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Sample records for highly conductive slags

  1. Calibration-free electrical conductivity measurements for highly conductive slags

    SciTech Connect

    MACDONALD,CHRISTOPHER J.; GAO,HUANG; PAL,UDAY B.; VAN DEN AVYLE,JAMES A.; MELGAARD,DAVID K.

    2000-05-01

    This research involves the measurement of the electrical conductivity (K) for the ESR (electroslag remelting) slag (60 wt.% CaF{sub 2} - 20 wt.% CaO - 20 wt.% Al{sub 2}O{sub 3}) used in the decontamination of radioactive stainless steel. The electrical conductivity is measured with an improved high-accuracy-height-differential technique that requires no calibration. This method consists of making continuous AC impedance measurements over several successive depth increments of the coaxial cylindrical electrodes in the ESR slag. The electrical conductivity is then calculated from the slope of the plot of inverse impedance versus the depth of the electrodes in the slag. The improvements on the existing technique include an increased electrochemical cell geometry and the capability of measuring high precision depth increments and the associated impedances. These improvements allow this technique to be used for measuring the electrical conductivity of highly conductive slags such as the ESR slag. The volatilization rate and the volatile species of the ESR slag measured through thermogravimetric (TG) and mass spectroscopy analysis, respectively, reveal that the ESR slag composition essentially remains the same throughout the electrical conductivity experiments.

  2. PENETRATION OF COAL SLAGS INTO HIGH-CHROMIA REFRACTORIES

    SciTech Connect

    Longanbach, Sara C.; Matyas, Josef; Sundaram, S. K.

    2009-10-05

    Slagging coal gasifiers are used for the production of electricity and synthetic gases, as well as chemicals. High temperatures in the reaction chamber, typically between 1250ºC and 1600ºC, high pressure, generally greater than 400 psi, and corrosive slag place severe demands on the refractory materials. Slag produced during the combustion of coal flows over the refractory surface and penetrates the porous material. Slag penetration is typically followed by spalling of a brick that significantly decreases the service life of gasifier refractories. Laboratory tests were conducted to determine the penetration depth of slags into high-chromia refractories as a function of time and temperature for various refractory-slag combinations.

  3. Initial stages of coal slag interaction with high chromia sesquioxide refractories

    SciTech Connect

    Rawers, James C.; Iverson, Larissa; Collins, Wesley K.

    2002-02-01

    Slagging coal gasifiers operate at temperatures as high as 1650◦C in a reducing environment, requiring combustion chambers to be lined with refractories. The liner materials of choice are semi-porous high chromia refractories. Recently, a new series of high-chromia aluminia sesquioxide refractories have been developed. Both long term and short term tests are being conducted to evaluate the performance of these materials. In this study, the initial stage of slag-refractory interactions was analyzed. Samples of gasifier slag were compacted and placed upon the surface of these new chromia refractories and the temperature was raised consistent with start-up operating conditions of commercial gasifiers. The slag was completely molten by the time the furnace achieved a temperature consistent with gasifier operation conditions: 1350◦C. Measurement of the slag contact angle, slag spread along the slag-refractory interface, and the loss of slag due to slag infusion into the refractory were monitored by camera. Analysis suggests a single phenomenon with an activation energy of approximately 54 kcal may be the controlling factor. Cross-section analysis of the sample and analysis of slag chemistry indicate that slag infusion preceded the slag-refractory interface front movement and that the iron component of the slag was becoming concentrated at the slag-refractory interface leading to the formation of a chromium-iron spinel phase. Results of these short term tests are critical in characterizing and understanding the results long term slag-refractory interactions.

  4. Initial stages of coal slag interaction with high chromia sesquioxide refractories

    SciTech Connect

    Rawers, J.C.; Iverson, L.; Collins, W.K.

    2002-02-01

    Slagging coal gasifiers operate at temperatures as high as 1650°C in a reducing environment, requiring combustion chambers to be lined with refractories. The liner materials of choice are semi-porous high chromia refractories. Recently, a new series of high-chromia aluminia sesquioxide refractories have been developed. Both long term and short term tests are being conducted to evaluate the performance of these materials. In this study, the initial stage of slag-refractory interactions was analyzed. Samples of gasifier slag were compacted and placed upon the surface of these new chromia refractories and the temperature was raised consistent with start-up operating conditions of commercial gasifiers. The slag was completely molten by the time the furnace achieved a temperature consistent with gasifier operation conditions: 1350°C. Measurement of the slag contact angle, slag spread along the slag-refractory interface, and the loss of slag due to slag infusion into the refractory were monitored by camera. Analysis suggests a single phenomenon with an activation energy of approximately 54 kcal may be the controlling factor. Cross-section analysis of the sample and analysis of slag chemistry indicate that slag infusion preceded the slag-refractory interface front movement and that the iron component of the slag was becoming concentrated at the slag-refractory interface leading to the formation of a chromium-iron spinel phase. Results of these short term tests are critical in characterizing and understanding the results long term slag-refractory interactions.

  5. Estimation Model for Electrical Conductivity of CaF2-CaO-Al2O3 Slags

    NASA Astrophysics Data System (ADS)

    Shi, Guan-yong; Zhang, Ting-an; Dou, Zhi-he; Niu, Li-ping

    2016-04-01

    Electrical conductivity is one of the most important properties of molten slags. It has an important influence on process parameter selection of the electroslag remelting process. In the present work, a new model for estimating electrical conductivity of high-temperature slags has been proposed via calculating the conductivity by electrical conductivity of pure substances and interaction parameters between the different components in the slag has been proposed. In this model, the Arrhenius law is used to describe the relationship between electrical conductivity and temperature of slags. This model has been successfully applied to the CaF2-Al2O3, CaF2-CaO, and CaO-Al2O3, as well as CaF2-CaO-Al2O3 systems, and the calculated results are in good agreement with the measured values.

  6. Slags

    NASA Astrophysics Data System (ADS)

    Somerville, Michael; Sun, Shouyi; Jahanshahi, Sharif

    2014-12-01

    New measurements on solubility of copper and redox equilibria in magnesia-saturated calcium ferrite-based slags are presented. These data were obtained from equilibrium experiments at 1573 K (1300 °C) and over a range of oxygen partial pressures of 10-11 to 10-5 atm, through equilibrating the slag with metallic copper in magnesia crucibles under a flowing Ar-CO-CO2 gas mixture. At low oxygen partial pressures, copper was found to dissolve into slag as a univalent species (CuO0.5) with a linear dependence on the oxygen partial pressure (in logarithm), with a slope of 0.23. At higher oxygen partial pressures (>10-7 atm), the data suggest a divalent copper species becomes significant (CuO) and causes the dependence on oxygen partial pressure to increase. The determination of the Fe3+/Fe2+ ratio in the slag was effected by the cuprous (Cu+) content, which acts to increase the apparent ferrous (Fe2+) content during acid digestion. A correction procedure was applied to the Fe3+/Fe2+ ratio based on the calculated Cu+ content of the slag. The procedure assumes that the activity coefficients of CuO0.5 and CuO (and γ CuO) in these slags are independent of oxygen partial pressure. The calculated activity coefficients of CuO0.5 and CuO were 3.43 and 0.29, respectively. The corrected Fe3+/Fe2+ ratio had a linear dependence of 0.17 on the oxygen partial pressure over the entire oxygen partial pressure range. This agrees with similar data from the literature.

  7. The hydraulic potential of high iron bearing steel slags

    NASA Astrophysics Data System (ADS)

    Ionescu, Denisa Virginia

    The incorporation of additives to the clinker or to the raw materials stream is a common practice in cement manufacture. However, steel slag, unlike its ironmaking parent the blast furnace slag, it is not a conventional admixture for cement. Currently most steel slags are slow cooled rendering stable crystalline compounds with minor hydraulic value. Nevertheless, if steel slags would be quenched and granulated, the resulting glassy product might display increased hydration and strength development potential. The use of steel slag in cement could contribute to important savings for both cement and steelmaking industries and provide a solution for the environmental problems linked to CO2 emissions and costs of transport and disposal. The purpose of this research is to explore the thermodynamics and kinetics of steel slag hydration in an effort to produce a cement additive, or a more promising material of near Portland cement composition. An important criteria used in the assessment of slags as potential cements is the presence of a glassy phase. At present, it is not very clear why glass enhances the hydration process. However, it is known that the free energy of formation for glasses is less than for crystals so that glasses are easier to hydrate compared to crystalline materials. In the particular case of steel slag, the glassy phase would have to contain high amounts of iron. Steel slags are known to display iron levels approximately 10 times higher than Portland cement and commonly used blast furnace slags. However, the effect of high Fe2O3 levels on the setting and strengthening of cement paste is not clearly understood due to the fact that most cement additives do not present this characteristic. The present work looks at the progress made in recycling steel slag as cement additive, the complexity of the hydration process in slags, the possibilities of improving the hydration potential of slags at laboratory and industrial level, and the problems that still

  8. Effect of High Cooling Rates on the Mineralogy and Hydraulic Properties of Stainless Steel Slags

    NASA Astrophysics Data System (ADS)

    Kriskova, Lubica; Pontikes, Yiannis; Pandelaers, Lieven; Cizer, Özlem; Jones, Peter Tom; Van Balen, Koen; Blanpain, Bart

    2013-10-01

    This article investigates the effect of chemical composition and cooling rate during solidification on the mineralogy and hydraulic properties of synthetic stainless steel slags. Three synthetic slags, covering the range of typical chemical composition in industrial practice, were subjected to high cooling rates, by melt spinning granulation or quenching in water, and to low cooling rates, by cooling inside the furnace. Both methods of rapid cooling led to volumetrically stable slags unlike the slow cooling which resulted in a powder-like material. Stabilized slags consisted predominantly of lamellar β-dicalcium silicate ( β-C2S) and Mg, Ca-silicates (merwinite and bredigite); the latter form the matrix at low basicity and are segregated along the C2S grain boundaries at high basicities. Slowly cooled slags consist of the γ-C2S polymorph instead of the β-C2S and of less Mg, Ca-silicates. Isothermal conduction calorimetry and thermogravimetric analysis indicate the occurrence of hydration reactions in the stabilized slags after mixing with water, while calcium silicate hydrates (C-S-H) of typical acicular morphology are identified by SEM. The present results demonstrate that the application of high cooling rates can result in a stable, environmental-friendly, hydraulic binder from stainless steel slags, rich in β-C2S, without the necessity of introducing any additions to arrest the β polymorph.

  9. Comprehensive model for a slag bath in electroslag remelting process with a current-conductive mould

    NASA Astrophysics Data System (ADS)

    Liu, Fu-bin; Zang, Xi-min; Jiang, Zhou-hua; Geng, Xin; Yao, Man

    2012-04-01

    A mathematical model was developed to describe the interaction of multiple physical fields in a slag bath during electroslag remelting (ESR) process with a current-conductive mould. The distributions of current density, magnetic induction intensity, electromagnetic force, Joule heating, fluid flow and temperature were simulated. The model was verified by temperature measurements during remelting 12CrMoVG steel with a slag of 50wt%-70wt% CaF2, 20wt%-30wt% CaO, 10wt%-20wt% Al2O3, and ≤10wt% SiO2 in a 600 mm diameter current-conductive mould. There is a good agreement between the calculated temperature results and the measured data in the slag bath. The calculated results show that the maximum values of current density, electromagnetic force and Joule heating are in the region between the corner electrodes and the conductivity element. The characteristics of current density distribution, magnetic induction intensity, electromagnetic force, Joule heating, velocity patterns and temperature profiles in the slag bath during ESR process with current-conductive mould were analyzed.

  10. Slag Penetration into Refractory Lining of Slagging Coal Gasifier

    SciTech Connect

    Matyas, Josef; Sundaram, S. K.; Rodriguez, Carmen P.; Edmondson, Autumn B.; Arrigoni, Benjamin M.

    2008-10-25

    The impurities in coal are converted into molten slag typically containing SiO2, FeO, CaO, and Al2O3 when coal feedstock is burned in slagging gasifiers. The slag flows down the gasifier sidewalls, dissolves, and penetrates and reacts with the refractory lining that protects the stainless steel shell of the gasifier from elevated temperatures (1300–1600°C). Refractories composed primarily of Cr2O3 have been found most resistant to slag corrosion, but they continue to fail performance requirements because of low resistance to spalling. Post-mortem analysis of high-chromia refractory bricks collected from commercial gasifiers suggests that the spalling is affected by the depth of slag penetration that is in turn affected by the wettability and interconnected porosity of the refractory as well as the slag viscosity. Laboratory tests were conducted to measure the viscosity of slags (Wyoming Powder River Basin [PRB], Pocahontas #3, and Pittsburgh #8), their contact angle on refractories (chromia-alumina [Aurex 75SR] and high-chromia [Serv 95 and Aurex 95P]), and the apparent porosity of selected refractories. In addition, the depth of slag penetration as a function of time and temperature was determined for various refractory-slag combinations. The results of laboratory tests were used to develop a refractory material that has high resistance to penetration by molten slag and thus has a potential to have a substantially longer service life than the materials currently being used.

  11. Reaction between Steel-Making Slag and Carbonaceous Materials While Mixing with High Density Polyethylene

    NASA Astrophysics Data System (ADS)

    Hong, Lan; Sahajwalla, Veena

    2016-01-01

    Since the beginning of the extensive applications in numerous high temperature processes such as iron- and steel-making, coke-making etc. partly in the place of coke, the investigation into the reaction mechanism of waste plastics has become increasingly necessary. In this paper a fundamental study on the behavior of a typical component of waste plastics, high density polyethylene (HDPE), in a mixture with coke at a 1:1 ratio in mass base was conducted during the reaction with iron oxide in steel-making slag at 1823 K and was compared with coke and graphite. The reaction mechanism of carbonaceous materials was analyzed based on the contents of CO and CO2 in the off-gas monitored by an infrared (IR) gas analyzer. It is clear from the results that the reaction of HDPE and coke mixture with steel-making slag approached equilibrium of the Boudouard reaction more quickly and closely than coke or graphite.

  12. Diffusion zone between high-chromium cast iron and high-manganese steel during electric-slag facing

    SciTech Connect

    Ponomarenko, V.P.; Shvartser, A.Y.; Stroganova, G.V.

    1986-05-01

    The authors investigate extending the service lives of components by the method of electric-slag facing of working surfaces. Steel 45 was used in the annealed state. Electric-slag remelting was the method used to determine the bending strength. Metallographic examinations were conducted under an MIM-8m microscope, while x-ray analysis of the built-up and base metals were performed on a DRON-2 diffractometer. BAsic alloying elements, chromium and manganese were studied on a ''Cameca MS-46'' microanalyzer. During the electri-slag facing of a high-chromium cast iron containing 8% of Mn on high-manganese steel 11OG13L diffusion equalization of the manganese content occurs in the fusion zone. Diffusion displacement of carbon, chromium, and manganese from high-chromium cast iron into the high-manganese steel during electric-slag facing gies rise to a smooth change in the structure of the metal in the fusion zone, and to increased strength of the joint between the unlike materials investigated.

  13. Glassy slags as novel waste forms for remediating mixed wastes with high metal contents

    SciTech Connect

    Feng, X.; Wronkiewicz, D.J.; Bates, J.K.; Brown, N.R.; Buck, E.C.; Gong, M.; Ebert, W.L.

    1994-03-01

    Argonne National Laboratory (ANL) is developing a glassy slag final waste form for the remediation of low-level radioactive and mixed wastes with high metal contents. This waste form is composed of various crystalline and metal oxide phases embedded in a silicate glass phase. This work indicates that glassy slag shows promise as final waste form because (1) it has similar or better chemical durability than high-level nuclear waste (HLW) glasses, (2) it can incorporate large amounts of metal wastes, (3) it can incorporate waste streams having low contents of flux components (boron and alkalis), (4) it has less stringent processing requirements (e.g., viscosity and electric conductivity) than glass waste forms, (5) its production can require little or no purchased additives, which can result in greater reduction in waste volume and overall treatment costs. By using glassy slag waste forms, minimum additive waste stabilization approach can be applied to a much wider range of waste streams than those amenable only to glass waste forms.

  14. Microscopic Study of Carbon Surfaces Interacting with High Carbon Ferromanganese Slag

    NASA Astrophysics Data System (ADS)

    Safarian, Jafar; Kolbeinsen, Leiv

    2015-02-01

    The interaction of carbon materials with molten slags occurs in many pyro-metallurgical processes. In the production of high carbon ferromanganese in submerged arc furnace, the carbothermic reduction of MnO-containing silicate slags yields the metal product. In order to study the interaction of carbon with MnO-containing slags, sessile drop wettability technique is employed in this study to reduce MnO from a molten slag drop by carbon substrates. The interfacial area on the carbon substrate before and after reaction with slag is studied by scanning electron microscope. It is indicated that no Mn metal particles are found at the interface through the reduction of the MnO slag. Moreover, the reduction of MnO occurs through the contribution of Boudouard reaction and it causes carbon consumption in particular active sites at the interface, which generate carbon degradation and open pore growth at the interface. It is shown that the slag is fragmented to many micro-droplets at the reaction interface, potentially due to the effect on the interfacial energies of a provisional liquid Mn thin film. The rapid reduction of these slag micro-droplets affects the carbon surface with making deep micro-pores. A mechanism for the formation of slag micro-droplets is proposed, which is based on the formation of provisional micro thin films of liquid Mn at the interface.

  15. Microscopic Study of Carbon Surfaces Interacting with High Carbon Ferromanganese Slag

    NASA Astrophysics Data System (ADS)

    Safarian, Jafar; Kolbeinsen, Leiv

    2014-09-01

    The interaction of carbon materials with molten slags occurs in many pyro-metallurgical processes. In the production of high carbon ferromanganese in submerged arc furnace, the carbothermic reduction of MnO-containing silicate slags yields the metal product. In order to study the interaction of carbon with MnO-containing slags, sessile drop wettability technique is employed in this study to reduce MnO from a molten slag drop by carbon substrates. The interfacial area on the carbon substrate before and after reaction with slag is studied by scanning electron microscope. It is indicated that no Mn metal particles are found at the interface through the reduction of the MnO slag. Moreover, the reduction of MnO occurs through the contribution of Boudouard reaction and it causes carbon consumption in particular active sites at the interface, which generate carbon degradation and open pore growth at the interface. It is shown that the slag is fragmented to many micro-droplets at the reaction interface, potentially due to the effect on the interfacial energies of a provisional liquid Mn thin film. The rapid reduction of these slag micro-droplets affects the carbon surface with making deep micro-pores. A mechanism for the formation of slag micro-droplets is proposed, which is based on the formation of provisional micro thin films of liquid Mn at the interface.

  16. Slag-Refractory Interaction in Slagging Coal Gasifiers

    SciTech Connect

    Matyas, Josef; Sundaram, S. K.; Hicks, Brent J.; Edmondson, Autumn B.; Arrigoni, Benjamin M.

    2008-03-03

    The combustion chamber of slagging coal gasifiers is lined with refractories to protect the stainless steel shell of the gasifier from elevated temperatures and corrosive attack of the coal slag. Refractories composed primarily of Cr2O3 have been found most resistant to slag corrosion, but they continue to fail performance requirements. Post-mortem analysis of high-chromia refractory bricks collected from commercial gasifiers suggests that slag penetration and subsequent spalling of refractory are the cause of significantly shorter service life of gasifier refractories. Laboratory tests were conducted to determine the penetration depth of three slags representative of a wide variety of coals in the United States into chromia-alumina and two high-chromia refractories. Variables tested were refractory-slag combinations and two partial pressures of O2. Slag penetration depths were measured from spliced images of each refractory. Samples heated to 1470°C for 2 hrs had maximum penetration depths ranging from 1.99±0.15 mm to at least 21.6 mm. Aurex 95P, a high-chromia refractory containing 3.3% phosphorous pentoxide (P2O5), showed the least slag penetration of all refractories tested. P2O5 likely reacts with the slags to increase their viscosity and restrict molten slag penetration. Experimental data on the slag-refractory interaction will be incorporated into mathematical model that will be used to 1) identify critical conditions at which refractory corrosion sharply increases, and 2) predict the service life of a gasifier refractory.

  17. The influence of compound admixtures on the properties of high-content slag cement

    SciTech Connect

    Dongxu, L.; Xuequan, W.; Jinlin, S.; Yujiang, W.

    2000-01-01

    Based on the activation theory of alkali and sulfate, the influence of compound admixtures on the properties of high-content slag cement was studied by testing the strength, pore structure, hydrates, and microstructure, Test results show that compound admixtures can obviously improve the properties of high-content slag cement. The emphasis of the present research is two-fold: substituting gypsum with anhydrite and calcining gypsum. These both can improve early and later performance.

  18. A study on anticorrosion effect in high-performance concrete by the pozzolanic reaction of slag

    SciTech Connect

    Hou, W.-M.; Chang, P.-K.; Hwang, C.-L

    2004-04-01

    The study examines the pozzolanic reaction brought by the addition of slag to the cement paste using the synchrotron radiation accelerator (SRA), the mercury intrusion porosimetry (MIP), and scanning electron microstructural analysis. The anticorrosion effect in high-performance concrete with and without slag added is also assessed by its electrical resistivity and permeability. Results show that pozzolanic reaction due to the addition of slag can decrease the amount of calcium hydroxide, reduce the volume of capillary pores (Pc), and lower its permeability, thus making the concrete more compact and durable. As evidenced by the enhanced electrical resistivity and reduced permeability, the addition of slag to high-performance concrete can indeed strength the anticorrosion effect.

  19. Co-treatment of converter slag and pyrrhotite tailings via high pressure oxidative leaching.

    PubMed

    Perederiy, Ilya; Papangelakis, Vladimiros G; Buarzaiga, Mohamed; Mihaylov, Indje

    2011-10-30

    High pressure oxidative acid leaching (HPOXAL) was successfully applied to slow-cooled converter slags from Vale's operations in Sudbury (Ontario, Canada). Extractions of Ni, Co and Cu exceeded 90% within 15-20 min and levelled at 95-97% after 45 min at 250°C, 90 psi O(2) overpressure and 70 g/L initial H(2)SO(4). Pyrrhotite tailings with ∼ 0.6% Ni content were also tested as a source of sulphuric acid in high pressure oxidation. Co-leaching of pyrrhotite tailings with converter slags at the same temperature, oxygen partial pressure and equivalent stoichiometric H(2)SO(4) was found to have kinetics similar to that of leaching with sulphuric acid. Lowering the addition of pyrrhotite tailings (and hence, the acidity) was found to have a detrimental effect on the kinetics of leaching and final extractions (especially at 250°C), and cause precipitation of metal sulphates. Continuous on-line acidity measurements were facilitated in experiments with an electrodeless conductivity sensor. It was shown that acid plays a major role in the conversion of fayalite to hematite and silica, and the dissolution of the base metals, while oxygen overpressure (or dispersion efficiency) determines the rate of acid generation and re-generation. PMID:21893384

  20. Characterizing coal-gasifier slag-refractory interactions

    SciTech Connect

    Rawers, J.; Kwong, J.; Bennett, J.

    1999-07-01

    To characterize refractory degradation and loss on commercial coal-gasifier combined cycle powder generating facilities, cup-type tests were conducted on high chromium-alumina, sinter-bonded refractories under laboratory conditions designed to simulate commercial operations of temperature, atmosphere, and slag interactions. These tests provided qualitative results from which the slag-refractory interactions can be characterized. These high chromium refractories were generally inert with respect to the coal slag components. However, this study did show (1) iron (oxide) in the slag reacted with chrome sesquioxide to produce a Cr-Fe spinel at the slag-refractory interface, and (2) chrome was soluble in the molten slag. Comparison of cup-type test results with data from operating commercial plants suggests that the principal loss of refractory material in a coal-gasifier combustion chamber is chrome dissolution into the slag. Tests are currently underway to determine if minor modifications to the combustion process might increase refractory life.

  1. Construction material properties of slag from the high temperature arc gasification of municipal solid waste.

    PubMed

    Roessler, Justin G; Olivera, Fernando D; Wasman, Scott J; Townsend, Timothy G; McVay, Michael C; Ferraro, Christopher C; Blaisi, Nawaf I

    2016-06-01

    Slag from the high temperature arc gasification (HTAG) of municipal solid waste (MSW) was tested to evaluate its material properties with respect to use as a construction aggregate. These data were compared to previously compiled values for waste to energy bottom ash, the most commonly produced and beneficially used thermal treatment residue. The slag was tested using gradations representative of a base course and a course aggregate. Los Angeles (LA) abrasion testing demonstrated that the HTAG slag had a high resistance to fracture with a measured LA loss of 24%. Soundness testing indicated a low potential for reactivity and good weathering resistance with a mean soundness loss of 3.14%. The modified Proctor compaction testing found the slag to possess a maximum dry density (24.04kN/m(3)) greater than conventionally used aggregates and WTE BA. The LBR tests demonstrated a substantial bearing capacity (>200). Mineralogical analysis of the HTAG suggested the potential for self cementing character which supports the elevated LBR results. Preliminary material characterization of the HTAG slag establishes potential for beneficial use; larger and longer term studies focusing on the material's possibility for swelling and performance at the field scale level are needed. PMID:27020344

  2. Modelling of High-Chromia Refractory Spalling in Slagging Coal Gasifiers

    SciTech Connect

    Williford, Rick E.; Johnson, Kenneth I.; Sundaram, S. K.

    2008-10-31

    The economic viability of converting coal into clean burning liquid fuels in slagging coal gasifiers is compromised by the limited service lifetime of hot-face refractories. One of the most severe refractory degradation mechanisms is spalling, which can occur by either volume expansion phenomena (compressive stresses) or by volume shrinkage phenomena (tensile stresses). A volume shrinkage model is benchmarked to high-chromia refractory material properties and performance under gasifier operating conditions. The model is found to be appropriate for first order estimates of gasifier refractory lifetime when the apparent diffusivity of volatized Cr in the refractory includes the effects of slag-filled pores and cracks.

  3. High temperature millimeter wave radiometric and interferometric measurements of slag-refractory interaction for application to coal gasifiers

    SciTech Connect

    McCloy, John S.; Crum, Jarrod V.; Sundaram, S. K.; Slaugh, Ryan W.; Woskov, Paul P.

    2011-09-17

    Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments (high temperature, pressure, and corrosive environments) such as in slagging coal gasifiers, where sensors have been identified as a key enabling technology need for process optimization. We present a state-of-the-art dual-channel MMW heterodyne radiometer with active interferometric capability that allows simultaneous radiometric measurements of sample temperature, emissivity, and flow dynamics to over 1873 K. Interferometric capability is supplied via a probe signal originating from the 137 GHz radiometer local oscillator (LO). The interferometric 'video' channels allow measurement of additional parameters simultaneously, such as volume expansion, thickness change, and slag viscosity along with temperature or emissivity. This capability has been used to demonstrate measurement of temperature and simulated coal slag infiltration into a chromia refractory brick sample as well as slag flow down a vertically placed refractory brick. Observed phenomena include slag melting and slumping, slag reboil and foam with oxygen evolution, and eventual failure of the alumina crucible through corrosion by the molten slag. These results show the promise of the MMW system for extracting quantitative and qualitative process parameters from operating slagging coal gasifiers, providing valuable information for process efficiency, control, and increased productivity.

  4. Electrical Conductivity and Electronic/Ionic Properties of TiO x -CaO-SiO2 Slags at Various Oxygen Potentials and Temperatures

    NASA Astrophysics Data System (ADS)

    Liu, Jun-Hao; Zhang, Guo-Hua; Wu, Yue-Dong; Chou, Kuo-Chih

    2016-02-01

    The electrical conductivity of molten slags is an extremely important factor in the design of electric smelting furnaces. As a fundamental study on properties of the TiO x -bearing slags, the total electrical conductivity and electronic/ionic properties of TiO x -SiO2-CaO slags were measured at different oxygen potentials and temperatures using four-electrode method. The experiment results show that for a specific composition, the temperature dependences of ionic, electronic, and total conductivity obey the Arrhenius law. The stepped potential chronoamperometry method was employed for measuring the electronic transference number, which exhibits a strong dependence on oxygen potential, but is unaffected by temperature. The total electrical, electronic, and ionic conductivities present similar increasing trends with increasing the ratio of CO/CO2, which is resulted from increasing of Ti3+.

  5. Structure, Growth Process, and Growth Mechanism of Perovskite in High-Titanium-Bearing Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Liu, Lu; Hu, Meilong; Xu, Yuzhou; Bai, Chenguang; Gan, Yunhua

    2015-08-01

    The isothermal crystallization of perovskite in TiO2-CaO-SiO2-Al2O3-MgO high-titanium-bearing blast furnace slag was observed in situ at 1698 K (1425 °C) using a confocal scanning laser microscope. The dendrite structure of perovskite (CaTiO3) thus obtained showed vividly the primary dendrite trunks and secondary dendrite arms. Furthermore, the dendritic growth of perovskite in liquid slag was clearly observed on line. The results showed that the dendrite arrays in which the primary dendrite trunks observed on slag surface were parallel with each other grew toward the same direction. The secondary dendrite arms grew in the perpendicular direction with the primary trucks and stopped growing when they encounter. The perovskite dendrites showed a linear growth at two stages. The dendrites grew faster at early stage at about 5 to 7 μm/s and grew with a lower growth rate at about 1 to 2 μm/s in later stage. Finally, the growth mechanism of perovskite in melt was analyzed with the solidification theory. Based on the theoretical calculation of equilibrium phases in slag, the initial slag could be considered as a binary component system. One component was perovskite and the other component was the sum of all the other species that did not attend the crystallization of perovskite (included SiO2, Al2O3, and MgO, as well as CaO and TiO2 that were not involved in the solid formation). The formation of perovskite required the diffusion of CaO and TiO2 to the solid/liquid interface and the rejection of the other species from the interface. The solid/liquid equilibrium schematic diagram was made based on the calculation.

  6. Secondary superheater slagging reduction

    SciTech Connect

    Larose, J.A. ); Benson, R.C. )

    1992-01-01

    Utility boilers can be modified to reduce excessive slagging on the secondary superheater lower leading edges. Reduction of the high slagging accumulation rates will increase the pendant heat absorption and reduce the required superheater cleaning and slag removal. The cause of te slagging and appropriate boiler modifications are determined with numerical modeling. Results from two utility boiler analyses showed that regions of high gas and particle temperatures and flow rates exist near the superheater lower surfaces and are the probable cause of the rapid slagging. Design modifications which redistribute the flow and reduce the temperature entering the superheater reduce the impaction of molten ash on the pendant surface; this lowers the slag accumulation rate which allows the boiler to operate longer without cleaning and at a higher capacity. This paper shows the potential improvements in the secondary superheater inlet conditions by modifying the boiler.

  7. Archaeomagnetic study of ancient slag mounds in Cyprus: continuous paleointensity curves in high resolution

    NASA Astrophysics Data System (ADS)

    Shaar, R.; Tauxe, L.; Ben-Yosef, E.; Levy, T. E.; Kassianidou, V.; Lorentzen, B. E.

    2012-12-01

    One of the main challenges in paleointensity research is obtaining continuous high-resolution records that describe the behavior of the geomagnetic field on short time scales. One difficulty in obtaining such records is the problem of precise dating of suitable samples. Another fundamental difficulty is the assessment of the uncertainty involved in the interpretation of paleointensity experiments. Here we present an archaeomagnetic study of ancient slag mounds, which is designed to minimize these difficulties. We study two archaeological slag mounds in the Troodos foothills of Cyprus; one from the massive Roman mines at Skouriotissa, and another pre Roman near Mitsero Kokkinoyia. The mounds consist of industrial layers of copper slag intermixed with charcoal, which were deposited during times of intense copper smelting activity. The slag mound at Skouriotissa represents one of the largest copper production sites in the ancient world, including a 25 m high section and more than 40 archaeological layers. The mound at Mitsero is ca. 10 m high and contains about 32 layers. Hundreds of slag samples and associated charcoals from both mounds were collected, from which more than 600 slag specimens from more than 150 individual samples were analyzed for paleointensity. In addition,19 charcoals were radiocarbon dated. To minimize the uncertainty in the radiocarbon dating we applied a Bayesian model for each mound, which takes into account the relative stratigraphy of the layers. To reduce the uncertainty involved in the subjective interpretation of the paleointensity experiments (conventionally done by manually selecting temperature bounds in the Arai plot of each specimen) we designed new optimization software. The optimization software uses the assumption that paleointensity estimates from samples that were collected from the same level, should be similar. The optimization algorithm finds the selecting criteria that yields minimum scatter within each level, assigns

  8. An analysis of the causes of failure in high chrome oxide refractory materials from slagging gasifiers

    SciTech Connect

    Bennett, James P.; Kwong, Kyei-Sing; Powell, Cynthia A.; Thomas, Hugh; Krabbe, Rick

    2006-01-01

    High Cr2O3 refractory materials are used to line the hot face of slagging gasifiers. Gasifiers are reaction chambers that convert water, oxygen, and a carbon feedstock into CO, H2, and methane at temperatures as high as 1575DGC and pressures up to 1000 psi. Ash in the carbon feedstock liquefies, erodes and corrodes the gasifier's refractory liner, contributing to liner failure within a few months to two years. The failure of a refractory liner decreases a gasifier's on-line availability and causes costly system downtime and repairs. Many factors contribute to refractory lining failure, including slag penetration and corrosion, thermal cycling, gasifier environment, and mechanical loads. The results of refractory post-mortem failure analysis and how observations relate to gasifier service life will be discussed.

  9. Analysis of the causes of failure in high chrome oxide refractory materials from slagging gasifiers

    SciTech Connect

    Bennett, J.P.; Kwong, K.-S.; Powell, C.A.; Thomas, H.; Krabbe, R.A.

    2006-03-01

    High Cr2O3 refractory materials are used to line the hot face of slagging gasifiers. Gasifiers are reaction chambers that convert water, oxygen, and a carbon feedstock into CO, H2, and methane at temperatures as high as 1575oC and pressures up to 1000 psi. Ash in the carbon feedstock liquefies, erodes and corrodes the gasifier’s refractory liner, contributing to liner failure within a few months to two years. The failure of a refractory liner decreases a gasifier’s on-line availability and causes costly system downtime and repairs. Many factors contribute to refractory lining failure, including slag penetration and corrosion, thermal cycling, gasifier environment, and mechanical loads. The results of refractory post-mortem failure analysis and how observations relate to gasifier service life will be discussed.

  10. High conductivity composite metal

    DOEpatents

    Zhou, Ruoyi; Smith, James L.; Embury, John David

    1998-01-01

    Electrical conductors and methods of producing them, where the conductors possess both high strength and high conductivity. Conductors are comprised of carbon steel and a material chosen from a group consisting of copper, nickel, silver, and gold. Diffusion barriers are placed between these two materials. The components of a conductor are assembled and then the assembly is subjected to heat treating and mechanical deformation steps.

  11. High conductivity composite metal

    DOEpatents

    Zhou, R.; Smith, J.L.; Embury, J.D.

    1998-01-06

    Electrical conductors and methods of producing them are disclosed, where the conductors possess both high strength and high conductivity. Conductors are comprised of carbon steel and a material chosen from a group consisting of copper, nickel, silver, and gold. Diffusion barriers are placed between these two materials. The components of a conductor are assembled and then the assembly is subjected to heat treating and mechanical deformation steps. 10 figs.

  12. Highly Thermal Conductive Nanocomposites

    NASA Technical Reports Server (NTRS)

    Sun, Ya-Ping (Inventor); Connell, John W. (Inventor); Veca, Lucia Monica (Inventor)

    2015-01-01

    Disclosed are methods for forming carbon-based fillers as may be utilized in forming highly thermal conductive nanocomposite materials. Formation methods include treatment of an expanded graphite with an alcohol/water mixture followed by further exfoliation of the graphite to form extremely thin carbon nanosheets that are on the order of between about 2 and about 10 nanometers in thickness. Disclosed carbon nanosheets can be functionalized and/or can be incorporated in nanocomposites with extremely high thermal conductivities. Disclosed methods and materials can prove highly valuable in many technological applications including, for instance, in formation of heat management materials for protective clothing and as may be useful in space exploration or in others that require efficient yet light-weight and flexible thermal management solutions.

