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Al-Li alloys were introduced for the use in aerospace applications due to its many advantages over steel such as its low density, good thermal and electrical conductivity and corrosion resistance of these alloys. The current generation of Al-Li alloys were developed to replace the currently used AA2024 alloy in commercial airframes, military and space applications. Traditional joining methods cannot be used to join dissimilar aluminium alloys. Thus, friction stir welding (FSW) was used to join the 2 dissimilar Al-Li alloys - AA2099 T83 and AA2060 T8E30 alloys. FSW causes several changes in the microstructure due to the rotational movement of the tool which results in localised plastic deformation and a thermal cycle in the alloys. This leads to 4 distinct zones in the alloys - the stir zone, thermo-mechanically affected zone, heat affected zone, and the base metal. The differences in microstructure is suggested to cause a change in the mechanical properties and localised corrosion behaviour of the alloys. In this work, the localised corrosion behaviour of the friction stir welded Al-Li alloys were investigated. The effect of FSW on the microstructure and corrosion behaviour was also studied. Microstructural characterisation was done for both the alloys and their respective weld zones. Coarse constituent particles were found in all weld zones with a decreasing trend in average size towards the weld centre. Strengthening precipitates such as the T_1 phase particles were observed on the grain boundaries of the alloys. This had a decreasing trend of distribution density towards the weld centre with virtually no precipitates in the SZ. In order to assess the corrosion performance potentiodynamic polarisation, open circuit potential, linear polarisation resistance, and immersion tests were deployed. Furthermore, scanning electron microscopy with energy dispersive X-ray spectroscopy was used to evaluate the morphology and chemical composition of the of the corroded surface, Mechanical Engineering | Vehicle Engineering

Al-Li alloys were introduced for the use in aerospace applications due to its many advantages over steel such as its low density, good thermal and electrical conductivity and corrosion resistance of these alloys. The current generation of Al-Li alloys were developed to replace the currently used AA2024 alloy in commercial airframes, military and space applications. Traditional joining methods cannot be used to join dissimilar aluminium alloys. Thus, friction stir welding (FSW) was used to join the 2 dissimilar Al-Li alloys - AA2099 T83 and AA2060 T8E30 alloys. FSW causes several changes in the microstructure due to the rotational movement of the tool which results in localised plastic deformation and a thermal cycle in the alloys. This leads to 4 distinct zones in the alloys - the stir zone, thermo-mechanically affected zone, heat affected zone, and the base metal. The differences in microstructure is suggested to cause a change in the mechanical properties and localised corrosion behaviour of the alloys. In this work, the localised corrosion behaviour of the friction stir welded Al-Li alloys were investigated. The effect of FSW on the microstructure and corrosion behaviour was also studied. Microstructural characterisation was done for both the alloys and their respective weld zones. Coarse constituent particles were found in all weld zones with a decreasing trend in average size towards the weld centre. Strengthening precipitates such as the T_1 phase particles were observed on the grain boundaries of the alloys. This had a decreasing trend of distribution density towards the weld centre with virtually no precipitates in the SZ. In order to assess the corrosion performance potentiodynamic polarisation, open circuit potential, linear polarisation resistance, and immersion tests were deployed. Furthermore, scanning electron microscopy with energy dispersive X-ray spectroscopy was used to evaluate the morphology and chemical composition of the of the corroded surface, Mechanical Engineering | Vehicle Engineering

Hexavalent chromium has been the industry standard for corrosion protection for many years. Its unsurpassed active corrosion inhibiting capabilities, its incredible versatility and its economic benefits made it a popular all-rounder. Nowadays the widely known toxic and carcinogenic nature have restricted its use within the European Union. More and more research in the field of corrosion science has been focussing on finding safer alternatives, since hexavalent chromium was officially added the US annual report on carcinogens in the 1980s. Before it was used in almost every step of corrosion protective schemes consisting of a pre-treatment, a primer and a topcoat. In this work a novel approach to two industrial anodising pre-treatments (sulfuric acid anodising and tartaric sulfuric acid anodising) was investigated in order to improve the corrosion performance of the corrosion sensitive aluminium alloy 2024-T3. Both are currently used as alternatives to the historically often applied chromic acid anodising procedure, which contains hexavalent chromium compounds. In this work the effect of the anodising electrolyte viscosity, the anodising interelectrode distance and the addition of ceric sulphate to the anodising bath were investigated. Different fractions of ethylene glycol were used to vary the electrolyte viscosity. All anodising procedures used a fixed anodising voltage, temperature, acid concentration and agitation speed. These parameters were not changed. All samples were cleaned before anodising. In order to assess the corrosion performance linear sweep voltammetry, electrochemical impedance spectroscopy and immersion tests were deployed. Furthermore scanning electron microscopy with energy dispersive X-ray spectroscopy was used to evaluate the chemical composition of the anodised substrates. It was found that an increase of the electrolyte viscosity results in a decrease of the anodising current density, which was related to a decrease in the overall thic, Materials Science and Engineering

