This month I continued preparing and improving my PhD thesis. Additionally, I have submitted two abstracts for conferences. The first one is on 31.03-01.04 in London. The abstract:
Automated three-dimensional (3D) orientation microscopy was used for characterization of grain boundary geometry and pore morphology in cubic zirconia. A set of three samples sintered under different conditions was investigated. Specimens were composed of cubic zirconia stabilized by addition of 8 mol% of yttria. Investigations of grain boundaries and pore structures were carried out in a dual-beam field emission scanning electron microscope. For each sample, a volume of 15*103 μm3 was investigated. Stacks of inverse pole figure maps were used for visualization and reconstruction of sinters microstructure. The results of 3D analysis were compared to the ones derived from the regular, two-dimensional (2D) orientation maps from the areas of 2500 μm2. Based on 2D and 3D data the average grain diameter, number of grains, average number of neighbors and porosity were calculated. The average grain diameter varied in the range from 2.4 μm to 2.9 μm, and from 3.0 μm to 3.8 μm, while the level of porosity ranged from 1.22% to 1.77%, and from 1.30% to 5.61% for 2D and 3D data, respectively. The analysis of grain boundary networks revealed a strong dependence between grain boundary density and sample preparation parameters. Sintering parameters affected also the size and distribution of pores. The comparison between the 2D and 3D results revealed significant differences in the values of calculated microstructure parameters.
The second will be held in Oludenitz on 24.04-27.04. The abstract:
Due to the important role of grain boundaries in ion conductivity it is of great interest to analyze grain boundary character distribution in zirconia electrolytes which are widely applied in solid oxide fuel cells. Automatic serial sectioning and electron backscatter diffraction (EBSD) mapping was used to analyze grain boundary geometry and pore morphology in cubic zirconia sinters. A set of three samples composed of cubic zirconia stabilized by addition of 8 mol.% of yttria and sintered under different conditions was investigated. The analysis of grain boundaries geometry and pores microstructure were carried out in a dual-beam focused ion beam scanning electron microscope FEI Quanta 3D FEGSEM equipped with EDAX Trident system. For each sample, a series of parallel EBSD maps from the volume of 15•103 μm3 was collected. Stacks of inverse pole figure (IPF) maps and image quality (IQ) maps were used for reconstruction of sinters microstructure and visualization of pores distribution, respectively. The results of 3D analysis were compared with those acquired from two-dimensional (2D) EBSD measurements from the areas of 2500 μm2. Based both on 2D and 3D data, the average grain diameter, number of grains, average number of neighbors and porosity were calculated. The average grain diameter varied in the range from 2.4 μm to 2.9 μm for 2D and from 3.0 μm to 3.8 μm for 3D data, while the level of porosity ranged from 1.22% to 1.77% for 2D and from 1.30% to 5.61% for 3D. The analysis of grain boundary networks revealed a strong dependence between grain boundary density and ceramic fabrication. Sintering parameters affected also the size and distribution of voids. The comparison between the 2D and 3D results revealed some discrepancies in the values of calculated microstructure parameters. Thus, a great caution must be taken when deriving conclusions from 2D EBSD data.