Engineering Commons^™

Silver Centers Induced In Borate Glasses: Esr And Optical Studies, Hadia El Zayyat

Archived Theses and Dissertations

No abstract provided.

A Method For Improving The Accuracy In Phase Change Heat Transfer Data Through Increased Precision In Thermophysical Property Determinations, John Philip Drummond

Mechanical & Aerospace Engineering Theses & Dissertations

Wind tunnel model materials typically have thermophysical properties that vary with both position and temperature. A numerical study using a finite difference representation of the heat conduction equation has been performed on several of these model materials to determine their thermal response under a specified heat loading. This study has confirmed the feasibility of using an effective thermophysical property to account for the existence of variable thermal properties when a model undergoes aero­ dynamic heating. The effective property, when used in the reduction of phase-change heat transfer data, forced agreement of the actual transient behavior of a model with the …

Some Structural Aspects Of Ni2+ In Potassium Haloborate Glasses, Samia Sidhom

Archived Theses and Dissertations

No abstract provided.

Subsolidus Equilibria And Metastable Phase Development In The System Zro₂-Al₂O₃-Sio₂, Charles Christopher Sorrell

Bachelors Theses

"Subsolidus equilibria in the low silica portion of the system ZrO₂-Al₂O₃-SiO₂ were studied by X-ray diffraction of quenched samples fired at 1300°, 1400°, and 1480°C. Samples prepared as powders from combinations of a-Al₂O₃, Al(OH)₃, silicic acid, ZrO₂, and kaolinite reacted very slowly at 1300° and 1400°C and the trends toward equilibria are not apparent. A mixture of zircon and Al(OH)₃ reacted slowly at 1480°C to form mullite and ZrO₂, indicating that the latter phases are the stable assemblage rather than zircon and alumina. A gel prepared from aluminum nitrate, zirconyl nitrate, and colloidal silica reacted at 1480°C to form alumina, …

Analogy Between Spinodal Decomposition And Martensitic Transformation, Tetsuro Suzuki, Manfred Wuttig

Physics Faculty Research & Creative Works

The translation of the theory developed for the spinodal decomposition of a supercooled alloy to the language appropriate for the martensitic transformation is carried out. In the spinodal theory, the stability of the alloy with respect to the composition fluctuation is examined, while in the present theory the stability of the crystal with respect to the shear displacement fluctuation, the transverse phonon, is studied. The analogy to the spinodal theory requires the revival of the strain gradient energy term or the couple stress term, the presence of which has been a subject of controversies for a long time since Laval. …

Electroless And Chemical Metal Deposition On Human Tooth Enamel., Richard Doyle Christie

Masters Theses

"Initial investigations have confirmed the feasibility of depositing an adherent metal film onto tooth enamel. Such films might be used as pit and fissure sealants in preventive dentistry, with denture or orthodontic work, as an intermediate substrate with various organic or inorganic restorative materials, or other such areas. The process employs chemical solutions containing ions of the metal to be deposited and suitable reducing agent solutions.

To date, metallic copper and silver films have been plated onto teeth in vitro. The deposits are quite adherent and appear to exhibit the conductivity, crystal structure, luster, hardness, and other chemical and physical …

The Influence Of Oxygen Activity On Sintering Of Strontium Doped Lanthanum Chromite., Leslie Groupp

Masters Theses

"The influence of oxygen activity upon the sintering of lanthanum chromite (La_1-xSr_x CrO₃) with x ranging from Oto 0.2 was investigated using chemically prepared powders of <0.1 microns particle size. The results show that at a temperature of 1740 ° C densities of >92% of theoretical could be achieved if the oxygen activities were maintained in the 10^-11 to 10^-12 atm. range. If oxygen activity exceeds 10^-10 atm., densities of not >80% theoretical could be obtained. For the compositions studied, room temperature X-ray analysis of both the starting powders and sintered compacts show the compositions to be orthorhombic and single phase. The ambient lattice parameters and resistivity measurements decreased …

Variables Affecting The Rate Of Solution Of Mold Inoculants In Cast Iron, Jose Osorno Fonnegra

Masters Theses

"The purpose of this investigation was to measure the effectiveness of an inoculant alloy reacting with molten cast iron in a reaction chamber properly located in the gating system.

The chemical composition of the gray iron was held constant while several metallurgical factors were varied to produce test samples with different cementite thicknesses. These chill depths were measured as an indication of the inoculation effectiveness.

