|
|
Unconventional methods of welding of wrought magnesium alloys
Klimčáková, Kateřina ; Mrňa, Libor (referee) ; Doležal, Pavel (advisor)
Master's thesis deals with consideration possibility of conventional and unconvetional welding methods of wrought magnesium alloys. Methods of Friction Stir Welding, Pulsed Nd:YAG laser and Continuous Fiber laser was used to join magnesium alloy sheets AZ31, AZ61, ZE10 and ZE41. For studying influence of processing parameters on microstructure and mechanical properties were used methods of light microscopy, scanning electron microscopy, tensile tests and microhardness measurements. The results of tensile tests show that from the point of view of keeping ultimate tensile strength is the best methods for welding magnesium alloys Friction Stir Welding. Compared with Nd:YAG laser, fiber laser give better properties of welds. From comparing microstructure and mechanical properties . It wasn't found publications about Friction Stir Welding of magnesium ZE alloys or about FSW sheets with thickness only 0,8 mm and 1,6 mm.
|
|
|
Analysis of Iron-Phosphorus Reaction Products Formation During Heat Treatment Processes
Skoumalová, Zuzana ; Jan, Vít (referee) ; Doležal, Pavel (advisor)
During high pressure pulsation tests repeated cracks of CP3. housings occur. High pressure pump CP3 is part of injection system Common Rail. Cracks can be caused by segregation of phosphorous from a washing medium on grain boundaries during subsequent heat treatment process. The present master´s thesis focuses on analysis of phosphorous compounds on specimen surface made from steel 20MnCr5, which were soaked in solutions with different concentration of phosphorous. Master’s thesis is also focused on potencial influence of phosphorous on structure and properties of this material. The first part of the thesis provides a summary of current knowledge in the studied field, experimental results can be found in the second part. The surface analysis XPS, the light microscopy, the scanning electron microscopy equipped by energy dispersive chemical analysis, the glow discharge optical emission spectroscopy, the methods of the phase analysis by means of the X-ray diffraction and impact test were used.
|
|
|
Technology of manufacture and treatment of medieval arrowhead
Kašpar, Jan ; Stránský, Karel (referee) ; Stránský, Karel (referee) ; Doležal, Pavel (advisor)
This thesis analyses issue of manufacture, typology and use of medieval arrowheads. In theoretical part describe historical evolution of bow and his archaeological discovery in Europe, especially from medieval times. After that is revealed historical evolution of arrowheads and describe their typology. In next chapters are mentioned ways of iron production, mainly in early medieval times and also describe technology of manufacture different types of arrowheads. There is a characterization of medieval arrow, his construction and characteristics. Continuously in this background research are revealing questions of penetration depend on the various types of arrowheads, which are testing on the most known types of armour like chainmail or breast plate. In experimental part of this paper are metallographicaly analyzing archaeological discoveries from the early and late medieval times. Conclusions about their manufacturing, treatment and possibilities of use are built on knowledge about arrowheads structures, hardness and shapes.
|
|
|
Optimization of Manufacturing and Assembling Technology of the Valve Bolt
Hrouzková, Andrea ; Zapletal, Josef (referee) ; Doležal, Pavel (advisor)
The thesis aimed to study the impact of manufacturing and assembly technology, the valve bolt fitted to diesel high pressure pump CP3 in the Bosch, which has been found to leak. As experimental material was chosen heat treated bolts M16x1,5 made of material 12 050th. Groups of samples were produced in two ranges hardness. Experimental determination of the optimum range of hardness was assessed on the basis of the results of the process of the screw and set the value of plastic deformation of the sealing surfaces of the parts. Experimental section also deals with the analysis of bearing surfaces on the pump and the components, after the screw process. To some extent, is observed as surface treatment
|
|
|
Research and Development of Technology for Surface Layers of Roll and Sliding Bearings Components
Němcová, Aneta ; Klakurková, Lenka (referee) ; Doležal, Pavel (advisor)
To increase of bearing steels properties are research and development of surface modifications well above dedicated, in present. Basic requirements to the surface modifications are high wear resistance and good temperature resistance (origin by friction). Surface modifications can not negatively influence properties of bearing steels as a substrate. One of the possibilities can be used surface modifications used for high temperature applications. These are based on saturation of substrate surface layer by Al (and Si) elements. This work deals with preparing of Al and Al-Si diffusion layers from slurries on 100Cr6 bearing steel surface and study of elements interaction between coating and bearing steel as a substrate during proceeding of protective layers at high temperatures. To elements interaction study light microscopy, scanning electron microscopy equipped by energy dispersive microanalyses, glow discharge optical emission spectrometry and microhardness measurement methods were used. To the evaluation of layer thickness image analyses was used.
|
|
|
Project management
Smolíková, Lucie ; Doležal, Pavel (referee) ; Fiala, Alois (advisor)
Project preparation of operating program of competitive advantage education. Create new bachelor honours plan of Metrology and quality assurance testing. Project management. Preparing documents for project formation. Process of working projects. Summary of reguired documents to create projects.
|
|
|
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.
|
|
|
Element analysis of magnesium alloys using laser induced breakdown spectrometry
Veis, Samuel ; Fintová, Stanislava (referee) ; Doležal, Pavel (advisor)
Bachelor‘s thesis is aimed at assessing the possibilities of trace elements detection in magnesium alloys using laser induced breakdown spectroscopy with a focus on rare earth elements. Base materials were wrought magnesium alloy sheet ZE10 with thickness of 1,6 mm and ZE41 with thickness of 2 mm produced using Direct Chill casting method. Qualitative and quantitative ways of LIBS spectra evaluation were described in the work. Qualitative analysis confirmed the presence of La, Ce, Nd and Pr in ZE41, and La with Ce in ZE10. These informations confirm results of EDS analysis. For a demonstration, quantitative analysis of ZE10 was made, which confirmed the possibility of using LIBS for detection of REE in Mg alloys.
|
|
|
Propsective surface treatments of magnesium alloys
Drábiková, Juliána ; Doležal, Pavel (referee) ; Zmrzlý, Martin (advisor)
The aim of this bachelor thesis is to summarize the methods of surface treatment of magnesium alloys and discussion of theireffectiveness of corrosion protection. In contrast to other metallic material used in technical practice, magnesium alloys have the lowest corrosion resistance, which can be increased by alloying or by use of surface treatments. The introduction part of the thesis deals with general knowledge about magnesium, its alloys AZ31, AZ91 and their corrosion processes. The recherché includes actual results of research about these alloys. Emphasizedare fluoride conversion coatings and composite coatings based on nickel, where their preparation is described and attention is focused on their properties in the sense of corrosion protection. Concluding the work, we give a critical assessment of the pros and cons of corrosion protective coatings on Mg alloys. Finally, there are suggested some convenient experiments to prove the repeatability of results published in the recherché literature.
|
|
|
Evaluation of corrosion resistance of magnesium alloy AZ61
Hlavnička, Jiří ; Horynová, Miroslava (referee) ; Doležal, Pavel (advisor)
This work is foccused on assessment of corrosion resistivity and character of corrosion attack of AZ61 magnesium alloy. Squeeze casting specimens in both as-cast state and in solution annealing state were used as the experimental material. Corrosion degradation was performed in a salt spray fog (5% solution of sodium chloride). Mechanism of corrosion, appearance and depth of corrosion attack have been evaluated.
|
guest ::
RSS feed.