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Materials Science and Engineering Faculty Research & Creative Works

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Articles 901 - 930 of 1011

Full-Text Articles in Materials Science and Engineering

Defect Structure Of Mg‐Doped Lacro3 Model And Thermogravimetric Measurements, B. K. Flandermeyer, M. M. Nasrallah, A. K. Agarwal, Harlan U. Anderson Jan 1984

Defect Structure Of Mg‐Doped Lacro3 Model And Thermogravimetric Measurements, B. K. Flandermeyer, M. M. Nasrallah, A. K. Agarwal, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

Chemical stability and cation stoichiometry determine the applicability of LaCrO3 as a high‐temperature oxide electrode. A model for the behavior of acceptor‐doped LaCrO3, as a function of oxygen activity is proposed. The model is in agreement with experimental data on Mg‐doped LaCrO3. Stability regimes and compensation mechanisms at various oxygen activities and temperature are presented. Copyright © 1984, Wiley Blackwell. All rights reserved

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Dynamics Of Stress Induced Hydride Formation In Vanadium, Alex Aning, Manfred Wuttig Jan 1984

Dynamics Of Stress Induced Hydride Formation In Vanadium, Alex Aning, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Dynamics Of Twinning In Natural Α-Quartz, Alexander Aning, Manfred Wuttig Jan 1984

Dynamics Of Twinning In Natural Α-Quartz, Alexander Aning, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

Finite amplitude internal friction experiments in α-quartz are described and interpreted in terms of the theory of nonlinear anelasticity. The theory predicts a linear relationship between the driving force of the excitation and the period of the auto modulation at its onset. This relation is substantiated by experiments performed with a natural α-quartz reed vibrating in flexure at resonance frequencies between 65 and 170 Hz in the temperature range of 162° and 224°C. The data suggests that Dauphiné twinning in α-quartz causes the auto modulation governed by an activation energy of 92 kJ mole. This activation energy characterizes short distance …

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The Effects Of Certain Impurities And Their Interactions On Zinc Electrowinning, Donald R. Fosnacht, Thomas J. O'Keefe Dec 1983

The Effects Of Certain Impurities And Their Interactions On Zinc Electrowinning, Donald R. Fosnacht, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

The effects of germanium, antimony, arsenic, cobalt, glue, and free acid concentration were studied on both commercial and synthetic electrolytes. The effects of a single factor and the combined effects of multiple factors were elucidated. The temperature, zinc concentration, and current density were varied for some of the tests. It was found that the acid content was the most critical factor when impurity levels were at normal plant solution concentrations. The ranges where the effect of the impurity became apparent were: greater than 20 ppb (parts per billion) for antimony; 40 ppb for germanium; 120 ppb for arsenic; and 7 …

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Screening Design Test For Cobalt Cementation From Zinc Electrolyte, Mark S. Blaser, Thomas J. O'Keefe Sep 1983

Screening Design Test For Cobalt Cementation From Zinc Electrolyte, Mark S. Blaser, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Control Of Oxygen And Carbon Related Crystal Defects In Silicon Processing, P. D. Ownby, P. E. Grayson Aug 1983

Control Of Oxygen And Carbon Related Crystal Defects In Silicon Processing, P. D. Ownby, P. E. Grayson

Materials Science and Engineering Faculty Research & Creative Works

In the production of silicon articles at an elevated temperature, a stream comprising a controlled mixture of an oxygen-containing first gas and a second gas is admitted to the processing chamber. The first gas is one which partially dissociates under the conditions in the chamber to form both oxygen and the second gas. The second gas is one which is not harmful to silicon at the conditions in the chamber. Substantially equilibrium conditions are established in the chamber so that the dissociation of the first gas to oxygen occurs reversibly. The partial pressure of oxygen (PO2) is sensed …

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Preface, Delbert E. Day, Günther H. Frischat Jan 1983

Preface, Delbert E. Day, Günther H. Frischat

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Comments On A Paper By Baik And Raj, Hollis P. Leighly Jan 1983