Appreciable differences in chilling tendency were observed within the different variables studied. The results indicate that pouring temperature, as well as the other variables studied, are of considerable importance when dealing with inoculation of gray …

Effect Of Temperature, Aging, And Composition On Phase Development In The System Al₂O₃-P₂O₅-H₂0., John Allan Middleton

Masters Theses

The chemical and physical conditions for the formation of various phases of aluminum phosphate were studied. Mixtures of Al₂O₃ and H₃PO₄ were aged in sealed containers and examined for phase development by X-ray diffraction. The results revealed the aging of samples to be a critical process for the formation of equilibrium phase assemblages at low temperatures, Initial composition becomes important as equilibrium is neared and at elevated temperatures when the molar ratios of Al₂O₃, P₂O₅, and H₂O determine what phases will be formed. Temperature …

Characterization Of Two Mexican Raw Dolomites For Refractory Brick Production, Rodolfo Trevino Cantu

Masters Theses

"Two Mexican dolomites were characterized in order to discover their suitability for production of refractory brick.

The results were compared with other dolomites from American Companies. Some samples were burned in a gas fired Laboratory Furnace and others were obtained in the burned state after processing in Industrial Rotary Kilns.

The characterization procedures included X-Ray Diffraction, Scanning Auger Microprobe, DTA and TGA techniques, Chemical Analysis and Bulk Density measurements.

The procedure to control the quality of the dead-burned dolomite at the industrial level was established taking as the main criteria, bulk density, hydration susceptibility, and impurity levels"--Abstract, page ii.

Ionic Thermal Current In Sodium-Rubidium Silicate Glasses., Chi-Ming Hong

Masters Theses

"The ionic thermal current (ITC) method has been employed to study alkali ion motion in a sodium silicate glass and two sodium-rubidium silicate glasses over the temperature range 110 ° K to 400 ° K. T wo peaks and three peaks were observed in a l.0Na₂O-3.0SiO₂ glass and a 0.75Na₂O-0.25Rb₂O-3.0SiO₂ glass, respectively. Only one peak and a high temperature shoulder were observed in the 0.50Na₂O-0.50Rb₂O-3.0SiO₂ glass. These peaks were attributed to orientation and space charge polarization with each peak associated with a particular movement of the sodium …

The Spheriodization Of Tool Steels., Siri Ram Rai

Masters Theses

"Four different tool steels--AISI 01, Sl, A9 and Tl5--were obtained in the 1/2-inch diameter hot rolled and air-cooled condition from the steel mill. The lower critical temperatures of these steels were determined. The spheroidization of each steel by three different spheroidizing procedures was evaluated with the use of hardness testing and metallographic techniques. Isothermal annealing completely spheroidized each steel yielding coarse carbides and low hardness. Cyclic annealing was an effective spheroidization procedure only for 01 and Tl5 steels. Hardening and tempering resulted in rather fine spheroidized structures in these steels. The total time consumed to produce the best spheroidized structures …

Phase Equilibria Near The Solidus Temperature For Iron-Rich Fe-Cu-C Alloys., Kenneth L. Metz Jr.

Masters Theses

"The effect of copper on the solidification temperature of graphite-saturated iron-rich alloys was determined with the use of cooling curves. The ternary invariant temperature for the alloy was found to be 1172°c with the use of heating curves. At 1172°c, graphite, austenite, an iron rich liquid, and a copper-rich liquid are in equilibrium. The composition of the metallic phases was determined by weight gain, chemical analysis, and the electron microprobe. In addition, the composition of the iron-rich liquid was calculated from thermodynamic data. Isothermal sections of the iron-rich corner of the system were constructed for several temperatures in the range …

Computation Of Potential And Potential Gradient Around Bundled Conductors, Mamdouh Hossny Ibrahim

Archived Theses and Dissertations

No abstract provided.

Crystallization Of A Tetrasilicic Fluormica Glass, W. H. Daniels, Robert E. Moore

Materials Science and Engineering Faculty Research & Creative Works

The crystallization of a tetrasilicic synthetic mica glass of nominal composition K2Mg5Si8O20F4 was investigated at selected temperatures from 560° to 1150°C using DTA, density measurements, electron microscopy, and X‐ray diffraction techniques. Crystallization is shown to occur in 2 stages. (1) Initial structural ordering occurs at ∼600°C, as indicated by a strongly exothermic reaction, an increase in density, and the appearance of X‐ray diffraction lines. (This transformation temperature is related to fluorine content.) (2) The crystal morphology of the glass‐ceramic changes at 900° to 1150°C. A mechanism is proposed for the transformation from amorphous to crystalline structure in this synthetic mica …

Determination Of Oxygen Chemical Diffusion Coefficients In Single Crystal Srtio By Capacitance Manometry, D. B. Schwarz, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The oxidation kinetics of a single crystal of SrTiOs were measured with a tensivolumetric system over the temperature range 700 -975 at 0.03 atm oxygen pressure. The oxidation was found to be oxygen diffusion limited with an activation energy of 14.9 - 1.3 kcal/mole. Combining the kinetic data with relative defect concentration data yielded an activation energy for oxygen self-diffusion of 57 - 16 kcal/mole. The enthalpy of formation of doubly ionized oxygen vacancies was calculated to be 126 - 13 kcal/mol. © 1975, The Electrochemical Society, Inc. All rights reserved.

