Materials Science and Engineering Commons^™

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 …

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 …

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 …

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 …

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.

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

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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 …

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 …

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. …

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 …

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 …

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.

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. …

Amine Flotation Of Feldspar From Magnetite Concentrate., Gary William Hudiburgh Jr.

Masters Theses

"The gangue in some magnetite ore bodies contains feldspar; the alkali content of the feldspar reduces the usefulness of these iron ores. One method of decreasing the feldspar content in magnetite concentrate is froth flotation.

The amine flotation of feldspar from magnetite concentrate was investigated using zeta potential measurements, Hallimond tube flotation tests and laboratory-scale flotation tests. The zeta potential of various feldspars (microcline, albite, anorthite, oligoclase and anorthoclase) were determined as a function of pH; the point of zero charge ranged from pH 1.4 to 2.5. Hallimond tube flotation tests using two amine reagents were conducted on the feldspars. …

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 …

Effect Of Nodule Count And Cooling Rate On The Matrix Of Nodular Iron., Subrata Sen Gupta

Masters Theses

"The objective of this investigation was to establish the relationship between the nodule count, the matrix structure, and the cooling rate through the eutectoid in nodular iron. The chemical composition of the nodular iron was held constant while various inoculation methods, inoculants, and mold designs, including chills, were used to vary the solidification time and cooling rate through the eutectoid range. This produced variations in both the matrix structure and the nodule count.

The nodule count has a power relationship with the percent pearlite in the matrix at fixed cooling rates: Percent pearlite = K (Nodule count)^-n where the …

Determination Of Oxygen Chemical Diffusion Coefficients In Single Crystal Strontium Titanate By Capacitance Manometry, Douglas Bugh Schwarz

Masters Theses

"The use of the tensi-volumetric apparatus to study the non-stoichiometric behavior of strontium titanate was discussed. Oxidation kinetics of reduced single crystal strontium titanate were measured with an ultrasensitive capacitance manometer as the sample absorbed oxygen in response to a changing oxygen activity.

The oxidation kinetics were found to fit a solution to Fick's second law for rectangularly shaped samples....

The procedure selected for measurement of the oxidation kinetics, and the method of obtaining diffusion coefficients from the oxidation data was discussed along with potential sources of error of the system"--Abstract, page ii.

Synthesis Of Fused Silica By Flame Hydrolysis, James Edward Rourke

Masters Theses

"Apparatus to synthesize and dope high purity, optical quality fused silica by flame hydrolysis was constructed. Fused silica samples containing 0, <35, 35 and 90 ppm niobium were synthesized and characterized by the following properties: purity, refractive index, radiation damage resistance, and transmission spectra. The properties of the undoped sample were shown to be comparable to those of available commercial fused silica. Deviations in the properties of the doped samples from those of the undoped samples were explained in terms of the niobium content"--Abstract, page ii.

Film Formation On Anodically Polarized Lead, H. Vaidyanathan, Ram A. Narasagoudar, Thomas J. O'Keefe, William Joseph James, James W. Johnson

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Solid Transformations And Premelting Phenomena In Fluorite Structures And The System Srcl₂Bacl₂, Damri Sukhotanang

Doctoral Dissertations

"Thermal expansion and phase transformations in CaF₂, BaF₂, SrCl₂, and BaCl₂ were studied by high temperature x-ray diffractometry, differential thermal analysis, and thermodilatometric analysis. Thermal expansion characteristics of CaF₂, BaF₂ and SrCl₂ are very similar. The structures expand normally at lower temperatures and depart substantially from linearity at higher temperatures, because of formation of defects and disordering of anions. At high temperatures CaF₂ and BaF₂ react with water vapor, even at low humidities, forming oxides and emitting HF, leading to difficulty in observation of phase transformations. SrCl …

A Mass Spectrometric Study Of Positive Ions Produced In An Experimental Diode, L. A. Addington, Gordon Lewis

Materials Science and Engineering Faculty Research & Creative Works

A simple diode ion source has been developed for direct observation in a mass spectrometer of the positive ions created in an operating diode. The ionic species accelerated toward the cathode were identified. The shape of the peak displayed in the spectrum is related to the region of the diode in which the ions were formed. Variation of experimental parameters, including the composition of the background gases, indicated that the characteristic shapes of the peaks can be related to space charge in the diode. This is complicated by the tendency of some of the species to fragment and further work …

Kiss Gating In Sand-Cast Aluminum Alloys., Michael Lynn Holt

Masters Theses

"This thesis describes the optimum conditions necessary for the production of macrosound plate castings of sand-cast aluminum alloys by the kiss gating process. Castings of alloys of different freezing ranges in the Al-Si-Cu system (alloys 195, 319, 380, and 384) were produced and examined visually to evaluate the effectiveness of various gating systems and superheats on the production of macrosound castings.

For the aluminum alloys used in this investigation, the optimum conditions leading to the production of macrosound castings without the use of risers are one or a combination of the following: (l) wider freezing ranges; (2) pressurized gating systems; …

Field Emission Of Boron On Tungsten, P. D. Ownby, Thomas A. Flaim

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Magnetic Properties Of Cadmium Manganese Ferrite, B. W. Jong, P. D. Ownby

Materials Science and Engineering Faculty Research & Creative Works

The room-temperature saturation magnetization of CdxMn1-xFe2O4 decreased with increasing cadmium concentration. When 0 < x < 0.5, the decrease in saturation magnetization was due to the increase in the amount of non-mgnetic distorted cubic Cd(Mn, Fe) 2O4.

Thermal Decomposition Of Boron Triiodide On Molybdenum Field Emitter Surfaces, Richard E. Moore, P. Darrell Ownby

Materials Science and Engineering Faculty Research & Creative Works

Boron has been adsorbed onto molybdenum field emitter surfaces by the thermal decomposition of boron triiodide at corrected partial pressures of 1.4 x 10-9 Torr to 4.5 x 10-9 Torr. Based on field emission work function data and an analytical work function versus adsorbate-coverage relationship, a quantitative measure of the monolayer coverage of boron on molybdenum has been determined; this value is 6.3 x 1014 atoms/cm2/monolayer. A parameter, β, is defined which is a measure of the effective yield of adsorbed boron on molyb-denum from BI3. β is formulated in terms of the free energy of dissociation of the BI3 …

Electronic Contribution To The Entropy Of Solution, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.