Comments On A Paper By Baik And Raj, Hollis P. Leighly

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Twinning Pseudoelasticity In Intl, Manfred Wuttig, Lin Chun-Hung Jan 1983

Twinning Pseudoelasticity In Intl, Manfred Wuttig, Lin Chun-Hung

Materials Science and Engineering Faculty Research & Creative Works

Twin boundaries generally contribute significantly to the damping of a twinned crystal. In an In-19.1 at.% Tl single crystal the damping gives rise to auto modulation if the internal friction studies are performed in the 10 Hz frequency range, with a strain amplitude larger than 0.05 and at temperatures lower than 10°C. The frequency of the auto modulation is about 60 times slower than the frequency with which the reed type sample is driven. The auto modulation frequency has a maximum at -6 C and is characterized by an activation energy of 29 kJ/mol (7 kcal/mol). This maximum can be …

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Factors Influencing The Production Rate And Quality Of Lead Sinter, John R. Knoepke, Hung Yang Tsai, Arthur E. Morris Mar 1982

Factors Influencing The Production Rate And Quality Of Lead Sinter, John R. Knoepke, Hung Yang Tsai, Arthur E. Morris

Materials Science and Engineering Faculty Research & Creative Works

The sintering characteristics of a typical Missouri lead concentrate were determined for two types of raw sinter mix: conventionally prepared and pelletized. The important sintering characteristics are sulfur elimination, sinter strength, production rate of sinter, permeability of the sinter bed, and bed temperature. These characteristics were analyzed statistically, and are described by an empirical model, in which proportion of returns, moisture content, air flow, bed height, size distribution of returns, and ignition time are the independent variables. The characteristics of a conventionally prepared sinter mix are most strongly affected by the moisture content of the raw mix. The characteristics of …

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Anomalous Diffusion Of Carbon In A 70/30 Iron-Nickel Alloy, L. R. Chapman, D. A. Powers, Manfred Wuttig Jan 1982

Anomalous Diffusion Of Carbon In A 70/30 Iron-Nickel Alloy, L. R. Chapman, D. A. Powers, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Effects Of Varying Oxygen Partial Pressure On Molten Silicon-Ceramic Substrate Interactions, And Oxygen Partial Pressure Measurements Of Silicon Sheet Production Facilities, P. D. Ownby, Harold V. Romero Jan 1982

Effects Of Varying Oxygen Partial Pressure On Molten Silicon-Ceramic Substrate Interactions, And Oxygen Partial Pressure Measurements Of Silicon Sheet Production Facilities, P. D. Ownby, Harold V. Romero

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Glass Surfaces Then And Now, Norbert J. Kreidl Jan 1982

Glass Surfaces Then And Now, Norbert J. Kreidl

Materials Science and Engineering Faculty Research & Creative Works

A reservoir of efficient instrumentation capable of detailed and quantitative exploration of glass surface features is now available in the face of the recognition of their crucial importance for both surface and bulk properties as well as performance. Yet it may be instructive to glance at what had been learned about glass surfaces by investigators before the advent of these intricate tools. Among such earlier findings are the recognition of the altered composition and structure of the surface layer, the extension of this disturbance to considerable depth, the effect of surface structure on adsorption, adhesion, wetting, finishing, etc. and on …

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Conduction Polarization In Sodium Germanate Glasses, Akira Doi, D. E. Day May 1981

Conduction Polarization In Sodium Germanate Glasses, Akira Doi, D. E. Day

Materials Science and Engineering Faculty Research & Creative Works

Only one thermally stimulated depolarization current (TSDC) peak was found in germanate glasses containing from 0.19 to 32.5 mol% Na20, whereas comparable silicate glasses exhibit two such peaks. Equations are developed showing that the distortion of the equilibrium Na+-ion distribution by an applied electrical field produces a polarization in general agreement with the observed TSDC peak. It is proposed that the TSDC peak is due to dc conduction.

