Title page for ETD etd-11242008-105521


Type of Document Dissertation
Author Payyapilly, Jairaj Joseph
Author's Email Address jairajp@vt.edu
URN etd-11242008-105521
Title Formation And Growth Mechanisms of a High Temperature Interfacial Layer Between Al and TiO2
Degree PhD
Department Materials Science and Engineering
Advisory Committee
Advisor Name Title
Logan, Kathryn V. Committee Chair
Clark, David E. Committee Member
Kelley, Michael J. Committee Member
Reynolds, William T. Jr. Committee Member
Keywords
  • oxidation-reduction
  • titanium aluminide
  • titanium dioxide
  • liquid aluminum
  • Interfacial Reaction
  • growth mechanism
Date of Defense 2008-11-19
Availability unrestricted
Abstract
The product of interaction between Al and TiO2 at elevated temperature has a wide range of applications in refractory, structural and electronics industries (refractory tiles, tank armor, fuel cells, and microelectronic devices). This research attempts to understand the extent of interaction between Al and TiO2 when the reactant surfaces are in contact at elevated temperature and normal atmospheric pressure. The interfacial region between the reactant compounds is examined using analytical techniques; and the formation of TiAl as the interfacial compound is described. The thermodynamics of the Al – Ti – O system is explained as it relates to the particular conditions for the Al – TiO2 reaction research. Thermodynamic principles have been used to demonstrate that the formation of TiAl is favored instead of other TixAly compounds for the set of conditions outlined in this thesis. A study of the mechanism of interactions in the interfacial region can help towards being able to determine the reaction kinetics that lead to the control of microstructure and thus an improvement in the material performance. An appropriate model that describes the formation of TiAl at the interface is described in this study. The formation of TiAl at the interface is a result of the reduction reaction between TiO2 and Al. The O released during the reduction of TiO2 has been investigated and demonstrated to partly remain dissolved in TiAl at the interfacial region. Some O reacts with Al as well to form crystalline Al2O3 in the interfacial layer.
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