high cycle fatigue (VHCF) was investigated, and a model for evaluating the probabilistic S–N curve associated with multiple failure modes was developed. Results show that the carburized Cr–Mn–Si steel exhibits three failure modes including the surface flaw-induced failure, the interior inclusion-induced failure without the fine granular area (FGA) and the interior inclusion-induced failure with the FGA. As the predominant failure mode in the VHCF regime, the interior failure process can be divided into four stages: (i) the small crack growth around the inclusion, (ii) the stable macroscopic crack growth outside the FGA, (iii) the unstable crack growth outside the fish-eye and (iv) the momentary fracture outside the final crack growth zone. The threshold values are successively evaluated to be 2.33 MPa m1/2, 4.13 MPa m1/2, 18.51 MPa m1/2 and 29.26 MPa m1/2. The distribution characteristics of the test data in transition failure region can be well characterized by the mixed two-parameter Weibull distribution function. The developed probabilistic S–N curve model is in good agreement with the test data with multiple failure modes. Although the result is somewhat conservative in the VHCF regime, it is acceptable for safety considerations

  6. 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.)

  7. 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

  8. 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

  9. 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)

  10. 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.

  11. 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.

  12. Propriété des défauts lacunaires dans le carbure de silicium : évolution de leur nature en fonction des conditions d'irradiation et intéraction avec l'hélium

    OpenAIRE

    Linez, Florence

    2012-01-01

    Le carbure de silicium est un des materiaux envisages pour des applications nucleaires tels que les reacteurs a fission de 4eme generation et les reacteurs a fusion. Dans ce cadre, le SiC serait soumis a des conditions extremes de temperatures et d'irradiation ainsi qu'a la presence de gaz issus des produits de fission ou d'activation qui necessitent de comprendre comment les proprietes physiques du SiC pourraient evoluer. Dans le present travail nous nous sommes attaches a etudier les phenom...

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

    International Nuclear Information System (INIS)

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

  14. Étude du carbure de titane nano- et micro-structuré : élaboration et comportement en conditions extrêmes d'irradiation aux ions 40Ar+

    OpenAIRE

    Gherrab, Mehdi,

    2013-01-01

    Ce travail de thèse s'inscrit dans le cadre de l'étude et du développement de matériaux céramiques de type carbure pouvant être utilisés dans l'assemblage combustible des réacteurs nucléaires du futur. Depuis l'accident de Fukushima, ces céramiques réfractaires sont envisagées afin d'améliorer la sûreté dans les centrales à eau pressurisée actuelles. Sous forme de revêtements ou de gaines, ces matériaux pourraient en effet permettre de garantir une meilleure résistance de l'assemblage combust...

  15. 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...

  16. 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...

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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.

  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 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

  6. 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

  7. 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

  8. 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 ...

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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.)

  14. 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)

  15. 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

  16. Doping of silicon carbide by ion implantation; Dopage du carbure de silicium par implantation ionique

    Energy Technology Data Exchange (ETDEWEB)

    Gimbert, J

    1999-03-04

    It appeared that in some fields, as the hostile environments (high temperature or irradiation), the silicon compounds showed limitations resulting from the electrical and mechanical properties. Doping of 4H and 6H silicon carbide by ion implantation is studied from a physicochemical and electrical point of view. It is necessary to obtain n-type and p-type material to realize high power and/or high frequency devices, such as MESFETs and Schottky diodes. First, physical and electrical properties of silicon carbide are presented and the interest of developing a process technology on this material is emphasised. Then, physical characteristics of ion implantation and particularly classical dopant implantation, such as nitrogen, for n-type doping, and aluminium and boron, for p-type doping are described. Results with these dopants are presented and analysed. Optimal conditions are extracted from these experiences so as to obtain a good crystal quality and a surface state allowing device fabrication. Electrical conduction is then described in the 4H and 6H-SiC polytypes. Freezing of free carriers and scattering processes are described. Electrical measurements are carried out using Hall effect on Van der Panw test patterns, and 4 point probe method are used to draw the type of the material, free carrier concentrations, resistivity and mobility of the implanted doped layers. These results are commented and compared to the theoretical analysis. The influence of the technological process on electrical conduction is studied in view of fabricating implanted silicon carbide devices. (author)

  17. Modelingof Acetylene Pyrolysis under Steel Vacuum Carburizing Conditions in a Tubular Flow Reactor

    Directory of Open Access Journals (Sweden)

    Rainer Reimert

    2007-03-01

    Full Text Available In the present work, the pyrolysis of acetylene was studied under steel vacuumcarburizing conditions in a tubular flow reactor. The pyrolysis temperature ranged from650 °C to 1050 °C. The partial pressure of acetylene in the feed mixture was 10 and 20mbar, respectively, while the rest of the mixture consisted of nitrogen. The total pressureof the mixture was 1.6 bar. A kinetic mechanism which consists of seven species andnine reactions has been used in the commercial computational fluid dynamics (CFDsoftware Fluent. The species transport and reaction model of Fluent was used in thesimulations. A comparison of simulated and experimental results is presented in thispaper.

  18. Method of nitriding, carburizing, or oxidizing refractory metal articles using microwaves

    Science.gov (United States)

    Holcombe, Cressie E.; Dykes, Norman L.; Tiegs, Terry N.

    1992-01-01

    A method of nitriding an article of refractory-nitride-forming metal or metalloids. A consolidated metal or metalloid article is placed inside a microwave oven and nitrogen containing gas is introduced into the microwave oven. The metal or metalloid article is heated to a temperature sufficient to react the metal or metalloid with the nitrogen by applying a microwave energy within the microwave oven. The metal or metalloid article is maintained at that temperature for a period of time sufficient to convert the article of metal or metalloid to an article of refractory nitride. in addition, a method of applying a coating, such as a coating of an oxide, a carbide, or a carbo-nitride, to an article of metal or metalloid by microwave heating.

  19. 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...

  20. 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)

  1. An alga oil fuel; Un carburant a base d'huile d'algue

    Energy Technology Data Exchange (ETDEWEB)

    Danielo, O.

    2005-05-15

    Biofuels are nowadays presented as a sustainable energetic alternative. Researches occur now on microscopic algae particularly rich on oil and whose hectare yield is better than those of turnsole or colza. The use at the industrial scale of micro-algae bioreactors, which trap the CO{sub 2} and the NO{sub x}, is in development in the United States. (O.M.)

  2. 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.

  3. 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.)

  4. 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.)

  5. 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)

  6. 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)

  7. 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.)

  8. 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...

  9. Etude thermodynamique et cinétique de la pyrophoricité du carbure d'uranium

    OpenAIRE

    Berthinier, Clément

    2010-01-01

    Les ressources en uranium ne sont pas inépuisables. Si la filière des réacteurs de 3ème génération continue son développement au rythme actuel, en se fiant aux données sur les ressources en uranium identifiées dans monde, ce serait à partir des années 2030-2040 que les ressources commenceraient à manquer. La découverte de nouveaux gisements exploitables d'uranium deviendrait une priorité. Pour répondre au besoin de développement durable, le CEA contribue à la mise au point des réacteurs de 4è...

  10. Low temperature nitriding and carburizing of AISI304 stainless steel by a low pressure plasma arc source

    Energy Technology Data Exchange (ETDEWEB)

    Liang Wang; Xiaolei Xu; Bin Xu; Zhiwei Yu; Zukun Hei [Dalian Maritime Univ. (China). Inst. of Metal and Technology

    2000-09-01

    This paper presents results on the nitriding and carbrizing of AISI 304 stainless steel by a low-pressure plasma arc source at 420 C in Ar-N{sub 2}-H{sub 2} or Ar-H{sub 2}-CH{sub 3}-COCH{sub 3} (acetone) gas mixtures. The working pressure was 0.3-0.4 Pa and the negative voltage applied to the samples was 0.8-1 kV. The phase of nitrided layer formed on the surface was confirmed by X-ray diffraction. The hardness of the samples was measured by using a Vickers microhardness tester with the load of 100 g. X-Ray photoelectron spectroscopy and Auger electron spectroscopy were also carried out to elucidate the chemical states and N concentration of the nitrided layer. The surface properties were investigated by wear and corrosion measurements. (orig.)

  11. 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.)

  12. 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)

  13. Preparation of porous silicon carbide from molecular precursors; Preparation de carbure de silicium poreux a partir de precurseurs moleculaires

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, J

    2008-02-15

    The preparation of Porous Silicon Carbide (SiC) from molecular precursors is described in this work. Firstly, poly-silane and poly-carbo-silane were synthesised from targeted molecular precursors TSCH and TCDSCB. The pyrolysis of these polymers under inert conditions gave the SiC. Secondly, the preparation of functional poly-silane was explored. It was shown that Cp{sub 2}Ti(OPh){sub 2} was a suitable catalyst for the preparation of such functional poly-silane in a one-pot process. Finally, macroporous SiC were prepared from hard templating method by using a commercial silica. (author)

  14. 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)

  15. 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.)

  16. 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...

  17. 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.

  18. 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.

  19. 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.)

  20. 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

  1. 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)

  2. 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.

  3. 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.

  4. 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...

  5. Current status: biomass valorisation and biofuels in Singapore; Etats des lieux: valorisation de la biomasse et agro-carburants a Singapour

    Energy Technology Data Exchange (ETDEWEB)

    Guermont, C.; Barbi, A.P.

    2010-05-15

    After having briefly presented the main types of biofuels (bio-ethanol, bio-diesel) and their first, second and third generation technologies to produce them (from food crops, from non food crops, and from algae), this report presents Singapore public R and D centres working in the field of biofuels development, and their activities. It also presents actors belonging to the private sector, and various realized and announced projects on biofuels

  6. 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…

  7. 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.

  8. 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.)

  9. 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.)

  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. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Accumulation d'acylglycérols par des espèces levuriennes à usage carburant aéronautique : physiologie et performances de procédés

    OpenAIRE

    Cescut, Julien

    2009-01-01

    L’accumulation d’acylglycérols par des espèces levuriennes induite par la limitation de l’élément azote a été caractérisée par l’analyse dynamique et systémique des différents états métaboliques identifiés lors de cultures sous conditions environnementales parfaitement maîtrisées, à hautes densités cellulaires. La mise en place d’un procédé de culture original en mode fed-batch a permis de dégager différents points majeurs : - la limitation en azote déclenche une accumulatio...

  16. 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)

  17. 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)

  18. 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)

  19. 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.)

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

    International Nuclear Information System (INIS)

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

  1. Investigation of the red mud catalytic activity in carbon monoxide reaction decomposition

    OpenAIRE

    Кириченко, Алексей Геннадьевич; Колесник, Дмитрий Николаевич

    2011-01-01

    The process of iron carburization using СО-contaning gas as a catalyst red mud is investigated. Determined the catalytic activity of red mud in the decomposition reaction of CO. The effect of red mud addition to iron ore materials to improve their recoverability and carburization

  2. Preparation and Characterization of Components for Intermediate Temperature Fuel Cells And Electrolyzers

    DEFF Research Database (Denmark)

    Jensen, Annemette Hindhede

    WO3 (WC-mWO3) which had been prepared by use of a mesoporous silica template by carburization with methane at 900°C for 3 hours, a surface area of 6 m2 g −1 was measured. By introducing an extra synthesis step by first converting the WO3 into W2N which was then converted into WC (WC-mW2N) a higher...... surface area of 18 m2 g −1 was measured. The use of methane versus ethane as carburizing agents were investigated, by carburizing commercial WO3 with both agents under the same conditions. From carburization with methane no surface area could be quantified, while the carburization with ethane resulted in...

  3. 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...

  4. Plasma-assisted surface hardening of dual two-phase intermetallic alloy composed of Ni3X type structures

    International Nuclear Information System (INIS)

    A dual two-phase intermetallic alloy composed of Ni3Al (L12) and Ni3V (D022) was plasma-nitrided (PN) or -carburized (PC) in dependence of processing temperature and time. The surface layers of nitrided or carburized alloy were characterized by micro-hardness measurement, scanning electron microscopy, electron probe micro-analysis and X-ray diffraction analysis. The maximum surface hardness of the alloy was obtained by nitriding at around 850 K and by carburizing at 1025 K, and little decreased up to a high temperature with increasing temperature. The XRD analysis revealed that vanadium nitrides (VN) and vanadium carbides (VC) were formed in the surface layer of the nitrided and carburized alloy, respectively; suggesting that the enhanced surface hardness is attributed to the dispersion hardening due to the nitrides and carbides.

  5. 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.

  6. 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.

  7. 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。

  8. Modelling of reactive gas transport

    OpenAIRE

    Sundelöf, Erik

    2003-01-01

    A rather general microscopic model for reactive gastransport in porous media is developed and applied to twodifferent processes in powder metal technology: carburization,and reduction of surface oxides. The carburization model is developed from the kinetic modelproposed by Grabke and applied to a 2-D porous geometryobtained from images. The effect of pore geometry on convectiveand diffusive transport is discussed by model problems andaveraging. The exercise demonstrates the capacity of theFEM...

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

    DEFF Research Database (Denmark)

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

    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...

  10. 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.

  11. 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)

  12. 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.)

  13. 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)

  14. 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.

  15. 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)

  16. 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...

  17. 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.

  18. Report of the results of the fiscal 1997 regional consortium R and D project. Regional consortium energy field / Development of the plasma use surface treatment process by in-situ control (first fiscal year); 1997 nendo chiiki consortium kenkyu kaihatsu jigyo. Chiiki consortium energy bun`ya / in-situ seigyo ni yoru plasma riyo hyohi shori process no kaihatsu (daiichi nendo) seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    The paper described the fiscal 1997 result of the development. To know of in-plasma phenomena such as carburization and nitriding, a basic plasma experimental device was fabricated for quantitative measurement of reaction activity species. For the study of reaction control between plasma and substrate, a rotary analyzer type ellipsometer was fabricated as a method to detect composition and thickness of the deposit on the substrate surface. For He gas cooling after carburization and hardening, basic specifications for He gas refining/circulating system were confirmed. For perfect non-hazardous processing of exhaust gas from plasma carburization furnace, conducted was the thermodynamic computation of the process. Priority in order of the functions to be possessed as specifications for basic design of mini plant is plasma carburization, He gas cooling, and in-situ measurement. To make the most of the plasma use surface treatment as substitutes for expensive alloy elements, sliding parts/die-cast mold raw materials were carburized to measure the hardness. The Cr carbide coating technology by plasma CVD is also under study as an application example except carburization. 47 refs., 59 figs., 31 tabs.

  19. Influence of a simulated HTGR environment on the mechanical properties of a commercial Ni-Cr-Mo-Fe alloy (Hastelloy Alloy X)

    International Nuclear Information System (INIS)

    The influence of a simulated advanced-reactor helium environment, containing 500 μatm H2/50 μatm CH4/50 μatm CO/approx. 1 μatm H2O, on the mechanical properties of two heats of Hastelloy Alloy X is discussed. Simultaneous exposures in air and controlled-impurity helium at temperatures in the range of 6500 to 10000C for times of 3000 h or more were performed. A combination of tensile testing, Charpy V-notch impact toughness testing, and creep testing was used to study the effects of reactor helium/metal interactions on the mechanical behavior of this alloy. Carburization was identified as the primary corrosion phenomenon. Increasing exposure time and temperature were observed to increase the depth of carburization. The increase in carbon concentration in the carburized zone suppressed the additional formation of M6C, which is observed in air-aged specimens, and resulted in the precipitation of M23C6, a chromium-rich carbide variant. The precipitation of M23C6 in the carburized zone occurred primarily along grain and twin boundaries; however, matrix precipitation was also observed, the degree of which depended on exposure temperature. Strength and impact toughness properties were found to be controlled primarily by thermal aging reactions, with only a small effect related to the carburization. Although tensile and creep ductilities were decreased as a result of carburization, substantial ductility remained. Variation was observed between the two heats, the finer-grained heat appearing to be weaker in the high-temperature creep tests and also possibly more susceptible to a loss of creep strength as a result of carburization

  20. 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.

  1. 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.

  2. 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.

  3. 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)

  4. Mechanisms of metal dusting corrosion

    DEFF Research Database (Denmark)

    Hummelshøj, Thomas Strabo

    temperatures at 613K and that the maximal dissolvable carbon content in the f.c.c. lattice is 5.3wt% at 613K. The hardness associated with the dissolved carbon, as measured on the metallographic cross sections, is shown to increase linearly with carbon content. Finally, for a low carburizing temperature it is...... shown that ferrite in heavily deformed stainless steel flakes is transformed to expanded martensite/austenite during low-temperature carburization. Various experimental procedures to experimentally determine the concentration dependent diffusion coefficient of carbon in expanded austenite are evaluated...

