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1

On the formation of U Al alloys in the molten LiCl KCl eutectic  

NASA Astrophysics Data System (ADS)

U-Al alloy formation has been studied in the temperature range of 400-550 °C by electrochemical techniques in the molten LiCl-KCl eutectic. Cyclic voltammetry showed that underpotential reduction of U(III) onto solid Al occurs at a potential about 0.35 V more anodic than pure U deposition. Open circuit potential measurements, recorded after small depositions of U metal onto the Al electrode, did not allow the distinction between potentials associated with UAl x alloys and the Al rest potential, as they were found to be practically identical. As a consequence, a spontaneous chemical reaction between dissolved UCl 3 and Al is thermodynamically possible and was experimentally observed. Galvanostatic electrolyses were carried out both on Al rods and Al plates. Stable and dense U-Al deposits were obtained with high faradic yields, and the possibility to load the whole bulk of a thin Al plate was demonstrated. The analyses (by SEM-EDX and XRD) of the deposits indicated the formation of different intermetallic phases (UAl 2, UAl 3 and UAl 4) depending on the experimental conditions.

Cassayre, L.; Caravaca, C.; Jardin, R.; Malmbeck, R.; Masset, P.; Mendes, E.; Serp, J.; Soucek, P.; Glatz, J.-P.

2008-08-01

2

Separation of plutonium from lanthanum by electrolysis in LiCl KCl onto molten bismuth electrode  

NASA Astrophysics Data System (ADS)

This work presents a study on the electroseparation of plutonium from lanthanum using molten bismuth electrodes in LiCl-KCl eutectic at 733 K. The reduction potentials of Pu 3+ and La 3+ ions were measured on a Bi thin film electrode using cyclic voltammetry (CV). A difference between the peak potentials for the formation of PuBi 2 and LaBi 2 of approximately 100 mV was found. Separation tests were then carried out using different current densities and salt phase compositions between a plutonium rod anode and an unstirred molten Bi cathode in order to evaluate the efficiency of an electrolytic separation process. At a current density of 12 mA/cm 2/wt% (Pu 3+), only Pu 3+ ions are reduced into the molten Bi electrode, leaving La 3+ ions in the salt melt. Similar results were found at two different Pu/La concentration ratios ([Pu]/[La] = 4 and 10). At a current density of 26 mA/cm 2/wt% (Pu 3+), co-reduction of Pu and La was observed as expected by the large negative potential of the Bi cathode during the separation test.

Serp, J.; Lefebvre, P.; Malmbeck, R.; Rebizant, J.; Vallet, P.; Glatz, J.-P.

2005-04-01

3

Molten salt eutectics from atomistic simulations  

NASA Astrophysics Data System (ADS)

Despite their importance for solar thermal power applications, phase-diagrams of molten salt mixture heat transfer fluids (HTFs) are not readily accessible from first principles. We present a molecular dynamics scheme general enough to identify eutectics of any HTF candidate mixture. The eutectic mixture and temperature are located using the liquid mixture free energy and the pure component solid-liquid free energy differences. The liquid mixture free energy is obtained using thermodynamic integration over particle identity transmutations sampled with molecular dynamics at a single temperature. Drawbacks of conventional phase diagram mapping methodologies are avoided by not considering solid mixtures, thereby evading expensive computations of solid phase free energies. Numerical results for binary and ternary mixtures of alkali nitrates agree well with experimental measurements.

Jayaraman, Saivenkataraman; Thompson, Aidan P.; von Lilienfeld, O. Anatole

2011-09-01

4

CATALYTIC GASIFICATION OF COAL USING EUTECTIC SALT MIXTURES  

Microsoft Academic Search

The project, ''Catalytic Gasification of Coal Using Eutectic Salt Mixtures'', is being conducted jointly by Clark Atlanta University (CAU), the University of Tennessee Space Institute (UTSI) and the Georgia Institute of Technology (GT). The aims of the project are to: identify appropriate eutectic salt mixture catalysts for the gasification of Illinois No.6 coal; evaluate various impregnation or catalyst addition methods

1999-01-01

5

CATALYTIC GASIFICATION OF COAL USING EUTECTIC SALT MIXTURES  

SciTech Connect

This progress report on the Department of Energy project DE-FG-97FT97263 entitled, ''Catalytic Gasification of Coal Using Eutectic Salt Mixtures'', covers the period April-September 1998. The specific aims of the project for this period were to identify appropriate eutectic salt mixture catalysts for the gasification of Illinois No.6 coal, evaluate various impregnation or catalyst addition methods to improve catalyst dispersion, and evaluate gasification performance in a bench-scale fixed bed reactor. The project is being conducted jointly by Clark Atlanta University (CAU), the University of Tennessee Space Institute (UTSI) and the Georgia Institute of Technology (Georgia Tech) with CAU as the prime contractor. Several single salt catalysts and binary and ternary eutectic catalysts were investigated at Clark Atlanta University. Physical mixing and incipient wetness methods were investigated as catalyst addition techniques. Gasification was carried out using TGA at CAU and UTSI and with a fixed-bed reactor at UTSI. The results showed better gasification activity in the presence of the catalysts tested. The eutectic salt studies showed clear agreement between the melting points of the prepared eutectics and reported literature values. The order of catalytic activity observed was ternary > binary > single salt. With the soluble single salt catalysts, the incipient wetness method was found to give better results than physical mixing technique. Also, catalyst preparation conditions such as catalyst loading, drying time and temperature were found to influence the gasification rate. Based on the Clark Atlanta University studies on Task 1, the project team selected the 43.5%Li{sub 2}CO{sub 3}-31.5%Na{sub 2}CO{sub 3}-25%K{sub 2}CO{sub 3} ternary eutectic and the 29%Na{sub 2}CO{sub 3}-71%K{sub 2}CO{sub 3} and 2.3% KNO{sub 3}-97.7%K{sub 2}CO{sub 3} binary eutectic for the fixed bed studies at UTSI. The eutectic salts were found to be highly insoluble in aqueous medium. As a result the technique of adding the eutectic to the raw coal was found to be better than using wet methods. Also, addition of the catalyst to the raw coal appeared to give better gasification results than addition to pyrolyzed coal. In addition, eutectic catalysts added to the coal yielded better gasification rates than rates obtained by mixing the individual salts in the eutectic ratio with the coal. These results, especially with the eutectic catalysts are very significant since the use of the low melting eutectics will reduce the severity of gasification processes.

NONE

2000-04-01

6

CATALYTIC GASIFICATION OF COAL USING EUTECTIC SALT MIXTURES  

SciTech Connect

This progress report on the Department of Energy project DE-FG-97FT97263 entitled, ''Catalytic Gasification of Coal Using Eutectic Salt Mixtures,'' covers the period April-September 1998. The specific aims of the project for this period were to identify appropriate eutectic salt mixture catalysts for the gasification of Illinois No.6 coal, evaluate various impregnation or catalyst addition methods to improve catalyst dispersion, and evaluate gasification performance in a bench-scale fixed bed reactor. The project is being conducted jointly by Clark Atlanta University (CAU), the University of Tennessee Space Institute (UTSI) and the Georgia Institute of Technology (Georgia Tech) with CAU as the prime contractor. Several single salt catalysts and binary and ternary eutectic catalysts were investigated at Clark Atlanta University. Physical mixing and incipient wetness methods were investigated as catalyst addition techniques. Gasification was carried out using TGA at CAU and UTSI and with a fixed-bed reactor at UTSI. The results showed better gasification activity in the presence of the catalysts tested. The eutectic salt studies showed clear agreement between the melting points of the prepared eutectics and reported literature values. The order of catalytic activity observed was ternary > binary > single salt. With the soluble single salt catalysts, the incipient wetness method was found to give better results than physical mixing technique. Also, catalyst preparation conditions such as catalyst loading, drying time and temperature were found to influence the gasification rate. Based on the Clark Atlanta University studies on Task 1, the project team selected the 43.5%Li{sub 2}CO{sub 3}-31.5%Na{sub 2}CO{sub 3}-25%K{sub 2}CO{sub 3} ternary eutectic and the 29%Na{sub 2}CO{sub 3}-71%K{sub 2}CO{sub 3} and 2.3%KNO{sub 3}-97.7%K{sub 2}CO{sub 3} binary eutectic for the fixed bed studies at UTSI. The eutectic salts were found to be highly insoluble in aqueous medium. As a result the technique of adding the eutectic to the raw coal was found to be better than using wet methods. Also, addition of the catalyst to the raw coal appeared to give better gasification results than addition to pyrolyzed coal. In addition, eutectic catalysts added to the coal yielded better gasification rates than rates obtained by mixing the individual salts in the eutectic ratio with the coal. These results, especially with the eutectic catalysts are very significant since the use of the low melting eutectics will reduce the severity of gasification processes.

NONE

1998-10-01

7

Catalytic Gasification of Coal using Eutectic Salt Mixtures  

SciTech Connect

The objectives of this study are to: identify appropriate eutectic salt mixture catalysts for coal gasification; assess agglomeration tendency of catalyzed coal; evaluate various catalyst impregnation techniques to improve initial catalyst dispersion; evaluate effects of major process variables (such as temperature, system pressure, etc.) on coal gasification; evaluate the recovery, regeneration and recycle of the spent catalysts; and conduct an analysis and modeling of the gasification process to provide better understanding of the fundamental mechanisms and kinetics of the process. A review of the collected literature was carried out. The catalysts which have been used for gasification can be roughly classified under the following five groups: alkali metal salts; alkaline earth metal oxides and salts; mineral substances or ash in coal; transition metals and their oxides and salts; and eutectic salt mixtures. Studies involving the use of gasification catalysts have been conducted. However, most of the studies focused on the application of individual catalysts. Only two publications have reported the study of gasification of coal char in CO2 and steam catalyzed by eutectic salt mixture catalysts. By using the eutectic mixtures of salts that show good activity as individual compounds, the gasification temperature can be reduced possibly with still better activity and gasification rates due to improved dispersion of the molten catalyst on the coal particles. For similar metal/carbon atomic ratios, eutectic catalysts were found to be consistently more active than their respective single salts. But the exact roles that the eutectic salt mixtures play in these are not well understood and details of the mechanisms remain unclear. The effects of the surface property of coals and the application methods of eutectic salt mixture catalysts with coal chars on the reactivity of gasification will be studied. Based on our preliminary evaluation of the literature, a ternary eutectic salt mixture consisting of Li- Na- and K- carbonates has the potential as gasification catalyst. To verify the literature reported, melting points for various compositions consisting of these three salts and the temperature range over which the mixture remained molten were determined in the lab. For mixtures with different concentrations of the three salts, the temperatures at which the mixtures were found to be in complete molten state were recorded. By increasing the amount of Li2CO3, the melting temperature range was reduced significantly. In the literature, the eutectic mixtures of Li- Na- and K-carbonates are claimed to have a lower activation energy than that of K2CO3 alone and they remain molten at a lower temperature than pure K2CO3. The slow increase in the gasification rates with eutectics reported in the literature is believed to be due to a gradual penetration of the coals and coal char particles by the molten and viscous catalyst phase. The even spreading of the salt phase seems to increase the overall carbon conversion rate. In the next reporting period, a number of eutectic salts and methods of their application on the coal will be identified and tested.

Atul Sheth; Pradeep Agrawal; Yaw D. Yeboah

1998-12-04

8

Modeling of anodic dissolution of U Pu Zr ternary alloy in the molten LiCl KCl electrolyte  

NASA Astrophysics Data System (ADS)

The metallic fuel anode in the molten salt electrorefining step for the pyrometallurgical reprocessing was modeled based on the findings from the anodic dissolution tests using a U Pu Zr ternary alloy. This anode model simulates selective dissolution of uranium and plutonium at lower anode potential, growth of a diffusion controlling layer consisting of a mixture of the molten salt electrolyte and the remaining zirconium metal, and simultaneous dissolution of all the constituents at higher anode potential. The calculation with this model reproduced well the actual anodic behavior of the U Pu Zr ternary alloy such as two-step rapid rise in the anode potential.

Iizuka, Masatoshi; Kinoshita, Kensuke; Koyama, Tadafumi

2005-02-01

9

CATALYTIC GASIFICATION OF COAL USING EUTECTIC SALT MIXTURES  

SciTech Connect

The project, ''Catalytic Gasification of Coal Using Eutectic Salt Mixtures'', is being conducted jointly by Clark Atlanta University (CAU), the University of Tennessee Space Institute (UTSI) and the Georgia Institute of Technology (GT). The aims of the project are to: identify appropriate eutectic salt mixture catalysts for the gasification of Illinois No.6 coal; evaluate various impregnation or catalyst addition methods to improve catalyst dispersion; evaluate effects of major process variables (e.g., temperature, system pressure, etc.) on coal gasification; evaluate the recovery, regeneration and recycle of the spent catalysts in a bench-scale fixed bed reactor; and conduct thorough analysis and modeling of the gasification process to provide a better understanding of the fundamental mechanisms and kinetics of the process. The eutectic catalysts increased gasification rate significantly. The methods of catalyst preparation and addition had significant effect on the catalytic activity and coal gasification. The incipient wetness method gave more uniform catalyst distribution than that of physical mixing for the soluble catalysts resulting in higher gasification rates for the incipient wetness samples. The catalytic activity increased by varying degrees with catalyst loading. The above results are especially important since the eutectic catalysts (with low melting points) yield significant gasification rates even at low temperatures. Among the ternary eutectic catalysts studied, the system 39% Li{sub 2}CO{sub 3}-38.5% Na{sub 2}CO{sub 3}-22.5% Rb{sub 2}CO{sub 3} showed the best activity and will be used for further bench scale fixed-bed gasification reactor in the next period. Based on the Clark Atlanta University studies in the previous reporting period, the project team selected the 43.5% Li{sub 2}CO{sub 3}-31.5% Na{sub 2}CO{sub 3}-25% K{sub 2}CO{sub 3} ternary eutectic and the 29% Na{sub 2}CO{sub 3}-71% K{sub 2}CO{sub 3} binary eutectic for the fixed-bed studies at UTSI during this reporting period. Temperature was found to have a significant effect on the rate of gasification of coal. The rate of gasification increased up to 1400 F. Pressure did not have much effect on the gasification rates. The catalyst loading increased the gasification rate and approached complete conversion when 10 wt% of catalyst was added to the coal. Upon further increasing the catalyst amount to 20-wt% and above, there was no significant rise in gasification rate. The rate of gasification was lower for a 2:1 steam to char molar ratio (60%) compared to gasification rates at 3.4:1 molar ratio of steam-to-char where the conversion approached 100%. The characterization results of Georgia Tech are very preliminary and inconclusive and will be made available in the next report.

Unknown

1999-04-01

10

CATALYTIC GASIFICATION OF COAL USING EUTECTIC SALT MIXTURES  

SciTech Connect

The Gas Research Institute (GRI) estimates that by the year 2010, 40% or more of U.S. gas supply will be provided by supplements including substitute natural gas (SNG) from coal. These supplements must be cost competitive with other energy sources. The first generation technologies for coal gasification e.g. the Lurgi Pressure Gasification Process and the relatively newer technologies e.g. the KBW (Westinghouse) Ash Agglomerating Fluidized-Bed, U-Gas Ash Agglomerating Fluidized-Bed, British Gas Corporation/Lurgi Slagging Gasifier, Texaco Moving-Bed Gasifier, and Dow and Shell Gasification Processes, have several disadvantages. These disadvantages include high severities of gasification conditions, low methane production, high oxygen consumption, inability to handle caking coals, and unattractive economics. Another problem encountered in catalytic coal gasification is deactivation of hydroxide forms of alkali and alkaline earth metal catalysts by oxides of carbon (CO{sub x}). To seek solutions to these problems, a team consisting of Clark Atlanta University (CAU, a Historically Black College and University, HBCU), the University of Tennessee Space Institute (UTSI) and Georgia Institute of Technology (Georgia Tech) proposed to identify suitable low melting eutectic salt mixtures for improved coal gasification. The research objectives of this project were to: Identify appropriate eutectic salt mixture catalysts for coal gasification; Assess agglomeration tendency of catalyzed coal; Evaluate various catalyst impregnation techniques to improve initial catalyst dispersion; Determine catalyst dispersion at high carbon conversion levels; Evaluate effects of major process variables (such as temperature, system pressure, etc.) on coal gasification; Evaluate the recovery, regeneration and recycle of the spent catalysts; and Conduct an analysis and modeling of the gasification process to provide better understanding of the fundamental mechanisms and kinetics of the process.

Dr. Yaw D. Yeboah; Dr. Yong Xu; Dr. Atul Sheth; Dr. Pradeep Agrawal

2001-12-01

11

Catalytic gasification of coal using eutectic salt mixtures. Report for the Period September 1, 1998-March 31, 1999.  

National Technical Information Service (NTIS)

The project, 'Catalytic Gasification of Coal Using Eutectic Salt Mixtures', is being conducted jointly by Clark Atlanta University (CAU), the University of Tennessee Space Institute (UTSI) and the Georgia Institute of Technology (GT). The aims of the proj...

1999-01-01

12

Recycling of LiCl-KCl eutectic based salt wastes containing radioactive rare earth oxychlorides or oxides  

NASA Astrophysics Data System (ADS)

Recycling of LiCl-KCl eutectic salt wastes containing radioactive rare earth oxychlorides or oxides was studied to recover renewable salts from the salt wastes and to minimize the radioactive wastes by using a vacuum distillation method. Vaporization of the LiCl-KCl eutectic salt was effective above 900 °C and at 5 Torr. The condensations of the vaporized salt were largely dependent on temperature gradient. Based on these results, a recycling system of the salt wastes as a closed loop type was developed to obtain a high efficiency of the salt recovery condition. In this system, it was confirmed that renewable salt was recovered at more than 99 wt.% from the salt wastes, and the changes in temperature and pressure in the system could be utilized to understand the present condition of the system operation.

Eun, H. C.; Cho, Y. Z.; Son, S. M.; Lee, T. K.; Yang, H. C.; Kim, I. T.; Lee, H. S.

2012-01-01

13

Eutectics and Phase Diagrams of Molten Salts from Molecular Dynamics simulations  

NASA Astrophysics Data System (ADS)

The use of alkali nitrate salt mixtures as heat transfer fluids in solar thermal power plants is limited by their relatively high melting point. Certain compositions of quaternary and higher dimensional mixtures of alkali and alkaline earth nitrates and nitrites have low melting points. However, the high dimensionality of the search space makes it difficult to find lowest melting compositions. Molecular simulations offer an efficient way to screen for promising mixtures. A molecular dynamics scheme general enough to identify eutectics of any HTF candidate mixture will be presented. The eutectic mixture and temperature are located as the tangent point between free energies of mixing for the liquid and a linear plane connecting the pure solid-liquid free energy differences. The free energy of mixing of the liquid phase is obtained using thermodynamic integration over "alchemical" transmutations sampled with molecular dynamics, in which particle identities are swapped gradually. Numerical results for binary and ternary mixtures of alkali nitrates agree well with experimental measurements.

Jayaraman, Saivenkataraman; von Lilienfeld, Anatole; Thompson, Aidan

2011-03-01

14

A Binary Eutectic Mixture of TNAZ and R-Salt Explosives  

NASA Astrophysics Data System (ADS)

TNAZ is a high performing explosive that is melt castable. However, the casting process can be problematic since TNAZ has a high vapor pressure exacerbated by a fairly high melting temperature. In order to mitigate the ill effects of its high vapor pressure, including a lower melting explosive was explored by making a series of mixtures of TNAZ and R-Salt. Initially, a eutectic temperature and composition was theoretically determined. Then a phase diagram was constructed from a series and mixtures by differential scanning calorimetery (DSC). The vapor pressure of the eutectic composition was determined by thermogravimetric analysis (TGA). Cylinder testing of the eutectic composition was carried out in copper tubes, 5'' long with 1/2 ``inner diameter and 1/16'' thick walls. The detonation velocity was measured using wire switches along the cylinder length and the expanding wall velocity was measured using PDV gauges. A rough evaluation of JWL equation-of-state parameters has been carried out. A more detailed evaluation is in progress.

Sandstrom, Mary; Manner, Virginia; Pemberton, Steven; Lloyd, Joseph; Tappan, Bryce

2011-06-01

15

Materials corrosion in molten lithium fluoride-sodium fluoride-potassium fluoride eutectic salt  

NASA Astrophysics Data System (ADS)

Static corrosion studies were undertaken to determine the compatibility of several candidate high temperature materials for a heat transfer loop in a molten alkali fluoride eutectic salt, LiF-NaF-KF: 46.5-11.5-42 mol % (commonly referred to as FLiNaK), as well as a molten chloride near eutectic salt, KCl-MgCl2: 68-32 mol %. Several high temperature alloys: Hastelloy-N, Hastelloy-X, Haynes-230, Inconel-617, and Incoloy-800H, Nb-1Zr, a nearly pure Ni alloy Ni-201, and a C/SiSiC ceramic were exposed to molten FLiNaK at 850°C for 500 h in sealed graphite crucibles under an argon cover gas. Corrosion occurred predominantly from dealloying of Cr from the Cr bearing alloys, an effect that was particularly pronounced at the grain boundaries. Corrosion was noted to occur from selective attack of the Si phase in the C/SiSiC ceramic. Alloy weight-loss/area due to molten fluoride salt exposure correlated with the initial Cr-content of the alloys, and was consistent with the Cr-content measured in the salts after corrosion tests. The alloys' weight-loss/area was also found to correlate to the concentration of carbon present in the nominally 20% Cr containing alloys, due to the formation of chromium carbide phases at the grain boundaries. The corrosion mechanisms for the chloride based salt were found to be similar to those observed in FLiNaK, but the chemical attack was found to be less aggressive. Sulfamate Ni electroplating and Mo plasma spraying of Fe-Ni-Cr alloy coupons was investigated to mitigate Cr dissolution. A chemical vapor deposited pyrolytic carbon and SiC coating was also investigated to protect the C/SiSiC composites. Results indicate that Ni-plating has the potential to provide protection against alloy corrosion in molten fluoride salts. Furthermore, the presence of a chromium-oxide interlayer at the interface of the Ni-plating and alloy substrate can further improve the efficacy of the Ni-plating. The pyrolytic carbon and SiC coating on the C/SiSiC composites was effective in eliminating the attack of the Si phase in the composites. Delamination of the Mo coating in FLiNaK prevented further investigation of this promising approach.

Olson, Luke Christopher

16

Catalytic gasification of coal using eutectic salt mixtures. Report for the Period April 1-September 30, 1998.  

National Technical Information Service (NTIS)

This progress report on the Department of Energy project DE-FG-97FT97263 entitled, 'Catalytic Gasification of Coal Using Eutectic Salt Mixtures' covers the period April-September 1998. The specific aims of the project for this period were to identify appr...

1998-01-01

17

EXAFS Study into the Speciation of Metal Salts Dissolved in Ionic Liquids and Deep Eutectic Solvents.  

PubMed

The speciation of metals in solution controls their reactivity, and this is extremely pertinent in the area of metal salts dissolved in ionic liquids. In the current study, the speciation of 25 metal salts is investigated in four deep eutectic solvents (DESs) and five imidazolium-based ionic liquids using extended X-ray absorption fine structure. It is shown that in diol-based DESs M(I) ions form [MCl2](-) and [MCl3](2-) complexes, while all M(II) ions form [MCl4](2-) complexes, with the exception of Ni(II), which exhibits a very unusual coordination by glycol molecules. This was also found in the X-ray crystal structure of the compound [Ni(phen)2(eg)]Cl2·2eg (eg = ethylene glycol). In a urea-based DES, either pure chloro or chloro-oxo coordination is observed. In [C6mim][Cl] pure chloro complexation is also observed, but coordination numbers are smaller (typically 3), which can be explained by the long alkyl chain of the cation. In [C2mim][SCN] metal ions are entirely coordinated by thiocyanate, either through the N or the S atom, depending on the hardness of the metal ion according to the hard-soft acid-base principle. With weaker coordinating anions, mixed coordination between solvent and solute anions is observed. The effect of hydrate or added water on speciation is insignificant for the diol-based DESs and small in other liquids with intermediate or strong ligands. One of the main findings of this study is that, with respect to metal speciation, there is no fundamental difference between deep eutectic solvents and classic ionic liquids. PMID:24897923

Hartley, Jennifer M; Ip, Chung-Man; Forrest, Gregory C H; Singh, Kuldip; Gurman, Stephen J; Ryder, Karl S; Abbott, Andrew P; Frisch, Gero

2014-06-16

18

Catalytic gasification of coal using eutectic salts: reaction kinetics for hydrogasification using binary and ternary eutectic catalysts  

Microsoft Academic Search

A kinetic study of the hydrogasification of Illinois #6 coal was carried out using a ternary (43.5mol% Li2CO3-31.5mol% Na2CO3-25mol% K2CO3) and a binary (29mol% Na2CO3-71mol% K2CO3) eutectic system. Hydrogasification experiments were carried out in a high-pressure, high-temperature differential fixed-bed gasifier unit to evaluate the product inhibition effect of H2 on the overall steam gasification kinetics. The overall gasification rate was

Atul C Sheth; Chandramouli Sastry; Yaw D Yeboah; Yong Xu; Pradeep Agarwal

2004-01-01

19

Synthesis and electrochemical properties of lithium cobalt oxides prepared by molten-salt synthesis using the eutectic mixture of LiCl–Li 2CO 3  

Microsoft Academic Search

Lithium cobalt oxide powders have been successfully prepared by a molten-salt synthesis (MSS) method using a eutectic mixture of LiCl and Li2CO3 salts. The physico-chemical properties of the lithium cobalt oxide powders are investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), particle-size analysis and charge–discharge cycling. A lower temperature and a shorter time (?700°C and 1h) in the

Chi-Hwan Han; Young-Sik Hong; Chang Moon Park; Keon Kim

2001-01-01

20

Electrochemical Study on the Electrodeposition of U, Nd, Ce, La and Y on a Liquid Cadmium Cathode in a LiCl-KCl Eutectic Salt  

SciTech Connect

Electro-depositions of U, Nd, Ce, La and Y on a liquid cadmium cathode in a LiCl-KCl eutectic salt were studied by using an electrolytic cell. For the LiCl-KCl-UCl{sub 3}- NdCl{sub 3}-CeCl{sub 3}-LaCl{sub 3}-YCl{sub 3}/Cd system, cyclic voltammograms and polarization curves were measured and the electrochemical properties of the system were discussed. From the results of the electro-depositions of U and rare earth metals on the LCC, separation factors and recovery ratios of U and REs were obtained and co-electro-depositions of U and REs were investigated. (authors)

Sung Bin Park; Jong Hyeon Lee; Sung Chan Hwang; Young Ho Kang; Joon Bo Shim; Han Soo Lee; Eung Ho Kim; Seong Won Park [Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)

2007-07-01

21

Activity coefficients of actinide and rare-earth chlorides in molten LiCl/KCl eutectic salt  

SciTech Connect

Using a numerical Gibbs free-energy minimization technique, the activity coefficients of actinide and rare-earth chlorides in molten LiCl/KCl eutectic at 450 C have been calculated. Laboratory tests of an electrochemical process for separating actinide metals from rare-earth metals in LiCl/KCl solvent at 450 C provided experimental concentration and cathode potential data. The generalized expansion by Wohl was used to express the concentration dependence of the excess Gibbs free energy. The activity coefficients were expressed in terms of the Wohl volume and interaction energy parameters. The Wohl parameters for the activity coefficient expansions were obtained by minimizing the total Gibbs free energy expressed in terms of the experimental mole fractions. This thermodynamic model will be valuable for process design and scale-up calculations.

Bechtel, T.B.; Storvick, T.S. [Univ. of Missouri, Columbia, MO (United States). Dept. of Chemical Engineering] [Univ. of Missouri, Columbia, MO (United States). Dept. of Chemical Engineering

1999-04-01

22

Distribution behavior of uranium, neptunium, rare-earth elements ( Y, La, Ce, Nd, Sm, Eu, Gd) and alkaline-earth metals (Sr,Ba) between molten LiCl?KCI eutectic salt and liquid cadmium or bismuth  

Microsoft Academic Search

Distribution coefficients of uranium neptunium, eight rare-earth elements (Y, La, Ce, Pr, Nd, Sm, Eu and Gd) and two alkaline-earth metals (Sr and Ba) between molten LiCl-KCI eutectic salt and either liquid cadmium or bismuth were measured at 773 K. Separation factors of trivalent rare-earth elements to uranium or neptunium in the LiCl-KCl\\/Bi system were by one or two orders

M. Kurata; Y. Sakamura; T. Hijikata; K. Kinoshita

1995-01-01

23

Effect of isothermal aging and salt spray tests on reliability and mechanical strength of eutectic Sn-Bi lead-free solder joints  

Microsoft Academic Search

Eutectic Sn-Bi solder has attracted a great deal of interest since it offers good reliability comparable to that of Sn-Pb solders. Additionally, the increasing need for low cost manufacturing processes, particularly in consumer electronics, has made it an interesting alternative. This paper presents reliability and microstructural studies of eutectic 42%Sn–58%Bi (wt.%) lead-free solder alloy. The reliability was investigated using two

M. Mostofizadeh; J. Pippola; T. Marttila; L. Frisk

2012-01-01

24

Temperature dependence of the elastic moduli and damping for polycrystalline LiF-22 pct CaF2 eutectic salt  

NASA Technical Reports Server (NTRS)

Young's and shear moduli and damping were measured for as-cast polycrystalline LiF-(22 mol pct)CaF2 eutectic specimens as a function of temperature using the piezoelectric ultrasonic composite oscillator technique. The shear modulus decreased with increasing temperature from about 40 GPa at 295 K to about 30 GPa at 1000 K, while the Young modulus decreased from about 115 GPa at 295 K to about 35 GPa at 900 K. These values are compared with those derived from the rule of mixtures using elastic moduli data for LiF and CaF2 single crystals. It is shown that, while the shear modulus data agree reasonably well with the predicted trend, there is a large discrepancy between the theoretical calculations and the Young modulus values, where this disagreement increases with increasing temperature.

Wolfenden, A.; Lastrapes, G.; Duggan, M. B.; Raj, S. V.

1991-01-01

25

Eutectic freeze crystallization simultaneous formation and separation of two solid phases  

NASA Astrophysics Data System (ADS)

Eutectic freeze crystallization (EFC) separates aqueous inorganic solutions into pure water and pure salt. By operating at the eutectic point, ice and salt can be formed simultaneously as two separate phases. Two aqueous systems were investigated in batch and continuous crystallization experiments: copper sulfate (eutectic temperature 271 K) and mono-ammonium phosphate (269 K). Below the eutectic temperature, ice can be formed without any salt formation by seeding with ice seeds and solely salt is formed by seeding with salt crystals. When however, the solution is seeded with both salt and ice crystals, two distinct solid phases are formed: when the stirrer is turned off, ice rises and salt settles. This shows that EFC separates aqueous solutions into ice and salt as two distinct phases. Based on these results, a 15 l cooled disk column crystallizer (CDCC) has been built, designed to crystallize and separate both the solids simultaneously in a single apparatus.

van der Ham, F.; Witkamp, G. J.; de Graauw, J.; van Rosmalen, G. M.

1999-03-01

26

Thermodynamic Assessment of Hot Corrosion Mechanisms of Superalloys Hastelloy N and Haynes 242 in Eutectic Mixture of Molten Salts KF and ZrF4  

SciTech Connect

The KF - ZrF4 system was considered for the application as a heat exchange agent in molten salt nuclear reactors (MSRs) beginning with the work carried out at ORNL in early fifties. Based on a combination of excellent properties such as thermal conductivity, viscosity in the molten state, and other thermo-physical and rheological properties, it was selected as one of possible candidates for the nuclear reactor secondary heat exchanger loop.

Michael V. Glazoff

2012-02-01

27

Spiraling eutectic dendrites  

NASA Astrophysics Data System (ADS)

Eutectic dendrites forming in a model ternary system have been studied using the phase-field theory. The eutectic and one-phase dendrites have similar forms, and the tip radius scales with the interface free energy as for one-phase dendrites. The steady-state eutectic patterns, appearing on these two-phase dendrites, include concentric rings and single- to multiarm spirals from which the fluctuations choose; a stochastic phenomenon characterized by a peaked probability distribution. The number of spiral arms correlates with the tip radius and the kinetic anisotropy.

Pusztai, Tamás; Rátkai, László; Szállás, Attila; Gránásy, László

2013-03-01

28

Solubility products of metal sulfides in molten salts: II. Measurements and calculations for lead sulfide in the LiCl-KCl and the LiCl-LiF eutectic compositions  

Microsoft Academic Search

The solubilities of lithium sulfide and the solubility products of lead sulfide in the LiCl-KCI and LiCI-LiF eutectic mixtures\\u000a have been measured by an electrochemical titration method in the temperature range from 673 to 823 K. At 823 K, the solubility\\u000a of Li2S in the LiCI-LiF eutectic was much larger than in the LiCI-KCI eutectic (1.95 ? 10?1 compared with

M. L. Saboungi; J. J. Marr; M. Blander

1979-01-01

29

Eutectics as improved pharmaceutical materials: design, properties and characterization.  

PubMed

Eutectics are a long known class of multi-component solids with important and useful applications in daily life. In comparison to other multi-component crystalline solids, such as salts, solid solutions, molecular complexes and cocrystals, eutectics are less studied in terms of molecular structure organization and bonding interactions. Classically, a eutectic is defined based on its low melting point compared to the individual components. In this article, we attempt to define eutectics not just based on thermal methods but from a structural organization view point, and discuss their microstructures and properties as organic materials vis-a-vis solid solutions and cocrystals. The X-ray crystal structure of a cocrystal is different from that of the individual components whereas the unit cell of a solid solution is similar to that of one of the components. Eutectics are closer to the latter species in that their crystalline arrangement is similar to the parent components but they are different with respect to the structural integrity. A solid solution possesses structural homogeneity throughout the structure (single phase) but a eutectic is a heterogeneous ensemble of individual components whose crystal structures are like discontinuous solid solutions (phase separated). Thus, a eutectic may be better defined as a conglomerate of solid solutions. A structural analysis of cocrystals, solid solutions and eutectics has led to an understanding that materials with strong adhesive (hetero) interactions between the unlike components will lead to cocrystals whereas those having stronger cohesive (homo/self) interactions will more often give rise to solid solutions (for similar structures of components) and eutectics (for different structures of components). We demonstrate that the same crystal engineering principles which have been profitably utilized for cocrystal design in the past decade can now be applied to make eutectics as novel composite materials, illustrated by stable eutectics of the hygroscopic salt of the anti-tuberculosis drug ethambutol as a case study. A current gap in the characterization of eutectic microstructure may be fulfilled through pair distribution function (PDF) analysis of X-ray diffraction data, which could be a rapid signature technique to differentiate eutectics from their components. PMID:24322207

Cherukuvada, Suryanarayan; Nangia, Ashwini

2014-01-28

30

Density measurements of the lithium fluoride\\/lithium sulfide eutectic at high temperature  

Microsoft Academic Search

A straightforward and reliable method to determine densities of molten salts at high temperatures was de-veloped by Janz and Lorenz several years ago.[1] This method was followed in order to determine the density of the LiF\\/Li2S eutectic[2] over the temperature range of 1176 to 1355 K in which the eutectic is liquid. The rel-ative lack of data for this eutectic

Charles L. Lloyd; James B. Gilbert

1994-01-01

31

Density measurements of the lithium fluoride\\/lithium sulfide eutectic at high temperature  

Microsoft Academic Search

A straightforward and reliable method to determine densities of molten salts at high temperatures was de-veloped by Janz and\\u000a Lorenz several years ago.[1] This method was followed in order to determine the density of the LiF\\/Li2S eutectic[2] over the temperature range of 1176 to 1355 K in which the eutectic is liquid. The rel-ative lack of data for this eutectic

Charles L. Lloyd; James B. Gilbert

1994-01-01

32

Basic molten salt process—A new route for synthesis of nanocrystalline Li 4Ti 5O 12–TiO 2 anode material for Li-ion batteries using eutectic mixture of LiNO 3–LiOH–Li 2O 2  

Microsoft Academic Search

A nanocrystalline Li4Ti5O12–TiO2 duplex phase has been synthesized by a simple basic molten salt process (BMSP) using an eutectic mixture of LiNO3–LiOH–Li2O2 at 400–500°C. The microstructure and morphology of the Li4Ti5O12–TiO2 product are characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The sample prepared by heat-treating at 300°C for 3h

M. M. Rahman; Jia-Zhao Wang; Mohd Faiz Hassan; Shulei Chou; David Wexler; Hua-Kun Liu

2010-01-01

33

Processing eutectics in space  

NASA Technical Reports Server (NTRS)

Experimental work is reported which was directed toward obtaining interface shape control while a numerical thermal analysis program was being made operational. An experimental system was developed in which the solid-liquid interface in a directionally solidified aluminum-nickel eutectic could be made either concave to the melt or convex to the melt. This experimental system provides control over the solid-liquid interface shape and can be used to study the effect of such control on the microstructure. The SINDA thermal analysis program, obtained from Marshall Space Flight Center, was used to evaluate experimental directional solidification systems for the aluminum-nickel and the aluminum-copper eutectics. This program was applied to a three-dimensional ingot, and was used to calculate the thermal profiles in axisymmetric heat flow. The results show that solid-liquid interface shape control can be attained with physically realizable thermal configurations and the magnitudes of the required thermal inputs were indicated.

Douglas, F. C.; Galasso, F. S.

1974-01-01

34

Processing eutectics in space  

NASA Technical Reports Server (NTRS)

The investigations of directional solidification have indicated the necessity of establishing a secure foundation in earth-based laboratory processing in order to properly assess low-gravity processing. Emphasis was placed on evaluating the regularity of microstructure of the rod-like eutectic Al-Al3Ni obtained under different conditions of growth involving the parameters of thermal gradient, solidification rate, and interfacial curvature. In the case of Al-Al3Ni, where the Al3Ni phase appears as facets rods, solidification rate was determined to be a controlling parameter. Zone melting of thin eutectic films showed that for films of the order of 10 to 20 micrometers thick, the extra surface energy appears to act to stabilize a regular microstructure. The results suggest that the role of low-gravity as provided in space-laboratory processing of materials is to be sought in the possibility of generating a higher thermal gradient in the solidifying ingot for a given power input-output arrangement than can be obtained under normal one-g processes.

Douglas, F. C.; Galasso, S. F.

1975-01-01

35

Coatings for directional eutectics  

NASA Technical Reports Server (NTRS)

Coatings developed to provide oxidation protection for the directionally-solidified eutectic alloy NiTaC-B (4.4 weight percent Cr) were evaluated. Of seven Co-, Fe- and Ni-base coatings that were initially investigated, best resistance to cyclic oxidation was demonstrated by duplex coatings fabricated by depositing a layer of NiCrAl(Y) by vacuum evaporation from an electron beam source followed by deposition of an Al overlayer using the pack cementation process. It was found that addition of carbon to the coating alloy substantially eliminated the problem of fiber denudation in TaC-type eutectic alloys. Burner rig cycled NiTaC-B samples coated with Ni-20Cr-5Al-0.1C-0.1Y+Al and rupture-tested at 1100 deg C performed as well as or better than uncoated, vacuum cycled and air-tested NiTaC-13; however, a slight degradation with respect to uncoated material was noted in air-stress rupture tests at 870 deg C for both cycled and uncycled samples.

Rairden, J. R.; Jackson, M. R.

1976-01-01

36

Kinetics of eutectic solidification  

NASA Astrophysics Data System (ADS)

A consistent thermodynamic description of the process of stationary eutectic solidification at low supercoolings is presented. To find the relation between the parameters that characterize this process, a new approach has been used that is based on obtaining an expression for the rate of the free-energy change by two different methods. This has made it possible to obtain a new relationship between the parameters of the arising structure. The first method is based on the consideration of the free-energy change that is due to the dissipative process of separative diffusion, which occurs in the bulk of the liquid phase. The second method involves the consideration of the balance of changes in the free energy far from the solidification front. Based on various extremum principles, analytical expressions for the rate of solidification and for the parameters of the arising eutectic structure have been derived. Rodlike and lamellar structures, which are observed most often in experiments, have been considered. It has been shown that conditions for the appearance of a particular structure are governed by the minimum values of the surface energy of the interfaces between the solid phases and by the "decomposition structure factor," which is introduced in this work.

Ivanov, M. A.; Naumuk, A. Yu.

2014-05-01

37

Electrochemical method of producing eutectic uranium alloy and apparatus  

DOEpatents

An apparatus and method for continuous production of liquid uranium alloys through the electrolytic reduction of uranium chlorides. The apparatus includes an electrochemical cell formed from an anode shaped to form an electrolyte reservoir, a cathode comprising a metal, such as iron, capable of forming a eutectic uranium alloy having a melting point less than the melting point of pure uranium, and molten electrolyte in the reservoir comprising a chlorine or fluorine containing salt and uranium chloride. The method of the invention produces an eutectic uranium alloy by creating an electrolyte reservoir defined by a container comprising an anode, placing an electrolyte in the reservoir, the electrolyte comprising a chlorine or fluorine containing salt and uranium chloride in molten form, positioning a cathode in the reservoir where the cathode comprises a metal capable of forming an uranium alloy having a melting point less than the melting point of pure uranium, and applying a current between the cathode and the anode.

Horton, James A. (Livermore, CA); Hayden, H. Wayne (Oakridge, TN)

1995-01-01

38

Coatings for directional eutectics  

NASA Technical Reports Server (NTRS)

Significant advances have been made in the development of an environmentally stable coating for a very high strength, directionally solidified eutectic alloy designated NiTaC-13. Three duplex (two-layer) coatings survived 3,000 hours on a cyclic oxidation test (1,100 C to 90 C). These coatings were fabricated by first depositing a layer of NiCrAl(Y) by vacuum evaporation from an electron beam heated source, followed by depositing an aluminizing overlayer. The alloy after exposure with these coatings was denuded of carbide fibers at the substrate/coating interface. It was demonstrated that TaC fiber denudation can be greatly retarded by applying a carbon-bearing coating. The coating was applied by thermal spraying followed by aluminization. Specimens coated with NiCrAlCY+Al survived over 2,000 hours in the cyclic oxidation test with essentially no TaC denudation. Coating ductility was studied for coated and heat-treated bars, and stress rupture life at 871 C and 1,100 C was determined for coated and cycled bars.

Rairden, J. R.; Jackson, M. R.

1976-01-01

39

Heat storage in eutectic alloys  

SciTech Connect

Classical thermodynamic equations based on the regular solution approximation yield enthalpic changes for eutectic transformation that agree roughly with values measured for several binary and ternary alloy systems by differential scanning calorimetry or differential thermal analysis. Restricting measurements to binary and ternary alloys of the relatively plentiful elements Al, Cu, Mg, Si and Zn, it has been verified that the best heat storage densities on a mass or volume basis are obtained with alloys rich in Si or Al, elements that have large heats of fusion. Several of these alloys have the highest heat-storage density reported for phase change materials that transform between 780 and 850/sup 0/K. The Mg/sub 2/Si-Si eutectic, which has outstanding storage density at 1219/sup 0/K, illustrates the utility of ordered intermetallic phases with large heat of formation that dissolve in the eutectic liquid to contribute to the entropy change.

Birchenall, C.E. (Univ. of Delaware, Newark, DE); Riechman, A.F.

1980-08-01

40

Eutectic structure in zirconium electrocorundum  

SciTech Connect

The authors explain the eutectic structure of zirconium electrocorundum, with the goal of controlling crystallization of actual alloys by changing the melt cooling conditions to produce materials of assigned properties. Sample chemical composition and conditions of preparation are shown. A qualitative change in structure of hypoeutectic alloys of Al/sub 2/O/sub 3/ with zRO/sub 2/ (zirconium electrocorundum) is possible only under conditions where the formation mechanism of corundum crystals changes, and the fresh branched growth of crystals composing the eutectic is disrupted. Nucleation of a regular eutetic struscure in zirconium electrocorundum is observed for the case of melt crystallization far from eutectic composition on abrupt melt cooling at the mold boundary and for the case of low-frequency melt vibration.

Zhekhanova, N.B.; Fotiev, A.A.; Gladkov, V.E.

1986-09-01

41

Directional Solidification of Eutectic Ceramics  

NASA Technical Reports Server (NTRS)

Two major problems associated with structural ceramics are lack of damage tolerance and insufficient strength and creep resistance at very high temperatures of interest for aerospace application. This work demonstrated that the directionally solidified eutectics can have unique poly-phase microstructures and mechanical properties superior to either constituent alone. The constraining effect of unique eutectic microstructures result in higher resistance to slow crack growth and creep. Prospect of achieving superior properties through controlled solidification are presented and this technology can also be beneficial to produce new class of materials.

Sayir, Ali

2001-01-01

42

Applications of molten salts in plutonium processing  

SciTech Connect

Plutonium is efficiently recovered from scrap at Los Alamos by a series of chemical reactions and separations conducted at temperatures ranging from 700 to 900/sup 0/C. These processes usually employ a molten salt or salt eutectic as a heat sink and/or reaction medium. Salts for these operations were selected early in the development cycle. The selection criteria are being reevaluated. In this article we describe the processes now in use at Los Alamos and our studies of alternate salts and eutectics.

Bowersox, D.F.; Christensen, D.C.; Williams, J.D.

1987-01-01

43

Dynamic modeling and simulation of eutectic freeze crystallization  

NASA Astrophysics Data System (ADS)

A computer-based dynamic model of an eutectic freeze crystallizer comprised of coupled kinetics, population, mass, and energy balances has been developed to simulate its transient behaviour. The model assumed an MSMPR crystallizer and was used to simulate the transient responses of crystal size distribution of salt and ice during the start-up of the crystallizer. The temperature and the solute concentration inside the crystallizer achieved constant values after two residence times, whereas the steady state of the crystal size distributions were reached after ten residence times. A coupled effect of the simultaneous crystallization of salt and ice was clearly visible when the high mass production rate of ice induced the occurrence of a second peak of the supersaturation of salt.

Himawan, C.; Vaessen, R. J. C.; Kramer, H. J. M.; Seckler, M. M.; Witkamp, G. J.

2002-04-01

44

A eutectic gold vapour laser  

NASA Astrophysics Data System (ADS)

This paper presents a eutectic gold vapour laser (EGVL) which uses the eutectic alloy of gold and silicon, Au/3.15Si, as the lasant. It was observed that, at low input power operation, the presence of the silicon vapour could increase the output of the 627.8 nm laser line by (50-60)% when compared with a gold vapour laser (GVL) which uses pure gold as the lasant. The improved laser output for the EGVL may be explained by an increased electron density, as a result of Penning ionization of silicon atoms. However, for higher input power operation, the EGVL showed a slower rate of increase in its laser output power and was overtaken by GVLs at a tube operating temperature of around 1650°C. This may be explained by a lowering of the electron temperature owing to increasing inelastic collisions between the electrons and silicon atoms which, although excited, may not produce additional electrons.

Tou, T. Y.; Cheak, K. E.; Low, K. S.

45

Concentration changes during eutectic solidification  

NASA Technical Reports Server (NTRS)

Thermotransport (or thermal diffusion, Soret effect) is shown to cause significant amount of segregation during the directional solidification of aluminum-copper eutectic. The concentration changes are predicted quantitatively and they are a function of temperature gradient, rate of melting and solidification and the time of soaking. There is a fair agreement between the experiments and calculations. A process is suggested where these concentration changes may be minimized.

Bhat, B. N.

1974-01-01

46

ESR OF Ti(III) in LiCl-KCl Eutectic  

Microsoft Academic Search

Study of corrosion phenomena associated with the use of molten salts as coolants raised interest in the behaviour of various metal ions in such melts. Gruen & McBeth, in the early sixties, studied various transition metal ions in LiCl\\/KCl eutectic. The purpose of the present letter is an attempt to correlate ESR data with data derived from optical spectroscopy, in

N. Beukema; D. C. Koningsberger; J. L. Verbeek

1969-01-01

47

Solubility of solid phases in eutectic systems  

SciTech Connect

A problem which takes into account the temperature dependence of interfacial energy is solved in order to describe quasi-equilibrium lines of solid-phase solubility in eutectic systems. The chosen reference point is the point of the eutectic horizontal corresponding to the limiting solubility of the second component in the solid solution. An expression is obtained which makes it possible to equate empirical values of solubility and to almost exactly represent its temperature path for the eutectic systems examined.

Psarev, V.I.

1987-04-01

48

Molten salt hydrolysis of latex  

Microsoft Academic Search

Latex-rich plants containing Guayule or its extracts are pyrolyzed in nitrogen in inorganic salt melts such as LiCl-KCl eutectic at approximately 500 degrees yield greater than 60% of a highly aromatic, combustible hydrocarbon oil suitable for use as a synthetic liquid fuel. Thus, on redistillation under N, the main fraction from molten-salt pyrolyzed dried Guayule plants powder boiled at approximately

Bauman

1980-01-01

49

Eutectic solidification and its role in casting porosity formation  

NASA Astrophysics Data System (ADS)

Understanding and controlling the eutectic solidification process in Al-Si alloys permits prediction of the formation of casting porosity, eventually leading to methods for its control and elimination. In addition, it enables control of eutectic structure, silicon morphology, and eutectic grain size to further improve the alloy properties. This paper presents the current understanding of eutectic solidification in hypoeutectic Al-Si foundry alloys and the relationship between eutectic solidification and porosity formation. New concepts in engineering eutectic solidification are also explored.

Lu, L.; Nogita, K.; McDonald, S. D.; Dahle, A. K.; Lu, L.; Dahle, A. K.

2004-11-01

50

Effects of heating on salt-occluded zeolite.  

National Technical Information Service (NTIS)

The electrometallurgical treatment of spent nuclear fuel generates a waste stream of fission products in the electrolyte, LiCl-KCl eutectic salt. Argonne National Laboratory is developing a mineral waste form for this waste stream. The waste form consists...

M. A. Lewis M. C. Hash C. Pereira J. P. Ackerman

1996-01-01

51

Synthesis and Characterization of New Materials in Molten Salt Fluxes  

Microsoft Academic Search

The main goal of this research was to explore molten salts as growth media for the synthesis of new materials. The molten salt systems investigated in this work were ionic liquids and eutectic mixtures of metal halide salts. The primary characterization methods included: SED-EDS, X-ray diffraction, SQUID magnetometry, Raman and solid state NMR. The main focus was on the magnetic

Parisa Mahjoor

2009-01-01

52

Electrochemical method of producing eutectic uranium alloy and apparatus  

DOEpatents

An apparatus and method are disclosed for continuous production of liquid uranium alloys through the electrolytic reduction of uranium chlorides. The apparatus includes an electrochemical cell formed from an anode shaped to form an electrolyte reservoir, a cathode comprising a metal, such as iron, capable of forming a eutectic uranium alloy having a melting point less than the melting point of pure uranium, and molten electrolyte in the reservoir comprising a chlorine or fluorine containing salt and uranium chloride. The method of the invention produces an eutectic uranium alloy by creating an electrolyte reservoir defined by a container comprising an anode, placing an electrolyte in the reservoir, the electrolyte comprising a chlorine or fluorine containing salt and uranium chloride in molten form, positioning a cathode in the reservoir where the cathode comprises a metal capable of forming an uranium alloy having a melting point less than the melting point of pure uranium, and applying a current between the cathode and the anode. 2 figures.

