Ceramic Materials Commons^™

A Study Of The System Lithia - Silica, Roy Richard Ramey

Masters Theses

"X-ray intensity and d-spacing measurements were performed upon samples in the system Li₂O-SiO₂. Samples ranged from 0.0 to 28.0 mole percent lithia and were fired for 72 hours at temperatures from 920ºC to 1400ºC. Atomic absorption analyses were made upon the fired samples. Non-equilibrium conditions were prevalent and results are inclusive. Quartz is the stable phase in the high silica field at temperatures below 1050ºC with cristobalite stable above that. The quartz - cristobalite transformation occurs at 950ºC with the cristobalite transforming into tridymite at 1010ºC. There was wide scattering of data at 1000ºC and below. There was no correlation …

A Tensi-Volumetric Apparatus: Theory, Calibration, And Use In An Investigation Of The Oxygen Non-Stoichiometry Of Pure Batio₃, Glenn Jon Conger

Masters Theses

"The development of the tensi-volumetric apparatus has been traced to its current position of significance in studies relating to oxide non-stoichiometry. Components of the tensi-volumetric apparatus, especially the capacitance membrane manometer, were examined in detail as were the parameters affecting the performance of such an apparatus. Based on a careful consideration of components and performance, a tensi-volumetric apparatus has been designed, built, and its operation theoretically justified for its particular physical configuration. Results of existing studies of the oxygen non-stoichiometry of barium titanate have been used to predict its behavior during a tensi-volumetric study. Specific analytical procedures developed for use …

Concentration By Sorting : Feasibility Determination By Radial Distribution Analysis, Robert M. Doerr

Masters Theses

"A method was developed for determining certain factors for assessing the feasibility of sorting fragments of an inhomogeneous solid to concentrate a species. These factors are the typical size of zones in which the grade exceeds a selected value, and the recovery potentially achievable by sorting fragments of such size"--Abstract, page iii.

Polynary Silicon Tellurium Glasses, Henry Edward Anthonis

Masters Theses

"The introduction of Ag into Si-As-Te glasses permits the incorporation of Se, otherwise volatile and/or degradable as a constituent in Si-containing chalcogenide glasses. Si-As-Ag-Te-Se glasses exhibit much higher softening ranges and glass transition temperatures than encountered in known chalcogenide systems. A glass Si₃₅As₁₅Ag₁₀Te₂₀Se₂₀ had the viscosity log η =13 at about 500°C, as compared to 370°C for the base glass Si₃₅As₂₅Te₄₀, the viscosity of log η = 9.8 at about 560°C, as compared to 442°C for the base glass Si₃₅As₂₅Te_{40 …}

The Pm3m-Fm3m Transformation And Phase Equilibrium In Solid Solutions Of Csc1 With Kc1, Rbc1, And Csbr, John David Weyand

Masters Theses

"Thermal expansion and the Pm3m t Fm3m transition of cesium chloride have been studied with high temperature diffractometry, differential thermal analysis, and heating and quenching techniques. The onset temperature of the transition in pure CsCl, on heating, is 471ºC. There are no observable premonitory effects below the transition temperature and no apparent structural relationships between the polymorphs is apparent. Both phases coexist over a 20º to 50ºC temperature range and equilibrium thermal hysteresis occurs on heating and cooling. Hysteresis behavior is explained by addition of strain energy parameters to the free energy function. Initiation of the Pm3m t Fm3m transformation …

Evaluation Of A Cation Isotopic Substitution Technique In Conjunction With A High Temperature Gas Pycnometer For Determining The Stoichiometry Of Materials, Michael Clair Graves

Masters Theses

"This study was concerned with the evaluation of a high temperature gas pycnometer, used in conjunction with a cation isotopic substitution technique, for determining the stoichiometry of materials. Three methods were investigated for determining the correction factors for the thermal gradient effects in the gas pycnometer. The correction factors were shown to be dependent on the temperature, the sample volume, and the height of the sample in the sample chamber. Under the conditions of these experiments, the correction factors were shown to be essentially independent of sample grain size and pycnometer atmosphere. The determination of the stoichiometry of cadmium oxide …

Final Sintering Of Cr₂O₃ With Minor Additions Of Mgo And Sintering Of Mgo With Minor Additions Of Cr₂O₃, Gordon E. Jungquist

Masters Theses

"The effect of oxygen activity on the sintering of Cr₂O₃ with minor additions of MgO, and of MgO with minor additions of Cr₂O₃ at 1600ºC was investigated. A peak density (99.4% of theoretical) was obtained for high purity Cr₂O₃ by maintaining the equilibrium oxygen partial pressure needed to maintain the Cr₂O₃ phase. The addition of 0.1 wt. % MgO increased the sintered density at the same oxygen pressure to 99.8%. Further MgO additions decreased the density. The density of pure MgO was independent of the P_O₂ over the range investigated. Addition of Cr₂O₃ to MgO decreased the density at …

Alkali Mobility And Mechanical Relaxation In Mixed-Alkali Silicate Glasses, James W. Fleming Jr.