  5. Material challenges in ethylene pyrolysis furnace heater service

    Energy Technology Data Exchange (ETDEWEB)

    Ibarra, S.

    1980-02-01

    Operating temperatures of pyrolysis furnaces are sometimes in excess of 2000/sup 0/F (1100/sup 0/C). These temperatures are very detrimental to the life of the typical HK-40 furnace tubes which normally have a three to five year life in the hot section of these furnaces. Short life is attributed to rapid carburization of ID surfaces which subjects tubes to higher than normal stresses and results in creep cracking of furnace tubes. As an aid to understanding the materials problems the ethylene process will be presented, along with data on the carburization of furnace tubes.

  6. 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.

  7. A novel microwave route for the preparation of ZrC-SiC composites

    Science.gov (United States)

    Das, Bharat. P.; Panneerselvam, M.; Rao, K. J.

    2003-06-01

    A novel microwave-assisted carbothermal reduction and carburization route has been used to prepare ZrC-SiC composite powders. Both zircon and mixtures of ZrO 2 and SiO 2 were used as starting materials along with amorphous carbon. Carbothermal reduction and carburization were examined in both argon and nitrogen atmospheres. Reaction kinetics in microwave field was found to exhibit notable differences for the two different starting materials. However, a complete oxide to carbide conversion was achieved in less than 30 min in both cases when argon was used as an ambient gas. The possible structural mechanism involved in the reactions has been discussed.

  8. A novel microwave route for the preparation of ZrC-SiC composites

    International Nuclear Information System (INIS)

    A novel microwave-assisted carbothermal reduction and carburization route has been used to prepare ZrC-SiC composite powders. Both zircon and mixtures of ZrO2 and SiO2 were used as starting materials along with amorphous carbon. Carbothermal reduction and carburization were examined in both argon and nitrogen atmospheres. Reaction kinetics in microwave field was found to exhibit notable differences for the two different starting materials. However, a complete oxide to carbide conversion was achieved in less than 30 min in both cases when argon was used as an ambient gas. The possible structural mechanism involved in the reactions has been discussed

  9. 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.

  10. 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.

  11. 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...

  12. Effects of methane concentration on the controlled-impurity helium corrosion behavior of selected HTGR structural materials

    International Nuclear Information System (INIS)

    The corrosion behavior of candidate structural alloys in a series of three simulated advanced gas-cooled reactor environments at 9000C (16520F), with methane concentration varied, is discussed. The alloys investigated include three wrought alloys, Hastelloy X, Inconel 617, and Incoloy 800H; two cast superalloys, Rene 100 and IN 713; one centrifugally cast alloy, HK 40; and an oxide-dispersion-strengthened alloy, MA 754. Corrosion behavior was found to be strongly dependent upon both the alloy chemistry and the environment. Oxidation, carburization, and/or mixed behavior was observed depending upon the specific conditions. An equilibrium thermodynamics approach has been used to predict alloy behavior and explain observations relevant to the understanding of gas/metal interactions in reactor helium, which inherently contains small amounts of reactive impurity species. Carburization was identified as the primary corrosion phenomenon of concern, and detailed analyses were performed to determine the susceptibility and control of carburization reactions. The presence of alumina scales, containing small amounts of titanium, was found to be particularly effective in inhibiting carburization. Small variations in methane concentration have been shown to have a dramatic effect upon the oxidation potential and subsequent corrosion behavior of the alloy systems

  13. Modelling of composition and stress profiles in low temperature surface engineered stainless steel

    DEFF Research Database (Denmark)

    Jespersen, Freja Nygaard; Hattel, Jesper Henri; Somers, Marcel A. J.

    2015-01-01

    Thermochemical surface engineering by nitriding/carburizing of stainless steel causes a surface zone of expanded austenite, which improves the wear resistance of the stainless steel while preserving the stainless behavior. As a consequence of the thermochemical surface engineering, huge residual ...

  14. 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...

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

    Science.gov (United States)

    Ripley, Edward B.

    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.

  16. 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.

  17. Apparatus for microwave heat treatment of manufactured components

    Science.gov (United States)

    Ripley, Edward B.

    2008-04-15

    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.

  18. 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.

  19. 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.

  20. Survey of post-irradiation examinations made of mixed carbide fuels

    International Nuclear Information System (INIS)

    Post-irradiation examinations on mixed carbide, nitride and carbonitride fuels irradiated in fast flux reactors Rapsodie and DFR were carried out during the seventies and early eighties. In this report, emphasis was put on the fission gas release, cladding carburization and head-end gaseous oxidation process of these fuels, in particular, of mixed carbides. (author). 8 refs, 16 figs, 3 tabs

  1. 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 ?

  2. 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...

  3. 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...

  4. Expanded austenite; crystallography and residual stress

    DEFF Research Database (Denmark)

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

    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. Meningkatkan Efektifitas Karburisasi Padat pada Baja Karbon Rendah dengan Optimasi Ukuran Serbuk Arang Tempurung Kelapa

    Directory of Open Access Journals (Sweden)

    Mujiyono Mujiyono

    2008-01-01

    Full Text Available Pack carburizing is the simplest method of carburizing process that use charcoal powder as carbon element adder. The research target is to increase the effectiveness of charcoal powder as pack carburizing media. Coconut shell charcoal was made into powder then sifted with size of 150, 250, 279, 600, 850 and 2000 m. Specimens were Low Carbon Steel which contain 0,082 % C. The pack carburizing process was conducted for 4 hours at 850 0C. The hardening process was done by reheating at 850 0C with 5 minutes holding time and quenched into water of 28 0C to form Martensite structure that was observed by optic microscope and Micro Vickers Hardness Tester. The conclusion of the research are that 250 until 600 m powder size of coconut shell charcoal can use to pack carburizing media. With 4 hours for pack carburizing process, case depth of carbon diffusion on surface specimen is about 1200 m and surface hardness specimen increase 250% to base material Abstract in Bahasa Indonesia: Karburising padat merupakan metode karburisasi yang paling sederhana, yaitu meng¬gunakan serbuk arang sebagai penambah unsur Karbon. Tujuan penelitian adalah untuk meningkatkan efektivitas hasil proses karburising yang menggunakan serbuk arang tempurung kelapa pada Baja Carbon Rendah. Arang tempurung kelapa dibuat serbuk dan diayak dengan ukuran butir 150, 250, 279, 600, 850 dan 2000 μm. Benda uji yang digunakan adalah baja karbon rendah dengan kandungan 0,082% C. Proses karburising padat dilakukan pada suhu 850 0C selama 4 jam. Proses pengerasan dilakukan dengan memanaskan ulang benda uji pada suhu 850 0C, ditahan 5 menit, kemudian dicelup ke dalam air bersuhu 28 0C. Struktur Martensit yang terbentuk diamati dengan mikroskop dan diuji dengan Micro Vickers Hardness Tester. Dari penelitian ini disimpulkan bahwa serbuk tempurung kelapa dengan ukuran antara 250 hingga 600 µm efektif digunakan untuk proses karburising padat pada Baja Karbón Rendah. Dengan waktu tahan

  6. 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)

  7. 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.

  8. 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

  9. 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

  10. 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...

  11. 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...... austenite and Hägg carbide, Ξ-M5C2. EXAFS showed that the Cr atoms were mainly present in environments similar to the carbides Hägg Ξ-M5C2 and M23C6. The environments of the Fe and Ni atoms were concluded to be largely metallic austenite. Light optical micrograph of stainless steel AISI 316 gas......-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...

  12. 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.)

  13. 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.

  14. 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.

  15. 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

  16. Synthesis and characterization of binder-free Cr3C2 coatings on nickel-based alloys for molten fluoride salt corrosion resistance

    Science.gov (United States)

    Brupbacher, Michael C.; Zhang, Dajie; Buchta, William M.; Graybeal, Mark L.; Rhim, Yo-Rhin; Nagle, Dennis C.; Spicer, James B.

    2015-06-01

    Under various conditions, chromium carbides appear to be relatively stable in the presence of molten fluoride salts and this suggests that their use in corrosion resistant coatings for fluoride salt environments could be beneficial. One method for producing these coatings is the carburization of sprayed Cr coatings using methane-containing gaseous precursors. This process has been investigated for the synthesis of binder-free chromium carbide coatings on nickel-based alloy substrates for molten fluoride salt corrosion resistance. The effects of the carburization process on coating microstructure have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS). Both plasma-sprayed and cold-sprayed Cr coatings have been successfully converted to Cr3C2, with the mechanism of conversion being strongly influenced by the initial porosity in the as-deposited coatings.

  17. 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.

  18. Synthesis and characterization of binder-free Cr3C2 coatings on nickel-based alloys for molten fluoride salt corrosion resistance

    International Nuclear Information System (INIS)

    Under various conditions, chromium carbides appear to be relatively stable in the presence of molten fluoride salts and this suggests that their use in corrosion resistant coatings for fluoride salt environments could be beneficial. One method for producing these coatings is the carburization of sprayed Cr coatings using methane-containing gaseous precursors. This process has been investigated for the synthesis of binder-free chromium carbide coatings on nickel-based alloy substrates for molten fluoride salt corrosion resistance. The effects of the carburization process on coating microstructure have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS). Both plasma-sprayed and cold-sprayed Cr coatings have been successfully converted to Cr3C2, with the mechanism of conversion being strongly influenced by the initial porosity in the as-deposited coatings

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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...... obtained by low-temperature gaseous carburizing of AISI 316. X-ray diffraction was applied for the determination of lattice spacing depth profiles by destructive depth profiling and reconstruction of the original lattice spacing profiles from the measured, diffracted intensity weighted, values. The...... compressive stress depth distributions correlate with the depth distribution of the strain-free lattice parameter, the latter being a measure for the depth distribution of carbon in expanded austenite. Elastically accommodated compressive stress values as high as -2.7 GPa were obtained, which exceeds the...

  4. Surface passivation of crystalline silicon by amorphous silicon carbide films for photovoltaic applications

    OpenAIRE

    Ferré Tomàs, Rafel

    2008-01-01

    En aquesta tesi s'estudia la passivació del silici cristal·lí per a la producció de cèl·lules solars d'alta eficiència (> 20%) a baix preu.Actualment la indústria fotovoltaica empra capes de nitrur de silici crescut mitjançant la tècnica PECVD. Com a alternativa, es presenta el carbur de silici amorf (a-SiC), també crescut mitjançant PECVD. Resultats anteriors mostren que la passivacio del silici a partir de carbur de silici amorf son excel·lents quan el material és ric en silici i dopat amb ...

  5. 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.

  6. 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 ...

  7. 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.

  8. 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.

  9. 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.

  10. 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)

  11. Thermodynamics of the hydrogen-carbon-oxygen-tungsten system, as applied to the manufacture of tungsten and tungsten carbide

    International Nuclear Information System (INIS)

    The thermodynamics of the quaternary hydrogen-carbon oxygen-tungsten system and its binary and ternary sub-systems are reviewed. Published thermodynamic data are evaluated, and expression for free energies of formation are chosen. These expressions are integrated with and equilibrium-calculating algorithm, producing a powerful tool for understanding and improving the manufacture of tungsten and tungsten carbide. Three examples are presented: reduction/carburization of tungstic oxide with hydrogen, carbon, and methane. (author)

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

    OpenAIRE

    Michalski, Jacek

    2015-01-01

    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 struct...

  13. 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。

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

    OpenAIRE

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

    2001-01-01

    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 c...

  15. Simulation of creep test on 316FR stainless steel in sodium environment at 550degC

    International Nuclear Information System (INIS)

    In sodium environment, material 316FR stainless steel risks to suffer from carburization. In this study, an analysis using a Fortran program is conducted to evaluate the carbon influence on the creep behavior of 316FR based on experimental results from uni-axial creep test that had been performed at temperature 550degC in sodium environment simulating Fast Breeder Reactor condition. As performed in experiments, two parts are distinguished. At first, elastic-plastic behavior is used to simulate the fact that just before the beginning of creep test, specimen suffers from load or stress much higher than initial yield stress. In second part, creep condition occurs in which the applied load is kept constant. The plastic component should be included, since stresses increase due to section area reduction. For this reason, elastic-plastic-creep behavior is considered. Through time carbon penetration occurs and its concentration is evaluated empirically. This carburization phenomena are assumed to affect in increasing yield stress, decreasing creep strain rate, and increasing creep rupture strength of material. The model is capable of simulating creep test in sodium environment. Material near from surface risks to be carburized. Its material properties change leading to non-uniform distribution of stresses. Those layers of material suffer from stress concentration, and are subject to damage. By introducing a damage criteria, crack initialization can thus be predicted. And even, crack growth can be evaluated. For high stress levels, tensile strength criterion is more important than creep damage criterion. But in low stress levels, the latter gives more influence in fracture. Under high stress, time to rupture of a specimen in sodium environment is shorter than in air. But for stresses lower than 26 kgf/mm2, the time to rupture of creep in sodium environment is the same or little longer than in air. Quantitatively, the carburization effect at 550degC is not important. This

  16. 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 ...

  17. 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...

  18. 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...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Systems design of advanced gear steels

    Science.gov (United States)

    Wise, John Patrick

    A new generation of Ni-Co secondary hardening gear steels has been developed using a systems approach. These high toughness ultrahigh-strength martensitic steels show great promise for demanding gear applications. Quantitative science-based modeling was used to create prototype alloys of superior strength and fatigue resistance over conventional steels. Carburizing and strengthening models were developed to relate processing parameters to microstructure and microstructure to strength. The failure of the DICTRA software to accurately predict the carburizing behavior of Ni-Co steels led to a series of experiments to refine its kinetic database. New carbon diffusivities were calculated from the concentration gradients of carburized model alloys, resulting in a significant improvement of simulation accuracy. A structure/property model was created to equate the strength of a secondary hardening steel to the sum of the effects of solid solution, precipitates, dislocation density, and the substructure of the lath martensite matrix. The strengthening model was subsequently combined with the carburizing simulations to predict the hardness gradient in a case-hardened alloy based upon initial carburizing conditions. In addition, existing precipitation theory was used in conjunction with the microstructure/strength relationship to simulate the evolution of material hardness during secondary hardening. The creation of three prototype gear steels began with the use of the strengthening model to establish the carbon and alloying element contents required to reach the core and case hardness objectives of 50 and 70 HRC respectively. The design approach also included the establishment of proper transformation and solution temperatures and the maximization of the efficiency of the Msb2C carbide strengthening dispersion. The core hardnesses of the C3-A and B prototypes significantly exceeded the design goal. A reduction in core carbon content from 0.16 to 0.12 weight percent was

  5. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

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

  7. Gas-Turbine and Advanced-HTGR Materials Screening Test Program. Semiannual progress report for the period March 31, 1977--September 30, 1977

    International Nuclear Information System (INIS)

    During the reporting period controlled impurity helium and air creep-corrosion tests on the original (Group I) 17 alloys in the program reached a maximum 14,000 hr duration, and similar tests on 9 additional (Group II) alloys reached a maximum of 5000 hr. The parallel unstressed controlled impurity helium and air fracture behavior tests on the same alloys reached a maximum of 10,000 hr. The initial tests in the parametric helium impurity corrosion study, which are investigating the effect of methane variation, were initiated and exceeded 1000 hr duration. The results of detailed metallurgical analyses and post-exposure tensile testing on the Group II alloys after 3000 hr stressed and unstressed exposure in controlled impurity helium at 800 to 10000C are reported. Data for the wrought austenitic alloys Hastelloy X (new heat), Hastelloy S, RA 333, and HD 556 and the cast austenitic alloys HK 40, Supertherm, Manaurite 36X, Manaurite 36XS, and Manaurite 900 are reported. All alloys carburized significantly at 900 and 10000C, with minor increases of carbon content exhibited at 8000C. The alloys were grouped with respect to the morphology of their oxide/carbide corrosion scales and the composition of these scales as identified by SEM microprobe analyses. Generally, carburization depths at 10000C were greater in the wrought alloys than in the cast alloys. Room-temperature tensile properties of the wrought alloys were more severely affected by impure helium exposure than were the tensile properties of the helium-exposed cast alloys. Decreases in ductility of the exposed wrought alloys, presumably caused by carburization, were greater than would be expected from thermal aging alone

  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. 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.