Horton, J.A.; Hayden, H.W.

1995-01-10

53

Eutectic nucleation in Al-Si alloys  

SciTech Connect

In addition to a change in silicon morphology, modification of aluminium-silicon alloys with strontium or sodium increases the size of the eutectic grains. To determine the mechanism responsible, eutectic solidification in commercial purity and ultra-high purity aluminium-silicon alloys, with and without strontium additions, was examined by a quenching technique. In the commercial unmodified alloy, nucleation was prolific while in the high-purity unmodified alloy few eutectic grains nucleated. The addition of strontium to the commercial alloy reduced the number of eutectic grains that nucleated. Addition of strontium to the high-purity alloy did not significantly alter nucleation. It is concluded that commercial purity alloys contain a large number of potent nuclei that are susceptible to poisoning by impurity modification. The flake-to-fibre transition that occurs with impurity modification is shown to be independent of any change in eutectic nucleation mode and frequency.

McDonald, Stuart D.; Nogita, Kazuhiro; Dahle, Arne K

2004-08-16

54

Re-evaluation of the eutectic region of the LiBr-KBr-LiF system  

SciTech Connect

The separator pellet in a thermal battery consists of electrolyte immobilized by a binder (typically, MgO powder). The melting point of the electrolyte determines the effective operating window for its use in a thermal battery. The development of a two-hour thermal battery required the use of a molten salt that had a lower melting point and larger liquidus range than the LiCl-KCl eutectic which melts at 352 C. Several candidate eutectic electrolyte systems were evaluated for their suitability for this application. One was the LiCl-LiBr-KBr eutectic used at Argonne National Laboratories for high-temperature rechargeable batteries for electric-vehicle applications. Using a custom-designed high-temperature conductivity cell, the authors were able to readily determine the liquidus region for the various compositions studied around the original eutectic for the LiBr-KBr-LiF system. The actual eutectic composition was found to be 60.0 m/o LiBr-37.5 m/o KBr-2.5 m/o LiF with a melting point of 324 {+-} 0.5 C.

Redey, L. [Argonne National Lab., IL (United States); Guidotti, R.A. [Sandia National Labs., Albuquerque, NM (United States)

1996-05-01

55

Controlled Ceramic-Ceramic Eutectic Microstructures.  

National Technical Information Service (NTIS)

Preparation, microstructure, crystallography and mechanical properties of high melting oxide eutectics are described. It is shown that the microstructure can be predicted from the volume fraction of the minor phase. Two basic criteria control the interfac...

V. S. Stubican R. C. Bradt

1976-01-01

56

Eutectic bonding of sapphire to sapphire  

NASA Technical Reports Server (NTRS)

Eutectic mixture of aluminum oxide and zirconium oxide provides new bonding technique for sapphires and rubies. Technique effectively reduces possibility of contamination. Bonding material is aluminum oxide and zirconium oxide mixture that matches coefficient of thermal expansion of sapphire.

Deluca, J. J.

1973-01-01

57

The Stability of a Eutectic Growth Front.  

National Technical Information Service (NTIS)

During the steady state advance of a binary eutectic growth front metallic (non faceted) materials frequently adopt a lamellar habit, and a relationship between lamellar spacing, lambda, and growth rate has previously been found experimentally and theoret...

S. O'Hara A. Hellawell

1967-01-01

58

Eutectic nucleation in Al–Si alloys  

Microsoft Academic Search

In addition to a change in silicon morphology, modification of aluminium–silicon alloys with strontium or sodium increases the size of the eutectic grains. To determine the mechanism responsible, eutectic solidification in commercial purity and ultra-high purity aluminium–silicon alloys, with and without strontium additions, was examined by a quenching technique. In the commercial unmodified alloy, nucleation was prolific while in the

Stuart D. McDonald; Kazuhiro Nogita; Arne K Dahle

2004-01-01

59

Eutectic experiment development for space processing  

NASA Technical Reports Server (NTRS)

A ground base test plan and a specimen evaluation scheme have been developed for the aluminum-copper eutectic solidification experiment to be run in the M518 multipurpose electric furnace during the Skylab mission. Besides thermal and solidification studies a detailed description is given of the quantitative metallographic technique which is appropriate for characterizing eutectic structures. This method should prove a key tool for evaluating specimen microstructure which is the most sensitive indicator of changes produced during solidification. It has been recommended that single grain pre-frozen eutectic specimens be used to simplify microstructural evaluation and to eliminate any porosity in the as-cast eutectic specimens. High purity (99.999%) materials from one supplier should be employed for all experiments. Laboratory studies indicate that porosity occurs in the MRC as-cast eutectic ingots but that this porosity can be eliminated by directional freezing. Chemical analysis shows that the MRC ingots are slightly Al rich and contain about .03% impurity. Because of the impurity content the lower cooldown rate (1.2 C/min) should be used for eutectic freezing if MRC material is used in the M518 furnace.

Hopkins, R. H.

1972-01-01

60

Density measurements of the lithium fluoride/lithium sulfide eutectic at high temperature  

NASA Astrophysics Data System (ADS)

A straightforward and reliable method to determine densities of molten salts at high temperatures was de-veloped by Janz and Lorenz several years ago.[1] This method was followed in order to determine the density of the LiF/Li2S eutectic[2] over the temperature range of 1176 to 1355 K in which the eutectic is liquid. The rel-ative lack of data for this eutectic is surprising given its potential usefulness in the study of advanced batteries'31 and electrowinning of metals from molten sulfides.[41] The method is based on the fact that a solid piece of metal of known volume suspended from a pan balance into a molten salt will weigh less than if it were sus-pended in air at the same temperature. This difference in weight measured in grams will be equal to the buoyant force of the liquid at that temperature. The density of the salt bath can then readily be determined by dividing this difference by the volume of the solid piece of metal that is immersed in the bath. The procedure can be re-peated to give density values over a range of temperatures.

Lloyd, Charles L.; Gilbert, James B.

1994-10-01

61

Protease activation in glycerol-based deep eutectic solvents  

PubMed Central

Deep eutectic solvents (DESs) consisting of mixtures of a choline salt (chloride or acetate form) and glycerol are prepared as easily accessible, biodegradable, and inexpensive alternatives to conventional aprotic cation-anion paired ionic liquids. These DES systems display excellent fluidity coupled with thermal stability to nearly 200 °C. In this work, the transesterification activities of cross-linked proteases (subtilisin and ?-chymotrypsin), immobilized on chitosan, were individually examined in these novel DESs. In the 1:2 molar ratio mixture of choline chloride/glycerol containing 3% (v/v) water, cross-linked subtilisin exhibited an excellent activity (2.9 ?mo l min?1 g?1) in conjunction with a selectivity of 98% in the transesterification reaction of N-acetyl-L-phenylalanine ethyl ester with 1-propanol. These highly encouraging results advocate more extensive exploration of DESs in protease-mediated biotransformations of additional polar substrates and use of DESs in biocatalysis more generally.

Zhao, Hua; Baker, Gary A.; Holmes, Shaletha

2011-01-01

62

Stability of eutectic interface during directional solidification  

SciTech Connect

Directional solidification of eutectic alloys shows different types of eutectic morphologies. These include lamellar, rod, oscillating and tilting modes. The growth of these morphologies occurs with a macroscopically planar interface. However, under certain conditions, the planar eutectic front becomes unstable and gives rise to a cellular or a dendritic structure. This instability leads to the cellular/dendritic structure of either a primary phase or a two-phase structure. The objective of this work is to develop a fundamental understanding of the instability of eutectic structure into cellular/dendritic structures of a single phase and of two-phases. Experimental studies have been carried out to examine the transition from a planar to two-phase cellular and dendritic structures in a ceramic system of Alumina-Zirconia (Al{sub 2}O{sub 3}-ZrO{sub 2}) and in a transparent organic system of carbon tetrabromide and hexachloroethane (CBr{sub 4}-C{sub 2}Cl{sub 6}). Several aspects of eutectic interface stability have been examined.

Han, S.H.

1996-04-23

63

Directionally solidified eutectic alloy gamma-beta  

NASA Technical Reports Server (NTRS)

A pseudobinary eutectic alloy composition was determined by a previously developed bleed-out technique. The directionally solidified eutectic alloy with a composition of Ni-37.4Fe-10.0Cr-9.6Al (in wt%) had tensile strengths decreasing from 1,090 MPa at room temperature to 54 MPa at 1,100 C. The low density, excellent microstructural stability, and oxidation resistance of the alloy during thermal cycling suggest that it might have applicability as a gas turbine vane alloy while its relatively low high temperature strength precludes its use as a blade alloy. A zirconium addition increased the 750 C strength, and a tungsten addition was ineffective. The gamma=beta eutectic alloys appeared to obey a normal freezing relation.

Tewari, S. N.

1977-01-01

64

Eutectic nucleation in hypoeutectic Al-Si alloys  

SciTech Connect

The nucleation mechanism of eutectic grains in hypoeutectic Al-Si foundry alloys has been investigated by examining deep etched specimens in high-resolution field emission gun scanning electron microscope (FEG-SEM) and by using in-situ Focused Ion Beam (FIB) milling and microscopy. Both unmodified and Sr-modified alloys were studied to characterize the nucleation mechanism of eutectic silicon flakes and fibers. It is proposed that following nucleation of eutectic Al on the primary {alpha}-Al dendrites, fine Si particles form at the solidification front upon which the eutectic Si flakes and fibers could develop. The formation of small Si particles is attributed to Si enrichment of the remaining melt due to the formation of eutectic Al (aluminum spikes) at the eutectic temperature. A hypothesis is then proposed to explain the mechanism of eutectic grains formation with main emphasis on the eutectic Si phase.

Nafisi, S. [Facility for Electron Microscopy Research, McGill University, 3640 University St., Montreal, QC, H3A 2B2 (Canada)], E-mail: snafisi@ipsco.com; Ghomashchi, R. [Advanced Materials and Processing Research Institute, Suite 122, A7-1390 Major MacKenzie, ON, L4S 0A1 (Canada); Vali, H. [Facility for Electron Microscopy Research, McGill University, 3640 University St., Montreal, QC, H3A 2B2 (Canada)

2008-10-15

65

Thermomigration in eutectic SnPb alloy  

NASA Astrophysics Data System (ADS)

The thermomigration (TM) behavior in eutectic SnPb alloy was observed under a constant thermal gradient of 1000 °C/cm. Pb phase was depleting in the hot side, so Pb atom should be the dominant migration species in the current studied conditions. By estimating the depletion atomic volume in the hot side, TM atomic flux in SnPb was estimated to be 7.02×1013 atoms/cm2 s. The important TM parameter, the molar heat flux (Q*), of eutectic SnPb alloy was obtained and found to be 22.16 kJ/mole.

Chuang, Y. C.; Liu, C. Y.

2006-04-01

66

Tin-silver-copper eutectic temperature and composition  

Microsoft Academic Search

A careful investigation of the Sn-Ag-Cu phase diagram near the ternary eutectic composition was undertaken using annealed\\u000a alloys and differential scanning calorimetry to settle some uncertainties in the eutectic composition. The eutectic composition\\u000a was found to be 3.5 wt pct Ag, 0.9 wt pct Cu, and the balance Sn. The published eutectic temperature, 217 C, was confirmed.\\u000a A value of

M. E. Loomans; M. E. Fine

2000-01-01

67

The structures of fully eutectic aluminium-silicon alloy castings  

Microsoft Academic Search

Strontium-modified aluminium alloys containing 14 to 15 wt% silicon were cast with fully eutectic structures by using heated moulds and high-purity materials. In alloys containing the additional elements magnesium, copper or nickel, a distinct eutectic colony structure was evident outlined by intermetallic compounds. At the edges of the castings the eutectic colony structures and the aluminium grains (revealed by anodizing)

T. B. Abbott; B. A. Parker

1990-01-01

68

Structure of Pure Aluminium-Silicon Eutectics.  

National Technical Information Service (NTIS)

The natural form of the silicon in the pure aluminiumsilicon eutectic at slow growth rates is continuous 'rods'. The silicon phase is ahead of the aluminium phase during the growth process. A remarkably simple explanation is given in terms of constitution...

J. A. E. Bell W. C. Winegard

1964-01-01

69

Growth mechanisms of modified eutectic silicon  

Microsoft Academic Search

Transmission electron microscopy has been used to study the growth mechanism of silicon in modified aluminium-silicon eutectic alloys. In agreement with earlier studies a high density of thin {1 1 1 } faults was observed in silicon modified by relatively large amounts of sodium or strontium. High-resolution microscopy showed that these faults were a mixture of thin twins and stacking

J. M. Dowling; J. M. Corbett; H. W. Kerr

1987-01-01

70

Pb-free Sn-Ag-Cu ternary eutectic solder  

DOEpatents

A Pb-free solder includes a ternary eutectic composition consisting essentially of about 93.6 weight % Sn-about 4.7 weight % Ag-about 1.7 weight % Cu having a eutectic melting temperature of about 217 C and variants of the ternary composition wherein the relative concentrations of Sn, Ag, and Cu deviate from the ternary eutectic composition to provide a controlled melting temperature range (liquid-solid ``mushy`` zone) relative to the eutectic melting temperature (e.g. up to 15 C above the eutectic melting temperature). 5 figs.

Anderson, I.E.; Yost, F.G.; Smith, J.F.; Miller, C.M.; Terpstra, R.L.

1996-06-18

71

Pb-free Sn-Ag-Cu ternary eutectic solder  

DOEpatents

A Pb-free solder includes a ternary eutectic composition consisting essentially of about 93.6 weight % Sn-about 4.7 weight % Ag-about 1.7 weight % Cu having a eutectic melting temperature of about 217.degree. C. and variants of the ternary composition wherein the relative concentrations of Sn, Ag, and Cu deviate from the ternary eutectic composition to provide a controlled melting temperature range (liquid-solid "mushy" zone) relative to the eutectic melting temperature (e.g. up to 15.degree. C. above the eutectic melting temperature).

Anderson, Iver E. (Ames, IA); Yost, Frederick G. (Cedar Crest, NM); Smith, John F. (Ames, IA); Miller, Chad M. (Ames, IA); Terpstra, Robert L. (Ames, IA)

1996-06-18

72

Corrosion of selected alloys in eutectic lithium-sodium-potassium carbonate at 900C  

SciTech Connect

There is an ongoing interest at the US Department of Energy in using molten salts as high temperature sensible heat storage media in advanced solar thermal systems. In this report, the compatibility of selected alloys in eutectic lithium-sodium-potassium carbonate, the salt that will be used in the near-term engineering experiments, has been evaluated at 900C. Several combinations of oxidation potential and acidity in the salt were used in the experiments. It was found that the extent of corrosion was dramatically lower for experiments conducted at high oxygen potential compared to experiments at low oxygen potential. For Inconel 600, Hastelloy N, and nickel the results indicated that corrosion rates substantially below 1 mm/year/side might reasonably be expected and that a reevaluation of alloys the showed poor corrosion resistance under low oxygen potential would be advisable.

Coyle, R.T.; Thomas, T.M.; Schissel, P.

1986-01-01

73

Crystallography of Alumina-YAG-Eutectic  

NASA Technical Reports Server (NTRS)

Multiple descriptions of the alumina-YAG eutectic crystallography appear in the ceramic literature. The orientation between two phases in a eutectic system has direct impact on residual stress, morphology, microstructural stability, and high temperature mechanical properties. A study to demonstrate that the different crystallographic relationships can be correlated with different growth constraints was undertaken. Fibers produced by Laser-Heated Float Zone (LHFZ) and Edge-defined Film-fed Growth (EFG) were examined. A map of the orientation relationship between Al2O3 and Y3Al5O12 and their relationship to the fiber growth axis as a function of pull rate are presented. Regions in which a single orientation predominates are identified.

Farmer, Serene C.; Sayir, Ali; Dickerson, Robert M.; Matson, Lawrence E.

2000-01-01

74

Eutectic mixtures for solar heat storage  

Microsoft Academic Search

Several inorganic eutectic mixtures which have melting points in a range most suitable for solar heat storage and which have high heats of fusion were investigated. Thermodynamic properties of LiNO3-NH4NO3-NH4Cl, LiNO3-NH4NO3-NaNO3, LiNO3-NH4NO3-KNO3, Mg(NO3)2.6H2O-MgCl2.6H2O, and Mg(NO3)2.6H2O-MgBr2.6H2O are reported. Supercooling, corrosion, and other problems associated with practical application of the eutectic mixtures are examined, the heat content of one system is calculated,

N. Yoneda; S. Takanashi

1978-01-01

75

Two-stage eutectic metal brushes  

DOEpatents

A two-stage eutectic metal brush assembly having a slip ring rigidly coupled to a shaft, the slip ring being electrically coupled to first voltage polarity. At least one brush is rigidly coupled to a second ring and slidingly engaged to the slip ring. Eutectic metal at least partially fills an annulus between the second ring and a stationary ring. At least one conductor is rigidly coupled to the stationary ring and electrically coupled to a second voltage polarity. Electrical continuity is maintained between the first voltage polarity and the second voltage polarity. Periodic rotational motion is present between the stationary ring and the second ring. Periodic rotational motion is also present between the brush and the slip ring.

Hsu, John S (Oak Ridge, TN) [Oak Ridge, TN

2009-07-14

76

Molten salt synthesis of potassium hexatitanate  

NASA Astrophysics Data System (ADS)

Potassium hexatitanate fibrous crystals have been synthesized by a conventional solid-state reaction and via molten salt process. The molten salt process has been shown to be effective in preparing fine and non-agglomerated K2Ti6O13 whiskers. The type of molten salt (KCl, NaCl-KCl) has a significant effect on the chemical composition of the whiskers. By using a eutectic mixture of NaCl and KCl, the replacement of potassium ions in solid potassium hexatitanate by smaller sodium ions from the chloride flux can be achieved. The characterization of the samples was carried out by means of XRD, SEM, EDX and WDX.

Zaremba, T.

2012-09-01

77

A LiAl\\/Cl sub 2 battery with a four-component alkali-metal chloride electrolyte  

Microsoft Academic Search

A LiAl\\/Clâ cell operating at 280°C was investigated. The electrolyte is a mixture of LiCl, KCl, RbCl, and CsCl with a eutectic melting point of 258 °C. The positive electrode is a gas-diffusion electrode formed by coating one side of a porous carbon electrode with PTFE. The limiting discharge current of the cell was controlled by solid-state diffusion of Li

Daniel L. Thomas; D. N. Bennion

1989-01-01

78

THE POLAROGRAPHY OF FUSED SALTS IN A MIXTURE OF LITHIUM AND POTASSIUM CHLORIDES WITH THE USE OF A STATIONARY ELECTRODE  

Microsoft Academic Search

The electrolytic cell consisted of two crucibles filled with a eutectic ; mixture of LiCl and KCl and connected by a salt bridge filled with the same salt. ; Electrical contact was made through a very thin glass diaphragm in the wall of ; the salt bridge. The anode was a pool of molten lead in contact with a carbon

I. I. Naryshkin; A. E. Bazhenov

1961-01-01

79

The effect of fluid flow on eutectic growth  

NASA Astrophysics Data System (ADS)

The effect of fluid flow on eutectic microstructure is systematically examined in Al-Cu alloys of compositions varying from 19.5 to 45.0 wt pct Cu. It is shown that significantly different fluid-flow effects are present in hypo- and hypereutectic alloys, since the modes of convection are different in these two cases. In hypoeutectic alloys, the rejected solute is copper, which is heavier than aluminum, and fluid flow gives rise to radial solute segregation in cylindrical samples. In hypereutectic alloys, a lighter aluminum is rejected that causes a double diffusive convection and gives rise to macrosegregation. These composition variations are shown to produce nonuniform microstructures that vary either radially (in hypoeutectic alloys) or axially (in hypereutectic alloys) and can give rise to a single phase-to-eutectic, lamellar-to-rod eutectic, or rod-to-lamellar eutectic transition in a given sample. Composition measurements are carried out to characterize solute segregation due to fluid flow. The fluid-flow effect on eutectic spacing in eutectic or near-eutectic alloys is found to be very small, whereas it increases the eutectic spacing in hypoeutectic alloys for a given local composition and it can increase or decrease the spacing in hypereutectic alloys, depending on the microstructure and solidification fraction. Theoretical models, based on diffusive grwoth, are modified to predict the spatio-temporal variation in eutectic microstructure caused by fluid flow.

Lee, J. H.; Liu, Shan; Trivedi, R.

2005-11-01

80

Microstructural evolution during containerless rapid solidification of Ni–Mo eutectic alloys  

Microsoft Academic Search

Ni–45%Mo hypoeutectic, Ni–47.7%Mo eutectic and Ni–50%Mo hypereutectic alloys are rapidly solidified during containerless processing in drop tube. The microstructures of Ni–47.7%Mo eutectic alloy are composed of lamellar eutectic plus anomalous eutectic of Ni and NiMo phases. When the droplet size decreases, the volume fraction of anomalous eutectic becomes larger. The structural morphology transforms into Ni dendrite plus lamellar eutectic in

W. J. Yao; X. J. Han; B. Wei

2003-01-01

81

Residual stresses in high-temperature ceramic eutectics  

Microsoft Academic Search

This paper explores residual thermal stresses in directionally solidified ceramic eutectics, a class of materials that has much promise for high-temperature structural applications. Residual strain tensors of both phases in a eutectic composite are measured by single crystal X-ray diffraction techniques. In the analysis the material is treated as fully anisotropic and the strain tensors, subsequently converted to stress tensors,

Elizabeth C. Dickey; Colleen S. Frazer; Thomas R. Watkins; Camden R. Hubbard

1999-01-01

82

Severe wear of a near eutectic aluminium–silicon alloy  

Microsoft Academic Search

The severe wear of a near eutectic aluminium–silicon alloy is explored using a range of electron microscopic, spectroscopic and diffraction techniques to identify the residually strained and unstrained regions, microcracks and oxidized regions in the subsurface. In severe wear the contact pressure exceeds the elastic shakedown limit. Under this condition the primary and eutectic silicon particles fragment drastically. The fragments

Anirban Mahato; Nisha Verma; Vikram Jayaram; S. K. Biswas

2011-01-01

83

Electrodeposition of microcrystalline chromium from fused salts  

Microsoft Academic Search

Chromium can be conveniently electroplated from fused chloride electrolytes. The deposition from LiCl-KCl (eutectic)-CrClâ melts is known to produce large crystal grains. Large grain size and other problems encountered in the electrodeposition of microcrystalline chromium from fused salt are discussed. The results indicate that combined use of forced electrolyte convection and a nucleating pulse in conjunction with a periodic reverse

T. Vargas; R. Varma; A. Brown

1987-01-01

84

ac impedance measurements of molten salt thermal batteries  

NASA Astrophysics Data System (ADS)

Non-destructive testing of thermal batteries without activating them is a challenging proposition. Molten salt thermal batteries are activated by raising their temperature to above the melting point of the salt constituting the electrolyte. One approach that we have considered is to raise the temperature of the molten salt electrolyte to a temperature below the melting point so that the battery does not get activated yet may provide sufficient mobility of the ionic species to be able to obtain some useful ac impedance measurements. This hypothesis was put to the test for two Li(Si)/FeS 2 molten salt batteries with two electrolytes of different melting points—a standard LiCl-KCl eutectic that melts at 352 °C and a LiBr-KBr-LiCl eutectic with a melting point of 319 °C. ac impedance measurements as a function of frequency and temperature below the melting point are presented for single cells and batteries.

Singh, Pritpal; Guidotti, Ronald A.; Reisner c, David

85

Method for the production of uranium chloride salt  

DOEpatents

A method for the production of UCl.sub.3 salt without the use of hazardous chemicals or multiple apparatuses for synthesis and purification is provided. Uranium metal is combined in a reaction vessel with a metal chloride and a eutectic salt- and heated to a first temperature under vacuum conditions to promote reaction of the uranium metal with the metal chloride for the production of a UCl.sub.3 salt. After the reaction has run substantially to completion, the furnace is heated to a second temperature under vacuum conditions. The second temperature is sufficiently high to selectively vaporize the chloride salts and distill them into a condenser region.

Westphal, Brian R.; Mariani, Robert D.

2013-07-02

86

Mass-transfer characteristics of nitrate-based salt mixtures  

NASA Astrophysics Data System (ADS)

Molten eutectic NaNO3-KNO3 was being circulated in three thermal convection loops constructed of alloy 800 and types 304L and 316 stainless steel. The loops were operated at a maximum salt temperature of 595 C and a salt temperature differential of 235 C. Corrosion specimens contained within each loop were withdrawn for periodic determinations of weight and microstructural changes. Salt samples were analyzed at selected intervals to monitor changes in the composition of the salt. Controlled potential voltammetry was also used. Results indicate low corrosion rates for the austenitic stainless steels in flowing NaNO3-KNO3.

Devan, J. H.; Tortorelli, P. F.

1981-03-01

87

Physical properties data compilations relevant to energy storage, 2. Molten salts: Data on single and multi-component salt systems  

Microsoft Academic Search

The work provides selected data with value judgments for a set of 49 salt systems of interest as candidate materials for thermal energy storage sub-systems and for electrochemical energy storage systems. The physical properties assessed are melting points; phase diagrams; eutectic compositions; density; surface tension; viscosity; electrical conductivity; diffusion for ions; heat of fusion; heat capacity; volume change on fusion;

G. J. Janz; C. B. Allen; N. P. Bansal; R. M. Murphy; R. P. T. Tomkins

1979-01-01

88

Eutectic freeze crystallization in a 2nd generation cooled disk column crystallizer for MgSO 4·H 2O system  

NASA Astrophysics Data System (ADS)

Eutectic freeze crystallization is a new separation process to produce pure ice and salt from concentrated salt solutions. For this new process, specialized crystallizers are being developed. A new, 2nd generation cooled disc column crystallizer (CDCC-2) with 150-l capacity and 5.6 m 2/m 3 cooling area was designed and tested for MgSO 4 crystallization. A heat flux of 1720-5750 W/m 2 was achieved at a temperature difference between coolant and crystallizer bulk solution of 3-6.5 K and a residence time of 1-3 h. Crystallization and gravitational separation of ice and salt are discussed.

Genceli, F. E.; Gärtner, R.; Witkamp, G. J.

2005-02-01

89

Halide eutectic growth experiment MA-131  

NASA Technical Reports Server (NTRS)

Fiberlike sodium chloride/lithium fluoride eutectic mixtures have been produced on earth and in space by the directional solidification technique. Macroscopic and microscopic examinations were made on longitudinal and transverse sections of Apollo Soyuz Test Project space grown and earth grown ingots. It was found that samples grown in space have a higher percentage of fibers alined with the growth axis. The enhanced alinement of fibers is attributed to the absence of convection currents in the liquid during solidification. Optical transmittance measurements of transverse sections of the space grown and earth grown ingots were performed with an infrared spectrometer. For a given sample thickness, the highest transmittance was obtained from ingots grown in space. For samples of different thicknesses, grown either in space or on earth, it was found that the thinner the sample, the higher the transmittance. This is in agreement with the general optical property of transparent materials.

Yue, A. S.; Yue, B. K.; Lee, J. Y. M.

1976-01-01

90

Directionally solidified iron-base eutectic alloys  

NASA Technical Reports Server (NTRS)

Pseudobinary eutectic alloys with nominal compositions of Fe-25Ta-22Ni-10Cr and Fe-15.5Nb-14.5Ni-6.0Cr were directionally solidified at 0.5 centimeter per hour. Their microstructure consisted of the fcc, iron solid-solution, matrix phase reinforced by about 41-volume-percent, hcp, faceted Fe2Ta fibers and 41-volume-percent, hcp, Fe2Nb lamellae for the tantalum- and niobium-containing alloys, respectively. The microstructural stability under thermal cycling and the temperature dependence of tensile properties were investigated. These alloys showed low elevated-temperature strength and were not considered suitable for application in aircraft-gas-turbine blades although they may have applicability as vane materials.

Tewari, S. N.

1976-01-01

91

Furnace atmosphere effects on casting of eutectic superalloys  

SciTech Connect

Control of furnace atmosphere is a key factor in the use of silica-bonded alumina shell molds for the directional solidification of eutectic superalloys reinforced with tantalum monocarbide whiskers. The use of a furnace atmosphere which is simultaneously oxidizing to aluminum in the eutectic alloy and reducing to silica phases in the mold results in the formation of an alumina barrier layer in situ at the metal/mold interface and an absence of silica phases in the mold region adjacent to this barrier layer. The presence of this microstructure permits castings of eutectics at metal temperatures up to 1750/sup 0/C.

Gigliotti, M.F.X.; Greskovich, C.

1980-02-01

92

Interaction of ?-silicon carbide with lead-lithium eutectic  

NASA Astrophysics Data System (ADS)

Compatibility of silicon carbide with molten lead-lithium eutectic has been studied by differential scanning calorimetry (DSC) and prolonged heating of ? - SiC pellet in molten Pb-17Li eutectic alloy at 823K. Multiple peaks were present in the DSC analysis. However, XRD analysis has not shown any new phase formation, which indicated that no chemical reaction occurred. An experiment have also been carried out by dipping ? - SiC pellet in molten Pb-17Li eutectic alloy at 823K for 500 h to check the solubility of ? - SiC in molten Pb-17Li. Substantial mass loss of ?-SiC pellet was observed which could be due to dissolution of ?-SiC or its component into the eutectic melt.

Chakraborty, Poulami; Kumar, Sanjay; Fotedar, Ram Kishen; Krishnamurthy, Nagaiyar

2013-06-01

93

Crystal morphology of unmodified aluminium-silicon eutectic microstructures  

NASA Astrophysics Data System (ADS)

The crystallography of eutectic silicon in an unmodified A1-12.7 wt% Si alloy has been studied by transmission electron microscopy and diffraction of thin films cut from bulk samples. Twinning mechanisms are described by which the silicon changes direction or adjusts interflake spacing at the solid-liquid interface. The branching mechanism observed by previous workers is confirmed but found to be infrequent at moderate freezing rates. A side-branching mechanism is described which is considered to be the primary mechanism for branching in the wheatsheaf configuration. Orientation relationships between the eutectic silicon and aluminium phases are described. These differ from those previously observed in thin films drawn from the melt. It is proposed that orientation relationships vary with freezing rate. Evidence is presented that the eutectic aluminium re-nucleates repeatedly during growth of a single eutectic grain.

Shamsuzzoha, M.; Hogan, L. M.

1986-08-01

94

Use of Microgravity to Control the Microstructure of Eutectics  

NASA Technical Reports Server (NTRS)

This grant began in June of 1996. Its long term goal is to be able to control the microstructure of directionally solidified eutectic alloys, through an improved understanding of the influence of convection. The primary objective of the projects in the present grant is to test hypotheses for the reported influence of microgravity on the microstructure of eutectics. The prior experimental results on the influence of microgravity on the microstructure of eutectics have been contradictory. With lamellar eutectics, microgravity had a negligible effect on the microstructure. Microgravity experiments with fibrous eutectics sometimes showed a finer microstructure and sometimes a coarser microstructure. Most research has been done on the MnBi/Bi rod-like eutectic. Larson and Pirich obtained a two-fold finer microstructure both from microgravity and by use of a magnetic field to quench buoyancy-driven convection. Smith, on the other hand, observed no change in microgravity. Prior theoretical work at Clarkson University showed that buoyancy-driven convection in the vertical Bridgman configuration is not vigorous enough to alter the concentration field in front of a growing eutectic sufficiently to cause a measurable change in microstructure. We assumed that the bulk melt was at the eutectic composition and that freezing occurred at the extremum, i.e. with minimum total undercooling at the freezing interface. There have been four hypotheses attempting to explain the observed changes in microstructure of fibrous eutectics caused by convection: I .A fluctuating freezing rate, combined with unequal kinetics for fiber termination and branching. 2. Off-eutectic composition, either in the bulk melt due to an off-eutectic feed or at the freezing interface because of departure from the extremum condition. 3. Presence of a strong habit modifying impurity whose concentration at the freezing interface would be altered by convection. At the beginning of the present grant, we favored the first of these hypotheses and set out to test it both experimentally and theoretically. We planned the following approaches: I .Pass electric current pulses through the MnBi/Bi eutectic during directional solidification in order to produce an oscillatory freezing rate. 2. Directionally solidify the MnBi/Bi eutectic on Mir using the QUELD II gradient freeze furnace developed by Professor Smith at Queen's University. 3. Select another fibrous eutectic system for investigation using the Accelerated Crucible Rotation Technique to introduce convection. 4. Develop theoretical models for eutectic solidification with an oscillatory freezing rate. Because of the problems with Mir, we substituted ground-based experiments at Queen's University with QUELD II vertical and horizontal, with and without vibration of the furnace. The Al-Si system was chosen for the ACRT experiments. Three related approaches were used to model eutectic solidification with an oscillatory freezing rate. A sharp interface model was used to calculate composition oscillations at the freezing interface in response to imposed freezing rate oscillations.

Wilcox. William R.; Regel, Liya L.

1999-01-01

95

Optical properties of NaCl-NaF eutectics  

NASA Technical Reports Server (NTRS)

A new concept is advanced to explain the phenomenon of transmittance versus far-field infrared wavelength of the directionally solidified NaCl-NaF eutectic in terms of the two-dimensional Bragg Scattering and the polarization effect of Rayleigh scattering. This concept can be applied to other eutectic systems as long as the index of refraction of the matrix over a range of wavelength is known. Experimental data are in excellent agreement with the theoretical prediction.

Yue, A. S.; Yu, J. G.

1976-01-01

96

The transient phase eutectic process for ceramic-metal bonding  

Microsoft Academic Search

A new method of ceramic-metal bonding using a transient gas-metal eutectic liquid is proposed, confirmed, and investigated using nickel\\/copper-oxygen\\/alumina as a model system. A low temperature gas-metal eutectic melt may be made transient (by solidification) through interaction with a more refractory metal component providing a ceramic-metal bond with good wetting, high strength, a broad process window (relative to conventional gas-metal

Thomas Richard Chapman

2002-01-01

97

Shear Strength of Eutectic Sn-Bi Lead-Free Solders After Corrosion Testing and Thermal Aging  

NASA Astrophysics Data System (ADS)

Low-cost manufacturing in the electronics industry is becoming more demanding, particularly in the production of consumer electronics. Such manufacturing processes require reliable and low-cost lead-free solders. Among the low temperature lead-free solders, eutectic Sn-Bi solder has attracted a great deal of interest since it offers good reliability comparable to that of Sn-Pb solders. In this paper, the shear strength of eutectic 42Sn-58Bi (wt.%) lead-free solder was studied using combinations of environmental tests including thermal aging at 100 °C, salt spray test, and a sequential combination of these tests. Microstructural studies on samples were performed at different time intervals of testing. To study the effect of salt spray and thermal aging on the mechanical reliability, shear testing was performed on the samples. Failure analysis including fractography on samples was conducted at different time intervals using a scanning electron microscope. Considerable corrosion was observed after the salt spray test. This was found to have a significant effect on the shear strength of the solder joints. Additionally, thermal aging was found to cause coarsening and to increase the thickness of intermetallic layers. This was also found to adversely affect the shear strength. The combination test was found to have the most significant effect, as the lowest shear strengths were seen after this testing.

Mostofizadeh, Milad; Pippola, Juha; Frisk, Laura

2014-05-01

98

Ultrasound in lead-bismuth eutectic  

SciTech Connect

The Belgian Nuclear Research Centre (SCK.CEN) is in the process of designing MYRRHA, a new multi-purpose irradiation facility to replace the ageing BR2. MYRRHA is a fast spectrum reactor cooled with lead-bismuth eutectic (LBE). As liquid metal is opaque to visual light, ultrasonic measurement techniques are selected to fulfill essential tasks that, according to our assessment, will be demanded by licensing authorities, in particular: fuel assembly identification and localization of a lost fuel assembly. To that end, a considerable research effort at SCK.CEN is devoted to study ultrasonic propagation in LBE. As ultrasonic experiments in LBE are elaborate and expensive to set up, we are particularly interested in to what extent experiments in water can be extrapolated to LBE - one of the main focuses of this article. We describe and present results of a first experiment with this goal which shows that the signal to noise ratio is better in LBE and that we even see small diffuse reflections up to 40 deg. off normal. On the other hand, we do not see internal reflections in stainless steel objects in LBE which we do in water. Therefore, we conclude that experiments in water can be used to validate algorithms for LBE on the condition that they do not rely on internal reflections. We also present solutions to tackle the essential tasks: fuel assembly identification and lost object localization. The requirements for the ultrasonic equipment implementing these solutions are also discussed. (authors)

Dierckx, M.; Van Dyck, D. [SCK.CEN, Belgian Nuclear Research Centre, Boeretang 200, BE-2400, Mol (Belgium)

2011-07-01

99

A LiAl/Cl sub 2 battery with a four-component alkali-metal chloride electrolyte  

SciTech Connect

A LiAl/Cl{sub 2} cell operating at 280{degrees}C was investigated. The electrolyte is a mixture of LiCl, KCl, RbCl, and CsCl with a eutectic melting point of 258 {degrees}C. The positive electrode is a gas-diffusion electrode formed by coating one side of a porous carbon electrode with PTFE. The limiting discharge current of the cell was controlled by solid-state diffusion of Li in the LiA1 alloy. Polarization of the Cl{sub 2} electrode was caused by the low cross-sectional area of the electrolyte film compared with the pore cross-sectional area. Deactivation of the positive electrode was caused by impurities, such as Cu{sup +}, in the electrolyte. Mathematical models of the negative and positive electrodes in a LiAl/Cl{sub 2} cell with a gas diffusion Cl{sub 2} electrode have been formulated. A thin film gas diffusion electrode model was used for the positive electrode, while solid-state diffusion of Li in {alpha}-LiAl was assumed to limit the negative electrode and the cell current. The thin film is liquid salt on the porous electrode walls through which chlorine diffuses.

Thomas, D.L. (Dept. of Chemical Engineering, Brigham Young Univ., Provo, UT (US)); Bennion, D.N. (Engineering Program, Univ. of Alabama in Huntsville, Huntsville, AL (US))

1989-01-01

100

Effect of additives on performance on hydrated-salt TES systems  

SciTech Connect

Calmac's objectives under this contract will be to evaluate a gelling agent, developed by Calor, Ltd. of England, as a means of preventing stratification in sodium thiosulfate pentahydrate and Glauber salt eutectic phase change materials; to determine techniques for the field filling and to develop repair procedures for systems incorporating the Calor gel; to study the effects of ethylene glycol and glycerin on the thermal performance of sodium thiosulfate pentahydrate and Glauber salt eutectic PCM; and to evaluate the effect of pH modification of sodium thiosulfate pentahydrate, specifically with regard to subcooling behavior. Progress is reported.

MacCracken, C.D.

1981-01-01

101

Orbital Processing of Eutectic Rod-Like Arrays  

NASA Technical Reports Server (NTRS)

The eutectic is one of only three solidification classes that exist. The others are isostructural and peritectic-class reactions, respectively. Simplistically, in a binaryeutectic phase diagram, a single liquid phase isothermally decomposes to two solid phases in a cooperative manner. The melting point minimum at the eutectic composition, isothermal solidification temperature, near-isocompositional solidification and refined solidification microstructure lend themselves naturally to such applications as brazing and soldering; industries that eutectic alloys dominate. Interest in direct process control of microstructures has led, more recently, to in-situ eutectic directional solidification with applications in electro-magnetics and electro-optics. In these cases, controlled structural refinement and the high aspect ratio and regularity of the distributed eutectic phases is highly significant to the fabrication and application of these in-situ natural composites. The natural pattern formation and scaling of the dispersed phase on a sub-micron scale has enormous potential application, since fabricating bulk materials on this scale mechanically has proven to be particularly difficult. It is thus of obvious importance to understand the solidification of eutectic materials since they are of great commercial significance. The dominant theory that describes eutectic solidification was derived for diffusion-controlled growth of alloys where both solid eutectic phases solidify metallically, i.e. without faceting at the solidification interface. Both high volume fraction (lamellar) and low volume fraction (rod-like) regular metallic arrays are treated by this theory. Many of the useful solders and brazements, however, and most of the regular in-situ composites are characterized by solidification reactions that are faceted/non-faceted in nature, rather than doubly non-faceted (metallic). Further, diffusion-controlled growth conditions are atypical terrestrially since gravitationally-driven convection is pervasive. As a consequence, it is important to determine whether these faceted/non-faceted composites behave in the same manner as their doubly non-faceted counterparts, particularly in the presence of convection. Prior analytical convective sensitivity testing of this theory predicted insensitivity. Prior experimental testing of this theory offered broad-based agreement between theory and experiment, though most results were for high volume fraction lamellar eutectics that solidified without faceting at the solidification interface. Directional solidification experiments of low volume fraction rod eutectics under damped (microgravity or magnetic field) conditions, however, have demonstrated significant sensitivity, challenging this fundamental theory. More recent theories have been proposed which introduce kinetic undercooling, faceting, fluid shear of the solute redistribution zone and the possibility that the interface composition is not the same as the bulk liquid composition. This program tests the established and proposed analytical theories and addresses the origins of discrepancies between the experimental and analytical results.

Larson, David J., Jr.

1998-01-01

102

Characterization of low-melting electrolytes for potential geothermal borehole power supplies: The LiBr-KBr-LiF eutectic  

SciTech Connect

The suitability of modified thermal-battery technology for use as a potential power source for geothermal borehole applications is under investigation. As a first step, the discharge processes that take place in LiSi/LiBr-KBr-LiF/FeS{sub 2} thermal cells were studied at temperatures of 350 C and 400 C using pelletized cells with immobilized electrolyte. Incorporation of a reference electrode allowed the relative contribution of each electrode to the overall cell polarization to be determined. The results of single-cell tests are presented, along with preliminary data for cells based on a lower-melting CsBr-LiBr-KBr eutectic salt.

Guidotti, R.A.; Reinhardt, F.W.

1998-05-01

103

Physical properties data compilations relevant to energy storage. IV. Molton salts: data on additional single and multi-component salt systems  

Microsoft Academic Search

The present work provides selected data with value judgements for an additional set of 107 salt systems of interest as candidate materials for thermal energy storage sub-systems, for electrochemical energy storage systems, and in electrochemical aluminum production. The physical properties assessed are: melting points; phase diagrams; eutectic compositions; density; surface tension; viscosity; electrical conductivity; diffusion constants for ions; heat of

G. J. Janz; R. P. T. Tomkins

1981-01-01

104

Dendritic and eutectic solidification of undercooled Co-Sb alloys  

SciTech Connect

Co-20- wt% Sb hypoeutectic, Co-41.4 st% Sb eutectic, and Co-45 wt% Sb hypereutectic alloys were undercooled by up to 224, 225 and 177 K, respectively. The dendritic and eutectic growth velocities during rapid solidification were measured by an infrared technique. It is found that dendrite growth in the hypoeutectic alloy is still in the regime of solute diffusion-controlled growth even at an undercooling of 224 K. A dendritic-equiaxed'' microstructure transition occurs if this hypoeutectic alloy is undercooled by more than 90 K, resulting in an abrupt grain refinement effect. Two undercooling thresholds were observed for the eutectic alloy: below the lower limit of [Delta]T[sup [asterisk

Wei, B.; Herlach, D.M.; Feuerbacher, B. (Inst. fuer Raumsimulation, Stuggart (Germany)); Sommer, F. (Max-Planck-Inst. fuer Metallforschung, Stuttgart (Germany))

1993-06-01

105

Properties of Rolled Sheet of Al-Mg2Si Monovariant Eutectic Alloys.  

National Technical Information Service (NTIS)

Rolled sheets were prepared from two Al-Mg2Si monovariant eutectic alloys, one with a quasi-binary eutectic composition, the other containing excess Mg. Their metallography, annealing behavior, age hardening, fracture strength, thermal stability and tensi...

J. Kaneko

1976-01-01

106

Ternary eutectic growth of Ag-Cu-Sb alloy within ultrasonic field  

NASA Astrophysics Data System (ADS)

The liquid to solid transformation of ternary Ag42.4Cu21.6Sb36 eutectic alloy was accomplished in an ultrasonic field with a frequency of 35 kHz, and the growth mechanism of this ternary eutectic was examined. Theoretical calculations predict that the sound intensity in the liquid phase at the solidification interface increases gradually as the interface moves up from the sample bottom to its top. The growth mode of ( ? + ? + Sb) ternary eutectic exhibits a transition of “divorced eutectic—mixture of anomalous and regular structures—regular eutectic” along the sample axis due to the inhomogeneity of sound field distribution. In the top zone with the highest sound intensity, the cavitation effect promotes the three eutectic phases to nucleate independently, while the acoustic streaming efficiently suppresses the coupled growth of eutectic phases. In the meantime, the ultrasonic field accelerates the solute transportation at the solid-liquid interface, which reduces the solute solubility of eutectic phases.

Zhai, Wei; Hong, Zhenyu; Wei, Bingbo

2007-08-01

107

Possible mechanism of superconductivity in metal-semiconductor eutectic alloys  

SciTech Connect

The effect due to the tunneling of conduction electrons into the negative-U centers at the disordered metal-semiconductor interfaces on the superconductivity of metal-semiconductor eutectic alloys is considered. Gorkov's formalism is used to calculate T/sub c/ for (i) n/sub I/<<1 and lambdanot =0, (ii) lambda=0. Where n/sub I/ is the concentration of the pairing centers and lambda is the phonon-mediated electron-electron interaction in BCS theory. Our results can qualitatively explain the increase of T/sub c/ in Al-Si, Al-Ge, and Be-Si eutectic alloys.

Ting, C.S.; Talwar, D.N.; Ngai, K.L.

1980-10-06

108

The fusion reactor blanket with lithium-lead eutectic alloy Li17-Pb83  

SciTech Connect

Results of improvements of lithium-lead eutectic blanket channels are described in the report. Operations conditions of breeding channels, technics of filling up with eutectic and tritium recovery problems are considered. LOCA and LOFA as well as eutectic-water interaction are analyzed. The article contains a survey of investigations of eutectic and channel structure thermal-mechanical behavior, that was the cause of the up-to-date channel option. There are suggestion for the further development of the channel design.

Danilov, I.V.; Poliksha, V.V.; Sidorov, A.M. [and others

1993-12-31

109

Radioscopic visualization of isothermal solidification of eutectic Ga-ln alloy  

Microsoft Academic Search

The phase diagram for a gallium-indium alloy shows that the eutectic is formed at a temperature of 15.3 C and has a eutectic composition of 14.2 at. pct In (21.4 wt pct In). A eutectic melt is expected to solidify completely when the eutectic temperature is reached. This requires that no gravitational segregation occurs in the melt. A survey of

R. Derebail; J. N. Koster

1996-01-01

110

Salt assault  

Microsoft Academic Search

If the offshore arena is the last great frontier for oil and gas exploration and development, then salt may very well be the last great barrier to exploring that frontier. In the game of seismic acquisition, salt refuses to follow the rules. Its relatively low density coupled with high velocity and structural complexity plays havoc with seismic imaging, rendering data

Duey

1999-01-01

111

High temperature molten salt storage  

NASA Astrophysics Data System (ADS)

The design of a high-temperature molten salt thermal energy storage (TES) concept, including some materials testing, was developed by Rockwell International's Rocketdyne Division (RD), under contract to SERI, and is described in this document. The main features of the concept are a conical hot tank with a liner and internal insulation that allows unrestricted relative thermal expansion and the use of cathodic protection (impressed voltage) to inhibit corrosion. The RD design uses two tanks and ternary eutectic lithium-sodium-potassium carbonates for sensible heat storage. The tanks were sized for 6 h of storage at a discharge rate of 300 MW, giving 1800 MWh total usable thermal storage capacity. The molten carbonate storage medium is cycled between 425 and 900C. From the design study, no definitive statement can be made as to the cost-effectiveness of cathodic protection. Several anode design issues need to be resolved before cathodic protection can significantly reduce corrosion where the liner comes in contact with molten salts. However, where the tank is exposed to salt vapor, the large corrosion allowance required for the liner without cathodic protection results in a much thicker liner wall and shorter liner life than originally perceived, which affects system costs significantly.

Ives, J.; Newcomb, J. C.; Pard, A. G.

1985-10-01

112

Refinement of Eutectic Silicon Phase of Aluminum A356 Alloy Using High-Intensity Ultrasonic Vibration  

SciTech Connect

The eutectic silicon in A356 alloy can be refined and modified using either chemical, quench, or superheating modification. We observed, for the first time, that the eutectic silicon can also be significantly refined using high-intensity ultrasonic vibration. Rosette-like eutectic silicon is formed during solidification of specimen treated with high-intensity ultrasonic vibration.

Jian, Xiaogang [ORNL; Han, Qingyou [ORNL

2006-01-01

113

Columnar to equiaxed transition of eutectic in hypoeutectic aluminium–silicon alloys  

Microsoft Academic Search

Directional solidification of unmodified and strontium modified binary, high-purity, aluminium–7 wt% silicon and commercial A356 alloys has been carried out to investigate the mechanism of eutectic solidification. The microstructure of the eutectic growth interface was investigated with optical microscopy and Electron Backscattering Diffraction (EBSD). In the commercial alloys, the eutectic solidification interface extends in the growth direction and creates a

G. Heiberg; K. Nogita; A. K. Dahle; L. Arnberg

2002-01-01

114

Eutectic grain size and strontium concentration in hypoeutectic aluminium–silicon alloys  

Microsoft Academic Search

Recently it has been shown that modification with strontium causes an increase in the size of eutectic grains. The eutectic grain size increases because there are fewer nucleation events, possibly due to the poisoning of phosphorus-based nuclei that are active in the unmodified alloy. The current paper investigates the effect of strontium concentration on the eutectic grain size. In the

Stuart D. McDonald; Kazuhiro Nogita; Arne K. Dahle

2006-01-01

115

Fourier Thermal Analysis of the Eutectic Formed in Pb-Sn Alloys  

NASA Astrophysics Data System (ADS)

The effect of the presence of two different primary phases on the microstructural characteristics and solidification kinetics of Pb-Sn eutectic was analyzed using Fourier thermal analysis method (FTA) and microstructural characterization. Three Pb-Sn alloys, a hypoeutectic, an eutectic, and a hypereutectic alloy, were melted in an electric furnace under an argon atmosphere and poured into sand molds. Cooling curves were obtained and numerically processed using FTA. Microstructural observations of the probes indicate a lamellar morphology for the eutectic microconstituent of the hypereutectic alloy; the eutectic alloy shows the presence of both lamellar and anomalous eutectic and the hypoeutectic alloy shows only the presence of anomalous eutectic. FTA results indicate that in the case of the probes showing the presence of anomalous eutectic, there is a primary eutectic formed during recalescence at high undercooling and a secondary eutectic yielded at low undercooling at the eutectic plateau temperature. This result shows that the cause behind the observed differences in the eutectic morphologies of the experimental alloys lies on the nucleating ability of the primary phase available as a potential substrate for nucleation of the eutectic microconstituent.