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Model For Evaporation Of A Grain‐Boundary Phase, Manfred Wuttig, Harlan U. Anderson Jan 1981

Model For Evaporation Of A Grain‐Boundary Phase, Manfred Wuttig, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The surface profile which develops in the vicinity of a grain boundary precipitate in the course of evaporation is calculated. It is shown that the presence of the grain boundary precipitate affects the profile significantly if the product of the width of the grain boundary precipitate and the ratio of the evaporation rates of the unperturbed surface and the grain boundary precipitate is larger than one. Copyright © 1981, Wiley Blackwell. All rights reserved

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Autooscillations In Zinc, Manfred Wuttig, Alex Aning, Tetsuro Suzuki Jan 1981

Autooscillations In Zinc, Manfred Wuttig, Alex Aning, Tetsuro Suzuki

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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The Inert Gas Effect On The Rate Of Evaporation Of Zinc And Cadmium, P. C.S. Wu, Thomas J. O'Keefe, Fred Kisslinger Dec 1980

The Inert Gas Effect On The Rate Of Evaporation Of Zinc And Cadmium, P. C.S. Wu, Thomas J. O'Keefe, Fred Kisslinger

Materials Science and Engineering Faculty Research & Creative Works

An experimental study has been made to investigate the effect of argon and helium on the rate of evaporation of zinc and cadmium under one atmosphere pressure at temperatures ranging from 500 to 850°C. The experimental results were compared with the maximum rates calculated using the effusion formula as well as with values obtained using two different types of equations based on kinetic theory, diffusion theory, and empirical data. Equations have been derived for expressing the rate of evaporation of zinc and cadmium in both argon and helium as functions of temperature of the liquid zinc and cadmium. It was …

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Evaluation Of Zinc Sulphate Electrolytes Containing Certain Impurities And Additives By Cyclic Voltammetry, D. R. Fosnacht, Thomas J. O'Keefe Jul 1980

Evaluation Of Zinc Sulphate Electrolytes Containing Certain Impurities And Additives By Cyclic Voltammetry, D. R. Fosnacht, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

The polarization characteristics of acid zinc sulphate electrolytes containing various amounts of germanium and cobalt were examined by cyclic voltammetry. The effects of zinc and acid concentration, temperature, and surface preparation were also investigated. Small concentrations of impurities are shown to cause measurable changes in polarization behavior. Levels as low as 0.02 mgl-1 Ge and 0.1 mgl-1 Co can be detected using this technique. The actual mechanism of impurity behavior is more clearly delineated using this technique and evaluation of the data from these tests indicate that germanium and cobalt form local galvanic cells. The results of these short-term tests …

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Discussion Of "Gas Composition, Temperature, And Pressure Measurements In A Lead Blast Furnace", Arthur E. Morris, John R. Knoepke Jun 1980

Discussion Of "Gas Composition, Temperature, And Pressure Measurements In A Lead Blast Furnace", Arthur E. Morris, John R. Knoepke

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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The System Mgo‐Mgcl2‐H2o At 23°C, Ladawan Urwongse, Charles A. Sorrell Jan 1980

The System Mgo‐Mgcl2‐H2o At 23°C, Ladawan Urwongse, Charles A. Sorrell

Materials Science and Engineering Faculty Research & Creative Works

Solubilities of MgO in aqueous HC1 solutions at 23°±3°C were measured and combined with analyses of neat magnesium oxychloride cements, cured in sealed containers, to construct an equilibrium phase diagram for the system MgO‐MgCl2‐H2O. Specific gravities and acidities of solutions saturated with MgO and relative humidities of vapor phases over sealed samples were measured and combined with XRD data to define the compositions in equilibrium with two crystalline phases. Studies of relative reaction rates indicated that the 5–1–8 phase crystallizes more rapidly than the 3·1·8 phase and that cements near the 3·1·8 composition react rapidly with atmospheric CO …