  13. Long-term evolution of highly alkaline steel slag drainage waters.

    PubMed

    Riley, Alex L; Mayes, William M

    2015-07-01

    The disposal of slag generated by the steel industry can have negative consequences upon the surrounding aquatic environment by the generation of high pH waters, leaching of potentially problematic trace metals, and rapid rates of calcite precipitation which smother benthic habitats. A 36-year dataset was collated from the long-term ambient monitoring of physicochemical parameters and elemental concentrations of samples from two steel slag leachate-affected watercourses in northern England. Waters were typified by elevated pH (>10), high alkalinity, and were rich in dissolved metals (e.g. calcium (Ca), aluminium (Al), and zinc (Zn)). Long-term trend analysis was performed upon pH, alkalinity, and Ca concentration which, in addition to Ca flux calculations, were used to highlight the longevity of pollution arising as a result of the dumping and subsequent leaching of steel slags. Declines in calcium and alkalinity have been modest over the monitoring period and not accompanied by significant declines in water pH. If the monotonic trends of decline in alkalinity and calcium continue in the largest of the receiving streams, it will be in the region of 50-80 years before calcite precipitation would be expected to be close to baseline levels, where ecological impacts would be negligible. PMID:26108748

  14. Extraction of vanadium from high calcium vanadium slag using direct roasting and soda leaching

    NASA Astrophysics Data System (ADS)

    Li, Xin-sheng; Xie, Bing

    2012-07-01

    The extraction of vanadium from high calcium vanadium slag was attempted by direct roasting and soda leaching. The oxidation process of the vanadium slag at different temperatures was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effects of roasting temperature, roasting time, Na2CO3 concentration, leaching temperature, leaching time, and liquid to solid ratio on the extraction of vanadium were studied. The results showed that olivine phases and spinel phases in the vanadium slag were completely decomposed at 500 and 800°C, respectively. Vanadium-rich phases were formed at above 850°C. The leaching rate of vanadium reached above 90% under the optimum conditions: roasting temperature of 850°C, roasting time of 60 min, Na2CO3 concentration of 160 g/L, leaching temperature of 95°C, leaching time of 150 min, and liquid to solid ratio of 10:1 mL/g. The main impurities were Si and P in the leach liquor.

  15. Recovery of iron and calcium aluminate slag from high-ferrous bauxite by high-temperature reduction and smelting process

    NASA Astrophysics Data System (ADS)

    Zhang, Ying-yi; Lü, Wei; Qi, Yuan-hong; Zou, Zong-shu

    2016-08-01

    A high-temperature reduction and smelting process was used to recover iron and calcium aluminate slag from high-ferrous bauxite. The effects of w(CaO)/ w(SiO2) ratio, anthracite ratio, and reduction temperature and time on the recovery and size of iron nuggets and on the Al2O3 grade of the calcium aluminate slag were investigated through thermodynamic calculations and experiments. The optimized process conditions were the bauxite/anthracite/slaked lime weight ratio of 100:16.17:59.37, reduction temperature of 1450°C and reduction time of 20 min. Under these conditions, high-quality iron nuggets and calcium aluminate slag were obtained. The largest size and the highest recovery rate of iron nuggets were 11.42 mm and 92.79wt%, respectively. The calcium aluminate slag mainly comprised Ca2SiO4 and Ca12Al14O33, with small amounts of FeAl2O4, CaAl2O4, and Ca2Al2SiO7.

  16. Seismic behavior of geogrid reinforced slag wall

    SciTech Connect

    Edincliler, Ayse; Baykal, Gokhan; Saygili, Altug

    2008-07-08

    Flexible retaining structures are known with their high performance under earthquake loads. In geogrid reinforced walls the performance of the fill material and the interface of the fill and geogrid controls the performance. Geosynthetic reinforced walls in seismic regions must be safe against not only static forces but also seismic forces. The objective of this study is to determine the behavior of a geogrid reinforced slag wall during earthquake by using shaking table experiments. This study is composed of three stages. In the first stage the physical properties of the material to be used were determined. In the second part, a case history involving the use of slag from steel industry in the construction of geogrid reinforced wall is presented. In the third stage, the results of shaking table tests conducted using model geogrid wall with slag are given. From the results, it is seen that slag can be used as fill material for geogrid reinforced walls subjected to earthquake loads.

  17. High conductance surge cable

    DOEpatents

    Murray, Matthew M.; Wilfong, Dennis H.; Lomax, Ralph E.

    1998-01-01

    An electrical cable for connecting transient voltage surge suppressers to ectrical power panels. A strip of electrically conductive foil defines a longitudinal axis, with a length of an electrical conductor electrically attached to the metallic foil along the longitudinal axis. The strip of electrically conductive foil and the length of an electrical conductor are covered by an insulating material. For impedance matching purposes, triangular sections can be removed from the ends of the electrically conductive foil at the time of installation.

  18. High conductance surge cable

    DOEpatents

    Murray, M.M.; Wilfong, D.H.; Lomax, R.E.

    1998-12-08

    An electrical cable for connecting transient voltage surge suppressors to electrical power panels. A strip of electrically conductive foil defines a longitudinal axis, with a length of an electrical conductor electrically attached to the metallic foil along the longitudinal axis. The strip of electrically conductive foil and the length of an electrical conductor are covered by an insulating material. For impedance matching purposes, triangular sections can be removed from the ends of the electrically conductive foil at the time of installation. 6 figs.

  19. Reduction Kinetics of MnO from High-Carbon Ferromanganese Slags by Carbonaceous Materials in Ar and CO Atmospheres

    NASA Astrophysics Data System (ADS)

    Safarian, J.; Tranell, G.; Kolbeinsen, L.; Tangstad, M.; Gaal, S.; Kaczorowski, J.

    2008-10-01

    The kinetics of MnO reduction from synthetic and industrial high-carbon ferromanganese slags were investigated using a sessile drop technique at 1600 °C. The effects of the reductant type, ambient atmosphere, and slag composition on the MnO reduction were illuminated. Six different types of carbonaceous reductants were used as substrates for small slag droplets, which were reacted in a CO or Ar atmosphere, with the reaction studied in situ. The cross sections of the reacted slag-carbon samples were subsequently studied by electron-probe microanalysis (EPMA), to find the extent of the MnO reduction as a function of the reaction time. It was found that the rate of the MnO reduction is affected by both the type of reductant and the ambient atmosphere. It was observed that the MnO reduction rate from synthetic slag by cokes produced from single coals is lower than that from industrial cokes. Reduction rates obtained when charcoal was used as the reductant were higher than when coke was used, while the CO atmosphere yielded a faster initial MnO reduction than did the Ar atmosphere. It was found that the faster reduction rates in the CO atmosphere are related to the MnO reduction by CO gas. A newly developed kinetic method was applied, to calculate the rate constants for the MnO reduction by carbon and CO that considered the reaction interfaces. It was indicated that the rate of the MnO reduction by CO is less than that by carbon; however, the contribution of these reductants to slag reduction is very dependent on their contact with the slag.

  20. Two-stage high temperature sludge gasification using the waste heat from hot blast furnace slags.

    PubMed

    Sun, Yongqi; Zhang, Zuotai; Liu, Lili; Wang, Xidong

    2015-12-01

    Nowadays, disposal of sewage sludge from wastewater treatment plants and recovery of waste heat from steel industry, become two important environmental issues and to integrate these two problems, a two-stage high temperature sludge gasification approach was investigated using the waste heat in hot slags herein. The whole process was divided into two stages, i.e., the low temperature sludge pyrolysis at ⩽ 900°C in argon agent and the high temperature char gasification at ⩾ 900°C in CO2 agent, during which the heat required was supplied by hot slags in different temperature ranges. Both the thermodynamic and kinetic mechanisms were identified and it was indicated that an Avrami-Erofeev model could best interpret the stage of char gasification. Furthermore, a schematic concept of this strategy was portrayed, based on which the potential CO yield and CO2 emission reduction achieved in China could be ∼1.92∗10(9)m(3) and 1.93∗10(6)t, respectively. PMID:26409106

  1. Slag pit practices to improve slag quality

    SciTech Connect

    Mertdogan, A.; Gambol, F.C.; Spaeth, J.R.; Zbos, J.; Batka, R.; Tolliver, D.

    1996-12-31

    Slag quality had deteriorated recently. Without the explicit approval for slag quality by the Illinois Department of Transportation, the slag would not be saleable. Disposal of slag to landfills was going to be an expensive solution and rife with environmental concerns. A slag quality control program embarked on in mid-1994 restored slag quality to desired specifications. This paper describes the changes in slag pit practice adopted following extensive tests performed on cooling slag under controlled conditions.

  2. Integration of coal gasification and waste heat recovery from high temperature steel slags: an emerging strategy to emission reduction

    NASA Astrophysics Data System (ADS)

    Sun, Yongqi; Sridhar, Seetharaman; Liu, Lili; Wang, Xidong; Zhang, Zuotai

    2015-11-01

    With the continuous urbanization and industrialization in the world, energy saving and greenhouse gas (GHG) emission reduction have been serious issues to be addressed, for which heat recovery from traditional energy-intensive industries makes up a significant strategy. Here we report a novel approach to extract the waste heat and iron from high temperature steel slags (1450-1650 oC) produced in the steel industry, i.e., integration of coal gasification and steel slag treatment. Both the thermodynamics and kinetics of the pertinent reactions were identified. It was clarified that the kinetic mechanism for gasification varied from A2 model to A4 model (Avrami-Erofeev) in the presence of slags. Most importantly, the steel slags acted not only as good heat carriers but also as effective catalysts where the apparent activation energy for char gasification got remarkably reduced from 95.7 kJ/mol to 12.1 kJ/mol (A2 model). Furthermore, the FeO in the slags was found to be oxidized into Fe3O4, with an extra energy release, which offered a potential for magnetic separation. Moreover, based on the present research results, an emerging concept, composed of multiple industrial sectors, was proposed, which could serve as an important route to deal with the severe environmental problems in modern society.

  3. Integration of coal gasification and waste heat recovery from high temperature steel slags: an emerging strategy to emission reduction.

    PubMed

    Sun, Yongqi; Sridhar, Seetharaman; Liu, Lili; Wang, Xidong; Zhang, Zuotai

    2015-01-01

    With the continuous urbanization and industrialization in the world, energy saving and greenhouse gas (GHG) emission reduction have been serious issues to be addressed, for which heat recovery from traditional energy-intensive industries makes up a significant strategy. Here we report a novel approach to extract the waste heat and iron from high temperature steel slags (1450-1650 (o)C) produced in the steel industry, i.e., integration of coal gasification and steel slag treatment. Both the thermodynamics and kinetics of the pertinent reactions were identified. It was clarified that the kinetic mechanism for gasification varied from A2 model to A4 model (Avrami-Erofeev) in the presence of slags. Most importantly, the steel slags acted not only as good heat carriers but also as effective catalysts where the apparent activation energy for char gasification got remarkably reduced from 95.7 kJ/mol to 12.1 kJ/mol (A2 model). Furthermore, the FeO in the slags was found to be oxidized into Fe3O4, with an extra energy release, which offered a potential for magnetic separation. Moreover, based on the present research results, an emerging concept, composed of multiple industrial sectors, was proposed, which could serve as an important route to deal with the severe environmental problems in modern society. PMID:26558350

  4. Integration of coal gasification and waste heat recovery from high temperature steel slags: an emerging strategy to emission reduction

    PubMed Central

    Sun, Yongqi; Sridhar, Seetharaman; Liu, Lili; Wang, Xidong; Zhang, Zuotai

    2015-01-01

    With the continuous urbanization and industrialization in the world, energy saving and greenhouse gas (GHG) emission reduction have been serious issues to be addressed, for which heat recovery from traditional energy-intensive industries makes up a significant strategy. Here we report a novel approach to extract the waste heat and iron from high temperature steel slags (1450–1650 oC) produced in the steel industry, i.e., integration of coal gasification and steel slag treatment. Both the thermodynamics and kinetics of the pertinent reactions were identified. It was clarified that the kinetic mechanism for gasification varied from A2 model to A4 model (Avrami-Erofeev) in the presence of slags. Most importantly, the steel slags acted not only as good heat carriers but also as effective catalysts where the apparent activation energy for char gasification got remarkably reduced from 95.7 kJ/mol to 12.1 kJ/mol (A2 model). Furthermore, the FeO in the slags was found to be oxidized into Fe3O4, with an extra energy release, which offered a potential for magnetic separation. Moreover, based on the present research results, an emerging concept, composed of multiple industrial sectors, was proposed, which could serve as an important route to deal with the severe environmental problems in modern society. PMID:26558350

  5. Accelerated carbonation of steelmaking slags in a high-gravity rotating packed bed.

    PubMed

    Chang, E-E; Pan, Shu-Yuan; Chen, Yi-Hung; Tan, Chung-Sung; Chiang, Pen-Chi

    2012-08-15

    Carbon dioxide (CO(2)) sequestration using the accelerated carbonation of basic oxygen furnace (BOF) slag in a high-gravity rotating packed bed (RPB) under various operational conditions was investigated. The effects of reaction time, reaction temperature, rotation speed and slurry flow rate on the CO(2) sequestration process were evaluated. The samples of reacted slurry were analyzed quantitatively using thermogravimetric analysis (TGA) and atomic absorption spectrometry (AAS) and qualitatively using X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), and transmission electron microscopy (TEM). The sequestration experiments were performed at a liquid-to-solid ratio of 20:1 with a flow rate of 2.5 L min(-1) of a pure CO(2) stream under atmospheric temperature and pressure. The results show that a maximum conversion of BOF slag was 93.5% at a reaction time of 30 min and a rotation speed of 750 rpm at 65°C. The experimental data were utilized to determine the rate-limiting mechanism based on the shrinking core model (SCM), which was validated by the observations of SEM and TEM. Accelerated carbonation in a RPB was confirmed to be a viable method due to its higher mass-transfer rate. PMID:22633879

  6. Laboratory Study on Oxide Inclusions in High-Strength Low-Alloyed Steel Refined by Slag with Basicity 2-5

    NASA Astrophysics Data System (ADS)

    Yu, Huixiang; Wang, Xinhua; Zhang, Jing; Wang, Wanjun

    2015-11-01

    Non-metallic inclusions in high-strength low-alloyed steel refined by slag with basicity (B) 2-5 and Al2O3 content 20%-30% (in mass percent) were investigated by slag-metal equilibrium experiments in laboratory and thermodynamic calculations. Most inclusions in equilibrium were quasi-spherical CaO-MgO-Al2O3-SiO2 system and the sizes were less than 5 µm. The average content ratio, CaO/Al2O3 and CaO/SiO2 of the inclusions, increased with slag basicity increasing when Al2O3 content in slag was around 25%, MgO/Al2O3 and CaO/Al2O3 increased with Al2O3 content in slag decreasing when slag basicity was around 3.3. The MgO/Al2O3 of the inclusions was influenced mainly by Al2O3 content in slag and CaO/Al2O3 was influenced mainly by slag basicity. To make the inclusions out of relative lower melting region (<1,773 K), the values of CaO/Al2O3, MgO/Al2O3 and (CaO+MgO)/Al2O3 of the inclusions should be enhanced by increasing basicity and decreasing Al2O3 content in slag properly.

  7. 50. Taken from highline; "B" furnace slag pots, pipe is ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    50. Taken from high-line; "B" furnace slag pots, pipe is main blast furnace gas line from "C" furnace dust catcher; levy, slag hauler, removing slag. Looking east - Rouge Steel Company, 3001 Miller Road, Dearborn, MI

  8. Molten welding slag enthalpies

    SciTech Connect

    Stukalo, V.A.; Neshchimenko, N.Ya.; Batalin, G.I.; Patselii, N.V.; Galinich, V.I.

    1988-05-01

    We measured enthalpies at 1740-19970 K for four multicomponent oxide liquids. The initial materials were special-purity metal oxides, chemically pure manganese oxalate, and calcium fluoride. High-temperature calorimetry has been applied to the enthalpies of slags used in automatic constructional-steel welding. The mean specific heats have been calculated from the temperature dependence of the enthalpies. The enthalpies increase with the basicity in these slags.

  9. Vanadium bioavailability in soils amended with blast furnace slag.

    PubMed

    Larsson, Maja A; Baken, Stijn; Smolders, Erik; Cubadda, Francesco; Gustafsson, Jon Petter

    2015-10-15

    Blast furnace (BF) slags are commonly applied as soil amendments and in road fill material. In Sweden they are also naturally high in vanadium. The aim of this study was to assess the vanadium bioavailability in BF slags when applied to soil. Two soils were amended with up to 29% BF slag (containing 800 mg V kg(-1)) and equilibrated outdoors for 10 months before conducting a barley shoot growth assay. Additional soil samples were spiked with dissolved vanadate(V) for which assays were conducted two weeks (freshly spiked) and 10 months (aged) after spiking. The BF slag vanadium was dominated by vanadium(III) as shown by V K-edge XANES spectroscopy. In contrast, results obtained by HPLC-ICP-MS showed that vanadium(V), the most toxic vanadium species, was predominant in the soil solution. Barley shoot growth was not affected by the BF slag additions. This was likely due to limited dissolution of vanadium from the BF slag, preventing an increase of dissolved vanadium above toxic thresholds. The difference in vanadium bioavailability among treatments was explained by the vanadium concentration in the soil solution. It was concluded that the vanadium in BF slag is sparingly available. These findings should be of importance in environmental risk assessment. PMID:25917693

  10. Chemical characterization of high-temperature arc gasification slag with a focus on element release in the environment.

    PubMed

    Roessler, Justin G; Oehmig, Wesley N; Blaisi, Nawaf I; Townsend, Timothy G

    2014-07-15

    High-temperature arc gasification (HTAG) has been proposed as a viable technology for the generation of energy and the production of saleable byproducts from municipal solid waste (MSW). Total concentrations of elements in HTAG slag were assessed and indicated a high partitioning of trace elements (Pb, Cd, and As) into the flue gas, an issue of concern when assessing the air pollution control residues (APCR) status as a hazardous waste. Hazardous waste leaching tests [such as the toxicity characteristic leaching procedure (TCLP)] were performed and confirmed that the slag did not meet U.S. criteria for a hazardous waste. Leaching was assessed using batch and column tests; the results revealed that Sb and Al were elevated in respect to risk-based regulatory thresholds. Slag samples were carbonated to simulate weathering effects, and although leachable concentrations of Al did decrease by an order of magnitude, Sb concentrations were found to increase. Low total concentrations of certain trace elements (As, Cd, and Pb), with respect to MSW incineration bottom ashes support the potential for reuse of HTAG slag; however, leaching of elements (Pb, Al, and Sb) in batch and column tests indicate that proper engineering controls would need to be taken to ensure protection of water supplies in a reuse application. PMID:24912855

  11. Characterizing coal-gasifier slag-refractory interactions

    SciTech Connect

    Rawers, James C.; Kwong, Kyei-Sing; Bennett, James P.

    1999-01-01

    To characterize refractory degradation and loss in commercial coal-gasifier combined cycle power systems, cup-type tests were conducted on high chromium-alumina, sinter-bonded refractories under laboratory conditions designed to simulate commercial operations of temperature, atmosphere, and slag interactions. These tests provided qualitative results from which the slag?refractory interactions can be characterized. These high chromium refractories were generally inert with respect to the coal slag components. However, in this study preliminary findings did show (1) iron ( oxide) in the slag reacted with chrome sesquioxide to produce a Cr?Fe spinel at the slag?refractory interface, and (2) chrome was soluble in the molten slag. Comparison of cup-type test results with data from operating commercial plants suggests that the principal loss of refractory material in a coal-gasifier combustion chamber is chrome dissolution into the slag. Tests are currently underway to determine if minor modifications to the combustion process might increase refractory life.

  12. Slag of Greek provenance uses in materials science and geophysics: implications for a highly potential material in the service of the development of Greek economy

    NASA Astrophysics Data System (ADS)

    Leontakianakos, G.; Baziotis, I.; Sotiriadis, K.; Goulas, G.; Liakopoulos, S.; Karastathis, V.

    2012-04-01

    parameters was done at steady state isothermal conditions using a set-up of dimensional water-vapor diffusion. Thermal conductivity and heat capacity were also specified. Specimens showed very good behavior under heating. Thermal properties were not significantly affected during the heating procedure leading to the conclusion that such materials can be used as protective layers against fire. Covering concrete structures is an effective way of protection against high temperatures. The above study shows that the slag of Greek origin is a material with a significant potential to be used in the field of building constructions protection against high temperatures. Though, it is an extremely promising material of highly potential value which can turn it into to the accessory part of the steam engine for sustainable development of the Greek economy.

  13. Bubbling at high flow rates in inviscid and viscous liquids (slags)

    NASA Astrophysics Data System (ADS)

    Engh, T. Abel; Nilmani, M.

    1988-02-01

    The behavior of gas discharging into melts at high velocities but still in the bubbling regime has been investigated in a laboratory modeling study for constant flow conditions. Air or helium was injected through a vertical tuyere into water, zinc-chloride, and aqueous glycerol solutions. High speed cinematography and pressure measurements in the tuyere have been carried out simultaneously. Pressure fluctuations at the injection point were monitored and correlated to the mode of bubble formation. The effects of high gas flow rates and high liquid viscosities have been examined in particular. Flow rates were employed up to 10-3 m3/s and viscosity to 0.5 Ns/m2. In order to attain a high gas momentum, the tuyere diameter was only 3 x 10-3 m. The experimental conditions and modeling liquids were chosen with special reference to the established practice of submerged gas injection to treat nonferrous slags. Such slags can be highly viscous. Bubble volume is smaller than that calculated from existing models such as those given by Davidson and Schüler10,11 due to the effect of gas momentum elongating the bubbles. On the other hand, viscosity tends to retard the bubble rise velocity, thus increasing volumes. To take elongation into account, a mathematical model is presented that assumes a prolate ellipsoidal shape of the bubbles. The unsteady potential flow equations for the liquid are solved for this case. Viscous effects are taken into account by noting that flow deviates from irrotational motion only in a thin boundary layer along the surface of the bubble. Thus, drag on the bubble can be obtained by calculating the viscous energy dissipation for potential flow past an ellipse. The time-dependent inertia coefficient for the ellipsoid is found by equating the vertical pressure increase inside and outside the bubble. This pressure change in the bubble is obtained by assuming that gas enters as a homogeneous jet and then calculating the stagnation pressure at the apex of

  14. Compatibility of water-cooled chromia-containing refractories with a high iron oxide acidic coal-ash slag at 1575/sup 0/C

    SciTech Connect

    Kennedy, C.R.

    1981-12-01

    Sixteen water-cooled refractories were exposed to a synthetic high iron oxide acidic coal slag. The importance of high chromia content and density in minimizing corrosive attack was evident. The beneficial effect of water cooling was also demonstrated. All the refractories reacted with the slag to form complex intermediate spinel layers. Refractories high in chromia resist fluxing by iron oxide better than refractories high in alumina.

  15. High temperature corrosion of MoSi2 HfO2 composites in coal slag

    NASA Astrophysics Data System (ADS)

    Mueller, Michael; Hilpert, Klaus; Singheiser, Lorenz

    2005-02-01

    The corrosion behaviour of MoSi2 15%HfO2 composites was investigated under simulated Pressurized Pulverized Coal Combustion (PPCC) conditions at 1450 °C in the presence of liquid slag. The composites form a dense glassy corrosion product layer which consists mainly of SiO2 and HfSiO4. The specimens show relative good corrosion resistance against coal slag in comparison to most commercial available ceramic materials.

  16. Disposal of High-Temperature Slags: A Review of Integration of Heat Recovery and Material Recycling

    NASA Astrophysics Data System (ADS)

    Sun, Yongqi; Zhang, Zuotai

    2016-05-01

    Nowadays with the continuous urbanization in China, the carbon emission and resource shortage have been serious issues, for which the disposal of blast furnace slags (BFS) and steel slags (SS) discharged from the metallurgical industry make up a significant strategy. The output of crude steel reached 823 Mt in China in 2014 and the thermal heat in these slags was equivalent to ~18 Mt of standard coal. Herein, the recent advances were systemically reviewed and analyzed, mainly from two respects, i.e., integration of heat recovery and material recycling and crystallization control of the slags. It was first found that for the heat recovery from BFS, the most intensively investigated physical method and chemical method were centrifugal granulation and gasification reaction, respectively. Furthermore, a two-step approach could contribute to a promising strategy for the treatment of slags, i.e., the liquid slags were first granulated into small particles, and then other further treatment was performed such as gasification reaction. With regard to SS, the effective disposal could be achieved using a selective crystallization and phase separation (SCPS) method, and moreover, the solid solution of 2CaO·SiO2 and the target phases could act as a promising enriched phase to extract the valuable elements.

  17. Slagging gasifier

    SciTech Connect

    Schulz, H.

    1982-07-20

    A slagging gasifier for the gasification of coal and organic waste materials is disclosed. The gasifier includes a vertical blast furnace having a hearth section at the bottom thereof. A slag tap hole is formed in hearth section and opens into a quenching vessel. A honeycomb structure is formed on the inner surface of said hearth section in the area surrounding said slag tap hole, and the inner wall of the hearth section. A plurality of tuyeres extend into the hearth section and feed the furnace with steam and oxygen so as to permit the oxidation of coal and organic waste materials fed into the furnace. As a result of the oxidation, gas and molten slag are formed in the furnace. The slag is collected in the hearth section and exits the hearth section via the tap hole. One or more conduits are provided for recycling (Either internally or externally) the gas exiting the top of the gasifier with the tars, oils, and particulates entrained therein to the partial combustion zone of the gasifier where the tars, oils and particulates are converted to noncondensible gases. A portion of the tar-free product gas is removed from an intermediate point in the gasifier below the pyrolysis and coking zone.

  18. Hydrology and geochemistry of a slag-affected aquifer and chemical characteristics of slag-affected ground water, northwestern Indiana and northeastern Illinois

    USGS Publications Warehouse

    Bayless, E. Randall; Greeman, T.K.; Harvey, C.C.

    1998-01-01

    Slag is a by-product of steel manufacturing and a ubiquitous fill material in northwestern Indiana. Ground water associated with slag deposits generally is characterized by high pH and elevated concentrations of many inorganic water-quality constituents. The U.S. Geological Survey, in cooperation with the Indiana Department of Environmental Management, conducted a study in northwestern Indiana from June 1995 to September 1996 to improve understanding of the effects of slag deposits on the water quality of a glacial-outwash aquifer. The Bairstow Landfill, a slag-fill deposit overlying the Calumet aquifer near Hammond, Indiana, was studied to represent conditions in slag-deposit settings that are common in northwestern Indiana. Ground water from 10 observation wells, located in four nests at the site, and surface water from the adjacent Lake George were analyzed for values of field-measured parameters and concentrations of major ions, nutrients, trace elements, and bulk properties. Solid-phase samples of slag and aquifer sediment collected during drilling were examined with X-ray diffraction and geochemical digestion and analysis. Concentrations of calcium, potassium, sodium, and sulfate were highest in wells screened partly or fully in slag. Potassium concentrations in ground water ranged from 2.9 to 120 milligrams per liter (mg/L), were highest in water from slag deposits, and decreased with depth. The highest concentrations for aluminum, barium, molybdenum, nickel, and selenium were in water from the slag. Silica concentrations were highest in wells screened directly beneath the slag?aquifer interface, and magnesium concentrations were highest in intermediate and deep aquifer wells. Silica concentrations in shallow and intermediate aquifer wells ranged from 27 to 41 mg/L and were about 10 times greater than those in water from slag deposits. The highest concentrations for chromium, lead, and zinc were in ground water from immediately below the slag

  19. Crystallization Behavior of Perovskite in the Synthesized High-Titanium-Bearing Blast Furnace Slag Using Confocal Scanning Laser Microscope

    NASA Astrophysics Data System (ADS)

    Hu, Meilong; Liu, Lu; Lv, Xuewei; Bai, Chenguang; Zhang, Shengfu

    2013-10-01

    The isothermal phase composition of high-titanium-bearing slag (23 mass pct TiO2) under an argon atmosphere during cooling process from 1723 K (1450 °C) was calculated by FactSage.6.3 (CRCT-ThermFact Inc., Montréal, Canada). Three main phases, which were perovskite, titania spinel, and clinopyroxene, could form during the cooling process and they precipitated at 1713 K, 1603 K, and 1498 K (1440 °C, 1330 °C, and 1225 °C), respectively. The nonisothermal crystallization process of perovskite in synthesized high-titanium-bearing slag was studied in situ by a confocal scanning laser microscope (CSLM) with cooling rate of 30 K/min. The results showed that the primary phase was perovskite that precipitated at 1703 K (1430 °C). The whole precipitation and growth process of perovskite was obtained, whereas other phases formed as glass under the current experimental conditions. Perovskite grew along a specific growth track and finally appeared with snowflake morphology. The growing kinetics of perovskite formation from molten slag were also mentioned.

  20. HIGH-TEMPERATURE HEAT EXCHANGER TESTING IN A PILOT-SCALE SLAGGING FURNACE SYSTEM

    SciTech Connect

    Michael E. Collings; Bruce A. Dockter; Douglas R. Hajicek; Ann K. Henderson; John P. Hurley; Patty L. Kleven; Greg F. Weber

    1999-12-01

    The University of North Dakota Energy & Environmental Research Center (EERC), in partnership with United Technologies Research Center (UTRC) under a U.S. Department of Energy (DOE) contract, has designed, constructed, and operated a 3.0-million Btu/hr (3.2 x 10{sup 6} kJ/hr) slagging furnace system (SFS). Successful operation has demonstrated that the SFS meets design objectives and is well suited for testing very high-temperature heat exchanger concepts. Test results have shown that a high-temperature radiant air heater (RAH) panel designed and constructed by UTRC and used in the SFS can produce a 2000 F (1094 C) process air stream. To support the pilot-scale work, the EERC has also constructed laboratory- and bench-scale equipment which was used to determine the corrosion resistance of refractory and structural materials and develop methods to improve corrosion resistance. DOE projects that from 1995 to 2015, worldwide use of electricity will double to approach 20 trillion kilowatt hours. This growth comes during a time of concern over global warming, thought by many policy makers to be caused primarily by increases from coal-fired boilers in carbon dioxide (CO{sub 2}) emissions through the use of fossil fuels. Assuming limits on CO{sub 2} emissions from coal-fired boilers are imposed in the future, the most economical CO{sub 2} mitigation option may be efficiency improvements. Unless efficiency improvements are made in coal-fired power plants, utilities may be forced to turn to more expensive fuels or buy CO{sub 2} credits. One way to improve the efficiency of a coal-fired power plant is to use a combined cycle involving a typical steam cycle along with an indirectly fired turbine cycle using very high-temperature but low-pressure air as the working fluid. At the heart of an indirectly fired turbine combined-cycle power system are very high-temperature heat exchangers that can produce clean air at up to 2600 F (1427 C) and 250 psi (17 bar) to turn an

  1. Thermodynamics and Kinetics of Boron Removal from Metallurgical Grade Silicon by Addition of High Basic Potassium Carbonate to Calcium Silicate Slag

    NASA Astrophysics Data System (ADS)

    Wu, Jijun; Wang, Fanmao; Ma, Wenhui; Lei, Yun; Yang, Bin

    2016-02-01

    In this study, we investigated the thermodynamics and kinetics of boron removal from metallurgical grade silicon (MG-Si) using a calcium silicate slag containing a high basic potassium carbonate. The distribution of boron between slag and silicon was theoretically derived and the distribution coefficients (L B) of boron with different compositions of CaO, SiO2, and K2CO3 in slag reagents were determined. The maximal value of L B reached 2.08 with a high basicity slag of 40 pctCaO-40 pctSiO2-20 pctK2CO3 (Λ = 0.73). The boron removal rates from MG-Si using CaO-SiO2 and CaO-SiO2-K2CO3 slags at 1823 K (1550 °C) were investigated in an electromagnetic induction furnace. The results showed that the boron concentration in MG-Si can be reduced from 22 to 1.8 ppmw at 1823 K (1550 °C) with 20 pct K2CO3 addition to calcium silicate slag, where the removal efficiency of boron reached 91.8 pct. The mass transfer coefficient (β S) of boron in binary 50 pctCaO-50 pctSiO2 slag was 3.16 × 10-6 m s-1 at 1823 K (1550 °C) and was 2.43 × 10-5 m s-1 in ternary 40 pctCaO-40 pctSiO2-20 pctK2CO3 slag.

  2. Thermodynamics and Kinetics of Boron Removal from Metallurgical Grade Silicon by Addition of High Basic Potassium Carbonate to Calcium Silicate Slag

    NASA Astrophysics Data System (ADS)

    Wu, Jijun; Wang, Fanmao; Ma, Wenhui; Lei, Yun; Yang, Bin

    2016-06-01

    In this study, we investigated the thermodynamics and kinetics of boron removal from metallurgical grade silicon (MG-Si) using a calcium silicate slag containing a high basic potassium carbonate. The distribution of boron between slag and silicon was theoretically derived and the distribution coefficients ( L B) of boron with different compositions of CaO, SiO2, and K2CO3 in slag reagents were determined. The maximal value of L B reached 2.08 with a high basicity slag of 40 pctCaO-40 pctSiO2-20 pctK2CO3 (Λ = 0.73). The boron removal rates from MG-Si using CaO-SiO2 and CaO-SiO2-K2CO3 slags at 1823 K (1550 °C) were investigated in an electromagnetic induction furnace. The results showed that the boron concentration in MG-Si can be reduced from 22 to 1.8 ppmw at 1823 K (1550 °C) with 20 pct K2CO3 addition to calcium silicate slag, where the removal efficiency of boron reached 91.8 pct. The mass transfer coefficient ( β S) of boron in binary 50 pctCaO-50 pctSiO2 slag was 3.16 × 10-6 m s-1 at 1823 K (1550 °C) and was 2.43 × 10-5 m s-1 in ternary 40 pctCaO-40 pctSiO2-20 pctK2CO3 slag.

  3. Highly elastic conductive polymeric MEMS

    NASA Astrophysics Data System (ADS)

    Ruhhammer, J.; Zens, M.; Goldschmidtboeing, F.; Seifert, A.; Woias, P.

    2015-02-01

    Polymeric structures with integrated, functional microelectrical mechanical systems (MEMS) elements are increasingly important in various applications such as biomedical systems or wearable smart devices. These applications require highly flexible and elastic polymers with good conductivity, which can be embedded into a matrix that undergoes large deformations. Conductive polydimethylsiloxane (PDMS) is a suitable candidate but is still challenging to fabricate. Conductivity is achieved by filling a nonconductive PDMS matrix with conductive particles. In this work, we present an approach that uses new mixing techniques to fabricate conductive PDMS with different fillers such as carbon black, silver particles, and multiwalled carbon nanotubes. Additionally, the electrical properties of all three composites are examined under continuous mechanical stress. Furthermore, we present a novel, low-cost, simple three-step molding process that transfers a micro patterned silicon master into a polystyrene (PS) polytetrafluoroethylene (PTFE) replica with improved release features. This PS/PTFE mold is used for subsequent structuring of conductive PDMS with high accuracy. The non sticking characteristics enable the fabrication of delicate structures using a very soft PDMS, which is usually hard to release from conventional molds. Moreover, the process can also be applied to polyurethanes and various other material combinations.

  4. High thermal conductivity of diamond

    NASA Technical Reports Server (NTRS)

    Stephan, Patrick M.

    1993-01-01

    The objectives of this educational exercise were to demonstrate the high rate of heat flow from a synthetic diamond coupon and to compare it to a commonly used thermal conductor, such as copper. The principles of heat transfer by conduction and convection may also be demonstrated. A list of equipment and supplies and the procedure for the experiment are presented.

