Sample records for chemical gradient-mediated melting

  1. Chemical reactions in solvents and melts

    Charlot, G


    Chemical Reactions in Solvents and Melts discusses the use of organic and inorganic compounds as well as of melts as solvents. This book examines the applications in organic and inorganic chemistry as well as in electrochemistry. Organized into two parts encompassing 15 chapters, this book begins with an overview of the general properties and the different types of reactions, including acid-base reactions, complex formation reactions, and oxidation-reduction reactions. This text then describes the properties of inert and active solvents. Other chapters consider the proton transfer reactions in

  2. Effect of melting pressure and superheating on chemical composition and contamination of yttria coated ceramic crucible induction melted titanium alloys

    Gomes, Fernando; Puga, Hélder; Barbosa, J; Ribeiro, Carlos Silva


    When melting reactive alloys, chemical composition and alloy homogeneity strongly depend on processing conditions, especially if melting is performed in ceramic crucibles. In this case, the nature of crucible materials, the melting stock composition and the melting parameters (atmosphere, pressure, superheating time and temperature) are critical processing variables. In this work, a Ti–48Al alloy was induction melted in a ZrO2 SiO2-based crucible with Y2O3 inner layer ...

  3. Nepheline structural and chemical dependence on melt composition

    Marcial, José; Crum, Jarrod; Neill, Owen; McCloy, John


    Nepheline crystallizes upon slow-cooling in some melts concentrated in Na2O and Al2O3, which can result in a residual glass phase of low chemical durability. Nepheline can incorporate many components often found in high-level waste radioactive borosilicate glass, including glass network ions (e.g., Si, Al, Fe), alkali metals (e.g., Cs, K, Na, and possibly Li), alkaline-earth metals (e.g., Ba, Sr, Ca, Mg), and transition metals (e.g., Mn, and possibly Cr, Zn, Ni). When crystallized from melts of different compositions, nepheline chemistry varies as a function of starting glass composition. Five simulated high level nuclear waste borosilicate glasses shown to crystallize large fractions of nepheline on slow cooling, were selected for study. These melts constituted a range of Al2O3, B2O3, CaO, Na2O, K2O, Fe2O3, and SiO2 compositions. Compositional analyses of nepheline crystals in glass by electron probe micro-analysis (EPMA) indicate that boron is unlikely to be present in any significant concentration, if at all, in nepheline. Also, several models are presented for calculating the fraction of vacancies in the nepheline structure.

  4. Melting and related precursor cooperative phenomena in chemically bonded assemblies

    A number of experimental studies of condensed matter assemblies with different types of chemical bonding will provide the focus of this work. Condensed compounds X(CH3)4, with X = C,Si or Ge, are the first of such assemblies; two phase boundaries in the pressure temperature plane being studied: melting and a solid phase boundary heralding orientational disordering of molecules still however on a lattice. Secondly, directionally bonded d-electron transition metals such as Ni, Pd and Nb will be treated. Here, melting is the main focus, but the precursor transition is now the separation of a high-temperature ductile solid from a lower temperature mechanically brittle phase. A dislocation-mediated model of these transitions is discussed, leading into the third area of covalently bonded solids graphite and silicon. Here topological defect models again provide the focus; both dislocations and rotation-dislocations now being invoked. Some qualitative suggestions are made to interpret the melting curve of graphite subjected to high pressure. (author)

  5. Raman spectroscopic studies of chemical speciation in calcium chloride melts

    Windisch, Charles F.; Lavender, Curt A.


    Raman spectroscopy was applied to CaCl2 melts at 900 degrees C under both non-electrolyzed and electrolyzed conditions. The later used titania cathodes supplied by TIMET, Inc. and graphite anodes. Use of pulse-gating to collect the Raman spectra successfully eliminated any interference from black-body radiation and other stray light. The spectrum of molten CaCl2 exhibited no distinct, resolvable bands that could be correlated with a calcium chloride complex similar to MgCl42- in MgCl2 melts. Rather, the low frequency region of the spectrum was dominated by a broad “tail” arising from collective oscillations of both charge and mass in the molten salt “network.” Additions of both CaO and Ca at concentrations of a percent or two resulted in no new features in the spectra. Addition of CO2, both chemically and via electrolysis at concentrations dictated by stability and solubility at 900 degrees C and 1 bar pressure, also produced no new bands that could be correlated with either dissolved CO2 or the carbonate ion. These results indicated that Raman spectroscopy, at least under the conditions evaluated in the research, was not well suited for following the reactions and coordination chemistry of calcium ions, nor species such as dissolved metallic Ca and CO2 that are suspected to impact current efficiency in titanium electrolysis cells using molten CaCl2. Raman spectra of TIMET titania electrodes were successfully obtained as a function of temperature up to 900 degrees C, both in air and in-situ in CaCl2 melts. However, spectra of these electrodes could only be obtained when the material was in the unreduced state. When reduced, either with hydrogen or within an electrolysis cell, the resulting electrodes exhibited no measurable Raman bands under the conditions used in this work.

  6. Heads or tails: how do chemically substituted fullerenes melt?

    Armstrong, Jeff; Mukhopadhyay, Sanghamitra; Bresme, Fernando; Fernandez-Alonso, Felix


    We address the question as to whether the melting of chemically substituted fullerenes is driven by the dynamics of the fullerene moiety (the head) or the substituted sub-unit (the tail). To this end, we have performed quasielastic neutron-scattering experiments and classical molecular-dynamics simulations as a function of temperature on the prototypical fullerene derivative phenyl-C61-butyric acid methyl ester. To enable a direct and quantitative comparison between experimental and simulation data, dynamic structure factors for the latter have been calculated from atomic trajectories and further convolved with the known instrument response. A detailed analysis of the energy- and momentum-transfer dependence of this observable in the quasielastic regime shows that melting is entirely driven by temperature-activated tail motions. We also provide quantitative estimates of the activation energy for this process as the material first enters a plastic-crystalline phase, followed by the emergence of a genuine liquid at higher temperatures. PMID:27087579

  7. MEMIN: Chemical Modification of Projectile Spheres, Target Melts and Shocked Quartz in Hypervelocity Impact Experiments

    Ebert, M.; Hecht, L.; Deutsch, A.; Kenkmann, T.


    We present results of hypervelocity cratering experiments using iron meteorite as projectile and a sandstone target. The ejecta show shock features (melting, PDFs, lechatelierite) and physical as well as chemical mixing between projectile and target.

  8. Mathematical modeling of quartz particle melting process in plasma-chemical reactor

    Volokitin, Oleg, E-mail:; Volokitin, Gennady, E-mail:; Skripnikova, Nelli, E-mail:; Shekhovtsov, Valentin, E-mail: [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Vlasov, Viktor, E-mail: [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Ave., 634050, Tomsk (Russian Federation)


    Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ r{sub p} ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ r{sub p} ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature.

  9. Mathematical modeling of quartz particle melting process in plasma-chemical reactor

    Volokitin, Oleg; Vlasov, Viktor; Volokitin, Gennady; Skripnikova, Nelli; Shekhovtsov, Valentin


    Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ rp ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ rp ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature.

  10. Mathematical modeling of quartz particle melting process in plasma-chemical reactor

    Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ rp ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ rp ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature

  11. The mineralogical, chemical, and chronological characteristics of the crystalline Apollo 16 impact melt rocks

    Reimold, W. U.; Reimold, J. N.


    A comparative review of mineralogical, chemical, and chronological data on crystalline Apollo 16 impact melt rocks is presented. The use of such data to identify distinct impact melt complex is discussed, and 22 distinct impact melt bodies are identified. The recently detected group of feldspathic microporphyritic (FM) melt rocks was tested for chemical and isotopic homogeneity; instrumental neutron activation analysis and new Rb-Sr isotopic whole rock data indicate that FMs were probably not derived from a single impact melt sheet, but might be representative of the Descartes basement. Stratigraphical and chronological concepts for the geological development of the landing site are discussed, and a model is presented for the formation of the Cayley Plains and the Descartes formation.


    Holubcik, Michal; Jandacka, Jozef; Malcho, Milan


    Solid fuels, including biomass, consist of combustible, ash and water. Ash in fuel is result of reaction of minerals presented in the biomass. Minerals and other different substances which form ash got into biomass during growth. Ash is solid residue resulted from the perfect laboratory combustion of fuel. It is composed of minerals that are present in the fuel. Some species of biomass ash have low ash melting temperature and can cause various problems in combustion boilers. Ash slags and sin...

  13. Melting behavior of typical thermoplastic materials – An experimental and chemical kinetics study

    Highlights: • A new medium-scale melting and pyrolysis experiment instrument for thermoplastics was designed. • The thermal hazard induced by melting and dripping of thermoplastics was studied. • The medium-scale experimental results on the thermoplastics pyrolysis suggest some limit for TGA tests. -- Abstract: A medium-scale melting experiment rig was designed and constructed in this study. A detailed experimental study was conducted on the melting behavior and the chemical kinetic characteristics of three typical thermoplastic materials, including polypropylene (PP), polyethylene (PE) and polystyrene (PS). It is observed that the thermal decomposition of the thermoplastic materials mainly consists of three stages: the initial heating stage, the melting-dominated stage and the gasification-dominated stage. Melting of the materials examined takes place within a certain temperature range. The melting temperature of PS is the lowest, moreover, it takes the shortest time to be completely liquefied. To quantitatively represent the chemical kinetics, an nth-order reaction model was employed to interpret the thermal decomposition behavior of the materials. The calculated reaction order is largely in accordance with the small-scale thermal gravimetric analysis (TGA). The small difference between the results and TGA data suggests that there are some limitations in the small-scale experiments in simulating the behavior of thermoplastic materials in a thermal hazard. Therefore, investigating the thermal physical and chemical properties of the thermoplastic materials and their thermal hazard prevention in medium or large-scale experiments is necessary for the fire safety considerations of polymer materials

  14. Chemical diffusion characteristics of Al–Si alloy melts under a transverse magnetic field

    Zhang, Kai; Bian, Xiufang, E-mail:; Li, Yumin; Liu, Yang; Yang, Chuncheng; Zhao, Xiaolin


    Effect of a transverse magnetic field on the chemical diffusion (interdiffusion) characteristics between Al–10 at.% Si metallic melts and pure Al melts has been investigated experimentally. Results show that the application of a weak transverse magnetic field has evidently decreased the diffusivity of solute atoms and retarded the interdiffusion process. This effect can be attributed to the combined suppression action of interior Hall Effect and Lorentz force on the atoms mobility. - Highlights: • Effect of magnetic field on the interdiffusion behavior of Al–Si melt is obtained. • The magnetic field impedes the atomic diffusion of Al–Si melt. • The physical model of interdiffusion is established based on Hall Effect.

  15. Note: X-ray radiography for measuring chemical diffusion in metallic melts

    Griesche, A.; Zhang, B.; Solórzano, E.; Garcia-Moreno, F.


    A x-ray radioscopy technique for measuring in situ chemical diffusion coefficients in metallic melts is presented. The long-capillary diffusion measurement method is combined with imaging techniques using microfocus tubes and flat panel detectors in order to visualize and quantitatively analyze diffusive mixing of two melts of different chemical composition. The interdiffusion coefficient as function of temperature and time is obtained by applying Fick's diffusion laws. Tracking the time dependence of the mean square penetration depth of the mixing process allows to detect changes in the mass transport caused by convective flow. The possibility to sort out convective mass transport contributions from analysis enhances significantly the accuracy compared to the conventional long-capillary diffusion measurement method with postmortem analysis. The performance of this novel diffusion measurement method with x-ray radiography technique is demonstrated by a diffusion experiment in an Al-Ni melt.

  16. Note: X-ray radiography for measuring chemical diffusion in metallic melts

    A x-ray radioscopy technique for measuring in situ chemical diffusion coefficients in metallic melts is presented. The long-capillary diffusion measurement method is combined with imaging techniques using microfocus tubes and flat panel detectors in order to visualize and quantitatively analyze diffusive mixing of two melts of different chemical composition. The interdiffusion coefficient as function of temperature and time is obtained by applying Fick's diffusion laws. Tracking the time dependence of the mean square penetration depth of the mixing process allows to detect changes in the mass transport caused by convective flow. The possibility to sort out convective mass transport contributions from analysis enhances significantly the accuracy compared to the conventional long-capillary diffusion measurement method with postmortem analysis. The performance of this novel diffusion measurement method with x-ray radiography technique is demonstrated by a diffusion experiment in an Al-Ni melt.

  17. Thermodynamic properties of Cu–Zr melts: The role of chemical interaction

    Kulikova, T.V.; Majorova, A.V.; Shunyaev, K.Yu. [Institute of Metallurgy, Ural Division of Russian Academy of Sciences, Amudsena str. 101, 620016 Ekaterinburg (Russian Federation); Ryltsev, R.E., E-mail: [Institute of Metallurgy, Ural Division of Russian Academy of Sciences, Amudsena str. 101, 620016 Ekaterinburg (Russian Federation); Ural Federal University, Mira str. 19, 620002 Ekaterinburg (Russian Federation)


    General statistical model is applied to analyze the role of chemical interaction in associated systems. We show that, at certain conditions, chemical interaction between associates may be not essential above a distectic point and so the model of ideal associated solutions is a good approximation for describing high temperature properties of associated system with chemical interaction. Within the frames of such conception, we calculate thermodynamic properties of Cu–Zr system in liquid state. The enthalpies of formation of Cu–Zr intermetallic compounds were redefined by using matching procedure taking into account the additive manifestation of chemical interaction. We conclude that simple model which is free of adjusting parameters allows us to calculate thermodynamic properties of Cu–Zr melts with quite good accuracy.

  18. Experiments on interactions between zirconium-containing melt and water (ZREX). Hydrogen generation and chemical augmentation of energetics

    Cho, D.H.; Armstrong, D.R.; Gunther, W.H. [Argonne National Lab., IL (United States); Basu, S.


    The results of the first data series of experiments on interactions between zirconium-containing melt and water are described. These experiments involved dropping 1-kg batches of pure zirconium or zirconium-zirconium dioxide mixture melt into a column of water. A total of nine tests were conducted, including four with pure zirconium melt and five with Zr-ZrO{sub 2} mixture melt. Explosions took place only in those tests which were externally triggered. While the extent of zirconium oxidation in the triggered experiments was quite extensive, the estimated explosion energetics were found to be very small compared to the combined thermal and chemical energy available. (author)

  19. Chemical speciation of U, Fe, and Pu in melt glass from nuclear weapons testing

    Pacold, J. I.; Lukens, W. W.; Booth, C. H.; Shuh, D. K.; Knight, K. B.; Eppich, G. R.; Holliday, K. S.


    Nuclear weapons testing generates large volumes of glassy materials that influence the transport of dispersed actinides in the environment and may carry information on the composition of the detonated device. We determine the oxidation state of U and Fe (which is known to buffer the oxidation state of actinide elements and to affect the redox state of groundwater) in samples of melt glass collected from three U.S. nuclear weapons tests. For selected samples, we also determine the coordination geometry of U and Fe, and we report the oxidation state of Pu from one melt glass sample. We find significant variations among the melt glass samples and, in particular, find a clear deviation in one sample from the expected buffering effect of Fe(II)/Fe(III) on the oxidation state of uranium. In the first direct measurement of Pu oxidation state in a nuclear test melt glass, we obtain a result consistent with existing literature that proposes Pu is primarily present as Pu(IV) in post-detonation material. In addition, our measurements imply that highly mobile U(VI) may be produced in significant quantities when melt glass is quenched rapidly following a nuclear detonation, though these products may remain immobile in the vitrified matrices. The observed differences in chemical state among the three samples show that redox conditions can vary dramatically across different nuclear test conditions. The local soil composition, associated device materials, and the rate of quenching are all likely to affect the final redox state of the glass. The resulting variations in glass chemistry are significant for understanding and interpreting debris chemistry and the later environmental mobility of dispersed material.

  20. Physical, chemical and electrochemical behaviour of boron oxide in cryolite-alumina melts

    The chemical, physical and electrochemical behaviour of the boron oxide in the cryolite-alumina melts is studied through the thermogravimetry and cyclic volt-amperometry at the temperature of 1000-1020 deg C. It is established, that introduction of the boron oxide into the molten cryolite in the form of its compound with the aluminium oxide of the 2Al2O3·B2O3 composition leads to the melt stabilization and decreases the boron losses in the form of the volatile BF3. In this case the electrochemical reduction of the boron oxide up to the elementary boron proceeds in one stage and it is the most electropositive process in the given system

  1. Probing Seismically Melting Induced Mantle Heterogeneities in Thermal-chemical Convection Models

    Heck, H. V.; Davies, H.; Nowacki, A.; Wookey, J. M.


    Two regions at the base of the Earth's mantle (the Large Low-Shear Velocity Provinces) pose a fundamental problem in understanding large-scale mantle dynamics and history. Are they dense piles of (possibly primordial) material separated from mantle circulation, or large-scale thermal features which are part of global mantle convection? Or some combination of the two? We use our numerical 3D spherical mantle convection code to perform simulations of the Earths mantle dynamical evolution. We drive the surface velocity of the model according to 200 Ma plate motion reconstructions, to arrive at Earth-like structures in the mantle at present day. Variations in bulk chemistry will be tracked in two ways: 1) by starting the calculations with a (primordial) dense layer at the base of the mantle, and 2) by tracking basalt fraction which is fractionated upon melting close to the surface. The resulting distribution of chemical heterogeneity and temperature will be converted to seismic velocities. This will be done with a thermodynamical database (Stixrude & Lithgow-Bertelloni, GJI, 2005, 2011), allowing us to compare the model with previous observations of triplications and waveform complexity near the margins of the LLSVPs. These observations have been taken as proof that strong chemical variations are present; our simulations can be used to show whether this is true, or if purely thermal convection can also cause these features. We simulate finite-frequency, 3D seismograms at ~5 s period and compare these with previous studies.

  2. Viscosity and chemical diffusion of halogens in silicate melts: implications for volcanic degassing

    Wasik, A.; Dingwell, D. B.; Courtial, P.; Hess, K.


    The efficiency of degassing processes in subduction zone volcanism may be affected by the magmato-hydrothermal geochemistry of halogens. In addition halogens may act as potential monitors of degassing efficiency and provide answers to the question of the role of disequilibrium during partitioning. Too little is known quantitatively about the transport properties of halogens in silicate melts. In particular, an accurate study of the transport properties of halogens should help to unlock the information contained in halogen concentrations of eruptive products and volcanic gases. For these reasons the chemical diffusivities of the halogens (fluorine, bromine, chlorine and iodine) have been measured in the synthetic Fe-bearing sodium disilicate melts, within a wide range of temperature (650-1400° C). The experiments were performed using diffusion couple technique. Halogens were added to the starting material in the form of FeF3, FeBr3, FeCl3 and FeI2 and stirred in concentric cylinder viscometer. The temperature was restricted to 1000-1100° C to avoid volatilization of halogens. After synthesis the samples were drilled, cut into 2mm disks and then doubly polished. Prepared disks were putted into platinum tubes (5mm diameter) and sealed by welding. The halogen rich sample was located at the bottom. During the experiments the temperature was monitored with a thermocouple located at the vicinity of the capsule. Run durations were between 30 minutes and 1 hour. The recovered samples were analyzed using an electron microprobe in order to determine the diffusion profiles of the halogens. The results were obtained by using Boltzmann-Matano method and they suggest at least 3 orders of magnitude range at 1000° C between the diffusion coefficients for F, Br, Cl and I. The fastest diffusing species was found to be fluorine, the slowest - iodine. In order to place the diffusivity measurements in the context of their extrinsic versus intrinsic nature, viscosity measurements were

  3. Melting and chemical reactivity of hydrocarbons under high pressure and temperature

    Lobanov, S.; Chanyshev, A.; Chen, P.; Litasov, K.; Chen, X.; Goncharov, A.


    Hydrocarbons comprise roughly ⅓ of the icy mantles in interiors of icy giant planets and may determine the planetary physical properties. Here we present the results of laser heated diamond anvil cell experiments on hydrocarbon chemical reactivity at P up to 50 GPa and T up to 2000 K. Ethane (C2H6) and n-docosane (C22H46) were chosen as starting materials. Raman spectroscopy at high P was used to probe the C-H systems. Melting lines of the hydrocarbons were found by visual observations of fluid-solid interface. The melting lines lie below 1500 K at P1000 K and P25-30 GPa. Remarkably, free H2 was found in experiments at P>30-35 GPa. The interpretation of Raman spectra of quenched reaction products is uncertain. In general, P and T affect the lifetimes of C-H and C-C bonds. Temperature provides energy to brake C-H and C-C bonds, while stabilization of the bonds with pressure may be more pronounced for C-C bonds. The composition of C-H fluid is determined by the competition between C-C and C-H bonds. This competition can result in hydrocarbons with long C-C network. The role of C=C and C≡C bonds at high P cannot be ruled out from this study. It is possible that unsaturated hydrocarbons appear upon quenching from highly dissociated C-H fluid rather than being present in C-H fluid. n-docosane at 12 GPa Ethane at 34 GPa

  4. Chemical and mineralogical evaluation of slag products derived from the pyrolysis/melting treatment of MSW.

    Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki; Motomura, Yoshinobu; Watanabe, Koichiro


    This paper provides the results of studies on the characteristics of novel material derived from pyrolysis/melting treatment of municipal solid waste in Japan. Slag products from pyrolysis/melting plants were sampled for the purpose of detailed phase analysis and characterization of heavy metal-containing phases using optical microscopy, electron probe microanalysis (EPMA), XRF and XRD. The study revealed that the slag material contains glass (over 95%), oxide and silicate minerals (spinel, melilite, pseudowollastonite), as well as individual metallic inclusions as the major constituents. A distinct chemical diversity was discovered in the interstitial glass in terms of silica content defined as low and high silica glass end members. Elevated concentrations of Zn, Cr, Cu, Pb and Ba were recorded in the bulk composition. Cu, Pb and Ba behave as incompatible elements since they have been markedly characterized as part of polymetallic alloys and insignificantly sulfides in the form of spherical metallic inclusions associated with tracer amounts of other elements such as Sb, Sn, Ni, Zn, Al, P and Si. In contrast, an appreciable amount of Zn is retained by zinc-rich end members of spinel and partially by melilite and silica glass. Chromium exhibits similar behavior, and is considerably held by Cr-rich spinel. The intense incorporation of Zn and Cr into spinel indicates the very effective enrichment of these two elements into phases more environmentally resistant than glass. There was no evidence, however, that Cu and Pb enter into the structure of the crystalline silicates or oxides that may lead to their easier leachability upon exposure to the environment. PMID:16446083

  5. Effects of chemical composition of fly ash on efficiency of metal separation in ash-melting of municipal solid waste

    Highlights: ► Separation of Pb and Zn from Fe and Cu in ash-melting of municipal solid waste. ► Molar ratio of Cl to Na and K in fly ash affected the metal-separation efficiency. ► The low molar ratio and a non-oxidative atmosphere were better for the separation. - Abstract: In the process of metal separation by ash-melting, Fe and Cu in the incineration residue remain in the melting furnace as molten metal, whereas Pb and Zn in the residue are volatilized. This study investigated the effects of the chemical composition of incineration fly ash on the metal-separation efficiency of the ash-melting process. Incineration fly ash with different chemical compositions was melted with bottom ash in a lab-scale reactor, and the efficiency with which Pb and Zn were volatilized preventing the volatilization of Fe and Cu was evaluated. In addition, the behavior of these metals was simulated by thermodynamic equilibrium calculations. Depending on the exhaust gas treatment system used in the incinerator, the relationships among Na, K, and Cl concentrations in the incineration fly ash differed, which affected the efficiency of the metal separation. The amounts of Fe and Cu volatilized decreased by the decrease in the molar ratio of Cl to Na and K in the ash, promoting metal separation. The thermodynamic simulation predicted that the chlorination volatilization of Fe and Cu was prevented by the decrease in the molar ratio, as mentioned before. By melting incineration fly ash with the low molar ratio in a non-oxidative atmosphere, most of the Pb and Zn in the ash were volatilized leaving behind Fe and Cu

  6. Effects of temperature, pressure and chemical compositions on the electrical conductivity of carbonated melts and its relationship with viscosity

    Sifré, David; Hashim, Leïla; Gaillard, Fabrice


    International audience Carbonated melts constitute a key medium in the global deep carbon cycle: their impact on the geochemical signature of deep rocks is well studied because of their role as metasomatic agents in the deep mantle. However, their physical properties and in particular their electrical conductivity at high temperature and high pressure remain poorly constrained. In this study, we investigated the effect of chemical composition on the electrical conductivity of carbonated me...

  7. Physical and chemical consequences of crustal melting in fossil mature intra-oceanic arcs

    Berger, J.; Burg, J.-P.


    Seismic velocity models of active intra-oceanic arcs show roots with densities and P-wave velocities intermediate to classical lower oceanic crust (density; ~3.0, Vp: ~7.0 km/s) and uppermost harzburgitic mantle (density: 3.2-3.3, Vp: 7.9-8.0 km/s). Most studies on active and fossil exhumed island arcs interpret the petrological nature of this root as ultramafic cumulates crystallized from primitive melts and/or as pyroxenites formed via basalt-peridotite reactions. Igneous cumulates and pyroxenites have densities close to or above that of uppermost mantle rocks; they can consequently undergo gravity-driven delamination, a process thought to drive the bulk composition of the arc toward an andesitic, continental crust-like composition. Dehydration and melting reactions are reported from exposed arc roots (Jijal complex in Kohistan; Amalaoulaou arc in Mali; Fiordland arc in New-Zealand). Intense influx of mantle-derived basaltic magmas at high pressure in a thickening island arc can enable lower crustal rocks to locally cross the dehydration-melting solidus of hydrous subalkaline basalts. Thermodynamic modeling using Perple_X, geochemical analysis and compilation of experimental and field data have been combined to constrain processes, conditions and consequences of intra-arc melting. The position of the solidus in a P-T grid is strongly dependent of the bulk water content: at 1 GPa, it is as low as 750 °C for water saturated hornblende-gabbros (>1 wt% H2O) and 830°C for gabbros with 0.1 wt% H2O. Incipient melting (F <10 %) near the solidus produces trondhjemitic melt and garnet granulites residue. The latter has composition very close to that of igneous precursors but is characterized by contrasted physical properties (density: 3.2-3.3, Vp: 6.9-7.4 km/s). Higher partial melting degrees (F: 10-20 %) lead to the formation of anorthositic melts in equilibrium with garnet-clinopyroxene-rutile residues (density: up to 3.45, Vp: up to 7.7 km/s). These melts are rich in

  8. Physical and chemical properties of fluid and melt inclusions of the Lagoa Real uraniferous albitites (Brazil)

    Chaves, Alexandre de Oliveira, E-mail: [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Inst. de Geociencias; Rios, Francisco Javier; Alves, James Vieira; Chaves, Adriana Monica Dalla Vecchia; Fuzikawa, Kazuo; Neves, Jose Marques Correia [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)


    Data of melt and fluid inclusions obtained by LA-ICP-MS and microthermometry techniques represent an important investigation complement to understand geological processes which took place in Lagoa Real uraniferous albitites (Brazil). Melt inclusions found in augite structure, which reveals the previous presence of U in the syenitic magma. Primary fluid inclusions in magmatic augite of the albitites contain Na, denoting once more its presence in original magma. The formation of andradite from augite during shear events that generated the metamorphosed syenite (uraniferous albitite) was certified by the ICP-MS signals and uranium released by magmatic titanite (U source mineral)during the 1.9 Ga metamorphism was recorded in the fluid inclusions found in andradite, mineral that was formed in this same metamorphic event which recrystallized titanite crystals. Such uranium was responsible by precipitation of the disseminated uraninite found inside andradite. (author)

  9. In-can melting demonstration of wastes from the Idaho Chemical Processing Plant

    The immobilization of Idaho Chemical Processing Plant (ICPP) zirconia calcine using Idaho glass composition (ICPP-127) was evaluated at Pacific Northwest Laboratory (PNL) in two engineering-scale in-can melter tests. The glass was initially characterized in the laboratory to verify processing parameters. Glass was then produced in a pilot-scale melter and then in a full-scale melter to evaluate the processing and the resultant product. Potential corrosion problems were identified with the glass and some processing problems were encountered, but neither is insurmountable. The product is a durable leach-resistant glass. The glass appears to be nonhomogeneous, but chemically it is quite uniform

  10. Termination of light-water reactor core-melt accidents with a chemical core catcher: the core-melt source reduction system (COMSORS)

    The Core-Melt Source Reduction System (COMSORS) is a new approach to terminate light-water reactor core melt accidents and ensure containment integrity. A special dissolution glass is placed under the reactor vessel. If core debris is released onto the glass, the glass melts and the debris dissolves into the molten glass, thus creating a homogeneous molten glass. The molten glass, with dissolved core debris, spreads into a wide pool, distributing the heat for removal by radiation to the reactor cavity above or by transfer to water on top of the molten glass. Expected equilibrium glass temperatures are approximately 600 degrees C. The creation of a low-temperature, homogeneous molten glass with known geometry permits cooling of the glass without threatening containment integrity. This report describes the technology, initial experiments to measure key glass properties, and modeling of COMSORS operations

  11. Termination of light-water reactor core-melt accidents with a chemical core catcher: the core-melt source reduction system (COMSORS)

    Forsberg, C.W.; Parker, G.W.; Rudolph, J.C.; Osborne-Lee, I.W. [Oak Ridge National Lab., TN (United States); Kenton, M.A. [Dames and Moore, Westmont, IL (United States)


    The Core-Melt Source Reduction System (COMSORS) is a new approach to terminate light-water reactor core melt accidents and ensure containment integrity. A special dissolution glass is placed under the reactor vessel. If core debris is released onto the glass, the glass melts and the debris dissolves into the molten glass, thus creating a homogeneous molten glass. The molten glass, with dissolved core debris, spreads into a wide pool, distributing the heat for removal by radiation to the reactor cavity above or by transfer to water on top of the molten glass. Expected equilibrium glass temperatures are approximately 600 degrees C. The creation of a low-temperature, homogeneous molten glass with known geometry permits cooling of the glass without threatening containment integrity. This report describes the technology, initial experiments to measure key glass properties, and modeling of COMSORS operations.