Cruz, H.; Ramírez-Argaez, M.; Juarez, A.; Garcia, A.; González-Rivera, C.

2009-06-01

116

Effects of boron on eutectic modification of hypoeutectic Al–Si alloys  

Microsoft Academic Search

The effects of boron on the eutectic modification and solidification mode of hypoeutectic Al–Si alloys have been studied adding different boride phases. The results show that boron does not cause modification of the eutectic silicon. Boron-containing samples display eutectic nucleation and growth characteristics similar to that of unmodified alloys.

K Nogita; A. K Dahle

2003-01-01

117

Preparation and Characterization of Single Crystals and Epitaxial Layers of Silicon Carbide by Molten Salt Electrolysis.  

National Technical Information Service (NTIS)

The synthesis of silicon carbide by electrolysis of molten salts has been achieved for the first time. Two systems have been investigated, one involving K2SiF6 and Li2CO3 dissolved in a KF/LiF eutectic, the other being a combination of Na2CO3 and SiO2 wit...

D. Elwell R. S. Feigelson T. H. Geballe

1979-01-01

118

Divorced eutectic in a HPDC magnesium–aluminum alloy  

Microsoft Academic Search

The morphology of the eutectic in a thin-wall high pressure die cast (HPDC) U-shape AM60 magnesium box was investigated by light microscope, SEM, TEM and EPMA. The extremely fast cooling rate taking place in the solidification process produces a highly segregated zone near the boundaries of small grains and a fine distribution of ? particles, which is typical of a

S. Barbagallo; H. I. Laukli; O. Lohne; E. Cerri

2004-01-01

119

Microstructural evolution of eutectic Au-Sn solder joints  

SciTech Connect

Current trends toward miniaturization and the use of lead(Pb)-free solder in electronic packaging present new problems in the reliability of solder joints. This study was performed in order to understand the microstructure and microstructural evolution of small volumes of nominally eutectic Au-Sn solder joints (80Au-20Sn by weight), which gives insight into properties and reliability.

Song, Ho Geon

2002-05-31

120

Structure of directionally solidified InSb-Sb eutectic alloy  

SciTech Connect

The eutectic alloy of InSb-Sb has been directionally solidified at various rates in order to investigate the structure changes due to solidification conditions. The boundary energy between the InSb and Sb phases was determined from a dislocation model of the interface.

Umehara, Y.; Koda, S.

1987-11-01

121

Quench modification of aluminium-silicon eutectic alloys  

Microsoft Academic Search

Directional solidification of aluminium-silicon eutectic alloys were carried out in order to investigate the mechanism by which the quench modification takes place. For this purpose a new type of Bridgman furnace was designed which can attain a high temperature gradient and a high interfacial growth velocity up to 1000 µm-1. It is established that the fibrous structure is the result

S. Khan; R. Elliott

1996-01-01

122

Refinement of Promising Coating Compositions for Directionally Cast Eutectics.  

National Technical Information Service (NTIS)

The successful application of high creep strength, directionally solidified gamma/gamma prime-delta (Ni-19.7Cb-6Cr-2.5Al) eutectic superalloy turbine blades requires the development of suitable coatings for airfoil, root and internal blade surfaces. In or...

T. E. Strangman E. J. Felten R. S. Benden

1976-01-01

123

Damping Capacity of HypoEutectic Zn-Al Alloys  

Microsoft Academic Search

Damping capacity of hypo-eutectic Zn-Al alloys as a function of rolling ratio is investigated. Effect of heat treatment after cold rolling on the damping capacity is discussed. Damping tests were carried out using the method of the free decay of vibrations in bending oscillation. With an increase in rolling reduction, the damping capacity was increased. As the results of tensile

T. Kurosawa; T. Otani; K. Hoshino

1996-01-01

124

Directional solidification of eutectic composites in space environment  

NASA Technical Reports Server (NTRS)

The Ni-Ni3Ta eutectic and a nickel-base alloy containing 30 wt pct Ta were solidified unidirectionally in an electron beam floating zone melting apparatus. It was found that the volume fraction of the Ni3Ta phase in the Ni-Ni3Ta eutectic mixture was increased from 7.6 to 36 volume pct in agreement with the theory as predicted. Tensile properties of the randomly solidified and unidirectionally solidified Ni-Ni3Ta eutectic were determined as function of solidification rate and temperature. It was found that the ultimate tensile strength decreased as both the test temperature and solidification rate increased. An elongation of 40 pct was obtained for a nickelbase alloy containing 30 wt at room temperature. This unusually large elongation was attributed to the superplastic behavior of the alloy. The critical currents versus the external fields at 2.5, 3.0, 3.5 and 4.2 deg for the unidirectionally solidified Pb-Sn eutectic were measured. The values of critical fields at zero critical currents were obtained by extrapolation.

Yue, A. S.

1972-01-01

125

Use of Microgravity to Control the Microstructure of Eutectics  

NASA Technical Reports Server (NTRS)

This grant began in June of 1996. Its long term goal is to be able to control the microstructure of directionally solidified eutectic alloys, through an improved understanding of the influence of convection. The primary objective of the present projects is to test hypotheses for the reported influence of microgravity on the microstructure of three fibrous eutectics (MnBi-Bi, InSb-NiSb, Al3Ni-Al). A secondary objective is to determine the influence of convection on the microstructure of other eutectic alloys. Two doctoral students and a masters student supported as a teaching assistant were recruited for this research. Techniques were developed for directional solidification of MnBi-Bi eutectics with periodic application of current pulses to produce an oscillatory freezing rate. Image analysis techniques were developed to obtain the variation in MnBi fiber spacing, which was found to be normally distributed. The mean and standard deviation of fiber spacing were obtained for several freezing conditions. Eighteen ampoules were prepared for use in the gradient freeze furnace QUELD developed at Queen's University for use in microgravity. Nine of these ampoules will be solidified soon at Queen's in a ground-based model. We hope to solidify the other nine in the QUELD that is mounted on the Canadian Microgravity Isolation Mount on MIR. Techniques are being developed for directional solidification of the Al-Si eutectic at different freezing rates, with and without application of accelerated crucible rotation to induce convection. For the first time, theoretical methods are being developed to analyze eutectic solidification with an oscillatory freezing rate. In a classical sharp-interface model, we found that an oscillatory freezing rate increases the deviation of the average interfacial composition from the eutectic, and increases the undercooling of the two phases by different amounts. This would be expected to change the volume fraction solidifying and the fiber spacing. Because of difficulties in tracking the freezing interfaces of the two solid phases, a phase-field model is also being developed. A paper demonstrating application of phase field methods to periodic structures has been submitted for publication.

Wilcox, William R.; Regel, Liya L.; Smith, Reginald W.

1998-01-01

126

The transient phase eutectic process for ceramic-metal bonding  

NASA Astrophysics Data System (ADS)

A new method of ceramic-metal bonding using a transient gas-metal eutectic liquid is proposed, confirmed, and investigated using nickel/copper-oxygen/alumina as a model system. A low temperature gas-metal eutectic melt may be made transient (by solidification) through interaction with a more refractory metal component providing a ceramic-metal bond with good wetting, high strength, a broad process window (relative to conventional gas-metal eutectic bonds), high thermal stability, and controlled thermoelastic stress; transport of a more active species to the ceramic interface may further improve adherence. A eutectic between the low-melting component (copper) and a gas (oxygen) forms at the interface between the refractory metal (nickel) and ceramic (alumina). This interfacial liquid wets the surfaces and promotes bonding. Because the entire copper interlayer is melted, the processing window is wider than conventional gas-metal eutectic in terms of temperature, atmosphere, and time. The liquid (Cu-O) dissolves the active, refractory component (Ni) providing transport to the interface where a refractory bond phase (NiAl2O4) forms. Interactions at temperature consume the liquid phase causing isothermal solidification. Diffusional homogenization further increases the solidus temperature of the joint. Multilayer bond structures were produced using both foils and plating. Oxygen additions were investigated using pre-oxidation of each metal and/or oxidation in-situ. The best bonds resulted from foils combining nickel pre-oxidation with a eutectic atmosphere. The oxide layer slows the oxidation kinetics of the nickel which allows eutectic liquid to form providing wetting, reaction, and adherence to the ceramic. The interfacial bond structure consists of a uniform, thin (sub-micron) reaction layer of nickel-aluminate (NiAl2 O4) spinel. Adhesion is comparable to current technologies and can exceed the ceramic strength. Typical peel failure occurs at the metal-spinel interface. Residual thermo-elastic stress is reduced relative to conventional direct bond copper. A high-temperature peel test was developed to evaluate thermal stability. It showed that strength was maintained to 800°C, the apparatus limit. Long term exposure at 1000°C did not deteriorate bond strength when interfacial oxidation was limited.

Chapman, Thomas Richard

127

The removal of encapsulated catalyst particles from carbon nanotubes using molten salts  

Microsoft Academic Search

A novel method, using molten salts, is described for the removal of encapsulated nickel catalyst particles from multi-walled carbon nanotubes. The multi-walled carbon nanotubes, synthesised by the decomposition of methane and hydrogen over a NiO\\/SiO2 aerogel catalyst, were treated in a LiCl–KCl eutectic molten salt and subsequently by hydrochloric acid to remove the nickel catalyst particles. The influence of the

Xuanke Li; Guanming Yuan; Andy Brown; Aidan Westwood; Rik Brydson; Brian Rand

2006-01-01

128

Microstructure and thermal fatigue life of BGAs with eutectic Sn-Ag-Cu balls assembled at 210\\/spl deg\\/C with eutectic Sn-Pb solder paste  

Microsoft Academic Search

Conventionally, it has been understood that in order to assemble BGAs with eutectic Sn-Ag-Cu solder balls in eutectic Sn-Pb solder paste, a reflow profile having a peak temperature higher than 217degC, which is the melting point of eutectic Sn-Ag-Cu, would be required to achieve complete mixing of the Sn-Pb paste and the Sn-Ag-Cu ball. Nevertheless, it was observed in this

N. Nandagopal; Zequn Mei; Sue Teng

2006-01-01

129

Microstructural development of eutectic Bi-Sn and eutectic In-Sn during high temperature deformation  

SciTech Connect

Eutectic Bi-Sn and In-Sn solder joints were subjected to high temperature deformation in shear in order to determine whether microstructural instabilities are generated during testing. Dynamic recrystallization had previously been observed in Sn-Pb solder joints during creep and fatigue in shear. The current study shows that Bi-Sn can recrystallize during deformation in creep or at constant strain rate, whereas no microstructural changes are observed in In-Sn. Recrystallization of Bi-Sn is concentrated in a narrow band along the length of the sample, parallel to the direction of shear strain, similar to behavior in Sn-Pb. The recrystallization appears to proceed by migration of interphase boundaries rather than by a nucleation and growth mechanism. A minimum total strain is required to induce obvious recrystallization in Bi-Sn, independent of applied stress or strain rate. This value of strain is much higher than the strain at initiation of tertiary creep or at the maximum shear stress. Onset of tertiary creep and strain softening occur as a result of nonuniform deformation in the samples that is independent of the microstructural instabilities. The creep behavior of In-Sn is relatively straightforward, with a single creep mechanism operating at all temperatures tested. 36 refs., 13 figs.

Goldstein, J.L.F.; Morris, J.W. Jr. (Lawrence Berkeley Lab., CA (United States) Univ. of California, Berkeley, CA (United States))

1994-05-01

130

Pearlite-like eutectic of ZL 108 aluminium-silicon alloy containing rare-earth elements rapidly solidified by laser  

Microsoft Academic Search

Cast aluminium alloys with eutectic composition have been frequently used in industry owing to their low cost, simple processing and light weight. Their mechanical properties strongly depend on their eutectic microstructure. Such methods as adding elements and rapid solidification have been widely used to refine the eutectic. A lot of work on the eutectic structure in cast aluminium alloys has

H. Jiandong; L. Yongbing; L. Zhang

1990-01-01

131

Corrosion of ODS steels in lead bismuth eutectic  

NASA Astrophysics Data System (ADS)

Oxide dispersion strengthened (ODS) ferritic steels are advanced materials being developed for high temperature applications. Their properties (high temperature strength, creep resistance, corrosion/oxidation resistance) make them potentially usable for high temperature applications in liquid metal cooled systems like liquid lead-bismuth eutectic cooled reactors and spallation sources. Corrosion tests on five different ODS alloys were performed in flowing liquid lead-bismuth eutectic in the DELTA Loop at the Los Alamos National Laboratory at 535 °C for 200 h and 600 h. The tested materials were chromium alloyed ferritic/martensitic steels (12YWT, 14YWT, MA957) and Cr-Al alloyed steels (PM2000, MA956). It was shown that the Al alloyed ODS steel above 5.5 wt% Al (PM2000) is highly resistant to corrosion and oxidation in the conditions examined, and that the corrosion properties of the ODS steels depend strongly on their grain size.

Hosemann, P.; Thau, H. T.; Johnson, A. L.; Maloy, S. A.; Li, N.

2008-02-01

132

Coatings for directional eutectics. [for corrosion and oxidation resistance  

NASA Technical Reports Server (NTRS)

Eleven coating systems based on MCrAlY overlay and diffusion aluminide prototypes were evaluated to determine their capability for protecting the gamma/gamma prime-delta directionally solidified eutectic alloy (Ni-20Cb-6Cr-2.5Al) in gas turbine engine applications. Furnace oxidation and hot corrosion, Mach 0.37 burner-rig, tensile ductility, stress-rupture and thermomechanical fatigue tests were used to evaluate the coated gamma/gamma prime-delta alloy. The diffusion aluminide coatings provided adequate oxidation resistance at 1144 K (1600 F) but offered very limited protection in 114 K (1600 F) hot corrosion and 1366 K (2000 F) oxidation tests. A platinum modified NiCrAlY overlay coating exhibited excellent performance in oxidation testing and had no adverse effects upon the eutectic alloy.

Felten, E. J.; Strangman, T. E.; Ulion, N. E.

1974-01-01

133

Nickel solubility limit in liquid lead–bismuth eutectic  

Microsoft Academic Search

In the framework of the Accelerator-Driven System (ADS), the Pb–Bi eutectic can be used as spallation target for neutron production. The Pb–Bi flow in contact with the ADS structural steels, T 91 (Fe–9Cr martensitic steel) and 316L (Fe–17Cr–10Ni austenitic steel), can dissolve the main steel components: iron, chromium and nickel. According to literature, in low oxygen containing Pb–Bi, the dissolution

L. Martinelli; F. Vanneroy; J. C. Diaz Rosado; D. L’Hermite; M. Tabarant

2010-01-01

134

Control of eutectic solidification microstructures through laser spot perturbations  

Microsoft Academic Search

We report on a new experimental technique for controlling lamellar (nonfaceted) eutectic microstructures and testing their stability in thin-sample directional solidification (TDS) of a model transparent alloy (CBr4–C2Cl6). We observe the solidification front in real time by optical microscopy. We use micromanipulation with a holographic laser spot array for perturbing the solidification front on a scale ranging from one to

Silvere Akamatsu; Kyuyong Lee; Wolfgang Losert

2006-01-01

135

Powder eutectic coating with Al 3 Ti for steels  

Microsoft Academic Search

Plates and round bars made of a pure iron or a carbon steel (JIS-S45C) have successfully been coated with Al3Ti powder by the “powder eutectic coating” method. The coated layers are found to show graded microstructures, where the concentrations\\u000a of Fe, Al, and Ti change gradually from the surface toward the inside of a specimen. The microstructure of the coated

H. Kafuku; Y. Tomota; T. Suzuki; M. Isaka

2002-01-01

136

High temperature creep properties of eutectic and near eutectic silver-copper alloys: Application to metal\\/ceramic joining  

Microsoft Academic Search

Calculations of residual stresses in eutectic Ag-Cu braze joints are often required to validate designs for a variety of metal\\/ceramic joining applications. In particular, Finite Element Analysis (FEA) codes have the capability of incorporating either elastic-plastic or minimum creep rate constitutive models for the braze material. Unfortunately, neither high temperature stress-strain or creep data are available in the literature for

J. J. Stephens; S. N. Burchett; F. M. Hosking

1991-01-01

137

Eutectic reaction and microstructural characteristics of Al (Li)Mg2Si alloys  

Microsoft Academic Search

Thermal analysis, directional solidification and metallographic techniques were applied to investigate the pseudobinary eutectic reaction process and the microstructural characteristics of Al(Li)-Mg2Si alloys. It was demonstrated that the eutectic reaction curve for L ? Al(Li) + Mg2Si in the Al(Li)-Mg-Si system moves to the Al-rich corner with the increase of Li additions. The pseudobinary eutectic point with the highest melting

S.-P. Li; S.-X. Zhao; M.-X. Pan; D.-Q. Zhao; X.-C. Chen; O. M. Barabash

2001-01-01

138

The initial stage of contact melting and the phase state of melt in eutectic systems  

Microsoft Academic Search

Mechanisms of anomalously fast formation of the transient layer and the formation of liquid-phase nucleation sites in the\\u000a initial stage of contact (eutectic) melting are proposed. The reasons for the low melting of eutectics are discussed. A method\\u000a for constructing a hypothetical solidus line in the state diagram of low-dimensional eutectic systems is described. The possibility\\u000a of existence of microinhomogeneous

V. Z. Afashokov; A. A. Ahkubekov; S. N. Ahkubekova; M. M. Baysultanov

2009-01-01

139

Bonding of sapphire to sapphire by eutectic mixture of aluminum oxide and zirconium oxide  

NASA Technical Reports Server (NTRS)

Bonding of an element comprising sapphire, ruby or blue sapphire to another element of such material with a eutectic mixture of aluminum oxide and zirconium oxide is discussed. The bonding mixture may be applied in the form of a distilled water slurry or by electron beam vapor deposition. In one embodiment the eutectic is formed in situ by applying a layer of zirconium oxide and then heating the assembly to a temperature above the eutectic temperature and below the melting point of the material from which the elements are formed. The formation of a sapphire rubidium maser cell utilizing eutectic bonding is shown.

Deluca, J. J. (inventor)

1975-01-01

140

Bonding of sapphire to sapphire by eutectic mixture of aluminum oxide and zirconium oxide  

NASA Technical Reports Server (NTRS)

An element comprising sapphire, ruby or blue sapphire can be bonded to another element of such material with a eutectic mixture of aluminum oxide and zirconium oxide. The bonding mixture may be applied in the form of a distilled water slurry or by electron beam vapor deposition. In one embodiment the eutectic is formed in situ by applying a layer of zirconium oxide and then heating the assembly to a temperature above the eutectic temperature and below the melting point of the material from which the elements are formed. The formation of a sapphire rubidium maser cell utilizing eutectic bonding is shown.

Deluca, J. J. (inventor)

1979-01-01

141

Investigations of neutron characteristics for salt blanket models; integral fission cross section measurements of neptunium, plutonium, americium and curium isotopes  

SciTech Connect

Neutron characteristics of salt blanket micromodels containing eutectic mixtures of sodium, zirconium and uranium sulphides were measured on FKBN-2M, BIGR and MAKET installations. The effective fission cross sections of neptunium, plutonium, americium and curium isotopes were measured on the neutron spectra formed by micromodels. KEYWORDS: transmutation, minor actinides, fluoride salts, micromodel, critical assembly, neutron spectrum, multiplication coefficient, fission, effective cross section, nuclear track detector, nuclear data library

Novoselov, G. F.; Gavrilov, V. V.; Kuvshinov, M. (Mikhail); Bogdanov, V. M. (Vladimir Mikha?lovich); Maslov, Georgi? Vladimirovich,; Vyachin, V. (Vladimir); Mashnik, S. G. (Stepan G.); Gorelov, V. I. (Vladimir Ivanovich); Fomushkin, E. F.

2001-01-01

142

Prebiotic chemistry in eutectic solutions at the water-ice matrix.  

PubMed

A crystalline ice matrix at subzero temperatures can maintain a liquid phase where organic solutes and salts concentrate to form eutectic solutions. This concentration effect converts the confined reactant solutions in the ice matrix, sometimes making condensation and polymerisation reactions occur more favourably. These reactions occur at significantly high rates from a prebiotic chemistry standpoint, and the labile products can be protected from degradation. The experimental study of the synthesis of nitrogen heterocycles at the ice-water system showed the efficiency of this scenario and could explain the origin of nucleobases in the inner Solar System bodies, including meteorites and extra-terrestrial ices, and on the early Earth. The same conditions can also favour the condensation of monomers to form ribonucleic acid and peptides. Together with the synthesis of these monomers, the ice world (i.e., the chemical evolution in the range between the freezing point of water and the limit of stability of liquid brines, 273 to 210 K) is an under-explored experimental model in prebiotic chemistry. PMID:22660387

Menor-Salván, César; Marín-Yaseli, Margarita R

2012-08-21

143

Chlorate salts and solutions on Mars  

NASA Astrophysics Data System (ADS)

Chlorate (ClO3-) is an intermediate oxidation species between chloride (Cl-) and perchlorate (ClO4-), both of which were found at the landing site by the Wet Chemistry Lab (WCL). The chlorate ion is almost as stable as perchlorate, and appears to be associated with perchlorate in most terrestrial reservoirs (e.g. Atacama and Antarctica). It is possible that chlorate contributed to the ion sensor response on the WCL, yet was masked by the strong perchlorate signal. However, very little is known about chlorate salts and their effect on the stability of water. We performed evaporation rate experiments in our Mars simulation chamber, which enabled us to determine the activity of water for various concentrations. From this we constructed solubility diagrams for NaClO3, KClO3, Mg(ClO3)2 and Ca(ClO3)2, and determined the Pitzer parameters for each salt. Chlorate salt eutectic temperatures range from 270 K (KClO3) to 204 K (Mg(ClO3)2). Modeling the addition of chlorate to the initial WCL solutions shows that it precipitates in concentrations comparable to other common salts, such as gypsum and epsomite, and implies that chlorates may play an important role in the wet chemistry on Mars.

Hanley, Jennifer; Chevrier, Vincent F.; Berget, Deanna J.; Adams, Robert D.

2012-04-01

144

Refinement of Promising Coating Compositions for Directionally Cast Eutectics  

NASA Technical Reports Server (NTRS)

The successful application of high creep strength, directionally solidified gamma/gamma prime-delta (Ni-19.7Cb-6Cr-2.5Al) eutectic superalloy turbine blades requires the development of suitable coatings for airfoil, root and internal blade surfaces. In order to improve coatings for the gamma/gamma prime-delta alloy, the current investigation had the goals of (1) refining promising coating compositions for directionally solidified eutectics, (2) evaluating the effects of coating/ substrate interactions on the mechanical properties of the alloy, and (3) evaluating diffusion aluminide coatings for internal surfaces. Burner rig cyclic oxidation, furnace cyclic hot corrosion, ductility, and thermal fatigue tests indicated that NiCrAlY+Pt(63 to 127 micron Ni-18Cr-12Al-0.3Y + 6 micron Pt) and NiCrAlY(63 to 127 micron Ni-18Cr-12Al-0.3Y) coatings are capable of protecting high temperature gas path surfaces of eutectic alloy airfoils. Burner rig (Mach 0.37) testing indicated that the useful coating life of the 127 micron thick coatings exceeded 1000 hours at 1366 K (2000 deg F). Isothermal fatigue and furnance hot corrosion tests indicated that 63 micron NiCrAlY, NiCrAlY + Pt and platinum modified diffusion aluminide (Pt + Al) coating systems are capable of protecting the relatively cooler surfaces of the blade root. Finally, a gas phase coating process was evaluated for diffusion aluminizing internal surfaces and cooling holes of air-cooled gamma/gamma prime-delta turbine blades.

Strangman, T. E.; Felten, E. J.; Benden, R. S.

1976-01-01

145

Directional solidification of Pb-Sn eutectic with vibration  

NASA Technical Reports Server (NTRS)

Pb-Sn eutectic alloy was directionally solidified at 1.4 to 3.2 cm/hr with forced convection induced by axial vibration of the growth ampoule with a frequency of 10 to 40 Hz and an amplitude of 0.5 to 1.0 mm. To determine the exact growth rate, an interface demarcation technique was applied. The lamellar spacing was increased 10 to 40 percent in ingots solidified with vibration compared to those solidified without vibration. The average intensity of convection in the melt under axial vibration of the ampoule was estimated by comparing the experimental results with a theoretical model.

Caram, Rubens; Banan, Mohsen; Wilcox, William R.

1991-01-01

146

Solidification of NaCl-NaF eutectic in space  

NASA Technical Reports Server (NTRS)

Continuous and discontinuous NaF fibers, embedded in a NaCl matrix, have been produced in space and on earth, respectively. The production of continuous fibers in a eutectic mixture was attributed to the absence of convection current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and earth-grown ingots were made with a light microscope and a spectrometer. It was found that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of NaF fibers along the ingot axis.

Yue, A. S.; Yu, J. G.

1974-01-01

147

Supercooling effects in faceted eutectic Nb-Si alloys  

NASA Technical Reports Server (NTRS)

The effect of melt supercooling on the microstructure of an Nb-58 at. pct Si alloy is investigated experimentally using an electromagnetic levitation apparatus. It is found that, starting with an alloy nominally of eutectic composition, nucleation of Nb5Si3 occurs in the supercooled liquid first. Upon further cooling, the remaining liquid continues to supercool until the second phase, NbSi2 is nucleated, which is commonly accompanied by rapid recalescence. The primary phase exibits a eutectoid-type decomposition. The observations are discussed with reference to the results of quantitative microstructural measurements, compositional and thermal analysis, and preliminary thermodynamic modeling of the phase diagram.

Gokhale, A. B.; Sarkar, G.; Abbaschian, G. J.; Haygarth, J. C.; Wojcik, C.

1988-01-01

148

A method of applying eutectic coatings by centrifugal bimetallization from powder mixtures  

Microsoft Academic Search

reaction mixture [coating) [2] at the temperature* of occurrence of a eutectic reaction between the components of the mixture and the base metal with subsequent cooling [3]. The liquid phase formed significantly strengthens occurrence of the diffusion processes and the eutectic structure of the hardened layer is the optimum in the sense of hardness and plasticity. These characteristicsa re the

V. M. Golubets; M. V. Kindrachuk; M. I. Pashechko

1984-01-01

149

Control of mechanical and wear properties of a commercial Al-Si eutectic alloy  

Microsoft Academic Search

The properties examined as a function of microstructural modification were ultimate tensile strength, fracture elongation, Vickers hardness and wear resistance. The microstructural modification was achieved by rapid cooling and additions of small amounts of strontium and lithium master alloys into the eutectic melt. In all experiments the commercial ETIAL 140 alloy was cast instead of a high-purity aluminium-silicon eutectic. This

M. A. Savas; S. Altintas

1992-01-01

150

Solidification Behavior and Microstructural Evolution of Near-Eutectic Zn-Al Alloys under Intensive Shear  

NASA Astrophysics Data System (ADS)

The effect of intensive shear on the solidification behavior and microstructural evolution of binary Zn-Al alloys is presented at hypoeutectic, eutectic, and hypereutectic compositions. It is found that the intensive shear, applied on the eutectic melt prior to solidification at a temperature above but close the eutectic temperature, can significantly reduce the size of eutectic cells, but the solidified microstructure still remains the lamellar morphology. For applying intensive shear on the melt during solidification, the nucleation occurs at temperatures very close to the equilibrium condition and requires very small undercooling for both the primary solidification and the eutectic solidification. The intensive shear can significantly alter the microstructural morphology. In contrast to the dendritic morphology formed in the conventional solidification, the primary Al-rich phase in hypoeutectic Zn-Al alloy and the primary Zn-rich phase in hypereutectic Zn-Al alloy under intensive shear exhibit fine and spherical particles, respectively. The lamellae morphology of Zn-rich phase and Al-rich phase formed in the conventional eutectic solidification exhibit fine and spherical particles. The increase of intensity of shear promotes the independence of solid Zn-rich particles and Al-rich particles during the eutectic solidification, resulting in the uniform and separate distribution of two solid particles in the matrix. It is speculated that the high intensity of shear can result in the independent nucleation of individual eutectic phase throughout the whole melt, and the separate growth of solid phases in the subsequent solidification.

Ji, S.; Fan, Z.

2009-01-01

151

Eutectic grains in unmodified and strontium-modified hypoeutectic aluminum-silicon alloys  

NASA Astrophysics Data System (ADS)

Additions of strontium to hypoeutectic aluminum-silicon alloys modify the morphology of the eutectic silicon phase from a coarse platelike structure to a fine fibrous structure. Thermal analysis, interrupted solidification, and microstructural examination of sand castings in this work revealed that, in addition to a change in silicon morphology, modification with strontium also causes an increase in the size of eutectic grains. The eutectic grain size increases because fewer grains nucleate, possibly due to poisoning of the phosphorus-based nucleants, that are active in the unmodified alloy. A simple growth model is developed to estimate the interface velocity during solidification of a eutectic grain. The model confirms, independent of microstructural observations, that the addition of 100 ppm strontium increases the eutectic grain size by at least an order of magnitude compared with the equivalent unmodified alloy. The model predicts that the growth velocity varies significantly during eutectic growth. At low strontium levels, these variations may be sufficient to cause transitions between flake and fibrous silicon morphologies depending on the casting conditions. The model can be used to rationally interpret the eutectic grain structure and silicon morphology of fully solidified aluminum-silicon castings and, when coupled with reliable thermal data, can be used to estimate the eutectic grain size.

McDonald, Stuart D.; Dahle, Arne K.; Taylor, John A.; Stjohn, David H.

2004-06-01

152

Inverse Analysis of Eutectic Nucleation and Growth Kinetics in Hypoeutectic Al-Cu Alloys  

NASA Astrophysics Data System (ADS)

The nucleation and growth kinetics of equiaxed eutectic grains in hypoeutectic Al-Cu alloys has been investigated numerically and experimentally. Three-dimensional geometries of eutectic/primary phases obtained by X-ray microtomography (XMT) have been used to generate computational domains for use with a eutectic transformation model. The samples for XMT analysis were extracted from a series of small-scale castings of Al-20 wt pct Cu solidified with different cooling rates to obtain a variety of microstructures. The stochastic nucleation technique has been coupled with a deterministic cellular automaton (CA) model to simulate the nucleation and growth of eutectic grains within the interdendritic network characterized by the XMT analysis. An inverse analysis approach has been employed to quantify the deterministic nucleation and growth relationships in the eutectic solidification model. Metallographic measurements of eutectic size and density made on cast samples solidified with a variety of cooling rates and quenched at different times after the start of the eutectic transformation were used in the inverse analysis. The current approach provides a realistic description of eutectic grain evolution in multicomponent alloys.

Khajeh, Ehsan; Maijer, Daan M.

2011-01-01

153

Effects of boron on eutectic solidification in hypoeutectic Al–Si alloys  

Microsoft Academic Search

The effects of boron on the solidified microstructure and cooling curve of Al–7Si alloy were investigated. The results show that B has no significant effects on the shape factor of eutectic silicon but the mean area of eutectic silicon phase is reduced when the grain size is reduced within a certain range.

Geng Huiyuan; Li Yanxiang; Chen Xiang; Wang Xue

2005-01-01

154

Eutectic solidification in hypoeutectic Al–Si alloys: electron backscatter diffraction analysis  

Microsoft Academic Search

Nucleation and growth of the eutectic in hypoeutectic Al–Si foundry alloys has been investigated by the electron backscatter diffraction (EBSD) mapping technique using a scanning electron microscope (SEM). Sample preparation procedures for optimizing mapping have been developed. To obtain a sufficiently smooth surface from a cast Al–Si eutectic microstructure for EBSD mapping, an appropriate preparation technique by ion milling was

K Nogita; A. K Dahle

2001-01-01

155

A fully coupled 2D model of equiaxed eutectic solidification  

SciTech Connect

We propose a model of equiaxed eutectic solidification that couples the macroscopic level of heat diffusion with the microscopic level of nucleation and growth of the eutectic grains. The heat equation with the source term corresponding to the latent heat release due to solidification is calculated numerically by means of an implicit finite difference method. In the time stepping scheme, the evolution of solid fraction is deduced from a stochastic model of nucleation and growth which uses the local temperature (interpolated from the FDM mesh) to determine the local grain density and the local growth rate. The solid-liquid interface of each grain is tracked by using a subdivision of each grain perimeter in a large number of sectors. The state of each sector (i.e. whether it is still in contact with the liquid or already captured by an other grain) and the increase of radius of each grain during one time step allows one to compute the increase of solid fraction. As for deterministic models, the results of the model are the evolution of temperature and of solid fraction at any point of the sample. Moreover the model provides a complete picture of the microstructure, thus not limiting the microstructural information to the average grain density but allowing one to compute any stereological value of interest. We apply the model to the solidification of gray cast iron.

Charbon, Ch.; LeSar, R.

1995-12-31

156

Anthracene + Pyrene Solid Mixtures: Eutectic and Azeotropic Character  

PubMed Central

To better characterize the thermodynamic behavior of a binary polycyclic aromatic hydrocarbon mixture, thermochemical and vapor pressure experiments were used to examine the phase behavior of the anthracene (1) + pyrene (2) system. A solid-liquid phase diagram was mapped for the mixture. A eutectic point occurs at 404 K at x1 = 0.22. A model based on eutectic formation can be used to predict the enthalpy of fusion associated with the mixture. For mixtures that contain x1 < 0.90, the enthalpy of fusion is near that of pure pyrene. This and X-ray diffraction results indicate that mixtures of anthracene and pyrene have pyrene-like crystal structures and energetics until the composition nears that of pure anthracene. Solid-vapor equilibrium studies show that mixtures of anthracene and pyrene form solid azeotropes at x1 of 0.03 and 0.14. Additionally, mixtures at x1 = 0.99 sublime at the vapor pressure of pure anthracene, suggesting that anthracene behavior is not significantly influenced by x2 = 0.01 in the crystal structure.

Rice, James W.; Fu, Jinxia; Suuberg, Eric M.

2010-01-01

157

Microstructural development and mechanical behavior of eutectic bismuth-tin and eutectic indium-tin in response to high temperature deformation  

Microsoft Academic Search

The mechanical behavior and microstructure of eutectic Bi-Sn and In-Sn solders were studied in parallel in order to better understand high temperature deformation of these alloys. Bi-Sn solder joints were made with Cu substrates, and In-Sn joints were made with either Cu or Ni substrates. The as-cast microstructure of Bi-Sn is complex regular, with the two eutectic phases interconnected in

Goldstein

1993-01-01

158

Spectroscopic and thermal investigations of the fluoroaluminate complex formation in NaF-KF and LiF-NaF-KF eutectics.  

PubMed

The dissolution and complex formation of fluoroaluminates in two eutectic alkalifluoride mixtures, NaF-KF (FNAK) and LiF-NaF-KF (FLINAK), have been investigated by Raman, NMR, and thermal analysis. Melting and dissolution took place stepwise. The eutectic alkalifluoride mixtures with minor amounts of dissolved fluoroaluminate salts started melting at around 460 and 740 degrees C for FLINAK and FNAK mixtures, respectively. Total melting/dissolution of mixtures with 9-11 mol % aluminum fluoro salts added took place near 780 degrees C in the FLINAK solvent and at approximately 900 degrees C for FNAK solutions. The solidified melts were characterized by Raman bands at 561 (nu(1)), 391 (nu(2)), and 328 cm(-1) (nu(5)) and a (27)Al NMR chemical shift near 0 ppm originating from isolated AlF(6)(3-) octahedral ions. The Raman and NMR signals due to AlF(6)(3-) were also observed at temperatures where the samples were only partly melted. Upon total melting, a pronounced dissociation of AlF(6)(3-) into AlF(5)(2-) and fluoride ions took place. At even higher temperatures, the equilibrium was displaced in favor of AlF(5)(2-) in the FNAK solvent. The AlF(5)(2-) ion was characterized by an intensive Raman band at 558 cm(-1) and an increasingly positive (27)Al chemical shift with raising temperature, e.g., of 16 ppm at 935 degrees C. PMID:12639123

von Barner, J H; Bessada, C; Berg, R W

2003-03-24

159

Evaporation of mercury impurity from liquid lead-bismuth eutectic  

NASA Astrophysics Data System (ADS)

The equilibrium evaporation of mercury from dilute solutions in liquid lead-bismuth eutectic (LBE) was studied in argon atmosphere. Mercury present as impurity in LBE was evaporated and detected by atomic fluorescence spectroscopy. A method which could accurately simulate the experimental data was developed. Coefficients of the Henry constant temperature correlation for mercury dissolved in LBE were determined. Experiments with samples from several different batches of LBE revealed that mercury at mole fractions between 10-6 and 10-12 and temperatures between 150 and 350 °C evaporated from liquid LBE close to ideal behavior. Evaporation of mercury from solid LBE on the other hand was unexpectedly high. These results are important for safety evaluations of LBE based spallation targets and accelerator driven systems.

Aerts, A.; Danaci, S.; Gonzalez Prieto, B.; Van den Bosch, J.; Neuhausen, J.

2014-05-01

160

Self Assembled Structures by Directional Solidification of Eutectics  

NASA Technical Reports Server (NTRS)

Interest in ordered porous structures has grown because of there unique properties such as photonic bandgaps, high backing packing density and high surface to volume ratio. Inspired by nature, biometric strategies using self assembled organic molecules dominate the development of hierarchical inorganic structures. Directional solidification of eutectics (DSE) also exhibit self assembly characteristics to form hierarchical metallic and inorganic structures. Crystallization of diphasic materials by DSE can produce two dimensional ordered structures consisting of rods or lamella. By selective removal of phases, DSE is capable to fabricate ordered pore arrays or ordered pin arrays. Criteria and limitations to fabricate hierarchical structures will be presented. Porous structures in silicon base alloys and ceramic systems will be reported.

Dynys, Frederick W.; Sayir, Ali

2004-01-01

161

Electroplated Fe films prepared from a deep eutectic solvent  

NASA Astrophysics Data System (ADS)

Electroplating of Fe films was carried out from choline chloride-ethylene glycol types of DES (Deep Eutectic Solvent). We investigated magnetic properties of the plated Fe films and evaluated the productivity for the electroplating process. Consequently, we found that surface morphology and current efficiency of the plated films were affected by the bath temperature. We obtained the Fe films with relatively smooth surface and high current efficiency in the bath temperature range from 70 to 110 °C. The deposition rate for our process depended on the current density, and we obtained high deposition rate value of approximately 120 ?m/h. We also obtained high current efficiency values of approximately 90% in the wide range of plating time. These results indicate that the DES-based bath has industrial advantages for mass-producing Fe films. Therefore, we conclude that the DES-based bath is an attractive plating bath for Fe films.

Yanai, T.; Shiraishi, K.; Shimokawa, T.; Watanabe, Y.; Ohgai, T.; Nakano, M.; Suzuki, K.; Fukunaga, H.

2014-05-01

162

On the phenomenology of tilted domains in lamellar eutectic growth  

NASA Astrophysics Data System (ADS)

We show that, due to the coupling between tilt (amplitude of the antisymmetric part of the font profile) and phase dynamics, the phenomenology of tilt domains of finite width proposed by Coullet et al. within the assumption of a subcritical homogeneous tilt bifurcation retains the same qualitative features when this bifurcation is direct, as is the case for lamellar eutectics. Nous montrons que, du fait du couplage entre les dynamiques d'inclinaison (amplitude de la partie impaire du profil de front) et de phase, la phénoménologie des domaines d'inclinaison de largeur finie proposée par Coullet et al. pour le cas d'une bifurcation d'inclinaison homogène sous critique garde les mêmes caractéristiques qualitatives quand cette bifurcation est directe, comme c'est le cas pour la croissance eutectique lamellaire.

Caroli, B.; Caroli, C.; Fauve, S.

1992-03-01

163

Traceable Co-C eutectic points for thermocouple calibration  

SciTech Connect

National Measurement Institute of Australia (NMIA) has developed a miniature crucible design suitable for measurement by both thermocouples and radiation thermometry, and has established an ensemble of five Co-C eutectic-point cells based on this design. The cells in this ensemble have been individually calibrated using both ITS-90 radiation thermometry and thermocouples calibrated on the ITS-90 by the NMIA mini-coil methodology. The assigned ITS-90 temperatures obtained using these different techniques are both repeatable and consistent, despite the use of different furnaces and measurement conditions. The results demonstrate that, if individually calibrated, such cells can be practically used as part of a national traceability scheme for thermocouple calibration, providing a useful intermediate calibration point between Cu and Pd.

Jahan, F.; Ballico, M. J. [National Measurement Institute, Lindfield, NSW 2070 (Australia)] [National Measurement Institute, Lindfield, NSW 2070 (Australia)

2013-09-11

164

Powder eutectic coating with Al3Ti for steels  

NASA Astrophysics Data System (ADS)

Plates and round bars made of a pure iron or a carbon steel (JIS-S45C) have successfully been coated with Al3Ti powder by the “powder eutectic coating” method. The coated layers are found to show graded microstructures, where the concentrations of Fe, Al, and Ti change gradually from the surface toward the inside of a specimen. The microstructure of the coated layer consists of Al3Ti, ?3 (Al22Fe3Ti8), ?2 (Al2FeTi), and B2 (FeAl). When the coated specimens were subjected to heat-cycling tests between 293 and 973 K, they showed no cracking, no peeling, little oxidation, and no significant changes in microstructure.

Kafuku, H.; Tomota, Y.; Suzuki, T.; Isaka, M.

2002-10-01

165

Eutectic superalloys by edge-defined, film-fed growth  

NASA Technical Reports Server (NTRS)

The feasibility of producing directionally solidified eutectic alloy composites by edge-defined, film-fed growth (EFG) was carried out. The three eutectic alloys which were investigated were gamma + delta, gamma/gamma prime + delta, and a Co-base TaC alloy containing Cr and Ni. Investigations into the compatibility and wettability of these metals with various carbides, borides, nitrides, and oxides disclosed that compounds with the largest (negative) heats of formation were most stable but poorest wetting. Nitrides and carbides had suitable stability and low contact angles but capillary rise was observed only with carbides. Oxides would not give capillary rise but would probably fulfill the other wetting requirements of EFG. Tantalum carbide was selected for most of the experimental portion of the program based on its exhibiting spontaneous capillary rise and satisfactory slow rate of degradation in the liquid metals. Samples of all three alloys were grown by EFG with the major experimental effort restricted to gamma + delta and gamma/gamma prime + delta alloys. In the standard, uncooled EFG apparatus, the thermal gradient was inferred from the growth speed and was 150 to 200 C/cm. This value may be compared to typical gradients of less than 100 C/cm normally achieved in a standard Bridgman-type apparatus. When a stream of helium was directed against the side of the bar during growth, the gradient was found to improve to about 250 C/cm. In comparison, a theoretical gradient of 700 C/cm should be possible under ideal conditions, without the use of chills. Methods for optimizing the gradient in EFG are discussed, and should allow attainment of close to the theoretical for a particular configuration.

Hurley, G. F.

1975-01-01

166

Characteristics and sintering behaviour of 3 mol % Y 2 O 3 -ZrO 2 powders synthesized by reaction in molten salts  

Microsoft Academic Search

Yttria-stabilized tetragonal zirconia powders have been synthesized by reaction in molten salts at 450 °C. To obtain a Y2O3-ZrO2 solid solution powder, it was necessary to use yttrium salts (not yttrium oxide directly) in molten NaNO3-KNO3 eutectic. The agglomeration state of the powders depended on their washing conditions. An alcohol-washed powder containing soft agglomerates led to a fine-grained and high-density

M. Descemond; C. Brodhag; F. Thevenot; B. Durand; M. Jebrouni; M. Roubin

1993-01-01

167

Effects of ultrasound and temperature on copper electro reduction in Deep Eutectic Solvents (DES).  

PubMed

This paper concerns a preliminary study for a new copper recovery process from ionic solvent. The aim of this work is to study the reduction of copper in Deep Eutectic Solvent (choline chloride-ethylene glycol) and to compare the influence of temperature and the ultrasound effects on kinetic parameters. Solutions were prepared by dissolution of chloride copper salt CuCl2 (to obtain Copper in oxidation degree II) or CuCl (to obtain Copper in oxidation degree I) and by leaching metallic copper directly in DES. The spectrophotometry UV-visible analysis of the leached solution showed that the copper soluble form obtained is at oxidation degree I (Copper I). Both cyclic voltammetry and linear voltammetry were performed in the three solutions at three temperatures (25, 50 and 80°C) and under ultrasonic conditions (F=20kHz, PT=5.8W) to calculate the mass transfer diffusion coefficient kD and the standard rate coefficient k°. These parameters are used to determine that copper reduction is carried out via a mixed kinetic-diffusion control process. Temperature and ultrasound have the same effect on mass transfer for reduction of Cu(II)/Cu(I). On the other hand, temperature is more beneficial than ultrasound for mass transfer of Cu(I)/Cu. Standard rate constant improvement due to temperature increase is of the same order as that obtained with ultrasound. But, by combining higher temperature and ultrasound (F=20kHz, PT=5.6W at 50°C), reduction limiting current is increased by a factor of 10 compared to initial conditions (T=25°C, silent), because ultrasonic stirring is more efficient in lower viscosity fluid. These values can be considered as key-parameters in the design of copper recovery in global processes using ultrasound. PMID:24629581

Mandroyan, Audrey; Mourad-Mahmoud, Mahmoud; Doche, Marie-Laure; Hihn, Jean-Yves

2014-11-01

168

Spasmodic growth during the rapid solidification of undercooled Ag-Cu eutectic melts  

NASA Astrophysics Data System (ADS)

A melt fluxing technique has been used to undercool Ag-Cu eutectic alloy by 10-70 K and the subsequent recalescence has been studied using high speed imaging. Spasmodic growth of the solidification front was observed, in which the growth front would make a series of quasi-periodic jumps separated by extended periods during which time growth appeared to arrest. Evidence of this previously unreported mode of growth is presented. The high speed images and microstructural evidence support the theory that anomalous eutectics form by the growth and subsequent remelting of eutectic dendrites.

Clopet, C. R.; Cochrane, R. F.; Mullis, A. M.

2013-01-01

169

Ice/hydrohalite crystallization structures in sub-eutectic freezing experiments in the system NaCl-H20 and possible implications for the properties of frozen brines in Europa: A preliminary report  

NASA Astrophysics Data System (ADS)

Sulfates are likely to be the most abundant solutes in the subsurface Europan liquid ocean. NaCl may also be a significant component of such liquids based on the compositions of stony meteorites like those thought to be among the source materials for the silicates in Europa's interior. The system NaCl-H20 exhibits a eutectic at -20.8°C and 23.3 weight percent NaCl between ice Ih and hydrohalite (NaCl.2H20). This low eutectic temperature compared to Mg and Na sulfate hydrate/ice eutectics indicates that hydrohalite should be among the last salts to crystallize in brine upwellings along rifts and other places where resurfacing by melt extrusion occurs on Europa. We conducted a suite of freezing experiments on NaCl brines with 20.3, 23.3, and 26.6 (saturated) weight percent NaCl by holding these liquids at a few degrees below the eutectic temperature. These runs produced ice-rich, eutectic and hydrohalite-rich aggregates of both phases, respectively, as confirmed by cryogenic x-ray diffraction and x-ray fluorescence spectroscopy. Based on direct observations of crystals forming at the tops and bottoms of the sample chambers and on refractive index measurements of subsequently melted sample material, marked fractional crystallization and segregation by density of ice, hydrohalite, and residual liquids occurred in the 20.3 and 26.6% samples and less so in for the eutectic composition. Crystallization of very fine grained eutectic intergrowths was recognized in cryogenic SEM images of all these samples and they were especially prominent in samples frozen from saturated brine. These samples were very difficult to cleave compared to pure polycrystalline ice, and hence are likely to have high fracture toughness. Direct measurements of this property and also the effects of partial melting on ductile flow rates are planned on such samples. Refracturing of such regions of fine eutectoid ice/hydrohalite intergrowths is likely to be inhibited in refrozen rifts compared to more ice-rich regions on Europa.

Rieck, K.; Kirby, S. H.; Stern, L. A.

2005-12-01

170

Dissolution of Eutectic ?-Mg17Al12 Phase in Magnesium AZ91 Cast Alloy at Temperatures Close to Eutectic Temperature  

NASA Astrophysics Data System (ADS)

Knowledge on the dissolution kinetics of ?-eut phase in cast Mg AZ91 alloy at temperatures close to the eutectic temperature is very useful for various processes of the alloy. In the present study, dissolution of ?-eut phase has been investigated experimentally and considered theoretically. Results have confirmed that the kinetics of ?-eut dissolution is basically diffusion controlled. Optimum times for dissolution heat treatment practice of different sizes of cast microstructure which are cooling rate dependant during casting could be suggested based on the present calculation. For fusion welding of the alloy, the present results indicate the difficulty of having a heating rate lower than the critical value (“critical heating rate”) for a significant reduction of the phase to avoid constitutional liquation.

Zhu, Tianping; Chen, Zhan W.; Gao, Wei

2010-08-01

171

Mass-transfer characteristics of nitrate-based salt mixtures. [Heat transfer fluid for solar thermal power systems  

SciTech Connect

Molten eutectic NaNO/sub 3/-KNO/sub 3/ is being circulated in three thermal-convection loops constructed of alloy 800 and types 304L and 316 stainless steel. The loops are operated at a maximum salt temperature of 595/sup 0/C and a salt temperature differential of 235/sup 0/C. Corrosion specimens contained within each loop are withdrawn for periodic determinations of weight and microstructural changes. Salt samples are analyzed at selected intervals to monitor changes in the composition of the salt. Controlled potential voltammetry is also used to follow changes in the oxidation potential of the salt. Preliminary results indicate low corrosion rates for the austenitic stainless steels in flowing NaNO/sub 3/-KNO/sub 3/. Corrosion rate data from these tests will be used to develop a kinetic model for the mass transfer of Cr, Ni, and Fe as a function of temperature gradient along the salt flow path.

DeVan, J.H.; Tortorelli, P.F.

1980-01-01

172

Viscosity Measurement of Molten Carbonate Salt.  

National Technical Information Service (NTIS)

This report describes research on the eutectic property values of lithium/sodium/potassium carbonate. This carbonate eutectic is the leading candidate for high-temperature heat transfer fluids for a direct-absorption receiver concept being researched at t...

