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1

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

2

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

3

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

4

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

5

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

6

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

7

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

8

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

9

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

10

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

11

Main chemical species and molecular structure of deep eutectic solvent studied by experiments with DFT calculation: a case of choline chloride and magnesium chloride hexahydrate.  

PubMed

The infrared spectrum of deep eutectic solvent of choline chloride and magnesium chloride hexahydrate was measured by the FTIR spectroscopy and analyzed with the aid of DFT calculations. The main chemical species and molecular structure in deep eutectic solvent of [MgClm(H2O)6-m](2-m) and [ChxCly](x+y) complexes were mainly identified and the active ion of magnesium complex during the electrochemical process was obtained. The mechanism of the electrochemical process of deep eutectic solvent of choline chloride and magnesium chloride hexahydrate was well explained by combination theoretical calculations and experimental. Besides, based on our results we proposed a new system for the dehydration study of magnesium chloride hexahydrate. PMID:25031082

Zhang, Chao; Jia, Yongzhong; Jing, Yan; Wang, Huaiyou; Hong, Kai

2014-08-01

12

Deep Eutectic Solvents for the Self-Assembly of Gold Nanoparticles: A SAXS, UV-Vis, and TEM Investigation.  

PubMed

In this work, we report the formation and growth mechanisms of gold nanoparticles (AuNPs) in eco-friendly deep eutectic solvents (DES; choline chloride and urea). AuNPs are synthesized on the DES surface via a low-energy sputter deposition method. Detailed small angle X-ray scattering (SAXS), UV-Vis, and cryogenic transmission electron microscopy (cryo-TEM) investigations show the formation of AuNPs of 5 nm diameter. Data analysis reveals that for a prolonged gold-sputtering time there is no change in the size of the particles. Only the concentration of AuNPs increases linearly in time. More surprisingly, the self-assembly of AuNPs into a first and second shell ordered system is observed directly by in situ SAXS for prolonged gold-sputtering times. The self-assembly mechanism is explained by the templating nature of DES combined with the equilibrium between specific physical interaction forces between the AuNPs. A disulfide-based stabilizer, bis((2-mercaptoethyl)trimethylammonium) disulfide dichloride, was applied to suppress the self-assembly. Moreover, the stabilizer even reverses the self-assembled or agglomerated AuNPs back to stable 5 nm individual particles as directly evidenced by UV-Vis. The template behavior of DES is compared to that of nontemplating solvent castor oil. Our results will also pave the way to understand and control the self-assembly of metallic and bimetallic nanoparticles. PMID:24814886

Raghuwanshi, Vikram Singh; Ochmann, Miguel; Hoell, Armin; Polzer, Frank; Rademann, Klaus

2014-06-01

13

In situ fabrication of electrochemically grown mesoporous metallic thin films by anodic dissolution in deep eutectic solvents.  

PubMed

We describe here a simple electrodeposition process of forming thin films of noble metallic nanoparticles such as Au, Ag and Pd in deep eutectic solvents (DES). The method consists of anodic dissolution of the corresponding metal in DES followed by the deposition on the cathodic surface. The anodic dissolution process in DES overcomes the problems associated with copious hydrogen and oxygen evolution on the electrode surface when carried out in aqueous medium. The proposed method utilizes the inherent abilities of DES to act as a reducing medium while simultaneously stabilizing the nanoparticles that are formed. The mesoporous metal films were characterized by SEM, XRD and electrochemical techniques. Potential applications of these substrates in surface enhanced Raman spectroscopy and electrocatalysis have been investigated. A large enhancement of Raman signal of analyte was achieved on the mesoporous silver substrate after removing all the stabilizer molecules from the surface by calcination. The highly porous texture of the electrodeposited film provides superior electro catalytic performance for hydrogen evolution reaction (HER). The mechanisms of HER on the fabricated substrates were studied by Tafel analysis and electrochemical impedance spectroscopy (EIS). PMID:24863793

Renjith, Anu; Roy, Arun; Lakshminarayanan, V

2014-07-15

14

Improved solubility of DNA in recyclable and reusable bio-based deep eutectic solvents with long-term structural and chemical stability.  

PubMed

The solubility of DNA in bio-based deep eutectic solvents (DESs) consisting of mixtures of choline chloride with levulinic acid, glycerol, ethylene glycol, sorbitol and resorcinol was investigated. The macromolecule was found to be soluble and chemically and structurally stable in DESs consisting of mixtures containing glycerol and ethylene glycol. Furthermore recyclability of the DESs was demonstrated over three consecutive reuses in DNA dissolution. PMID:24022824

Mondal, Dibyendu; Sharma, Mukesh; Mukesh, Chandrakant; Gupta, Vishal; Prasad, Kamalesh

2013-10-25

15

Use of dilute hydrofluoric acid and deep eutectic solvent systems for back end of line cleaning in integrated circuit fabrication  

NASA Astrophysics Data System (ADS)

Fabrication of current generation integrated circuits involves the creation of multilevel copper/low-k dielectric structures during the back end of line processing. This is done by plasma etching of low-k dielectric layers to form vias and trenches, and this process typically leaves behind polymer-like post etch residues (PER) containing copper oxides, copper fluorides and fluoro carbons, on underlying copper and sidewalls of low-k dielectrics. Effective removal of PER is crucial for achieving good adhesion and low contact resistance in the interconnect structure, and this is accomplished using wet cleaning and rinsing steps. Currently, the removal of PER is carried out using semi-aqueous fluoride based formulations. To reduce the environmental burden and meet the semiconductor industry's environmental health and safety requirements, there is a desire to completely eliminate solvents in the cleaning formulations and explore the use of organic solvent-free formulations. The main objective of this work is to investigate the selective removal of PER over copper and low-k (Coral and Black DiamondRTM) dielectrics using all-aqueous dilute HF (DHF) solutions and choline chloride (CC) -- urea (U) based deep eutectic solvent (DES) system. Initial investigations were performed on plasma oxidized copper films. Copper oxide and copper fluoride based PER films representative of etch products were prepared by ashing g-line and deep UV photoresist films coated on copper in CF4/O2 plasma. PER removal process was characterized using scanning electron microscopy and X-ray photoelectron spectroscopy and verified using electrochemical impedance spectroscopy measurements. A PER removal rate of ~60 A/min was obtained using a 0.2 vol% HF (pH 2.8). Deaeration of DHF solutions improved the selectivity of PER over Cu mainly due to reduced Cu removal rate. A PER/Cu selectivity of ~20:1 was observed in a 0.05 vol% deaerated HF (pH 3). DES systems containing 2:1 U/CC removed PER at a rate of ~10 and ~20 A/min at 40 and 70°C respectively. A mixture of 10-90 vol% de-ionized water (W) with 2:1 U/CC in the temperature range of 20 to 40°C also effectively removed PER. Importantly, etch rate of copper and low-k dielectric in DES formulations were lower than that in conventional DHF cleaning solutions.

Padmanabhan Ramalekshmi Thanu, Dinesh

16

How a protein can remain stable in a solvent with high content of urea: insights from molecular dynamics simulation of Candida antarctica lipase B in urea?:?choline chloride deep eutectic solvent.  

PubMed

Deep eutectic solvents (DESs) are utilized as green and inexpensive alternatives to classical ionic liquids. It has been known that some of DESs can be used as solvent in the enzymatic reactions to obtain very green chemical processes. DESs are quite poorly understood at the molecular level. Moreover, we do not know much about the enzyme microstructure in such systems. For example, how some hydrolase can remain active and stable in a deep eutectic solvent including 9 M of urea? In this study, the molecular dynamics of DESs as a liquid was simulated at the molecular level. Urea?:?choline chloride as a well-known eutectic mixture was chosen as a model DES. The behavior of the lipase as a biocatalyst was studied in this system. For comparison, the enzyme structure was also simulated in 8M urea. The thermal stability of the enzyme was also evaluated in DESs, water, and 8M urea. The enzyme showed very good conformational stability in the urea?:?choline chloride mixture with about 66% urea (9 M) even at high temperatures. The results are in good agreement with recent experimental observations. In contrast, complete enzyme denaturation occurred in 8M urea with only 12% urea in water. It was found that urea molecules denature the enzyme by interrupting the intra-chain hydrogen bonds in a "direct denaturation mechanism". However, in a urea?:?choline chloride deep eutectic solvent, as a result of hydrogen bonding with choline and chloride ions, urea molecules have a low diffusion coefficient and cannot reach the protein domains. Interestingly, urea, choline, and chloride ions form hydrogen bonds with the surface residues of the enzyme which, instead of lipase denaturation, leads to greater enzyme stability. To the best of our knowledge, this is the first study in which the microstructural properties of a macromolecule are examined in a deep eutectic solvent. PMID:24930496

Monhemi, Hassan; Housaindokht, Mohammad Reza; Moosavi-Movahedi, Ali Akbar; Bozorgmehr, Mohammad Reza

2014-06-25

17

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

18

Introducing deep eutectic solvents to polar organometallic chemistry: chemoselective addition of organolithium and grignard reagents to ketones in air.  

PubMed

Despite their enormous synthetic relevance, the use of polar organolithium and Grignard reagents is greatly limited by their requirements of low temperatures in order to control their reactivity as well as the need of dry organic solvents and inert atmosphere protocols to avoid their fast decomposition. Breaking new ground on the applications of these commodity organometallics in synthesis under more environmentally friendly conditions, this work introduces deep eutetic solvents (DESs) as a green alternative media to carry out chemoselective additions of ketones in air at room temperature. Comparing their reactivities in DES with those observed in pure water suggest that a kinetic activation of the alkylating reagents is taking place, favoring nucleophilic addition over the competitive hydrolysis, which can be rationalized through formation of halide-rich magnesiate or lithiate species. PMID:24771680

Vidal, Cristian; García-Álvarez, Joaquín; Hernán-Gómez, Alberto; Kennedy, Alan R; Hevia, Eva

2014-06-01

19

Part I: Virtual laboratory versus traditional laboratory: Which is more effective for teaching electrochemistry? Part II: The green synthesis of aurones using a deep eutectic solvent  

NASA Astrophysics Data System (ADS)

The role of the teaching laboratory in science education has been debated over the last century. The goals and purposes of the laboratory are still debated and while most science educators consider laboratory a vital part of the education process, they differ widely on the purposes for laboratory and what methods should be used to teach laboratory. One method of instruction, virtual labs, has become popular among some as a possible way of capitalizing on the benefits of lab in a less costly and more time flexible format. The research regarding the use of virtual labs is limited and the few studies that have been done on General Chemistry labs do not use the virtual labs as a substitute for hands-on experiences, but rather as a supplement to a traditional laboratory program. This research seeks to determine the possible viability of a virtual simulation to replace a traditional hands-on electrochemistry lab in the General Chemistry II course sequence. The data indicate that for both content knowledge and the development of hands-on skills the virtual lab showed no significant difference in overall scores on the assessments, but that an individual item related to the physical set-up of a battery showed better scores for the hands-on labs over the virtual labs. Further research should be done to determine if these results are similar in other settings with the use of different virtual labs and how the virtual labs compare to other laboratories using different learning styles and learning goals. One often cited purpose of laboratory experiences in the context of preparing chemists is to simulate the experiences common in chemical research so graduate experience in a research laboratory was a necessary part of my education in the field of laboratory instruction. This research experience provided me the opportunity, to complete an organic synthesis of aurones using a deep eutectic solvent. These solvents show unique properties that make them a viable alternative to ionic liquids. Aurones are a unique biological product in many plants and preliminary research has shown that these chemicals could be viable drug candidates. The use of the deep eutectic solvent provides a green and inexpensive way to make large numbers of different aurones quickly. In this dissertation, we show the synthesis of 12 different aurones using this method.

Hawkins, Ian C.

20

Preparation of chlorocholine chloride/urea deep eutectic solvent-modified silica and an examination of the ion exchange properties of modified silica as a Lewis adduct.  

PubMed

Chlorocholine chloride/urea (ClChCl-urea), a deep eutectic solvent (DES), was applied successfully to the modification of silica. The resulting modified silica was characterized by Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, and elemental analysis. Based on the ClChCl-urea modification of silica, the ClChCl-urea-modified silica is a Lewis adduct with ion exchange properties, and ferulic acid was adsorbed on the ClChCl-urea-modified silica via an ion exchange process. The adsorbed percentage of ferulic acid increased with the increasing amount of modified silica, and a high adsorbed percentage of 89 % could be obtained by the ion exchange process. The Freundlich isotherm used to describe the adsorption of ferulic acid on the modified silica by ion exchange showed a good correlation (R (2)?=?0.93). Based on the characterization of the structure and the analysis of the ion exchange property of the ClChCl-urea-modified silica, the modified silica as a potential medium can be applied in some analytical technologies such as solid phase extraction, chromatography, and so on. PMID:24748453

Tang, Baokun; Park, Ha Eun; Row, Kyung Ho

2014-07-01

21

Tuning the gallium content of metal precursors for Cu(In,Ga)Se2 thin film solar cells by electrodeposition from a deep eutectic solvent.  

PubMed

Controlling the Ga incorporation of Cu-In-Ga metal precursors for Cu(In,Ga)Se2 (CIGS) solar cells is one of the main challenges for low cost electrodeposition processes, mainly due to the difficulty in electrodepositing metallic Ga from aqueous electrolytes. In this work we use the deep eutectic solvent (DES) Choline Chloride?:?Urea (ChCl?:?U - 1?:?2) to efficiently codeposit In-Ga on Cu and Mo electrodes. We control the Ga/(Ga+In) (Ga/III) ratio of the films via the mass fluxes. The electrochemical behavior of ChCl?:?U containing GaCl3 and InCl3 is studied by rotating disk electrode cyclic voltammetry (CV) on Mo and Cu electrodes. CV revealed on both Mo and Cu electrodes that the electrochemical behavior of the ChCl?:?U-GaCl3-InCl3 system is the superposition of the individual In and Ga electrochemistry. On a Cu electrode the morphology, crystal structure and element distribution of the deposits were a function of the Ga/III ratio. We demonstrate the precise control of Ga incorporation over a large composition range from 0.1 ? Ga/III ? 0.9 and proved that ED from DES is a straightforward, robust and efficient process. First solar cells based on Mo/Cu/In-Ga metal stacks achieved efficiencies as high as 7.9% with a Voc of 520 mV. PMID:24382400

Malaquias, João C; Regesch, David; Dale, Phillip J; Steichen, Marc

2014-02-14

22

Synthesis of monoclinic structured BiVO4 spindly microtubes in deep eutectic solvent and their application for dye degradation.  

