Doctor of Philosophy, The Ohio State University, 2008, Materials Science and Engineering

The beneficial influence of boron additions on processing, microstructure, physical and mechanical properties of various titanium alloys has been recognized since 1950's. However, boron additions to titanium alloys to obtain specific microstructures and mechanical properties for several niche applications, including automotive and aerospace, have been actively studied during the past 25 years. The addition of boron concentrations greater than 0.05 wt.% to titanium alloys creates a dispersion of TiB. The presence of TiB enhances the tensile and fatigue strengths as well as the wear resistance as compared to the original titanium alloy. Although these improvements in mechanical properties are attractive, there are still two major obstacles in using these alloys: (1) relationship of microstructure and mechanical properties in Ti-B alloys needs further investigation to optimize the alloys for specific commercial applications; and (2) cost to benefit ratio of producing these alloys is high for a given application(s). The Armstrong process is a novel process that can produce commercially pure (CP) titanium and titanium alloy powder directly from TiCl4 (and other metal halides or as required, to obtain the desired alloy composition). The Armstrong process uses sodium as a reducing agent, with similar reactions as the Hunter process using sodium as a reducing agent and Kroll process using magnesium as a reducing agent. The Armstrong process forms CP-Ti and titanium alloyed powder, which can be directly consolidated or melted into the final product. In comparing the downstream processing steps required by the Kroll and Hunter processes with direct consolidation of Armstrong powder, several processing features or steps are eliminated: (1) restriction of batch processing of material, (2) blending of titanium sponge and master alloy material to create titanium alloys, (3) crushing of the sponge product, (4) melting, and (5) several handling steps. The main objective of this res (open full item for complete abstract)

Committee: James Williams (Advisor) Subjects: Textile Technology

Doctor of Philosophy, The Ohio State University, 2005, Textiles and Clothing

The research reported in this dissertation encompassed the investigation of the sources of variation in visual judgment of color differences in textiles and the consequent disparities in color differences calculated from instrumental color measurement. In a paired comparison method, 46 color pairs, including color inconstant samples, were assessed four times by a panel of 59 observers under two daylight simulators, filtered tungsten and F7. Observer variation was assessed with performance factor analysis for observer accuracy and repeatability and by Kappa statistics for observer reliability. Accuracy and repeatability were low compared to previous studies and assessment of inter- and intra-observer reliability showed poor agreement in visual judgments within and between observers. While observers were found to be the most significant source of variation, observer accuracy and repeatability were significantly higher for samples viewed under the filtered tungsten simulator, as compared to F7, leading to the conclusion that choice of simulator affects visual judgments. Visual results were also used to test the effectiveness of four color difference formulae: CIELAB, CMC, CIE94, and CIEDE2000. Using performance factor analysis with confidence intervals formed with a bootstrap method, instead of the simple ranking that has been used in other research, no statistical difference was found in the performance of any color difference formula for either simulator. However, the combination of CIEDE2000 and filtered tungsten consistently showed less variation. The use of constant and inconstant samples did not affect the results; however, the effect may be due to the large color differences of the inconstant samples. Even though prediction of visual judgments by color difference equations was low, the importance of instrumental color difference evaluation is supported by its stability in contrast to the variability demonstrated by observers.

Committee: Kathryn Jakes (Advisor) Subjects: Textile Technology

Master of Science, The Ohio State University, 1986, Textiles and Clothing

Committee: Nancy Rudd (Advisor) Subjects: Textile Technology