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Study of the microstructure of deposited Ni-P coatings with different phosphorus contents
Najser, Tomáš ; Kosár, Petr (referee) ; Wasserbauer, Jaromír (advisor)
The aim of this bachelor thesis was the preparation and characterization of Ni-P coatings with different phosphorus contents on the substrate of AZ91 magnesium alloy. The theoretical part deals with magnesium alloys and specifies the utilized substrate AZ91. It also focuses on Ni-P coatings, their microstructure and their properties. However, there are also described factors affecting the rate of deposition and the resulting behavior of these coatings. Last but not least, the theoretical part summarizes the basic principles of laboratory methods used in the experimental part for observation and characterization of samples. Conclusion of the theoretical part consists of several background researches where the authors deal with similar problems and factors influencing the resulting behavior of Ni-P coatings. The experimental part is focused on the deposition of each Ni-P coatings on the AZ91 alloy and their characterization. The study of deposited Ni-P layers was focused on the determination of their microstructural texture by XRD method, mechanical properties and elemental composition depending on phosphorus content.
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Coatings on aluminum alloys
Slouková, Karolína ; Wasserbauer, Jaromír (referee) ; Zmrzlý, Martin (advisor)
Aim of this bachelor thesis is a summary of results of research of conversion coatings on aluminum alloys and coatings based on examination of cerium using potentiodynamic measurements. In the theoretical section there are described basic properties of aluminum and its alloys. Then corrosion of aluminum and its alloys is discussed and an overview of the most common types of corrosion affecting these alloys is presented. A brief overview of aluminum alloys notation follows. Next section is devoted to concepts that are already associated with potentiodynamic measurements. There are described electrochemical cells, effects of current density, polarization and passivation. The following summary of research articles deal with current research of aluminum alloys and coatings formed on them. Discussed are especially research results on coatings based on cerium. The experimental part focuses on the effect of hydrogen peroxide concentration on coatings based on cerium, and the influence of the surface roughness of the samples on the adhesion of these coatings. Analyses were performed using electro microscopy and potentiodynamic measurements.
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Heat hardening of Ni-P based coatings prepared on wrought magnesium alloys
Kotland, Vojtěch ; Březina, Matěj (referee) ; Wasserbauer, Jaromír (advisor)
This bachelor’s thesis is focused to hardening of nickel-phosphorus coatings on magnesium alloys. In the theoretical part are listed current knowledge about magnesium alloys and electroless deposition of Ni-P coatings for which is also stated mechanism and function of components contained in the bath. Theoretical part is ended by review aimed to the research in areas of chemical coating. Experimental part describes individual steps of pretreatment on magnesium alloy AZ31 and then planting of Ni-P coating on thus prepared alloy. In the next part is stated range of used hardening temperatures and mechanical repercussion to that. Composition and morphology of deposited coating and magnesium alloy were studied using scanning electron microscopy.
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Galvanic plating of magnesium alloy with Ni-P bond coat
Zahálka, Martin ; Kosár, Petr (referee) ; Wasserbauer, Jaromír (advisor)
Cílem této diplomové práce jse najít nejnižší možnou tloušťku nikl-fosforového povlaku, který může být galvanicky pokoven mědí bez defektů na horčíkové slitině, nikl-fosforového nebo měděného povlaku. V teoretické části jsou shrnuty poznatky o hořčíkových slitinách a jejich korozi. Navíc se teoreticá část zaměřuje na popis procesu bezproudého niklování a elektrochemického pokovování mědí a jejich porovnání. Na konci teoretické části je shrnut současný výzkum o elektrochemickém pokovování hořčíkových slitin. V experimentální části byl popsán proces přípravy povlaků Ni-P a Cu na horčíkové slitině AZ91. Na jedné vrstvě a dvojité vrstvě Ni-P povlaku byla provedena elektrodepozice mědi. Navíc byl diskutován vliv předůpravy před samotnou elektrodepozicí mědi. Za účelem zjištění korozních vlastností vzorků byl vykonán potenciodynamický test. Následně byly připraveny metalografické výbrusy jednotlivých vzorků a pomocí světelného a rastrovacího elektronového mikroskopu byla provedena charakterizace. Na konec bylo zjištěno prvkové složení jednotlivých povlaků pomocí EDX analýzy.
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Fluoride conversion coatings on magnesium materials
Staněk, Jan ; Wasserbauer, Jaromír (referee) ; Březina, Matěj (advisor)
This bachelor thesis deals with the topic of corrosion protection of magnesium materials by conversion coatings. The aim is to characterize and compare properties of fluoride conversion coatings formed on wrought magnesium sample and magnesium sample prepared by powder metallurgy. Basic knowledge of pure magnesium, magnesium alloys, powder metallurgy, corrosion, and protection against it are described in the theoretical part. Recent results of corrosion protection by fluoride conversion coatings on magnesium materials are summarised in the recherché part. The experimental part is focused on preparation of fluoride conversion coatings on each type of sample by immersion in Na[BF4] molten salt and by dipping in hydrofluoric acid. Surface morphology and composition of coatings were characterized by EDS analysis and corrosion protection was evaluated by potentiodynamic measurements.
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Characterization of heat treated Ni-P coatings with different phosphorus contents.