Al-Li alloys were introduced for the use in aerospace applications due to its many advantages over steel such as its low density, good thermal and electrical conductivity and corrosion resistance of these alloys. The current generation of Al-Li alloys were developed to replace the currently used AA2024 alloy in commercial airframes, military and space applications. Traditional joining methods cannot be used to join dissimilar aluminium alloys. Thus, friction stir welding (FSW) was used to join the 2 dissimilar Al-Li alloys - AA2099 T83 and AA2060 T8E30 alloys. FSW causes several changes in the microstructure due to the rotational movement of the tool which results in localised plastic deformation and a thermal cycle in the alloys. This leads to 4 distinct zones in the alloys - the stir zone, thermo-mechanically affected zone, heat affected zone, and the base metal. The differences in microstructure is suggested to cause a change in the mechanical properties and localised corrosion behaviour of the alloys. In this work, the localised corrosion behaviour of the friction stir welded Al-Li alloys were investigated. The effect of FSW on the microstructure and corrosion behaviour was also studied. Microstructural characterisation was done for both the alloys and their respective weld zones. Coarse constituent particles were found in all weld zones with a decreasing trend in average size towards the weld centre. Strengthening precipitates such as the T_1 phase particles were observed on the grain boundaries of the alloys. This had a decreasing trend of distribution density towards the weld centre with virtually no precipitates in the SZ. In order to assess the corrosion performance potentiodynamic polarisation, open circuit potential, linear polarisation resistance, and immersion tests were deployed. Furthermore, scanning electron microscopy with energy dispersive X-ray spectroscopy was used to evaluate the morphology and chemical composition of the of the corroded surface, Mechanical Engineering | Vehicle Engineering

Hexavalent chromium has been the industry standard for corrosion protection for many years. Its unsurpassed active corrosion inhibiting capabilities, its incredible versatility and its economic benefits made it a popular all-rounder. Nowadays the widely known toxic and carcinogenic nature have restricted its use within the European Union. More and more research in the field of corrosion science has been focussing on finding safer alternatives, since hexavalent chromium was officially added the US annual report on carcinogens in the 1980s. Before it was used in almost every step of corrosion protective schemes consisting of a pre-treatment, a primer and a topcoat. In this work a novel approach to two industrial anodising pre-treatments (sulfuric acid anodising and tartaric sulfuric acid anodising) was investigated in order to improve the corrosion performance of the corrosion sensitive aluminium alloy 2024-T3. Both are currently used as alternatives to the historically often applied chromic acid anodising procedure, which contains hexavalent chromium compounds. In this work the effect of the anodising electrolyte viscosity, the anodising interelectrode distance and the addition of ceric sulphate to the anodising bath were investigated. Different fractions of ethylene glycol were used to vary the electrolyte viscosity. All anodising procedures used a fixed anodising voltage, temperature, acid concentration and agitation speed. These parameters were not changed. All samples were cleaned before anodising. In order to assess the corrosion performance linear sweep voltammetry, electrochemical impedance spectroscopy and immersion tests were deployed. Furthermore scanning electron microscopy with energy dispersive X-ray spectroscopy was used to evaluate the chemical composition of the anodised substrates. It was found that an increase of the electrolyte viscosity results in a decrease of the anodising current density, which was related to a decrease in the overall thic, Materials Science and Engineering

An investigation was conducted to determine the compatibility of recently specified silicone brake fluids with elastomers expected to be found in developmental vehicles submitted to US Army Aberdeen Proving Ground for tests and to compare their performance with conventional fluids. More than 1500 immersion tests were conducted at temperatures ranging from minus 18 to plus 120 degrees C (0 to 248 degrees F) with 14 different elastomers and 5 different brake fluids. It was found that the silicone brake fluids performed as well as/ or better than the conventional fluid in all tests involving vehicle brake system elastomers.

A recently developed fracture mechanics test (the A-S test), which involves pressurisation of an enclosed circular flaw, has been used to investigate the adhesion of two epoxy resins (Shell Epikote 828 and 3 M's SP 250) to glass. Specimens were tested after various times of immersion in water at 80 C and the adhesive failure energy theta determined. The effects of adding silane coupling agents to the epoxy resin and the influence of water pH were particularly studied. The theory of generalized fracture mechanics is used to derive, from theta, an intrinsic failure failure energy theta sub 0 which is the energy to break unit area of interatomic bonds across the interface. The decrease of theta sub 0 with time follows first order reaction kinetics, with a rate constant controlled by the type and concentration of coupling agent as well as by the pH of the aqueous environment. The results are interpreted in terms of the chemical hydrolysis of interfacial bonds. (Author)

