|
| |
|
|
Magnesium alloys
Březina, Matěj ; Šoukal, František (referee) ; Zmrzlý, Martin (advisor)
The study is focused on corrosion and corrosion protection of magnesium and magnesium alloys. The theoretical part describes properties of magnesium and magnesium alloys. It shows their advantages as well as their disadvantages and discusses ideal use for these alloys. The theoretical part analyses basic corrosion characteristics and typical corrosion processes. It deals with types of corrosion protection and ways of its use. The experimental part was focused on metallographic analysis and corrosion behavior of magnesium alloy AZ91. Metallographic methods were used for preparing AZ91 to corrosion tests. The experimental part compared corrosion rate and degradation of pure AZ91 and AZ91 with conversion coating (phosphate-permanganate) in 3,5% sodium chloride solution in times: 1, 8 and 48 hours.
|
|
|
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.
|
|
|
Optimalisation of evaluation methods for phosphating bathes
Brzuchańská, Anna ; Trčka, Josef (referee) ; Zmrzlý, Martin (advisor)
This work deals with phosphating technology of steel. In theoretical part are summarized facts about conventional phosphating process, including steel surfaces pretreatment. In the next chapter the latest contemporary technology of phosphating is discussed, i.e. electrolytic phosphating. This chapter contains principles and characteristics of this technique. Than follow comparisons of electrolytic phosphating and conventional process, concerning economical and ecological aspects. In experimental part is firstly stated nowaday situation of process analyses of phosphating bath for electrolytic phosphating. Intention of experimental part is finding of analytical technique which can be used in operating conditions of phosphating production line. Next chapter render an account of all analytical techniques – measuring of density, refractive index, conductance, reduction potential, pH, turbidity and determination of sulphate, iron and phosphate by indicator papers. Discussion of all results leads to conclusions on tested techniques in connection with practical use in operating conditions of phosphating production line and recommendations for use of individual analytical techniques.
|
|
|
Passivation of magnesium alloys
Krejčířová, Dana ; Sponar, Jan (referee) ; Zmrzlý, Martin (advisor)
Diploma thesis deals with the technology of surface modifications of magnesium alloys. Basic knowledge from the field of the corrosion of metal materials. The division corrosion according to way of attack and corrosion environment, etc. There is an enumeration of ways of the corrosion defence. Questions of surface modifications with an emphasis on passivation by conversion coating and its analysis. Characteristics of magnesium and its alloys. Magnesium alloys with lithium, possibilities of its passivation and the verification of corrosion resistance. Enumeration of the used devices, chemicals and materials. characteristics of the used alloys. creation of the corrosion resistance standard. Research in passivation on the alloy containing 12 percent of lithium. The verification of the corrosion test usability based on the suggestion of the background research results. The test results for passivated as well as untreated samples and the reference material (steel). Aplication of chromate-free passivation and corrosion test on the alloy containing 12 percent of lithium.
|
|
|
Fluoride conversion coatings on composite Mg/MgO materials
Peroutka, Jakub ; Buchtík, Martin (referee) ; Hasoňová, Michaela (advisor)
Bachelor thesis deals with preparation of composite materials based on Mg/MgO and their subsequent coating with fluoride conversion coating. Materials based on Mg/MgO were prepared by powder metallurgy. The theoretical part contains of basic magnesium information, advantages and disadvantages of Mg and brief Mg preparation. In the next part there are summarized basic principles, advantages and disadvantages in powder metallurgy. The second theoretical part deals with basic properties of MgO, literary research which deals with description of MgO on chemical structure of different varieties of Mg alloys or composition materials based on Mg/MgO. The last part of theoretical part describes conversion coatings, brief description of chemical reaction kinetics and diffusion of fluoride conversion coating. The experimental part deals with preparation of composite materials based on Mg/MgO by powder metallurgy. The main goal of experimental part was description of possible effect of MgO content on the formation of fluoride conversion coating.
|
|
|
Fluoride conversion coatings on composite Mg/MgO materials
Peroutka, Jakub ; Buchtík, Martin (referee) ; Hasoňová, Michaela (advisor)
Bachelor thesis deals with preparation of composite materials based on Mg/MgO and their subsequent coating with fluoride conversion coating. Materials based on Mg/MgO were prepared by powder metallurgy. The theoretical part contains of basic magnesium information, advantages and disadvantages of Mg and brief Mg preparation. In the next part there are summarized basic principles, advantages and disadvantages in powder metallurgy. The second theoretical part deals with basic properties of MgO, literary research which deals with description of MgO on chemical structure of different varieties of Mg alloys or composition materials based on Mg/MgO. The last part of theoretical part describes conversion coatings, brief description of chemical reaction kinetics and diffusion of fluoride conversion coating. The experimental part deals with preparation of composite materials based on Mg/MgO by powder metallurgy. The main goal of experimental part was description of possible effect of MgO content on the formation of fluoride conversion coating.
|
|
|
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.
|
|
| |
|
|
Passivation of magnesium alloys
Krejčířová, Dana ; Sponar, Jan (referee) ; Zmrzlý, Martin (advisor)
Diploma thesis deals with the technology of surface modifications of magnesium alloys. Basic knowledge from the field of the corrosion of metal materials. The division corrosion according to way of attack and corrosion environment, etc. There is an enumeration of ways of the corrosion defence. Questions of surface modifications with an emphasis on passivation by conversion coating and its analysis. Characteristics of magnesium and its alloys. Magnesium alloys with lithium, possibilities of its passivation and the verification of corrosion resistance. Enumeration of the used devices, chemicals and materials. characteristics of the used alloys. creation of the corrosion resistance standard. Research in passivation on the alloy containing 12 percent of lithium. The verification of the corrosion test usability based on the suggestion of the background research results. The test results for passivated as well as untreated samples and the reference material (steel). Aplication of chromate-free passivation and corrosion test on the alloy containing 12 percent of lithium.
|
guest ::
