Materials Science and Engineering Commons^™

Effects Of 0.5 Weight Percent Boron On Cobalt Aluminide, Kevin Thomas Slattery

Masters Theses

"A study was made on the effects of adding 0.5 weight percent boron to the ordered intermetallic Cobalt Aluninide. Thirty gram (30g) specimens were induction melted in an pure argon atmosphere and cast into a copper alloy bar mold. The addition of boron raised the modulus of rupture from 30.1 to 44.3 ksi; increased the Knoop microhardness from 543 to 693; reduced the average grain size from 190 to 70 microns; and gave a more equiaxed grain structure. X-ray diffraction detected the presence of a second phase, AlB , 12 in the material containing boron. Scanning electron micro-scopy revealed that …

Influence Of Prior Deformation On Structure And Properties Of Heat Treated Aluminum Casting Alloy, Chungwei Hsia

Masters Theses

"A1 356 alloy is extensively used for a wide variety of casting applications. The structure is composed of primary dendrites and eutectic silicon formed during the eutectic reaction. It has long been recognized that the shape of the eutectic silicon significantly affects the ductility of the alloy. Traditionally, the morphology of the silicon is changed by certain chemical and/or thermal processes to improve the ductility. Mechanically deforming the castings to "modify" the shape of silicon has been shown by this research to be an effective alternative method to improve the spheroidization rate of eutectic silicon during heat treatment. The best …

Glass Formation And Properties In The Sm₂O₃·Al₂O₃·Sio₂ System, Erik M. Erbe

Masters Theses

"The purpose of this investigation was to develop a samarium containing aluminosilicate glass with properties suitable for use in the treatment of rheumatoid arthritis. Microspheres made from these compositions would be neutron activated to produce radioactive Sm-153 which has beta-particle energies suitable for treating rheumatoid arthritis as well as appropriate gamma-ray emission for nuclear imaging. The properties of Sm₂O₃ · AI₂O₃ · SiO₂ glasses containing 10 to 25 mole% Sm₂O₃ were evaluated as a function of composition. The density, refractive index, thermal expansion coefficient, and microhardness increased with increasing Sm …

The Effect Of Phosphate Additives On Alumina, Alumina-Calcia, Alumina-Silica Refractory Castable Systems, Sukendro Widjaja

Masters Theses

The effects of the addition of phosphate chemicals to Al₂O₃, Al₂O₃-CaO, and Al₂O₃-SiO₂ systems have been studied concentrating on selected dry and fired properties. The various refractories evaluated were formulated from all alumina aggregate systems based on 1) a mix of tabular and calcined fine aluminas, 2) a combination of calcium aluminate cement bonded-tabular and calcined fine aluminas, and 3) an alumina aggregate-silica fume mixture. Specimens were vibration-cast, dried at 110°C and fired at 1450°C. It was found that each system has different property responses to different …

Sessile Drop Studies Of Aluminum On Sapphire, Ke Wen K. Li

Masters Theses

A sessile drop technique employing a drop placement method has been used to investigate the wetting behavior and interfacial phenomena between aluminum and single crystal α-alumina. Measurements were made under a flowing mixture of H₂ and He atomsphere from 1200°C to 1600°C. Acute contact angles decreased continuously in all cases during the 8-hour experimental time. Neither the oxygen partial pressure of the flowing gas nor the orientation of the single crystal alumina substrate affected the contact angles, but the shapes of crystals grown at the substrate-metal interfaces were dependent on the orientation of the substrate surface to some extent. …

Processing And Characterization Of Ceramic Fiber Reinforced Porous Matrix Composites, Wen-Chiang Tu

Masters Theses

"The development of ceramic fiber reinforced ceramic matrix composites has been shown to be a promising approach for high toughness ceramic materials. The purpose of this work was to develop a new ceramic matrix composite(CMC) system based on a porous mullitic matrix reinforced with ceramic fibers. Unidirectional alligned fiber reinforced mullitic matrix composites were fabricated by a filament winding process. Prepregs were laminated and thermal processed in air. SEM fractographs of the composites were characterized and related to the observed load-deflection behaviors under 3-point flexure. The fracture surface expositions changed from extensive fiber tear-out to limited fiber pull-out as the …

