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Corrosion resistance of aluminum alloys
Kouba, Jan ; Pacal,, Bohumil (referee) ; Zmrzlý, Martin (advisor)
This diploma thesis deals with cerium-based conversion coatings for aluminium alloys. At first the mechanism of protection of metals by inhibitory substances is described in the theoretical section. The next chapter is devoted to application of lanthanide salts as cathodic corrosion inhibitors. Then the characterization of alloy AA 2024 follows. The main part is dedicated to the growth mechanism of the cerium-based mixed conversion coating on the alloy AA 2024. Finally, the factors affecting the character and the quality of obtained coatings are commented. In the experimental part an influence of the thermal activation together with the activation by a hydrogen peroxide was observed. The created film was characterized using SEM and EDS. The level of corrosion protection was evaluated by the polarization resistance measurement. erized using SEM and EDS. The level of corrosion protection was evaluated by the polarization resistance measurement.
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Preparation of historical binders with high resistance to ambient influences
Nehybka, Josef ; Palovčík, Jakub (referee) ; Opravil, Tomáš (advisor)
This master’s thesis is focused on preparation of the mortar mixtures inspired by roman cement with a great resistivity against the corrosion environment, especially a seawater. There were prepared samples of a roman cement containing of pure lime and various artificial pozzolans and natural tuff which were used as pozzolan admixtures. The task of this work is to explore possibility of using pure lime and for example pozzolan admixture which can resist against the corrosive environment like a roman cement. There were prepared a lot of various samples which were tested separately on their mechanical characteristics before and after their exposure of the influence of the corrosive environment. There were used X-ray diffraction analysis for the characterization of a phase composition of the raw materials and some selected samples.
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Corrosion layers removal in low-pressure plasma
Kujawa, Adam ; Grossmannová, Hana (referee) ; Krčma, František (advisor)
A plasmachemical reduction of corrosion layers on copper was studied. In this case two series of copper samples were prepared and putted in two corrosive environments for one week. The first corrosive environment contained a concentrated nitric acid and the second environment contained a concentrated sulfuric acid. Samples thus prepared were ready to be plasmachemicaly treated. The plasmachemical reductions took place in low-temperature, low-pressure, non-isothermal, high-frequency-inducted hydrogen plasma on the Faculty of Chemistry in University of Technology in Brno. The discharge was generated in continual or pulse mode with changeable pulse ratio. To monitor the reduction process an optical emission spectroscopy was used. The radiation from plasma discharge was measured by an optical spectrometer in the intervals of 1 to 10 minutes. An object of our concern in collected spectrum was the radiation of OH radicals with electromagnetical wavelenght in a range of 305 – 330 nm, and which were produced in a reaction between the hydrogen radicals and the oxygen atoms, contained in the corosion layers. A rotation temperature of plasma was calculated from the spectrums of OH radicals in a dependence of discharge conditions. Gathered findings will give us a better knowing of this conservation technique, that is used for treatment of the corroded surfaces of the archeological artifacts, and will also allow more provident appliance of this method on a copper historical objects.
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Examination of the activity and possibility verification ability of various types of corrosion inhibitors
Kroča, Michal ; Švehla, Vladimír (referee) ; Drochytka, Rostislav (advisor)
The aim of the work is to describe the degradation of concrete structures from the perspective of corrosion of steel reinforcement. The basis of a detailed survey and analysis of additives containing corrosion inhibitors, designed to improve the concrete matrix and increased protection of steel reinforcement. The essential part is a summary of the detection methods designed to verify the presence of inhibitors in reinforced concrete (direct method) or anti - corrosion effect on steel reinforcement (indirect method). Subsequently, to compare the available products in the market based on their characteristics and parameters, including prices and environmental point of view. From the data obtained is drawn optimization calculation, the output of which is to determine nevhodnějšího product for protection of steel reinforcement embedded in concrete structures, especially at a dosage rate specified by the manufacturer.
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Anticorrosive modification of electric motors surface
Vlčková, Irena ; Straková, Monika (referee) ; Gráf, Jiří (advisor)
This Master´s thesis is devoted to the basic theory from semester project. There are describe completed practical tests, measurements and results. This project was written below patronage of company Siemens s.r.o. odštěpný závod Elektromotory Mohelnice, which is at the same time also my employer. There is production of asynchronous electromotors frame size 56 to 200. On the all of electromotors is desired quality surface treatment with difference on the base of request of customers.
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Conversion coatings and their characterisation
Březina, Matěj ; Doležal, Pavel (referee) ; Zmrzlý, Martin (advisor)
Aim of this study is to improve corrosion resistance of magnesium alloy AZ91 by conversion coatings. Influence of alloy microstructure on conversion coating growth and corrosion resistance was evaluated. Properties of pure magnesium and magnesium alloy AZ91 as well as the influence of alloying elements on properties of this alloy are described in theoretical part. Recent results of corrosion protection by conversion coatings on AZ type magnesium alloys are summarised in recherché part. Practical part focuses on preparation of hexavalent chromium based conversion coating and phosphate-permanganate based conversion coating on as cast AZ91 magnesium alloy, these coatings were subsequently applied on annealed AZ91 magnesium alloy. Corrosion protection of the coatings prepared on as cast and annealed alloy was evaluated by potentiodynamic measurements and testing in neutral salt spray. Furthermore the influence of plasma activation on phosphate-permanganate coating surface was studied.
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Materials for biodegradable bones based on Fe
Hrabovský, Jan ; Vondrák, Jiří (referee) ; Sedlaříková, Marie (advisor)
The thesis deals with biodegradable bone implants which must have good mechanical properties and also good compatibility with the human body. The thesis contains literary research in the area of bone physiology, biogenic materials and implants for the human body. The thesis focues on the selection of suitable materials for biogenic implants. It is also described the preparation of iron powder mixtures and application onto selected materials. The selected samples were subjected to thermal analysis.
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The effect of plastic strain of the reinforcement of aircraft panel made from aluminium alloy on the corrosion process
Valoušek, Tomáš ; Tulka, Jaromír (referee) ; Pacal, Bohumil (advisor)
This bachelor thesis is focused on study of corrosion of reinforcement panel of aircraft in environment of salt fog. The reinforcement material is aluminum alloy AlZnMgCu1,5 after solution annealing, release stress relieving and artificial aging, can be slighly deformed to compliance limit deviation. Material is not provided with any coating. The aim was to find out what is the effect of plastic deformation on the corrosion behavior of this alloy. In the experimental part of this thesis were studied the size and type of corrosion attack of samples with different plastic deformation. These values were furhter processed, evaluated and were drawn from them conclusions.
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