  12. On the Chemical Evolution of Upper Mantle of the Early Earth—An Experimental Study on Melting of the Silicate Phase in Jilin Chondrite at High Pressures

    谢鸿森; 方虹; 等


    Relatively old ages of chondrites(normally around 4.5Ga)suggest that their parent bodies did not experience any mely-fractionation under high temperature and high pressure conditions pertaining to the interior of terrestrial plaets.Therefore,it is reasonable to take chondrites as starting materials in the study of the chemical evolution of the early earth.The sillicate phase in the Jilin chondrite (H5)was chosen for this purpose because it possesses a chemical composition similar to that of the primitive mantle.The melting experiment was carried out at 20-30 k bar and has rsulted in a product which contains1-5% melts in addition to solid cryustal phase.The chemical composition of the melt phases and the partitioning of various elements between the coexisting silicate melts are geochemically similar to those of anatectic rocks on the earth.This can thus serve as the basis for discussing the chemical evolution of the early upper mantle.

  13. Olivine and melt inclusion chemical constraints on the source of intracontinental basalts from the eastern North China Craton: Discrimination of contributions from the subducted Pacific slab

    Li, Hong-Yan; Xu, Yi-Gang; Ryan, Jeffrey G.; Huang, Xiao-Long; Ren, Zhong-Yuan; Guo, Hua; Ning, Zhen-Guo


    Contributions from fluid and melt inputs from the subducting Pacific slab to the chemical makeup of intraplate basalts erupted on the eastern Eurasian continent have long been suggested but have not thus far been geochemically constrained. To attempt to address this question, we have investigated Cenozoic basaltic rocks from the western Shandong and Bohai Bay Basin, eastern North China Craton (NCC), which preserve coherent relationships among the chemistries of their melt inclusions, their hosting olivines and their bulk rock compositions. Three groups of samples are distinguished: (1) high-Si and (2) moderate-Si basalts (tholeiites, alkali basalts and basanites) which were erupted at ∼23-20 Ma, and (3) low-Si basalts (nephelinites) which were erupted at eclogite derived from subducted Pacific slab materials present in the deeper mantle. High degree melting of garnet pyroxenites from a shallower mantle source produced the early (∼23-20 Ma) higher-Si basalts. Mixing of these materials with deeper-sourced melts of carbonated mantle source produced the moderate-Si basalts. A thicker lithosphere after 9 Ma precluded melting of shallower garnet pyroxenites, so melts of the deeper carbonated mantle source are responsible for the low-Si basalts.

  14. Report on the relevance and feasibility of measurements of the heat of chemical reactions during core meltdown and of the integral heat content of core melts. Pt. 2

    In the feasibility study chemical reactions which seemed to need experimental investigation had to be identified with special reference to the accident simulation by computer codes. For selected reactions, measuring methods and measuring set-ups had to be devised. A total of seven chemical reactions requiring experimental investigation were identified. In line with the current emphasis within the core meltdown research programme, three subjects were selected: (a) the exothermic steel melt-steam reaction during the core melt-concrete interaction, (b) the reaction which may occur immediately after the rupture of the reactor pressure vessel, between the metal melt, which contains steel and residual amounts of zirconium, and the containment atmosphere, and (c) the total of all reactions occuring during core melt-concrete interaction (integral reaction). Measuring methods and detailed set-ups for experimental investigations were conceived for the first two reactions. The apparatus were designed such that they can also be used for other investigations on chemical reactions during core meltdown. As regards the determination of integral heat of reaction by means of high-temperature calorimetry, the study showed that experimental difficulties may arise if gaseous reactions are involved. (orig.) 891 HP

  15. Effect of Alkali-Acid-Heat Chemical Surface Treatment on Electron Beam Melted Porous Titanium and Its Apatite Forming Ability

    Suzan Bsat


    Full Text Available Advanced additive manufacturing techniques such as electron beam melting (EBM, can produce highly porous structures that resemble the mechanical properties and structure of native bone. However, for orthopaedic applications, such as joint prostheses or bone substitution, the surface must also be bio-functionalized to promote bone growth. In the current work, EBM porous Ti6Al4V alloy was exposed to an alkali acid heat (AlAcH treatment to bio-functionalize the surface of the porous structure. Various molar concentrations (3, 5, 10M and immersion times (6, 24 h of the alkali treatment were used to determine optimal parameters. The apatite forming ability of the samples was evaluated using simulated body fluid (SBF immersion testing. The micro-topography and surface chemistry of AlAcH treated samples were evaluated before and after SBF testing using scanning electron microscopy and energy dispersive X-ray spectroscopy. The AlAcH treatment successfully modified the topographical and chemical characteristics of EBM porous titanium surface creating nano-topographical features ranging from 200–300 nm in size with a titania layer ideal for apatite formation. After 1 and 3 week immersion in SBF, there was no Ca or P present on the surface of as manufactured porous titanium while both elements were present on all AlAcH treated samples except those exposed to 3M, 6 h alkali treatment. An increase in molar concentration and/or immersion time of alkali treatment resulted in an increase in the number of nano-topographical features per unit area as well as the amount of titania on the surface.

  16. X-ray photoelectron spectroscopy and electron probe X-ray microanalysis investigation and chemical speciation of aerosol samples formed in light water reactor core-melting experiments

    Aerosol samples consisting of fission products and elements of light water reactor structural materials were collected during laboratory-scale simulation of the heat-up phase of a core melt accident. The aerosol particles were formed in a steam atmosphere at temperatures of the melting charge between 1200 and 19000C. The investigation of the samples by use of x-ray photoelectron spectroscopy (XPS) permitted the chemical speciation of the detected aerosol constituents silver, cadmium, indium, tellurium, iodine, and cesium. A comparison of the elemental analysis results obtained from XPS with those achieved from electron probe x-ray microanalysis revealed that aerosol particle surface and aerosol particle bulk are principally composed of the same elements. The compositions determined in dependence of the release temperature reflect the differing volatilities of the detected elements. Quantitative differences between the composition of surface and bulk have been observed only for those aerosol samples that were collected at higher melting charge temperatures. These samples show an enrichment of more volatile species at the particles' surfaces. In order to obtain direct information on chemical species below the surface, selected samples were argon ion bombarded. Changes in composition and chemistry were monitored by XPS, and the results were interpreted under consideration of possible influences of the sputter process on the surface composition

  17. Thermodynamics of Glass Melting

    Conradt, Reinhard

    First, a model based on linear algebra is described by which the thermodynamic properties of industrial multi-component glasses and glass melts can be accurately predicted from their chemical composition. The model is applied to calculate the heat content of glass melts at high temperatures, the standard heat of formation of glasses from the elements, and the vapor pressures of individual oxides above the melt. An E-fiber glass composition is depicted as an example. Second, the role of individual raw materials in the melting process of E-glass is addressed, with a special focus on the decomposition kinetics and energetic situation of alkaline earth carriers. Finally, the heat of the batch-to-melt conversion is calculated. A simplified reaction path model comprising heat turnover, content of residual solid matter, and an approach to batch viscosity is outlined.

  18. Chemical durability of slag produced by thermal plasma melting of low-level miscellaneous solid wastes. Effects of slag composition

    Low-level radioactive miscellaneous solid wastes are generated from commercial operation of nuclear power plants and will be generated from decommissioning of nuclear power plants in future. Static leaching tests were carried out in deionized water of 10degC on slag obtained by thermal plasma melting of simulating materials of the miscellaneous solids wastes with surrogate elements of radionuclides. It is found that logarithm of normalized elemental mass loss from the slag is proportional to the basicity represented by mole fractions of main structural oxides of the slag, such as SiO2, Al2O3, CaO, FeO and MgO. The range of static leaching rates from the slag is determined based on the above results and the basicity range of the miscellaneous solid wastes. Then we compared the leaching rates form the slag and from high level waste glasses. On these grounds, we concluded that the slag obtained by thermal plasma melting of miscellaneous solid wastes can stabilize radio-nuclides in it by no means inferior to the high level waste glasses. (author)

  19. Characterization of chemically sprayed CdO films on borate and phosphate glass substrates produced by melt-quenching technique

    The properties of substrates used to deposit thin films are an important parameter in thin film production. Instead of using a commercial substrate, in this work, borate and phosphate glasses have been obtained by classic melt-quenching technique to be used as substrates for CdO films. Also, a microscope glass substrate has been used to compare the coating properties by other glass substrates. All films have been produced by Ultrasonic Spray Pyrolysis technique. The substrate temperature has been selected as 275 ± 5 °C. Thicknesses and some optical parameters such as refractive index and extinction coefficient have been determined by spectroscopic ellipsometry. Absorbance and transmittance spectra have been taken by UV/VIS spectrophotometer. Four-probe method has been used to determine the electrical resistivity values of the films. XRD investigations have shown that type of the substrate dramatically affects the characteristics of CdO films. CdO film deposited on phosphate glass substrate has the best structural quality. Atomic Force Microscope has been used to investigate the surface properties and roughness values of the films. - Highlights: ► Borate/phosphate glasses were prepared by melt-quenching and used as substrates. ► Alternative, low resistive CdO films were deposited by an economical technique. ► A low refractive index (by Spectroscopic Ellipsometry) CdO film was obtained

  20. The chemical digestion of Ti6Al7Nb scaffolds produced by Selective Laser Melting reduces significantly ability of Pseudomonas aeruginosa to form biofilm.

    Junka, Adam F; Szymczyk, Patrycja; Secewicz, Anna; Pawlak, Andrzej; Smutnicka, Danuta; Ziółkowski, Grzegorz; Bartoszewicz, Marzenna; Chlebus, Edward


    In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann-Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann-Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements. PMID:27150429

  1. Selective Laser Sintering And Melting Of Pristine Titanium And Titanium Ti6Al4V Alloy Powders And Selection Of Chemical Environment For Etching Of Such Materials

    Dobrzański L.A.


    Full Text Available The aim of the investigations described in this article is to present a selective laser sintering and melting technology to fabricate metallic scaffolds made of pristine titanium and titanium Ti6Al4V alloy powders. Titanium scaffolds with different properties and structure were manufactured with this technique using appropriate conditions, notably laser power and laser beam size. The purpose of such elements is to replace the missing pieces of bones, mainly cranial and facial bones in the implantation treatment process. All the samples for the investigations were designed in CAD/CAM (3D MARCARM ENGINEERING AutoFab (Software for Manufacturing Applications software suitably integrated with an SLS/SLM system. Cube-shaped test samples dimensioned 10×10×10 mm were designed for the investigations using a hexagon-shaped base cell. The so designed 3D models were transferred to the machine software and the actual rapid manufacturing process was commenced. The samples produced according to the laser sintering technology were subjected to chemical processing consisting of etching the scaffolds’ surface in different chemical mediums. Etching was carried out to remove the loosely bound powder from the surface of scaffolds, which might detach from their surface during implantation treatment and travel elsewhere in an organism. The scaffolds created were subjected to micro- and spectroscopic examinations

  2. Microwave Glass Melting Technology

    Hájek, Milan

    Tokyo, 2001, s. 11-14. [Conference on Application of Microwave Energy in Industry. Tokyo (JP), 30.07.2001-03.08.2001] R&D Projects: GA AV ČR IBS4072003 Institutional research plan: CEZ:AV0Z4072921 Keywords : microwave * glass melting technology * application Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  3. Melting and Sintering of Ashes

    Hansen, Lone Aslaug


    of melt in the investigated ashes has been determined as a function of temperature. Ash fusion results have been correlated to the chemical and mineralogical composition of the ashes, to results from a standard ash fusion test and to results from sintering experiments. Furthermore, the ash fusion results...... straw combustion are characterised by a large fraction of KCl and a smaller fraction of K-, Ca-, Al-silicates and quartz. The salt part of these ashes melt in the temperature range from 600-750°C, whereas the silicate part predominantly melts between 1000 and 1200°C. Increasing salt (KCl) content...... in the ashes lead to increased melt fractions in the temperature range 600-750°C.b) Bottom ashes from straw combustion consist purely of silicates, with varying ratios of the quite refractory Al-silicates and quartz to the less refractory K- and Ca-silicates. Bottom ashes melt in the temperature range 800...

  4. Study on the Physical and Chemical Conditions of Ore Formation of Hetai Ductile Shear Zone—Hosted Gold Deposit and Discovery of Melt Inclusions

    李兆麟; 翟伟; 等


    The Hetai ductile shear zone-hosted gold deposit occurs in the deep-seated falut mylonite zone of the Sinian-Silurian metamorphic rock series.In this study there have been discovered melt inclusions,fluid-melt inclusions and organic inclusions in ore-bearing ruartz veins of the ore deposit and mylonite for the first time.The homogenization temperatures of the various types of inclusions are 160℃,180-350℃,530℃and 870℃ for organic inclusions,liquid inclsions two-phase immiscible liquid inclusions and melt inclusion,respectively,Ore fluid is categoriezed as the neutral to basic K+-Ca2+-Mg2+-Na+-SO42--HCO3-Cl- system.The contents of trace gases follow a descending order of H2O>CO2>CH4>(orCO>C2H2>C2H6>O2>N2.The concentrations of K+,Ca2+,SO42-,HCO3-,Cl-,H2O and C2H2 in fluid inclusions are related to the contents of gold and the Au/Ag ratios in from different levels of the gold deposit.This is significant for deep ore prospecting in the region.Daughter minerals in melt inclusions were analyzed using SEM.Quartz,orthoclase,wollastonite and other silicate minerals were identified.They were formed in different mineral assemblages.This analysis further proves the existence of melt inclusions in ore veins.Sedimentary metamophic rocks could form silicate melts during metamorphic anatexis and dynamic metamorphism,which possess melt-soulution characteristics.Ore formation is related to the multi-stage forming process of silicate melt and fluid.

  5. Study on the Physical and Chemical Conditions of Ore Formation of Hetai Ductile Shear Zone-Hosted Gold Deposit and Discovery of Melt Inclusions

    李兆麟; 翟伟; 李文; 石贵勇; 文拥军


    The Hetai ductile shear zone-hosted gold deposit occurs in the deep-seated fault mylonite zone of the Sinian-Silurian metamorphic rock series. In this study there have been discovered melt inclusions, fluid-melt inclusions and organic inclusions in ore-bearing quartz veins of the ore deposit and mylonite for the first time. The homogenization temperatures of the various types of inclusions are 160℃, 180 - 350℃, 530℃ and 870℃ for organic inclusions, liquid inclusions, two-phase immiscible liquid inclusions and melt inclusions, respectively. Ore fluid is categorized as the neutral to basic K+ -Ca2+ -Mg2+ -Na+ - SO2- 4-HCO3-Cl- system. The contents of trace gases follow a descending order of H2O>CO2>CH4>(or < ) H2>CO>C2H2>C2I-I6>O2>N2.The concentrations of K , Ca2 + ,SO2-4,HCO3-,Cl- H2O and C2H2 in fluid inclusions are related to the contents of gold and the Au/Ag ratios in ores from different levels of the gold deposit. This is significant for deep ore prospecting in the region. Daughter minerals in melt inclusions were analyzed using SEM. Quartz, orthoclase, wollastonite and other silicate minerals were identified. They were formed in different mineral assemblages.This analysis further proves the existence of melt inclusions in ore veins. Sedimentary metamorphic rocks could form silicate melts during metamorphic anatexis and dynamic metamorphism, which possess melt-solution characteristics. Ore formation is related to the multi-stage forming process of silicate melt and fluid.

  6. Simple models for disequilibrium fractional melting and batch melting with application to REE fractionation in abyssal peridotites

    Liang, Yan; Liu, Boda


    Disequilibrium melting arises when the kinetics of chemical exchange between a residual mineral and partial melt is sluggish compare to the rate of melting. To better understand the role of a finite crystal-melt exchange rate on trace element fractionation during mantle melting, we have developed a disequilibrium melting model for partial melting in an upwelling steady-state column. We use linear kinetics to approximate crystal-melt mass exchange rate and obtain simple analytical solutions for cases of perfect fractional melting and batch melting. A key parameter determining the extent of chemical disequilibrium during partial melting is an element specific dimensionless ratio (ε) defined as the melting rate relative to the solid-melt chemical exchange rate for the trace element of interest. In the case of diffusion in mineral limited chemical exchange, ε is inversely proportional to diffusivity of the element of interest. Disequilibrium melting is important for the trace element when ε is comparable to or greater than the bulk solid-melt partition coefficient for the trace element (k). The disequilibrium fractional melting model is reduced to the equilibrium perfect fractional melting model when ε is much smaller than k. Hence highly incompatible trace elements with smaller mobilities in minerals are more susceptible to disequilibrium melting than moderately incompatible and compatible trace elements. Effect of chemical disequilibrium is to hinder the extent of fractionation between residual solid and partial melt, making the residual solid less depleted and the accumulated melt more depleted in incompatible trace element abundances relative the case of equilibrium melting. Application of the disequilibrium fractional melting model to REE and Y abundances in clinopyroxene in abyssal peridotites from the Central Indian Ridge and the Vema Lithospheric Section, Mid-Atlantic Ridge revealed a positive correlation between the disequilibrium parameter ε and the

  7. Aluminium evaporation during ceramic crucible induction melting of titanium aluminides

    Gomes, Fernando Manuel Duarte; Barbosa, J; Ribeiro, Carlos Silva


    Melting TiAl based alloys in ceramic crucibles often leads to chemical contamination, alloy heterogeneity and non-metallic inclusions. The severity of such phenomena usually depends on the nature of crucible materials, the melting stock composition and the melting parameters, namely superheating time and temperature and melting pressure. Among the referred drawbacks, Al loss during melting is a critical aspect, as its concentration in TiAl based alloys has a very strong effect in their mechan...

  8. Hull melting

    Irradiated fuel cladding scraps produced in reprocessing plants constitute contaminated and irradiating nuclear waste. While the cement embedding method currently used to condition such wastes is simple and inexpensive, an alternative method for conditioning zircaloy and stainless steel cladding wastes has been developed in France by the Commissariat a l'Energie Atomique (CEA) at Marcoule since 1982. The volume reduction factor is maximized and the final product is chemically stable, with a small potential leaching exchange surface area, and contains no tritium. Under some circumstances the decontaminating effect may be sufficient to allow storage under less stringent conditions. A nonradioactive industrial prototype has been built and qualified. Since 1988, a lab-scale hot-cell unit has also demonstrated process feasibility with actual radioactive clads while providing essential process data on volatilization and decontamination factors. A full-scale radioactive industrial prototype has been built in the Pilot Reprocessing Facility at Marcoule and should begin operation in 1992

  9. Melting of Pb nanocrystals

    The size-dependent melting and surface melting of Pb nanocrystals is demonstrated by x-ray powder diffraction in ultrahigh vacuum. Whereas some prior studies have measured the size-dependent melting temperature via the diffraction intensity, it is shown here that crystallite reorientation makes the diffraction intensity an unreliable indicator of melting. Instead of the diffraction intensity, the diffraction peak shape reveals the size-dependent melting via changes in the crystallite size distribution. Measurements showed that the melting temperature varies inversely with the crystallite size and quantitatively favors the liquid-skin melting model over the homogeneous melting model. Surface melting is demonstrated via the reversible growth of a 0.5 nm liquid skin on 50 nm crystallites just below the size-dependent melting temperature. copyright 1998 The American Physical Society

  10. Importance of the Small-Scale Processes Melting, Plate Boundary Formation and Mineralogy on the Large-Scale, Long-Term Thermo-Chemical Evolution of Earth's Mantle-Plate System

    Tackley, P.


    Seismic observations of the deep Earth reveal the presence of two large low shear velocity provinces (LLSVPs) that are typically inferred to be dense chemically-distinct material, as well as discontinuities that are typically linked to the post-perovskite (pPv) phase transition. Several possible origins of chemically-dense material have been proposed, including recycling of mid-ocean ridge basalt (MORB), primordial differentiation events, crystallisation of a basal magma ocean, or some combination of these creating a basal melange (BAM; Tackley 2012 Earth Sci. Rev.). Each of these possibilities would result in a different composition hence different mineralogy. In order to constrain this we have been running calculations of thermo-chemical mantle evolution over 4.5 billion years that include melting-induced differentiation, plate tectonics induced by strongly temperature-dependent viscosity and plastic yielding, core cooling and compressibility with reasonable assumptions about the pressure-dependence of other material properties. Some of our simulations start from a magma ocean state so initial layering is developed self-consistently. Already-published results (Nakagawa et al., 2009 GCubed, 2010 PEPI, 2012 GCubed) already indicate the importance of exact MORB composition on the amount of MORB segregating above the CMB, which in turn influences mantle thermal structure and the evolution of the core and geodynamo. In more recent results we have been additionally including primordial material. We find that melting-induced differentiation has several first-order effects on the dynamics, including (i) making plate tectonics easier (through stresses associated with lateral variations in crustal thickness) and (ii) reducing heat flux through the CMB (due to the build-up of dense material above the CMB); also (iii) tectonic mode (continuous plate tectonics, episodic lid or stagnant lid) also makes a first-order difference to mantle structure and dynamics. This emphasises

  11. Experimental study on thermal chemical separation of cesium by melting from municipal solid waste incineration ash, sewage sludge incineration ash and soil

    Due to the occurrence of the Great East Japan Earthquake, large amount of radioactive cesium (Cs) diffused around the Fukushima area, and the treatment of solids to which Cs was transferred has become a pressing issue. Melting technology can volatilize alkali metals and heavy metals with the addition of chlorides or combustibles by reduction or chlorination reaction and separate those metals into molten fly ash. Because Cs is also a kind of alkali metal element, it is thought to be capable of separation by a similar mechanism. So, in this study, for the purpose of investigating the volatilization characteristics of Cs, laboratory melting test was performed for municipal waste incineration ash, sewage sludge incineration ash and soil doped with non-radioactive Cs. When CaCl2 was added as a chloride, volatilization of alkali metals and heavy metals was promoted for all kinds of solids, so CaCl2 was found to have Cs volatilization promoting effect. Alkali metal element which had larger atomic number got higher volatilization rate. The higher the basicity of molten slag was, the higher volatilization rate was. When activated carbon was added as a combustible, volatilization of heavy metals was promoted, but that of alkali metals was not promoted. However, by the co-addition with CaCl2, activated carbon expressed volatilization promoting effect also for the alkali metals, and Cs volatilization rate of more than 99% was obtained. Further, when PVC waste was added as a volatilization promoter, because it contained both chlorides and combustibles, volatilization of alkali metals and heavy metals was promoted to the same extent as in the case of CaCl2 addition, so PVC waste was found to have sufficient Cs volatilization promoting effect. (author)


    Medical Service


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  13. Melting of Transition Metals

    Ross, M; Japel, S; Boehler, R


    We review the transition melting studies carried out at Mainz, and describe a recently developed model used to explain that the relatively low melting slopes are due to the partially filled d-bands, and the persistence of the pressure induced s-d transition. The basic tenets of the model have now been reconfirmed by new measurements for Cu and Ni. The measurements show that Cu which has a filled 3d-band, has a melt slope that is about 2.5 greater than its neighbor Ni. In the case of Mo, the apparent discrepancy of DAC melting measurements with shock melting can be explained by accounting for the change in melt slope due to the bcc-cp transition observed in the shock studies. The Fe melt curve is revisited. The possible relevance of the Jahn-Teller effect and recently observed transition metal melts with Icosahedral Short-Range Order (ISRO) is discussed.

  14. Effect of melting conditions on striae in iron-bearing silicate melts

    Jensen, Martin; Yue, Yuanzheng


    melt temperature and/or a decrease of viscosity play a more important role in decreasing the stria content. We also demonstrate that the extent of striation is influenced by the crucible materials that causes a change of redox state of the melt, and hence its viscosity. We discuss the effect of other...... factors such as compositional fluctuation of melts and bubbling due to iron reduction on the stria content. During the melting process, striae with a chemical gradient in a more mobile species equilibrate faster than striae caused by a chemical gradient in a less mobile species. The temperature and time...... effects on melt homogeneity at lower temperatures are larger than at higher temperatures....

  15. Microwave melting device

    Low level radioactive wastes (concrete pieces) or materials to be melted such as burnt ashes of wastes are charged into a melting furnace. Then, gyrotron of a microwave generator is oscillated, and generated microwaves of a large power are introduced to a melting furnace by a waveguide. The microwaves are irradiated from an irradiator to a beam converging-type reflecting mirror antenna disposed opposite to the irradiator. Then, an antenna driving portion is operated to rotate and move the antenna in parallel. With such procedures, the microwaves of a large power are converged acutely in a beam-like manner to a predetermined range in the melting furnace, and the converged beams of the microwaves are scanned. This can generate heat from the inner side of the materials to be melted charged to the melting furnace by the induction loss and they are melted. (I.N.)

  16. Rapidly solidified titanium alloys by melt overflow

    Gaspar, Thomas A.; Bruce, Thomas J., Jr.; Hackman, Lloyd E.; Brasmer, Susan E.; Dantzig, Jonathan A.; Baeslack, William A., III


    A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling.

  17. Physics of the Lindemann melting rule

    Lawson, Andrew C [Los Alamos National Laboratory


    We investigate the thermodynamics of melting for 74 distinct chemical elements including several actinides and rare earths. We find that the observed melting points are consistent with a linear relationship between the correlation entropy of the liquid and the Grueneisen constant of the solid, and that the Lindemann rule is well obeyed for the elements with simple structures and less well obeyed for the less symmetric more open structures. No special assumptions are required to explain the melting points of the rare earths or light actinides.

  18. Report on the relevance and feasibility of measurements of the heat of chemical reactions during core meltdown and of the integral heat content of core melts. Pt. 1

    Under the reactor safety programme of the German Federal Ministry of Research and Technology, Battelle-Frankfurt is conducting investigations into the heat produced by chemical reactions which may occur in the course of a hypothetical core meltdown accident. The first research phase consisted of a study into the significance of this heat compared with the nuclear decay heat. At present, some of the boundary conditions determining the course of the chemical reactions are not sufficiently well known. Therefore, some of the calculations had to be based upon assumptions which were chosen under conservative aspects. The results of the present study should thus be regarded as limiting values intended to stimulate more detailed investigations. Of the reactions that may occur between the main core components (zircaloy, steel and uranium dioxide), steam and atmospheric oxygen in the containment, the oxidation reactions were considered more closely. Reactions involving the hydrogen evolved in the reactions, the pressure vessel material or the concrete were left out of consideration. Based on the available literature, the maximum possible reaction heat, under the assumption of the complete oxidation of zircaloy and steel, and the rate of the highly exothermal reaction between zirconium and steam, were calculated. It was found that the latter reaction alone may be substantial compared with the nuclear decay reaction, both in terms of the amount of heat produced per unit time and of total heat produced. The oxidation of the steel, which is an exothermal reaction as well, is to be added to the oxidation of the zirconium. If the atmospheric oxygen in the containment should participate in the oxidation of steel during the late phases of the accident, additional peaks in the heat production must be expected. (orig.) 891 HP

  19. Melt containment member

    Rieken, Joel R.; Heidloff, Andrew J.


    A tubular melt containment member for transient containment of molten metals and alloys, especially reactive metals and alloys, includes a melt-contacting layer or region that comprises an oxygen-deficient rare earth oxide material that is less reactive as compared to the counterpart stoichiometric rare earth oxide. The oxygen-deficient (sub-stoichiometric) rare earth oxide can comprise oxygen-deficient yttria represented by Y.sub.2O.sub.3-x wherein x is from 0.01 to 0.1. Use of the oxygen-deficient rare earth oxide as the melt-contacting layer or region material reduces reaction with the melt for a given melt temperature and melt contact time.

  20. Model of interfacial melting

    Mouritsen, Ole G.; Zuckermann, Martin J.


    A two-dimensional model is proposed to describe systems with phase transitions which take place in terms of crystalline as well as internal degrees of freedom. Computer simulation of the model shows that the interplay between the two sets of degrees of freedom permits observation of grain-boundar......-boundary formation and interfacial melting, a nonequilibrium process by which the system melts at the boundaries of a polycrystalline domain structure. Lipid membranes are candidates for systems with pronounced interfacial melting behavior....