  5. Advanced Characterization of Slags and Refractory Bricks Using Electron Backscatter Diffraction

    SciTech Connect

    John Kay; Kurt Eylands

    2007-09-30

    Numerous studies have been conducted to determine changes that occur in slag that cause a rapid change in viscosity, but these studies have been limited by the inability to characterize/identify the phases present in the slag. Rapid freezing of slag in entrained gasifiers and slagging combustion systems can cause a shutdown of the system. The reactions occurring in slag that result in rapid freezing of slags are not well understood. It is believed that electron backscatter diffraction (EBSD) can be used to analyze slags and aid in their characterization although its use has not been found in literature. The EBSD technique allows particle-by-particle mineralogy based on diffraction patterns generated by the electron beam when the sample is tilted to a high angle. The diffraction pattern (Kikuchi bands) can only come from crystalline phases, which makes this technique ideally suited to study crystal formation in slags where oftentimes the crystals are very small and a reasonable chemical analysis cannot be made by conventional energy-dispersive spectrometry (EDS) methods in the scanning electron microscope. The ability to have mineralogical data based on the crystalline structure of a phase rather than a chemical analysis by EDS allows much better interpretation of the temperature regimes in which specific phases tend to form. Knowing the type and relative amounts of a phase crystallizing in a slag is critical in predicting the viscosity of a slag at a given temperature. Six slag samples were selected based on the parent coal. Unfortunately, none of the slags appeared to have any crystalline material associated with them. The funding for this project was not adequate for generating more slags from the various coal types. For this reason, sample archives were searched for those containing slags that were not rapidly quenched. A slag from a bituminous coal was found to contain several dendritic crystals (10 {mu}m to 50 {mu}m in size) that formed near the edges of the

  6. Slag Behavior in Gasifiers. Part II: Constitutive Modeling of Slag

    SciTech Connect

    Massoudi, Mehrdad; Wang, Ping

    2013-02-07

    The viscosity of slag and the thermal conductivity of ash deposits are among two of the most important constitutive parameters that need to be studied. The accurate formulation or representations of the (transport) properties of coal present a special challenge of modeling efforts in computational fluid dynamics applications. Studies have indicated that slag viscosity must be within a certain range of temperatures for tapping and the membrane wall to be accessible, for example, between 1,300 °C and 1,500 °C, the viscosity is approximately 25 Pa·s. As the operating temperature decreases, the slag cools and solid crystals begin to form. Since slag behaves as a non-linear fluid, we discuss the constitutive modeling of slag and the important parameters that must be studied. We propose a new constitutive model, where the stress tensor not only has a yield stress part, but it also has a viscous part with a shear rate dependency of the viscosity, along with temperature and concentration dependency, while allowing for the possibility of the normal stress effects. In Part I, we reviewed, identify and discuss the key coal ash properties and the operating conditions impacting slag behavior.

  7. Transport and removal of bacteriophages MS2 and PhiX174 in steel slag-amended soils: column experiments and transport model analyses.

    PubMed

    Park, Jeong-Ann; Kang, Jin-Kyu; Kim, Jae-Hyun; Kim, Song-Bae; Yu, Seungho; Kim, Tae-Hun

    2014-01-01

    The aim of this study was to investigate the removal of bacteriophages MS2 and PhiX174 in soils amended with converter furnace steel slag. Column experiments were performed to examine the bacteriophage removal in slag-amended (slag content: 0%, 25%, and 50%) loam soils. For comparison, column experiments were also conducted with Escherichia coli. In addition, chloride (Cl) was used as a conservative tracer to determine transport characteristics. Results showed mass recoveries of Cl of 98.6 +/- 3.5%, indicating that the experiments were conducted successfully. The mass recovery of MS2 was 86.7% in no slag (100% soil), decreasing to 0% in slag contents of 25% and 50%. The mass recovery of PhiX174 decreased from 87.8% to 51.5% with increasing slag content from 0% to 50%. In the case of E. coli, the mass recoveries decreased from 47.0% to 10.5% with increasing slag content from 0% to 50%. In the transport models analyses, the HYDRUS-1D code was used to quantify the sorption parameters from breakthrough curves. For the 100% soil column, a one-site kinetic sorption model was fitted to the data, whereas a two-site kinetic sorption model was fitted for slag-amended (25% and 50% slag) soil data. Results demonstrate that the addition of steel slag to soil enhances the removal of bacteriophages due to the presence of FeO in the steel slag. However, CaO could not contribute to the bacteriophage removal in our experimental conditions because the effluent pH (7.7-8.9) in slag-amended (25% and 50% slag) soils was not high enough to promote the bacteriophage inactivation. PMID:24701916

  8. High-Thermal-Conductivity Fabrics

    NASA Technical Reports Server (NTRS)

    Chibante, L. P. Felipe

    2012-01-01

    Heat management with common textiles such as nylon and spandex is hindered by the poor thermal conductivity from the skin surface to cooling surfaces. This innovation showed marked improvement in thermal conductivity of the individual fibers and tubing, as well as components assembled from them. The problem is centered on improving the heat removal of the liquid-cooled ventilation garments (LCVGs) used by astronauts. The current design uses an extensive network of water-cooling tubes that introduces bulkiness and discomfort, and increases fatigue. Range of motion and ease of movement are affected as well. The current technology is the same as developed during the Apollo program of the 1960s. Tubing material is hand-threaded through a spandex/nylon mesh layer, in a series of loops throughout the torso and limbs such that there is close, form-fitting contact with the user. Usually, there is a nylon liner layer to improve comfort. Circulating water is chilled by an external heat exchanger (sublimator). The purpose of this innovation is to produce new LCVG components with improved thermal conductivity. This was addressed using nanocomposite engineering incorporating high-thermalconductivity nanoscale fillers in the fabric and tubing components. Specifically, carbon nanotubes were added using normal processing methods such as thermoplastic melt mixing (compounding twin screw extruder) and downstream processing (fiber spinning, tubing extrusion). Fibers were produced as yarns and woven into fabric cloths. The application of isotropic nanofillers can be modeled using a modified Nielsen Model for conductive fillers in a matrix based on Einstein s viscosity model. This is a drop-in technology with no additional equipment needed. The loading is limited by the ability to maintain adequate dispersion. Undispersed materials will plug filtering screens in processing equipment. Generally, the viscosity increases were acceptable, and allowed the filled polymers to still be

  9. High Temperature Millimeter Wave Radiometric and Interferometric Measurements of Slag-Refractory Interaction for Application to Coal Gasifiers

    NASA Astrophysics Data System (ADS)

    McCloy, John S.; Crum, Jarrod V.; Sundaram, S. K.; Slaugh, Ryan; Woskov, Paul P.

    2011-11-01

    Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments such as in slagging coal gasifiers, where sensors have been identified as a key enabling technology need for process optimization. We present a dual-channel MMW heterodyne radiometer with active interferometric capability that allows simultaneous measurements of sample temperature, emissivity, and flow dynamics. Interferometric capability at 137 GHz is supplied via a probe signal originating from a local oscillator allowing monitoring of sample dynamics such as volume expansion and thickness change. This capability has been used to monitor characteristic behavior between refractories and slag such as slag infiltration, slag melting, viscous flow, foaming, and crucible corrosion by the molten slag. These results show the promise of the MMW system for extracting process parameters from operating slagging coal gasifiers, providing valuable information for process efficiency, control, and increased productivity.

  10. Characterizing coal-gasifier slag-refractory interactions

    SciTech Connect

    Rawers, James C.; Bennett, James P.; Kwong, Kyei-Sing

    1999-01-01

    To characterize refractory degradation and loss in commercial coal-gasifier combined cycle power systems, cup-type tests were conducted on high chromium-alumina, sinter-bonded refractories under laboratory conditions designed to simulate commercial operations of temperature, atmosphere, and slag interactions. These tests provided qualitative results from which the slag–refractory interactions can be characterized. These high chromium refractories were generally inert with respect to the coal slag components. However, in this study preliminary findings did show (1) iron ( oxide) in the slag reacted with chrome sesquioxide to produce a Cr–Fe spinel at the slag–refractory interface, and (2) chrome was soluble in the molten slag. Comparison of cup-type test results with data from operating commercial plants suggests that the principal loss of refractory material in a coal-gasifier combustion chamber is chrome dissolution into the slag. Tests are currently underway to determine if minor modifications to the combustion process might increase refractory life.

  11. Utilization of Lightweight Materials Made from Coal Gasificaiton Slags

    SciTech Connect

    Choudhry, V.; Hadley, S.

    1996-12-31

    The integrated gasification combined-cycle (IGCC) coal conversion process has been demonstrated to be a clean, efficient, and environmentally acceptable method of generating power; however, it generates solid waste materials in relatively large quantities. For example, a 400-MW power plant using 4000 tons of 10% ash coal per day may generate over 440 tons/day of solid waste of slag, consisting of vitrified mineral matter and unburned carbon. The disposal of the wastes represents significant costs. Regulatory trends with respect to solid wastes disposal, landfill development costs and public concern make utilization of solid wastes a high-priority issue. As coal gasification technologies find increasing commercial applications for power generation or production of chemical feed stocks, it becomes imperative that slag utilization methods be developed, tested and commercialized in order to offset disposal costs. Praxis is working on a DOE/METC funded project to demonstrate the technical and economic feasibility of making lightweight and ultra-lightweight aggregates from slags left as solid by-products from the coal gasification process. The project objectives are to develop and demonstrate the technology for producing slag-based lightweight aggregates (SLA), to produce 10 tons of SLA products with different unit weights from two slags, to collect operational and emissions data from pilot-scale operations, and to conduct laboratory and commercial scale evaluations of SLA with conventional lightweight and ultra-lightweight aggregates.

  12. Refractory failure in slagging gasifiers

    SciTech Connect

    Bennett, James P.; Kwong, Kyei-Sing

    2004-08-01

    Slagging gasifiers are used to produce chemicals and/or electricity from feedstocks such as coal and/or petroleum coke. A gasifier environment includes pressures from 400 to 1000 psi, temperatures from 1250-1550 C, are cyclic, reducing gases of CO and H2, and molten ash that interacts with the refractory liner materials. The high Cr2O3 refractory liners of gasifiers fail within 3 to 24 months due to slag attack at elevated temperatures. Gasifier users seek materials with increased reliability and service life. The causes of refractory failure and efforts to increase refractory service life are discussed. Mechanisms involving corrosion and slag infiltration/spalling are the main causes of refractory wear. The reduction of slag penetration can reduce hot face lining wear. The performance of high Cr2O3-Al2O3 materials with phosphate additions were evaluated. Phosphate additions were found to have comparable wear and physical properties to materials with no additions, and to have good slag penetration resistance. Field trials in a gasifier are needed to clarify the potential of the materials.

  13. High infrared radiance glass-ceramics obtained from fly ash and titanium slag.

    PubMed

    Wang, Shuming; Liang, Kaiming

    2007-11-01

    A new glass-ceramic was synthesized by crystal growth from a homogenous glass obtained by melting a mixture of fly ash collected from a power plant in Hebei province of China, titanium slag collected from a titanium factory in Sichuan province of China, and MgCO(3) as an additive. According to the measurement results of differential thermal analysis, a thermal treatment of nucleating at 850 degrees C for 2h and crystallizing at 985 degrees C for 1.5h was used to obtain the crystallized glass. X-ray diffraction and scanning electron microscopy measurements showed that the main crystalline phase of this material was iron-ion substituted cordierite, (Mg,Fe)(2)Al(4)Si(5)O(18), which is homogeneously dispersed within the parent glass matrix. The infrared radiance and thermal expansion coefficient of this material have been examined, and the results demonstrate that this glass-ceramic material has potential for application in a wide range of infrared heating and drying materials. PMID:17640707

  14. Synthesis of highly efficient CaO-based, self-stabilizing CO2 sorbents via structure-reforming of steel slag.

    PubMed

    Tian, Sicong; Jiang, Jianguo; Yan, Feng; Li, Kaimin; Chen, Xuejing

    2015-06-16

    Capturing anthropogenic CO2 in a cost-effective and highly efficient manner is one of the most challenging issues faced by scientists today. Herein, we report a novel structure-reforming approach to convert steel slag, a cheap, abundant, and nontoxic calcium-rich industrial waste, as the only feedstock into superior CaO-based, self-stabilizing CO2 sorbents. The CO2 capture capacity of all the steel slag-derived sorbents was improved more than 10-fold compared to the raw slag, with the maximum uptake of CO2 achieving at 0.50 gCO2 gsorbent(-1). Additionally, the initial steel slag-derived sorbent could retain 0.25 gCO2 gsorbent(-1), that is, a decay rate of only 12% over 30 carbonation-calcination cycles, the excellent self-stabilizing property allowed it to significantly outperform conventional CaO, and match with most of the existing synthetic CaO-based sorbents. A synergistic effect that facilitated CO2 capture by CaO-based sorbents was clearly recognized when Mg and Al, the most common elements in steel slag, coexisted with CaO in the forms of MgO and Al2O3, respectively. During the calcium looping process, MgO served as a well spacer to increase the porosity of sorbents together with Al2O3 serving as a durable stabilizer to coresist the sintering of CaCO3 grains at high temperatures. PMID:25961319

  15. Modeling of a coal-fired slagging combustor: Development of a slag submodel

    SciTech Connect

    Wang, X.H.; Zhao, D.Q.; He, L.B.; Jiang, L.Q.; He, Q.; Chen, Y.

    2007-05-15

    In a slagging combustor or furnace, the high combustion temperature makes the molten slag layer cover the wall and capture the particles. If these particles contain combustible matter, they will continue to burn on the running slag. As a result, the total amount of ash deposition will be much greater than that in dry-wall combustors and the total heat flux through the deposition surface will change greatly. Considering the limitations of existing simulation methods for slagging combustion, this paper introduces a new wall burning model and slag flow model from the analysis of particle deposition phenomena. Combined with a conventional combustion simulation program, the total computational frame is introduced. From comparisons of simulation results from several kinds of methods with experimental data, the conclusion is drawn that the conventional simulation methods are not very suitable for slagging combustion and the wall burning mechanism should be considered more thoroughly. (author)

  16. Separation of Iron Phase and P-Bearing Slag Phase from Gaseous-Reduced, High-Phosphorous Oolitic Iron Ore at 1473 K (1200 °C) by Super Gravity

    NASA Astrophysics Data System (ADS)

    Gao, Jintao; Zhong, Yiwei; Guo, Lei; Guo, Zhancheng

    2016-04-01

    In situ observation on the morphology evolution and phosphorous migration of gaseous-reduced, high-phosphorous oolitic iron ore during the melting process was carried out with a high-temperature confocal scanning laser microscope. The results showed that 1473 K (1200 °C) was a critical temperature at which the gangue minerals started to form into the slag phase while the iron grains remained in a solid state; in addition, the phosphorus remained in the slag phase. Since the separation of iron grains and P-bearing slag was not achieved at the low temperature under the conventional conditions, separate experiments of the iron phase and the P-bearing slag phase from gaseous-reduced, high-phosphorous oolitic iron ore at 1473 K (1200 °C) by super gravity were carried out in this study. Based on the iron-slag separation by super gravity, phosphorus was removed effectively from the iron phase at the temperature below the melting point of iron. Iron grains moved along the super-gravity direction, joined, and concentrated as the iron phase on the filter, whereas the slag phase containing apatite crystals broke through the barriers of the iron grains and went through the filter. Consequently, increasing the gravity coefficient was definitely beneficial for the separation of the P-bearing slag phase from the iron phase. With the gravity coefficient of G = 1200, the mass fractions of separated slag and iron phases were close to their respective theoretical values, and the mass fraction of MFe in the separated iron phase was up to 98.09 wt pct and that of P was decreased to 0.083 wt pct. The recovery of MFe in the iron phase and that of P in the slag phase were up to 99.19 and 95.83 pct, respectively.

  17. COAL SLAGGING AND REACTIVITY TESTING

    SciTech Connect

    Donald P. McCollor; Kurt E. Eylands; Jason D. Laumb

    2003-10-01

    carbon as well as slagging. A second phase of the project involved advanced analysis of the baseline coal along with an Australian coal fired at the plant. These analysis results were used in equilibrium thermodynamic modeling along with a coal quality model developed by the EERC to assess slagging, fouling, and opacity for the coals. Bench-scale carbon conversion testing was performed in a drop-tube furnace to assess the reactivity of the coals. The Australian coal had a higher mineral content with significantly more clay minerals present than the baseline coal. The presence of these clay minerals, which tend to melt at relatively low temperatures, indicated a higher potential for problematic slagging than the baseline coal. However, the pyritic minerals, comprising over 25% of the baseline mineral content, may form sticky iron sulfides, leading to severe slagging in the burner region if local areas with reducing conditions exist. Modeling results indicated that neither would present significant fouling problems. The Australian coal was expected to show slagging behavior much more severe than the baseline coal except at very high furnace temperatures. However, the baseline coal was predicted to exhibit opacity problems, as well as have a higher potential for problematic calcium sulfate-based low-temperature fouling. The baseline coal had a somewhat higher reactivity than the Australian coal, which was consistent with both the lower average activation energy for the baseline coal and the greater carbon conversion at a given temperature and residence time. The activation energy of the baseline coal showed some effect of oxygen on the activation energy, with E{sub a} increasing at the lower oxygen concentration, but may be due to the scatter in the baseline coal kinetic values at the higher oxygen level tested.

  18. A Brief Review of Viscosity Models for Slag in Coal Gasification

    SciTech Connect

    Massoudi, Mehrdad; Wang, Ping

    2011-11-01

    , especially in high-temperature environments need to be understood and properly modeled. The viscosity of slag and the thermal conductivity of ash deposits are among two of the most important constitutive parameters that need to be studied. The accurate formulation or representations of the (transport) properties of coal (and biomass for co-firing cases) present a special challenge of modeling efforts in computational fluid dynamics applications. In this report, we first provide a brief review of the various approaches taken by different researchers in formulating or obtaining a slag viscosity model. In general, these models are based on experiments. Since slag behaves as a non-linear fluid, we discuss the constitutive modeling of slag and the important parameters that must be studied.

  19. Phosphorus partitioning and recovery of low-phosphorus iron-rich compounds through physical separation of Linz-Donawitz slag

    NASA Astrophysics Data System (ADS)

    Makhija, Dilip; Rath, Rajendra Kumar; Chakravarty, Kaushik; Patra, Abhay Shankar; Mukherjee, Asim Kumar; Dubey, Akhilesh Kumar

    2016-07-01

    The Linz-Donawitz (LD) steelmaking process produces LD slag at a rate of about 125 kg/t. After metallic scrap recovery, the non-metallic LD slag is rejected because its physical/chemical properties are unsuitable for recycling. X-ray diffraction (XRD) studies have indicated that non-metallic LD slag contains a substantial quantity of mineral phases such as di- and tricalcium silicates. The availability of these mineral phases indicates that LD slag can be recycled by iron (Fe)-ore sintering. However, the presence of 1.2wt% phosphorus (P) in the slag renders the material unsuitable for sintering operations. Electron probe microscopic analysis (EPMA) studies indicated concentration of phosphorus in dicalcium silicate phase as calcium phosphate. The Fe-bearing phases (i.e., wustite and dicalcium ferrite) showed comparatively lower concentrations of P compared with other phases in the slag. Attempts were made to lower the P content of LD slag by adopting various beneficiation techniques. Dry high-intensity magnetic separation and jigging were performed on as-received samples with particle sizes of 6 and 3 mm. Spiral separation was conducted using samples ground to sizes of less than 1 and 0.5 mm. Among these studies, grinding to 0.5 mm followed by spiral concentration demonstrated the best results, yielding a concentrate with about 0.75wt% P and 45wt% Fe.

  20. A Comparison Study of the Oxygen-Rich Side Blow Furnace and the Oxygen-Rich Bottom Blow Furnace for Liquid High Lead Slag Reduction

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Hao, Zhandong; Yang, Tianzu; Liu, Weifeng; Zhang, Duchao; Zhang, Li; Bin, Shu; Bin, Wanda

    2015-05-01

    This work investigates the characteristics of the oxygen-rich side blow furnace (OSBF) and the oxygen-rich bottom blow furnace (OBBF) as the reductive smelting reactor for molten high lead slag. The slags were collected from different sampling points of these furnaces during a regular high lead slag reduction process and analyzed. It is disclosed that lead content of the melt in the OSBF shows dramatic fluctuations, while melt from different sampling points of the furnace behave similarly, exhibiting the characteristics of batch reactor. An obvious axial lead content gradient is detected in the OBBF, showing the characteristics of a plug flow reactor. The industrial performances of these furnaces are also compared. The results indicate that 1.38% higher lead recovery can be achieved by using the OSBF instead of the OBBF. Unit energy consumptions of the OBBF-OSBF and OBBF-OBBF processes can be reduced to 230 kgce/ t crude lead, which is 70 kgce/ t crude lead less than that of the tradition Shuikoushan (SKS) process.

  1. Molten Slag Would Boost Coal Conversion

    NASA Technical Reports Server (NTRS)

    Ferrall, J. F.

    1984-01-01

    Reactor increases residence time of uncovered char. Near-100percent carbon conversion achievable in reactor incorporating moltenslag bath. Slag maintains unconverted carbon impinging on surface at high temperatures for longer period of time, enhancing conversion.

  2. Semi lightweight concretes produced by volcanic slags

    SciTech Connect

    Topcu, I.B.

    1997-01-01

    The properties of the semi-lightweight concretes produced by using volcanic slags as coarse aggregate were investigated. The volcanic slags were brought from the quarry crushed and then classified according to their aggregate sizes of 0--8, 0--16, 0--31.5, 4--8, and 8--16 mm. The concrete series of five different volcanic slag sizes were produced by addition of a specific cement paste in volume fractions of 0.15, 0.30, 0.45 and 0.60. The cubic, cylindrical and prismatic specimens were made from each of the concrete series. The physical and mechanical properties of the concrete series were determined by conducting unit weight, slump, ultrasound velocity, Schmidt hardness, cylindrical and cubic compressive, bending and splitting tensile strength tests. The results indicated that the volcanic slags can be safely used in the production of semi lightweight concrete.

  3. Pulverized coal firing of aluminum melting furnaces. Final report. [Sulfide capacity of various slags in given temperature range

    SciTech Connect

    Stewart, D.L. Jr.; Dastolfo, L.E. Jr.; DeYoung, D.H.

    1984-04-01

    Significant progress has been achieved in the development of a desulfurizing coal combustion process by the Aluminum Company of America (Alcoa) in a research program funded by the United States Department of Energy. Conceptually, high sulfur coal is burned with additives in a staged cyclone combustor, such that sufficient sulfur to obviate products of combustion (POC) scrubbing is retained in the slag by-product. Bench scale studies conducted during the program have shown that 70% of the sulfur (2.65% sulfur coal) reports to the slag at equilibrium through a 25% addition of iron ore to the coal. Results obtained correlate with published data for similar slag at higher temperatures. In pilot scale combustion tests, equilibrium levels of coal sulfur were retained by the slag (11 to 14%). Equilibrium sulfur capture was limited by low particulate retention and operating temperature higher than optimal. Cost estimates for implementation of the process are included in this report. 28 references, 39 figures, 58 tables.

  4. Understanding Slag Freeze Linings

    NASA Astrophysics Data System (ADS)

    Fallah-Mehrjardi, Ata; Hayes, Peter C.; Jak, Evgueni

    2014-09-01

    Slag freeze linings, the formation of protective deposit layers on the inner walls of furnaces and reactors, are increasingly used in industrial pyrometallurgical processes to ensure that furnace integrity is maintained in these aggressive, high-temperature environments. Most previous studies of freeze-linings have analyzed the formation of slag deposits based solely on heat transfer considerations. These thermal models have assumed that the interface between the stationary frozen layer and the agitated molten bath at steady-state deposit thickness consists of the primary phase, which stays in contact with the bulk liquid at the liquidus temperature. Recent experimental studies, however, have clearly demonstrated that the temperature of the deposit/liquid bath interface can be lower than the liquidus temperature of the bulk liquid. A conceptual framework has been proposed to explain the observations and the factors influencing the microstructure and the temperature of the interface at steady-state conditions. The observations are consistent with a dynamic steady state that is a balance between (I) the rate of nucleation and growth of solids on detached crystals in a subliquidus layer as this fluid material moves toward the stagnant deposit interface and (II) the dissolution of these detached crystals as they are transported away from the interface by turbulent eddies. It is argued that the assumption that the interface temperature is the liquidus of the bulk material represents only a limiting condition, and that the interface temperature can be between T liquidus and T solidus depending on the process conditions and bath chemistry. These findings have implications for the modeling approach and boundary conditions required to accurately describe these systems. They also indicate the opportunity to integrate considerations of heat and mass flows with the selection of melt chemistries in the design of future high temperature industrial reactors.

  5. Effect of Temperature Gradient on Industrial Coal Slag Infiltration into Porous Refractory Materials in Slagging Gasifiers

    SciTech Connect

    Kaneko, Tetsuya Kenneth; Bennett, James P.; Dridhar, Seetharaman

    2011-12-01

    Infiltration characteristics of industrial coal slag into alumina (Al{sub 2}O{sub 3}) refractory material with a temperature gradient induced along the slag's penetration direction are compared to those obtained under near-isothermal conditions. Experiments were conducted with a hot-face temperature of 1450°C and a CO/CO{sub 2} ratio of 1.8, which corresponds to an oxygen partial pressure of ~10{sup −8} atm. The refractory under the near-isothermal temperature profile, with higher average temperatures, demonstrated a greater penetration depth than its counterpart that was under the steeper temperature gradient. Slag that did not infiltrate into the refractory due to the induced temperature gradient, pooled and solidified on the top of the sample. Within the pool, a conglomerated mass of troilite (FeS) formed separately from the surrounding slag. Microscopy of the cross-sectioned infiltrated refractories revealed that the slag preferentially corroded the matrix regions closer to the top surface. Furthermore, the formation of a thick layer of hercynite (FeAl{sub 2}O{sub 4}) at the top of refractory/slag interface significantly depleted the slag of its iron-oxide content with respect to its virgin composition. A qualitative description of the penetration process is provided in this article.

  6. Polyethylene nanofibres with very high thermal conductivities.

    PubMed

    Shen, Sheng; Henry, Asegun; Tong, Jonathan; Zheng, Ruiting; Chen, Gang

    2010-04-01

    Bulk polymers are generally regarded as thermal insulators, and typically have thermal conductivities on the order of 0.1 W m(-1) K(-1). However, recent work suggests that individual chains of polyethylene--the simplest and most widely used polymer--can have extremely high thermal conductivity. Practical applications of these polymers may also require that the individual chains form fibres or films. Here, we report the fabrication of high-quality ultra-drawn polyethylene nanofibres with diameters of 50-500 nm and lengths up to tens of millimetres. The thermal conductivity of the nanofibres was found to be as high as approximately 104 W m(-1) K(-1), which is larger than the conductivities of about half of the pure metals. The high thermal conductivity is attributed to the restructuring of the polymer chains by stretching, which improves the fibre quality toward an 'ideal' single crystalline fibre. Such thermally conductive polymers are potentially useful as heat spreaders and could supplement conventional metallic heat-transfer materials, which are used in applications such as solar hot-water collectors, heat exchangers and electronic packaging. PMID:20208547

  7. High quality transparent conducting oxide thin films

    DOEpatents

    Gessert, Timothy A.; Duenow, Joel N.; Barnes, Teresa; Coutts, Timothy J.

    2012-08-28

    A transparent conducting oxide (TCO) film comprising: a TCO layer, and dopants selected from the elements consisting of Vanadium, Molybdenum, Tantalum, Niobium, Antimony, Titanium, Zirconium, and Hafnium, wherein the elements are n-type dopants; and wherein the transparent conducting oxide is characterized by an improved electron mobility of about 42 cm.sup.2/V-sec while simultaneously maintaining a high carrier density of .about.4.4e.times.10.sup.20 cm.sup.-3.

  8. Steel slag carbonation in a flow-through reactor system: the role of fluid-flux.

    PubMed

    Berryman, Eleanor J; Williams-Jones, Anthony E; Migdisov, Artashes A

    2015-01-01

    Steel production is currently the largest industrial source of atmospheric CO2. As annual steel production continues to grow, the need for effective methods of reducing its carbon footprint increases correspondingly. The carbonation of the calcium-bearing phases in steel slag generated during basic oxygen furnace (BOF) steel production, in particular its major constituent, larnite {Ca2SiO4}, which is a structural analogue of olivine {(MgFe)2SiO4}, the main mineral subjected to natural carbonation in peridotites, offers the potential to offset some of these emissions. However, the controls on the nature and efficiency of steel slag carbonation are yet to be completely understood. Experiments were conducted exposing steel slag grains to a CO2-H2O mixture in both batch and flow-through reactors to investigate the impact of temperature, fluid flux, and reaction gradient on the dissolution and carbonation of steel slag. The results of these experiments show that dissolution and carbonation of BOF steel slag are more efficient in a flow-through reactor than in the batch reactors used in most previous studies. Moreover, they show that fluid flux needs to be optimized in addition to grain size, pressure, and temperature, in order to maximize the efficiency of carbonation. Based on these results, a two-stage reactor consisting of a high and a low fluid-flux chamber is proposed for CO2 sequestration by steel slag carbonation, allowing dissolution of the slag and precipitation of calcium carbonate to occur within a single flow-through system. PMID:25597686

  9. Crystallization phenomena in slags

    NASA Astrophysics Data System (ADS)

    Orrling, Carl Folke

    2000-09-01

    The crystallization of the mold slag affects both the heat transfer and the lubrication between the mold and the strand in continuous casting of steel. In order for mold slag design to become an engineering science rather than an empirical exercise, a fundamental understanding of the melting and solidification behavior of a slag must be developed. Thus it is necessary to be able to quantify the phenomena that occur under the thermal conditions that are found in the mold of a continuous caster. The double hot thermocouple technique (DHTT) and the Confocal Laser Scanning Microscope used in this study are two novel techniques for investigating melting and solidification phenomena of transparent slags. Results from these techniques are useful in defining the phenomena that occur when the slag film infiltrates between the mold and the shell of the casting. TTT diagrams were obtained for various slags and indicated that the onset of crystallization is a function of cooling rate and slag chemistry. Crystal morphology was found to be dependent upon the experimental temperature and four different morphologies were classified based upon the degree of melt undercooling. Continuous cooling experiments were carried out to develop CCT diagrams and it was found that the amount and appearance of the crystalline fraction greatly depends on the cooling conditions. The DHTT can also be used to mimic the cooling profile encountered by the slag in the mold of a continuous caster. In this differential cooling mode (DCT), it was found that the details of the cooling rate determine the actual response of the slag to a thermal gradient and small changes can lead to significantly different results. Crystal growth rates were measured and found to be in the range between 0.11 mum/s to 11.73 mum/s depending on temperature and slag chemistry. Alumina particles were found to be effective innoculants in oxide melts reducing the incubation time for the onset of crystallization and also extending

  10. Triple-activated blast furnace slag

    SciTech Connect

    Clarke, W.J.

    1995-12-31

    The current shortage of portland cement in the world will require the use of Ground Granulated Blast Furnace Slag (GGBFS) to fill demands in many industrialized countries. Therefore, an extensive series of triple-activated slag experiments have been undertaken to optimize an economical combination of mechanical properties for alkali-activated slags. Na{sub 2}OSiO{sub 2} (N Grade), Ca(OH){sub 2}, H{sub 2}O and Na{sub 2}CO{sub 3} have been added as activators in 5 to 10, 0 to 5 and 0 to 5 weight percentages of water and slag in a mix with a water:cement ratio of 1:1. Silica Fume and Sika 10 superplasticizer have been added as 1 and 10 weight percent of slag. Set times, initial hardening times and compressive strengths at percentages of the mix to identify more refined formulations. Finally, the resulting aggregate to develop a triple-activated slag formulation with the ultimate objective of contributing toward satisfying the world shortage of high performance concrete.

  11. Electrical conductivity of chlorite at high pressures and high temperatures

    NASA Astrophysics Data System (ADS)

    Eymard, I.; Mibe, K.; Reynard, B.

    2012-12-01

    In the mantle wedge of subduction zones, high electrical-conductivity bodies have been observed. In order to understand the cause of high-conductivity body in subduction zones, we measured the electrical conductivity of polycrystalline chlorite, at pressures from 2 to 4 GPa and at high temperatures up to 850K using complex impedance spectroscopy in a multi-anvil high-pressure apparatus. The electrical conductivity increased slightly with increasing pressure. The obtained electrical conductivity values are higher than serpentine and talc (Reynard et al., 2011; Guo et al., 2011) and are slightly lower than brucite (Fujita et al., 2007). Although the obtained values are higher compared to serpentine, the presence of chlorite alone is not high enough to explain high-conductivity bodies in subduction-zones. Instead, the presence of some amount of saline fluids is inferred.

  12. Phosphorus removal by steel slag filters: modeling dissolution and precipitation kinetics to predict longevity.

    PubMed

    Claveau-Mallet, Dominique; Courcelles, Benoît; Comeau, Yves

    2014-07-01

    This article presents an original numerical model suitable for longevity prediction of alkaline steel slag filters used for phosphorus removal. The model includes kinetic rates for slag dissolution, hydroxyapatite and monetite precipitation and for the transformation of monetite into hydroxyapatite. The model includes equations for slag exhaustion. Short-term batch tests using slag and continuous pH monitoring were conducted. The model parameters were calibrated on these batch tests and experimental results were correctly reproduced. The model was then transposed to long-term continuous flow simulations using the software PHREEQC. Column simulations were run to test the effect of influent P concentration, influent inorganic C concentration and void hydraulic retention time on filter longevity and P retention capacity. High influent concentration of P and inorganic C, and low hydraulic retention time of voids reduced the filter longevity. The model provided realistic P breakthrough at the column outlet. Results were comparable to previous column experiments with the same slag regarding longevity and P retention capacity. A filter design methodology based on a simple batch test and numerical simulations is proposed. PMID:24871615

  13. An Innovative High Thermal Conductivity Fuel Design

    SciTech Connect

    PI: James S. Tulenko; Co-PI: Ronald H. Baney,

    2007-10-14

    Uranium dioxide (UO2) is the most common fuel material in commercial nuclear power reactors. UO2 has the advantages of a high melting point, good high-temperature stability, good chemical compatibility with cladding and coolant, and resistance to radiation. The main disadvantage of UO2 is its low thermal conductivity. During a reactor’s operation, because the thermal conductivity of UO2 is very low, for example, about 2.8 W/m-K at 1000 oC [1], there is a large temperature gradient in the UO2 fuel pellet, causing a very high centerline temperature, and introducing thermal stresses, which lead to extensive fuel pellet cracking. These cracks will add to the release of fission product gases after high burnup. The high fuel operating temperature also increases the rate of fission gas release and the fuel pellet swelling caused by fission gases bubbles. The amount of fission gas release and fuel swelling limits the life time of UO2 fuel in reactor. In addition, the high centerline temperature and large temperature gradient in the fuel pellet, leading to a large amount of stored heat, increase the Zircaloy cladding temperature in a lost of coolant accident (LOCA). The rate of Zircaloy-water reaction becomes significant at the temperature above 1200 oC [2]. The ZrO2 layer generated on the surface of the Zircaloy cladding will affect the heat conduction, and will cause a Zircaloy cladding rupture. The objective of this research is to increase the thermal conductivity of UO2, while not affecting the neutronic property of UO2 significantly. The concept to accomplish this goal is to incorporate another material with high thermal conductivity into the UO2 pellet. Silicon carbide (SiC) is a good candidate, because the thermal conductivity of single crystal SiC is 60 times higher than that of UO2 at room temperature and 30 times higher at 800 oC [3]. Silicon carbide also has the properties of low thermal neutron absorption cross section, high melting point, good chemical

  14. Making IGCC slag valuable

    SciTech Connect

    Wicker, K.

    2005-12-01

    All indications are that integrated gasification combined-cycle (IGCC) technology will play a major role in tomorrow's generation industry. But before it does, some by-products of the process must be dealt with, for example unburned carbon that can make IGCC slag worthless. Charah Inc.'s processing system, used at Tampa Electric's Polk Station for years, segregates the slag's constituents by size, producing fuel and building materials. 3 figs.

