Materials Science and Engineering Commons^™

Some Effects Of Oh Groups On Sodium Silicate Glasses, Mokhtar Sayed Maklad

Doctoral Dissertations

"Glasses of various compositions in the Na₂O-SiO₂ system were prepared with different levels of OH concentration. Phase separation kinetics, thermal expansion, radiation induced optical absorption, and internal friction of these glasses were studied. The increase in OH content in these glasses was found to (a) enhance the rate of phase separation; (b) increase thermal expansion above the glass temperature and change the dilatometric softening temperature in a way that depends on microstructure; (c) increase the radiation induced optical absorption bands associated with positive hole centers and decrease those associated with electron trap centers; and, (d) decrease the low temperature alkali …

A Crystallization Study Of A Tetrasilicic Fluormica Glass, William H. Daniels

Doctoral Dissertations

"The transformation of a synthetic mica composition K₂Mg₅Si₈O₂₀F₄ from amorphous to crystalline structure was studied isothermally at selected temperatures from 560°C to 1150°C. thermal changes associated with the transformation were followed by differential thermal analysis techniques. Structural changes promoted by the isothermal treatments were observed by density measurements, Debye-Scherrer X-ray diffraction techniques, electron replication microscopy, and electron scanning microscopy. Isothermal treatment at 450°C for 9 hours produces structural ordering in quenched K₂Mg₅Si₈O₂₀F₄ glass. Fluorine exerts a significant influence on the transformation temperature; decreasing amounts of fluorine producing increasing transformation temperatures. The crystallizing phase rapidly attains a limiting particle size and …

Internal Friction Of Phase Separated Glasses, Scot Walter Taylor

Masters Theses

"The large internal friction peak observed in a 10Li₂O·10Na₂O·80SiO₂ glass was studied as a function of the degree of phase separation. Transmission electron microscopy was used to evaluate the type and degree of phase separation. No observable changes in the temperature position or height of the internal friction peak were observed at successive stages of phase separation. Phase separation of a mixed alkali borosilicate glass also produced no changes in the internal friction peaks. Phase separation is not considered responsible for the large internal friction peak observed in mixed alkali glasses"--Abstract, page ii.

Kinetics Of The Formation Of Strontium Zirconate, W. H. Parker

Masters Theses

"The decomposition rate of strontium carbonate (SrC0₃) was measured using a TGA apparatus. It was found to deviate slightly from zero order classical reaction. The rate of formation of strontium zirconate (SrZr0₃) from zirconium oxide (ZrO₂) and strontium oxide (SrO) in the form of the decomposition product of SrCO₃ was measured using quantitative x-ray diffraction for mineralogical analysis. It was found to most nearly follow the Zhuravlev-Lesokhin-Tempel' man rate equation. The rate of decomposition of strontium carbonate was found to be more rapid than the rate of formation of strontium zirconate such that for the most part strontium oxide is …

The Damage Assessment Of Thermally Shocked High Density, High Purity Aluminum Oxide, John H. Ainsworth

Doctoral Dissertations

"The traditional approach to thermal shock testing in brittle materials has been to determine the temperature difference required to nucleate cracks in these materials. Recent work has indicated that the degree of damage after crack nucleation should be an additional consideration. The degree of damage resulting from cooling thermal shocks has been the primary consideration of the present work. Test specimens of two geometries: long, solid rods and short, solid cylinders were quenched from selected temperatures into ice water. The degree of damage was determined through strength measurements and sonic damping analysis. Initial damage occurred at a temperature difference above …

Decomposition Of Cr(Oh)₃ To Form Active Cr₂C₃, Timothy A. Clancy

Doctoral Dissertations

"This study was concerned with the sinterability of Cr₂C₃ powders produced by the calcination of a Cr(OH)₃ gel. The decomposition of the gel was investigated by thermogravimetric analysis, X-ray analysis and microscopic examination. Comparison was made between the size of crystallites as determined by X-ray line broadening and the size of aggregated particles as determined by independent means. These lineal measurements were compared to surface area measurements on the calcined powders. The degree of sinterability was judged from the density measurements on Cr₂C₃ pellets fired under air, oxygen and nitrogen atmospheres. Energies of activation of 25 and 20 kilocalories per …