An elastic stress analysis was performed on a wedge specimen (prismatic bar with double-edge wedge cross-section) subjected to thermal cycles in fluidized beds. Five alloys (IN 100, Mar-M 200, Mar-M 302, NASA TAZ-8A, and Rene 80) subjected to the same thermal cycling condition were analyzed. This condition was alternate 3 minute immersions in fluidized beds maintained at 316 degrees and 1088 degrees C (600 degrees and 1990 degrees F). The analyses were performed as a joint effort of two laboratories using different models and computer programs (NASTRAN and IS03DQ). Stress, strain, and temperature results are presented. (Author)

An investigation was conducted to determine the compatibility of recently specified silicone brake fluids with elastomers expected to be found in developmental vehicles submitted to US Army Aberdeen Proving Ground for tests and to compare their performance with conventional fluids. More than 1200 immersion tests were conducted at temperatures ranging from 0 degree F to 248 degrees F (-18 to +120 degrees C) with 14 different elastomers and 5 different brake fluids. It was found that the silicone brake fluids performed as well as/or better than the conventional fluid in all tests involving vehicle brake system elastomers. Extended periods of exposure did not reveal any deficiencies. Studies are continuing on mixtures of silicone and conventional fluids in order to accumulate data which will aid in identifying and evaluating possible problems found in test vehicles. (Author)

Predložená práca sa zaoberá nekonvenčnou technológiou prípravy fluoridového konverzného povlaku na horčíkových zliatinách typu AZ31, AZ61, ZE10 a ZE41, a to vložením zliatin do roztavenej soli Na[BF4]. V práci je posudzovaný vplyv technologických parametrov prípravy (teplota a čas) na kvalitu vzniknutého fluoridového konverzného povlaku, a to z hľadiska morfológie, chemického zloženia a jeho dosiahnutej hrúbky, kedy boli využité metódy svetelnej a elektrónovej mikroskopie. Vybrané vzorky bez a s fluoridovým konverzným povlakom boli podrobené krátkodobým a dlhodobým koróznym skúškam v roztoku simulovaných telesných tekutín pri teplote 37 ± 2 °C. Na vyhodnotenie krátkodobých skúšok boli využité potenciodynamické skúšky, konkrétne metóda lineárnej polarizácie a pre dlhodobé experimenty bola využitá metóda elektrochemickej impedančnej spektroskopie, či ponorové skúšky. Na základe dosiahnutých výsledkov bol definovaný vplyv parametrov prípravy povlaku na charakter vytvoreného fluoridového konverzného povlaku. Ďalšia časť práce je zameraná na popis možného mechanizmu vzniku a kinetiky rastu nekonvenčného fluoridového konverzného povlaku na vybranej horčíkovej zliatine AZ61. V tejto časti práce bola ďalej detailne vykonaná analýza mikroštruktúry a chemického zloženia fluoridového konverzného povlaku s využitím fokusovaného iónového zväzku, transmisnej elektrónovej mikroskopie a röntgenovej fotoelektrónovej spektroskopie., The submitted work is aimed at the unconventional fluoride conversation coating preparation on the AZ31, AZ61, ZE10 and ZE41 magnesium alloys by their immersion in Na[BF4] molten salt. The influence of the preparation parameters (such as temperature and time) on the quality of the fluoride conversion coating is investigated. Methods of light and scanning electron microscopy were used for the evaluation of morphology, chemical composition and thickness of the coating. Short and long-term corrosion tests were executed to analyze the corrosion performance in simulated body fluid solution at 37 ± 2 °C with and without the fluoride conversion coating. The short-term behavior was evaluated by potentiodynamic tests, namely by the linear polarization. Long-term performance was assessed by electrochemical impedance spectroscopy or immersion tests. The coating preparation parameters influence on the character of the formed fluoride conversion coating was defined based on the obtained results. The next part of the thesis deals with the description of the possible mechanism of formation and kinetics of growth of the unconventional fluoride conversion coating on the selected AZ61 magnesium alloy. In this part, further detailed analyses were carried out to investigate the microstructure and chemical composition of the fluoride conversion coating using focused ion beam, transmission electron microscopy and X-ray photoelectron spectroscopy.