Fabrication And Mechanical Property Analysis Of A Transparent, Glass Fiber Reinforced Polymer Matrix Composite, James R. Olson

Masters Theses

"A "transparent” composite was produced by reinforcing poly(methyl methacrylate) (PMMA) with unidirectional borosilicate glass fibers. Composites with 40 volume percent fiber had a modulus of rupture of 600 MPa which is six times greater than that of pure PMMA. Young's modulus for the same composite was 18 MPA which is nine times greater than the 2 MPa measured for pure PMMA. Work of fracture was 110 kJ/m² or more than double the 45 kJ/m² required to fracture pure PMMA. The optical transmission of the composite with 30 volume percent fiber was approximately 40 percent through a 10 mm …

The Effect Of Additives On Properties Of Pfn-Pfw Dielectric Materials, Weih-Min Liao

Masters Theses

"The purpose of this study was to investigate the effect of processing and additives on the properties of the Pb(Fe_1/2Nb_1/2)O₃-PB(Fe_2/3W_1/3)O₃ solid solutions. The basic composition was 70 m% Pb(Fe_1/2Nb_1/2)O₃ and 30 m% Pb(Fe_2/3W_1/3)O₃. The additives used were MnO, PbO and ZnNbO₆. Pressed compacts were sintered over the temperature range 900'C to 1050°C for 1 to 5 hours.

The influence of processing and composition on the properties was determined by measurement of density, shrinkage, dielectric constant, dissipation factor and …

Reductive Stripping Of Iron(Iii) From Di(2-Ethylhexyl) Phosphoric Acid, Byron G. Belew

Masters Theses

"Unwanted impurities, present in raw materials, are often coextracted along with desired constituents during leaching. If left unchecked, impurity levels may increase in hydrometallurgical process streams until their presence has deleterious effects upon subsequent unit processes. Due to its abundance and ease of extraction, the presence of ferric iron in solvent extraction circuits has always been a problem. The technique proposed herein constitutes a novel approach to remove iron from zinc hydrometallurgical circuits; but the principles employed may find a variety of applications.

This research investigated the reduction and stripping of ferric iron from di(2-ethylhexyl) phosphoric acid into a …

The Effect Of Excess Lead Oxide On The Sintering Characteristics And Dielectric Properties Of Lead Magnesium Niobate Ceramics, Dyllan Jye-Lun Hong

Masters Theses

"The effect of lead oxide additions on sintering characteristics and dielectric properties of ferroelectric Pb₃MgNb₂O₉ based capacitors was studied. The basic dielectric compositions were formed by solid state reaction. Densification was studied as a function of PbO content over the temperature range 900 °C to 1000 °C for sintering times one to six hours depending on the amount of additive, and the sintering temperature.

Weight loss, density and shrinkage measurements of each composition were made in order to relate the effects of the excess PbO additions on the densification. The dielectric and electrical properties were …

An Apparatus For The Measurement Of Dc Electrical Conductivity And Seebeck Coefficient Of Semiconductors As A Function Of High Temperature And Oxygen Partial Pressure, George Francis Carini Ii

Masters Theses

"A computer controlled apparatus for the measurement of dc electrical conductivity and Seebeck coefficient as a function of temperature and oxygen partial pressure has been developed. Thermocouples are in electrical and thermal contact with the ends of the specimen bar. This allows both Seebeck and four-wire electrical conductivity measurements to be made in situ. Environmental enclosure of the specimen allows measurements over a range of oxygen activities from 1 to 10^-18 atm. A discussion of the measuring technique with schematics of the apparatus and data retrieval system is made. Results for measurements in selected oxide ceramics are compared to …

The Development Of Glass-Ceramic Matrix Composites And The Crystallization Of Two Glass-Ceramic Matrices, William M. Carty