PubMed

Monoclinic structured spindly bismuth vanadate microtubes were fabricated on a large scale by a simple ionothermal treatment in the environment-friendly green solvent of urea/choline chloride. The as-prepared samples were characterized by XRD, SEM, TEM, IR and their photocatalytic activity was evaluated by photocatalytic decolorization of rhodamine B aqueous solution under visible-light irradiation. As-obtained BiVO(4) microtubes exhibit the spindly shape with a side length of ca. 800 nm and a wall thickness of ca. 100 nm. The opening of these microtubes presents a saw-toothed structure, which is seldom in other tube-shaped materials. The formation mechanism of the spindly microtubes is ascribed to the complex cooperation of the reaction-crystallization process controlled by BiOCl and the nucleation-growth process of nanosheets induced by solvent molecules attached on the surface of microtubes. Such spindly microtubes exhibit much higher visible-light photocatalytic activity than that of bulk BiVO(4) prepared by solid-state reaction, possibly resulting from their large surface area and improved crystallinity. PMID:20576353

Liu, Wei; Yu, Yaqin; Cao, Lixin; Su, Ge; Liu, Xiaoyun; Zhang, Lan; Wang, Yonggang

2010-09-15

23

Deep Metastable Eutectic Nanometer-Scale Particles in the MgO-Al2O3-SiO2 System  

NASA Technical Reports Server (NTRS)

Laboratory vapor phase condensation experiments systematically yield amorphous, homogeneous, nanoparticles with unique deep metastable eutectic compositions. They formed during the nucleation stage in rapidly cooling vapor systems. These nanoparticles evidence the complexity of the nucleation stage. Similar complex behavior may occur during the nucleation stage in quenched-melt laboratory experiments. Because of the bulk size of the quenched system many of such deep metastable eutectic nanodomains will anneal and adjust to local equilibrium but some will persist metastably depending on the time-temperature regime and melt/glass transformation.

Reitmeijer, Frans J. M.; Nash, J. A., III

2011-01-01

24

Fast fluctuations in deep eutectic melts: Multi-probe fluorescence measurements and all-atom molecular dynamics simulation study  

NASA Astrophysics Data System (ADS)

Larger excitation wavelength dependence of fluorescence emission of chromophores with shorter lifetime suggests fast environmental fluctuations in (CH3CONH2 + LiBr/NO3) deep eutectics. Stronger fractional viscosity dependence for rotation of a short-lifetime probe has been observed and ascribed to stronger sensitivity to these fast fluctuations. All-atom molecular dynamics simulations reveal stretched exponential relaxation for the wavenumber dependent incoherent and coherent scattering functions for acetamide with dominating sub-hundred picosecond and sub-nanosecond timescales. These simulated results provide support to the experimentally observed different fractional viscosity dependence of rotation rates for probes with different lifetimes, and stronger decoupling for short-lifetime probes in these melts.

Das, Anuradha; Das, Suman; Biswas, Ranjit

2013-08-01

25

Self-assembly of gold nanoparticles on deep eutectic solvent (DES) surfaces.  

PubMed

Self-assembly of gold nanoparticles was obtained by sputter deposition on DES. SAXS and TEM investigations reveal the formation of spherical nanoparticles with a mean diameter of 5 ± 0.5 nm. For extended sputtering times, the number density of AuNPs increases linearly and a very pronounced 1st and 2nd shell ordering is observed. PMID:24957797

Raghuwanshi, V S; Ochmann, M; Polzer, F; Hoell, A; Rademann, K

2014-08-14

26

Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity  

NASA Astrophysics Data System (ADS)

Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH2 + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH2) considered are acetamide (CH3CONH2), propionamide (CH3CH2CONH2), and butyramide (CH3CH2CH2CONH2); the electrolytes (LiX) are lithium perchlorate (LiClO4), lithium bromide (LiBr), and lithium nitrate (LiNO3). Differential scanning calorimetric measurements reveal glass transition temperatures (Tg) of these DEs are ˜195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady state fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ˜100-150 K above their individual Tgs. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH3CONH2 + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in terms of temporal heterogeneity and amide clustering in these multi-component melts.

Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit

2014-03-01

27

High-performance dye-sensitized solar cells based on solvent-free electrolytes produced from eutectic melts  

Microsoft Academic Search

Low-cost excitonic solar cells based on organic optoelectronic materials are receiving an ever-increasing amount of attention as potential alternatives to traditional inorganic photovoltaic devices. In this rapidly developing field, the dye-sensitized solar cell (DSC) has achieved so far the highest validated efficiency of 11.1% (ref. 2) and remarkable stability. However, the cells with the best performance use volatile solvents in

Yu Bai; Yiming Cao; Jing Zhang; Mingkui Wang; Renzhi Li; Peng Wang; Shaik M. Zakeeruddin; Michael Grätzel

2008-01-01

28

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

29

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

30

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

31

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

32

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

33

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

34

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

35

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

36

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

37

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

38

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.

39

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

40

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

41

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

42

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

43

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

44

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

45

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

46

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

47

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

48

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

49

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

50

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

51

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

52

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

53

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

54

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

55

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

56

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

57

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

58

Solvent immersion imprint lithography.  

PubMed

We present Solvent Immersion Imprint Lithography (SIIL), a technique for polymer functionalization and microsystem prototyping. SIIL is based on polymer immersion in commonly available solvents. This was experimentally and computationally analyzed, uniquely enabling two practical aspects. The first is imprinting and bonding deep features that span the 1 to 100 ?m range, which are unattainable with existing solvent-based methods. The second is a functionalization scheme characterized by a well-controlled, 3D distribution of chemical moieties. SIIL is validated by developing microfluidics with embedded 3D oxygen sensors and microbioreactors for quantitative metabolic studies of a thermophile anaerobe microbial culture. Polystyrene (PS) was employed in the aforementioned applications; however all soluble polymers - including inorganic ones - can be employed with SIIL under no instrumentation requirements and typical processing times of less than two minutes. PMID:24789571

Vasdekis, A E; Wilkins, M J; Grate, J W; Kelly, R T; Konopka, A E; Xantheas, S S; Chang, T-M

2014-06-21

59

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

60

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

61

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

62

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

63

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

64

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

65

Deep Desulfurization of Diesel Fuels with Plasma/Air as Oxidizing Medium, Diperiodatocuprate (III) as Catalyzer and Ionic Liquid as Extraction Solvent  

NASA Astrophysics Data System (ADS)

In this paper, the oxidative desulfurization (ODS) system is directly applied to deal with the catalytic oxidation of sulfur compounds of sulfur-containing model oil by dielectric barrier discharge (DBD) plasma in the presence of air plus an extraction step with the oxidation-treated fuel put over ionic liquid [BMIM]FeCl4 (1-butyl-3-methylimidazolium tetrachloroferrate). This new system exhibited an excellent desulfurization effect. The sulfur content of DBT in diesel oil decreased from 200 ppm to 4.92 ppm (S removal rate up to 97.5%) under the following optimal reaction conditions: air flow rate (?) of 60 mL/min, amplitude of applied voltage (U) on DBD of 16 kV, input frequency (f) of 79 kHz, catalyst amount (?) of 1.25 wt%, reaction time (t) of 10 min. Moreover, a high desulfurization rate was obtained during oxidation of benzothiophene (BT) or 4,6-DMDBT (4,6-dimethyl-dibenzothiophene) under the aforementioned conditions. The oxidation reactivity of different S compounds was decreased in the order of DBT, 4,6-DMDBT and BT. The remarkable advantage of the novel ODS system is that the desulfurization condition applies in the presence of air at ambient conditions without peroxides, aqueous solvent or biphasic oil-aqueous solution system.

Ban, Lili; Liu, Ping; Ma, Cunhua; Dai, Bin

2013-12-01

66

Solvent recovery  

Microsoft Academic Search

A brief overview is presented of the economic significance of solvent recovery in the oilseed extraction industry in view\\u000a of the steep price advance of hexane since 1974. The present solvent recovery practices in oilseed plants are outlined with\\u000a addition of operating techniques since 1976. Also, industry trends are noted in terms of improved equipment. Information is\\u000a presented on the

N. W. Myers

1983-01-01

67

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

68

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

69

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

70

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

71

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

72

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

73

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

74

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

75

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

76

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

77

Polymer thermophoresis in solvents and solvent mixtures  

Microsoft Academic Search

The thermophoresis of homopolymer chains dissolved in a pure non-electrolyte solvent or solvent mixture is theoretically examined. Thermophoresis is related to the temperature-dependent pressure gradient in the solvent layer surrounding the monomer units (mers). The gradient is produced by small changes in the solvent or solvent mixture density due to the mer-solvent interaction. The London-van der Waals interaction was considered

Martin E. Schimpf; Semen N. Semenov

2003-01-01

78

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

79

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

80

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

81

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

82

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

83

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

84

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

85

Effect of deep cryogenic treatment on microstructure, creep and wear behaviors of AZ91 magnesium alloy  

Microsoft Academic Search

This paper focuses on the effect of deep cryogenic treatment (?196°C) on microstructure and mechanical properties of AZ91 magnesium alloy. The execution of deep cryogenic treatment on samples changed the distribution of ? precipitates. The tiny laminar ? particles almost dissolved in the microstructure and the coarse divorced eutectic ? phase penetrated into the matrix. This microstructural modification resulted in

Kaveh Meshinchi Asl; Alireza Tari; Farzad Khomamizadeh

2009-01-01

86

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

87

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

88

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

89

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

90

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

91

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

92

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

93

Study of solute–solvent and solvent–solvent interactions in pure and mixed binary solvents  

Microsoft Academic Search

Solute–solvent and solvent–solvent interactions have been studied in fifteen pure solvents and seven binary aqueous mixtures by monitoring the solubility of a dye in the solvents. The standard Gibbs energy of solvation, as given by log s, where s is the solubility has been found to depend on various modes of solute–solvent interaction and also on the Hildebrand solubility parameter

Angshuman Maitra; Sanjib Bagchi

2008-01-01

94

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

95

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

96

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

97

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

98

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

99

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

100

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

101

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

102

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

103

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

104

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

105

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

106

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

107

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

108

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

109

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

110

Degreaser Reduces Solvent Loss  

NASA Technical Reports Server (NTRS)

Escape of solvent minimized by second cooling coil. Degreaser suppresses solvent-vapor loss through parts-basket dragout and air drafts. Within C02 blanket, convection repeatedly exposes C02/solvent mixture to cold spot created by C02 coil. Solvent vapor condenses, then runs down via through to cold tank. This small expenditure of C02 minimizes health and environmental hazards.

Du Fresne, E. R.

1985-01-01

111

How Deep Is Deep?  

NSDL National Science Digital Library

This interactive online tool helps students grasp just how deep scientists must dive to study deep sea vents. By providing points of comparison, it puts the nearly unfathomable depth of the ocean floor into perspective. It compares the scale of a 2,400-meter (7,874-foot) dive against the height of famous landmarks such as the Empire State Building, the Eiffel Tower, and the Space Needle. Students can also enter the height, in feet or meters, of any landmark they chose to gain additional perspective.

112

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

113

Solvent wash solution  

DOEpatents

Process for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 volume percent of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.

Neace, James C. (Blackville, SC) [Blackville, SC

1986-01-01

114

Solvent wash solution  

DOEpatents

A process is claimed for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 vol % of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.

Neace, J.C.

1984-03-13

115

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

116

Substrate Injection Treatment for a Chlorinated Solvent Groundwater Source Area  

Microsoft Academic Search

An industrial facility was found to have contamination from chlorinated solvents in surface, shallow and deep groundwater systems in the early 1990s, with perchlorate found in 2001. In situ anaerobic bioremediation pilot tests were implemented beginning in August 2002 to address both the residual chlorinated solvents (primarily tetrachloroethene) and perchlorate in soil and shallow groundwater simultaneously at and adjacent to

Kevin A. Morris; William Smith

117

Miscellaneous hydrocarbon solvents.  

PubMed

The solvents discussed in this article are common solvents not categorized as halogenated, aromatic, or botanical. The solvents discussed are categorized into two groups: hydrocarbon mixtures and single agents. The hydrocarbon mixtures discussed are Stoddard solvent, naphtha, and kerosene. The remaining solvents described are n-hexane, methyl n-butyl ketone, dimethylformamide, dimethyl sulfoxide, and butyl mercaptans. Effects common to this group of agents and their unique effects are characterized. Treatment of exposures and toxic effects of these solvents is described, and physiochemical properties and occupational exposure levels are listed. PMID:15325316

Bebarta, Vikhyat; DeWitt, Christopher

2004-08-01

118

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

119

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

120

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

121

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

122

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

123

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

124

Peat dewatering: solvent extraction  

SciTech Connect

The objective of this program is to determine the preliminary technical and economic feasibility of using IGT's solvent-extraction process for the dewatering of peat. Parallel objectives of the program are to: identify organic solvents that can be readily used to dewater raw peat by IGT's solvent-extraction process; design, construct, and operate bench-scale equipment for testing the most promising solvents; and estimate the preliminary economics of the process for a commerical-scale peat dewatering plant using a selective solvent. The results indicate that: solvent-extraction dewatering can remove up to 90% of the water in peat; and diethyl ketone (DEK) and benzene appear to dewater peat better than the other solvents tested. A preliminary economic evaluation of solvent-extraction dewatering of peat with DEK shows that the cost of this type of dewatering method is not currently competitive with other peat dewatering methods. (DWC)

Paganessi, J.E.; Mensinger, M.C.; Tsaros, C.L.; Arora, J.

