Thursday, 6 February, 2014, 11:54 Posted by Piotr Drzymala
Worked to improve the orientation and disorientation calculator. While in the case of parameterization Rodriguez Vector representation does not cause many problems , apart from the need to become familiar with the shape of the primary zones for orientation and disorientation , the Euler parameterization of a challenge. The first observation is that the data supplied from the TSL program in the form of a matrix orientation expressed as Euler angles ( φ1 , Φ , φ2 ) are not brought to the area of ​​basic orientation . Perhaps it can be set in the program, but due to the difficult access to equipment and generalization of the calculation in the calculator and so it is impossible to avoid these transformations . The fact that the orientations are not reduced to the primary area can be seen at the level of individual grains which have a consistent orientation of the domain . Such grains can not be described on average one three numbers ( φ1 , Φ , φ2 ), but his relationship orientation has n equivalence classes (n depend on the symmetry of the crystallites ) , due to the lack of conversion to one particular area of ​​the primary . The next problem was how to draw Euler angles of the rotation matrix . Angles drawn in accordance with the formula φ1 = ArcTan [- g [ [ 3, 2 ]] g [ [ 3, 1 ]]] , Φ = ArcCos [g [ [ 3, 3 ]]] , φ2 = ArcTan [g [ [ 2, 3 ] ] , g [ [ 1, 3 ]]] , where the function ArcTan meant extensive arkus tangent , taking into account the sign of expressions. Then had properly wrap Euler angles , as these drawn from the matrix of rotation could be negative. The first step was to add or subtract one period 2π , that is modulo 2π to perform an operation on each of the angles. Then , if the angle Φ exceeded π , to be added to φ1 and φ2 value of π , and for the new Φ recognize the value of 2π - Φ . Then again , of course, had to bring the angles φ1 and φ2 to φ1 numbers mod ( 2π ) and φ2 mod ( 2π ) .
Wednesday, 5 February, 2014, 07:24 Posted by Zbigniew Starowicz
Main subject among January experiments was photochemical deposition of silver nanoparticles on titania substrates.This experiment was conducted and directed on investigtion of first stages of the deposition hence nucleation stage. For that matter illumination time was set on 5 min. Five different silver nitrade solution concentration (0,5, 1, 2, 5 10mM) were investigated under three levels of laser light intensity ( low, meidum, high). The blue laser ( 405nm) was used. The titania was previously annealed in 500 Celcius degrees. It is expected that different conditions should result in different microstructure formation. The samples will be examined by HR SEM imiging in following months.
January 2014/ P. Bobrowski
Tuesday, 4 February, 2014, 11:13 Posted by Piotr Bobrowski
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.
PhD report (January 2014) M.Gajewska
Monday, 3 February, 2014, 11:03 Posted by Marta Gajewska
In January, I continued my works on the thesis, namely on a part of literature review concerning production methods of particle reinforced aluminium matrix composites, e.g. mechanical alloying, reactive gas injection, etc.. I also performed some supplementary TEM investigations of in situ Al/AlN composites produced via reactive sintering.
January K. Stan-Glowinska
Monday, 3 February, 2014, 09:33 Posted by Katarzyna Stan
This month I pulverized ribbons with two types of compositions. Obtained powders were used to prepare bulk samples by hot pressing. I have started to analyze these samples by XRD and SEM. First results are promising. During this month I have prepared an abstract for the XV International Conference on Electron Microscopy concerning in-situ heating of melts spun ribbons with quasicrystalline particles.
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