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Adhesion of plasma polymer films deposited from tetravinylsilane monomer
Plichta, Tomáš ; Salyk, Ota (referee) ; Čech, Vladimír (advisor)
This bachelor thesis deals with the characterization of thin films of plasma polymers prepared from monomers of tetravinylsilane (TVS) and deposited on planar silicon substrates. Plasma enhanced chemical vapor deposition (PE CVD) was used as a method of thin films preparation. Three power series were prepared from pure TVS and two mixtures TVS with argon and oxygen. The main characterization methods were scratch tests and atomic force microscopy (AFM) is used to assess the adhesion degree of the layers and topography of scratches. To assess the characteristics and context the layer thickness was measured by spectroscopic ellipsometry (ELL) and elastic modulus using nanoindentation. The collected data were used to assess the reproducibility of the results with the regard to the purity of substrates and adhesion layers, depending on the deposition conditions and layers aging.
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Design of a device for scratch tests
Brandejs, Petr ; Otáhal, Alexandr (referee) ; Skácel, Josef (advisor)
This thesis deals with designing a scratch tester. Theoretical part introduces scratch testing, with focus mainly on testing adhesion and layer toughness in microelectronics. Second chapter deals with research of commercially available scratch tester parameters. Based on the findings, construction, and electronics of a device capable of performing scratch tests with required parameters were designed. In the end, a few scratch tests were performed to show capabilities of the device.
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Preparation and characterization of modern wound covers
Balášová, Patricie ; Pernicová, Iva (referee) ; Skoumalová, Petra (advisor)
This diploma thesis is focused on the study of bioactive wound dressings. During the thesis, hydrogel, lyophilized and nanofiber wound dressings were prepared. Hydrogel and lyophilized wound dressings were prepared on basis of two polysaccharides – alginate and chitosan. Nanofiber wound dressings were prepared by spinning polyhydroxybutyrate. All prepared wound dressings were enriched with bioactive substances, which represented analgesics (ibuprofen), antibiotics (ampicillin) and enzymes (collagenase). Into hydrogel and lyophilized wound dressings were all the mentioned active substances incorporated, whereas nanofiber wound dressings were only with ibuprofen and ampicillin prepared. The theoretical part deals with the anatomy and function of human skin. There was explained the process of wound healing and also there were introduced available modern wound dressings. The next chapter of the theoretical part deals with materials for preparing wound dressings (alginate, chitosan, polyhydroxybutyrate) and with active substances, which were used during the experimental part of this thesis. In the theoretical part, the methods of preparation of nanofiber wound dressings and also the methods of cytotoxicity testing used in this work were presented. The first part of the experimental part of this thesis was focused on preparing already mentioned wound dressings. Then, their morphological changes over time and also the gradual release of incorporated active substances into the model environment were monitored. The gradual release of ampicillin was monitored not only spectrophotometrically, but also by ultra-high-performance chromatography. In wound dressings, in which collagenase was incorporated, was also the final proteolytic activity of this enzyme monitored. The effect of the active substances was observed on three selected microorganisms: Escherichia coli, Staphylococcus epidermidis and Candida glabrata. The cytotoxic effect of the active substances on the human keratinocyte cell line was monitored by MTT test and LDH test. A test for monitoring the rate of wound healing – a scratch test – was also performed.
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Why monitor acoustic emissions during nanomechanical tests?
Čtvrtlík, Radim ; Václavek, L. ; Tomáštík, J.
Acoustic Emissions (AE) monitoring has been proved as an effective non-destructive technique at the macro scale. Nevertheless, it may also be employed at nano/micro scale during nanomechanical and nanotribological testing. Local mechanical properties of surfaces or micro object are routinely explored using nanoindentation, scratch test or dynamic impact tests that are evaluated based on analysis of depth-load-time records or microscopic observation of residual indents, scratch grooves or impact craters, respectively. Although these approaches have been proven to be sufficient in most cases for a variety of materials, there are many situations where they do not provide sufficient information for a complex understanding of the deformation response. On the other hand, analysis of AE signals generated during these tests may provide valuable complementary information and provide some insight into the dynamics of phenomena like cracking, phase transitions, plastic instabilities, etc.\n
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Benefits of use of acoustic emission in scratch testing
Václavek, L. ; Tomáštík, Jan ; Chmelíčková, H. ; Čtvrtlík, R.
Scratch test is regularly used for assessment of cohesive and adhesive strength of thin films and coatings. By default, its evaluation is based on analysis of depth-load-time record and microscopic observation of residual scratch groove. The visual analysis of the residual groove provides the most detailed description of the final damage of the surface (crack patterns, extent of plastic deformation, delamination, etc.), but it may be a time demanding approach. Although the continuous recording of indenter penetration depth and applied load offers instantaneous information about the performance of the tested material, it may not provide sufficient description of the sample’s deformation behaviour. Therefore, other complementary techniques for description of the deformation response to scratch loading are desirable.