Masters Theses

"In order to develop ceramic matrix composites for high temperature applications, two glass-ceramic matrices, one an yttrium aluminosilicate (YAS), the other a magnesium aluminosilicate (cordierite), were chosen as possible matrix compositions. Two separate sets of experiments were performed. Specimens were hot pressed and heat treated then analyzed for the crystallization products and C.T.E. Specimens were also prepared containing commercially available ceramic fibers and coated ceramic fibers to investigate fiber/matrix interactions and the effect of fiber additions on the crystallization of the glass matrices. DTA was employed to approximate the crystallization temperature of the glasses and to determine the effect of …

Glass Fiber Reinforced Polycarbonate Composites, Wen Ching Hu

Masters Theses

"The purpose of this work was to develop a transparent glass fiber reinforced polymer composite material which is superior to the transparent unreinforced thermoplastic in mechanical properties but similar in optical clarity. Polycarbonate matrix composite specimens containing 0 to 40 wt% SK-12 glass fiber were studied, with mechanical and optical properties determined as a function of glass fiber content. The mechanical properties -- flexural strength and elastic modulus increased with increasing glass fiber content. The optical properties -- transmission and transparency decreased with increasing glass fiber content. The factors which influence the mechanical and optical properties were investigated"--Abstract, page ii.

Characterization Of The Fluid-Dynamic Mixing Of A Bottom Gas-Injected Channel Reactor Using Low-Temperature Modelling, Jay Bernett Gassel

Masters Theses

"Variables influencing the mixing in a single-phase (30.5 x 60 x 606 cm) and a two-phase (20 x 40 x 200 cm) channel reactor model were studied. Tracer and/or neutral density particle techniques were used to determine an eddy diffusivity, De, for the system(s). Three bubbler arrangements were investigated in the one-phase work. A separate apparatus was developed to withstand the corrosiveness of the tetrachloroethylene used in the two-phase work.

Both the electrical conductivity tracer technique and the neutral density particle technique were shown to be feasible experimental techniques for determining an eddy diffusivity in the systems studied. Decreasing liquid …

Causal Factors In The Hydration Susceptibility Of Periclase Aggregates, Chao-Min Cheng

Masters Theses

"The findings presented in this thesis are the result of a study of the hydration mechanism of pre-calcined periclase aggregates. It is hoped that these findings will provide the means to develop an economical, stable and hydration resistant layer on the surface of periclase aggregates by coating with appropriate chemical systems.

In the conduct of this study two sources of commercially obtained materials, Steetley 323, and China metal 90-10, supplied by the Quigley company, were characterized and treated with different concentrations of boron-containing water suspensions in order to impose an altered layer which would resist hydration.

Variables affecting hydration investigated …

Formability Of 356 Aluminum, Karol Krumrey Schrems

Masters Theses

"Although aluminum casting alloys are not often thought of as being formable, this thesis examines this possibility. Aluminum alloy 356 was cast in permanent molds and subsequently deformed by rolling (providing compressive loading) and bending (providing tensile loading). Cold forming was found to be very limited, while forming at elevated temperatures was comparatively easy and permitted reductions of up to 90%. Tensile properties and microstructures were examined in detail. Forming breaks up the eutectic silicon and intermetallic compounds. The yield strength and tensile strength increased almost linearly with increasing total percent reduction. The elongation at first increases with total percent …

Property Survey Of Y₂O₃-Al₂O₃-Sio₂-MₓoY Glasses, Amy Lee Applewhite

Masters Theses

"The purpose of this work was to investigate the properties of Y₂O₃-Al₂O₃-SiO₂-M_xO_y glasses. Many M_xO_y components were tested, but TiO₂ and B₂O₃ proved the most interesting. Glasses containing 5 to 25 wt % TiO₂ were melted and found to have improved chemical durability and a higher refractive index and density than the eutectic Y₂O₃-Al₂O₃-SiO₂ starting glass. These glasses could be crystallized to form an opaque glass ceramic. Glasses containing B₂O₃ were formed by exchanging SiO₂ with B₂O₃ while holding the Y₂O₃ and Al₂O₃ content constant. The density, hardness, refractive index, transformation temperature, softening temperature …

The Use Of Computerized Data Acquisition Techniques To Measure The Kinetics Of A Batch Flotation Process, Jose Antonio Barrera-Godinez

Masters Theses

"The flotation response of a lead ore was measured by utilization of a computer driven data acquisition system. A symmetric, fast and automatic froth removal and weighing system was attached to a conventional laboratory flotation cell. The rate controlling mechanisms were identified by manipulation of the froth removal rate, (FRR), froth layer thickness, (FT), and air flow rate, (AFR). The production of froth, water, solids and value in addition to value recovery and concentrate grade were determined as a function of time of flotation.

