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Trends in the design and creation of new materials
Kašičková, Václava ; Gaff, Milan (advisor) ; Babiak, Marian (referee)
Thesis investigates the flexural properties of modified laminated wood. Thesis examined two wood species - beech and aspen. The aim was to describe effect of wood species, material thickness, densification, adhesives and loaded cyclic stress on selection of mechanical properties.
Wood species and thickness of material were determined as factors with very significant impact. They affected modulus of elasticity, limit of proportionality and bending strength. All these characteristics achieved higher values while testing beech lamellas. Degree of densification does not appear as a very significant factor. Comparing modulus of elasticity in this thesis and data given in the literature it is possible to say that densified lamellas used in this research reached higher values.
This thesis also investigates tensile-shear strength and bendability.
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Brickmaking grogs and their thermo-dilatometric determination
Hladík, Václav ; Skotal, Zbyněk (referee) ; Sokolář, Radomír (advisor)
Main focus of the bachelor´s thesis is use of rock waste fraction as an alternative raw material to traditional quartz sand. Effect of this substitution on ceramic produts properties is outlined. Key properties are water absorption, flexural strength and compressive strength. The practical part traces the potential of alternative grogs. Their behavior is monitored by DKTA analysis, water absorption tests and strength tests. Thesis includes author´s suggestion of an optimal grog based on publications and results of the practical part.
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Hybrid dental composites combining short fibers and particulate fillers
Klieštiková, Nikola ; Přikryl, Radek (referee) ; Bystřický, Zdeněk (advisor)
This work deals with the hybrid composite material combining particulate filler with short fibers for dental applications. The barium micro-filler and the short glass fibers were treated with -methacryloxypropyltrimethoxysilane in cyclohexane using n-propylamine. The barium micro-filler and the short glass fibers were mixed with the matrix based on a dimethacrylate resin. The effects of the addition of short glass fibers on mechanical properties were studied. Surface treatment of the filler was characterized by thermogravimetric analysis (TGA) and diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). Fracture surfaces and the adhesion to the matrix was observed by scanning electron microscope (SEM). The modulus of elasticity and strenght was determined by three point bending flexural test. Critical values of the stress intensity factor annd energy release rate were determined using the three point bending flexural test of notched specimens. The particulate filler increased the flexural modulus of elasticity and fragility. The addition of short fibers had little effect on flexural modulus of elasticity, but increased the flexural strength and fracture toughness of the specimen.
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The influence of coatings on fracture behaviour of ledeburitic steel
Šafář, Martin ; Jurči,, Peter (referee) ; Hadraba, Hynek (advisor)
This work deals with tool steel Vanadis 6. It describes the preparation of samples for the three-point bending test, with which it examines the influence of surface roughness, the effect of nitriding, coating and duplex coatings on fracture behaviour of the steel. First, it examines bending strength and the total energy required to work of fracture. The work also includes mapping and measurement of surface roughness on different layers. This measurement is performed on a confocal microscope.
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Results of Anorthite Creation in ceramic Body
Beránková, Karla ; Šveda,, Mikuláš (referee) ; Sokolář, Radomír (advisor)
Anorthite is crystalline phase in the ceramic body. Is acquired on burning a mixture of calcium ceramic raw material. This work deals with the influence on the resulting properties of anorthite ceramic body, especially flexural strength, porosity, shrinkage, thermal expansion coefficient. And the influence of different CaO sources on the properties. As a source of CaO was used calcium carbonate, calcium hydroxide and fluid fly ash.
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Local tests of mechanical properties of materials
Wasserbauer, Jaromír ; Šoukal, František (referee) ; Zmrzlý, Martin (advisor)
This thesis deals with measurement of hardness and microhardness in relation to structure of homogeneous and heterogeneous materials. In the introduction basic theoretical background is commented, i.e. definitions, terminology, principles of measuring techniques for estimation of hardness, microhardness, tensile strength, compressive strength and bending strength. Follows a brief review of present research results focused on use of described principles in materials engineering. Then the experimental equipment and sample preparation is described. The crucial part of the thesis is summary of achieved results of original measurement and discussion of their relations to each other. Finally, the groundbreaking estimation is described, showing the correlation of chemical composition gradient and mechanical properties in interfacial zone of geopolymeric material.
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Polymer-cement composites of increased refractoriness
Žůrová, Marcela ; Mončeková, Miroslava (referee) ; Šoukal, František (advisor)
The subject of the barchelor thesis is the preparation of high-strength polymer – cement composites based on the calcium aluminate cement and polyvinylalcohol. For macrodefect–free (MDF) composites are characterized by low porosity and the absence of microcracks. The main problem of the MDF composites is decreased resistance to water or moisture, with a decrease in strength. These compounds are interesting with its mechanical properties, which are greater than the strength of common materials (wood, glass, PMMA,…). Represent perspective type of material that could be used for construction purposes. The thermal degradation of the polymer, however, there are changes in the structure of the composite and to the deterioration of mechanical properties. This thesis is focused on characterization of the effect of temperature change on the structure, material composition and mechanical properties. The MDF composites were prepared based on calcium aluminate cement, which was gradually replaced by refractory additives. During the work was carried out tests of bending strength at various temperatures. Changes in the composition and structure were characterized by TG – DTA, XRD and SEM analysis.
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Modern Inorganic Building Materials Free of Portland Cement
Sadílek, Jakub ; Opravil, Tomáš (referee) ; Zmrzlý, Martin (advisor)
This bachelor’s thesis is focused on properties of modern construction inorganic ma-terials – geopolymeric concretes. In introductional part of work it is described basic theoretical background, as properties of binders, principles of setting and hardening. For preparation of geopolymer matrix was used secondary or waste materials of energetic and metallurgical industry – fly ashes and slags. In laboratory were prepared four com-positions of geopolymeric concretes combined from geopolymeric matrix with constant compostition and variable composition of aggregates. As aggregates these materials were used: three fractions of quartz sand, steel furnace slag and in one composition also crystals of mineral wollastonit. It was discovered that the use of steel furnace slag as aggregate in geopolymeric concrete has positive influence mainly to compressive strength, but the addition of wollastonite mineral do not evocate expectable increase of mechanical properties of samples.
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Flexular Strength and Hydrolytic Stability of FRC/PFC Dental Bi-Material
Dombková, Julie ; Trautmann, Radoslav (referee) ; Poláček, Petr (advisor)
This thesis deals with the flexural strength of FRC/PFC dental bi-materials and their resistance degree to hydrolysis degradation. The block-shaped samples were exposed to the flexure in three points. The strength and modulus of elasticity were measured by multi-purpose test device called Zwick Z0100. Electron scanning microscope was used for observation of disrupted localities. From the outcomes gained result that the mechanical characteristics are affected by dipping of fibre composite, spatial organization of the support, water absorption of materials used and the matrix and the support adhesion.
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