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Phase Relations In Magnesium Oxysulfate Cements, Ladawan Urwongse, Charles A. Sorrell Jan 1980

Phase Relations In Magnesium Oxysulfate Cements, Ladawan Urwongse, Charles A. Sorrell

Materials Science and Engineering Faculty Research & Creative Works

Solubilities of MgO in H2SO4 solutions were measured and X‐ray analyses of over 100 neat cement samples were used to construct an isothermal phase diagram for the system MgO‐H2SO4‐H2O at 23°±3°C. The phases MgO, Mg(OH)2, 3Mg(OH)2 MgSO4·8H2O (3·1·8), MgSO4·7H2O, MgSO4·6H2O, and MgSO4·H2O were stable at 23°C. The phases Mg(OH)2· MgSO4·5H2O (1·1·5) and MgSO4·4H2O were observed but are considered to be metastable, resulting …

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Autooscillations And Nonlinear Anelasticity, Manfred Wuttig, Tetsuro Suzuki Jan 1980

Autooscillations And Nonlinear Anelasticity, Manfred Wuttig, Tetsuro Suzuki

Materials Science and Engineering Faculty Research & Creative Works

In conclusion it can be stated that a novel phenomenon, a mechanical auto oscillation, has been described theoretically and shown to exist experimentally. These auto oscillations occur when a nonlinear anelastic solid is forced into large amplitude oscillations in the vicinity of a martensitic transformation. They manifest themselves as a low frequency auto modulation of the a martensitic transformation. They manifest themselves as low frequency auto modulation of the forced vibration of such a solid. © 1980.

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An Experimental Study Of The Reactions Of Excited Neon Atoms In Pure Afterglow Plasmas Using Resonance Absorption Spectrometry, R. A. Sierra, J. Beverley Clark, A. J. Cunningham Dec 1979

An Experimental Study Of The Reactions Of Excited Neon Atoms In Pure Afterglow Plasmas Using Resonance Absorption Spectrometry, R. A. Sierra, J. Beverley Clark, A. J. Cunningham

Materials Science and Engineering Faculty Research & Creative Works

Resonance absorption spectrometry has been applied in a room temperature study of the reactions of excited neon atoms in pure afterglow plasmas. The pressure range 10-500 Torr was investigated. Lorentz broadened linewidths calculated using a simple classical interruption theory allowed fractional absorption signals as large as 98% to be analyzed and absolute excited-state concentrations to be determined. The first absorption studies of the decay of 1P1 excited atoms in neon afterglows are reported. Analysis of the decay profiles of the 3P2, 3P0 and 1P1 excited states allowed quenching rate coefficients for each state to be determined and the role of …

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Phase Equilibria For Iron-Rich Fe-Cu-C Alloys: 1500 To 950°C, Krishna Parameswaran, Kenneth Metz, Arthur E. Morris Dec 1979

Phase Equilibria For Iron-Rich Fe-Cu-C Alloys: 1500 To 950°C, Krishna Parameswaran, Kenneth Metz, Arthur E. Morris

Materials Science and Engineering Faculty Research & Creative Works

Isothermal sections for the iron rich corner of the Fe-Cu-C system have been constructed at 1500, 1450, 1200, 1172, 1150, 1000, and 950°C. A ternary invariant point exists at 1172°C where an iron rich liquid, a copper rich liquid, austenite, and graphite coexist. The iron rich liquid contains 3.7 wt pct Cu and 4.0 wt pct C. The austenite contains 7.3 pct Cu and 1.6 pct C. The copper rich liquid contains 2.4 pct Fe, and apparently very little carbon. The diagrams are used to explain the phenomena of "inverse segregation" that occurs during the solidification of iron rich Fe-Cu-C …

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Thermally Stimulated Polarization Current Technique For Measuring The Electrical Conductivity Of Vitreous Solids, Chi-Ming Hong, D. E. Day Jan 1979

Thermally Stimulated Polarization Current Technique For Measuring The Electrical Conductivity Of Vitreous Solids, Chi-Ming Hong, D. E. Day

Materials Science and Engineering Faculty Research & Creative Works

The electrical conductivity of glasses determined by TSPC agrees well with that measured by conventional ac or dc techniques. The TSPC technique is a rapid and easy method of measuring the dc conductivity over the range 10−15-10−7 (Ω cm)−1 and is especially suited for conductivities <10−12 (Ω cm)−1. Polarization at the electrodes is easily detected and avoided.

