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Influence of a size of a cutting edge rounding of the insert during turning
Tichá, Dana ; Sedlák, Josef (referee) ; Dvořák, Jaromír (advisor)
The work is focused on the durability test of replaceable cutting inserts, which are coated with a newly developed coating. In the work are tested two types of replaceable inserts with different shapers, while three different edge roundings are produced for each shaper. The test is performed on three different materials. During testing, the cutting depth doesn’t change, only the feed changes, where tests are performed on each material at two different feeds. A different cutting speed was chosen for each material and feed, which resulted in a durability of the replaceable insert cca 15–20 minutes. The goal of the work is to find out what is the most suitable rounding of the blade on replaceable cutting inserts, when applying a newly developed coating.
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Effect of cutting inserts surface treatment on turning durability of stainless steel
Filip, Jiří ; Vítek, Jiří (referee) ; Sedlák, Josef (advisor)
The diploma thesis deals with the testing of coated carbide inserts with different types of surface treatments. The testing was conducted using longitudinal turning technology under constant cutting conditions, and the workpiece material used was austenitic corrosion-resistant steel. The aim was to analyze the wear progress of the cutting edges after predetermined time intervals and to determine the resulting durability of the tested inserts. During the testing, the cutting edges of the tools broke off and the required durability was not achieved. After a thorough examination of the workpiece material, a significant amount of unevenly distributed inclusions was found in the steel structure, which proved to be the main cause of the insert breakage. Therefore, it was decided to perform a replacement test using material from a new supplier. Material analysis of the newly delivered steel showed a significantly better purity of the structure, which was positively reflected in the results of the second test, in which there was no brittle fracture of the edge in any case and the tested samples reached the required durability. The best results were obtained with samples treated on flanks using a new surface treatment method developed by Dormer Pramet s.r.o. After completing the tests, an adhesion test of the coating to the tool substrate was performed using the Rockwell method. Based on microscopic images that revealed partial delamination of the coating, it was evaluated that the quality of the deposited layer was not quite optimal. In a technical and economical evaluation were determined the potentially saved costs when using the experimental cutting insert compared to the reference plate A.
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Possibilities of using recycled aggregates for the production of structural concrete
Hrachovcová, Ludmila ; Brožovský, Jiří (referee) ; Hubáček, Adam (advisor)
The bachelor thesis deals with the study of recycled aggregates and concretes made from them. Nowadays, more and more emphasis is being placed on recycling waste and especially construction and demolition waste. Therefore, we are looking for ways to use recycled aggregates in concrete composites despite heterogeneous parametres of concrete and brick recyclates. The paper summarizes the existing knowledge about recycled aggregates, especially about brick and concrete recyclates, their parameters and possibilities of their use. Furthermore, the thesis deals with brick and concrete recyclate concretes, their parameters and behaviour and their subsequent use in practice.
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Study of properties of concrete and brick recycled aggregate and its use for structures
Lípová, Sabina ; Voves, Jiří (referee) ; Hubáček, Adam (advisor)
This bachelor thesis studies the existing knowledge on recycled aggregates, particularly brick and concrete recyclates. It describes the properties and parameters of different types of recyclates and their possible applications in structures such as concrete, base courses, non-structural parts of pavements, etc. It also deals with the development of a methodology for selecting and testing recycled aggregates with the possibility of using them to meet the requirements of aggregate standards. Geometric, physical and mechanical parameters of aggregates that could affect the properties of the materials for structures made from them have been studied
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Methods of assessing the durability of concrete against frost and chemical deicing salts in the Czech Republic and in Europe
Žíla, František ; Novosad,, Petr (referee) ; Hubáček, Adam (advisor)
The bachelor thesis deals with the methods of assessing the durability of concretes against frost and chemical deicing salts used in the Czech Republic and Europe. The theoretical part of the thesis describes the basic properties of concrete, the classes of environmental influence, the theory of concrete failure by cyclic freezing and thawing, methods for assessing the durability of concrete against freezing and methods for assessing the durability against water and chemical deicing salts, as well as properties affecting the repeatability and reproducibility of tests. The practical part focuses on testing the resistance of concrete to the action of freezing and chemical thawing agents using the methods according to the standards ČSN 73 1322 and ČSN 73 1326 and also on the influence of concrete surface treatment on the process and result of these tests.
