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The analysis of Fe-Cr-Ti binary alloys
Lauš, Lukáš ; Havlík, Petr (referee) ; Jan, Vít (advisor)
The aim of this bachelor thesis is the preparation of high volume ratio of intermediate phases in the microstructure of Ti-Fe, Fe-Cr, Ti-Cr. The bibliographic introduction includes basic information about phase equilibrium diagrams. It also includes phases in metal systems and the binary diagrams of the prepared alloys. The experimental part deals with the analysis of the alloy phases. The experimental part also deals with determination of alloys microstructure parts using calculated pseudobinary diagrams. It has been found, that although prepared from pure stock materials, the produced alloys were not binary and contained 0,6–1,4 at. % Si. Intermediate phases were found in Ti-Fe and Ti-Cr alloys. According to the calculated diagrams comparison, all of the prepared alloys were not in equilibrium.
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Hydrogels amino-dextran-surfactant: phase diagram
Daňková, Kristýna ; Hurčíková, Andrea (referee) ; Pekař, Miloslav (advisor)
This bachelor thesis deals with a study about hydrogel systems based on the physical interactions of the oppositely charged particles, specifically interactions between positive polyelectrolyte and negative detergent. The phase diagrams were created based on the visual evaluation of results of the laboratory experiment, which is a part of this thesis, for in advance chosen concentration of the polymer diethylaminoethyl-dextran hydrochloride and detergents sodium dodecyl sulphate and sodium tetradecyl sulphate. These phase diagrams characterize incurred dextran systems.
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Hydrogels hyaluronan-surfactant: phase diagram
Gruberová, Eliška ; Hurčíková, Andrea (referee) ; Pekař, Miloslav (advisor)
This bachelor’s thesis deals with phase separation of the hyaluronan-cationic surfactant system in a model physiological solution of 0,15 M NaCl resulting in gel formation. The most widely used concentrations of hyaluronan and a wide range of surfactant concentrations was used to form the gel. We have investigated under which conditions the greatest amount of compacted gel was produced. It has been found that phase separation occurs over the entire concentration range. The largest amount of gel was formed at the highest concentration of both hyaluronan and surfactant. The results were plotted in well-arranged graphs. A hydrophobic colorant was used to indicate the presence of micellar formations and the results were depicted in a schematic phase diagram.
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LiF-NaF-KF Coolant Phase Diagram
Mikula, Hynek ; Matal, Oldřich (advisor)
In introduction this graduation theses discource about phase diagrams and thein fission. Next part is about concrete phase diagrams NaF – KF, NaF – LiF, KF – LiF. Their determination trough use of cooling surves and their specification trough use of numerical method. Conclusion contains proposal of method for concrete phase diagram of NaF – KF – LiF.
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Structural changes in intermetallic compounds
Doležal, Petr ; Prchal, Jiří (advisor)
This diploma thesis is focused on the study of the structural phase transitions in intermetallic compounds LaPd2(Al,Ga)2 by low-temperature x-ray powder diffraction and macroscopic measurements on single crystals. The results obtained from powder diffraction at room temperature confirm that the compounds crystallize in tetragonal CaBe2Ge2 structure type (space group P4/nmm). At low temperature all the compounds undergo the same structural phase transition by lowering the symmetry to the orthorhombic space group Cmma. Although the structural transformation is of first order, the transition is not-manifested in step-like change of the phase at a certain temperature, but occurs in a broader temperature interval. In this interval the different phases coexist and transform gradually from high- to low- temperature phase. After application of hydrostatic pressure the structural transition is shifted to higher temperatures. Despite that the low temperature structures are of the same type, there is a difference between compounds containing Ga and Al in the discontinuity of the lattice parameters resulting in a distinct anomaly in electrical resistivity. In pressures >0.6 GPa this characteristic anomaly on single crystalline CePd2Al2 is changed, indicating a pressure- induced change of the low-temperature...