Compressive Creep Of Basic Refractories, Maurice E. Green

Masters Theses

"The microstructure and mineralogical composition of direct bonded, 50 wt.% magnesia - 50 wt.% chrome ore refractory compositions containing controlled additions of silica were correlated with their compressive creep behavior in the temperature range 1450⁰ to 1550⁰C under stresses of 100 to 175 psi. Steady state creep rates were determined from the linear regression of the steady state regions of deformation on time. Apparent activation energies and deformation flow characteristics were determined from the temperature and stress dependence of the steady state creep rates. Silica contents up to 3.5 wt.% increased the amount of direct intergranular bonding which decreased the …

Cutting Nbs Budget, Norbert J. Kreidl

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Optical Reflectance Spectra Of Chromium (Iii) In Mgo-Ss, Thomas Spencer Montgomery

Doctoral Dissertations

"The valence state and coordination site of the transition-metal ion, chromium, was investigated in a MgO host lattice. The chromium ion incorporated into poly-crystalline MgO by quenching from elevated temperatures allowed investigation of a single crystalline phase, MgO-solid solution (ss). The chromium ion was confirmed to occur in the trivalent state and to occupy octahedral cation sites in the MgO lattice by the use of optical reflectance spectroscopy. The effect of the concentration of the chromium ion on the crystal field splitting energy, 10 Dq, permitted analysis over a range of Dq/B values. In conjunction, MgO-ss lattice parameters examined as …

Vapor Pressure And Evaporation Coefficient Of Cadmium Oxide, R. Tom Coyle Jr.

Masters Theses

"Knudsen effusion experiments were carried out on CdO in fused silica crucibles at temperatures of 918°K, 1008°K with orifice areas from 2.742x10^-3 cm² to 30.52x10^-2 cm². The experiments were made in a molybdenum-wire, resistance-heated vacuum furnace. Several orifice areas were used at each temperature and reciprocal pressure versus orifice area plots were made. These plots yielded an upper limit to the evaporation coefficient of. 4.15x10^-2. An equilibrium constant for the vaporization reaction

CdO(s) = Cd(g) + 1/20₂ (g)

of

log Keq = 11.12 - 1.952x10⁴/T.

was obtained. Second and third …

Relationship Of Feldspar Properties To Surface And Volume Defects In Porcelains, Macy Wiiliam Vance

Masters Theses

"Four levels of particle size distribution and four compositions of feldspar ranging from high-potash to high-soda content were evaluated in their effect on body and surface defects and selected engineering properties of an electrical porcelain. It was found that surface blistering defects occurred at a high incidence in porcelain specimens slightly overfired at 1225⁰C in a body composition containing 33% albite (soda), 67% high-potash feldspar blend and a relatively coarse, 140 mesh grind, of the feldspar. The occurrence of surface and volume blisters was correlated with the formation of a microscopic bleb structure in the porcelain matrix. It was also …

Compressive Creep Of High Alumina Refractories, Vernon Lee Burdick

Masters Theses

"The deformation of refractory materials consisting of 90% sintered or fused alumina plus 10% silica was measured at temperatures from 1450 to 1515⁰C and a compressive stress of 100 psi. Creep rates and activation energies were determined from the steady state portion of deformation vs. time data and correlated with the mineralogical composition. Supplemental measurements included x-ray diffraction, electron probe microanalysis, apparent porosity and tensile strength. conditions having an important effect upon the mineralolgical composition were: (1) duration of heat treatment, (2) amount of sodium oxide impurity, and (3) reactivity of the alumina grain. Prolonged heat treatment and sodium oxide …

Tensile Strength Of Prereacted Porcelain Compositions, Chester Lee Hill

Masters Theses

"The tensile strengths of two porcelain compositions containing prereacted silica and feldspar have been determined with the diametral loading technique. A comparison was made between the strength of the prereacted samples and the strength of samples of the same compositions, but prepared in the conventional manner. At the optimum firing temperature, no significant differences in tensile strengths were observed between the prereacted and control samples for the two compositions studied. At temperatures below and above the optimum firing temperature, the prereacted samples had the higher tensile strengths. The tensile strengths are correlated with the average size of the quartz particles …

The Elastic And Anelastic Constants Of A Synthetic Fluor-Mica Formed By Glass-Ceramic Fabrication Techniques, John H. Ainsworth

Masters Theses

"A tetrasilicic fluor mica, K₂Mg₅Si₈O₂₀F₄, was synthesized using glass forming techniques. Density changes, weight losses, and shrinkage, as well as elastic and anelastic properties, were measured on bars heat-treated at selected temperatures between 500°C and 1150°C to determine the characteristics of this material. Phase changes were followed by determining thermal expansion, logarithmic decrement, and modulus of elasticity from room temperature to 800°C.