  15. Energy effective approach for activation of metallurgical slag

    NASA Astrophysics Data System (ADS)

    Mazov, I. N.; Khaydarov, B. B.; Mamulat, S. L.; Suvorov, D. S.; Saltikova, Y. S.; Yudin, A. G.; Kuznetsov, D. V.

    2016-01-01

    The paper presents results of investigation of the process of mechanical activation of metallurgical slag using different approaches - ball milling and electromagnetic vortex apparatus. Particle size distribution and structure of mechanically activated slag samples were investigated, as well as energetic parameters of the activation process. It was shown that electromagnetic vortex activation is more energy effective and allows to produce microscale milled slag-based concrete using very short treatment time. Activated slag materials can be used as clinker-free cement in civilian and road construction, providing ecology-friendly technology and recycling of high-tonnage industrial waste.

  16. Electrochemical corrosion of iron-magnesium-alumina spinel (FMAS) in molten potassium salts and coal slag

    SciTech Connect

    Marchant, D.D.; Griffin, C.W.; Bates, J.L.

    1981-01-01

    Iron, magnesium-alumina spinel (FMAS) (0.25 Fe/sub 3/O/sub 4/ . 0.75 MgAl/sub 2/O/sub 4/) has been considered for use as an electrode in magnetohydrodynamic (MHD) generator channels. Predominantly an electronic conductor, FMAS has adequate electrical conductivity (>1 S/m) above 520/sup 0/K. In addition, FMAS can be easily fabricated into a form and sintered in air to >90% theoretical density and has a melting point of 2124 +- 20/sup 0/K. Laboratory tests to measure both the electrochemical and chemical corrosion of FMAS in molten K/sub 2/CO/sub 3/, K/sub 2/SO/sub 4/ and coal slags were developed at the Pacific Northwest Laboratory to evaluate the relative corrosion of FMAS. Under isothermal conditions, a direct electric current was passed between an anode and a cathode through a molten electrolyte. The molten coal slags were synthetic high-calcium, low-iron Montana Rosebud and low-calcium, high-iron Illinois No. 6. Evaluations of electrochemical corrosion were made as functions of current density, temperature, and slag composition. These results were compared to those of FMAS tested without electric current. The corrosion rates and reaction products were investigated by optical microscopy and scanning electron microscopy. Overall, FMAS has too-high an electrochemical corrosion rate to be considered as MHD electrodes in Montana Rosebud coal slag or in systems where only molten potassium salts are present. However, FMAS may be considered for use in high-iron coal slags although the corrosion rates are still quite high even in these slags.

  17. High H- ionic conductivity in barium hydride

    NASA Astrophysics Data System (ADS)

    Verbraeken, Maarten C.; Cheung, Chaksum; Suard, Emmanuelle; Irvine, John T. S.

    2015-01-01

    With hydrogen being seen as a key renewable energy vector, the search for materials exhibiting fast hydrogen transport becomes ever more important. Not only do hydrogen storage materials require high mobility of hydrogen in the solid state, but the efficiency of electrochemical devices is also largely determined by fast ionic transport. Although the heavy alkaline-earth hydrides are of limited interest for their hydrogen storage potential, owing to low gravimetric densities, their ionic nature may prove useful in new electrochemical applications, especially as an ionically conducting electrolyte material. Here we show that barium hydride shows fast pure ionic transport of hydride ions (H-) in the high-temperature, high-symmetry phase. Although some conductivity studies have been reported on related materials previously, the nature of the charge carriers has not been determined. BaH2 gives rise to hydride ion conductivity of 0.2 S cm-1 at 630 °C. This is an order of magnitude larger than that of state-of-the-art proton-conducting perovskites or oxide ion conductors at this temperature. These results suggest that the alkaline-earth hydrides form an important new family of materials, with potential use in a number of applications, such as separation membranes, electrochemical reactors and so on.

  18. Processing fine stainless-steel slag using spiral concentration.

    PubMed

    Wolfe, Eric R; Klima, Mark S

    2008-04-01

    In this study, the effectiveness of spiral concentration to process a fine (-1 mm) stainless-steel slag was evaluated. Specifically, testing was conducted to determine the feasibility of producing a high metal content stainless steel product and a low metal content aggregate product. This involved investigating a key operating variable for both five-and seven-turn spiral concentrators. The raw slag and spiral products were characterized to determine their respective size and metal distributions. Separation testing was carried out using the two full-scale spiral concentrators to evaluate the effects of feed solids concentration on spiral performance at solids feed rates ranging from 15 to 30 kg/min. The results indicated that under certain conditions, a high-quality metal fraction could be produced. For example, using the five-turn spiral, a product containing 95% metal was obtained at a low metal recovery. Both spirals were ineffective at concentrating the aggregate fraction. Overall, the feed solids concentration did not significantly affect the quality or recoveries of the products, particularly for feed solids concentrations less than 35% by weight. In order to improve the metal recoveries and to produce a low-metal aggregate material, reprocessing of the product streams and/or additional liberation of the raw slag would be required. PMID:18324536

  19. Other Oxides Pre-removed from Bangka Tin Slag to Produce a High Grade Tantalum and Niobium Oxides Concentrate

    NASA Astrophysics Data System (ADS)

    Permana, S.; Soedarsono, J. W.; Rustandi, A.; Maksum, A.

    2016-05-01

    Indonesia, as the second largest tin producer in the world, has a byproduct from the production of tin. This byproduct is in the forms of tin slag containing tantalum pentoxide (Ta2O5) and niobium pentoxide (Nb2O5). This study focuses on the recovery of tantalum pentoxide and niobium pentoxide from the tin slag. In the process, one part of the tin slag sample was sieved only (BTS), and the other was roasted at 900°C, water quenched and then sieved (BTS-RQS). Samples BTS and BTS-RQS were characterized by thermo gravimetric analysis (TGA) and X-ray flourence (XRF). One part of BTS-RQS sample was dissolved in hydrofluoric acid (HF) and the other was dissolved in hydrochloric acid (HCl), washed with distilled water, then dissolved into sodium hydroxide (NaOH). Each sample was characterized by using XRF. The BTS sample produced the highest recovery of 0.3807 and 0.6978% for Ta2O5 and Nb2O5, respectively, from the particle size of -1.00+0.71 and a fraction of 47.29%, while BTS-RQS produced the highest recovery of 0.3931 and 0.8994% for Ta2O5 and Nb2O5, respectively, on the particle size of -0.71+0350 and a fraction of 21%. BTS-RQS, dissolved with 8% hydro fluoride acid, yields tantalum pentoxide and niobium pentoxide with a ratio of 2.01 and 2.09, respectively. For the sample BTS-RQS dissolve first with 6M hydrochloric acid, washed with distilled water, then dissolved with sodium hydroxide 10M, the yield ratios are 1.60 and 1.84 for tantalum pentoxide and niobium pentoxide, respectively. In this study, it is found that the dissolution by using hydrofluoric acid 8% yields the best ratio.

  20. On the high conductivity of nonconjugated polymers

    SciTech Connect

    Lachinov, A. N. Kornilov, V. M.; Zagurenko, T. G.; Zherebov, A. Yu.

    2006-04-15

    The mechanism of charge transfer in a metal-electroactive polymer-metal structure has been experimentally studied near the threshold of the uniaxial-pressure-induced transition into a high-conductivity state in the polymer. The dynamics of the I-V curve is investigated as a function of the applied pressure. The data obtained are analyzed in terms of the model of injection currents using the concepts of possible scanning of a quasi-Fermi level near an injection level. Our estimates suggest that a narrow band made of deep trap states located near the Fermi level forms in the polymer film in the pretransition pressure range. In the immediate vicinity of the transition range, a narrow band of coherent charge transfer appears from these states; this band can be responsible for the high metal-type conductivity of thin polymer films, which has been repeatedly observed by many researchers.

  1. Highly Conductive Multifunctional Graphene Polycarbonate Nanocomposites

    NASA Technical Reports Server (NTRS)

    Yoonessi, Mitra; Gaier, James R.

    2010-01-01

    Graphene nanosheet bisphenol A polycarbonate nanocomposites (0.027 2.2 vol %) prepared by both emulsion mixing and solution blending methods, followed by compression molding at 287 C, exhibited dc electrical percolation threshold of approx.0.14 and approx.0.38 vol %, respectively. The conductivities of 2.2 vol % graphene nanocomposites were 0.512 and 0.226 S/cm for emulsion and solution mixing. The 1.1 and 2.2 vol % graphene nanocomposites exhibited frequency-independent behavior. Inherent conductivity, extremely high aspect ratio, and nanostructure directed assembly of the graphene using PC nanospheres are the main factors for excellent electrical properties of the nanocomposites. Dynamic tensile moduli of nanocomposites increased with increasing graphene in the nanocomposite. The glass transition temperatures were decreased with increasing graphene for the emulsion series. High-resolution electron microscopy (HR-TEM) and small-angle neutron scattering (SANS) showed isolated graphene with no connectivity path for insulating nanocomposites and connected nanoparticles for the conductive nanocomposites. A stacked disk model was used to obtain the average particle radius, average number of graphene layers per stack, and stack spacing by simulation of the experimental SANS data. Morphology studies indicated the presence of well-dispersed graphene and small graphene stacking with infusion of polycarbonate within the stacks.

  2. Highly conductive, printable pastes from capillary suspensions

    NASA Astrophysics Data System (ADS)

    Schneider, Monica; Koos, Erin; Willenbacher, Norbert

    2016-08-01

    We have used the capillary suspension phenomenon to design conductive pastes for printed electronic applications, such as front side metallization of solar cells, without non-volatile, organic additives that often deteriorate electrical properties. Adding a small amount of a second, immiscible fluid to a suspension creates a network of liquid bridges between the particles. This capillary force-controlled microstructure allows for tuning the flow behavior in a wide range. Yield stress and low-shear viscosity can be adjusted such that long-term stability is provided by inhibiting sedimentation, and, even more importantly, narrow line widths and high aspect ratios are accessible. These ternary mixtures, called capillary suspensions, exhibit a strong degree of shear thinning that allows for conventional coating or printing equipment to be used. Finally, the secondary fluid, beneficial for stability and processing of the wet paste, completely evaporates during drying and sintering. Thus, we obtained high purity silver and nickel layers with a conductivity two times greater than could be obtained with state-of-the-art, commercial materials. This revolutionary concept can be easily applied to other systems using inorganic or even organic conductive particles and represents a fundamental paradigm change to the formulation of pastes for printed electronics.

  3. Highly conductive, printable pastes from capillary suspensions.

    PubMed

    Schneider, Monica; Koos, Erin; Willenbacher, Norbert

    2016-01-01

    We have used the capillary suspension phenomenon to design conductive pastes for printed electronic applications, such as front side metallization of solar cells, without non-volatile, organic additives that often deteriorate electrical properties. Adding a small amount of a second, immiscible fluid to a suspension creates a network of liquid bridges between the particles. This capillary force-controlled microstructure allows for tuning the flow behavior in a wide range. Yield stress and low-shear viscosity can be adjusted such that long-term stability is provided by inhibiting sedimentation, and, even more importantly, narrow line widths and high aspect ratios are accessible. These ternary mixtures, called capillary suspensions, exhibit a strong degree of shear thinning that allows for conventional coating or printing equipment to be used. Finally, the secondary fluid, beneficial for stability and processing of the wet paste, completely evaporates during drying and sintering. Thus, we obtained high purity silver and nickel layers with a conductivity two times greater than could be obtained with state-of-the-art, commercial materials. This revolutionary concept can be easily applied to other systems using inorganic or even organic conductive particles and represents a fundamental paradigm change to the formulation of pastes for printed electronics. PMID:27506726

  4. Highly conductive, printable pastes from capillary suspensions

    PubMed Central

    Schneider, Monica; Koos, Erin; Willenbacher, Norbert

    2016-01-01

    We have used the capillary suspension phenomenon to design conductive pastes for printed electronic applications, such as front side metallization of solar cells, without non-volatile, organic additives that often deteriorate electrical properties. Adding a small amount of a second, immiscible fluid to a suspension creates a network of liquid bridges between the particles. This capillary force-controlled microstructure allows for tuning the flow behavior in a wide range. Yield stress and low-shear viscosity can be adjusted such that long-term stability is provided by inhibiting sedimentation, and, even more importantly, narrow line widths and high aspect ratios are accessible. These ternary mixtures, called capillary suspensions, exhibit a strong degree of shear thinning that allows for conventional coating or printing equipment to be used. Finally, the secondary fluid, beneficial for stability and processing of the wet paste, completely evaporates during drying and sintering. Thus, we obtained high purity silver and nickel layers with a conductivity two times greater than could be obtained with state-of-the-art, commercial materials. This revolutionary concept can be easily applied to other systems using inorganic or even organic conductive particles and represents a fundamental paradigm change to the formulation of pastes for printed electronics. PMID:27506726

  5. Highly conductive multifunctional graphene polycarbonate nanocomposites.

    PubMed

    Yoonessi, Mitra; Gaier, James R

    2010-12-28

    Graphene nanosheet-bisphenol A polycarbonate nanocomposites (0.027-2.2 vol %) prepared by both emulsion mixing and solution blending methods, followed by compression molding at 287 °C, exhibited dc electrical percolation threshold of ∼0.14 and ∼0.38 vol %, respectively. The conductivities of 2.2 vol % graphene nanocomposites were 0.512 and 0.226 S/cm for emulsion and solution mixing. The 1.1 and 2.2 vol % graphene nanocomposites exhibited frequency-independent behavior. Inherent conductivity, extremely high aspect ratio, and nanostructure directed assembly of the graphene using PC nanospheres are the main factors for excellent electrical properties of the nanocomposites. Dynamic tensile moduli of nanocomposites increased with increasing graphene in the nanocomposite. The glass transition temperatures were decreased with increasing graphene for the emulsion series. High-resolution electron microscopy (HR-TEM) and small-angle neutron scattering (SANS) showed isolated graphene with no connectivity path for insulating nanocomposites and connected nanoparticles for the conductive nanocomposites. A stacked disk model was used to obtain the average particle radius, average number of graphene layers per stack, and stack spacing by simulation of the experimental SANS data. Morphology studies indicated the presence of well-dispersed graphene and small graphene stacking with infusion of polycarbonate within the stacks. PMID:21082818

  6. Micronutrient availability from steel slag amendment in pine bark substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Steel slag is a byproduct of the steel industry that can be used as a liming agent, but also has a high mineral nutrient content. While micronutrients are present in steel slag, it is not known if the mineral form of the micronutrients would render them available for plant uptake. The objective of...

  7. Predicting slag viscosity from coal ash composition

    SciTech Connect

    Laumb, J.; Benson, S.A.; Katrinak, K.A.; Schwalbe, R.; McCollor, D.P.

    1999-07-01

    Management of slag flow from cyclone-fired utility boilers requires accurate prediction of viscosity. Cyclones tend to build up slag when the cyclone combustion temperature is less than the temperature required to melt and tap the ash from the coal being fired. Cyclone-fired boilers designed for lignite are equipped with predry systems, which remove 6-9% of the moisture from the coal. Cyclones tend to slag when the as-received heating value of the fuel is less than 6350 Btu/lb and T250 (temperature where viscosity equals 250 poise) is greater than 2350 F. The T250 value, as well as the rest of the viscosity-temperature relationship, can be predicted using models based on coal ash composition. The focus of this work is to evaluate several models in terms of their agreement with measured viscosities. Viscosity measurements were made for ten samples, including nine lignite coals and one lignite-derived slag. Model performance is related to the SiO{sub 2}, CaO, and Fe{sub 2}O{sub 3} contents of the slag. The Sage and McIlroy and Kalmanovitch models worked best for high SiO{sub 2} and low Fe{sub 2}O{sub 3} fuels. The Senior model worked best when Fe{sub 2}O{sub 3} content was moderate to high.

  8. Highly anisotropic conductivity in organosiloxane liquid crystals

    NASA Astrophysics Data System (ADS)

    Gardiner, D. J.; Coles, H. J.

    2006-12-01

    In this paper, we present the conductivity and dielectric characterization of three homologous series of smectic A siloxane containing liquid crystals. The materials studied include one monomesogenic series, which consists of a 4-(ω-alkyloxy)-4'-cyanobiphenyl unit terminated by pentamethyldisiloxane, and two bimesogenic series, which consist of twin 4-(ω-alkyloxy)-4'-cyanobiphenyls joined via tetramethyldisiloxane or decamethylpentasiloxane. All of the compounds exhibit wide temperature range enantiotropic smectic A phases; the effect of the siloxane moiety is to suppress nematic morphology even in the short chain homologs. We find that these compounds exhibit a highly anisotropic conductivity: the value perpendicular to the director is to up to 200 times that parallel to the director. For the nonsiloxane analog 4-(ω-octyl)-4'-cyanobiphenyl (8CB), this value is approximately 2. It is also found that the dielectric anisotropy is reduced significantly; a typical value is ˜1 compared to 8.4 for 8CB. We propose that the origin of these unusual properties is in the smectic structure; the microphase separation of the bulky, globular siloxane moieties into liquidlike regions severely inhibits the mobility parallel to the director and across the smectic layers. Further, the inclusion of this unit acts to increase the antiparallel correlations of molecular dipoles in the aromatic and alkyloxy sublayers, reducing the dielectric anisotropy significantly compared to nonsiloxane analogs. The highly anisotropic conductivity suggests that these materials are particularly suitable for application in electro-optic effects which exploit this property, e.g., the bistable electro-optic effect in smectic A liquid crystals.

  9. Highly Conducting Graphite Epoxy Composite Demonstrated

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    1999-01-01

    Weight savings as high as 80 percent could be achieved if graphite polymer composites could replace aluminum in structures such as electromagnetic interference shielding covers and grounding planes. This could result in significant cost savings, especially for the mobile electronics found in spacecraft, aircraft, automobiles, and hand-held consumer electronics. However, such composites had not yet been fabricated with conductivity sufficient to enable these applications. To address this lack, a partnership of the NASA Lewis Research Center, Manchester College, and Applied Sciences, Inc., fabricated nonmetallic composites with unprecedented electrical conductivity. For these composites, heat-treated, vapor-grown graphite fibers were selected which have a resistivity of about 80 mW-cm, more than 20 times more conductive than typical carbon fibers. These fibers were then intercalated with iodine bromide (IBr). Intercalation is the insertion of guest atoms or molecules between the carbon planes of the graphite fibers. Since the carbon planes are not highly distorted in the process, intercalation has little effect on mechanical and thermal properties. Intercalation does, however, lower the carbon fiber resistivity to less than 10 mW-cm, which is comparable to that of metal fibers. Scaleup of the reaction was required since the initial intercalation experiments would be carried out on 20-mg quantities of fibers, and tens of grams of intercalated fibers would be needed to fabricate even small demonstration composites. The reaction was first optimized through a time and temperature study that yielded fibers with a resistivity of 8.7 2 mW-cm when exposed to IBr vapor at 114 C for 24 hours. Stability studies indicated that the intercalated fibers rapidly lost their conductivity when exposed to temperatures as low as 40 C in air. They were not, however, susceptible to degradation by water vapor in the manner of most graphite intercalation compounds. The 1000-fold scaleup

  10. High frequency stimulation can block axonal conduction.

    PubMed

    Jensen, Alicia L; Durand, Dominique M

    2009-11-01

    High frequency stimulation (HFS) is used to control abnormal neuronal activity associated with movement, seizure, and psychiatric disorders. Yet, the mechanisms of its therapeutic action are not known. Although experimental results have shown that HFS suppresses somatic activity, other data has suggested that HFS could generate excitation of axons. Moreover it is unclear what effect the stimulation has on tissue surrounding the stimulation electrode. Electrophysiological and computational modeling literature suggests that HFS can drive axons at the stimulus frequency. Therefore, we tested the hypothesis that unlike cell bodies, axons are driven by pulse train HFS. This hypothesis was tested in fibers of the hippocampus both in-vivo and in-vitro. Our results indicate that although electrical stimulation could activate and drive axons at low frequencies (0.5-25 Hz), as the stimulus frequency increased, electrical stimulation failed to continuously excite axonal activity. Fiber tracts were unable to follow extracellular pulse trains above 50 Hz in-vitro and above 125 Hz in-vivo. The number of cycles required for failure was frequency dependent but independent of stimulus amplitude. A novel in-vitro preparation was developed, in which, the alveus was isolated from the remainder of the hippocampus slice. The isolated fiber tract was unable to follow pulse trains above 75 Hz. Reversible conduction block occurred at much higher stimulus amplitudes, with pulse train HFS (>150 Hz) preventing propagation through the site of stimulation. This study shows that pulse train HFS affects axonal activity by: (1) disrupting HFS evoked excitation leading to partial conduction block of activity through the site of HFS; and (2) generating complete conduction block of secondary evoked activity, as HFS amplitude is increased. These results are relevant for the interpretation of the effects of HFS for the control of abnormal neural activity such as epilepsy and Parkinson's disease. PMID

  11. Mechanisms of pyrite oxidation to non-slagging species. Quarterly report, January 1, 1995--March 31, 1995

    SciTech Connect

    Akan-Etuk, A.E.J.; Mitchell, R.E.

    1995-08-01

    This document is the third quarterly status report on a project conducted at the High Temperature Gasdynamics Laboratory at Stanford University, Stanford, California and concerned with enhancing the transformation of iron pyrite to non-slagging species during staged, low-NO{sub x} pulverized coal (P.C.) combustion. The research project is intended to advance PETC`s efforts to improve our technical understanding of the high-temperature chemical and physical processes involved in the utilization of coal. The work focuses on the mechanistic description and rate quantification of the effects of fuel properties and combustion environment on the oxidation of iron pyrite to form the non-slagging species magnetite. The knowledge gained from this work is intended to be incorporated into numerical codes that can be used to formulate anti-slagging strategies involving minimal disturbance of coal combustor performance.

  12. Modeling of Manganese Ferroalloy Slag Properties and Flow During Tapping

    NASA Astrophysics Data System (ADS)

    Muller, Jacques; Zietsman, Johannes Hendrik; Pistorius, Petrus Christiaan

    2015-12-01

    Stable operation of submerged-arc furnaces producing high-carbon ferromanganese (HCFeMn) and silicomanganese (SiMn) requires tapping of consistent amounts of liquid slag and metal. Minimal effort to initiate and sustain tapping at reasonable rates is desired, accommodating fluctuations in especially slag chemical composition and temperature. An analytical model is presented that estimates the tapping rate of the liquid slag-metal mixture as a function of taphole dimensions, coke bed particulate properties, and slag and metal physicochemical properties with dependencies on chemical composition and temperature. This model may be used to evaluate the sensitivity to fluctuations in these parameters, and to determine the influence of converting between HCFeMn and SiMn production. The model was applied to typical HCFeMn and SiMn process conditions, using modeled slag viscosities and densities. Tapping flow rates estimated were comparable to operational data and found to be dependent mostly on slag viscosity. Slag viscosities were generally lower for typical SiMn slags due to the higher temperature used for calculating viscosity. It was predicted that flow through the taphole would mostly develop into laminar flow, with the pressure drop predominantly over the coke bed. Flow rates were found to be more dependent on the taphole diameter than on the taphole length.

  13. Refractory liner materials used in slagging gasifiers

    SciTech Connect

    Bennett, James P.

    2004-09-01

    Refractory liners are used on the working face of entrained flow slagging gasifiers that react coal, petroleum coke, or other carbon feedstock with oxygen and water. The refractory liners protect the gasifier shell from elevated temperatures, corrosive slags, and thermal cycling during gasification. Refractory failure is primarily by two means, corrosive dissolution and spalling. High chrome oxide refractory materials have evolved as the material of choice to line the hot face of gasifiers, yet the performance of these materials does not meet the service requirements of industry. A review of gasifier liner materials, their evolution, issues impacting their performance, and future research direction are discussed.

  14. Effect of Al2O3 Addition on the Precipitated Phase Transformation in Ti-Bearing Blast Furnace Slags

    NASA Astrophysics Data System (ADS)

    Li, Zhongmin; Li, Jinfu; Sun, Yongqi; Seetharaman, Seshadri; Liu, Lili; Wang, Xidong; Zhang, Zuotai

    2016-04-01

    The present paper aims to provide a fundamental understanding on phase change of Ti-enriched crystalline phase induced by Al2O3 addition in Ti-bearing blast furnace slags with different basicities using Single Hot Thermocouple Technique and X-ray Diffraction. The results showed that an increase in the Al2O3 content led to phase change from rutile or perovskite to Mg3Al4Ti8O25 and prompted crystallization of the slags with basicity of 0.60 and 0.75, whereas only CaTiO3 was precipitated at a basicity of 0.95. Both thermodynamic and kinetic analyses were conducted to study the slag crystallization, which would throw light on phase change and enhanced crystallization. To further reveal the relationship with Al2O3 addition on slag structure and crystallization, Fourier transform infrared spectroscopy and magic angle spinning-nuclear magnetic resonance were adopted, with AlO4 tetrahedra and AlO6 octahedra observed in the slag. For slags with the basicity of 0.60 and 0.75, AlO6 octahedron, which was suggested to induce the phase change from TiO2 or CaTiO3 to Mg3Al4Ti8O25, was detected at high Al2O3 content. On the other hand, in slags with the basicity of 0.95, abundant Ca2+ may be connected to TiO6 octahedra, resulting in CaTiO3 formation.

  15. Synthetic Biological Protein Nanowires with High Conductivity.

    PubMed

    Tan, Yang; Adhikari, Ramesh Y; Malvankar, Nikhil S; Pi, Shuang; Ward, Joy E; Woodard, Trevor L; Nevin, Kelly P; Xia, Qiangfei; Tuominen, Mark T; Lovley, Derek R

    2016-09-01

    Genetic modification to add tryptophan to PilA, the monomer for the electrically conductive pili of Geobacter sulfurreducens, yields conductive protein filaments 2000-fold more conductive than the wild-type pili while cutting the diameter in half to 1.5 nm. PMID:27409066

  16. First high-temperature applications of anti-gas migration slag cement and settable oil-mud removal spacers in deep south Texas gas wells

    SciTech Connect

    Sweatman, R.E.; Nahm, J.J.; Loeb, D.A.

    1995-12-31

    Applications of a new slag cement and spacer system have reduced the chance of gas channels forming in the cement column during cement hydration in deep, hot south Texas gas wells. These slag cements were formulated with water and conventional cement additives to prevent gas migration and to improve interfacial bonding to oil-wet surfaces. Oil-mud removal spacer fluids (OMRS) were also specially formulated to remove oily residues and improve water-wetting of the oil-wet surfaces. These OMRS can also be designed to develop compressive strength when cementing operations have been completed. Set slag cement provides a tight gas seal with shear-bond healing capacity, as demonstrated by recently developed HTHP shear-bond strength tests. The previously reported phenomenon of healing or regeneration of slag-mix bonds has been reproduced with slag cement. The rapid development of strength at the top of the long cement column and the improved bonding to oil-wet surfaces were the two major improvements provided by the slag cement. OMRS can clean oil-wet surfaces, and then set once the job has been completed. Laboratory tests and field evaluations based on cement bond logs and pressure tests indicated improved bonding and isolation of the gas zones. Field applications of slag cements and OMRS fluids have led to greater primary and plug cementing successes in south Texas gas wells, and well production economics have improved accordingly.

  17. Characterization of structure and thermophysical properties of three ESR slags

    NASA Astrophysics Data System (ADS)

    Plotkowski, A.; deBarbadillo, J.; Krane, Matthew J. M.

    2016-07-01

    The structure and properties of electroslag remelting (ESR) slags were characterized. Slags samples of three compositions were obtained from industrial remelting processes at Special Metals Corporation and from casting in a laboratory vacuum induction melter. The structure of the slag samples was observed using optical and electron microscopy, and phases were identified and their relative amounts quantified using X-ray diffraction. Laser flash thermal diffusivity, density, and differential scanning calorimetry measurements for specific heat were performed to determine the bulk thermal conductivity of the samples. Sample porosity was measured as a function of depth using a serial sectioning technique, and a onedimensional computational model was developed to estimate the thermal conductivity of the fully dense slags. These results are discussed in context with previous studies, and opportunities for future research are identified. AFRL Case Number: 88ABW-2015-1871.

  18. High mobility annealing of Transparent Conductive Oxides

    NASA Astrophysics Data System (ADS)

    Warzecha, M.; Owen, J. I.; Wimmer, M.; Ruske, F.; Hotovy, J.; Hüpkes, J.

    2012-04-01

    To improve electrical properties a high temperature annealing treatment was applied to several transparent conductive oxides (TCO), namely tin doped indium oxide (ITO), Ga- or Al- doped ZnO (ZnO:Al/Ga), ion beam assisted deposited (IBAD) ZnO:Ga and Ga doped zinc magnesium oxide (ZnMgO:Ga). All these films were grown by magnetron sputtering. During the annealing process all TCO films were capped with 50 nm of amorphous silicon in order to protect the films from environmental impact. Increase in mobility up to 72 cm2/Vs and low resistivity of 1.6 × 10-4 Ωcm was achieved for ZnO:Al after annealing at 650°C for 24 h. Independent of the deposition conditions and doping or alloying material almost all ZnO based films show a consistent improvement in mobility. Also for ITO films a decrease in resistivity with partially improved mobility was found after annealing. However, not all ITO films show consistent improvement, but carrier density above 1021 cm-3 while ZnO films show no clear trend for carrier density but a remarkable increase in mobility. Thus we propose the healing of defects and the activation of donors to be most significant effects for ZnO and ITO films, respectively.

  19. Hierarchical Order of Influence of Mix Variables Affecting Compressive Strength of Sustainable Concrete Containing Fly Ash, Copper Slag, Silica Fume, and Fibres

    PubMed Central

    Natarajan, Sakthieswaran; Karuppiah, Ganesan

    2014-01-01

    Experiments have been conducted to study the effect of addition of fly ash, copper slag, and steel and polypropylene fibres on compressive strength of concrete and to determine the hierarchical order of influence of the mix variables in affecting the strength using cluster analysis experimentally. While fly ash and copper slag are used for partial replacement of cement and fine aggregate, respectively, defined quantities of steel and polypropylene fibres were added to the mixes. It is found from the experimental study that, in general, irrespective of the presence or absence of fibres, (i) for a given copper slag-fine aggregate ratio, increase in fly ash-cement ratio the concrete strength decreases and with the increase in copper slag-sand ratio also the rate of strength decrease and (ii) for a given fly ash-cement ratio, increase in copper slag-fine aggregate ratio increases the strength of the concrete. From the cluster analysis, it is found that the quantities of coarse and fine aggregate present have high influence in affecting the strength. It is also observed that the quantities of fly ash and copper slag used as substitutes have equal “influence” in affecting the strength. Marginal effect of addition of fibres in the compression strength of concrete is also revealed by the cluster analysis. PMID:24707213

  20. Hierarchical order of influence of mix variables affecting compressive strength of sustainable concrete containing fly ash, copper slag, silica fume, and fibres.

    PubMed

    Natarajan, Sakthieswaran; Karuppiah, Ganesan

    2014-01-01

    Experiments have been conducted to study the effect of addition of fly ash, copper slag, and steel and polypropylene fibres on compressive strength of concrete and to determine the hierarchical order of influence of the mix variables in affecting the strength using cluster analysis experimentally. While fly ash and copper slag are used for partial replacement of cement and fine aggregate, respectively, defined quantities of steel and polypropylene fibres were added to the mixes. It is found from the experimental study that, in general, irrespective of the presence or absence of fibres, (i) for a given copper slag-fine aggregate ratio, increase in fly ash-cement ratio the concrete strength decreases and with the increase in copper slag-sand ratio also the rate of strength decrease and (ii) for a given fly ash-cement ratio, increase in copper slag-fine aggregate ratio increases the strength of the concrete. From the cluster analysis, it is found that the quantities of coarse and fine aggregate present have high influence in affecting the strength. It is also observed that the quantities of fly ash and copper slag used as substitutes have equal "influence" in affecting the strength. Marginal effect of addition of fibres in the compression strength of concrete is also revealed by the cluster analysis. PMID:24707213

  1. An Innovative High Thermal Conductivity Fuel Design

    SciTech Connect

    Jamil A. Khan

    2009-11-21

    Thermal conductivity of the fuel in today's Light Water Reactors, Uranium dioxide, can be improved by incorporating a uniformly distributed heat conducting network of a higher conductivity material, Silicon Carbide. The higher thermal conductivity of SiC along with its other prominent reactor-grade properties makes it a potential material to address some of the related issues when used in UO2 [97% TD]. This ongoing research, in collaboration with the University of Florida, aims to investigate the feasibility and develop a formal methodology of producing the resultant composite oxide fuel. Calculations of effective thermal conductivity of the new fuel as a function of %SiC for certain percentages and as a function of temperature are presented as a preliminary approach. The effective thermal conductivities are obtained at different temperatures from 600K to 1600K. The corresponding polynomial equations for the temperature-dependent thermal conductivities are given based on the simulation results. Heat transfer mechanism in this fuel is explained using a finite volume approach and validated against existing empirical models. FLUENT 6.1.22 was used for thermal conductivity calculations and to estimate reduction in centerline temperatures achievable within such a fuel rod. Later, computer codes COMBINE-PC and VENTURE-PC were deployed to estimate the fuel enrichment required, to maintain the same burnup levels, corresponding to a volume percent addition of SiC.

  2. Determination of slagging behavior of various coal ash samples by using DTF

    SciTech Connect

    Kim, H.T.; Choi, B.C.; Park, S.W.

    1999-07-01

    The objective of this study is to investigate slagging behavior of various ash samples with the conjunction to the properties of ashes and original coal such as concentration of each ash components, ash slagging temperature and slag viscosity. To simulate actual ash melting condition in coal combustion as well as gasification, DTF (drop tube furnace) is utilized for the acquisition of slag sample with different reaction condition. The sampled slag is photographed for the visual inspection and the shape of the slag is evaluated with ash properties. The sampled ash slag is also analyzed with XRD for the determination of phase transition during the ash melting. Furthermore, coal ashes are processed with Ash Fusion Determinator for the fusion temperature and High-Temperature Viscometer for the slag viscosity. Such ash-related properties are also determined by empirical formulation for the refinement of the result. So far, three different coal samples, Alaska, Datong, Cyprus are investigated. For the 3 ash samples, slag formation shows similar shape in combustion as well as gasification condition and completely different shape with different coal types. Alaska slag, which represents higher fluidity, is penetrated into alumina disk so that small half-cone shape of slag is produced. However, Cyprus slag is formed with more circular shape of sphere and Datong slag represents an in-between shape. More coal samples will be studied for the determination of slag behavior. The shape data will be analyzed with ash composition, fluidity behavior and ash fusion determination of original coal. Such relationship will be the baseline to determine the operation parameter of slag removal in the 3 ton/day coal gasifier located in the Ajou University, Suwon, Korea.

  3. Nonequilibrium Sulfur Capture and Retention in an Air cooled Slagging Coal Combustion.

    SciTech Connect

    Zauderer, B.

    1997-04-14

    Calcium oxide sorbents injected in a slagging combustor react with the sulfur released during coal combustion to form sulfur bearing particles, some of which are deposited on the liquid slag layer on the combustor wall. Since the solubility of sulfur in liquid slag is low, the slag must be drained from the combustor to limit sulfur re-evolution into the gas phase. The objective of this 24 month project is to perform a series of 16 one day tests to determine the factors that control the retention of the sulfur in the slag that is drained from the combustor. The last of the 16 tests planned for this project was completed in the present reporting period. This was the first test in this project that validated one of the primary hypothesis of this project, namely to retain substantial quantities of sulfur in slag requires high slag mass flow rate. Previous attempts to achieve high sulfur retention with artificial slag met limited success. In this, the 16th test, a high, 37%, ash Indian coal was injected into Coal Tech`s 20 MMBtu/hr air cooled, slagging combustor with gypsum, CaSO{sub 4} (2H{sub 2}O). The slag analysis showed that 20% of the sulfur in the gypsum remained in the slag. This is double the highest sulfur concentration in slag measured in numerous test operations with this combustor. While the test results to date have met the objectives of this project, further high slag mass flow rate tests are planned with the Indian coal to optimize sulfur retention in slag.