Masters Theses

"Internal friction and sodium and potassium self-diffusion coefficients for (1-X)Na₂O · XK₂O· 3SiO₂ glasses were measured. Alkali diffusion was measured between 300 and 500ºC using radioactive isotopes and a thin-sectioning technique. Internal friction was measured from room temperature to 500ºC, 0.1 to 2000 Hz. Comparison between alkali diffusion and internal friction data for Na-K glasses with those for other mixed-alkali glasses shows that the mixed-alkali peak is related to alkali mobility. It is concluded that the mechanism for mixed-alkali internal friction is a cooperative rearrangement of dissimilar alkali ions, with the slower moving ion controlling the rate of reorientation"--Abstract, page …

High Temperature Compressive Creep In Mullite, Peter C. Smith

Masters Theses

"Compressive creep measurements were made on two groups of mullites at temperatures between 1455ºC and 1520ºC. The first group consisted of commercially manufactured mullites. The second group was made up of 7 different mullite compositions spanning the alumina-silica solid solution range from 3Al₂O₃ • 2SiO₂ to 2Al₂O₃ • SiO₂ . Thermal activation energies and stress exponents were calculated for the mullites in the second group. Steady state strain rates taken at 1460ºC under loads of 100 and 110 psi varied between 1.3x10⁻⁴ in/in/hr and 15.4x10⁻⁴ in/in/hr. Activation energies were between 109 Kcal/mole and 204 Kcal/mole. Stress exponents calculated from data …

Investigation Of The System Al₂O₃-Teo₂-O₂, Vera Zelenkova Sestak

Masters Theses

"The system Al₂O₃-TeO₂-O₂ has been investigated by X-ray diffraction and differential thermal analysis in air and in sealed silica ampoules. The tellurate, Al₂TeO₆, with tellurium in the +6 valence state, forms in air but not in vacuum at 1 mm pressure. A second phase, a tellurite, possibly Al₂Te₂O₇, forms in air or vacuum by devitrification. The glass-forming region is wider than previously stated and is more extensive in vacuum--from 50% to 98% TeO₂. Tentative phase boundaries have been placed for the system in air and vacuum"--Abstract, page ii.

Fracture Surface Energy Determinations Of High Density Polycrystalline Ceramics, Gene Arthur Pahlmann

Masters Theses

"Values of fracture surface energy were measured for steatite, zircon, mullite and four densities of alumina. Rods of these high density materials were cut into thin rectangular specimens which were notched and broken in three-point loading. The resulting load necessary for fracture of the specimens was used to calculate the fracture surface energy of the materials. The value for the steatite was around 20,000 ergs/cm². The values for the zircon and mullite were on the order of 13,000 ergs/cm², and the values for the aluminas ranged from 17,000 to 24,000 ergs/cm²"--Abstract, page ii.

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.

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 …

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 …

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 …

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 …

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 …

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.

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 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 …

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 …

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

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

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 …

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 …

A Preliminary Study Of The Dielectric Properties Of Bismuth Ferrate Ceramics., John Joseph Schwaller

Masters Theses

"In this investigation some of the results of Fedulov¹⁸ for a composition of 30 percent lead titanate - 70 percent bismuth ferrate were verified. The system of lead zirconatebismuth ferrate was studied with sintering data determined for the series. By X-ray and microscopic analysis the system was determined to be not a solid solution. The dielectric measurements show a linear relation between the dielectric constant and the percent lead zirconate from 100 percent BiFeo₃ to 10 percent BiFeo₃ - 90 percent PbZro₃"--Abstract, p. ii

Influence Of Porosity On The Fracture Stresses Of Electrical Porcelain., Edward Anton Snajdr

Masters Theses

"Spherical pores were induced in a typical quartz electrical porcelain body. Three levels of pore size and four levels of concentration were studied. Large strength sample sizes were employed using a three-point loading and diametral loading method. Data for induced quartz particles is also included"--Abstract, p.ii

Preliminary Investigation Of Acid Treatment For The Stabilization Of Doloma, Deward Pan

Masters Theses

"The work presented in this thesis is the result of an investigation to develop an economical and successful means for producing a stable, hydration resistant compound on the surface of doloma particles by an acid treatment, which does not significantly alter the refractoriness of the material. Granite, a commercial doloma, from Valley Dolomite Corporation, was treated with different concentrations of inorganic acid-water solutions and organic acid-alcohol solutions for varying time at atmospheric pressure and temperature. The treated doloma was examined by (l) X-ray diffraction and (2) the hydration test.

It was found that the organic acid acted as a coating …