  1. User's manual for SIN: a one-dimensional hydrodynamic code for problems that include chemical reactions, elastic--plastic flow, spalling, phase transitions, melting, Forest Fire, detonation build-up, and Sesame tabular equation of state

    A CDC 7600 or CRAY computer FORTRAN code for computing one-dimensional hydrodynamic problems in slab, cylindrical, or spherical geometry with realistic equations of state is described. Features available in the code include chemical reactions using an Arrhenius rate law, the C-J volume burn, or, for slabs, a gamma-law Taylor wave; sharp-shock burn, Forest Fire; elastic--plastic flow using the Hooke's law--Von Mises yield model and Kennedy melt law; and spalling using the Whiteman and Skidmore model of the tensile stress at spalling as a linear function of the square root of the stress rate. The HOM equation of state is used to compute the equation of state for detonation products, undecomposed explosives, mixtures of the two, and condensed components which may have an instantaneous phase change. The Sesame tabular equation of state, Barnes equation of state, explosive build-up equation of state, and a solid-foam equation of state are included. Sample input and output are given for several typical types of problems. 2 tables

  2. Purification of iridium by electron beam melting

    The purification of iridium metal by electron beam melting has been characterized for 48 impurity elements. Chemical analysis was performed by glow discharge mass spectrographic (GDMS) analysis for all elements except carbon, which was analyzed by combustion. The average levels of individual elemental impurities in the starting powder varied from 37 μg/g to 0.02 μg/g. The impurity elements Li, Na, Mg, P, S, Cl, K, Ca, Mn, Co, Ni, Cu, Zn, As, Pd, Ag, Cd, Sn, Sb, Te, Ba, Ce, Tl, Pb, and Bi were not detectable following the purification. No significant change in the concentration of the elements Ti, V, Zr, Nb, Mo, and Re was found following melting. The elements B, C, Al, Si, Cr, Fe, Ru, Rh, and Pt were partially removed by vaporization during electron beam melting. Langmuir's equation for ideal vaporization into a vacuum was used to calculate for each impurity element the expected ratio of impurity content after melting to that before melting. Equilibrium vapor pressures were calculated using Henry's law, with activity coefficients obtained from published data for the elements Fe, Ti, and Pt. Activity coefficients were estimated from enthalpy data for Al, Si, V, Cr, Mn, Co, Ni, Zr, Nb, Mo, and Hf and an ideal solution model was used for the remaining elements. The melt temperature was estimated from measured iridium weight loss and impurity measurements. Good agreement, either quantitative or qualitative, was found between measured and calculated impurity ratios for all impurity elements. The results are consistent with some localized heating of the melt pool due to rastering of the electron beam, with an average vaporization temperature of 3100 K as compared to a temperature of 2965 K calculated for uniform heating of the melt pool. The results are also consistent with ideal mixing in the melt pool

  3. Simplicity in melt densification in multicomponent magmatic reservoirs in Earth’s interior revealed by multinuclear magnetic resonance

    Lee, Sung Keun


    Pressure-induced changes in properties of multicomponent silicate melts in magma oceans controlled chemical differentiation of the silicate earth and the composition of partial melts that might have formed hidden reservoirs. Although melt properties show complex pressure dependences, the melt structures at high pressure and the atomistic origins of these changes are largely unknown because of their complex pressure–composition dependence, intrinsic to multicomponent magmatic melts. Chemical c...

  4. Signatures of nonthermal melting

    Tobias Zier


    Full Text Available Intense ultrashort laser pulses can melt crystals in less than a picosecond but, in spite of over thirty years of active research, for many materials it is not known to what extent thermal and nonthermal microscopic processes cause this ultrafast phenomenon. Here, we perform ab-initio molecular-dynamics simulations of silicon on a laser-excited potential-energy surface, exclusively revealing nonthermal signatures of laser-induced melting. From our simulated atomic trajectories, we compute the decay of five structure factors and the time-dependent structure function. We demonstrate how these quantities provide criteria to distinguish predominantly nonthermal from thermal melting.

  5. Depth and Differentiation of the Orientale Melt Lake

    Vaughan, W. M.; Head, J. W.; Hess, P. C.; Wilson, L.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.


    Impact melt emplacement and evolution in lunar multi-ring basins is poorly understood since impact melt deposits in basins are generally buried by mare basalt fill and obscured by subsequent impact cratering. The relatively young Orientale basin, which is only partially flooded with mare basalt, opens a rare window into basin-scale impact melts. We describe the geology of impact melt-related facies in Orientale and suggest that the central depression of Orientale may represent a solidified impact melt lake that vertically subsided shortly after basin formation due to solidification and cooling. We use Lunar Orbiter Laser Altimeter (LOLA) data to measure the depth (approx. 1.75 km) and diameter (approx 350 km) of this central depression. If all the observed subsidence of the central depression is due to solidification and cooling, the melt lake should be approx 12.5-16 km deep, far more voluminous (approx 106 km3) than the largest known differentiated igneous intrusions on Earth. We investigate the possibility that the Orientale melt lake has differentiated and model 1) the bulk composition of the melt lake, 2) the operation of melt mixing in the melt lake, and 3) the chemical evolution of the resulting liquids on the An-Fo-Qz ternary in order to predict the lithologies that might be present in the solidified Orientale melt lake. Finally, we consider the possible significance of these lithologies.

  6. Monitoring of polymer melt processing

    The paper reviews the state-of-the-art of in-line and on-line monitoring during polymer melt processing by compounding, extrusion and injection moulding. Different spectroscopic and scattering techniques as well as conductivity and viscosity measurements are reviewed and compared concerning their potential for different process applications. In addition to information on chemical composition and state of the process, the in situ detection of morphology, which is of specific interest for multiphase polymer systems such as polymer composites and polymer blends, is described in detail. For these systems, the product properties strongly depend on the phase or filler morphology created during processing. Examples for optical (UV/vis, NIR) and ultrasonic attenuation spectra recorded during extrusion are given, which were found to be sensitive to the chemical composition as well as to size and degree of dispersion of micro or nanofillers in the polymer matrix. By small-angle light scattering experiments, process-induced structures were detected in blends of incompatible polymers during compounding. Using conductivity measurements during extrusion, the influence of processing conditions on the electrical conductivity of polymer melts with conductive fillers (carbon black or carbon nanotubes) was monitored. (topical review)

  7. Model of interfacial melting

    Mouritsen, Ole G.; Zuckermann, Martin J.


    A two-dimensional model is proposed to describe systems with phase transitions which take place in terms of crystalline as well as internal degrees of freedom. Computer simulation of the model shows that the interplay between the two sets of degrees of freedom permits observation of grain-boundary formation and interfacial melting, a nonequilibrium process by which the system melts at the boundaries of a polycrystalline domain structure. Lipid membranes are candidates for systems with pronoun...

  8. Melt fracture revisited

    Greenberg, J. M.


    In a previous paper the author and Demay advanced a model to explain the melt fracture instability observed when molten linear polymer melts are extruded in a capillary rheometer operating under the controlled condition that the inlet flow rate was held constant. The model postulated that the melts were a slightly compressible viscous fluid and allowed for slipping of the melt at the wall. The novel feature of that model was the use of an empirical switch law which governed the amount of wall slip. The model successfully accounted for the oscillatory behavior of the exit flow rate, typically referred to as the melt fracture instability, but did not simultaneously yield the fine scale spatial oscillations in the melt typically referred to as shark skin. In this note a new model is advanced which simultaneously explains the melt fracture instability and shark skin phenomena. The model postulates that the polymer is a slightly compressible linearly viscous fluid but assumes no slip boundary conditions at the capillary wall. In simple shear the shear stress {tau}and strain rate d are assumed to be related by d = F{tau} where F ranges between F{sub 2} and F{sub 1} > F{sub 2}. A strain rate dependent yield function is introduced and this function governs whether F evolves towards F{sub 2} or F{sub 1}. This model accounts for the empirical observation that at high shears polymers align and slide more easily than at low shears and explains both the melt fracture and shark skin phenomena.

  9. Melting of MORB at core-mantle boundary

    Pradhan, Gopal K.; Fiquet, Guillaume; Siebert, Julien; Auzende, Anne-Line; Morard, Guillaume; Antonangeli, Daniele; Garbarino, Gaston


    We investigated the melting properties of natural mid-ocean ridge basalt (MORB) up to core-mantle boundary (CMB) pressures using laser-heated diamond anvil cell. Textural and chemical characterizations of quenched samples were performed by analytical transmission electron microscopy. We used in situ X-ray diffraction primarily for phase identification whereas our melting criterion based on laser power versus temperature plateau combined with textural analysis of recovered solidus and subsolidus samples is accurate and unambiguous. At CMB pressure (135 GPa), the MORB solidus temperature is 3970 (± 150) K. Quenched melt textures observed in recovered samples indicate that CaSiO3 perovskite (CaPv) is the liquidus phase in the entire pressure range up to CMB. The partial melt composition derived from the central melt pool is enriched in FeO, which suggests that such melt pockets may be gravitationally stable at the core mantle boundary.

  10. Study on treatment of miscellaneous solid waste by plasma melting. Melting characteristics of plasma heating method

    The melting treatment is of great promise as treatment technology of volume reduction and stabilization for low-level radioactive miscellaneous solid wastes generated from nuclear facilities. Japan Atomic Energy Research Institute (JAERI) has been developing plasma melting method and carrying out melting tests of simulated miscellaneous solid wastes by this method. This paper describes heating characteristic, distribution behavior of radioactive tracer and volatilization behavior of slag component n the plasma melting. Thermal property of waste material had a great influence on heating efficiency of plasma heating. Uniformity of molten products was confirmed by radioactivity measurements. Residual fraction of Cs-137 in solidified product decreased with increasing of heating times. On the contrary, almost all of Eu-152 remained in solidified product. Volatilization of chemical components from molten slag was observed. (author)

  11. Melt Rate Improvement for DWPF MB3: Foaming Theory and Mitigation Techniques

    The objective of this research is to enhance the basic understanding of the role of glass chemistry, including the chemical kinetics of pre-melting, solid state reactions, batch melting, and the reaction pathways in glass and/or acid addition strategy changes on the overall melting process for the Defense Waste Processing Facility (DWPF) Macrobatch 3 (MB3)

  12. Kinetics of anorthite dissolution in basaltic melt

    Yu, Yi; Zhang, Youxue; Chen, Yang; Xu, Zhengjiu


    We report convection-free anorthite dissolution experiments in a basaltic melt at 1280-1500 °C and 0.5 GPa on two different crystallographic surfaces, (1 2 1 bar) and (3 bar 0 2) to investigate dissolution kinetics. The anisotropy of the anorthite dissolution rate along these two surfaces is negligible. Time series experiments at ∼1280 °C show that anorthite dissolution is mainly controlled by diffusion in the melt within experimental uncertainty. Analytical solutions were used to model the dissolution and diffusion processes, and to obtain the diffusivities and the saturation concentrations of the equilibrium-determining component (Al2O3) for anorthite dissolution into the basaltic melt. For the first time, we are able to show the physical and chemical characteristics of quench growth effect on the near-interface melt using high spatial resolution (0.3 μm) EDS analyses. For anorthite (An# ⩾ 90) saturation in a melt with 39-53 wt% SiO2 and ⩽0.4 wt% H2O, the concentration of Al2O3 in wt% depends on temperature as follows:

  13. Axial vibration control of melt structure of sodium nitrate in crystal growth process

    Sadovskiy, Andrey; Sukhanova, Ekaterina; Belov, Stanislav; Kostikov, Vladimir; Zykova, Marina; Artyushenko, Maxim; Zharikov, Evgeny; Avetissov, Igor


    The melt structure evolution under the action of the low-frequency axial vibration control (AVC) technique was studied in situ by Raman spectroscopy for several complex chemical compound melts: sodium nitrate, margarine acid, paraffin mixture (C17-C20). The measurements were conducted in the temperature range from the melting point up to 60 °C above. Comparison of crystallization heats for AVC activated and steady melts with melting heats of AVC-CZ and conventional CZ produced powders allowed to propose the energy diagram of NaNO3 states for activated and non-activated melts and crystals based on DTA, XRD, DSC and Raman experimental data.

  14. Emerging melt quality control solution technologies for aluminium melt

    Arturo Pascual, Jr


    The newly developed "MTS 1500" Melt Treatment System is performing the specifically required melt treatment operations like degassing, cleaning, modification and/or grain refinement by an automated process in one step and at the same location. This linked process is saving time, energy and metal losses allowing-by automated dosage of the melt treatment agents-the production of a consistent melt quality batch after batch. By linking the MTS Metal Treatment System with sensors operating on-line in the melt, i.e., with a hydrogen sensor "Alspek H", a fully automated control of parts of the process chain like degassing is possible. This technology does guarantee a pre-specified and documented melt quality in each melt treatment batch. Furthermore, to ensure that castings are consistent and predictable there is a growing realization that critical measuring the cleanliness of an aluminum melt but these can be both slow and costly. A simple, rapid and meaningful method of measuring and bench marking the cleanliness of an aluminum melt has been developed to offer the foundry a practical method of measuring melt cleanliness.This paper shows the structure and performance of the integrated MTS melt treatment process and documents achieved melt quality standards after degassing, cleaning, modification and grain refinement operations under real foundry conditions. It also provides an insight on a melt cleanliness measuring device "Alspek MQ" to provide foundry men better tools in meeting the increasing quality and tighter specification demand from the industry.


    Němec L.


    Full Text Available Four aspects of effective glass melting have been defined – namely the fast kinetics of partial melting phenomena, a consideration of the melting phenomena ordering, high utilisation of the melting space, and effective utilisation of the supplied energy. The relations were defined for the specific melting performance and specific energy consumption of the glass melting process which involve the four mentioned aspects of the process and indicate the potentials of effective melting. The quantity “space utilisation” has been treated in more detail as an aspect not considered in practice till this time. The space utilisation was quantitatively defined and its values have been determined for the industrial melting facility by mathematical modelling. The definitions of the specific melting performance and specific energy consumption have been used for assessment of the potential impact of a controlled melt flow and high space utilisation on the melting process efficiency on the industrial scale. The results have shown that even the partial control of the melt flow, leading to the partial increase of the space utilisation, may considerably increase the melting performance, whereas a decrease of the specific energy consumption was determined to be between 10 - 15 %.

  16. Melting of graphene clusters

    Singh, Sandeep Kumar; Neek-Amal, M.; Peeters, F. M.


    Density-functional tight-binding and classical molecular dynamics simulations are used to investigate the structural deformations and melting of planar carbon nano-clusters $C_{N}$ with N=2-55. The minimum energy configurations for different clusters are used as starting configuration for the study of the temperature effects on the bond breaking/rotation in carbon lines (N$

  17. Viscosity Measurement for Tellurium Melt

    Lin, Bochuan; Li, Chao; Ban, Heng; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.


    The viscosity of high temperature Te melt was measured using a new technique in which a rotating magnetic field was applied to the melt sealed in a suspended ampoule, and the torque exerted by rotating melt flow on the ampoule wall was measured. Governing equations for the coupled melt flow and ampoule torsional oscillation were solved, and the viscosity was extracted from the experimental data by numerical fitting. The computational result showed good agreement with experimental data. The melt velocity transient initiated by the rotating magnetic field reached a stable condition quickly, allowing the viscosity and electrical conductivity of the melt to be determined in a short period.

  18. Water-fluxed melting of the continental crust: A review

    Weinberg, Roberto F.; Hasalová, Pavlína


    Water-fluxed melting, also known as fluid- or water-present melting, is a fundamental process in the differentiation of continents but its importance has been underestimated in the past 20 years during which research efforts focused mostly on dehydration melting reactions involving hydrate phases, in the absence of a separate aqueous phase. The presence of a free aqueous phase in anatectic terranes influences all major physical and chemical aspects of the melting process, from melt volumes, viscosity and ability to segregate from rock pores, to melt chemical and isotopic composition. A review of the literature shows that melting due to the fluxing of aqueous fluids is a widespread process that can take place in diverse tectonic environments. Active tectono-magmatic processes create conditions for the release of aqueous fluids and deformation-driven, transient high permeability channels, capable of fluxing high-temperature regions of the crust where they trigger voluminous melting. Water-fluxed melting can be either congruent in regions at the water-saturated solidus, or incongruent at suprasolidus, P-T conditions. Incongruent melting reactions can give rise to peritectic hornblende, or to nominally anhydrous minerals such as garnet, sillimanite or orthopyroxene. In this case, the presence of an aqueous phase is indicated by a mismatch between the large melt fraction generated and the much smaller fractions predicted in its absence. The relatively small volumes of aqueous fluids compared to that of rocks imply that melting reactions are generally rock buffered. Fluids tend to move upwards and down temperature. However, there are cases in which pressure gradients drive fluids up temperature, potentially fluxing suprasolidus terranes. Crustal regions at conditions equivalent to the water-saturated solidus represent a natural impediment to the up-temperature migration of aqueous fluids because they are consumed in melting reactions. In this case, continued migration

  19. Melting of polydisperse hard disks

    Pronk, S.; Frenkel, D.


    The melting of a polydisperse hard-disk system is investigated by Monte Carlo simulations in the semigrand canonical ensemble. This is done in the context of possible continuous melting by a dislocation-unbinding mechanism, as an extension of the two-dimensional hard-disk melting problem. We find th

  20. Thermodynamics of Oligonucleotide Duplex Melting

    Schreiber-Gosche, Sherrie; Edwards, Robert A.


    Melting temperatures of oligonucleotides are useful for a number of molecular biology applications, such as the polymerase chain reaction (PCR). Although melting temperatures are often calculated with simplistic empirical equations, application of thermodynamics provides more accurate melting temperatures and an opportunity for students to apply…

  1. Continuous eclogite melting and variable refertilisation in upwelling heterogeneous mantle.

    Rosenthal, Anja; Yaxley, Gregory M; Green, David H; Hermann, Joerg; Kovács, István; Spandler, Carl


    Large-scale tectonic processes introduce a range of crustal lithologies into the Earth's mantle. These lithologies have been implicated as sources of compositional heterogeneity in mantle-derived magmas. The model being explored here assumes the presence of widely dispersed fragments of residual eclogite (derived from recycled oceanic crust), stretched and stirred by convection in the mantle. Here we show with an experimental study that these residual eclogites continuously melt during upwelling of such heterogeneous mantle and we characterize the melting reactions and compositional changes in the residue minerals. The chemical exchange between these partial melts and more refractory peridotite leads to a variably metasomatised mantle. Re-melting of these metasomatised peridotite lithologies at given pressures and temperatures results in diverse melt compositions, which may contribute to the observed heterogeneity of oceanic basalt suites. We also show that heterogeneous upwelling mantle is subject to diverse local freezing, hybridization and carbonate-carbon-silicate redox reactions along a mantle adiabat. PMID:25130275

  2. Induction melting of simulated transuranic waste

    Coreless induction melting was investigated as a method to melt and consolidate waste material representative of the transuranic waste (TRU) stored at the Idaho National Engineering Laboratory (INEL). Waste material was introduced onto the surface of a molten cast iron bath in a coreless induction furnace. Waste metallics were incorporated into the bath. Noncombustibles formed a slag which was poured or skimmed from the bath surface. Stack sampling was performed to characterize the off-gas and particulate matter evolved. Experimental melting tests were performed for a variety of types of wastes including metallics, chemical sludge, soil, concrete, and glass. Each test also included a representative level of combustible materials consisting of paper, wood, cloth, polyvinyl chloride and polyethylene. Metallic wastes were readily processed by induction melting with a minimum of slag production. Test waste consisting primarily of chemical sludge provided fluid slags which could be poured from the bath surface. Processing of wastes consisting of soil, concrete, or glass was limited by the inability to achieve fluid slags. It appears from test results that coreless induction melting is a feasible method to process INEL-type waste materials if two problems can be resolved. First, slag fluidity must be improved to facilitate the collection of slags formed from soil, concrete, or glass containing wastes. Secondly, refractory life must be further optimized to permit prolonged processing of the waste materials. The use of a chrome-bearing high-alumina refractory was found to resist slag line attach much better than a magnesia refractory, although some attack was still noted

  3. Melting of clusters

    Haberland, H. [Freiburg Univ., Facultat fur Physik (Germany)


    An experiment is described which allows to measure the caloric curve of size selected sodium cluster ions. This allows to determine rather easily the melting temperatures, and latent heats in the size range between 55 and 340 atoms per cluster. A more detailed analysis is necessary to show that the cluster Na{sub 147}{sup +} has a negative microcanonical heat capacity, and how to determine the entropy of the cluster from the data. (authors)

  4. Melt spinning study

    Workman, Gary L.; Rathz, Thomas


    Containerless processing of materials provides an excellent opportunity to study nucleation phenomena and produce unique materials, primarily through the formation of metastable phases and deep undercoolings. Deep undercoolings can be readily achieved in falling drops of molten material. Extended solute solubilities and greatly refined microstructures can also be obtained in containerless processing experiments. The Drop Tube Facility at Marshall Space Flight Center has played an important role in enhancing that area of research. Previous experiments performed in the Drop Tube with refractory metals has shown very interesting microstructural changes associated with deep undercoolings. It is apparent also that the microstructure of the deep undercooled species may be changing due to the release of the latent heat of fusion during recalescence. For scientific purposes, it is important to be able to differentiate between the microstructures of the two types of metallic species. A review of the literature shows that although significant advances have been made with respect to the engineering aspects of rapid solidification phenomena, there is still much to be learned in terms of understanding the basic phenomena. The two major ways in which rapid solidification processing provides improved structures and hence improved properties are: (1) production of refined structures such as fine dendrites and eutectics, and (2) production of new alloy compositions, microstructures, and phases through extended solid solubility, new phase reaction sequences, and the formation of metallic-glass microstructures. The objective of this work has been to determine the optimal methodology required to extract this excess energy without affecting the thermo-physical parameters of the under-cooled melt. In normal containerless processing experiments recalescence occurs as the melt returns toward the melting point in order to solidify. A new type of experiment is sought in which the resultant

  5. Examination of the physico-chemical properties of CORIUM-based oxidic melt systems at extremely high temperatures modelling non-standard states of VVER type nuclear reactors. Research report for 2007

    Initial activities of this project, performed in 2007, were aimed at preparing high-purity monocrystalline UO2 by controlled crystallization in a COMETA high frequency furnace. From the radiation protection aspect it is safer and thus more appropriate to investigate the best conditions for pure UO2 preparation by testing the procedures first by using iron oxides. In melting conditions, iron oxides exhibit affinity for atmospheric oxygen and valence state changes similar to uranium oxides. The x-ray diffraction results, from which different structural forms of iron oxides were determined, suggested that melting in normal atmosphere is unsuitable for controlled crystallization of iron oxides and hence, for uranium oxides as well. As an alternative, a procedure to prepare pure UO2 in nitrogen was developed. This called for modification of the COMETA system. (author)

  6. Global-scale modelling of melting and isotopic evolution of Earth's mantle: melting modules for TERRA

    van Heck, Hein J.; Davies, J. Huw; Elliott, Tim; Porcelli, Don


    Many outstanding problems in solid-Earth science relate to the geodynamical explanation of geochemical observations. Currently, extensive geochemical databases of surface observations exist, but satisfying explanations of underlying mantle processes are lacking. One way to address these problems is through numerical modelling of mantle convection while tracking chemical information throughout the convective mantle. We have implemented a new way to track both bulk compositions and concentrations of trace elements in a finite-element mantle convection code. Our approach is to track bulk compositions and trace element abundances via particles. One value on each particle represents bulk composition and can be interpreted as the basalt component. In our model, chemical fractionation of bulk composition and trace elements happens at self-consistent, evolving melting zones. Melting is defined via a composition-dependent solidus, such that the amount of melt generated depends on pressure, temperature and bulk composition of each particle. A novel aspect is that we do not move particles that undergo melting; instead we transfer the chemical information carried by the particle to other particles. Molten material is instantaneously transported to the surface layer, thereby increasing the basalt component carried by the particles close to the surface and decreasing the basalt component in the residue. The model is set to explore a number of radiogenic isotopic systems, but as an example here the trace elements we choose to follow are the Pb isotopes and their radioactive parents. For these calculations we will show (1) the evolution of the distribution of bulk compositions over time, showing the buildup of oceanic crust (via melting-induced chemical separation in bulk composition), i.e. a basalt-rich layer at the surface, and the transportation of these chemical heterogeneities through the deep mantle; (2) the amount of melt generated over time; (3) the evolution of the

  7. Primary carbonatite melt from deeply subducted oceanic crust

    Walter, M.J.; Bulanova, G.P.; Armstrong, L.S.; Keshav, S.; Blundy, J.D.; Gudfinnesson, G.; Lord, O.T.; Lennie, A.R.; Clark, S.M.; Smith, C.B.; Gobbo, L.


    Partial melting in the Earth's mantle plays an important part in generating the geochemical and isotopic diversity observed in volcanic rocks at the surface. Identifying the composition of these primary melts in the mantle is crucial for establishing links between mantle geochemical 'reservoirs' and fundamental geodynamic processes. Mineral inclusions in natural diamonds have provided a unique window into such deep mantle processes. Here they provide exper8imental and geochemical evidence that silicate mineral inclusions in diamonds from Juina, Brazil, crystallized from primary and evolved carbonatite melts in the mantle transition zone and deep upper mantle. The incompatible trace element abundances calculated for a melt coexisting with a calcium-titanium-silicate perovskite inclusion indicate deep melting of carbonated oceanic crust, probably at transition-zone depths. Further to perovskite, calcic-majorite garnet inclusions record crystallization in the deep upper mantle from an evolved melt that closely resembles estimates of primitive carbonatite on the basis of volcanic rocks. Small-degree melts of subducted crust can be viewed as agents of chemical mass-transfer in the upper mantle and transition zone, leaving a chemical imprint of ocean crust that can possibly endure for billions of years.

  8. Emerging melt quality control solution technologies for aluminium melt

    Arturo Pascual, Jr


    Full Text Available The newly developed “MTS 1500” Melt Treatment System is performing the specifi cally required melt treatment operations like degassing, cleaning, modification and/or grain refinement by an automated process in one step and at the same location. This linked process is saving time, energy and metal losses allowing - by automated dosage of the melt treatment agents - the production of a consistent melt quality batch after batch. By linking the MTS Metal Treatment System with sensors operating on-line in the melt, i.e., with a hydrogen sensor “Alspek H”, a fully automated control of parts of the process chain like degassing is possible. This technology does guarantee a pre-specifi ed and documented melt quality in each melt treatment batch. Furthermore, to ensure that castings are consistent and predictable there is a growing realization that critical parameters such as metal cleanliness must be measured prior to casting. There exists accepted methods for measuring the cleanliness of an aluminum melt but these can be both slow and costly. A simple, rapid and meaningful method of measuring and bench marking the cleanliness of an aluminum melt has been developed to offer the foundry a practical method of measuring melt cleanliness. This paper shows the structure and performance of the integrated MTS melt treatment process and documents achieved melt quality standards after degassing, cleaning, modifi cation and grain refi nement operations under real foundry conditions. It also provides an insight on a melt cleanliness measuring device “Alspek MQ” to provide foundry men better tools in meeting the increasing quality and tighter specifi cation demand from the industry.

  9. Tenoumer impact crater, Mauritania: Impact melt genesis from a lithologically diverse target

    Schultze, Dina Simona; Jourdan, Fred; Hecht, Lutz; Reimold, Wolf Uwe; Schmitt, Ralf-Thomas


    Impact melt rocks from the 1.9 km diameter, simple bowl-shaped Tenoumer impact crater in Mauritania have been analyzed chemically and petrologically. They are heterogeneous and can be subdivided into three types based on melt matrix color, occurrence of lithic clast components, amount of vesiculation (melt degassing), different proportions of carbonate melt mingled into silicate melt, and bulk rock chemical composition. These heterogeneities have two main causes (1) due to the small size of the impact crater, there was probably no coherent melt pool where a homogeneous mixture of melts, derived from different target lithologies, could be created; and (2) melt rock heterogeneity occurring at the thin section scale is due to fast cooling during and after the dynamic ejection and emplacement process. The overall period of crystal growth from these diverse melts was extremely short, which provides a further indication that complete chemical equilibration of the phases could not be achieved in such short time. Melt mixing processes involved in the generation of impact melts are, thus, recorded in nonequilibrium growth features. Variable mixing processes between chemically different melt phases and the formation of hybrid melts can be observed even at millimeter scales. Due to extreme cooling rates, different mixing and mingling stages are preserved in the varied parageneses of matrix minerals and in the mineral chemistry of microlites. 40Ar39Ar step-heating chronology on specimens from three melt rock samples yielded five concordant inverse isochron ages. The inverse isochron plots show that minute amounts of inherited 40Ar* are present in the system. We calculated a weighted mean age of 1.57 ± 0.14 Ma for these new results. This preferred age represents a refinement from the previous range of 21 ka to 2.5 Ma ages based on K/Ar and fission track dating.

  10. Holographic meson melting

    The plasma phase at high temperatures of a strongly coupled gauge theory can be holographically modelled by an AdS black hole. Matter in the fundamental representation and in the quenched approximation is introduced through embedding D7-branes in the AdS-Schwarzschild background. Low spin mesons correspond to the fluctuations of the D7-brane world volume. As is well known by now, there are two different kinds of embeddings, either reaching down to the black hole horizon or staying outside of it. In the latter case the fluctuations of the D7-brane world volume represent stable low spin mesons. In the plasma phase we do not expect mesons to be stable but to melt at sufficiently high temperature. We model the late stages of this meson melting by the quasinormal modes of D7-brane fluctuations for the embeddings that do reach down to the horizon. The inverse of the imaginary part of the quasinormal frequency gives the typical relaxation time back to equilibrium of the meson perturbation in the hot plasma. We briefly comment on the possible application of our model to quarkonium suppression

  11. Carbonatite melt in oceanic upper mantle beneath the Kerguelen Archipelago

    Moine, B. N.; Grégoire, M.; O'Reilly, Suzanne Y.; Delpech, G.; Sheppard, S. M. F.; Lorand, J. P.; Renac, C.; Giret, A.; Cottin, J. Y.


    Some mantle-derived Kerguelen harzburgite and dunite xenoliths have bulk-rock and mineral trace element compositions that provide evidence of carbonatitic metasomatism similar to that described in some continental and other oceanic settings. Rare xenoliths contain carbonates that are highly enriched in rare earth elements (REE), interpreted to be quenched, evolved carbonatitic melts. One amphibole-bearing dunite mantle wall-rock containing carbonates in small interstitial pockets (100-500 μm across) has been studied in detail. Mg-bearing calcite (MgO: magnesio-wüstite concentrated near the boundaries of the carbonate pockets. The unusual metasomatic mineral assemblage, together with the microstructural features and chemical composition of carbonates (with trace element contents similar to those of common carbonatite magmas), suggests that the pockets of Mg-bearing calcite represent quenched carbonate melts rather than crystal cumulates from carbonate-rich melts. The associated mafic silicate glass could represent the immiscible silicate fraction of an evolved fluid produced by the dissolution-percolation of the original carbonate melt in the dunitic matrix and subsequent unmixing as the xenoliths ascended to the surface. Clinopyroxene formed during the percolation event and is therefore inferred to be in chemical equilibrium with the carbonate melt. This allowed calculation of clinopyroxene/carbonate melt partition coefficients for a large set of trace elements at relatively low pressure (1 GPa). As a result, a significant pressure control on REE partitioning between carbonate melt and silicate minerals was observed. This study provides further evidence for the occurrence of carbonate melts and demonstrates that these melts can be preserved in hot oceanic uppermost mantle.

