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Electric field effects on densification of TiB2 and BaTiO3
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Ozdemir, Tevfik Ertugrul. Electric field effects on densification of TiB2 and BaTiO3. Retrieved from https://doi.org/doi:10.7282/T31Z46GB

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TitleElectric field effects on densification of TiB2 and BaTiO3
NameOzdemir, Tevfik Ertugrul (author); Tsakalakos, Thomas (chair); Klein, Lisa (internal member); Kear, Bernard (internal member); Zhong, Zhong (outside member); Rutgers University; Graduate School - New Brunswick
Date Created2016
Other Date2016-01 (degree)
SubjectMaterials Science and Engineering, Sintering
Extent1 online resource (x, 126 p. : ill.)
DescriptionFlash sintering is a unique consolidation method of applying an electric field directly on a specimen while heating it. This method results in outstanding densification results at temperature values typically 30-70% less than the conventional sintering temperature and at ultra-short time scales such as 1-2 orders of magnitude smaller than conventional sintering times. This technique has been used on many oxide and non-oxide ceramics and yielded high densification results. This thesis seeks to establish an improved understanding on mass flux phenomena at unit cell scale under an applied dc electric field utilizing energy dispersive x-ray diffraction (EDXRD). Titanium diboride (TiB2) and barium titanate (BaTiO3) were chosen as the materials of interest to investigate the electric field induced densification and phase transformation. Uniaxially cold pressed TiB2 and BaTiO3 particulate matters of ≤ 128 nm and ≤ 100 nm median particle size, respectively, were used. A custom made experimental setup was utilized for in-situ flash sintering experiments. An electric field of chosen amplitude, depending on the electrical properties of the material on which each experiment was carried out, was directly applied on the bulk sample while it was being subjected to thermal field. TiB2 samples showed no densification but oxidation and a phase transformation between already existing oxides in the raw commercial powder even in an inert atmosphere due to its high tendency to oxidation and poor sinterability. All new oxide peaks occurred upon current leakage were found to be of titanium borate (TiBO3). BaTiO3 was found to be more prone to densification compared to TiB2. 92% - 94% ρth was obtained in BaTiO3 pellets based on two different commercial powders as the temperature and sintering time ranging from ~400 °C to ~950 °C and from 24 seconds to ~1.5 minutes, respectively. This material, in addition to consolidation, showed a phase transformation from cubic to tetragonal structure under electric fields smaller than its coercive field. Ultra-high energy polychromatic radiation with photons of as much energy as 200 keV was employed as energy dispersive x-ray diffraction method (EDXRD) to collect data from the body center of each sample with a time interval as short as maximum 4 seconds while the sample was being subjected to thermal and electric fields. Changes in crystal parameters, and hence unit cell volume, were continuously tracked. Therefore, all mass transport phenomena was monitored and recorded with an error of ≤4 seconds. Phase transformations occurred under applied fields were determined by examining EDXRD data. Scanning electron microscope (SEM) and powder x-ray diffraction were also utilized for the characterization of BaTiO3 for continuity and completeness of the analysis on its consolidation.
NotePh.D.
NoteIncludes bibliographical references
Noteby Tevfik Ertugrul Ozdemir
Genretheses, ETD doctoral
Persistent URLhttps://doi.org/doi:10.7282/T31Z46GB
Languageeng
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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