  10. The foil equilibration method for carbon in sodium

    International Nuclear Information System (INIS)

    Among the non-metallic impurities in sodium, carbon plays an important role since at high temperatures the structural materials exposed to sodium are subject to carburization and decarburization depending on the carbon activity of the sodium. Carburization of austenitic stainless steels leads to reduction in ductility and fatigue properties whereas decarburization results in a decrease in the high temperature creep strength. A knowledge of the carbon activities in sodium will help understanding of the carbon transfer phenomena in operating sodium systems of the fast reactors, and also carbon diffusion, microstructural stability and mechanical behaviour of materials under different service conditions. An understanding of the carbon behaviour in sodium becomes difficult in view of the complexities of the different species present as elemental carbon, carbide, acetylide, carbonate, and cyanide. Carbon estimation techniques for sodium presently in use are: chemical analytical methods, on-line carbon monitors, and oil equilibration method. Various chemical methods have been developed for the estimation of different species like acetylide, cyanide, carbonate, elemental carbon, and total carbon in sodium. All these methods are time consuming and subject to various errors. The on-line monitors developed for carbon in sodium are able to give continuous indication of carbon activities and have higher sensitivity than the chemical methods. A still more simple method for the determination of carbon activities is by the foil equilibration first published by Natesan et al. Because of its simplicity like the vanadium wire equilibration for oxygen it is being used widely for the estimation of carbon activities in sodium systems. Carbon concentrations in operating sodium systems estimated by this procedure by applying solubility relation to carbon activities have yielded very low values of carbon, lower than the sensitivity limits of the chemical estimation methods. Foil

  11. 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.

  12. 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.

  13. 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.

  14. An experimental investigation on DI diesel engine with hydrogen fuel

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, N.; Nagarajan, G.; Narayanasamy, S. [Internal Combustion Engineering Division, Department of Mechanical Engineering, College of Engineering, Guindy, Anna University, Chennai 600 025 (India)

    2008-03-15

    The internal combustion engines have already become an indispensable and integral part of our present day life style, particularly in the transportation and agricultural sectors [Nagalingam B. Properties of hydrogen. In: Proceedings of the summer school of hydrogen energy, IIT Madras, 1984]. Unfortunately the survival of these engines has, of late, been threatened due to the problems of fuel crisis and environmental pollution. Therefore, to sustain the present growth rate of civilization, a nondepletable, clean fuel must be expeditiously sought. Hydrogen exactly caters to the specified needs. Hydrogen, even though ''renewable'' and ''clean burning'', does give rise to some undesirable combustion problems in an engine operation, such as backfire, pre-ignition, knocking and rapid rate of pressure rise [Srinivasa Rao P. Utilization of hydrogen in a dual fueled engine. In: Proceedings of the summer school of hydrogen energy, IIT Madras, 1984; Siebers DL. Hydrogen combustion under diesel engine conditions. Hydrogen Energy 1998;23:363-71]. The present investigation compares the performance and emission characteristics of a DI diesel engine with gaseous hydrogen as a fuel inducted by means of carburation technique and timed port injection technique (TPI) along with diesel as a source of ignition [Swain N, Design and testing of dedicated hydrogen-fueled engine. SAE 961077, 1996]. In the present study the specific energy consumption, NO{sub x} emission and the exhaust gas temperature increased by 6%, 8% and 14%, respectively, and brake thermal efficiency and smoke level reduced by 5% and 8%, respectively, using carburation technique compared to baseline diesel. But in the TPI technique, the specific energy consumption, exhaust gas temperature and smoke level reduced by 15%, 45% and 18%, respectively. The brake thermal efficiency and NO{sub x} increased by 17% and 34%, respectively, compared to baseline diesel. The emissions such as HC

  15. 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.

  16. 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.

  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. 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.

  19. Effect of carbon on the oxidation of zirconium; Influence du carbone sur l'oxygenation du zirconium a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Chauvin, G.; Boudouresques, B.; Coriou, H.; Hure, J. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    The study of specimens contaminated by different amounts of carbon shows a deleterious effect of this element in the resistance of zirconium to high temperature oxidation (700 to 900 deg. C). We drew the following results: a) the white spots or 'pimples' observed by numerous authors seem to be caused by the oxidation of precipitated carbides. We suggest a mechanism of formation and growth of these pimples; b) for a certain carbon content, the resistance to oxidation is increased by an uniform dispersion of the carbide phase and decreased, for instance, by extrusion textures. In this case, for the more marked textures, the more oriented corrosion was observed; c) by burning of the carbide phase it can result a second reaction increasing the corrosion rate; d) thin zirconium foils undergoes dimensional changes when scaling in oxygen. This unusual feature is also subordinated to carbon content and specially to the carbide phase dispersion. (author) [French] L'etude d'echantillons differemment contamines par le carbone nous a permis de mettre en evidence l'action particulierement nocive de cet element sur la resistance du zirconium a la corrosion par l'oxygene a haute temperature (700 a 900 deg. C). Nous avons pu degager les resultats essentiels suivants: a) l'origine des pustules d'oxyde blanc signalees par de nombreux auteurs doit etre recherchee dans l'oxydation des carbures precipites. Nous suggerons un mecanisme de formation et de croissance de ces pustules, b) la tenue du metal est d'autant meilleure que, pour une meme teneur en carbone, la phase 'carbure' est plus uniformement dispersee. En consequence, si la dispersion est mauvaise, on observe selon l'axe des textures de filage, par exemple, une corrosion preferentielle d'autant plus accentuee que les textures sont plus marquees, c) la combustion de la phase 'carbure' peut engendrer une reaction secondaire susceptible d

  20. 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.

  1. A computational model for the carbon transfer in stainless steel sodium systems

    International Nuclear Information System (INIS)

    A method is proposed of computing the carbon transfer in the type 316, 304 and 321 stainless steels in sodium environment as a function of temperature, exposure time and carbon concentration in the sodium. The method is based on the criteria developed at ANL by introducing some simplifications and takes also into account the correlations obtained at WARD. Calculated carbon profiles are compared both with experimental data and with the results available by the other computer methods. The limits for quantitative predictions of the stainless steel carburization or decarburization exposed in a specific environment are discussed. (author)

  2. 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...

  3. Transformaciones de inequilibrio producidas por ciclos anisotérmicos en aceros inoxidables martensíticos tipo 13Cr y 14CrMoV

    OpenAIRE

    Álvarez Moreno, Luisa Fernanda

    1991-01-01

    Diversas investigaciones en el campo de las transformaciones de inequilibrio en estado sólido han intentado buscar explicación a ciertos comportamientos atípicos observados en el desarrollo de la transformación martensítica de aceros aleados con elementos carburíqenos, tales como el cromo, molibdeno, vanadio y wolframio. En estos aceros aleados, la transformación anisotérmica de la austenita en rnartensita no se realiza de forma continua durante el enfriamiento en un intervalo determinado de ...

  4. 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.

  5. 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.

  6. Technology of processing furnaces for refining and petrochemistry. Criteria for the choice of materials for pipes of bundles

    Energy Technology Data Exchange (ETDEWEB)

    Pingeot, M. (ENSEEG, Grenoble (France))

    1981-12-01

    The present state of technology is examined for the determination of steel types as a function of service conditions: temperature, pressure and corrosion. Austenitic structure, grain size, carbon content and additional elements are studied for creep resistance at a temperature of 1000 and a pressure up to 300 atmospheres. Influence of hydrogen, sulfhydric acid, polythionic acids, naphtenic acids and carburation on internal corrosion of pipes is examined and also oxidation and attack by fuel oil ashes of the external surfaces for different types of steels. Precautions to be taken for welding of chromium mobybdenum steels and austenitic stainless steels are indicated.

  7. Kinetics of Hydrocarbon formation in a-C:H film deposition plasmas

    International Nuclear Information System (INIS)

    The formation of C2 and C3 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 mechanism 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 carburized metal. (Author)

  8. 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...

  9. 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...

  10. 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.

  11. Wear properties of metal ion implanted 4140 steel

    International Nuclear Information System (INIS)

    AISI type 4140 (high tensile) steel has been implanted with tungsten and titanium using a metal vapour vacuum arc ion source. Doses in the range (1-5)x1016ionscm-2 were implanted to a depth of approximately 30nm. The relative wear resistance between non-implanted and implanted specimens has been estimated using pin-on-disc and abrasive wear tests. Implantation of titanium decreased the area of wear tracks by a factor of 5 over unimplanted steel. In some cases the steel was also hardened by a liquid carburization treatment before implantation. Abrasion tests revealed a further improvement in wear resistance on this material following ion irradiation. ((orig.))

  12. Static and cyclic strength of bimetal prepared by surfacing method

    International Nuclear Information System (INIS)

    The effect is studied of the magnitude of the operating repeated static load and the number of changes in heat conditions upon the development of diffusion bimetal interlayers (low-carbon unalloyed structural steel plus austenitic highalloy steel). When the material is heated at elevated temperatures under stress and when the temperature and stress change cyclically, the diffusion processes are accelerated. Then in the basic metal there appear decarbonization zones, whereas in the filler metal, carburization zones. The statical strenght is minium in the basic metal, the cyclical strength, in the diffusion zone metal

  13. Impact des propriétés des gaz d'échappement recyclés sur l'initiation et le déroulement de la combustion : caractérisation paramétrique de la réactivité de l'EGR

    OpenAIRE

    Piperel, Aurélie

    2008-01-01

    Du fait des nouvelles réglementations sur les émissions de polluants à l'échappement, de nouveaux procédés de combustion LTC (Low Temperature Combustion) tels que le HCCI (Homogeneous Charge Compression Ignition) ont vu le jour. En effet, en mode HCCI, peu de particules et peu d'oxydes d'azote sont émis, mais il est nécessaire de contrôler précisément l'initiation et le déroulement de la combustion : soit par des solutions technologiques novatrices, soit par une formulation de carburant appro...

  14. Amélioration des performances des moteurs à combustion par amélioration du système d'allumage

    OpenAIRE

    Astanei, Dragoş-George

    2014-01-01

    Face aux normes actuelles et futures, de plus en plus drastiques, concernant les émissions de polluants, les constructeurs automobiles cherchent en permanence à améliorer l'efficacité des moteurs à allumage commandé. Une des solutions les plus efficaces et applicables pour diminuer la quantité de polluants émis dans les gaz d’échappement (HC, CO, NOx) et réduire la consommation de carburant, est d’utiliser un mélange très pauvre (richesse du mélange inférieure à 0,6). Toutefois, ce concept de...

  15. Technological applications of Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    A brief review is given of some recent industrial applications of Moessbauer spectroscopy. One of the most desirable futures of the Moessbauer effect is the feasibility of performing in situ measurements. Such measurements are extremely important especially in the upgrading of coal derived liquids. Such applications have been very successful in understanding the role of iron sulfides stoichiometries in direct coal liquefaction. The use of in situ techniques is invaluable in the investigation of the metal support interaction and their relation to carburization processes in Fischer-Tropsch reactions. Emphasis is placed in the use of a multiple technique approach to elucidate scientific problems of industrial importance. (Auth.)

  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. 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 ...

  18. Carbon transfer between 2 1/4 Cr 1 Mo alloy and austenitic steels (experiments in anisothermal loops)

    International Nuclear Information System (INIS)

    Studies on carbon transfer between the ferritic steel 2 1/4 Cr 1 Mo and the austenitic steels 316L and 321H have shown that there is not any measurable carbon transfer in the operating conditions of the secondary circuit of PHENIX (475 deg C was the maximal temperature of the 2 1/4 Cr 1 Mo steel). A significant carbon transfer has been observed between the ferritic steel and the 316L steel when the 321H was replaced by the 2 1/4 Cr 1 Mo steel in the same thermohydraulic conditions (the ferritic steel was then used up to 545 deg C). This experiment has demonstrated the importance of the temperature and the initial carbon content of the ferritic steel as parameters in the decarburization process. It appears that decarburization may not be sensitive to the thermohydraulic conditions at least in the range investigated in those experiments. In the other hand the 316L steel is observed to have been carburized, the degree of carburization remaining appreciably constant and independent on the temperature between 400 deg C and 550 deg C

  19. Application of a commercial diffusion type carbon meter in a sodium circuit

    International Nuclear Information System (INIS)

    The exchange of carbon between structural materials and liquid sodium influences the mechanical properties of components of the cooling circuits. Therefore, the estimation of the carbon content of the alkali metal and the knowledge of its carburizing potential is of importance. Since some years the measurement of the carburizing potential of sodium is easy to perform by the application of the foil equilibration method which leads to good results in spite of the very low carbon concentrations in the liquid metal. Thin foils (0.025 to 0.125 mm) of Fe-18Cr-8Ni-C alloy (corresponding to stainless steel type AISI 304) are immersed in sodium at 550 to 700 deg. C for 200 to 400 hours. The equilibrium of the carbon distribution must be reached. Chemical analyses of the steel tabs and relation of concentration to activity of carbon lead to information on the carbon concentration in the sodium, if the saturation concentration of carbon in sodium is known. The method gives arbitrary values over a longer period of time. The time needed for equilibration and analysis causes a delay for the getting of results. Therefore, there is a need for instruments which are capable to measure carbon directly in the circuits and give continuously information on the actual carbon activities in the fluid. Until 1975 only one carbon meter was commercially available. One unit in was tested a chemical analytical sodium circuit

  20. Porous graphitic carbon nanosheets derived from cornstalk biomass for advanced supercapacitors.

    Science.gov (United States)

    Wang, Lei; Mu, Guang; Tian, Chungui; Sun, Li; Zhou, Wei; Yu, Peng; Yin, Jie; Fu, Honggang

    2013-05-01

    Porous graphitic carbon nanosheets (PGCS) are synthesized by an in situ self-generating template strategy based on the carburized effect of iron with cornstalks. Cornstalks firstly coordinate with [Fe(CN)(6)](4-) ions to form the cornstalk-[Fe(CN)(6)](4-) precursor. After carbonization and removal of the catalyst, PGCS are obtained. Series experiments indicate that PGCS can only be formed when using an iron-based catalyst that can generate a carburized phase during the pyrolytic process. The unique structures of PGCS exhibit excellent capacitive performance. The PGCS-1-1100 sample (synthesized from 0.1 M [Fe(CN)(6)](4-) with a carbonization temperature of 1100 °C), which shows excellent electrochemical capacitance (up to 213 F g(-1) at 1 A g(-1)), cycling stability, and rate performance in 6 M KOH electrolyte. In the two-electrode symmetric supercapacitors, the maximum energy densities that can be achieved are as high as 9.4 and 61.3 Wh kg(-1) in aqueous and organic electrolytes, respectively. Moreover, high energy densities of 8.3 and 40.6 Wh kg(-1) are achieved at the high power density of 10.5 kW kg(-1) in aqueous and organic electrolytes, respectively. This strategy holds great promise for preparing PGCS from natural resources, including cornstalks, as advanced electrodes in supercapacitors. PMID:23606450

  1. 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)

  2. 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)

  3. Single-step non-thermal plasma synthesis of 3C-SiC nanoparticles

    International Nuclear Information System (INIS)

    We present a scalable, single-step, non-thermal plasma synthesis technique for the growth of sub-5 nm, hydrogenated amorphous carbon (a-C:H) coated 3C-SiC nanoparticles (NPs). In a tubular flow reactor, we first nucleate and grow c-Si NPs upstream in a SiH4/Ar plasma. These c-Si NPs are then transported by gas flow to a downstream C2H2/Ar plasma, and carburized in-flight by carbon-containing radicals and ions to 3C-SiC NPs. X-ray diffraction and transmission electron microscopy indicate an NP size of ∼4 nm. X-ray photoelectron spectroscopy analysis confirms that the c-Si NPs are completely carburized to 3C-SiC. Fourier transform infrared spectroscopy shows that the surface of the 3C-SiC NPs is coated with a-C:H with some alkenyl termination, which can facilitate further solution-based surface functionalization for biomedical applications. (paper)

  4. 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.