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Comparison of properties and behaviour of selected systems of thin film - Substrate with TiSiN, AlCrN and AlTiN on samples and selected cutting tools
Mertová, Andrea ; Štěpánek, Ivo ; Šimečková, Lucie ; Dudáčková, Simona ; Ulrychová, Monika
The paper is devoted by evaluation of comparison of selected systems of thin film - basic material, which are optimized in the range of solution of the project with goal application of thin films on selected real cutting tools. There are evaluated thin films prepared by low voltage reactive arc evaporation in vacuum with different composition of ternary nitride. The evaluation of properties and behaviour is oriented on systems with thin films TiSiN, AlCrN and AlTiN. The surfaces of these systems of thin film - basic material are evaluated from point of view of verification homogeneity of thin films through of area of samples and through of geometry of selected real tools too. The distribution of thickness is evaluated by x-ray fluorescence analysis on samples and real selected places of geometry of tools too. The other comparison is realised from point of view of differences of mechanical properties and behaviour by using of indentation methods namely of nanoindentation and scratch indentation for evaluation of differences in hardness and adhesive cohesive behaviour of systems thin films - basic material.
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Hardness and scratch resistance measurement using universal tribometer
Urbášek, Jan ; Galas, Radovan (referee) ; Omasta, Milan (advisor)
This bachelor thesis deals with a hardness and scratch resistance measurement. These tests are normally performed using special devices. From a design point of view, these tests can also be performed using universal tribometers, but they do not have implemented tools for subsequent measurement evaluation. The main goal of the work was to develop a methodical procedure including evaluation of these tests. The methodological procedures were subsequently verified by several experiments.
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Surface topography and mechanical properties of thin films on tetravinylsilane basis
Plichta, Tomáš ; Klapetek, Petr (referee) ; Čech, Vladimír (advisor)
Proposed diploma thesis is focused on preparation and characterization of the plasma polymer thin films based on tetravinylsilane monomer (TVS). Plasma enhanced chemical vapour deposition (PECVD) method involving pulse and continual plasma discharge modes were used for thin film deposition on silicon wafer pieces. Reactive plasma composition was containing pure TVS or mixtures of TVS and argon or oxygen gas. Atomic force microscopy was used for surface topography and roughness characterization. Cyclic nanoindentation was involved to measurements to determine the Young’s modulus and hardness of prepared films and scratch test was performed to evaluate the degree of adhesion. Special attention was drawn to the characterization of films with a Young’s modulus below 10 GPa. Tip geometry of indenter influence on scratch test was also commented. Surface and mechanical properties of thin films in relation to the deposition conditions were correlated to the obtained results and final analysis of deposition conditions influence is proposed.
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Influence of Zinc Coating Morphology on Limit Conditions Formability of Thin Sheet Metal
Císařová, Michaela ; Suchánek, Jan (referee) ; Rusz, Stanislav (referee) ; Dvořák, Milan (advisor)
The doctor thesis deals about the influence of zinc coating morphology on limit conditions formability of a thin sheet metal. In the introduction of the thesis is discusesed about current problems searching the most suitable morphology of the steel sheet metals, a method of appliing to the zinc sheet metal. The hot dip zinc coating is discussed in next chapter, the topical knowledges about the influence of the individual factors have some effect to coat calibre and quality. In literary researchs are discussed the concrete technological tests of zinc coating to harder sheet metal forming, the theory of the bend and the basic theory of pressing sheet metal. In following chapter is devoted interpretation selected technological tests, according to that is described behaviour, characteristics, influence of zinc coating formability of basic material and his morphology.
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Surface and Mechanical Properties of Thin Films
Pálesch, Erik ; Klapetek, Petr (referee) ; Skuhurov,, Andrey (referee) ; Čech, Vladimír (advisor)
The doctoral thesis deals with the study of morphology and mechanical properties of thin plasma polymer films based on tetravinylsilane monomer and its mixtures with oxygen and argon. Thin films were prepared by plasma-enhanced chemical vapour deposition on silicon and glass substrates. Atomic force microscopy was used for characterization of thin film surface and for depiction of composite interphase with functional interlayer. Mechanical properties of thin films, namely Young’s modulus and hardness, were studied by cyclic nanoindentation technique. Nanoindentation device was also used to carry out scratch test, which was helpful to describe adhesion of films to substrate. In this thesis the influence of deposition conditions on surface and mechanical properties of thin films prepared in continual and pulse wave on planar substrates is discussed. Also, the suitability of few atomic force microscopy techniques for depiction of composite interphase was reviewed.
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