It was found that the elastic and anelastic constants decreased gradually with heat treatments from 600°C to 1000°C. This indicated progressively increased structural ordering. Heat treatments above 1000°C …

The Dielectric Properties Of A Synthetic Fluor-Mica Formed By Glass-Ceramic Fabrication Techniques, Ray Fred Schumacher

Masters Theses

"A tetrasilicic fluor-mica, K₂Mg₅Si₈O₂₀F₄, was synthesized, utilizing glass forming techniques and subsequent heat treating of the mica glass. Discs, approximately two inches in diameter, were formed and heat-treated at selected temperatures between 700⁰C. and 1150⁰C. for various time periods. Density change, weight loss, shrinkage, and dielectric properties were measured to determine the characteristics of this material"--Abstract, page ii.

Internal Friction Of Mixed-Alkali Silicate Glasses, James E. Shelby

Doctoral Dissertations

"The mixed alkali effect in silicate glasses was examined from internal friction measurements made over the temperature range from -190 to 500⁰C and at a frequency of 0.4 Hz. Supplemental measurements of the activation energy for the different internal friction peaks, dynamic shear modulus, density, and index of refraction were also made. All measurements were confined to silicate glasses containing mixtures of Li-Na, Li-K, Li-Rb, Li-Cs, Na-K, Na-Rb, Na-Cs, and K-Rb. Rötger's interpretation of the internal friction of mixed-alkali silicate glasses is shown to be incorrect. A previously unreported internal friction peak was observed whenever two different alkali oxides were …

Effects Of Oxygen Content Of Admitted Gases In Sulfide Flotation, Brian J. Boyle

Bachelors Theses and Reports, 1928 - 1970

No abstract provided.

Methods Of Studying The Effects Of Frothers, Frank L. Bazzanella

Bachelors Theses and Reports, 1928 - 1970

No abstract provided.

Mechanism Of Siliconizing Of Molybdenum And Tantalum By Vapor Deposition, Gordon Pu Kong Chu

Doctoral Dissertations

"Molybdenum and tantalum were siliconized in an enclosed system by the hydrogen reduction of silicon tetrachloride with induction heating between 900°C and 1450°C.

The siliconizing process was primarily influenced by the gaseous composition, temperature, time, molar flow ratio (SiCl₄/H₂), geometrical shape and ionization charges. The rate of siliconizing, measured as the weight gain by the fused quartz helix balance, generally follows a parabolic law, y = k t^1/2, where y = weight gain, t = time, and k = rate constant. The activation energy is estimated at 21.6 k cal/mole for siliconizing of molybdenum. …

Densification Studies Of Three-Component Refractory Grog Systems., Jerome Dale Patterson

Masters Theses

"The bulk density and crushing strength properties of three-component refractory grog systems that were formed by mechanical impact or by mechanical vibration were determined.

Aqueous alkali silicate solutions of various types, concentrations, and amounts were investigated as room temperature binders for these grog systems. Compositions having maximum bulk densities were determined for each of six different three-component refractory grog systems. The densification rate curves for systems formed by mechanical impact were determined"--Abstract, p. ii

Solid Solubility Of Sodium Oxide In Tricalcium Aluminate, Joel A. Conwicke

Masters Theses

"The tie line connecting the compounds 3CaO·Al₂O₃ and Na₂O·8CaO·3Al₂O₃ in the ternary system CaO-Al₂O₃-Na₂O was studied at 1250° Celsius.

It was determined that Na₂O can exist in crystalline solution with 3CaO·Al₂O₃ in percentages of about 2.3% or less without any apparent change in the structure of 3CaO·Al₂O₃. X-ray diffraction peaks in the back-reflection region shifted to lower d-spacing values on increasing Na₂O contents.

