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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.
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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.
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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.
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Structure and Properties of Sintered Tungsten Carbides
Novotná, Hana ; Klakurková, Lenka (referee) ; Čelko, Ladislav (advisor)
This bachelor thesis deals with the structure and properties of sintered tungsten carbides. The literature review section concerns the development of sintered carbides, their composi-tion and structure, different types of carbides, the steps of the production of sintered car-bides, sintering technology and alternative materials for cutting tools. The experimental section deals with composition of WC-Co and is ascertained by the dependency coercivity on WC grain size and also on cobalt content. This work describes the measurement of WC grain size and measurement of the coercivity, one of the fundamental properties of sintered carbides.
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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.
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Optimisation of heat treatment of aluminium alloy AlSi7Mg0,6
Julišová, Martina ; Klakurková, Lenka (referee) ; Juliš, Martin (advisor)
The presented diploma thesis deals with various types of quenching and their respective effects on mechanical and structural properties of AlSi7Mg0.6 alloy castings. Cast with precision casting technology into a self-supporting ceramic shell made by plaster investment technology, flat test bars cast by Alucast were used as experimental samples. Sample castings were used in both cast state and after T6 heat treatment. Air-flow and air-water combination with varying water passage (spraying) were used as the quenching media in the quenching process of the castings. In order to evaluate the effect of five different quenching processes on the structure and mechanical properties of the castings, the method of light microscopy, Brinell hardness test and static traction test were used. Evaluation and porosity and SDAS quantifications were carried out by means of image analysis. Experiments did not prove right the hypothesis holding that low SDAS values inevitably mean higher mechanical properties of the castings. On the other hand, distinct is the negative influence of heterogeneous structure and porosity. Despite the fact that the heat treatment was successful in reducing the influence of structural inhomogeneities, it cannot be concluded that spray quenching has an utterly positive bearing on the mechanical and structural properties of the castings.
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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.
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Analysis of the structure Hadfield steel depending on the load deformation
Darida, Jiří ; Julišová, Martina (referee) ; Klakurková, Lenka (advisor)
This bachelor´s thesis deals with the analysis of the structure Hadfield steel depending on the load deformation. The first part of the thesis determines summary of basic mechanical and physical properties of Hadfield steel, its chemical composition, the influence of alloying elements on the resulting microstructure, manufacturing, heat treatment, hardening mechanisms and its use in technical applications. Attention is also paid to the various types of work hardening among which include explosive strengthening. The experimental part of the thesis is focused on the analysis of samples Hadfield steel, which were stressed by different loading conditions. Analysis of these samples consists of observations of structural changes and measurement of work hardening using microhardness in surface and sub-surface region of the sample. The final part presents the view into the future and overall evaluation of results.
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The role of material sciences in solving the problems technical accidents
Tonkovič, Miroslav ; Řičánková, Veronika (referee) ; Klakurková, Lenka (advisor)
Material sciences plays an irreplaceable role in explanation of various technical accidents. The proposed work focuses on examples of sever chosen technical accidents in which the knowledge of materials science was crucial in use and help to solve them. Description of an incident is stated to particular cases as well as results of these investigations, taking in mind the given topis of proposed work. The accidents are always described with necessary theoretical basis connected to each particular issue. Its knowledge was undoubtedly essential in solving the accident. The end of the work is a summary of the most frequent causes of technical accidents.
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