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Plasma and microplasma welding
Ryšavý, Radek ; Kubíček, Jaroslav (referee) ; Daněk, Ladislav (advisor)
The first part of the bachelor thesis is devoted to literary recherche, which describes plasma welding and microplasma welding. Here is explained the principle of these technologies, the types of burners and the gases that enter them. Comparison of advantages and disadvantages of plasma welding and microplazma welding. And consequently the industries in which these technologies are used. The second part is devoted to the comparison of two welds. These were made by similar welding parameters. For both welds the specific heat input was calculated. Subsequent metallographic macrostructure evaluation, which used to calculate the dilution of the weld metal. Finally, hardness measurements were performed in three areas of welding: basic material, heat-affected area and weld metal.
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Optimization of process parameters for the laser welding of thin-walled blanks of stainless steel
Kačírek, David ; Daněk, Ladislav (referee) ; Mrňa, Libor (advisor)
For increase productivity, the current technology of welding pipes bellows was replaced by laser welding. Experiment was carried out on the material of austenitic stainless steel 1.4541 for sheet thickness 0.25 mm and 0.15 mm. On sheet 0.25 mm was achieved comparable mechanical properties as the current manufacturing process upon achieving 10 times higher welding speeds. Samples of 0.15 mm thickness achieved to about 30% lower deepening over existing technology. For improvement was advised to reduce heat input. From an economic assessment shows that the price per 1 m of weld decreases with increasing speed welding. With higher welding speeds reduces the heat input.
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Noise diagnostics of rectifier diodes PN junctions
Klimíček, Jaromír ; Macků, Robert (referee) ; Raška, Michal (advisor)
The thesis deals with the design of the measurement installation, which is intended for the microplasma noise measurements. This noise is being generated in the defective parts of the PN junction. The goal of this work is to design the measurement installation and to realize the fully functional workbench for the analogical noise related measurements and to determine the transfer function of the measurement installation. Main part of the work is to choose proper parameters for the measuring devices and to design the software intended for the automated measurements. Consequently, we have to process the measured waveforms of the microplasma noise, to determine the dependency of the noise on the signal magnitude and to calculate the power spectral noise density. Finally, we have to determine the transfer function of the measurement installation and to design the inversion filter.
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Usage Local Light Radiation for the Diagnostic Method of Photovoltaic Cells
Dolenský, Jan ; Šály, Vladimír (referee) ; Unčovský,, Marek (referee) ; Vaněk, Jiří (advisor)
This thesis is focused on the area of analysis and diagnostic of monocrystalline solar cells, using local light radiation. Main goals of this thesis are focused on explanation of generation and behavior microplasma in solar cell, in dependence of temperature and reversed bias voltage. As a next focus of this thesis is strong regions of microplasma sources, analyzed by scanning electron microscope and a detailed analysis of edge and surface structure is made. The influence of the environment (air pressure, level of vacuum and nitrogen gas) on the microplasma generation and behavior is observed in the vacuum chamber of electron microscope. The results from microplasma method are correlated with noise diagnostic method and on the base of these results are set a new thesis and mathematical equations for the defects behavior in different conditions. The outcomes of the research are shared with the manufacturer od silicon solar cells, Solartec s.r.o. company. It is the advanced diagnostic methods that allow improving the quality of the production process, through early detection of individual groups of defects.
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Noise diagnostic of solar cells
Krahulec, Martin ; Macků, Robert (referee) ; Sadovský, Petr (advisor)
The thesis deals with detailed theoretical and experimental investigation of noise and transport characteristics of selected photovoltaic cells in both forward and reversed directions focusing on the area of local PN junction instability (within the microplasma regions). It will be studied the correlation among different characteristics.
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Plasma and microplasma welding
Ryšavý, Radek ; Kubíček, Jaroslav (referee) ; Daněk, Ladislav (advisor)
The first part of the bachelor thesis is devoted to literary recherche, which describes plasma welding and microplasma welding. Here is explained the principle of these technologies, the types of burners and the gases that enter them. Comparison of advantages and disadvantages of plasma welding and microplazma welding. And consequently the industries in which these technologies are used. The second part is devoted to the comparison of two welds. These were made by similar welding parameters. For both welds the specific heat input was calculated. Subsequent metallographic macrostructure evaluation, which used to calculate the dilution of the weld metal. Finally, hardness measurements were performed in three areas of welding: basic material, heat-affected area and weld metal.
|
|
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Optimization of process parameters for the laser welding of thin-walled blanks of stainless steel
Kačírek, David ; Daněk, Ladislav (referee) ; Mrňa, Libor (advisor)
For increase productivity, the current technology of welding pipes bellows was replaced by laser welding. Experiment was carried out on the material of austenitic stainless steel 1.4541 for sheet thickness 0.25 mm and 0.15 mm. On sheet 0.25 mm was achieved comparable mechanical properties as the current manufacturing process upon achieving 10 times higher welding speeds. Samples of 0.15 mm thickness achieved to about 30% lower deepening over existing technology. For improvement was advised to reduce heat input. From an economic assessment shows that the price per 1 m of weld decreases with increasing speed welding. With higher welding speeds reduces the heat input.
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Usage Local Light Radiation for the Diagnostic Method of Photovoltaic Cells
Dolenský, Jan ; Šály, Vladimír (referee) ; Unčovský,, Marek (referee) ; Vaněk, Jiří (advisor)
This thesis is focused on the area of analysis and diagnostic of monocrystalline solar cells, using local light radiation. Main goals of this thesis are focused on explanation of generation and behavior microplasma in solar cell, in dependence of temperature and reversed bias voltage. As a next focus of this thesis is strong regions of microplasma sources, analyzed by scanning electron microscope and a detailed analysis of edge and surface structure is made. The influence of the environment (air pressure, level of vacuum and nitrogen gas) on the microplasma generation and behavior is observed in the vacuum chamber of electron microscope. The results from microplasma method are correlated with noise diagnostic method and on the base of these results are set a new thesis and mathematical equations for the defects behavior in different conditions. The outcomes of the research are shared with the manufacturer od silicon solar cells, Solartec s.r.o. company. It is the advanced diagnostic methods that allow improving the quality of the production process, through early detection of individual groups of defects.
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