  12. Melting of Ice under Pressure

    Schwegler, E; Sharma, M; Gygi, F; Galli, G


    The melting of ice under pressure is investigated with a series of first principles molecular dynamics simulations. In particular, a two-phase approach is used to determine the melting temperature of the ice-VII phase in the range of 10 to 50 GPa. Our computed melting temperatures are consistent with existing diamond anvil cell experiments. We find that for pressures between 10 to 40 GPa, ice melts as a molecular solid. For pressures above {approx}45 GPa there is a sharp increase in the slope of the melting curve due to the presence of molecular dissociation and proton diffusion in the solid, prior to melting. The onset of significant proton diffusion in ice-VII as a function of increasing temperature is found to be gradual and bears many similarities to that of a type-II superionic solid.

  13. Melt Cleanliness Comparison of Chlorine Fluxing and Ar Degassing of Secondary Al-4Cu

    Çolak, Murat; Kayikci, Ramazan; Dispinar, Derya


    The treatment of liquid aluminum prior to casting typically consists of purging gas and/or fluxes through the melt. By the use of several chemicals during these operations, several environmental problems can occur. Therefore, in this study, the melt cleanliness of Al-4Cu secondary alloy was investigated by comparing the use of argon degassing with or without chlorine fluxing. Reduced pressure test was used to assess the melt quality. Highest quality melt was obtained by Ar degassing with preheated graphite lance without the need to use any chemicals.


    FU Shuren; CHEN Taoyung


    Multiple melting behavior of nylon 1010 has been investigated by using DSC instrument. Effects of partial scanning, partial scanning and annealing, heating rate, cooling rate and stepwise annealing on the melting curve were studied. Experimental results indicate that the sample undergoes a process of continuous melting and recrystallization during DSC scanning. Nylon 1010 contains a distribution of crystallites of different degrees of perfection which is strongly dependent on its previous thermal history. From the structural reorganization point of view, the origin of double and multiple peaks of the melting curve is explained.

  15. Melting behavior of yttrium orthovanadate

    When YVO4 melts at 18100C, it decomposes to form YVO3, a black semi-conducting compound. Between about 15000C and its melting point, YVO4 also reacts to form Y8V2O17 plus V2O5. The melt actually consists of a ternary system whose composition changes with time. Reoxidation of YVO3 to YVO4 can be accomplished below the melting point by annealing in oxygen. The difficulty in obtaining high-quality optical crystals of YVO4 by Czrochralski growth is thus explained. (U.S.)

  16. Viscosity of ring polymer melts

    Pasquino, Rossana


    We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime η0,linear/η 0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/ η0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 < Z < 20, η0,linear/η0,ring ∼ Z 1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring ∼ Z 1.6±0.3) and the simulations (η0,linear/ η0,ring ∼ Z2.0±0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem. © 2013 American Chemical Society.

  17. Melting method for miscellaneous radioactive solid waste and melting furnace

    A vessel containing miscellaneous solid wastes is inserted in a crucible having a releasable material on the inner surface, they are induction-heated from the outside of the crucible by way of low temperature heating coils to melt low melting point materials in the miscellaneous wastes within a temperature range at which the vessel does not melt. Then, they are induction-heated by way of high temperature heating coils to melt the vessel and not yet melted materials, those molten materials are cooled, solidified molten material and the releasable material are taken out, and then the crucible is used again. Then, the crucible can be used again, so that it can be applied to a large scaled melting furnace which treats wastes by a unit of drum. In addition, since the cleaning of the used crucible and the application of the releasable material can be conducted without interrupting the operation of the melting furnace, the operation cycle of the melting furnace can be shortened. (N.H.)

  18. Crystallization behavior during melt-processing of ceramic waste forms

    Tumurugoti, Priyatham; Sundaram, S. K.; Misture, Scott T.; Marra, James C.; Amoroso, Jake


    Multiphase ceramic waste forms based on natural mineral analogs are of great interest for their high chemical durability, radiation resistance, and thermodynamic stability. Melt-processed ceramic waste forms that leverage existing melter technologies will broaden the available disposal options for high-level nuclear waste. This work reports on the crystallization behavior in selected melt-processed ceramics for waste immobilization. The phase assemblage and evolution of hollandite, zirconolite, pyrochlore, and perovskite type structures during melt processing were studied using thermal analysis, x-ray diffraction, and electron microscopy. Samples prepared by melting followed by annealing and quenching were analyzed to determine and measure the progression of the phase assemblage. Samples were melted at 1500 °C and heat-treated at crystallization temperatures of 1285 °C and 1325 °C corresponding to exothermic events identified from differential scanning calorimetry measurements. Results indicate that the selected multiphase composition partially melts at 1500 °C with hollandite coexisting as crystalline phase. Perovskite and zirconolite phases crystallized from the residual melt at temperatures below 1350 °C. Depending on their respective thermal histories, different quenched samples were found to have different phase assemblages including phases such as perovskite, zirconolite and TiO2.

  19. Core-melt behavior in a LWR-containment

    Three further experiments in the BETA facility have been carried out to investigate special aspects of molten corium interacting with concrete. The invesigation of Zr oxidation during concrete attack has been completed. The measurements show the dominance of Zr oxidation by the chemical reduction of SiO2 to elemental Si and the subsequent Si oxidation by the gases from the concrete. Serpentine concrete as used in Russian power plants releases a large amount of vapour and hydrogen when attacked by the hot melt. This is due to the high portion of crystal water in the serpentine mineral. Additionally, the failure of a cylindrical concrete wall was studied, which is eroded on the inner side by a heated melt while being cooled outside by stagnant water. The WECHSL code was improved in the description of the early melt/concrete interaction, predominantly in the high temperature phase of concrete erosion with high Zirconium content of the melt. (orig.DG)

  20. Morphology, Crystallization and Melting Behavior of Propylene-Ethylene Statistical Copolymers

    Uan-Zo-li, Julie Tammy


    In this work the morphology, crystallization and melting behavior of novel Dow Chemical propylene-ethylene copolymers were investigated. The incorporation of ethylene units into a polypropylene chain resulted in the decrease in crystallization, melting and glass transition temperatures and overall crystallinity. Based on the shape of heat capacity curves and the dependence of the melting temperature offset on ethylene content, it was concluded that copolymers prepared using different ca...

  1. Sulfur behaviour on stainless steel melting by single-slag process

    A consideration is given to desulfurizing process during melting stainless steel type 08-12Kh18N10T according to a single-slag variant of melting technology. Wastes of abrasive metal machining and worn-out equipment from chemical plants are shown to be highly contaminated with sulfur and cannot be remelted by the above-mentioned process. A new variant of two-slag melting technology was successfully tested. 4 refs

  2. Two dimensional superfluidity and melting

    The author reviews the equilibrium theory of superfluidity and XY magnetism, due in large part to the seminal work of Kosterlitz and Thouless. A dynamic generalization of this theory, with application to third sound in helium films is discussed. The statistical mechanics of two-dimensional melting on both smooth and periodic substrates, is discussed. The dynamic version of the theory is sketched. A theory of melting dynamics is particularly important in interpreting of the experiments on melting and crystallization described earlier. Finally the theory as it applies to anisotropic media including layered materials like smectics, cholesterics, and Rayleigh-Benard convection cells, is discussed. (Auth.)

  3. Glass melting phenomena, their ordering and melting space utilisation

    Němec, Lubomír; Jebavá, Marcela; Dyrčíková, Petra


    Roč. 57, č. 4 (2013), s. 275-284. ISSN 0862-5468 R&D Projects: GA TA ČR TA01010844 Institutional support: RVO:67985891 Keywords : glass melting * space utilization * melt flow * phenomena ordering Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.434, year: 2013


    V. Yu. Stetsenko


    Full Text Available On the basis of thermodynamic analysis it is shown that metal melts are the nanostructured systems which consist of phases and atoms nanocrystals. Nanocrystalsmake 97% ofthemeltvolume.

  5. Structure and rheological properties in alkali aluminosilicate melts

    Le Losq, Charles; Neuville, Daniel


    Rheological properties of silicate melts govern both magma ascension from the mantle to the surface of the earth and volcanological eruptions styles and behaviors. In this mind, it is very important to understand which parameters influence these properties. Up to now, we know for example that viscosity of silicate melts is dependent of temperature, pressure and chemical composition. In this work, we will focus on the Na2O-K2O-Al2O3-SiO2 system, which is of a prime importance because it deals with a non-negligible part of natural melts like haplogranitic rhyolitic alkali magmas. We will first present our viscosity measurements and some modelisation concepts based on the Adam and Gibbs theory. From configurational entropy theory we obtain some macroscopic information's that we can link to the structure of glasses and melts. In this mind, we have investigated them with Raman and NMR spectroscopies. These spectroscopies provide information on speciation and polymerization of glasses and melts. We will present and discuss structural and rheological variations as a function of temperature and chemical change.

  6. Scaleable Clean Aluminum Melting Systems

    Han, Q.; Das, S.K. (Secat, Inc.)


    The project entitled 'Scaleable Clean Aluminum Melting Systems' was a Cooperative Research and Development Agreements (CRADAs) between Oak Ridge National Laboratory (ORNL) and Secat Inc. The three-year project was initially funded for the first year and was then canceled due to funding cuts at the DOE headquarters. The limited funds allowed the research team to visit industrial sites and investigate the status of using immersion heaters for aluminum melting applications. Primary concepts were proposed on the design of furnaces using immersion heaters for melting. The proposed project can continue if the funding agency resumes the funds to this research. The objective of this project was to develop and demonstrate integrated, retrofitable technologies for clean melting systems for aluminum in both the Metal Casting and integrated aluminum processing industries. The scope focused on immersion heating coupled with metal circulation systems that provide significant opportunity for energy savings as well as reduction of melt loss in the form of dross. The project aimed at the development and integration of technologies that would enable significant reduction in the energy consumption and environmental impacts of melting aluminum through substitution of immersion heating for the conventional radiant burner methods used in reverberatory furnaces. Specifically, the program would couple heater improvements with furnace modeling that would enable cost-effective retrofits to a range of existing furnace sizes, reducing the economic barrier to application.

  7. Electric arc furnace melting of simulated transuranic wastes

    As part of an interagency agreement between the Bureau of Mines, US Department of the Interior, and the US Department of Energy through its contractor, EG and G Idaho, Inc., the Bureau conducted six melting tests at its Albany Research Center to assess the feasibility of melting transuranic-containing wastes. The tests were conducted with simulated wastes in a conventional refractory-lined electric arc furnace. Charge materials included concrete, soil, metal, wood, CaO- and Na2O-containing chemical waste sludges, cement, and polyethylene mixed in various proportions in both unburned and partially incinerated forms. The investigation showed that it is possible to melt these materials in a 1-metric-ton conventional electric arc furnace and separate the slag and metal provided that suitable fluxes are added to condition the silicious slages. However, the electric arc furnace cannot be considered an efficient incinerator. The molten slags were poured into 210-liter steel drums having a 0.64-cm-thick steel chill plate on the bottom. All slags were tapped from the furnace satisfactorily. The concrete and sludge materials required the most energy for melting (2.2 to 2.6 kWhr/kg). The highest electrode consumption occurred when the sludges were melted (0.04 kg/kg product). A high alumina-chrome refractory is satisfactory for use as a furnace lining in melting these wastes. Offgases and particulates from all of the tests were sampled and analyzed. The greatest amounts of particulate matter in the offgas streams were obtained from melting sludges and incinerated wastes. It is recommended that if a conventional electric arc furnace is used to melt transuranic waste that it (1) be fed slowly to prevent excessive fumes and flames and (2) be operated continuously to minimize startup problems and improve efficiency

  8. Synthesis of fluorophosphate glasses with low melting temperatures

    Leissner, J; Sebastian, K; Roggendorf, Hans; Schmidt, Helmut K.


    Fluorophosphate glasses can combine low melting temperatures with a good chemical durability. In order to vary optical properties while retaining other features some new compositions were synthesized and some of their properties were investigated. The glasses were melted at 450°C by using SnO, PbF2, SnF2, NH4H2PO4 and NH4PF6 as raw materials. Metal fluorides like ZrF4 and ZnF2 were introduced, too. The Tg ranges between 87 and 141°C. Preliminary results concerning the transmission spectra in ...

  9. Melt eruptions during molten corium concrete interactions

    Robb, Kevin Richard

    The melt eruption phenomenon could occur during severe accidents at existing light water nuclear reactors. A postulated beyond-design basis accident includes the melting and relocation of the reactor core onto the concrete basemat of containment. The continually heated melt can reach high temperatures and thermally attack the underlying concrete, MCCI. As the melt cools, a crust forms on the upper surface of the melt pool. Melt eruptions occur when gases from the decomposing concrete passes through channels in the crust ejecting melt onto the upper surface of the crust. The impact of melt eruptions on the coolability of the melt is important when estimating the probability and timing of containment failure. This work focuses on understanding and modeling the melt eruption phenomenon. A model has been developed to predict the amount of melt ejected during melt eruptions. This entrainment model has been verified against an experimental database developed as part of this work. Several phenomena have been identified and modeled which may predict the creation and closure of eruptions sites. The models have been integrated into a MCCI systems code. The new melt eruption model predicted reasonable rates of melt ejection and the number and diameter of eruption sites for a sample simulation of a postulated reactor scale MCCI. Results from the new melt eruption model suggest an ex-vessel core melt under flooded conditions could readily quench.

  10. Chemistry and petrology of Apollo 17 highland coarse fines - Plutonic and melt rocks

    Laul, J. C.; Gosselin, D. C.; Galbreath, K. C.; Simon, S. B.; Papike, J. J.


    A suite of 21 fragments from the Apollo 17 coarse-fines consists of ferroan anorthosites, anorthositic gabbros, granulitic and regolith breccias, and impact melts. These samples belong to known petrographic and chemical groups. Three ferroan anorthosites were found, including one which appears to be the lowest in REE (La = 0.60X) and probably the purest of the Apollo 17 anorthosites identified thus far. The ferroan suite is a more important component at the Apollo 17 site than previously recognized. The Apollo 17 melt rocks are similar to other samples with LKFM and low-K KREEP compositions and show less diversity in trace elements (REE) than the Apollo 15 melt rocks. Apollo 17 melt rocks consist of aphanitic and poikilitic types that show some compositional variability with identical Ni/Ir, suggesting that either two distinct melt sheets formed by similar projectiles, or compositional heterogeneity within one melt sheet is possible.

  11. On mathematical modeling of convective melting of a granular porous medium

    Sabau, A.S.; Tao, Y.X.


    Packed beds of solid particles are widely used in various processes in chemical, metallurgical, pharmaceutical, and building industries. In most of these applications, such as in situ vitrification of hazardous waste, or preform infiltration for manufacturing fiber reinforced composites, phase change occur in porous materials and packed beds. Here, a mathematical model and its experimental validation are presented for the melting of a granular porous media saturated with a flowing liquid. Repacking of the granular packed bed is accounted for by considering the motion of the solid grains. An analytical solution for the melting rate is provided for the one-dimensional, quasi-steady state melting case. Convection effects upstream of the melting zone are considered. It is shown that the melting rate depends on the Stefan number based on the upstream liquid temperature, liquid to solid density ratio, fluid velocity and solid fraction downstream of the melting zone.

  12. Melting in temperature sensitive suspensions

    Alsayed, Ahmed M.

    We describe two experimental studies about melting in colloidal systems. In particular we studied melting of 1-dimensional lamellar phases and 3-dimensional colloidal crystals. In the first set of experiments we prepared suspensions composed of rodlike fd virus and the thermosensitive polymer, poly(N-isopropylacrylamide). The phase diagram of this systems is temperature and concentration dependent. Using video microscopy, we directly observed melting of lamellar phases and single lamellae into nematic phase. We found that lamellar phases swell with increasing temperature before melting into the nematic phase. The highly swollen lamellae can be superheated as a result of topological nucleation barriers that slow the formation of the nematic phase. In another set of experiments we prepared colloidal crystals from thermally responsive microgel spheres. The crystals are equilibrium close-packed three-dimensional structures. Upon increasing the temperature slightly above room temperature, particle volume fraction decreased from 0.74 to less than 0.5. Using video microscopy, we observed premelting at grain boundaries and dislocations within bulk colloidal crystals. Premelting is the localized loss of crystalline order at surfaces and defects at sample volume fractions above the bulk melting transition. Particle tracking revealed increased disorder in crystalline regions bordering defects, the amount of which depends on the type of defect, distance from the defect, and particle volume fraction. In total these observations suggest that interfacial free energy is the crucial parameter for premelting in colloidal and in atomic scale crystals.

  13. Transport properties of silicate melts

    Ni, Huaiwei; Hui, Hejiu; Steinle-Neumann, Gerd


    A quantitative description of the transport properties, diffusivity, viscosity, electrical, and thermal conductivity, of silicate melts is essential for understanding melting-related petrologic and geodynamic processes. We here provide a systematic overview on the current knowledge of these properties from experiments and molecular dynamics simulations, their dependence on pressure, temperature, and composition, atomistic processes underlying them, and physical models to describe their variations. We further establish phenomenological and physical links between diffusivity, viscosity, and electrical conductivity that are based on structural rearrangement in the melt. Neutral molecules and network-modifying cations with low electric field strength display intrinsic diffusivity, which is controlled by the intrinsic properties (size and valence) of the species. By contrast, oxygen and network formers with high field strength show extrinsic diffusivity, which is more sensitive to extrinsic parameters including temperature (T), pressure (P), and melt composition (X). Similar T-P-X dependence of diffusivity and electrical conductivity and their quantitative relation reveal the role of intrinsically diffusing species in electrical transport, while viscosity is tied to the extrinsically diffusing species in a similar way. However, the differences in the structural role and mobility of various atomic species diminish with increasing temperature and/or pressure: all transport processes are increasingly coupled, eventually converging to a uniform rate and mechanism. Accurate comprehension of interatomic interactions and melt structure is vital to fully accounting for the compositional dependence of transport properties, and simple polymerization parameters such as nonbridging oxygen per tetrahedrally coordinated cation are inadequate.

  14. DSC melting behavior of irradiated low density polyethylenes containing antioxidants

    The effect of antioxidants (0.5 wt% content) on the melting behaviour of low density polyethylenes, one branched and one linear, was examined with data obtained by DSC. The two polyethylenes exhibit noticeable differences in pure form: LLDPE has a higher melting point, lower heat of fusion and a more complex fusion endotherm than LDPE. The addition of antioxidants has a scarcely noticeable influence on the melting behaviour of LDPE whether irradiated or not, while in the case of LLDPE the effect is more visible. However, a careful analysis of the observed characteristics, peak temperatures and lamellae thickness distribution as well as heat of fusion, show that the observed effects are appearing as the consequence of chemical processes, scission and crosslinking, which occur in PE under either thermomechanical action (mixing in the course of the sample preparation), or radiation. (author)

  15. Flash heating in the diamond cell: melting curve of rhenium.

    Yang, Liuxiang; Karandikar, Amol; Boehler, Reinhard


    A new method for measuring melting temperatures in the laser-heated diamond cell is described. This method circumvents previous problems associated with the sample instability, thermal runaway, and chemical reactions. Samples were heated with a single, 20 milliseconds rectangular pulse from a fiber laser, monitoring their thermal response with a fast photomultiplier while measuring the steady state temperature with a CCD spectrometer. The samples were recovered and analyzed using scanning electron microscopy. Focused ion beam milling allowed to examine both the lateral and the vertical solid-liquid boundaries. Ambient pressure tests reproducibly yielded the known melting temperatures of rhenium and molybdenum. Melting of Re was measured to 50 GPa, a 5-fold extension of previous data. The refractory character of Re is drastically enhanced by pressure, in contrast to Mo. PMID:22755641

  16. Organochlorine compounds in ice melt water from Italian Alpine rivers.

    Villa, Sara; Negrelli, Christian; Finizio, Antonio; Flora, Onelio; Vighi, Marco


    Organochlorine chemicals (OCs) (dichlorodiphenyltrichloroethanes, hexachlorocyclohexanes, and hexachlorobenzene) were measured in ice melt water from five glaciers in the Italian Alps. Even though the data collected may not be sufficient for a precise description of persistent organic pollutant release patterns from glacier melting, they have, however, highlighted the potential for surface water contamination. Concentrations were of the same order of magnitude in all glacial streams, indicating comparable contamination levels in different glaciers of the alpine region. OC levels in nonglacial springs sampled in the same areas are usually lower. Even if differences during the melting season (from spring to autumn) have been identified, a regular seasonal pattern in OC concentrations was not observed. Risk for the aquatic environment is excluded through direct water exposure, but it is likely to occur through biomagnification and secondary poisoning exposure. PMID:16054693

  17. Thermodynamics of freezing and melting.

    Pedersen, Ulf R; Costigliola, Lorenzo; Bailey, Nicholas P; Schrøder, Thomas B; Dyre, Jeppe C


    Although the freezing of liquids and melting of crystals are fundamental for many areas of the sciences, even simple properties like the temperature-pressure relation along the melting line cannot be predicted today. Here we present a theory in which properties of the coexisting crystal and liquid phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio), and the liquid's diffusion constant and viscosity. The framework developed, which applies for the sizable class of systems characterized by hidden scale invariance, is validated by computer simulations of the standard 12-6 Lennard-Jones system. PMID:27530064

  18. The melting behaviour of uranium/neptunium mixed oxides

    Highlights: • Melting temperatures in the (UO2 + NpO2) system have been measured by laser heating and fast pyrometry. • The melting behaviour of this system is satisfactorily described by an ideal solution model. • Raman spectroscopy demonstrates that blending and sintering of UO2 and NpO2 results in the formation of oxygen defects. • Addition of NpO2 to a UO2 matrix does not lead to significant chemical or thermal changes. - Abstract: The melting behaviour in the pseudo-binary system (UO2 + NpO2) has been studied experimentally for the first time in this work with the help of laser heating under controlled atmosphere. It has been observed that the solidus and liquidus lines of this system follow an ideal solution behaviour (negligible mixing enthalpy) between the well-established solid/liquid transition temperatures of pure UO2 (3130 K) and that recently assessed for NpO2 (T = 3070 K). Pre- and post-melting material characterizations performed with the help of X-ray diffraction and Raman spectroscopy are also consistent with ideal mixing of the two end members. Such behaviour follows the similar structure and bonding properties of tetravalent uranium and neptunium and the similar melting points of the two oxides. The interest of this investigation is twofold. From a technological viewpoint, it indicates that the incorporation of NpO2 in UO2 fuel or transmutation targets is a viable option to recycle neptunium without inducing any relevant change in the chemical or thermal stability of the uranium dioxide matrix, even up to the melting point. From a more fundamental perspective, it confirms that actinide dioxides, and particularly UO2, tend to mix in a way closer to ideal, the closer are the atomic numbers, 5-f electron shell filling, atomic radii and oxygen potentials of the metals forming the pure dioxides

  19. Challenges in Melt Furnace Tests

    Belt, Cynthia


    Measurement is a critical part of running a cast house. Key performance indicators such as energy intensity, production (or melt rate), downtime (or OEE), and melt loss must all be understood and monitored on a weekly or monthly basis. Continuous process variables such as bath temperature, flue temperature, and furnace pressure should be used to control the furnace systems along with storing the values in databases for later analysis. While using measurement to track furnace performance over time is important, there is also a time and place for short-term tests.

  20. Skull melting of synthetic minerals

    Scott, S.D.; Hull, D.E.; Herrick, C.C.


    Direct high-frequency induction melting of dielectric materials in a water-cooled cage has been developed in the LASL synthetic minerals program. Molten material is contained in a skull, i.e., sintered shell, of its own composition so the traditional problems associated with refractory melt contamination are essentially eliminated. Preliminary analyses of power input, cage design, and coil geometry are discussed. Initial experimental results on the preparation of polycrystalline ingots, single crystals, and glasses are presented along with possible applications of this technique.

  1. Medium-range order clusters in metal melts

    BIAN; Xiufang(边秀房); PAN; Xuemin(潘学民); QIN; Xubo(秦绪波); JIANG; Minhua(蒋民华)


    Structures of molten metals Cu and Al,alloys Cu-Al,Al-Ni,Al-Fe and,Al-Si were investigated by using high temperature X-ray diffractometer.It has been found that there are not only short-range order structures (SRO) but also medium range order structures (MRO) in Cu-Al,Al-Ni,Al-Fe alloy melts.There are only short-range order structures in the pure metals Cu and Al and Al-Si alloy melts at different temperatures.It has also been found that the presence and the disappearance of the MRO structures in molten metals are a function of temperature.Moreover,the pre-peak in the structure factor is an indication of MRO in molten metals.There is a pre-peak in each structure factor S(Q) of Al-Fe alloy melt containing 14 wt% Fe,16 wt% Fe and 19 wt% Fe at 1550℃,showing that there are the medium range order structures in these alloy melts.For Al-35wt%Ni alloy,the pre-peak exists in S(Q) when the temperature is lower than 1300℃,and it is weakened drastically when the temperature surpasses 1300℃.The pre-peak occurs at values of scattering vector Q=18.5 nm-1 in the structural factor of Cu-12 wt %Al alloy melts at 1250℃.The height of the pre-peak in the melt decreases with increasing temperature.These results show that there exist not only the SRO structure but also MRO structure in the Al-TM melts,and the MRO is correspondent to the tendency of formation of chemical compound.The formation mechanism of the MRO is also studied in this work.Based on the measured results of Cu-Al alloy,a model of the MRO is presented.``

  2. Melting and liquid structure of polyvalent metal halides

    A short review is given of recent progress in determining and understanding liquid structure types and melting mechanisms for halides of polyvalent metals. The nature of the preferred local coordination for the polyvalent metal ion in the melt can usually be ascertained from data on liquid mixtures with halogen-donating alkali halides. The stability of these local coordination states and the connectivity that arises between them in the approach to the pure melt determines the character of its short-range and possible medium-range order. A broad classification of structural and melting behaviours can be given on the basis of measured melting parameters and transport coefficients for many compounds, in combination with the available diffraction data on the liquid structure of several compounds. Correlations have been shown to exist with a simple indicator of the nature of the chemical bond and also with appropriate parameters of ionic models, wherever the latter are usefully applicable for semiquantitative calculations of liquid structure. Consequences on the mechanisms for valence electron localization in solutions of metallic elements into strongly structured molten salts are also briefly discussed. (author). 46 refs, 4 figs, 2 tabs

  3. Incorporation of atomic carbon and hydrogen in high-melting oxide - nuclear-chemical, dilatometric and infrared spectroscopical investigations on C- and H-doped MgO and CaO-monocrystals

    C and H doped monocrystals of MgO and CaO were investigated in a temperature region of 78 K to 1500 K for the chemical state of the doping agents and their temperature-dependent behaviour. Starting with monocrystals obtained by coal arcing, carbon doping was carried out via the nuclear reaction 12C (d,p)13C, whereas hydrogen doping is present from the start of the crystal growth due to remaining moisture of the initial product. Hydrogen is present in the form of OH-contained defects or secondary produced Hz bubbles. All investigations, namely laser microprobe investigations, infrared spectroscopy, CO2 and hydrocarbon formation measurements and argon and O2 atmosphere, C-profile measurements, diffusion measurements, thermal expansion, lead to the result that carbon in the atomic form is present in the lattice on interstitial places or cation vacancies. The reaction mechanisms are discussed. An interaction model (between OH and C defects) does not completely clarify the complex IR spectra in detail, however shows good agreement with the experimental results. (RB)

  4. Melt-Enhanced Rejuvenation of Lithospheric Mantle: Insights from the Colorado Plateau

    Roy, Mousumi; Holtzman, Ben; Gaherty, James


    The stability of the lithospheric mantle beneath the ancient cratonic cores of continents is primarily a function of chemical modification during the process of melt extraction. Processes by which stable continental lithosphere may be destabilized are not well-understood, although destabilization by thickening and removal of negatively-buoyant lithospheric mantle in "delamination" events has been proposed in a number of tectonic settings. In this paper we explore an alternative process for destabilizing continents, namely, thermal and chemical modification during infiltration of metasomatic fluids and melts into the lithospheric column. We consider observations pertinent to the structure and evolution of the Colorado Plateau within the western United States to argue that the physical and chemical state of the margins of the plateau have been variably modified and destabilized by interaction with melts. In the melt-infiltration process explored here, the primary mechanism for weakening and rejuvenating the pla...

  5. Kinetics of iron oxidation in silicate melts

    High-temperature XANES experiments at the Fe K-edge have been used to study the kinetics of iron oxidation in a supercooled melt of Fe-bearing pyroxene composition. These experiments, made just above the glass transition between 600 and 700 deg C, show that variations in relative abundances of ferric and ferrous iron can be determined in situ at such temperatures. The kinetics of iron oxidation do not vary much with temperature down to the glass transition. This suggests that rate-limiting factor in this process is not oxygen diffusion, which is coupled to relaxation of the silicate network, but diffusion of network modifying cations along with a counter flux of electrons. To give a firmer basis to redox determinations made from XANES spectroscopy, the redox state of a series of a samples was first determined from wet chemical, Moessbauer spectroscopy and electron microprobe analyses. (authors)

  6. Primordial metallic melt in the deep mantle

    Zhang, Zhou; Dorfman, Susannah M.; Labidi, Jabrane; Zhang, Shuai; Li, Mingming; Manga, Michael; Stixrude, Lars; McDonough, William F.; Williams, Quentin


    Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large-scale variations in temperature and composition in the deep mantle. Other characteristics include elevated density, elevated bulk sound speed, and sharp boundaries. We show that properties of LLSVPs can be explained by the presence of small quantities (0.3-3%) of suspended, dense Fe-Ni-S liquid. Trapping of metallic liquid is demonstrated to be likely during the crystallization of a dense basal magma ocean, and retention of such melts is consistent with currently available experimental constraints. Calculated seismic velocities and densities of lower mantle material containing low-abundance metallic liquids match the observed LLSVP properties. Small quantities of metallic liquids trapped at depth provide a natural explanation for primitive noble gas signatures in plume-related magmas. Our model hence provides a mechanism for generating large-scale chemical heterogeneities in Earth's early history and makes clear predictions for future tests of our hypothesis.