G. J. Janz

1986-01-01

173

Fission product ion exchange between zeolite and a molten salt  

NASA Astrophysics Data System (ADS)

The electrometallurgical treatment of spent nuclear fuel (SNF) has been developed at Argonne National Laboratory (ANL) and has been demonstrated through processing the sodium-bonded SNF from the Experimental Breeder Reactor-II in Idaho. In this process, components of the SNF, including U and species more chemically active than U, are oxidized into a bath of lithium-potassium chloride (LiCl-KCl) eutectic molten salt. Uranium is removed from the salt solution by electrochemical reduction. The noble metals and inactive fission products from the SNF remain as solids and are melted into a metal waste form after removal from the molten salt bath. The remaining salt solution contains most of the fission products and transuranic elements from the SNF. One technique that has been identified for removing these fission products and extending the usable life of the molten salt is ion exchange with zeolite A. A model has been developed and tested for its ability to describe the ion exchange of fission product species between zeolite A and a molten salt bath used for pyroprocessing of spent nuclear fuel. The model assumes (1) a system at equilibrium, (2) immobilization of species from the process salt solution via both ion exchange and occlusion in the zeolite cage structure, and (3) chemical independence of the process salt species. The first assumption simplifies the description of this physical system by eliminating the complications of including time-dependent variables. An equilibrium state between species concentrations in the two exchange phases is a common basis for ion exchange models found in the literature. Assumption two is non-simplifying with respect to the mathematical expression of the model. Two Langmuir-like fractional terms (one for each mode of immobilization) compose each equation describing each salt species. The third assumption offers great simplification over more traditional ion exchange modeling, in which interaction of solvent species with each other is considered. (Abstract shortened by UMI.)

Gougar, Mary Lou D.

174

Electrolyte salts for power sources  

DOEpatents

Electrolyte salts are disclosed for power sources comprising salts of phenyl polysulfonic acids and phenyl polyphosphonic acids. The preferred salts are alkali and alkaline earth metal salts, most preferably lithium salts. 2 figs.

Doddapaneni, N.; Ingersoll, D.

1995-11-28

175

The Effect of Eutectic Microstructures on the Mechanical Properties of Ceramic Oxides.  

National Technical Information Service (NTIS)

Various experimental techniques for the production of unidirectionally solidified oxide eutectics were examined. These included a modified Bridgman-Starkbarger technique and bottom cooling of melts held in platinum crucibles. It was concluded that the bes...

C. O. Hulse J. A. Batt

1974-01-01

176

Microstructure of directionally solidified Ti-Fe eutectic alloy with low interstitial and high mechanical strength  

NASA Astrophysics Data System (ADS)

The performance of Ti alloys can be considerably enhanced by combining Ti and other elements, causing an eutectic transformation and thereby producing composites in situ from the liquid phase. This paper reports on the processing and characterization of a directionally solidified Ti-Fe eutectic alloy. Directional solidification at different growth rates was carried out in a setup that employs a water-cooled copper crucible combined with a voltaic electric arc moving through the sample. The results obtained show that a regular fiber-like eutectic structure was produced and the interphase spacing was found to be a function of the growth rate. Mechanical properties were measured using compression, microindentation and nanoindentation tests to determine the Vickers hardness, compressive strength and elastic modulus. Directionally solidified eutectic samples presented high values of compressive strength in the range of 1844-3000 MPa and ductility between 21.6 and 25.2%.

Contieri, R. J.; Lopes, E. S. N.; Taquire de La Cruz, M.; Costa, A. M.; Afonso, C. R. M.; Caram, R.

2011-10-01

177

Study of zirconium/stainless steel interface in tubular junctions made by eutectic diffusion.  

National Technical Information Service (NTIS)

Reprocessing plants and pressurized water loops for fuels irradiation have zirconium (or zircaloy) and austenitic stainless steel tubes connected by mean of diffusion bondings. These bondings are achieved by producing an eutectic film at the interface bet...

J. Y. Blanc R. Le Goff P. Regnier

1990-01-01

178

Growth of eutectic silicon from primary silicon crystals in aluminium-silicon alloys  

SciTech Connect

Technological interest in aluminium-silicon alloys derives, fundamentally, from their excellent moulding properties provided by the presence of silicon. In addition, they possess high thermal and electrical conductivities and good corrosion resistance. The possibility of modification of their cast structure by adding small quantities of alkaline and alkaline-earth elements makes their mechanical characteristics very competitive. Metallographic observations of the structures of primary and eutectic silicon crystals, and their possible synergistic influence, provide useful data on the critical stages of formation and growth of eutectic silicon phase. The nucleation and growth of eutectic silicon, removed from the cooperative precipitation zone, induce refinement in crystal size and, therefore, an improvement of the mechanical properties of the moulded structure. The aim of this investigation was to observe the influence of primary silicon crystals on the nucleation and growth of eutectic silicon.

Criado, A.J.; Martinez, J.A.; Calabres, R. [Complutense Univ. of Madrid (Spain). Dept. of Materials Science and Metallurgical Engineering] [Complutense Univ. of Madrid (Spain). Dept. of Materials Science and Metallurgical Engineering

1997-01-01

179

Hypereutectic heat storage alloy: Final report, Silicon shell integrity in molten Al-Si eutectic  

SciTech Connect

As a part of a program to evaluate the feasibility of using silicon encapsulated spheres of aluminum--silicon eutectic for thermal energy storage at temperatures near 650/degree/C, experiments were done to test the dimensional stability of the interface between silicon and the eutectic to thermal cycling. Cycled samples were sectioned and examined by optical micrography and by electron microscopy (SEM/EDX) techniques. Little or no degradation of the interface was observed at 600/degree/C (eutectic temperature 577/degree/C) while catastrophic degradation occurred at 700/degree/C. AT 650/degree/C interpenetration of 0.1/endash/0.2 mm was observed between the silicon and the eutectic alloys, with occasional larger (3/endash/4 mm) intrusions. 11 refs., 15 figs., 3 tabs.

Bennett, M.R.; Braunstein, J.

1988-06-01

180

Effect of boron on the microstructure of near-eutectic Al-Si alloys  

SciTech Connect

The effect of boron on the microstructure of a near-eutectic Al-Si alloy (ZL109) was investigated by scanning electron microscopy (SEM) and electron beam microprobe analysis (EPMA). It was found that {alpha}-Al dendrites and eutectic clusters were significantly refined by the addition of boron. Another interesting discovery is that the near-eutectic alloy exhibited hypereutectic structure characteristics when the level of boron added exceeds 0.3%, i.e., primary Si is precipitated in the eutectic microstructure. A new type of nucleation substrate for the primary Si is found, Al {sub x}Ca {sub m}B {sub n}Si. This appears to be the main reason for the precipitation of primary Si.

Wu Yuying [Key Laboratory of Materials Liquid Structure and Heredity, Ministry of Education, Shandong University, Jinan 250061, Shandong (China)]. E-mail: wyy532001@163.com; Liu Xiangfa [Key Laboratory of Materials Liquid Structure and Heredity, Ministry of Education, Shandong University, Jinan 250061, Shandong (China); Bian Xiufang [Key Laboratory of Materials Liquid Structure and Heredity, Ministry of Education, Shandong University, Jinan 250061, Shandong (China)

2007-02-15

181

High-temperature non-eutectic indium-tin joints fabricated by a fluxless process  

Microsoft Academic Search

A new alternative solder joint made of a non-eutectic indium–tin (In–Sn) multilayer composite deposited in high vacuum is reported. The unique features of this design are that it is fluxless, oxidation-free, and more importantly the fabricated joint achieves a re-melting temperature significantly higher than the bonding temperature. The In–Sn non-eutectic multilayer structure with a thin gold film evaporated as a

Ricky W Chuang; Chin C Lee

2002-01-01

182

Localized silicon fusion and eutectic bonding for MEMS fabrication and packaging  

Microsoft Academic Search

Silicon fusion and eutectic bonding processes based on the technique of localized heating have been successfully demonstrated. Phosphorus-doped polysilicon and gold films are applied separately in the silicon-to-glass fusion bonding and silicon-to-gold eutectic bonding experiments. These films are patterned as line-shape resistive heaters with widths of 5 or 7 ?m for the purpose of heating and bonding. In the experiments,

Y. T. Cheng; Liwei Lin; Khalil Najafi

2000-01-01

183

Microstructure and mechanical properties of Fe–Cr–C eutectic composites  

Microsoft Academic Search

In the present investigation, an Fe–Cr–C eutectic alloy was prepared from industry-grade materials and subjected to unidirectional solidification (UDS), through which new types of fibre reinforced composites, eutectic composites, were generated. The composites obtained were examined using X-ray diffraction (XRD), electron microprobe and field emission scanning electron microscopy (FESEM). According to XRD, the composites consist of three phases, i.e. ?,

Liming Lu; Hiroshi Soda; Alexander McLean

2003-01-01

184

Eutectic structures in friction spot welding joint of aluminum alloy to copper  

NASA Astrophysics Data System (ADS)

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl2 eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.

Shen, Junjun; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; dos Santos, Jorge F.

2014-05-01

185

Studies on the dry sliding wear behaviour of hypoeutectic and eutectic Al–Si alloys  

Microsoft Academic Search

The effect of grain refiner and or modifier on the wear behaviour of hypoeutectic (Al–0.2, 2, 3, 4, 5 and 7Si) and eutectic (Al–12Si) alloys has been investigated using a Pin-On-Disc machine. Various parameters such as alloy composition, normal pressure, sliding speed and sliding distance were studied on the hypoeutectic and eutectic Al–Si alloys. The cast master alloys (Al–5Ti–1B, Al–1Ti–3B

S. A. Kori; T. M. Chandrashekharaiah

2007-01-01

186

Eutectic grains in unmodified and strontium-modified hypoeutectic aluminum-silicon alloys  

Microsoft Academic Search

Additions of strontium to hypoeutectic aluminum-silicon alloys modify the morphology of the eutectic silicon phase from a\\u000a coarse platelike structure to a fine fibrous structure. Thermal analysis, interrupted solidification, and microstructural\\u000a examination of sand castings in this work revealed that, in addition to a change in silicon morphology, modification with\\u000a strontium also causes an increase in the size of eutectic

Stuart D. McDonald; Arne K. Dahle; John A. Taylor; David H. StJohn

2004-01-01

187

Preliminary study of the electrolysis of aluminum sulfide in molten salts  

SciTech Connect

A preliminary laboratory-scale study of the electrolysis of aluminum sulfide in molten salts investigated the (1) solubility of Al/sub 2/S/sub 3/ in molten salts, (2) electrochemical behavior of Al/sub 2/S/sub 3/, and (3) electrolysis of Al/sub 2/S/sub 3/ with the determination of current efficiency as a function of current density. The solubility measurements show that MgCl/sub 2/-NaCl-KCl eutectic electrolyte at 1023 K can dissolve up to 3.3 mol % sulfide. The molar ratio of sulfur to aluminum in the eutectic is about one, which suggests that some sulfur remains undissolved, probably in the form of MgS. The experimental data and thermodynamic calculations suggest that Al/sub 2/S/sub 3/ dissolves in the eutectic to form AlS/sup +/ species in solution. Addition of AlCl/sub 3/ to the eutectic enhances the solubility of Al/sub 2/S/sub 3/; the solubility increases with increasing AlCl/sub 3/ concentration. The electrode reaction mechanism for the electrolysis of Al/sub 2/S/sub 3/ was elucidated by using linear sweep voltammetry. The cathodic reduction of aluminum-ion-containing species to aluminum proceeds by a reversible, diffusion-controlled, three-electron reaction. The anodic reaction involves the two-electron discharge of sulfide-ion-containing species, followed by the fast dimerization of sulfur atoms to S/sub 2/. Electrolysis experiments show that Al/sub 2/S/sub 3/ dissolved in molten MgCl/sub 2/-NaCl-KCl eutectic or in eutectic containing AlCl/sub 3/ can be electrolyzed to produce aluminum and sulfur. In the eutectic at 1023 K, the electrolysis can be conducted up to about 300 mA/cm/sup 2/ for the saturation solubility of Al/sub 2/S/sub 3/. Although these preliminary results are promising, additional studies are needed to elucidate many critical operating parameters before the technical potential of the electrolysis can be accurately assessed. 20 figures, 18 tables.

Minh, N.Q.; Loutfy, R.O.; Yao, N.P.

1983-02-01

188

Prussian blue nanospheres synthesized in deep eutectic solvents  

NASA Astrophysics Data System (ADS)

A novel route for controlled synthesis of Prussian blue nanospheres (PB NSs) with different sizes by using deep eutectic solvents (DES) as both solvent and template provider was demonstrated. The size-controlled PB NSs were obtained directly by the coordination of Fe(CN)64- ion with Fe3+ ion in the DES. The probable mechanism of formation of PB NSs was discussed based on the characterization results of UV-visible, X-ray diffraction, X-ray photoelectronic spectrum and transfer electron microscopy. Furthermore, the electrochemical and electrocatalytic properties of the synthesized PB NSs were investigated, and it has demonstrated that the PB NSs exhibited excellent catalytic activity for H2O2 reduction, and then extended this strategy to glucose sensing, by detecting H2O2 formed from the enzymatic reaction of glucose oxidase with its substrate glucose. The linear calibration range for glucose was from 0.9 ?M to 0.12 mM, with a correlation coefficient of 0.998. The limit of detection was 0.3 ?M and the sensitivity was 61.7 A cm-2 M-1. The present study provides a general platform for the controlled synthesis of novel nanomaterials in DES and can be extended to other optical, electronic and magnetic nanocompounds.A novel route for controlled synthesis of Prussian blue nanospheres (PB NSs) with different sizes by using deep eutectic solvents (DES) as both solvent and template provider was demonstrated. The size-controlled PB NSs were obtained directly by the coordination of Fe(CN)64- ion with Fe3+ ion in the DES. The probable mechanism of formation of PB NSs was discussed based on the characterization results of UV-visible, X-ray diffraction, X-ray photoelectronic spectrum and transfer electron microscopy. Furthermore, the electrochemical and electrocatalytic properties of the synthesized PB NSs were investigated, and it has demonstrated that the PB NSs exhibited excellent catalytic activity for H2O2 reduction, and then extended this strategy to glucose sensing, by detecting H2O2 formed from the enzymatic reaction of glucose oxidase with its substrate glucose. The linear calibration range for glucose was from 0.9 ?M to 0.12 mM, with a correlation coefficient of 0.998. The limit of detection was 0.3 ?M and the sensitivity was 61.7 A cm-2 M-1. The present study provides a general platform for the controlled synthesis of novel nanomaterials in DES and can be extended to other optical, electronic and magnetic nanocompounds. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr31830j

Sheng, Qinglin; Liu, Ruixiao; Zheng, Jianbin

2012-10-01

189

Theoretical Investigation of Binary Eutectic Alloy Nanoscale Phase Diagrams  

NASA Astrophysics Data System (ADS)

Recently, embedded binary eutectic alloy nanostructures (BEANs) have drawn some attention. A previously calculated equilibrium structure map predicts four possible nanocrystal alloy morphologies: phase-separated, bi-lobe, core-shell and inverse core-shell governed by two dimensionless interface energy parameters. The shape of the bilobe nanoparticles is obtained by finding the surface area of all interfaces that minimizes the overall energy, while also maintaining mechanical equilibrium at the triple point. Two representative alloy systems displaying eutectic phase diagrams and negligible solid solubility were chosen: GeSn and AuGe. GeSn samples were prepared by sequential implantation of Ge and Sn into SiO2. AuGe samples were prepared by implanting Ge within Au-doped silica films. Transmission electron microscopy images revealed bi-lobe nanocrystals in both samples. Therefore, the interface energies in both systems must be such that the dimensionless parameters lie in the region of bi-lobe stability. Careful analysis of the bi-lobe structure leads to the determination of two dimensionless length scales, which describe the bi-lobe independent of the size of the nanoparticle. These two parameters, eta 1 and eta 2 can be used to calculate contours of equal eta 1 and eta 2 over the entire range of bi-lobe stability. Experimental measurement and comparison to predicted structures leads to determination of acting dimensionless interface energies. Experimentally available wetting data is then used to calculate the remaining interface energies in the system. gamma Ge(s)/SiO2 was found to be between 0.82-0.99 J/m2 . gamma Ge0.22Sn0.78(l)/SiO2 and gamma Au0.53Ge0.47(l)/SiO2 are determined to be 1.20 and 0.94 J/m2 , respectively. To investigate the possibility of size effects at the nanoscale, size dependent phase diagrams for the AuGe and GeSn system are determined. This is done by the theoretical approach first outlined by Weissmueller et al., which takes into account the energy contribution of the various morphologies listed above. Results from this calculation are compared to those using the tangent line construction approach. The composition dependent surface energies of binary alloy liquids required in this calculation are determined using Butler's equation.

Boswell-Koller, Cosima Nausikaa

190

A fundamental investigation into the effects of eutectic formation on transmembrane transport.  

PubMed

Eutectic systems enhance the permeation of therapeutic agents across biological barriers, but the mechanism by which this occurs has not previously been elucidated. Using human skin it has proven difficult to isolate the fundamental effects of eutectic formation on molecule diffusion and partition from those that arise as a consequence of the simultaneous application of two agents. The aim of this work was to employ a model hydrophobic membrane to understand the fundamental permeation characteristics of two agents when applied as a eutectic mixture. Lidocaine and prilocaine were selected as model agents and infinite-dose permeation studies were carried out using pre-calibrated Franz diffusion cells with two thicknesses of silicone membrane. Membrane solubility was determined by HCl solution extraction and the membrane diffusion coefficients were calculated from the permeation lag-times. The maximum permeation enhancement was achieved using a eutectic mixture at a 0.7:0.3 prilocaine/lidocaine ratio. A higher solubility of both agents in silicone membrane, enhanced diffusivity of prilocaine and superior release of both drugs, all contributed to produce enhanced permeation from the eutectic mixtures. Deconvolution of the transmembrane transport process suggests that the eutectic enhancement phenomena is a consequence of more favorable permeation characteristics of the two molecules in the absence of a formulation vehicle which competes in the transport process. PMID:20382211

Fiala, Sarah; Jones, Stuart A; Brown, Marc B

2010-06-30

191

Formation mechanism of primary phases and eutectic structures within undercooled Pb-Sb-Sn ternary alloys  

NASA Astrophysics Data System (ADS)

The solidification characteristics of three types of Pb-Sb-Sn ternary alloys with different primary phases were studied under substantial undercooling conditions. The experimental results show that primary (Pb) and SbSn phases grow in the dendritic mode, whereas primary (Sb) phase exhibits faceted growth in the form of polygonal blocks and long strips. (Pb) solid solution phase displays strong affinity with SbSn intermetallic compound so that they produce various morphologies of pseudobinary eutectics, but it can only grow in the divorced eutectic mode together with (Sb) phase. Although (Sb) solid solution phase and SbSn intermetallic compound may grow cooperatively within ternary eutectic microstructures, they seldom form pseudobinary eutectics independently. The (Pb)+(Sb)+SbSn ternary eutectic structure usually shows lamellar morphology, but appears as anomalous eutectic when its volume fraction becomes small. EDS analyses reveal that all of the three primary (Pb), (Sb) and SbSn phases exhibit conspicuous solute trapping effect during rapid solidification, which results in the remarkable extension of solute solubility.

Wang, Weili; Dai, Fuping; Wei, Bingbo

2007-08-01

192

Growth and characterization of the NiAl-NiAlNb eutectic structure  

NASA Astrophysics Data System (ADS)

Despite presenting potential as high-temperature structural material, the NiAl intermetallic compound cannot be easily employed due to its low room temperature fracture toughness and poor creep strength. A solution for such a problem is combining such a compound with other phase using a eutectic transformation, as in the case of the NiAl-NiAlNb eutectic structure. In this study, several samples containing Ni, Al and Nb were arc melted in order to evaluate the eutectic composition of this transformation, as well as the temperature at which it occurs. The resulting phases were the B2 NiAl and the Laves phase NiAlNb. It was found that the eutectic alloy occurs close to 16.0 at% Nb and the eutectic transformation temperature is 1487 °C. The amount of NiAl phase clearly decreases when the Nb content is raised. Thus, hypoeutectic alloys present NiAl dendrites with NiAlNb precipitated at the grain boundaries while hypereutectic alloys present primary dendrites of NiAlNb. The eutectic alloy was directionally solidified at growth rates varying from 5.0 to 50.0 mm/h. As expected, the lamellar spacing was found to decrease as the growth rate was increased.

Ferrandini, P. L.; Araujo, F. L. G. U.; Batista, W. W.; Caram, R.

2005-02-01

193

Preparation of eutectic substrate mixtures for enzymatic conversion of ATC to L-cysteine at high concentration levels.  

PubMed

High concentration eutectic substrate solutions for the enzymatic production of L-cysteine were prepared. Eutectic melting of binary mixtures consisting of D,L-2-amino-?(2)-thiazoline-4-carboxylic acid (ATC) as a substrate and malonic acid occurred at 39 °C with an ATC mole fraction of 0.5. Formation of eutectic mixtures was confirmed using SEM, SEM-EDS, and XPS surface analyses. Sorbitol, MnSO4, and NaOH were used as supplements for the enzymatic reactions. Strategies for sequential addition of five compounds, including a binary ATC mixture and supplements, during preparation of eutectic substrate solutions were established. Eutectic substrate solutions were stable for 24 h. After 6 h of enzymatic reactions, a 550 mM L-cysteine yield was obtained from a 670 mM eutectic ATC solution. PMID:24249216

Youn, Sung Hun; Park, Hae Woong; Choe, Deokyeong; Shin, Chul Soo

2014-06-01

194

Shock-induced melting of a KCl:LiCl eutectic powder as determined from electrochemical response measurements  

Microsoft Academic Search

Shock-induced melting of powder compacts of a eutectic of KCl and LiCl has been investigated in an electrochemical cell in which the eutectic serves as the electrolyte with an anode of a lithium-silicon alloy and a cathode with a mixture of FeS2, the eutectic and silicon dioxide. The cell remains inactive into low impedance electrical loads until the powder is

R. A. Graham; B. Morosin; D. M. Bush

1987-01-01

195

Salt tectonics on Venus  

SciTech Connect

The discovery of a surprisingly high deuterium/hydrogen ratio on Venus immediately led to the speculation that Venus may have once had a volume of surface water comparable to that of the terrestrial oceans. The authors propose that the evaporation of this putative ocean may have yielded residual salt deposits that formed various terrain features depicted in Venera 15 and 16 radar images. By analogy with models for the total evaporation of the terrestrial oceans, evaporite deposits on Venus should be at least tens to hundreds of meters thick. From photogeologic evidence and in-situ chemical analyses, it appears that the salt plains were later buried by lava flows. On Earth, salt diapirism leads to the formation of salt domes, anticlines, and elongated salt intrusions - features having dimensions of roughly 1 to 100 km. Due to the rapid erosion of salt by water, surface evaporite landforms are only common in dry regions such as the Zagros Mountains of Iran, where salt plugs and glaciers exist. Venus is far drier than Iran; extruded salt should be preserved, although the high surface temperature (470/sup 0/C) would probably stimulate rapid salt flow. Venus possesses a variety of circular landforms, tens to hundreds of kilometers wide, which could be either megasalt domes or salt intrusions colonizing impact craters. Additionally, arcurate bands seen in the Maxwell area of Venus could be salt intrusions formed in a region of tectonic stress. These large structures may not be salt features; nonetheless, salt features should exist on Venus.

Wood, C.A.; Amsbury, D.

1986-05-01

196

The effect of porosity and gamma-gamma-prime eutectic content on the fatigue behavior of hydrogen charged PWA 1480  

NASA Technical Reports Server (NTRS)

The study addresses the effect of systematically varying gamma-gamma-prime eutectic content and porosity level on the fatigue life of a hydrogen-charged single crystal PWA 1480 superalloy. Four microstructural variants are produced, and differences in gamma-gamma-prime eutectic morphology among the four processing variants are analyzed. Single valued tensile test data indicate that the tensile and yield strength of the PWA 1480 are degraded by hydrogen charging, with the exception of the material given a eutectic solution treatment. It is shown that the reduction of the fatigue life can be minimized by a duplex thermomechanical treatment consisting of a eutectic solution followed by hot isostatic pressing.

Gayda, J.; Dreshfield, R. L.; Gabb, T. P.

1991-01-01

197

Electrolytic recovery of chlorine from hydrogen chloride gas with fused molten salt electrolyte LiCl\\/KCl  

Microsoft Academic Search

A method of electrolytic recovery of chlorine from hydrogen chloride gas based on the fused molten salt LiCl\\/KCl is under development. For the feasibility study, described here, a reticulated vitreous carbon (or porous carbon) cathode was immersed in a low-melting eutectic of LiCl\\/KCl. A graphite rod was used as the anode. Gaseous dilute hydrogen chloride, in a mixture with nitrogen,

Y. Ding; J. Winnick

1996-01-01

198

Identification of salt-alloy combinations for thermal energy storage applications in advanced solar dynamic power systems  

Microsoft Academic Search

Thermodynamic calculations based on the available data for flouride salt systems reveal that a number of congruently melting compositions and eutectics exist which have the potential to meet the lightweight, high energy storage requirements imposed for advanced solar dynamic systems operating between about 1000 and 1400 K. Compatibility studies to determine suitable containment alloys to be used with NaF-22CaF2-13MgF2, NaF-32CaF2,

J. D. Whittenberger; A. K. Misra

1987-01-01

199

Lead-bismuth eutectic technology for Hyperion reactor  

NASA Astrophysics Data System (ADS)

A small lead-bismuth eutectic-cooled reactor concept (referred to as the Hyperion reactor concept) is being studied at Los Alamos National Laboratory and Hyperion Power Generation. In this report, a critical assessment of the lead-bismuth eutectic technology for Hyperion reactor is presented based on currently available knowledge. Included are: material compatibility, oxygen control, thermal hydraulics, polonium control. The key advances in the technology and their applications to Hyperion reactor design are analyzed. Also, the near future studies in main areas of the technology are recommended for meeting the design requirements. For cases with an outlet temperature below 550 °C, LBE was selected, while for cases with an outlet temperature above 550 °C, liquid lead was selected. Except SVBR-75/100, the primary coolant system is pool-type and natural convection. No reactor has an intermedium loop. Except SSTAR, steam generator is used as the energy conversion system. SSTAR uses Super critical CO2 brayton. The flow velocity of the primary coolant is limited to 2.0 m/s. Except ELYS, nitride fuel is selected. ELYS selects U-oxide fuel. Martensitic stainless steel is selected for the cladding materials (EP823 for Russian design, HT-9 for Japan and U.S design, T-91 for EU design, compositions of the steels are given in Table 3). The complexity as well as the cost of the reactor can be reduced by employing direct contacting energy conversion system without an intermediate loop which would be needed in a sodium cooled reactor. This is because LBE has low vapor pressure and does not react with air and water intensively. For such a design (without the intermediate loop), the designer has to concern that the primary coolant system may be pressurized by the high pressure steam when there is a break at the steam generator or heat exchanger.SSTAR employs super critical CO2 (S-CO2) Brayton for the energy conversion system. This system can be very compact, offers the prospect of higher thermal efficiencies with lower Pb outlet temperature and small turbomachinery reducing the footprint and cost of the power converter [7]. However, there are few studies on the S-CO2 compatibility with structural materials at high temperatures, and the corrosion can become serious issues. Further studies are needed to find a structural material having good corrosion resistance to S-CO2 at the operating temperature.When the flow velocity is high, the mechanical erosion may become a serious problem, especially for the heavy liquid metal. The flow velocity of the primary coolant is limited by constrain of avoiding erosion of the protective layer, which is a disadvantage of using LBE as coolant. For current Hyperion reactor design, the flow velocity is designed to be less than 2.0 m/s, which is based on Russian operation experience. Theoretically, the upper limit of the velocity is not clear, and it should be different for different primary coolant system design.

Zhang, J.; Kapernick, R. J.; McClure, P. R.; Trapp, T. J.

2013-10-01

200

Image matching technology in high power LED's eutectic welding.  

PubMed

As the integration packaging density of high-power LED (Light Emitting Diode) chip modules become higher and higher, the accuracy and speed of visual inspection require higher demands correspondingly. The accurate position matching of substrates and flip-chip LEDs is one of the key technologies in the automatic eutectic welding process. In this paper we propose a method based on image features to complete the matching of the substrates and the flip-chip LEDs. Firstly, the substrate images and the flip-chip images are pre-processed respectively to obtain binary images. Then we apply Hough transformation to detect straight lines on the binary images, and find out the main linear directions to trigger the mechanical arms to adjust the positions of the substrate and the chip initially. Thirdly, we use eight neighbors interconnected domain algorithm for the first time to locate notable features of the substrate, and pass the located information to the control system to trigger the mechanical arm to adjust the substrate for the second time. At the same time, projection algorithm is applied to locate the anode of the flip-chip to drive the mechanical arm to adjust the position of the flip-chip again. Finally, the position information is used to trigger the mechanical arm to accomplish the matching of the substrate and the flip-chip. The proposed method improves the speed of matching on the basis of the accuracy of matching, which achieves these requirements of real-time and high accuracy applications. PMID:24921546

Ge, Peng; Yin, Peipei; Wang, Hong; Chang, Tianhai

2014-06-01

201

Directional solidification of the alumina-zirconia ceramic eutectic system  

SciTech Connect

It is possible to produce alumina-zirconia ceramic samples through existing solidification techniques. The resulting microstructures typically consist of rods of zirconia in an alumina matrix, although a lamellar structure has been noted in some cases. In nearly all cases, colony growth was present which may possibly result from grain size, repeated nucleation events, and lamellar oscillations. In the same vein, it appears that the amount of impurities within the system might be the underlying cause for the colony growth. Colony growth was diminished through impurity control as the higher purity samples exhibited colony free behavior. In addition to colony formations, faceted alumina dendrites or nonfaceted zirconia dendrites may result in the ceramic if the sample is solidified out of the coupled zone. In all cases, for larger-sized Bridgman samples, a lower limit in the eutectic spacing was noted. The solidification model which includes the kinetic effect has been developed, although the effect appears to be negligible under present experimental conditions. A spacing limit might also occur due to the result of heat flow problems. Heat flow out of the ceramic is difficult to control, often causing radial and not axial growth. This behavior is exaggerated in the presence of impurities. Thus, higher purity powders should always be used. Higher purity samples, in addition to yielding a more microstructurally uniform ceramic, also showed increased directionality. In the future, the kinetic model needs to be examined in more detail, and further research needs to be accomplished in the area of molten ceramics. Once better system constants are in place, the kinetic model will give a better indication of the behavior in the alumina-zirconia system.

Boldt, C.

1994-07-27

202

Retrospective salt tectonics  

SciTech Connect

The conceptual breakthroughs in understanding salt tectonics can be recognized by reviewing the history of salt tectonics, which divides naturally into three parts: the pioneering era, the fluid era, and the brittle era. The pioneering era (1856-1933) featured the search for a general hypothesis of salt diapirism, initially dominated by bizarre, erroneous notions of igneous activity, residual islands, in situ crystallization, osmotic pressures, and expansive crystallization. Gradually data from oil exploration constrained speculation. The effects of buoyancy versus orogeny were debated, contact relations were characterized, salt glaciers were discovered, and the concepts of downbuilding and differential loading were proposed as diapiric mechanisms. The fluid era (1933-{approximately}1989) was dominated by the view that salt tectonics resulted from Rayleigh-Taylor instabilities in which a dense fluid overburden having negligible yield strength sinks into a less dense fluid salt layer, displacing it upward. Density contrasts, viscosity contrasts, and dominant wavelengths were emphasized, whereas strength and faulting of the overburden were ignored. During this era, palinspastic reconstructions were attempted; salt upwelling below thin overburdens was recognized; internal structures of mined diapirs were discovered; peripheral sinks, turtle structures, and diapir families were comprehended; flow laws for dry salt were formulated; and contractional belts on divergent margins and allochthonous salt sheets were recognized. The 1970s revealed the basic driving force of salt allochthons, intrasalt minibasins, finite strains in diapirs, the possibility of thermal convection in salt, direct measurement of salt glacial flow stimulated by rainfall, and the internal structure of convecting evaporites and salt glaciers. The 1980`s revealed salt rollers, subtle traps, flow laws for damp salt, salt canopies, and mushroom diapirs.

Jackson, M.P.A. [Univ. of Texas, Austin, TX (United States)

1996-12-31

203

Ionic liquid and deep eutectic solvent-activated CelA2 variants generated by directed evolution.  

PubMed

Chemoenzymatic cellulose degradation is one of the key steps for the production of biomass-based fuels under mild conditions. An effective cellulose degradation process requires diverse physico-chemical dissolution of the biomass prior to enzymatic degradation. In recent years, "green" solvents, such as ionic liquids and, more recently, deep eutectic liquids, have been proposed as suitable alternatives for biomass dissolution by homogenous catalysis. In this manuscript, a directed evolution campaign of an ionic liquid tolerant ?-1,4-endoglucanase (CelA2) was performed in order to increase its performance in the presence of choline chloride/glycerol (ChCl:Gly) or 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), as a first step to identify residues which govern ionic strength resistance and obtaining insights for employing cellulases on the long run in homogenous catalysis of lignocellulose degradation. After mutant library screening, variant M4 (His288Phe, Ser300Arg) was identified, showing a dramatically reduced activity in potassium phosphate buffer and an increased activity in the presence of ChCl:Gly or [BMIM]Cl. Further characterization showed that the CelA2 variant M4 is activated in the presence of these solvents, representing a first report of an engineered enzyme with an ionic strength activity switch. Structural analysis revealed that Arg300 could be a key residue for the ionic strength activation through a salt bridge with the neighboring Asp287. Experimental and computational results suggest that the salt bridge Asp287-Arg300 generates a nearly inactive CelA2 variant and activity is regained when ChCl:Gly or [BMIM]Cl are supplemented (~5-fold increase from 0.64 to 3.37 ?M 4-MU/h with the addition ChCl:Gly and ~23-fold increase from 3.84 to 89.21 ?M 4-pNP/h with the addition of [BMIM]Cl). Molecular dynamic simulations further suggest that the salt bridge between Asp287 and Arg300 in variant M4 (His288Phe, Ser300Arg) modulates the observed salt activation. PMID:24802079

Lehmann, Christian; Bocola, Marco; Streit, Wolfgang R; Martinez, Ronny; Schwaneberg, Ulrich

2014-06-01

204

Retrospective salt tectonics  

Microsoft Academic Search

The conceptual breakthroughs in understanding salt tectonics can be recognized by reviewing the history of salt tectonics, which divides naturally into three parts: the pioneering era, the fluid era, and the brittle era. The pioneering era (1856-1933) featured the search for a general hypothesis of salt diapirism, initially dominated by bizarre, erroneous notions of igneous activity, residual islands, in situ

1996-01-01

205

Sugar and Salt Solutions  

NSDL National Science Digital Library

What happens when sugar and salt are added to water? Pour in sugar, shake in salt, and evaporate water to see the effects on concentration and conductivity. Zoom in to see how different sugar and salt compounds dissolve. Zoom in again to explore the role of water.

Simulations, Phet I.; Lancaster, Kelly; Reid, Sam; Moore, Emily; Chamberlain, Julia; Loeblein, Trish

2011-10-12

206

Utah: Salt Lake Region  

article title:  Winter and Summer Views of the Salt Lake Region     ... Salt Lake City, Utah are captured in these winter and summer images from the Multi-angle Imaging SpectroRadiometer (MISR) ... the obvious difference in snow cover between the winter and summer views, water color changes in parts of the Great Salt Lake are apparent ...

2013-04-18

207

Plant salt tolerance  

Microsoft Academic Search

Soil salinity adversely affects crop productivity and quality. The success of breeding programs aimed at salinity tolerant crop varieties is limited by the lack of a clear understanding of the molecular basis of salt tolerance. Recent advances in genetic analysis of Arabidopsis mutants defective in salt tolerance, and molecular cloning of these loci, have showed some insight into salt stress

Viswanathan Chinnusamy; Jian-Kang Zhu

208

Deformation and fracture of a directionally solidified NiAl-28Cr-6Mo eutectic alloy  

NASA Technical Reports Server (NTRS)

A directionally solidified alloy based on the NiAl-(Cr, Mo) eutectic was examined by transmission and scanning electron microscopy to characterize the microstructure and room temperature deformation and fracture behavior. The microstructure consisted of a lamellar morphology with a group of zone axes (111) growth direction for both the NiAl and (Cr, Mo) phases. The interphase boundary between the eutectic phases was semicoherent and composed of a well-defined dislocation network. In addition, a fine array of coherent NiAl precipitates was dispersed throughout the (Cr, Mo) phase. The eutectic morphology was stable at 1300 K with only coarsening of the NiAl precipitates occurring after heat treatment for 1.8 ks (500 h). Fracture of the aligned eutectic is characterized primarily by a crack bridging/renucleation mechanism and is controlled by the strength of the semicoherent interface between the two phases. However, contributions to the toughness of the eutectic may arise from plastic deformation of the NiAl phase and the geometry associated with the fracture surface.

Chen, X. F.; Johnson, D. R.; Noebe, R. D.; Oliver, B. F.

1995-01-01

209

Solidification microstructure of Bridgman-grown Si-TaSi2 eutectic in situ composite  

NASA Astrophysics Data System (ADS)

Directionally solidified Si-TaSi2 eutectic in situ composite was fabricated by Bridgman growth technique with a high temperature gradient. The microstructure and solid/liquid interface morphology evolvement were systematically investigated. The grown Si-TaSi2 presents typical semiconductor-metal eutectic structure with the TaSi2 regularly and uniformly embedded into Si matrix. As the solidification rate increases from 6 to 150 µm/s, the fiber diameter and eutectic spacing rapidly decrease, whereas the rod density increases. The eutectic spacing and solidification rate obey the relationship of ?V0.53=73.7 ?m1.53/s0.53. Under the optimal solidification parameter (V=100 µm/s), the fiber diameter is 1.37 ?m, average eutectic spacing is 3.83 ?m, and rod density is 3×106 rod/cm2, which well satisfy the requirement of Spindt field emission arrays. Furthermore, the solid/liquid interface undergoes an evolvement of planar-shallow cell-cell with the increase of solidification rate.

Yang, Xinyu; Zhang, Jun; Su, Haijun; Jie, Ziqi; Liu, Lin; Fu, Hengzhi

2013-08-01

210

PU/SS EUTECTIC ASSESSMENT IN 9975 PACKAGINGS IN A STORAGE FACILITY DURING EXTENDED FIRE  

SciTech Connect

In a radioactive material (RAM) packaging, the formation of eutectic at the Pu/SS (plutonium/stainless steel) interface is a serious concern and must be avoided to prevent of leakage of fissile material to the environment. The eutectic temperature for the Pu/SS is rather low (410 C) and could seriously impact the structural integrity of the containment vessel under accident conditions involving fire. The 9975 packaging is used for long term storage of Pu bearing materials in the DOE complex where the Pu comes in contact with the stainless steel containment vessel. Due to the serious consequences of the containment breach at the eutectic site, the Pu/SS interface temperature is kept well below the eutectic formation temperature of 410 C. This paper discusses the thermal models and the results for the extended fire conditions (1500 F for 86 minutes) that exist in a long term storage facility and concludes that the 9975 packaging Pu/SS interface temperature is well below the eutectic temperature.

Gupta, N.

2012-03-26

211

Interactions between iron, manganese, and the Al-Si eutectic in hypoeutectic Al-Si alloys  

NASA Astrophysics Data System (ADS)

Sand-cast plates were used to determine the effect of iron and manganese concentrations on porosity levels in Al-9 pct Si-0.5 pct Mg alloys. Iron increased porosity levels. Manganese additions increased porosity levels in alloys with 0.1 pct Fe, but reduced porosity in alloys with 0.6 and 1 pct Fe. Thermal analysis and quenching were undertaken to determine the effect of iron and managanese on the solidification of the Al-Si eutectic. At high iron levels, the presence of large ?-Al5FeSi was found to reduce the number of eutectic nucleation events and increase the eutectic grain size. The preferential formation of ?-Al15Mn3Si2 upon addition of manganese reversed these effects. It is proposed that this interaction is due to ?-Al5FeSi and the Al-Si eutectic having common nuclei. Porosity levels are proposed to be controlled by the eutectic grain size and the size of the iron-bearing intermetallic particles rather than the specific intermetallic phase that forms.

Dinnis, C. M.; Taylor, J. A.; Dahle, A. K.

2006-11-01

212

Some Peculiarities of Eutectic Crystallization of LaB 6-(Ti,Zr)B 2 Alloys  

NASA Astrophysics Data System (ADS)

The structures of eutectic LaB 6-(Ti,Zr)B 2 alloys are studied after directional crystallization. The eutectic compositions and monovariant equilibrium between two quasibinary eutectics in this system were determined. Varying the TiB 2/ZrB 2 borides ratio permits us to control in their solid solutions the corresponding cell dimensions and, consequently, the boron-boron distances in the resulting quasibinary borides. Our previous assumptions that the perfectness of the real structure is determined by differences in the distances between boron atoms in boron sublattices of hexa- and diboride phases were confirmed. It is shown that forming the regular whiskers structure is much easier for complex (Ti,Zr)B 2 boride than for individual TiB 2 or ZrB 2 borides.

Paderno, Yu.; Paderno, V.; Filippov, V.

2000-10-01

213

Studies of directionally solidified eutectic Bi/MnBi at low growth velocities  

NASA Astrophysics Data System (ADS)

A deviation from the interrod spacing (?) and growth velocity (V) relation ?2V = constant, anticipated for diffusion-only rod eutectic growth, has been observed at growth velocities ?5 cm/h (14 µm/s) in directionally solidified eutectic Bi-Mn (Bi/MnBi). At lower growth velocities, V? 0.5 cm/h, a breakdown in the aligned rod eutectic, cooperative growth mechanism, has also been noted. The ?2V relation has been experimentally determined over a range of furnace (growth) velocities (0.5 ? V ? 50 cm/h), thermal gradients in the liquid (40 ? GL ? 120 °C/cm) and solidification orientation with respect to the direction of gravity (parallel, antiparallel, and perpendicular). Naturally induced, convective instabilities are suggested as a possible, lower growth velocity limit for cooperative growth in this system.

Pirich, Ron G.

1984-12-01

214

Solidification processing of eutectic alloys; Proceedings of the Symposium, Cincinnati, OH, Oct. 12-15, 1987  

SciTech Connect

The papers presented in this volume address the effect of solidification processing variables, such as cooling rate, nucleation hierarchy, and the faceted or nonfaceted nature of the constituent phases, on the eutectic morphology and resulting properties. Topics discussed include the current status of the modeling of eutectic growth and directional solidification experiments on a variety of alloys, such as aluminum foundry alloy A 356, Si- and GaAs-based eutectics for electronic applications, and Cu-Al in-situ composites. Particular attention is given to undercooled and rapidly solidified alloys, including classical simple alloys, such as Pb-Sn as well as more complicated alloys such as Nb-Si, alumina-zirconia, and Cr90Ta10.

Stefanescu, D.M.; Abbaschian, G.J.; Bayuzick, R.J.

1988-01-01

215

Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces  

SciTech Connect

This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 {angstrom} Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 {angstrom}, 500 {angstrom}, and 300 {angstrom} per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 {angstrom}/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 {angstrom}/side appear to correspond with the phonon transmission study.

Knowlton, W.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley Lab., CA (United States). Materials Sciences Div.

1995-07-01

216

Environmental effects on ultra-high temperature creep behavior of directionally solidified oxide eutectic ceramics  

Microsoft Academic Search

Experimental studies were undertaken to assess the environmental effects on ultra-high temperature tensile creep behavior of directionally solidified Al2O3\\/Y3Al5O12(YAG) and Al2O3\\/GdAlO3(GAP) eutectic ceramics. Tensile creep deformation tests conducted under constant stress ranging 100–200MPa at temperature range of 1673–1873K at different environmental conditions consisting of air and at different water vapor pressure, pH2O, up to 0.6MPa. These eutectic ceramics exhibited a

Yoshihisa Harada; Takayuki Suzuki; Kazumi Hirano; Narihito Nakagawa; Yoshiharu Waku

2005-01-01

217

Numerical study: Iron corrosion-resistance in lead-bismuth eutectic coolant by molecular dynamics method  

SciTech Connect

In this present work, we report numerical results of iron (cladding) corrosion study in interaction with lead-bismuth eutectic coolant of advanced nuclear reactors. The goal of this work is to study how the oxygen can be used to reduce the corrosion rate of cladding. The molecular dynamics method was applied to simulate corrosion process. By evaluating the diffusion coefficients, RDF functions, MSD curves of the iron and also observed the crystal structure of iron before and after oxygen injection to the coolant then we concluded that a significant and effective reduction can be achieved by issuing about 2% number of oxygen atoms to lead-bismuth eutectic coolant.

Arkundato, Artoto; Su'ud, Zaki; Abdullah, Mikrajuddin; Widayani,; Celino, Massimo [Nuclear Physics and Biophysics Research Division, Physics Department Institut Teknologi Bandung, Jl. Ganesha 10, Bandung Physics Department, Faculty of Mathematical and Natural Sciences Universitas (Indonesia); Nuclear Physics and Biophysics Research Division, Physics Department Institut Teknologi Bandung, Jl. Ganesha 10, Bandung (Indonesia); ENEA, CR Cassacia, Via Anguillarese 301, Roma (Italy)

2012-06-06

218

Low-Temperature Interface Reaction Between Titanium and the Eutectic Silver-Copper Brazing Alloy  

Microsoft Academic Search

Reaction zones formed at 790 °C between solid titanium and liquid Ag-Cu eutectic alloys (pure and Ti-saturated) have been\\u000a characterized. When pure Ag-Cu eutectic alloy with 40 at.% Cu is used, the interface reaction layer sequence is: ?Ti\\/Ti2Cu\\/TiCu\\/Ti3Cu4\\/TiCu4\\/L. Because of the fast dissolution rate of Ti in the alloy, the reaction zone remains very thin (3-6 ?m) whatever the reaction\\u000a time. When the

J. Andrieux; O. Dezellus; F. Bosselet; J. C. Viala

2009-01-01

219

Numerical study: Iron corrosion-resistance in lead-bismuth eutectic coolant by molecular dynamics method  

NASA Astrophysics Data System (ADS)

In this present work, we report numerical results of iron (cladding) corrosion study in interaction with lead-bismuth eutectic coolant of advanced nuclear reactors. The goal of this work is to study how the oxygen can be used to reduce the corrosion rate of cladding. The molecular dynamics method was applied to simulate corrosion process. By evaluating the diffusion coefficients, RDF functions, MSD curves of the iron and also observed the crystal structure of iron before and after oxygen injection to the coolant then we concluded that a significant and effective reduction can be achieved by issuing about 2% number of oxygen atoms to lead-bismuth eutectic coolant.

Arkundato, Artoto; Su'ud, Zaki; Abdullah, Mikrajuddin; Widayani; Celino, Massimo

2012-06-01

220

Solidification of binary and Sr-modified Al-Si eutectic alloys - Theoretical analysis of solute fields  

SciTech Connect

This paper analyzes experimental data in available literature concerning the eutectic spacing lambda and growth undercooling Delta-T in the Al-Si binary eutectic and in the strontium-modified eutectic. The expression for Delta-T obtained in Jackson and Hunt's model is used, before application of the minimum undercooling growth criterion. It is shown that, for the binary eutectic, the results can be interpreted quantitatively by means of this equation. On the other hand, it is shown that the results for the modified alloy cannot be interpreted on this basis and that a contribution of the kinetic undercooling for growth of Si has to be taken into account. A high level of kinetic undercooling is found (ranging from 5 to 15 K depending on the solidification rate). This analysis also predicts a significant silicon-enrichment of the interfacial liquid, especially in the modified eutectic (up to 2 wt pct). 13 refs.

Sens, H.; Eustathopoulos, N.; Camel, D.; Favier, J.J. (CEA, Centre d'Etudes Nucleaires de Grenoble (France) Ecole Nationale Superieure d'Electrochimie et d'Electrometallurgie, Saint-Martin-d'Heres (France))

1992-07-01

221

Numerical study of the effect of the shape of the phase diagram on the eutectic freezing temperature  

SciTech Connect

To evaluate the reliability of metal-carbon eutectic systems as fixed points for the next generation of high-temperature standards the effect of thermodynamic properties related to the shape of eutectic phase diagram on the freezing temperature is investigated within the context of the numerical multi-phase-field model. The partition coefficient and liquidus slopes of the two solids involved in the eutectic reaction are varied deliberately and independently. The difference between the eutectic temperature and the freezing temperature is determined in dependence of the solid/liquid (s/l) interface shape and concentration. Where appropriate reference is made to the Jackson-Hunt analytical theory. It is shown that there are mainly two typical conditions to decrease the undercooling: 1) a small liquidus slope and 2) the associated difference between the eutectic composition and the liquid composition during solidification.

Ode, M.; Shimono, M. [National Institute for Materials Science (NIMS), Tsukuba (Japan)] [National Institute for Materials Science (NIMS), Tsukuba (Japan); Sasajima, N.; Yamada, Y. [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ, AIST), Tsukuba (Japan)] [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ, AIST), Tsukuba (Japan); Bloembergen, P. [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ, AIST), Tsukuba, Japan and National Institute of Metrology, Beijing 100013 (China)] [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ, AIST), Tsukuba, Japan and National Institute of Metrology, Beijing 100013 (China)

2013-09-11

222

Synthesis of oxide perovskite solid solutions using the molten salt method  

SciTech Connect

The molten salt method has in the past been employed to synthesize a large number of compounds at low temperatures. In this work we report the formation of solid solutions of BaTiO{sub 3}{endash}SrTiO{sub 3} and BaZrO{sub 3}{endash}SrZrO{sub 3} using a molten salt eutectic of NaOH{endash}KOH as a solvent. Alkaline earth carbonates and titanium oxide were used as precursors for the titanate system, and alkaline earth carbonates and zirconium oxide were used as precursors for the zirconate system. It was found that both systems form solid solutions throughout the composition range. The implications of these results with regards to the applicability of the molten salt method as a tool to investigate low temperature phase equilibria are discussed. {copyright} {ital 1996 Materials Research Society.}

Gopalan, S.; Mehta, K.; Virkar, A.V. [Department of Materials Science and Engineering, 304 EMRO University of Utah, Salt Lake City, Utah 84112 (United States)

1996-08-01

223

Structure of molten salts  

SciTech Connect

A brief review of the structure of molten salts is given with special emphasis on structural features in reciprocal space. Selected diffraction results on halide salts containing monovalent and divalent cations are presented, along with recent results on salts containing trivalent cations. Different models and computational techniques, such as random packing of structural units, the reference interaction site model, and reverse Monte Carlo are used to derive structural information at the partial level. 15 refs., 3 figs.

Saboungi, M.L.; Howe, M.A.; Price, D.L.

