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Articles 181 - 210 of 249
Full-Text Articles in Metallurgy
South East Missouri Lead Belt - A Review 1987, Johh L. Watson
South East Missouri Lead Belt - A Review 1987, Johh L. Watson
Materials Science and Engineering Faculty Research & Creative Works
The south-east Missouri Lead Belt is, and has been for many years, a major world producer of lead concentrate. This paper reviews the current mill operations in the area and presents detailed information on equipment, operating parameters and metallurgical performance. © 1988.
Nucleation And Growth Of Zinc Electrodeposited From Acidic Zinc Solutions, A. C. Beshore, B. J. Flori, G. Schade, Thomas J. O'Keefe
Nucleation And Growth Of Zinc Electrodeposited From Acidic Zinc Solutions, A. C. Beshore, B. J. Flori, G. Schade, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
The nucleation and initial crystal growth kinetics by electrodeposition from acidic zinc solutions was studied in the absence and presence of antimony and glue on a glassy carbon electrode. Zinc exhibits instantaneous nucleation under the experimental conditions employed in the potential region from -1600 to -2000 mV (mercurous sulphate reference). At low overpotentials antimony and glue increase the number of nuclei. © 1987 Chapman and Hall Ltd.
Calculation Of Mass Transfer Coefficients In Metal Deposition Using Electrochemical Tracer Techniques, Thomas J. O'Keefe, J. S. Cuzmar, S. F. Chen
Calculation Of Mass Transfer Coefficients In Metal Deposition Using Electrochemical Tracer Techniques, Thomas J. O'Keefe, J. S. Cuzmar, S. F. Chen
Materials Science and Engineering Faculty Research & Creative Works
A modification of the tracer technique of Ettel has been developed for determining mass-transfer coefficients in electrolytes for both electrowinning and electrorefining systems. The method involves the direct measurement of the limiting current density of a more noble tracer ion at low concentration by cyclic voltammetry techniques in an electrolyte of choice. A Ag+tracer in acid copper sulfate is used as the example. Additional tests were made by code positing the tracer with copper to compare the results of the two methods. The effect of copper ion concentration and temperature on the electrochemical and transport properties of the solution were …
The Mg-Sb System, A. A. Nayeb-Hashemi, J. Beverley Clark
The Mg-Sb System, A. A. Nayeb-Hashemi, J. Beverley Clark
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.
Electrochemical Monitoring Of Electrogalvanizing Solutions, Thomas J. O'Keefe, S. F. Chen, E. R. Cole, M. Dattilo
Electrochemical Monitoring Of Electrogalvanizing Solutions, Thomas J. O'Keefe, S. F. Chen, E. R. Cole, M. Dattilo
Materials Science and Engineering Faculty Research & Creative Works
The corrosion resistance of steel is vastly improved when a zinc cathodic protective layer is applied. In recent years there has been renewed interest in producing this galvanized coating electrolytically. As with many deposition processes, the control of the operating parameters is very important in order to produce good quality zinc coatings. The homogeneity, ductility and smoothness of the zinc layer are critical. These factors are usually influenced by the electrochemical nature of the solution and organic additives are often used to assist in control. Studies on the polarization behavior of solutions for electro galvanizing electrolytes were made. Cyclic voltammetry …
Screening Design Test For Cyclic Voltammetric Evaluation Of Zinc Sulfate Electrolyte, R. K. Singh, Thomas J. O'Keefe
Screening Design Test For Cyclic Voltammetric Evaluation Of Zinc Sulfate Electrolyte, R. K. Singh, Thomas J. O'Keefe
Materials Science and Engineering Faculty Research & Creative Works
A statistical screening design program was conducted to determine the effects of certain operating parameters in the cyclic voltametric evaluation of zinc sulfate electrolyte. The variables studied included solution temperature, sulfuric acid and zinc concentrations, and scan rate. Solution temperature was found to be the most significant factor affecting the initial potential, followed by scan rate and zinc concentration. Based on screening design data, mathematical equations were developed to predict polarization behavior of addition-free zinc sulfate electrolytes. A few preliminary tests on the effect of impurities and organic additives, such as Sb(III) and glue, on potential, deposit morphology, and crystal …
The Oxidation Of Dilute Alloys Of Magnesium In Aluminium, Hollis P. Leighly, A. Alam
The Oxidation Of Dilute Alloys Of Magnesium In Aluminium, Hollis P. Leighly, A. Alam
Materials Science and Engineering Faculty Research & Creative Works
The oxide layers developed during the oxidation of aluminum alloys containing 500 and 1000 PPM of magnesium at 850K were examined with the aid of electron spectroscopy for chemical analysis. The magnesium content of the oxide layers was relatively high because of the preferential depletion of the magnesium atoms from the base alloys. Near the outer surfaces of the oxide layers, spinel (MgAl2O4) was the predominant magnesium-bearing compound. At depth, MgO was more dominant. The preferential depletion of magnesium from the alloys injected vacancies into the material. This led to the formation of defect clusters. The presence of these defect …
Dynamics Of Twinning In Natural Α-Quartz, Alexander Aning, Manfred Wuttig
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 …
Dynamics Of Stress Induced Hydride Formation In Vanadium, Alex Aning, Manfred Wuttig
Dynamics Of Stress Induced Hydride Formation In Vanadium, Alex Aning, Manfred Wuttig
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.
