Engineering Commons^™

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. …

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; …

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 …

Effect Of Dissolved Water On Physical Properties Of Silver Borate Glasses, E Richard Reynolds

Masters Theses

"The effect of dissolved water on borate glasses containing 4-20 mol % Ag₂O was investigated. Water was dissolved in the glasses by bubbling with a carrier gas (oxygen) containing different partial pressures of water vapor. A minimum in water solubility was found at 11 mol % Ag₂O. Water contents in excess of 0.5 mol % H₂O did not have a great effect on the transition temperature or the dilatometric softening point. Below 15 mol % Ag₂O, the water content had no effect on the thermal expansion coefficients. Beyond 15 mol % Ag …

Magnetostrictive Aftereffects In A Dilute 50fe-50ni-C Alloy, Raj N. Master

Masters Theses

"Crystallographically equivalent interstitial sites are energetically equivalent when the host crystal is free of any fields. This situation is shown in Fig. Pl from which it may be appreciated that the difference of the free energy of the "crystal" with an interstitial "I" located in "x" and "y" sites, respectively, is equal to zero. This energy equivalence of the various interstitial sites is destroyed when the host crystal is subjected to fields such as strain fields, magnetization fields or a combination of both as may be appreciated from Figs. P2 through P4. In this case, the interstitials will preferentially occupy …

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.

Knudsen Effusion Study Of The Vaporization Of Cdo(S), R. Tom Coyle, Gordon Lewis

Materials Science and Engineering Faculty Research & Creative Works

Knudsen effusion studies were conducted on CdO(s) in fused‐SiO2 Knudsen cells from 889 to 1110 K. The orifice size was varied; the largest cell orifice yielded a calculated pressure significantly lower than could be accounted for by experimental error. Average‐slope‐ and average‐free‐energy‐function‐based values of ΔHc298 were 86.9 ± 1.1 and 88.8 ± 0.5 kcal/mol, respectively. The data from the present work were combined with those of previous investigators using a method discussed by McCreary and Thorn; a ΔHc298 of 88.2 ± 0.2 kcal/mol was obtained. Using this combined value for ΔHc298 and ΔSc298= 51.40 ± 0.1 eu (obtained from the …

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.

Magnetostrictive Aftereffect In A Dilute 50fe-50ni-C Alloy, Raj Master, Manfred Wuttig

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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 …

Influence Of Oxygen Activity On The Sintering Of Mgcr2o4, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The sintering behavior of MgCr2O4 powder compacts was investigated as a function of temperature, time, and oxygen activity. The results show that MgCr2O4 cannot be densified to >70% of theoretical density at temperatures up to 1700°C if the oxygen activity exceeds 10−6 atm. The oxygen activity must be decreased to <10−10 atm before densities exceeding 90% of theoretical can be achieved. Weight loss and X‐ray data indicated that maximum density occurred at an oxygen activity just above that where MgCr2O4 becomes unstable. Copyright © 1974, Wiley Blackwell. All rights reserved

X-Ray Powder Data And Unit Cell Parameters Of Mgcl2.6h2o, Charles A. Sorrell, Roy R. Ramey

Materials Science and Engineering Faculty Research & Creative Works

Detailed X-ray powder data for MgCl2·6H2O 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 = 9.858 ± 0.001 Å; b = 7.107 ± 0.001 Å; c = 6.069 ± 0.001 Å; ß = 93° 47′ ± 10′. Calculated density was 1.591 g/cm3, compared with a measured density of 1.593 ± 0.003 g/cm3. © 1974, American Chemical Society. All rights reserved.

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.

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 …

Explosive Metal Forming, Braulio Antonio Tovar

Graduate Research Papers

This study will be concerned with investigating the development of equipment and instructional materials to teach a unit of explosive metal forming in a high school Industrial Arts class. The study will be specifically concerned with: (1) dies and dies blanks for explosive forming, (2) physical phenomena such as velocity, pressure forces, etc., generated in the explosion, (3) technical and laboratory activity content regarding explosion forming, and (4) to prepare a final written report.

Recent Developments In The Use Of Precast Concrete Units For Buildings In The United States And Iran, Khosrow Ebadi Farshchi

Dissertations and Theses

The object of this study was to investigate the recent developments in the use of precast prestressed concrete members for buildings in the United States and Iran. In the United States, the study was concerned with developments in the usage of members such as slabs, wall panels, beams and columns. The latest technical and engineering reports, along with personal interviews, were used, and a number of case studies were conducted on recently built structures. The author also studied the newest developments in the precast concrete industry in Iran. A questionnaire was formulated in both Persian (native language of Iran) and …

15th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 15th 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 20-21, 1973.