1990-01-01

224

Eutectic melting temperature of the lowermost Earth's mantle  

NASA Astrophysics Data System (ADS)

Partial melting of the Earth's deep mantle probably occurred at different stages of its formation as a consequence of meteoritic impacts and seismology suggests that it even continues today at the core-mantle boundary. Melts are important because they dominate the chemical evolution of the different Earth's reservoirs and more generally the dynamics of the whole planet. Unfortunately, the most critical parameter, that is the temperature profile inside the deep Earth, remains poorly constrained accross the planet history. Experimental investigations of the melting properties of materials representative of the deep Earth at relevant P-T conditions can provide anchor points to refine past and present temperature profiles and consequently determine the degree of melting at the different geological periods. Previous works report melting relations in the uppermost lower mantle region, using the multi-anvil press [1,2]. On the other hand, the pyrolite solidus was determined up to 65 GPa using optical observations in the laser-heated diamond anvil cell (LH-DAC) [3]. Finally, the melting temperature of (Mg,Fe)2SiO4 olivine is documented at core-mantle boundary (CMB) conditions by shock wave experiments [4]. Solely based on these reports, experimental data remain too sparse to draw a definite melting curve for the lower mantle in the relevant 25-135 GPa pressure range. We reinvestigated melting properties of lower mantle materials by means of in-situ angle dispersive X-ray diffraction measurements in the LH-DAC at the ESRF [5]. Experiments were performed in an extended P-T range for two starting materials: forsterite and a glass with chondrite composition. In both cases, the aim was to determine the onset of melting, and thus the eutectic melting temperatures as a function of pressure. Melting was evidenced from drastic changes of diffraction peak shape on the image plate, major changes in diffraction intensities in the integrated pattern, disappearance of diffraction rings, and changes in the relation between sample-temperature and laser-power. In this work, we show that temperatures higher than 4000 K are necessary for melting mean mantle at the 135 GPa pressure found at the core mantle boundary (CMB). Such temperature is much higher than that from estimated actual geotherms. Therefore, melting at the CMB can only occur if (i) pyrolitic mantle resides for a very long time in contact with the outer core, (ii) the mantle composition is severely affected by additional elements depressing the solidus such as water or (iii) the temperature gradient in the D" region is amazingly steep. Other implications for the temperature state and the lower mantle properties will be presented. References (1) Ito et al., Phys. Earth Planet. Int., 143-144, 397-406, 2004 (2) Ohtani et al., Phys. Earth Planet. Int., 100, 97-114, 1997 (3) Zerr et al., Science, 281, 243-246, 1998 (4) Holland and Ahrens, Science, 275, 1623-1625, 1997 (5) Schultz et al., High Press. Res., 25, 1, 71-83, 2005.

Andrault, D.; Lo Nigro, G.; Bolfan-Casanova, N.; Bouhifd, M.; Garbarino, G.; Mezouar, M.

2009-12-01

225

Dosimetry using silver salts  

DOEpatents

The present invention provides a method for detecting ionizing radiation. Exposure of silver salt AgX to ionizing radiation results in the partial reduction of the salt to a mixture of silver salt and silver metal. The mixture is further reduced by a reducing agent, which causes the production of acid (HX) and the oxidized form of the reducing agent (R). Detection of HX indicates that the silver salt has been exposed to ionizing radiation. The oxidized form of the reducing agent (R) may also be detected. The invention also includes dosimeters employing the above method for detecting ionizing radiation.

Warner, Benjamin P. (Los Alamos, NM)

2003-06-24

226

Evaluation of magnesium-aluminum eutectic to improve combustion efficiency in low burning rate propellants  

NASA Technical Reports Server (NTRS)

A previous investigation indicated that combustion efficiency of low burning-rate propellants could be improved if the aluminum fuel was replaced by aluminum particles coated with a magnesium-aluminum eutectic alloy (ALCAL). The purpose of the present investigation was to evaluate the possibility of improving the combustion efficiency of these propellants by admixing the eutectic with the aluminum rather than coating the aluminum. Tests of three propellants similar in every respect except for the metal fuel were conducted in test motors with 4.54 kg (10 lbm) of propellant. The first propellant used aluminum fuel; the second contained aluminum admixed with magnesium-aluminum eutectic; the third used ALCAL. The test results show the the admixed fuel gave better low burning-rate combustion efficiency than the other two. The test results also showed that the ALCAL was deficient in that much, if not all, of the coating material could be found as the fine particles in a bimodal mix of aluminum and eutectic. The combustion efficiency of low burning-rate aluminized propellants can be significantly improved by mixing a small amount of magnesium-aluminum alloy with the aluminum fuel.

Northam, B. G.; Sullivan, E. M.

1973-01-01

227

Eutectic channelling in a squeeze cast Al-4.5Wt%Cu alloy  

SciTech Connect

The purpose of this study was to investigate to what extent macrosegregation occurs during the squeeze casting of a simple cylindrical shape in an Al-4.5wt%Cu alloy. The application of 100 MPa pressure during solidification caused a sharp increase in the cooling rate, to an average value of about 14 Ks{sup {minus}1}. At this cooling rate the liquidus temperature was resolvable, however it was difficult to observe the eutective thermal arrest. The macrostructure was characterized by a V-shaped pattern that extended over a large fraction of the ingot cross-section. The V-shaped segregates were regions which consisted of a mixture of the {alpha}-Al phase, the {alpha}-Al + {theta}-Al{sub 2}Cu eutectic and pro-eutectic {theta}-Al{sub 2}Cu particles. The exact cause of the formation of the eutectic channels in squeeze cast alloys is unclear. A previous explanation was that the V-shaped channels in squeeze castings are produced along the liquid metal feeding path. However, as the segregated channels are very large, these regions should be relatively easily fed during solidification. Also, as the solidification process occurs under near hydrostatic pressure, it is unclear where the driving force for the filling of these channels could come from. A simpler explanation may be that the macrosegregation is an effect of the different thermal conditions during solidification that exist between gravity and squeeze casting.

Gallerneault, M.; Durrant, G.; Cantor, B. [Univ. of Oxford (United Kingdom)] [Univ. of Oxford (United Kingdom)

1995-05-15

228

Eutectic freeze crystallization: Application to process streams and waste water purification  

Microsoft Academic Search

Two case studies are presented using eutectic freeze crystallization (EFC) as an alternative for evaporative crystallization: a 7.8 ton day?1 35 w% aqueous sodium nitrate and a 24 ton day?1 12 w% copper sulfate stream. The proposed crystallizer is a cooled disk column crystallizer (CDCC), using indirect cooling for heat transfer. In single stage operation, the formed ice crystals are

F. van der Ham; G. J. Witkamp; J. de Graauw; G. M. van Rosmalen

1998-01-01

229

Banding due to temperature oscillations in the unidirectional solidification of eutectic alloys  

NASA Technical Reports Server (NTRS)

Banding observed in unidirectional solidification of eutectic alloys is shown to be due to melting back of the freezing interface because of oscillations in the temperature of the furnace. General theoretical criteria as to the amplitude and frequency of the permissible temperature oscillations are given to ensure that banding will not occur.

Kidron, A.

1972-01-01

230

Design of eutectic photoinitiator blends for UV\\/visible curable acrylated printing inks and coatings  

Microsoft Academic Search

The optimisation of photoinitiator systems used in UV printing inks and coatings has been carried out by means of Design of Experiments (Mixture designs). Mixture designs have been used to improve the reactivity of photoinitiator blends in order to design cost effective, synergistic, near eutectic photoinitiator blends for curing UV printing inks. Both the reactivity and bulk stability of photoinitiator

Juan Segurola; Norman S Allen; Michele Edge; Adam Mc Mahon

1999-01-01

231

Eutectic Solidification of MgO-MgAl2O4.  

National Technical Information Service (NTIS)

Directional solidification of the MgO-MgAl2O4 eutectic yields MgO whiskers in a spinel matrix. Microstructures produced at solidification rates of 0.4 to 30.0 cm/h were studied. The interlamellar spacing agrees with the inverse-square-root dependence on s...

F. L. Kennard R. C. Bradt V. S. Stubican

1973-01-01

232

Damage by eutectic particle cracking in aluminum casting alloys A356/357  

NASA Astrophysics Data System (ADS)

The strain dependence of particle cracking in aluminum alloys A356/357 in the T6 temper has been studied in a range of microstructures produced by varying solidification rate and Mg content, and by chemical (Sr) modification of the eutectic silicon. The damage accumulates linearly with the applied strain for all microstructures, but the rate depends on the secondary dendrite arm spacing and modification state. Large and elongated eutectic silicon particles in the unmodified alloys and large ?-phase (Al9FeMg3Si5) particles in alloy A357 show the greatest tendency to cracking. In alloy A356, cracking of eutectic silicon particles dominates the accumulation of damage while cracking of Fe-rich particles is relatively unimportant. However, in alloy A357, especially with Sr modification, cracking of the large ?-phase intermetallics accounts for the majority of damage at low and intermediate strains but becomes comparable with silicon particle cracking at large strains. Fracture occurs when the volume fraction of cracked particles (eutectic silicon and Fe-rich intermetallics combined) approximates 45 pct of the total particle volume fraction or when the number fraction of cracked particles is about 20 pct. The results are discussed in terms of Weibull statistics and existing models for dispersion hardening.

Wang, Q. G.; Caceres, C. H.; Griffiths, J. R.

2003-12-01

233

Determination of the elastic moduli of a directionally solidified nickel-based TaC eutectic  

Microsoft Academic Search

Measurements of ultrasonic wave velocities in a polycrystalline directionally solidified nickel based eutectic alloy are used to evaluate the three independent single crystal elastic moduli at temperatures between 298 to 925 K. The Cu and C44 moduli are obtained directly from high frequency wave propagation along the D.S. axis, corresponding to . Evaluation of C12 requires measurements at lower frequencies

E. S. Fisher

1980-01-01

234

Observations on the Mechanisms of Fatigue in Eutectic Pb-Sn Solder Joints.  

National Technical Information Service (NTIS)

Near-eutectic Pb-Sn solders are widely used for joints in electrical devices. These are liable to failure by thermal fatigue during operation of the device. Since the thermal fatigue load is often in shear, the mechanisms of thermal fatigue in shear fare ...

D. Tribula D. Grivas D. R. Frear J. W. Morris

1988-01-01

235

Use of Eutectic Fixed Points to Characterize a Spectrometer for Earth Observations  

NASA Astrophysics Data System (ADS)

A small palm-sized, reference spectrometer, mounted on a remote-controlled model helicopter is being developed and tested by the National Physical Laboratory (NPL) in conjunction with City University, London. The developed system will be used as a key element for field vicarious calibration of optical earth observation systems in the visible-near infrared (VNIR) region. The spectrometer is hand held, low weight, and uses a photodiode array. It has good stray light rejection and wide spectral coverage, allowing simultaneous measurements from 400 to 900 nm. The spectrometer is traceable to NPL’s primary standard cryogenic radiometer via a high-temperature metal-carbon eutectic fixed-point blackbody. Once the fixed-point temperature has been determined (using filter radiometry), the eutectic provides a high emissivity and high stability source of known spectral radiance over the emitted spectral range. All wavelength channels of the spectrometer can be calibrated simultaneously using the eutectic transition without the need for additional instrumentation. The spectrometer itself has been characterized for stray light performance and wavelength accuracy. Its long-term and transportation stability has been proven in an experiment that determined the “World’s Bluest Sky”—a process that involved 56 flights, covering 100,000 km in 72 days. This vicarious calibration methodology using a eutectic standard is presented alongside the preliminary results of an evaluation study of the spectrometer characteristics.

Salim, Saber G. R.; Fox, Nigel P.; Woolliams, Emma R.; Winkler, Rainer; Pegrum, Heather M.; Sun, Tong; Grattan, Ken T. V.

2007-12-01

236

Eutectic Temperatures for Low and High Pressure Phases of Sodium Sulfate Hydrates with Applications to Europa  

NASA Astrophysics Data System (ADS)

We use optical images of crystallization in the Na_2SO_4-H_2O system, coupled with measurements of pressure, temperature, and volume changes, to report eutectic transitions for pressures up to 375 MPa, with implications for modeling Europa's ocean.

Dougherty, A. J.; Avidon, J. A.; Hogenboom, D. L.; Kargel, J. S.

2012-03-01

237

Fabrication of cellular shape memory alloy materials by reactive eutectic brazing using niobium  

Microsoft Academic Search

A novel metal-joining process is described that exploits interfacial reactions between nitinol and pure niobium to produce a reactive eutectic liquid that readily creates a robust metallurgical bond between nitinol and itself. With this new reactive-brazing process we have been able to create prototypes of superelastic cellular honeycomb topologies from conventional nitinol precursor materials such as tubes and corrugated sheets.

David S. Grummon; John A. Shaw; John Foltz

2006-01-01

238

The effect of substrate on the microstructure and creep of eutectic In-Sn  

SciTech Connect

This study was conducted in order to determine and understand the effect of substrate on the behavior of eutectic In-Sn. Samples for mechanical testing were produced with either bare Cu or Ni on Cu substrates. Both the microstructure and the mechanical behavior are strongly dependent on substrate. When eutectic In-Sn is joined to bare Cu, Cu diffusion into the joint causes the alloy to become off-eutectic, giving a nonuniform and irregular microstructure. The addition of a layer of Ni acts as a diffusion barrier, preventing Cu diffusion sufficiently such that a uniform, normal colony-based eutectic forms. Deformation is more uniform in the In-Sn on Ni, while it is concentrated along the length of the joint in the In-Sn on Cu. This distinction is reflected in the different shapes of shear stress-strain curves between In-Sn on Cu and In-Sn on Ni. The stress exponents and activation energies for creep also vary with substrate. Creep deformation is governed by the In-rich [beta] phase for In-Sn on Cu and by the Sn-rich [gamma] phase for In-Sn on Ni. If In-Sn on Ni samples are aged, the microstructure coarsens and the mechanical behavior changes to resemble that of the as-cast In-Sn on Cu.

Goldstein, J.L.F. (Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering); Morris, J.W. Jr. (Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering Lawrence Berkeley Lab., CA (United States))

1994-12-01

239

Microstructure and creep of eutectic indium\\/tin on copper and nickel substrates  

Microsoft Academic Search

The behavior during creep in shear of eutectic indium-tin joints on copper and nickel substrates was examined in order to determine the effect of creep deformation on the microstructure of the alloy. Primary creep was absent in all the samples tested. The stress exponent at 20° C was much higher for samples on nickel than for those on copper, indicating

J. L. Freer; J. W. Morris

1992-01-01

240

Microstructure and creep of eutectic indium/tin on copper and nickel substrates  

SciTech Connect

The behavior during creep in shear of eutectic indium-tin joints on copper and nickel substrates was examined in order to determine the effect of creep deformation on the microstructure of the alloy. Primary creep was absent in all the samples tested. The stress exponent at 20[degree] C was much higher for samples on nickel than for those on copper, indicating a different creep deformation mechanism. Also, the microstructure within the indium-tin joints differed significantly with a change of substrate. Samples with a nickel substrate showed a colony microstructure that was not observed in those with a copper substrate. Thus, eutectic morphology is important in determining deformation mechanism during creep. The microstructure within the joints in tested and untested regions of the samples was effectively the same. This is quite distinct from the behavior of eutectic lead-tin observed in previous work. Lead-tin formed a recrystallized band of material along a region of concentrated shear deformation. While the deformation pattern in the indium-tin samples appeared to be the same as for lead-tin, the microstructural changes did not occur. This implies that the behavior observed in lead-tin is not universal to eutectic alloys. 8 refs., 7 figs.

Freer, J.L.; Morris, J.W. Jr. (Lawrence Berkeley Lab., CA (United States))

1992-06-01

241

Kinetic Monte Carlo Simulations of Rod Eutectics and the Surface Roughening Transition in Binary Alloys.  

National Technical Information Service (NTIS)

In this paper we report on two related topics: Kinetic Monte Carlo simulations of the steady state growth of rod eutectics from the melt, and a study of the surface roughness of binary alloys. We have implemented a three dimensional kinetic Monte Carlo (k...

D. N. Bentz W. Betush K. A. Jackson

2003-01-01

242

Over-Modification Band in Aluminum--Silicon Eutectic Solidified Structure Modified with Sodium.  

National Technical Information Service (NTIS)

The nature and origin of so called ''over modification band'' which appears in the microscopic structure of eutectic Al--Si alloy treated with an excessive amount of sodium has been investigated in detail by the method of (1) the optical and scanning elec...

K. Kobayashi H. Shingu R. Ozaki

1972-01-01

243

Coarsening of silicon fibres in modified eutectic aluminium-silicon alloys  

Microsoft Academic Search

which formed adjacent to the mould walls during the initial stages of solidification. In the present work these effects were eliminated by using heated moulds, giving rise to fully eutectic microstructures. The alloys were examined in the as-cast state or after heat treatment at 510 ° C for 1.3, 8, 50 or 200 h. The morphology of the silicon phase

T. B. Abbott; B. A. Parker

1988-01-01

244

The role of trace element segregation in the eutectic modification of hypoeutectic Al–Si alloys  

Microsoft Academic Search

Modification of the eutectic silicon in hypoeutectic Al–Si alloys causes a structural transformation of the silicon phase from a needle-like to a fine fibrous morphology and is carried out extensively in industry to improve mechanical properties. It has been documented that the fibrous silicon phase in chemically modified alloys is heavily twinned. It has been proposed that this increased density

K. Nogita; H. Yasuda; M. Yoshiya; S. D. McDonald; K. Uesugi; A. Takeuchi; Y. Suzuki

2010-01-01

245

Directional solidification of aluminium-silicon eutectic alloy in a magnetic field  

NASA Astrophysics Data System (ADS)

By the use of a vertical Bridgman growth method, the Al-Si eutectic alloy containing 11.6 wt% Si was directionally solidified in a vertical magnetic field of 35,000 Oe and without the magnetic field. The application of the magnetic field showed a pronounced tendency to suppress the development of the primary Al phase dendrites.

Aoki, Y.; Hayashi, S.; Komatsu, H.

1983-06-01

246

About the shape of eutectic grains solidifying in a thermal gradient  

Microsoft Academic Search

In eutectic alloys solidified in a thermal gradient, it has been observed that the final shape of the grains nucleated in the bulk of the liquid is more elongated in the direction opposite to that of the heat flow. This experimental result appears to be in contraction with that expected for the growth of an isolated grain, since the portion

M. Rappaz; C. Charbon; R. Sasikumar

1994-01-01

247

Effect of superheating temperatures on microstructure and properties of strontium modified aluminium–silicon eutectic alloy  

Microsoft Academic Search

Superheating temperature on strontium modification of Al–Si alloy has tremendous effect on its solidification characteristics, which determines the structural refinement and hence the properties of the alloy. In this study, it is observed that as the superheating temperature is increased up to an optimum temperature of 750°C, the eutectic silicon becomes more globular and well distributed all over the entire

M. M. Haque; Ahmad F. Ismail

2005-01-01

248

Influence of Mg on Grain Refinement of Near Eutectic Al-Si Alloys  

NASA Astrophysics Data System (ADS)

Although the grain-refinement practice is well established for wrought Al alloys, in the case of foundry alloys such as near eutectic Al-Si alloys, the underlying mechanisms and the use of grain refiners need better understanding. Conventional grain refiners such as Al-5Ti-1B are not effective in grain refining the Al-Si alloys due to the poisoning effect of Si. In this work, we report the results of a newly developed grain refiner, which can effectively grain refine as well as modify eutectic and primary Si in near eutectic Al-Si alloys. Among the material choices, the grain refining response with Al-1Ti-3B master alloy is found to be superior compared to the conventional Al-5Ti-1B master alloy. It was also found that magnesium additions of 0.2 wt pct along with the Al-1Ti-3B master alloy further enhance the near eutectic Al-Si alloy's grain refining efficiency, thus leading to improved bulk mechanical properties. We have found that magnesium essentially scavenges the oxygen present on the surface of nucleant particles, improves wettability, and reduces the agglomeration tendency of boride particles, thereby enhancing grain refining efficiency. It allows the nucleant particles to act as potent and active nucleation sites even at levels as low as 0.2 pct in the Al-1Ti-3B master alloy.

Ravi, K. R.; Manivannan, S.; Phanikumar, G.; Murty, B. S.; Sundarraj, Suresh

2011-07-01

249

Aluminium phosphide as a eutectic grain nucleus in hypoeutectic Al-Si alloys.  

PubMed

Aluminium phosphide (AlP) particles are often suggested to be the nucleation site for eutectic silicon in Al-Si alloys, since both the crystal structure and lattice parameter of AlP (crystal structure: cubic F43m; lattice parameter: 5.421 A) are close to that of silicon (cubic Fd3m, 5.431 A), and the melting point is higher than the Al-Si eutectic temperature. However, the crystallographic relationships between AlP particles and the surrounding eutectic silicon are seldom reported due to the difficulty in analysing the AlP particles, which react with water during sample preparation for polishing. In this study, the orientation relationships between AlP and Si are analysed by transmission electron microscopy using focused ion-beam milling for sample preparation to investigate the nucleation mechanism of eutectic silicon on AlP. The results show a clear and direct lattice relationship between centrally located AlP particles and the surrounding silicon in the hypoeutectic Al-Si alloy. PMID:15585468

Nogita, Kazuhiro; McDonald, Stuart D; Tsujimoto, Katsuhiro; Yasuda, Kazuhiro; Dahle, Arne K

2004-01-01

250

On the relation between primary and eutectic solidification structures in gray iron  

NASA Astrophysics Data System (ADS)

The solidification of hypoeutectic gray cast iron starts with the nucleation of primary austenite crystals. Before graphite is nucleated, and the eutectic structure is formed, these crystals start to grow as columnar or equiaxed dendrites. However, very little is known about these dendrites, and especially how they influence the subsequent eutectic structure. Besides, it has previously been shown that the primary solidification structure influences the formation of defects. Shrinkage porosity was found between the dendrites, in the grain boundaries, and the formation of the primary solidification structure was found to influence problems related to metal expansion penetration. Therefore a better understanding about the formation of this structure is of importance. In this work, different inoculants and their influence on the formation of the micro- and macrostructures has been investigated. The inoculants considered are commercially used inoculants, i.e. inoculants used in the foundries, as well as different iron powders. The addition of iron powder is used to promote the primary solidification structure. It is shown that the nucleation of the dendrites is influenced by the amount of iron powder. Secondary dendrite arm spacing is a quantitative measurement in the microstructure related to these dendrites, which in turn depends on the solidification time. Eutectic cell size, on the other hand, is found to depend on secondary dendrite arm spacing. It is shown how the addition of inoculants influences both primary and eutectic solidification structures, and how they are related to each other.

Elmquist, L.; Sonawane, P. A.

2012-01-01

251

Diffusion Welding of a Directionally Solidified gamma/gamma Prime - delta Eutectic Alloy.  

National Technical Information Service (NTIS)

Hot-press diffusion welding parameters were developed for a directionally solidified, gamma/gamma prime-delta eutectic alloy. Based on metallography, a good diffusion weld was achieved at 1100 C under 34.5 MPa (5 ksi) pressure for 1 hour. In addition, a d...

T. J. Moore

1977-01-01

252

Natural deep eutectic solvents as new potential media for green technology.  

PubMed

Developing new green solvents is one of the key subjects in Green Chemistry. Ionic liquids (ILs) and deep eutectic solvents, thus, have been paid great attention to replace current harsh organic solvents and have been applied to many chemical processing such as extraction and synthesis. However, current ionic liquids and deep eutectic solvents have still limitations to be applied to a real chemical industry due to toxicity against human and environment and high cost of ILs and solid state of most deep eutectic solvents at room temperature. Recently we discovered that many plant abundant primary metabolites changed their state from solid to liquid when they were mixed in proper ratio. This finding made us hypothesize that natural deep eutectic solvents (NADES) play a role as alternative media to water in living organisms and tested a wide range of natural products, which resulted in discovery of over 100 NADES from nature. In order to prove deep eutectic feature the interaction between the molecules was investigated by nuclear magnetic resonance spectroscopy. All the tested NADES show clear hydrogen bonding between components. As next step physical properties of NADES such as water activity, density, viscosity, polarity and thermal properties were measured as well as the effect of water on the physical properties. In the last stage the novel NADES were applied to the solubilization of wide range of biomolecules such as non-water soluble bioactive natural products, gluten, starch, and DNA. In most cases the solubility of the biomolecules evaluated in this study was greatly higher than water. Based on the results the novel NADES may be expected as potential green solvents at room temperature in diverse fields of chemistry. PMID:23427801

Dai, Yuntao; van Spronsen, Jaap; Witkamp, Geert-Jan; Verpoorte, Robert; Choi, Young Hae

2013-03-01

253

Transient and steady state creep response of ice I and magnesium sulfate hydrate eutectic aggregates  

USGS Publications Warehouse

Using uniaxial compression creep experiments, we characterized the transient and steady state deformation behaviors of eutectic aggregates of system ice I and MgSO4 11H2O (MS11; meridianiite), which has significance because of its likely presence on moons of the outer solar system. Synthetic samples of eutectic liquid bulk composition, which produce eutectic colonies containing 0.35-0.50 volume fraction MS11, were tested as functions of colony size and lamellar spacing, temperature (230-250 K), and confining pressure (0.1 and 50 MPa) to strains ???0.2. Up to a differential stress of 6 MPa, the ice I-MS11 aggregates display an order of magnitude higher effective viscosity and higher stress sensitivity than do aggregates of pure polycrystalline ice at the same conditions. The creep data and associated microstructural observations demonstrate, however, that the aggregates are additionally more brittle than pure ice, approaching rate-independent plasticity that includes rupture of the hydrate phase at 6-8 MPa, depending on the scale of the microstructure. Microstructures of deformed samples reveal forms of semibrittle flow in which the hydrate phase fractures while the ice phase deforms plastically. Semibrittle flow in the icy shell of a planetary body would truncate the lithospheric strength envelope and thereby decrease the depth to the brittle-ductile transition by 55% and reduce the failure limit for compressional surface features from 10 to ???6 MPa. A constitutive equation that includes eutectic colony boundary sliding and intracolony flow is used to describe the steady state rheology of the eutectic aggregates. Copyright ?? 2011 by the American Geophysical Union.

McCarthy, C.; Cooper, R. F.; Goldsby, D. L.; Durham, W. B.; Kirby, S. H.

2011-01-01

254

On the nature of eutectic carbides in Cr-Ni white cast irons  

NASA Astrophysics Data System (ADS)

The mechanical and tribological properties of white cast irons are strongly dependent on whether they contain M7C3 or M3C carbides (M = Fe, Cr, etc.). In an effort to improve the wear resistance of such materials, the United States Bureau of Mines has studied the effects of adding 0.3 to 2.3 wt pct (throughout) Si to hypoeutectic irons containing approximately 8.5 pct Cr and 6.0 pct Ni. The eutectic carbides formed were identified by electron microprobe analysis, X-ray diffraction, and scanning electron (SEM) and optical microscopies. In addition, differential thermal analysis (DTA) was used to study the process of solidification. At Si contents of 0.3 and 1.2 pct, the eutectic carbides exhibited a duplex structure, consisting of cores of M7C3 surrounded by shells of M3C. Additionally, the microstructure contained ledeburite (M3C + ?Fe (austenite)). At the higher Si content of 1.6 pct, the eutectic carbides consisted entirely of M7C3, and some ledeburite remained. Last, when the Si content was raised to 2.3 pct, the eutectic carbides again consisted entirely of M7C3, but ledeburite was no longer formed. These observations can be explained in terms of the effects of Si and, to a lesser extent, of Ni on the shape of the liquidus surface of the metastable Fe-Cr-C phase diagram. The addition of Si reduces the roles played by the four-phase class II p reaction L + M7C3 ? M3C + ?Fe and the ledeburitic eutectic reaction L ? M3C + ?Fe in the overall process of solidification.

Laird, G.; Nielsen, R. L.; MacMillan, N. H.

1991-08-01

255

The fabrication of all-silicon micro gas chromatography columns using gold diffusion eutectic bonding  

NASA Astrophysics Data System (ADS)

Temperature programming of gas chromatography (GC) separation columns accelerates the elution rate of chemical species through the column, increasing the speed of analysis, and hence making it a favorable technique to speedup separations in microfabricated GCs (micro-GC). Temperature-programmed separations would be preferred in an all-silicon micro-column compared to a silicon-Pyrex® micro-column given that the thermal conductivity and diffusivity of silicon is 2 orders of magnitude higher than Pyrex®. This paper demonstrates how to fabricate all-silicon micro-columns that can withstand the temperature cycling required for temperature-programmed separations. The columns were sealed using a novel bonding process where they were first bonded using a gold eutectic bond, then annealed at 1100 °C to allow gold diffusion into silicon and form what we call a gold diffusion eutectic bond. The gold diffusion eutectic-bonded micro-columns when examined using scanning electron microscopy (SEM), scanning acoustic microscopy (SAM) and blade insertion techniques showed bonding strength comparable to the previously reported anodic-bonded columns. Gas chromatography-based methane injections were also used as a novel way to investigate proper sealing between channels. A unique methane elution peak at various carrier gas inlet pressures demonstrated the suitability of gold diffusion eutectic-bonded channels as micro-GC columns. The application of gold diffusion eutectic-bonded all-silicon micro-columns to temperature-programmed separations (120 °C min-1) was demonstrated with the near-baseline separation of n-C6 to n-C12 alkanes in 35 s.

Radadia, A. D.; Salehi-Khojin, A.; Masel, R. I.; Shannon, M. A.

2010-01-01

256

SALT for Language Acquisition.  

ERIC Educational Resources Information Center

Discusses Schuster's Suggestive-Accelerative Learning Techniques (SALT) Method, which combines Lozanov's Suggestopedia with such American methods as Asher's Total Physical Response and Galyean's Confluent Education. The article argues that students trained with the SALT Method have higher achievement scores and better attitudes than others. (14…

Bancroft, W. Jane

1996-01-01

257

Molten salt electrolyte separator  

DOEpatents

The patent describes a molten salt electrolyte/separator for battery and related electrochemical systems including a molten electrolyte composition and an electrically insulating solid salt dispersed therein, to provide improved performance at higher current densities and alternate designs through ease of fabrication. 5 figs.

Kaun, T.D.

1996-07-09

258

A History of Salt  

Microsoft Academic Search

The medical history of salt begins in ancient times and is closely related to different aspects of human history. Salt may be extracted from sea water, mineral deposits, surface encrustations, saline lakes and brine springs. In many inland areas, wood was used as a fuel source for evaporation of brine and this practice led to major deafforestation in central Europe.

Massimo Círillo; Giovambattista Capasso; Vito Andrea Di Leo; Natale Gaspare De Santo

1994-01-01

259

Acids and Salts (GCMP)  

NSDL National Science Digital Library

Acids and Salts: this is a resource in the collection "General Chemistry Multimedia Problems". This problem will explore a few properties of common acids and their salts. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

260

Reliability of Au-Ge and Au-Si Eutectic Solder Alloys for High-Temperature Electronics  

NASA Astrophysics Data System (ADS)

High-temperature electronics will facilitate deeper drilling, accessing harder-to-reach fossil fuels in oil and gas industry. A key requirement is reliability under harsh conditions for a minimum continuous operating time of 500 h at 300°C. Eutectic solder alloys are generally favored due to their excellent fatigue resistance. Performance of Au-Ge and Au-Si eutectic solder alloys at 300°C up to 500 h has been evaluated. Nanoindentation results confirm the loss of strength of Au-Ge and Au-Si eutectic solder alloys during thermal aging at 300°C, as a result of grain coarsening. However, the pace at which the Au-Ge eutectic alloy loses its strength is much slower when compared with Au-Si eutectic alloy. The interfacial reactions between these eutectic solder alloys and the underbump metallization (UBM), i.e., electroless nickel immersion gold (ENIG) UBM and Cu/Au UBM, have been extensively studied. Spalling of Au3Cu intermetallic compound is observed at the interface between Au-Ge eutectic solder and the Cu/Au UBM, when aged at 300°C for 500 h, while the consumption of ENIG UBM is nominal. Unlike the Au-Si solder joint, hot ball shear testing at high temperature confirmed that the Au-Ge joint on ENIG UBM, when aged at 300°C for 500 h, could still comply with the minimum qualifying bump shear strength based on the UBM dimension used in this work. Thus, it has been determined that, among these two binary eutectic alloys, Au-Ge eutectic alloy could fulfill the minimum requirement specified by the oil and gas exploration industry.

Chidambaram, Vivek; Yeung, Ho Beng; Shan, Gao

2012-08-01

261

Removal of nanoaerosol during the bubbling of the salt melt of beryllium and lithium fluorides for the preparation of reactor radioisotopes  

Microsoft Academic Search

The parameters of aerosol particles formed in the course of the spontaneous thermal condensation of vapors and bubbling a 66LiF-34BeF2 (mol %) eutectic salt mixture with helium have been studied. For this purpose, a vertical bubbling mode at T ≈ 900 K and an ampule device for obtaining reactor radioisotopes for medical applications were used. The rate of the bulk

A. V. Zagnit'ko; D. Yu. Chuvilin

2010-01-01

262

Removal of nanoaerosol during the bubbling of the salt melt of beryllium and lithium fluorides for the preparation of reactor radioisotopes  

Microsoft Academic Search

The parameters of aerosol particles formed in the course of the spontaneous thermal condensation of vapors and bubbling a\\u000a 66LiF-34BeF2 (mol %) eutectic salt mixture with helium have been studied. For this purpose, a vertical bubbling mode at T ? 900 K and an ampule device for obtaining reactor radioisotopes for medical applications were used. The rate of the bulk

A. V. Zagnit’ko; D. Yu. Chuvilin

2010-01-01

263

Mg-Al-Ca In-Situ Composites with a Refined Eutectic Structure and Their Compressive Properties  

Microsoft Academic Search

In a series of Mg\\u000a x\\u000a (Al2Ca)100?x\\u000a (76 ? x ? 87) ternary alloys near the Mg-(Mg,Al)2Ca pseudo-binary eutectic point, different phases and morphologies based on ultrafine eutectic microstructure have been obtained\\u000a by controlling the composition and changing the cooling rate via either induction melting or copper mold casting. For 81 ? x ? 87, the chill-cast alloys with ductile Mg dendrites embedded in an ultrafine [Mg + (Mg,Al)2Ca] eutectic

Ling-Ling Shi; Jian Xu; Evan Ma

2008-01-01

264

Amine Salts as Bonding Agents.  

National Technical Information Service (NTIS)

The polyamine compound, TEPAN, a partially cyanoethylated tetraethylene pentamine, is reacted with a selected ammonium salt to form an adduct of TEPAN and the selected ammonium salt. The ammonium salt is selected from ammonium perchlorate (AP), ammonium n...

M. E. Ducote H. C. Allen

1983-01-01

265

Fetal bile salt metabolism  

PubMed Central

Bile salt metabolism was studied in fetal dogs 1 wk before term. The size and distribution of the fetal bile salt pool were measured, and individual bile salts were identified. The hepatic excretion of endogenous bile salts was studied in bile fistula fetuses, and the capacity of this excretory mechanism was investigated by the i.v. infusion of a load of sodium taurocholate-14C up to 20 times the endogenous pool size. The total fetal bile salt pool was 30.9±2.7 ?moles, of which two-thirds was in the fetal gallbladder. Expressed on a body weight basis, this was equal to approximately one-half the estimated pool size in the adult dog (119.2±11.3 vs. 247.5±33.1 ?moles/kg body wt). Measurable quantities of bile salt were found in small bowel (6.0±1.8 ?moles), large bowel (1.1±0.3 ?moles), liver (1.2±0.5 ?moles), and plasma (0.1±0.03 ?moles). Plasma bile salt levels were significantly greater in fetal than in maternal plasma (1.01±0.24 ?g/ml vs. 0.36±0.06 ?g/ml; P < 0.05). Fetal hepatic bile salt excretion showed a fall over the period of study from 2.04±0.34 to 0.30±0.07 ?moles/hr. The maximal endogenous bile salt concentration in fetal hepatic bile was 18.7±1.5 ?moles/ml. The concentration in fetal gallbladder bile was 73.9±8.6 ?moles/ml; and, in those studies in which hepatic and gallbladder bile could be compared directly, the gallbladder appeared to concentrate bile four- to fivefold. Taurocholate, taurochenodeoxycholate, and taurodeoxycholate were present in fetal bile, but no free bile salts were identified. The presence of deoxycholate was confirmed by thin-layer chromatography and gas liquid chromatography, and the absence of microorganisms in fetal gut suggests that it was probably transferred from the maternal circulation. After infusion of a taurocholate load, fetal hepatic bile salt excretion increased 30-fold, so that 85-95% of the dose was excreted by the fetal liver during the period of observation. Placental transfer accounted for less than 5% of the dose. Fetal bile volume increased 15-fold on average, while bile salt concentrations increased two- to threefold. It is concluded that bile salt is taken up, conjugated, and excreted by the fetal liver with remarkable efficiency. The excreted material is either stored and concentrated in the fetal gallbladder or released into the intestine and reabsorbed to be reexcreted in bile.

Smallwood, R. A.; Lester, R.; Piasecki, G. J.; Klein, P. D.; Greco, R.; Jackson, B. T.

1972-01-01

266

Seasonal flows on dark martian slopes, thermal condition for liquescence of salts  

NASA Astrophysics Data System (ADS)

RSLs are narrow, dark albedo features on relatively steep slopes that appear during warm seasons and fade in the cold ones. So far they have only been observed in mid-latitudes where surface temperature is too high, periodically exceeding 300 K, for the presence of shallow ground ice. We attempt to determine what conditions are needed for the liquescence of salt to occur exactly when the RSLs are observed. If the eutectic temperature is exceeded, and humidity is high enough, salts may produce liquid brines through absorption of water vapor and liquescence. We calculate regolith temperature as a function of time and depth, for different macroscopic distributions of salt, for two different microphysical models of the distribution of salt on the regolith grains. Model parameters which are varied include surface albedo, thermal inertia of the dry regolith, the depths at which salt is present, and the salt content. We find that it is possible, for liquescence of magnesium perchlorate to occur where and when RSLs have been observed, but only within a very narrow range of parameters.

Kossacki, Konrad J.; Markiewicz, Wojciech J.

2014-05-01

267

Crushed Salt Constitutive Model  

SciTech Connect

The constitutive model used to describe the deformation of crushed salt is presented in this report. Two mechanisms -- dislocation creep and grain boundary diffusional pressure solution -- are combined to form the basis for the constitutive model governing the deformation of crushed salt. The constitutive model is generalized to represent three-dimensional states of stress. Upon complete consolidation, the crushed-salt model reproduces the Multimechanism Deformation (M-D) model typically used for the Waste Isolation Pilot Plant (WIPP) host geological formation salt. New shear consolidation tests are combined with an existing database that includes hydrostatic consolidation and shear consolidation tests conducted on WIPP and southeastern New Mexico salt. Nonlinear least-squares model fitting to the database produced two sets of material parameter values for the model -- one for the shear consolidation tests and one for a combination of the shear and hydrostatic consolidation tests. Using the parameter values determined from the fitted database, the constitutive model is validated against constant strain-rate tests. Shaft seal problems are analyzed to demonstrate model-predicted consolidation of the shaft seal crushed-salt component. Based on the fitting statistics, the ability of the model to predict the test data, and the ability of the model to predict load paths and test data outside of the fitted database, the model appears to capture the creep consolidation behavior of crushed salt reasonably well.

Callahan, G.D.

1999-02-01

268

Stress Analysis, Thermomechanical Fatique Evaluation, and Root Subcomponent Testing of gamma/gamma Prime-delta Eutectic Alloy.  

National Technical Information Service (NTIS)

Thermomechanical fatigue (TMF) and root subcomponent tensile, creep, and low cycle fatigue (LCF) tests were conducted to determine the capability of a fully lamellar directionally solidified eutectic alloy to sustain the airfoil thermal fatigue and root a...

K. D. Sheffler J. J. Jackson

1976-01-01

269

Automated detection and characterization of microstructural features: application to eutectic particles in single crystal Ni-based superalloys  

NASA Astrophysics Data System (ADS)

Serial sectioning methods continue to produce an abundant amount of image data for quantifying the three-dimensional nature of material microstructures. Here, we discuss a methodology to automate detecting and characterizing eutectic particles taken from serial images of a production turbine blade made of a heat-treated single crystal Ni-based superalloy (PWA 1484). This method includes two important steps for unassisted eutectic particle characterization: automatically identifying a seed point within each particle and segmenting the particle using a region growing algorithm with an automated stop point. Once detected, the segmented eutectic particles are used to calculate microstructural statistics for characterizing and reconstructing statistically representative synthetic microstructures for single crystal Ni-based superalloys. The significance of this work is its ability to automate characterization for analysing the 3D nature of eutectic particles.

Tschopp, M. A.; Groeber, M. A.; Fahringer, R.; Simmons, J. P.; Rosenberger, A. H.; Woodward, C.

2010-03-01

270

Correlation between fragility and eutectic instability and glass-forming ability in binary metallic glasses under growth controlled conditions  

NASA Astrophysics Data System (ADS)

We find that the fragility can be correlated to the eutectic instability and the glass forming ability in binary metallic glass formers under growth controlled conditions via a dimensionless parameter ? defined as DfT0/2(Te - T0), where Df is fragility parameter, T0 is Vogel-Fulcher-Tammann temperature, and Te is eutectic temperature. It is shown that the large ? value, which results from high Df and from that T0 is close to the eutectic temperature, can lead to small interface growth velocity and undercooling of eutectic structure, and good glass forming ability. This indicates that high ? leads to small characteristic diffusion length resulting from sluggish material transport that governs the glass forming ability. The results might provide an in-depth insight into the glass formation mechanism and be helpful for searching new glasses in growth controlled process.

Wang, N.; Ji, L.; Yao, W. J.; Zheng, Y. P.

2012-05-01

271

Growth and microstructure evolution of the Nb{sub 2}Al-Al{sub 3}Nb eutectic in situ composite  

SciTech Connect

In situ composite materials obtained by directional growth of eutectic alloys usually show improved properties, that make them potential candidates for high temperature applications. The eutectic alloy found in the Al-Nb system is composed of the two intermetallic phases Al{sub 3}Nb (D0{sub 22}) and Nb{sub 2}Al (D8{sub b}). This paper describes the directional solidification of an Al-Nb eutectic alloy using a Bridgman type facility at growth rates varying from 1.0 to 2.9 cm/h. Longitudinal and transverse sections of grown samples were characterized regarding the solidification microstructure by using optical and scanning electron microscopy, energy dispersive spectroscopy (EDS) and X-ray diffraction. Despite both phases being intermetallic compounds, the eutectic microstructure obtained was very regular. The results obtained were discussed regarding the effect of the growth rate on the microstructure, lamellar-rod transition and variation of phase volume fraction.

Rios, C.T. [State University of Campinas, P.O. Box 6122, Campinas, SP 13083-970 (Brazil); Ferrandini, P.L. [Centro Universitario da FEI, C.P.85, CEP:09850-901, SP-Brasil (Brazil); Milenkovic, S. [State University of Campinas, P.O. Box 6122, Campinas, SP 13083-970 (Brazil); Caram, R. [State University of Campinas, P.O. Box 6122, Campinas, SP 13083-970 (Brazil)]. E-mail: rcaram@fem.unicamp.br

2005-03-15

272

Peculiarities of aluminium interaction with Ga85In15 eutectics as evidenced by X-ray synchrotron diagnostics  

NASA Astrophysics Data System (ADS)

A set of X-ray synchrotron techniques, viz., diffraction, EXAFS/XANES spectroscopy and microtomography, is applied to elucidate microstructural changes in a technical aluminium alloy treated with GaIn eutectics. Such a treatment gives rise simultaneously to a prominent enbrittlement of the material and its activation towards reaction with water with the hydrogen evolution. The latter fact makes the activated aluminium a promising energy carrier for the small-scale hydrogen energetics. It is demonstrated that both phenomena are caused by the fast diffusion of the eutectics along intergrain boundaries and microcracks throughout the bulk of polycrystalline Al. The diffusion is promoted by the formation of (Al-Ga-In) solid solution in near-surface regions of Al crystalline grains. The progressive loss of activity of aluminium treated with GaIn eutectics upon a prolonged storage in humid air is due to the decomposition of the eutectics accompanied by the segregation of indium metal and partial gallium oxidation.

Nizovskii, A. I.; Bukhtiyarov, V. I.; Veligzhanin, A. A.; Zubavichus, Y. V.; Murzin, V. Y.; Chernyshov, A. A.; Khlebnikov, A. S.; Senin, R. A.; Kazakov, I. V.; Vorobyov, A. A.

2012-09-01

273

Soluble salts at the Phoenix Lander site, Mars: A reanalysis of the Wet Chemistry Laboratory data  

NASA Astrophysics Data System (ADS)

The Wet Chemistry Laboratory (WCL) on the Phoenix Mars Scout Lander analyzed soils for soluble ions and found Ca2+, Mg2+, Na+, K+, Cl-, SO42-, and ClO4-. The salts that gave rise to these ions can be inferred using aqueous equilibrium models; however, model predictions are sensitive to the initial solution composition. This is problematic because the WCL data is noisy and many different ion compositions are possible within error bounds. To better characterize ion concentrations, we reanalyzed WCL data using improvements to original analyses, including Kalman optimal smoothing and ion-pair corrections. Our results for Rosy Red are generally consistent with previous analyses, except that Ca2+ and Cl- concentrations are lower. In contrast, ion concentrations in Sorceress 1 and Sorceress 2 are significantly different from previous analyses. Using the more robust Rosy Red WCL analysis, we applied equilibrium models to determine salt compositions within the error bounds of the reduced data. Modeling with FREZCHEM predicts that WCL solutions evolve Ca-Mg-ClO4-rich compositions at low temperatures. These unusual compositions are likely influenced by limitations in the experimental data used to parameterize FREZCHEM. As an alternative method to evaluate salt assemblages, we employed a chemical divide model based on the eutectic temperatures of salts. Our chemical divide model predicts that the most probable salts in order of mass abundance are MgSO4·11H2O (meridianiite), MgCO3·nH2O, Mg(ClO4)2·6H2O, NaClO4·2H2O, KClO4, NaCl·2H2O (hydrohalite), and CaCO3 (calcite). If ClO3- is included in the chemical divide model, then NaClO3 precipitates instead of NaClO4·2H2O and Mg(ClO3)2·6H2O precipitates in addition to Mg(ClO4)2·6H2O. These salt assemblages imply that at least 1.3 wt.% H2O is bound in the soil, noting that we cannot account for water in hydrated insoluble salts or deliquescent brines. All WCL solutions within error bounds precipitate Mg(ClO4)2·6H2O and/or Mg(ClO3)2·6H2O salts. These salts have low eutectic temperatures and are highly hygroscopic, which suggests that brines will be stable in soils for much of the Martian summer.

Toner, J. D.; Catling, D. C.; Light, B.

2014-07-01

274

Amine salts of nitroazoles  

DOEpatents

Compositions of matter, a method of providing chemical energy by burning said compositions, and methods of making said compositions are described. These compositions are amine salts of nitroazoles. 1 figure.

Kienyin Lee; Stinecipher, M.M.

1993-10-26

275

Poor Teenage Salt Habits  

MedlinePLUS Videos and Cool Tools

... MedlinePlus Pages Dietary Sodium Nutrition Obesity in Children Teen Health Transcript Open almost any kitchen cabinet and ... dietary fixture across all age groups with today's teens consuming as much salt as adults. After tracking ...

276

Aging characteristics of Ga\\/1-x\\/\\/Al\\/x\\/As double-heterostructure lasers bonded with gold eutectic alloy solder  

Microsoft Academic Search

Aging characteristics of Ga1?xAlxAs DH lasers bonded with gold eutectic alloy solder and indium solder were studied. In the lasers bonded with indium solder, it was found that thermal resistance increased during the aging test and the activation energy for the increasing rate of thermal resistance was 0.6 eV. Sixteen lasers bonded with gold-tin eutectic alloy solder have been operating

K. Fujiwara; T. Fujiwara; K. Hori; M. Takusagawa

1979-01-01

277

A cobalt carbon eutectic fixed point for the calibration of contact thermometers at temperatures above 1100 °C  

Microsoft Academic Search

A vertical cobalt-carbon (Co-C) eutectic fixed point cell was constructed at PTB to demonstrate its use for improvement of the calibration of noble-metal thermocouples at temperatures above 1100 °C. The melting and freezing temperatures of the Co-C eutectic were measured in different high-temperature furnaces at PTB and INMETRO (Brazil) to show its stability by using a Pt\\/Pd thermocouple. The reproducibility

F. Edler; A. C. Baratto

2005-01-01

278

Refinement of promising coating compositions for directionally cast eutectics. [Ni19. 7Nb6Cr2. 5Al  

Microsoft Academic Search

The successful application of high creep strength, directionally solidified gamma\\/gamma'-delta (Ni--19.7Nb--6Cr--2.5Al) eutectic superalloy turbine blades requires the development of suitable coatings for airfoil, root and internal blade surfaces. In order to improve coatings for the gamma\\/gamma'-delta alloy, the current investigation had the goals of refining promising coating compositions for directionally solidified eutectics, evaluating the effects of coating\\/substrate interactions on the

T. E. Strangman; E. J. Felten; R. S. Benden

1976-01-01

279

Compatibility of surface-coated steels, refractory metals and ceramics to high temperature lead–bismuth eutectic  

Microsoft Academic Search

Compatibility of cladding material with lead–bismuth eutectic at temperature higher than 650°C is one of the most crucial issues for feasibility of lead–bismuth-cooled fast reactors with cycle efficiency as high as 40%. In order to search for corrosion-resistant materials with lead–bismuth eutectic at temperature higher than 650°C, surface-coated steels, some refractory metals and various ceramics were tested by means of

Abu Khalid Rivai; Minoru Takahashi

2008-01-01

280

Hardness and mechanical property relationships in directionally solidified aluminium-silicon eutectic alloys with different silicon morphologies  

Microsoft Academic Search

Hardness and tensile property measurements made on directionally solidified Al-Si eutectic alloys show that definite but different hardness-growth velocity and hardness-silicon interparticle spacing relationships exist for alloys with different silicon eutectic phase morphologies. Tensile property measurements show that hardness and 0.2% proof stress follow silicon interparticle spacing relationships of the same form. It is suggested that hardness can only be

S. Khan; A. Ourdjini; Q. S. Named; M. A. Alam Najafabadi; R. Elliott

1993-01-01

281

The effects of a eutectic modifier on microstructure and surface corrosion behavior of Al-Si hypoeutectic alloys  

Microsoft Academic Search

Hypoeutectic aluminum–silicon alloys can have significant improvements in mechanical properties by inducing structural modification\\u000a in the normally occurring eutectic. The eutectic modification may affect not only the mechanical properties but also the corrosion\\u000a resistance of such alloys. It is well known that structural parameters such as grain size and interdendritic spacing can significantly\\u000a affect corrosion resistance of alloys. However, to

Wislei R. Osório; Noé Cheung; José E. Spinelli; Pedro R. Goulart; Amauri Garcia

2007-01-01

282

Creep properties of eutectic Sn3.5Ag solder joints reinforced with mechanically incorporated Ni particles  

Microsoft Academic Search

The creep deformation behavior of eutectic Sn-3.5Ag based Ni particle rein forced composite solder joints was investigated.\\u000a The Ni particle reinforced composite solder was prepared by mechanically dispersing 15 vol.% of Ni particles into eutectic\\u000a Sn-3.5Ag solder paste. Static-loading creep tests were carried out on solder joint specimens at 25 C, 65 C, and 105 C, representing\\u000a homologous temperatures ranging

F. Guo; J. Lee; J. P. Lucas; K. N. Subramanian; T. R. Bieler

2001-01-01

283

Enhancement of coupled growth of off-eutectic alloys by ``stop-and-go'' technique  

NASA Astrophysics Data System (ADS)

The beneficial effect of solutal (gravity induced) or other convective segregation on promoting plane front growth in directionally solidified off-eutectic alloys has been investigated. Specifically, it has been found that halting directional solidification for periods of the order an hour frequently results in plane front growth after resumption of solidification in alloys which originally grow dendritically. This is attributed to liquid homogenization during the stop period. This homogenization produces a liquid with composition within the coupled growth region. The process has been analyzed and conditions under which this process is feasible are related to the alloy composition and phase diagram characteristics as well as the growth parameters, thermal gradient, and solidification rate. The process is illustrated by and the analysis compared with selected experiments in the Co-CoAl eutectic.

