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Measurement of the corrosion of the public lighting
Jalový, Michal ; TSB,, Josef Šaroun, provozně-technický ředitel (referee) ; Krutílek, David (advisor)
This thesis describes corrosion degradation processes taking place on the surface of metal materials in different environments. The theoretical part deals with basic environments we encounter in practice. This part specifies protection of materials against the aggressive environments and provides principles of corrosion measurement. It analyses the issue of corrosion measurement and its impact on mechanical strength of structures. It deals with the application of Electrochemical Impedance Spectroscopy (EIS) method for measurement of public lighting corrosion and identification of potential breakdown.
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Corrosion of Nonferrous Metal Materials
Ševčíková, Barbora ; Nový,, František (referee) ; Pacal, Bohumil (referee) ; Havlica, Jaromír (advisor)
In the presented dissertation thesis, I closely focused on corrosion resistance of non-ferrous metals. For full understanding of the possibilities for increasing corrosion resistance, it was vital to initially recognize the influences to the corrosion system of the samples and their surrounding environment. For this purpose, I focused on heat treatment, corrosion, and protective coatings, in the theoretical part of the thesis. For the subsequent research, it was necessary to define several constant variables, first. For this purpose, I have chosen a group of magnesium alloys, namely AZ91 Alloy and 3.5 % NaCl Electrolyte. AZ91 Alloy is of heterogenous structure formed by a solid solution of aluminum in magnesium, intermetallic phase in Mg17Al12, and their eutectic. Local microcells tend to occur in these heterogenities, which leads to faster corrosion. In order to increase corrosion resistance of the alloy, I used a combination of heat treatment and protective phosphate coating. For creating of the desired structure, which further affects compact coating formation, I selected a process involving solution heating with precipitation hardening T6. Secondary goals of the thesis involved optimization of standard technical procedures for the sake of increasing efficiency. With regard to this goal, I introduced optimized heat treatment T6 using accelerated cooling of a sample in water and liquid nitrogen. A modification besides the standard phosphating procedure was carried out with no activation step. For evaluation of corrosion resistance of the samples, I conducted water immersion tests using electrochemical methods; such as potenciodynamic curves combined with electrochemical impedance spectroscopy. In order to streamline the evaluation of the corrosion surface in technical practice, I used automatic detection. Substantial improvement of corrosion resistance of the above mentioned system, compared to heat-untreated samples, was proven through electrochemical methods. Due to accelerated cooling, a more homogeneous structure was achieved, which could be further utilized to create more uniform protective coating. For some phosphate coating, specifically manganese phosphate coating, I identified certain modifications that were in line with the set goals; i.e. skipping the activation phase, and using automatic detection for evaluation of uniform corrosion on the samples.
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Evaluation of electrochemical characteristics of AZ31 wrought magnesium alloy
Hána, Tomáš ; Tkacz, Jakub (referee) ; Drábiková, Juliána (advisor)
This thesis deals with the issue of electrochemical characterization of AZ31 wrought magnesium alloy, which was exposed to corrosive environment of 0.1 moldm3 solution of sodium chloride. Electrochemical impedance spectroscopy and potentiodynamic tests were used for evaluation of electrochemical characteristics such as corrosion rate, corrosion current density, corrosion potential and polarization resistance. There is a summary of ways of a production of magnesium alloys, influence of alloying element on properties of material and types of corrosion, which leads to degradation of material in the theoretical part. In the experimental part there is characterization of used methods, summary of results and a discussion of obtained data and its comparison.
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The application of electrochemical impedance spectroscopy for investigation of enzyme kinetics
Pospíšilová, Michaela ; Sedláček, Jiří (referee) ; Fohlerová, Zdenka (advisor)
The application of electrochemical impedance spectroscopy (EIS) in theory and experiment for investigation of redox enzyme kinetics has been already described. The impedance studies are quite sensitive to the changes at the interface caused by adsorption of charged species and therefore can be used to study the kinetics of adsorption of macromolecules and also enables us to study enzyme kinetics since the action of the enzymes on their substrates involved modification and generation of charged species. In this work, we would explore the potential of electrochemical impedance technique to follow the kinetics of glucose oxidasesubstrate reactions on the immobilized surface. The enzyme will be allowed to interact with different concentrations of its substrate and the resulting reaction will be recorded in real time. Changes in the imaginary component of the impedance at various substrate concentrations will be expected to follow MichelisMenten kinetics. The experimental procedure should be simple and can be carried out directly in buffer solutions most suited for the required interaction to take place, without the requirement of any additional redox probes.