  5. The tensile properties of alloys 800H and 617 in the range 20 to 950deg C

    International Nuclear Information System (INIS)

    The tensile properties of Alloy 800H and Alloy 617 in the solution treated condition and after ageing or carburization have been determined for the temperature range 20 to 950deg C. It was found that ageing at 900deg C prior to testing led to an increase in strength and a decrease in ductility at test temperatures up to 700deg C. Above 700deg C, there was no significant difference between the tensile properties of solution treated and aged material. Carburization caused a severe loss of ductility in both alloys at temperatures of 20 to around 800deg C, but the ductility increased sharply at test temperatures above 800deg C, accompanied by a change in the fracture mode from fracture of the carbide particles themselves to void formation and separation at the carbide/matrix interface. The correlation between tensile properties and creep data was investigated in tests carried out at different strain rates. Reasonable agreement was found at 800 to 950deg C for Alloy 617 and at 800 to 900deg C for Alloy 800H. Strain ageing effects were observed in both alloys at some temperatures and strain rates; these effects were serrated flow, negative strain rate sensitivity, peaks in the normalized UTS-temperature curves and plateaus in the elongation-temperature curves. The experimental results were interpreted in the light of two current models for strain ageing, the dislocation-dislocation interaction model and the dislocation-solute interaction model. (orig.)

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

    International Nuclear Information System (INIS)

    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

  7. 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)

  8. Effect of yttrium on the coking behavior of Fe-based superalloy in heavy hydrocarbon

    International Nuclear Information System (INIS)

    Graphical abstract: Compared with bare specimen (a), specimen doped with yttrium (b) shows the elimination of the intergranular coking behavior of Fe-based superalloy and changes the coke morphology. - Highlights: • Effect of Y on the coking behavior of Fe-based superalloy was studied. • The alloy doped with Y exhibits the better coking and carbonizing resistance. • Y doped in the alloy eliminates the intergranular coking and carbonization. - Abstract: Effect of the rare earth element yttrium on the coking behavior of Fe-based superalloy has been studied. The coking process of Fe-based superalloy during dodecane pyrolysis includes three stages – incubation period, coke protrusions growing and graphite layer stacking. Fe-based superalloy with yttrium addition exhibits the better coking and carburization resistance. The reason is that Y doped in Fe-based superalloy eliminates the intergranular coking and carburization by forming yttrium oxides to inhibit the aggregation of Cr2O3 at the grain boundary in initial period of coking behavior, thus internal Cr2O3 layer forms and effectively blocks the permeation of outer graphite

  9. 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.

  10. 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.

  11. 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)

  12. Properties of structural materials for sodium-cooled fast breeder reactor

    International Nuclear Information System (INIS)

    For the selection of the structural materials for superheaters and reheaters of sodium-cooled fast breeder reactors, it is important to grasp the change of strength due to the complex change of material properties, such as the combination of surface corrosion, the decarbonization of 2-1/4 Cr-1Mo steel, the carburization of austenitic stainless steel, the structural change due to heating history, etc. in sodium environment. The stress corrosion cracking of austenitic materials in water must be studied also. The materials taken up in this paper are austenitic stainless steels such as SUS 304, SUS 316, SUS 321, and SUS 347, iron-based superalloy Incoloy 800, and ferritic alloy steel 2-1/4Cr-1Mo steel. The data on the above described properties of the materials are given. Also the tensile strength, creep rupture and fatigue characteristics of the parent materials in the amount of corrosion in sodium. The strength of ferritic alloy steel is lowered owing to the decarbonization in sodium, but the change of strength due to carburization was not observed. There is some possibility that the unstabilized steels such as SUS 304 and SUS 316 become sensitive to stress corrosion cracking, and the stabilized steels such as SUS 321 and SUS 347 become sensitive to it in long hour heating. The tensile strength of welded joints is almost same as that of parent materials, but the elongation decreases by about 10%. (Kako, I.)

  13. 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.

  14. Study of Softening and Melting Behaviour of Iron Ore Sinter and Pellets

    Science.gov (United States)

    Shatokha, Volodymyr; Velychko, Olexandr

    2012-06-01

    Softening and melting behaviour of the iron ore materials was studied towards understanding the mechanism of formation of liquid slag and metal phases in the pre-reduced sinter and pellets. Wide range of the sinter and pellets samples was investigated revealing the effect of gangue amount and composition on temperature indices corresponding to gas permeability loss in the bed (T1) and to the largest portion of liquid products dripping (T2). For both sinter and pellets, the growth of bacisity is followed by T1 increase which is explained by raised temperature of primary liquid phase appearance during the heating-reduction treatment. Relationship of T2 with the bacisity corresponds to the basicity effect on slag liquidus temperature. Both slag and metal phases were only partially evacuated from the crucible with essential portions of both phases captured in the coke bed. Growing divergence of the basicities of effluent slag and of slag captured in crucible was observed with the increase of sinter basicity. Increased share of the effluent metal with the sinter bacisity growth is explained by the decreased adhesion of slag to iron surface which assists carburization. Growth of melt-down temperature with the increase of gangue amount is explained by less active carburization owing to larger quantity of slag minimising direct contact of sponge with carbonaceous materials.

  15. 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.

  16. 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.

  17. Microstructure analysis and wear behavior of titanium cermet femoral head with hard TiC layer.

    Science.gov (United States)

    Luo, Yong; Ge, Shirong; Liu, Hongtao; Jin, Zhongmin

    2009-12-11

    Titanium cermet was successfully synthesized and formed a thin gradient titanium carbide coating on the surface of Ti6Al4V alloy by using a novel sequential carburization under high temperature, while the titanium cermet femoral head was produced. The titanium cermet phase and surface topography were characterized with X-ray diffraction (XRD) and backscattered electron imaging (BSE). And then the wear behavior of titanium cermet femoral head was investigated by using CUMT II artificial joint hip simulator. The surface characterization indicates that carbon effectively diffused into the titanium alloys and formed a hard TiC layer on the Ti6Al4V alloys surface with a micro-porous structure. The artificial hip joint experimental results show that titanium cermet femoral head could not only improve the wear resistance of artificial femoral head, but also decrease the wear of UHMWPE joint cup. In addition, the carburized titanium alloy femoral head could effectively control the UHMWPE debris distribution, and increase the size of UHMWPE debris. All of the results suggest that titanium cermet is a prospective femoral head material in artificial joint. PMID:19836751

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. Analyse Thermodynamique en Dimensions Finies du Système Pile à Combustible

    OpenAIRE

    Vaudrey, Alexandre

    2009-01-01

    En tant que système producteur de puissance électrique continue, la pile à combustible est souvent considérée de la même manière qu'une batterie. Il s'agit cependant d'un système ouvert qui utilise l'énergie chimique portée par un couple carburant/comburant, pour produire du travail, électrique en l'occurrence. Elle peut ainsi être considérée comme un type particulier de moteur thermique à combustion interne. Partant de cee simple réflexion, nous représentons dans cette thèse la pile à combu...

  4. Compatibility of steel No. 1.4970 with liquid sodium at high temperatures

    International Nuclear Information System (INIS)

    The sodium corrosion and the influence of liquid sodium at 873 and 973 K on the creep strength of cladding tubes of steel No. 1.4970 was studied in a sodium loop. The corrosion and creep tests with cladding tube specimens were extended up to 10 000 h. The mass losses showed an effect of the oxygen content in the sodium loop which was controlled by means of a cold trap. The exposure to sodium caused chemical changes as losses of chromium, nickel and manganese and the carbon concentrations were increased in the outer zones of the material. The boron content of the steel was significantly reduced. Despite the changes of the chemical composition of the material, the time to the creep deformation of 1% at 973 K was not influenced by the sodium corrosion. This might be due to the carburization of the steel. All corrosion effects were only marginal at 873 K

  5. 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.

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

    Science.gov (United States)

    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.

  7. ASSET, An Information System for Alloy Corrosion in High Temperature Gases

    International Nuclear Information System (INIS)

    A large database for corrosion data and a corrosion prediction information system for metals and alloys corroding in high-temperature gases have been created. Corrosion data for about 75 commercial alloys, 4600 corrosion data measurements, and six million exposure hours have been compiled into an information system, ASSET. ASSET allows prediction of sound metal thickness losses for metals and alloys corroding by several common corrosion mechanisms at high-temperatures as functions of gas composition, temperature, time, and alloy. This paper presents examples of predicted metal losses of alloys corroding in standard conditions for several corrosion mechanisms expected in high-temperature gases. ASSET also provides a comprehensive capability to analyze the thermochemical interactions between alloys, corrosion products and exposure conditions. Some of the uses of the data compilation and the corrosion prediction feature are illustrated for oxidizing, sulfidizing, sulfidizing/oxidizing , and carburizing conditions

  8. 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.

  9. Computer simulation of diffusion in multiphase systems

    Science.gov (United States)

    Engström, Anders; Höglund, Lars; Ågren, John

    1994-06-01

    A general model to treat multicomponent diffusion in multiphase dispersions is presented. The model is based on multicomponent diffusion data and basic thermodynamic data and contains no adjustable parameters. No restriction is placed on the number of components or phases that take part in the calculations, as long as the necessary thermodynamic and kinetic data are available. The new model is implemented into the DICTRA software, which makes use of THERMO-CALC to handle the thermodynamics. The model is applied to carburization of Ni alloys and heat treatment of welded joints between dissimilar materials. In both cases, the diffusion is accompanied by carbide formation or dissolution. A good agreement between experiments and calculations is found, despite the fact that no adjustable parameters are needed.

  10. Post irradiation examinations of 87F-2A capsule containing uranium-plutonium mixed carbide fuels

    International Nuclear Information System (INIS)

    One fuel pin filled with hyperstoichiometric uranium-plutonium mixed carbide pellets was encapsulated in 87F-2A and irradiated in JMTR up to 4.4 %FIMA at an average linear power of 60 kW/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 section of fuel pin that the helium gap between the pellets and the cladding tube was completely closed. Compared with the results obtained so far, very low open porosity and fission gas release rate as well as mild restructuring was observed owing to the adoption of thermally stable pellets. The diametric increase of fuel pin reached ∼0.06mm at the position of maximum reading, although it might not affect the fuel performance itself. The inner surface of cladding tube did not show signs of carburization. (author)

  11. 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...

  12. Measurement of carbon activity of sodium using nickel tabs and the Harwell Carbon Meter - Preliminary experience

    International Nuclear Information System (INIS)

    Carbon can have an important effect on the mechanical properties of certain constructional materials likely to be used in the LMFBRs. Transfer of carbon will occur between the metal and the sodium at any particular location to bring the chemical potential of carbon in both components to the sam: value. Thus, in a mixed system containing austenitic stainless steel and unstabilized ferritic steel, carbon could be transferred by the sodium from the high carbon activity ferritic to the lower activity austenitic steel. Loss of carbon from the unstabilized ferritic steel leads to a weaker, more ductile material, while carburization of the stainless steel could lead to its embrittlement. Similarly carbon entering the coolant in the form of oil from leaking mechanical pumps could have similar effects on the mechanical property of stainless steels. In the light of these possibilities it is essential to measure the carbon activity of the sodium so that its effect on materials properties can be predicted

  13. 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.

  14. 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

  15. Utilització de l'oli de colza com a biocarburant en explotacions agrícoles

    OpenAIRE

    Esteban Dalmau, Bernat; Baquero Armans, Grau; Puig Vidal, Rita; Riba Ruiz, Jordi-Roger; Rius Carrasco, Antoni

    2010-01-01

    La utilització de l’oli de colza com a carburant és una tecnologia que ja s’utilitza a altres països europeus com Alemanya i Dinamarca, degut principalment a dos factors: el gasoil agrícola està menys subvencionat i el grau de conscienciació mediambiental és major en aquest països. L’oli de colza és un biocarburant que s’obté del premsat de llavors de plantes oleaginoses i que, realitzant una petita modificació al sistema d’alimentació dels motors dièsel, pot ser utilitzat com a comb...

  16. Effect of slag composition on iron nuggets formation from carbon composite pellets

    Directory of Open Access Journals (Sweden)

    Alberto Eloy Anduze Nogueira

    2010-06-01

    Full Text Available Iron-carbon nuggets can be obtained by high temperature reduction of iron ore by carbonaceous material when both are agglomerated together as a carbon composite pellet. During this process, the stable oxides contained in the materials will form a slag. This work investigates the effect of this slag composition on iron nugget formation. Pellets were prepared with iron ore and two different carbonaceous materials. Through the addition of Portland® cement, silica and alumina the slag composition was varied to adjust the expected liquidus temperature to 1573 and 2273 K. It has been shown that the formation of iron nuggets is favored for slags presenting low liquidus temperature. In order to further investigate this phenomenon, pellets containing iron powder and carbonaceous material, together with previously prepared slags, were also submitted to high temperature, and it has been shown that iron carburization depends on slag composition.

  17. 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...

  18. 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...

  19. 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 ...

  20. 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.

  1. 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.

  2. 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)

  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. Etude de la structure des flammes diphasiques dans les brûleurs aéronautiques

    OpenAIRE

    Hannebique, Gregory

    2013-01-01

    La régulation des polluants a mené à la création de nouveaux systèmes de combustion. Le carburant étant stocké sous forme liquide, sa transformation jusqu’à sa combustion est complexe. La capacité de la Simulation aux grandes échelles à simuler des écoulements turbulents réactifs a été montrée sur des cas académiques comme sur des configurations industrielles, tout en prenant en compte les phénomènes multiphysiques intervenant dans ces configurations, mais les études sur la structure de flamm...

  5. 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...

  6. 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.

  7. 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...

  8. 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)

  9. 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.

  10. 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.)

  11. La production industrielle sous la IVe République

    OpenAIRE

    Michel Catinat

    1981-01-01

    [fre] A partir d'un instrument nouveau, les comptes trimestriels de la période 1946-1962, cet article essaie de décrire les fluctuations économiques du système productif pendant la quatrième république. Il est centré uniquement sur les branches énergétiques (combustibles minéraux solides et gaz, électricité, pétrole, gaz naturel et carburants) et sur les branches industrielles (mines de fer et sidérurgie, minerais et métaux non ferreux, industries mécaniques et électriques, chimie et caoutcho...

  12. 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.

  13. High temperature materials for radioactive waste incineration and vitrification. Revision 1

    International Nuclear Information System (INIS)

    Incineration or vitrification of radioactive waste subjects equipment to alkaline or acidic fluxing, oxidation, sulfidation, carburization, and thermal shock. It is necessary to select appropriate materials of construction and control operating conditions to avoid rapid equipment failure. Nickel- and cobalt-based alloys with high chromium or aluminum content and aluminum oxide/chromium oxide refractories with high chromium oxide content have provided the best service in pilot-scale melter tests. Inconel 690 and Monofrax K-3 are being used for waste vitrification. Haynes 188 and high alumina refractory are undergoing pilot scale tests for incineration equipment. Laboratory tests indicate that alloys and refractories containing still higher concentrations of chromium or chromium oxide, such as Inconel 671 and Monofrax E, may provide superior resistance to attack in glass melter environments

  14. 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

  15. 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.

  16. Ion nitriding; Proceedings of the International Conference, Cleveland, OH, Sept. 15-17, 1986

    Science.gov (United States)

    Spalvins, T. (Editor)

    1987-01-01

    The present conference discusses plasma-assisted surface coating/modification processes, the applications to date of ion nitriding, the effects of nitrogen on metal surfaces, ion nitriding mechanisms in Cr, Al and Cr + Al-containing 1040 steel, ion nitriding of Al and its alloys, life enhancement for forging dies, novel anode plasma nitriding developments, and a comparative study of the pulsed and dc ion-nitriding behavior in specimens with blind holes. Also discussed are the influence of heating method on ion nitriding, surface hardening of marage steels by ion nitriding without core hardness reduction, plasma nitriding of nodular cast iron sput gears, NbN composites for superconductors, the carburization of tungsten in a glow discharge methane plasma, economic considerations concerning plasma nitriding, and the corrosion properties obtained by ion nitriding.

  17. Study of Thermal Fatigue of H13 Die Steel with Various Surface Treatments

    Science.gov (United States)

    Ivanov, V. V.; Ferguson, W. G.; Paine, I. R.

    Surfaces of die-casting dies are subjected to very severe conditions of cyclical thermal and mechanical load, and chemical and mechanical wear. Dies mostly fail due to a combination of heat checking, erosion, corrosion and soldering. It is conceivable that appropriate surface treatments and coatings have a favourable influence on the temperature dependant performance of the surface of the die. The objective of this study was to examine various surface treatments and coatings. including shot peening, nitriding, nitro-carburizing, laser hardening and remelting, electro-spark alloying (deposition) and plasma spraying, under thermal fatigue conditions. Thermal cycling tests were conducted by alternate dipping of treated samples in an LM24 melt and in water. Results and interpretation are presented in this paper. The best thermal fatigue resistance was shown for a double surface treatment of laser hardening plus electro-spark deposition.