Frydman, S. S.; Courtney, T. H.

1982-06-01

284

Directional solidification of (Ti, Zr) carbide-(Ti, Zr) diboride eutectics  

SciTech Connect

The ZrC-ZrB2, ZrC-TiB2, and TiC-TiB2 metal diboride-metal carbide pseudo-binary eutectic systems have been successfully solidified directionally by means of the floating zone method. The first and third of these eutectics possess a morphology consisting of columnar grains of parallel lamellae with interlamellar spacings that adhere to the lambda-squared (R) C relationship, while the second is noted to solidify in a Chinese calligraphy-like morphology of broken and deformed lamellae. This phenomenon may be related to solid solution effects, but it did not prevent the interlamellar spacings from following the aforementioned law. The calligraphic effect's values are larger than those of the other two systems, and the constant, C, is accordingly about an order of magnitude larger. All three of these cubic-hexagonal systems exhibited identical epitaxial relationships. 24 references.

Sorrell, C.C.; Beratan, H.R.; Bradt, R.C.; Stubican, V.C.

1984-03-01

285

Development of Ti/Ti{sub 3}Sn functionally gradient material produced by eutectic bonding method  

SciTech Connect

Although many materials which have a single function have been developed, future needs are anticipated to include materials which have various functions. A functionally gradient material (FGM) which has characteristics of two different materials is a promising candidate for multi-functional material. The present methods for production of FGM, however, are very complicated and costly. In this study the authors answer the serious problem of high production cost by fabricating the FGM by a eutectic bonding method. This fabrication method includes structural control of FGM by changing the cooling process. They describe Ti/Ti{sub 3}Sn FGM obtained by the eutectic bonding method, and tell how the structure of its composition gradient part is changed by controlling the cooling process.

Kirihara, S.; Takeda, M.; Tsujimoto, T. [Ibaraki Univ., Hitachi (Japan). Faculty of Engineering] [Ibaraki Univ., Hitachi (Japan). Faculty of Engineering

1996-07-15

286

Formation of a crystallization courtyard in eutectic systems and crystal growth  

NASA Astrophysics Data System (ADS)

The so-called crystallization courtyard is investigated that forms in processes of mass crystallization around the Ge and Si crystals and their solid solutions (Ge+Si) during cooling of hypereutectic alloys in the Ge-Al, Si-Al, and (Ge+Si)-Al eutectic systems. For the first time, data on the composition and microhardness of this crystallization courtyard are given and its role is shown as a stopper of cracking in an Al-(Ge,Si) system during rapid cooling after the heating system is turned off. For the first time, it is suggested that a crystallization courtyard forms in all hypereutectic systems (including every system in which the amount of the taken solvent does not correspond to the eutectic point).

Gurin, V. N.; Osipov, V. N.; Derkachenko, L. I.; Korchunov, B. N.; Popova, T. B.

2014-03-01

287

High temperature oxidation resistant coatings for the directionally solidified Ni-Nb-Cr-Al eutectic superalloy  

NASA Technical Reports Server (NTRS)

Protective coatings required for the Ni-Nb-Cr-Al directionally solidified eutectic superalloy were developed and evaluated on the basis of oxidation resistance, diffusional stability, thermal fatigue, and creep resistance. NiCrAlY+Pt and NiCrAlY physical vapor-deposition coating systems exhibited the best combination of properties. Burner-rig testing indicated that the useful life of a 127-micron-thick NiCrAlY+Pt coating exceeds 1000 h at 1366 K. Eutectic-alloy creep lives at 1311 K and a stress of 151.7 MN/sq m were greater for NiCrAlY+Pt-coated specimens than for uncoated specimens by a factor of two.

Strangman, T. E.; Ulion, N. E.; Felten, E. J.

1977-01-01

288

Microstructural Effects on High Cycle Fatigue of Ni-AI-Mo Aligned Eutectics  

NASA Astrophysics Data System (ADS)

Two nickel-base aligned eutectics, AG15 (Ni-8.1 wt pct Al-26.4 wt pct Mo) and AG34 (Ni-6.3 wt pct Al-31.2 wt pct Mo), have been tested in high cycle fatigue at room temperature. Experimental variables were test environment and post-solidification heat treatment. The fatigue lives of both alloys and the crack propagation resistance of AG15 improved substantially in tests performed in vacuum vs those performed in air. AG34 had a higher fatigue limit than AGI5; both alloys showed surface initiation and stage I crack propagation. Post-solidification heat treatment had a beneficial effect on the S-N lives of AG34 specimens. Fatigue resistance of both alloys is compared with that of other nickel or cobalt base eutectics strengthened with brittle fibers.

Tartaglia, J. M.; Stoloff, N. S.

1981-06-01

289

Fatigue of Ni-Ai-Mo aligned eutectics at elevated temperatures  

NASA Astrophysics Data System (ADS)

The elevated-temperature mechanical behavior of two aligned eutectics (Ni-8.1 wt pct Al-26.4 wt pct Mo and Ni-6.3 wt pct Al-31.2 wt pct Mo) has been investigated utilizing monotonic and cyclic testing in vacuum. Tensile yield strength and fatigue resistance increased from 25 to 725 °C, but then were reduced at 825 °C. The fatigue lives of specimens tested at 725 °C decreased sharply with decreasing frequency. A shift from surface to internal crack initiation was observed upon increasing the test temperature from 725 to 825 °C. Stage II crack propagation was observed at both temperatures, in contrast to stage I cracking at 25 °C. The test results are compared to those for other nickel and cobalt-base aligned eutectics to show that the frequency effect on fatigue life is not limited to the Ni-AI-Mo system.

Tartaglia, J. M.; Stoloff, N. S.

1981-11-01

290

Determination of the structural morphology of eutectic coatings from technological factors  

SciTech Connect

The influence of such factors as the ratio of the components in the powder mixture, the form, temperature, and length of heating, and the cooling rate on diffusion-directed eutectic layers was determined. Specimens of 45 steel with a powder mixture consisting of gray iron, ferromanganese, a fluxing agent, and an activator were placed in a previously heated furnace. The structure of the coatings was investigated by microscopy and the phase composition was determined by x-ray analysis and found to be multialloyed pearlite, metastable iron carbide, and inclusions of iron boride. The formation of coatings with hypoeutectic and eutectic structures on carbon and alloy steels was found to be possible with a change in composition and thickness of the powder mixture, the temperature-time conditions of the process and the cooling rate.

Golubets, V.M.; Pashechko, M.I.

1988-01-01

291

Electrodialysis technology for salt recovery from aluminum salt cake  

SciTech Connect

Electrodialysis technology for recovering salt from aluminum salt cake is being developed at Argonne National Laboratory. Salt cake, a slag-like aluminum-industry waste stream, contains aluminum metal, salt (NaCl and KCl), and nonmetallics (primarily aluminum oxide). Salt cake can be recycled by digesting with water and filtering to recover the metal and oxide values. A major obstacle to widespread salt cake recycling is the cost of recovering salt from the process brine. Electrodialysis technology developed at Argonne appears to be a cost-effective approach to handling the salt brines, compared to evaporation or disposal. In Argonne's technology, the salt brine is concentrated until salt crystals are precipitated in the electrodialysis stack; the crystals are recovered downstream. The technology is being evaluated on the pilot scale using Eurodia's EUR 40-76-5 stack.

Hryn, J. N.; Krumdick, G.; Graziano, D.; Sreenivasarao, K.

2000-02-02

292

Salt Lake City, Utah  

NASA Technical Reports Server (NTRS)

Salt Lake City, Utah, will host the 2002 Winter Olympic Games. The city is located on the southeastern shore of the Great Salt Lake and sits to the west of the Wasatch Mountains, which rise more than 3,500 meters (10,000 feet) above sea level. The city was first settled in 1847 by pioneers seeking relief from religious persecution. Today Salt Lake City, the capital of Utah, is home to more than 170,000 residents. This true-color image of Salt Lake City was acquired by the Enhanced Thematic Mapper Plus (ETM+), flying aboard Landsat 7, on May 26, 2000. The southeastern tip of the Great Salt Lake is visible in the upper left of the image. The furrowed green and brown landscape running north-south is a portion of the Wasatch Mountains, some of which are snow-capped (white pixels). The greyish pixels in the center of the image show the developed areas of the city. A number of water reservoirs can be seen east of the mountain range. Salt Lake City International Airport is visible on the northwestern edge of the city. About 20 miles south of the airport is the Bingham Canyon Copper Mine (tan pixels), the world's largest open pit excavation. See also this MODIS image of Utah. Image courtesy NASA Landsat7 Science Team and USGS Eros Data Center

2002-01-01

293

Salt and hypertension  

PubMed Central

1 Studies comparing different communities have suggested that the amount of salt in the diet may play an important role in determining blood pressure levels within a particular community. Intervention studies have also suggested that salt intake may play an important role in determining blood pressure levels in man. 2 In animals, where more clearcut experiments can be done, an increase in salt intake both in inherited forms of hypertension and experimental hypertension causes a further rise in blood pressure. Recent work has suggested that this rise in blood pressure could be related to an inherited or imposed defect in the kidney's ability to excrete sodium, which will give rise to greater compensatory mechanisms to overcome the sodium retention. These compensatory mechanisms might eventually be responsible for the development of high blood pressure. 3 In patients who have already developed high blood pressure, restricting the amount of salt in the diet does cause a fall in blood pressure in many patients. However, short-term reduction of salt intake in normotensive subjects causes little, if any, fall in blood pressure. The effectiveness of short term salt restriction in lowering blood pressure in adults therefore appears to be related to the severity of the high blood pressure and, probably more directly, to the suppression of the renin system that occurs as blood pressure rises.

MacGregor, G. A.

1986-01-01

294

The peculiarities of crystallization of low-temperature eutectic in magnesium-lead system  

Microsoft Academic Search

Density of low-temperature eutectic in magnesium-lead system (83.06 at. % Pb) has been measured by gamma-raying of the samples\\u000a with narrow beam from cesium-137 isotope over the temperature range 293–1000 K of solid and liquid states. Approximation density\\u000a dependences have been obtained and data of this work and other authors have been compared. Reference tables of temperature\\u000a dependences of the

S. V. Stankus; R. A. Khairulin

2010-01-01

295

Current-Induced Phase Partitioning in Eutectic Indium-Tin Pb-Free Solder Interconnect  

Microsoft Academic Search

Structural changes from high-density electric currents were examined in a eutectic In-Sn\\/Cu interconnect. Under electrical\\u000a loading, Sn and In migrated in opposite directions, creating a partition of the Sn- and In-rich phases between the anode and\\u000a the cathode. At the anode, a net gain of Sn atoms resulted in the formation of massive, columnar hillocks on the surface,\\u000a but a

John P. Daghfal; J. K. Shang

2007-01-01

296

Selective Au-Si eutectic bonding for Si-based MEMS applications  

SciTech Connect

A novel method of fabricating three-dimensional silicon micro electromechanical systems (MEMS) is presented, using selectivity thin film deposited Au-Si eutectic bond pads. Utilizing this process, complicated structures such as microgrippers and microchannels are fabricated. Bond strengths are higher than the silicon fracture strength and the bond areas can be localized and aligned to the processed wafer. The process and the applications are described in this paper.

Lee, A.; Lehew, S.; Yu, C. [and others

1995-05-22

297

Determination of the elastic moduli of a directionally solidified nickel-based TaC eutectic  

Microsoft Academic Search

Measurements of ultrasonic wave velocities in a polycrystalline directionally solidified nickel based eutectic alloy are used\\u000a to evaluate the three independent single crystal elastic moduli at temperatures between 298 to 925 K. The Cu and C44 moduli are obtained directly from high frequency wave propagation along the D.S. axis, corresponding to . Evaluation\\u000a of C12 requires measurements at lower frequencies

E. S. Fisher

1980-01-01

298

Partially-constrained thermomechanical fatigue of eutectic tin-bismuth\\/copper solder joints  

Microsoft Academic Search

Small bimetallic load-frames with reference assembly stiffness, k', and fully-constrained shear strain, gammafc, were used to simulate the thermo-mechanical conditions experienced by eutectic Bi-42wt.%Sn-to-Cu solder joints. Shear stress and strain were induced in the solder joint by a 45-minute, 0 to 100°C temperature cycle and were calculated from the assembly temperature, joint configuration, and measured elastic strain in the load-frame.

C. H. Raeder; R. W. Messler Jr.; L. F. Coffin Jr.

1999-01-01

299

Tensile tests on MANET II steel in circulating Pb–Bi eutectic  

Microsoft Academic Search

Off-beam tensile tests have been performed on MANET II steel in the eutectic Pb–55.5Bi (LBE) and Ar during commissioning of the LiSoR loop, an experimental liquid metal loop, which was developed to investigate the influence of Pb–Bi on possible structural materials under static load and irradiation. Test temperatures were 180–300 °C. MANET II (11% CrMoVNb steel) exhibits good swelling and

H. Glasbrenner; F. Gröschel; T. Kirchner

2003-01-01

300

The mechanical properties of the superplastic AI 33 Pct Cu eutectic alloy  

Microsoft Academic Search

Experiments were conducted to determine the mechanical properties of the superplastic Al-33 Pct Cu eutectic alloy at temperatures from 673 to 723 K. Specimens were tested in a well-annealed condition and there was no evidence for grain growth even at the lowest experimental strain rate of 6.7 × 1(10-7 s-1. It is shown that the stress-strain curves rapidly attain a

Atul H. Chokshi; Terence G. Langdon

1988-01-01

301

The mechanical properties of the superplastic AI 33 Pct Cu eutectic alloy  

Microsoft Academic Search

Experiments were conducted to determine the mechanical properties of the superplastic Al-33 Pct Cu eutectic alloy at temperatures\\u000a from 673 to 723 K. Specimens were tested in a well-annealed condition and there was no evidence for grain growth even at the\\u000a lowest experimental strain rate of 6.7 × 1(10-7 s-1. It is shown that the stress-strain curves rapidly attain a

Atul H. Chokshi; Terence G. Langdon

1988-01-01

302

Thermodynamic Analysis and Experimental Study of Composite Structure Formation in Eutectic Alloys ? Al + Mg2Si  

Microsoft Academic Search

The Al ? Mg ? Si phase diagram was studied and the formation conditions for a regular two-phase eutectic structure (a-Al + Mg2Si) were established. Concentration limits were found for optimum alloy compositions with maximum melting point (~595°C) and a narrow (or zero) melting (crystallization) range (less than 5°C). The structures of these alloys are formed by Mg2Si monocrystal fibers

Tatyana N. Legkaya; N. P. Korzhova; O. V. Sulzhenko

2000-01-01

303

Measurement of solid liquid interfacial energy in the In Bi eutectic alloy at low melting temperature  

Microsoft Academic Search

The Gibbs-Thomson coefficient and solid-liquid interfacial energy of the solid In solution in equilibrium with In Bi eutectic liquid have been determined to be (1.46 ± 0.07) × 10-7 K m and (40.4 ± 4.0) × 10-3 J m-2 by observing the equilibrated grain boundary groove shapes. The grain boundary energy of the solid In solution phase has been calculated

N. Marasli; S. Akbulut; Y. Ocak; K. Keslioglu; U. Böyük; H. Kaya; E. Çadirli

2007-01-01

304

Structure of the ternary gallium-indium-tin eutectic system in the liquid state  

Microsoft Academic Search

An x-ray study has been made of the short-range structure of the ternary gallium-indium-tin eutectic system in the liquid state at T = 288, 308, and 368 °K. Intensity curves were compared with the diffraction reflections of the components. The radial distribution of atoms was calculated. This distribution is interpreted for model ``quasieutectic'' and statistical distributions of the scattering atoms.

Ya. I. Dutchak; N. M. Klym; V. S. Frenchko

1969-01-01

305

Structure of the ternary gallium-indium-tin eutectic system in the liquid state  

Microsoft Academic Search

An x-ray study has been made of the short-range structure of the ternary gallium-indium-tin eutectic system in the liquid state at T = 288, 308, and 368 °K. Intensity curves were compared with the diffraction reflections of the components. The radial distribution of atoms was calculated. This distribution is interpreted for model “quasieutectic” and statistical distributions of the scattering atoms.

Ya. I. Dutchak; N. M. Klym; V. S. Frenchko

1969-01-01

306

Corrosion behaviors of US steels in flowing lead–bismuth eutectic (LBE)  

Microsoft Academic Search

Corrosion tests of several US martensitic and austenitic steels were performed in a forced circulation lead–bismuth eutectic non-isothermal loop at the Institute of Physics and Power Engineering (IPPE), Russia. Tube and rod specimens of austenitic steels 316\\/316L, D-9, and martensitic steels HT-9, T-410 were inserted in the loop. Experiments were carried out simultaneously at 460°C and 550°C for 1000, 2000

Jinsuo Zhang; Ning Li; Yitung Chen; A. E. Rusanov

2005-01-01

307

The effect of humidity on friction and wear of an aluminium–silicon eutectic alloy  

Microsoft Academic Search

The sliding wear of an aluminium–silicon eutectic alloy against cast iron counterface in 3–100% relative humidity range has\\u000a been investigated. The results show that the moisture content has a significant effect on the friction and wear of the Al–Si\\u000a alloy. The wear rate decreases by two orders of magnitude as the relative humidity increases from 3% to 100%. At low

BING K. YEN

1997-01-01

308

Effect of surface etching on the lubricated sliding wear of an eutectic aluminium–silicon alloy  

Microsoft Academic Search

The paper presents a study of the formation of wear grooves on near-eutectic aluminium–silicon alloy flats, by sliding a steel ball. The formation of the grooves are tracked on etched and unetched flats as functions of normal load and sliding distance. The groove is initially formed by plastic flow, and then expanded by micro-abrasion as the ball continues to slide

S. Das; T. Perry; S. K. Biswas

2006-01-01

309

Effect of element additions on wear property of eutectic aluminium-silicon alloys  

Microsoft Academic Search

The effects of cerium, zinc and zirconium additions and subsequent heat treatment on wear of the eutectic aluminium-silicon alloys have been investigated in dry sliding against a steel counterface by using a pin-on-disc machine. Wear surfaces and debris were examined by scanning electron microscopy. Wear characteristics of both binary Al-Si alloys and a commercial LM 13 alloy, were also studied

Mohd Harun; I. A. Talib; A. R. Daud

1996-01-01

310

Nucleation mechanism of the eutectic phases in aluminum-silicon hypoeutectic alloys  

SciTech Connect

A theory is presented to explain the mechanism of formation of the eutectic phases in Al-Si hypoeutectic alloys. Results include optical, scanning and transmission electron microscopy, as well as selected area electron diffraction analysis and elemental X-ray mapping performed on Al-Si hypoeutectic alloy samples. The alloy samples had precisely controlled chemistry and were solidified at various cooling rates. The data presented support the proposed theory with microstructural and crystallographic evidence.

Shankar, Sumanth; Riddle, Yancy W.; Makhlouf, Makhlouf M

2004-09-06

311

Effect of antimony on the growth kinetics of aluminium-silicon eutectic alloys  

Microsoft Academic Search

On treating aluminium-silicon alloy with 0.2 wt% Sb, it was revealed that antimony refines the eutectic structure by reducing the interflake spacing rather than acting as a modifier. The growth mechanism is similar to the unmodified Al=Si flake structure, giving the relationships of the type ?T=K1V0.51 and ?=K2V-0.4, where K1 and K2 are constants at high solidification rate, the transition

S. Khan; R. Elliott

1994-01-01

312

Microstructure and properties of a bismuth-indium-tin eutectic alloy  

Microsoft Academic Search

A ternary eutectic alloy with a composition of 57.2%Bi, 24.8%In and 18%Sn was continuously cast into wire of 2 mm diameter with casting speeds of 14 and 79 mm min-1 using the Ohno continuous casting process. The microstructures and mechanical properties of the wires were compared with those of statically cast specimens. Extensive segregation of massive bismuth crystals, bismuth complex

S. Sengupta; H. Soda; A. McLean

2002-01-01

313

Nucleation mechanism of the eutectic phases in aluminum–silicon hypoeutectic alloys  

Microsoft Academic Search

A theory is presented to explain the mechanism of formation of the eutectic phases in Al–Si hypoeutectic alloys. Results include optical, scanning and transmission electron microscopy, as well as selected area electron diffraction analysis and elemental X-ray mapping performed on Al–Si hypoeutectic alloy samples. The alloy samples had precisely controlled chemistry and were solidified at various cooling rates. The data

Sumanth Shankar; Yancy W. Riddle; Makhlouf M Makhlouf

2004-01-01

314

Electronic absorption spectra of U3+ and U4+ in molten LiCl-RbCl eutectic  

NASA Astrophysics Data System (ADS)

In the non-aqueous reprocessing process of spent nuclear fuels by the pyro-electrochemical method, a spent fuel is dissolved into molten LiCl-KCl and NaCl-CsCl eutectics and dissolved uranium and plutonium are collected as either metal or oxide. However, the binary alkali chloride mixture with the lowest melting point is the LiCl-RbCl eutectic. In this study, electronic absorption spectra of U3+ and U4+ in molten LiCl-RbCl eutectic at various temperatures between 673 and 973 K were measured by the UV/Vis/NIR spectrophotometry. We confirmed that these spectra were similar to those in molten LiCl-KCl and NaCl-CsCl eutectics. The sensitive absorption bands of U4+ in LiCl-RbCl eutectic were found at 22000, 16500, 14900, 8600, and 4950 cm-1. The large absorption bands of U4+ over 25000 cm-1 increased with increasing melt temperature, while absorption peaks at 15500-4000 cm-1 decreased. The large absorption bands of U3+ in LiCl-RbCl eutectic were observed over 14000 cm-1. The sensitive absorption bands of U3+ at Vis/NIR region were found at 13300, 11500-11200, 9800-9400, and 8250 cm-1, and these peaks decreased with increasing temperature.

Nagai, T.; Uehara, A.; Fujii, T.; Sato, N.; Yamana, H.

2010-03-01

315

Solubilization of Genistein in Poly(Ethylene Glycol) via Eutectic Crystal Melting  

NASA Astrophysics Data System (ADS)

Genistein (5,7,4'-trihydroxyisoflavone) is a phytoestrogen found in soybean. It possesses various biological/pharmacological functions, e.g., tyrosine kinase inhibitory, anticarcinogenic, antioxidant, anti-inflammatory, and anti-microbial activities. However, genistein has poor water solubility and skin permeability, which have seemingly prohibited the progress to preclinical evaluation. Eutectic melting approach has been performed as a means of solubilizing genistein in poly(ethylene glycol) (PEG). Eutectic phase diagrams of blends containing genistein and PEG having three different molecular weights, i.e., 44k, 7k, and 500 g/mol, were established by means of DSC and compared with the theoretical liquidus and solidus lines, calculated self-consistently by taking into consideration all interactions including amorphous-amorphous, crystal-amorphous, amorphous-crystal, and crystal-crystal interactions. The eutectic temperatures were found to decrease with decreasing molecular weight of PEG. Guided by the phase diagram, it was found that genistein can be dissolved in PEG500 up to ˜7 wt% at room temperature. More importantly, the solubility of genistein in PEG can be improved to meet the end-use criteria of the PEG/genistein mixtures.

Buddhiranon, Sasiwimon; Kyu, Thein

2012-02-01

316

On the Freezing and Melting Behavior of the Eutectic Pt-C  

NASA Astrophysics Data System (ADS)

The feasibility of referring to freezing as an alternative to melting for defining the eutectic transition temperature has been studied using two Pt-C cells constructed at NIM, one of a sleeve type, and the other of a hybrid type, including support. Freezing and melting experiments have been done by varying the offset of the furnace temperature T furn with respect to the nominal eutectic temperature T E used to freeze the fixed point with offsets ( T furn- T E)freeze from -5 K to -40 K, followed by melting at a fixed offset ( T furn- T E)melt = + 20 K. Plotting the liquidus temperatures T liq,freeze and T liq,melt obtained for freezing and melting against {(T_E-T_furn)^{1/2}_freeze} resulted in linear relations for both cells, allowing extrapolation toward T liq,freeze(0) and T liq, melt(0). For the cells Pt-C5# and Pt-C6# under study: T liq,melt(0)- T liq,freeze(0) = 10 mK and 20 mK, respectively, with a standard uncertainty of 30 mK for both T liq,melt(0) and T liq,freeze(0). The coherence of the results obtained for melting and freezing indicates that freezing can be used, as an alternative to melting, to define the liquidus temperature T liq(0) of the eutectic Pt-C.

Dong, W.; Bloembergen, P.; Wang, T.; Duan, Y. Y.

2011-12-01

317

Martensitic transformation and ordering in heat-resistant Ni-Co-Cr-AI ?/? eutectics  

NASA Astrophysics Data System (ADS)

The method of thin-foil transmission electron microscopy was used to examine phase transformations in the ?-phase, representing the main heat-resistant component, of ?/? eutectics of the Ni-Co-Cr-Al system (mass % : 0 15 Co, 14 20 Cr, 8.5 10.5 Al). The martensitic transformation ?(B2)to L10 took place in all the alloys, except those with 20 mass % Cr, when they were quenched in water from 1200°C. It was found for the first time that high-rank superstructures A2B (Ni2Al) and A5B3 (Ni5Al3) could be formed in a complex-alloyed ? solid solution. Phase transformations L1{0}toA_5B_3, L1_0to 14M, L1_0to B2to A_2B, and L1_0to B2to A_5B_3 were observed in the ?-component of the eutectics when isothennal annealing temperature was increased from 250 to 600°C. At a temperature of 400°C and higher those transformations were accompanied by the decomposition of the ? solid solution and the appearance of dispersed ?-Cr particles. Structural features of the aforementioned phase transformations in heat-resistant quaternary eutectics were considered.

Kositsyn, S. V.; Katayeva, N. V.; Kositsyna, I. I.; Valiullin, A. I.; Litvinov, V. S.

2003-10-01

318

In-situ observation of eutectic growth in Al-based alloys by light microscopy  

NASA Astrophysics Data System (ADS)

An experimental method for the in-situ observation of solidification in eutectic metallic alloys growing at moderate temperatures, i.e. 500-600 °C was developed. It is based on unidirectional solidification of thin samples (200 to 700 ?m thick) contained in rectangular quartz glass tubes allowing for in-situ observation of growth on the sample surface by means of light microscopy using a long-distance microscope. The method is illustrated for two-phase eutectic growth in Al-17.5Cu-1.0Ag, Al-11.8Si and Al-11.8Si-0.025Sr as well as for three phase growth in Al-13.3Cu-5.7Si, all at%. Coupled growth of lamellar Al-Al2Cu eutectic in Al-17.5Cu-1.0Ag was investigated in more detail with regard to spacing selection: experiments were performed in a temperature gradient of 38±1 K cm-1 using different, but constant withdrawal velocities ranging from 0.025 to 1.8 ?m s-1. Measured spacing was compared with literature data and discussed with reference to the Jackson-Hunt theory and the recent amendment proposed by Akamatsu, Faivre, Karma and Plapp. In-situ observations were complemented by post-mortem metallographic analysis using SEM and EBSD in transverse sections.

Witusiewicz, V. T.; Hecht, U.; Rex, S.

2013-06-01

319

Resolving issues of content uniformity and low permeability using eutectic blend of camphor and menthol.  

PubMed

The aim of present study were to arrest the problem of content uniformity without the use of harmful organic solvent and to improve ex vivo permeability of captopril, a low dose class III drug as per biological classification system. Eutectic mixture of camphor and menthol was innovatively used in the work. Captopril solution in eutectic mixture was blended with Avicel PH 102 and then the mixture was blended with mannitol in different ratios. Formulated batches were characterized for angle of repose and Carr's index. A selected batch was filled in hard gelatin capsule. Tablet dosage form was also developed. Capsules and tablets were characterized for in vitro drug release in 0.1N HCl. Additionally, the captopril tablets were analyzed for content uniformity and ex vivo drug permeation study using rat ileum in modified apparatus. The measurement of angle of repose and Carr's index revealed that the powder blend exhibited good flow property and compressibility. The captopril capsules and tablets exhibited immediate drug release in 0.1 N HCl. The captopril tablets passed content uniformity test as per IP 1996. Ex vivo permeation of captopril, formulated with eutectic mixture, was faster than control. The permeation was increased by 15% at the end of 3 h. Tablets and capsule exhibited reasonable short term stability with no considerable change in performance characteristics. PMID:20376214

Gohel, M C; Nagori, S A

2009-11-01

320

Zero-gravity growth of NaF-NaCl eutectics in the NASA Skylab program  

NASA Technical Reports Server (NTRS)

Continuous and discontinuous NaF fibers, embedded in a NaCl matrix, were produced in space and on earth. The production of continuous fibers in a eutectic mixture is attributed to the absence of convection current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and earth-grown ingots were made with a light microscope and a spectrometer. It is shown that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of NaF fibers along the ingot axis. A new concept is advanced to explain the phenomenon of transmittance versus far infrared wavelength of the directionally solidified NaCl-NaF eutectic in terms of the two-dimensional Bragg Scattering and the polarization effect of Rayleigh scattering. This concept can be applied to other eutectic systems as long as the index of refraction of the matrix over a range of wavelengths is known. Experimental data are in agreement with the theoretical prediction.

Yue, A. S.; Allen, F. G.; Yu, J. G.

1976-01-01

321

Lowering Salt in Your Diet  

MedlinePLUS

... or less for sodium, per serving. Q. Are salt substitutes safe? A. Many salt substitutes contain potassium chloride and can be used by ... heart disease. Check with your doctor before using salt substitutes. Q. What is FDA's role in regulating salt? ...

322

Brazing characteristics of a Zr-Ti-Cu-Fe eutectic alloy filler metal for Zircaloy-4  

NASA Astrophysics Data System (ADS)

A Zr-Ti-Cu-Fe quaternary eutectic alloy was employed as a new Be-free brazing filler metal for Zircaloy-4 to supersede physically vapor-deposited Be coatings used conventionally with several disadvantages. The quaternary eutectic composition of Zr58Ti16Cu10Fe16 (at.%) showing a low melting temperature range from 832 °C to 853 °C was designed by a partial substitution of Zr with Ti based on a Zr-Cu-Fe ternary eutectic system. By applying an alloy ribbon with the determined composition, a highly reliable joint was obtained with a homogeneous formation of predominantly grown ?-Zr phases owing to a complete isothermal solidification, exhibiting strength higher than that of Zircaloy-4. The homogenization of the joint was rate-controlled by the diffusion of the filler elements (Ti, Cu, and Fe) into the Zircaloy-4 base metal, and the detrimental segregation of the Zr2Fe phase in the central zone was completely eliminated by an isothermal holding at a brazing temperature of 920 °C for 10 min. The quaternary eutectic composition of Zr58Ti16Cu10Fe16 (at.%) with a low melting temperature range from 832 °C to 853 °C was determined by substituting a part of Zr with Ti based on a Zr-Cu-Fe ternary eutectic system. For the sample brazed at 880 °C, the joint formed a dendritic growth structure with a continuous segregation in the central zone, whereas the isothermally solidified joint at 920 °C consisted of only a homogeneous dendritic structure without segregation. The primary phase solidified isothermally was a hexagonal ?-Zr rather than a ?-Zr owing to a relatively low brazing temperature, and it nucleated to grow into a joint with a dendritic structure. In an interdendritic region, a fine lamellar structure with alternate ?-Zr and Zr3Fe phases was produced by a eutectoid decomposition of a (Cu-Fe)-rich ?-Zr phase, i.e., ?-Zr ? ?-Zr + Zr3F, at the cooling stage. A Zr2Fe phase was formed continuously in the segregated center zone owing to a sluggish diffusion of the filler elements (Ti, Cu, and Ni), and accordingly a disappearance of the central Zr2Fe phase was rate-controlled by the outward diffusion of the filler elements into the base metal. When the detrimental Zr2Fe phase was eliminated by a complete isothermal solidification at 920 °C, the strength of the joint was high enough to cause yielding and fracture in the base Zircaloy-4 (see Fig. 9).

Lee, Jung G.; Lim, C. H.; Kim, K. H.; Park, S. S.; Lee, M. K.; Rhee, C. K.

2013-10-01

323

Salt Made the World Go Round: MRBLOCH Salt Archive  

NSDL National Science Digital Library

Don't you just love it when everything can be summed up with one simple explanantion? Created by David Bloch, this Website proves that life as we know depends upon salt. Sections of the site look at salt in relation to a wide range of areas of study, such as Physiology, Geology, Archaeology, Paleoclimatology, Religion, and Economics. For example, the Economics section provides information on the use of salt as money, the history of the control of salt by monopolies, and the influence of the salt trade on transportation. The Religion section points out the importance of salt in religious practices, such as Jewish koshering and Egyptian embalming. Also included are links to over fifty additional salt sites, an email list, and an announcement for Salt 2000, the 8th World Salt Symposium, to be held in the Hague in May 2000.

Bloch, David.

324

The Influence of Cr on the Solidification Behavior of Polycrystalline ?(Ni)/ ?'(Ni3Al)- ?(Ni3Nb) Eutectic Ni-Base Superalloys  

NASA Astrophysics Data System (ADS)

In the current investigation, the effect of Cr on the solidification characteristics and as-cast microstructure of pseudobinary ?- ? eutectic alloys based on a near-eutectic composition (Ni-5.5Al-13.5Nb at. pct) was investigated. It was found that Cr additions promote the formation of a higher volume fraction of ?- ? eutectic microstructure in the interdendritic region. Increasing levels of Cr also triggered morphological changes in the ?- ? eutectic and the formation of ?- ?'- ? ternary eutectic during the last stage of solidification. A detailed characterization of the as-cast alloys also revealed that Cr additions suppressed the liquidus, solidus, and ?' precipitation temperature of these ?/ ?'- ? eutectic alloys. A comparison of the experimental results with thermodynamic calculations using the CompuTherm Pandat database (CompuTherm LLC, Madison, WI) showed qualitative agreement.

Xie, Mengtao; Helmink, Randolph; Tin, Sammy

2012-04-01

325

The effect of growth velocity and temperature gradient on growth characteristics of matrix eutectic in a hypereutectic aluminium-silicon alloy  

Microsoft Academic Search

The growth undercooling ?T and eutectic interlamellar spacing ?, have been measured as functions of growth velocityV and temperature gradientG for matrix Al-Si eutectic in the presence of primary silicon in Bridgman-grown hypereutectic Al-18.3 wt% Si alloy. ?T\\/V1\\/2 shows a step decrease atV>270 µm s-1 corresponding to a change in eutectic growth morphology from flake-like to fibrous, but there was

Y. Bayraktar; D. Liang; H. Jones

1995-01-01

326

Clean Salt integrated flowsheet  

SciTech Connect

The Clean Salt Process (CSP) is a novel waste management scheme that removes sodium nitrate and aluminum nitrate nonahydrate as decontaminated (low specific activity) salts from Hanford`s high-level waste (HLW). The full scale process will separate the bulk of the waste that exists as sodium salts from the small portion of the waste that is by definition radioactive and dangerous. This report presents initial conceptual CSP flowsheets and demonstrates the benefit of integrating the process into the Tank Waste Remediation Systems (TWRS) Reference Flowsheet. Total HLW and low-level (LLW) volumes are reported for two different CSP integration options and are compared to the TWRS Reference Flowsheet values. The results for a single glass option eliminating LLW disposal are also reported.

Lunsford, T.R.

1994-09-27

327

Gas releases from salt  

SciTech Connect

The occurrence of gas in salt mines and caverns has presented some serious problems to facility operators. Salt mines have long experienced sudden, usually unexpected expulsions of gas and salt from a production face, commonly known as outbursts. Outbursts can release over one million cubic feet of methane and fractured salt, and are responsible for the lives of numerous miners and explosions. Equipment, production time, and even entire mines have been lost due to outbursts. An outburst creates a cornucopian shaped hole that can reach heights of several hundred feet. The potential occurrence of outbursts must be factored into mine design and mining methods. In caverns, the occurrence of outbursts and steady infiltration of gas into stored product can effect the quality of the product, particularly over the long-term, and in some cases renders the product unusable as is or difficult to transport. Gas has also been known to collect in the roof traps of caverns resulting in safety and operational concerns. The intent of this paper is to summarize the existing knowledge on gas releases from salt. The compiled information can provide a better understanding of the phenomena and gain insight into the causative mechanisms that, once established, can help mitigate the variety of problems associated with gas releases from salt. Outbursts, as documented in mines, are discussed first. This is followed by a discussion of the relatively slow gas infiltration into stored crude oil, as observed and modeled in the caverns of the US Strategic Petroleum Reserve. A model that predicts outburst pressure kicks in caverns is also discussed.

Ehgartner, B.; Neal, J.; Hinkebein, T.

1998-06-01

328

The Nature of Salt  

NSDL National Science Digital Library

This is a hands-on lab activity about the composition of salt. Learners will explain the general relationship between an element's Periodic Table Group Number and its tendency to gain or lose electron(s), and explain the difference between molecular compounds and ionic compounds. They will then use household materials to build a model to demonstrate sodium chloride's cubic form and describe the nature of the electrostatic attraction that holds the structure of salt together. Background information, common preconceptions, a glossary and more is included. This activity is part of the Aquarius Hands-on Laboratory Activities.

329

[Salt intake in children].  

PubMed

Very early in life, sodium intake correlates with blood pressure level. This warrants limiting the consumption of sodium by children. However, evidence regarding exact sodium requirements in that age range is lacking. This article focuses on the desirable sodium intake according to age as suggested by various groups of experts, on the levels of sodium intake recorded in consumption surveys, and on the public health strategies implemented to reduce salt consumption in the pediatric population. Practical recommendations are given by the Committee on nutrition of the French Society of Pediatrics in order to limit salt intake in children. PMID:24686038

Girardet, J-P; Rieu, D; Bocquet, A; Bresson, J-L; Briend, A; Chouraqui, J-P; Darmaun, D; Dupont, C; Frelut, M-L; Hankard, R; Goulet, O; Simeoni, U; Turck, D; Vidailhet, M

2014-05-01

330

Oxygen sparging of residue salts  

SciTech Connect

Oxygen sparge is a process for treating salt residues at Los Alamos National Laboratory by sparging oxygen through molten salts. Oxygen reacts with the plutonium trichloride in these salts to form plutonium dioxide. There is further reaction of the plutonium dioxide with plutonium metal and the molten salt to form plutonium oxychloride. Both of the oxide plutonium species are insoluble in the salt and collect atthe bottom of the crucible. This results in a decrease of a factor of 2--3 in the amount of salt that must be treated, and the amount of waste generated by aqueous treatment methods.

Garcia, E.; Griego, W.J.; Owens, S.D.; Thorn, C.W.; Vigil, R.A.

1993-03-01

331

Study of Salt Neutrino Detector  

NASA Astrophysics Data System (ADS)

Rock salt is studied as a radio wave transmission medium in an ultra high energy (UHE) cosmic neutrino detector. The radio wave would be generated by Askar'yan effect (coherent Chrenkov radiation from negative excess charges in the electromagnetic shower) in the UHE neutrino interaction in the rock salt. We collected the samples of the rock salts from various rock salt mines in order to investigate whether they have a possibility as a Salt Neutrino Detector (SND) sites or not. As a tentative result, the absorption length of the rock salt samples was measured to be between 40 m and400 m at 1 GHz. .

Chiba, Masami; Kamijo, Toshio; Kawaki, Miho; Husain, Athar; Inuzuka, Masahide; Ikeda, Maho; Yasuda, Osamu

2001-07-01

332

Identification of salt—Alloy combinations for thermal energy storage applications in advanced solar dynamic power systems  

Microsoft Academic Search

.  Thermodynamic calculations based on the available data for flouride salt systems reveal that a number of congruently melting\\u000a compositions and eutectics exist which have the potential to meet the lightweight, high energy storage requirements imposed\\u000a for advanced solar dynamic systems operating between ?1000 and 1400 K. Compatibility studies to determine suitable containment\\u000a alloys to be used with NaF-22CaF2-13MgF2, NaF-32CaF2, and

J. D. Whittenberger; A. K. Misra

1987-01-01

333

Molten salt synthesis of SrTiO 3 nanocrystals using nanocrystalline TiO 2 as a precursor  

Microsoft Academic Search

A molten salt method was proposed to synthesize SrTiO3 nanocrystals in the eutectic NaCl–KCl at 700°C for 6h, by using the homemade TiO2 nanocrystals and commercial Sr(NO3)2 powder as raw materials. Besides, a control experiment with the commercial TiO2 submicron-sized crystallites as a precursor was also conducted. The structure and composition of the obtained products were characterized by powder X-ray

Tian Xi Wang; Shuang Zhi Liu; Jun Chen

2011-01-01

334

The CF Salt Controversy  

Microsoft Academic Search

There is controversy over whether abnormalities in the salt concentration or volume of airway surface liquid (ASL) initiate cystic fibrosis (CF) airway disease. In vivo studies of CF mouse nasal epithelia revealed an increase in goblet cell number that was associated with decreased ASL volume rather than abnormal [Cl?]. Aerosolization of osmolytes in vivo failed to raise ASL volume. In

R Tarran; B. R Grubb; D Parsons; M Picher; A. J Hirsh; C. W Davis; R. C Boucher

2001-01-01

335

Properties of Rochelle Salt  

Microsoft Academic Search

In a qualitative way the anomalous properties of Rochelle salt can be explained on the basis of four different theories: (a) on the dipole theory, (b) by assuming polymorphic transitions at the Curie points, (c) by postulating an anomalous piezoelectric effect, and (d) with an inter-action theory which assumes that the structure and the fundamental properties of the crystal have

Hans Mueller

1940-01-01

336

Avi's Sensational Salt Dough  

NSDL National Science Digital Library

In this activity on page 5 of the PDF, learners mimic the process for making bricks. Learners shape and bake creations from a dough that is made from flour, salt, and water. Use this activity to introduce learners to chemical changes. Safety notes: Follow Milli's safety notes (on page 2) and do this activity with an adult.

Society, American C.

2006-01-01

337

Unitized paramagnetic salt thermometer  

SciTech Connect

The details of construction and assembly of a cerous magnesium nitrate (CMN) paramagnetic thermometer are presented. The thermometer is a small unit consisting of a primary, two secondaries, the salt pill, and thermal links. The thermometer calibration changes very little on successive coolings and is reliable to 35 mK. A typical calibration curve is also presented.

Abraham, B.M.

1982-06-01

338

Salt River Project.  

National Technical Information Service (NTIS)

Humanity's resourcefulness inspired two attempts to draw life out of the desolation of Central Arizona's Salt River Valley over the past 1,500 years. Building over the remains of an irrigation culture left behind by lost Indian tribe, the Hohokam, federal...

R. Autobee

2011-01-01

339

SALT and Spelling Achievement.  

ERIC Educational Resources Information Center

A study investigated the effects of suggestopedic accelerative learning and teaching (SALT) on the spelling achievement, attitudes toward school, and memory skills of fourth-grade students. Subjects were 20 male and 28 female students from two self-contained classrooms at Kennedy Elementary School in Rexburg, Idaho. The control classroom and the…

Nelson, Joan

340

Kinetic Monte Carlo Simulations of Rod Eutectics and the Surface Roughening Transition in Binary Alloys  

NASA Technical Reports Server (NTRS)

In this paper we report on two related topics: Kinetic Monte Carlo simulations of the steady state growth of rod eutectics from the melt, and a study of the surface roughness of binary alloys. We have implemented a three dimensional kinetic Monte Carlo (kMC) simulation with diffusion by pair exchange only in the liquid phase. Entropies of fusion are first chosen to fit the surface roughness of the pure materials, and the bond energies are derived from the equilibrium phase diagram, by treating the solid and liquid as regular and ideal solutions respectively. A simple cubic lattice oriented in the {100} direction is used. Growth of the rods is initiated from columns of pure B material embedded in an A matrix, arranged in a close packed array with semi-periodic boundary conditions. The simulation cells typically have dimensions of 50 by 87 by 200 unit cells. Steady state growth is compliant with the Jackson-Hunt model. In the kMC simulations, using the spin-one Ising model, growth of each phase is faceted or nonfaceted phases depending on the entropy of fusion. There have been many studies of the surface roughening transition in single component systems, but none for binary alloy systems. The location of the surface roughening transition for the phases of a eutectic alloy determines whether the eutectic morphology will be regular or irregular. We have conducted a study of surface roughness on the spin-one Ising Model with diffusion using kMC. The surface roughness was found to scale with the melting temperature of the alloy as given by the liquidus line on the equilibrium phase diagram. The density of missing lateral bonds at the surface was used as a measure of surface roughness.

Bentz, Daniel N.; Betush, William; Jackson, Kenneth A.

2003-01-01

341

Metals removal from spent salts  

SciTech Connect

A method and apparatus for removing metal contaminants from the spent salt of a molten salt oxidation (MSO) reactor is described. Spent salt is removed from the reactor and analyzed to determine the contaminants present and the carbonate concentration. The salt is dissolved in water, and one or more reagents may be added to precipitate the metal oxide and/or the metal as either metal oxide, metal hydroxide, or as a salt. The precipitated materials are filtered, dried and packaged for disposal as waste or can be immobilized as ceramic pellets. More than about 90% of the metals and mineral residues (ashes) present are removed by filtration. After filtration, salt solutions having a carbonate concentration >20% can be spray-dried and returned to the reactor for re-use. Salt solutions containing a carbonate concentration <20% require further clean-up using an ion exchange column, which yields salt solutions that contain less than 1.0 ppm of contaminants.

Hsu, Peter C. (Pleasanton, CA); Von Holtz, Erica H. (Livermore, CA); Hipple, David L. (Livermore, CA); Summers, Leslie J. (Livermore, CA); Brummond, William A. (Livermore, CA); Adamson, Martyn G. (Danville, CA)

2002-01-01

342

Actinide removal from spent salts  

DOEpatents

A method for removing actinide contaminants (uranium and thorium) from the spent salt of a molten salt oxidation (MSO) reactor is described. Spent salt is removed from the reactor and analyzed to determine the contaminants present and the carbonate concentration. The salt is dissolved in water, and one or more reagents are added to precipitate the thorium as thorium oxide and/or the uranium as either uranium oxide or as a diuranate salt. The precipitated materials are filtered, dried and packaged for disposal as radioactive waste. About 90% of the thorium and/or uranium present is removed by filtration. After filtration, salt solutions having a carbonate concentration >20% can be dried and returned to the reactor for re-use. Salt solutions containing a carbonate concentration <20% require further clean-up using an ion exchange column, which yields salt solutions that contain less than 0.1 ppm of thorium or uranium.

Hsu, Peter C. (Pleasanton, CA) [Pleasanton, CA; von Holtz, Erica H. (Livermore, CA) [Livermore, CA; Hipple, David L. (Livermore, CA) [Livermore, CA; Summers, Leslie J. (Livermore, CA) [Livermore, CA; Adamson, Martyn G. (Danville, CA) [Danville, CA

2002-01-01

343

Electrodeposition of mixed metal oxides from the eutectic sodium-potassium nitrate melt  

SciTech Connect

Mixed yttrium-copper oxides, some containing several percent barium, have been deposited cathodically on CuO/Cu substrates from eutectic Na-K nitrate melts (300 C) containing dissolved Y[sup 3+] and Ba[sup 2+] nitrate species. Cobalt oxide (Co[sub 3]O[sub 4]) has also been deposited from this system by cathodic reduction of Co[sup 3+] nitrate ions at a Pt electrode. Available data for Na-K nitrate melts have been summarized to facilitate the design of schemes for deposition of various mixed metallic oxides.

Kendig, M.W.; Tench, D.M.; Jeanjaquet, S.; Stocker, P. (Rockwell International Science Center, Thousand Oaks, CA (United States))

1994-02-01

344

Zero-gravity growth of NaCl-LiF eutectic. Experiment MA-131  

NASA Technical Reports Server (NTRS)

Continuous and discontinuous lithium fluoride fibers embedded in a sodium chloride matrix were produced in space and on earth, respectively. The production of continuous fibers in an eutectic mixture was attributed to the absence of convection current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and earth-grown ingots were made with a light microscope and a spectrometer. It was found that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of lithium fluoride fibers along the growth direction.

Yue, A. S.; Yeh, C. W.; Yue, B. K.

1977-01-01

345

Partially-constrained thermomechanical fatigue of eutectic tin-bismuth\\/copper solder joints  

Microsoft Academic Search

Small bimetallic load-frames with reference assembly stiffness, k?, and fully-constrained shear strain, ?fc, were used to simulate the thermo-mechanical conditions experienced by eutectic Bi-42wt.%Sn-to-Cu solder joints. Shear stress\\u000a and strain were induced in the solder joint by a 45-minute, 0 to 100°C temperature cycle and were calculated from the assembly\\u000a temperature, joint configuration, and measured elastic strain in the load-frame.

C. H. Raeder

1999-01-01

346

The effect of low Au concentrations on the properties of eutectic Sn/Pb  

SciTech Connect

This study was of the effects moderately low Au concentrations ({le} 10 wt%) have on the mechanical properties and microstructure of an eutectic Sn/Pb alloy. Vibration (60--90 Hz swept sine wave for 30 hours) and thermal cycling (0--110C for 1450 cycles) reliability tests were performed on fine pitch leaded chip carriers using eutectic Sn/Pb solder on PCBs (printed circuit boards) with 0, 5, 10, 20, and 50{mu}in nominal Au thicknesses. Testing was also performed on double shear creep specimens consisting of arrays of regular pitch joints. There was a dramatic increase in the number of joints containing voids with increasing Au concentration, an effect more pronounced in the creep joints than in the reliability joints. These voids tended to coalesce and grow during rework simulation of the reliability joints. AuSn{sub 4} intermetallics present in toe of 4.8 wt% (50 {mu}in) Au vibration joints rotated from initial vertical perpendicular to surface of PCB metallization, solidification positions to roughly horizontal (parallel to plating surface) orientations during rework simulation and during aging of the parts. The AuSn{sub 4} intermetallics in the toe of the 4.8 wt% (50{mu}in) Au reflowed joints also rotated after vibration testing. No joint failures were observed in either vibration tested or thermally cycled specimens. Cracks formed in some of the vibration tested specimen joints under the heel of the gull-wing lead at Pb-rich phases. Thermally cycled specimens showed eutectic microstructure and intermetallic coarsening without crack formation. Creep tests showed loss of the superplasticity in eutectic Sn/Pb alloys with even the lowest Au concentration tested of 0.2 wt% Au. Intermetallic rotation was not a factor in crack propagation, but void presence was. Cracks tended to form in joints containing voids before forming in void-free joints. Crack propagation followed Sn/Sn grain boundaries and Sn/Pb phase boundaries from Pb-rich phase to Pb-rich phase.

