National Repository of Grey Literature 41 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Influence of cooling rate on microstructure and mechanical properties of castings from magnesium alloys AZ91, WE43B and Elektron21 produced by investment casting
Jakubcová, Eliška ; Klakurková, Lenka (referee) ; Juliš, Martin (advisor)
This master's thesis deals with the effects of the cooling rate on the grain size of magnesium alloys based on Mg–Al (AZ91E) and Mg–Zr–RE (WE43B and Elektron21). The effects of the cooling rate are analyzed on samples of varying thickness for different cooling methods (forced–air–cooling, cooling into polymer, natural air cooling). We also evaluated the final microstructure, porosity, hardness, and mechanical properties for investment castings. Based on the evaluated grain sizes, we demonstrated a significant difference in the cooling rate influence on the grain size for the alloy AZ91E. Compared to Zirconium-based alloys (WE43B and Elektron21), for which the zirconium content influences grain size the most. For the alloys based on Mg–Zr–RE, it is possible to prefer casting conditions, without negative enlarging of the grain size.
Deposition and analysis of AlCrN coatings
Drásalová, Kateřina ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
The topic of this thesis is the deposition process and methods of quality assessment of AlCrN surface coatings produced by methods of (i) magnetron sputtering, (ii) magnetron sputtering with arc enhanced glow discharge, and (iii) high power magnetron sputtering with the movable magnetic field. The main focus is placed on categorizing properties of the produced coatings based on the production method (which vary in the ionization level). Qualities of the surface coatings are assessed by adhesion and cohesion parameters testing of coarseness using AFM (Atomic Force Microscopy), depth measuring using a calotest, measuring internal tension using the Bent Strip Method and Instrumented indentation test for hardness.
The analysis of couses of the damage of stroller welded construction
Štarhová, Martina ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
This bachelor thesis deals with analysis of causes of damage of aluminum welded structures of baby carriages. The theoretical part contains a summary of information concerning the most frequently used aluminum alloys and their heat treatment. Furthemore, it deals with possibilities of welding and testing of welded joints, corrosion resistance of aluminum alloys. Basic information on the most frequently used surface treatment, anodic oxidation, is also mentioned. The experimental part of the work deals with a complex material analysis of three frames of baby carriages. This analysis is focused on mapping the occurrence of the most common defects and determining their contribution to damage or destruction of the baby carriage frame.
Nondestructive testing in current industrial practice
Jakubcová, Eliška ; Klakurková, Lenka (referee) ; Juliš, Martin (advisor)
The bachelor thesis is focused on personnel certification of non-destructive testing according to valid standards. The theoretical part compares the Czech certification system for non-destructive testing with systems in other countries and evaluates their differences. Problems that occur during certification according to ČSN EN ISO 9712 are also discussed. In the practical part of the thesis the evaluation of the test sample is documented by means of radiographic test, magnetic particle test and leak test. At the end of the thesis the results are evaluated and discussed and also described in the form of measuring protocols.
Analysis of degradation processes of the shock absorber rod
Sýkorová, Jitka ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
The bachelor thesis deals with the analysis of degradation processes of the rods of the synchronizer generator. The theoretical part deals with the description of the generator, the analysis of the material, the properties of the brass for the production of the absorber rod and the possible parameters influencing its degradation. The experimental part of the thesis analyzes damaged bars of the shock absorber using destructive and non-destructive techniques, suggests non-destructive testing in-field and determines the dependence of electrical properties on the structure.
Evaluation of bearing steel´s microstructural parameters with regards to their mechanical properties and lifetime
Hroš, Michal ; Juliš, Martin (referee) ; Klakurková, Lenka (advisor)
The aim of this bachelor thesis is evaluating the impact of microstructural parameters of bearing materials with an emphasis on evaluation carbidic phase with using protocol SEP 1520. Literary section analyzes the specific groups of materials for the manufacture of rolling bearings, specifically focusing on steel, where is discussed their performance, production, heat treatment, micropurity, microstructure and macroscopic requirements. Work on structure of bearing steel as well as the experimental part of the thesis is focused on a more detailed description carbidic phase materials and the systematic evaluation with regards to type of initial a semifinished product for the manufacture of bearings, the heat treatment, the resulting mechanical properties and especially durability.
Methods to increase the visibility of the original austenite grain boundaries in steels
Gamanov, Štěpán ; Klakurková, Lenka (referee) ; Juliš, Martin (advisor)
This thesis deals with methods of revealing prior austenite grains in steels. The objective was to describe and demonstrate these basic methods on samples. The theoretical part deals with the importance of austenite grain and its size, with description of base methods of revealing austenite grains, and with methods of determination of grain size. The practical part consists of pictures and commentary of samples wich were made with some of the base methods described in the theoretical part. Conclusion consists of comparison of our and external results and also expanding commentary on individual methods.
Applications of aluminium alloys
Ponka, Ondřej ; Juliš, Martin (referee) ; Němec, Karel (advisor)
This bachelor thesis deals with basic overview of aluminum and its alloys. It deals with properties of primary aluminum, its production and the benefits resulting from the processing of secondary aluminum. The thesis also discusses aluminum alloys as well. It describes the basic alloying elements, their distribution and their specific properties. It also mentions the effects of the heat and surface treatments on the properties of the alloys. Finally, the thesis deals with applicability of aluminum and its alloys in various industries. Briefly describes the issue of specific applications and provides advantages and disadvantages arising from their use.
Composite materials used in the manufacture of cars
Rendek, Marek ; Juliš, Martin (referee) ; Němec, Karel (advisor)
Bachelor’s thesis deals with various types of composites used in the spheres of automotive industry. In the first section, it’s focused on the introduction to issues of composite materials, methods of production, their advantages and disadvantages. The second part of thesis focuses on specific applications in the automotive industry. In the final part there is a future evaluation and an overall view of the composite materials in the automotive field.
Monitoring of the content of selected elements in the batch for blast furnace and their influence on optimizing the production of pig iron
Filipová, Iveta ; Němec, Karel (referee) ; Juliš, Martin (advisor)
This Bachelors thesis deals with monitoring the content of elements in batch for blast furnace and their influence on optimizing the production of pig iron. Contents in output materials were also recorded. For a given time period were monitored especially the quantity of sulfur, phosphorus, manganese, zinc, iron and alkali (K2O, Na2O) in cooperation with TŘINECKÉ ŽELEZÁRNY, a.s. and their material balances were subsequently forged. Processed regression analysis show the influence of batch on the content of individual elements in the output materials.

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