  7. The Melt Segregation During Ascent of Buoyant Diapirs in Subduction Zones

    Zhang, N.; Behn, M. D.; Parmentier, E. M.; Kincaid, C. R.


    Cold, low-density diapirs arising from hydrated mantle and/or subducted sediments on the top of subducting slabs may transport key chemical signatures from the slab to the shallow source region for arc magmas. These chemical signatures are strongly influenced by melting of this buoyant material during its ascent. However, to date there have been relatively few quantitative models to constrain melting and melt segregation in an ascending diapir, as well as the induced geochemical signature. Here, we use a two-phase Darcy-Stokes-energy model to investigate thermal evolution, melting, and melt segregation in buoyant diapirs as they ascend through the mantle wedge. Using a simplified 2-D axi-symmetric circular geometry we investigate diapir evolution in three scenarios with increasing complexity. First, we consider a case without melting in which the thermal evolution of the diapir is controlled solely by thermal diffusion during ascent. Our results show that for most cases (e.g., diapir radius ≤ 3.7 km and diapir generation depths of ~ 75 km) thermal diffusion times are smaller than the ascent time—implying that the diapir will thermal equilibrate with the mantle wedge. Secondly, we parameterize melting within the diapir, but without melt segregation, and add the effect of latent heat to the thermal evolution of the diapir. Latent heat significantly buffers heating of the diapir. For the diapir with radius ~3.7 km, the heating from the outside is slowed down ~30%. Finally, we include melt segregation within the diapir in the model. Melting initiates at the boundaries of the diapir as the cold interior warms in response to thermal equilibration with the hot mantle wedge. This forms a high porosity, high permeability rim around the margin of the diapir. As the diapir continues to warm and ascend, new melts migrate into this rim and are focused upward, accumulating at the top of the diapir. The rim thus acts like an annulus melt channel isolating the central part of

  8. Lithium hydride near melting point

    The mechanical stability of LiH crystal is studied in this paper. The instability temperature Te is found to lie above the observed melting point, in accord with computer simulation results of other materials. Several other features of LiH both in the solid and molten states are also discussed. (author). 22 refs, 4 figs

  9. Melting of alloy CTZ-110 in the electron-beam scull installation with the use gun of high-voltage glow discharge

    The results of melting alloy ingots Zr1Nb on the basis of the calcium-thermal zirconium using electron gas discharge gun GEG-300 are presented in this paper. Chemical composition, macro- and microstructure, hardness and microhardness of the ingots were investigated. Conditions of application of electromagnetic stirring of the melt at the melting of zirconium alloy ingots are discussed. Recommendations on the use of electron gas discharge gun and the electromagnetic mixing at the melting of ingots are given

  10. Influence of the melt structure on the electrodeposition of molybdenum

    The influence of ionic structure molten salts used as electrolyte in electrodeposition of molybdenum has been studied by voltammetric and chronopentiometric method. It was found that during the dissolution for potassium molybdenum in KF-B2O3 electrolyte, both electrochemically active and inactive, molybdenum containing species have been created in the melt. The electrochemically active molybdenum compound was created by a chemical reaction with boron containing constituents in the melt. Electrochemically inactive molybdenum species were created by the reaction of K2MoO4 with fluoride anions. Using the complex thermodynamics and physico-chemical analysis it was found that the investigated electrolyte KF-K2MoO4-B2O3 the electrochemical process is significantly facilitated by the formation of complex heteropolyanions with lowered symmetry of coordination sphere. (author)

  11. Manufacturing of amber particles suitable for composite fibre melt spinning

    Ļašenko Inga Ļ


    Full Text Available Polyamide fibre containing amber particles was fabricated. The amber particles were obtained by grinding technology using planetary ball-mills. Scanning electron microscopy and granulometry testing were used to characterise the structure and the size of prepared amber particles. Fourier transform infrared spectroscopy was used to analyse the chemical structure of the amber particles. The amber particles were characterised with average size up to 3 μm. The chemical composition of amber before and after the grinding remained unchanged. The amber particles were melt-extruded using polyamide 6 as the matrix. Melt spinning processing was used to fabricate polyamide-amber filaments. Pre-oriented yarns and fully drawn yarns were obtained after hotdrawing experiments. Reported experimental findings of amber composite fibre could be important for textile applications.

  12. Disordering and Melting of Aluminum Surfaces

    Stoltze, Per; Nørskov, Jens Kehlet; Landman, U.


    We report on a molecular-dynamics simulation of an Al(110) surface using the effective-medium theory to describe the interatomic interactions. The surface region is found to start melting ≅200 K below the bulk melting temperature with a gradual increase in the thickness of the disordered layer...... as the temperature approaches the bulk melting point. The more close-packed Al(111) surface shows a much weaker disordering below the melting temperature....

  13. Asymmetric Melting and Freezing Kinetics in Silicon.

    Aziz, Michael; Tsao, Jeff Y.; Thompson, Michael O.; Peercy, Paul S.


    We report measurements of the melting velocity of amorphous Si relative to that of (100) crystalline Si. These measurements permit the first severe experimental test of theories describing highly nonequilibrium freezing and melting. The results indicate that freezing in Si is inherently slower than melting; this asymmetry can be interpreted in terms of an entropy-related reduction in the freezing rate.

  14. Multijet investigations with tin melt

    In the experiments which are described in this paper, several jets or chains of drops by hot tin melt were side by side brought into a container filled with water, so that the melt formed a plane in the water. By the ignition of an underwater bridgewire explosion an interaction was triggered at that jet, which was nearest to the explosion centre. Under suitable conditions this interaction leaped over to neighbouring jets and reached even the most distant jet, when not stopped before. The propagation could be recorded by a high speed camera. The records showed, that the interactions propagated in special directions and the velocity of the propagation was in a range of 2 to 8 m/s. The position of the drops and their distance to each other is very important for the propagation. By separating the single melt jets with fixed copper plats, it could be showed, that hydrodynamic effects are not responsible for the propagation of the interactions. Shock waves, resulting from the interaction cycles, are the cause for the propagation of the interactions. (orig.)

  15. A Comprehensive Evaluation of the Melting Points of Fatty Acids and Esters Determined by Differential Scanning Calorimetry

    The melting point is one of the most important physical properties of a chemical compound and plays a significant role in determining possible applications. For fatty acid esters the melting point is essential for a variety of food and non-food applications, the latter including biodiesel and its c...

  16. Ash melting behavior by Fourier transform infrared spectroscopy

    LI Han-xu; QIU Xiao-sheng; TANG Yong-xin


    A Fourier Transform Infrared Spectroscopic (FTIR) method involving a Fe2O3 flux was used to learn how China's coal ash melts. The relationship between ash fusion temperature and chemical composition, as well as the effects of Fe2O3 flux on the ash fusion temperature were studied. The relationship between ash fusion temperature and chemical composition, mineralogical phases and functional groups was analyzed with the FTIR method. The results show that the ash fusion temperature is related to the location and transmittance of certain absorption peaks, which is of great significance for the study of ash behavior.

  17. Dehydration melting of solid amphibolite at 2.0 GPa: Effects of time and temperature

    ZHOU; Wenge; XIE; Hongsen; LIU; Yonggang; ZHENG; Xiaogang


    Two sets of dehydration-melting with a natural solid amphibolite, collected from North Himalayan structure zone, Tibet, have been carried out in multi-anvil apparatus at 2.0 GPa and 800―1000℃, for 12―200 h. One is keeping the pressure at 2.0 GPa and the annealing time of 12 h, changing the temperature (800―1000℃). The other is keeping the pressure at 2.0 GPa and temperature at 850℃, varying the annealing time (12―200 h). The products are inspected with microscope and electron probe. The results indicate that at 2.0 GPa, annealing time of 12 h, garnets, melts and clinopyroxenes occur in amphibolite gradually with increasing temperature and the chemical compositions of melt vary from tonalite to granodiorite, and then to tonalite. However, at 2.0 GPa and 850℃, with the annealing time increasing, the garnets, melts and clinopyroxenes also occur in amphibolite gradually and the chemical compositions of melt vary from tonalite to granodiorite. In both cases, melts interconnect with each other when the contents of melt are over the 5 vol.%. the viscosities of the melt produced in amphibolite at temperature higher than 850℃ are on a level with 104 Pa·s. The interconnected melt with such a viscosity may segregate from the source rock and form the magma over reasonable geological time. Therefore, it is believed that at the lower part of the overthickened crust, the tonlitic and granodioritic magma may be generated through the dehydration melting of amphibolite.

  18. Melting of the Primitive Mercurian Mantle, Insights into the Origin of Its Surface Composition

    Boujibar, A.; Righter, K.; Rapp, J. F.; Ross, D. K.; Pando, K. M.; Danielson, L. R.; Fontaine, E.


    Recent findings of the MESSENGER mission on Mercury have brought new evidence for its reducing nature, widespread volcanism and surface compositional heteregeneity. MESSENGER also provided major elemental ratios of its surface that can be used to infer large-scale differentiation processes and the thermal history of the planet. Mercury is known as being very reduced, with very low Fe-content and high S and alkali contents on its surface. Its bulk composition is therefore likely close to EH enstatite chondrites. In order to elucidate the origin of the chemical diversity of Mercury's surface, we determined the melting properties of EH enstatite chondrites, at pressures between 1 bar and 3 GPa and oxygen fugacity of IW-3 to IW-5, using piston-cylinder experiments, combined with a previous study on EH4 melting at 1 bar. We found that the presence of Ca-rich sulfide melts induces significant decrease of Ca-content in silicate melts at low pressure and low degree of melting (F). Also at pressures lower than 3 GPa, the SiO2-content decreases with F, while it increases at 3 GPa. This is likely due to the chemical composition of the bulk silicate which has a (Mg+Fe+Ca)/Si ratio very close to 1 and to the change from incongruent to congruent melting of enstatite. We then tested whether the various chemical compositions of Mercury's surface can result from mixing between two melting products of EH chondrites. We found that the majority of the geochemical provinces of Mercury's surface can be explained by mixing of two melts, with the exception of the High-Al plains that require an Al-rich source. Our findings indicate that Mercury's surface could have been produced by polybaric melting of a relatively primitive mantle.

  19. Composition and heterogeneity of anorthositic impact melt at Mistastin Lake crater, Labrador

    Marion, Cassandra L.; Sylvester, Paul J.


    Anorthositic impact melt rocks, their target rocks (principally anorthosite, mangerite, granodiorite) and zircon clasts from the ˜36-Ma-old, 28-km-wide Mistastin Lake crater of northern Labrador (55°53'N; 63°18'W) have been examined in order to evaluate the scale and origin of compositional heterogeneities in impact melts produced in craters of moderate size. In particular we assess whether and, if so, how the initial composition of the impact melt was modified as it entrained mineral clasts derived from the underlying rocks over which it flowed when it moved away from the shock-induced, central melting zone. A secondary goal was to determine if zircon clasts in the impact melts are present in the proportions of their target rock sources and/or the substrate lithologies over which they flowed. Chemical compositions of bulk samples of 33 melt rocks and 14 target rocks were measured by XRF and SN-ICPMS. Matrix compositions of nine samples of impact melt rocks were determined by EPMA and LA-ICPMS. Zircon grains from four samples of target rock and zircon clasts from three samples of impact melt rock were measured for multi-element composition, U-Pb age and Hf-isotopic composition by LA-(MC)-ICPMS. The data reveal compositional heterogeneities in the impact melts on the scales of both bulk samples and matrices. Bulk samples can be divided into compositions with high and low concentrations of high-field-strength elements (HFSE; Ti, Zr, Nb) and Fe, Ba, Ce and Y. High HFSE-type melt rocks formed when impact melt entrained large quantities of clasts from mangerite, which is rich in HFSE. Matrix compositions of bulk samples do not show the HFSE distinction but are affected by the introduction of low-temperature melts from the clasts to form dispersed, micron-scale silica-rich heterogeneities. The best estimate of sources of the initial impact melt is ˜73% anorthosite, ˜7% mangerite and ˜20% granodiorite, based on least-squares modeling of major-element compositions of

  20. Melt evolution and residence in extending crust: Thermal modeling of the crust and crustal magmas

    Karakas, Ozge; Dufek, Josef


    Tectonic extension and magmatism often act in concert to modify the thermal, mechanical, and chemical structure of the crust. Quantifying the effects of extension and magma flux on melting relationships in the crust is fundamental to determining the rate of crustal melting versus fractionation, magma residence time, and the growth of continental crust in rift environments. In order to understand the coupled control of tectonic extension and magma emplacement on crustal thermal evolution, we develop a numerical model that accounts for extension and thermal-petrographic processes in diverse extensional settings. We show that magma flux exerts the primary control on melt generation and tectonic extension amplifies the volume of melt residing in the crustal column. Diking into an extending crust produces hybrid magmas composed of 1) residual melt remaining after partial crystallization of basalt (mantle-derived melt) and 2) melt from partial melting of the crust (crustal melt). In an extending crust, mantle-derived melts are more prevalent than crustal melts across a range of magma fluxes, tectonic extension rates, and magmatic water contents. In most of the conditions, crustal temperatures do not reach their solidus temperatures to initiate partial melting of these igneous lithologies. Energy balance calculations show that the total enthalpy transported by dikes is primarily used for increasing the sensible heat of the cold surrounding crust with little energy contributing to latent heat of melting the crust (maximum crustal melting efficiency is 6%). In the lower crust, an extensive mush region develops for most of the conditions. Upper crustal crystalline mush is produced by continuous emplacement of magma with geologically reasonable flux and extension rates on timescales of 106 yr. Addition of tectonic effects and non-linear melt fraction relationships demonstrates that the magma flux required to sustain partially molten regions in the upper crust is within the

  1. Highly refractory peridotites in Songshugou, Qinling orogen: Insights into partial melting and melt/fluid-rock reactions in forearc mantle

    Cao, Yi; Song, Shuguang; Su, Li; Jung, Haemyeong; Niu, Yaoling


    The Songshugou ultramafic massif is located in the eastern segment of the Qinling orogenic belt, central China. It is a large spinel peridotite body dominated by coarse-grained, porphyroclastic, and fine-grained dunite with minor harzburgite, olivine clinopyroxenite, and banded/podiform chromitite. The compositions of the bulk-rock dunite and harzburgite, and the constituent olivine and spinel, together with the textures and chemical characteristics of multiphase mineral inclusions, point to the highly refractory nature of these rocks with complex histories of high-temperature boninite melt generation and boninitic melt-rock reaction, probably in a young, warm, and volatile-rich forearc lithospheric mantle setting. Additionally, a subsequent low-temperature fluid-rock reaction is also recorded by TiO2-rich spinel with Ti solubility/mobility enhanced by chloride- or fluoride-rich subduction-zone fluids as advocated by Rapp et al. (2010). The olivine clinopyroxenite, on the other hand, was likely crystallized from a residual boninitic melt that had reacted with harzburgitic residues. The ubiquitous occurrences of hydrous minerals, such as anthophyllite, tremolite, Cr-chlorite, and serpentine (stable at lower P-T crustal conditions) in the matrix, suggest that further low-temperature fluid-rock reaction (or retrograde metamorphism) has affected the original volatile-poor peridotites either in a mature and cool subduction zone, or in a continental crust during their exhumation into the Qinling collisional orogeny at early Paleozoic era, or both. The prolonged and intense ductile/brittle deformation can decrease the mineral grain size through dynamic recrystallization and fracturing, and thus aid the fluid-rock reaction or retrograde metamorphism and mineral chemical re-equilibration processes. Therefore, the Songshugou peridotites present a good example for understanding the petrogenesis and evolution of the mantle wedge, with the emphasis on the complex partial

  2. Density of iron-nickel melts

    Iron-nickel melt density is studied in the wide ranges of concentrations and temperatures using the penetrating gamma radiation method. Mean coordination numbers and interatomic distances have been calculated. Attainment of equilibrium state from the point of view of the melt composition and microvolume structure requires, depending on melting condition, rather long time in some cases, up to several hours. Concentration dependences of density, mean coordination numbers and interatomic distances indicate complex, heterogeneous microstructure of the Fe-Ni melts. In equilibrium the level of heterogeneity as well as the short-range order structure significantly depend on melt composition

  3. Vapor segregation and loss in basaltic melts

    Edmonds, M.; Gerlach, T.M.


    Measurements of volcanic gases at Pu'u'O??'o??, Kilauea Volcano, Hawai'i, reveal distinct degassing regimes with respect to vapor segregation and loss during effusive activity in 2004-2005. Three styles of vapor loss are distinguished by the chemical character of the emitted volcanic gases, measured by open path Fourier transform infrared spectroscopy: 1 persistent continuous gas emission, 2 gas piston events, and 3 lava spattering. Persistent continuous gas emission is associated with magma ascent and degassing beneath the crater vents, then eruption of the degassed magma from flank vents. Gas piston events are the result of static gas accumulation at depths of 400-900 m beneath Pu'u'O??'o??. A CO2-rich gas slug travels up the conduit at a few meters per second, displacing magma as it expands. Lava spattering occurs due to dynamic bubble coalescence in a column of relatively stagnant magma. The Large gas bubbles are H2O rich and are generated by open-system degassing at depths of segregation in basaltic melts, but their implications differ. Accumulation and segregation of CO2-rich vapor at depth does not deplete the melt of H2O (required to drive lava fountains near to the surface) and therefore gas piston events can occur interspersed with lava fountaining activity. Lava spattering, however, efficiently strips H2O-rich vapor from magma beneath the crater vents; the magma must then erupt effusively from vents on the flank of the cone. ?? 2007 The Geological Society of America.

  4. Global Warming and Glaciers Melting at Fjords in Greenland

    Coelho, Pablo


    This paper presents a discussion on the validation or not of a likely paradigm about the melting of polar glaciers and their direct impact on increasing ocean levels. Physico-chemical properties of ocean waters, as well as anomalies in the thermal behavior of water are used as providers of this discussion using fjords of Greenland as study area. This text seeks to infer the relationship between the most recent developments in global warming, specifically dealing with the melting of glaciers located in fjords in the eastern part of Greenland, increasing the water temperature in ocean currents and changes in sea levels. We emphasize the importance of the correlation of the water physico-chemical characteristics in these changes perceived in the studied environment. Greenland is defined by convention as the widest oceanic island in the world. In its fjords formed in the last glaciation of the Quaternary period, basically made of ice mountains with entries to the sea, there has been melts that are discussed in this work. At first, global warming and the melting of glaciers with a consequent rise in sea levels are presented almost as an axiom. This paper seeks to address the conclusions arising from this type of research according the basic laws of physics and chemistry, related to the behavior of water in their states (typically solid and liquid). The ultimate goal of this work glimpsed through some inferences and validation of water behavior in the ice condition and in its liquid state, a broader view with regard to the findings applied to the relationship between global warming and ice melting processes. Will be observed some water anomalies in the variation between its liquid and solid states to attempt a better understanding of the phenomena occurring in this area of interest as well as their possible impacts. It is noteworthy the fact that the water does not behave thermally as most liquids, with very specific consequences in relation to the variation between its

  5. Industrial opportunities of controlled melt flow during glass melting, part 1: Melt flow evaluation

    Dyrčíková, Petra; Hrbek, Lukáš; Němec, Lubomír


    Roč. 58, č. 2 (2014), s. 111-117. ISSN 0862-5468 R&D Projects: GA TA ČR TA01010844 Institutional support: RVO:67985891 Keywords : glass melting * controlled flow * space utilization Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.435, year: 2014

  6. Melting by temperature-modulated calorimetry

    Wunderlich, B.; Okazaki, Iwao; Ishikiriyama, Kazuhiko; Boller, A. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States)


    Well-crystallized macromolecules melt irreversibly due to the need of molecular nucleation, while small molecules melt reversibly as long as crystal nuclei are present to assist crystallization. Furthermore, imperfect crystals of low-molar-mass polymers may have a sufficiently small region of metastability between crystallization and melting to show a reversing heat-flow component due to melting of poor crystals followed by crystallization of imperfect crystals which have insufficient time to perfect before the modulation switches to heating and melts the imperfect crystals. Many metals, in turn. melt sharply and reversibly as long as nuclei remain after melting for subsequent crystallization during the cooling cycle. Their analysis is complicated, however, due to thermal conductivity limitations of the calorimeters. Polymers of sufficiently high molar mass, finally, show a small amount of reversible. local melting that may be linked to partial melting of individual molecules. Experiments by temperature-modulated calorimetry and model calculations are presented. The samples measured included poly(ethylene terephthalate)s, poly(ethylene oxide)s, and indium. Two unsolved problems that arose from this research involve the origin of a high, seemingly stable, reversible heat capacity of polymers in the melting region, and a smoothing of melting and crystallization into a close-to-elliptical Lissajous figure in a heat-flow versus sample-temperature plot.

  7. Long term coolability of a core melt

    One of the problems which must be solved in severe accidents is the melt concrete interaction which occurs when the core debris penetrates the lower vessel head and contacts the basement. To prevent these consequences a core catcher concept is considered to be integrated into a new PWR design based on the standard German PWR. The core catcher achieves coolability by spreading and fragmentation of the ex-vessel core melt based on the process of water inlet from the bottom through the melt. In order to identify the dominant processes of flooding the melt from the bottom experiments in laboratory scale have been carried out. To get more detailed information on the very important process of water penetration into the melt, a simulant experiment has been conducted using a transparent plastic melt with the typical viscosity behaviour of an oxidic corium melt and a temperature allowing evaporation of water. (orig.(DG)

  8. Decontamination of transuranic contaminated metals by melt refining

    Melt refining of transuranic contaminated metals is a possible decontamination process with the potential advantages of producing metal for reuse and of simplifying chemical analyses. By routinely achieving the 10 nCi/g( about0.1ppm) level by melt refining, scrap metal can be removed from the transuranic waste category. (To demonstrate the effectiveness of this melt refining process, mild steel, stainless steel, nickel, and copper were contaminated with 500 ppm (μg/g) PuO2 and melted with various fluxes. The solidified slags and metals were analyzed for their plutonium contents, and corresponding partition ratios for plutonium were calculated. Some metals were double refined in order to study the effect of secondary slag treatment. The initial weight of the slags was also varied to investigate the effect of slag weight on the degree of plutonium removal. In general, all four metals could be decontaminated below 1 ppm (μg/g) Pu ( about100 nCi/g) by a single slag treatment. Doubling the slag weight did not improve decontamination significantly; however, double slag treatment using 5 wt.% slag did decontaminate the metals to below 0.1 ppm (μg/g) Pu (10 nCi/g).)

  9. Fluid—Melt and Fluid Inclusions in Mianning REE Deposit,Sichuan Southwest Cina

    牛贺才; 林茂青; 等


    Abundant fluid-melt inclusions are found in the aegirine-augite-barite pegmatite and carbonatite veins in the Mianning REE deposit,Sichuan,They were trapped in early stage fluorite and quartz from a salt-melt system at temperatures higher than 5000℃,Meanwhile,fluid inclusions are also present in alrge amounts in bastnaesite.Homogenized between 150 and 270℃,these inclusions are thought to be representative of the physico-chemical conditions of REE mineralization.These results show that the Mianning REE deposit is of typical hydrothermal origin developed from a salt-melt system.

  10. Microstructural changes due to laser surface melting of an AISI 304 stainless steel

    d?Oliveira A.S.C.M.


    Full Text Available Several techniques can be used to improve surface properties. These can involve changes on the surface chemical composition (such as alloying and surface welding processes or on the surface microstructure, such as hardening and melting. In the present work surface melting with a 3kW CO2 cw laser was done to alter surface features of an AISI 304 stainless steel. Microstructure characterisation was done by optical and scanning electron microscopy. Vickers and Knoop microhardness tests evaluated mechanical features after surface melting. Phase transformation during rapid solidification is analysed and discussed.

  11. Assessment of the melting behavior of batches containing boron oxide carrier raw materials

    Jatmiko, Widiya


    The kinetic aspects of batch melting related to grain size, primary melt formation, gas liberation, and quartz dissolution can only be characterized by performing laboratory experiments, whereas the thermodynamic aspects can be quantified theoretically. One approach to close the gap between laboratory and industrial practice is scaling up experiments from the milligram to the kilogram range. In the micro scale (less than 150 mg sample), physical and chemical reactions of one component, as wel...

  12. What can we learn from melt inclusions in migmatites and granulites?

    Cesare, B.; Acosta-Vigil, A.; Bartoli, O.; Ferrero, S.


    With less than two decades of activity, research on melt inclusions (MI) in crystals from rocks that have undergone crustal anatexis - migmatites and granulites - is a recent addition to crustal petrology and geochemistry. Studies on this subject started with glassy inclusions in anatectic crustal enclaves in lavas, and then progressed to regionally metamorphosed and partially melted crustal rocks, where melt inclusions are normally crystallized into a cryptocrystalline aggregate (nanogranitoid). Since the first paper on melt inclusions in the granulites of the Kerala Khondalite Belt in 2009, reported and studied occurrences are already a few tens. Melt inclusions in migmatites and granulites show many analogies with their more common and long studied counterparts in igneous rocks, but also display very important differences and peculiarities, which are the subject of this review. Microstructurally, melt inclusions in anatectic rocks are small, commonly 10 μm in diameter, and their main mineral host is peritectic garnet, although several other hosts have been observed. Inclusion contents vary from glass in enclaves that were cooled very rapidly from supersolidus temperatures, to completely crystallized material in slowly cooled regional migmatites. The chemical composition of the inclusions can be analyzed combining several techniques (SEM, EMP, NanoSIMS, LA-ICP-MS), but in the case of crystallized inclusions the experimental remelting under confining pressure in a piston cylinder is a prerequisite. The melt is generally granitic and peraluminous, although granodioritic to trondhjemitic compositions have also been found. Being mostly primary in origin, inclusions attest for the growth of their peritectic host in the presence of melt. As a consequence, the inclusions have the unique ability of preserving information on the composition of primary anatectic crustal melts, before they undergo any of the common following changes in their way to produce crustal magmas

  13. Wasteless combined aggregate-coal-fired steam-generator/melting-converter.

    Pioro, L S; Pioro, I L


    A method of reprocessing coal sludge and ash into granulate for the building industry in a combined wasteless aggregate-steam-generator/melting-converter was developed and tested. The method involves melting sludge and ash from coal-fired steam-generators of power plants in a melting-converter installed under the steam-generator, with direct sludge drain from the steam generator combustion chamber. The direct drain of sludge into converter allows burnup of coal with high ash levels in the steam-generator without an additional source of ignition (natural gas, heating oil, etc.). Specific to the melting process is the use of a gas-air mixture with direct combustion inside a melt. This feature provides melt bubbling and helps to achieve maximum heat transfer from combustion products to the melt, to improve mixing, to increase rate of chemical reactions and to improve the conditions for burning the carbon residue from the sludge and ash. The "gross" thermal efficiency of the combined aggregate is about 93% and the converter capacity is about 18 t of melt in 100 min. The experimental data for different aspects of the proposed method are presented. The effective ash/charging materials feeding system is also discussed. The reprocessed coal ash and sludge in the form of granules can be used as fillers for concrete and as additives in the production of cement, bricks and other building materials. PMID:12781221

  14. Effects of surface shape on the geometry and surface topography of the melt pool in low-power density laser melting

    Kim, Youngdeuk


    The quantitative correlations between workpiece volume and melt pool geometry, as well as the flow and thermal features of the melt pool are established. Thermocapillary convections in melt pool with a deformable free surface are investigated with respect to surface shape and laser intensity. When the contact angle between the tangent to the top surface and the vertical wall at the hot center is acute, the free surface flattens, compared with that of the initial free surface. Otherwise, the free surface forms a bowl-like shape with a deep crater and a low peripheral rim when the contact angle at the hot center is obtuse. Increasing the workpiece volume at a fixed laser intensity and a negative radial height gradient cause linear decreases in the geometric size and magnitude of flow and temperature of the melt pool. Conversely, linear increases are observed with a positive radial height gradient. © 2011 American Institute of Chemical Engineers (AIChE).

  15. Melt decontamination of aluminum waste by electric arc melting

    In Korea, the decontamination and decommissioning of the retired TRIGA MARK II and III research reactors and a uranium conversion plant at the Korea Atomic Energy Research Institute (KAERI) has been under way. Hundreds of tons of metallic wastes are expected from the D and D of these facilities Therefore, prompt countermeasures should be taken to deal with the amount of wastes generated by dismantling the retired nuclear facilities. Most of the dismantled material is slightly contaminated. A recycle or volume reduction of the metallic wastes can be considered as one of the waste management options under the circumstances of the absence of a waste disposal site in Korea and the capacity limitation of the temporary waste storage facility at KAERI. The results of the XRD analysis showed that the surrogate nuclides move into the slag, which can be easily separated from the melt, and then they combine with the aluminum oxide to form a more stable compound. The distribution ratio of cobalt in the ingot was more than 40% according to the types of fluxes. A removal efficiency of more than 98% for the cesium and strontium from the ingot could be achieved due to their transportation from the ingot to the slag and the dust phase. Therefore, it can be expected that a greater part of the aluminum wastes generated from the retired research reactors can be recycled or their volumes reduced for a disposal by a melting

  16. Melt decontamination of aluminum waste by electric arc melting

    Choi, Wang Kyu; Song, Pyung Seob; Jung, Chong Hun; Oh, Won Zin [Korea Atomic Energy Research Institute, Taejeon (Korea, Republic of); Min, Byung Youn [Chungnam National University, Taejeon (Korea, Republic of)


    In Korea, the decontamination and decommissioning of the retired TRIGA MARK II and III research reactors and a uranium conversion plant at the Korea Atomic Energy Research Institute (KAERI) has been under way. Hundreds of tons of metallic wastes are expected from the D and D of these facilities Therefore, prompt countermeasures should be taken to deal with the amount of wastes generated by dismantling the retired nuclear facilities. Most of the dismantled material is slightly contaminated. A recycle or volume reduction of the metallic wastes can be considered as one of the waste management options under the circumstances of the absence of a waste disposal site in Korea and the capacity limitation of the temporary waste storage facility at KAERI. The results of the XRD analysis showed that the surrogate nuclides move into the slag, which can be easily separated from the melt, and then they combine with the aluminum oxide to form a more stable compound. The distribution ratio of cobalt in the ingot was more than 40% according to the types of fluxes. A removal efficiency of more than 98% for the cesium and strontium from the ingot could be achieved due to their transportation from the ingot to the slag and the dust phase. Therefore, it can be expected that a greater part of the aluminum wastes generated from the retired research reactors can be recycled or their volumes reduced for a disposal by a melting.