Kramer, P.A.

1992-05-01

347

A Directionally Solidified Iron-chromium-aluminum-tantalum Carbide Eutectic Alloy  

NASA Technical Reports Server (NTRS)

A eutectic alloy, Fe-13.6CR-3.7Al+9TaC, was directionally solidified in a high gradient furnace, producing a microstructure of alined TaC fibers in an oxidation resistant alpha-iron matrix. Tensile and stress rupture properties, thermal cycling resistance, and microstructures were evaluated. The alloy displays at 1000 C an ultimate tensile strength of 58 MPa and a 100-hour rupture life at a stress of 21 MPa. Thermal cycling to 1100 C induces faceting in the TaC fibers.

Harf, F. H.

1977-01-01

348

Diffusion in a Liquid Indium-Tin Alloy at the Eutectic Concentration  

Microsoft Academic Search

Self diffusion coefficients for the two tracers In114 and Sn113 in the liquid alloy indium-tin at the eutectic composition have been measured as a function of temperature in the range 200°C–450°C. The customary Arrhenius equation is used to describe the experimental results. For indium as a tracer we obtained D=(42.5±5.7) 10?5 exp?2771±158RTcm2?sec, and for tin D=(11.7±1.7) 10?5 exp?1380±156RTcm2?sec. It is

A. Paoletti; M. Vicentini

1961-01-01

349

Melting points of gallium and of binary eutectics with gallium realized in small cells  

Microsoft Academic Search

Melting\\/freezing curves are studied for the single-component Ga and bimetallic eutectic alloys Ga-In, Ga-Sn, Ga-Zn and Ga-Al in small-size cells. These phase-transition studies were conducted at VNIIOFI and SDL in order to design small-size fixed-point devices for metrological monitoring of temperature sensors on autonomous platforms. Our prime objective is to develop technology to improve the long-term performance of in-flight blackbody

A. Burdakin; B. Khlevnoy; M. Samoylov; V. Sapritsky; S. Ogarev; A. Panfilov; G. Bingham; V. Privalsky; J. Tansock; T. Humpherys

2008-01-01

350

Atomic-Scale Surface Demixing in a Eutectic Liquid BiSn Alloy  

SciTech Connect

Resonant x-ray reflectivity of the surface of the liquid phase of the Bi{sub 43}Sn{sub 57} eutectic alloy reveals atomic-scale demixing extending over three near-surface atomic layers. Because of the absence of an underlying atomic lattice which typically defines adsorption in crystalline alloys, studies of adsorption in liquid alloys provide unique insight on interatomic interactions at the surface. The observed composition modulation could be accounted for quantitatively by the Defay-Prigogine and Strohl-King multilayer extensions of the single-layer Gibbs model, revealing a near-surface domination of the attractive Bi-Sn interaction over the entropy.

Shpyrko, Oleg G.; Grigoriev, Alexei Yu.; Streitel, Reinhard; Pontoni, Diego; Pershan, Peter S. [Department of Physics and DEAS, Harvard University, Cambridge, Massachusetts 02138 (United States); Deutsch, Moshe [Department of Physics, Bar-Ilan University, Ramat-Gan 52900 (Israel); Ocko, Ben [Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 (United States); Meron, Mati; Lin Binhua [CARS, University of Chicago, Chicago, Illinois 60637 (United States)

2005-09-02

351

Atomic-scale surface demixing in a eutectic liquid BiSn alloy.  

PubMed

Resonant x-ray reflectivity of the surface of the liquid phase of the Bi(43)Sn(57) eutectic alloy reveals atomic-scale demixing extending over three near-surface atomic layers. Because of the absence of an underlying atomic lattice which typically defines adsorption in crystalline alloys, studies of adsorption in liquid alloys provide unique insight on interatomic interactions at the surface. The observed composition modulation could be accounted for quantitatively by the Defay-Prigogine and Strohl-King multilayer extensions of the single-layer Gibbs model, revealing a near-surface domination of the attractive Bi-Sn interaction over the entropy. PMID:16196945

Shpyrko, Oleg G; Grigoriev, Alexei Yu; Streitel, Reinhard; Pontoni, Diego; Pershan, Peter S; Deutsch, Moshe; Ocko, Ben; Meron, Mati; Lin, Binhua

2005-09-01

352

Atomic-Scale Surface Demixing in a Eutectic Liquid BiSn Alloy  

NASA Astrophysics Data System (ADS)

Resonant x-ray reflectivity of the surface of the liquid phase of the Bi43Sn57 eutectic alloy reveals atomic-scale demixing extending over three near-surface atomic layers. Because of the absence of an underlying atomic lattice which typically defines adsorption in crystalline alloys, studies of adsorption in liquid alloys provide unique insight on interatomic interactions at the surface. The observed composition modulation could be accounted for quantitatively by the Defay-Prigogine and Strohl-King multilayer extensions of the single-layer Gibbs model, revealing a near-surface domination of the attractive Bi-Sn interaction over the entropy.

Shpyrko, Oleg G.; Grigoriev, Alexei Yu.; Streitel, Reinhard; Pontoni, Diego; Pershan, Peter S.; Deutsch, Moshe; Ocko, Ben; Meron, Mati; Lin, Binhua

2005-09-01

353

Kinetics of interfacial reaction between eutectic Sn-Pb solder and Cu\\/Ni\\/Pd metallizations  

Microsoft Academic Search

The interfacial microstructure and the kinetics of interfacial reaction between the eutectic Sn-Pb solder and electroplated\\u000a Ni\\/Pd on Cu substrate (Cu\\/Ni\\/NiPd\\/Ni\\/Pd) were studied both in the liquid- and solid-state of the solder. The liquidstate reaction\\u000a was carried out at 200°C, 225°C, and 250°C for 30 s, 60 s, 150 s, and 300 s at each temperature. The solid-state aging was

G. Ghosh

1999-01-01

354

Interflake spacings and undercoolings in Al–Si irregular eutectic alloy  

Microsoft Academic Search

Aluminium–silicon irregular eutectic alloy was melted in a graphite crucible in vacuum. This alloy was directionally solidified at a constant growth rate, V (8.3?m\\/s) and at different temperature gradients, G (2.0–7.8K\\/mm) and also with a constant G (7.8K\\/mm) and different V (8.3–498.7?m\\/s) in the Bridgman type directional solidification furnace. The interflake spacings, ?i, were measured from both transverse and longitudinal

M. Gündüz; H. Kaya; E. Çad?rl?; A. Özmen

2004-01-01

355

Internal zone growth method for producing metal oxide metal eutectic composites  

DOEpatents

An improved method for preparing a cermet comprises preparing a compact having about 85 to 95 percent theoretical density from a mixture of metal and metal oxide powders from a system containing a eutectic composition, and inductively heating the compact in a radiofrequency field to cause the formation of an internal molten zone. The metal oxide particles in the powder mixture are effectively sized relative to the metal particles to permit direct inductive heating of the compact by radiofrequency from room temperature. Surface melting is prevented by external cooling or by effectively sizing the particles in the powder mixture.

Clark, Grady W. (Oak Ridge, TN) [Oak Ridge, TN; Holder, John D. (Knoxville, TN) [Knoxville, TN; Pasto, Arvid E. (Oak Ridge, TN) [Oak Ridge, TN

1980-01-01

356

Zero-gravity growth of a sodium chloride-lithium fluoride eutectic mixture  

NASA Technical Reports Server (NTRS)

Continuous and discontinuous lithium fluoride fibers embedded in a sodium chloride matrix were produced in space and on Earth, respectively. The production of continuous fibers in a eutectic mixture was attributed to the absence of convective current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and Earth-grown ingots were made with a light microscope and a spectrometer. It was found that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of lithium fluoride fibers along the growth direction.

Yue, A. S.; Yeh, C. W.; Yue, B. K.

1982-01-01

357

Deposition studies of lithium and bismuth at tungsten microelectrodes in LiCl:KCl eutectic  

SciTech Connect

The authors discuss tungsten microelectrodes (diam = 25 {mu}m) used to study the deposition and stripping behavior of Li/Li+ and Bi/Bi/sup 3+/ in the LiCl:KCl eutectic at 400{sup 0}C. The Li deposition current can be simulated assuming the growth of a single hemisphere of liquid metal on the microelectrode. High stripping current densities were observed and quantitated using standard electrochemical equipment. An inverted microscope assembly was employed for in situ observation of the Li/Li+ deposition and stripping processes at the microelectrode. A precipitate appears to form in the melt surrounding the electrode during Li deposition.

Carlin, R.T.; Osteryoung, R.A. (State Univ. of New York, Buffalo, NY (USA). Dept. of Chemistry)

1989-05-01

358

Resistance of a gamma/gamma prime - delta directionally solidified eutectic alloy to recrystallization  

NASA Technical Reports Server (NTRS)

The lamellar directionally solidified nickel-base eutectic alloy gamma/gamma prime-delta has potential as an advanced turbine blade material. The microstructural stability of this alloy was investigated. Specimens were plastically deformed by uniform compression or Brinell indentation, then annealed between 705 and 1120 C. Microstructural changes observed after annealing included gamma prime coarsening, pinch-off and spheroidization of delta lamellae, and the appearance of an unidentified blocky phase in surface layers. All but the first of these was localized in severely deformed regions, suggesting that microstructural instability is not a serious problem in the use of this alloy.

Tewari, S. N.; Scheuermann, C. M.; Andrews, C. W.

1975-01-01

359

Activation energies of intermetallic growth of SnAg eutectic solder on copper substrates  

Microsoft Academic Search

Intermetallic phases formed along a Sn-Ag eutectic solder\\/Cu interface during solid-state aging have been characterized and\\u000a the activation energies of Cu3Sn and Cu6Sn5 growth have been calculated. Diffusion couples consisting of Cu\\/ 96.5Sn-3.5Ag\\/Cu were aged at 110 to 208?C for 0 to 32 days.\\u000a After aging, the Cu\\/ solder interfaces were examined using scanning electron microscopy and energy dispersive x-ray

D. R. Flanders; E. G. Jacobs; R. F. Pinizzotto

1997-01-01

360

Conditioning of Waste LiCl Salt from Pyrochemical Process Using Zeolite A  

SciTech Connect

The electrolytic (LiCl-Li{sub 2}O) reduction process (Advanced spent fuel Conditioning Process; ACP) and the electrorefining process, which are being developed by the Korea Atomic Energy Research Institute (KAERI), are to generate two types of molten salt wastes such as a LiCl salt and a LiCl-KCl eutectic salt, respectively. These waste salts must meet certain criteria for a disposal. A conditioning process composed of an immobilization and then a thermal treatment, for LiCl salt waste from the ACP has been developed using zeolite A. The immobilization of molten LiCl salt waste was conducted in a blender by mixing it with zeolite A at 923 K, producing a salt-loaded zeolite (SLZ). During the immobilization, the zeolite A was transformed to zeolite Li-A [Li{sub 2}Al{sub 2}Si{sub 2}O{sub 80}], with some minor phases such as a Li-type sodalite [Li{sub 8}Cl{sub 2}-Sod; Li{sub 8}(AlSiO{sub 4}){sub 6}Cl{sub 2}] and Nepheline for some zeolite-rich condition. In order to obtain a final ceramic waste form with Na-type sodalite [Na{sub 8}Cl{sub 2}-Sod; Na{sub 8}(AlSiO{sub 4}){sub 6}Cl{sub 2}], the very highly leach-resistant crystal phase, the SLZ with r (=LiCl/zeolite) < 0.3 should be treated in a high temperature furnace above 1173 K, which was independent from an addition of glass frit during a mixing. (authors)

Kim, J.G.; Lee, J.H.; Kim, E.H.; Ahn, D.H.; Kim, J.H. [Korea Atomic Energy Research Institute P.O. Box 105, Yuseong, Daejeon, 305-600 (Korea, Republic of)

2006-07-01

361

Internal kinematics of salt diapirs  

Microsoft Academic Search

The internal structure of intrusive and extrusive salt bodies elucidates their external shape and the mechanism and history of diapiric emplacement-information relevant to petroleum exploration. Trace amounts of brine can act like heat to weaken salt and promote geologic creep by solution-transfer mechanisms. They compare natural strain markers in salt with the artificial markers used by fluid dynamicists: stream lines

C. J. Talbot; M. P. A. Jackson

1987-01-01

362

REVIEW ARTICLE: Metal (carbide) carbon eutectics for thermometry and radiometry: a review of the first seven years  

NASA Astrophysics Data System (ADS)

Since 1999, when the first high temperature fixed-points based on the metal-carbon eutectic phase transitions were realized, more than 60 papers have been published on this topic. Eutectic based fixed-points are already being considered as secondary reference points for the International Temperature Scale and have been introduced into industrial laboratories. This rapid progress has been possible through the combined effort of scientists around the world, from national metrology institutes, universities and industry. It has been proposed that these fixed-points should be officially adopted as a way to improve the realization and dissemination of temperature scales above the silver point. In radiometry, the availability of stable high temperature fixed-points will give greater flexibility and at some wavelengths the potential for greater accuracy for spectral radiance and irradiance scale realization. This paper summarizes the major progress in eutectic research so far.

Woolliams, Emma R.; Machin, Graham; Lowe, David H.; Winkler, Rainer

2006-12-01

363

Shock-induced melting of a KCl:LiCl eutectic powder as determined from electrochemical response measurements  

SciTech Connect

Shock-induced melting of powder compacts of a eutectic of KCl and LiCl has been investigated in an electrochemical cell in which the eutectic serves as the electrolyte with an anode of a lithium-silicon alloy and a cathode with a mixture of FeS2, the eutectic and silicon dioxide. The cell remains inactive into low impedance electrical loads until the powder is melted either under shock pressure or upon release of pressure. Melt behavior is clearly indicated in time-resolved electrochemical voltage measurements and the degree of melt is sensitive to the starting powder density which controls the increase in temperature. The indicated electrolytic conductivity suggests that melting is not complete in either the shock or release state. Such electrochemical response measurements provide capability for direct studies of melting behavior, for determination of Gibbs potentials of reactions and their kinetics while under shock compression.

Graham, R.A.; Morosin, B.; Bush, D.M.

1987-01-01

364

Improving crop salt tolerance.  

PubMed

Salinity is an ever-present threat to crop yields, especially in countries where irrigation is an essential aid to agriculture. Although the tolerance of saline conditions by plants is variable, crop species are generally intolerant of one-third of the concentration of salts found in seawater. Attempts to improve the salt tolerance of crops through conventional breeding programmes have met with very limited success, due to the complexity of the trait: salt tolerance is complex genetically and physiologically. Tolerance often shows the characteristics of a multigenic trait, with quantitative trait loci (QTLs) associated with tolerance identified in barley, citrus, rice, and tomato and with ion transport under saline conditions in barley, citrus and rice. Physiologically salt tolerance is also complex, with halophytes and less tolerant plants showing a wide range of adaptations. Attempts to enhance tolerance have involved conventional breeding programmes, the use of in vitro selection, pooling physiological traits, interspecific hybridization, using halophytes as alternative crops, the use of marker-aided selection, and the use of transgenic plants. It is surprising that, in spite of the complexity of salt tolerance, there are commonly claims in the literature that the transfer of a single or a few genes can increase the tolerance of plants to saline conditions. Evaluation of such claims reveals that, of the 68 papers produced between 1993 and early 2003, only 19 report quantitative estimates of plant growth. Of these, four papers contain quantitative data on the response of transformants and wild-type of six species without and with salinity applied in an appropriate manner. About half of all the papers report data on experiments conducted under conditions where there is little or no transpiration: such experiments may provide insights into components of tolerance, but are not grounds for claims of enhanced tolerance at the whole plant level. Whether enhanced tolerance, where properly established, is due to the chance alteration of a factor that is limiting in a complex chain or an effect on signalling remains to be elucidated. After ten years of research using transgenic plants to alter salt tolerance, the value of this approach has yet to be established in the field. PMID:14718494

Flowers, T J

2004-02-01

365

Advanced Central Receiver Molten Salts Materials Review.  

National Technical Information Service (NTIS)

A set of view graphs are presented which document the review. Topics covered include: advanced central receiver molten salt program overview; molten salt chemistry; molten salt test program; molten salt processing and industrial experience; materials test...

1978-01-01

366

Salt stress or salt shock: which genes are we studying?  

PubMed

Depending on the method of NaCl application, whether gradual or in a single step, plants may experience either salt stress or salt shock, respectively. The first phase of salt stress is osmotic stress. However, in the event of salt shock, plants suffer osmotic shock, leading to cell plasmolysis and leakage of osmolytes, phenomena that do not occur with osmotic stress. Patterns of gene expression are different in response to salt stress and salt shock. Salt stress initiates relatively smooth changes in gene expression in response to osmotic stress and a more pronounced change in expression of significant numbers of genes related to the ionic phase of salt stress. There is a considerable time delay between changes in expression of genes related to the osmotic and ionic phases of salt stress. In contrast, osmotic shock results in strong, rapid changes in the expression of genes with osmotic function, and fewer changes in ionic-responsive genes that occur earlier. There are very few studies in which the effects of salt stress and salt shock are described in parallel experiments. However, the patterns of changes in gene expression observed in these studies are consistently as described above, despite the use of diverse plant species. It is concluded that gene expression profiles are very different depending the method of salt application. Imposition of salt stress by gradual exposure to NaCl rather than salt shock with a single application of a high concentration of NaCl is recommended for genetic and molecular studies, because this more closely reflects natural incidences of salinity. PMID:23186621

Shavrukov, Yuri

2013-01-01

367

Thermal performance of a eutectic mixture of lauric and stearic acids as PCM encapsulated in the annulus of two concentric pipes  

Microsoft Academic Search

Thermal performance characteristics of a eutectic mixture of lauric and stearic acids as phase change material (PCM) during the melting and solidification processes were determined experimentally in a vertical two concentric pipe-energy storage system. This study deals with three important subjects: The first one is to determine the eutectic composition ratio of the lauric acid (LA) and stearic acid (SA)

Ahmet Sari; Kamil Kaygusuz

2002-01-01

368

Directional solidification and interface structure of BaTiO3-CoFe2O4 eutectic  

Microsoft Academic Search

The directional solidification and the interface structure of BaTiO3-CoFe2O4 eutectic grown by the floating zone melting method were investigated. The microstructure of the eutectic were found to consist grains of lamellar or fibrous morphology. Two types of crystal structures of BaTiO3 were observed for different growth conditions. The orientation relationships between BaTiO3 and CoFe2O4 (the spinel-type crystal structure) are a)

J. Echigoya; S. Hayashi; Y. Obi

2000-01-01

369

Tribological Properties of a Nano-Eutectic Fe 1.87 C 0.13 Alloy Under Water Environment  

Microsoft Academic Search

Tribological properties of a nano-eutectic Fe1.87C0.13 alloy were investigated under distilled-water lubrication against AISI52100 steel ball for various applied loads and sliding\\u000a speeds. For comparison, the tribological behavior of annealed coarse-grained Fe1.87C0.13 alloy was also examined under the same testing conditions. Worn surfaces of both alloys were analyzed by using a scanning\\u000a electron microscope (SEM). The wear rate of nano-eutectic

Lin Wang; Jun Yang; Jiqiang Ma; Qinling Bi; Licai Fu; Junying Hao; Weimin Liu

2010-01-01

370

Competitive growth of stable and metastable Fe- C- X eutectics: Part II. mechanisms  

NASA Astrophysics Data System (ADS)

The competition between stable and metastable solidification in Fe-C-X alloys has been studied theo-retically, with particular regard to phase stability, nucleation, and growth processes. The effects of small additions of Si, P, Cr, Mn, Ti, Al, and S upon the transition velocities from grey to white and from white to grey in directional solidification are related to their influence on the eutectic tempera-tures, and nucleation and growth undercoolings. It is shown that the consequences of simultaneously adding Si and Cr upon the transition velocities can be deduced from the results of adding of Si and Cr separately only when the detailed effects of these elements upon phase stability, nucleation, and growth are known. The well-known carburizing effect of a high thermal gradient (superheat) has been shown to influence only the nucleation process. A three-phase austenite-graphite-cementite mi-crostructure resulting from the cooperative growth of a double stable/metastable eutectic has been observed for the first time.

Magnin, P.; Kurz, W.

1988-08-01

371

THE THERMAL EXPANSION OF THE DIRECTIONALLY SOLIDIFIED Al-CuAl{sub 2} EUTECTIC  

SciTech Connect

Alloys of Al- CuAl{sub 2} eutectic composition were prepared from 99.999% pure materials and directionally solidified in a temperature gradient of about 45°C/cm at different growth rates R. The {lambda}{sup 2}R = constant relation was verified and lamellar spacings of 7.5, 3.5, 2.6, 1.8 and 1.4 ~m were obtained. Dilatometer specimens were machined with axes aligned in the principal lamellae coordinate directions. Thermal expansion was measured by standard dilatometry (Cu standard) using a set point program cycling between room temperature and 500°C . Thermal expansion of the directionally solidified Al-CuAl{sub 2} eutectic is greatest in the growth direction (in the plane of the lamellae), least in the transverse direction (orthogonal to the growth direction in the plane of the lamellae) and intermediate in the vertical direction (normal to the lamellae) . The most significant finding of the study is that the thermal expansion increases with decreasing lamellar spacing between limits defined approximately by the thermal expansion of the CuAl{sub 2} phase alone and the predicted thermal expansion of an isotropic elastic model of the composite.

Baker, Dennis F.; Bragg, Robert H.

1980-03-01

372

Eutectic mixed monolayers in equilibrium with phospholipid-bilayers and triolein-liquid phase.  

PubMed

Triolein (TO) and phospholipids (egg yolk phosphatidylcholine, egg yolk phosphatidylethanolamine, and bovine brain phosphatidylserine) had low mutual solubilities and separated into the TO-liquid phase and phospholipid-bilayers. Spreading pressures of the TO-phospholipid mixture (i.e., surface pressures of the mixed monolayer in equilibrium with the phase-separating lipid mixture) at the air/saline interface were independent of the lipid composition. On the other hand, collapse pressures of the mixed monolayer of TO and phospholipid (i.e., surface pressures of the mixed monolayer in equilibrium with the TO-liquid phase) at the interface changed with the monolayer composition and were lower than the spreading pressure. The experimental data indicated the spreading and collapse pressures as offering a phase diagram for the presence of equilibrium between the mixed monolayer, the phospholipid-bilayers and the TO-liquid phase. The diagram showed that TO and the phospholipids were miscible in the mixed monolayer, forming an eutectic mixed monolayer. When the mixed monolayer initially had the eutectic composition, no collapse of the monolayer was detected until the surface pressure reached the value of the spreading pressure. No specific complex between TO and the phospholipid is required to explain the stability and collapse of the mixed monolayers. The bulk immiscibility of the lipids elucidated by the spreading pressure-measurements, immediately leads to the phase behaviors observed. PMID:8369406

Handa, T; Saito, H; Miyajima, K

1993-06-01

373

Effect of applied magnetic fields during directional solidification of eutectic Bi-Mn  

NASA Astrophysics Data System (ADS)

Samples of eutectic Bi/MnBi were directionally solidified in the presence of a transverse magnetic field up to 3 kG to determine if gravity-induced convection effects could be reduced or eliminated. Furnace velocity, V, was varied over the range 0.2 cm/h ? V ? 50 cm per hour (1 cm per hour =2.8 µm per second) while thermal gradients at the liquid-solid interface were 100 °C/cm and 150 °C/cm. The microstructure of Bi/MnBi is characterized by a regular, aligned-rod eutectic morphology which is sensitive to growth conditions. This, combined with ferromagnetism of one of the components, MnBi, can be used to determine whether convection effects are significant enough to be affected by the presence of a static, homogeneous, magnetic field. Morphological, thermal, and magnetic analyses were carried out on samples grown with and without an applied magnetic field. Results indicated reduced MnBi mean rod diameters and interred spacings for samples grown at velocities > 3 cm per hour in a transverse magnetic field. Additionally, there was significant undercooling occurring for the applied field case as evidenced by in situ thermocouple measurements. Enhanced magnetic coercivities were also observed for samples grown above V = 3 cm per hour in a transverse magnetic field compared with no field conditions. The magnetic field growth was found to be similar to previous low-gravity results.

Decarlo, J. L.; Pirich, Ron G.

1984-12-01

374

Density functional theory study of the interfacial properties of Ni/Ni3Si eutectic alloy  

NASA Astrophysics Data System (ADS)

In order to clarify the heterogeneous nucleation potential of ?-Ni grains on Ni3Si particles in Ni-Ni3Si eutectic alloy, the work of adhesion (Wad), fracture toughness (G), interfacial energy (?i), and electronic structure of the index (0 0 1), (1 1 0) and (1 1 1) Ni/Ni3Si interfaces with two different cohesive manners are investigated using first-principles method based on density functional theory. Results indicate that the center site stacking sequence (OM) is preferable to continue the natural stacking sequence of bulk Ni and Ni3Si. Since OM stacking interfaces have larger Wad, G and ?i than that of the top site stacking (OT) interfaces. The Ni/Ni3Si (1 1 0) interface with OM stacking has the best mechanical properties. Therefore, the formation of this interface can improve the stability, ductility and fracture toughness of Ni-Ni3Si eutectic alloy. The calculated interfacial energy of Ni/Ni3Si (0 0 1), (1 1 0) and (1 1 1) interfaces with OM stacking proves the excellent nucleation potency of Ni3Si particles for ?-Ni phase from thermodynamic considerations. Besides, the electronic structure and chemical bonding of (1 1 0) interface with OM stacking are also discussed.

Zhao, Yuhong; Wen, Zhiqin; Hou, Hua; Guo, Wei; Han, Peide

2014-06-01

375

About the shape of eutectic grains solidifying in a thermal gradient  

SciTech Connect

In eutectic alloys solidified in a thermal gradient, it has been observed that the final shape of the grains nucleated in the bulk of the liquid is more elongated in the direction opposite to that of the heat flow. This experimental result appears to be in contraction with that expected for the growth of an isolated grain, since the portion of the interface located n the downstream heat flow direction is the most undercooled and thus has the highest growth rate. However, when considering a family of grains which continuously nucleate in the bulk of the liquid, it is shown that the impingement of the grains limits their growth in the downstream heat flow direction and thus explains their final shape. In order to investigate this phenomenon, the differential equation which governs the growth of an isolated eutectic grain in a thermal gradient has been derived and solved analytically for the two extreme positions of the interface along the heat flow direction. Using these relationships, the asymmetry factor of the grains has been deduced as a function of the solidification parameters. The overall shape of an isolated grain has also been predicted using numerical integration. Finally, these results are integrated into a stochastic model of grain structure formation and the simulated microstructure is compared with experimental micrographs previously obtained for hypereutectic aluminium-silicon alloys remelted by laser.

Rappaz, M.; Charbon, C.; Sasikumar, R. (Ecole Polytechnique Federale, Lausanne (Switzerland). Lab. de Metallurgie Physique)

1994-07-01

376

Thermodynamics of reaction of praseodymium with gallium-indium eutectic alloy  

NASA Astrophysics Data System (ADS)

Thermodynamic properties of Ga-In eutectic alloys saturated with praseodymium were determined for the first time employing the electromotive force method. The equilibrium potentials of the Pr-In alloys saturated with praseodymium (8.7-12.1 mol.% Pr) and Pr-Ga-In alloys (containing 0.0012-6.71 mol.% Pr) were measured between 573-1073 K. Pr-In alloy containing solid PrIn3 with known thermodynamic properties was used as the reference electrode when measuring the potentials of ternary Pr-In-Ga alloys. Activity, partial and excessive thermodynamic functions of praseodymium in alloys with indium and Ga-In eutectic were calculated. Activity (a), activity coefficients (?) and solubility (X) of praseodymium in the studied temperature range can be expressed by the following equations: lga?-Pr(In) = 4.425 - 11965/T ± 0.026. lg??-Pr(Ga-In) = 5.866 - 14766/T ± 0.190. lg??-Pr(Ga-In) = 2.351 - 9996/T ± 0.39. lg?Pr(Ga-In) = 3.515 - 4770/T ± 0.20.

Melchakov, S. Yu.; Ivanov, V. A.; Yamshchikov, L. F.; Volkovich, V. A.; Osipenko, A. G.; Kormilitsyn, M. V.

2013-06-01

377

Thermodynamic properties and equation of state of liquid lead and lead bismuth eutectic  

NASA Astrophysics Data System (ADS)

Since the 1950s, liquid lead (Pb) and lead-bismuth eutectic (Pb-Bi) have been studied in the USA, Canada and in the former-USSR as potential coolants for nuclear installations due to their very attractive thermophysical and neutronic properties. However, experimental data on the thermal properties of these coolants in the temperature range of interest are still incomplete and often contradictory. This makes it very difficult to perform design calculations and to analyse the normal and abnormal behaviour of nuclear installations where these coolants are expected to be used. Recently, a compilation of heavy liquid metal (HLM) properties along with recommendations for its use was prepared by the OECD/NEA Working Party on Fuel Cycle (WPFC) Expert Group on Lead-Bismuth Eutectic Technology. A brief review of this compilation and some new data are presented in this article. A set of correlations for the temperature dependence of the main thermodynamic properties of Pb and Pb-Bi(e) at normal pressure, and a set of simplified thermal and caloric equations of state for the liquid phase are proposed.

Sobolev, V. P.; Schuurmans, P.; Benamati, G.

2008-06-01

378

A Trail of Salts  

NASA Technical Reports Server (NTRS)

This graph shows the relative abundances of sulfur (in the form of sulfur tri-oxide) and chlorine at three Meridiani Planum sites: soil measured in the small crater where Opportunity landed; the rock dubbed 'McKittrick' in the outcrop lining the inner edge of the crater; and the rock nicknamed 'Guadalupe,' also in the outcrop. The 'McKittrick' data shown here were taken both before and after the rover finished grinding the rock with its rock abrasion tool to expose fresh rock underneath. The 'Guadalupe' data were taken after the rover grounded the rock. After grinding both rocks, the sulfur abundance rose to high levels, nearly five times higher than that of the soil. This very high sulfur concentration reflects the heavy presence of sulfate salts (approximately 30 percent by weight) in the rocks. Chloride and bromide salts are also indicated. Such high levels of salts strongly suggest the rocks contain evaporite deposits, which form when water evaporates or ice sublimes into the atmosphere.

2004-01-01

379

Performance optimization of diffused Li on Ga/In eutectic, In/Sn solder and eutectic Ga/In Ohmic contacts to n-high purity-crystalline (100) Ge  

NASA Astrophysics Data System (ADS)

Performance optimization study of novel contacts such as diffused lithium on Ga/In eutectic (75.5/24.5 wt%), In/Sn solder (95.0/5.0 wt%) and Ga/In eutectic (75.5/24.5 wt%) to n-high purity-crystalline <100> Ge (HP-SC-Ge) has been presented. Ultrasonically clean samples taken from same substrate were used to process the contacts followed by their characterization utilizing current--voltage (I--V), Hall-effect and AFM measurements. Extreme care was introduced to minimize the effect of parasitic oxide layers. Contacts such as diffused Li on eutectic Ga/In and In/Sn solder were processed in an inert glove box and characterized at 305 K (RT) and 77 K (LN) respectively. Comparative study revealed that Ga/In eutectics contacts behave throughout linear and stable, showing strong hall-effect to that of its counter parts. This was attributed due to the high adsorption behavior of anions at liquid (Ga--In) contacts and improved wettability. Whereas, for In/Sn solder case, the contacts processing considerations were substantially different, mainly because of its poor solder flow, excessive void formation, and heterogeneous phase distribution responsible for process yield loss. For diffused Li on Ga/In eutectic contacts, the linearity of the obtained Ohmic profiles was not consistent due to the high reactivity of the Li with HP-SC-Ge substrate. This work is supported by DOE grant DE-FG02-10ER46709 and the state of South Dakota.

Khan, Khizar; Gang, Yang; Wang, Guojian; Xiang, Wenchang; Guan, Yutong; Mei, Dongming

2012-02-01

380

Terephthalate salts: salts of monopositive cations  

PubMed

The crystal structures of dilithium, disodium and diammonium terephthalate (1,4-benzenedicarboxylate) have been solved ab initio using Monte Carlo simulated annealing techniques, and refined using synchrotron powder data. The structures of dipotassium terephthalate, potassium hydrogen terephthalate and ammonium hydrogen terephthalate have been refined using single-crystal techniques. Li2C8H4O4 crystallizes in P2(1)/c, with a = 8.35921 (5), b = 5.13208 (2), c = 8.48490 (5) A, beta = 93.1552 (4) degrees, V = 363.451 (3) A3, Z = 2. The Li anions are tetrahedrally coordinated and the packing of the terephthalate anions resembles the gamma-packing of aromatic hydrocarbons. Na2C8H4O4 crystallizes in Pbc2(1), with a = 3.54804 (5), b = 10.81604 (16), c = 18.99430 (20) A, V = 728.92 (2) A3, Z = 4. The coordination of the two independent Na is trigonal prismatic and the terephthalate packing resembles the beta packing of hydrocarbons. (NH4)2C8H4O4 also crystallizes in Pbc2(1), with a = 4.0053 (5), b = 11.8136 (21), c = 20.1857 (24) A, V = 955.1 (2) A3, Z = 4. The cations and planar anions are linked by hydrogen bonds and the packing is a looser version of the beta packing. K2C8H4O2 crystallizes in P2(1)/c, with a = 10.561 (4), b = 3.9440 (12), c = 11.535 (5) A, beta = 113.08 (3) degrees, V = 442.0 (3) A3, Z = 2. The K is trigonal prismatic and the packing is also beta. Both KHC8H4O4 and (NH4)HC8H4O4 crystallize in C2/c, with a = 18.825 (4) and 18.924 (4), b = 3.770 (2) and 3.7967 (9), c = 11.179 (2) and 11.481 (2) A, beta = 98.04 (3) and 94.56 (5) degrees, V = 816.8 (3) and 790.9 (3) A3, respectively, and Z = 4. The packing in the hydrogen-bonded acid salts is also beta. Electrostatic interactions among the terephthalate anions appear to be important in determining the crystal packing. PMID:10877356

Kaduk

2000-06-01

381

Oxygen and chlorine electrodes on semiconductive SnO 2 in molten LiCl-KCl eutectic  

Microsoft Academic Search

The oxidation of oxide (O2-) and chloride ions were studied at tin oxide electrodes in molten LiCl-KCl eutectic at 450° C using voltammetric techniques. The polarization characteristics of the oxide semiconductor electrode were compared with that of Pt in the case of the oxygen electrode and with that of glassy carbon in the case of chlorine evolution. Both electrode reactions

I. Uchida; S. Toshima

1979-01-01

382

Eutectic temperatures and melting relations in the Fe-O-S system at high pressures and temperatures  

NASA Astrophysics Data System (ADS)

We have investigated melting relations in the Fe-O-S ternary system in the pressure range of 15-27 GPa and 1873 K. Subsolidus phase relations are Fe, Fe3S2, and FeO up to 17 GPa and Fe, Fe3S, and FeO above this pressure. The eutectic temperature slightly decreases from ambient pressure to 17 GPa, whereas increases above this pressure. The eutectic temperature in this study is 100 K lower than that in the Fe-S binary system. The oxygen content in the Fe-O-S eutectic liquid drops when the coexisting solid phases changes from FeS to Fe3S2. The cotectic lines in the ternary phase diagram lie close to the Fe-FeS binary axis. The isothermal sections indicate that oxygen solubility in the Fe-O-S liquid increases with increasing temperature, and with increasing sulfur content. The solubility of sulfur in the solid Fe has a maximum value at the eutectic temperature, and decreases with increasing temperature. Our results could have important implications for formation and composition of the Martian core.

Tsuno, Kyusei; Ohtani, Eiji

2009-01-01

383

Microstructural Evolution of Hypoeutectic, Near-Eutectic, and Hypereutectic High-Carbon Cr-Based Hard-Facing Alloys  

NASA Astrophysics Data System (ADS)

A series of high-carbon Cr-based hard-facing alloys were successfully fabricated on a substrate of 0.45 pct C carbon steel by gas tungsten arc welding (GTAW) process using various alloy fillers with chromium and chromium carbide, CrC (Cr:C = 4:1) powders. These claddings were designed to observe hypoeutectic, near-eutectic, and hypereutectic structures with various (Cr,Fe)23C6 and (Cr,Fe)7C3 carbides at room temperature. According to X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and optical microscopy (OM), in 3.8 pct C cladding, the microstructure consisted of the primary carbides with outer shells (Cr,Fe)23C6 surrounding (Cr,Fe)7C3 cores and [ ? + (Cr,Fe)23C6] eutectic structures. In 5.9 pct C cladding, the composite comprised primary (Cr,Fe)7C3 as the reinforcing phase and [? + (Cr,Fe)7C3] eutectic structures as matrix. Various morphologies of carbides were found in primary and eutectic (Cr,Fe)7C3 carbides, which included bladelike and rodlike (with a hexagonal cross section). The 5.9C cladding with great amounts of primary (Cr,Fe)7C3 carbides had the highest hardness (approximately HRC 63.9) of the all conditions.

Lin, Chi-Ming; Chang, Chia-Ming; Chen, Jie-Hao; Hsieh, Chih-Chun; Wu, Weite

2009-05-01

384

Spectrographic analysis of bismuth-tin eutectic alloys by spark-ignited low-voltage ac-arc excitation  

NASA Technical Reports Server (NTRS)

Spectrographic method determines individual stainless steel components in molten bismuth-42 w/o tin eutectic to determine the solubility of Type 304 stainless steels. It utilizes the high sensitivity and precision of the spark-ignited, low-voltage ac-arc excitation of samples rendered homogeneous by dissolution.

Huff, E. A.; Kulpa, S. J.

1969-01-01

385

Tensile Strength and Microstructure of Al2O3-ZrO2 Hypo-Eutectic Fibers Studied  

NASA Technical Reports Server (NTRS)

Oxide eutectics offer high-temperature strength retention and creep resistance in oxidizing environments. Al2O3-ZrO2 eutectic strengths have been studied since the 1970's. Directionally solidified oxide eutectics exhibit improved resistance to slow crack growth and excellent strength retention at high temperatures up to 1400 C. Materials studied typically contain Y2O3 to metastably retain the high-temperature cubic and tetragonal polymorphs at room temperature. Al2O3-ZrO2 is of fundamental interest for creep studies because it combines a creep-resistant material, Al2O3, with a very low creep resistance material, ZrO2. Results on mechanical properties and microstructures of these materials will be used to define compositions for creep testing in future work. Substantial variations from the eutectic alumina to zirconia ratio can be tolerated without a loss in room-temperature strength. The effect of increasing Y2O3 addition on the room-temperature tensile strength of an Al2O3-ZrO2 material containing excess Al2O3 was examined at the NASA Glenn Research Center, where the materials were grown using Glenn's world-class laser growth facilities.

Farmer, Serene C.; Sayir, Ali

2001-01-01

386

A Finite-Element-Based Methodology for Evaluating Solder Electromigration Current Limits of Sn\\/Pb Eutectic Solder Bumps  

Microsoft Academic Search

This paper investigates the effect of current distribution to the bump and current crowding on the electromigration (EM) of Sn\\/Pb eutectic solder bumps. The peak current density in the bump is found to have a significant effect on the EM lifetime of the tested structures and, thus, impacts the maximum allowable bump current. A finite-element model is developed which accurately

Walter Dauksher; Dennis H. Eaton; James D. Rowatt

2008-01-01

387

Molten salt lithium cells  

DOEpatents

Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400.degree.-500.degree. C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell (10) which may be operated at temperatures between about 100.degree.-170.degree. C. Cell (10) comprises an electrolyte (16), which preferably includes lithium nitrate, and a lithium or lithium alloy electrode (12).

Raistrick, Ian D. (Menlo Park, CA); Poris, Jaime (Portola Valley, CA); Huggins, Robert A. (Stanford, CA)

1983-01-01

388

Molten salt lithium cells  

DOEpatents

Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400.degree.-500.degree. C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell (10) which may be operated at temperatures between about 100.degree.-170.degree. C. Cell (10) comprises an electrolyte (16), which preferably includes lithium nitrate, and a lithium or lithium alloy electrode (12).

Raistrick, Ian D. (Menlo Park, CA); Poris, Jaime (Portola Valley, CA); Huggins, Robert A. (Stanford, CA)

1982-02-09

389

Modeling Solute Thermokinetics in LiCI-KCI Molten Salt for Nuclear Waste Separation  

SciTech Connect

Recovery of actinides is an integral part of a closed nuclear fuel cycle. Pyrometallurgical nuclear fuel recycling processes have been developed in the past for recovering actinides from spent metallic and nitride fuels. The process is essentially to dissolve the spent fuel in a molten salt and then extract just the actinides for reuse in a reactor. Extraction is typically done through electrorefining, which involves electrochemical reduction of the dissolved actinides and plating onto a cathode. Knowledge of a number of basic thermokinetic properties of salts and salt-fuel mixtures is necessary for optimizing present and developing new approaches for pyrometallurgical waste processing. The properties of salt-fuel mixtures are presently being studied, but there are so many solutes and varying concentrations that direct experimental investigation is prohibitively time consuming and expensive (particularly for radioactive elements like Pu). Therefore, there is a need to reduce the number of required experiments through modeling of salt and salt-fuel mixture properties. This project will develop first-principles-based molecular modeling and simulation approaches to predict fundamental thermokinetic properties of dissolved actinides and fission products in molten salts. The focus of the proposed work is on property changes with higher concentrations (up to 5 mol%) of dissolved fuel components, where there is still very limited experimental data. The properties predicted with the modeling will be density, which is used to assess the amount of dissolved material in the salt; diffusion coefficients, which can control rates of material transport during separation; and solute activity, which determines total solubility and reduction potentials used during electrorefining. The work will focus on La, Sr, and U, which are chosen to include the important distinct categories of lanthanides, alkali earths, and actinides, respectively. Studies will be performed using LiCl-KCl salt at the eutectic composition (58 mol% LiCl, 42 mol% KCl), which is used for treating spent EBR-II fuel. The same process being used for EBRII fuel is currently being studied for widespread international implementation. The methods will focus on first-principles and first- principles derived interatomic potential based simulations, primarily using molecular dynamics. Results will be validated against existing literature and parallel ongoing experimental efforts. The simulation results will be of value for interpreting experimental results, validating analytical models, and for optimizing waste separation by potentially developing new salt configurations and operating conditions.

Morgan, Dane; Eapen, Jacob

2013-10-01

390

Electrolyte salts for nonaqueous electrolytes  

DOEpatents

Metal complex salts may be used in lithium ion batteries. Such metal complex salts not only perform as an electrolyte salt in a lithium ion batteries with high solubility and conductivity, but also can act as redox shuttles that provide overcharge protection of individual cells in a battery pack and/or as electrolyte additives to provide other mechanisms to provide overcharge protection to lithium ion batteries. The metal complex salts have at least one aromatic ring. The aromatic moiety may be reversibly oxidized/reduced at a potential slightly higher than the working potential of the positive electrode in the lithium ion battery. The metal complex salts may also be known as overcharge protection salts.

Amine, Khalil; Zhang, Zhengcheng; Chen, Zonghai

2012-10-09

391

Bacterial degradation of bile salts  

Microsoft Academic Search

Bile salts are surface-active steroid compounds. Their main physiological function is aiding the digestion of lipophilic nutrients\\u000a in intestinal tracts of vertebrates. Many bacteria are capable of transforming and degrading bile salts in the digestive tract\\u000a and in the environment. Bacterial bile salt transformation and degradation is of high ecological relevance and also essential\\u000a for the biotechnological production of steroid

Bodo Philipp

2011-01-01

392

Electrochromic Salts, Solutions, and Devices  

DOEpatents

Electrochromic salts. Electrochromic salts of dicationic viologens such as methyl viologen and benzyl viologen associated with anions selected from bis(trifluoromethylsulfonyl)imide, bis(perfluoroethylsulfonyl)imide, and tris(trifluoromethylsulfonyl)methide are produced by metathesis with the corresponding viologen dihalide. They are highly soluble in molten quarternary ammonium salts and together with a suitable reductant provide electrolyte solutions that are used in electrochromic windows.

Burrell, Anthony K. (Los Alamos, NM); Warner, Benjamin P. (Los Alamos, NM); McClesky, T. Mark (Los Alamos, NM)

2008-11-11

393

Electrochromic salts, solutions, and devices  

SciTech Connect

Electrochromic salts. Electrochromic salts of dicationic viologens such as methyl viologen and benzyl viologen associated with anions selected from bis(trifluoromethylsulfonyl)imide, bis(perfluoroethylsulfonyl)imide, and tris(trifluoromethylsulfonyl)methide are produced by metathesis with the corresponding viologen dihalide. They are highly soluble in molten quarternary ammonium salts and together with a suitable reductant provide electrolyte solutions that are used in electrochromic windows.

Burrell, Anthony K. (Los Alamos, NM); Warner, Benjamin P. (Los Alamos, NM); McClesky,7,064,212 T. Mark (Los Alamos, NM)

2006-06-20

394

Competitive growth of stable and metastable Fe- C- X eutectics: Part I. experiments  

NASA Astrophysics Data System (ADS)

The effect of small additions of Si, P, Cr, Mn, Ti, Al, and S to pure Fe-C eutectic, upon the transi-tion velocities from grey to white and white to grey cast iron, has been measured by varying the growth rate during directional solidification. As a result, it is found that alloying elements can be classified into three types: graphitizing (Si, Al, P, and S), carburizing (Cr), and “hysteretic effect” (Mn, Ti). The well-known influence of a thermal gradient (or the superheat) has been shown to af-fect only the grey-to-white transition. Growth undercoolings were measured as a function of growth rate, while the average lamellar spacings were determined from transverse sections of directionally solidified samples. A small addition of the element studied can have a marked effect upon these parameters.

Magnin, P.; Kurz, W.

1988-08-01

395

Deep-eutectic solvents playing multiple roles in the synthesis of polymers and related materials.  

PubMed

The aim of this review is to provide an exposition of some of the most recent applications of deep-eutectic solvents (DESs) in the synthesis of polymers and related materials. We consider that there is plenty of room for the development of fundamental research in the field of DESs because their compositional flexibility makes the number of DESs susceptible of preparation unlimited and so do the range of properties that DESs can attain. Ultimately, these properties can be transferred into the resulting materials in terms of both tailored morphologies and compositions. Thus, interesting applications can be easily envisaged, especially in those fields in which the preparation of high-tech products via low cost processes is critical. We hope that the preliminary work surveyed in this review will encourage scientists to explore the promising perspectives offered by DESs. PMID:22695767

Carriazo, Daniel; Serrano, María Concepción; Gutiérrez, María Concepción; Ferrer, María Luisa; del Monte, Francisco

2012-07-21

396

Directionally solidified lamellar eutectic superalloys by edge-defined, film-fed growth. [including tensile tests  

NASA Technical Reports Server (NTRS)

A program was performed to scale up the edge-defined, film-fed growth (EFG) method for the gamma/gamma prime-beta eutectic alloy of the nominal composition Ni-19.7 Cb - 6 Cr-2.5 Al. Procedures and problem areas are described. Flat bars approximately 12 x 1.7 x 200 mm were grown, mostly at speeds of 38 mm/hr, and tensile tests on these bars at 25 and 1000 C showed lower strength than expected. The feasibility of growing hollow airfoils was also demonstrated by growing bars over 200 mm long with a teardrop shaped cross-section, having a major dimension of 12 mm and a maximum width of 5 mm.

Hurley, G. F.

1975-01-01

397

Natural deep eutectic solvents providing enhanced stability of natural colorants from safflower (Carthamus tinctorius).  

PubMed

A certain combination of natural products in the solid state becomes liquid, so called natural deep eutectic solvents (NADES). Recently, they have been considered promising new green solvents for foods, cosmetics and pharmaceuticals due to their unique solvent power which can dissolve many non-water-soluble compounds and their low toxicity. However, in addition to the features as solvents, the stabilisation ability of NADES for compounds is important for their further applications. In the study, the stability analysis demonstrates that natural pigments from safflower are more stable in sugar-based NADES than in water or 40% ethanol solution. Notably, the stabilisation capacity of NADES can be adjusted by reducing water content with increasing viscosity. The strong stabilisation ability is due to the formation of strong hydrogen bonding interactions between solutes and NADES molecules. The stabilising ability of NADES for phenolic compounds shows great promise for their applications in food, cosmetic and pharmaceutical industries. PMID:24767033

Dai, Yuntao; Verpoorte, Robert; Choi, Young Hae

2014-09-15

398

Electrodeposition of copper oxide from the eutectic sodium-potassium nitrate melt  

SciTech Connect

Oxide films are of interest for a variety of practical applications, including corrosion protection, batteries, high temperature superconductors, catalysts, electronic devices, and flat panel displays. Copper injected anodically into eutectic Na-K nitrate melt at 300 C is shown to deposit cathodically as cupric oxide (CuO). The dissolved copper is in the +2 oxidation state and apparently forms a nitrate complex that facilitates reduction of nitrate to oxide (and nitrite) at potentials more than a volt positive of that for reduction of the Na/K nitrate species. From these results and literature studies, cathodic metal oxide deposition from nitrate melts appears to be a general phenomenon that could prove to be a practical means of preparing anhydrous metal oxide films.

Tench, D.M.; Kendig, M.W.; Jeanjaquet, S. (Rockwell International Science Center, Thousand Oaks, CA (United States))

1994-02-01

399

Superconductivity in filamentary eutectic composites. Progress report, June 1, 1980-May 31, 1980  

SciTech Connect

Measurements of electrical resistivity and magnetic susceptibility have been performed as a function of temperature on samples of Nb-Th eutectic composite. Samples with Nb filament radii as small as 38A were used which is considerably less than the coherence length xi in Nb of approx. 380A. Surprisingly, measurements of all samples showed a drop in electrical resistance near the transition temperature of bulk Nb and an unmeasurably small resistance by approx. 8K. The magnetic susceptibility showed essentially perfect diamagnetism below approx. 7 to 9K even for samples with the smallest of filament radii. This is in contradiction to theories of the proximity effect which predict a sharp decrease in the transition temperature for samples with a radius smaller than xi. Some measurements in a static magnetic field have also been made.