At a Na₂O content of about 2.7%, each major x-ray …

Influence Of Quartz Particle Size And Concentration On The Fracture Stresses Of Triaxial Alumina Porcelain., John David Weyand

Masters Theses

"Quartz particles were introduced into a typical triaxial alumina porcelain. Three levels of particle size and three levels of concentration were studied. The strength sample sizes were large. A diametral- compression loading method was used for strength testing. It was found that the porcelain strength decreased with increasing grain size and concentration of quartz particles. A linear relationship existed between log quartz concentration and mean fracture stress"--Abstract, p. ii

A Study Of Crystallization Of Synthetic Fluor-Glaucophane Compositions, Kartini Tjokroatmodjo

Masters Theses

"The ability to form a stable glass and the crystallization properties of four compositions close to that of glaucophane, Na₂Mg₃Al₂Si₈O₂₂(OH)₂ studied. Three glasses were compared with a fourth glass containing no fluorine. The crystallization products of all four glasses were examined between the temperature range 600 - 1200°C. The crystallization products of the three fluorine containing glasses were similar, consisting of mica below 1000°C and of mica, fluor-glaucophane, enstatite and forsterite above 1000°C. In the fluorine free glass, enstatite was the only crystalline phase present below 1000°C, however, forsterite …

The Effects Of Surface Flaw Density And Configuration On Fracture Stresses Of A Triaxial Porcelain., William H. Daniels

Masters Theses

"The fracture behavior of a model brittle solid containing artificial surface flaws was studied. An industrial ceramic porcelain body was employed as the model brittle material. Sample groups of specimens containing 6, 11, 24, 49,. and 90 sharp surface notches uniformly distributed over a four inch length were broken under pure bending. The fracture data we-re compared to those of an identically treated control group containing no artificial flaws.

The mean strengths of the two groups of lowest flaw density were identical, both being significantly less than that for the control group. Further increases in flaw density resulted in increased …

A Preliminary Study Of The Controlled Crystallization Of A Bottle Glass., Narayan M. Sedalia

Masters Theses

The effect of addition of Ti0₂ as a nucleating agent was studied with a bottle glass composition of 74 weight percent Si0₂, l percent Al₂O₃, 5.4 percent Cao, 3.7 percent MgO, 15. 3 percent Na₂O, and 0.6 percent K₂O as a base or original composition. The addition of titanium dioxide ii varied from 3 to 20 weight percent. The composition of this bottle glass was changed by increasing the following ingredients and keeping the other ingredients in the same ratios:

1. Increased 5 weight percent of Al₂O …

Development Of A Fluor-Mica Dielectric Using Glass-Ceramic Fabrication Methods., James Joseph Tuzzeo

Masters Theses

"A tetrasilicic fluor-mica, K₂Mg₅si₈o₂₀F₄, was synthesized using glass-ceramic fabrication methods. Bubbles, rods, and disks of glass-mica were formed, and heat treated at selected temperatures between 620°c and 1160°c for various time periods. Density changes were correlated to mica content to determine the relative amounts of crystalline mica phase precipitated after heat treatment. Dielectric losses and dielectric constants of the glass-mica disks were measured for correlation to mica content"--Abstract, p/ ii

Studies In Modulation Of Interfacial Reactions For Certain Sulphide Minerals, Robert Owen Beyaert

Bachelors Theses and Reports, 1928 - 1970

No abstract provided.

Habit Modification Of Naclo3 With Nai, William A. Coghlan

Bachelors Theses and Reports, 1928 - 1970

No abstract provided.

Production Of Standard-Grade Ferromanganese In An Electric Arc Furnace, Force F. Baney Jr.

Bachelors Theses and Reports, 1928 - 1970

The investigations conducted in this project were essentially concerned with the effects of various compositions of two different slag systems upon the increased recovery of manganese in a standard-grade ferromanganese.

Investigation Of The Ternary System Silver-Aluminum-Indium (Ag-Al-In), Elvin H. Beardslee

Bachelors Theses and Reports, 1928 - 1970

This thesis paper contains material pertaining to & preliminary investigation of the ternary system Ag-Al-In. Procedures in this preliminary investigation are discussed in detail.