  4. Slag recycling of irradiated vanadium

    SciTech Connect

    Gorman, P.K.

    1995-04-05

    An experimental inductoslag apparatus to recycle irradiated vanadium was fabricated and tested. An experimental electroslag apparatus was also used to test possible slags. The testing was carried out with slag materials that were fabricated along with impurity bearing vanadium samples. Results obtained include computer simulated thermochemical calculations and experimentally determined removal efficiencies of the transmutation impurities. Analyses of the samples before and after testing were carried out to determine if the slag did indeed remove the transmutation impurities from the irradiated vanadium.

  5. Slag characterization and removal using pulse detonation for coal gasification. Quarterly research report, July 1--September 31, 1996

    SciTech Connect

    Huque, Z.; Mei, D.; Biney, P.O.; Zhou, J.; Ali, M.R.

    1996-10-25

    Boiler slagging and fouling as a result of inorganic impurities in combustion gases being deposited on heat transfer tubes have caused severe problems in coal-fired power plant operation. These problems are fuel, system design, and operating condition dependent. Conventional slag and ash removal methods include the use of in situ blowing or jet-type devices such as air or steam soot blowers and water lances. Pulse detonation technology for the purpose of removing slag and fouling deposits in coal-fired utility power plant boilers offers great potential. The detonation wave technique based on high impact velocity with sufficient energy and thermal shock on the slag deposited on gas contact surfaces offers a convenient, inexpensive, yet efficient and effective way to supplement existing slag removal methods. These detonation waves have been demonstrated experimentally to have exceptionally high shearing capability important to the task of removing slag and fouling deposits. Several tests have been performed with single shot detonation wave at University of Texas at Arlington to remove the slag deposit. To hold the slag deposit samples at the exit of detonation tube, two types of fixture was designed and fabricated. They are axial arrangement and triangular arrangement. The slag deposits from the utility boilers have been used to prepare the slag samples for the test. The experimental results show that the single shot detonation wave is capable of removing the entire slag (types of slag deposited on economizer, and air-heater, i.e., relatively softer slags) and 30% of the reheater slag (which is harder) even at a distance of 6 in. from the exit of a detonation engine tube. Wave strength and slag orientation also have different effects on the chipping off of the slag. The annual report discusses about the results obtained in effectively removing the slag.

  6. Electrochemical cell with high conductivity glass electrolyte

    DOEpatents

    Nelson, Paul A.; Bloom, Ira D.; Roche, Michael F.

    1987-01-01

    A secondary electrochemical cell with sodium-sulfur or other molten reactants is provided with a ionically conductive glass electrolyte. The cell is contained within an electrically conductive housing with a first portion at negative potential and a second portion insulated therefrom at positive electrode potential. The glass electrolyte is formed into a plurality of elongated tubes and placed lengthwise within the housing. The positive electrode material, for instance sulfur, is sealed into the glass electrolyte tubes and is provided with an elongated axial current collector. The glass electrolyte tubes are protected by shield tubes or sheets that also define narrow annuli for wicking of the molten negative electrode material.

  7. Electrochemical cell with high conductivity glass electrolyte

    DOEpatents

    Nelson, P.A.; Bloom, I.D.; Roche, M.F.

    1986-04-17

    A secondary electrochemical cell with sodium-sulfur or other molten reactants is provided with an ionically conductive glass electrolyte. The cell is contained within an electrically conductive housing with a first portion at negative potential and a second portion insulated therefrom at positive electrode potential. The glass electrolyte is formed into a plurality of elongated tubes and placed lengthwise within the housing. The positive electrode material, for instance sulfur, is sealed into the glass electrolyte tubes and is provided with an elongated axial current collector. The glass electrolyte tubes are protected by shield tubes or sheets that also define narrow annuli for wicking of the molten negative electrode material.

  8. Electrochemical cell with high conductivity glass electrolyte

    DOEpatents

    Nelson, P.A.; Bloom, I.D.; Roche, M.F.

    1987-04-21

    A secondary electrochemical cell with sodium-sulfur or other molten reactants is provided with a ionically conductive glass electrolyte. The cell is contained within an electrically conductive housing with a first portion at negative potential and a second portion insulated therefrom at positive electrode potential. The glass electrolyte is formed into a plurality of elongated tubes and placed lengthwise within the housing. The positive electrode material, for instance sulfur, is sealed into the glass electrolyte tubes and is provided with an elongated axial current collector. The glass electrolyte tubes are protected by shield tubes or sheets that also define narrow annuli for wicking of the molten negative electrode material. 6 figs.

  9. Conducting polymer for high power ultracapacitor

    DOEpatents

    Shi, Steven Z.; Gottesfeld, Shimshon

    2002-01-01

    In accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention is directed to an electrode having a conducting polymer active material for use in an ultracapacitor. The conducting polymer active material is electropolymerized onto a carbon paper substrate from a mixed solution of a dimer of (3,3' bithiophene) (BT) and a monomer that is selected from the group of thiophenes derived in the 3-position, having an aryl group attached to thiophene in the 3-position or having aryl and alkly groups independently attached to thiophene in the 3 and 4 positions.

  10. Coal gasifier wall protection system - slag shedding technique

    SciTech Connect

    Sanscrainte, W.; Marshall, D.

    1982-12-01

    This report describes how a long-term slag shedding experiment was developed. The results of the evaluation of various materials and techniques for protecting gasifier walls from damaging environments while maintaining high efficiency and good cooling properties are presented. This report states that an A 387 alloy appears to be an acceptable gasifier wall material. Cyclic slag shedding and slag thickness are dependent on cooling level, temperature and surface roughness. A water-cooled test section was operated successfully at full-scale operating temperature.

  11. Slag/mud mixtures improve cementing operations in China

    SciTech Connect

    Wu, D.; Peiyan; Huang, B.

    1996-12-23

    The use of blast furnace slag, which is inexpensive and widely available throughout China, can with proper activators and retarders, solidify mud into an excellent cementing material. The use of slag-mix has been somewhat controversial. Some experts claim slag-mix is the most important progress to date in mud-to-cement conversion and has become another choice for cementing practices.They also believed there were no fundamental limitations to its application downhole, and conceivably the material could be used for any well cemented. Other experts have different points of view and thought it might have limits for oil field use. In their studies, the basic mud had to be diluted by 60% or more with water before the blast furnace slag (BFS) was added. Their slag slurries showed a high incidence of cracking and apparent brittle nature, bad settling stability, and volume shrinkage. To date, the Chinese National petroleum Corp. (CNPC) has used mud solidification by slag successfully on 22 cementing jobs in the Sichun, Changqing, Jidong, and Shengli oil fields.The major purpose of these investigations was to determine the application of slag-mix technology to various cementing operations.

  12. Decalcification resistance of alkali-activated slag.

    PubMed

    Komljenović, Miroslav M; Baščarević, Zvezdana; Marjanović, Nataša; Nikolić, Violeta

    2012-09-30

    This paper analyses the effects of decalcification in concentrated 6M NH(4)NO(3) solution on mechanical and microstructural properties of alkali-activated slag (AAS). Portland-slag cement (CEM II/A-S 42.5 N) was used as a benchmark material. Decalcification process led to a decrease in strength, both in AAS and in CEM II, and this effect was more pronounced in CEM II. The decrease in strength was explicitly related to the decrease in Ca/Si atomic ratio of C-S-H gel. A very low ratio of Ca/Si ~0.3 in AAS was the consequence of coexistence of C-S-H(I) gel and silica gel. During decalcification of AAS almost complete leaching of sodium and tetrahedral aluminum from C-S-H(I) gel also took place. AAS showed significantly higher resistance to decalcification in relation to the benchmark CEM II due to the absence of portlandite, high level of polymerization of silicate chains, low level of aluminum for silicon substitution in the structure of C-S-H(I), and the formation of protective layer of polymerized silica gel during decalcification process. In stabilization/solidification processes alkali-activated slag represents a more promising solution than Portland-slag cement due to significantly higher resistance to decalcification. PMID:22818592

  13. Effect of fuel quality on slagging behavior in a cyclone-fired boiler

    SciTech Connect

    Katrinak, K.; Laumb, J.; Peterson, W.; Schwalbe, R.

    1998-12-31

    Relationships between the occurrence of poor slag flow episodes at a cyclone-fired boiler, coal mineral content, heating value, and other fuel quality parameters have been investigated. In addition, optimization of boiler operating conditions to match coal quality is the major emphasis of current activities. The boiler fires North Dakota lignite, a highly variable fuel, and experiences intermittent cyclone slagging problems related to coal quality. Cyclone slagging episodes were found to occur when the heating value of the fuel was less than 6600 Btu/lb and the T250 was greater than 2250 F. Higher-Btu coals burn hotter and appear to be able to handle higher T250 values without slagging. Other fuel quality parameters related to cyclone slag flow behavior include high silicon and aluminum concentrations and high concentrations of the silicon- and aluminum-rich clay minerals illite and montmorillonite. These minerals are thought to contribute to cyclone slagging episodes by reducing the ability of the slag to incorporate calcium, thus leading to increased slag viscosity. To improve slag flow behavior, operating conditions have been modified to maintain high temperatures in the cyclones. Changes include increasing coal drying temperature and balancing the air/fuel ratio. T250 can be readily calculated from coal ash composition. Clays and other minerals can be identified in individual coal particles using automated scanning electron microscopy with energy-dispersive X-ray spectrometry. Use of these analytical techniques can enable potential cyclone slagging problems to be predicted in advance.

  14. Thermal Conductivity of Argon at High Pressures and High Temperatures

    NASA Astrophysics Data System (ADS)

    Wong, M. L.; Goncharov, A. F.; Dalton, D. A.; Ojwang, J.; Struzhkin, V.; Konopkova, Z.; Lazor, P.

    2010-12-01

    Accurate data on the thermal conductivity of argon at high pressures and high temperatures is essential to unraveling the nature of the Earth’s interior. Argon is a common pressure-transmitting medium in diamond anvil cell (DAC) experiments, which is commonly used for studying the properties of minerals at pressures and temperatures native to the mantel and core. We used a transient heating technique (Beck et al., 2007) in a symmetric DAC up to 50 GPa and 2500 K. A thin iridium foil (1 μm thick) positioned in a recessed gasket hole filled with argon served as a heat absorber (coupler) to pump thermal energy into the sample. We used 6 μs width pulses from electronically modulated Yb-based fiber laser. We determined the temperature of the coupler with 500 ns time resolution by applying the Planck function to its thermal emission spectrum, and doing this over time yields temperature verses time for the coupler. Using finite element (FE) calculation methods we simulated the heat flux transfer in the DAC cavity using the experimentally determined geometric and laser heating parameters. The thermochemical parameters of Ir and Ar were determined by scaling the ambient pressure data using the available equations of state. The temperature dependent thermal conductivity of Ar was determined by fitting the results of FE calculations to the experimentally determined time dependent coupler temperature. We used the results of the theoretical calculations (Tretiakov & Scandolo, 2004) as the initial input. The results for the pressure and temperature dependent thermal conductivity of Ar will be reported at the meeting. This work is supported by NSF EAR 0711358, NSF-REU, Carnegie Institution of Washington, and DOE-NNSA (CDAC). Beck, P; Goncharov, A.F., Struzhkin, V.V., Militzer, B, Mao, H.K, Hemley, R.J. (2007). Measurement of thermal diffusivity at high pressure using a transient heating technique, Appl Phys. Lett. 91, 181914-(1-3). Tretiakov, K. V. & S. Scandolo (2004

  15. Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

    NASA Astrophysics Data System (ADS)

    Shi, Huan; Feng, Ke-qin; Wang, Hai-bo; Chen, Chang-hong; Zhou, Hong-ling

    2016-05-01

    To effectively reuse high-titanium blast furnace slag (TS), foam glass-ceramics were successfully prepared by powder sintering at 1000°C. TS and waste glass were used as the main raw materials, aluminium nitride (AlN) as the foaming agent, and borax as the fluxing agent. The influence of the amount of AlN added (1wt%-5wt%) on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing AlN content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the average pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AlN.

  16. A discussion on improving hydration activity of steel slag by altering its mineral compositions.

    PubMed

    Wang, Qiang; Yan, Peiyu; Feng, Jianwen

    2011-02-28

    This study aims to investigate the ways to improve the cementitious properties of steel slag. The results show that the cementitious phase of steel slag is composed of silicate and aluminate, but the large particles of these phases make a very small contribution to the cementitious properties of steel slag. RO phase (CaO-FeO-MnO-MgO solid solution), Fe(3)O(4), C(2)F and f-CaO make no contribution to the cementitious properties of steel slag. A new kind of steel slag with more cementitious phase and less RO phase can be obtained by removing some large particles. This new steel slag possesses better cementitious properties than the original steel slag. The large particles can be used as fine aggregates for concrete. Adding regulating agent high in CaO and SiO(2) during manufacturing process of steel slag to increase the cementitious phase to inert phase ratio is another way to improve its cementitious properties. The regulating agent should be selected to adapt to the specific steel slag and the alkalinity should be increased as high as possible on the premise that the f-CaO content does not increase. The cooling rate should be enhanced to improve the hydration activity of the cementitious phase at the early ages and the grindability of steel slag. PMID:21168967

  17. Desulfurization ability of refining slag with medium basicity

    NASA Astrophysics Data System (ADS)

    Yu, Hui-xiang; Wang, Xin-hua; Wang, Mao; Wang, Wan-jun

    2014-12-01

    The desulfurization ability of refining slag with relative lower basicity ( B) and Al2O3 content ( B = 3.5-5.0; 20wt%-25wt% Al2O3) was studied. Firstly, the component activities and sulfide capacity ( C S) of the slag were calculated. Then slag-metal equilibrium experiments were carried out to measure the equilibrium sulfur distribution ( L S). Based on the laboratorial experiments, slag composition was optimized for a better desulfurization ability, which was verified by industrial trials in a steel plant. The obtained results indicated that an MgO-saturated CaO-Al2O3-SiO2-MgO system with the basicity of about 3.5-5.0 and the Al2O3 content in the range of 20wt%-25wt% has high activity of CaO ( a CaO), with no deterioration of C S compared with conventional desulfurization slag. The measured L S between high-strength low-alloyed (HSLA) steel and slag with a basicity of about 3.5 and an Al2O3 content of about 20wt% and between HSLA steel and slag with a basicity of about 5.0 and an Al2O3 content of about 25wt% is 350 and 275, respectively. The new slag with a basicity of about 3.5-5.0 and an Al2O3 content of about 20wt% has strong desulfurization ability. In particular, the key for high-efficiency desulfurization is to keep oxygen potential in the reaction system as low as possible, which was also verified by industrial trials.

  18. Use of granular slag columns for lead removal.

    PubMed

    Dimitrova, S V

    2002-09-01

    The use of granular blast furnace slag (GBFS)-packed columns to treat lead-containing solutions has been investigated. The results obtained indicated that the slag usage rate decreased with increasing flow velocity, particle size, initial lead concentration and decreasing with bed height. Lead removed selectively in the presence of other heavy metal ions. High concentrations of sodium and especially calcium in the solutions impeded the uptake of lead. For 20 mg l(-1) lead concentration an empty bed contact time greater of 4 min provided to efficient use of the slag bed. Column pH was an important parameter to lead removal under dynamic conditions and reflected the influence of the investigated factors. During all runs lead breakthrough coincided with an abrupt drop in effluent pH. The apparent mechanisms of lead removal in GBFS column are sorption (ion exchange and adsorption) on the slag surface and precipitation. PMID:12405409

  19. Strength and pore structure of ternary blended cement mortars containing blast furnace slag and silica fume

    SciTech Connect

    Bagel, L.

    1998-07-01

    Blended cement mortars with fixed workability and incorporating blast furnace slag and silica fume, were tested for compressive strength and mercury intrusion, with a view to comparing their performance with that of plain Portland cement mortar and/or slag-cement mortar. The obtained results showed that with high portions of slag and silica fume in the binding system, the mortars reached relatively satisfactory level of compressive strength and contributed to the significantly denser pore structure.

  20. Estimating phosphorus removal by steel slag in a flume experiment: effects of P concentrations and subsurface hydrological conditions

    NASA Astrophysics Data System (ADS)

    Chagas, I. S. P.; Huang, C. H.; Bowling, L. C.; Smith, D. R.

    2015-12-01

    Managing excessive phosphorus (P) is essential to reduce the incidence of environmental quality issues, such as eutrophication and harmful algal blooms. One potential strategy that have been developed with this purpose is the use of P sorption materials (PSMs) to sequester P from water systems, which is the objective of this study. We evaluated the performance of steel slag, an industrial by-product with high P sorption potential, through a flume experiment under two different subsurface hydrological conditions, drainage and saturation, and two input P concentrations, 1 and 5 ppm. The 10-m flume configuration, designed to simulate processes occurring in a drainage ditch, is comprised of four 2.5-m sequential segments: a sediment bed, a slag bed over sediment, a slag dam built over a slag bed, and another sediment bed. In the experiments, all four segments of the flume were set to either saturation or with a constant drainage (percolation) of 0.1 L/min for each segment. The experiment was conducted with a constant flow of elevated P water at 7.3 L/min for 4 hrs (adsorption run) and followed 24 hrs later by a 4-hr run of deionized water (desorption run) at the same inflow rate. The adsorption-desorption cycle was repeated three times with the same sediment and slag materials, to allow testing of the resilience of P sorption under different PSM placement, subsurface hydrologic and P loading conditions. Preliminary results from the first adsorption and desorption cycle show that the flow-through slag section sequestered the most P during the adsorption runs. By comparing the different P inflow concentrations analysis, it is clear that the removal process is concentration driven: 83% of the injected P was removed in the 5 ppm as compared to 46% in the 1 ppm saturation run. Because of the higher P removal at 5 ppm P inflow, slightly higher release was also observed during the desorption run. Analyses of the persistence of steel slag as PSM under repeated adsorption and

  1. Study of Chromium Oxide Activities in EAF Slags

    NASA Astrophysics Data System (ADS)

    Yan, Baijun; Li, Fan; Wang, Hui; Sichen, Du

    2016-02-01

    The activity coefficients of chromium in Cu-Cr melts were determined by equilibrating liquid copper with solid Cr2O3 in CO-CO2 atmosphere. The temperature dependence of the activity coefficients of chromium in Cu-Cr melts could be expressed as lg γ_{Cr}(s)^{0} = { 3 2 5 9( ± 1 8 6} )/T - 0. 5 9( { ± 0. 1} ). Based on the above results, the activities of bivalent and trivalent chromium oxide in some slags at 1873 K (1600 °C) were measured. The slags were equilibrated with Cu-Cr melts under two oxygen partial pressures ( {p_{O}_{ 2} }} } = 6.9 × 10-4 and 1.8 × 10-6 Pa, respectively). The morphology of the quenched slags and the solubility of chromium oxide in the melts were investigated by EPMA, SEM, and XRD. Under both oxygen partial pressures, the slags were saturated by the solid solution MgAl2- x Cr x O4- δ . At the low oxygen partial pressure (1.8 × 10-6 Pa), the content of Cr in the liquid phase varied from 0.4 to 1.6 mass pct with the total Cr content in the slags increasing from 1.3 to 10.8 mass pct. At the high oxygen partial pressure (6.9 × 10-4 Pa), the content of Cr in the liquid phase decreased to the level of 0.2 to 0.6 mass pct. Both the activities of CrO and Cr2O3 in slag were found to increase approximately linearly with the increase of the total Cr content in slag. While the oxygen partial pressure had minor effect on the activity of Cr2O3 in the slag, it had significant effect on the activity of CrO.

  2. Use of ancient copper slags in Portland cement and alkali activated cement matrices.

    PubMed

    Nazer, Amin; Payá, Jordi; Borrachero, María Victoria; Monzó, José

    2016-02-01

    Some Chilean copper slag dumps from the nineteenth century still remain, without a proposed use that encourages recycling and reduces environmental impact. In this paper, the copper slag abandoned in landfills is proposed as a new building material. The slags studied were taken from Playa Negra and Púquios dumps, both located in the region of Atacama in northern Chile. Pozzolanic activity in lime and Portland cement systems, as well as the alkali activation in pastes with copper slag cured at different temperatures, was studied. The reactivity of the slag was measured using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), electrical conductivity and pH in aqueous suspension and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, copper slag-Portland cement mortars with the substitution of 25% (by weight) of cement by copper slag and alkali-activated slag mortars cured at 20 and 65 °C were made, to determine the compressive strength. The results indicate that the ancient copper slags studied have interesting binding properties for the construction sector. PMID:26615227

  3. Properties and hydration of blended cements with steelmaking slag

    SciTech Connect

    Kourounis, S.; Tsivilis, S. . E-mail: stsiv@central.ntua.gr; Tsakiridis, P.E.; Papadimitriou, G.D.; Tsibouki, Z.

    2007-06-15

    The present research study investigates the properties and hydration of blended cements with steelmaking slag, a by-product of the conversion process of iron to steel. For this purpose, a reference sample and three cements containing up to 45% w/w steel slag were tested. The steel slag fraction used was the '0-5 mm', due to its high content in calcium silicate phases. Initial and final setting time, standard consistency, flow of normal mortar, autoclave expansion and compressive strength at 2, 7, 28 and 90 days were measured. The hydrated products were identified by X-ray diffraction while the non-evaporable water was determined by TGA. The microstructure of the hardened cement pastes and their morphological characteristics were examined by scanning electron microscopy. It is concluded that slag can be used in the production of composite cements of the strength classes 42.5 and 32.5 of EN 197-1. In addition, the slag cements present satisfactory physical properties. The steel slag slows down the hydration of the blended cements, due to the morphology of contained C{sub 2}S and its low content in calcium silicates.

  4. Effects of Slag Ejection on Solid Rocket Motor Performance

    NASA Technical Reports Server (NTRS)

    Whitesides, R. Harold; Purinton, David C.; Hengel, John E.; Skelley, Stephen E.

    1995-01-01

    In past firings of the Reusable Solid Rocket Motor (RSRM) both static test and flight motors have shown small pressure perturbations occurring primarily between 65 and 80 seconds. A joint NASA/Thiokol team investigation concluded that the cause of the pressure perturbations was the periodic ingestion and ejection of molten aluminum oxide slag from the cavity around the submerged nozzle nose which tends to trap and collect individual aluminum oxide droplets from the approach flow. The conclusions of the team were supported by numerous data and observations from special tests including high speed photographic films, real time radiography, plume calorimeters, accelerometers, strain gauges, nozzle TVC system force gauges, and motor pressure and thrust data. A simplistic slag ballistics model was formulated to relate a given pressure perturbation to a required slag quantity. Also, a cold flow model using air and water was developed to provide data on the relationship between the slag flow rate and the chamber pressure increase. Both the motor and the cold flow model exhibited low frequency oscillations in conjunction with periods of slag ejection. Motor and model frequencies were related to scaling parameters. The data indicate that there is a periodicity to the slag entrainment and ejection phenomena which is possibly related to organized oscillations from instabilities in the dividing streamline shear layer which impinges on the underneath surface of the nozzle.

  5. Decontamination of metals by melt refinings/slagging: An annotated bibliography

    SciTech Connect

    Mizia, R.E.; Worcester, S.A.; Twidwell, L.G.; Paolini, D.J.; Weldon, T.A.

    1993-07-01

    As the number of nuclear installations undergoing decontamination and decommissioning (D&D) increases, current radioactive waste storage space is consumed and establishment of new waste storage areas becomes increasingly difficult, the problem of handling and storing radioactive scrap metal (RSM) gains increasing importance in the DOE Environmental Restoration and Waste Management Program. To alleviate present and future waste storage problems, Westinghouse Idaho Nuclear Company (WINCO) is managing a program for the recycling of RSM for beneficial use within the DOE complex. As part of that effort, Montana Tech has been awarded a contract to help optimize melting and refining technology for the recycling of stainless steel RSM. The scope of the Montana Tech program includes a literature survey, a decontaminating slag design study, small scale melting studies to determine optimum slag compositions for removal of radioactive contaminant surrogates, analysis of preferred melting techniques, and coordination of large scale melting demonstrations (100--500 lbs) to be conducted at selected facilities. The program will support recycling and decontaminating stainless steel RSM for use in waste canisters for Idaho Waste Immobilization Facility densified high level waste. This report is the result of the literature search conducted to establish a basis for experimental melt/slag program development.

  6. An Empirical Viscosity Model for Coal Slags

    SciTech Connect

    Matyas, Josef; Cooley, Scott K.; Sundaram, S. K.; Rodriguez, Carmen P.; Edmondson, Autumn B.; Arrigoni, Benjamin M.

    2008-10-25

    Slags of low viscosity readily penetrate the refractory lining in slagging gasifiers, causing rapid and severe corrosion called spalling. In addition, a low-viscosity slag that flows down the gasifier wall forms a relatively thin layer of slag on the refractory surface, allowing the corrosive gases in the gasifier to participate in the chemical reactions between the refractory and the slag. In contrast, a slag viscosity of <25 Pa•s at 1400°C is necessary to minimize the possibility of plugging the slag tap. There is a need to predict and optimize slag viscosity so slagging gasifiers can operate continuously at temperatures ranging from 1300 to 1650°C. The approach adopted in this work was to statistically design and prepare simulated slags, measure the viscosity as a function of temperature, and develop a model to predict slag viscosity based on slag composition and temperature. Statistical design software was used to select compositions from a candidate set of all possible vertices that will optimally represent the composition space for 10 main components. A total of 21 slag compositions were generated, including 5 actual coal slag compositions. The Arrhenius equation was applied to measured viscosity versus temperature data of tested slags, and the Arrhenius coefficients (A and B in ln(vis) = A + B/T) were expressed as linear functions of the slag composition. The viscosity model was validated using 1) data splitting approach, and 2) viscosity/temperature data of selected slag compositions from the literature that were formulated and melted at Pacific Northwest National Laboratory. The capability of the model to predict the viscosity of coal slags was compared with the model developed by Browning et al. because this model can predict the viscosity of slags from coal ash better than the most commonly used empirical models found in the literature.

  7. Environmental impacts of asphalt mixes with electric arc furnace steel slag.

    PubMed

    Milačič, Radmila; Zuliani, Tea; Oblak, Tina; Mladenovič, Ana; Ančar, Janez Šč

    2011-01-01

    Electric arc furnace (EAF) steel slag can be used as an alternative high-quality material in road construction. Although asphalts with slag aggregates have been recognized as environmentally acceptable, there is a lack of data concerning the potential leaching of toxic Cr(VI) due to the highly alkaline media of EAF slag. Leaching of selected water extractable metals from slag indicated elevated concentrations of total chromium and Cr(VI). To estimate the environmental impacts of asphalt mixes with slag, leachability tests based on diffusion were performed using pure water and salt water as leaching agents. Compact and ground asphalt composites with natural aggregates, and asphalt composites in which the natural aggregates were completely replaced by slag were prepared. The concentrations of total chromium and Cr(VI) were determined in leachates over a time period of 6 mo. After 1 and 6 mo, the concentrations of some other metals were also determined in the leachates. The results indicated that chromium in leachates from asphalt composites with the addition of slag was present almost solely in its hexavalent form. However, the concentrations were very low (below 25 μg L) and did not represent an environmental burden. The leaching of other metals from asphalt composites with the addition of slag was negligible. Therefore, the investigated EAF slag can be considered as environmentally safe substitute for natural aggregates in asphalt mixes. PMID:21712585

  8. Rearrangement of 1D conducting nanomaterials towards highly electrically conducting nanocomposite fibres for electronic textiles.

    PubMed

    Han, Joong Tark; Choi, Sua; Jang, Jeong In; Seol, Seung Kwon; Woo, Jong Seok; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Lee, Geon-Woong

    2015-01-01

    Nanocarbon-based conducting fibres have been produced using solution- or dry-spinning techniques. Highly conductive polymer-composite fibres containing large amounts of conducting nanomaterials have not been produced without dispersants, however, because of the severe aggregation of conducting materials in high-concentration colloidal solutions. Here we show that highly conductive (electrical conductivity ~1.5 × 10(5) S m(-1)) polymer-composite fibres containing carbon nanotubes and silver nanowires can be fabricated via a conventional solution-spinning process without any other treatment. Spinning dopes were fabricated by a simple mixing of a polyvinyl alcohol solution in dimethylsulfoxide with a paste of long multi-walled carbon nanotubes dispersed in organic solvents, assisted by quadruple hydrogen-bonding networks and an aqueous silver nanowire dispersion. The high electrical conductivity of the fibre was achieved by rearrangement of silver nanowires towards the fibre skin during coagulation because of the selective favourable interaction between the silver nanowires and coagulation solvents. The prepared conducting fibres provide applications in electronic textiles such as a textile interconnector of light emitting diodes, flexible textile heaters, and touch gloves for capacitive touch sensors. PMID:25792333

  9. Rearrangement of 1D Conducting Nanomaterials towards Highly Electrically Conducting Nanocomposite Fibres for Electronic Textiles

    NASA Astrophysics Data System (ADS)

    Han, Joong Tark; Choi, Sua; Jang, Jeong In; Seol, Seung Kwon; Woo, Jong Seok; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Lee, Geon-Woong

    2015-03-01

    Nanocarbon-based conducting fibres have been produced using solution- or dry-spinning techniques. Highly conductive polymer-composite fibres containing large amounts of conducting nanomaterials have not been produced without dispersants, however, because of the severe aggregation of conducting materials in high-concentration colloidal solutions. Here we show that highly conductive (electrical conductivity ~1.5 × 105 S m-1) polymer-composite fibres containing carbon nanotubes and silver nanowires can be fabricated via a conventional solution-spinning process without any other treatment. Spinning dopes were fabricated by a simple mixing of a polyvinyl alcohol solution in dimethylsulfoxide with a paste of long multi-walled carbon nanotubes dispersed in organic solvents, assisted by quadruple hydrogen-bonding networks and an aqueous silver nanowire dispersion. The high electrical conductivity of the fibre was achieved by rearrangement of silver nanowires towards the fibre skin during coagulation because of the selective favourable interaction between the silver nanowires and coagulation solvents. The prepared conducting fibres provide applications in electronic textiles such as a textile interconnector of light emitting diodes, flexible textile heaters, and touch gloves for capacitive touch sensors.

  10. Rearrangement of 1D Conducting Nanomaterials towards Highly Electrically Conducting Nanocomposite Fibres for Electronic Textiles

    PubMed Central

    Han, Joong Tark; Choi, Sua; Jang, Jeong In; Seol, Seung Kwon; Woo, Jong Seok; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Lee, Geon-Woong

    2015-01-01

    Nanocarbon-based conducting fibres have been produced using solution- or dry-spinning techniques. Highly conductive polymer-composite fibres containing large amounts of conducting nanomaterials have not been produced without dispersants, however, because of the severe aggregation of conducting materials in high-concentration colloidal solutions. Here we show that highly conductive (electrical conductivity ~1.5 × 105 S m−1) polymer-composite fibres containing carbon nanotubes and silver nanowires can be fabricated via a conventional solution-spinning process without any other treatment. Spinning dopes were fabricated by a simple mixing of a polyvinyl alcohol solution in dimethylsulfoxide with a paste of long multi-walled carbon nanotubes dispersed in organic solvents, assisted by quadruple hydrogen-bonding networks and an aqueous silver nanowire dispersion. The high electrical conductivity of the fibre was achieved by rearrangement of silver nanowires towards the fibre skin during coagulation because of the selective favourable interaction between the silver nanowires and coagulation solvents. The prepared conducting fibres provide applications in electronic textiles such as a textile interconnector of light emitting diodes, flexible textile heaters, and touch gloves for capacitive touch sensors. PMID:25792333

  11. SLAG CHARACTERIZATION AND REMOVAL USING PULSE DETONATION TECHNOLOGY DURING COAL GASIFICATION

    SciTech Connect

    DR. DANIEL MEI; DR. JIANREN ZHOU; DR. PAUL O. BINEY; DR. ZIAUL HUQUE

    1998-07-30

    Pulse detonation technology for the purpose of removing slag and fouling deposits in coal-fired utility power plant boilers offers great potential. Conventional slag removal methods including soot blowers and water lances have great difficulties in removing slags especially from the down stream areas of utility power plant boilers. The detonation wave technique, based on high impact velocity with sufficient energy and thermal shock on the slag deposited on gas contact surfaces offers a convenient, inexpensive, yet efficient and effective way to supplement existing slag removal methods. A slight increase in the boiler efficiency, due to more effective ash/deposit removal and corresponding reduction in plant maintenance downtime and increased heat transfer efficiency, will save millions of dollars in operational costs. Reductions in toxic emissions will also be accomplished due to reduction in coal usage. Detonation waves have been demonstrated experimentally to have exceptionally high shearing capability, important to the task of removing slag and fouling deposits. The experimental results describe the parametric study of the input parameters in removing the different types of slag and operating condition. The experimental results show that both the single and multi shot detonation waves have high potential in effectively removing slag deposit from boiler heat transfer surfaces. The results obtained are encouraging and satisfactory. A good indication has also been obtained from the agreement with the preliminary computational fluid dynamics analysis that the wave impacts are more effective in removing slag deposits from tube bundles rather than single tube. This report presents results obtained in effectively removing three different types of slag (economizer, reheater, and air-heater) t a distance of up to 20 cm from the exit of the detonation tube. The experimental results show that the softer slags can be removed more easily. Also closer the slag to the exit of

  12. Purex Processing of Dissolved Sand, Slag, and Crucible Containing High Levels of Boric Acid and Calcium Fluoride

    SciTech Connect

    Kyser, E.A.

    1998-05-01

    The plutonium solution obtained from the dissolution of SSC in F- Canyon will be high in fluoride. Flowsheet adjustments must be made to increase the plutonium extraction in the solvent extraction cycle to keep Pu losses from being excessive.

  13. Experimental investigation of basic oxygen furnace slag used as aggregate in asphalt mixture.

    PubMed

    Xue, Yongjie; Wu, Shaopeng; Hou, Haobo; Zha, Jin

    2006-11-16

    Chinese researchers have commenced a great deal of researches on the development of application fields of basic oxygen steel making furnace slag (BOF slag) for many years. Lots of new applications and properties have been found, but few of them in asphalt mixture of road construction engineering. This paper discussed the feasibility of BOF steel slag used as aggregate in asphalt pavement by two points of view including BOF steel slag's physical and micro-properties as well as steel slag asphalt materials and pavement performances. For the former part, this paper mainly concerned the mechanochemistry and physical changes of the steel slag and studied it by performing XRD, SEM, TG and mercury porosimeter analysis and testing method. In the second part, this paper intended to use BOF steel slag as raw material, and design steel slag SMA mixture. By using traditional rutting test, soak wheel track and modified Lottman test, the high temperature stability and water resistance ability were tested. Single axes compression test and indirect tensile test were performed to evaluate the low temperature crack resistance performance and fatigue characteristic. Simultaneously, by observing steel slag SMA pavement which was paved successfully. A follow-up study to evaluate the performance of the experimental pavement confirmed that the experimental pavement was comparable with conventional asphalt pavement, even superior to the later in some aspects. All of above test results and analysis had only one main purpose that this paper validated the opinion that using BOF slag in asphalt concrete is feasible. So this paper suggested that treated and tested steel slag should be used in a more extensive range, especially in asphalt mixture paving projects in such an abundant steel slag resource region. PMID:16982138

  14. Durability of Alkali Activated Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Ellis, K.; Alharbi, N.; Matheu, P. S.; Varela, B.; Hailstone, R.

    2015-11-01

    The alkali activation of blast furnace slag has the potential to reduce the environmental impact of cementitious materials and to be applied in geographic zones where weather is a factor that negatively affects performance of materials based on Ordinary Portland Cement. The scientific literature provides many examples of alkali activated slag with high compressive strengths; however research into the durability and resistance to aggressive environments is still necessary for applications in harsh weather conditions. In this study two design mixes of blast furnace slag with mine tailings were activated with a potassium based solution. The design mixes were characterized by scanning electron microscopy, BET analysis and compressive strength testing. Freeze-thaw testing up to 100 freeze-thaw cycles was performed in 10% road salt solution. Our findings included compressive strength of up to 100 MPa after 28 days of curing and 120 MPa after freeze-thaw testing. The relationship between pore size, compressive strength, and compressive strength after freeze-thaw was explored.