Predložená práca sa zaoberá nekonvenčnou technológiou prípravy fluoridového konverzného povlaku na horčíkových zliatinách typu AZ31, AZ61, ZE10 a ZE41, a to vložením zliatin do roztavenej soli Na[BF4]. V práci je posudzovaný vplyv technologických parametrov prípravy (teplota a čas) na kvalitu vzniknutého fluoridového konverzného povlaku, a to z hľadiska morfológie, chemického zloženia a jeho dosiahnutej hrúbky, kedy boli využité metódy svetelnej a elektrónovej mikroskopie. Vybrané vzorky bez a s fluoridovým konverzným povlakom boli podrobené krátkodobým a dlhodobým koróznym skúškam v roztoku simulovaných telesných tekutín pri teplote 37 ± 2 °C. Na vyhodnotenie krátkodobých skúšok boli využité potenciodynamické skúšky, konkrétne metóda lineárnej polarizácie a pre dlhodobé experimenty bola využitá metóda elektrochemickej impedančnej spektroskopie, či ponorové skúšky. Na základe dosiahnutých výsledkov bol definovaný vplyv parametrov prípravy povlaku na charakter vytvoreného fluoridového konverzného povlaku. Ďalšia časť práce je zameraná na popis možného mechanizmu vzniku a kinetiky rastu nekonvenčného fluoridového konverzného povlaku na vybranej horčíkovej zliatine AZ61. V tejto časti práce bola ďalej detailne vykonaná analýza mikroštruktúry a chemického zloženia fluoridového konverzného povlaku s využitím fokusovaného iónového zväzku, transmisnej elektrónovej mikroskopie a röntgenovej fotoelektrónovej spektroskopie., The submitted work is aimed at the unconventional fluoride conversation coating preparation on the AZ31, AZ61, ZE10 and ZE41 magnesium alloys by their immersion in Na[BF4] molten salt. The influence of the preparation parameters (such as temperature and time) on the quality of the fluoride conversion coating is investigated. Methods of light and scanning electron microscopy were used for the evaluation of morphology, chemical composition and thickness of the coating. Short and long-term corrosion tests were executed to analyze the corrosion performance in simulated body fluid solution at 37 ± 2 °C with and without the fluoride conversion coating. The short-term behavior was evaluated by potentiodynamic tests, namely by the linear polarization. Long-term performance was assessed by electrochemical impedance spectroscopy or immersion tests. The coating preparation parameters influence on the character of the formed fluoride conversion coating was defined based on the obtained results. The next part of the thesis deals with the description of the possible mechanism of formation and kinetics of growth of the unconventional fluoride conversion coating on the selected AZ61 magnesium alloy. In this part, further detailed analyses were carried out to investigate the microstructure and chemical composition of the fluoride conversion coating using focused ion beam, transmission electron microscopy and X-ray photoelectron spectroscopy.

Diplomová práce se zabývá korozní odolností nikl-fosforových povlaků na hořčíkové slitině AZ91. V teoretické části jsou shrnuty současné znalosti o hořčíkových slitinách a bezproudé depozici Ni-P povlaků včetně reakcí při níž probíhajících. Dále jsou v teoretické části uvedeny jednotlivé složky obsažené v niklovací lázni a jejich význam. Druhá půlka teoretické části pojednává o korozi a ponorových testech. Na závěr jsou uvedeny rešerše ze současného výzkumu v oblasti ponorových testů. Experimentální část se zabývá jednotlivými kroky předúpravy hořčíkové slitiny a následnou depozicí Ni-P povlaku. Pomocí energiově disperzní spektroskopie bylo určeno prvkové složení Ni-P povlaku i hořčíkové slitiny. Dále jsou v experimentální části popsány pokusy zjišťující ideální tloušťku nízkofosforového povlaku, který ochrání hořčíkovou slitinu před zkorodováním. Diplomová práce je zakončena seznamem ponorový testů a výsledky z nichž vycházejících., This master’s thesis is focused on corrosion resistance of nickel-phosphorus coatings on magnesium alloy AZ91. In the theoretical part is summarized current knowledge about magnesium alloys and electroless deposition of Ni-P coatings including ongoing reactions. Theoretical part also lists all substances contained in the nickel bath and their specific use there. In the second half of theoretical part are discussed corrosion and immersion tests. Theoretical part is ended by review aimed towards the research in areas of immersion tests. Experimental part describes individual steps of pretreatment on magnesium alloy and then deposition of the Ni-P coating. Composition and morphology of deposited Ni-P coating and magnesium alloy were studied using energy dispersive spectroscopy. Experiment part also contains list of experiments trying to figure out ideal thickness of low-phosphorus coating which is able to protect magnesium alloy from corrosion. Master’s thesis is ended with the list of immersion tests and results which outcomes from them.