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Nonlinear Anelasticity And The Martensitic Transformation, Manfred Wuttig, Tetsuro Suzuki Jan 1979

Nonlinear Anelasticity And The Martensitic Transformation, Manfred Wuttig, Tetsuro Suzuki

Materials Science and Engineering Faculty Research & Creative Works

Zener's model of a standard linear solid is extended to include nonlinearities characteristic of metals and alloys in the vicinity of a martensitic transformation. The equation of motion of a nonlinear anelastic solid is derived and solved using van der Pol's method. The characteristics of the solutions indicate that auto-oscillations of finite amplitude can be excited externally. It is proposed that the streaming oscillations represent the beat between the external excitation and the auto-oscillation. © 1979.

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The Effect Of Antimony, Chloride Ion, And Glue On Copper Electrorefining, Thomas J. O'Keefe, L. R. Hurst Mar 1978

The Effect Of Antimony, Chloride Ion, And Glue On Copper Electrorefining, Thomas J. O'Keefe, L. R. Hurst

Materials Science and Engineering Faculty Research & Creative Works

A study has been made to determine the effect of antimony, chloride ion, and glue on copper electrorefining. All deposits were made at a temperature of 65° C on a titanium cathode. Current densities of 398 A m-2 and 133 A m-2 were used. The deposits were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) to determine morphology and crystal orientation. Atomic absorption (AA) and Auger spectroscopy (AES) were used to study the chemical composition of the deposits and a simple bend test was used to determine structural integrity. It was found that when the antimony concentration in …

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Discussion, Ronald A. Kohser Jan 1978

Discussion, Ronald A. Kohser

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Disk And Strip Forging With Side Surface Foldower: Part 2: Evaluation Of The Upper-Bound Solutions, Ronald A. Kohser, B. Avitzur Jan 1978

Disk And Strip Forging With Side Surface Foldower: Part 2: Evaluation Of The Upper-Bound Solutions, Ronald A. Kohser, B. Avitzur

Materials Science and Engineering Faculty Research & Creative Works

The upper-bound solutions developed in Part 1 are evaluated with regard to their ability to produce a lower value for required power (load, pressure, or work). Comparisons made with existing solutions such as the triangular field solution and one-zone bulge solution show that for strip, each solution has a domain of geometry and friction in which it is superior. The new solution produces a lower upper-bound for conditions of high interface, friction and relatively thin specimen, the area where fold over is the observed mode of flow. For solid cylindrical disks, the solution fails to improve upon existing analyses, but …

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Effect Of Collagen And Chloride Additions On Electrolytic Copper Deposits, William P. Lorenz, Thomas J. O'Keefe, Carlo B. Sonnino Jan 1978

Effect Of Collagen And Chloride Additions On Electrolytic Copper Deposits, William P. Lorenz, Thomas J. O'Keefe, Carlo B. Sonnino

Materials Science and Engineering Faculty Research & Creative Works

The effects of collagen concentration and molecular weight on the morphology and crystal orientation of electrolytic copper deposits have been determined and compared. The effect of chlorides in the presence of collagen on the above properties has also been investigated. Three different molecular weight collagens were studied and the consumption rate of each was determined by chemical analysis of the electrolyte before and after electrodeposition. Two-hour deposits were made in an electrolyte containing the subject collagens in concentrations ranging from 1.2 to 38.4 mg 1-1. Scanning electron and light microscopes and X-ray diffraction were used to evaluate the electrodeposits. © …

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