Žilinský, Martin ; Kosár, Petr (referee) ; Wasserbauer, Jaromír (advisor)
The aim of this work was the characterization of heat–treated, electroless nickel–phosphorus coatings of different phosphorus content. In the theoretical part of this work, the substrate for the nickel–phosphorus coating, namely the AZ91 alloy, is discussed. Further, the deposition of the nickel–phosphorus coating on the substrate, the components of the nickel baths and their influence on the phosphorus content of the deposited coating nickel–phosphorus, is analyzed. Attention is also paid to the structure of this coating depending on the phosphorus content. Heat–treatment and its influence on the hardness of this coating is also discussed. At the end of the theoretical part, the current research in the field of nickel–phosphorus coatings, is described. The experimental part of this work describes the pre–treatment of samples and their characterization. Using a scanning electron microscope, the phosphorus content of the heat–treated coatings was determined. Furthermore, the microhardness of heat–treated nickel–phosphorus coatings was measured. X–ray diffraction analysis determined microstructure and crystallite size of the phases present in coatings after heat–treatment.
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Characterization of electrochemical properties of magnesium batteries in electrolyte modification
Honč, Jiří ; Doskočil, Leoš (referee) ; Wasserbauer, Jaromír (advisor)
This thesis deals with novel electrolytes for magnesium batteries. Prepared electrolytes were composed of affordable solvents and chemicals, which can be handled at normal laboratory conditions. Specifically, solutions of tetrahydrofurane and dimethylsulfoxide with magnesium chloride, aluminium chloride, nitrilotriacetic acid and disodium ethylenediaminetetraacetic acid, were prepared. To determine electrolyte ability of magnesium stripping and deposition, the cyclic voltammetry was used. The kinetics of electrochemical reactions in terms of polarization resistance was studied by electrochemical impedance spectroscopy. Based on scanning electron microscopy and EDS analysis, the effect of atmospheric oxygen and humidity on magnesium electrode corrosion during cycling was discussed.
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Mechanical Properties of Microstructural Components of Inorganic Materials
Wasserbauer, Jaromír ; Palou, Martin (referee) ; Drábik,, Milan (referee) ; Havlica, Jaromír (advisor)
Disertační práce se zabývá studiem strukturních a mechanických vlastností anorganických materiálů. Cílem je nalezení jednotlivých fází ve zkoumaném materiálu a hlavně lokalizace (mechanicky) nejslabšího místa, jeho ovlivnění a následně výroba materiálu o lepších mechanických vlastnostech. Z důvodu velkého množství použitých metod je základní teorie vložena vždy na začátku příslušné kapitoly. Taktéž z důvodu značného množství výsledků jsou na konci kapitol uvedeny dílčí závěry. Práce je rozdělena na tři části, kdy první se zabývá seznámením s možnostmi modelování mikro-mechanických vlastností a provedením experimentů umožňujících posouzení rozsahu platnosti některého modelu. V druhé části je provedeno shrnutí současných možností indentačních zkoušek pro měření mechanických vlastností strukturních složek betonu a praktické zvládnutí metodiky vhodné k užití pro výzkum materiálů zkoumaných domovským pracovištěm. V třetí části je navržena metoda identifikace nejslabších článků struktury anorganických pojiv a její ověření na konkrétním materiálu zkoumaném na domovském pracovišti. V této dizertační práci jsou použity tyto metody: kalorimetrie, ultrazvukové testování, jednoosá pevnost v tlaku, nanoindentace, korelativní mikroskopie a rastrovací elektronová mikroskopie s energiově disperzním spektrometrem. Dílčími výsledky jsou kompletní charakterizace cementových materiálů, upřesnění stávajících poznatků a nalezení optimálního postupu pro charakterizaci. Hlavním výsledkem je inovativní přístup vedoucí k pozitivnímu ovlivnění materiálu.
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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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Preparation and evaluation of fluoride conversion coating created on AZ31 wrought magnesium alloy
Matějka, Lukáš ; Wasserbauer, Jaromír (referee) ; Fintová, Stanislava (advisor)
The aim of this work is optimization of preparation parameters of fluoride conversion coating on the wrought magnesium alloy AZ31 in Na[BF4] melt. The monitored factors for determining quality of the prepared coatings are homogeneity of the coating surface on ground and polished samples of magnesium alloy, mechanical properties of the coating (adhesion and hardness) and the coating thickness. The main parameter was the change in these properties at different exposition times of the material to the salt melt. Coating surfaces were documented on an inverted light microscope with the addition of images representative samples using SEM. The coating thickness was documented with inverted light microscope using a polarization filter. The chemical composition was determined on three representative samples using an energy-dispersive X-ray spectrometer. The mechanical properties of the coatings were determined by scratch test on REVETEST Scratch Testing System with detector of acoustic emissions. The resulting scratches were documented on a light microscope. It was proved that polished samples exhibit superior coating in respect with ground samples, wherein the coating did not fill the trench after the finish treatment (grinding). Constant chemical composition has been demonstrated in all the coatings. Polished sample after 2 hours of exposure in the Na [BF 4] melt exhibits best mechanical properties. The obtained data are of practical importance in the use of the alloy AZ31 in various fields of industry, medicine and other research.
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