Diplomová práce se zabývá korozní odolností nikl-fosforových povlaků na hořčíkové slitině AZ91. V teoretické části jsou shrnuty současné znalosti o hořčíkových slitinách a bezproudé depozici Ni-P povlaků včetně reakcí při níž probíhajících. Dále jsou v teoretické části uvedeny jednotlivé složky obsažené v niklovací lázni a jejich význam. Druhá půlka teoretické části pojednává o korozi a ponorových testech. Na závěr jsou uvedeny rešerše ze současného výzkumu v oblasti ponorových testů. Experimentální část se zabývá jednotlivými kroky předúpravy hořčíkové slitiny a následnou depozicí Ni-P povlaku. Pomocí energiově disperzní spektroskopie bylo určeno prvkové složení Ni-P povlaku i hořčíkové slitiny. Dále jsou v experimentální části popsány pokusy zjišťující ideální tloušťku nízkofosforového povlaku, který ochrání hořčíkovou slitinu před zkorodováním. Diplomová práce je zakončena seznamem ponorový testů a výsledky z nichž vycházejících., This master’s thesis is focused on corrosion resistance of nickel-phosphorus coatings on magnesium alloy AZ91. In the theoretical part is summarized current knowledge about magnesium alloys and electroless deposition of Ni-P coatings including ongoing reactions. Theoretical part also lists all substances contained in the nickel bath and their specific use there. In the second half of theoretical part are discussed corrosion and immersion tests. Theoretical part is ended by review aimed towards the research in areas of immersion tests. Experimental part describes individual steps of pretreatment on magnesium alloy and then deposition of the Ni-P coating. Composition and morphology of deposited Ni-P coating and magnesium alloy were studied using energy dispersive spectroscopy. Experiment part also contains list of experiments trying to figure out ideal thickness of low-phosphorus coating which is able to protect magnesium alloy from corrosion. Master’s thesis is ended with the list of immersion tests and results which outcomes from them.

Predložená práca sa zaoberá nekonvenčnou technológiou prípravy fluoridového konverzného povlaku na horčíkových zliatinách typu AZ31, AZ61, ZE10 a ZE41, a to vložením zliatin do roztavenej soli Na[BF4]. V práci je posudzovaný vplyv technologických parametrov prípravy (teplota a čas) na kvalitu vzniknutého fluoridového konverzného povlaku, a to z hľadiska morfológie, chemického zloženia a jeho dosiahnutej hrúbky, kedy boli využité metódy svetelnej a elektrónovej mikroskopie. Vybrané vzorky bez a s fluoridovým konverzným povlakom boli podrobené krátkodobým a dlhodobým koróznym skúškam v roztoku simulovaných telesných tekutín pri teplote 37 ± 2 °C. Na vyhodnotenie krátkodobých skúšok boli využité potenciodynamické skúšky, konkrétne metóda lineárnej polarizácie a pre dlhodobé experimenty bola využitá metóda elektrochemickej impedančnej spektroskopie, či ponorové skúšky. Na základe dosiahnutých výsledkov bol definovaný vplyv parametrov prípravy povlaku na charakter vytvoreného fluoridového konverzného povlaku. Ďalšia časť práce je zameraná na popis možného mechanizmu vzniku a kinetiky rastu nekonvenčného fluoridového konverzného povlaku na vybranej horčíkovej zliatine AZ61. V tejto časti práce bola ďalej detailne vykonaná analýza mikroštruktúry a chemického zloženia fluoridového konverzného povlaku s využitím fokusovaného iónového zväzku, transmisnej elektrónovej mikroskopie a röntgenovej fotoelektrónovej spektroskopie., The submitted work is aimed at the unconventional fluoride conversation coating preparation on the AZ31, AZ61, ZE10 and ZE41 magnesium alloys by their immersion in Na[BF4] molten salt. The influence of the preparation parameters (such as temperature and time) on the quality of the fluoride conversion coating is investigated. Methods of light and scanning electron microscopy were used for the evaluation of morphology, chemical composition and thickness of the coating. Short and long-term corrosion tests were executed to analyze the corrosion performance in simulated body fluid solution at 37 ± 2 °C with and without the fluoride conversion coating. The short-term behavior was evaluated by potentiodynamic tests, namely by the linear polarization. Long-term performance was assessed by electrochemical impedance spectroscopy or immersion tests. The coating preparation parameters influence on the character of the formed fluoride conversion coating was defined based on the obtained results. The next part of the thesis deals with the description of the possible mechanism of formation and kinetics of growth of the unconventional fluoride conversion coating on the selected AZ61 magnesium alloy. In this part, further detailed analyses were carried out to investigate the microstructure and chemical composition of the fluoride conversion coating using focused ion beam, transmission electron microscopy and X-ray photoelectron spectroscopy.

