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Passivation of Aluminum and Aluminum Alloys in passivation baths without Cr6+ Compounds
Macháč, Pavel ; Tulka,, Jaromír (referee) ; Molliková, Eva (advisor)
This diploma thesis deals with evaluation of efficiency of protection conversion coatings created by passivation metals and alloys in passivation baths without chromium compounds. The theoretical part is initially concerned with question of electrochemical corrosion of metals, consequently there are mentioned different methods of corrosion protection. The main section of theoretical part of this thesis deals with chromate conversion coatings, description of their protective efficiency (including their unique self-healing effect) and then with account of new chromate-free conversion coatings occurring as chromate alternatives, whose usage is constrained because of their content of hexavalent chromium, which is highly toxic, oxidizing and also carcinogenic and thereby very dangerous for human body and the environment. Experimental part of this thesis is concerned with evaluation of efficiency of particular conversion coating which is quite commonly use in some applications as chromate alternative. It is chromate-free conversion coating which is created by passivation of metals or alloys in passivation bath Pragokor BP, which contains zirconium fluorocomplexes and is without any chromium or other toxic or ecologically unhealthy compounds. The influence of sealing of the coating in preparation Pragokor Seal Al and also other surface treatments such as application of conservation wax WAXENG or cold application of zinc coating were tested too. Efficiency of mentioned surface treatments was then evaluated on aluminum and steel by laboratory accelerated and atmospheric corrosion testing.
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Passivation of germanium surface using ALD
Kuba, Jakub ; Polčák, Josef (referee) ; Kolíbal, Miroslav (advisor)
The thesis deals with passivation of germanium surfaces by chemical etching and atomic layer deposition (ALD). Attention was paid to the rate of oxidation of germanium surfaces after selected passivation methods and the composition of the germanium suboxides. In the thesis selected methods for germanium oxide removal are reviewed and a brief description of the methods used for analysis (XPS) and thin film deposition (ALD) is given.
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Surface Modification of Zinc Alloys
Kinc, Marek ; Foral, Karel (referee) ; Molliková, Eva (advisor)
The object of this bachelor’s thesis is to create a research in field of zinc alloys. In the first part, there are outlined production of pure zinc with a different methods and briefly described the treatment of waste. The next are described the zinc alloys and their properties and outline the ways of die casting. The end of this thesis is focused on methods of finishing the surfaces.
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Stainless steels
Chára, Tomáš ; Kalina, Lukáš (referee) ; Zmrzlý, Martin (advisor)
This thesis deals with stainless steels. The theoretical part describes the mechanisms and types of corrosion. Then the thesis deals with the properties, distribution and manufacture of the stainless steels and a brief description of the XPS method used for the practical part. In the recherche section summarizes the ways of using the XPS method for determining the quality of the passive layer of stainless steels eaten in different environments. Practical task was to compare the quality of the passive layer of stainless steels resulting from natural and chemical passivation.
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Evaluation of the efficiency of operation of a mechanical, high-temperature and high-pressure filter in NPP Temelín.
JAROŠ, Luboš
The primary circuit with the VVER1000{--}320V reactor installed in the nuclear power plant Temelín represents a world-unique technology in terms of reduction of concentration of corrosion products and activated corrosion products by means of mechanical, high-temperature and high-pressure filters. The technology uses continual filtration and its main advantage is cleaning of the primary coolant at operating parameters, i.e. without any adjustments of pressure and temperature of the filtered coolant. The filter is made of especially treated titanium, whose spongy form improves the required interception of undissolved corrosion products and activated corrosion products on its surface. It contributes to limitation of formation of radiation fields and it favorably affects reduction of the effective dose received by the plant{\crq}s operating personnel. In my thesis I have monitored behavior of the corrosion products and activated corrosion products intercepted on the mechanical, high-temperature and high-pressure filters. In the evaluation I have focused on efficiency of operation of one of the selected filters in case of changes in physicochemical parameters in the primary circuit during reactor shutdown and on determination of a potential release of corrosion products and activated corrosion products back into the primary coolant and resulting deterioration of a radiation situation in the proximity of the technological equipment before refueling.
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