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in subjects: "Phase Studies"

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Thermodynamic model for calorimetric and phase coexistence properties of coal derived fluids

On September 1, 1989 work was initiated on a project to extend the available vapor-liquid equilibrium (VLE) model for coal fluids to allow satisfactory predictions of excess enthalpies of coal liquids at high pressures. The available vapor liquid equilibrium model was developed with support from previous grant from DOE-PETC (Grant no. DE-FG22-89PC90541). The current project also involves measurement of some model compound VLE data and chromatographic characterization of coal liquids for distrib… more

Date: October 1, 1991

Creator: Kabadi, V. N.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Theory of ordering transformations in metals and minerals

This dissertation presents an investigation of ordering in FCC based systems using the pair potential approximation in the ground state and mean field limits. The theoretical approach is used to explain the occurrence of observed equilibrium phases and characteristics of thermodynamic instabilities, in particular, spinodal ordering and decomposition. It is shown that the stability of non-integer domain sizes in long period superstructures such as Al{sub 3}Ti and Ag{sub 3}Mg may result from the … more

Date: July 1, 1991

Creator: Lindsey, Timothy Francis

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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FY 90 annual research plan

The National Institute for Petroleum and Energy Research (NIPER) was established by the DOE to perform contract research for government and industrial clients. The emphasis of the DOE program is immediate near- and mid-term concerns of domestic oil and gas producibility. Its primary purpose is to improve the fundamental understanding of domestic oil and gas resources and the chemical, physical, and biological phenomena that govern the occurrence and recovery of these resources in addition to th… more

Date: January 1, 1990

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Effects of catalytic mineral matter on CO/CO sub 2 , temperature and burning time for char combustion

The temperature of a char particle burning in an oxygen containing atmosphere is the product of a strongly coupled balance between particle size and physical properties, heat transfer from the particle, surface reactivity, CO/CO{sub 2} ratio and gas phase diffusion in the surrounding boundary layer and within the particle. CO{sub 2}/CO ratios can be strongly influenced by catalytic material in the carbon and by the char temperature. In this program we are measuring the CO{sub 2}/CO ratio for bo… more

Date: May 4, 1992

Creator: Longwell, J. P.; Sarofim, A. F.; Lee, Chun-Hyuk & Modestino, A. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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High-temperature of thermodynamic properties of sodium

The set of high-temperature thermodynamic properties for sodium in the two-phase and subcooled-liquid regions which was previously recommended, has been modified to incorporate recent experimental data. In particular, replacement of the previously estimated critical constants with experimentally-determined values has resulted in substantial differences in the region of the critical point. The following thermodynamic properties were determined: pressure, density, enthalpy, entropy, internal ener… more

Date: January 1, 1977

Creator: Padilla, A. Jr.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Existence of fcc TiCr/sub 1/ /sub 8/H/sub 5/ /sub 3/

Originally an orthorhombic structure was assigned to the non-stoichiometric hydride TiCr/sub 1/ /sub 8/H/sub 3/ /sub 6/. Recent neutron and x-ray diffraction data indicated, however, that an alternate interpretation was possible, i.e. the solid consists of two hydride phases, an ..cap alpha..' Laves phase having a composition of TiCr/sub 1/ /sub 8/H/sub 2/ /sub 8/ and an fcc phase with a much higher hydrogen content. This proved to be the case and it has been determined that the high concentrat… more

Date: February 1, 1982

Creator: Johnson, J. R.; Reilly, J. J.; Reidinger, F.; Corliss, L. M. & Hastings, J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Mushy-zone model with an exact solution

In this paper we propose a very simple model of a mushy zone which admits of an explicit solution. To our knowledge, it is the only instance where an actual observation of the mushy zone width and structure is used as a partial basis for the model definition. The model rests upon two unknown parameters. The first determines the relation between the equilibrium temperature gradient and the mushy zone width. The second depends upon the dendritic structure in the mushy zone, and is related to the … more

Date: April 1, 1982

Creator: Solomon, A. D.; Wilson, D. G. & Alexiades, V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Novel nanodispersed coal liquefaction catalysts: Molecular design via microemulsion-based synthesis