Diplomová práce se zabývá korozní odolností nikl-fosforových povlaků na hořčíkové slitině AZ91. V teoretické části jsou shrnuty současné znalosti o hořčíkových slitinách a bezproudé depozici Ni-P povlaků včetně reakcí při níž probíhajících. Dále jsou v teoretické části uvedeny jednotlivé složky obsažené v niklovací lázni a jejich význam. Druhá půlka teoretické části pojednává o korozi a ponorových testech. Na závěr jsou uvedeny rešerše ze současného výzkumu v oblasti ponorových testů. Experimentální část se zabývá jednotlivými kroky předúpravy hořčíkové slitiny a následnou depozicí Ni-P povlaku. Pomocí energiově disperzní spektroskopie bylo určeno prvkové složení Ni-P povlaku i hořčíkové slitiny. Dále jsou v experimentální části popsány pokusy zjišťující ideální tloušťku nízkofosforového povlaku, který ochrání hořčíkovou slitinu před zkorodováním. Diplomová práce je zakončena seznamem ponorový testů a výsledky z nichž vycházejících., This master’s thesis is focused on corrosion resistance of nickel-phosphorus coatings on magnesium alloy AZ91. In the theoretical part is summarized current knowledge about magnesium alloys and electroless deposition of Ni-P coatings including ongoing reactions. Theoretical part also lists all substances contained in the nickel bath and their specific use there. In the second half of theoretical part are discussed corrosion and immersion tests. Theoretical part is ended by review aimed towards the research in areas of immersion tests. Experimental part describes individual steps of pretreatment on magnesium alloy and then deposition of the Ni-P coating. Composition and morphology of deposited Ni-P coating and magnesium alloy were studied using energy dispersive spectroscopy. Experiment part also contains list of experiments trying to figure out ideal thickness of low-phosphorus coating which is able to protect magnesium alloy from corrosion. Master’s thesis is ended with the list of immersion tests and results which outcomes from them.

Predložená práca sa zaoberá nekonvenčnou technológiou prípravy fluoridového konverzného povlaku na horčíkových zliatinách typu AZ31, AZ61, ZE10 a ZE41, a to vložením zliatin do roztavenej soli Na[BF4]. V práci je posudzovaný vplyv technologických parametrov prípravy (teplota a čas) na kvalitu vzniknutého fluoridového konverzného povlaku, a to z hľadiska morfológie, chemického zloženia a jeho dosiahnutej hrúbky, kedy boli využité metódy svetelnej a elektrónovej mikroskopie. Vybrané vzorky bez a s fluoridovým konverzným povlakom boli podrobené krátkodobým a dlhodobým koróznym skúškam v roztoku simulovaných telesných tekutín pri teplote 37 ± 2 °C. Na vyhodnotenie krátkodobých skúšok boli využité potenciodynamické skúšky, konkrétne metóda lineárnej polarizácie a pre dlhodobé experimenty bola využitá metóda elektrochemickej impedančnej spektroskopie, či ponorové skúšky. Na základe dosiahnutých výsledkov bol definovaný vplyv parametrov prípravy povlaku na charakter vytvoreného fluoridového konverzného povlaku. Ďalšia časť práce je zameraná na popis možného mechanizmu vzniku a kinetiky rastu nekonvenčného fluoridového konverzného povlaku na vybranej horčíkovej zliatine AZ61. V tejto časti práce bola ďalej detailne vykonaná analýza mikroštruktúry a chemického zloženia fluoridového konverzného povlaku s využitím fokusovaného iónového zväzku, transmisnej elektrónovej mikroskopie a röntgenovej fotoelektrónovej spektroskopie., The submitted work is aimed at the unconventional fluoride conversation coating preparation on the AZ31, AZ61, ZE10 and ZE41 magnesium alloys by their immersion in Na[BF4] molten salt. The influence of the preparation parameters (such as temperature and time) on the quality of the fluoride conversion coating is investigated. Methods of light and scanning electron microscopy were used for the evaluation of morphology, chemical composition and thickness of the coating. Short and long-term corrosion tests were executed to analyze the corrosion performance in simulated body fluid solution at 37 ± 2 °C with and without the fluoride conversion coating. The short-term behavior was evaluated by potentiodynamic tests, namely by the linear polarization. Long-term performance was assessed by electrochemical impedance spectroscopy or immersion tests. The coating preparation parameters influence on the character of the formed fluoride conversion coating was defined based on the obtained results. The next part of the thesis deals with the description of the possible mechanism of formation and kinetics of growth of the unconventional fluoride conversion coating on the selected AZ61 magnesium alloy. In this part, further detailed analyses were carried out to investigate the microstructure and chemical composition of the fluoride conversion coating using focused ion beam, transmission electron microscopy and X-ray photoelectron spectroscopy.