  15. Molybdate adsorption from steel slag eluates by subsoils.

    PubMed

    Matern, K; Rennert, T; Mansfeldt, T

    2013-11-01

    Steel slags are industrial by-products which are generated in large amounts worldwide, e.g. 150-230×10(6) Mg in 2012, and which are partly used for construction. Molybdenum (Mo) can be added during steel processing in order to harden the steel. The objective of this study was to evaluate the adsorption behaviour of molybdate (MoO4(2-)) from slag eluates in subsoils. Molybdate batch adsorption experiments were carried out with eluates obtained from two different kinds of steel slags (i) LD slag (Linz-Donawitz operation, LDS) and (ii) electric arc furnace slag (EAF) to assess the risk that may arise from the contamination of groundwater by the leaching of molybdate. Six different subsoils were chosen in order to provide a wide range of chemical properties (pH 4.0-7.6; dithionite-extractable Fe 0.73-14.7 g kg(-1)). Molybdate adsorption experiments were carried out at the pH of the steel slag eluates (pH 11-12) as well as at pH values adjusted to the soil pH. The data were evaluated with the Freundlich equation. Molybdate adsorption exhibited a maximum near pH 4 for steel slag eluates adjusted to the soil pH, and decreased rapidly with increasing pH until adsorption was virtually zero at pH>11. Adsorption was greater for soils with high amounts of dithionite-extractable Fe oxides. The extent and behaviour of molybdate adsorption from both eluates was similar. After a reaction time of 24h, the pH of the EAF slag eluate was lower than that of the LD steel slag eluate, which was caused by different acid buffer capacities. Some soils were able to decrease the pH of the EAF slag eluates by about 4 pH units, enhancing the adsorption of molybdate. Transport simulations indicated that molybdate discharge is low in acidic soils. PMID:23973286

  16. SEM evaluation of advanced refractory failures in slagging gasifiers

    SciTech Connect

    Collins, W.Keith; Dahlin, Cheryl L.; Bennett, James P.; Kwong, Kyei-Sing; Rawers, James C.

    2005-08-01

    The SEM is an invaluable tool in the evaluation of advanced refractories and their failure. A reaction vessel?s refractory liner, at minimum, must protect the reaction vessel from elevated temperatures, corrosive slag and thermal cycling. To understand the failure mechanisms ARC staff had first to determine how an advanced chrome rich refractory was attacked by various components that make up a slag. Refractory cups were made from the refractory of interest and various compounds that can be found in a slag such as CaO, SiO2, Fe2O3, NaCl were placed into the test cups and fired for 24 hours at the required temperature with the desired atmosphere. The cups are prepared for examination by embedding in epoxy and cross sectioning. SEM examination revealed how various slag compositions attacked and penetrated the refractory. The slag could corrode, free refractory grains or react with the refractory and from a new compound. It was found that the only way to measure slag component penetration was with multiple elemental X-ray maps. SiO2 penetrated deeply and in many instances moved through the cup. The knowledge of slag refractory interactions gather during cup testing was applied to actual spent refractory from reaction vessels. Obtaining samples from the reaction vessel itself proved difficult due to time constraints imposed in relining. Samples were selected based on spent brick shape, color or location in the heap of spent refractory. Sample preparation affected the results dry, water or oil coolant during cutting may dissolve reaction products. The complex reactions between the slag and refractory made for very interesting and time consuming evaluation. Elemental X-ray maps at low and high magnification combined with point analysis aided in locating regions of interest. Crystals were found growing in voids and appear to be from vapor deposition. Other crystal structures are from the slag refractory interaction. Knowledge gathered from this and other supporting

  17. New evidence for rejuvenation of phosphorus retention capacity in EAF steel slag.

    PubMed

    Drizo, Aleksandra; Cummings, John; Weber, David; Twohig, Eamon; Druschel, Greg; Bourke, Bill

    2008-08-15

    The purpose of this research was to investigate phosphorus (P) retention capacity and rejuvenation potential of electric arc furnace (EAF) steel slag from Quebec and New Zealand (NZ) iron melter slag (IMS). Columns filled with slag materials were fed with dairy effluent and subjected to two feeding and one resting cycle(s). P retention capacities and rejuvenation potentials were determined after each feeding cycle. Elemental composition and mineralogical analysis were performed on IMS samples. Finally, chemical fractionation analysis was conducted on both NZ IMS and Quebec EAF steel slags. The results revealed that initiating a resting period in EAF steel slag filters prior to reaching their P saturation point increased the overall filter P retention capacity by 49.5 and 42.4% compared to 28% in a filter which had its resting period initiated after reaching P saturation. The rejuvenation property could play a significant role in full-scale applications by prolonging life expectancy and increasing cost efficiency. P retention and rejuvenation by NZ slag materials was negligible relative to EAF steel slag material from Quebec. Chemical fractionation analysis revealed differences between materials, indicating that the highest quantities of P were bound to Ca and Fe in EAF steel slag and to Ca and Al fractions in iron melter slag. This study also demonstrates that slag's performance is dependent on the source of the material and the steel making practices. Therefore, testing of the P adsorptive capability and, if relevant, the rejuvenation potential of individual steel mill slags, should be a prerequisite prior to their use in field applications. PMID:18767686

  18. High conductance thermal interface concept for space applications

    NASA Technical Reports Server (NTRS)

    Poulin, Elizabeth C.; Horan, D. C.

    1991-01-01

    An interface concept has been developed which produces high conductance at a thermal/mechanical joint without resorting to high clamping forces or potentially contaminating fillers such as thermal grease. This paper discusses the characteristics of several variations of the high conductance interface concept and compares them to those of existing interface concepts proposed for several Space Station applications. The application of the high conductance concept to thermal joints such as internal coldplate interfaces and external equipment module to heat acquisition plate interfaces would reduce the weight and complexity and increase the efficiency of the Space Station Thermal Management System.

  19. Decontamination of metals by melt refining/slagging: First year progress report

    SciTech Connect

    Mizia, R.E.; Worcester, S.A.; Twidwell, L.G.; Paolini, D.J.; Weldon, T.A.

    1994-03-01

    As the number of nuclear installations undergoing decontamination and decommissioning (D&D) increases, current radioactive waste storage space is consumed and establishment of new waste storage areas becomes increasingly difficult. The problem of handling and storing radioactive scrap metal (RSM) gains increasing importance in the DOE Environmental Restoration and Waste Management Program. To alleviate present and future waste storage problems, Westinghouse Idaho Nuclear Company (WINCO) is managing a program for the recycling of RSM for beneficial use within the DOE complex. As part of that effort, Montana Tech has been awarded a contract to help optimize melting and refining technologies for the recycling of stainless steel RSM. The scope of the Montana Tech program includes a literature survey, a decontaminating slag design study, small scale melting studies to determine optimum slag compositions for removal of radioactive contaminant surrogates, analysis of preferred melting techniques, and coordination of pilot scale melting demonstrations (100-500 lbs) to be conducted at selected commercial facilities. This program will identify methods that can be used to recycle stainless steel RSM which will be used to fabricate high and low level waste canisters for the Idaho Waste Immobilization Facility. This report summarizes the results of an extensive literature review and the first year`s progress on slag design, small-scale melt refining of surrogate-containing stainless steel (presently only a three month effort), and pilot-scale preparation of surrogate master ingots.

  20. Corrosion resistant refractory ceramics for slagging gasifier environment

    SciTech Connect

    Medvedovski, E.; Chinn, Richard E.

    2004-01-01

    Integrated gasification combined cycle power systems are the most efficient and economical power generation systems with a relatively low environmental impact. The gasification process requires the optimal design of gasifiers with extremely corrosion resistant refractory lining. The majority of the refractory materials tested for gasifier lining applications cannot resist the action of slagging corrosive environment combined with high operation temperatures as high as 1600?C and possible thermal shocks and thermal expansion mismatch between the lining and the slag. Silicon carbide-based ceramics and some zirconia- and zircon-based ceramics manufactured by Ceramic Protection Corporation (CPC) have been tested in a simulated coal-fired slagging gasifier environment at a temperature of 1500?C. Crucible ceramic samples have been examined after exposure to the slag at high temperature. Microstructure studies of the ceramic zone contacted with the slag have been carried out. The highest performance, i.e. the absence of corrosion damage and thermal cracking after testing, was observed for silicon carbide-based ceramics ABSC formed by silicon carbide grains with an optimized particle size distribution bonded by the aluminosilicate crystalline-glassy matrix. Dense zirconia and alumina-zirconia and slightly porous zircon ceramics demonstrated comparatively lower performance due to their lower corrosion resistance and greater thermal cracking. ABSC ceramics can be manufactured as thick-walled large components and may be considered as a promising material for gasifier refractory applications. Similar ceramics, but with finer grain sizes, may also be recommended for thermocouple protection.

  1. Preparation of calcium silicate absorbent from iron blast furnace slag.

    PubMed

    Brodnax, L F; Rochelle, G T

    2000-09-01

    Calcium silicate hydrate (CSH) solids were prepared from hydrated lime and iron blast furnace slag in an aqueous agitated slurry at 92 degrees C. While it was hoped a minimal lime/slag ratio could be used to create near-amorphous CSH, the surface area of the product improved by increasing the lime/slag weight ratio to 2. The addition of gypsum to the lime/slag system dramatically improved the formation of surface area, creating solids with 139 m2/g after 30 hr of reaction when only a minimal amount of lime was present. The SO2 reactivity of solids prepared with gypsum greatly exceeded that of hydrated lime, achieving greater than 70-80% conversion of the alkalinity after 1 hr of reaction with SO2. The use of CaCl2 as an additive to the lime/slag system, in lieu of gypsum, also produced high-surface-area solids, 115 m2/g after 21 hr of reaction. However, the SO2 reactivity of these sorbents was relatively low given the high surface area. This emphasized that the correlation between surface area and SO2 reactivity was highly dependent on the solid phase, which was subsequently dependent on slurry composition. PMID:11055162

  2. Crystallization of synthetic coal-petcoke slag mixtures simulating those encountered in entrained bed slagging gasifiers

    SciTech Connect

    Jinichiro Nakano; Seetharaman Sridhar; Tyler Moss; James Bennett; Kyei-Sing Kwong

    2009-09-15

    Commercial entrained bed slagging gasifiers use a carbon feedstock of coal, petcoke, or combinations of them to produce CO and H{sub 2}. These carbon sources contain mineral impurities that liquefy during gasification and flow down the gasification sidewall, interacting with the refractory linear and solidifying in the cooler zones of the gasifier. Proper slag flow is critical to good gasifier operation. A hot-stage confocal scanning laser microscope (CSLM) was used to analyze the kinetic behavior of slag crystallization for a range of synthetic coal-petcoke mixtures. On the basis of the observed precipitation during cool down studies in the 1200-1700{sup o}C temperature range, a time-temperature-transformation (TTT) diagram was created. The crystallization studies were conducted with a CO/CO{sub 2} (=1.8) corresponding to a gasification PO{sub 2} of approximately 10-8 atm at 1500{sup o}C. Ash chemistries were chosen such that they correspond to coal-petcoke feedstock mixtures with coal ash amounts of 0, 10, 30, 50, 70, and 100% (by weight), with the balance being petcoke ash. The TTT diagram exhibited two crystallization areas, one above and one below 1350{sup o}C. At the nose of the higher temperature curves, karelianite (V{sub 2}O{sub 3}) crystallization occurred and was fastest for a 30% coal-petcoke ash mixture. The second nose was located below 1350{sup o}C and had spinel-type phases that formed at 1200{sup o}C, in which preferred atomic occupation at the octahedral and tetrahedral sites varied depending upon the ash composition. At 1200{sup o}C, an Al-rich spinel formed for 100% coal slag and a Fe-rich spinel formed in petcoke-enriched slags. The addition of petcoke ash to coal ash promoted crystallization in the slag, with additional crystalline phases, such as V-rich spinel, forming at the lower temperatures. These phases were not predicted using commercially available databases. 30 refs., 18 figs.

  3. High thermal conductivity lossy dielectric using a multi layer configuration

    DOEpatents

    Tiegs, Terry N.; Kiggans, Jr., James O.

    2003-01-01

    Systems and methods are described for loss dielectrics. A loss dielectric includes at least one high dielectric loss layer and at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer. A method of manufacturing a loss dielectric includes providing at least one high dielectric loss layer and providing at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer. The systems and methods provide advantages because the loss dielectrics are less costly and more environmentally friendly than the available alternatives.

  4. Slag-based saltstone formulations

    SciTech Connect

    Langton, C.A.

    1987-08-01

    Approximately 400 x 10/sup 6/ L of low-level alkaline salt solution will be treated at the Savannah River Plant (SRP) Defense Waste Processing Facility (DWPF) prior to disposal in concrete vaults at SRP. Treatment involves removal of Cs/sup +/ and Sr/sup +2/, followed by solidification and stabilization of potential contaminants in saltstone, a hydrated ceramic wasteform. Chromium, technetium, and nitrate releases from saltstone can be significantly reduced by substituting hydraulic blast furnace slag for portland cement in the formulation designs. Slag-based mixes are also compatible with the Class F flyash used in saltstone as a functional extender to control heat of hydration and reduce permeability. (Class F flyash is also locally available at SRP.) A monolithic wasteform is produced by the hydration of the slag and flyash. Soluble ion release (NO/sup 3 -/) is controlled by the saltstone microstructure. Chromium and technetium are less leachable from slag mixes because these species are chemically reduced to a lower valence state by ferrous iron in the slag and are precipitated as relatively insoluble phases, such as Cr(OH)/sub 3/ and TcO/sub 2/. 3 refs., 3 figs., 2 tabs.

  5. Slag-based saltstone formulations

    SciTech Connect

    Langton, C.A.

    1987-08-25

    Approximately 400 x 10/sup 6/ liters of low-level alkaline salt solution will be treated at the Savannah River Plant (SRP) Defense Waste Processing Facility (DWPF) prior to disposal in concrete vaults at SRP. Treatment involves removal of CS/sup +/ and Sr/sup +2/ followed by solidification and stabilization of potential contaminants in saltstone, a hydrated ceramic waste form. Chromium, technetium, and nitrate releases from saltstone can be significantly reduced by substituting hydraulic blast furnace slag for portland cement in the formulation designs. Slag-based mixes are also compatible with Class F fly ash used in saltstone as a functional extender to control heat of hydration and reduce permeability. A monolithic waste form is produced by the hydration of the slag and fly ash. Soluble ion release (NO/sub 3//sup -/) is controlled by the saltstone microstructure. Chromium and technetium are less leachable from slag mixes compared to cement-based waste forms because these species are chemically reduced to a lower valence state by ferrous iron in the slag and precipitated as relatively insoluble phases, such as CR(OH)/sub 3/ and TcO/sub 2/. 5 refs., 4 figs., 4 tabs.

  6. Humidifier for fuel cell using high conductivity carbon foam

    DOEpatents

    Klett, James W.; Stinton, David P.

    2006-12-12

    A method and apparatus of supplying humid air to a fuel cell is disclosed. The extremely high thermal conductivity of some graphite foams lends itself to enhance significantly the ability to humidify supply air for a fuel cell. By utilizing a high conductivity pitch-derived graphite foam, thermal conductivity being as high as 187 W/m.dot.K, the heat from the heat source is more efficiently transferred to the water for evaporation, thus the system does not cool significantly due to the evaporation of the water and, consequently, the air reaches a higher humidity ratio.

  7. Substrate pH and butterfly bush response to dolomitic lime or steel slag amendment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Steel slag is a fertilizer amendment with a high concentration of calcium oxide, and thus capable of raising substrate pH similar to dolomitic lime. Steel slag, however, contains higher concentrations of some nutrients, such as iron, manganese, and silicon, compared to dolomitic lime. The objectiv...

  8. Evaluation of electric arc furnace-processed steel slag for dermal corrosion, irritation, and sensitization from dermal contact.

    PubMed

    Suh, Mina; Troese, Matthew J; Hall, Debra A; Yasso, Blair; Yzenas, John J; Proctor, Debora M

    2014-12-01

    Electric arc furnace (EAF) steel slag is alkaline (pH of ~11-12) and contains metals, most notably chromium and nickel, and thus has potential to cause dermal irritation and sensitization at sufficient dose. Dermal contact with EAF slag occurs in many occupational and environmental settings because it is used widely in construction and other industrial sectors for various applications including asphaltic paving, road bases, construction fill, and as feed for cement kilns construction. However, no published study has characterized the potential for dermal effects associated with EAF slag. To assess dermal irritation, corrosion and sensitizing potential of EAF slag, in vitro and in vivo dermal toxicity assays were conducted based on the Organisation for Economic Co-operation and Development (OECD) guidelines. In vitro dermal corrosion and irritation testing (OECD 431 and 439) of EAF slag was conducted using the reconstructed human epidermal (RHE) tissue model. In vivo dermal toxicity and delayed contact sensitization testing (OECD 404 and 406) were conducted in rabbits and guinea pigs, respectively. EAF slag was not corrosive and not irritating in any tests. The results of the delayed contact dermal sensitization test indicate that EAF slag is not a dermal sensitizer. These findings are supported by the observation that metals in EAF slag occur as oxides of low solubility with leachates that are well below toxicity characteristic leaching procedure (TCLP) limits. Based on these results and in accordance to the OECD guidelines, EAF slag is not considered a dermal sensitizer, corrosive or irritant. PMID:24395402

  9. Highly conductive single naphthalene and anthracene molecular junction with well-defined conductance

    SciTech Connect

    Liu, Chenyang; Kaneko, Satoshi; Komoto, Yuki; Fujii, Shintaro Kiguchi, Manabu

    2015-03-09

    We performed electronic investigation on single acene molecular junctions bridging Au-electrodes in ultra-high vacuum conditions using mechanically controllable break junction technique. While the molecular junctions displayed various conductance values at 100 K, they exhibited well-defined high conductance values (∼0.3 G{sub 0}) at 300 K, which is close to that of metal atomic contact. Direct π-binding of the molecules to the Au-electrodes leads to the high conductivities at the metal-molecule interface. At the elevated temperature, single molecular junctions trapped in local metastable structures can be fallen into energetically preferential more stable state and thus we fabricated structurally well-defined molecular junctions.

  10. Fabrication Routes for High Strength High Conductivity Wires

    SciTech Connect

    Han, K.; Embury, J.D.; Sims, J.R.; Pantsyrnyi, V.I.; Shikov, A.; Bochvar, A.A.

    1998-10-01

    The development of suitable wires for magnet windings requires both the attainment of suitable combinations of properties (electrical conductivity and strength), the development of a production route capable of fabricating suitable quantity of wire of required dimension (5.2x7.6mm{sup 2} cross-section and 120 m in length) and a product with acceptable fabricability, joinability and service life. In this survey, the authors consider methods of producing suitable wire products by the codeformation of in-situ composites. This will include details of the quality control of the processing of Cu-Ag and Cu-Nb and the assessment of their detailed mechanical properties.

  11. High conductivity Be-Cu alloys for fusion reactors

    SciTech Connect

    Lilley, E.A.; Adachi, Takao; Ishibashi, Yoshiki

    1995-09-01

    The optimum material has not yet been identified. This will result in heat from plasma to the first wall and divertor. That is, because of cracks and melting by thermal power and shock. Today, it is considered to be some kinds of copper, alloys, however, for using, it must have high conductivity. And it is also needed another property, for example, high strength and so on. We have developed some new beryllium copper alloys with high conductivity, high strength, and high endurance. Therefore, we are introducing these new alloys as suitable materials for the heat sink in fusion reactors.

  12. High Thermal Conductivity Aligned Polyethylene-Graphene Nanocomposites

    NASA Astrophysics Data System (ADS)

    Garg, Jivtesh; Saeidijavash, Mortaza

    We investigate enhancement of thermal conductivity in polyethylene-graphene nanocomposites. The effect of alignment of both the polymer chains and the dispersed graphene flakes on thermal conductivity enhancement will be reported. In this work nanocomposites are prepared through microextrusion of polyethylene pellets and graphene nanopowder. Alignment is achieved through mechanical stretching of the nanocomposites. Thermal conductivity is measured using both Angstrom method and Laser flash. Variables involved in the study are the draw ratio and the weight percentage of graphene nanopowder. Results will shed light on the role of alignment of graphene flakes on enhancing thermal transport and provide new avenues to achieve ultra-high thermal conductivity in polymeric materials.

  13. Effective Thermal Conductivity of High Porosity Open Cell Nickel Foam

    NASA Technical Reports Server (NTRS)

    Sullins, Alan D.; Daryabeigi, Kamran

    2001-01-01

    The effective thermal conductivity of high-porosity open cell nickel foam samples was measured over a wide range of temperatures and pressures using a standard steady-state technique. The samples, measuring 23.8 mm, 18.7 mm, and 13.6 mm in thickness, were constructed with layers of 1.7 mm thick foam with a porosity of 0.968. Tests were conducted with the specimens subjected to temperature differences of 100 to 1000 K across the thickness and at environmental pressures of 10(exp -4) to 750 mm Hg. All test were conducted in a gaseous nitrogen environment. A one-dimensional finite volume numerical model was developed to model combined radiation/conduction heat transfer in the foam. The radiation heat transfer was modeled using the two-flux approximation. Solid and gas conduction were modeled using standard techniques for high porosity media. A parameter estimation technique was used in conjunction with the measured and predicted thermal conductivities at pressures of 10(exp -4) and 750 mm Hg to determine the extinction coefficient, albedo of scattering, and weighting factors for modeling the conduction thermal conductivity. The measured and predicted conductivities over the intermediate pressure values differed by 13%.

  14. Analyzing the Technology of Using Ash and Slag Waste from Thermal Power Plants in the Production of Building Ceramics

    NASA Astrophysics Data System (ADS)

    Malchik, A. G.; Litovkin, S. V.; Rodionov, P. V.; Kozik, V. V.; Gaydamak, M. A.

    2016-04-01

    The work describes the problem of impounding and storing ash and slag waste at coal thermal power plants in Russia. Recovery and recycling of ash and slag waste are analyzed. Activity of radionuclides, the chemical composition and particle sizes of ash and slag waste were determined; the acidity index, the basicity and the class of material were defined. The technology for making ceramic products with the addition of ash and slag waste was proposed. The dependencies relative to the percentage of ash and slag waste and the optimal parameters for baking were established. The obtained materials were tested for physical and mechanical properties, namely for water absorption, thermal conductivity and compression strength. Based on the findings, future prospects for use of ash and slag waste were identified.

  15. Distinctive microstructural features of aged sodium silicate-activated slag concretes

    SciTech Connect

    San Nicolas, Rackel; Bernal, Susan A.; Mejía de Gutiérrez, Ruby; Deventer, Jannie S.J. van; Provis, John L.

    2014-11-15

    Electron microscopic characterisation of 7-year old alkali-activated blast-furnace slag concretes enabled the identification of distinct microstructural features, providing insight into the mechanisms by which these materials evolve over time. Backscattered electron images show the formation of Liesegang-type ring formations, suggesting that the reaction at advanced age is likely to follow an Oswald supersaturation–nucleation–depletion cycle. Segregation of Ca-rich veins, related to the formation of Ca(OH){sub 2}, is observed in microcracked regions due to the ongoing reaction between the pore solution and available calcium from remnant slag grains. A highly dense and uniform interfacial transition zone is identified between siliceous aggregate particles and the alkali activated slag binders, across the concretes assessed. Alkali-activated slag concretes retain a highly dense and stable microstructure at advanced ages, where any microcracks induced at early ages seem to be partially closing, and the remnant slag grains continue reacting.

  16. High thermal conductivity connector having high electrical isolation

    DOEpatents

    Nieman, Ralph C.; Gonczy, John D.; Nicol, Thomas H.

    1995-01-01

    A method and article for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection. The connection method involves clamping, by thermal interference fit, an electrically isolating cylinder between an outer metallic ring and an inner metallic disk. The connection provides durable coupling of a heat sink and a heat source.

  17. Process for fabricating composite material having high thermal conductivity

    DOEpatents

    Colella, Nicholas J.; Davidson, Howard L.; Kerns, John A.; Makowiecki, Daniel M.

    2001-01-01

    A process for fabricating a composite material such as that having high thermal conductivity and having specific application as a heat sink or heat spreader for high density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper, and basically consists of coated diamond particles dispersed in a high conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process basically consists, for example, of sputter coating diamond powder with several elements, including a carbide forming element and a brazeable material, compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as copper-silver alloy, thereby producing a dense diamond-copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost.

  18. Flexible Fabrics with High Thermal Conductivity for Advanced Spacesuits

    NASA Technical Reports Server (NTRS)

    Trevino, Luis A.; Bue, Grant; Orndoff, Evelyne; Kesterson, Matt; Connel, John W.; Smith, Joseph G., Jr.; Southward, Robin E.; Working, Dennis; Watson, Kent A.; Delozier, Donovan M.

    2006-01-01

    This paper describes the effort and accomplishments for developing flexible fabrics with high thermal conductivity (FFHTC) for spacesuits to improve thermal performance, lower weight and reduce complexity. Commercial and additional space exploration applications that require substantial performance enhancements in removal and transport of heat away from equipment as well as from the human body can benefit from this technology. Improvements in thermal conductivity were achieved through the use of modified polymers containing thermally conductive additives. The objective of the FFHTC effort is to significantly improve the thermal conductivity of the liquid cooled ventilation garment by improving the thermal conductivity of the subcomponents (i.e., fabric and plastic tubes). This paper presents the initial system modeling studies, including a detailed liquid cooling garment model incorporated into the Wissler human thermal regulatory model, to quantify the necessary improvements in thermal conductivity and garment geometries needed to affect system performance. In addition, preliminary results of thermal conductivity improvements of the polymer components of the liquid cooled ventilation garment are presented. By improving thermal garment performance, major technology drivers will be addressed for lightweight, high thermal conductivity, flexible materials for spacesuits that are strategic technical challenges of the Exploration

  19. Highly conducting graphene sheets and Langmuir-Blodgett films

    NASA Astrophysics Data System (ADS)

    Li, Xiaolin; Zhang, Guangyu; Bai, Xuedong; Sun, Xiaoming; Wang, Xinran; Wang, Enge; Dai, Hongjie

    2008-09-01

    Graphene is an intriguing material with properties that are distinct from those of other graphitic systems. The first samples of pristine graphene were obtained by `peeling off' and epitaxial growth. Recently, the chemical reduction of graphite oxide was used to produce covalently functionalized single-layer graphene oxide. However, chemical approaches for the large-scale production of highly conducting graphene sheets remain elusive. Here, we report that the exfoliation-reintercalation-expansion of graphite can produce high-quality single-layer graphene sheets stably suspended in organic solvents. The graphene sheets exhibit high electrical conductance at room and cryogenic temperatures. Large amounts of graphene sheets in organic solvents are made into large transparent conducting films by Langmuir-Blodgett assembly in a layer-by-layer manner. The chemically derived, high-quality graphene sheets could lead to future scalable graphene devices.

  20. A High Conducting Oxide Sulfide Composite Lithium Superionic Conductor

    SciTech Connect

    Rangasamy, Ezhiylmurugan; Keum, Jong Kahk; Sahu, Gayatri; Rondinone, Adam Justin; Dudney, Nancy J; Liang, Chengdu

    2014-01-01

    A hybrid superionic conductor was fabricated utilizing the space charge effect between the LLZO and LPS interfaces. This space-charge effect resulted in an improvement over the individual bulk conductivities of the two systems. Sample with higher weight fractions of LLZO are limited by the porosity and grain boundary resistance arising from non-sintered membranes. By combining the properties of LLZO and LPS, the high temperature sintering step has been avoided thus facilitating easier materials processing. The interfacial resistances were also measured to be minimal at ambient conditions. This procedure thus opens a new avenue for improving the ionic conductivity and electrochemical properties of existing solid state electrolytes. High frequency impedance analyses could aid in resolving the ionic conductivity contributions from the space charge layer in the higher conducting composites while mechanical property investigations could illustrate an improvement in the composite electrolyte in comparison with the crystalline LPS membranes.

  1. Electrically Joining Mixed Conducting Oxides for High Temperature Applications

    SciTech Connect

    Weil, K. Scott; Hardy, John S.

    2003-01-06

    Mixed conducting oxides such as lanthanum strontium cobalt ferrite are currently being investigated for potential use as electrochemically active electrodes and catalytic membranes in a number of high temperature devices, including oxygen generators and solid oxide fuel cells (SOFC). However to take full advantage of the unique properties of these materials, reliable joining techniques need to be developed. What complicates joining in these applications is the requirement that the ceramic-to-metal junction be electrically conductive, so that current can either be drawn from the mixed conducting oxide, in the case of SOFC applications, or be carried to the oxide to initate ionic conduction, as required for oxygen separation and electrocatalysis. This paper outlines a new technique that is being developed to electrically join an oxide conductor to a metal current collector for high temperature electrochemical application.

  2. Highly anisotropic thermal conductivity of arsenene: An ab initio study

    NASA Astrophysics Data System (ADS)

    Zeraati, Majid; Vaez Allaei, S. Mehdi; Abdolhosseini Sarsari, I.; Pourfath, Mahdi; Donadio, Davide

    2016-02-01

    Elemental two-dimensional (2D) materials exhibit intriguing heat transport and phononic properties. Here we have investigated the lattice thermal conductivity of newly proposed arsenene, the 2D honeycomb structure of arsenic, using ab initio calculations. Solving the Boltzmann transport equation for phonons, we predict a highly anisotropic thermal conductivity of 30.4 and 7.8 W/mK along the zigzag and armchair directions, respectively, at room temperature. Our calculations reveal that phonons with mean free paths between 20 nm and 1 μ m provide the main contribution to the large thermal conductivity in the zigzag direction; mean free paths of phonons contributing to heat transport in the armchair directions range between 20 and 100 nm. The obtained anisotropic thermal conductivity and feasibility of synthesis, in addition to high electron mobility reported elsewhere, make arsenene a promising material for nanoelectronic applications and thermal management.

  3. Design of a continuous process setup for precipitated calcium carbonate production from steel converter slag.

    PubMed

    Mattila, Hannu-Petteri; Zevenhoven, Ron

    2014-03-01

    A mineral carbonation process "slag2PCC" for carbon capture, utilization, and storage is discussed. Ca is extracted from steel slag by an ammonium salt solvent and carbonated with gaseous CO2 after the separation of the residual slag. The solvent is reused after regeneration. The effects of slag properties such as the content of free lime, fractions of Ca, Si, Fe, and V, particle size, and slag storage on the Ca extraction efficiency are studied. Small particles with a high free-lime content and minor fractions of Si and V are the most suitable. To limit the amount of impurities in the process, the slag-to-liquid ratio should remain below a certain value, which depends on the slag composition. Also, the design of a continuous test setup (total volume ∼75 L) is described, which enables quick process variations needed to adapt the system to the varying slag quality. Different precipitated calcium carbonate crystals (calcite and vaterite) are generated in different parts of the setup. PMID:24578147

  4. Physico-chemical characterization of steel slag. Study of its behavior under simulated environmental conditions.

    PubMed

    Navarro, Carla; Díaz, Mario; Villa-García, María A

    2010-07-15

    The chemical and mineralogical composition of steel slag produced in two ArcelorMittal steel plants located in the North of Spain, as well as the study of the influence of simulated environmental conditions on the properties of the slag stored in disposal areas, was carried out by elemental chemical analysis, XRF, X-ray diffraction, thermal analysis, and scanning electron microscopy with EDS analyzer. Spectroscopic characterization of the slag was also performed by using FTIR spectroscopy. Due to the potential uses of the slag as low cost adsorbent for water treatment and pollutants removal, its detailed textural characterization was carried out by nitrogen adsorption-desorption at 77 K and mercury intrusion porosimetry. The results show that the slag is a crystalline heterogeneous material whose main components are iron oxides, calcium (magnesium) compounds (hydroxide, oxide, silicates, and carbonate), elemental iron, and quartz. The slags are porous materials with specific surface area of 11 m(2)g(-1), containing both mesopores and macropores. Slag exposure to simulated environmental conditions lead to the formation of carbonate phases. Carbonation reduces the leaching of alkaline earth elements as well as the release of the harmful trace elements Cr (VI) and V. Steel slags with high contents of portlandite and calcium silicates are potential raw materials for CO(2) long-term storage. PMID:20568743

  5. Thermodynamics of Indium Dissolution Behavior in FeO-Bearing Metallurgical Slags

    NASA Astrophysics Data System (ADS)

    Han, Yun Soon; Park, Joo Hyun

    2015-02-01

    Indium solubility in the FeO-SiO2-Al2O3-5CaO-MgOsat slag system was measured at 1573 K (1300 °C) to confirm the thermodynamic dissolution behavior of indium at atm. The indium solubility in FeO-bearing slags increased with increasing oxygen partial pressure and decreased with increasing basicity which is in proportion to the activity of FeO. The dissolution of indium in FeO-bearing slags was confirmed to progress according to the following reaction: The enthalpy change for the dissolution of indium in FeO-bearing slag was about -181 kJ/mol, indicating that indium dissolution is exothermic. The indium solubility in the FeO-SiO2-Al2O3-5CaO-MgOsat slag system was minimized as a function of alumina content at a given FeO/SiO2 ratio, which can be explained by the amphoteric behavior of Al2O3 in the slag system. To improve indium recovery by lowering indium loss to the slag phase during the pyro-recycling of In-containing materials using FeO-bearing metallurgical slags, a lower oxygen potential and lower silica content are highly favorable.

  6. Study of Phase Relations of ZnO-Containing Fayalite Slag Under Fe Saturation

    NASA Astrophysics Data System (ADS)

    Shi, Huayue; Chen, Liugang; Malfliet, Annelies; Jones, Peter Tom; Blanpain, Bart; Guo, Muxing

    2016-06-01

    A ZnO-containing fayalite-based slag can be formed in copper smelting from secondary raw materials and its high viscosity is a common issue that hinders slag tapping. In this work, the crystallization behavior of the industrial slag was observed in situ by confocal laser scanning microscopy. Solid precipitation was found to be the major cause of the poor slag fluidity. The phase relations in the industrial slag system ZnO-"FeO"-SiO2-Al2O3-CaO (CaO/SiO2 = 0.05, Al2O3/SiO2 = 0.15) were investigated by quenching the samples after reaching equilibrium at 1423 K (1150 °C) under iron saturation. The equilibrium composition of the phases was determined with electron probe micro-analysis. The effect of individual components, such as FeO, ZnO, and CaO on the phase equilibrium of the slag system has been quantitatively studied. The relation between the solid-phase fraction and the chemical composition of the slag has been revealed. Suggestions to modify the slag composition toward low viscosity are provided.

  7. Dissolutive Wetting and Spreading Phenomena Between Al2O3 Substrate and CaO-Al2O3 Liquid Slags

    NASA Astrophysics Data System (ADS)

    Kim, Seonjin; Lee, Kyuyong; Chung, Yongsug

    2016-04-01

    The wetting and spreading behavior are influenced by the dissolution reaction. The wetting and spreading behavior between CaO-Al2O3 slag and Al2O3 substrate were investigated using the dispensed drop technique and a high speed camera (1000 frame/s) at 1823 K (1550 °C) using saturated slag and non-saturated slag on Al2O3. The contact angle of the saturated slag and the non-saturated slag was not substantially different. The apparent height of the spreading droplet for the non-saturated slag was lower than that of the saturated slag due to the formation of a crater generated by the dissolution reaction. A spherical cap model is associated with crater formation was suggested by analyzing the spread droplet and a quenched sample. The spreading rate of the non-saturated slag was faster than that of the saturated slag due to convection. For the saturated slag, the experimental values are in good agreement with the De Gennes's theoretical model. (Non-reactive viscous model) In contrast, the non-saturated slag curve shifts the experimental curve to correspond with the saturated slag curve.