Mechanism Of Uai3 To Uai4 Transformation, Ling Ping Lee, Hollis P. Leighly

Materials Science and Engineering Faculty Research & Creative Works

The compound, UA14, which forms during the peritectic reaction (Liquid + UA13 → UAI4), has a long needlelike shape and reveals the characteristic morphology of a fishtail when cut along the long axis. When cut perpendicular to the long axis, it shows an internal core of another phase, which has been identified as a primary aluminum solid solution. Because of the interesting relationship between the crystallographic structures of UA13 and UA14, the peculiar UA14 morphology can be explained on the basis of a proposed mechanism. The mechanism of UA13 to UA14 transformation has been identified as shear and diffusion controlled …

Moiré Simulation Of Field-Ion Micrographs, P. D. Ownby, Robert M. Doerr

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Characterization Of Heat-Treated Nickel And Gold Films On Silicon Single Crystals, Ki Hyun Yoon

Doctoral Dissertations

"An experimental electron impact ionization source was used to determine the presence of various neutral atoms and molecules on metallized and bare surfaces of silicon wafers. The metallization consisted of thin films of nicke l and gold separately and in combination. The major surface contaminates on all samples were found to be F, Na, Cl, K, CO, and CO₂. The surface concentration of these species was found to be sensitive to the sample temperature up to 550 °C, the maximum temperature used in this study.

In the course of the mass spectrometric study, it was found that crystallites …

Application Of Voltammetry To Copper Electrodeposition, Louis Francis Toth Jr.

Doctoral Dissertations

"A study was undertaken to determine the feasibility of using voltammetry and scanning electron microscopy techniques to characterize copper deposition from an acid-sulfate electrolyte. The main process variables investigated were temperature and addition agents (chloride ion, glue, separan or thiourea) at different concentrations, over a range of current densities. Cathodes employed were either polycrystalline titanium or copper. Some long-time copper deposits were also made using Ti cathodes and the orientations of these deposits were determined by x-ray diffraction.

Observations of copper crystals produced during voltammetry scans, on a Ti cathode, indicated that a characteristic morphology was associated with each type …

Corrosion And Electrochemical Behavior Of Indium And Indium-Bismuth Alloys In Hydrochloric Acid, Yar Ming Wang

Doctoral Dissertations

"The corrosion of In-Bi alloys was studied using X-ray, scanning electron microscopy, atomic absorption spectroscopy, and cyclic voltammetry techniques.

Calculated activation energy values indicated that the corrosion of In-Bi alloys was activation controlled. The effect of amine mixtures on the corrosion of In and In₂Bi (ß₁ phase) was studied. Morphological studies revealed that the porosity of the resulting physical surface structure was influential in determining the corrosion rate. In deaerated 3N HCl solutions, the selective dissolution of indium was the predominant mechanism in the corrosion of In-Bi alloys. The corrosion was always accompanied by a phase change …

X-Ray Powder Data And Unit Cell Parameters Of Mgbr2.6h2o, Charles A. Sorrell, Roy R. Ramey

Materials Science and Engineering Faculty Research & Creative Works

Detailed X-ray powder data for MgBr2·6H2O were obtained by diffractometry by use of CuKα radiation at 22°C. The data were indexed on a bimolecular monoclinic unit cell, space group C2/m, with a = 10.290 ± 0.001 Å; b = 7.334 ± 0.001 Å; C = 6.211 ± 0.001 Å; β = 93° 25′ ± 10′. Calculated density was 2.074 g/cm3, compared with a measured density of 2.07 ± 0.01 g/cm3. © 1974, American Chemical Society. All rights reserved.

16th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Final program and abstracts from the 16th annual meeting of the Rocky Mountain Spectroscopy Conference, sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, August 5-6, 1974.