  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. 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.

  20. 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.)

  1. 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

  2. Dommages d'irradiation dans Ti3SiC2 : Effets des interactions nucléaires et électroniques

    OpenAIRE

    Nappé, Jean-Christophe; Grosseau, Philippe; Audubert, Fabienne; Guilhot, Bernard; Beauvy, Michel; Benabdesselam, Mourad

    2008-01-01

    Comme pour tout système nucléaire, le concept du combustible pour les réacteurs de IVème génération consiste en des pastilles de combustible conditionnées dans une matrice qui doit contenir les produits de fission. De par leur excellente réfractarité, les carbures sont pressentis pour constituer cette barrière de confinement. Parmi ceux étudiés, le ternaire Ti3SiC2 se distingue par ses propriétés mécaniques particulières : en effet, sa structure nanolamellaire lui confère une certaine plastic...

  3. Thermodynamic analysis of equilibria in Fe-Cr-C alloys and evaluation of their dusting stability in aggressive carboniferous atmospheres

    International Nuclear Information System (INIS)

    Thermodynamic analysis of phase equilibria and reactions in alloys of Fe-Cr-C system are done taking into account all possible stable and metastable states in temperature interval when spontaneous transformation of metal into powder in active carbon-containing gaseous media takes place. It is shown that critical content of chromium, when mechanism of catastrophic carburization changes, is situated in 0.03≤y≤0.055 (2.8-5.1 mass % Cr). It is shown that introduction of chromium into iron alloys could only to slow down but not to prevent destruction of materials on Fe=Cr-C basis in conditions of spontaneous transformation of metal into powder

  4. Chimie des processus biologiques

    OpenAIRE

    Fontecave, Marc

    2016-01-01

    Enseignement Cours : Du CO2 aux carburants, un renversement salutaire Le développement des nouvelles technologies de l’énergie pour l’exploitation des énergies renouvelables, comme l’énergie solaire ou l’énergie éolienne diluées et intermittentes, nécessite celui des procédés de stockage de l’énergie. Une façon de stocker ces énergies est de les transformer en énergie chimique. L’exemple le plus classique est l’électrolyse de l’eau en hydrogène, ce dernier pouvant être en effet ensuite utilis...

  5. Conception et caractérisation de nouveaux catalyseurs pour la photolyse de l'eau

    OpenAIRE

    Sheth, Sujitraj

    2013-01-01

    La photosynthèse artificielle est considérée comme étant un atout capable de fournir des carburants alternatifs et renouvelables par conversion et stockage de l'énergie solaire. Une approche prometteuse consiste en un développement de photo-catalyseurs moléculaires inspirés par des enzymes photosynthétiques naturelles. La première partie de cette thèse concerne les modèles artificiels du photosystème II (qui catalyse l'oxydation d'eau), composé d'un chromophore et d'un relais d'électrons comm...

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Modélisation à l'échelle atomique de matériaux nucléaires du cycle du combustible

    OpenAIRE

    BERTOLUS Marjorie

    2011-01-01

    Ce mémoire d'habilitation à diriger des recherches présente le travail de recherche que j'ai effectué depuis 1999 au CEA Cadarache sur la modélisation à l'échelle atomique de différents matériaux nucléaires non métalliques impliqués dans le cycle du combustible : matériaux hôtes pour radioéléments issus des déchets nucléaires (apatites), matériaux combustibles (en particulier dioxyde d'uranium) et matériaux céramiques de gainage (carbure de silicium). Il s'agit de matériaux complexes à la lim...

  11. 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.

  12. 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).

  13. 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...

  14. Plasma assisted surface coating/modification processes - An emerging technology

    Science.gov (United States)

    Spalvins, T.

    1987-01-01

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation. These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  15. Plasma assisted surface coating/modification processes: An emerging technology

    Science.gov (United States)

    Spalvins, T.

    1986-01-01

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation). These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  16. A contribution to the study of the mixed uranium-plutonium mono-carbides containing small quantities of zirconium

    International Nuclear Information System (INIS)

    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)

  17. Problematic of atmospheric pollution in Lebanon: the better stake is apprehended, the best acts are taken

    International Nuclear Information System (INIS)

    Lebanon has imported in 1996 5000 Kt of carburants causing about 80 Kt of SOx; 40 Kt of NOx; 3 Kt of dusts and 3.5 million tons of CO2. The atmospheric pollution in Lebanon is due to three main sources: - Thermal central of electric production - Industries (cement) - Transportation sector The document describes in tables: the inventory of pollutants and pollutant emissions in 1993 and 2010; industrial and heating gas oil; liquified petroleum gas commercial propane; fuel oil for EDL; consumption of energy in 1996; sectorial distribution of pollutants PPM; emissions of CO2 per tons per habitant in 1993; consumption in 1993 broken down by use and application. Finally, three projects concerning public transportation were presented

  18. 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.

  19. 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...

  20. Chimie bio-inspirée et nanosciences: vers de nouveaux catalyseurs pour la production et l’oxydation de l’hydrogène

    OpenAIRE

    Fontecave, Marc; Artero, Vincent

    2013-01-01

    Il ne fait pas de doute que la source d’énergie renouvelable la plus abondante, très largement supérieure aux contributions potentielles de l’énergie éolienne, géothermique ou hydroélectrique par exemple, est l’énergie solaire. Une façon d’exploiter cette énergie est de la transformer en énergie chimique, de la stocker sous la forme d’un carburant, par exemple l’hydrogène. Ce dernier est, on le sait, une alternative prometteuse à l’utilisation du pétrole, à la fois en raison de la grande quan...

  1. Researches on vanadium and its compounds

    International Nuclear Information System (INIS)

    In this research thesis, the author proposes a new study of the action of some reduction agents on two groups of vanadium compounds, oxides and chlorides. Thus, he reports the study of the circumstances of reduction of vanadium oxides by carbon and of vanadium carburization from these compounds. He also reports the determination of the composition of vanadium melts obtained at high temperatures (either in a vacuum furnace or with an electric arc furnace). In order to determine in which conditions the processing of vanadium oxides could produce the pure metal, the author studied the action of calcium and magnesium on the vanadium pentoxide and trioxide. The second part of the thesis addresses the preparation of pure vanadium from vanadium anhydride chlorides. Then, the author reports the development of processes which could easily produce powdered vanadium

  2. 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.

  3. Materials Science Division second quarterly report for period ending March 15, 1975. [Gasification plant materials

    Energy Technology Data Exchange (ETDEWEB)

    Tevebaugh, A. D.; Weeks, R. W.

    1975-01-01

    Progress in material science studies for coal gasification plants, in particular for the BI-GAS process pilot plant, is reported. The results of slag corrosion tests of various refractories (compositions are given) are presented. The development and testing (by thermal cycling) of protective ceramic coatings on metals is described. The capability for several kinds of nondestructive testing is being developed and some results are reported. A major part of the effort involves the development of mathematical models of wear processes (erosion and corrosion) based on the elastic, plastic and fracture properties of materials and particle size, impact velocity, angle of impact, etc. Another major section involves the behavior of iron and nickel base alloys in the hostile environments expected with respect to oxidation, corrosion, sulfidation, carburization, nitridation and erosion. The investigation of a pipe failure is reported (stress corrosion cracking). (LTN)

  4. 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...

  5. 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

  6. Stability of noble-metal clusters on C/W(110) templates against CO and O2 exposure

    International Nuclear Information System (INIS)

    Full text: Small noble-metal (especially Au) clusters on oxidic supports have gained a lot of attention in the last years due to their high activity and selectivity as catalysts for CO oxidation. The importance of cluster-size effects and the influence of the substrate material are still discussed controversially. We introduce two differently carburized W(110) surfaces R(15x12)C/W(110) and R(15x3)C/W(110) as templates for the growth of different types of Au, Ag and Cu nanoclusters. In a first step towards exploring the catalytic properties these clusters we studied the stability of the nano-clusters against exposure to the reaction gases CO and O2 by scanning tunnelling microscopy. Differences and similarities concerning gas-induced alterations on different types of clusters are discussed. (author)

  7. 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).

  8. 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.)

  9. 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.)

  10. 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...

  11. 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.

  12. Oxidation of iron and steels by carbon dioxide under pressure (1962)

    International Nuclear Information System (INIS)

    After having developed one of the first thermo-balances to operate under pressure, we have studied the influence of the pressure on the corrosion of iron and steels by carbon dioxide. The corrosion was followed by three different methods simultaneously: by the oxidation kinetics, by micrographs, and by radiocrystallography. We have been able to show that the influence of the pressure is not negligible and we have provided much experimental evidence: oxidation kinetics, micrographic aspects, surface precipitation of carbon, metal carburization, the texture of the magnetite layer. All these phenomena are certainly modified by changes in the carbon dioxide pressure. In order to interpret most of our results we have been led to believe that the phenomenon of corrosion by CO2 depends on secondary reactions localised at the oxide-gas interface. This would constitute a major difference between the oxidation by CO2 and that by oxygen. (author)

  13. Transition metal carbides (WC, Mo2C, TaC, NbC) as potential electrocatalysts for the hydrogen evolution reaction (HER) at medium temperatures

    DEFF Research Database (Denmark)

    Meyer, Simon; Nikiforov, Aleksey V.; Petrushina, Irina M.;

    2015-01-01

    at medium temperatures (200-400 degrees C). By introducing a new setup which makes use of molten KH2PO4 as electrolyte, a model system for solid acid membrane electrolyser cells was obtained. Metal carbide coated wires prepared by a two-step oxidation carburization reaction of the metal wire surfaces...... were used as electrodes and allowed the measurement of the intrinsic catalytic properties of different transition metal carbides in direct comparison to Pt at 260 degrees C. Under these conditions, the activity in the hydrogen evolution reaction (HER) followed the order WC > Pt approximate to MO2C > Nb......C > TaC. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved....

  14. Measurement of the activity coefficient of carbon in steels in liquid sodium

    International Nuclear Information System (INIS)

    In sodium cooled fast reactors carbon is both a carbon impurity and element of structural materials. Carbon transfert through liquid sodium can produce carburization or decarburization of structural materials. Carbon content in sodium is determined with thin foils of austenitic alloys, when equilibrium is reached thermodynamic activity of carbon in sodium is deduced from carbon activity in alloys. Studied alloys are FeMn 20%, FeNi 30%, Z2CN 18-10 and Z3CND17-13. Carbon activity of alloys in sodium was between 5.10-3 and 10-1 at 600 and 6500C. Calibration was obtained with the alloys FeNi 30% in gaseous mixtures He-CO-CO2 of known activity

  15. 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...

  16. Bell Helicopter Advanced Rotocraft Transmission (ART) program

    Science.gov (United States)

    Henry, Zachary S.

    1995-06-01

    Future rotorcraft transmissions require key emerging material and component technologies using advanced and innovative design practices in order to meet the requirements for a reduced weight to power ratio, a decreased noise level, and a substantially increased reliability. The specific goals for the future rotorcraft transmission when compared with a current state-of-the-art transmission (SOAT) are: (1) a 25 percent weight reduction; (2) a 10 dB reduction in the transmitted noise level; and (3) a system reliability of 5000 hours mean-time-between-removal (MTBR) for the transmission. This report summarizes the work conducted by Bell Helicopter Textron, Inc. to achieve these goals under the Advanced Rotorcraft Transmission (ART) program from 1988 to 1995. The reference aircraft selected by BHTI for the ART program was the Tactical Tiltrotor which is a 17,000 lb gross weight aircraft. A tradeoff study was conducted comparing the ART with a Selected SOAT. The results showed the ART to be 29 percent lighter and up to 13 dB quieter with a calculated MTBR in excess of 5000 hours. The results of the following high risk component and material tests are also presented: (1) sequential meshing high contact ratio planetary with cantilevered support posts; (2) thin dense chrome plated M50 NiL double row spherical roller planetary bearings; (3) reduced kinematic error and increased bending strength spiral bevel gears; (4) high temperature WE43 magnesium housing evaluation and coupon corrosion tests; (5) flexure fatigue tests of precision forged coupons simulating precision forged gear teeth; and (6) flexure fatigue tests of plasma carburized coupons simulating plasma carburized gear teeth.

  17. Application of the laser pyrolysis to the synthesis of SiC, TiC and ZrC pre-ceramics nano-powders

    International Nuclear Information System (INIS)

    Refractory carbide nano-structured ceramics appear to be promising materials for high temperature applications requiring hard materials such as nuclear energy industry. Such carbide materials are usually obtained with micrometric sizes from the high temperature carbo-reduction of an oxide phase in a raw mixture of C black and titania or zirconia. TiC and ZrC nano-powders were produced from an intimate mixture of oxide nano-grains with free C synthesized by laser pyrolysis from the decomposition of a liquid precursor. The temperature and the duration of the thermal treatment leading to the carburization were decreased, allowing the preservation of the nano-scaled size of the starting grains. A solution of titanium iso-prop-oxide was laser-pyrolyzed with ethylene as sensitizer in order to synthesize Ti/C/O powders. These powders were composed of crystalline TiO2 nano-grains mixed with C. Annealing under argon enabled the formation of TiC through the carburization of TiO2 by free C. The final TiC mean grain size was about 80 nm. Zr/O/C powders were prepared from a solution of zirconium butoxide and were composed of ZrO2 crystalline nano-grains and free C. The same thermal treatment as for TiC, but at higher temperature, showed the formation of crystalline ZrC with a final mean grain size of about 40 nm. These two liquid routes of nano-particles synthesis are also compared to the very efficient gaseous route of SiC nano-powders synthesis from a mixture of silane and acetylene. (authors)

  18. Systems design of high-performance stainless steels

    Science.gov (United States)

    Campbell, Carelyn Elizabeth

    A systems approach has been applied to the design of high performance stainless steels. Quantitative property objectives were addressed integrating processing/structure/property relations with mechanistic models. Martensitic transformation behavior was described using the Olson-Cohen model for heterogeneous nucleation and the Ghosh-Olson solid-solution strengthening model for interfacial mobility, and incorporating an improved description of Fe-Co-Cr thermodynamic interaction. Coherent Msb2C precipitation in a BCC matrix was described, taking into account initial paraequilibrium with cementite. Using available SANS data, a composition dependent strain energy was calibrated and a composition independent interfacial energy was evaluated to predict the critical particle size versus the fraction of the reaction completed as input to strengthening theory. Multicomponent Pourbaix diagrams provided an effective tool for evaluating oxide stability; constrained equilibrium calculations correlated oxide stability to Cr enrichment in the oxide film to allow more efficient use of alloy Cr content. Multicomponent solidification simulations provided composition constraints to improve castability. Using the Thermo-Calc and DICTRA software packages, the models were integrated to design a carburizing, secondary-hardening martensitic stainless steel. Initial characterization of the prototype showed good agreement with the design models and achievement of the desired property objectives. Prototype evaluation confirmed the predicted martensitic transformation temperature and the desired carburizing response, achieving a case hardness of Rsb{c} 64 in the secondary-hardened condition without case primary carbides. Decarburization experiments suggest that the design core toughness objective (Ksb{IC} = 65 MPasurdm) can be achieved by reducing the core carbon level to 0.05 weight percent. To achieve the core toughness objective at high core strength levels requires further analysis of an

  19. 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

  20. Thermal stability and environmental compatibility of Inconel 617

    International Nuclear Information System (INIS)

    The thermal stability and environmental compatibility of Inconel 617, a prime nuclear process heat steam reformer candidate alloy, are described in this paper. This commercially available wrought nickel-base alloy has excellent high-temperature strength but is subject to loss of toughness and ductility due to thermal instability. Work done to improve the thermal stability of this alloy is discussed. Room-temperature tensile and toughness data and microstructural information for Inconel 617 specimens exposed at elevated temperatures are presented. Preliminary data indicate that controlling the chemistry of Inconel 617 can provide a substantial improvement in thermal stability. Preliminary work to define the range of high-temperature gas-cooled reactor (HTGR) primary coolant compositions within which minimal deleterious gas/metal reactions occur with Inconel 617 is described. Within this gas chemistry range a stable surface oxide forms and only slight carburization occurs. In other gas chemistry ranges, rapid carburization or decarburization can occur. The gas corrosion experiments discussed are part of a series of relatively short-term exposures to HTGR helium in which the effects of different H2O concentrations (0.01 to 1.0 Pa) were determined as a function of the systematic variation of a second constituent (CO and CH4 for this work) in the test gas. The composition of the basic HTGR helium was 40 Pa H2, 4 Pa CO, 0.02 Pa CO2, 2 Pa CH4 in helium at 0.2 MPa. Two other CO levels (1 and 12 Pa) and one additional CH4 level (0.63 Pa) were used in these experiments. Experimental exposure methods are discussed and the results of gas-metal interaction studies are presented. These results include carbon analyses and optical and scanning electron microscopy to determine the morphology and type of surface and subsurface microstructures. (author). 15 refs, 6 figs, 5 tabs

  1. 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)

  2. 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.