The Effects Of Certain Impurities And Their Interactions On Zinc Electrowinning, Donald R. Fosnacht, Thomas J. O'Keefe
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 …
Screening Design Test For Cobalt Cementation From Zinc Electrolyte, Mark S. Blaser, Thomas J. O'Keefe
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.
Comments On A Paper By Baik And Raj, Hollis P. Leighly
Comments On A Paper By Baik And Raj, Hollis P. Leighly
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.
Twinning Pseudoelasticity In Intl, Manfred Wuttig, Lin Chun-Hung
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 …
Anomalous Diffusion Of Carbon In A 70/30 Iron-Nickel Alloy, L. R. Chapman, D. A. Powers, Manfred Wuttig
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.
Model For Evaporation Of A Grain‐Boundary Phase, Manfred Wuttig, Harlan U. Anderson
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
Autooscillations In Zinc, Manfred Wuttig, Alex Aning, Tetsuro Suzuki
Autooscillations In Zinc, Manfred Wuttig, Alex Aning, Tetsuro Suzuki
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.
The Inert Gas Effect On The Rate Of Evaporation Of Zinc And Cadmium, P. C.S. Wu, Thomas J. O'Keefe, Fred Kisslinger
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 …
Evaluation Of Zinc Sulphate Electrolytes Containing Certain Impurities And Additives By Cyclic Voltammetry, D. R. Fosnacht, Thomas J. O'Keefe
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 …
Autooscillations And Nonlinear Anelasticity, Manfred Wuttig, Tetsuro Suzuki
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.
Phase Equilibria For Iron-Rich Fe-Cu-C Alloys: 1500 To 950°C, Krishna Parameswaran, Kenneth Metz, Arthur E. Morris
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 …
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
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 …
Nonlinear Anelasticity And The Martensitic Transformation, Manfred Wuttig, Tetsuro Suzuki
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.
The Effect Of Antimony, Chloride Ion, And Glue On Copper Electrorefining, Thomas J. O'Keefe, L. R. Hurst
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 …
Disk And Strip Forging With Side Surface Foldower: Part 2: Evaluation Of The Upper-Bound Solutions, Ronald A. Kohser, B. Avitzur
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 …
Effect Of Collagen And Chloride Additions On Electrolytic Copper Deposits, William P. Lorenz, Thomas J. O'Keefe, Carlo B. Sonnino
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. © …
Discussion, Ronald A. Kohser
Discussion, Ronald A. Kohser
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.
Evaluation Of Organic Additives For Use In Zinc Electrowinning, R. C. Kerby, H. E. Jackson, Thomas J. O'Keefe, Yar Ming Wang
Evaluation Of Organic Additives For Use In Zinc Electrowinning, R. C. Kerby, H. E. Jackson, Thomas J. O'Keefe, Yar Ming Wang
Materials Science and Engineering Faculty Research & Creative Works
Organic additives are used extensively in zinc electrowinning to assist in controlling the process. A cyclic voltammetry technique has been developed to provide a rapid, quantitative evaluation of the effectiveness of selected organic additives in minimizing the deleterious effects that impurities, such as antimony, have on zinc deposition. Results have indicated that animal glues are more effective than the other organic additives tested, which included several gums, enzymes, and amino acids, in relation to the current efficiency of zinc production. Of the various animal glues compared in this research, the most effective appeared to have average molecular weights in the …
Evaluation Of Organic Additives For Use In Zinc Electrowinning, R. C. Kerby, H. E. Jackson, Thomas J. O'Keefe, Yar Ming Wang
Evaluation Of Organic Additives For Use In Zinc Electrowinning, R. C. Kerby, H. E. Jackson, Thomas J. O'Keefe, Yar Ming Wang
Materials Science and Engineering Faculty Research & Creative Works
Organic additives are used extensively in zinc electrowinning to assist in controlling the process. A cyclic voltammetry technique has been developed to provide a rapid, quantitative evaluation of the effectiveness of selected organic additives in minimizing the deleterious effects that impurities, such as antimony, have on zinc deposition. Results have indicated that animal glues are more effective than the other organic additives tested, which included several gums, enzymes, and amino acids, in relation to the current efficiency of zinc production. Of the various animal glues compared in this research, the most effective appeared to have average molecular weights in the …
Positron Lifetime As A Function Of Grain Size, Hollis P. Leighly
Positron Lifetime As A Function Of Grain Size, Hollis P. Leighly
Materials Science and Engineering Faculty Research & Creative Works
Published data on positron annihilation lifetime in copper as a function of grain size have been analyzed to show that there is a linear relationship between the internal grain boundary surface area, per unit volume, S v, and the positron lifetime, τ. The analysis indicates that grain boundaries are important in the trapping of positrons. It is suggested that the slope of the resulting straight line, dS v/dτ, can be used to determine the annihilation rate of the grain boundaries. © 1977 Springer-Verlag.
Low Order Correction For Subsurface Contributions In Diffusion Experiments, D. Powers, Manfred Wuttig
Low Order Correction For Subsurface Contributions In Diffusion Experiments, D. Powers, Manfred Wuttig
Materials Science and Engineering Faculty Research & Creative Works
No abstract provided.