1981-01-01

125

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

126

Solvents safety handbook  

SciTech Connect

Know solvents and how to protect yourself from dangerous exposure to them. Instant information for decision-making regarding industrial solvents in everyday use, is provided in this handbook which is a compilation of data on 335 hazardous and frequently-used solvents.

De Renzo, D.J.

1986-01-01

127

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

128

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

129

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

130

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

131

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

132

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

133

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 produce Ca 6Pt 3Zn 5, with an orthorhombic structure related to that of W 3CoB 3 ( Pmmn, a=13.7339(9) Å, b=4.3907(3) Å, c=10.7894(7) Å).

Stojanovic, Milorad; Latturner, Susan E.

2007-03-01

134

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

135

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

136

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

137

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

138

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

139

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

140

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

141

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

142

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

143

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

144

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

145

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

146

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

147

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

148

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

149

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

150

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

151

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

152

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

153

Alternative Green Solvents Project  

NASA Technical Reports Server (NTRS)

Necessary for safe and proper functioning of equipment. Mainly halogenated solvents. Tetrachloride, Trichloroethylene (TCE), CFC-113. No longer used due to regulatory/safety concerns. Precision Cleaning at KSC: Small % of total parts. Used for liquid oxygen (LOX) systems. Dual solvent process. Vertrel MCA (decafluoropentane (DFP) and trons-dichloroethylene) HFE-7100. DFP has long term environmental concerns. Project Goals: a) Identify potential replacements. b) 22 wet chemical processes. c) 3 alternative processes. d) Develop test procedures. e) Contamination and cleaning. f) Analysis. g) Use results to recommend alternative processes. Conclusions: a) No alternative matched Vertrel in this study. b) No clear second place solvent. c) Hydrocarbons- easy; Fluorinated greases- difficult. d) Fluorinated component may be needed in replacement solvent. e) Process may need to make up for shortcoming of the solvent. f) Plasma and SCC02 warrant further testing.

Maloney, Phillip R.

2012-01-01

154

Deep Habits  

Microsoft Academic Search

This paper generalizes the standard habit-formation model to an environment in which agents form habits over individual varieties of goods as opposed to over a composite consumption good. We refer to this preference specification as deep habit formation. Under deep habits, the demand function faced by individual producers depends on past sales. This feature is typically assumed ad hoc in

MORTEN RAVN; STEPHANIE SCHMITT-GROHÉ; Mart ´ in Uribe

2006-01-01

155

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

156

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

157

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

158

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

159

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

160

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

161

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

162

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

163

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

164

SOLVENT WASTE REDUCTION ALTERNATIVES  

EPA Science Inventory

This publication contains edited versions of presentations on this subject made at five Technology Transfer seminars in 1988. Chapters are included on land disposal regulations and requirements; waste solvent disposal alternatives from various industries such as process equipment...

165

Continuous countercurrent membrane column for the separation of solute/solvent and solvent/solvent systems  

DOEpatents

A reverse osmosis membrane process or hybrid membrane - complementary separator process for producing enriched product or waste streams from concentrated and dilute feed streams for both solvent/solvent and solute/solvent systems is described.

Nerad, Bruce A. (Longmont, CO); Krantz, William B. (Boulder, CO)

1988-01-01

166

Continuous countercurrent membrane column for the separation of solute\\/solvent and solvent\\/solvent systems  

Microsoft Academic Search

A reverse osmosis membrane process or hybrid membrane - complementary separator process for producing enriched product or waste streams from concentrated and dilute feed streams for both solvent\\/solvent and solute\\/solvent systems is described.

Bruce A. Nerad; William B. Krantz

1988-01-01

167

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

168

Cleaning without chlorinated solvents  

SciTech Connect

Because of health and environmental concerns, many regulations have been passed in recent years regarding the use of chlorinated solvents. The Oak Ridge Y-12 Plant has had an active program to find alternatives for these solvents used in cleaning applications for the past 7 years. During this time frame, the quantity of solvents purchased has been reduced by 92%. The program has been a twofold effort. Vapor degreasers used in batch cleaning-operations have been replaced by ultrasonic cleaning with aqueous detergent, and other organic solvents have been identified for use in hand-wiping or specialty operations. In order to qualify these alternatives for use, experimentation was conducted on cleaning ability as well as effects on subsequent operations such as welding, painting and bonding. Cleaning ability was determined using techniques such as X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) which are capable of examining monolayer levels of contamination on a surface. Solvents have been identified for removal of rust preventative oils, lapping oils, machining coolants, lubricants, greases, and mold releases. Solvents have also been evaluated for cleaning urethane foam spray guns, swelling of urethanes and swelling of epoxies.

Thompson, L.M.; Simandl, R.F.

1994-12-31

169

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

170

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

171

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

172

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

173

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

174

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

175

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

176

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

177

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

178

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

179

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

180

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

181

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

182

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

183

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

184

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

185

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

186

Deep earthquakes  

SciTech Connect

Earthquakes are often recorded at depths as great as 650 kilometers or more. These deep events mark regions where plates of the earth's surface are consumed in the mantle. But the earthquakes themselves present a conundrum: the high pressures and temperatures at such depths should keep rock from fracturing suddenly and generating a tremor. This paper reviews the research on this problem. Almost all deep earthquakes conform to the pattern described by Wadati, namely, they generally occur at the edge of a deep ocean and define an inclined zone extending from near the surface to a depth of 600 kilometers of more, known as the Wadati-Benioff zone. Several scenarios are described that were proposed to explain the fracturing and slipping of rocks at this depth.

Frohlich, C.

1989-01-01

187

Safe battery solvents  

DOEpatents

An ion transporting solvent maintains very low vapor pressure, contains flame retarding elements, and is nontoxic. The solvent in combination with common battery electrolyte salts can be used to replace the current carbonate electrolyte solution, creating a safer battery. It can also be used in combination with polymer gels or solid polymer electrolytes to produce polymer batteries with enhanced conductivity characteristics. The solvents may comprise a class of cyclic and acyclic low molecular weight phosphazenes compounds, comprising repeating phosphorus and nitrogen units forming a core backbone and ion-carrying pendent groups bound to the phosphorus. In preferred embodiments, the cyclic phosphazene comprises at least 3 phosphorus and nitrogen units, and the pendent groups are polyethers, polythioethers, polyether/polythioethers or any combination thereof, and/or other groups preferably comprising other atoms from Group 6B of the periodic table of elements.

Harrup, Mason K. (Idaho Falls, ID); Delmastro, Joseph R. (Idaho Falls, ID); Stewart, Frederick F. (Idaho Falls, ID); Luther, Thomas A. (Idaho Falls, ID)

2007-10-23

188

Halogenated solvent remediation  

DOEpatents

Methods for enhancing bioremediation of ground water contaminated with nonaqueous halogenated solvents are disclosed. An illustrative method includes adding an electron donor for microbe-mediated anaerobic reductive dehalogenation of the halogenated solvents, which electron donor enhances mass transfer of the halogenated solvents from residual source areas into the aqueous phase of the ground water. Illustrative electron donors include C.sub.2-C.sub.4 carboxylic acids and hydroxy acids, salts thereof, esters of C.sub.2-C.sub.4 carboxylic acids and hydroxy acids, and mixtures thereof, of which lactic acid, salts of lactic acid--such as sodium lactate, lactate esters, and mixtures thereof are particularly illustrative. The microbes are either indigenous to the ground water, or such microbes can be added to the ground water in addition to the electron donor.

Sorenson, Jr., Kent S. (Windsor, CO)

2008-11-11

189

Solvent resistant copolyimide  

NASA Technical Reports Server (NTRS)

A solvent resistant copolyimide was prepared by reacting 4,4'-oxydiphthalic anhydride with a diaimine blend comprising, based on the total amount of the diamine blend, about 75 to 90 mole percent of 3,4'-oxydianiline and about 10 to 25 mole percent p-phenylene diamine. The solvent resistant copolyimide had a higher glass transition temperature when cured at 350.degree. , 371.degree. and 400.degree. C. than LaRC.TM.-IA. The composite prepared from the copolyimide had similar mechanical properties to LaRC.TM.-IA. Films prepared from the copolyimide were resistant to immediate breakage when exposed to solvents such as dimethylacetamide and chloroform. The adhesive properties of the copolyimide were maintained even after testing at 23.degree., 150.degree., 177.degree. and 204.degree. C.

Chang, Alice C. (Inventor); St. Clair, Terry L. (Inventor)

1995-01-01

190

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

191

Deep Time  

NSDL National Science Digital Library

In this video a Penn State professor refers to National Park canyons carved out by water and wind as he explains “deep time” - the notion that the earth is billions of years old; another professor states how the theory of evolution is supported by evidence of an ancient Earth recorded in rocks.

Wpsu

2010-05-04

192

Deep gas  

SciTech Connect

Deep gas research emphasizes studies of natural gas in subduction emplaced sediments and in deep sedimentary basins. Deep gas research in subduction-emplaced sediments is based on the hypothesis that natural gas is generated in sediments carried to great depths at convergent plate boundaries in the Earth's crust. Many areas of North America are believed to have experienced plate tectonic convergence. The specific area of interest in this province encompasses approximately 1.5 million square miles of the western US (including Alaska) and Canada; other portions of this same province extend southward into Mexico and Central and South America. For subduction-emplaced sediments, ongoing research consists of basic studies of hydrocarbon generation, stability, and preservation at depths in excess of 15,000 feet, and a comprehensive evaluation of the geologic structures, stratigraphy, and geochemistry of the above region. Results to date include: geologic and geophysical evidence of deeply emplaced sedimentary rock units at depths exceeding 30,000 feet in western Washington and south-central Alaska, and high-resolution seismic-reflection verification of structures defined by reconnaissance, magnetotelluric geophysical techniques in western Washington; a new methodology for verifying deep methane stability with fluid inclusion studies; and a preliminary gas resource estimate of 3000 trillion cubic feet (Tcf). 1 ref., 9 figs., 4 tabs.

Gwilliam, W.J.

1990-06-01

193

Deep Lysimeter  

DOEpatents

A deep lysimeter including a hollow vessel having a chamber, a fill conduit extending into the chamber through apertures, a semi-permeable member mounted on the vessel and in fluid communication with the fill conduit, and a line connection for retrieving the lysimeter.

Hubbell, Joel M. (Idaho Falls, ID); Sisson, James B. (Idaho Falls, ID)

2004-06-01

194

ENGINEERING BULLETIN: SOLVENT EXTRACTION  

EPA Science Inventory

Solvent extraction does not destroy hazardous contaminants, but is a means of separating those contaminants from soils, sludges, and sediments, thereby reducing the volume of the hazardous material that must be treated. enerally it is used as one in a series of unit operations an...

195

ONSITE SOLVENT RECOVERY  

EPA Science Inventory

This study evaluated the product quality, waste reduction/pollution prevention, and economic aspects of three technologies for onsite solvent recovery. The technologies were (1) atmospheric batch distillation, (2) vacuum heat-pump distillation, and (3) low-emission vapor degreas...

196

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

197

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

198

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

199

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

200

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

201

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

202

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

203

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

204

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

205

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

206

PARIS II: DESIGNING GREENER SOLVENTS  

EPA Science Inventory

PARIS II (the program for assisting the replacement of industrial solvents, version II), developed at the USEPA, is a unique software tool that can be used for customizing the design of replacement solvents and for the formulation of new solvents. This program helps users avoid ...

207

Deep Vein Thrombosis  

MedlinePLUS

Deep vein thrombosis, or DVT, is a blood clot that forms in a vein deep in the body. Most deep vein ... the condition is called thrombophlebitis. A deep vein thrombosis can break loose and cause a serious problem ...

208

Hazardous solvent substitution  

SciTech Connect

Eliminating hazardous solvents is good for the environment, worker safety, and the bottom line. However, even though we are motivated to find replacements, the big question is `What can we use as replacements for hazardous solvents?`You, too, can find replacements for your hazardous solvents. All you have to do is search for them. Search through the vendor literature of hundreds of companies with thousands of products. Ponder the associated material safety data sheets, assuming of course that you can obtain them and, having obtained them, that you can read them. You will want to search the trade magazines and other sources for product reviews. You will want to talk to users about how well the product actually works. You may also want to check US Environmental Protection Agency (EPA) and other government reports for toxicity and other safety information. And, of course, you will want to compare the product`s constituent chemicals with the many hazardous constituency lists to ensure the safe and legal use of the product in your workplace.

Twitchell, K.E.

1995-11-01

209

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

210

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

211

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

212

Effects of solute-solvent and solvent-solvent attractive interactions on solute diffusion  

Microsoft Academic Search

A study is reported on the diffusion process of a solute molecule in a Lennard-Jones-like liquid near the triple point by a molecular dynamics simulation. Systematic changes were made to the strength of the solute-solvent or solvent-solvent attractive interaction in order to elucidate its effects on the diffusion coefficient. When the solute-solvent attractive interaction is enhanced, the diffusion coefficient of

T. Yamaguchi; Y. Kimura

2000-01-01

213

Analysis of Solvent–Solvent Interactions in Mixed Isosteric Solvents by Inverse Gas Chromatography  

Microsoft Academic Search

The Flory–Huggins interaction parameter, ?\\u000a 23, characterizing the interaction between solvents in a mixed stationary phase has been calculated using inverse gas chromatography\\u000a (IGC). The ?\\u000a 23 parameters for four mixed solvent systems formed by mixing a non-polar branched alkane, 19, 24-dioctadecyldotetracontane\\u000a (C78), with four different polar solvents are analysed as a function of temperature. Two of the polar solvents

T. V. M. Sreekanth; K. S. Reddy

2007-01-01

214

SOLVENT FIRE BY-PRODUCTS  

SciTech Connect

Southwest Research Institute (SwRI) conducted a burn test of the Caustic-Side Solvent Extraction (CSSX) solvent to determine the combustion products. The testing showed hydrogen fluoride gas is not a combustion product from a solvent fire when up to 70% of the solvent is consumed. The absence of HF in the combustion gases may reflect concentration of the modifier containing the fluoride groups in the unburned portion. SwRI reported results for other gases (CO, HCN, NOx, formaldehyde, and hydrocarbons). The results, with other supporting information, can be used for evaluating the consequences of a facility fire involving the CSSX solvent inventory.