Diplomová práce se zabývá korozní odolností nikl-fosforových povlaků na hořčíkové slitině AZ91. V teoretické části jsou shrnuty současné znalosti o hořčíkových slitinách a bezproudé depozici Ni-P povlaků včetně reakcí při níž probíhajících. Dále jsou v teoretické části uvedeny jednotlivé složky obsažené v niklovací lázni a jejich význam. Druhá půlka teoretické části pojednává o korozi a ponorových testech. Na závěr jsou uvedeny rešerše ze současného výzkumu v oblasti ponorových testů. Experimentální část se zabývá jednotlivými kroky předúpravy hořčíkové slitiny a následnou depozicí Ni-P povlaku. Pomocí energiově disperzní spektroskopie bylo určeno prvkové složení Ni-P povlaku i hořčíkové slitiny. Dále jsou v experimentální části popsány pokusy zjišťující ideální tloušťku nízkofosforového povlaku, který ochrání hořčíkovou slitinu před zkorodováním. Diplomová práce je zakončena seznamem ponorový testů a výsledky z nichž vycházejících., This master’s thesis is focused on corrosion resistance of nickel-phosphorus coatings on magnesium alloy AZ91. In the theoretical part is summarized current knowledge about magnesium alloys and electroless deposition of Ni-P coatings including ongoing reactions. Theoretical part also lists all substances contained in the nickel bath and their specific use there. In the second half of theoretical part are discussed corrosion and immersion tests. Theoretical part is ended by review aimed towards the research in areas of immersion tests. Experimental part describes individual steps of pretreatment on magnesium alloy and then deposition of the Ni-P coating. Composition and morphology of deposited Ni-P coating and magnesium alloy were studied using energy dispersive spectroscopy. Experiment part also contains list of experiments trying to figure out ideal thickness of low-phosphorus coating which is able to protect magnesium alloy from corrosion. Master’s thesis is ended with the list of immersion tests and results which outcomes from them.

Predložená práca sa zaoberá nekonvenčnou technológiou prípravy fluoridového konverzného povlaku na horčíkových zliatinách typu AZ31, AZ61, ZE10 a ZE41, a to vložením zliatin do roztavenej soli Na[BF4]. V práci je posudzovaný vplyv technologických parametrov prípravy (teplota a čas) na kvalitu vzniknutého fluoridového konverzného povlaku, a to z hľadiska morfológie, chemického zloženia a jeho dosiahnutej hrúbky, kedy boli využité metódy svetelnej a elektrónovej mikroskopie. Vybrané vzorky bez a s fluoridovým konverzným povlakom boli podrobené krátkodobým a dlhodobým koróznym skúškam v roztoku simulovaných telesných tekutín pri teplote 37 ± 2 °C. Na vyhodnotenie krátkodobých skúšok boli využité potenciodynamické skúšky, konkrétne metóda lineárnej polarizácie a pre dlhodobé experimenty bola využitá metóda elektrochemickej impedančnej spektroskopie, či ponorové skúšky. Na základe dosiahnutých výsledkov bol definovaný vplyv parametrov prípravy povlaku na charakter vytvoreného fluoridového konverzného povlaku. Ďalšia časť práce je zameraná na popis možného mechanizmu vzniku a kinetiky rastu nekonvenčného fluoridového konverzného povlaku na vybranej horčíkovej zliatine AZ61. V tejto časti práce bola ďalej detailne vykonaná analýza mikroštruktúry a chemického zloženia fluoridového konverzného povlaku s využitím fokusovaného iónového zväzku, transmisnej elektrónovej mikroskopie a röntgenovej fotoelektrónovej spektroskopie., The submitted work is aimed at the unconventional fluoride conversation coating preparation on the AZ31, AZ61, ZE10 and ZE41 magnesium alloys by their immersion in Na[BF4] molten salt. The influence of the preparation parameters (such as temperature and time) on the quality of the fluoride conversion coating is investigated. Methods of light and scanning electron microscopy were used for the evaluation of morphology, chemical composition and thickness of the coating. Short and long-term corrosion tests were executed to analyze the corrosion performance in simulated body fluid solution at 37 ± 2 °C with and without the fluoride conversion coating. The short-term behavior was evaluated by potentiodynamic tests, namely by the linear polarization. Long-term performance was assessed by electrochemical impedance spectroscopy or immersion tests. The coating preparation parameters influence on the character of the formed fluoride conversion coating was defined based on the obtained results. The next part of the thesis deals with the description of the possible mechanism of formation and kinetics of growth of the unconventional fluoride conversion coating on the selected AZ61 magnesium alloy. In this part, further detailed analyses were carried out to investigate the microstructure and chemical composition of the fluoride conversion coating using focused ion beam, transmission electron microscopy and X-ray photoelectron spectroscopy.