  8. Conductance saturation in a series of highly transmitting molecular junctions

    NASA Astrophysics Data System (ADS)

    Yelin, T.; Korytár, R.; Sukenik, N.; Vardimon, R.; Kumar, B.; Nuckolls, C.; Evers, F.; Tal, O.

    2016-04-01

    Revealing the mechanisms of electronic transport through metal-molecule interfaces is of central importance for a variety of molecule-based devices. A key method for understanding these mechanisms is based on the study of conductance versus molecule length in molecular junctions. However, previous works focused on transport governed either by coherent tunnelling or hopping, both at low conductance. Here, we study the upper limit of conductance across metal-molecule-metal interfaces. Using highly conducting single-molecule junctions based on oligoacenes with increasing length, we find that the conductance saturates at an upper limit where it is independent of molecule length. With the aid of two prototype systems, in which the molecules are contacted by either Ag or Pt electrodes, we find two different possible origins for conductance saturation. The results are explained by an intuitive model, backed by ab initio calculations. Our findings shed light on the mechanisms that constrain the conductance of metal-molecule interfaces at the high-transmission limit.

  9. Glasslike Heat Conduction in High-Mobility Crystalline Semiconductors

    NASA Astrophysics Data System (ADS)

    Cohn, J. L.; Nolas, G. S.; Fessatidis, V.; Metcalf, T. H.; Slack, G. A.

    1999-01-01

    The thermal conductivity of polycrystalline semiconductors with type-I clathrate hydrate crystal structure is reported. Ge clathrates (doped with Sr and/or Eu) exhibit lattice thermal conductivities typical of amorphous materials. Remarkably, this behavior occurs in spite of the well-defined crystalline structure and relatively high electron mobility ( ~100 cm2/V s). The dynamics of dopant ions and their interaction with the polyhedral cages of the structure are a likely source of the strong phonon scattering.

  10. High conductivity magnetic tearing instability. [of neutral plasma sheets

    NASA Technical Reports Server (NTRS)

    Cross, M. A.; Van Hoven, G.

    1976-01-01

    Linearized equations of magnetohydrodynamics are used to investigate the tearing mode, for arbitrary values of the conductivity, through a consideration of the additional effect of the electron-inertia contribution to Ohm's law. A description is provided of the equilibrium and subsequent instability in the magnetohydrodynamic approximation. A method for solving the perturbation equations in the linear approximation is discussed and attention is given to the results in the high conductivity limit.

  11. Rapid Dissolution of Quicklime into Molten Slag by Internally Formed Gas

    NASA Astrophysics Data System (ADS)

    Maruoka, Nobuhiro; Nogami, Hiroshi

    2016-07-01

    In steelmaking process, quicklime is used to produce CaO-based slag. Although rapid dissolution of quicklime is required for high-efficiency refining, it is known that the rate decreases when dicalcium silicate (C2S) layer forms around the quicklime by reacting with slag. The equation that driving force is the difference of CaO content between in slag and a liquid phase of slag saturated by C2S has been often used for estimating the dissolution rate of lime, in which this saturated value is thermodynamically determined. The authors, however, revealed that the quicklime used in actual operation showed much faster dissolving rate than that of completely calcined lime that is covered by C2S layer during dissolution into slag. This was caused by a gas formation due to a thermal decomposition of residual limestone existed in quicklime. In this study, the dissolution rate of quicklime with the gas formation is quantitatively investigated.

  12. Utilization of lightweight materials made from coal gasification slags. Quarterly report, September 15--November 30, 1994

    SciTech Connect

    1997-07-01

    Coal gasification technologies are finding increasing commercial applications for power generation or production of chemical feedstocks. The integrated-gasification-combined-cycle (IGCC) coal conversion process has been demonstrated to be a clean, efficient, and environmentally acceptable method of generating power. However, the gasification process produces relatively large quantities of a solid waste termed slag. Regulatory trends with respect to solid waste disposal, landfill development costs, and public concern make utilization of slag a high-priority issue. Therefore, it is imperative that slag utilization methods be developed, tested, and commercialized in order to offset disposal costs. This project aims to demonstrate the technical and economic viability of the slag utilization technologies developed by Praxis to produce lightweight aggregates (LWA) and ultra-lightweight aggregates (ULWA) from slag in a large-scale pilot operation, followed by total utilization of these aggregates in a number of applications.

  13. Development of a Novel Titania Slag Upgrading Process Using Titanium Tetrachloride

    NASA Astrophysics Data System (ADS)

    Kang, Jungshin; Okabe, Toru H.

    2016-02-01

    In order to remove iron from titania slag for the production of high-grade titanium dioxide (TiO2), a novel slag upgrading process was developed based on a selective chlorination method. In the experiments, various types of suitably pretreated slag reacted with titanium tetrachloride (TiCl4) as a chlorinating agent at 1100 K (827 °C) for 5 hours in the presence of carbon. Once the reaction had reached completion, the iron in the slags was selectively removed as iron chloride (FeCl2) in a dry form. As a result, the mass percent of iron decreased from 13.9 to 0.21 pct (nominal, excluding oxygen) and the mass percent of titanium increased from 78.1 to 96.0 pct (nominal, excluding oxygen) under certain conditions. Therefore, this selective chlorination process using TiCl4 is considered a feasible approach for the upgrading of titania slag.

  14. Conductivity Analysis of Membranes for High-Temperature PEMFC Applications

    SciTech Connect

    Reed, R.; Turner, J.A.

    2005-01-01

    Low-temperature operation requirements for per-fluorinated membranes are one factor that limits the viability of current fuel cell technology for transportation and other uses. Because of this, high-temperature membrane materials are being researched. The protonic conductivity of organic/inorganic hybrid composites, Nafion® analog material, and heteropoly acid doped Nafion membranes were studied using a BekkTech® conductivity test cell as a hydrogen pump. The goal was to find a high-temperature membrane with sufficient enough conductive properties to replace the currently implemented low-temperature membranes, such as Nafion. Four-point conductivity measurements were taken using a hydrogen pump experiment. Results showed that one of the organic/inorganic membranes that we tested had similar protonic conductivity to Nafion. Nafion analog membranes were shown to have similar to slightly better conductivity than Nafion at high-temperatures. However, like Nafion, performance dropped upon dehydration of the membrane at higher temperatures. Of the heteropoly acid doped Nafion membranes studied, silicotungstic acid was found to be, overall, the most promising for use as a dopant.

  15. Synthetic Coal Slag Infiltration into Varying Refractory Materials

    SciTech Connect

    Kaneko, Tetsuya K; Thomas, Hugh; Bennett, James P; Sridhar, Seetharaman

    2012-10-01

    The infiltrations of synthetic coal slag into 99%Al{sub 2}O{sub 3}, 85%Al{sub 2}O{sub 3}–15%SiO{sub 2}, and 90%Cr{sub 2}O{sub 3}–10%Al{sub 2}O{sub 3} refractories with a temperature gradient induced along the penetration direction were compared to one another. The infiltrating slag was synthesized with a composition that is representative of an average of the ash contents from U S coal feedstock. Experiments were conducted with a hot-face temperature of 1450°C in a CO/CO{sub 2} atmosphere. Minimal penetration was observed in the 90%Cr{sub 2}O{sub 3}–10%Al{sub 2}O{sub 3} material because interactions between the refractory and the slag produced a protective layer of FeCr{sub 2}O{sub 4}, which impeded slag flow into the bulk of the refractory. After 5 h, the 99%Al{sub 2}O{sub 3} sample exhibited an average penetration of 12.7 mm whereas the 85%Al{sub 2}O{sub 3}–15%SiO{sub 2} sample showed 3.8 mm. Slag infiltrated into the 99%Al{sub 2}O{sub 3} and 85%Al{sub 2}O{sub 3}–15%SiO{sub 2} refractory systems by dissolving the respective refractories' matrix materials, which consist of fine Al{sub 2}O{sub 3} particles and an amorphous alumino-silicate phase. Due to enrichment in SiO{sub 2}, a network-former, infiltration into the 85%Al{sub 2}O{sub 3}–15%SiO{sub 2} system yielded a higher viscosity slag and hence, a shallower penetration depth. The results suggest that slag infiltration can be limited by interactions with the refractory through the formation of either a solid layer that physically impedes fluid flow or a more viscous slag that retards infiltration.

  16. Effect of Slag on Titanium, Silicon, and Aluminum Contents in Superalloy During Electroslag Remelting

    NASA Astrophysics Data System (ADS)

    Jiang, Zhou-Hua; Hou, Dong; Dong, Yan-Wu; Cao, Yu-Long; Cao, Hai-Bo; Gong, Wei

    2016-04-01

    Many factors influence the chemical composition in electroslag remelting (ESR) steel, including atmosphere in crucible, melting rate, slag composition, deoxidation, and so on. Fluoride-based slag, which is exposed to liquid metal directly, influences the chemical composition of ESR ingots to a large extent. The present paper focuses on the effect of slag on the titanium, silicon, and aluminum contents in ingots based on the interaction of the slag and metal. In present work, superalloy of GH8825 and several slags containing different CaO contents have been employed for investigating the effect of slag on titanium, silicon, and aluminum contents in an electrical resistance furnace under argon atmosphere. Results indicate that the higher CaO content in slag has better capacity for avoiding loss of titanium caused by the reaction of titanium with silica in slag, especially in case of remelting superalloy with high titanium and low silicon content. The CaO has a great effect on the activities of TiO2, SiO2, and Al2O3. Thermodynamic analysis is applied to investigate the CaO behavior. Based on the ion and molecule coexistence theory of slag, activity model is established to calculate the activities of components containing titanium, silicon, and aluminum elements in a six-component slag consisting of CaO-CaF2-Al2O3-SiO2-TiO2-MgO. The components containing titanium, silicon, and aluminum in slag are mainly CaO·TiO2, 2CaO·SiO2, CaO·SiO2, CaO·Al2O3, and MgO·Al2O3. With the increase of CaO mass fraction in slag, the activity coefficient of SiO2 decreases significantly, whereas slightly change happens for Al2O3. As a result, the lg ({{γ_{{{{SiO}}2 }} } {/ {{{γ_{{{{SiO}}2 }} } {γ_{{{{TiO}}2 }} }}} {γ_{{{{TiO}}2 }} }}) decreases with increasing CaO content, which is better for preventing loss of titanium caused by the reaction of titanium with silica in slag. The slag with high CaO and appropriate TiO2 content is suitable for electroslag remelting of GH8825.

  17. Mechanisms of pyrite oxidation to non-slagging species. Quarterly report, April 1, 1996 - June 30, 1996

    SciTech Connect

    Das, K.; Akan-Etuk, A.E.J.; Mitchell, R.E.

    1996-12-01

    This document is the eighth quarterly status report on a project that is conducted at the High Temperature Gasdynamics Laboratory at Stanford University, Stanford, California and is concerned with enhancing the transformation of iron pyrite to non-slagging species during staged, low-NO{sub x} pulverized coal (P. C.) combustion. In general, the project has the following objectives: (1) the characterization of the various mechanisms of intraparticle mass transfer and chemical reaction that control overall pyrite combustion rates and (2) the synthesis of the reaction rate resistances of the various mechanisms into a general rate expression for pyrite combustion. The knowledge gained from this project will be incorporated into numerical codes and utilized to formulate slagging abatement strategies involving the minor adjustment of firing conditions. Ultimately, the benefit of this research program is intended to be an increase in the range of coals compatible with staged, low-NO{sub X} combustor retrofits.

  18. Survey of Processing Methods for High Strength High Conductivity Wires for High Field Magnet Applications

    SciTech Connect

    Han, K.; Embury, J.D.

    1998-10-01

    This paper will deal with the basic concepts of attaining combination of high strength and high conductivity in pure materials, in-situ composites and macrocomposites. It will survey current attainments, and outline where some future developments may lie in developing wire products that are close to the theoretical strength of future magnet applications.

  19. Study on Control of Inclusion Compositions in Tire Cord Steel by Low Basicity Top Slag

    NASA Astrophysics Data System (ADS)

    Xin, Cai-ping; Yue, Feng; Jiang, Chen-xu; Wu, Qi-fan

    2016-01-01

    Top slag melting experiment was conducted in a silicon molybdenum furnace with tire cord steel billet. The influence of top slag composition on the plasticity of CaO-Al2O3-SiO2-MgO inclusion and inclusion plasticization conditions was calculated by thermodynamic software FactSage. Use the thermodynamic calculation to guide the laboratory experiments to study slag compositions influence inclusions composition. Then industrial experiments were conducted based on the theoretical calculation and results of laboratory experiments. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to determine the morphology and composition of inclusions in steel. All studies show that in the CaO-Al2O3-SiO2-10% MgO diagram, when CaO = 8-48%, SiO2 = 35-75%, Al2O3 = 0-32%, inclusions are in the plastic area. When basicity of top slag is certain, Al2O3 content in inclusions increases with the increase of Al2O3 content in the slag, and the distribution of inclusions becomes scattered with the increase of Al2O3 content in slag. Inclusion plasticization can be achieved when the binary basicities of top slag are 0.6, 0.8-1.2, 1.4 and corresponding w(Al2O3)s are 2-15%, 2-10%, <2%. According to industrial experimental results, when top slag basicity decreases from 1.5 to 0.67-0.9 and Al2O3 content decreases below 10 wt%, the inclusion falls into plastic area. It is feasible in practice to control the CaO-Al2O3-SiO2-MgO inclusions plastic through adjusting Al2O3 content in slag.

  20. Thermal Conductivity Measurements in Metals at High Pressures and Temperatures.

    NASA Astrophysics Data System (ADS)

    Konopkova, Z.; McWilliams, R. S.; Goncharov, A.

    2014-12-01

    The transport properties of iron and iron alloys at high pressures and temperatures are crucial parameters in planetary evolution models, yet are difficult to determine both theoretically and experimentally. Estimates of thermal conductivity in the Earth's core range from 30 to 150 W/mK, a substantial range leaving many open questions regarding the age of the inner core, the thermal structure of the outer core, and the conditions for a working geodynamo. Most experiments have measured electrical resistivity rather than directly measuring thermal conductivity, and have used models to extrapolate from low-temperature data to the high temperature conditions of the core. Here we present direct, in-situ high-pressure and high-temperature measurements of the thermal conductivity of metals in the diamond-anvil cell. Double-sided continuous laser heating is combined with one-side flash heating of a metallic foil, while the time-resolved temperature is measured from both sides with spectral radiometry in an optical streak camera. Emission and temperature perturbations measured on opposite sides of the foil were modeled using finite element calculations in order to extract thermal diffusivity and conductivity of foils. Results on platinum and iron at high pressures and temperatures will be presented.

  1. Interpretation of the high conductive anomaly of the Society hotspot

    NASA Astrophysics Data System (ADS)

    Tada, Noriko; Tarits, Pascal; Baba, Kiyoshi; Utada, Hisashi; Suetsugu, Daisuke

    2016-04-01

    The mantle upwellings are one of the most important features for understanding the mantle dynamics. A large-scale mantle upwelling beneath the French Polynesia region in the South Pacific has been suggested from seismic studies, which is called the South Pacific superplume, and a slow velocity anomaly continues from the core mantle boundary to the upper mantle just beneath the Society hotspot (e.g., Suetsugu et al., 2009). However, the previous studies are not enough to understand the geometry, temperature, and composition of the Society hotspot. Then, we carried out the TIARES project that composed of multi-sensor stations that include broadband ocean bottom seismometers, ocean bottom electromagnetometers (OBEMs), and differential pressure gauges from 2009 to 2010 (Suetsugu et al., 2012). We have analyzed marine magnetotelluric data obtained totally 20 sites around the Society hotspot, and revealed a three-dimensional shaped high conductive anomaly, like a thumb, beneath the Society hotspot (see detail in session GD8.3/EMRP4.9/SM7.6). In order to clarify the cause of the high conductivity, water content, melt fraction, and H2O and CO2 contents in the upper mantle were estimated by adopting results of rock experiments at high temperatures and pressures. As a result, the upper mantle in the high conductive anomaly involves more water, melt, H2O, and CO2 rather than that in the surrounding area. Furthermore, temperature of high conductive anomaly might be higher than the surrounding area.

  2. High conductivity, low cost aluminum composite for thermal management

    SciTech Connect

    Sommer, J.L.

    1997-04-01

    In order to produce an inexpensive packaging material that exhibits high thermal conductivity and low CTE, Technical Research Associates, Inc. (TRA) has shown in Phase I the feasibility of incorporating natural flake graphite in an aluminum matrix. TRA has developed a proprietary coating technique where graphite flakes have been coated with a thin layer of molybdenum/molybdenum carbide (approximately 0.2 microns). This barrier coating can protect the graphite flake from chemical reaction and high temperature degradation in molten aluminum silicon alloys. Methods to successfully vacuum infiltrate coated flake with molten aluminum alloys were developed. The resulted metal matrix composites exhibited lower CTE than aluminum metal. The CTE of the composites were significantly lower than aluminum and its alloys. The CTE can potentially be tailored for specific applications. The in plane thermal conductivity was higher than the aluminum matrix alloy. The thermal conductivity and CTE of the composite may be significantly improved by improving the bond strength of the molybdenum coating on the graphite flake. The flake can potentially be incorporated in the molten aluminum and pressure die cast to align the flakes within the aluminum matrix. By preferentially aligning high conductivity graphite flakes within a plane or direction, the thermal conductivity of the resulting composite will be above pure aluminum in the alignment direction.

  3. Strength of VGCF/Al Composites for High Thermal Conductivity

    NASA Astrophysics Data System (ADS)

    Fukuchi, Kohei; Sasaki, Katsuhiko; Imanishi, Terumitsu; Katagiri, Kazuaki; Kakitsuji, Atsushi; Shimizu, Akiyuki

    In this paper, the evaluation of the strength of the VGCF/Aluminum composites which have high thermal conductivity is reported. VGCF (Vapor Growth Carbon Fiber) is a kind of the Carbon nanotube (CNT) which has very high thermal conductivity as well as CNT. The composites are made by spark plasma sintering. The stress-strain curves of the composites are obtained by the tensile tests and show that the composites have brittle behavior. The brittleness of the composites increases with increase in the volume fraction of VGCF. A numerical simulation based on the micromechanics is conducted to estimate nonlinear behavior in the elastic deformation and plastic deformation of the stress-strain relations of the composites. The theories of Eshelby, Mori-Tanaka, Weibull, and Ramberg-Osgood are employed for the numerical simulation. The simulations give some information of the microstructural change in the composite related to the volume fraction of VGCF.

  4. Hybrid electrokinetic manipulation in high-conductivity media.

    PubMed

    Gao, Jian; Sin, Mandy L Y; Liu, Tingting; Gau, Vincent; Liao, Joseph C; Wong, Pak Kin

    2011-05-21

    This study reports a hybrid electrokinetic technique for label-free manipulation of pathogenic bacteria in biological samples toward medical diagnostic applications. While most electrokinetic techniques only function in low-conductivity buffers, hybrid electrokinetics enables effective operation in high-conductivity samples, such as physiological fluids (∼1 S m(-1)). The hybrid electrokinetic technique combines short-range electrophoresis and dielectrophoresis, and long-range AC electrothermal flow to improve its effectiveness. The major technical hurdle of electrode instability for manipulating high conductivity samples is tackled by using a Ti-Au-Ti sandwich electrode and a 3-parallel-electrode configuration is designed for continuous isolation of bacteria. The device operates directly with biological samples including urine and buffy coats. We show that pathogenic bacteria and biowarfare agents can be concentrated for over 3 orders of magnitude using hybrid electrokinetics. PMID:21487576

  5. Ultralow thermal conductivity in highly anion-defective aluminates.

    PubMed

    Wan, Chunlei; Qu, Zhixue; He, Yong; Luan, Dong; Pan, Wei

    2008-08-22

    Ultralow thermal conductivity (1.1 W/m.K, 1000 degrees C) in anion-deficient Ba2RAlO5 (R=Dy, Er, Yb) compounds was reported. The low thermal conductivity was then analyzed by kinetic theory. The highly defective structure of Ba2RAlO5 results in weak atomic bond strength and low sound speeds, and phonon scattering by large concentration of oxygen vacancies reduces the phonon mean free path to the order of interatomic distance. Ba2DyAlO5 exhibits the shortest phonon mean free path and lowest thermal conductivity among the three compositions investigated, which can be attributed to additional phonon scattering by DyO6 octahedron tilting as a result of a low tolerance factor. The Ba2RAlO5 (R=Dy, Er, Yb) compounds have shown great potential in high-temperature thermal insulation applications, particularly as a thermal barrier coating material. PMID:18764638

  6. Engineering Graphene Conductivity for Flexible and High-Frequency Applications.

    PubMed

    Samuels, Alexander J; Carey, J David

    2015-10-14

    Advances in lightweight, flexible, and conformal electronic devices depend on materials that exhibit high electrical conductivity coupled with high mechanical strength. Defect-free graphene is one such material that satisfies both these requirements and which offers a range of attractive and tunable electrical, optoelectronic, and plasmonic characteristics for devices that operate at microwave, terahertz, infrared, or optical frequencies. Essential to the future success of such devices is therefore the ability to control the frequency-dependent conductivity of graphene. Looking to accelerate the development of high-frequency applications of graphene, here we demonstrate how readily accessible and processable organic and organometallic molecules can efficiently dope graphene to carrier densities in excess of 10(13) cm(-2) with conductivities at gigahertz frequencies in excess of 60 mS. In using the molecule 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane (F2-HCNQ), a high charge transfer (CT) of 0.5 electrons per adsorbed molecule is calculated, resulting in p-type doping of graphene. n-Type doping is achieved using cobaltocene and the sulfur-containing molecule tetrathiafulvalene (TTF) with a CT of 0.41 and 0.24 electrons donated per adsorbed molecule, respectively. Efficient CT is associated with the interaction between the π electrons present in the molecule and in graphene. Calculation of the high-frequency conductivity shows dispersion-less behavior of the real component of the conductivity over a wide range of gigahertz frequencies. Potential high-frequency applications in graphene antennas and communications that can exploit these properties and the broader impacts of using molecular doping to modify functional materials that possess a low-energy Dirac cone are also discussed. PMID:26387636

  7. Free-standing nanocomposites with high conductivity and extensibility.

    PubMed

    Chun, Kyoung-Yong; Kim, Shi Hyeong; Shin, Min Kyoon; Kim, Youn Tae; Spinks, Geoffrey M; Aliev, Ali E; Baughman, Ray H; Kim, Seon Jeong

    2013-04-26

    The prospect of electronic circuits that are stretchable and bendable promises tantalizing applications such as skin-like electronics, roll-up displays, conformable sensors and actuators, and lightweight solar cells. The preparation of highly conductive and highly extensible materials remains a challenge for mass production applications, such as free-standing films or printable composite inks. Here we present a nanocomposite material consisting of carbon nanotubes, ionic liquid, silver nanoparticles, and polystyrene-polyisoprene-polystyrene having a high electrical conductivity of 3700 S cm(-1) that can be stretched to 288% without permanent damage. The material is prepared as a concentrated dispersion suitable for simple processing into free-standing films. For the unstrained state, the measured thermal conductivity for the electronically conducting elastomeric nanoparticle film is relatively high and shows a non-metallic temperature dependence consistent with phonon transport, while the temperature dependence of electrical resistivity is metallic. We connect an electric fan to a DC power supply using the films to demonstrate their utility as an elastomeric electronic interconnect. The huge strain sensitivity and the very low temperature coefficient of resistivity suggest their applicability as strain sensors, including those that operate directly to control motors and other devices. PMID:23535262

  8. Free-standing nanocomposites with high conductivity and extensibility

    NASA Astrophysics Data System (ADS)

    Chun, Kyoung-Yong; Kim, Shi Hyeong; Shin, Min Kyoon; Kim, Youn Tae; Spinks, Geoffrey M.; Aliev, Ali E.; Baughman, Ray H.; Kim, Seon Jeong

    2013-04-01

    The prospect of electronic circuits that are stretchable and bendable promises tantalizing applications such as skin-like electronics, roll-up displays, conformable sensors and actuators, and lightweight solar cells. The preparation of highly conductive and highly extensible materials remains a challenge for mass production applications, such as free-standing films or printable composite inks. Here we present a nanocomposite material consisting of carbon nanotubes, ionic liquid, silver nanoparticles, and polystyrene-polyisoprene-polystyrene having a high electrical conductivity of 3700 S cm-1 that can be stretched to 288% without permanent damage. The material is prepared as a concentrated dispersion suitable for simple processing into free-standing films. For the unstrained state, the measured thermal conductivity for the electronically conducting elastomeric nanoparticle film is relatively high and shows a non-metallic temperature dependence consistent with phonon transport, while the temperature dependence of electrical resistivity is metallic. We connect an electric fan to a DC power supply using the films to demonstrate their utility as an elastomeric electronic interconnect. The huge strain sensitivity and the very low temperature coefficient of resistivity suggest their applicability as strain sensors, including those that operate directly to control motors and other devices.

  9. Electronically conductive ceramics for high temperature oxidizing environments

    DOEpatents

    Kucera, Gene H.; Smith, James L.; Sim, James W.

    1986-01-01

    A high temperature, ceramic composition having electronic conductivity as measured by resistivity below about 500 ohm-cm, chemical stability particularly with respect to cathode conditions in a molten carbonate fuel cell, and composed of an alkali metal, transition metal oxide containing a dopant metal in the crystalline structure to replace a portion of the alkali metal or transition metal.

  10. Electronically conductive ceramics for high temperature oxidizing environments

    DOEpatents

    Kucera, G.H.; Smith, J.L.; Sim, J.W.

    1983-11-10

    This invention pertains to a high temperature, ceramic composition having electronic conductivity as measured by resistivity below about 500 ohm-cm, chemical stability particularly with respect to cathode conditions in a molten carbonate fuel cell, and composed of an alkali metal, transition metal oxide containing a dopant metal in the crystalline structure to replace a portion of the alkali metal or transition metal.

  11. High performance electrically conductive adhesives (ECAs) for leadfree interconnects

    NASA Astrophysics Data System (ADS)

    Li, Yi

    Electrically conductive adhesives (ECAs) are one of the lead-free interconnect materials with the advantages of environmental friendliness, mild processing conditions, fewer processing steps, low stress on the substrates, and fine pitch interconnect capability. However, some challenging issues still exist for the currently available ECAs, including lower electrical conductivity, conductivity fatigue in reliability tests, limited current-carrying capability, poor impact strength, etc. The interfacial properties is one of the major considerations when resolving these challenges and developing high performance conductive adhesives. Surface functionalization and interface modification are the major approaches used in this thesis. Fundamental understanding and analysis of the interaction between various types of interface modifiers and ECA materials and substrates are the key for the development of high performance ECA for lead-free interconnects. The results of this thesis provide the guideline for the enhancement of interfacial properties of metal-metal and metal-polymer interactions. Systematic investigation of various types of ECAs contributes to a better understanding of materials requirements for different applications, such as surface mount technology (SMT), flip chip applications, flat panel display modules with high resolution, etc. Improvement of the electrical, thermal and reliability of different ECAs make them a potentially ideal candidate for high power and fine pitch microelectronics packaging option.

  12. Dynamics and sensitivity analysis of high frequency conduction block

    PubMed Central

    Ackermann, D. Michael; Bhadra, Niloy; Gerges, Meana; Thomas, Peter J.

    2012-01-01

    The local delivery of extracellular high frequency stimulation (HFS) has been shown to be a fast acting and quickly reversible method of blocking neural conduction, and is currently being pursued for several clinical indications. However, the mechanism for this type of nerve block remains unclear. In this study, we investigate two hypotheses: 1) That depolarizing currents promote conduction block via inactivation of sodium channels, and 2) that the gating dynamics of the fast sodium channel are the primary determinate of minimal blocking frequency. Hypothesis 1 was investigated using a combined modeling and experimental study to investigate the effect of depolarizing and hyperpolarizing currents on high frequency block. The results of the modeling study show that both depolarizing and hyperpolarizing currents play an important role in conduction block and that the conductance to each of three ionic currents increases relative to resting values during HFS. However, depolarizing currents were found to promote the blocking effect, and hyperpolarizing currents were found to diminish the blocking effect. Inward sodium currents were larger than the sum of the outward currents, resulting in a net depolarization of the nodal membrane. Our experimental results support these findings and closely match results from the equivalent modeling scenario: intra-peritoneal administration of the persistent sodium channel blocker ranolazine resulted in an increase in the amplitude of HFS required to produce conduction block in rats, confirming that depolarizing currents promote the conduction block phenomenon. Hypothesis 2 was investigated using a spectral analysis of the channel gating variables in a single fiber axon model. The results of this study suggested a relationship between the dynamical properties of specific ion channel gating elements and the contributions of corresponding conductances to block onset. Specifically, we show that the dynamics of the fast sodium inactivation

  13. Dynamics and sensitivity analysis of high-frequency conduction block

    NASA Astrophysics Data System (ADS)

    Ackermann, D. Michael; Bhadra, Niloy; Gerges, Meana; Thomas, Peter J.

    2011-10-01

    The local delivery of extracellular high-frequency stimulation (HFS) has been shown to be a fast acting and quickly reversible method of blocking neural conduction and is currently being pursued for several clinical indications. However, the mechanism for this type of nerve block remains unclear. In this study, we investigate two hypotheses: (1) depolarizing currents promote conduction block via inactivation of sodium channels and (2) the gating dynamics of the fast sodium channel are the primary determinate of minimal blocking frequency. Hypothesis 1 was investigated using a combined modeling and experimental study to investigate the effect of depolarizing and hyperpolarizing currents on high-frequency block. The results of the modeling study show that both depolarizing and hyperpolarizing currents play an important role in conduction block and that the conductance to each of three ionic currents increases relative to resting values during HFS. However, depolarizing currents were found to promote the blocking effect, and hyperpolarizing currents were found to diminish the blocking effect. Inward sodium currents were larger than the sum of the outward currents, resulting in a net depolarization of the nodal membrane. Our experimental results support these findings and closely match results from the equivalent modeling scenario: intra-peritoneal administration of the persistent sodium channel blocker ranolazine resulted in an increase in the amplitude of HFS required to produce conduction block in rats, confirming that depolarizing currents promote the conduction block phenomenon. Hypothesis 2 was investigated using a spectral analysis of the channel gating variables in a single-fiber axon model. The results of this study suggested a relationship between the dynamical properties of specific ion channel gating elements and the contributions of corresponding conductances to block onset. Specifically, we show that the dynamics of the fast sodium inactivation gate are

  14. Measurement of FeO activity and solubility of MgO in smelting slags

    NASA Astrophysics Data System (ADS)

    Liu, Shih-Hsien; Fruehan, R. J.; Morales, A.; Ozturk, B.

    2001-02-01

    In bath smelting, the FeO activity of the slag must be known to predict the equilibrium of slag-metal reactions and for effective control of the rate of reduction in the system. Also, knowledge of the solubility of MgO in these slags is useful for reducing refractory consumption. A series of measurements of the FeO activity in simulated bath smelting slags (CaO-SiO2-Al2O3-MgOsat-FeO) were conducted by the electromotive force (EMF) technique. The influence of the slag composition on the relationship between the FeO activity coefficient and FeO content was studied. It has been found that the measured FeO activity coefficient decreases with increasing FeO content in the slag and increases slightly with increasing slag basicity, which is defined as (CaO + MgO)/(SiO2 + Al2O3) on a mole fraction basis. The measured values of the FeO activity coefficient are in reasonable agreement with previously published data. The solubility of MgO was also measured and found to rang from 16 to 30 pct and decrease with increasing basicity.

  15. Modeling Slag Penetration and Refractory Degradation Using the Finite Element Method

    SciTech Connect

    Johnson, Kenneth I.; Williford, Ralph E.; Matyas, Josef; Pilli, Siva Prasad; Sundaram, S. K.; Korolev, Vladimir N.

    2008-09-01

    Refractory degradation due to slag penetration can significantly reduce the service life of gasifier refractory linings. This paper describes a modeling approach that was developed to predict refractory spalling as a function of operating temperature, coal feedstock and refractory type. The model simulates the coupled thermal, diffusion, and mechanical interactions of coal slag with refractory ceramics. The heat transfer and slag diffusion solutions are directly coupled through a temperature-dependent effective diffusivity for slag penetration. The effective diffusivity is defined from slag penetration tests conducted in our laboratories on specific coal slag and refractory combinations. Chemically-induced swelling of the refractory and the build-up of mechanical stresses are functions of the slag penetration. The model results are compared with analytical spalling models and validated by experimental data in order to develop an efficient refractory degradation model for implementation in a systems level gasifier model. The ultimate goal of our research is to provide a tool that will help optimize gasifier performance by balancing conversion efficiency with refractory life.

  16. Effect of electric arc furnace slag on growth and physiology of maize (Zea mays L.).

    PubMed

    Radić, Sandra; Crnojević, Helena; Sandev, Dubravka; Jelić, Sonja; Sedlar, Zorana; Glavaš, Katarina; Pevalek-Kozlina, Branka

    2013-12-01

    Basic slag, used in this study as a potential source of certain nutrients, is a byproduct of the production of steel in electric arc furnace (EAF). A pot experiment with two nutrient-poor substrates was conducted to investigate to compare the effect of EAF steel slag and fertilizers NPK + F e on growth and availability of specific nutrients to maize. Mineral content of both substrate and plant leaves, growth, chlorophyll fluorescence and photosynthetic pigments were measured following six weeks of cultivation. As steel slag also contains trace amounts of heavy metals, certain oxidative parameters (antioxidative enzyme activities and lipid peroxidation) were evaluated as well. The steel slag improved soil mineral composition, increased above ground maize biomass by providing Fe, Mn, Mg, K and partly P and improved photosynthetic parameters. The potential phytotoxicity of EAF slag containing substrates was not determined as evaluated by MDA (malondialdehyde), GR (glutathione reductase) and APX (ascorbate peroxidase) levels. The obtained results show that EAF steel slag is comparable to NPK + F e in supplying nutrients for maize growth, indicating the potential of EAF steel slag as an inexpensive and non-phytotoxic nutrient supplier especially in poor soils. PMID:24275594

  17. Transient Thermo-fluid Model of Meniscus Behavior and Slag Consumption in Steel Continuous Casting

    NASA Astrophysics Data System (ADS)

    Jonayat, A. S. M.; Thomas, Brian G.

    2014-10-01

    The behavior of the slag layer between the oscillating mold wall, the slag rim, the slag/liquid steel interface, and the solidifying steel shell, is of immense importance for the surface quality of continuous-cast steel. A computational model of the meniscus region has been developed, that includes transient heat transfer, multi-phase fluid flow, solidification of the slag, and movement of the mold during an oscillation cycle. First, the model is applied to a lab experiment done with a "mold simulator" to verify the transient temperature-field predictions. Next, the model is verified by matching with available literature and plant measurements of slag consumption. A reasonable agreement has been observed for both temperature and flow-field. The predictions show that transient temperature behavior depends on the location of the thermocouple during the oscillation relative to the meniscus. During an oscillation cycle, heat transfer variations in a laboratory frame of reference are more severe than experienced by the moving mold thermocouples, and the local heat transfer rate is increased greatly when steel overflows the meniscus. Finally, the model is applied to conduct a parametric study on the effect of casting speed, stroke, frequency, and modification ratio on slag consumption. Slag consumption per unit area increases with increase of stroke and modification ratio, and decreases with increase of casting speed while the relation with frequency is not straightforward. The match between model predictions and literature trends suggests that this methodology can be used for further investigations.

  18. Influence of slag blended cement concrete on chloride diffusion rate

    SciTech Connect

    Dehghanian, C.; Arjemandi, M.