Walker, D; Samuel Fink, S

2006-05-22

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

Deep smarts.  

PubMed

When a person sizes up a complex situation and rapidly comes to a decision that proves to be not just good but brilliant, you think, "That was smart." After you watch him do this a few times, you realize you're in the presence of something special. It's not raw brainpower, though that helps. It's not emotional intelligence, either, though that, too, is often involved. It's deep smarts. Deep smarts are not philosophical--they're not"wisdom" in that sense, but they're as close to wisdom as business gets. You see them in the manager who understands when and how to move into a new international market, in the executive who knows just what kind of talk to give when her organization is in crisis, in the technician who can track a product failure back to an interaction between independently produced elements. These are people whose knowledge would be hard to purchase on the open market. Their insight is based on know-how more than on know-what; it comprises a system view as well as expertise in individual areas. Because deep smarts are experienced based and often context specific, they can't be produced overnight or readily imported into an organization. It takes years for an individual to develop them--and no time at all for an organization to lose them when a valued veteran walks out the door. They can be taught, however, with the right techniques. Drawing on their forthcoming book Deep Smarts, Dorothy Leonard and Walter Swap say the best way to transfer such expertise to novices--and, on a larger scale, to make individual knowledge institutional--isn't through PowerPoint slides, a Web site of best practices, online training, project reports, or lectures. Rather, the sage needs to teach the neophyte individually how to draw wisdom from experience. Companies have to be willing to dedicate time and effort to such extensive training, but the investment more than pays for itself. PMID:15449858

Leonard, Dorothy; Swap, Walter

2004-09-01

217

Deep Time  

NSDL National Science Digital Library

Earth has been significantly altered over its 4.6 billion year history by climate swings, volcanism, and drifting continents. These dynamic conditions, in turn, have influenced every living thing that has inhabited the planet. This interactive timeline discusses the concept of deep time, and allows users to learn about geological events, evolutionary transformations, and the extinction of species or whole families of organisms that once inhabited the planet, and to better appreciate the vast period of time over which these transformations have occurred. A background essay and discussion questions are included.

218

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

219

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

220

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

221

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

222

Production of low-density poly (4-methyl-1-pentene) foam via phase inversion from binary solvent/nonsovent systems  

SciTech Connect

Phase inversion from durene/naphthalene, durene/tmpdo, and durene/hexadecanol binary solvent/nonsolvent systems produced well interconnected, radiographically homogeneous, open-celled poly (4- methyl-1-pentene) or pmp foams. These foams ranged in density from 5 to 50 mg/cm{sup 2}. Foam homogeneity and casting efficiency were dependent on casting scheme, durene quality, solvent-to-nonsolvent ratio, and quench temperature. Foam density tracked linearly with dissolved-polymer content. Homogeneous, ultralow-density (5 to 6 mg/cm{sup 3}) foams were produced by using a 49/51 durene/naphthalene solvent eutectic. Foam hardness or firmness tracked somewhat linearly with foam density. Foams with densities above 20 mg/cm{sup 3} were too fragile to handle without damage.

Simandl, R.F.; Robinson, D.N.; Bolinger, W.L.; Davis, W.E.

1991-11-01

223

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

224

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

225

(Electrochemistry in nonaqueous solvents)  

SciTech Connect

The traveler attended the XXVI International Conference on Coordination Chemistry and presented some work entitled An Investigation of the Perchlorate Complexation of Europium(III) in Benzonitrile and Dimethylsulphoxide Using an Ion Exchange Technique.'' Papers of particular interest concerned electrochemistry in nonaqueous solvents (in particular, using electrodes of submicron dimensions that could be applicable to the later actinides); Raman spectroscopy as applied to coordination chemistry, and solution chemistry in nonaqueous solvents with emphasis on identifying the species in solution. The traveler also attended the XIII International Conference on Organometallic Chemistry in Turin, Italy and presented work entitled Synthesis and Characterization of Some Divalent and Trivalent Samarium Organometallic Complexes.'' Papers of particular interest were given in a complete session on organometallic chemistry of the f-elements. Other papers useful to our work concerned d-transition metals where phosphine, arsine, and stibine ligands were used (in order to compare and contrast the behavior with the work we have done on this type of ligand with europium) and phosphide and sulphur bridged type species applicable to both d-transition and f-transition metals.

Payne, G.F.

1988-01-01

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

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

228

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

229

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

230

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

231

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

232

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

233

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

234

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

235

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

236

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

237

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

238

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

239

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

240

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

241

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

242

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

243

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

244

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

245

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

246

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

247

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

248

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

249

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

250

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

251

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

252

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

253

Solvent Blending Strategy to Upgrade MCU CSSX Solvent to Equivalent Next-Generation CSSX Solvent  

SciTech Connect

The results of the present study have validated an equal-volume blending strategy for upgrading freshly prepared CSSX solvent to a blended solvent functionally equivalent to NG-CSSX solvent. It is shown that blending fresh CSSX solvent as currently used in MCU with an equal volume of an NG-CSSX solvent concentrate of appropriate composition yields a blended solvent composition (46.5 mM of MaxCalix, 3.5 mM of BOBCalixC6, 0.5 M of Cs-7SB, 3 mM of guanidine suppressor, and 1.5 mM of TOA in Isopar L) that exhibits equivalent batch ESS performance to that of the NG-CSSX solvent containing 50 mM of MaxCalix, 0.5 M of Cs-7SB, and 3 mM of guanidine suppressor in Isopar L. The solvent blend composition is robust to third-phase formation. Results also show that a blend containing up to 60% v/v of CSSX solvent could be accommodated with minimal risk. Extraction and density data for the effect of solvent concentration mimicking diluent evaporation or over-dilution of the equal-volume blended solvent are also given, providing input for setting operational limits. Given that the experiments employed all pristine chemicals, the results do not qualify a blended solvent starting with actual used MCU solvent, which can be expected to have undergone some degree of degradation. Consequently, further work should be considered to evaluate this risk and implement appropriate remediation if needed.

Delmau, Laetitia Helene [ORNL; Moyer, Bruce A [ORNL

2012-12-01

254

Method for extraction solvent recovery  

SciTech Connect

A method for recovery of extraction solvent from a dissolved solute wherein halogen gas evolution and halogen compound retention in the solute are minimized comprises heating a solution of a halogenated organic solvent and the extracted solute in the presence of an ammonium, Group I metal or Group II metal salt of an acid of carbon number 1 to 6, such as ammonium bicarbonate, ammonium carbonate, ammonium formate, sodium carbonate, sodium formate, or calcium formate, to recover the solvent and the solute.

Wolff, W. F.

1985-10-22

255

Coumarin6 interaction with solvents  

NASA Astrophysics Data System (ADS)

Bonding arrangements and changes induced by chemicals in structure/bonding of laser dyes molecule can be investigated from the study of IR spectra. These changes are expected to depend upon the nature of interacting solvent. In the present study, we have studied the FTIR spectra of Coumarin6 in powder form and in different solvents in order to investigate the effect of solvents on Coumarin6 molecule by observing the changes in the spectra. This study may provide the deeper understanding of the sensing properties of Coumarin 6 and also the dependence of its fluorescence and, therefore, lasing property on solvents.

Sharma, Amit

2013-06-01

256

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

257

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

258

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

259

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

260

Deep Impact  

NSDL National Science Digital Library

Comets have fascinated humans for hundreds of years, and most recently with the idea of creating a "deep impact" upon a comet in order to study the interior composition and makeup of these bodies. With this scientific mission in mind, a team of researchers (including participants from NASA's Jet Propulsion Laboratory and the University of Maryland) will send an impactor spacecraft into the Comet Tempel 1 on July 4th, 2005. The data collected from this fascinating experiment will help answer many questions about comets, and should be of interest to research scientists and the general public alike. The site itself contains quite a few helpful sections, including one dedicated to explaining the science behind studying comets. A technology section offers detailed explanations behind much of the flight system, the launch vehicle, and the various instruments on board. The gallery section has some nice animations that show how the mission will encounter and impact Comet Tempel 1. Overall, this is very engaging and well thought out site that explains this mission in jargon-free language.

2008-02-29

261

Femtosecond transient dichroism/birefringence studies of solute- solvent friction and solvent dynamics  

SciTech Connect

Ultrafast, heterodyne, polarization spectroscopies are used to measure solute-solvent frictional coupling and characterize the neat solvent`s relaxation dynamics on femtosecond and picosecond timescales.

Chang, Y.J.; Castner, E.W. Jr. [Brookhaven National Lab., Upton, NY (United States); Konitsky, W.; Waldeck, D.H. [Pittsburgh Univ., PA (United States). Dept. of Chemistry

1994-02-01

262

Deep brain stimulation  

MedlinePLUS

Globus pallidus deep brain stimulation; Subthalamic deep brain stimulation; Thalamic deep brain stimulation; DBS ... lead, or electrode that is placed into the brain The neurostimulator, similar to a heart pacemaker, which ...

263

Deep breathing after surgery  

MedlinePLUS

... way to do so is by doing deep breathing exercises. Deep breathing keeps your lungs well-inflated and healthy while ... uncomfortable. But if you do not practice deep breathing after surgery, you may develop lung problems, like ...

264

Deep Venous Thrombosis  

MedlinePLUS

Deep venous thrombosis is a blood clot that forms in a vein deep inside a part of the body. It mainly ... things you can do to prevent deep vein thrombosis include: Wear the pressure stockings your doctor prescribed. ...

265

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

266

Deep scientific computing requires deep data  

Microsoft Academic Search

Increasingly, scientific advances require the fusion of large amounts of complex data with extraordinary amounts of computational power. The problems of deep science demand deep computing and deep storage resources. In addition to teraflop-range computing engines with their own local storage, facilities must provide large data repositories of the order of 10-100 petabytes, and networking to allow the movement of

William T. C. Kramer; Arie Shoshani; Deborah A. Agarwal; Brent R. Draney; Guojun Jin; Gregory F. Butler; John A. Hules

2004-01-01

267

Solvent changeouts without plant shutdown  

SciTech Connect

For reasons of greater selectivity, lower regeneration energy requirements, reduced corrosivity and possible greater amine stability, MDEA continues to replace DEA in numerous selective H/sub 2/S removal applications. Solvent changeouts from DEA to MDEA often require no equipment modification, yet they are generally achieved by shutting down the plant, draining the old solvent, cleaning, and finally recharging with MDEA. However, in at least one plant, solvent changeout was done on the fly simply by periodically making up normal DEA losses with MDEA until the plant was finally operating on MDEA alone. Gradual solvent changeouts have the advantages of no lost production, no disposal problems with the environmentally-hazardous old solvent, no use and subsequent disposal of cleaning agents, and no additional manpower requirements. An advanced flowsheet simulation capability can suggest when such a procedure is feasible and, when it is, plant simulation can help to ensure that the solvent changeout is done reliably and with no production or cost penalties. GASPLANT-PLUS(TM) is currently the only commercial simulator having formulated solvent (mixed amine) capabilities within a fully flexible flowsheeting environment. After highlighting its technical foundations, they will compare GASPLANT-PLUS predictions with some commercial plant data and, through examples, they will show how solvent changeouts can be done gradually, without plant shutdown.

Vickery, D.J.; Campbell, S.W. (Taylor, Weiland and Associates, Inc., Potsdam, NY (US))

1988-01-01

268

Chemical reactivity: Inverse solvent design  

NASA Astrophysics Data System (ADS)

Choosing a solvent for a particular reaction is often a matter of personal preference or the result of limited screening. Now, a computational method allows identification of a solvent that will enhance the kinetics of a reaction prior to running a wet experiment.

Truhlar, Donald G.

2013-11-01

269

SOLV-DB: Solvents Database  

NSDL National Science Digital Library

The purpose of SOLV-DB is to help you find a wide variety of data on solvents quickly and easily, including health and safety data, chemical and physical data, regulatory responsibilities, and environmental fate information. SOLV-DB is maintained by the National Center for Manufacturing Sciences and is considered a "one-stop source for solvents data."

2008-08-27

270

Laboratory solvent reuse -- Liquid chromatography  

SciTech Connect

The objective of this work was to develop a method for reduction of waste solvent in the Process Engineering Chemistry Laboratory. The liquid chromatographs are the largest generators of explosive-contaminated waste in the laboratory. We developed a successful process for the reuse of solvents from the liquid chromatographs and demonstrated the utility of the process in the assay of hexanitrostilbene.

Quinlin, W.T.; Schaffer, C.L.

1992-11-01

271

Solvent Retention and Fibre Chemistry.  

National Technical Information Service (NTIS)

The aim of this study was to understand in which way different chemical and physical treatments affect the solvent retention properties of pulps used in the middle layer of folding boxboard. The solvent retention properties of the treated pulps were exami...

M. Rantanen

2003-01-01

272

Solvent influence on base stacking.  