Interfacial Energy And Wettability Of Some Glass-Metal Systems, Mahmoud Yehia Demeri

Archived Theses and Dissertations

No abstract provided.

Formation And Densification Of Cadmium Manganese Ferrite, B. W. Jong, P. D. Ownby

Materials Science and Engineering Faculty Research & Creative Works

Formation of Ni-ferrite, Mn-ferrite, NiZn-ferrite, Zn-ferrite and Mg-ferrite have been investigated using X-ray diffraction analysis. Jander's diffusion equation described the data from these investigations over a portion of the temperature ranges studied. However, the reaction mechanisms and sequences involved in the formation of mixed ferrites have not been well defined in the literature. The purposes of this investigation were: ( 1) To further the understanding of the formation of CdMnferrite by studying first the kinetics of the formation of Cd-ferrite and Cd-manganite, which provides a basis for understanding the details of the mixed CdMn-ferrite reaction and to obtain the optimum …

A New And Direct Process For The Reduction Of Lead Sulfide, Rolando Oscar Fernandez

Masters Theses

"The direct reduction of lead sulfide concentrates by iron was investigated. An oxygen-bearing flux was shown to be a necessary ingredient for complete reduction of the concentrate. The effects of time and temperature on lead recovery were studied. Only a trace amount of sulfur dioxide is evolved during reduction, which is in agreement with thermochemical calculations"--Abstract, page ii.

Characterization Of A Mexican Halloysitic Clay And Behavior In Dry Pressing, Jesus L. Derat

Masters Theses

"A Mexican clay, intended to be used as refractory raw material, was identified. Problems encountered in the characterization of halloysitic clays are discussed and emphasis is made on the use of the electron microscope (scanning or transmission type) as a definite evidence of the existence of halloysite due to its unique morphology within the kaolinite group of clay minerals.

Beneficiation of this particular clay was carried out on a small scale hydrocyclone equipment and the results are discussed.

In an attempt to increase the green density in dry pressing of this halloysitic clay, mixtures with grog were prepared using different …

The Effect Of Gating On Soundness Of Al-Alloy Permanent Mold Castings, Dinesh Shantilal Patel

Masters Theses

"This thesis describes the step by step approach to the design of a gating system for the production of sound plate castings in permanent molds. Castings of different thicknesses were produced, utilizing various gating systems, and examined radiographically to evaluate the effectiveness of these gating systems in the production of sound castings. A gating system which allows metal to enter the mold cavity with no turbulence and which establishes proper temperature gradients in the casting will produce sound permanent mold castings"--Abstract, page ii.

Sintering And Microstructure Control Of A Ferrimagnetic Mn-Zn Ferrite Spinel, Joel Keith Michel

Masters Theses

"The effect of minor additions of CaO dopant to a manganese zinc ferrite – Zn_.25Mn_.75 Fe_2.17 O_4.0 - on its grain growth and densification kinetics in air at 1250°C., 1300°C., and 1350°C. was studied. Grain growth was controlled over a range of dopant levels. At a sintering temperature of 1350°C. and time of six hours a ferrite with the smallest dopant addition was sintered to the highest density - 98% of theoretical. Under the same sintering conditions ferrites with higher dopant levels also sintered with normal growth but sintered to lower densities.

Due to discontinuous …

Precipitation Of Carbon From Martensite In Ductile Iron, Devendra Ratilal Majmundar

Masters Theses

"Since metallographic studies of quenched and tempered cast iron have indicated that the carbon might precipitate directly as graphite rather than as carbides which are found in steels, this investigation used the Debye-Scherrer x-ray diffraction technique to examine electrolytically extracted residues from quenched and tempered ductile cast iron samples to determine if cementite was present. The precipitation of carbon in quenched samples of this ductile cast iron was found to be similar to the precipitation process in steels. Cementite was identified during the early stages of the tempering process when the tempering temperature was 800 degrees F, 900 degrees F, …

The Effect Of Porosity On Strength Degradation In Thermally Shocked Alumina, Russell David Smith

Masters Theses

"Strength degradation and crack propagation in Al₂O₃ are shown to depend on the initial strength and porosity of the material. Specimens were fabricated containing between 0 and 5% induced cylindrical, two dimensional, and spherical porosity. The strengths of the various porosity samples decreased discontinuously at a critical quenching temperature. No difference was observed in the critical temperature for the various aluminas; initial strength decrease occurred between 165°C and 175°C temperature differential. The strength retained after thermal shock decreased with increasing initial strength. The degree of damage sustained upon shocking was also characterized by crack density and crack …

Electrical Switching In Iron Calcium Phosphate Glasses, Mohsen Naguib Morcos

Archived Theses and Dissertations

No abstract provided.