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Corrosion of Nonferrous Metal Materials
Ševčíková, Barbora ; Nový,, František (referee) ; Pacal, Bohumil (referee) ; Havlica, Jaromír (advisor)
In the presented dissertation thesis, I closely focused on corrosion resistance of non-ferrous metals. For full understanding of the possibilities for increasing corrosion resistance, it was vital to initially recognize the influences to the corrosion system of the samples and their surrounding environment. For this purpose, I focused on heat treatment, corrosion, and protective coatings, in the theoretical part of the thesis. For the subsequent research, it was necessary to define several constant variables, first. For this purpose, I have chosen a group of magnesium alloys, namely AZ91 Alloy and 3.5 % NaCl Electrolyte. AZ91 Alloy is of heterogenous structure formed by a solid solution of aluminum in magnesium, intermetallic phase in Mg17Al12, and their eutectic. Local microcells tend to occur in these heterogenities, which leads to faster corrosion. In order to increase corrosion resistance of the alloy, I used a combination of heat treatment and protective phosphate coating. For creating of the desired structure, which further affects compact coating formation, I selected a process involving solution heating with precipitation hardening T6. Secondary goals of the thesis involved optimization of standard technical procedures for the sake of increasing efficiency. With regard to this goal, I introduced optimized heat treatment T6 using accelerated cooling of a sample in water and liquid nitrogen. A modification besides the standard phosphating procedure was carried out with no activation step. For evaluation of corrosion resistance of the samples, I conducted water immersion tests using electrochemical methods; such as potenciodynamic curves combined with electrochemical impedance spectroscopy. In order to streamline the evaluation of the corrosion surface in technical practice, I used automatic detection. Substantial improvement of corrosion resistance of the above mentioned system, compared to heat-untreated samples, was proven through electrochemical methods. Due to accelerated cooling, a more homogeneous structure was achieved, which could be further utilized to create more uniform protective coating. For some phosphate coating, specifically manganese phosphate coating, I identified certain modifications that were in line with the set goals; i.e. skipping the activation phase, and using automatic detection for evaluation of uniform corrosion on the samples.
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The application of electrochemical impedance spectroscopy for investigation of enzyme kinetics
Pospíšilová, Michaela ; Sedláček, Jiří (referee) ; Fohlerová, Zdenka (advisor)
The application of electrochemical impedance spectroscopy (EIS) in theory and experiment for investigation of redox enzyme kinetics has been already described. The impedance studies are quite sensitive to the changes at the interface caused by adsorption of charged species and therefore can be used to study the kinetics of adsorption of macromolecules and also enables us to study enzyme kinetics since the action of the enzymes on their substrates involved modification and generation of charged species. In this work, we would explore the potential of electrochemical impedance technique to follow the kinetics of glucose oxidasesubstrate reactions on the immobilized surface. The enzyme will be allowed to interact with different concentrations of its substrate and the resulting reaction will be recorded in real time. Changes in the imaginary component of the impedance at various substrate concentrations will be expected to follow MichelisMenten kinetics. The experimental procedure should be simple and can be carried out directly in buffer solutions most suited for the required interaction to take place, without the requirement of any additional redox probes.
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Evaluation of electrochemical characteristics of AZ31 wrought magnesium alloy
Hána, Tomáš ; Tkacz, Jakub (referee) ; Drábiková, Juliána (advisor)
This thesis deals with the issue of electrochemical characterization of AZ31 wrought magnesium alloy, which was exposed to corrosive environment of 0.1 moldm3 solution of sodium chloride. Electrochemical impedance spectroscopy and potentiodynamic tests were used for evaluation of electrochemical characteristics such as corrosion rate, corrosion current density, corrosion potential and polarization resistance. There is a summary of ways of a production of magnesium alloys, influence of alloying element on properties of material and types of corrosion, which leads to degradation of material in the theoretical part. In the experimental part there is characterization of used methods, summary of results and a discussion of obtained data and its comparison.
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Measurement of the corrosion of the public lighting
Jalový, Michal ; TSB,, Josef Šaroun, provozně-technický ředitel (referee) ; Krutílek, David (advisor)
This thesis describes corrosion degradation processes taking place on the surface of metal materials in different environments. The theoretical part deals with basic environments we encounter in practice. This part specifies protection of materials against the aggressive environments and provides principles of corrosion measurement. It analyses the issue of corrosion measurement and its impact on mechanical strength of structures. It deals with the application of Electrochemical Impedance Spectroscopy (EIS) method for measurement of public lighting corrosion and identification of potential breakdown.
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