The effect of silica-containing binders on the titanium/face coat reaction
AdvisorPoirier, David R.
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PublisherThe University of Arizona.
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AbstractThe interactions of CP-Ti and Ti-6Al-4V with investment molds with alumina/silica and yttria/silica face coat systems, and yttria crucibles were studied. It was found that the thickness of the reaction layer (alpha case) was the same, whether a yttria/silica or alumina/silica face coat was used, indicating that it is the silica binder truly which reacts with the titanium. Furthermore, it was found that only the yttria crucible was inert to reacting with titanium when it was used as a mold. When titanium was heated in yttria crucibles, however, and held just above the liquidus for 15 s and 30 s, oxygen and yttrium were found in the resulting samples. This indicates that commercial castings requiring longer solidification times might not be free of the alpha case even when produced in a 100% yttria mold system.
Degree ProgramGraduate College
Materials Science and Engineering