  17. Copolymer Melts in Disordered Media

    Stepanow, S.; Dobrynin, A.; Vilgis, T.; Binder, K.


    We have considered a symmetric AB block copolymer melt in a gel matrix with preferential adsorption of A monomers on the gel. Near the point of the microphase separation transition such a system can be described by the random field Landau-Brazovskii model, where randomness is built into the system during the polymerization of the gel matrix. By using the technique of the 2-nd Legendre transform, the phase diagram of the system is calculated. We found that preferential adsorption of the copoly...

  18. Ocean Basalt Simulator version 1 (OBS1): Trace element mass balance in adiabatic melting of a pyroxenite-bearing peridotite

    Kimura, Jun-Ichi; Kawabata, Hiroshi


    present a new numerical trace element mass balance model for adiabatic melting of a pyroxenite-bearing peridotite for estimating mantle potential temperature, depth of melting column, and pyroxenite fraction in the source mantle for a primary ocean basalt/picrite. The Ocean Basalt Simulator version 1 (OBS1) uses a thermodynamic model of adiabatic melting of a pyroxenite-bearing peridotite with experimentally/thermodynamically parameterized liquidus-solidus intervals and source mineralogy. OBS1 can be used to calculate a sequence of adiabatic melting with two melting models, including (1) melting of peridotite and pyroxenite sources with simple mixing of their fractional melts (melt-melt mixing model), and (2) pyroxenite melting, melt metasomatism in the host peridotite, and melting of the metasomatized peridotite (source-metasomatism model). OBS1 can be used to explore (1) the fractions of peridotite and pyroxenite, (2) mantle potential temperature, (3) pressure of termination of melting, (4) degree of melting, and (5) residual mode of the sources. In order to constrain these parameters, the model calculates a mass balance for 26 incompatible trace elements in the sources and in the generated basalt/picrite. OBS1 is coded in an Excel spreadsheet and runs with VBA macros. Using OBS1, we examine the source compositions and conditions of the mid-oceanic ridge basalts, Loihi-Koolau basalts in the Hawaiian hot spot, and Jurassic Shatsky Rise and Mikabu oceanic plateau basalts and picrites. The OBS1 model shows the physical conditions, chemical mass balance, and amount of pyroxenite in the source peridotite, which are keys to global mantle recycling.

  19. Electron beam melting of sponge titanium

    Fundamental investigations were done on electron beam (EB) melting of sponge titanium by using 80 kW EB melting furnace. Results obtained are as follows: (1) To increase the melting yield of titanium in EB melting of sponge titanium, it is important to recover splashed metal by installation of water-cooled copper wall around the hearth and to decrease evaporation loss of titanium by keeping the surface temperature of molten metal just above the melting temperature of titanium without local heating. (2) Specific power consumption of drip melting of pressed sponge titanium bar and hearth melting of sponge titanium are approximately 0.9 kWh/kg-Ti and 0.5-0.7 kWh/kg-Ti, respectively. (3) Ratios of the heat conducted to water-cooled mould in the drip melting and to water-cooled hearth in the hearth melting to the electron beam input power are 50-65% and 60-65%, respectively. (4) Surface defects of EB-melted ingots include rap which occurs when the EB output is excessively great, and transverse cracks when the EB output is excessively small. To prevent surface defects, the up-down withdrawal method is effective. (author)

  20. Experimental Melting Study of Basalt-Peridotite Hybrid Source: Melting model of Hawaiian plume

    Takahashi, E.; Gao, S.


    Eclogite component entrained in ascending plume is considered to be essentially important in producing flood basalts (e.g., Columbia River basalt, Takahashi et al., 1998 EPSL), alkalic OIBs (e.g., Kogiso et al.,2003), ferro-picrites (Tuff et al.,2005) and Hawaiian shield lavas (e.g., Hauri, 1996; Takahashi & Nakajima, 2002, Sobolev et al.,2005). Size of the entrained eclogite, which controls the reaction rates with ambient peridotite, however, is very difficult to constrain using geophysical observation. Among Hawaiian shield volcanoes, Koolau is the most enriched end-member in eclogite component (Frey et al, 1994). Reconstruction of Koolau volcano based on submarine study on Nuuanu landslide (AGU Monograph vol.128, 2002, Takahashi Garcia Lipman eds.) revealed that silica-rich tholeiite appeared only at the last stage (Makapuu stage) of Koolau volcano. Chemical compositions of lavas as well as isotopes change abruptly and coherently across a horizon (Shinozaki et al. and Tanaka et al. ibid.). Based on these observation, Takahashi & Nakajima (2002 ibid) proposed that the Makapuu stage lava in Koolau volcano was supplied from a single large eclogite block. In order to study melting process in Hawaiian plume, high-pressure melting experiments were carried out under dry and hydrous conditions with layered eclogite/peridotite starting materials. Detail of our experiments will be given by Gao et al (2015 AGU). Combined previous field observation with new set of experiments, we propose that variation in SiO2 among Hawaiian tholeiites represent varying degree of wall-rock interaction between eclogite and ambient peridotite. Makapuu stage lavas in Koolau volcano represents eclogite partial melts formed at ~3 GPa with various amount of xenocrystic olivines derived from Pacific plate. In other words, we propose that "primary magma" in the melting column of Hawaiian plume ranges from basaltic andesite to ferro-picrite depending on the lithology of the source. Solidus of

  1. Probing depth dependencies of melt emplacement on time dependent quantities in a continental rift scenario with melting and melt extraction

    Wallner, Herbert; Schmeling, Harro


    Since some years seismological observations provide increasing evidence of a discontinuity near the mid of older mantle lithosphere. Explanation may be a melt infiltration front (MIF) as upper margin of an evolving network of veins. These are formed by crystallized melt supplied by episodic melting events in the asthenosphere. To test this concept geodynamically we performed numerical modelling applying melting, extraction of melt and emplacement in a viscous matrix. Thereupon, we were faced to the problem defining an intrusion level for the melt. Findings of prior studies led to the need of movable, process dependent boundaries of the emplacement zone additionally making the process probably more self-consistent. Here we present a preliminary study exploring several empirical attempts to relate time dependent states to an upward moving boundary for intrusion. Modeled physics is based on thermo-mechanics of visco-plastic flow. The equations of conservation of mass, momentum and energy are solved for a multi component (crust-mantle) and two phase (melt-matrix) system. Rheology is temperature-, pressure-, and stress-dependent. In consideration of depletion and enrichment melting and solidification are controlled by a simplified linear binary solid solution model. The Compaction Boussinesq Approximation and the high Prandtl number approximation are used, elasticity is neglected and geometry is restricted to 2D. Approximation is done with the Finite Difference Method with markers in an Eulerian formulation (FDCON). Model guiding scenario is a extending thick lithosphere associated to by updoming asthenosphere probably additionally heated by a plume nearby. As the P-T conditions in the asthenosphere are near the solidus caused changes may increase melting and generate partial melt. Against conventional expectations on permeability at lithosphere-asthenosphere boundary (LAB) depth a fast melt transport into and sometimes through the lithosphere often is observed. The

  2. Dynamical meson melting in holography

    We discuss mesons in thermalizing gluon backgrounds in the N=2 supersymmetric QCD using the gravity dual. We numerically compute the dynamics of a probe D7-brane in the Vaidya-AdS geometry that corresponds to a D3-brane background thermalizing from zero to finite temperatures by energy injection. In static backgrounds, it has been known that there are two kinds of brane embeddings where the brane intersects the black hole or not. They correspond to the phases with melted or stable mesons. In our dynamical setup, we obtain three cases depending on final temperatures and injection time scales. The brane stays outside of the black hole horizon when the final temperature is low, while it intersects the horizon and settles down to the static equilibrium state when the final temperature is high. Between these two cases, we find the overeager case where the brane dynamically intersects the horizon although the final temperature is not high enough for a static brane to intersect the horizon. The interpretation of this phenomenon in the dual field theory is meson melting due to non-thermal effects caused by rapid energy injection. In addition, we comment on the late time evolution of the brane and a possibility of its reconnection

  3. Melting a Sample within TEMPUS


    One of the final runs of the TEMPUS experiment shows heating of a sample on STS-94, July 15, 1997, MET:14/11:01 (approximate) and the flows on the surface. At the point this image was taken, the sample was in the process of melting. The surface of the sample is begirning to flow, looking like the motion of plate tectonics on the surface of a planet. During this mission, TEMPUS was able to run than 120 melting cycles with zirconium, with a maximum temperature of 2,000 degrees C, and was able to undercool by 340 degrees -- the highest temperature and largest undercooling ever achieved in space. The TEMPUS investigators also have provided the first measurements of viscosity of palladium-silicon alloys in the undercooled liquid alloy which are not possible on Earth. TEMPUS (stands for Tiegelfreies Elektromagnetisches Prozessiere unter Schwerelosigkeit (containerless electromagnetic processing under weightlessness). It was developed by the German Space Agency (DARA) for flight aboard Spacelab. The DARA project scientist was Igon Egry. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). DARA and NASA are exploring the possibility of flying an advanced version of TEMPUS on the International Space Station.(176KB JPEG, 1350 x 1516 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at

  4. In-Situ Biological Decontamination of an Ice Melting Probe

    Digel, Ilya

    A major concern in space and even many terrestrial missions is the forward contamination of the alien environment with microbes and biological molecules, transported on spacecraft from Earth. Furthermore, organisms and molecules can be brought to the sampling place from the surface. All this can lead to serious misinterpretations of the obtained data and more impor-tantly, could irreversibly alter the pristine nature of the extraterrestrial environments. These issues were addressed and are constantly updated in COSPAR planetary protection policy (20 October 2002; Amended 24 March 2005; 20 July 2008). The objective of our study was to investigate the efficacy of different in-situ decontamination protocols in the conditions of thermo-mechanical ice-melting. We evaluated survival rate of microorganisms on the melting probe as a function of both time and penetration depth. Special focus was made on deter-mination of the optimal concentration of chemical decontaminants (hydrogen peroxide and sodium hypochlorite) the peculiarities of their antimicrobial action at low temperatures (-80 to 0C) combined with constant dilution with melted ice and mechanical abrasion. Common, non-pathogenic microbial strains belonging to different morphological and metabolic groups (Pseudomonas, Micrococcus, Escherichia, Bacillus and others) were chosen as test objects for this study. The working part of the melting probe was first controllably contaminated by in-cubation in suspension of microbial cells. After appropriate sedimentation of microbial cells had been reached, the drilling-melting process was started using specially prepared sterile ice blocks. Every 2 minutes the samples were taken and analyzed. In the control tests, 1 mL of distilled water was injected into the penetration site at the onset of drilling. In the other tests, 1 mL of hydrogen peroxide (30Collected data suggest high efficacy of both used compounds in respect of all tested microbial groups. Typically, 99.9

  5. Determination of the heavy rare earth radionuclides in melted rock

    There are some heavy rare earth radionuclides in the melted rocks, such as 160Tb, 168,170Tm, 88,91Y, 174,177Lu, 169Yb, etc.. Because their contents are very low in the melted rocks and the light rare earth fission products are interfered with their determination, it is very complicated to measure them quantitatively. So a new method has been studied in which P507 resin is used to separate and purify the rare earths. Radioactive sources are prepared by the pieces of filter paper for determining chemical yield with X-fluorescence analysis, and radioactive activity is determined with the γ-spectra analysis. It is proved that this method has satisfied the demands of experiments

  6. Volcanic ash melting under conditions relevant to ash turbine interactions.

    Song, Wenjia; Lavallée, Yan; Hess, Kai-Uwe; Kueppers, Ulrich; Cimarelli, Corrado; Dingwell, Donald B


    The ingestion of volcanic ash by jet engines is widely recognized as a potentially fatal hazard for aircraft operation. The high temperatures (1,200-2,000 °C) typical of jet engines exacerbate the impact of ash by provoking its melting and sticking to turbine parts. Estimation of this potential hazard is complicated by the fact that chemical composition, which affects the temperature at which volcanic ash becomes liquid, can vary widely amongst volcanoes. Here, based on experiments, we parameterize ash behaviour and develop a model to predict melting and sticking conditions for its global compositional range. The results of our experiments confirm that the common use of sand or dust proxy is wholly inadequate for the prediction of the behaviour of volcanic ash, leading to overestimates of sticking temperature and thus severe underestimates of the thermal hazard. Our model can be used to assess the deposition probability of volcanic ash in jet engines. PMID:26931824

  7. Reactive Infiltration of Silicon Melt Through Microporous Amorphous Carbon Preforms

    Sangsuwan, P.; Tewari, S. N.; Gatica, J. E.; Singh, M.; Dickerson, R.


    The kinetics of unidirectional capillary infiltration of silicon melt into microporous carbon preforms have been investigated as a function of the pore morphology and melt temperature. The infiltrated specimens showed alternating bands of dark and bright regions, which corresponded to the unreacted free carbon and free silicon regions, respectively. The decrease in the infiltration front velocity for increasing infiltration distances, is in qualitative agreement with the closed-form solution of capillarity driven fluid flow through constant cross section cylindrical pores. However, drastic changes in the thermal response and infiltration front morphologies were observed for minute differences in the preforms microstructure. This suggests the need for a dynamic percolation model that would account for the exothermic nature of the silicon-carbon chemical reaction and the associated pore closing phenomenon.

  8. Volcanic ash melting under conditions relevant to ash turbine interactions

    Song, Wenjia; Lavallée, Yan; Hess, Kai-Uwe; Kueppers, Ulrich; Cimarelli, Corrado; Dingwell, Donald B.


    The ingestion of volcanic ash by jet engines is widely recognized as a potentially fatal hazard for aircraft operation. The high temperatures (1,200-2,000 °C) typical of jet engines exacerbate the impact of ash by provoking its melting and sticking to turbine parts. Estimation of this potential hazard is complicated by the fact that chemical composition, which affects the temperature at which volcanic ash becomes liquid, can vary widely amongst volcanoes. Here, based on experiments, we parameterize ash behaviour and develop a model to predict melting and sticking conditions for its global compositional range. The results of our experiments confirm that the common use of sand or dust proxy is wholly inadequate for the prediction of the behaviour of volcanic ash, leading to overestimates of sticking temperature and thus severe underestimates of the thermal hazard. Our model can be used to assess the deposition probability of volcanic ash in jet engines.

  9. The influence of chemistry on core melt accidents

    Chemical reactions play an important role in assessing the safety of nuclear power plants. The main source of heat in the early stage of an accident is due to a chemical reaction between steam and the circonium encapsulating the nuclear fuel. The heating and melting of fuel leads to a release of fission products which rapidly condense to form particles suspended in the surrounding gas. These aerosols are the main carriers of radioactivity as they may transport active material from the reactor vessel into the reactor containment building where it is deposited. The content of fission products in the aerosol particles and their chemical form determine their interaction with water molecules. Chemical forces laed to an absorption of water in the particles which transforms them into droplets with increased mass. The particles become spherical and hence deposit more rapidly on surrounding surfaces. There is a rapid reaction between boron carbide and stainless steel in the control blades of boiling water reactors. There is only a small formation of boric acid. This leads to a smaller formation of volatile iodine compounds. But the alloying process is likely to cause melting of the control blades so the are removed from the reactor core, a process which may have negative secondary effects. It has been found that a series of materials that are present in the reactor containment are likely to participate in various chemical reactions during an accident. Among these are electric cables, motors, thermal insulation, surface coatings and sheet metal. Metallic surface coatings and sheet metal can be some of the main sources of hydrogen. Effects from chemical reactions can be more accurately predicted by the new SHMAPP code, developed within this project, combining thermal, hydraulic and chemical phenomena. (AB)

  10. Transient melting of an ESR electrode

    Kharicha, A.; Karimi-Sibaki, E.; Bohacek, J.; Wu, M.; Ludwig, A.


    Melting parameters of ESR process such as melt rate and immersion depth of electrode are of great importance. In this paper, a dynamic mesh based simulation framework is proposed to model melt rate and shape of electrode during the ESR process. Coupling interactions between turbulent flow, temperature, and electromagnetic fields are fully considered. The model is computationally efficient, and enables us to directly calculate melting parameters. Furthermore, dynamic change of electrode shape by melting can be captured. It is necessary to control the feeding velocity of electrode due to melting instabilities in the ESR process. As such, a numerical control is implemented based on the immersion depth of electrode to achieve the steady state in the simulation. Furthermore, the modeling result is evaluated against an experiment.


    C.J. Sun; H.R. Geng; Y.S. Shen; X.Y. Teng; Z.X. Yang


    The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80, alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20, alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.

  12. Snow Melting and Freezing on Older Townhouses

    Nielsen, Anker; Claesson, Johan


    The snowy winter of 2009/2010 in Scandinavia prompted many newspaper articles on icicles falling from buildings and the risk this presented for people walking below. The problem starts with snow melting on the roof due to heat loss from the building. Melt water runs down the roof and some...... of it will freeze on the overhang. The rest of the water will either run off or freeze in gutters and downpipes or turn into icicles. This paper describes use of a model for the melting and freezing of snow on roofs. Important parameters are roof length, overhang length, heat resistance of roof and overhang......, outdoor and indoor temperature, snow thickness and thermal conductivity. If the snow thickness is above a specific limit value – the snow melting limit- some of the snow will melt. Another interesting limit value is the dripping limit. All the melt water will freeze on the overhang, if the snow thickness...

  13. Structural relaxation of metallic glass forming melts


    The fragility of superheated melts, M, for 13 kinds of metallic alloys has been evaluated from the data of the dynamic viscosity above their liquidus temperatures. The authors find that the glass forming ability of metallic melts depends on the fragility of superheated melts rather than on the value of viscosity. In the present work the value of fragility is less than 1 for good glass-forming melts but more than 1 for the other melts. The variation rate of atomic coordination number with temperature indicates clearly the relaxation rate of molten structures. The fragility of superheated melts is found in good agreement with the variation rate of the atomic coordination number with temperature.

  14. Are Entangled Polymer Melts Different From Solutions?

    Huang, Qian; Mednova, Olga; Rasmussen, Henrik K.; Skov, Anne Ladegaard; Almdal, Kristoffer; Hassager, Ole


    The possible existence of a qualitative difference on extensional steady state viscosity between polymer melts and polymer solutions is still an open question. Recent experiments [1-4] showed the extensional viscosity of both polymer melts and solutions decayed as a function of strain rate with an exponent of -0.5. When the strain rate became higher than the order of inverse Rouse time, the polymer solutions showed an upturn [1, 4]. However, in the same regime for polymer melts, the experimen...

  15. Filament stretching rheometry of polymer melts

    Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz


    The Filament Stretching Rheometry (FSR) method developed by Sridhar, McKinley and coworkers for polymer solutions has been extended to be used also for polymer melts. The design of a melt-FSR will be described and differences to conventional melt elongational rheometers will be pointed out. Resul...... for LDPE up to 7 Hencky strain units show a maximum in the transient elongational viscosity followed by a steady stress. Also results for monodisperse PS fractions will be shown and discussed....

  16. Frictional melting of peridotite and seismic slip

    Del Gaudio, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Di Toro, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Han, R.; Department of Earth and Environmental Sciences, Korea University, Seoul South Korea; Hirose, T.; Kochi Institute for Core Sample Research, JAMSTEC, Kochi, Japan.; Nielsen, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Shimamoto, T.; Department of Earth and Planetary Systems Science Graduate School of Science Hiroshima University, Higashi-Hiroshima Japan; Cavallo, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia


    The evolution of the frictional strength along a fault at seismic slip rates (about 1 m/s) is a key factor controlling earthquake mechanics. At mantle depths, friction-induced melting and melt lubrication may influence earthquake slip and seismological data. We report on laboratory experiments designed to investigate dynamic fault strength and frictional melting processes in mantle rocks. We performed 20 experiments with Balmuccia peridotite in a high-velocity rotary shear appa...

  17. High-Performance Polymers Having Low Melt Viscosities

    Jensen, Brian J.


    High-performance polymers that have improved processing characteristics, and a method of making them, have been invented. One of the improved characteristics is low (relative to corresponding prior polymers) melt viscosities at given temperatures. This characteristic makes it possible to utilize such processes as resin-transfer molding and resin-film infusion and to perform autoclave processing at lower temperatures and/or pressures. Another improved characteristic is larger processing windows that is, longer times at low viscosities. Other improved characteristics include increased solubility of uncured polymer precursors that contain reactive groups, greater densities of cross-links in cured polymers, improved mechanical properties of the cured polymers, and greater resistance of the cured polymers to chemical attack. The invention is particularly applicable to poly(arylene ether)s [PAEs] and polyimides [PIs] that are useful as adhesives, matrices of composite materials, moldings, films, and coatings. PAEs and PIs synthesized according to the invention comprise mixtures of branched, linear, and star-shaped molecules. The monomers of these polymers can be capped with either reactive end groups to obtain thermosets or nonreactive end groups to obtain thermoplastics. The synthesis of a polymeric mixture according to the invention involves the use of a small amount of a trifunctional monomer. In the case of a PAE, the trifunctional monomer is a trihydroxy- containing compound for example, 1,3,5-trihydroxybenzene (THB). In the case of a PI, the trifunctional monomer is a triamine for example, triamino pyrimidine or melamine. In addition to the aforementioned trifunctional monomer, one uses the difunctional monomers of the conventional formulation of the polymer in question (see figure). In cases of nonreactive end caps, the polymeric mixtures of the invention have melt viscosities and melting temperatures lower than those of the corresponding linear polymers of equal

  18. Evolution of Shock Melt Compositions in Lunar Regoliths

    Vance, A. M.; Christoffersen, R.; Keller, L. P.; Berger, E. L.; Noble, S. K.


    Space weathering processes - driven primarily by solar wind ion and micrometeorite bombardment, are constantly changing the surface regoliths of airless bodies, such as the Moon. It is essential to study lunar soils in order to fully under-stand the processes of space weathering, and how they alter the optical reflectance spectral properties of the lunar surface relative to bedrock. Lunar agglutinates are aggregates of regolith grains fused together in a glassy matrix of shock melt produced during micrometeorite impacts into the lunar regolith. The formation of the shock melt component in agglutinates involves reduction of Fe in the target material to generate nm-scale spherules of metallic Fe (nanophase Fe0 or npFe0). The ratio of elemental Fe, in the form of npFe0, to FeO in a given bulk soil indicates its maturity, which increases with length of surface exposure as well as being typically higher in the finer-size fraction of soils. The melting and mixing process in agglutinate formation remain poorly understood. This includes incomplete knowledge regarding how the homogeneity and overall compositional trends of the agglutinate glass portions (agglutinitic glass) evolve with maturity. The aim of this study is to use sub-micrometer scale X-ray compositional mapping and image analysis to quantify the chemical homogeneity of agglutinitic glass, correlate its homogeneity to its parent soil maturity, and identify the principal chemical components contributing to the shock melt composition variations. An additional focus is to see if agglutinitic glass contains anomalously high Fe sub-micron scale compositional domains similar to those recently reported in glassy patina coatings on lunar rocks.

  19. Can compaction, caused by melt extraction and intrusion, generate tectonically effective stresses in the lithosphere?

    Wallner, Herbert; Schmeling, Harro


    Aim of our study is to deepen understanding the role of melt processes while the lithospheric evolution by means of numerical modeling. In the sense of plate tectonics, on the one hand, stresses are transferred by stiff lithospheric plates, on the other, lithosphere is deformed, broken, or modified in various ways. Melting often plays an important role but is not easy to model numerically due to all the interactions of physics, phase changes, non-linearities, time scales, petrology, heterogeneities and chemical reactions. Here we restrict on a thermo-mechanical model of visco-plastic two phase flow with partial melting. Viscosity is temperature-, stress- and depth-dependent. Freezing and melting are determined by a simplified linear binary solid solution model. The fast melt transport through and into the lithosphere, acting on a short time scale, is replaced by melt extraction and intrusion in a given emplacement level. Numerical approximation is done in 2D with Finite Differences with markers in an Eulerian formulation. A scenario of continental rifting serves for a model of lithosphere above asthenosphere under extensional conditions. An anomaly of increased temperature at the bottom produces a low fraction of melt initially in the asthenosphere. Above a porosity limit melt is extracted and leads to compaction at its origin which induces under-pressure attracting ambient melt and contracting the depleted matrix. In a higher, colder lithospheric level the emplaced melt extends the matrix, immediately freezes; an increase of enrichment and heating takes place. The dilatation of the rock matrix generates relative high compaction pressures if it's viscosity is high as in the uppermost mantle lithosphere. Local and temporary varying stresses provide deviatoric components which sometimes may be the origin of tectonic activity in nature. Divergence terms of the full compaction formulation, responsible for viscous stress, are tested and reviewed. Quality and stability

  20. Low Melt Height Solidification of Superalloys

    Montakhab, Mehdi; Bacak, Mert; Balikci, Ercan


    Effect of a reduced melt height in the directional solidification of a superalloy has been investigated by two methods: vertical Bridgman (VB) and vertical Bridgman with a submerged baffle (VBSB). The latter is a relatively new technique and provides a reduced melt height ahead of the solidifying interface. A low melt height leads to a larger primary dendrite arm spacing but a lower mushy length, melt-back transition length, and porosity. The VBSB technique yields up to 38 pct reduction in the porosity. This may improve a component's mechanical strength especially in a creep-fatigue type dynamic loading.

  1. Melt inclusions in Luna 24 soil fragments

    Roedder, W.; Weiblen, P. W.


    Optical examinations of 28 slides of Luna 24 soil fragments revealed melt inclusions in grains of olivine, plagioclase, spinel, and ilmenite as well as interstitial inclusions. In contrast with Apollo samples, the Luna 24 samples contain sulfide melt inclusions, which indicates that saturation with respect to an iron sulfide melt took place throughout much of the crystallization history, even while olivine was crystallizing. The Luna 24 silicate-melt inclusions have recorded a more extensive differentiation toward higher iron magmas than have the Apollo inclusions, but they have also recorded some inexplicably low aluminum values.

  2. Solute Redistribution in Directional Melting Process


    @@The solute redistribution in directional melting process is theoretically studied. Based on quantitative evaluations, uniform solute distribution in liquid and a quasi-steady solute distribution in solid are supposed. The discussion on the solute balance comes to a simple model for the solute redistribution in directional melting process. As an example, the variation of liquid composition during melting process of carbon steel is quantitatively evaluated using the model. Results show that the melting of an alloy starts at solidus temperature, but approaches the liquidus temperature after a very short transient process.

  3. Impact of gneissic layering and localized incipient melting upon melt flow during experimental deformation of migmatites

    Ganzhorn, A. C.; Trap, P.; Arbaret, L.; Champallier, R.; Fauconnier, J.; Labrousse, L.; Prouteau, G.


    In this study, we test experimentally the role of compositional layering as a key parameter for controlling melt flow in a natural migmatite during coaxial deformation. We performed in - situ pure-shear experiments on two natural gneisses. The first gneiss is weakly foliated with minerals homogenously distributed. The second gneiss shows a pronounced compositional layering of alternating quartz - feldspar - rich and biotite - muscovite - rich layers. Experimental conditions were selected to obtain homogeneous melt distribution in the homogeneous gneiss and heterogeneous melt distribution in the layered gneiss. Initial melt distribution is not modified by deformation in experiments on the homogeneous gneiss, implying that melting products did not migrate from their initiation sites. In contrast, melt flowed in shear zones or in inter-boudin positions during experimental deformation of the heterogeneous gneiss. These experiments attest to the strong influence of initial gneissic layering on melting pattern, melt segregation and flow during deformation of partially molten rocks.

  4. Chemistry of Impact-Generated Silicate Melt-Vapor Debris Disks

    Visscher, Channon; Fegley, Jr, Bruce


    In the giant impact theory for lunar origin, the Moon forms from material ejected by the impact into an Earth-orbiting disk. Here we report the initial results from a silicate melt-vapor equilibrium chemistry model for such impact-generated planetary debris disks. In order to simulate the chemical behavior of a two-phase (melt+vapor) disk, we calculate the temperature-dependent pressure and chemical composition of vapor in equilibrium with molten silicate from 2000 to 4000 K. We consider the ...