PubMed Central

In this paper we present a detailed analysis of the base-stacking phenomenon in different solvents, using nanosecond molecular dynamics simulations. The investigation focuses on deoxyribo- and ribodinucleoside monophosphates in aqueous and organic solutions. Organic solvents with a low dielectric constant, such as chloroform, and solvents with intermediate dielectric constants, such as dimethyl sulfoxide and methanol, were analyzed. This was also done for water, which is highly polar and has a high dielectric constant. Structural parameters such as the sugar puckering and the base-versus-base orientations, as well as the energetics of the solute-solvent interactions, were examined in the different solvents. The obtained data demonstrate that base stacking is favored in the high dielectric aqueous solution, followed by methanol and dimethyl sulfoxide with intermediate dielectric constants, and chloroform, with a low dielectric constant.

Norberg, J; Nilsson, L

1998-01-01

273

Solvent degradation products in nuclear fuel processing solvents  

SciTech Connect

The Savannah River Plant uses a modified Purex process to recover enriched uranium and separate fission products. This process uses 7.5% tri-n-butyl phosphate (TBP) dissolved in normal paraffin hydrocarbons for the solvent extraction of a nitric acid solution containing the materials to be separated. Periodic problems in product decontamination result from solvent degradation. A study to improve process efficiency has identified certain solvent degradation products and suggested mitigation measures. Undecanoic acid, lauric acid, and tridecanoic acid were tentatively identified as diluent degradation products in recycle solvent. These long-chain organic acids affect phase separation and lead to low decontamination factors. Solid phase extraction (SPE) was used to concentrate the organic acids in solvent prior to analysis by high performance liquid chromatography (HPLC). SPE and HPLC methods were optimized in this work for analysis of decanoic acid, undecanoic acid, and lauric acid in solvent. Accelerated solvent degradation studies with 7.5% TBP in normal paraffin hydrocarbons showed that long-chain organic acids and long-chain alkyl butyl phosphoric acids are formed by reactions with nitric acid. Degradation of both tributyl phosphate and hydrocarbon can be minimized with purified normal paraffin replacing the standard grade presently used. 12 refs., 1 fig., 3 tabs.

Shook, H.E. Jr.

1988-06-01

274

COMPUTER AIDED SOLVENT DESIGN FOR THE ENVIRONMENT  

EPA Science Inventory

Solvent substitution is an effective and useful means of eliminating the use of harmful solvents, but finding substitute solvents which are less harmful and as effective as currently used solvents presents significant difficulties. Solvent substitution is a form of reverse engin...

275

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

276

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

277

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

278

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

279

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

280

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

281

EXPERIENCES IN DESIGNING SOLVENTS FOR THE ENVIRONMENT  

EPA Science Inventory

To meet the great need of replacing many harmful solvents commonly used by industry and the public with environmentally benign substitute solvents, the PARIS II solvent design software has been developed. Although the difficulty of successfully finding replacements increases with...

282

Preventing Deep Vein Thrombosis  

MedlinePLUS

What is deep vein thrombosis (DVT)? Deep vein thrombosis is a condition in which blood clots (or thrombi) form in deep veins in the legs ... and Gynecologists f AQ • What is deep vein thrombosis (DVT)? • How does a clot form in a ...

283

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

284

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

285

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

286

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

287

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

288

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

289

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

290

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

291

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

292

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

293

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

294

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

295

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

296

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

297

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

298

Caustic-Side Solvent Extraction Solvent-Composition Recommendation  

SciTech Connect

The U.S. Department of Energy has selected caustic-side solvent extraction as the preferred cesium removal technology for the treatment of high-level waste stored at the Savannah River Site. Data for the solubility of the extractant, calix[4]arene-bis(tert-octyl benzo-crown-6), acquired and reported for the Salt Processing Program down-select decision, showed the original solvent composition to be supersaturated with respect to the extractant. Although solvent samples have been observed for approximately 1 year without any solids formation, work was completed to define a new solvent composition that was thermodynamically stable with respect to solids formation and to expand the operating temperature with respect to third-phase formation. Chemical and physical data as a function of solvent component concentrations were collected. The data included calix[4]arene-bis(tert-octyl benzo-crown-6) solubility; cesium distribution ratio under extraction, scrub, and strip conditions; flow sheet robustness; temperature range of third-phase formation; dispersion numbers for the solvent against waste simulant, scrub and strip acids, and sodium hydroxide wash solutions; solvent density; viscosity; and surface and interfacial tension. These data were mapped against a set of predefined performance criteria. The composition of 0.007 M calix[4]arene-bis(tert-octyl benzo-crown-6), 0.75 M 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol, and 0.003 M tri-n-octylamine in the diluent Isopar{reg_sign} L provided the best match between the measured properties and the performance criteria. Therefore, it is recommended as the new baseline solvent composition.

Klatt, L.N.

2002-05-09

299

Solvent degradation products in nuclear fuel processing solvents  

Microsoft Academic Search

The Savannah River Plant uses a modified Purex process to recover enriched uranium and separate fission products. This process uses 7.5% tri-n-butyl phosphate (TBP) dissolved in normal paraffin hydrocarbons for the solvent extraction of a nitric acid solution containing the materials to be separated. Periodic problems in product decontamination result from solvent degradation. A study to improve process efficiency has

Shook; H. E. Jr

1988-01-01

300

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

301

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

302

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

303

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

304

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

305

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

306

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

307

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

308

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

309

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

310

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

311

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

312

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

313

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

314

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

315

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

316

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

317

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

318

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

319

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

320

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

321

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

322

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

323

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

324

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

325

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

326

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

327

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

328

SOLV-DB: Solvents Data  

DOE Data Explorer

SOLV-DB provides a specialized mix of information on commercially available solvents. The development of the database was funded under the Strategic Environmental Research and Development Program (SERDP) with funds from EPA and DOE's Office of Industrial Technologies in EE. The information includes: • Health and safety considerations involved in choosing and using solvents • Chemical and physical data affecting the suitability of a particular solvent for a wide range of potential applications • Regulatory responsibilities, including exposure and effluent limits, hazard classification status with respect to several key statutes, and selected reporting requirements • Environmental fate data, to indicate whether a solvent is likely to break down or persist in air or water, and what types of waste treatment techniques may apply to it • CAS numbers (from Chemical Abstracts Service) and Sax Numbers (from Sax, et.al., Dangerous Properties of Industrial Materials) Supplier Information See help information at http://solvdb.ncms.org/welcome.htm (Specialized Interface)

329

DOE solvent handbook information sheet.  

National Technical Information Service (NTIS)

Solvents and cleaners are used in the Department of Defense (DOD) and the Department of Energy-Defense Program (DOE-DP) maintenance facilities for removing wax, grease, oil, carbon, machining fluids, solder fluxes, mold releases, and other contaminants be...

A. A. Chavez

1992-01-01

330

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

331

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

332

Thermal conductivities of Wilsonville solvent and Wilsonville solvent\\/Illinois No. 6 coal slurry. [Wilsonville solvent  

Microsoft Academic Search

Thermal conductivities of a Wilsonville solvent and of a slurry prepared from this solvent and Illinois No. 6 coal have been measured at temperatures from 295 up to 500 K. With increasing temperature, the thermal conductivity varied from 1.23 to 1.02 mW cm⁻¹ K⁻¹ (296 to 438 K) and from 1.51 to 1.02 mW cm⁻¹ K⁻¹ (295 to 505 K)

J. H. Wilson; J. E. Mrochek; J. K. Johnson

1984-01-01

333

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

334

Dissolution of coal in solvents  

SciTech Connect

Experimental studies were effected in a 1-liter batch reactor to determine the role of the solvent and temperature on the dissolution of a Kentucky No. 9 coal. The goal was to increase the dissolution yield, defined as conversion of coal to pyridine-soluble material, while decreasing the hydrogen demand. The experiments were carried out in the absence of hydrogen gas. The solvent and coal were heated at a constant rate of temperature rise to 300 to 400/sup 0/C and held at a constant temperature for periods of 0 to 50 minutes before rapidly quenching the reaction mixture. 2-Methylnaphalene, 1,2,3,4-tetrahydronaphthalene (tetralin), p-cresol or ..beta..-naphthol, and ..gamma..-picoline were used in different ratios as the solvent. These compounds represented, respectively, the polycondensed aromatics, hydroaromatics (hydrogen donor), monophenols, and basic nitrogen compounds found in coal liquefaction recycle solvents. Dissolution yield of the coal reached a maximum in a solvent containing equal parts of 2-methylnaphthalene and tetralin. The H/C ratio of the preasphaltenes remained virtually constant when the tetralin content ranged from 20 to 65 wt % in mixtures with 2-methylnaphthalene. A slight increase was noted when pure tetralin was the solvent. Addition of small amounts of ..beta..-naphthol and ..gamma..-picoline to a 1:4 weight ratio of tetralin and 2-methylnaphthalene improved the dissolution yield. Coal was dissolved with no or minor chemical reactions up to the temperature of approx. 340/sup 0/C in a solvent containing 46.1 wt % tetralin, 46.1 wt % 2-methylnaphthalene, 4.9 wt % ..beta..-naphthol, and 2.9 wt % ..gamma..-picoline. Beyond this temperature dissolution yield increased exponentially typical of thermal cracking reactions.

Ebnesajjad, S.

1982-01-01

335

Properties of ionic liquid solvents for catalysis  

Microsoft Academic Search

Ionic liquids are good solvents for catalytic reactions. The rational selection of the appropriate ionic liquid solvent for a particular reaction requires general knowledge of the properties of ionic liquids, and the details of some properties of the specific ionic liquid solvents being considered. The solvent properties of ionic liquids that are relevant to catalysis are discussed, and sources of

John S Wilkes

2004-01-01

336

NCMS solvent substitution and material compatibility databases  

Microsoft Academic Search

The NCMS Solvent Database collects information on alternatives to ODC-based solvents used in electronics manufacturing. The database contains over 320 pure solvents and trade name mixtures. Each record includes 15 fields of environmental fate, 31 fields of health and safety, 21 fields of regulatory status, 36 fields of chemical\\/physical properties, and 19 fields of descriptive and supplier data. The Solvent

M. R. Wixom

1994-01-01

337

Taoism and Deep Ecology.  

ERIC Educational Resources Information Center

Contrasted are the philosophies of Deep Ecology and ancient Chinese. Discusses the cosmology, morality, lifestyle, views of power, politics, and environmental philosophies of each. Concludes that Deep Ecology could gain much from Taoism. (CW)

Sylvan, Richard; Bennett, David

1988-01-01

338

Demonstration of a Universal Solvent Extraction Process for the Separation of Cesium and Strontium from Actual Acidic Tank Waste at the INEEL  

Microsoft Academic Search

A universal solvent extraction process is being evaluated for the simultaneous separation of Cs, Sr, and the actinides from acidic high-activity tank waste at the Idaho National Engineering and Environmental Laboratory (INEEL) with the goal of minimizing the high-activity waste volume to be disposed in a deep geological repository. The universal solvent extraction process is being developed as a collaborative

B. N. Zaitsev; D. J. Wood; I. V. Smirnov; J. D. Law; R. S. Herbst; T. A. Todd; V. A. Babain; V. M. Esimantovskiy; V. N. Romanovskiy

1999-01-01

339

Solvent effects in polyelectrolyte adsorption: Computer simulations with explicit and implicit solvent  

Microsoft Academic Search

The adsorption of strongly charged polyelectrolyte chains to an oppositely charged planar surface is studied using computer simulation. In addition to an explicit solvent model, two implicit solvent models are considered: one where the solvent induces an implicit Lennard-Jones (ILJ) interaction between polymer sites and one where the solvent induces a many body interaction that depends on the solvent accessible

Govardhan Reddy; Arun Yethiraj

2010-01-01

340

Solvent leaching of tar sands  

SciTech Connect

Solvent flooding is the basis of a wide range of enhanced oil recovery methods, and has been shown to be a possible method of creating initial steam injectivity in tar sands. This paper presents a unique model of dissolution of a semi-solid bitumen, resulting from the injection of a solvent. The solution of the mathematical equations, describing this phenomena is discussed. Results, including a series of two-dimensional problems, are presented. Numerical aspects are addressed. It is shown that three dimensionless groups control the bitumen leaching process. In the absence of fluid flow, the dissolution of bitumen is governed by the Damkohler and solvent capacity numbers. In the absence of dissolution, the Peclet number governs miscible displacement in the fluid phase. This paper presents computational results for a series of two-dimensional problems for a five-spot flow geometry, showing the importance of the model developed.

Oguztoreli, M.; Faroqu, S.M.

1983-11-01

341

Solvent sensitive polymer composite structures  

NASA Astrophysics Data System (ADS)

In this paper we describe a composite system based on polystyrene colloidal nanoparticles assembled and embedded in an elastomeric matrix (polymer colloidal crystal, PCC), in the specific we have designed a PCC structure which displays an iridescent green color that can be attributed to the photonic crystal effect. This effect has been exploited to create a chemical sensor, in fact optical measurements have evidenced that the composite structure presents a different optical response as a function of the solvent applied on the surface. In particular we have demonstrated that the PCC possess, for specific solvents: (i) high sensitivity, (ii) fast response (less than 1s), and (iii) reversibility of the signal change. Finally preliminary results on the PCC have shown that this system can be also used as optical writing substrate using a specific solvent as ink, moreover an erasing procedure is also reported and discussed.

Chiappini, A.; Armellini, C.; Carpentiero, A.; Minati, L.; Righini, G. C.; Ferrari, M.

2013-11-01

342

Solvent-regenerated activated carbon  

SciTech Connect

This report summarizes the results of a University/Industry research project, sponsored by the New York State Energy Research and Development Authority and Fluids Design Corporation. The research project studied the solvent regeneration of activated carbon. Activate carbon was used to remove trace organics from aqueous streams, then regenerated by desorbing the adsorbates with organic solvents. The project included a survey of the potential applications in New York State industries, fundamental research on the adsorption/desorption phenomena, and design of a full-scale process. The economics of the full-scale process were evaluated and compared to alternate available technologies. The result of this work is a versatile process with attractive economics. A wide range of adsorbates and solvents were found to be acceptable for this process. The design methodologies are developed and the techniques for evaluating a new application are delineated. 13 refs., 12 figs., 4 tabs.