An Automatic Rinse Tank Controller For Industrial Applications, Aliasghar Emami

Dissertations and Theses

This thesis describes an automatic Rinse Tank Control System used in detection and removal of contaminating agents from industrial plating rinse tanks. It automatically monitors the purity of the rinse water in sixteen separate rinse tanks, and permits fresh water to enter the tanks only when the conductivity of the rinse water in each tank exceeds a predetermined level. Its use will result in large savings in consumption of fresh water and the subsequent reduction in discharge of effluent to the treatment plants.

A Microscopy Study Of Lead Sinter, Thomas J. O'Keefe, C. Bennett, E. R. Cole

Materials Science and Engineering Faculty Research & Creative Works

Samples of up-draft sinters produced at three different Missouri lead smelters were studied, to determine the chemical phases present, as a first step toward a more complete understanding of the lead blast furnace operation. The sinters seemed to be basically similar, and all the results reported are from samples from one smelter (Herculaneum smelter, St. Joe Minerals). Analytical tools used included the electron microprobe and scanning electron microscope with a non-dispersive X-ray spectrometer attachment Major phase that were positively identified are metallic lead, lead sulfide and zinc ferrite. The predominant lead phase was tentatively identified as a lead oxide-silicate compound. …

Phase Equilibria And Transformations In Potassium Sulfate, Chromate, Molybdate, And Tungstate, Roy Richard Ramey

Doctoral Dissertations

"Thermal expansion and transformations of K₂SO₄, K₂CrO₄, K₂MoO₄, and K₂WO₄ were studied by high temperature diffractometry, differential thermal analysis, and dilatometry. K₂SO₄ and K₂CrO₄ transform from an orthorhombic to a hexagonal structure at 580°C and 670°C respectively, with initiation of the transformation probably related to increased amplitude of S-O tetrahedral vibrations. K₂MoO₄ and K₂WO₄ transform from a monoclinic to an orthorhombic structure at 300° and 370°C respectively. A minor K₂MoO_{4 …}

The Morphology Of Cellular Precipitation In Magnesium Rich Magnesium-Aluminum Alloys, Jyong Shi Cho

Doctoral Dissertations

"The morphology of cellular precipitation in a Mg-9wt. %AI alloy has been investigated by light and electron microscopy. A study of the early stages of the cellular precipitation process indicated that cellular precipitate structure forms in Mg-Al alloys by Fournelle and Clark mechanism. "Replacive" motion indicative of the Tu and Turnbull mechanism for cellular precipitation was not seen"--Abstract, page 1.

Esca Characterization Of Flotation Products From A Lead-Zinc-Copper Concentrator On The New Lead Belt Of Southeast Missouri., Kevin Leroy Purdy

Masters Theses

"Electron spectroscopy for chemical analysis (ESCA) was used to determine the surface characteristics of products from an operating Pb-Zn-Cu concentrator on the New Lead Belt of southeast Missouri and pure galena and sphalerite samples treated with flotation reagents in concentrations similar to those used in the mills. The emphasis was on the action of surface modifiers such as Na₂Cr₂O7, starch, SO₂, CuSO₄ and NaCN in sphalerite flotation and in the galena-chalcopyrite separation. The objective of the investigation was to monitor the relative oxidation states of the mineral and reagent constituents and correlate these …

A Study Of The Feasibility In Obtaining The Kinetics Of Various Ordering Phenomena Of The Iron Aluminum System Utilizing The Mössbauer Effect, Lloyd Rollan Chapman

Masters Theses

"The determination of the kinetics of ordering for various ordering phenomena of the Iron-Aluminum system utilizing exclusively the Mössbauer effect technique is shown to be infeasible for all but a highly restrictive consideration from experimental as well as theoretical evidence. Also, the possible use of the Mössbauer effect for the analysis of other ordered systems is discussed.

An alternative method for the acquisition of the needed information utilizing diffraction and Mossbauer techniques is presented recognizing the need for a computer fitting analysis of the complex Mössbauer effect spectra. However, at this stage of investigation, no experimental work has been performed …

Detection Of Impurities In Zinc Sulfate Electrolytes By Cyclic Voltammetry Techniques., Bruce Alan Lamping

Masters Theses

"A cyclic voltammetric technique has been developed for quantitatively detecting the presence of active chemical species present in zinc sulfate electrolytes. The experimental apparatus consisted of a pyrex "H" cell, an Al cathode encased in a Teflon holder, a carbon anode and a mercurous sulfate reference electrode. Voltammograms were obtained from industrial, purified neutral leach solution (Cominco Ltd., Trail, B.C.) acidified to give a final concentration of 0.77 M Zn⁺⁺, 1 M H₂SO₄. The polarization curves were then evaluated and used as a reference standard to compare with results obtained when various organic and …