The objective of this project is to pursue the development of highly dispersed and inexpensive catalysts for improved coal solubilization and upgrading of coal liquids. A novel study of the synthesis of liquefaction catalysts of nanometer size will be carried out. It is based on the molecular design of reverse micelles (microemulsions). These surfactant-stabilized, metal bearing microdrops offer unique opportunities for synthesizing very small particles by providing a cage-like effect that limi… more

Date: April 1, 1991

Creator: Osseo-Asare, K. & Radovic, L.R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Highest temperatures recorded by the Oklo mineral phase assemblages and rock textures

Biotite-bearing pelitic phase assemblages are observed in reactor zones 2 and 5 and up to at least 4 m outside of zone 2, indicating a minimum temperature in these regions of about 400/sup 0/C. Rock textures suggest that still higher temperatures may have been reached within the reactors.

Date: January 1, 1977

Creator: Vidale, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Development of a metallographic method for tungsten--rhenium. Final report

A metallographic method was developed for chemical vapor deposited tungsten-rhenium alloys consisting of a two-phase structure of ..beta.. solid solution and a finely dispersed A-15 or federite phase. This method provides fast and reliable information on the structure and composition of the CVD deposit.

Date: March 1, 1978

Creator: Rahe, A.H.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Advances in materials science, Metals and Ceramics Division. Triannual progress report, February-May 1980

Research is reported in the magnetic fusion energy and laser fusion energy programs, aluminium-air battery and vehicle research, geothermal research, nuclear waste management, basic energy science, and chemistry and materials science. (FS)

Date: August 1, 1980

Creator: Truhan, J.J. & Gordon, K.M. (eds.)

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Auger Electron Studies of Surfaces: Uranium Dioxide, Uranium, Graphite, 300 Series Stainless Steel, and Niobium.

No Description Available.

Date: January 1, 1968

Creator: Campbell, B. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Morphology and phase composition of an amine cured rubber modified epoxy

The sharpness of the interface between the matrix and the dispersed phase, the volume fraction of the dispersed phase, the distribution of particle sizes, and the concentration of epoxy in the dispersed phase were determined. Scanning transmission electron microscopy coupled with energy dispersive x-ray analysis revealed that the interface width is less than 500 A. Variation of the fraction of mobile hydrogens with temperature determined by nuclear magnetic resonance indicated that a small frac… more

Date: January 1, 1980

Creator: Sayre, J. A.; Assink, R. A. & Lagasse, R. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Separation of alcohol-water mixtures using salts

Use of a salt (KF or Na/sub 2/SO/sub 4/) to induce phase separation of alcohol-water mixtures was investigated in three process flowsheets to compare operating and capital costs with a conventional distillation process. The process feed was the Clostridia fermentation product, composed of 98 wt % water and 2 wt % solvents (70% 1-butanol, 27% 2-propanol, and 3% ethanol). The design basis was 150 x 10/sup 6/ kg/y of solvents. Phase equilibria and tieline data were obtained from literature and exp… more

Date: April 1, 1982

Creator: Card, J. C. & Farrell, L. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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State-of-the-art review of phase equilibria

High-pressure phase-equilibrium calculations using an equation of state are more sensitive to the mixing rules than to details in the effect of density or temperature on pressure. Attention must be given to the problem of how to extend equations of state to mixtures. One possible technique is provided by perturbation theory; another by superposition of chemical equilibria. At low or moderate pressures, vapor-phase corrections are often important. When specific intermolecular forces produce form… more

Date: March 1, 1980

Creator: Prausnitz, J.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Energetics and statistics of order in alloys with application to oxide superconductors

Now that first-principles calculations of ordering transformations are becoming increasingly accurate, the deficiencies of earlier mean field methods are becoming increasingly apparent. New techniques, based on cluster expansions, are now alleviating many of the earlier problems and are producing very satisfactory results. These ideas will be illustrated for the case of oxygen ordering in the YBa{sub 2}Cu{sub 3}O{sub z} superconducting compound, for which a very simple two-dimensional Ising mod… more

Date: June 1, 1991

Creator: de Fontaine, D. (Lawrence Livermore National Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering); Ceder, G. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering) & Asta, M. (Lawrence Livermore National Lab., CA (United States) California Univ., Berkeley, CA (United States).

