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Mechanical Properties Of Alumina For Orthopedic Implant Use, Ho Tong Fang

Masters Theses

"The static fatigue, flexural strength and chemical corrosion of three commercially prepared, polycrystalline aluminas, two of orthopedic implant grade, were measured in demineralized water at 37°C and 70°C. The dissolution of a Ca-rich impurity phase, probably a glass, segregated at the grain boundaries and external surface, appears at least partially responsible for the significant difference in static fatigue of these three aluminas. The present results indicate that the minimum static fatigue in demineralized water, and the highest flexural strength in demineralized water and HF solution are both achieved by the alumina characterized by a low concentration of Ca at the …

The Effect Of Selected Alloying Elements On The Hardness And Microstructure Of Ductile Cast Iron, Chi-Hua Edward Tseng

Masters Theses

The effects of cooling rate and alloying element on the matrix structure, nodule count and hardness have been studied in this investigation.

Recommendations for producing ferritic ductile iron have been made and the relationship between hardness and pearlite percentage has been obtained in this study.

Glass Formation And Properties In The Gallia-Calcia System, Glenn Whichard

Masters Theses

“The critical cooling rate for glass formation for melts containing from 37.5 to 68.0 mol % Ga₂O₃ varied from 310 ± 80°C/s to 855 ± 115°C/s. The crystallization temperature, microhardness, UV and visible transmission were measured. The density increased from 4.075 g/cm³ at 37.5 3 mol % Ga₂O₃ to 4.402 g/cm³ at 56.0 mol % Ga₂O₃. The refractive index, n_D, increased from 1.778 at 37.5 mol % Ga₂O₃ to 1.802 at 62.0 mol % Ga₂O₃. The IR spectra indicate …

Defect Chemistry Of La-Doped Strontium Titanate, Brian Keith Flandermeyer

Masters Theses

"Thermogravimetric measurements as a function of oxygen activity were performed in the temperature range of 1200°C to 1400°C on a series of La-doped SrTiO₃ compounds. A model postulating the crystallographic accommodation of ionic defects induced by the donor under oxidizing conditions is assumed. Thermodynamic calculations were performed to compare this model to the experimental results with reasonable success"--Abstract, page iii.

Sintering Of Lif-Fluxed Srtio₃, Marie-Christine P. Proudian

Masters Theses

"Lithium fluoride (LiF) is used to enhance the sinterability of perovskites, as it results in the formation of a liquid phase. In this study, the mechanism and kinetics of sintering for LiF-fluxed strontium titanate (SrTiO₃) were investigated. The Sr/Ti ratio was varied between 0.98 and 1.03, and the LiF content in the green compact ranged from 0.5 to 2.0 weight percent. Sintering was conducted at temperatures between 695° and 925°C for isothermal dilatometric shrinkage measurements for time intervals of 6000 seconds or less. Weight loss, shrinkage, density and porosity measurements were conducted on samples isothermally sintered between 690° …

Separation Of Mineral Particles In Cyclones Under The Influence Of A Magnetic Field, Kwasi Amoako-Gyampah

Masters Theses

"The separation of mineral particles in a cyclone under the influence of a magnetic field was investigated using an electromagnetic - cyclone arrangement. Feed pulps of dolomite and magnetite were used in the study. Two different cyclone types were investigated: An air-type cyclone arrangement and a conventional cyclone arrangement. Magnetic field strengths of 0 to 3000 gauss (0 - 0.3 Tesla) were used in the study by varying the current through the coils of the electromagnet .

The parameters evaluated in the study were the grades and recoveries of the magnetic concentrates produced, the enrichment ratios, the improvement in recoveries …

Development Of Glass Microspheres For Radiotherapeutic Applications, Thomas A. Wetteroth

Masters Theses

"Oxide glasses make excellent candidates for radiotherapeutic microspheres used in liver cancer treatment because of their generally high chemical durability and safety of manufacture. From the compositions containing ~5 wt% P₂O₅ studied, magnesium alumino silicate glass microspheres and magnesium alkali silicate glass microspheres with 4 wt% ZrO₂ had acceptably low releases of both elemental phosphorus in deionized water at 50°C, and radioactive ³²P in human blood plasma at 37°C. The relative ranking of glass compositions in the elemental phosphorus leach test shows good agreement with the rankings of compositions in the radioactive ³²P leach …