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Hodnocení kvality bezlepkových potravin se zaměřením na pečivo
OSINKOVÁ, Radka
This dissertation addresses the issue of shelf life and low nutritional value of gluten-free bread. Its aim was to determine the effect of certain additives on increase of the nutritional value and on extension of the shelf life of gluten-free bread. The first section of the thesis is devoted to the theoretical part, offering a general overview of properties of gluten, diseases associated with disorders of gluten digestion and the issue of gluten-free bread. It concludes with a description of a method of sensory analysis and possibility of compiling a questionnaire. The second section of the thesis is focused on the practical part which is developed on the basis of performing a baking experiment using enriching additives - hemp flour and mash. The bread samples are subjected to texture analysis by means of a texture analyser. The experimental part includes a questionnaire survey. The achieved results are processed and graphically represented. On the grounds of the acquired results, it is possible to label the chosen additives - hemp flour and mash as enriching ingredients positively affecting the nutritional value and shelf life of gluten-free bread. The results of the questionnaire survey show that the respondents are interested in the quality of the bakery products consumed; this is especially true for coeliac sufferers and people with other disorders of gluten digestion.
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SPECIAL POLYMER COATINGS AND SCREEDS MATERIALS WITH USE OF SECONDARY RAW MATERIALS
Žlebek, Tomáš ; Seidlová, Michaela (referee) ; Bydžovský, Jiří (referee) ; Ďurica, Tibor (referee) ; Drochytka, Rostislav (advisor)
The work deals with the development of new polymeric coatings and screeds – epoxy, polyurethane and vinyl ester materials with the use of hazardous waste in the form of fillers. The areas that are destined for their landfill are constantly expanding and the costs of disposing of this waste are high. Their use eliminates negative impacts on the environment, but also leads to significant financial savings. The aim of this PhD thesis was to find a suitable way to treat selected hazardous waste and experimentally verify the possibilities of using the fillers pre-treated by optimal way in polymer coatings and screeds. The coatings and screeds are intended primarily for concrete substrates but the possibility of use on metal substrates, asphalt and cement-bonded particle boards was also been verified. These materials serve as a secondary protection of structures against the adverse effects of weather conditions. Secondary raw materials were used as fillers, which were fluidized bed combustion fly ash contaminated due to flue gas denitrification and specially pre-treated hazardous waste (solidification products). The aim was to proceed progressive use of the secondary raw materials as much as possible in order to reduce landfilling in the maximum possible way. It was necessary to treat hazardous waste in such a way that the most effective solidification would be achieved. The behavior of the solidifaction products in the polymer matrix, the distribution of particles in the structure and the disruption of coatings and screeds due to chemical stress were also investigated.
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Study of concrete properties in extreme climatic conditions
Stará, Tereza ; Novosad,, Petr (referee) ; Hubáček, Adam (advisor)
The bachelor thesis deals with the study of concretes that are exposed to extreme climatic conditions during their service life. Many concrete structures around the world are exposed to various climatic conditions during their service life, such as high temperatures or, conversely, low temperatures. These conditions affect the properties of concrete both in its fresh and hardened state and have an impact on its durability. This thesis summarises the existing knowledge of the behaviour of concrete in these conditions, and describes suitable input materials that can be used for these environments. Furthermore, the thesis describes the possibilities of improving the durability and resistance of concrete to these climatic conditions. In the experimental part, selected durability parameters of concrete are monitored during its exposure to climatic stresses.
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Study of FRP for concrete reinforcement
Blahová, Aneta ; Prokeš,, Jan (referee) ; Bodnárová, Lenka (advisor)
The diploma thesis aims to analyze bent FRP reinforcements. It describes the method of production of bent FRP reinforcement, examples of application of FRR reinforcement in structures and mentions aggressive influences influencing the durability of FRP reinforcement. Furthermore, an experiment is proposed to monitor changes in straight and bent FRP reinforcement stored in an aqueous environment at 20 °C and an alkaline environment at 20 °C and 40 °C. The output of the diploma thesis is the evaluation of changes in mechanical properties and durability. The condition of the FRP reinforcement is documented using optical and electron mocroscopy.
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Development of new technologies of translucent architectural concrete
Adámková, Aneta ; Novosad,, Petr (referee) ; Hela, Rudolf (advisor)
The diploma thesis follows up on the bachelor thesis and deals with the issue of light-transmitting concrete LTC. The aim of thesis determines the transparency and its decrease due to durability. The terotical part deals with extension of LTC issues and follows up reserch from bachelor thesis. The teory is also focused on the issue of glass optical fibers. The experimental part deals with the influence of selected durability test on transparency of LTC. Transparency is determined by mesuring devise called black box. In the conclusion is summarized influences witch affects transparency and evaluation of whether the selected fibers are suitable for outdoor use.
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