Zaitlin, M P

1980-01-01

400

Heat treating of a lamellar eutectic alloy (gamma/gamma prime + delta). [heat resistant alloys  

NASA Technical Reports Server (NTRS)

Eutectic superalloys are being developed at several laboratories for application as aircraft gas turbine airfoils. One such alloy was subjected to several heat treatments to determine if its mechanical properties could be improved. It was found that by partially dissolving the alloy at 1210 C and then aging at 900 C the tensile strength can be increased about 12 percent at temperatures up to 900 C. At 1040 C no change in tensile strength was observed. Times to rupture were measured between 760 and 1040 C and were essentially the same or greater than for as-grown material. Tensile and rupture ductility of the alloy are reduced by heat treatment. Photographs of the microstructure are shown.

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

1976-01-01

401

Comparison of Co-C eutectic fixed-point cells between VNIIM and VNIIOFI  

NASA Astrophysics Data System (ADS)

Two national metrological institutes of the Russian Federation, VNIIM and VNIIOFI, take part in the international research plan of CCT WG5 for investigation of high-temperature fixed points (HTFP). In the framework of this CCT-WG5 HTFP Research Plan the both institutes have designed and built independently cobalt-carbon (Co-C) eutectic radiation cells. The comparison of the Co-C cells developed by the institutes was carried out with the aim of determination of a difference in the melting temperature due to difference in the constructional characteristics of the cells. The radiance-mode radiation thermometers with central wavelength nearby 650 nm were used for the fixed-point melting temperature measurements. The article presents preliminary results of the comparison, which shows agreement between melting temperature of the compared cells within 20 mK. The details of the comparison are reported.

Sild, Y.; Khlevnoy, B.; Matveyev, M.; Grigorieva, I. A.; Fuksov, V. M.

2013-09-01

402

Crystalline surface phases of the liquid Au-Si eutectic alloy  

NASA Astrophysics Data System (ADS)

A two-dimensional crystalline layer is found at the surface of the liquid eutectic Au82Si18 alloy above its melting point TM=359°C . Underlying this crystalline layer, we find a layered structure, 6-7 atomic layers thick. This surface layer undergoes a first-order solid-solid phase transition occurring at 371°C . The crystalline phase observed for T>371°C is stable up to at least 430°C . Grazing-incidence x-ray diffraction data at T>371°C imply lateral order comprising two coexisting phases of different oblique unit cells, in stark contrast with the single phase with a rectangular unit cell found for low-temperature crystalline phase, 359°C

Shpyrko, Oleg G.; Streitel, Reinhard; Balagurusamy, Venkatachalapathy S. K.; Grigoriev, Alexei Yu.; Deutsch, Moshe; Ocko, Benjamin M.; Meron, Mati; Lin, Binhua; Pershan, Peter S.

2007-12-01

403

An atomistic insight into the corrosion of the oxide film in liquid lead-bismuth eutectic.  

PubMed

When used as a protective scale, the Fe3O4 layer covering the stainless steel surface in accelerator driven subcritical systems (ADS) is corroded by liquid lead-bismuth eutectics (LBE). By performing theoretical calculations, we reveal that both Pb and Bi at the interface between the LBE and the Fe3O4 scale, favorably adsorb onto the Fe3O4 surfaces, weakening the strength of Fe-O bonds nearby significantly. This facilitates the movement of iron atoms toward the deposited Pb(Bi) and away from the Fe3O4 surface, thus causing corrosion. Such corrosion behavior becomes severe if oxygen vacancies exist in the surface region. PMID:24626636

Li, Dongdong; Song, Chi; He, H Y; Liu, C S; Pan, B C

2014-04-28

404

Tailoring nickel coatings via electrodeposition from a eutectic-based ionic liquid doped with nicotinic acid  

NASA Astrophysics Data System (ADS)

Pure nickel (Ni) was electrodeposited onto a copper (Cu) substrate from choline chloride-urea (1:2 molar ratio) eutectic-based ionic liquid (1:2 ChCl-urea IL) with 0-1200 mg/L additions of nicotinic acid (NA). The effect of NA on the voltammetric behavior of Ni (II) was investigated by cyclic voltammetry, whilst the nucleation/growth of Ni deposits was studied by chronoamperometry. The resultant surface morphologies and microstructures of the Ni coatings were revealed by SEM/EDXS, XRD and TEM, demonstrating that NA can inhibit, hence tailor, the Ni deposition and serve as a very effective brightener producing highly uniform and smooth Ni deposits. The nucleation/growth process of Ni was not affected by the presence of NA, proceeding via three-dimensional instantaneous nucleation. NA has a profound grain refining effect with a grain size of ˜4.2 nm achievable.

Yang, Haiyan; Guo, Xingwu; Birbilis, Nick; Wu, Guohua; Ding, Wenjiang

2011-08-01

405

Tensile properties influencing variables in eutectic Al-Si casting alloys  

SciTech Connect

Efforts to identify and characterize the physical properties of aluminum castings alloys are envisaged to lead to a new guideline from which the mechanical behavior of these alloys can be accurately predicted. For aluminum-silicon (Al-Si) casting alloys the tensile properties of a specific composition are observed to vary depending on the production parameters. The difference in the tensile properties appears to be mainly due to the microstructural features concomitant with the imposed production parameters. The present study aims to identify, quantitatively, the tensile properties influencing variables in high purity eutectic Al-Si casting alloy produced under a variety of solidification cooling rate with different strontium (Sr) additions, as a modifying agent. The correlation between the fracture characteristics and the microstructures has also been investigated.

Hafiz, M.F. (Al-Azhar Univ., Cairo (Egypt). Dept. of Mechanical Engineering); Kobayashi, Toshiro (Toyohashi Univ. of Technology, Aichi (Japan). Dept. of Production Systems Engineering)

1994-09-15

406

Hypereutectic aluminum-silicon alloy having refined primary silicon and a modified eutectic  

SciTech Connect

A hypereutectic aluminum-silicon casting alloy is described consisting essentially of 19% to 30% by weight of silicon, 0.03% to 1.6% by weight of magnesium, less than 0.37% by weight of copper, less than 0.03% by weight of manganese, less than 0.04% by weight of iron, 0.005% to 0.06% by weight of phosphorous, 0. 15% to 1. 1 5% by weight of titanium, and the balance aluminum, said alloy having a liquidus temperature above the peritectic temperature for the formation of titanium-aluminum particles, said alloy having a metallographic structure consisting of refined primary silicon particles and a modified silicon phase in the eutectic.

Donahue, R.J.; Hesterberg, W.G.; Cleary, T.M.

1993-08-10

407

3D CAFE modeling of grain structures: application to primary dendritic and secondary eutectic solidification  

NASA Astrophysics Data System (ADS)

A three-dimensional model is presented for the prediction of grain structures formed in casting. It is based on direct tracking of grain boundaries using a cellular automaton (CA) method. The model is fully coupled with a solution of the heat flow computed with a finite element (FE) method. Several unique capabilities are implemented including (i) the possibility to track the development of several types of grain structures, e.g. dendritic and eutectic grains, (ii) a coupling scheme that permits iterations between the FE method and the CA method, and (iii) tabulated enthalpy curves for the solid and liquid phases that offer the possibility to work with multicomponent alloys. The present CAFE model is also fully parallelized and runs on a cluster of computers. Demonstration is provided by direct comparison between simulated and recorded cooling curves for a directionally solidified aluminum-7 wt% silicon alloy.

Carozzani, T.; Digonnet, H.; Gandin, Ch-A.

2012-01-01

408

Tetrabutylammonium bromide (TBABr)-based deep eutectic solvents (DESs) and their physical properties.  

PubMed

Density, viscosity and ionic conductivity data sets of deep eutectic solvents (DESs) formed by tetrabutylammonium bromide (TBABr) paired with ethlyene glycol, 1,3-propanediol, 1,5-pentanediol and glycerol hydrogen bond donors (HBDs) are reported. The properties of DES were measured at temperatures between 303 K and 333 K for HBD percentages of 66.7% to 90%. The effects of HBDs under different temperature and percentages are systematically analyzed. As expected, the measured density and viscosity of the studied DESs decreased with an increase in temperature, while ionic conductivity increases with temperature. In general, DESs made of TBABr and glycerol showed the highest density and viscosity and the lowest ionic conductivity when compared to other DESs. The presence of an extra hydroxyl group on glycerol in a DES affected the properties of the DES. PMID:24932572

Yusof, Rizana; Abdulmalek, Emilia; Sirat, Kamaliah; Rahman, Mohd Basyaruddin Abdul

2014-01-01

409

Assessment of cytotoxicity and toxicity for phosphonium-based deep eutectic solvents.  

PubMed

In this work, the cytotoxicity and toxicity of phosphonium-based deep eutectic solvents (DESs) with three hydrogen bond donors, namely glycerine, ethylene glycol, and triethylene glycol were investigated. The cytotoxicity effect was tested using brine shrimp (Artemia salina). The toxicity was investigated using the two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity of tested DESs was much higher than that of their individual components, indicating their toxicological behavior was different. It was also found that there was toxic effect on the studied bacteria, indicating their potential application as anti-bacterial agents. To the best of our knowledge, this is the first time the cytotoxicity and toxicity of phosphonium-based DESs were studied. PMID:23820537

Hayyan, Maan; Hashim, Mohd Ali; Al-Saadi, Mohammed A; Hayyan, Adeeb; AlNashef, Inas M; Mirghani, Mohamed E S

2013-09-01

410

Salt sensitivity in chickpea.  

PubMed

The growth of chickpea (Cicer arietinum L.) is very sensitive to salinity, with the most susceptible genotypes dying in just 25 mm NaCl and resistant genotypes unlikely to survive 100 mm NaCl in hydroponics; germination is more tolerant with some genotypes tolerating 320 mm NaCl. When growing in a saline medium, Cl(-), which is secreted from glandular hairs on leaves, stems and pods, is present in higher concentrations in shoots than Na(+). Salinity reduces the amount of water extractable from soil by a chickpea crop and induces osmotic adjustment, which is greater in nodules than in leaves or roots. Chickpea rhizobia show a higher 'free-living' salt resistance than chickpea plants, and salinity can cause large reductions in nodulation, nodule size and N(2)-fixation capacity. Recent screenings of diverse germplasm suggest significant variation of seed yield under saline conditions. Both dominance and additive gene effects have been identified in the effects of salinity on chickpea and there appears to be sufficient genetic variation to enable improvement in yield under saline conditions via breeding. Selections are required across the entire life cycle with a range of rhizobial strains under salt-affected, preferably field, conditions. PMID:19843257

Flowers, Timothy J; Gaur, Pooran M; Gowda, C L Laxmipathi; Krishnamurthy, L; Samineni, Srinivasan; Siddique, Kadambot H M; Turner, Neil C; Vadez, Vincent; Varshney, Rajeev K; Colmer, Timothy D

2010-04-01

411

Dietary Salt Intake and Hypertension  

PubMed Central

Over the past century, salt has been the subject of intense scientific research related to blood pressure elevation and cardiovascular mortalities. Moderate reduction of dietary salt intake is generally an effective measure to reduce blood pressure. However, recently some in the academic society and lay media dispute the benefits of salt restriction, pointing to inconsistent outcomes noted in some observational studies. A reduction in dietary salt from the current intake of 9-12 g/day to the recommended level of less than 5-6 g/day will have major beneficial effects on cardiovascular health along with major healthcare cost savings around the world. The World Health Organization (WHO) strongly recommended to reduce dietary salt intake as one of the top priority actions to tackle the global non-communicable disease crisis and has urged member nations to take action to reduce population wide dietary salt intake to decrease the number of deaths from hypertension, cardiovascular disease and stroke. However, some scientists still advocate the possibility of increased risk of CVD morbidity and mortality at extremes of low salt intake. Future research may inform the optimal sodium reduction strategies and intake targets for general populations. Until then, we have to continue to build consensus around the greatest benefits of salt reduction for CVD prevention, and dietary salt intake reduction strategies must remain at the top of the public health agenda.

2014-01-01

412

Dietary salt intake and hypertension.  

PubMed

Over the past century, salt has been the subject of intense scientific research related to blood pressure elevation and cardiovascular mortalities. Moderate reduction of dietary salt intake is generally an effective measure to reduce blood pressure. However, recently some in the academic society and lay media dispute the benefits of salt restriction, pointing to inconsistent outcomes noted in some observational studies. A reduction in dietary salt from the current intake of 9-12 g/day to the recommended level of less than 5-6 g/day will have major beneficial effects on cardiovascular health along with major healthcare cost savings around the world. The World Health Organization (WHO) strongly recommended to reduce dietary salt intake as one of the top priority actions to tackle the global non-communicable disease crisis and has urged member nations to take action to reduce population wide dietary salt intake to decrease the number of deaths from hypertension, cardiovascular disease and stroke. However, some scientists still advocate the possibility of increased risk of CVD morbidity and mortality at extremes of low salt intake. Future research may inform the optimal sodium reduction strategies and intake targets for general populations. Until then, we have to continue to build consensus around the greatest benefits of salt reduction for CVD prevention, and dietary salt intake reduction strategies must remain at the top of the public health agenda. PMID:25061468

Ha, Sung Kyu

2014-06-01

413

Meloxicam transdermal delivery: effect of eutectic point on the rate and extent of skin permeation  

PubMed Central

Objective(s): Drug delivery through the skin can transfer therapeutic levels of drugs for pharmacological effects. Analgesics such as NSAIDs have gastrointestinal side effects and topical dosage forms of these drugs are mainly preferred, especially for local pains. Meloxicam is one of NSAIDs with no topical form in the market. In this research, we attempted to quantify the skin permeation of a meloxicam topical preparation and to show how permeation would be increased by using thymol as an enhancer. The effect of eutectic point of drug and thymol mixture on rate and extent of skin permeation was also studied. Materials and Methods: Different mixtures of thymol and meloxicam (2:8, 4:6, 5:5, 6:4, 8:2) were prepared and their melting point were obtained by differential scanning calorimetry. Then drug permeation was measured using diffusion cells and the Guinea pig skin. Results: Mixtures in ratios 5:5 and 4:6 of meloxicam / thymol showed a new endotherm at 149 and 140°C in DSC thermograms. The permeability of meloxicam from the creams containing 6:4, 5:5 and 4:6 ratios of meloxicam to thymol were 4.71, 15.2, 22.06 µg/cm2 respectively. This was significantly different from the cream of pure meloxicam (3.76 µg/cm2). Conclusion: This study set out to determine that thymol plays as a skin permeation enhancer and increases the meloxicam skin absorption and this enhancement is significant at the eutectic point of drug-enhancer mixture.

Mohammadi-Samani, Soliman; Yousefi, Gholamhossein; Mohammadi, Farhad; Ahmadi, Fatemeh

2014-01-01

414

Numerical Modeling of Lead Oxidation in Controlled Lead Bismuth Eutectic Systems: Chemical Kinetics and Hydrodynamic Effects  

SciTech Connect

Using liquid Lead-Bismuth Eutectic (LBE) as coolant in nuclear systems has been studied for more than 50 years. And LBE has many unique nuclear, thermo physical and chemical attributes which are attractive for practical application. But, corrosion is one of the greatest concerns in using liquid Lead-Bismuth Eutectic (LBE) as spallation target in the Accelerator-driven Transmutation of Waste (ATW) program. Los Alamos National Laboratory has designed and built the Liquid Lead-Bismuth Materials Test Loop (MTL) to study the materials behavior in a flow of molten LBE. A difference of 100 deg. C was designed between the coldest and the hottest parts at a nominal flow rate of 8.84 GPM. Liquid LBE flow was activated by a mechanical sump pump or by natural convection. In order to maintain a self-healing protective film on the surface of the stainless steel pipe, a certain concentration of oxygen has to be maintained in the liquid metal. Therefore, it is of importance to understand what the oxygen concentrations are in the LBE loop related to the corrosion effects on the metal surface, the temperature profiles, the flow rates, and diffusion rates through the metal surface. The chemical kinetics also needs to be fully understood in the corrosion processes coupled with the hydrodynamics. The numerical simulation will be developed and used to analyze the system corrosion effects with different kind of oxygen concentrations, flow rates, chemical kinetics, and geometries. The hydrodynamics modeling of using computational fluid dynamics will provide the necessary the levels of oxygen and corrosion products close to the boundary or surface. This paper presents an approach towards the above explained tasks by analyzing the reactions between the Lead and oxygen at a couple of sections in the MTL. Attempt is also made to understand the surface chemistry by choosing an example model and estimating the near wall surface concentration values for propane and oxygen. (authors)

Wu, Chao; Kanthi Kiran Dasika; Chen, Yitung; Moujaes, Samir [Department of Mechanical Engineering, University of Nevada, Las Vegas, 4505 Maryland Parkway, Las Vegas NV, 89154-4027 (United States)

2002-07-01

415

Developments in Molten Salt and Liquid-Salt-Cooled Reactors  

Microsoft Academic Search

In the last 5 years, there has been a rapid growth in interest in the use of high-temperature (700 to 1000 deg C) molten and liquid fluoride salts as coolants in nuclear systems. This renewed interest is a consequence of new applications for high-temperature heat and the development of new reactor concepts. Fluoride salts have melting points between 350 and

Charles W. Forsberg; Charles W

2006-01-01

416

Boron carbon nitride nanostructures from salt melts: tunable water-soluble phosphors.  

PubMed

A simple, high yield, chemical process is developed to fabricate layered h-BN nanosheets and BCNO nanoparticles with a diameter of ca. 5 nm at 700 °C. The use of the eutectic LiCl/KCl salt melt medium enhances the kinetics of the reaction between sodium borohydride and urea or guanidine as well as the dispersion of the nanoparticles in water. The carbon content can be tuned from 0 to 50 mol % by adjusting the reactant ratio, thus providing precise control of the light emission of the particles in the range 440-528 nm while reaching a quantum yield of 26%. Because of their green synthesis, low toxicity, small size, and stability against aggregation in water, the as-obtained photoluminescent BCNO nanoparticles show promise for diagnostics and optoelectronics. PMID:21506566

Lei, Weiwei; Portehault, David; Dimova, Rumiana; Antonietti, Markus

2011-05-11

417

History Leaves Salts Behind  

NASA Technical Reports Server (NTRS)

These plots, or spectra, show that a rock dubbed 'McKittrick' near the Mars Exploration Rover Opportunity's landing site at Meridiani Planum, Mars, has higher concentrations of sulfur and bromine than a nearby patch of soil nicknamed 'Tarmac.' These data were taken by Opportunity's alpha particle X-ray spectrometer, which uses curium-244 to assess the elemental composition of rocks and soil. Only portions of the targets' full spectra are shown to highlight the significant differences in elemental concentrations between 'McKittrick' and 'Tarmac.' Intensities are plotted on a logarithmic scale.

A nearby rock named Guadalupe similarly has extremely high concentrations of sulfur, but very little bromine. This 'element fractionation' typically occurs when a watery brine slowly evaporates and various salt compounds are precipitated in sequence.

2004-01-01

418

Salt resistant crop plants.  

PubMed

Soil salinity is a major constraint to agriculture. To improve salinity tolerance of crops, various traits can be incorporated, including ion exclusion, osmotic tolerance and tissue tolerance. We review the roles of a range of genes involved in salt tolerance traits. Different tissues and cells are adapted for specific and often diverse function, so it is important to express the genes in specific cell-types and to pyramid a range of traits. Modern biotechnology (marker-assisted selection or genetic engineering) needs to be increasingly used to introduce the correct combination of genes into elite crop cultivars. Importantly, the effects of introduced genes need to be evaluated in the field to determine their effect on salinity tolerance and yield improvement. PMID:24679267

Roy, Stuart J; Negrão, Sónia; Tester, Mark

2014-04-01

419

Computer Simulations of Salt Solubility  

NSDL National Science Digital Library

Computer Simulations of Salt Solubility provides an animated, visual interpretation of the different solubilities of related salts based on simple entropy changes associated with dissolution: configurational disorder and thermal disorder. This animation can also help improve students conceptual understanding of chemical equilibrium before any quantitative interpretation of equilibrium constants is attempted.

420

Art with Salt and Ice  

NSDL National Science Digital Library

This open-ended art project allows learners to create their own colorful ice sculpture by using rock salt and food coloring on a solid block of ice. The entire activity is like a mini-science lesson because it teaches learners the physical reaction of salt on ice.

Kcet

2007-01-01

421

CHED Events: Salt Lake City  

NASA Astrophysics Data System (ADS)

The Division of Chemical Education (CHED) Committee meetings planned for the Spring 2009 ACS Meeting in Salt Lake City will be in the Marriott City Center Hotel. Check the location of other CHED events, the CHED Social Event, the Undergraduate Program, Sci-Mix, etc. because many will be in the Salt Palace Convention Center.

Wink, Donald J.

2009-03-01

422

Temperature effect on laser-induced breakdown spectroscopy spectra of molten and solid salts  

NASA Astrophysics Data System (ADS)

Laser-induced breakdown spectroscopy (LIBS) has been investigated as a potential analytical tool to improve operations and safeguards for electrorefiners, such as those used in processing spent nuclear fuel. This study set out to better understand the effect of sample temperature and physical state on LIBS spectra of molten and solid salts by building calibration curves of cerium and assessing self-absorption, plasma temperature, electron density, and local thermal equilibrium (LTE). Samples were composed of a LiCl-KCl eutectic salt, an internal standard of MnCl2, and varying concentrations of CeCl3 (0.1, 0.3, 0.5, 0.8, and 1.0 wt.% Ce) under different temperatures (773, 723, 673, 623, and 573 K). Analysis of salts in their molten form is preferred as plasma plumes from molten samples experienced less self-absorption, less variability in plasma temperature, and higher clearance of the minimum electron density required for local thermal equilibrium. These differences are attributed to plasma dynamics as a result of phase changes. Spectral reproducibility was also better in the molten state due to sample homogeneity.

Hanson, Cynthia; Phongikaroon, Supathorn; Scott, Jill R.

2014-07-01

423

Plant salt-tolerance mechanisms.  

PubMed

Crop performance is severely affected by high salt concentrations in soils. To engineer more salt-tolerant plants it is crucial to unravel the key components of the plant salt-tolerance network. Here we review our understanding of the core salt-tolerance mechanisms in plants. Recent studies have shown that stress sensing and signaling components can play important roles in regulating the plant salinity stress response. We also review key Na+ transport and detoxification pathways and the impact of epigenetic chromatin modifications on salinity tolerance. In addition, we discuss the progress that has been made towards engineering salt tolerance in crops, including marker-assisted selection and gene stacking techniques. We also identify key open questions that remain to be addressed in the future. PMID:24630845

Deinlein, Ulrich; Stephan, Aaron B; Horie, Tomoaki; Luo, Wei; Xu, Guohua; Schroeder, Julian I

2014-06-01

424

Effect of salt on the formation of salt-bridges in ?-hairpin peptides.  

PubMed

Salt-bridges ubiquitously form between oppositely charged moieties in proteins. Here we quantify changes in population of salt-bridged ?-hairpin peptides due to added salt, and determine the thermodynamic driving forces and cooperativity of salt-bridge formation under these conditions. We find only a fraction of salt-bridged folded conformations at physiologically relevant salt concentrations. PMID:24926740

Sukenik, Shahar; Boyarski, Yoav; Harries, Daniel

2014-07-01

425

Nickel-plating for active metal dissolution resistance in molten fluoride salts  

NASA Astrophysics Data System (ADS)

Ni electroplating of Incoloy-800H was investigated with the goal of mitigating Cr dissolution from this alloy into molten 46.5%LiF-11.5%NaF-42%KF eutectic salt, commonly referred to as FLiNaK. Tests were conducted in graphite crucibles at a molten salt temperature of 850 °C. The crucible material graphite accelerates the corrosion process due to the large activity difference between the graphite and the alloy. For the purposes of providing a baseline for this study, un-plated Incoloy-800H and a nearly pure Ni-alloy, Ni-201 were also tested. Results indicate that Ni-plating has the potential to significantly improve the corrosion resistance of Incoloy-800H in molten fluoride salts. Diffusion of Cr from the alloy through the Ni-plating does occur and if the Ni-plating is thin enough this Cr eventually dissolves into the molten salt. The post-corrosion test microstructure of the Ni-plating, particularly void formation was also observed to depend on the plating thickness. Diffusion anneals in a helium environment of Ni-plated Incoloy-800H and an Fe-Ni-Cr model alloy were also investigated to understand Cr diffusion through the Ni-plating. Further enhancements in the efficacy of the Ni-plating as a protective barrier against Cr dissolution from the alloy into molten fluoride salts can be achieved by thermally forming a Cr 2O 3 barrier film on the surface of the alloy prior to Ni electroplating.

Olson, Luke; Sridharan, Kumar; Anderson, Mark; Allen, Todd

2011-04-01

426

7 CFR 58.721 - Salt.  

...Agriculture 3 2014-01-01 2014-01-01 false Salt. 58.721 Section 58.721 Agriculture Regulations...Quality Specifications for Raw Material § 58.721 Salt. Salt shall be free flowing, white refined sodium chloride...

2014-01-01

427

7 CFR 58.721 - Salt.  

Code of Federal Regulations, 2013 CFR

...Agriculture 3 2013-01-01 2013-01-01 false Salt. 58.721 Section 58.721 Agriculture Regulations...Quality Specifications for Raw Material § 58.721 Salt. Salt shall be free flowing, white refined sodium chloride...

2013-01-01

428

40 CFR 721.6085 - Phosphonocarboxylate salts.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Phosphonocarboxylate salts. 721.6085 Section 721.6085 ...Substances § 721.6085 Phosphonocarboxylate salts. (a) Chemical substances and significant...identified generically as phosphonocarboxylate salts (PMNs P-93-722,...

2011-07-01

429

7 CFR 58.721 - Salt.  

Code of Federal Regulations, 2012 CFR

...Agriculture 3 2012-01-01 2012-01-01 false Salt. 58.721 Section 58.721 Agriculture Regulations...Quality Specifications for Raw Material § 58.721 Salt. Salt shall be free flowing, white refined sodium chloride...

2012-01-01

430

7 CFR 58.721 - Salt.  

Code of Federal Regulations, 2010 CFR

...Agriculture 3 2010-01-01 2010-01-01 false Salt. 58.721 Section 58.721 Agriculture Regulations...Quality Specifications for Raw Material § 58.721 Salt. Salt shall be free flowing, white refined sodium chloride...

2010-01-01

431

7 CFR 58.721 - Salt.  

Code of Federal Regulations, 2011 CFR

...Agriculture 3 2011-01-01 2011-01-01 false Salt. 58.721 Section 58.721 Agriculture Regulations...Quality Specifications for Raw Material § 58.721 Salt. Salt shall be free flowing, white refined sodium chloride...

2011-01-01

432

On the Impurity Parameters for Impurities Detected in the Eutectics Co-C and Pt-C and Their Role in the Estimate of the Uncertainty in the Eutectic Temperatures  

NASA Astrophysics Data System (ADS)

In this paper, impurity parameters m i and k i have been calculated for a range of impurities I as detected in the eutectics Co-C and Pt-C, by means of the software package Thermo-Calc within the ternary phase spaces Co-C- I and Pt-C- I. The choice of the impurities is based upon a selection out of the results of impurity analyses performed for a representative set of samples for each of the eutectics in study. The analyses in question are glow discharge mass spectrometry (GDMS) or inductively coupled plasma mass spectrometry (ICP-mass). Tables and plots of the impurity parameters against the atomic number Z i of the impurities will be presented, as well as plots demonstrating the validity of van't Hoff's law, the cornerstone to this study, for both eutectics. For the eutectics in question, the uncertainty u( T E - T liq ) in the correction T E - T liq will be derived, where T E and T liq refer to the transition temperature of the pure system and to the liquidus temperature in the limit of zero growth rate of the solid phase during solidification of the actual system, respectively. Uncertainty estimates based upon the current scheme SIE-OME, combining the sum of individual estimates (SIE) and the overall maximum estimate (OME) are compared with two alternative schemes proposed in this paper, designated as IE-IRE, combining individual estimates (IE) and individual random estimates (IRE), and the hybrid scheme SIE-IE-IRE, combining SIE, IE, and IRE.

Bloembergen, Pieter; Dong, Wei; Bai, Cheng-Yu; Wang, Tie-Jun

2011-12-01

433

Hot tensile properties and deformation response of a gamma/Ni/-gamma prime/Ni3Al/-delta/Ni3Nb/ eutectic composite  

NASA Technical Reports Server (NTRS)

Three distinct regions of tensile, deformation and fracture behavior were observed in a 2.5 wt. per cent Al gamma/gamma prime-delta eutectic alloy as the testing temperature was varied. The major finding was an extraordinary ductility maximum at about 550 C. It was shown that this phenomenon is caused by the deflection of transverse cracks at the eutectic grain boundaries when yielding occurs. This delamination between eutectics grains caused by fracture of a gamma prime eutectic grain boundary film leads to a distinctly different 'wood-like' fracture surface morphology. Above 690 C to 926 C, yield and tensile strength values decrease while ductility increase slightly. Cooperative twinning of both phases develops giving rise to block-like deformation of the microstructure quite in parallel to the behavior observed previously in the gamma-delta system.

Bertorello, H. R.; Hertzberg, R. W.; Kraft, R. W.

1975-01-01

434

Mechanism of formation of the anomalous eutectic structure in rapidly solidified Ni-Si, Co-Sb and Ni-Al-Ti alloys  

SciTech Connect

Electromagnetic levitation technique was applied to crystallize containerless bulk melts of eutectic Ni-Si, Co-Sb and Ni-Al-Ti alloys at various undercoolings and cooling rates. Complementary, the drop-tube technique was used to solidify droplets of the same alloys at high cooling rates as splats. At small undercoolings, a regular lamellar eutectic microstructure was found which undergoes a partial transition above a critical undercooling to an anomalous eutectic structure. This critical undercooling depends on the cooling rate. The transition is explained by a fragmentation of primary grown eutectic lamellae, with the reduction of the interfacial energy as its driving force. Fragmentation models are applied to describe quantitatively the observed processes.

Goetzinger, R.; Barth, M.; Herlach, D.M. [Deutsches Zentrum fuer Luft- und Raumfahrt, Cologne (Germany). Inst. fuer Raumsimulation] [Deutsches Zentrum fuer Luft- und Raumfahrt, Cologne (Germany). Inst. fuer Raumsimulation

1998-03-02

435

Improving the Mechanical Properties of Fe-Nb-(Ni-Mn) Dendrite-Ultrafine Eutectic Composites via Controlling the Primary Phase Features  

NASA Astrophysics Data System (ADS)

Tuning of microstructure by addition of austenite stabilizers effectively enhances the mechanical properties in Fe-Nb-(Ni-Mn) dendrite-ultrafine eutectic composites. The Fe93Nb7 alloy displays the improved plasticity up to 10 pct due to the introduction of a ductile ?-Fe dendrite into the ultrafine eutectic matrix. Meanwhile, the Fe78Nb7Ni10Mn5 alloy, which forms an in-situ martensitic ?'-Fe dendritic phase reinforced ultrafine eutectic composite exhibits excellent combination of a high fracture strength of 1.6 GPa and a large plastic strain of 11 pct. The investigations reveal that the characteristics of the modulated primary dendrites in the dendrite-ultrafine eutectic composites play an important role in manipulating the generation and propagation of shear bands, thus resulting in the improved mechanical properties and plastic deformation behavior.

Park, Jin Man; Kim, Tae Eung; Kim, Suk Jun; Kim, Won Tae; Kühn, Uta; Eckert, Jürgen; Kim, Do Hyang

2012-08-01

436

Salt Lake City, Utah  

NASA Technical Reports Server (NTRS)

The 2002 Winter Olympics are hosted by Salt Lake City at several venues within the city, in nearby cities, and within the adjacent Wasatch Mountains. This simulated natural color image presents a late spring view of north central Utah that includes all of the Olympic sites. The image extends from Ogden in the north, to Provo in the south; and includes the snow-capped Wasatch Mountains and the eastern part of the Great Salt Lake.

This image was acquired on May 28, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The Terra mission is part of NASA's Earth Science Enterprise, a long-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as a total integrated system.

The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

Size: 63.5 x 123.3 km (38.1 x 74 miles) Location: 40.7 deg. North lat., 111.9 deg. West long. Orientation: North at top Image Data: ASTER bands 1,2, and 3. Original Data Resolution: 15 m Date Acquired: May 28, 2000

2001-01-01

437

Will salt repositories be dry?  

NASA Astrophysics Data System (ADS)

The National Academy of Science committee that considered geologic disposal of nuclear waste in the mid-1950s recommended salt as a repository medium, partly because of its high thermal conductivity and because it was believed to be “dry” (perhaps the appropriate thought is “impermeable”). Certainly, the fact that Paleozoic salt deposits exist in many parts of t h e world is evidence for very low rates of dissolution by moving groundwater. The fact that the dissolution rates were so small led many scientists to the conclusion that the salt beds were nearly impermeable. The major source of brine within the salt beds was thought to be fluid inclusions within salt crystals, which could migrate through differential solution toward a source of high heat. The idea that salt was uniformly “dry” was revised when exploratory drilling in the vicinity of the Waste Isolation Pilot Plant (WIPP) in New Mexico encountered brines within the Castile Formation, an evaporite deposit below the Salado Formation. The brine reservoirs were thought to be isolated pockets of brine in an otherwise “impermeable” salt section.

Bredehoeft, John D.

438

Analysis of directional solidification of molybdenum(5)silicon(3)-molybdenum silicide aligned lamellar eutectics and the effect of residual stress induced cracking  

Microsoft Academic Search

The Mo-Si phase diagram exhibits a Mo5Si3-MoSi 2 eutectic at the 54% Si composition. Since the terminal phases have comparable melting points and are equidistant from the eutectic composition, there is the possibility of obtaining lamellar microstructures in this system. In addition, if the alloys are directionally solidified, there is the further possibility of obtaining aligned lamellae. In this study,

Stanislaw Marek Borowicz

2002-01-01

439

Aging characteristics of Ga\\/sub 1-x\\/Al\\/sub x\\/As double-heterostructure lasers bonded with gold eutectic alloy solder  

Microsoft Academic Search

Aging characteristics of Ga\\/sub 1-x\\/Al\\/sub x\\/As DH lasers bonded with gold eutectic alloy solder and indium solder were studied. In the lasers bonded with indium solder, it was found that thermal resistance increased during the aging test and the activation energy for the increasing rate of thermal resistance was 0.6 eV. Sixteen lasers bonded with gold-tin eutectic alloy solder have

K. Fujiwara; T. Fujiwara; K. Hori; M. Takusagawa

1979-01-01

440

Interaction of Al-Si, Al-Ge, and Zn-Al eutectic alloys with SiC\\/Al discontinuously reinforced metal matrix composites  

Microsoft Academic Search

Interactions between Al-Si, Al-Ge, and Zn-Al eutectic alloys with SiC whisker-reinforced aluminium metal matrix composites were studied as a function of temperature above the eutectic melting temperature. Penetration extended several millimetres into the composite for the Al-Si and Al-Ge alloys but was restricted to a thin surface layer (50 µm) for the Zn-Al alloy. The extent of the penetration zone

W. C. Moshier; J. S. Ahearn; D. C. Cooke

1987-01-01

441

Investigation of the microstructure of the Al–Si eutectic in binary aluminium–7 wt% silicon alloys by electron backscatter diffraction (EBSD)  

Microsoft Academic Search

Binary aluminium–7 wt% silicon alloys with and without strontium modification have been cast with a cooling rate of 0.2–0.6°C\\/s. The level of impurities has been kept at a minimum. The crystallographic orientation of the dendritic and eutectic aluminium as well as the eutectic silicon has been studied using electron backscatter diffraction (EBSD). The crystallographic orientation of the aluminium within the

G. Heiberg; L. Arnberg

2001-01-01

442

Preliminary study on nano- and micro-composite sol–gel based alumina coatings on structural components of lead–bismuth eutectic cooled fast breeder reactors  

Microsoft Academic Search

In order to protect the structural components of lead–bismuth eutectic cooled fast breeder reactors from liquid metal corrosion, Al2O3 nano- and micro-composite coatings were developed using an improved sol–gel process, which includes dipping specimens in a sol–gel solution dispersed with fine ?-Al2O3 powders prepared by mechanical milling. Accelerated corrosion tests were conducted on coated specimens in liquid lead–bismuth eutectic at

Peng Dou; Ryuta Kasada

2011-01-01

443

Nucleation Control and Thermal Aging Resistance of Near-Eutectic Sn-Ag-Cu-X Solder Joints by Alloy Design  

NASA Astrophysics Data System (ADS)

Elemental (X) additions to Sn-3.5Ag-0.95Cu (SAC3595) solder were developed with minimal (<0.25 wt.%) concentration to avoid pro-eutectic Ag3Sn blades by reducing undercooling (? T) and to eliminate thermal-aging-induced embrittlement. Calorimetry and microstructure results on simple Cu/Cu joints identified 0.21Zn, 0.10Mn, and 0.05Al as sufficient to reduce undercooling below that for SAC3595 and to eliminate Ag3Sn blades. A 211°C melting onset for the X = Mn alloys also suggested the discovery of a new quaternary eutectic. Shear testing and microstructure analysis of larger joints showed that 0.05Al and 0.21Zn additions resulted in reduced as-soldered strength (30 MPa), like Sn-0.95Cu, but all joints showed ductile failure at about 30 MPa after 1000 h at 150°C.

Anderson, Iver E.; Walleser, Jason W.; Harringa, Joel L.; Laabs, Fran; Kracher, Alfred

2009-12-01

444

Self-calibration of a W/Re thermocouple using a miniature Ru-C (1954 °C) eutectic cell  

NASA Astrophysics Data System (ADS)

Previous successful investigations of miniature cobalt-carbon (Co-C, 1324 °C) and palladium-carbon (Pd-C, 1492 °C) high temperature fixed-point cells for thermocouple self-calibration have been reported [1-2]. In the present work, we describe a series of measurements of a miniature ruthenium-carbon (Ru-C) eutectic cell (melting point 1954 °C) to evaluate the repeatability and stability of a W/Re thermocouple (type C) by means of in-situ calibration. A miniature Ru-C eutectic fixed-point cell with outside diameter 14 mm and length 30 mm was fabricated to be used as a self-calibrating device. The performance of the miniature Ru-C cell and the type C thermocouple is presented, including characterization of the stability, repeatability, thermal environment influence, ITS-90 temperature realization and measurement uncertainty.

Ongrai, O.; Pearce, J. V.; Machin, G.; Sweeney, S. J.

2013-09-01

445

Stress analysis, thermomechanical fatique evaluation, and root subcomponent testing of gamma/gamma prime-delta eutectic alloy  

NASA Technical Reports Server (NTRS)

Thermomechanical fatigue (TMF) and root subcomponent tensile, creep, and low cycle fatigue (LCF) tests were conducted to determine the capability of a fully lamellar directionally solidified eutectic alloy to sustain the airfoil thermal fatigue and root attachment loads anticipated in advanced, hollow, high work turbine blades. A three dimensional finite element elastic stress analysis was performed on typical advanced hollow eutectic airfoil and root-platform designs to determine appropriate conditions for these tests. Results of TMF tests conducted on longitudinal specimens (stress axis parallel to the solidification direction) containing a simulated leading edge cooling hole pattern indicated the longitudinal TMF properties to be more than adequate for the particular advanced hollow blade analyzed, with the strain range for a 10,000 cycle life being more than 50% above the maximum strain range calculated for the advanced hollow blade.

Sheffler, K. D.; Jackson, J. J.

1976-01-01

446

Self-calibration of a W/Re thermocouple using a miniature Ru-C (1954 °C) eutectic cell  

SciTech Connect

Previous successful investigations of miniature cobalt-carbon (Co-C, 1324 °C) and palladium-carbon (Pd-C, 1492 °C) high temperature fixed-point cells for thermocouple self-calibration have been reported [1-2]. In the present work, we describe a series of measurements of a miniature ruthenium-carbon (Ru-C) eutectic cell (melting point 1954 °C) to evaluate the repeatability and stability of a W/Re thermocouple (type C) by means of in-situ calibration. A miniature Ru-C eutectic fixed-point cell with outside diameter 14 mm and length 30 mm was fabricated to be used as a self-calibrating device. The performance of the miniature Ru-C cell and the type C thermocouple is presented, including characterization of the stability, repeatability, thermal environment influence, ITS-90 temperature realization and measurement uncertainty.

Ongrai, O. [National Physical Laboratory (NPL), Hampton Road, Teddington, Middlesex (United Kingdom) [National Physical Laboratory (NPL), Hampton Road, Teddington, Middlesex (United Kingdom); University of Surrey, Guildford, Surrey (United Kingdom); National Institute of Metrology, Klong 5, Klong Luang, Pathumthani (Thailand); Pearce, J. V.; Machin, G. [National Physical Laboratory (NPL), Hampton Road, Teddington, Middlesex (United Kingdom)] [National Physical Laboratory (NPL), Hampton Road, Teddington, Middlesex (United Kingdom); Sweeney, S. J. [University of Surrey, Guildford, Surrey (United Kingdom)] [University of Surrey, Guildford, Surrey (United Kingdom)

2013-09-11

447

Development and Evaluation of Directionally-Solidified NiAl/(CR,MO)-Based Eutectic Alloys for Airfoil Applications  

NASA Technical Reports Server (NTRS)

The results of recent efforts to develop directionally-solidified alloys based on the Ni-33Al-31Cr-3Mo eutectic composition are discussed. These developmental efforts included studying the effects of macroalloying and growth rates on microstructure formation as well as the elevated temperature compressive and tensile properties of these alloys. These observations revealed that contrary to conventional opinion, the cellular microstructure was stronger and tougher than the planar eutectic microstructure due to a microstructural refinement of the cell size and interlamellar spacing. The high temperature strengths of these alloys are compared with those of commercial superalloys and advanced NiAl single crystals. The implications of this research on airfoil manufacturing and applications are discussed.

Raj, S. V.; Locci, I. E.; Whittenberger, J. D.

2001-01-01

448

The nature of the ordering of atoms in a melt and the surface properties of simple eutectic systems  

Microsoft Academic Search

Using the models reconstructed from the experimental structure factor curves by the reverse Monte-Carlo and Voronoy-Delaunay\\u000a methods the local atomic structures of the Sn-Ge, Ag-Ge, and Ni-C simple eutectic systems has been analyzed. It has been found\\u000a that the nature of the atom ordering in melts is responsible not only for the melt bulk properties, but for its surface properties

V. P. Kazimirov; A. S. Roik; V. M. Perevertailo; O. B. Loginova; S. A. Lisovenko

2008-01-01

449

Transition probabilities in the absorption and fluorescence spectra of lanthanides in molten lithium nitrate: potassium nitrate eutectic  

Microsoft Academic Search

Oscillator strengths for f ..-->.. f transitions in Pm\\/sup 3 +\\/, Sm\\/sup 3 +\\/, Eu\\/sup 3 +\\/, Tb\\/sup 3 +\\/, Dy\\/sup 3 +\\/, and Ho\\/sup 3 +\\/, each in molten LiNOâ--KNOâ eutectic at 160°C, have been measured. Based on these results, parameters of the Judd--Ofelt theory for electric-dipole transitions were computed. Together with similar parameters for other members of the

W. T. Carnall; Jan P. Hessler; F. Jr. Wagner

1978-01-01

450

Bonding of Mg and Al with Mg–Al eutectic alloy and its application in aluminum coating on magnesium  

Microsoft Academic Search

Magnesium and aluminum were bonded successfully by using Mg–Al eutectic alloy as the solder under different pressures at 450°C in atmosphere. The microstructures of the Mg\\/Al joints were characterized by SEM, the composition analyzed by EDS, and their bond strengths measured by the bend test. The results show that the bond strength of these Mg\\/Al joints is improved with increasing

Xianrong Li; Wei Liang; Xingguo Zhao; Yan Zhang; Xiaopeng Fu; Fencheng Liu

2009-01-01

451

The solubility of helium and argon in liquid lead, bismuth, and their eutectic alloy at high temperatures  

Microsoft Academic Search

The “hole” model is used to calculate the solubility of inert gases of helium and argon, in heavy liquid-metal coolants of\\u000a fast nuclear power reactors, such as lead, bismuth, and lead-bismuth eutectic, at temperatures up to 1000 K and pressure of\\u000a 0.1 MPa. The relative error of the resultant calculation data is estimated.

E. E. Shpil’rain; S. N. Skovorod’ko; A. G. Mozgovoi

2007-01-01

452

Reflow soldering and isothermal solid-state aging of SnAg eutectic solder on Au\\/Ni surface finish  

Microsoft Academic Search

The reaction between the eutectic Sn-3.5Ag solder and the Au\\/Ni surface finish during reflow as well as during isothermal\\u000a aging was studied. The Au layer was electroplated and had a thickness of the one ?m. The peak reflow temperature was fixed\\u000a at 250 C while the reflow time was varied between 10 sec and one h. Samples that went through

C. M. Liu; C. E. Ho; W. T. Chen; C. R. Kao

2001-01-01

453

A fine pitch COG technique using eutectic Bi-Sn solder joints for LCD driver IC packaging applications  

Microsoft Academic Search

We developed the fine pitch COG (chip on glass) technique using the eutectic Bi-Sn solder bumps for LCD driver IC packaging. The fine pitch Bi-Sn solder bumps were fabricated using the evaporation method and lift-off process and joined the metal pad on the glass substrate. The minimum pitch was 50 ?m and the joining temperature was kept below 160°C. The

Un-Byoung Kang; Young-Ho Kim

2001-01-01

454

Effect of eutectic phase on damping and mechanical properties of as-cast Mg-Ni hypoeutectic alloys  

Microsoft Academic Search

Dynamic mechanical analysis (DMA) was applied to systematically investigate the low frequency damping properties of as-cast hypoeutectic Mg-Ni alloys. The results show that the as-cast hypoeutectic Mg-Ni alloys exhibit high damping capacities. The strain amplitude dependent damping curve has its own special characteristic, in which the damping is strongly related to the strain amplitude. The effect of the eutectic phase

Di-qing WAN; Jin-cheng WANG; Gai-fang WANG; Lin LIN; Zhi-gang FENG; Gen-cang YANG

2009-01-01

455

Sr-Al-Si co-segregated regions in eutectic Si phase of Sr-modified Al-10Si alloy.  

PubMed

The addition of 200 ppm strontium to an Al-10 wt% Si casting alloy changes the morphology of the eutectic silicon phase from coarse plate-like to fine fibrous networks. In order to clarify this modification mechanism the location of Sr within the eutectic Si phase has been investigated by a combination of high-resolution methods. Whereas three-dimensional atom probe tomography allows us to visualise the distribution of Sr on the atomic scale and to analyse its local enrichment, transmission electron microscopy yields information about the crystallographic nature of segregated regions. Segregations with two kinds of morphologies were found at the intersections of Si twin lamellae: Sr-Al-Si co-segregations of rod-like morphology and Al-rich regions of spherical morphology. Both are responsible for the formation of a high density of multiple twins and promote the anisotropic growth of the eutectic Si phase in specific crystallographic directions during solidification. The experimental findings are related to the previously postulated mechanism of "impurity induced twinning". PMID:23298536

Timpel, M; Wanderka, N; Schlesiger, R; Yamamoto, T; Isheim, D; Schmitz, G; Matsumura, S; Banhart, J

2013-09-01

456

Recent advances in the molten salt destruction of energetic materials  

SciTech Connect

We have demonstrated the use of the Molten Salt Destruction (MSD) Process for destroying explosives, liquid gun propellant, and explosives-contaminated materials on a 1.5 kg of explosive/hr bench- scale unit (1, 2, 3, 4, 5). In our recently constructed 5 kg/hr pilot- scale unit we have also demonstrated the destruction of a liquid gun propellant and simulated wastes containing HMX (octogen). MSD converts the organic constituents of the waste into non-hazardous substances such as carbon dioxide, nitrogen, and water. Any inorganic constituents of the waste, such as metallic particles, are retained in the molten salt. The destruction of energetic materials waste is accomplished by introducing it, together with air, into a vessel containing molten salt (a eutectic mixture of sodium, potassium, and lithium carbonates). The following pure explosives have been destroyed in our bench-scale experimental unit located at Lawrence Livermore National Laboratory`s (LLNL) High Explosives Applications Facility (HEAF): ammonium picrate, HMX, K- 6 (keto-RDX), NQ, NTO, PETN, RDX, TATB, and TNT. In addition, the following compositions were also destroyed: Comp B, LX- IO, LX- 1 6, LX- 17, PBX-9404, and XM46 (liquid gun propellant). In this 1.5 kg/hr bench-scale unit, the fractions of carbon converted to CO and of chemically bound nitrogen converted to NO{sub x} were found to be well below 1%. In addition to destroying explosive powders and compositions we have also destroyed materials that are typical of residues which result from explosives operations. These include shavings from machined pressed parts of plastic-bonded explosives and sump waste containing both explosives and non-explosive debris. Based on the process data obtained on the bench-scale unit we designed and constructed a next-generation 5 kg/hr pilot-scale unit, incorporating LLNL`s advanced chimney design. The pilot unit has completed process implementation operations and explosives safety reviews. To date, in this pilot unit we have successfully destroyed liquid gun propellant and dimethylsulfoxide containing HMX in continuous, long-duration runs.

Pruneda, C. O., LLNL

1996-09-01

457

Synthesis of Quaternary Heterocyclic Salts  

PubMed Central

The microwave synthesis of twenty quaternary ammonium salts is described. The syntheses feature comparable yields to conventional synthetic methods reported in the current literature with reduced reaction times and the absence of solvent or minimal solvent.

Winstead, Angela J.; Nyambura, Grace; Matthews, Rachael; Toney, Deveine; Oyaghire, Stanley

2014-01-01

458

Sodium (Salt or Sodium Chloride)  

MedlinePLUS

... Fit-Friendly Worksites Program Requirements Fit-Friendly Resources Sodium and Salt Updated:Jun 23,2014 About Sodium Frequently Asked ... Dining Out • Cookbooks and Health Guides Reduce Your Sodium Intake Receive Healthy Living news every month! First ...

459

Salts Are Mostly NOT Ionized.  

ERIC Educational Resources Information Center

Discusses the misconception that salts are completely ionizing in solution, the presence of this error in textbooks, probable origins of the error, covalent bonding and ion pairs, and how to tell students the truth. (MKR)

Hawkes, Stephen J.

1996-01-01

460

Growth of new ternary intermetallic phases from Ca/Zn eutectic flux  

NASA Astrophysics Data System (ADS)

The eutectic 7.3:2.7 molar ratio mixture of calcium and zinc metal melts at 394 °C and was explored as a solvent for the growth of new intermetallic phases for potential use as hydrogen storage materials. The reaction of nickel in this molten mixture produces two new phases—the CaCu 5-related structure CaNi 2Zn 3 ( P6/ mmm, a=8.9814(5) Å, c=4.0665(5) Å) and a new cubic structure Ca 21Ni 2Zn 36 ( Fd-3 m, a=21.5051(4) Å). Palladium-containing reactions produced CaPd 0.85Zn 1.15 with the orthorhombic TiNiSi structure type ( Pnma, a=7.1728(9) Å, b=4.3949(5) Å, c=7.7430(9) Å). Reactions of platinum in the Ca/Zn mixture p