    1997-06-01

    This research was conducted to investigate the effect of 0 to 30% partial replacement of cement by slag on chloride diffusion rate in concrete. Concretes with 0 to 30% slag were used and exposed to 2 to 5% NaCl solutions. The effect of different external salt concentration solutions and the influence of water-cement ratios ranging from 0.45 to 0.75 was also studied. In this research, different curing methods such as 9 to 18 days exposure to 100% humidity and 9 to 18 days submersion in distilled water were selected. The results indicated that after 90 days of exposure to salt solutions an/d 108 days of concrete age, chloride diffusivity for concretes containing slag almost remained the same. This effect was more pronounced for water-cement ratio of 0.45 and curing condition of 18 days submersion in water. An increase in water-cement ratio beyond 0.55 indicated a higher chloride diffusion rate. Curing condition for slag blended cement concrete also indicated a different behavior in chloride diffusivity. The best curing method obtained for this type of concrete was 18 days submersion in water.

  19. Thylakoid membranes contain a high-conductance channel.

    PubMed

    Hinnah, S C; Wagner, R

    1998-05-01

    Ion channels in the thylakoid membrane were investigated by direct patch clamping on swollen thylakoids. A preparation method has been developed in order to release osmotically swollen intact thylakoids from pea protoplasts derived from cotyledons of young Pisum sativum plants. The swollen thylakoids with typical diameters between 10 microm and 20 microm formed reproducibly high-resistance seals with patch pipettes. We observed a potassium channel with a main conductant state of lambda approximately 40 pS and a conductance of lambda approximately 90 pS (in asymmetric 20/100 mM KCl) for the fully open channel. Surprisingly, the thylakoid membranes also contained a high-conductance channel with a main conductant state of lambda approximately 620 pS (in asymmetric 20/100 mM KCl), revealing also higher and lower conductant states. With a different experimental approach we showed that thylakoids are able to accumulate transiently the membrane impermeant fluorescent dye Lucifer Yellow which likewise suggests the presence of a pore-like channel with a diameter large enough to allow permeation of Lucifer Yellow. PMID:9654056

  20. Changes in mineralogical and leaching properties of converter steel slag resulting from accelerated carbonation at low CO2 pressure.

    PubMed

    van Zomeren, André; van der Laan, Sieger R; Kobesen, Hans B A; Huijgen, Wouter J J; Comans, Rob N J

    2011-11-01

    Steel slag can be applied as substitute for natural aggregates in construction applications. The material imposes a high pH (typically 12.5) and low redox potential (Eh), which may lead to environmental problems in specific application scenarios. The aim of this study is to investigate the potential of accelerated steel slag carbonation, at relatively low pCO2 pressure (0.2 bar), to improve the environmental pH and the leaching properties of steel slag, with specific focus on the leaching of vanadium. Carbonation experiments are performed in laboratory columns with steel slag under water-saturated and -unsaturated conditions and temperatures between 5 and 90 °C. Two types of steel slag are tested; free lime containing (K3) slag and K1 slag with a very low free lime content. The fresh and carbonated slag samples are investigated using a combination of leaching experiments, geochemical modelling of leaching mechanisms and microscopic/mineralogical analysis, in order to identify the major processes that control the slag pH and resulting V leaching. The major changes in the amount of sequestered CO2 and the resulting pH reduction occurred within 24h, the free lime containing slag (K3-slag) being more prone to carbonation than the slag with lower free lime content (K1-slag). While carbonation at these conditions was found to occur predominantly at the surface of the slag grains, the formation of cracks was observed in carbonated K3 slag, suggesting that free lime in the interior of slag grains had also reacted. The pH of the K3 slag (originally pH±12.5) was reduced by about 1.5 units, while the K1 slag showed a smaller decrease in pH from about 11.7 to 11.1. However, the pH reduction after carbonation of the K3 slag was observed to lead to an increased V-leaching. Vanadium leaching from the K1 slag resulted in levels above the limit values of the Dutch Soil Quality Decree, for both the untreated and carbonated slag. V-leaching from the carbonated K3 slag remained

  1. Simulation Basics: How to Conduct a High-Fidelity Simulation.

    PubMed

    Willhaus, Janet

    2016-02-01

    Well-planned and conducted health care simulation scenarios provide opportunities for staff development in areas such as communication, patient care, and teamwork. Consideration of resources, the location for the training, preparation of learners, and use of either a high-fidelity mannequin or a trained actor (eg, a standardized patient) are all part of the operational attentions needed to conduct a simulation training scenario. In order for participants to meet training objectives, the execution of the simulation session must be both planned and purposeful. PMID:26909456

  2. Obtaining high thermally conductive materials by pressing from the granulate

    NASA Astrophysics Data System (ADS)

    Ditts, A.; Revva, I.; Pautova, Y.; Pogrebenkov, V.; Nepochatov, Y.; Galashov, E.; Tarnovskiy, R.

    2015-01-01

    This work contains results of investigation of obtaining high thermally conductive ceramics from commercial powders of aluminum nitride and yttrium oxide by the method of monoaxial compaction of granulate. The principal scheme of preparation is proposed and technological properties of granulate are defined. Compaction conditions for simple items to use as heat removal in microelectronics and power electrical engineering have been established. Investigations of thermophysical properties of obtained ceramics and its structure by the XRD and SEM methods have been carried out. Ceramics with thermal conductivity from 172 to 174 W/m·K has been obtained as result of this work.

  3. Thermal conductance of metal-diamond interfaces at high pressure.

    PubMed

    Hohensee, Gregory T; Wilson, R B; Cahill, David G

    2015-01-01

    The thermal conductance of interfaces between metals and diamond, which has a comparatively high Debye temperature, is often greater than can be accounted for by two-phonon processes. The high pressures achievable in a diamond anvil cell (DAC) can significantly extend the metal phonon density of states to higher frequencies, and can also suppress extrinsic effects by greatly stiffening interface bonding. Here we report time-domain thermoreflectance measurements of metal-diamond interface thermal conductance up to 50 GPa in the DAC for Pb, Au0.95Pd0.05, Pt and Al films deposited on type 1A natural [100] and type 2A synthetic [110] diamond anvils. In all cases, the thermal conductances increase weakly or saturate to similar values at high pressure. Our results suggest that anharmonic conductance at metal-diamond interfaces is controlled by partial transmission processes, where a diamond phonon that inelastically scatters at the interface absorbs or emits a metal phonon. PMID:25744853

  4. Highly Conductive and Reliable Copper-Filled Isotropically Conductive Adhesives Using Organic Acids for Oxidation Prevention

    NASA Astrophysics Data System (ADS)

    Chen, Wenjun; Deng, Dunying; Cheng, Yuanrong; Xiao, Fei

    2015-07-01

    The easy oxidation of copper is one critical obstacle to high-performance copper-filled isotropically conductive adhesives (ICAs). In this paper, a facile method to prepare highly reliable, highly conductive, and low-cost ICAs is reported. The copper fillers were treated by organic acids for oxidation prevention. Compared with ICA filled with untreated copper flakes, the ICA filled with copper flakes treated by different organic acids exhibited much lower bulk resistivity. The lowest bulk resistivity achieved was 4.5 × 10-5 Ω cm, which is comparable to that of commercially available Ag-filled ICA. After 500 h of 85°C/85% relative humidity (RH) aging, the treated ICAs showed quite stable bulk resistivity and relatively stable contact resistance. Through analyzing the results of x-ray diffraction, x-ray photoelectron spectroscopy, and thermogravimetric analysis, we found that, with the assistance of organic acids, the treated copper flakes exhibited resistance to oxidation, thus guaranteeing good performance.

  5. Highly thermally conductive and mechanically strong graphene fibers.

    PubMed

    Xin, Guoqing; Yao, Tiankai; Sun, Hongtao; Scott, Spencer Michael; Shao, Dali; Wang, Gongkai; Lian, Jie

    2015-09-01

    Graphene, a single layer of carbon atoms bonded in a hexagonal lattice, is the thinnest, strongest, and stiffest known material and an excellent conductor of heat and electricity. However, these superior properties have yet to be realized for graphene-derived macroscopic structures such as graphene fibers. We report the fabrication of graphene fibers with high thermal and electrical conductivity and enhanced mechanical strength. The inner fiber structure consists of large-sized graphene sheets forming a highly ordered arrangement intercalated with small-sized graphene sheets filling the space and microvoids. The graphene fibers exhibit a submicrometer crystallite domain size through high-temperature treatment, achieving an enhanced thermal conductivity up to 1290 watts per meter per kelvin. The tensile strength of the graphene fiber reaches 1080 megapascals. PMID:26339027

  6. Highly thermally conductive and mechanically strong graphene fibers

    NASA Astrophysics Data System (ADS)

    Xin, Guoqing; Yao, Tiankai; Sun, Hongtao; Scott, Spencer Michael; Shao, Dali; Wang, Gongkai; Lian, Jie

    2015-09-01

    Graphene, a single layer of carbon atoms bonded in a hexagonal lattice, is the thinnest, strongest, and stiffest known material and an excellent conductor of heat and electricity. However, these superior properties have yet to be realized for graphene-derived macroscopic structures such as graphene fibers. We report the fabrication of graphene fibers with high thermal and electrical conductivity and enhanced mechanical strength. The inner fiber structure consists of large-sized graphene sheets forming a highly ordered arrangement intercalated with small-sized graphene sheets filling the space and microvoids. The graphene fibers exhibit a submicrometer crystallite domain size through high-temperature treatment, achieving an enhanced thermal conductivity up to 1290 watts per meter per kelvin. The tensile strength of the graphene fiber reaches 1080 megapascals.

  7. Steel slag used in landfill cover liners: laboratory and field tests.

    PubMed

    Herrmann, Inga; Andreas, Lale; Diener, Silvia; Lind, Lotta

    2010-12-01

    Stricter rules for landfilling within the EU have led to the closure of many landfills and a need for large amounts of cover liner materials. Therefore, the potential utilization of mixtures of electric arc furnace slag (EAFS) and ladle slag (LS), which are currently deposited in landfills, as a material for use as landfill liner was investigated. Laboratory analyses showed the mixtures to have similar compression strength to that of high-strength concrete and low hydraulic conductivity (< 10(-11) m s(-1) in some cases). However, both their hydraulic conductivity and compaction properties were strongly affected by the time between adding water to the mixtures and compacting them (tests showed that a delay of 24 h can lead to an increase in hydraulic conductivity, so it should be compacted as soon as possible after mixing the material with water). In addition, the performance of a cover liner constructed using EAFS and LS was studied in a 2-year field trial on a landfill for municipal solid waste, in which the average amount of leachate collected from ten lysimeters was only 27 L m(-2) year(-1), easily meeting Swedish criteria for the permeability of covers on non-hazardous waste landfills (≤ 50 L m(-2) year(-1)). Thus, the material seems to have promising potential for use in barrier constructions. PMID:20421245

  8. Mechanisms of pyrite oxidation to non-slagging species. Quarterly report, April 1, 1995--June 30, 1995

    SciTech Connect

    Akan-Etuk, A.E.J.; Mitchell, R.E.

    1995-12-01

    This document is the fourth quarterly status report on a project that is conducted at the High Temperature Gasdynamics Laboratory at Stanford University, Stanford, California and is concerned with enhancing the transformation of iron pyrite to non-slagging species during staged, low-NO{sub x} pulverized coal (P.C.) combustion. The research project is intended to advance PETC`s efforts to improve our technical understanding of the high-temperature chemical and physical processes involved in the utilization of coal. The work focuses on the mechanistic description and rate quantification of the effects of fuel properties and combustion environment on the oxidation of iron pyrite to form the non-slagging species magnetite. The knowledge gained from this work is intended to be incorporated into numerical codes that can be used to formulate anti-slagging strategies involving minimal disturbance of coal combustor performance. This project is to be performed over the three-year period from September 1994 to August 1997. The project aims to identify the mechanisms of pyrite combustion and to quantify their effects, in order to formulate a general rate expression for the combustion of pyrite that accounts for coal properties as well as furnace conditions.

  9. Electrical conductivity of albite melts at high pressures

    NASA Astrophysics Data System (ADS)

    Ni, H.; Keppler, H.

    2009-12-01

    High electrical conductivity observed from magnetotelluric/geomagnetic depth sounding is probably associated with the presence of silicate melts. We investigated electrical conductivity of albite melts, both anhydrous and hydrous with 2.0-5.4 wt% H2O, at 300-1500°C and 0.9-1.8 GPa in a piston-cylinder apparatus. Anhydrous glass was synthesized by fusing oxides and carbonates in 1-bar furnace, and hydrous glasses were prepared by fusing the mixture of glass powder and water in a TZM vessel. A glass cylinder was enclosed between a platinum rod as inner electrode and a Pt-Rh capsule as outer electrode. Platinum wires were used to connect both electrodes to a Solartron 1260 impedance analyzer for conductivity measurements at 3M to 3 HZ. A type-S thermocouple, which was separated from the conductivity circuit, was used to monitor temperature. Furthermore, a Mo foil was employed to reduce the interference from heating circuit. Experimental results demonstrate that the electrical conductivity of albite melt follows an Arrhenius relationship in both glass (<700°C) and liquid (>1100°C) region. In both cases, electrical conductivity increases with water content but decreases with pressure. In the glass region, electrical conductivity can be modelled as logσ = 3.5734 + 0.25534C - (4264+160.43P)/T, where σ is conductivity in S/m, C is water content in wt%, P is pressure in GPa, and T is temperature in K. The above expression implies an activation energy of 82 kJ/mol and an activation volume of 3.1 cc/mol. In the liquid region, electrical conductivity can be modelled as logσ = 2.6906 + 0.065915C - (2339+371.97P)/T, which implies an activation energy of 45 kJ/mol and an activation volume of 7.1 cc/mol. The dominating conduction mechanism in albite melts is suggested to be the motion of sodium cation.

  10. Constant voltage electro-slag remelting control

    DOEpatents

    Schlienger, Max E.

    1996-01-01

    A system for controlling electrode gap in an electro-slag remelt furnace has a constant regulated voltage and an eletrode which is fed into the slag pool at a constant rate. The impedance of the circuit through the slag pool is directly proportional to the gap distance. Because of the constant voltage, the system current changes are inversely proportional to changes in gap. This negative feedback causes the gap to remain stable.

  11. Constant voltage electro-slag remelting control

    DOEpatents

    Schlienger, M.E.

    1996-10-22

    A system for controlling electrode gap in an electro-slag remelt furnace has a constant regulated voltage and an electrode which is fed into the slag pool at a constant rate. The impedance of the circuit through the slag pool is directly proportional to the gap distance. Because of the constant voltage, the system current changes are inversely proportional to changes in gap. This negative feedback causes the gap to remain stable. 1 fig.

  12. Developing a High Thermal Conductivity Fuel with Silicon Carbide Additives

    SciTech Connect

    baney, Ronald; Tulenko, James

    2012-11-20

    The objective of this research is to increase the thermal conductivity of uranium oxide (UO{sub 2}) without significantly impacting its neutronic properties. The concept is to incorporate another high thermal conductivity material, silicon carbide (SiC), in the form of whiskers or from nanoparticles of SiC and a SiC polymeric precursor into UO{sub 2}. This is expected to form a percolation pathway lattice for conductive heat transfer out of the fuel pellet. The thermal conductivity of SiC would control the overall fuel pellet thermal conductivity. The challenge is to show the effectiveness of a low temperature sintering process, because of a UO{sub 2}-SiC reaction at 1,377°C, a temperature far below the normal sintering temperature. Researchers will study three strategies to overcome the processing difficulties associated with pore clogging and the chemical reaction of SiC and UO{sub 2} at temperatures above 1,300°C:

  13. Experimental study on sulfur removal from ladle furnace refining slag in hot state by blowing air

    NASA Astrophysics Data System (ADS)

    Zhao, Li-hua; Lin, Lu; Wu, Qi-fan

    2016-01-01

    In view of the present problem of sulfur enrichment in the metallurgical recycling process of ladle furnace (LF) refining slag, a simple and efficient method of removing sulfur from this slag was proposed. The proposed method is compatible with current steelmaking processes. Sulfur removal from LF refining slag for SPHC steel (manufactured at a certain steel plant in China) by blowing air in the hot state was studied by using hot-state experiments in a laboratory. The FactSage software, a carbon/sulfur analyzer, and scanning electron microscopy in conjunction with energy-dispersive X-ray spectroscopy were used to test and analyze the sulfur removal effect and to investigate factors influencing sulfur removal rate. The results show that sulfur ions in LF refining slag can be oxidized into SO2 by O2 at high temperature by blowing air into molten slag; SO2 production was observed to reach a maximum with a small amount of blown O2 when the temperature exceeded 1350°C. At 1370°C and 1400°C, experimental LF refining slag is in the liquid state and exhibits good fluidity; under these conditions, the sulfur removal effect by blowing air is greater than 90wt% after 60 min. High temperature and large air flow rate are beneficial for removing sulfur from LF refining slag; compared with air flow rate, temperature has a greater strongly influences on the sulfur removal.

  14. Effect of blast furnace slag on self-healing of microcracks in cementitious materials

    SciTech Connect

    Huang, Haoliang; Ye, Guang; Damidot, Denis

    2014-06-01

    The physico-chemical process of self-healing in blast furnace slag cement paste was investigated in this paper. With a high slag content i.e., 66% in cement paste and saturated Ca(OH)₂ solution as activator, it was found that the reaction products formed in cracks are composed of C-S-H, ettringite, hydrogarnet and OH–hydrotalcite. The fraction of C-S-H in the reaction products is much larger than the other minerals. Large amount of ettringite formed in cracks indicates the leaching of SO₄⁻² ions from the bulk paste and consequently the recrystallization. Self-healing proceeds fast within 50 h and then slows down. According to thermodynamic modeling, when the newly formed reaction products are carbonated, the filling fraction of crack increases first and then decreases. Low soluble minerals such as silica gel, gibbsite and calcite are formed. Compared to Portland cement paste, the potential of self-healing in slag cement paste is higher when the percentage of slag is high. Highlights: • Self-healing reaction products in slag cement paste were characterized. • Self-healing reaction products formed in time were quantified with image analysis. • Self-healing in slag cement paste was simulated with a reactive transport model. • Effect of carbonation on self-healing was investigated by thermodynamic modeling. • Effect of slag on self-healing was discussed based on experiments and simulation.

  15. Hydration characteristics and environmental friendly performance of a cementitious material composed of calcium silicate slag.

    PubMed

    Zhang, Na; Li, Hongxu; Zhao, Yazhao; Liu, Xiaoming

    2016-04-01

    Calcium silicate slag is an alkali leaching waste generated during the process of extracting Al2O3 from high-alumina fly ash. In this research, a cementitious material composed of calcium silicate slag was developed, and its mechanical and physical properties, hydration characteristics and environmental friendly performance were investigated. The results show that an optimal design for the cementitious material composed of calcium silicate slag was determined by the specimen CFSC7 containing 30% calcium silicate slag, 5% high-alumina fly ash, 24% blast furnace slag, 35% clinker and 6% FGD gypsum. This blended system yields excellent physical and mechanical properties, confirming the usefulness of CFSC7. The hydration products of CFSC7 are mostly amorphous C-A-S-H gel, rod-like ettringite and hexagonal-sheet Ca(OH)2 with small amount of zeolite-like minerals such as CaAl2Si2O8·4H2O and Na2Al2Si2O8·H2O. As the predominant hydration products, rod-like ettringite and amorphous C-A-S-H gel play a positive role in promoting densification of the paste structure, resulting in strength development of CFSC7 in the early hydration process. The leaching toxicity and radioactivity tests results indicate that the developed cementitious material composed of calcium silicate slag is environmentally acceptable. This study points out a promising direction for the proper utilization of calcium silicate slag in large quantities. PMID:26691955

  16. Highly thermally conductive papers with percolative layered boron nitride nanosheets.

    PubMed

    Zhu, Hongli; Li, Yuanyuan; Fang, Zhiqiang; Xu, Jiajun; Cao, Fangyu; Wan, Jiayu; Preston, Colin; Yang, Bao; Hu, Liangbing

    2014-04-22

    In this work, we report a dielectric nanocomposite paper with layered boron nitride (BN) nanosheets wired by one-dimensional (1D) nanofibrillated cellulose (NFC) that has superior thermal and mechanical properties. These nanocomposite papers are fabricated from a filtration of BN and NFC suspensions, in which NFC is used as a stabilizer to stabilize BN nanosheets. In these nanocomposite papers, two-dimensional (2D) nanosheets form a thermally conductive network, while 1D NFC provides mechanical strength. A high thermal conductivity has been achieved along the BN paper surface (up to 145.7 W/m K for 50 wt % of BN), which is an order of magnitude higher than that in randomly distributed BN nanosheet composites and is even comparable to the thermal conductivity of aluminum alloys. Such a high thermal conductivity is mainly attributed to the structural alignment within the BN nanosheet papers; the effects of the interfacial thermal contact resistance are minimized by the fact that the heat transfer is in the direction parallel to the interface between BN nanosheets and that a large contact area occurs between BN nanosheets. PMID:24601534

  17. Nonequilibrium sulfur capture and retention in an air cooled slagging coal combustor

    SciTech Connect

    Zauderer, B.

    1997-08-13

    Calcium oxide injected in a slagging combustor react with the sulfur from coal combustion to form sulfur bearing particles, which are deposited on the liquid slag layer on the combustor wall. Due to the low solubility of sulfur in slag, it must be drained from the combustor to limit sulfur gas re-evolution. Analysis indicated that slag mass flow rates in excess of 400 lb/hr should limit sulfur re- evolution. The objective of this 36 month project was to perform a series of 16 one day tests to determine the factors that control the retention of the sulfur in the slag. In the present quarterly reporting period, 3 days of combustor tests were performed, bringing the total number of tests performed to 19. Two of the test were a repeat of two tests performed in the previous quarter with a high, 37% ash, Indian coal. The high slag flow rate with that coal resulted in the highest observed sulfur retention to-date, namely 20% of the injected sulfur. In the present quarter, this test was repeated with the same coal feed rate but with 75% longer period of 2.4 hours. The total mineral matter injected was 635 lb/hr, compared to only 19.7 lb/hr of sulfur, of which 75% was from injected gypsum. However, despite excellent slag flow from the previous Indian coal tests, only 5.8% of the sulfur from the gypsum reported to the slag. Since substantial amounts slag remained on the combustor walls, it is concluded that still longer duration tests are required to establish equilibrium conditions. Current efforts are focused on finding a U.S. source of high ash coal to implement additional tests.

  18. Nonequilibrium Sulfur Capture and Retention in an Air Cooled Slagging Coal Combustor.

    SciTech Connect

    Zauderer, B.

    1997-09-30

    Calcium oxide injected in a slagging combustor react with the sulfur from coal combustion to form sulfur bearing particles, which are deposited on the liquid slag layer on the combustor wall. Due to the low solubility of sulfur in slag, it must be drained from the combustor to limit sulfur gas re-evolution. Analysis indicated that slag mass flow rates in excess of 400 lb/hr should limit sulfur re-evolution. The objective of this 36 month project was to perform a series of 16 one day tests to determine the factors that control the retention of the sulfur in the slag. In the present quarterly reporting period, 3 days of combustor tests were performed, bringing the total number of tests performed to 19. Two of the test were a repeat of two tests performed in the previous quarter with a high, 37% ash, Indian coal. The high slag flow rate with that coal resulted in the highest observed sulfur retention to-date, namely 20% of the injected sulfur. In the present quarter, this test was repeated with the same coal feed rate but with 75% longer period of 2.4 hours. The total mineral matter injected was 635 lb/hr, compared to only 19.7 lb/hr of sulfur, of which 75% was from injected gypsum. However, despite excellent slag flow from the previous Indian coal tests, only 5.8% of the sulfur from the gypsum reported to the slag. Since substantial amounts slag remained on the combustor walls, it is concluded that still longer duration tests are required to establish equilibrium conditions. Current efforts are focused on finding a U.S. source of high ash coal to implement additional tests.

  19. Uniformly embedded silver nanomesh as highly bendable transparent conducting electrode

    NASA Astrophysics Data System (ADS)

    Choi, Hak-Jong; Choo, Soyoung; Jung, Pil-Hoon; Shin, Ju-Hyeon; Kim, Yang-Doo; Lee, Heon

    2015-02-01

    Ag-nanomesh-based highly bendable conducting electrodes are developed using a combination of metal nanotransfer printing and embossing for the 6-inch wafer scale. Two Ag nanomeshes, including pitch sizes of 7.5 and 10 μm, are used to obtain highly transparent (approximately 85% transmittance at a wavelength of 550 nm) and electrically conducting properties (below 10 Ω sq-1). The Ag nanomeshes are also distinguished according to the fabrication process, which is called transferred or embedded Ag nanomesh on polyethylene terephthalate (PET) substrate, in order to compare their stability against bending stress. Then the enhancement of bending stability when the Ag nanomesh is embedded in the PET substrate is confirmed.

  20. Highly conducting ZnSe films by reactive magnetron sputtering

    NASA Technical Reports Server (NTRS)

    Nouhi, A.; Stirn, R. J.

    1986-01-01

    This paper presents the results of an effort to deposit high-conductivity ZnSe on glass and conducting SnO2-coated glass substrates by reactive magnetron sputter deposition, using pure metal sputter targets of Zn and dopants such as In, Ga, and Al. Clear yellow ZnSe films were successfully obtained. By using substrate temperatures as low as 150 C, cosputtered dopants, and sputter parameters and H2Se injection rates which maximize the Zn-to-Se ratio in the films, ZnSe bulk resistivities have been lowered by up to seven orders of magnitude, reaching values as low as 20 ohm cm. The most effective dopant to data has been In, cosputtered with Zn in amounts leading to In atomic concentrations as high as 1.4 percent. Atomic-absorption measurements show an average 49.9/48.9 ratio of Zn to Se.

  1. Analysis of Slug Tests in Formations of High Hydraulic Conductivity

    USGS Publications Warehouse

    Butler, J.J., Jr.; Garnett, E.J.; Healey, J.M.

    2003-01-01

    A new procedure is presented for the analysis of slug tests performed in partially penetrating wells in formations of high hydraulic conductivity. This approach is a simple, spreadsheet-based implementation of existing models that can be used for analysis of tests from confined or unconfined aquifers. Field examples of tests exhibiting oscillatory and nonoscillatory behavior are used to illustrate the procedure and to compare results with estimates obtained using alternative approaches. The procedure is considerably simpler than recently proposed methods for this hydrogeologic setting. Although the simplifications required by the approach can introduce error into hydraulic-conductivity estimates, this additional error becomes negligible when appropriate measures are taken in the field. These measures are summarized in a set of practical field guidelines for slug tests in highly permeable aquifers.

  2. Fabrication of highly conductive carbon nanotube fibers for electrical application

    NASA Astrophysics Data System (ADS)

    Guo, Fengmei; Li, Can; Wei, Jinquan; Xu, Ruiqiao; Zhang, Zelin; Cui, Xian; Wang, Kunlin; Wu, Dehai

    2015-09-01

    Carbon nanotubes (CNTs) have great potential for use as electrical wires because of their outstanding electrical and mechanical properties. Here, we fabricate lightweight CNT fibers with electrical conductivity as high as that of stainless steel from macroscopic CNT films by drawing them through diamond wire-drawing dies. The entangled CNT bundles are straightened by suffering tension, which improves the alignment of the fibers. The loose fibers are squeezed by the diamond wire-drawing dies, which reduces the intertube space and contact resistance. The CNT fibers prepared by drawing have an electrical conductivity as high as 1.6 × 106 s m-1. The fibers are very stable when kept in the air and under cyclic tensile test. A prototype of CNT motor is demonstrated by replacing the copper wires with the CNT fibers.

  3. Powder-Derived High-Conductivity Coatings for Copper Alloys

    NASA Technical Reports Server (NTRS)

    Thomas-Ogbuji, Linus U.

    2003-01-01

    Makers of high-thermal-flux engines prefer copper alloys as combustion chamber liners, owing to a need to maximize heat dissipation. Since engine environments are strongly oxidizing in nature and copper alloys generally have inadequate resistance to oxidation, the liners need coatings for thermal and environmental protection; however, coatings must be chosen with great care in order to avoid significant impairment of thermal conductivity. Powder-derived chromia- and alumina- forming alloys are being studied under NASA's programs for advanced reusable launch vehicles to succeed the space shuttle fleet. NiCrAlY and Cu-Cr compositions optimized for high thermal conductivity have been tested for static and cyclic oxidation, and for susceptibility to blanching - a mode of degradation arising from oxidation-reduction cycling. The results indicate that the decision to coat the liners or not, and which coating/composition to use, depends strongly on the specific oxidative degradation mode that prevails under service conditions.

  4. Method for producing highly conformal transparent conducting oxides

    DOEpatents

    Elam, Jeffrey W.; Mane, Anil U.

    2016-07-26

    A method for forming a transparent conducting oxide product layer. The method includes use of precursors, such as tetrakis-(dimethylamino) tin and trimethyl indium, and selected use of dopants, such as SnO and ZnO for obtaining desired optical, electrical and structural properties for a highly conformal layer coating on a substrate. Ozone was also input as a reactive gas which enabled rapid production of the desired product layer.

  5. Hierarchical nanostructured conducting polymer hydrogel with high electrochemical activity

    PubMed Central

    Pan, Lijia; Yu, Guihua; Zhai, Dongyuan; Lee, Hye Ryoung; Zhao, Wenting; Liu, Nian; Wang, Huiliang; Tee, Benjamin C.-K.; Shi, Yi; Cui, Yi; Bao, Zhenan

    2012-01-01

    Conducting polymer hydrogels represent a unique class of materials that synergizes the advantageous features of hydrogels and organic conductors and have been used in many applications such as bioelectronics and energy storage devices. They are often synthesized by polymerizing conductive polymer monomer within a nonconducting hydrogel matrix, resulting in deterioration of their electrical properties. Here, we report a scalable and versatile synthesis of multifunctional polyaniline (PAni) hydrogel with excellent electronic conductivity and electrochemical properties. With high surface area and three-dimensional porous nanostructures, the PAni hydrogels demonstrated potential as high-performance supercapacitor electrodes with high specific capacitance (∼480 F·g-1), unprecedented rate capability, and cycling stability (∼83% capacitance retention after 10,000 cycles). The PAni hydrogels can also function as the active component of glucose oxidase sensors with fast response time (∼0.3 s) and superior sensitivity (∼16.7 μA·mM-1). The scalable synthesis and excellent electrode performance of the PAni hydrogel make it an attractive candidate for bioelectronics and future-generation energy storage electrodes. PMID:22645374

  6. A Novel Methodology to Synthesize Highly Conductive Anion Exchange Membranes

    NASA Astrophysics Data System (ADS)

    He, Yubin; Pan, Jiefeng; Wu, Liang; Zhu, Yuan; Ge, Xiaolin; Ran, Jin; Yang, Zhengjin; Xu, Tongwen

    2015-08-01

    Alkaline polyelectrolyte fuel cell now receives growing attention as a promising candidate to serve as the next generation energy-generating device by enabling the use of non-precious metal catalysts (silver, cobalt, nickel et al.). However, the development and application of alkaline polyelectrolyte fuel cell is still blocked by the poor hydroxide conductivity of anion exchange membranes. In order to solve this problem, we demonstrate a methodology for the preparation of highly OH- conductive anion exchange polyelectrolytes with good alkaline tolerance and excellent dimensional stability. Polymer backbones were grafted with flexible aliphatic chains containing two or three quaternized ammonium groups. The highly flexible and hydrophilic multi-functionalized side chains prefer to aggregate together to facilitate the formation of well-defined hydrophilic-hydrophobic microphase separation, which is crucial for the superior OH- conductivity of 69 mS/cm at room temperature. Besides, the as-prepared AEMs also exhibit excellent alkaline tolerance as well as improved dimensional stability due to their carefully designed polymer architecture, which provide new directions to pursue high performance AEMs and are promising to serve as a candidate for fuel cell technology.

  7. A Novel Methodology to Synthesize Highly Conductive Anion Exchange Membranes

    PubMed Central

    He, Yubin; Pan, Jiefeng; Wu, Liang; Zhu, Yuan; Ge, Xiaolin; Ran, Jin; Yang, ZhengJin; Xu, Tongwen

    2015-01-01

    Alkaline polyelectrolyte fuel cell now receives growing attention as a promising candidate to serve as the next generation energy-generating device by enabling the use of non-precious metal catalysts (silver, cobalt, nickel et al.). However, the development and application of alkaline polyelectrolyte fuel cell is still blocked by the poor hydroxide conductivity of anion exchange membranes. In order to solve this problem, we demonstrate a methodology for the preparation of highly OH− conductive anion exchange polyelectrolytes with good alkaline tolerance and excellent dimensional stability. Polymer backbones were grafted with flexible aliphatic chains containing two or three quaternized ammonium groups. The highly flexible and hydrophilic multi-functionalized side chains prefer to aggregate together to facilitate the formation of well-defined hydrophilic-hydrophobic microphase separation, which is crucial for the superior OH− conductivity of 69 mS/cm at room temperature. Besides, the as-prepared AEMs also exhibit excellent alkaline tolerance as well as improved dimensional stability due to their carefully designed polymer architecture, which provide new directions to pursue high performance AEMs and are promising to serve as a candidate for fuel cell technology. PMID:26311616

  8. Method and apparatus for connecting high voltage leads to a high temperature super-conducting transformer

    DOEpatents

    Golner, Thomas M.; Mehta, Shirish P.

    2005-07-26

    A method and apparatus for connecting high voltage leads to a super-conducting transformer is provided that includes a first super-conducting coil set, a second super-conducting coil set, and a third super-conducting coil set. The first, second and third super-conducting coil sets are connected via an insulated interconnect system that includes insulated conductors and insulated connectors that are utilized to connect the first, second, and third super-conducting coil sets to the high voltage leads.

  9. Highly conductive paper for energy-storage devices

    PubMed Central

    Hu, Liangbing; Choi, Jang Wook; Yang, Yuan; Jeong, Sangmoo; La Mantia, Fabio; Cui, Li-Feng; Cui, Yi

    2009-01-01

    Paper, invented more than 2,000 years ago and widely used today in our everyday lives, is explored in this study as a platform for energy-storage devices by integration with 1D nanomaterials. Here, we show that commercially available paper can be made highly conductive with a sheet resistance as low as 1 ohm per square (Ω/sq) by using simple solution processes to achieve conformal coating of single-walled carbon nanotube (CNT) and silver nanowire films. Compared with plastics, paper substrates can dramatically improve film adhesion, greatly simplify the coating process, and significantly lower the cost. Supercapacitors based on CNT-conductive paper show excellent performance. When only CNT mass is considered, a specific capacitance of 200 F/g, a specific energy of 30–47 Watt-hour/kilogram (Wh/kg), a specific power of 200,000 W/kg, and a stable cycling life over 40,000 cycles are achieved. These values are much better than those of devices on other flat substrates, such as plastics. Even in a case in which the weight of all of the dead components is considered, a specific energy of 7.5 Wh/kg is achieved. In addition, this conductive paper can be used as an excellent lightweight current collector in lithium-ion batteries to replace the existing metallic counterparts. This work suggests that our conductive paper can be a highly scalable and low-cost solution for high-performance energy storage devices. PMID:19995965

  10. Environmental impact and potential utilization of historical Cu-Fe-Co slags.

    PubMed

    Veselská, Veronika; Majzlan, Juraj

    2016-04-01

    Historical slags from the past Fe and Cu-Co production were investigated in order to evaluate either their potential for utilization or their long-term environmental risk for unsupervised old smelting areas. Here, we studied ferrous slags produced during the recovery of Fe from siderite-Cu ores in Slovakia and two different types of non-ferrous slags produced during the recovery of Cu and Co from Kupferschiefer ores in Germany. The glassy character, rare occurrence of primary silicate phases, and the lack of secondary phases in Cu slags indicate their stability for a prolonged period of time. Electron microprobe analytical work showed that the metals and metalloids (Cu, Co, Fe, Zn, Pb, As) are largely encased in droplets of matte and metal alloys and remain protected by the glassy matrix with its low weathering rate. Fe and Co slags are composed of high-temperature silicates such as wollastonite, cristobalite, as well as olivine, feldspar, quartz, leucite, pyroxene, and pyroxenoids. The presence of secondary phases attests to a certain degree metal release owing to weathering. Assuming minimal contents of metals in slags after a treatment with dilute H2SO4, slags could be used as pozzolanas for addition to cement. PMID:26681328