McLaughlin, H. (Fluids Design Corp., Troy, NY (USA))

1988-07-01

343

Deep Web video  

SciTech Connect

To make the web work better for science, OSTI has developed state-of-the-art technologies and services including a deep web search capability. The deep web includes content in searchable databases available to web users but not accessible by popular search engines, such as Google. This video provides an introduction to the deep web search engine.

None Available

2009-06-01

344

Deep Web video  

ScienceCinema

To make the web work better for science, OSTI has developed state-of-the-art technologies and services including a deep web search capability. The deep web includes content in searchable databases available to web users but not accessible by popular search engines, such as Google. This video provides an introduction to the deep web search engine.

345

Deep space antennas  

Microsoft Academic Search

Three 26-m tracking antennas operated by the NASA Deep Space Network at Goldstone, Calif.; Madrid, Spain; and near Canberra, Australia, will cease operations on Dec. 1, 1981. The stations will continue to operate 64-m and 34-m deep space tracking antennas. Ending operation of the 26-m antennas will cause a reduction of about 30%; of the Deep Space Network tracking and

Peter M. Bell

1981-01-01

346

Deep Web video  

ScienceCinema

To make the web work better for science, OSTI has developed state-of-the-art technologies and services including a deep web search capability. The deep web includes content in searchable databases available to web users but not accessible by popular search engines, such as Google. This video provides an introduction to the deep web search engine.

None Available

2012-03-28

347

Occupational neurotoxicology of organic solvents and solvent mixtures  

Microsoft Academic Search

The results of two field studies in painters and spray painters, the outcomes of examinations of workers with suspected work-related disease due to solvents, as well as data from an evaluation of an epidemiologic study in painters with confirmed occupational disease, are presented and discussed. The results of these studies and the experiences in occupational medicine in the Federal Republic

G TRIEBIG

1989-01-01

348

MICROBIOLOGY: Breathing with Chlorinated Solvents  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required: Chlorinated solvents, the carcinogenic agents that permeate the air in your dry cleaners, have accumulated in the groundwater because microorganisms in the soil do not break them down. Now Maymó-Gatell et al. have isolated the first bacterium that can metabolize trichloroethylene and perchloroethylene to the harmless compound ethene. Identification of the bacterium will potentially allow manipulation of the conditions underground to facilitate the natural destruction of chlorinated solvents.

Perry L. McCarty (Stanford University;Department of Civil Engineering)

1997-06-06

349

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

350

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

351

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

352

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

353

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

354

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

355

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

356

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

357

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

358

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

359

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

360

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

361

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

362

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

363

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

364

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

365

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

366

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

367

DOE solvent handbook information sheet  

Microsoft Academic Search

Solvents and cleaners are used in the Department of Defense (DOD) and the Department of Energy-Defense Program (DOE-DP) maintenance facilities for removing wax, grease, oil, carbon, machining fluids, solder fluxes, mold releases, and other contaminants before repairing or electroplating parts. Private industry also uses cleaners and degreasers for surface preparation of various metals. Growing environmental and worker safety concerns have

Chavez

1992-01-01

368

Improved Purex solvent scrubbing methods  

SciTech Connect

Studies of hydrazine and hydroxylamine salts as solvent scrubbing agents that can be decomposed into gases are summarized. Results from testing of countercurrent scrubbers and solid sorber columns that produce lesser amounts of permanent salts are reported. The status of studies of the acid-degradation of paraffin diluent and the options for removal of long-chain organic acids is given.

Mailen, J.C.; Tallent, O.K.

1984-01-01

369

Nanopapers for organic solvent nanofiltration.  

PubMed

Would it not be nice to have an organic solvent nanofiltration membrane made from renewable resources that can be manufactured as simply as producing paper? Here the production of nanofiltration membranes made from nanocellulose by applying a papermaking process is demonstrated. Manufacture of the nanopapers was enabled by inducing flocculation of nanofibrils upon addition of trivalent ions. PMID:24752201

Mautner, A; Lee, K-Y; Lahtinen, P; Hakalahti, M; Tammelin, T; Li, K; Bismarck, A

2014-06-01

370

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

371

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

372

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

373

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

374

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

375

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

376

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

377

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

378

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

379

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

380

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

381

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

382

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

383

Compatibility of Contaminants and Plastics with Solvents.  

National Technical Information Service (NTIS)

The use of solvents is being examined as a result of environmental improvement requirements being established by state and federal agencies. Although purchase cost is a factor in selecting alternate solvents for particular requirements, performance contro...

L. C. Jackson E. T. Walsh

1975-01-01

384

Dipolar correlations in structured solvents under nanoconfinement.  

PubMed

We study electrostatic correlations in structured solvents confined to nanoscale systems. We derive variational equations of Netz-Orland type for a model liquid composed of finite size dipoles. These equations are solved for both dilute solvents and solvents at physiological concentrations in a slit nanopore geometry. Correlation effects are of major importance for the dielectric reduction and anisotropy of the solvent resulting from dipole image interactions and also lead to a reduction of van der Waals attractions between low dielectric bodies. Finally, by comparison with other recently developed self-consistent theories and experiments, we scrutinize the effect of solvent-membrane interactions on the differential capacitance of the charged liquid in contact with low dielectric substrates. The interfacial solvent depletion driven by solvent-image interactions plays the major role in the observed low values of the experimental capacitance data, while non-locality associated with the extended charge structure of solvent molecules only brings a minor contribution. PMID:24952564

Buyukdagli, Sahin; Blossey, Ralf

2014-06-21

385

Alternatives to Solvent-Borne Adhesives.  

National Technical Information Service (NTIS)

Rapidly escalating costs of solvent borne adhesives have now given water borne adhesives a significant economic advantage to further advance the environmental and OSHA forces already acting to reduce solvent usage. Water borne adhesive systems based on ch...

W. C. Kania

1980-01-01

386

Dipolar correlations in structured solvents under nanoconfinement  

NASA Astrophysics Data System (ADS)

We study electrostatic correlations in structured solvents confined to nanoscale systems. We derive variational equations of Netz-Orland type for a model liquid composed of finite size dipoles. These equations are solved for both dilute solvents and solvents at physiological concentrations in a slit nanopore geometry. Correlation effects are of major importance for the dielectric reduction and anisotropy of the solvent resulting from dipole image interactions and also lead to a reduction of van der Waals attractions between low dielectric bodies. Finally, by comparison with other recently developed self-consistent theories and experiments, we scrutinize the effect of solvent-membrane interactions on the differential capacitance of the charged liquid in contact with low dielectric substrates. The interfacial solvent depletion driven by solvent-image interactions plays the major role in the observed low values of the experimental capacitance data, while non-locality associated with the extended charge structure of solvent molecules only brings a minor contribution.

Buyukdagli, Sahin; Blossey, Ralf

2014-06-01

387

Wash solvent reuse in paint production  

SciTech Connect

The project evaluated solvent used to clean paint manufacture equipment for its utility in production of subsequent batches of solvent-borne paint. Reusing wash solvent would reduce the amount of solvent disposed of as waste. The evaluation of this wash-solvent recovery technology was conducted by Battelle Memorial Institute for the Pollution Prevention Research Branch of the U.S. Environmental Protection Agency. The evaluation was conducted with the cooperation and assistance of Vanex Color, Inc. The product quality, waste reduction/pollution prevention, and economic impacts of this technology change, as it has been implemented by Vanex, were examined. Two batches of a solvent-borne alkyd house paint were prepared at Vanex--one batch made with 100%-new solvent and the other with 30%-wash solvent--and sampled for laboratory analysis at Battelle.

Parsons, A.B.; Heater, K.J.; Olfenbuttel, R.F.

1994-04-01

388

Restoring Solvent for Nuclear Separation Processes.  

National Technical Information Service (NTIS)

Solvent extraction separation processes are used to recover usable nuclear materials from spent fuels. These processes involve the use of an extractant/diluent (solvent) for separation of the reusable actinides from unwanted fission products. The most wid...

D. J. Reif

1987-01-01

389

Google's Deep Web crawl  

Microsoft Academic Search

The Deep Web, i.e., content hidden behind HTML forms, has long been acknowledged as a significant gap in search engine coverage. Since it represents a large portion of the structured data on the Web, accessing Deep-Web content has been a long-standing challenge for the database commu- nity. This paper describes a system for surfacing Deep-Web content, i.e., pre-computing submissions for

Jayant Madhavan; David Ko; Lucja Kot; Vignesh Ganapathy; Alex Rasmussen; Alon Y. Halevy

2008-01-01

390

Solvent refining of Kuwaiti heavy diesel oil  

SciTech Connect

Results of studies to determine the optimum operating conditions for the solvent refining of Kuwaiti heavy diesel oil (HDO) to find the most suitable solvent for the production of lube oil base stocks from HDO are reported. The solvents studied were furfural, ..beta..-methoxypropionitrile (..beta..-MPN) and N-methylpyrrolidone (NMP). NMP was found to have the highest capacity as a solvent. (BLM)

Ijam, M.J.; Fahim, M.A.; Abu-Elgheit, M.

1981-08-01

391

Preparation of coal slurry with organic solvents  

Microsoft Academic Search

In this study, various organic solvents were used to prepare coal slurries and the rheological and thermal properties of coal–organic solvent slurries were examined. Solvents with molecules containing unpaired electrons (high basicity) show high extraction power and cause swelling of coal. Therefore, coal–organic solvent slurries usually showed higher viscosities compared to coal–water slurry. In addition, coal slurries prepared by alcohols

Yu-Jen Shin; Yun-Hwei Shen

2007-01-01

392

Venture Deep Ocean  

NSDL National Science Digital Library

Venture Deep Ocean highlights recent discoveries about seafloor volcanoes and hydrothermal vents, and the uniquely specialized organisms that inhabit these extreme environments. Site materials include feature stories that are updated periodically and an image gallery with illustrated articles, slideshows, and a featured image. There are also tutorials on deep-sea exploration that cover volcanoes and vents, life in the deep, expeditions to explore the deep sea, and some of their tools and techniques. Other materials include links to news articles from other websites and a brief overview of the organization.

393

Deep Space Communication  

NASA Technical Reports Server (NTRS)

ITU defines deep space as the volume of Space at distances from the Earth equal to, or greater than, 2 106 km. Deep Space Spacecraft have to travel tens of millions of km from Earth to reach the nearest object in deep space. Spacecraft mass and power are precious. Large ground-based antennas and very high power transmitters are needed to overcome large space loss and spacecraft's small antennas and low power transmitters. Navigation is complex and highly dependent on measurements from the Earth. Every deep space mission is unique and therefore very costly to develop.

Manshadi, Farzin

2012-01-01

394

The deep space network  

NASA Technical Reports Server (NTRS)

Summaries are given of Deep Space Network progress in flight project support, tracking and data acquisition research and technology, network engineering, hardware and software implementation, and operations.

1975-01-01

395

A deep reef in deep trouble  

USGS Publications Warehouse

The well-documented degradation of shallower reefs which are often closer to land and more vulnerable to pollution, sewage and other human-related stressors has led to the suggestion that deeper, more remote offshore reefs could possibly serve as sources of coral and fish larvae to replenish the shallower reefs. Yet, the distribution, status, and ecological roles of deep (>30 m) Caribbean reefs are not well known. In this report, an observation of a deep reef which has undergone a recent extensive loss of coral cover is presented. In stark contrast to the typical pattern of coral loss in shallow reefs, the deeper corals were most affected. This report is the first description of such a pattern of coral loss on a deep reef.

Menza, C.; Kendall, M.; Rogers, C.; Miller, J.

2007-01-01

396

Restoring solvent for nuclear separation processes  

Microsoft Academic Search

Solvent extraction separation processes are used to recover usable nuclear materials from spent fuels. These processes involve the use of an extractant\\/diluent (solvent) for separation of the reusable actinides from unwanted fission products. The most widely used processes employ tributyl phosphate as an extractant diluted with a normal-paraffin hydrocarbon. During use, the solvent is altered due to hydrolysis and radiolysis,

Rief

1988-01-01

397

Restoring solvent for nuclear separation processes  

Microsoft Academic Search

Solvent extraction separation processes are used to recover usable nuclear materials from spent fuels. These processes involve the use of an extractant\\/diluent (solvent) for separation of the reusable actinides from unwanted fission products. The most widely used processes employ tributyl phosphate as an extractant diluted with a normal-paraffin hydrocarbon. During use, the solvent is altered due to hydrolysis and radiolysis,

Reif

1987-01-01

398

Restoring Solvent for Nuclear Separation Processes  

Microsoft Academic Search

Solvent extraction separation processes are used to recover usable nuclear materials from spent fuels. These processes involve the use of an extractant\\/diluent (solvent) for separation of the reusable actinides from unwanted fission products. The most widely used processes employ tributyl phosphate as an extractant diluted with a normal-paraffin hydrocarbon. During use, the solvent is altered due to hydrolysis and radiolysis,

D. J. Reif

1988-01-01

399

The use of alternative solvent purification techniques  

Microsoft Academic Search

A recent accident at the University of California, Irvine involved the purification of an organic solvent using a solvent still resulting in a fire in the lab. A graduate student was seriously burned and $3.5 million in property damage was incurred. In this report, lessons learned from this accident are used to improve the safety of solvent purification operations. Column

Michael E. Cournoyer; Jeffrey H Dare

2003-01-01

400

Solvent Extraction of Furfural From Biomass  

NASA Technical Reports Server (NTRS)

Solvent-extraction method reduces energy required to remove furfural produced during acid hydrolysis of biomass. Acid hydrolysis performed in vessel containing both solvents and reacting ingredients. With intimate contact between solvents and aqueous hydrolyis liqour, furfural removed form liquor almost as fast as it forms.