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Structural changes in intermetallic compounds
Doležal, Petr ; Prchal, Jiří (advisor) ; Daniš, Stanislav (referee)
This diploma thesis is focused on the study of the structural phase transitions in intermetallic compounds LaPd2(Al,Ga)2 by low-temperature x-ray powder diffraction and macroscopic measurements on single crystals. The results obtained from powder diffraction at room temperature confirm that the compounds crystallize in tetragonal CaBe2Ge2 structure type (space group P4/nmm). At low temperature all the compounds undergo the same structural phase transition by lowering the symmetry to the orthorhombic space group Cmma. Although the structural transformation is of first order, the transition is not-manifested in step-like change of the phase at a certain temperature, but occurs in a broader temperature interval. In this interval the different phases coexist and transform gradually from high- to low- temperature phase. After application of hydrostatic pressure the structural transition is shifted to higher temperatures. Despite that the low temperature structures are of the same type, there is a difference between compounds containing Ga and Al in the discontinuity of the lattice parameters resulting in a distinct anomaly in electrical resistivity. In pressures >0.6 GPa this characteristic anomaly on single crystalline CePd2Al2 is changed, indicating a pressure- induced change of the low-temperature...
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Consequences of applying the hydrostatic pressure on the structural jump in RTAl compounds
Doležal, Petr ; Prchal, Jiří (advisor) ; Javorský, Pavel (referee)
Title: Consequences of applying the hydrostatic presure on the structural jump in RTAl compounds Author: Petr Doležal Department: Department of Condensed Matter Physics Supervisor: RNDr. Jiří Prchal, PhD., Department of Condensed Matter Physics Abstract: This bachelor thesis investigates the effects of hydrostatic pressure on structural transition in GdNiAl compound (ZrNiAl-type of structure), which have not been studied yet. This structural transformation represents an existence of a range of forbidden values of the lattice parameters ratio c/a, which cannot be adopted by compounds crystallizing in this type of structure. It prefers rather a step-like change of the parameters a and c. An anomalous behavior of resistivity, which appears in the area of the transition, was used for the structural transition determination. The results are accompanied by measurements of electrical resistivity at ambient pressure. Measurements on a polycrystalline sample suggested an anomalous behavior depicting the pressure dependence of the structural transition temperature. The pressure evolution of the structural transition temperature of a virgin sample is decreasing, being a consequence of higher sensitivity of the lattice constant c. Repeating the same experiment on the same piece of sample - i.e. sample with the...
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Lead-Free solder thermal and microstructure analysis
Klepárníková, Eliška ; Molliková, Eva (referee) ; Jan, Vít (advisor)
The bachelor thesis deals with Ag-Sn-Sb system, construction of pseudobinary diagram 90An10Sb – 90Sn10Sb and construction of ternary diagram at 20 C. The theoretical part deals with soldering, phase diagrams and methodics of determination of phase diagrams. The experimental part is focused on describing the creation of five alloys and their further exploration. Alloy analyzes were performed by differential scanning calorimetry (DSC), light microscope and scanning electron microscope. Results from these thermal and microstructural analyzes were processed into the resulting pseudobinary and ternary diagram.
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The possibilities of SMD components soldering by equipment Fritsch
Juračka, Martin ; Šandera, Josef (referee) ; Adámek, Martin (advisor)
This thesis focuses on soldering technology in microelectronics. It describes in detail the basic ways of soldering and repairs in electronics. This piece of work shows the principles of technological equipment for bulk soldering and used repairing devices. In the theoretical part of this work there are also briefly described the packages for integrated circuits that were used in the practical part of the thesis. The practical part of the thesis deals with setting of the heat profiles for hot air repair station Fritsch Mikroplacer for LQFP64, SOIC16, TSSOP14, QFN16 and DSBGA5 packages. The heat profiles for assembly and disassembly of the particular types of the packages on designed and manufactured test printed circuit board were set and tested. The resulting heat profiles are compared with the recommended heat profile of an ordinary solder paste SnAg3Cu0,5 which was used for the test. This thesis can serve as an aid for the further settings of heat profiles in other types of packages not only on Fritsch Mikroplacer devices, but also on other repairing devices of this type.
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