The flotation response was controlled by events dependent of AFR when using shallow froths of less …

The Interfacial Phenomena Of Liquid Copper Of Sapphire Substrates, Jenq Liu

Masters Theses

"The wetting behavior of liquid copper on the sapphire is effected by the crystallographic orientation of the solid surface, the oxygen partial pressure, and the temperature. Each of these influences has been studied by the sessile drop technique, over the oxygen partial pressure range from 10^-2 to 10^-20 atm at temperatures of 1373°K, and 1523°K. The effect of oxygen partial pressure on the liquid copper surface energy follows the Gibbs Langmuir Law.

The crystallographic orientation of the sapphire surface causes variations in the contact angle. This is more significant for higher oxygen partial pressure, but is eliminated at …

A Dynamic Study Of The Effect Of Cationic Starch Molecular Weight And Charge On Filler And Fines Flocculation, Deflocculation, And Reflocculation, Bob Shian-Hou Ching

Masters Theses

A modified laboratory instrument was used to dynamically monitor the flocculation of fines and filler under various shear conditions on the "seconds" basis. A three-way factorial design and ANOVA were used to evaluate the significance of cationio starch molecular weight and charge in affecting fines and filler flocculation, deflocculation, and reflocculation. The reduction of molecular weight under high shear was suggested by the results. Both main effects and interaction effects of charge and molecular weight were important in determining flocculation. Charge was the only significant factor for the reflocculation process. Molecular weight was more important than charge in imparting shear …

Isolation And Characterization Of The Dimers Formed In The Free-Radical And Anionic Initiated Polymerization Of Alpha-Methylstryene, Kevin S. Bosman

Masters Theses

No abstract provided.

A Study Of Problem Lead-Zinc Ores Of Southeast Missouri In Terms Of Mineralogy And Galena Oxidation, Michael G. Schroer

Masters Theses

"Recovery problems encountered at some of the St. Joe Lead Company's milling facilities prompted the study of 6 different ores. High and low grade ores had characteristics that varied from poor lead - zinc selectivity to excessive lead losses to the flotation tailings. Three ores from both the Fletcher and Viburnum mills were studied through flotation tests, mill water analysis, and ore analysis using an ore microscope.

The major cause for poor recovery was found to be due to ore oxidation. Not only was lead, in the form of oxides, reporting to the tails, but high levels of copper ions …

Characteristics Of A Stirred Bed Reactor Used For Gas-Solid Reactions, Christine Joy Beyke

Masters Theses

“A fluidized bed gas-solid reactor was designed and tested in which most of the fluidization energy is provided by a helical stirrer, with gas being used primarily as a reactant. The bulk gas in which the particles are suspended is practically constant in composition except for the area immediately adjacent to the gas inlet. The reactor is capable of withstanding temperatures up to at least 800°C and can be used with a wide range of flow rates. It is intended primarily as a laboratory tool, with the potential to be scaled up to multikilogram size.

The reactoor is a useful …

Influence Of Oxygen Activity On The Lattice Parameters And Thermal Expansion Of Mg And Sr-Doped Lacro₃, Sutham Srilomsak

Masters Theses

"Lanthanum Chromite, when used as the fuel cell interconnector material is exposed to extremely different oxygen activities on its two surfaces. In addition, it must also form coherent boundaries with the fuel electrode (anode) and air electrode (cathode) layers. In order to accomplish these functions the acceptor doped LaCrO₃ must not only be chemically stable over large oxygen activity ranges, but also have good thermal expansion coefficient of match with both the anode and cathode. Therefore, the objective of this study is to investigate these requirements for Mg and Sr doped LaCrO₃. The study was divided into …