  3. Scale formation on ferritic and austenitic steels in high CO2/H2O containing gases simulating oxy-fuel environments

    International Nuclear Information System (INIS)

    The oxy-fuel process represents a promising technology for CO2 capture from the exhaust gas in coal fired power plants. The principle of this process consists of burning coal with pure oxygen, a recirculation of the CO2 gas produced and finally a separation of the CO2 from the combustion gases, by various methods which are presently being developed. Depending on the actual process parameters used, a number of metallic heat exchanging components will in the oxy-fuel process be subjected to service environments containing high amounts of CO2 and water vapour. In the present study, the oxidation behaviour of selected commercial ferritic and austenitic steels was investigated in simulated oxy-fuel environments at temperatures in the range 550-650 C. Thereby, the behaviour of the materials in the simulated oxy-fuel gas was compared with that in CO2, H2O and CO2-O2. The experiments showed that ferritic steels components exposed to CO2/H2O gas mixtures, may exhibit substantially higher oxidation rates than during air exposure. The oxidation rates are similar to those observed in service environments of conventional power plants; however the steels exhibit a substantially larger tendency to carburization than in conventional service gases. Austenitic steels exposed to the CO2/H2O atmospheres exhibit oxidation and carburization rates which are strongly dependent on the actual Cr content of the steel and also on component surface preparation. The paper will discuss how the individual species present in the mixed gases affect the scale formation mechanisms especially in respect to their positive or adverse effect on formation of protective chromia base oxide scales. (authors)

  4. 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.

  5. 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.

  6. Fatigue and creep crack propagation behaviour of Alloy 617 in the annealed and aged conditions

    International Nuclear Information System (INIS)

    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 deg. C under constant stress intensity (ΔK) 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 deg. 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 γ' (Ni3Al) after short times, occurred during ageing. 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 deg. C and a stress intensity of K = 40 MPa√(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 ageing or evolution of a crack tip creep zone. Finally, fatigue crack propagation tests at 800 deg. 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 deg. C. (authors)

  7. 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

  8. 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

  9. Exergetic Evaluation of Speed and Load Effects in Spark Ignition Engines Évaluation exergétique des effets de la vitesse et de la charge dans les moteurs àallumage par étincelle

    Directory of Open Access Journals (Sweden)

    Sezer I.

    2012-08-01

    analyse exergétique. Des variables exergétiques comme les transferts exergétiques de chaleur et de travail, les irréversibilités, l’exergie thermomécanique, l’exergie chimique du carburant et l’exergie totale ont été calculées dans l’analyse exergétique. La variation des paramètres exergétiques et leur distribution dans l’exergie du combustible ont été déterminées pour différentes conditions de fonctionnement, c’est à dire différentes vitesses du moteur et différentes charges. L’efficacité déduite, d’une part, de la première et la deuxième loi de la thermodynamique et, d’autre part, de la consommation spécifique de carburant ont également été calculées pour révéler les conditions optimales de fonctionnement. Les résultats montrent que le transfert exergétique de chaleur diminue et que le transfert exergétique par l’échappement augmente avec la vitesse du moteur. Le régime moteur de 3 000 tr/min donne le transfert d’exergie maximal de travail, les irréversibilités minimales, les meilleurs rendements et la moindre consommation de carburant. Les transferts exergétiques avec la chaleur, le travail et l’échappement et ainsi que les irréversibilités augmentent avec la charge du moteur. En outre, l’efficacité déduite de la première et la seconde loi de la thermodynamique augmente et la consommation de carburant diminue avec la charge du moteur, donc une charge du moteur élevée donne les meilleurs rendements et la moindre consommation de carburant.

  10. 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

  11. 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)

  12. 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

  13. 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

  14. 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

  15. 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

  16. Experience in the Design and Operation of High-Temperature Alkali Metal Systems

    International Nuclear Information System (INIS)

    Our experience with the alkali metals began in 1942, when it became necessary to manufacture potassium as an intermediate step in producing potassium superoxide and oxygen generator chemicals for use in rebreather safety equipment evaluation. Study of the alkali metals has continued to the present with measurement of the physical properties, high temperature heat transfer properties, followed by the development of liquid metal instruments and the design and reliable manufacture of components. The present operation (up to 1200°F) of two sodium systems to study the instream mechanical properties of materials for long periods of time reveals the satisfactory operation of many components and the trouble to be experienced when operation is attempted with impurities added to the sodium. Cold-trap purification of 1200°F sodium systems is sufficient for low-corrosion operation over a 2-yr period in an AISI, Type 316 stainless-steel system. The adding of new specimens always raises the oxygen level, requiring repurification of the sodium. Some carbon was removed by the cold trap when high carbon-sodium conditions prevailed, but removal is not complete enough for satisfactory operation; therefore great care should be taken in preventing the carbon contamination. Plugging indicators were a good tool for normal operation. Under high carbon conditions the initial break in the plugging indicator curve can be related to the carburization potential of the sodium. Inert gas lines in sodium systems need to be heated above the melting point of sodium to prevent plugging. However, under high oxygen-sodium conditions, solids deposit in the cover gas regions under ambient temperatures above the melting point of sodium. It is observed that the main difficulty incurred in running with high oxygen - sodium systems is the oxide plugging of small lines. In high carbon sodium systems, the failure of valve bellows by carburization causes operational difficulties. Stability of magnetic flow

  17. 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

  18. 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

  19. Synthesis, structural characterization, and catalytic properties of tungsten-exchanged H-ZSM5

    International Nuclear Information System (INIS)

    W-exchanged H-ZSM5 was prepared by sublimation of WCl6 at 673 K followed by hydrolysis of exchanged WClx species at 523 K. D2 exchange with residual OH groups showed that each W initially replaced about two zeolitic protons for W/Al ratios of 0.29 and 0.44, consistent with the formation of (WO2)2+ containing W6+ species bridging two cation exchange sites. As temperatures reached973 K during D2-OH exchange, these species reduced to (WO2)+ with the concurrent formation of one OD group. CH4 conversion turnover rates (per W) and C2-C1 2 selectivities are very similar to those observed on a Mo/H-ZSM5 sample with similar cation exchange level. As in the case of Mo/H-ZSM5, WOx/H-ZSM5 precursors are initially inactive in CH4 reactions, but they activate during induction with the concurrent evolution of CO, H2O, and an excess amount of H2. The reduction and carburization processes occurring during CH4 reactions and the structure of the exchanged WOx precursors was probed using in situ X-ray absorption spectroscopy (XAS). XAS studies confirmed the isolated initial nature of the exchanged WOx precursors after hydrolysis and dehydration and the formation of WCx clusters 0.6 nm in diameter during CH4 reactions at 973 K. The structural and catalytic resemblance between W- and Mo-exchanged H-ZSM5 is not unexpected, in view of chemical similarities between oxides or carbides of Mo and W. The synthesis of exchanged WOx precursors and their subsequent carburization during CH4 reactions, however, are more difficult than the corresponding processes for the MoOx counterparts. This may account for previous reports of lower CH4 reaction rates and aromatics selectivities on W/H-ZSM5 compared with those observed on Mo/H-ZSM5 and with those reported here for rigorously exchanged W/H-ZSM5

  20. Synthesis, structural characterization, and catalytic properties of tungsten-exchanged H-ZSM5

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Weiping; Meitzner, George D.; Marler, David O.; Iglesia, Enrique

    2001-01-18

    W-exchanged H-ZSM5 was prepared by sublimation of WCl6 at 673 K followed by hydrolysis of exchanged WClx species at 523 K. D2 exchange with residual OH groups showed that each W initially replaced about two zeolitic protons for W/Al ratios of 0.29 and 0.44, consistent with the formation of (WO2)2+ containing W6+ species bridging two cation exchange sites. As temperatures reached973 K during D2-OH exchange, these species reduced to (WO2)+ with the concurrent formation of one OD group. CH4 conversion turnover rates (per W) and C2-C1 2 selectivities are very similar to those observed on a Mo/H-ZSM5 sample with similar cation exchange level. As in the case of Mo/H-ZSM5, WOx/H-ZSM5 precursors are initially inactive in CH4 reactions, but they activate during induction with the concurrent evolution of CO, H2O, and an excess amount of H2. The reduction and carburization processes occurring during CH4 reactions and the structure of the exchanged WOx precursors was probed using in situ X-ray absorption spectroscopy (XAS). XAS studies confirmed the isolated initial nature of the exchanged WOx precursors after hydrolysis and dehydration and the formation of WCx clusters 0.6 nm in diameter during CH4 reactions at 973 K. The structural and catalytic resemblance between W- and Mo-exchanged H-ZSM5 is not unexpected, in view of chemical similarities between oxides or carbides of Mo and W. The synthesis of exchanged WOx precursors and their subsequent carburization during CH4 reactions, however, are more difficult than the corresponding processes for the MoOx counterparts. This may account for previous reports of lower CH4 reaction rates and aromatics selectivities on W/H-ZSM5 compared with those observed on Mo/H-ZSM5 and with those reported here for rigorously exchanged W/H-ZSM5.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. RDS-21 Face-Gear Surface Durability Tests

    Science.gov (United States)

    Lewicki, David G.; Heath, Gregory F.; Filler, Robert R.; Slaughter, Stephen C.; Fetty, Jason

    2007-01-01

    Experimental fatigue tests were performed to determine the surface durability life of a face gear in mesh with a tapered spur involute pinion. Twenty-four sets of gears were tested at three load levels: 7200, 8185, and 9075 lb-in face gear torque, and 2190 to 3280 rpm face gear speed. The gears were carburized and ground, shot-peened and vibro-honed, and made from VIM-VAR Pyrowear 53 steel per AMS 6308. The tests produced 17 gear tooth spalling failures and 7 suspensions. For all the failed sets, spalling occurred on at least one tooth of all the pinions. In some cases, the spalling initiated a crack in the pinion teeth which progressed to tooth fracture. Also, spalling occurred on some face gear teeth. The AGMA endurance allowable stress for a tapered spur involute pinion in mesh with a face gear was determined to be 275 ksi for the material tested. For the application of a tapered spur involute pinion in mesh with a face gear, proper face gear shim controlled the desired gear tooth contact pattern while proper pinion shim was an effective way of adjusting backlash without severely affecting the contact pattern.

  8. 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

  9. 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

  10. 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.

  11. Silicon carbide based one-dimensional nanostructure growth: towards electronics and biology perspectives

    International Nuclear Information System (INIS)

    One-dimensional (1D) nanostructures such as nanowires or nanotubes have attracted great interest in fundamental research as well as potential breakthrough applications. Among many materials, silicon carbide (SiC) has very interesting physical, chemical and electronic properties. This is why silicon carbide based 1D nanostructures, which combine excellent intrinsic properties with low dimensionality, have great potential. In this topical review, the growth of SiC 1D nanostructures is addressed as well as the potential applications of these peculiar nano-objects. This subject is first introduced by the interest in this material and by a summing up of the state of the art of SiC nanowire growth. In the second part, Si–SiC core–shell nanowire synthesis is described, followed by the growth of SiC nanotubes. In particular, these two kinds of nanostructures can be obtained via Si nanowire carburization. The third part is dedicated to the control of the synthesis from Si–SiC core–shell nanowires to SiC nanotubes using this original technique. Then, an alternative top-down approach to synthesize SiC 1D nanostructures is described. Finally, preliminary results towards integration for biology, energy and electronics are provided. (topical review)

  12. 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.

  13. 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

  14. Preparation and Fatigue Properties of Functionally Graded Cemented Carbides

    International Nuclear Information System (INIS)

    Cemented carbides with a functionally graded structure have significantly improved mechanical properties and lifetimes in cutting, drilling and molding. In this work, WC-6 wt.% Co cemented carbides with three-layer graded structure (surface layer rich in WC, mid layer rich in Co and the inner part of the average composition) were prepared by carburizing pre-sintered η-phase-containing cemented carbides. The three-point bending fatigue tests based on the total-life approach were conducted on both WC-6wt%Co functionally graded cemented carbides (FGCC) and conventional WC-6wt%Co cemented carbides. The functionally graded cemented carbide shows a slightly higher fatigue limit (∼100 MPa) than the conventional ones under the present testing conditions. However, the fatigue crack nucleation behavior of FGCC is different from that of the conventional ones. The crack nucleates preferentially along the Co-gradient and perpendicular to the tension surface in FGCC, while parallel to the tension surface in conventional cemented carbides

  15. An electrochemical engineering technique to improve the corrosion resistance of some structural materials in lead-alloy coolants

    International Nuclear Information System (INIS)

    The goal of this paper is to present some conclusions resulted from the literature studies referring to the materials potential to be used in Lead Fast Reactors (LFR), and the results obtained in the surface engineering field which can be used in our institute in order to obtain materials with appropriate properties for their use in LFR. In this context, the paper presents some preliminary results obtained in Surface Analysis Laboratory of INR Pitesti and research works in progress referring to: controlled modification of AISI 316L surface by electrochemical plasma treatment (carburization, nitrocarburizings); electrodeposition of some protective thin-films based on Ni and Al obtained from ionic liquids; development of some procedures related to the activities involved in the behaviour evaluation, in LFR specific conditions, for material samples subjected to treatments by surface engineering techniques using the LEad COrrosion TEsting LOop (LECOTELO) test bench. The superficial structures obtained have been characterized by metallographic microscopy, X-Ray Photoemission Spectroscopy (XPS), Electrochemical Impedance Spectroscopy (EIS); the electrochemical techniques were used to evaluate the corrosion behaviour. The preliminary results have shown that the used electrochemical surface engineering techniques are appropriate in order to improve the mechanical properties and corrosion behaviour of AISI 316L steel. (authors)

  16. Influence of hard particle addition and chemical interdiffusion on the properties of hot extruded tool steel compounds

    International Nuclear Information System (INIS)

    Low alloyed steel bars were co-extruded with pre-sintered tool steel powders with the addition of tungsten carbides (W2C/WC) as hard particles. During the hot extrusion process of these massive and powdery materials, an extrudate is formed consisting of a completely densified wear resistant coating layer and a bulk steel bar as the tough substrate core. This work combines experimental measurements (EPMA) and diffusion calculations (DICTRATM) to investigate the effect of hard particle addition and its dissolution, as well as the formation of M6C carbides on the properties of two different PM tool steel coatings hot extruded with a 1.2714 steel bar. A carburization effect resulting from the W2C hard particles is responsible for an increase of the 1.2344 steel matrix hardness. The mechanical properties of the interface region between coating matrix and substrate are influenced by chemical interdiffusion of carbon and other alloying elements occurring during heat treatment.

  17. Influence of hard particle addition and chemical interdiffusion on the properties of hot extruded tool steel compounds

    Energy Technology Data Exchange (ETDEWEB)

    Silva, P.A. [Max-Planck-Institut fuer Eisenforschung GmbH, MPIE, Max-Planck-Strasse 1, D-40237 Duesseldorf (Germany); Weber, S., E-mail: weber@wtech.rub.de [Institut fuer Werkstoffe, Ruhr-Universitaet Bochum, Universitaetsstrasse, D-44780 Bochum (Germany); Helmholtz-Zentrum Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany); Inden, G. [Max-Planck-Institut fuer Eisenforschung GmbH, MPIE, Max-Planck-Strasse 1, D-40237 Duesseldorf (Germany); Pyzalla, A.R. [Helmholtz-Zentrum Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany)

    2009-08-15

    Low alloyed steel bars were co-extruded with pre-sintered tool steel powders with the addition of tungsten carbides (W{sub 2}C/WC) as hard particles. During the hot extrusion process of these massive and powdery materials, an extrudate is formed consisting of a completely densified wear resistant coating layer and a bulk steel bar as the tough substrate core. This work combines experimental measurements (EPMA) and diffusion calculations (DICTRA{sup TM}) to investigate the effect of hard particle addition and its dissolution, as well as the formation of M{sub 6}C carbides on the properties of two different PM tool steel coatings hot extruded with a 1.2714 steel bar. A carburization effect resulting from the W{sub 2}C hard particles is responsible for an increase of the 1.2344 steel matrix hardness. The mechanical properties of the interface region between coating matrix and substrate are influenced by chemical interdiffusion of carbon and other alloying elements occurring during heat treatment.