  5. Modelling of the controlled melt flow in a glass melting space – Its melting performance and heat losses

    Jebavá, Marcela; Dyrčíková, Petra; Němec, Lubomír


    Roč. 430, DEC 15 (2015), s. 52-63. ISSN 0022-3093 Institutional support: RVO:67985891 Keywords : glass melt flow * mathematical modelling * energy distribution * space utilizatios * melting performance Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.766, year: 2014

  6. Structure and properties of ASP2060 tool steel after laser melting and conventional heat treatment

    In this work the structure and properties of ASDP2060 steel after laser melting and conventional heat treatment is described. In order to increase the tool life the laser surface treatment is applied. The results of these investigations have in view to explain the process of crystallization after laser melting and the influence laser melting parameters on the structure and properties of ASP2060 steel. Scanning Electron Microscopy (SEM) and X-ray Energy Dispersive Spectroscopy (EDS) were used to investigate the structure and chemical composition of the surface layer. The hardness and wear resistance measurements were performed during the investigation. The laser melting resulted in chemical homogenization and refinement of the steel surface. The results of investigation show, that in the laser melted zone was achieved increase of hardness level (2-3 times higher than in the annealed matrix) and of wear resistance (4-5 times higher than in the annealed matrix). The conventional heat treatment applied after laser melting causes additional increase of hardness and wear resistance. (author)

  7. The fate of per- and polyfluoroalkyl substances within a melting snowpack of a boreal forest

    Per- and polyfluoroalkyl substances (PFAS) were measured systematically in a snowpack in northern Sweden to determine chemical behaviour during seasonal melt. Average PFAS concentrations were generally low, but displayed a wide range with median (range) concentrations of PFOA and PFOS of 66.5 pg L−1 (ND-122) and 20.5 pg L−1 (2.60–253) respectively. Average concentrations of the shorter chain, C4 and C5 perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs), were ∼10-fold higher. Differences in the PFAS concentrations and profile were observed between surface snow and deeper layers, with evidence of PFAS migration to deeper snow layers as melt progressed. Chemical loads (ng m−2) for C4−9 PFCAs decreased gradually as melt progressed, but increased for C4, C6−8 PFSAs and the longer chain C10−12 PFCAs. This enrichment in the diminishing snowpack is an unusual phenomenon that will affect PFAS elution with meltwater and subsequent entry to catchment surface waters. - Highlights: • C4 and C5 PFCAs and PFSAs were ∼10-fold higher in snow compared to PFOA and PFOS. • PFASs migrate to deeper snow layers during the melting process. • C4−8 PFCA loads decreased as melt progressed, but increased for PFSAs and C10−12 PFCA. - This study examines the fate of per- and polyfluoroalkyl substances within a melting snowpack in a remote, northern catchment

  8. Melt infiltration: an emerging technique for the preparation of novel functional nanostructured materials.

    de Jongh, Petra E; Eggenhuisen, Tamara M


    The rapidly expanding toolbox for design and preparation is a major driving force for the advances in nanomaterials science and technology. Melt infiltration originates from the field of ceramic nanomaterials and is based on the infiltration of porous matrices with the melt of an active phase or precursor. In recent years, it has become a technique for the preparation of advanced materials: nanocomposites, pore-confined nanoparticles, ordered mesoporous and nanostructured materials. Although certain restrictions apply, mostly related to the melting behavior of the infiltrate and its interaction with the matrix, this review illustrates that it is applicable to a wide range of materials, including metals, polymers, ceramics, and metal hydrides and oxides. Melt infiltration provides an alternative to classical gas-phase and solution-based preparation methods, facilitating in several cases extended control over the nanostructure of the materials. This review starts with a concise discussion on the physical and chemical principles for melt infiltration, and the practical aspects. In the second part of this contribution, specific examples are discussed of nanostructured functional materials with applications in energy storage and conversion, catalysis, and as optical and structural materials and emerging materials with interesting new physical and chemical properties. Melt infiltration is a useful preparation route for material scientists from different fields, and we hope this review may inspire the search and discovery of novel nanostructured materials. PMID:24014262

  9. Reaction of soda-lime-silica glass melt with water vapour at melting temperatures

    Vernerová, Miroslava; Kloužek, Jaroslav; Němec, Lubomír


    Roč. 416, MAY 15 (2015), s. 21-30. ISSN 0022-3093 R&D Projects: GA TA ČR TA01010844 Institutional support: RVO:67985891 Keywords : glass melt * sulfate * water vapour * bubble nucleation * melt foaming * glass melting Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.766, year: 2014

  10. The mechanisms of water diffusion in polymerized silicate melts

    Behrens, Harald; Nowak, M.


    Diffusion of water was experimentally investigated for melts of albitic (Ab) and quartz-orthoclasic (Qz29Or71, in wt %) compositions with water contents in the range of 0 to 8.5 wt % at temperatures of 1100 to 1200 °C and at pressures of 1.0 and 5.0 kbar. Apparent chemical diffusion coefficients of water ( D water) were determined from concentration-distance profiles measured by FTIR microspectroscopy. Under the same P- T condition and water content the diffusivity of water in albitic, quartz-orthoclasic and haplogranitic (Qz28Ab38 Or34, Nowak and Behrens, this issue) melts is identical within experimental error. Comparison to data published in literature indicates that anhydrous composition only has little influence on the mobility of water in polymerized melts but that the degree of polymerization has a large effect. For instance, Dwater is almost identical for haplogranitic and rhyolitic melts with 0.5-3.5 wt % water at 850 °C but it is two orders of magnitude higher in basaltic than in haplogranitic melts with 0.2-0.5 wt % water at 1300 °C. Based on the new water diffusivity data, recently published in situ near-infrared spectroscopic data (Nowak 1995; Nowak and Behrens 1995), and viscosity data (Schulze et al. 1996) for hydrous haplogranitic melts current models for water diffusion in silicate melts are critically reviewed. The NIR spectroscopy has indicated isolated OH groups, pairs of OH groups and H2O molecules as hydrous species in polymerized silicate melts. A significant contribution of isolated OH groups to the transport of water is excluded for water contents above 10 ppm by comparison of viscosity and water diffusion data and by inspection of concentration profiles from trace water diffusion. Spectroscopic measurements have indicated that the interconversion of H2O molecules and OH pairs is relatively fast in silicate glasses and melts even at low temperature and it is inferred that this reaction is an active step for migration of water. However

  11. In-situ determination of the oxidation state of iron in Fe-bearing silicate melts

    Courtial, P.; Wilke, M.; Potuzak, M.; Dingwell, D. B.


    Terrestrial lavas commonly contain up to 10 wt% of iron. Furthermore, rocks returned from the Moon indicate lunar lava containing up to 25 wt% of iron and planetary scientists estimated that the martian mantle has about 18 wt% of iron. An experimental challenge in dealing with Fe-bearing silicate melts is that the oxidation state, controlling the proportions of ferric and ferrous iron, is a function of composition, oxygen fugacity and temperature and may vary significantly. Further complications concerning iron originate from its potential to be either four-, six- or even five-fold coordinated in both valence states. Therefore, the oxidation state of iron was determined in air for various Fe-bearing silicate melts. Investigated samples were Na-disilicate (NS), one atmosphere anorthite-diopside eutectic (AD) and haplogranitic (HPG8) melts containing up to 20, 20 and 10 wt% of iron, respectively. XANES spectra at the Fe K-edge were collected for all the melts at beamline A1, HASYLAB, Hamburg, using a Si(111) 4-crystal monochromator. Spectra were collected for temperatures up to 1573 K using a Pt-Rh loop as heating device. The Fe oxidation state was determined from the centroid position of the pre-edge feature using the calibration of Wilke et al. (2004). XANES results suggest that oxidation state of iron does not change within error for NS melts with addition of Fe, while AD and HPG8 melts become more oxidised with increasing iron content. Furthermore, NS melts are well more oxidised than AD and HPG8 melts that exhibit relatively similar oxidation states for identical iron contents. The oxidation state of iron for NS melts appears to be slightly temperature-dependent within the temperature range investigated (1073-1573 K). However, this trend is stronger for AD and HPG8 melts. Assuming that glass reflects a picture of the homogeneous equilibria of the melt, the present in-situ Fe-oxidation states determined for these melts were compared to those obtained on quenched

  12. A benchmark initiative on mantle convection with melting and melt segregation

    Schmeling, Harro; Dannberg, Juliane; Dohmen, Janik; Kalousova, Klara; Maurice, Maxim; Noack, Lena; Plesa, Ana; Soucek, Ondrej; Spiegelman, Marc; Thieulot, Cedric; Tosi, Nicola; Wallner, Herbert


    In recent years a number of mantle convection models have been developed which include partial melting within the asthenosphere, estimation of melt volumes, as well as melt extraction with and without redistribution at the surface or within the lithosphere. All these approaches use various simplifying modelling assumptions whose effects on the dynamics of convection including the feedback on melting have not been explored in sufficient detail. To better assess the significance of such assumptions and to provide test cases for the modelling community we carry out a benchmark comparison. The reference model is taken from the mantle convection benchmark, cases 1a to 1c (Blankenbach et al., 1989), assuming a square box with free slip boundary conditions, the Boussinesq approximation, constant viscosity and Rayleigh numbers of 104 to 10^6. Melting is modelled using a simplified binary solid solution with linearly depth dependent solidus and liquidus temperatures, as well as a solidus temperature depending linearly on depletion. Starting from a plume free initial temperature condition (to avoid melting at the onset time) five cases are investigated: Case 1 includes melting, but without thermal or dynamic feedback on the convection flow. This case provides a total melt generation rate (qm) in a steady state. Case 2 is identical to case 1 except that latent heat is switched on. Case 3 includes batch melting, melt buoyancy (melt Rayleigh number Rm) and depletion buoyancy, but no melt percolation. Output quantities are the Nusselt number (Nu), root mean square velocity (vrms), the maximum and the total melt volume and qm approaching a statistical steady state. Case 4 includes two-phase flow, i.e. melt percolation, assuming a constant shear and bulk viscosity of the matrix and various melt retention numbers (Rt). These cases are carried out using the Compaction Boussinseq Approximation (Schmeling, 2000) or the full compaction formulation. For cases 1 - 3 very good agreement

  13. Summer Melts Immigrant Students' College Plans

    Naranjo, Melissa M.; Pang, Valerie Ooka; Alvarado, Jose Luis


    Many college-intending students find themselves dealing with the undermatch and summer melt phenomena. Undermatch refers to the situation where academically-successful high-school graduates choose not to go to any college or to go to a local community college not commensurate with their academic achievements. Summer melt describes how students may…

  14. Melt dumping in string stabilized ribbon growth

    Sachs, Emanuel M.


    A method and apparatus for stabilizing the edge positions of a ribbon drawn from a melt includes the use of wettable strings drawn in parallel up through the melt surface, the ribbon being grown between the strings. A furnace and various features of the crucible used therein permit continuous automatic growth of flat ribbons without close temperature control or the need for visual inspection.

  15. Are Entangled Polymer Melts Different From Solutions?

    Huang, Qian; Mednova, Olga; Rasmussen, Henrik K.; Skov, Anne Ladegaard; Almdal, Kristoffer; Hassager, Ole

    The possible existence of a qualitative difference on extensional steady state viscosity between polymer melts and polymer solutions is still an open question. Recent experiments [1-4] showed the extensional viscosity of both polymer melts and solutions decayed as a function of strain rate with a...

  16. Application of Markov Chain Monte Carlo Method to Mantle Melting: An Example from REE Abundances in Abyssal Peridotites

    LIU, B.; Liang, Y.


    Markov chain Monte Carlo (MCMC) simulation is a powerful statistical method in solving inverse problems that arise from a wide range of applications, such as nuclear physics, computational biology, financial engineering, among others. In Earth sciences applications of MCMC are primarily in the field of geophysics [1]. The purpose of this study is to introduce MCMC to geochemical inverse problems related to trace element fractionation during concurrent melting, melt transport and melt-rock reaction in the mantle. MCMC method has several advantages over linearized least squares methods in inverting trace element patterns in basalts and mantle rocks. First, MCMC can handle equations that have no explicit analytical solutions which are required by linearized least squares methods for gradient calculation. Second, MCMC converges to global minimum while linearized least squares methods may be stuck at a local minimum or converge slowly due to nonlinearity. Furthermore, MCMC can provide insight into uncertainties of model parameters with non-normal trade-off. We use MCMC to invert for extent of melting, amount of trapped melt, and extent of chemical disequilibrium between the melt and residual solid from REE data in abyssal peridotites from Central Indian Ridge and Mid-Atlantic Ridge. In the first step, we conduct forward calculation of REE evolution with melting models in a reasonable model space. We then build up a chain of melting models according to Metropolis-Hastings algorithm to represent the probability of specific model. We show that chemical disequilibrium is likely to play an important role in fractionating LREE in residual peridotites. In the future, MCMC will be applied to more realistic but also more complicated melting models in which partition coefficients, diffusion coefficients, as well as melting and melt suction rates vary as functions of temperature, pressure and mineral compositions. [1]. Sambridge & Mosegarrd [2002] Rev. Geophys.

  17. Development of induction skull melting technology

    BARC had developed and indigenized cold crucible induction melter technology for high temperature glass melting applications. In order to extend this technology for metal melting applications, development of Induction Skull Melting was undertaken. As a part of the indigenous development of the ISM technology, a systematic numerical simulation was carried out initially to arrive at the design parameters of the segmented crucible. Based on the model-based design, an induction skull melting facility comprising of a water-cooled segmented copper crucible with in-situ casting module, induction heating power supply system, cooling water recirculation systems, vacuum chamber with vacuum delivery system and associated instrumentation and control units was built. The ISM facility was successfully tested for melting and homogenizing different metals and alloys. The ISM technology is the most preferred technology when highly refractory and extremely reactive metals and their alloys are to be processed with ultra high purity. (author)

  18. The contribution of glacier melt to streamflow

    Schaner, Neil; Voisin, Nathalie; Nijssen, Bart; Lettenmaier, D. P.


    Ongoing and projected future changes in glacier extent and water storage globally have lead to concerns about the implications for water supplies. However, the current magnitude of glacier contributions to river runoff is not well known, nor is the population at risk to future glacier changes. We estimate an upper bound on glacier melt contribution to seasonal streamflow by computing the energy balance of glaciers globally. Melt water quantities are computed as a fraction of total streamflow simulated using a hydrology model and the melt fraction is tracked down the stream network. In general, our estimates of the glacier melt contribution to streamflow are lower than previously published values. Nonetheless, we find that globally an estimated 225 (36) million people live in river basins where maximum seasonal glacier melt contributes at least 10% (25%) of streamflow, mostly in the High Asia region.

  19. Nanotexturing of surfaces to reduce melting point.

    Garcia, Ernest J.; Zubia, David (University of Texas at El Paso El Paso, TX); Mireles, Jose (Universidad Aut%C3%94onoma de Ciudad Ju%C3%94arez Ciudad Ju%C3%94arez, Mexico); Marquez, Noel (University of Texas at El Paso El Paso, TX); Quinones, Stella (University of Texas at El Paso El Paso, TX)


    This investigation examined the use of nano-patterned structures on Silicon-on-Insulator (SOI) material to reduce the bulk material melting point (1414 C). It has been found that sharp-tipped and other similar structures have a propensity to move to the lower energy states of spherical structures and as a result exhibit lower melting points than the bulk material. Such a reduction of the melting point would offer a number of interesting opportunities for bonding in microsystems packaging applications. Nano patterning process capabilities were developed to create the required structures for the investigation. One of the technical challenges of the project was understanding and creating the specialized conditions required to observe the melting and reshaping phenomena. Through systematic experimentation and review of the literature these conditions were determined and used to conduct phase change experiments. Melting temperatures as low as 1030 C were observed.


    SHI Guanyi; YUE Junshi


    The nature of the transition in molten FEP copolymer was examined in relation to the enthalpy change, mechanical damping and melt viscosity. For a pre-heat-treated FEP copolymer sample a small endothermic peak appeared at 309-312 ℃ in DSC trace with enthalpy change 0.03-0.05cal/g. A peak was also detected in damping versus temperature curve at the same temperature range.The rheological property of FEP copolymer melt was similar to that of liquid crystal, but no birefrigence was viewed in the melt. Therefore the transition was explained as the melting of small crystallites which persist in typical copolymer beyond its melting temperature. These crystallites can act as nuclei for crystallization upon cooling.

  1. Target-projectile interaction during impact melting at Kamil Crater, Egypt

    Fazio, Agnese; D'Orazio, Massimo; Cordier, Carole; Folco, Luigi


    In small meteorite impacts, the projectile may survive through fragmentation; in addition, it may melt, and chemically and physically interact with both shocked and melted target rocks. However, the mixing/mingling between projectile and target melts is a process still not completely understood. Kamil Crater (45 m in diameter; Egypt), generated by the hypervelocity impact of the Gebel Kamil Ni-rich ataxite on sandstone target, allows to study the target-projectile interaction in a simple and fresh geological setting. We conducted a petrographic and geochemical study of macroscopic impact melt lapilli and bombs ejected from the crater, which were collected during our geophysical campaign in February 2010. Two types of glasses constitute the impact melt lapilli and bombs: a white glass and a dark glass. The white glass is mostly made of SiO2 and it is devoid of inclusions. Its negligible Ni and Co contents suggest derivation from the target rocks without interaction with the projectile (compression stage and the excavation stage, projectile and target liquids formed at their interface and chemically interact in a restricted zone. Projectile contamination affected only a shallow portion of the target rocks. The SiO2 melt that eventually solidified as white glass behaved as an immiscible liquid and did not interact with the projectile. During the excavation stage dark glass melt engulfed and coated the white glass melt, target fragments, and got stuck to iron meteorite shrapnel fragments. This model could also explain the common formation of white and dark glasses in small impact craters generated by iron bodies (e.g., Wabar).

  2. Focused ion beam structuring of low melting polymeric materials

    This thesis focuses on heating effects during focused ion beam (FIB) processing of low melting polymers. The combined approach using experiments and simulations identifies the in part massive local temperatures as a convolution between intrinsic ion-matter effects and a considerable, technically-induced heating component. While the former is invariable, the latter has been minimized by an alternative process strategy which massively improves the morphological stability and minimizes chemical damage during FIB processing, thus opening new possibilities for application on sensitive, low melting materials. The study starts with systematic experimental investigations which strongly suggested the existence of a technically-induced heating component as a consequence of classically-used serpentine or raster-like patterning strategies. Based on these results, a combined simulation approach of ion trajectories and thermal spike model calculations have been employed to get a deeper insight into spatial and temporal temperature evolution. The results were then combined with the thermodynamic behavior of polymers by means of melting and volatizing temperatures. The comparison of these simulationbased predictions with real FIB experiments revealed very good agreement, proving the applicability of the approach used to describe the temperature evolution from a fundamental point of view. As a next step, these simulations were then applied to the dierent scanning strategies which further con rmed the existence of a technically-induced heating component via classically-used patterning approaches. Due to the deep insight gained via simulations, an alternative patterning strategy was developed, which was expected to minimize these avoidable influences. This new strategy was then evaluated using a multi-technique approach, which revealed strongly reduced chemical damage together with increasing morphological stabilities even for temperature-sensitive polymers. Finally, this alternative


    V. Yu. Stetsenko


    Full Text Available It is shown that melting and molding of hypoeutectic silumin are difficult physical and chemical nanostructural processes. In them the major role is played by the centers of crystallization of primary dendrites of aluminum, aluminum nanocrystals, the dissolved and adsorbed hydrogen. The role of the modifying crystals of an intermetallid of TiAl3 is reduced to absorption of the dissolved hydrogen and an intensification of process of a koalestsention of nanocrystals of aluminum in the centers of crystallization of primary dendrites of aluminum.

  4. Water storage and early hydrous melting of the Martian mantle

    Pommier, A.; Grove, T. L.; Charlier, Bernard


    We report an experimental investigation of the near-solidus phase equilibria of a water-saturated analog of the Martian mantle. Experiments were performed at low temperatures (700-920°C) and high pressure (4-7GPa) using multi-anvil apparatus and piston cylinder device (4GPa). The results of this study are used to explore the role of water during early melting and chemical differentiation of Mars, and to further our understanding of the near-solidus behavior in planetary mantle compositions at...

  5. Properties of niobium coatings electrodeposited from fluoride melts

    Certain properties (chemical purity, continuity, surface roughness, ultimate strength, specific electric resistance) of niobium coatings produced by means of (Li-Na-K)Feut - K2NbF7 melt electrolysis, depending on deposition conditions, have been studied. It is shown that the coatings have a high continuity, their thickness being in excess of 5 μm. Interrelation between roughness parameters and conditions of the coating production has been considered. Influence of electrolysis conditions on mechanical and electric properties of the coatings has been ascertained. 23 refs., 7 figs

  6. Volatile diffusion in silicate melts and its effects on melt inclusions

    P. Scarlato


    Full Text Available A compendium of diffusion measurements and their Arrhenius equations for water, carbon dioxide, sulfur, fluorine, and chlorine in silicate melts similar in composition to natural igneous rocks is presented. Water diffusion in silicic melts is well studied and understood, however little data exists for melts of intermediate to basic compositions. The data demonstrate that both the water concentration and the anhydrous melt composition affect the diffusion coefficient of water. Carbon dioxide diffusion appears only weakly dependent, at most, on the volatilefree melt composition and no effect of carbon dioxide concentration has been observed, although few experiments have been performed. Based upon one study, the addition of water to rhyolitic melts increases carbon dioxide diffusion by orders of magnitude to values similar to that of 6 wt% water. Sulfur diffusion in intermediate to silicic melts depends upon the anhydrous melt composition and the water concentration. In water-bearing silicic melts sulfur diffuses 2 to 3 orders of magnitude slower than water. Chlorine diffusion is affected by both water concentration and anhydrous melt composition; its values are typically between those of water and sulfur. Information on fluorine diffusion is rare, but the volatile-free melt composition exerts a strong control on its diffusion. At the present time the diffusion of water, carbon dioxide, sulfur and chlorine can be estimated in silicic melts at magmatic temperatures. The diffusion of water and carbon dioxide in basic to intermediate melts is only known at a limited set of temperatures and compositions. The diffusion data for rhyolitic melts at 800°C together with a standard model for the enrichment of incompatible elements in front of growing crystals demonstrate that rapid crystal growth, greater than 10-10 ms-1, can significantly increase the volatile concentrations at the crystal-melt interface and that any of that melt trapped

  7. Melt Rate Improvement for DWPF MB3: Melt Rate Furnace Testing

    Stone, M.E.


    The Defense Waste Processing Facility (DWPF) would like to increase its canister production rate. The goal of this study is to improve the melt rate in DWPF specifically for Macrobatch 3. However, the knowledge gained may result in improved melting efficiencies translating to future DWPF macrobatches and in higher throughput for other Department of Energy's (DOE) melters. Increased melting efficiencies decrease overall operational costs by reducing the immobilization campaign time for a particular waste stream. For melt rate limited systems, a small increase in melting efficiency translates into significant hard dollar savings by reducing life cycle operational costs.

  8. Slab melting as a barrier to deep carbon subduction

    Thomson, Andrew R.; Walter, Michael J.; Kohn, Simon C.; Brooker, Richard A.


    Interactions between crustal and mantle reservoirs dominate the surface inventory of volatile elements over geological time, moderating atmospheric composition and maintaining a life-supporting planet. While volcanoes expel volatile components into surface reservoirs, subduction of oceanic crust is responsible for replenishment of mantle reservoirs. Many natural, ‘superdeep’ diamonds originating in the deep upper mantle and transition zone host mineral inclusions, indicating an affinity to subducted oceanic crust. Here we show that the majority of slab geotherms will intersect a deep depression along the melting curve of carbonated oceanic crust at depths of approximately 300 to 700 kilometres, creating a barrier to direct carbonate recycling into the deep mantle. Low-degree partial melts are alkaline carbonatites that are highly reactive with reduced ambient mantle, producing diamond. Many inclusions in superdeep diamonds are best explained by carbonate melt-peridotite reaction. A deep carbon barrier may dominate the recycling of carbon in the mantle and contribute to chemical and isotopic heterogeneity of the mantle reservoir.

  9. Mixing Silicate Melts with High Viscosity Contrast by Chaotic Dynamics: Results from a New Experimental Device

    de Campos, Cristina; Perugini, Diego; Ertel-Ingrisch, Werner; Dingwell, Donald B.; Poli, Giampiero


    A new experimental device has been developed to perform chaotic mixing between high viscosity melts under controlled fluid-dynamic conditions. The apparatus is based on the Journal Bearing System (JBS). It consists of an outer cylinder hosting the melts of interest and an inner cylinder, which is eccentrically located. Both cylinders can be independently moved to generate chaotic streamlines in the mixing system. Two experiments were performed using as end-members different proportions of a peralkaline haplogranite and a mafic melt, corresponding to the 1 atm eutectic composition in the An-Di binary system. The two melts were stirred together in the JBS for ca. two hours, at 1,400° C and under laminar fluid dynamic condition (Re of the order of 10-7). The viscosity ratio between the two melts, at the beginning of the experiment, was of the order of 103. Optical analyses of experimental samples revealed, at short length scale (of the order of μm), a complex pattern of mixed structures. These consisted of an intimate distribution of filaments; a complex inter-fingering of the two melts. Such features are typically observed in rocks thought to be produced by magma mixing processes. Stretching and folding dynamics between the melts induced chaotic flow fields and generated wide compositional interfaces. In this way, chemical diffusion processes become more efficient, producing melts with highly heterogeneous compositions. A remarkable modulation of compositional fields has been obtained by performing short time-scale experiments and using melts with a high viscosity ratio. This indicates that chaotic mixing of magmas can be a very efficient process in modulating compositional variability in igneous systems, especially under high viscosity ratios and laminar fluid-dynamic regimes. Our experimental device may replicate magma mixing features, observed in natural rocks, and therefore open new frontiers in the study of this important petrologic and volcanological process.

  10. In situ multi-element analysis of the Mount Pinatubo quartz-hosted melt inclusions by NIR femtosecond laser ablation-inductively coupled plasma-mass spectrometry

    A. Y. Borisova; Freydier, R.; Polvé, Mireille; Salvi, S; F. Candaudap; Aigouy, T.


    Microscopic melt inclusions found in magmatic minerals are undoubtedly one of the most important sources of information on the chemical composition of melts. This paper reports on the successful application of near-infrared (NIR) femtosecond laser ablation (LA) - inductively coupled plasma-mass spectrometry to in situ determination of incompatible trace elements (Li, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Ta, Th, U) and ore metals (As, Mo, Pb) in individual melt inclusions hosted in quartz from the ...

  11. The investigation of microstructures and properties of SWV9 high speed tool steel after laser melting

    The article presents the results of an investigation of changes in microstructure, hardness, phase and chemical composition, of the CO2 laser-melted high-speed tool steel namely SWV9. Formation of structure under rapid solidification condition is described. Microstructural and compositional analysis considered of optical, SEM, TEM, X-ray diffraction analysis and the sliding wear investigations. Microhardness was determined using a Hanemann microhardness tester. The microstructure formed under rapid solidification conditions after laser melting of SWV9 steel shows high chemical homogeneity and is extremely refined. Structure obtained in the surface layer after laser melting permitted to get high level of hardness (about 1200 HV65) and improved wear resistance. (author)

  12. Melting and boiling of clusters

    Clusters properties depends on their size, the transition from the atom / molecule to the bulk is often smooth and the asymptotic behaviour well understood, but for cluster melting is not the case, where irregular fluctuations are found even for clusters containing more than hundred atoms. A method to measure caloric curves for size selected cluster ions is provided. A plot of the cluster energy as a function of cluster temperature gives the caloric curve and contains all its basic thermodynamic properties. The method consists of two steps: in the first, sodium clusters ions are produced and thermalized. The heat bath was a helium gas of known temperature T, where clusters make so many collisions that they reach thermal equilibrium. Then, the thermalized clusters are extracted, transferred to high vacuum, and mass analysed. In the second step, the internal dominantly vibrational energy E of the cluster is measured by a photofragmentation technique, knowing E and T, the caloric curve E= E(T) can be plotted. As an example the Na 139+ and Na+n study is presented. (nevyjel)

  13. Olivine flotation in mantle melt

    Agee, Carl B.; Walker, David


    Molten komatiite and peridotite have been compressed in an octahedral multi-anvil device up to 10 GPa. Densities of the melts were measured at pressure intervals in the range 7 to 10 GPa by observing sinking and floating San Carlos olivines and synthetic forsterite marker spheres. The multi-anvil results for komatiite, when combined with piston-cylinder measurements done at 4 to 6 GPa and a calculated reference density at 10 5 Pa, yield a Birch-Murnaghan isothermal bulk modulus of (K 1900C) = 26 GPa and pressure derivative K' = 4.25. The pressure of neutral buoyancy for olivine in komatiite is confirmed to be near 8 GPa as predicted in earlier work. Olivine flotation in the experimental komatiite commences at a pressure close to where the liquidus phase changes from olivine to denser garnet, leading to the possibility of density driven crystal sorting during fractionation. Molten peridotite (KLB-1) shows an isothermal compression (2000°C) of 0.065 g cm -3 GPa -1 in the interval 10 5 Pa to 8.2 GPa. The olivine/liquid peridotite density crossover is predicted to lie between 9 and 11 GPa, indicating that olivine flotation can operate at depths of 300-500 km in a molten peridotitic mantle.

  14. Beta experiments on zirconium oxidation and aerosol release during melt-concrete interaction

    Three experiments on melt-concrete interaction have been carried out in the BETA facility to investigate the zirconium oxidation processes during concrete attack and their influence on concrete erosion and aerosol release. The results clearly show the dominance of the condensed phase chemistry, that is the chemical reaction of Zr and SiO2 leading to the rapid oxidation of 80 kg of Zr and the formation of Si in the metallic melt within a few minutes only. The high chemical energy release from this reaction produces fast concrete erosion and a pronounced gas spike dominated by hydrogen release. After the completion of Zr oxidation the erosion is determined by the much lower internal decay heat level with moderate interaction processes. The temperature of the melt is measured to decrease very fast to the freezing temperature which can be explained by the very effective heat removal to the melting concrete. The overall downward erosion of 40 to 50 cm of the concrete crucible produces characteristic 2-dimensional cavity shapes. Aerosol release including simulated fission product behavior is reported with respect to aerosol rates, chemical composition, and characteristic particle size. In conclusion: The three tests investigated the interaction of predominantly metallic melts of high initial Zr concentration with siliceous concrete in a cylindrical crucible. They give clear and consistent data on Zr oxidation and related processes which may be summarized as follows: - Oxidation of 80 kg Zry-4 in 300 kg metallic melt dominates the interaction during the first 2 or 3 minutes. Material investigation shows the depletion of Zr within only 1 minute and a simultaneous increase of Si concentration in the metallic melt as described by the condensed phase chemical reaction Zr + SiO2 ZrO2 + Si. - In spite of the high energy deposition from Zr oxidation and from electric heating the temperature of the metal in all three BETA tests drops to its freezing temperature within some 150 s

  15. Distribution of radionuclides during melting of carbon steel

    Thurber, W.C.; MacKinney, J.