The Effect Of Oxygen Partial Pressure On Oxygen And Carbon Incorporation In Czochralski Grown Single Crystal Silicon, Paul Shane Carter

Masters Theses

"The study herein detailed was made to determine the effect of varying the oxygen partial pressure of a Czochralski type crystal pulling furnace using conventional hardware and remelt silicon on the level of incorporated oxygen and carbon in the single crystal. The oxygen partial pressure was measured by a zirconia type oxygen sensor and controlled by additions of hydrogen or carbon dioxide to the argon purge gas. The oxygen and carbon incorporation measurements were made by the Fourier Transform Infrared (FTIR) method, using the American Standard for Testing Materials (ASTM) standard calibration.

During the study boules which were zero dislocation …

An Investigation Of The Low Voltage Failure Mechanism In Multilayer Ceramic Capacitors, Christopher John Brannon

Masters Theses

"Enhanced leakage current was induced into multilayer ceramic capacitors by the introduction of micro-cracks. These cracks extended from the surface through the electrode layers and were formed by means of thermal shock. The capacitors were then exposed to a low voltage bias and a humid atmosphere. Results indicated that a simple electrolytic solution mechanism may be responsible for the increased conduction, and that the proposed dendritic growth mechanisms may be more complex than necessary"--Abstract, p. ii

Microencapsulation As An Alternative To Emulsification For Preparing As A For Use In Papermaking, William J. Corriveau

Masters Theses

The sizing chemical ASA is emulsified to make i t compatible with the papermaking process. Unfortunately, emulsified ASA is chemically reactive with water at the elevated temperatures found in papermaking systems. As an alternative, encapsulated ASA was made and investigated for its stability towards water at elevated temperatures.

A handsheet procedure was developed to analyze emulsified and encapsulated ASA. It was concluded that the procedure gave statistically reproducible results. Investigations with the procedure revealed important variables concerning the laboratory and m ill application of ASA. Evidence indicated that retention of ASA was critical to sizing development.

Encapsulated ASA made for …

The Effect Of Electrodes On The Thermally Stimulated Currents In Sodium Silicate Glass, Ruth Mogrovejo Cuzmar

Masters Theses

“Electrodes play an important role in the study of alkali ion motion in glasses when TSPC/TSDC techniques are used. Silver, gold and combinations of them were used in the study of Na⁺ motion in Na₂O·3SIO₂ glass. The lower temperature peak is not affected by any of these electrodes, so it is attributed to the bulk glass. A second and third peak are strongly dependent on the kind of electrode used. A gold anode is a blocking electrode, and a gold cathode, is partially blocking. There is a tendency for a space charge polarization to form when …

Sintering Of Catio₃ With The Addition Of Caco₃ And Lif, Surapol Pleekram

Masters Theses

"The densification of CaTiO₃ with the addition of 4.74, 5.90, 6.88 mol% CaCO₃ and 22 mol% LiF was investigated over the temperature range 800° to 1050°C, for sintering times ranging from 1 to 216 hours. It was found that CaCO₃ reacts with LiF and to form a liquid at a temperature of about 450°C. This liquid enhances the densification of CaTiO₃ . The densification process was followed by making weight loss, shrinkage and porosity measurements. The microstructural development was determined by scanning electron microscope examination of both fractured and polished surfaces. X-ray diffraction and DTA/TGA were …

A Study Of The Effect Of Solids, Viscosity, And Basestock On The Development Of Blade Coated Paper Properties, Steven D. Bennett

Masters Theses

A review of literature relating coating solids to coated paper properties revealed many contradictions. Little was found relating coating viscosity to coated paper property development. A statistically designed study was conducted to evaluate the importance of solids, viscosity, and basestock on the development of blade coated paper properties. Temperature was used to control coating viscosity independently of solids. Clay-latex and calcium carbonate-latex coatings were applied to groundwood containing basestocks using a Flooded Nip blade coater. Multiple linear regression models were generated for each of the coated paper properties. Solids and basestock were most important in the models for gloss, smoothness, …