Humphrey, M. F.

1984-01-01

401

Firing of pulverized solvent refined coal  

DOEpatents

An air-purged burner for the firing of pulverized solvent refined coal is constructed and operated such that the solvent refined coal can be fired without the coking thereof on the burner components. The air-purged burner is designed for the firing of pulverized solvent refined coal in a tangentially fired boiler.

Derbidge, T. Craig (Sunnyvale, CA); Mulholland, James A. (Chapel Hill, NC); Foster, Edward P. (Macungie, PA)

1986-01-01

402

Solvent characterization using the dispersion number.  

National Technical Information Service (NTIS)

When developing new solvent extraction processes, one often has to evaluate new solvents, new aqueous phases, or both for their ability to work in plant-scale equipment. To facilitate solvent characterization, a simple test is proposed based on the dimens...

R. A. Leonard

1993-01-01

403

Solvent-free oil dispersant  

US Patent & Trademark Office Database

The present invention is directed toward an oil dispersant composition useful in treating oil spills, and for cleanup of the shoreline, animals, plants, and equipment. The oil dispersant product is a non-toxic, solvent-free composition which efficiently breaks down grease, grime and crude oil at the molecular level, by breaking down the hydrocarbon chains and preventing the oil molecules from ever reforming again.

2013-04-09

404

Solvent cleaning system and method for removing contaminants from solvent used in resin recycling  

DOEpatents

A two step solvent and carbon dioxide based system that produces essentially contaminant-free synthetic resin material and which further includes a solvent cleaning system for periodically removing the contaminants from the solvent so that the solvent can be reused and the contaminants can be collected and safely discarded in an environmentally safe manner.

Bohnert, George W. (Harrisonville, MO); Hand, Thomas E. (Lee's Summit, MO); DeLaurentiis, Gary M. (Jamestown, CA)

2009-01-06

405

Cleanup of 7. 5% tributyl phosphate\\/n-paraffin solvent-extraction solvent  

Microsoft Academic Search

The HM process at the Savannah River Plant uses 7.5% tributyl phosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials which influence product losses, product decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown that carbonate washing, although removing residual solvent activity, does not remove

Reif

1987-01-01

406

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

407

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

408

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

409

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

410

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

411

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

412

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

413

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

414

SOLVENT DISPERSION AND FLOW METER CALCULATION RESULTS  

SciTech Connect

Savannah River National Laboratory (SRNL) found that the dispersion numbers for the six combinations of CSSX:Next Generation Solvent (NGS) “blend” and pure NGS versus salt solution, caustic wash, and strip aqueous solutions are all good. The dispersion numbers are indications of processability with centrifugal contactors. A comparison of solvent physical and thermal properties shows that the Intek™ solvent flow meter in the plant has a reading biased high versus calibrated flow when NGS is used, versus the standard CSSX solvent. The flow meter, calibrated for CSSX solvent, is predicted to read 2.8 gpm of NGS in a case where the true flow of NGS is 2.16 gpm.

Nash, C.; Fondeur, F.; Peters, T.

2013-06-21

415

Aminosilicone solvents for CO(2) capture.  

PubMed

This work describes the first report of the use of an aminosilicone solvent mix for the capture of CO(2). To maintain a liquid state, a hydroxyether co-solvent was employed which allowed enhanced physisorption of CO(2) in the solvent mixture. Regeneration of the capture solvent system was demonstrated over 6 cycles and absorption isotherms indicate a 25-50 % increase in dynamic CO(2) capacity over 30 % MEA. In addition, proof of concept for continuous CO(2) absorption was verified. Additionally, modeling to predict heats of reaction of aminosilicone solvents with CO(2) was in good agreement with experimental results. PMID:20730981

Perry, Robert J; Grocela-Rocha, Teresa A; O'Brien, Michael J; Genovese, Sarah; Wood, Benjamin R; Lewis, Larry N; Lam, Hubert; Soloveichik, Grigorii; Rubinsztajn, Malgorzata; Kniajanski, Sergei; Draper, Sam; Enick, Robert M; Johnson, J Karl; Xie, Hong-bin; Tapriyal, Deepak

2010-08-23

416

Querying the deep web  

Microsoft Academic Search

Data stored outside Web pages and accessible from the Web, typically through HTML forms, consitute the so-called Deep Web. Such data are of great value, but difficult to query and search. We survey techniques to optimize query processing on the Deep Web, in a setting where data are represented in the relational model. We illustrate optimizations both at query plan

Andrea Calì; Davide Martinenghi

2010-01-01

417

The Deep Space Network  

NASA Technical Reports Server (NTRS)

Deep Space Network progress in flight project support, tracking and data acquisition, research and technology, network engineering, hardware and software implementation, and operations is cited. Topics covered include: tracking and ground based navigation; spacecraft/ground communication; station control and operations technology; ground communications; and deep space stations.

1979-01-01

418

Deep-diving dinosaurs  

NASA Astrophysics Data System (ADS)

Dysbaric bone necrosis demonstrated in ichthyosaurs may be the result of prolonged deep diving rather than rapid ascent to escape predators. The bone lesions show structural and anatomical similarity to those that may occur in human divers and in the deep diving sperm whale, Physeter macrocephalus.

Hayman, John

2012-08-01

419

Deep vein thrombosis.  

PubMed

Deep vein thrombosis (DVT) is a thrombus or blood clot that can occur in any of the deep veins in the body. DVTs occur most commonly in the leg or pelvis but also travel to the lungs, causing pulmonary embolism. PMID:24938985

Jackson, Mike

2014-06-18

420

The deep space network  

NASA Technical Reports Server (NTRS)

The progress is reported of Deep Space Network (DSN) research in the following areas: (1) flight project support, (2) spacecraft/ground communications, (3) station control and operations technology, (4) network control and processing, and (5) deep space stations. A description of the DSN functions and facilities is included.

1974-01-01

421

Institutions and Deep Integration  

Microsoft Academic Search

The paper explains why institutions matter for a deep integration process, as illustrated by the liberalization of Non-Tariff Barriers (NTBs) in Europe. We argue that deep trade liberalization requires supranational institutions of deeper integration that permit enforcement, surveillance, and adjudication. To support the claim, we develop a simple model showing why mutual recognition of norms and testing procedures, coupled with

Alberto Amurgo Pacheco

2006-01-01

422

More efficient deep grinding  

Microsoft Academic Search

Currently, abrasive machining is used to improve product quality and productivity and also for preliminary and final machining in a single pass. Deep grinding is of particular interest here. In this method, with considerable metal removal in a single pass, problems arise in preventing thermal and other damage to the part. The kinematic aspects of deep grinding were analyzed in

O. G. Bykadorova; V. M. Shumyacher

2008-01-01

423

Effect of solvents on obligately anaerobic bacteria.  

PubMed

Growth of Acetobacterium woodii and Clostridium sporogenes was studied in the presence of water-immiscible solvents. Nitrogen purging, vacuum distillation or distillation under nitrogen were all suitable as methods to remove oxygen from the solvents, since growth rates and yields of A. woodii were unaffected in the presence of tetradecane which had been degassed by these methods. Varying the solvent volume from 20% to 80% of the culture volume had little effect on growth rate of A. woodii. A.woodii was relatively sensitive to organic solvents since growth was inhibited by alkanes with logP(octanol/water) values below 7.1. C. sporogenes was less solvent sensitive, since it grew without inhibition when the logP of the solvent was > or = 6.6. Nevertheless, both A. woodii and C. sporogenes were more sensitive to solvent polarity than aerobic bacteria. PMID:18083050

Rodriguez Martinez, Maria Fernanda; Kelessidou, Niki; Law, Zoe; Gardiner, John; Stephens, Gill

2008-02-01

424

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

425

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

426

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

427

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

428

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

429

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

430

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

431

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

432

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

433

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

434

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

435

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

436

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

437

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

438

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

439

Time resolved solvent rearrangement dynamics.  

PubMed

Ultrafast pump-probe studies of I2- recombination in size-selected I2- (CO2)n cluster ions demonstrate long time coherent motions in size-selected clusters and the resulting non-statistical energy flow in the cluster. For I2- photodissociated to produce either I- + I or I- + I*, we identify a solvent-driven energy transfer process without a condensed phase counterpart. The mechanism involved is a Marcus-like solvent-driven curve crossing, with the driving force arising from asymmetric solvation, not just from solvent orientation. By substituting another halogen for one I atom, we "break" the I2- symmetry, and thus obtain direct information on the electron transfer process. New experiments on IBr- (CO2)n photodissociation products confirm the behavior suspected in the I2- studies. Time-resolved experiments on IBr- and theoretical modeling of the dynamics provide quantitative information on the multiple curve crossings encountered in the recombination process. In related investigations, femtosecond negative ion-neutral-positive ion charge reversal apparatus is employed to investigate transient neutral species evolving along a reaction coordinate. We report studies of the rearrangement dynamics of Cu(OH2) produced by photodetachment of the corresponding anion. Following a controlled delay period, a second ultrafast tunable laser pulse initiates resonant multiphoton photoionization of the time-evolving Cu...OH2 complex. The time-resolved Cu+ and Cu+(OH2) signals provide information both on the prompt dissociation of the complex and on energy redistribution between internal rotational and radial modes of the evolving complex. Calculations of the time evolution of the anion geometric configuration on the neutral potential energy surface yield deeper insight into the nature of the rearrangement process and the energy flow within the complex. PMID:15471355

Sanford, Todd; Andrews, Django; Rathbone, Jeff; Taylor, Mark; Muntean, Felician; Thompson, Matthew; McCoy, Anne B; Parson, Robert; Lineberger, W Carl

2004-01-01

440

Solvent cavitation under solvophobic confinement  

NASA Astrophysics Data System (ADS)

The stability of liquids under solvophobic confinement can tip in favor of the vapor phase, nucleating a liquid-to-vapor phase transition that induces attractive forces between confining surfaces. In the case of water adjacent to hydrophobic surfaces, experimental and theoretical evidence support confinement-mediated evaporation stabilization of biomolecular and colloidal assemblies. The macroscopic thermodynamic theory of cavitation under confinement establishes the connection between the size of the confining surfaces, interfacial free energies, and bulk solvent pressure with the critical evaporation separation and interfacial forces. While molecular simulations have confirmed the broad theoretical trends, a quantitative comparison based on independent measurements of the interfacial free energies and liquid-vapor coexistence properties has, to the best of our knowledge, not yet been performed. To overcome the challenges of simulating a large number of systems to validate scaling predictions for a three-dimensional fluid, we simulate both the forces and liquid-vapor coexistence properties of a two-dimensional Lennard-Jones fluid confined between solvophobic plates over a range of plate sizes and reservoir pressures. Our simulations quantitatively agree with theoretical predictions for solvent-mediated forces and critical evaporation separations once the length dependence of the solvation free energy of an individual confining plate is taken into account. The effective solid-liquid line tension length dependence results from molecular scale correlations for solvating microscopic plates and asymptotically decays to the macroscopic value for plates longer than 150 solvent diameters. The success of the macroscopic thermodynamic theory at describing two-dimensional liquids suggests application to surfactant monolayers to experimentally confirm confinement-mediated cavitation.

Ashbaugh, Henry S.

2013-08-01

441

Solvent refined coal (SRC) process  

SciTech Connect

This report summarizes the progress of the Solvent Refined Coal (SRC) project by The Pittsburg and Midway Coal Mining Co. at the SRC Pilot Plant in Fort Lewis, Washington and the Gulf Science and Technology Company Process Development Unit (P-99) in Harmarville, Pennsylvania, for the Department of Energy during the month of October, 1980. The Fort Lewis Pilot Plant was shut down the entire month of October, 1980 for inspection and maintenance. PDU P-99 completed two runs during October investigating potential start-up modes for the Demonstration Plant.

Not Available

1980-12-01

442

A COMPARISON OF PHYSICAL SOLVENTS FOR ACID GAS REMOVAL  

Microsoft Academic Search

Physical solvents such as DEPG (Selexol™ or Coastal AGR®), NMP or N-Methyl-2- Pyrrolidone (Purisol®), Methanol (Rectisol®), and Propylene Carbonate (Fluor Solvent™) are becoming increasingly popular as gas treating solvents, especially for coal gasification applications. Physical solvents tend to be favored over chemical solvents when the concentration of acid gases or other impurities is very high. In addition, physical solvents can

Barry Burr; Lili Lyddon

443

Deep Moonquakes: Remaining Problems  

NASA Technical Reports Server (NTRS)

We have recently reexamined more than 9000 United States previously unidentified seismic events catalogued during the Apollo landing missions and positively identified for the first time about 30 deep moonquake nests on the far side of the Moon. Although only a few of them are currently locatable, the relative arrival times among stations for the rest and presence or absence of seismic signals at particular stations suggest that either (a) the region within about $40\\deg$ of the antipode is aseismic or (b) the deep interior of the Moon severely attenuates or deflects seismic waves. Aside from the obvious question of how to distinguish between such hypothetical models, this effort raised several more general questions concerning the use of deep moonquake signals to infer the structure and dynamics of the deep interior of the Moon. Among more important ones are: (1) How reliable are the seismic arrival picks from which to compute the seismic velocity variations in the Moon? (2) How do the possible lateral variations in seismic velocity affect the computed radial variation in seismic velocity at depth? (3) Can we tell more about the distribution and mechanism of deep moonquakes from the newly expanded database of identified deep moonquakes? Questions (1) and (2) are especially important because the inferred deep internal structure of the Moon depends critically on their answers. Answering these questions may demand additional data collected on future lunar missions, but some may be resolved with further examination of the existing data.