  18. 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.

  19. How much life is left in your olefin unit

    International Nuclear Information System (INIS)

    Highly attractive economics in the olefin industry has justified increasing capacity via plant expansion and using aging olefin units beyond expected limitations. If these existing units are to operate well beyond their design life, what type of analysis and information is necessary to make this decision? What technologies or methods should be used for continued safe and controlled operation of these not so new units. This paper reports that the plant's mechanical integrity is the focal point of this analysis and decision-making method. Plant life expectancy study (PLES) looks at an operating plant's mechanical integrity from several vantage points. Four basic principles, such as plant history, process upsets and operating records, assessment of plant fires, and how to conduct records, assessment of plant fires, and how to conduct inspection and testing, provide the basis of how well a plant has been operated and maintained. Furthermore, the analysis includes a critical component inventory. These items address additional potential-failure causes, such as creep, fatigue, toughness, corrosion, erosion and carburization/oxidation

  20. Solid-state Diffusion Bonding of Candidate Fe-base and Ni-base Alloys for the Application of S-CO2 Cycle Heat Exchanger

    International Nuclear Information System (INIS)

    To achieve efficient heat transfer, compact type heat exchangers, such as printed circuit or plate fin type heat exchanger, are considered for intermediate heat exchangers (IHXs). Solid-state diffusion bonding (DB) is one of key issues for joining the thin metal sheets with flow passages that are either machined or photo-chemically etched. In this study, diffusion bonding was performed for the candidate Fe-base and Ni-base alloys. Tensile properties of the as-bonded were compared with the as-received and characteristics of the aged in high temperature S-CO2 environment were discussed. Studies on diffusion bonding of candidate alloys for the application of super-critical CO2 cycle were carried out. Strength ratios were close to 1 for Fe-base alloys (F91, SS 316H, and SS 347H), while those of Ni-base alloys (Alloy 600, Alloy 690) and Fe-Ni-Cr alloy (Incoloy 800HT) were somewhat decreased to about 0.8 due to the planar grain boundary and precipitates formed along the bond-line. After exposure in high temperature S-CO2 environment for 1000 h, mechanical properties were not changed substantially and the location of the failure was still in the gauge section away from the bond-line for most alloys. Thus, bond-line which plays a role as grain boundary is thought to have superior corrosion and carburization resistance comparable to that of parent matrix

  1. Impact of H2/CO ratios on phase and performance of Mn-modified Fe-based Fischer Tropsch synthesis catalyst

    International Nuclear Information System (INIS)

    Highlights: ► Decreasing H2/CO ratio facilitated the conversion of Fe3O4 to iron carbides on the surface layers. ► The formation of surface carbonaceous species was promoted in higher CO partial pressure. ► The formation of iron carbides on the surface of Fe3O4 provided the FTS active sites. ► Decreasing H2/CO ratio promoted the product shifting towards heavy hydrocarbons. - Abstract: Impacts of H2/CO ratios on both the bulky and surface compositions of an iron–manganese based catalyst were investigated by XRD, MES, N2-physisorption, XPS and LRS. Fischer–Tropsch (F–T) synthesis performances were studied in a slurry-phase continuously stirred tank reactor. The characterization results showed that the fresh catalyst was comprised of the hematite, which was converted firstly to Fe3O4, and then carburized to iron carbides in both the bulk and surface regions under different H2/CO ratios atmosphere. Pretreatment in lower H2/CO ratio facilitated the formation of iron carbides on the surface of magnetite and surface carbonaceous species. During the F–T synthesis reaction, the catalyst reduced in lower H2/CO ratio presented higher catalytic activity, which is assigned probably to the formation of more iron carbides (especially for χ-Fe5C2) on the surface of magnetite. The increase of CO partial pressure promoted the product distribution shifting towards heavy hydrocarbons

  2. 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.

  3. 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.

  4. 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.

  5. Corrosion resistance in liquid sodium and residual life after 40,000-hour exploitation of structural materials used for BOR-1 steam generator

    International Nuclear Information System (INIS)

    A 40,000-hour corrosion test was carried out of structural materials on the 30 MW BOR-1 steam generator in Dimitrovgrad in the USSR. Tested in liquid sodium were the following structural materials: HT8X6 (Cr2.25Mo1Nb), 3R12 (Cr18Ni11) and S31 (Cr20Ni35Ti). The materials preserved their good mechanical properties, including unchanged structures of welded joints. Changes in carbon concentration were studied by gradual sampling of successive layers 25 μm in thickness. Carburization of all used materials was only found to have taken place in surface layers to a depth of 100-150 μm. Tests of intergranular corrosion only showed sensitization in S31 tubes, this most pronounced at the sodium inlet to the superheater, i.e., at 480 degC. A 10,000-hour corrosion experiment was made in liquid sodium at a temperature of 550 degC under conditions of convection flow. The test showed that uniform corrosion due to sodium does not affect the planned service life of used structural materials. Structural changes of the materials are described resulting from exposure to corrosion in the BOR-1 steam generator. Possible uses of HT8X6 and 3R12 for fast reactor steam generators are discussed. (Pu)

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Avoiding ghost stress on reconstruction of stress- and composition-depth profiles from destructive X-ray diffraction depth profiling

    International Nuclear Information System (INIS)

    The present paper addresses the accuracy of the reconstruction of depth profiles from X-ray diffraction lattice-strain analysis, combined with successive sublayer removal. In order to test the accuracy of reconstruction irrespective of experimental inaccuracies, X-ray diffraction was simulated for model stress-depth profiles and/or composition-depth profiles, reflecting those obtainable with surface engineering of materials, i.e. shot peening, carburizing of austenite and low temperature nitriding of stainless steel. Two principally different methods for the reconstruction of the actual stress and composition profiles were compared:(I)assuming that the lattice parameter determined at a specific depth, for a specific value for ψ is a weighted average over the actual lattice spacing profile for this ψ-direction; (II)assuming that the stress/strain determined at a specific depth is a weighted average over the actual stress/strain depth profile. On the basis of the results it is concluded that method (I) virtually avoids the occurrence of ghost stresses (stress artefacts) upon data evaluation. Substantial ghost stresses may occur upon data analysis using method (II) for strongly compositionally graded materials.

  12. The microstructure and its impact on the high-temperature properties of the heat-resistant cast steel G-X 40 NiCr 35 25

    International Nuclear Information System (INIS)

    The report explains the influence of the elements Mo, W, Nb and Ti on the microstructure and thus on the high-temperature properties of the heat-resistant cast steel G-X 40 NiCr 35 25. The creep-rupture tests carried out at temperatures between 900deg C and 1100deg C for 2000 hours suggest that the interdendritic carbide skeleton as a non-creeping fiber reinforcement has a strong effect on the minimum creep rate. Especially the elements Nb and Ti have been found to reduce the minimum creep rate. Oxidation experiments have shown that the alloys with the lowest concentrations of the four elements varied in the alloying composition exhibit the least mass increases within the duration of the experiments. But enhanced concentrations of the dissolved elements Nb and Ti in the matrix have been found to reduce the solubility of the matrix with regard to carbon, and thus protect the material from carburization. (orig.) With 66 figs., 16 tabs

  13. 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)

  14. High-temperature resistant, thermally sprayed diffusion barrier coatings on CFC lightweight materials; Hochtemperaturbestaendige, thermisch gespritzte Diffusionsbarriereschichten auf CFC-Leichtbauchargiergestellen

    Energy Technology Data Exchange (ETDEWEB)

    Drehmann, Rico; Rupprecht, Christian; Wielage, Bernhard; Lampke, Thomas [Technische Univ. Chemnitz (Germany). Inst. fuer Werkstoffwissenschaft und Werkstofftechnik (IWW); Gilbert, Maria; Uhlig, Volker; Trimis, Dimosthenis [Technische Univ. Bergakademie Freiberg (Germany). Inst. fuer Waermetechnik und Thermodynamik (IWTT); Heuer, Volker [ALD Vacuum Technologies GmbH, Hanau (Germany)

    2013-03-15

    In heat treating processes as well as in high temperature brazing processes, charge carriers enable the positioning and transport of work pieces. Recently, charge carriers consisting of graphite or carbon fibre reinforced carbon (CFC) are used. The main disadvantage of charge carriers based on CFC is the undesirable carburization of the overlying components due to diffusion processes. Under this aspect, thermally sprayed coatings are applied on CFC and tested with respect to their suitability as a high-temperature diffusion barrier. The ceramic powders aluminium oxide, aluminium oxide/chromium oxide, aluminium oxide/titanium oxide and zirconium oxide/yttrium oxide are used as a coating material which is processed by means of the powder flame spraying as well as atmospheric plasma spraying. Molybdenum and silicon carbide are used as an adhesive layer. The coating materials aluminium oxide and aluminium oxide/chromium oxide on siliconized CFC presented excellent results. This supplies a large potential of application for thermally sprayed ceramic coatings on carbon-based lightweight materials.

  15. Carbide precipitation in nickel-base model alloys and its influence on the ductility and fracture bahaviour at room temperature

    International Nuclear Information System (INIS)

    The influence of carburization with internal carbide formation on the room temperature tensile properties was determined for nickel-base model alloys of different composition. The relationship between carbide volume fraction and the loss of ductility was systematically investigated. The embrittlement was found to be severe for volume fractions greater than about 0.03 if the carbides were formed principally on grain and twin boundaries. Cracks were propagated unhindered in the continuous, grain boundary carbide films formed in alloys containing Cr or Mo and caused intergranular fracture with rupture elongations of similar magnitude to that of the carbide phase itself. Grain boundary carbide precipitates which were not continuous led to less severe ductility loss. Intracrystalline carbide precipitates as found in the W or Nb containing alloys reduced the ductility only slightly compared with grain boundary carbides in alloys of similar carbon content because the linkage of pores was prevented by the presence of ductile matrix between the pores. The fracture of individual intragranular carbides as well as of connected carbide plates was interpreted using the parallel loaded, two phase structure model. The form of the relationship between the 0.2% proof stress and the carbide volume fraction was qualitatively described using a rule of mixtures. The rule of mixtures could not however satisfactorily describe the tensile strength and the true rupture elongation without consideration of crack growth by linkage of pores between fractured carbide particles. (orig.)

  16. 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)

  17. 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.

  18. 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

  19. 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

  20. 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

  1. Effects of sodium on the low-cycle fatigue behavior of austenitic stainless steel

    International Nuclear Information System (INIS)

    Low-cycle fatigue data have been obtained on annealed Type 316 stainless steel specimens during exposure to well-characterized sodium. Instrumented sodium loops, in which the oxygen, carbon, and hydrogen concentrations in sodium are controlled and measured, provide the desired test environment. Two closed-loop servohydraulic testing machines have been used for the low-cycle fatigue tests, which have been conducted with axial stroke-control loading at a strain rate of approximately 4 x 10-3 sec-1. The fatigue life of annealed Type 316 stainless steel tested in sodium is substantially greater than that tested in air. The fatigue life of sodium-exposed stainless steel (1512 hr at 6000C) that resulted in surface carburization of the material has also been investigated. The applied stress range for the sodium-exposed specimens decreased by 15-20 percent relative to the annealed specimens. For total strain ranges below approximately 1 percent, the fatigue life was enhanced by the 1500-hr sodium exposure

  2. Surface hardening on stainless steel 304 material with RF-plasma nitrocarburizing

    International Nuclear Information System (INIS)

    Surface hardening on stainless steel 304 material with RF-plasma nitro carburizing made in BATAN have been carried out. Some samples was nitrocarburized at temperature 400°C for (0,5-6) hour. The results show that the hardness of untreated sample of SUS 304 material was 260,58 Kgf/mm2, after the sample nitrocarburized at temperature 400°C for 6 hour, the hardness increased up to 347,62 Kgf/mm2. Furthermore, the maximum depth of carbon and nitrogen atoms that diffused in SUS 304 was 109,1 micrometer. Microstructure observation shows that the sample after nitrocarburized at temperature 400°C for 6 hour to be seen very clear that there are layer of N and C atoms in SUS304 material. Un-treated sample and sample that nitrocarburized at temperature 400°C (t = 6 jam) have same matrixes namely, γ-phase, δ-ferrite, and twinning transformation. (author)

  3. 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.

  4. Content of nitrogen in waste petroleum carbon for steel industries

    International Nuclear Information System (INIS)

    Steel industries use refined carbon as an alloy for steel production. This alloy is produced from waste carbon from the distillation of the petroleum. The refined carbon, called recarburizer, is obtained by calcination at high temperature. Under these thermal conditions the organic molecules decompose and a fraction of the N2, S and H2, volatile material and moisture are released; while the carbon tends to develop a crystalline structure similar to graphite's. The right combination of calcinations temperature and time in the furnace can optimize the quality of the resulting product. The content of S and N2 has to be minimized for the use of calcined carbon in the steel industry. Nitrogen content should be reduced by two orders of magnitude, from 1% - 2% down to hundreds of ppm by weight. This work describes the activities undertaken to obtain calcined coke from petroleum from crude oil carbon that satisfies the requirements of the Mercosur standard 02:00-169 (Pending) for use as a carborizer in steels industries. To satisfy the requirements of the Mercosur standards NM 236:00 IRAM-IAS-NM so that graphite is used as a carburizer a content of 300 ppm maximum weight of nitrogen has to be obtained. So the first stage in this development is to define a production process for supplying calcined coke in the range of nitrogen concentrations required by the Mercosur standards (CW)

  5. 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.

  6. The metallurgy of superalloys part 2

    International Nuclear Information System (INIS)

    This is part II of the report titled 'the metallurgy of superalloys'. It deals with the effect of heat treatment and operating conditions (thermal exposure and environment) on the mechanical properties of superalloys. The heat treatment is important in the development of superalloys through that it controls type, amount, size shape and distribution of the precipitate and the grain size of the matrix. The thermal exposure leads to reduction in the amount of the primary carbides and to precipitation of secondary carbides. Also it leads to the agglomeration and coarsening of gamma or the transformation of gamma phase to phase. The environment may lead to the internal oxidation, carburization, decarburization or sulphidization of the superalloys which may result in the degradation of their mechanical properties. This part gives also an example of applications of superalloys in the field of nuclear reactors especially high temperature-gas cooled reactors. Joined with this part a table which contains the major superalloys including its chemical analysis, creep rupture strength and some of its applications. 1 tab

  7. 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.

  8. 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.

  9. 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.

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

    International Nuclear Information System (INIS)

    Highlights: • Cu@C core–shell composite was prepared by reduction of [Cu(NH3)4]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(NH3)4]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

  11. 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.

  12. Application of Moessbauer Spectroscopy to the Carbon Oxides Hydrogenation Reactions

    International Nuclear Information System (INIS)

    Iron-based catalysts have favorable activity and selectivity properties for the CO and CO2 hydrogenation reactions. Several Fe phases (oxides and carbides) can be present in these catalysts. The interaction of Fe with the other components of the catalyst (support, promoters) can affect the ease of reduction and also its transformation during the reactions. In this work, the relationship between catalytic behavior in the CO and CO2 hydrogenation reactions and the Fe phase composition of fresh and reacted catalysts was studied. Two types of catalysts were tested: a laterite and the other one made of iron supported on alumina, both unpromoted and promoted with K and Mn. Only those Fe species which can be reduced-carburized, by means of a pretreatment or by an in situ transformation under the reaction, seem to be able to perform the CO or CO2 hydrogenation. The reoxidation of the Fe carbide to magnetite was not associated to deactivation. The selectivity seems to be more affected by Fe species difficult to reduce than by magnetite produced by reoxidation

  13. Reduction of friction and wear by ion-implanted carbonized photoresist

    International Nuclear Information System (INIS)

    The influence of ion-implanted carbonized photoresist layers (AZ 5210) on wear and friction is discussed in this paper. Photoresist, an organic resin, was used because of the simplicity of coating the sample, accurate control of the layer thickness, and high amount of carbon. The samples investigated were coated by conventional spin-on techniques with layer thicknesses varying from 0.2 μm to 2.2μm. Subsequent ion bombardment at energies of 200 keV and 1.4 MeV with doses ranging from 1x1016 cm-2 to 1x1017 cm-2 caused carburization, densification, and a mixing of the layer with the steel substrate. Transmission electron microscopy investigations, Raman spectroscopy, elastic recoil detection analysis, and microhardness measurements confirmed the production of a hard, amorphous, hydrogen-containing (about 17%) carbon layer after implantation. The layers were deposited onto different steels (AISI 52100, AISI 440 B unhardened, and AISI M2) and after implantation of boron, aluminium, phosphorus, arsenic and titanium, showed a strongly reduced friction coefficient (lower than 0.2) and drastically reduced wear behaviour. The duration of the wear reduction depended on both the thickness of the carbonized photoresist layer and on the implanted ion dose. Doses of 5x1016 cm-2 for hard steels and doses of 1x1017 cm-2 for soft steels are necessary to produce a sufficient layer adhesion by ion beam mixing. (orig.)