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Design of duplex low carbon steels for improved strength: weight applications

Duplex ferrite-martensite (DFM) steels with excellent combinations of strength and formability have been selected from first principles, and their microstructure-property relationships established through a systematic investigation of a series of ternary Fe/X/0.1 C steels (X being varying amount of Cr and Si). Duplex processing consists of initial austenitization and quenching to form 100% martensite, followed by annealing in the (..cap alpha.. + ..gamma..) range and subsequent quenching. The r… more

Date: August 1, 1977

Creator: Koo, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Production of aluminum-silicon alloy and ferrosilicon and commercial purity aluminum by the direct reduction process. Fourth interim technical report, Phase B, June 1-August 31, 1979

A series of calculated energy balances were made on alternate thermal processes for Al and Al-Si production. The computer modeling program was checked for validity by modeling low shaft Si production and comparing to known commercial conditions. Burden materials ground to -65 mesh prior to agglomeration compared favorably to -200 mesh grinds. Ball forming agglomeration was developed for bauxite-clay-coke mixes. The balls produced had higher strength and abrasion resistance than extrusions made … more

Date: September 1, 1979

Creator: Bruno, M. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Interstitial-Phase Precipitation in Iron-Base Alloys: A Comparative Study

Recent developments have elucidated the atomistic mechanisms of precipitation of interstitial elements in simple alloy systems. However, in the more technologically important iron base alloys, interstitial phase precipitation is generally not well understood. The present experimental study was therefore designed to test the applicability of these concepts to more complex ferrous alloys. Hence, a comparative study was made of interstitial phase precipitation in ferritic Fe-Si-C and in austenitic… more

Date: June 1, 1982

Creator: Pelton, Alan Roy

Item Type: Report

Partner: UNT Libraries Government Documents Department

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A review of the U sub 3 O sub 8 -aluminum reaction as a potential heat source in research and test reactor accidents

A critical review of the literature on the U{sub 3}O{sub 8}-aluminum reaction has been conducted. The reaction in fabricated fuel plates is found to be less energetic and much slower than in cold-pressed powder mixtures. The difference is at least partially attributable to conversion of up to 50% of the U{sub 3}O{sub 8} to U{sub 4}O{sub 9} during fabrication. No definitive measurements of the amount and rate of energy release have been made. Data are provided upon which to base calculations of … more

Date: January 1, 1992

Creator: Snelgrove, J.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Chemical Engineering Division Fuel Cycle Programs. Quarterly progress report, January-March 1979

In the program on pyrochemical and dry processing methods (PDPM) for nuclear fuel, corrosion testing of refractory metals and alloys, graphite, and SiC in PDPM environments was done. A tungsten-metallized Al/sub 2/O/sub 3/-3% Y/sub 2/O/sub 3/ crucible was successfully fabricated. Tungsten microstructure of a plasma-sprayed tungsten crucible was stabilized by nickel infiltration and heat treatment. Solubility measurements of Th in Cd and Cd-Mg alloys were continued, as were experiments to study … more

Date: January 1, 1980

Creator: Steindler, M J; Ader, M & Barletta, R E

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Chemical Technology Division, Annual technical report, 1991

Highlights of the Chemical Technology (CMT) Division's activities during 1991 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including advanced batteries and fuel cells; (2) technology for fluidized-bed combustion and coal-fired magnetohydrodynamics; (3) methods for treatment of hazardous and mixed hazardous/radioactive waste; (4) the reaction of nuclear waste glass and spent fuel under conditions expected for an uns… more

Date: March 1, 1992

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Tricritical behavior in the ferromagnetic superconductor ErRh/sub 4/B/sub 4/

A new tricritical point on the phase boundary between the superconducting vortex phase and the normal paramagnetic phase of ErRh/sub 4/B/sub 4/ is presented. The microscopic origin of the tricritical point and the expected tricritical behavior are briefly discussed.

Date: August 1, 1985

Creator: Crabtree, G.W.; Kalia, R.K.; Hinks, D.G.; Behroozi, F. & Tachiki, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Hydrothermal reactions of fly ash

The reactions which occur when fly ash is treated under hydrothermal conditions will be investigated. Formation of four classes of compounds, which bracket likely fly ash compositional ranges, have been selected for study. These are calcium silicate hydrates, calcium silicosulfates, calcium aluminosulfates, and alkali aluminosilicates. The specific compounds fabricated will be determined and their stability regions assessed. As a part of stability assessment, the extent to which selected hazard… more

Date: January 1, 1991

Creator: Brown, P.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department