    During the melting of steel with radioactive contamination, radionuclides may be distributed among the metal product, the home scrap, the slag, the furnace lining and the off-gas collection system. In addition, some radionuclides will pass through the furnace system and vent to the atmosphere. To estimate radiological impacts of recycling radioactive scrap steel, it is essential to understand how radionuclides are distributed within the furnace system. For example, an isotope of a gaseous element (e.g., radon) will exhaust directly from the furnace system into the atmosphere while a relatively non-volatile element (e.g., manganese) can be distributed among all the other possible media. This distribution of radioactive contaminants is a complex process that can be influenced by numerous chemical and physical factors, including composition of the steel bath, chemistry of the slag, vapor pressure of the particular element of interest, solubility of the element in molten iron, density of the oxide(s), steel melting temperature and melting practice (e.g., furnace type and size, melting time, method of carbon adjustment and method of alloy additions). This paper discusses the distribution of various elements with particular reference to electric arc furnace steelmaking. The first two sections consider the calculation of partition ratios for elements between metal and slag based on thermodynamic considerations. The third section presents laboratory and production measurements of the distribution of various elements among slag, metal, and the off-gas collection system; and the final section provides recommendations for the assumed distribution of each element of interest.

  16. Alkali aluminosilicate melts and glasses: structuring at the middle range order of amorphous matter

    Le Losq, C.; neuville, D. R.


    Rheological properties of silicate melts govern both magma ascension from the mantle to the surface of the earth and volcanological eruptions styles and behaviours. It is well known that several parameters impact strongly these properties, such as for instance the temperature, pressure, chemical composition and volatiles concentration, finally influencing eruptive behaviour of volcanoes. In this work, we will focus on the Na2O-K2O-Al2O3-SiO2 system, which is of a prime importance because it deals with a non-negligible part of natural melts, like for instance the Vesuvius (Italy) or Erebus (Antartica) magmas. In an oncoming paper in Chemical Geology (Le Losq and Neuville, 2012), we have communicated results of the study of mixing Na-K in tectosilicate melts containing a high concentration of silica (≥75mol%). In the present communication, we will enlarge this first point of view to tectosilicate melts presenting a lower silica concentration. We will first present our viscosity data, and then the Adam and Gibbs theory that allows theoretically modelling Na-K mixing in aluminosilicate melts by using the so-called "mixed alkali effect". On the basis of the rheological results, the Na-K mixing cannot be explained with the ideal "mixed alkali effect", which involves random exchange of Na-K cationic pairs. To go further and as rheological properties are directly linked with structural properties, we will present our first results obtained by Raman and NMR spectroscopy. These last ones provide important structural pieces of information on the polymerization state of glasses and melts, and also on the environment of tetrahedrally coordinated cations. Rheological and structural results all highlight that Na and K are not randomly distributed in aluminosilicate glasses and melts networks. Na melts present a network with some channels and a non-random distribution of Al and Si. K networks are different. They also present a non-random distribution of Al and Si, but in two sub

  17. Heat content of liquid Fe-Cu-Si alloys formed in the melting treatment process of domestic waste incineration residue

    Some new melting processes for the ash have been developed to solve the problems on increasing volume of ash generated from municipal waste incinerators. The metal phase formed in this melting process generally consists of Fe-Cu-Si-P-C containing a small amount of other heavy metals, but their phase equilibria and physico-chemical properties are unknown. The present work aimed at determining the thermochemical properties of liquid Fe-Cu-Si alloys, which establish the basic system in this melting process. The heat contents of liquid Fe, Fe-Cu and Fe-Cu-Si alloys have been directly measured with a drop calorimeter at mainly 2073 K in the present work. The observed heat content and the enthalpy of mixing of the alloys were assessed by a thermodynamic model. The input energy which should be supplied to melt the metal phase in the new melting treatment process was also discussed. (orig.)

  18. Heat content of liquid Fe-Cu-Si alloys formed in the melting treatment process of domestic waste incineration residue

    Washizu, T. [Nippon Steel Corp., Ohita (Japan). Ohita Works; Nagasaka, T.; Hino, M. [Tohoku Univ., Sendai (Japan). Dept. of Metallurgy


    Some new melting processes for the ash have been developed to solve the problems on increasing volume of ash generated from municipal waste incinerators. The metal phase formed in this melting process generally consists of Fe-Cu-Si-P-C containing a small amount of other heavy metals, but their phase equilibria and physico-chemical properties are unknown. The present work aimed at determining the thermochemical properties of liquid Fe-Cu-Si alloys, which establish the basic system in this melting process. The heat contents of liquid Fe, Fe-Cu and Fe-Cu-Si alloys have been directly measured with a drop calorimeter at mainly 2073 K in the present work. The observed heat content and the enthalpy of mixing of the alloys were assessed by a thermodynamic model. The input energy which should be supplied to melt the metal phase in the new melting treatment process was also discussed. (orig.)

  19. Melt processed high-temperature superconductors


    The achievement of large critical currents is critical to the applications of high-temperature superconductors. Recent developments have shown that melt processing is suitable for producing high J c oxide superconductors. Using magnetic forces between such high J c oxide superconductors and magnets, a person could be levitated.This book has grown largely out of research works on melt processing of high-temperature superconductors conducted at ISTEC Superconductivity Research Laboratory. The chapters build on melt processing, microstructural characterization, fundamentals of flux pinning, criti

  20. Structure of aluminum-iron melts

    Khomutova, Z.V.; Slukhovskii, O.I.; Romanova, A.V.


    Aluminum-based melts with compositions close to those of intermetallic compounds (Al3Fe, Al5Fe2, and AlFe) and eutectics with atomic Fe concentrations of 0.9 and 8.0 percent are investigated experimentally using X-ray diffraction analysis. The concentration and temperature dependences of the electrical resistivity of these melts are determined for temperatures up to 1700 C. Calculations of the electrical resistance are then made on the basis of a microinhomogeneous structural model of the melts. 9 references.

  1. Pb isotopes during mingling and melting

    Waight, Tod Earle; Lesher, Charles E.


    Pb isotopic data are presented for hybrid rocks formed by mingling between mantle-derived tholeiitic magma of the Eocene Miki Fjord macrodike (East Greenland) and melt derived from the adjacent Precambrian basement. Bulk mixing and AFC processes between end-members readily identified in the field...... grain boundaries during disequilibrium melting of the host rock by the mafic magma. The crustal melt involved in magma interactions was therefore heterogeneous with respect to Pb isotopes on a metre-scale. These results illustrate the difficulties inherent in interpreting isotopic variations...

  2. Analysis of Turf Fungicides in Snow Melt Runoff by LC/MS

    Fungicides are applied on turf grass, in autumn, to control snow mold in the north-central United States. Fungicides of varying chemical classes have been detected in snow melt runoff from turf. A multi-residue method for simultaneous sample extraction and analysis is needed to process a large quant...

  3. Silicate melt inclusions in clinopyroxene phenocrysts from mafic dikes in the eastern North China Craton: Constraints on melt evolution

    Cai, Ya-Chun; Fan, Hong-Rui; Santosh, M.; Hu, Fang-Fang; Yang, Kui-Feng; Liu, Xuan; Liu, Yongsheng


    Silicate melt inclusions (SMIs) in magmatic minerals provide key information on the chemical and mineralogical evolution of source magmas. The widespread Cretaceous mafic dikes in the Jiaojia region of the eastern North China Craton contain abundant SMIs within clinopyroxene phenocrysts. The daughter minerals in these SMIs include amphibole, plagioclase, pyrite and ilmenite, together with CO2 + CH4 and CH4 as the major volatile phase. The total homogenization temperatures of the SMIs range between 1280 and 1300 °C. The host clinopyroxene phenocrysts in these dolerite dikes are dominantly augite with minor diopside. From LA-ICPMS analyses of the SMIs, we identify two compositional groups: (1) low-MgO (6.0-7.6 wt.%) SMIs and (2) high-MgO (11.2-13.9 wt.%) SMIs. The Low-MgO group exhibits higher concentrations of TiO2, Al2O3, Na2O, P2O5 and lower CaO and CaO/Al2O3 ratio as compared to the high-MgO SMIs. The trace element patterns of the two types of SMIs are similar to those of the host mafic dikes. However, the low-MgO SMIs and host mafic dikes are clearly more enriched in all the trace elements as compared to the high-MgO type, especially with regard to the highly incompatible elements. The estimated capture temperatures and pressures are 1351-1400 °C and 1.6-2.1 GPa for the high-MgO SMIs and 1177-1215 °C and 0.6-1.1GPa for the low-MgO type. The high-MgO and low-MgO SMIs were trapped at depths of ∼51-68 km and ∼20-35 km, respectively. Computations show that the parental melt is mafic with SiO2 content 49.6 wt% and Mg# 80.0 with relatively low total alkali contents (1.35 wt% Na2O + K2O) and high CaO (15.2 wt%). Exploratory runs with the program MELTS and pMELTS show that the low-MgO and high-MgO SMIs were derived from the same parental melt through different degrees of crystallization. Clinopyroxene and a small amount of olivine were the fractionating phases during the evolution from parental melts to high MgO melts, while the low MgO melts experienced

  4. An experimental investigation on diffusion of water in haplogranitic melts

    Nowak, M.; Behrens, Harald


    The diffusivity of water has been investigated for a haplogranitic melt of anhydrous composition Qz28Ab38Or34 (in wt %) at temperatures of 800-1200°C and at pressures of 0.5-5.0 kbar using the diffusion couple technique. Water contents of the starting glass pairs varied between 0 and 9 wt %. Concentration-distance profiles for the different water species (molecular water and hydroxyl groups) were determined by near-infrared microspectroscopy. Because the water speciation of the melt is not quenchable (Nowak 1995; Nowak and Behrens 1995; Shen and Keppler 1995), the diffusivities of the individual species can not be evaluated directly from these profiles. Therefore, apparent chemical diffusion coefficients of water ( D water) were determined from the total water profiles using a modified Boltzmann-Matano analysis. The diffusivity of water increases linearly with water content P (in kbar) by in the ranges 1073 K ≤ T ≤ 1473 K; 0.5 kbar ≤ P≤ 5␣kbar; 0.5 wt % ≤ C water ≤ 6 wt %. The absence of alkali concentration gradients in the glasses after the experiments shows that interdiffusion of alkali and H+ or H3O+ gives no contribution to the transport of water in aluminosilicate melts. The H/D interdiffusion coefficients obtained at 800°C and 5 kbar using glass pieces with almost the same molar content of either water or deuterium oxide are almost identical to the chemical diffusivities of water. This indicates that protons are transported by the neutral component H2O under these conditions.

  5. Interaction mechanism between niobium-silicide-based alloy melt and Y2O3 refractory crucible in vacuum induction melting process

    Gao Ming


    Full Text Available The Y2O3 crucibles were introduced in the study as an alternative to the traditional ceramic ones in vacuum induction melting of multi-component Nb-16Si-22Ti-2Al-2Hf-17Cr (at.% alloys, to reveal the possible interactions between the alloy melt and the refractory crucible. Multiple melting time lengths and two cooling schemes were designed and used for the experiments. The chemical composition and microstructure of the tested alloy and the melt-crucible interaction were investigated and evaluated. In the experiments, Y2O3 crucible displays good physical-chemical compatibility. The results indicate that the increment of O element in the as-cast ingot is 0.03at.%-0.04at.% (72-97 ppm and the increment of Y element is very insignificant. The key features of the alloy melt interacting with Y2O3 ceramics are analyzed and concluded in the paper. As a result of the dissolution reaction xY2O3 (in molten alloy + (1-xHfO2 (impurity →Hf1-xY2xO2-x, a continuous double-layer solid film consisted of HfO2 solid solution (~2 μm and pure HfO2 (~5 μm is formed on the surface of the test ingot after cooled down in the crucible. The experimental results show that the Y2O3 crucible is applicable to the vacuum induction melting of Nb-Si based alloys.

  6. Effect of Sulfur on Siderophile Element Partitioning Between Olivine and Martian Primary Melt

    Usui, T.; Shearer, C. K.; Righter, K.; Jones, J. H.


    Since olivine is a common early crystallizing phase in basaltic magmas that have produced planetary and asteroidal crusts, a number of experimental studies have investigated elemental partitioning between olivine and silicate melt [e.g., 1, 2, 3]. In particular, olivine/melt partition coefficients of Ni and Co (DNi and DCo) have been intensively studied because these elements are preferentially partitioned into olivine and thus provide a uniquely useful insight into the basalt petrogenesis [e.g., 4, 5]. However, none of these experimental studies are consistent with incompatible signatures of Co [e.g., 6, 7, 8] and Ni [7] in olivines from Martian meteorites. Chemical analyses of undegassed MORB samples suggest that S dissolved in silicate melts can reduce DNi up to 50 % compared to S-free experimental systems [9]. High S solubility (up to 4000 ppm) for primitive shergottite melts [10] implies that S might have significantly influenced the Ni and Co partitioning into shergottite olivines. This study conducts melting experiments on Martian magmatic conditions to investigate the effect of S on the partitioning of siderophile elements between olivine and Martian primary melt.

  7. Origins of ultralow velocity zones through slab-derived metallic melt.

    Liu, Jiachao; Li, Jie; Hrubiak, Rostislav; Smith, Jesse S


    Understanding the ultralow velocity zones (ULVZs) places constraints on the chemical composition and thermal structure of deep Earth and provides critical information on the dynamics of large-scale mantle convection, but their origin has remained enigmatic for decades. Recent studies suggest that metallic iron and carbon are produced in subducted slabs when they sink beyond a depth of 250 km. Here we show that the eutectic melting curve of the iron-carbon system crosses the current geotherm near Earth's core-mantle boundary, suggesting that dense metallic melt may form in the lowermost mantle. If concentrated into isolated patches, such melt could produce the seismically observed density and velocity features of ULVZs. Depending on the wetting behavior of the metallic melt, the resultant ULVZs may be short-lived domains that are replenished or regenerated through subduction, or long-lasting regions containing both metallic and silicate melts. Slab-derived metallic melt may produce another type of ULVZ that escapes core sequestration by reacting with the mantle to form iron-rich postbridgmanite or ferropericlase. The hypotheses connect peculiar features near Earth's core-mantle boundary to subduction of the oceanic lithosphere through the deep carbon cycle. PMID:27143719

  8. Melting relations of the Allende meteorite

    Seitz, M. G.; Kushiro, I.


    The proportions of major oxides in the Allende carbonaceous chondrite after partial reduction are remarkably similar to those in possible mantle material of the earth. When heated, the Allende meteorite generates a sulfide melt, a ferrobasaltic melt, and olivine with or without pyroxene, over a wide pressure range (5 to 25 kilobar). The silicate melt contains more sodium and less titanium than lunar ferrobasalts. An aggregate of the Allende chondrite rich in calcium and aluminum produces silica-undersaturated, calcium-rich melt and spinel over a wide pressure and temperature range. It is suggested that the earth's core contains significant amounts of both nickel and sulfur and that a 3:2 mixture of Allende bulk sample and calcium- and aluminum-rich agregates is closer in major element abundances than either of these components to the average composition of the moon.

  9. Theoretical description of laser melt pool dynamics

    Dykhne, A.


    Melting of solid matter under laser radiation is realized in almost every process of laser technology. The present paper addresses melted material flows in cases when melt zones are shallow, i.e., the zone width is appreciably greater than or of the same order as its depth. Such conditions are usually realized when hardening, doping or perforating thin plates or when using none-deep penetration. Melted material flowing under conditions of deep penetration, drilling of deep openings and cutting depends on a number of additional factors (as compared to the shallow-pool case), namely, formation of a vapor and gas cavern in the sample and propagation of the laser beam through the cavern. These extra circumstances complicate hydrodynamic consideration of the liquid bath and will be addressed is the paper to follow.

  10. Sierra Nevada snow melt from SMS-2

    Breaker, L. C.; Mcmillan, M. C.


    A film loop from SMS-2 imagery shows snow melt over the Sierra Nevadas from May 10 to July 8, 1975. The sequence indicates a successful application of geostationary satellite data for monitoring dynamic hydrologic conditions.

  11. Microwave melting of ashes from waste incineration

    A system derived from the treatment of sludges from waste water and applied to radioactive waste processing is described. Calcined wastes in a container are heated by microwaves melted, solidified in the same container and conditioned for final storage

  12. Extraction of scandium by organic substance melts

    Regularities of scandium extraction by the melts of octadecanicoic acid, n-carbonic acids of C17-C20 commerical fraction and mixtures of tributylphosphate (TBP) with paraffin at (70+-1) deg C have been studied. The optimum conditions for scandium extraction in the melt of organic substances are determined. A scheme of the extraction by the melts of higher carbonic acids at ninitial metal concentrations of 10-5 to 10-3 mol/l has been suggested. The scandium compound has been isolated in solid form, its composition having been determined. The main advantages of extraction by melts are as follows: a possibility to attain high distribution coefficients, distinct separation of phases after extraction, the absence of emulsions, elimination of employing inflammable and toxic solvents, a possibility of rapid X-ray fluorescence determinatinon of scandium directly in solid extract

  13. Principle of Melt-glue Cloth

    陈人豪; 曹建达; 李济群; 张利梅; 何洋


    This paper advances a new concept of textile-meltglue cloth, and introduces the readers to the basic principle of melt-glue cloth. On the basis of melt spinning, the spinneret can be replaced by a spinning device that consists of an outer spinneret (a loop)and an inner spinneret ( a round plate), and between them there is an interval circle on which the centers of the holes are evenly distributed. When the machine is running, the outer spinneret (or the inner one) is fixed, the inner spinneret (or the outer one)is spinning, and a columnar net will be obtained.Then it will be excided with the help of a cutter in transporting it. Finally the once-forming melt-glue cloth will be produced. Compared with the traditional woven fabric, melt-glue cloth has a lot of special features and a bright future of application.

  14. Incomplete melting of the Au(100) surface

    We study the high-temperature disordering of the reconstructed Au(100) surface by molecular dynamics simulation using a many-body interatomic potential. We find that the surface deconstructs at 0.8Tm in good agreement with experimental data, but proper surface melting does not occur close to the bulk melting point. Instead there is an in-plane disordering of the two topmost layers. The thickness of the disordered region remains constant with increasing temperature, indicating blocked, or incomplete, melting of the (100) crystalline substrate. An analysis of the structure reveals that crystalline and disordered islands coexist on two first surface layers for temperature between deconstruction and bulk melting. (author). 24 refs, 10 figs

  15. Melting behavior of mixed U-Pu oxides under oxidizing conditions

    Strach, Michal; Manara, Dario; Belin, Renaud C.; Rogez, Jacques


    In order to use mixed U-Pu oxide ceramics in present and future nuclear reactors, their physical and chemical properties need to be well determined. The behavior of stoichiometric (U,Pu)O2 compounds is relatively well understood, but the effects of oxygen stoichiometry on the fuel performance and stability are often still obscure. In the present work, a series of laser melting experiments were carried out to determine the impact of an oxidizing atmosphere, and in consequence the departure from a stoichiometric composition on the melting behavior of six mixed uranium plutonium oxides with Pu content ranging from 14 to 62 wt%. The starting materials were disks cut from sintered stoichiometric pellets. For each composition we have performed two laser melting experiments in pressurized air, each consisting of four shots of different duration and intensity. During the experiments we recorded the temperature at the surface of the sample with a pyrometer. Phase transitions were qualitatively identified with the help of a reflected blue laser. The observed phase transitions occur at a systematically lower temperature, the lower the Pu content of the studied sample. It is consistent with the fact that uranium dioxide is easily oxidized at elevated temperatures, forming chemical species rich in oxygen, which melt at a lower temperature and are more volatile. To our knowledge this campaign is a first attempt to quantitatively determine the effect of O/M on the melting temperature of MOX.

  16. Energy Saving Melting and Revert Reduction Technology (E-SMARRT): Melting Efficiency Improvement

    Principal Investigator Kent Peaslee; Co-PI’s: Von Richards, Jeffrey Smith


    Steel foundries melt recycled scrap in electric furnaces and typically consume 35-100% excess energy from the theoretical energy requirement required to pour metal castings. This excess melting energy is multiplied by yield losses during casting and finishing operations resulting in the embodied energy in a cast product typically being three to six times the theoretical energy requirement. The purpose of this research project was to study steel foundry melting operations to understand energy use and requirements for casting operations, define variations in energy consumption, determine technologies and practices that are successful in reducing melting energy and develop new melting techniques and tools to improve the energy efficiency of melting in steel foundry operations.

  17. Uniaxial Elongational viscosity of bidisperse polystyrene melts

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole


    The startup and steady uniaxial elongational viscosity have been measured for three bidisperse polystyrene (PS) melts, consisting of blends of monodisperse PS with molecular weights of 52 kg/mole or 103 kg/mole and 390 kg/mole. The bidisperse melts have a maximum in the steady elongational...... viscosity, of up to a factor of 7 times the Trouton limit of 3 times the zero-shear viscosity....

  18. Electrodepositions on Tantalum in Alkali Halide Melts

    Barner, Jens H. Von; Jensen, Annemette Hindhede; Christensen, Erik


    Surface layers of tantalum metal were electrodeposited on steel from K2TaF7-LiF-NaF-KF melts. With careful control of the oxide contents dense and adherent deposits could be obtained by pulse plating. In NaCl-KCl-NaF-Na2CO3 and NaCl-KCl-Na2CO3 melts carbonate ions seems to be reduced to carbon in...

  19. Iron melting curve with a tricritical point

    Aitta, A.


    Solidification as a first order phase transition is described in the Landau theory by the same equation as tricritical phenomena. Here, the solidification or melting temperature against pressure curve is modelled to end at a tricritical point. The model gives the phase transition temperature's dependence on pressure up to the quadratic term with a definite expression for the coefficients. This formula is expected to be generally valid for pure materials having melting curves with dT/dP approa...

  20. Pressure effect on the melting temperature

    Garai, Jozsef


    Pressure-melting temperature relationship is proposed and tested against the experiments of metals (Pt and Al), salt (NaCl), and ceramic (MgO) with positive results. The equation contains one open parameter which remains constant for the investigated substances. The constant value of the parameter indicates that the presented equation for the melting curve might be the first one which does not contain any arbitrary constant which is left open to fit to the experiments.

  1. Electrochemical behaviours of scandium in chloride melts

    Electrochemical behaviour of scandium(3) ions in an eutectic melt of NaCl-KCl-CsCl at 810-850 K is studied by cyclic voltammetry and chronoamperometry. The process of cathodic reduction of scandium complex ions in chloride melts is found to proceed according to the scheme: Sc(3) → Sc(0) and to be controlled by the rate of ScCl63- complex dissociation

  2. Vacancies in quantal Wigner crystals near melting

    We estimate the formation energy of lattice vacancies in quantal Wigner crystals of charged particles near their melting point at zero temperature, in terms of the crystalline Lindemann parameter and of the static dielectric function of the fluid phase near freezing. For both 3D and 2D crystals of electrons our results suggest the presence of vacancies in the ground state at the melting density. (author)

  3. A spectroscopic and computational study of Al(III) complexes in cryolite melts: Effect of cation nature

    Nazmutdinov, Renat R.; Zinkicheva, Tamara T.; Vassiliev, Sergey Yu.; Glukhov, Dmitrii V.; Tsirlina, Galina A.; Probst, Michael


    Lithium, sodium and potassium cryolite melts are probed by Raman spectroscopy in a wide range of the melt composition. The experimental data demonstrate a slight red shift of main peaks and a decrease of their half-widths in the row Li+, Na+, K+. Quantum chemical modelling of the systems is performed at the density functional theory level. The ionic environment is found to play a crucial role in the energy of fluoroaluminates. Potential energy surfaces describing the formation/dissociation of...

  4. Manufacturing laser glass by continuous melting

    Campbell, J H; Suratwala, T; krenitsky, S; Takeuchi, K


    A novel, continuous melting process is being used to manufacture meter-sized plates of laser glass at a rate 20-times faster, 5-times cheaper, and with 2-3 times better optical quality than with previous one-at-a-time, ''discontinuous'' technology processes. This new technology for manufacturing laser glass, which is arguably the most difficult continuously-melted optical material ever produced, comes as a result of a $60 million, six-year joint R&D program between government and industry. The glasses manufactured by the new continuous melting process are Nd-doped phosphate-based glasses and are marketed under the product names LG-770 (Schott Glass Technologies) and LHG-8 (Hoya Corporation USA). With this advance in glass manufacturing technology, it is now possible to construct high-energy, high-peak-power lasers for use in fusion energy development, national defense, and basic physics research that would have been impractical to build using the old melting technology. The development of continuously melted laser glass required technological advances that have lead to improvements in the manufacture of other optical glass products as well. For example, advances in forming, annealing, and conditioning steps of the laser glass continuous melting process are now being used in manufacture of other large-size optical glasses.

  5. Low soluble cerium compounds in salt melts

    The behaviour of cerium tungstate NaCe(WO4)2 and cerium phosphate Na3Ce2(PO4)3 in high-temperature salt melts has been investigated. The solubility in the NaCe(WO4)2-NaWO4-NaCl(1) and Na3Ce2(PO4)3-Na2WO4-NaCl(2) systems at 700-800 deg C has been studied. It is shown, that with the increase of the Na2WO4 part in systems (1), (2) the solubility increases in the following way: for NaCe(WO4)2 from 1.3x10-3 m in NaCl melt to 4.9x10-3 m in NaWO4 melt, for Na3Ce2(PO4)3 from 0.4x10-3 m in NaCl melt to 5.7x10-3 m in NaWO4 melt. With an increase in the Na2WO4 part in system (2) the formation of a new phase - NaCe(WO4)2 is observed. The melting enthalpy of NaCe(WO4)2 is 19+-3 kJ/mol

  6. Analyses of the melt cooling rate in the melt-spinning process

    B. Karpe


    Full Text Available Purpose: Rapid solidification (RS of metallic melts is important for the development of the advance metallic materials, because enables the production of new alloys with superior properties according to conventionally treated alloys. In practice it turned out, that single roll melt spinning process has one of the highest melt cooling rates among all continuous casting processes. But, because very short solidification time and movement of the melt and substrate, melt cooling rate is very difficult to measure with confidence. Primary goal of our work was to determine the limits of cooling rate over the ribbon thickness and to outline, which property or typical feature of the process has the greatest influence on cooling rate of the melt. Design/methodology/approach: On the basis of developed mathematical model, a computer program was made and used for melt cooling rate calculation in the melt-spinning process.Findings: The calculations show that distance from the contact surface in relation to the thermal properties of the melt, chilling wheel material and contact resistance between metal melt and chilling wheel have the greatest influence on melt/ribbon cooling rate. In the case of continuous casting, significant “long term” surface temperature increase may take place, if the wheel is not internally cooled.Research limitations/implications: Influence of the melt physical properties, chill wheel material, contact resistance and cooling mode of the chill wheel on melt cooling rate are outlined.Practical implications: Practical limits of melt cooling rate over ribbon thickness are outlined and directions for the chill wheel cooling system design are indicated.Originality/value: Comparison between cooling rates calculated at various thermal resistance assumptions of particular constituents is outlined. New method for determining contact resistance through variable heat transfer coefficient is introduced which takes into account physical

  7. Scanning electron microscopy and transmission electron microscopy microstructural investigation of high-speed tool steel after Nd:YAG pulsed laser melting.

    Kac, S; Kusinski, J; Zielinskalipiec, A; Wronska, I


    This article presents the microstructure of a pulsed Nd:YAG laser-melted high-speed steel, namely HS6-5-2. The high chemical homogeneity and fine structure of the melted zone was attributed to high cooling rates due to the short duration of interaction with the Nd:YAG pulsed laser radiation and the relatively small volume of the melted material. The structure obtained in the surface layer after laser melting has a high level of hardness and shows improved wear resistance. PMID:17100909

  8. Behaviour of iron and titanium species in cryolite-alumina melts

    Jentoftsen, Trond Eirik


    The solubility of divalent iron oxide in cryolite-based melts was studied. Both electrochemical and chemical techniques were employed. To ensure that only divalent iron was present in solution, the melt was contained in an iron crucible under an atmosphere of argon. The experimental work included investigation of the solubility as a function of alumina concentration, temperature and cryolite ratio (CR = NaF/AlF3 molar ratio). The solubility at 1020 ºC was found to decrease from 4.17 wt% Fe in...

  9. Patterns in new dimensionless quantities containing melting temperature, and their dependence on pressure



    Full Text Available The relationships existing between melting temperature and other
    macroscopic physical quantities are investigated. A new dimensionless
    quantity Q(1 not containing the Grtineisen parameter proves to be suited for serving in future studies as a tool for the determination of the melting temperature in the outer core of the Earth. The pressure dependence of more general dimensionless quantities Q„ is determined analytically and, for the chemical elements, numerically, too. The patterns of various interesting dimensionless quantities are shown in the Periodic Table and compared.

  10. Magnetic properties of ND Rich Melt-Spun ND-FE-B alloy

    Grujić Aleksandar


    Full Text Available As a part of these experimental investigations of melt-spun Nd-Fe-B alloy with Nd rich content in relation to Nd2Fe14B prepared by rapid quenching process for optimally selected cooling rate and heat treatment, the influence of the chosen chemical composition on magnetic properties was observed. The results of X-ray diffraction, Mössbauer spectroscopy phase analysis and magnetic measurement of investigated melt-spun Nd14.5Fe78.5B7 alloy are presented to bring some new information concerning the relation between their structure and magnetic properties.