  14. Effect of titanium implantation on the friction and surface chemistry of a Co-Cr-W-C alloy

    International Nuclear Information System (INIS)

    The effects of the implantation of titanium ions, to a fluence of 5 X 1017 Ti ions cm-2 at 190 keV, on the tribological behavior of a centrifugally cast cobalt-based alloy (Stoody 3) were investigated by friction tests against a variety of alloy and carbon counterfaces. Dry sliding friction coefficients were compared with those made on similarly prepared, but non-implanted, and fatty-acid-coated samples. High friction coefficients (μsub(K) approx. 0.6) for the alloy-Stoody 3 couples coincided with the formation of debris, with the same composition as the softer of the mating alloys, in the wear scars. Much lower μsub(K) values were measured on titanium-implanted (μsub(K) approx. 0.25) and acid-coated (μsub(K) approx. 0.1) surfaces. Optical microscopy indicated a change in the surface texture of the implanted surfaces attributable to sputtering. Auger spectroscopy showed that vacuum carburization of both carbide and matrix phases of the Stoody alloy occurred during implantation. The friction and wear mechanisms involved are discussed. (Auth.)

  15. UKAEA mechanical test work in sodium

    International Nuclear Information System (INIS)

    The main aim of the UKAEA work is to perform mechanical tests in high quality sodium, and on the basis of relatively long term tests to establish whether factors need to be applied to the air data for the design and assessment of components which will have to operate in sodium for up to 30 years. Most of the tests will be performed in sodium containing 5-10 ppm O2 and ∼ 1 ppm C with a flow rate over the specimen surface of 3m/sec. Some work is also planned to establish the effect of changes in oxygen level up to 30 ppm on the properties and carburization studies will also be performed. Thin work has been in progress on a limited scale for 2-3 years but is now increasing in magnitude to meet the programme requirements. The materials under test include Type 316 steel and 9% Cr steel with most emphasis being placed on the austenitic steel. From the very limited fatigue and stress rupture tests so far performed on Type 316 steel there is no evidence to suggest that high purity sodium may be detrimental. Longer term tests are necessary however to confirm this finding which is based on results from relatively short term tests. Tests are also necessary in less pure sodium

  16. Cyclic voltammetry and X-ray photoelectron spectroscopy studies of electrochemical stability of clean and Pt-modified tungsten and molybdenum carbide (WC and Mo{sub 2}C) electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Weigert, Erich C. [Department of Materials Science and Engineering, Center for Catalytic Science and Technology (CCST), University of Delaware, Newark, DE 19716 (United States); Esposito, Daniel V.; Chen, Jingguang G. [Department of Chemical Engineering, Center for Catalytic Science and Technology (CCST), University of Delaware, 150 Academy St., Newark, DE 19716 (United States)

    2009-09-05

    The electrochemical stability of tungsten carbide (WC), Pt-modified WC, molybdenum carbide (Mo{sub 2}C), and Pt-modified Mo{sub 2}C has been examined using an in situ electrochemical half-cell in combination with X-ray photoelectron spectroscopy (XPS). The WC surface, created via the carburization of a tungsten foil, was electrochemically stable to {proportional_to}0.8 V with respect to the normal hydrogen electrode (NHE) when exposed to dilute sulfuric acid. At higher potentials, XPS confirmed the surface oxidation of WC to form W{sub x}O{sub y} species. The deposition of submonolayer coverage of Pt on the WC surface increased the region of stability of WC, extending the onset of catalyst oxidation to {proportional_to}1.0 V (NHE). These results suggest that both WC and Pt/WC have the potential to be used as anode electrocatalysts. In contrast, both Mo{sub 2}C and Pt-modified Mo{sub 2}C underwent oxidation at {proportional_to}0.4 V (NHE), indicating that molybdenum carbides are not stable enough for applications as anode electrocatalysts. (author)

  17. 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.

  18. Low loading platinum nanoparticles on reduced graphene oxide-supported tungsten carbide crystallites as a highly active electrocatalyst for methanol oxidation

    International Nuclear Information System (INIS)

    In this study, low loading platinum nanoparticles (Pt NPs) have been highly dispersed on reduced graphene oxide-supported WC nanocrystallites (Pt-WC/RGO) via program-controlled reduction-carburization technique and microwave-assisted method. The scanning electron microscopy and transmission electron microscopy results show that WC nanocrystallites are homogeneously decorated on RGO, and Pt NPs with a size of ca. 3 nm are dispersed on both RGO and WC. The prepared Pt-WC/RGO is used as an electrocatalyst for methanol oxidation reaction (MOR). Compared with the Pt/RGO, commercial carbon-supported Pt (Pt/C) and PtRu alloy (PtRu/C) electrocatalysts, the Pt-WC/RGO composites demonstrate higher electrochemical active surface area and excellent electrocatalytic activity toward the methanol oxidation, such as better tolerance toward CO, higher peak current density, lower onset potential and long-term stability, which could be attributed to the characterized RGO support, highly dispersed Pt NPs and WC nanocrystallites and the valid synergistic effect resulted from the increased interface between WC and Pt. The present work proves that Pt-WC/RGO composites could be a promising alternative catalyst for direct methanol fuel cells where WC plays the important role as a functional additive in preparing Pt-based catalysts because of its CO tolerance and lower price

  19. 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.

  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. 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.

  2. Design, irradiation and post-irradiation examination of the (U,Pu) C fuel pins of the test group FR 2-6d

    International Nuclear Information System (INIS)

    In the frame of the capsule group 6d three mixed carbide pins (pellet-density 92% T.D.) with a big radial gap (250 μm) were irradiated in the thermal neutron flux of FR 2. The cladding material consisted of the austenitic steel No. 1.4988. The exposure time in the reactor was up to 680 days, the burnup was 7.4 at %. The pins were instrumented on their surface with 6 thermocouples each. During irradiation in the NaK capsule no bigger irregularities in temperature readings were found. During dismantling in Karlsruhe Hot Cells the capsules it was found that all 3 pins showed cracks on their clads. The profilometry of the pins showed diameter increases from 4.5 to 6.0%. The carburization of the cladding proved the same tolerable magnitude as found for pins irradiated with moderate rod powers (Tsub(clad) 0C). Comparing ceramography with that of other pins of the same capsule group (KfK 2577) no bigger differences in structure were found. (orig.)

  3. 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.

  4. DURABILITY AND TRIBOLOGICAL PROPERTIES OF THERMALLY SPRAYED WC CERMET COATING IN LUBRICATED ROLLING WITH SLIDING CONTACT

    Directory of Open Access Journals (Sweden)

    Mohammad Ali

    2010-09-01

    Full Text Available Durability and tribological properties of thermally sprayed WC-Cr-Ni cermet coating were investigated experimentally in lubricated rolling with sliding contact conditions. By means of the high energy type flame spraying (Hi-HVOF method, the coating was formed onto the axially ground and circumferentially ground roller specimens made of a thermally refined carbon steel. In the experiments, the WC cermet coated steel roller was mated with the carburized hardened steel roller without coating in line contact condition. The coated roller was mated with the smooth non-coated roller under a contact pressure of 1.0 or 1.2 GPa, and it was mated with the rough non-coated roller under a contact pressure of 0.6 or 0.8 GPa. As a result, it was found that in general, the coating on the circumferentially ground substrate shows a lower durability compared with that on the axially ground substrate and this difference appears more distinctly for the higher contact pressure for both smooth mating surface and rough mating surface. It was also found that there are significant differences in the tribological properties of WC cermet coating depending on the contact pressure. In addition, depending on the smooth or rough mating surface, remarkable differences in the tribological properties were found.

  5. 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)

  6. 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.

  7. 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.

  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. 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. Analysis of the mechanical response of LMFBR fuel clads subjected to in-service property variations

    International Nuclear Information System (INIS)

    Evidence from available literature is presented to illustrate the degradation of 316 type stainless steel considered for use in Liquid Metal Fast Breeder Reactors where sodium is used as the coolant. Nonuniform changes in properties of the steel have been found to occur due to the thermal, thermochemical, and irradiation environment to which it is exposed. Variations in impurity concentrations (such as carbon in the steel) of several orders of magnitude compared to the original values have been observed under controlled sodium exposures. At temperatures relevant to the reactor system migration of impurities by diffusion, compound formations and carburization/decarburization behavior have been observed to occur. Mechanical property measurements such as tensile and yield strengths made under these conditions indicate that thermal and thermochemical influences can result in variations in the above properties quite different from the original material. Modified formulations of the elastic and elastic-plastic analysis of the degraded fuel-clad are presented in two dimensions. The elastic and plastic parameters relating to the properties of the degraded material are represented by spatially varying functions as opposed to being treated as constants which is the conventional case. The changes in the mathematical nature of the constitutive equations are demonstrated by sample illustrations and solutions involving continuous changes in the elastic moduli through-the-thickness of the clad. Recommendations for the establishment of improved Reactor Research Development Standards are made based on the studies

  11. A Physics and Tabulated Chemistry Based Compression Ignition Combustion Model: from Chemistry Limited to Mixing Limited Combustion Modes Un modèle de combustion à allumage par compression basé sur la physique et la chimie tabulée : des modes de combustion contrôlés par la chimie jusqu’aux modes contrôlés par le mélange

    Directory of Open Access Journals (Sweden)

    Bordet N.

    2011-11-01

    experimental measurements carried out on a 2 liter Renault Diesel engine and good agreements are found. Ce papier présente une nouvelle approche 0D phénoménologique pour prédire le déroulement de la combustion dans les moteurs Diesel à injection directe pour toutes les conditions d’utilisation usuelles. Le but de ce travail est de développer une approche physique en vue d’améliorer la prédiction de la pression cylindre et du dégagement d’énergie, avec un nombre minimum d’essais nécessaires à la calibration. Les contributions principales de cette étude sont la modélisation de la phase de pré-mélange de la combustion et une extension du modèle pour les stratégies d’injections multiples. Dans ce modèle, le taux de dégagement d’énergie dû à la combustion pour la phase pré-mélangée est relié à un taux de réaction moyen du carburant. Ce taux de réaction moyen de carburant est évalué à l’aide d’une approche basée sur un taux de réaction local de carburant tabulé et la détermination d’une fonction de densité de probabilité (PDF de la fraction de mélange (Z. Cette PDF permet de prendre en compte la distribution de richesse existante dans la zone pré-mélangée. L’allure de cette PDF présumée est une β-fonction standardisée. Les fluctuations de la fraction de mélange sont décrites avec une équation de transport pour la variance de Z. La définition standard de la fraction de mélange, établie dans le cas de flammes de diffusion, est ici adaptée à une combustion pré-mélangée de type Diesel pour décrire l’inhomogénéité de la richesse dans le volume de contrôle. La chimie détaillée est décrite au travers de la tabulation du taux de réaction relatif à la flamme principale et du délai d’auto-inflammation relatif à la flamme froide, ces tabulations sont fonction de la variable d’avancement c, du taux de gaz brûlé ainsi que des grandeurs thermodynamiques telles que la température et la pression. Le

  12. Production of Methanol-Higher Alcohol Mixtures from Natural Gas via Syngas Chemistry Production de mélanges méthanol-alcools supérieurs à partir du gaz, via (CO + H2

    Directory of Open Access Journals (Sweden)

    Courty P.

    2006-11-01

    Full Text Available Despite the prevailing position of ethers (MTBE, TAME as octane boosters, and the low oil prices at present, alcohol synthesis remains one of the near future means of natural gas upgrading via syngas chemistry. After a review of the available process development data in the field, this paper focuses on the IFP process studies, based on the CuCo and CuNi catalysts developed by Institut Français du Pétrole (IFR, France and Idemitsu Kosan (Japan. The adequacy between the product specifications, and the optimization of the performances is then discussed in a technico-economic context, together with a presentation of lab scale, pilot scale and demonstration scale test results. As a conclusion, a prospective overall view brings together todays economics and some improvement guidelines dealing with investments, operating cost and catalyst performances. Cette publication présente les travaux de R & D (Recherche et Développement menés par l'Institut Français du Pétrole (IFP, France et Idemitsu Kosan (Japon en synthèse d'alcools. Elle situe les résultats dans le contexte technique et économique actuel. L'accroissement constant des ressources prouvées en gaz et, chronologiquement, les deux crises pétrolières, la suppression du plomb dans les essences, ont conduit le monde industriel à intensifier les recherches concernant la synthèse d'alcools. Très récemment, les effets bénéfiques de l'addition d'alcools sur les émissions de polluants ont été mis en évidence. Toutefois, l'additivation de carburants par les alcools est en voie de disparition au profit des éthers, alors que, indépendamment, les procédés de production d'ammoniac, de méthanol, d'acide acétique, également fondés sur le gaz, se sont seuls développés. La synthèse d'alcools a fait l'objet de nombreux travaux, résumés dans les tableaux 1 et 2. L'étude des différents aspects réactionnels amène à prendre en compte l'exothermicité importante des r

  13. Material requirements for the Very High Temperature Reactor results and progress within the RAPHAEL-IP

    International Nuclear Information System (INIS)

    issues. The main emphasis on materials is for graphite development, materials for the heat exchangers, continuation of vessel qualification and work on design code requirements. The progress of the materials issues within the RAPHAEL-IP, which has reached its mid-term stage will be reviewed and the expected future orientations of the programme described. The main materials issues addressed in the paper are as follows: Reactor pressure vessel: - review and database actions covering existing and new vessel material options; - tests on Mod 9Cr 1Mo steel welded joints under irradiated and non-irradiated conditions to determine suitability for vessel application. High temperature materials: - review and database actions for the control rod and turbine; - review and database actions for the heat exchangers; - tests on selected materials (carbon/carbon (C/C) composites, high alloy steels) at temperature and under short and intermediate times in air, and simulated carburizing and de-carburizing environments. Graphite core: - review of experience plus data base actions for new graphites; - oxidation tests on graphites and C composites; - graphite selection and irradiation testing at 750 deg C and 950 deg C; - micro-structural modelling and development of guidelines. (authors)

  14. 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

  15. 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

  16. 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

  17. 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.

  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. Advanced Gear Alloys for Ultra High Strength Applications

    Science.gov (United States)

    Shen, Tony; Krantz, Timothy; Sebastian, Jason

    2011-01-01

    Single tooth bending fatigue (STBF) test data of UHS Ferrium C61 and C64 alloys are presented in comparison with historical test data of conventional gear steels (9310 and Pyrowear 53) with comparable statistical analysis methods. Pitting and scoring tests of C61 and C64 are works in progress. Boeing statistical analysis of STBF test data for the four gear steels (C61, C64, 9310 and Pyrowear 53) indicates that the UHS grades exhibit increases in fatigue strength in the low cycle fatigue (LCF) regime. In the high cycle fatigue (HCF) regime, the UHS steels exhibit better mean fatigue strength endurance limit behavior (particularly as compared to Pyrowear 53). However, due to considerable scatter in the UHS test data, the anticipated overall benefits of the UHS grades in bending fatigue have not been fully demonstrated. Based on all the test data and on Boeing s analysis, C61 has been selected by Boeing as the gear steel for the final ERDS demonstrator test gearboxes. In terms of potential follow-up work, detailed physics-based, micromechanical analysis and modeling of the fatigue data would allow for a better understanding of the causes of the experimental scatter, and of the transition from high-stress LCF (surface-dominated) to low-stress HCF (subsurface-dominated) fatigue failure. Additional STBF test data and failure analysis work, particularly in the HCF regime and around the endurance limit stress, could allow for better statistical confidence and could reduce the observed effects of experimental test scatter. Finally, the need for further optimization of the residual compressive stress profiles of the UHS steels (resulting from carburization and peening) is noted, particularly for the case of the higher hardness C64 material.

  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.