Nakamura, Y.

2004-01-01

444

Rational solvent selection for cooling crystallizations  

SciTech Connect

The development of a successful crystallization process for purification and isolation of an organic compound requires the selection of a suitable solvent or solvent mixture; to date, no logical method has been established for determining the best solvent combination. The process chemist or engineer often employs a trial-and-error procedure to identify an appropriate solvent system, the success of which is dependent on experience and intuition. This paper describes a strategy for choosing crystallization solvents based upon equilibrium limits. The approach utilizes a group-contribution method (UNIFAC) to predict a value for the activity coefficient of the solute in a given solvent system at the saturation point. This value is then used to calculate the solubility of the solute at a high'' temperature and a low'' temperature. The resulting solubility values determine the maximum theoretical yield for the process. Both quantities are used to rank order solvents and/or their mixtures relative to one another according to their solvent power and potential process yield. Several examples illustrating the successful application of this method are described, and potential improvements to the algorithm are discussed. Implementation of this strategy will reduce product cycle time, minimize solvent usage, and allow identification of cheaper solvent alternatives.

Nass, K.K. (Eastman Kodak Co., Rochester, NY (United States). Chemicals Development Div.)

1994-06-01

445

Process for solvent refining of coal using a denitrogenated and dephenolated solvent  

SciTech Connect

A process is disclosed for the solvent refining of nonanthracitic coal at elevated temperatures and pressure in a hydrogen atmosphere using a hydrocarbon solvent which before being recycled in the solvent refining process is subjected to chemical treatment to extract substantially all nitrogenous and phenolic constituents from the solvent so as to improve the conversion of coal and the production of oil in the solvent refining process. The solvent refining process can be either thermal or catalytic. The extraction of nitrogenous compounds can be performed by acid contact such as hydrogen chloride or fluoride treatment, while phenolic extraction can be performed by caustic contact or contact with a mixture of silica and alumina.

Carg, D.; Givens, E.N.

1984-09-18

446

Nurturing Deep Connections.  

ERIC Educational Resources Information Center

Argues that the missing ingredient in school reform is soul, that is, deep connections among students, teachers, and administrators. Discusses five principles of leadership with soul: Personalize, pacing, permission, protection, and paradox. (PKP)

Kessler, Rachael

2002-01-01

447

The deep space network  

NASA Technical Reports Server (NTRS)

The functions and facilities of the Deep Space Network are considered. Progress in flight project support, tracking and data acquisition research and technology, network engineering, hardware and software implementation, and operations is reported.

1980-01-01

448

The deep space network  

NASA Technical Reports Server (NTRS)

The facilities, programming system, and monitor and control system for the deep space network are described. Ongoing planetary and interplanetary flight projects are reviewed, along with tracking and ground-based navigation, communications, and network and facility engineering.

1977-01-01

449

The Deep Space Network.  

National Technical Information Service (NTIS)

Work accomplished on the Deep Space Network (DSN) was described, including the following topics: supporting research and technology, advanced development and engineering, system implementation, and DSN operations pertaining to mission-independent or multi...

1975-01-01

450

Deep vein thrombosis - discharge  

MedlinePLUS

Deep venous thrombosis (DVT) is when a blood clot forms in a vein that is not on the surface of the ... al. Executive Summary: Antithrombotic Therapy and Prevention of Thrombosis. 9th ed. American College of Chest Physicians Evidence- ...

451

Solvent dependent photophysical properties of dimethoxy curcumin  

NASA Astrophysics Data System (ADS)

Dimethoxy curcumin (DMC) is a methylated derivative of curcumin. In order to know the effect of ring substitution on photophysical properties of curcumin, steady state absorption and fluorescence spectra of DMC were recorded in organic solvents with different polarity and compared with those of curcumin. The absorption and fluorescence spectra of DMC, like curcumin, are strongly dependent on solvent polarity and the maxima of DMC showed red shift with increase in solvent polarity function (?f), but the above effect is prominently observed in case of fluorescence maxima. From the dependence of Stokes' shift on solvent polarity function the difference between the excited state and ground state dipole moment was estimated as 4.9 D. Fluorescence quantum yield (?f) and fluorescence lifetime (?f) of DMC were also measured in different solvents at room temperature. The results indicated that with increasing solvent polarity, ?f increased linearly, which has been accounted for the decrease in non-radiative rate by intersystem crossing (ISC) processes.

Barik, Atanu; Indira Priyadarsini, K.

2013-03-01

452

Organic solvents in the pharmaceutical industry.  

PubMed

Organic solvents are commonly used in the pharmaceutical industry as reaction media, in separation and purification of synthesis products and also for cleaning of equipment. This paper presents some aspects of organic solvents utilization in an active pharmaceutical ingredient and a drug product manufacturing process. As residual solvents are not desirable substances in a final product, different methods for their removal may be used, provided they fulfill safety criteria. After the drying process, analyses need to be performed to check if amounts of solvents used at any step of the production do not exceed acceptable limits (taken from ICH Guideline or from pharmacopoeias). Also new solvents like supercritical fluids or ionic liquids are developed to replace "traditional" organic solvents in the pharmaceutical production processes. PMID:20210074

Grodowska, Katarzyna; Parczewski, Andrzej

2010-01-01

453

Solvent Signal is a NMR Concentration Reference  

PubMed Central

We propose that the NMR solvent signal be utilized as a universal concentration reference because most solvents can be observed by NMR, and solvent concentrations can be readily calculated or determined independently. In particular, a highly protonated solvent such as water can serve as a primary concentration standard for its stability, availability and ease of observation. The potential issues of radiation damping associated with a strong NMR signal can be alleviated by small pulse angle excitations. The solvent signal then can be detected by the NMR receiver with the same efficiency as a dilute analyte. We demonstrated that the analyte's proton concentration can be accurately determined from 4 ?M to more than 100 M, referenced by solvent (water) protons of concentrations more than 10 M. The proposed method is robust and indifferent to probe tuning, and does not require any additional concentration standard.

Mo, Huaping; Raftery, Daniel

2009-01-01

454

Shallow & Deep Foundations  

NSDL National Science Digital Library

Students investigate the critical nature of foundations as they learn differences between shallow and deep foundations, including the concepts of bearing pressure and settlement. Using models representing a shallow foundation and a deep pile foundation, they test, see and feel the effects in a cardboard box test bed composed of layers of pebbles, soil and sand. They also make bearing pressure calculations and recommendations for which type of foundations to use in various engineering scenarios.

Integrated Teaching And Learning Program

455

The Deep Space Network  

NASA Technical Reports Server (NTRS)

The objectives, functions, and organization, of the Deep Space Network are summarized. Deep Space stations, ground communications, and network operations control capabilities are described. The network is designed for two-way communications with unmanned spacecraft traveling approximately 1600 km from earth to the farthest planets in the solar system. It has provided tracking and data acquisition support for the following projects: Ranger, Surveyor, Mariner, Pioneer, Apollo, Helios, Viking, and the Lunar Orbiter.

1974-01-01

456

The deep space network  

NASA Technical Reports Server (NTRS)

The objectives, functions, and organization of the Deep Space Network are summarized along with deep space station, ground communication, and network operations control capabilities. Mission support of ongoing planetary/interplanetary flight projects is discussed with emphasis on Viking orbiter radio frequency compatibility tests, the Pioneer Venus orbiter mission, and Helios-1 mission status and operations. Progress is also reported in tracking and data acquisition research and technology, network engineering, hardware and software implementation, and operations.

1975-01-01

457

Femtosecond dynamics in hydrogen-bonded solvents  

SciTech Connect

We present results on the ultrafast dynamics of pure hydrogen-bonding solvents, obtained using femtosecond Fourier-transform optical-heterodyne-detected, Raman-induced Kerr effect spectroscopy. Solvent systems we have studied include the formamides, water, ethylene glycol, and acetic acid. Inertial and diffusive motions are clearly resolved. We comment on the effect that such ultrafast solvent motions have on chemical reactions in solution.

Castner, E.W. Jr.; Chang, Y.J.

1993-09-01

458

In-depth analysis of solvent effects on bulk heterojunction solar cell performance  

NASA Astrophysics Data System (ADS)

Efficiency of an organic solar cell is very sensitive to fabrication procedure. One of the most important parameters is active layer morphology which radically influences several cell properties such as generation rate, layer resistance, charge carrier motilities etc. Meantime, in P3HT:fullerene based solar cells, using PCBM would improve the morphology and increase the cost simultaneously. On the other hand, C60 is way less expensive, but its limited solubility in common solvents would influence cell performance. To benefit from its cost and as the formation of C60 aggregates and P3HT crystallinity significantly depend on the solvent which would influence several cell properties, one should find a proper solvent. To make an in-depth investigation of solvent effects, experimental investigations will not suffice and using a precise model to fit the data and extract hidden parameters would help us to have a deep understanding of the cells physical basis. In this work, an optimization algorithm is employed to fit a numerical model simulation results with experiments and the model benefits from a field dependent series resistance. Simulation results indicate that a suitable solvent mainly improves the cell performance by changing 3 basic parameters which are G, ?n and ?p. Additionally, although parameters such as Eg and DC dielectric constant are very crucial in determining power conversion efficiency, they cannot be effectively improved changing the solvent. It is reported that the cell prepared by Cl-naph:CB performs better than the other cells. Considering our results, it can be attributed to its larger G, ?n and ?p. It also has the least Rs and the largest Rsh among all other P3HT:C60 based cells (which is caused by its higher mobility-carrier density product). This work gives experimentalists an idea of how they should choose a solvent. The results can also be generalized to find a proper solvent for other active layer materials.

Zohourian Aboutorabi, Reihaneh; Joodaki, Mojtaba; Shahbazi, Kosar

2014-05-01

459

Process for hydrogenating coal and coal solvents  

DOEpatents

A novel process is described for the hydrogenation of coal by the hydrogenation of a solvent for the coal in which the hydrogenation of the coal solvent is conducted in the presence of a solvent hydrogenation catalyst of increased activity, wherein the hydrogenation catalyst is produced by reacting ferric oxide with hydrogen sulfide at a temperature range of 260.degree. C. to 315.degree. C. in an inert atmosphere to produce an iron sulfide hydrogenation catalyst for the solvent. Optimally, the reaction temperature is 275.degree. C. Alternately, the reaction can be conducted in a hydrogen atmosphere at 350.degree. C.

Tarrer, Arthur R. (Auburn, AL); Shridharani, Ketan G. (Auburn, AL)

1983-01-01

460

Organic solvent use in enterprises in Japan.  

PubMed

This study was initiated to elucidate possible changes in types of organic solvents (to be called solvents in short) used in enterprises in Japan through comparison of current solvent types with historical data since 1983. To investigate current situation in solvent use in enterprises, surveys were conducted during one year of 2009 to 2010. In total, workroom air samples in 1,497 unit workplaces with solvent use were analyzed in accordance with regulatory requirements. Typical use pattern of solvents was as mixtures, accounting for >70% of cases. Adhesives spreading (followed by adhesion) was relatively common in small-scale enterprises, whereas printing and painting work was more common in middle-scale ones, and solvent use for testing and research purpose was basically in large-scaled enterprises. Through-out printing, painting, surface coating and adhesive application, toluene was most common (being detected in 49 to 82% of workplaces depending on work types), whereas isopropyl alcohol was most common (49%) in degreasing, cleaning and wiping workplaces. Other commonly used solvents were methyl alcohol, ethyl acetate and acetone (33 to 37%). Comparison with historical data in Japan and literature-retrieved data outside of Japan all agreed with the observation that toluene is the most commonly used solvent. Application of trichloroethylene and 1,1,1-trichloroethane, once common in 1980s, has ceased to exist in recent years. PMID:21697614

Nagasawa, Yasuhiro; Ukai, Hirohiko; Okamoto, Satoru; Samoto, Hajime; Itoh, Kenji; Moriguchi, Jiro; Sakuragi, Sonoko; Ohashi, Fumiko; Takada, Shiro; Kawakami, Tetsuya; Ikeda, Masayuki

2011-01-01

461

Lipid membranes as solvents for carbon nanoparticles.  

PubMed

Fullerene is scarcely soluble in most solvents, including alkanes. Yet, it has been shown that C60 dissolves in lipid bilayers, whose interior is chemically identical to alkanes. Here, we use molecular simulations to explain why lipid bilayers are better than alkanes at dissolving fullerene clusters. Fullerene aggregation is driven by entropy, but enthalpic contributions determine the difference between alkanes and bilayers. Surprisingly, confinement and chain alignment in the bilayer do not affect fullerene aggregation, while solvent density and the perturbation of solvent-solvent interactions are key factors. PMID:24580709

Barnoud, Jonathan; Rossi, Giulia; Monticelli, Luca

2014-02-14

462

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

463

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

464

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

465

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

466

Solvent anode for plutonium purification  

SciTech Connect

The purpose of this study is to develop a technique to allow complete oxidation of plutonium from the anode during plutonium electrorefining. This will eliminate the generation of a ''spent'' anode heel which requires further treatment for recovery. Our approach is to employ a solvent metal in the anode to provide a liquid anode pool throughout electrorefining. We use molten salts and metals in ceramic crucibles at 700/sup 0/C. Our goal is to produce plutonium metal at 99.9% purity with oxidation and transfer of more than 98% of the impure plutonium feed metal from the anode into the salt and product phases. We have met these criteria in experiments on the 100 to 1000 g scale. We plan to scale our operations to 4 kg of feed plutonium and to optimize the process parameters.

Bowersox, D.F.; Fife, K.W.; Christensen, D.C.

1986-01-01

467

Quantitation of buried contamination by use of solvents. [degradation of silicone polymers by amine solvents  

NASA Technical Reports Server (NTRS)

Spore recovery form cured silicone potting compounds using amine solvents to degrade the cured polymers was investigated. A complete list of solvents and a description