Predložená práca sa zaoberá nekonvenčnou technológiou prípravy fluoridového konverzného povlaku na horčíkových zliatinách typu AZ31, AZ61, ZE10 a ZE41, a to vložením zliatin do roztavenej soli Na[BF4]. V práci je posudzovaný vplyv technologických parametrov prípravy (teplota a čas) na kvalitu vzniknutého fluoridového konverzného povlaku, a to z hľadiska morfológie, chemického zloženia a jeho dosiahnutej hrúbky, kedy boli využité metódy svetelnej a elektrónovej mikroskopie. Vybrané vzorky bez a s fluoridovým konverzným povlakom boli podrobené krátkodobým a dlhodobým koróznym skúškam v roztoku simulovaných telesných tekutín pri teplote 37 ± 2 °C. Na vyhodnotenie krátkodobých skúšok boli využité potenciodynamické skúšky, konkrétne metóda lineárnej polarizácie a pre dlhodobé experimenty bola využitá metóda elektrochemickej impedančnej spektroskopie, či ponorové skúšky. Na základe dosiahnutých výsledkov bol definovaný vplyv parametrov prípravy povlaku na charakter vytvoreného fluoridového konverzného povlaku. Ďalšia časť práce je zameraná na popis možného mechanizmu vzniku a kinetiky rastu nekonvenčného fluoridového konverzného povlaku na vybranej horčíkovej zliatine AZ61. V tejto časti práce bola ďalej detailne vykonaná analýza mikroštruktúry a chemického zloženia fluoridového konverzného povlaku s využitím fokusovaného iónového zväzku, transmisnej elektrónovej mikroskopie a röntgenovej fotoelektrónovej spektroskopie., The submitted work is aimed at the unconventional fluoride conversation coating preparation on the AZ31, AZ61, ZE10 and ZE41 magnesium alloys by their immersion in Na[BF4] molten salt. The influence of the preparation parameters (such as temperature and time) on the quality of the fluoride conversion coating is investigated. Methods of light and scanning electron microscopy were used for the evaluation of morphology, chemical composition and thickness of the coating. Short and long-term corrosion tests were executed to analyze the corrosion performance in simulated body fluid solution at 37 ± 2 °C with and without the fluoride conversion coating. The short-term behavior was evaluated by potentiodynamic tests, namely by the linear polarization. Long-term performance was assessed by electrochemical impedance spectroscopy or immersion tests. The coating preparation parameters influence on the character of the formed fluoride conversion coating was defined based on the obtained results. The next part of the thesis deals with the description of the possible mechanism of formation and kinetics of growth of the unconventional fluoride conversion coating on the selected AZ61 magnesium alloy. In this part, further detailed analyses were carried out to investigate the microstructure and chemical composition of the fluoride conversion coating using focused ion beam, transmission electron microscopy and X-ray photoelectron spectroscopy.

Diplomová práce se zabývá korozní odolností nikl-fosforových povlaků na hořčíkové slitině AZ91. V teoretické části jsou shrnuty současné znalosti o hořčíkových slitinách a bezproudé depozici Ni-P povlaků včetně reakcí při níž probíhajících. Dále jsou v teoretické části uvedeny jednotlivé složky obsažené v niklovací lázni a jejich význam. Druhá půlka teoretické části pojednává o korozi a ponorových testech. Na závěr jsou uvedeny rešerše ze současného výzkumu v oblasti ponorových testů. Experimentální část se zabývá jednotlivými kroky předúpravy hořčíkové slitiny a následnou depozicí Ni-P povlaku. Pomocí energiově disperzní spektroskopie bylo určeno prvkové složení Ni-P povlaku i hořčíkové slitiny. Dále jsou v experimentální části popsány pokusy zjišťující ideální tloušťku nízkofosforového povlaku, který ochrání hořčíkovou slitinu před zkorodováním. Diplomová práce je zakončena seznamem ponorový testů a výsledky z nichž vycházejících., This master’s thesis is focused on corrosion resistance of nickel-phosphorus coatings on magnesium alloy AZ91. In the theoretical part is summarized current knowledge about magnesium alloys and electroless deposition of Ni-P coatings including ongoing reactions. Theoretical part also lists all substances contained in the nickel bath and their specific use there. In the second half of theoretical part are discussed corrosion and immersion tests. Theoretical part is ended by review aimed towards the research in areas of immersion tests. Experimental part describes individual steps of pretreatment on magnesium alloy and then deposition of the Ni-P coating. Composition and morphology of deposited Ni-P coating and magnesium alloy were studied using energy dispersive spectroscopy. Experiment part also contains list of experiments trying to figure out ideal thickness of low-phosphorus coating which is able to protect magnesium alloy from corrosion. Master’s thesis is ended with the list of immersion tests and results which outcomes from them.

Diplomová práce se zabývá korozní odolností nikl-fosforových povlaků na hořčíkové slitině AZ91. V teoretické části jsou shrnuty současné znalosti o hořčíkových slitinách a bezproudé depozici Ni-P povlaků včetně reakcí při níž probíhajících. Dále jsou v teoretické části uvedeny jednotlivé složky obsažené v niklovací lázni a jejich význam. Druhá půlka teoretické části pojednává o korozi a ponorových testech. Na závěr jsou uvedeny rešerše ze současného výzkumu v oblasti ponorových testů. Experimentální část se zabývá jednotlivými kroky předúpravy hořčíkové slitiny a následnou depozicí Ni-P povlaku. Pomocí energiově disperzní spektroskopie bylo určeno prvkové složení Ni-P povlaku i hořčíkové slitiny. Dále jsou v experimentální části popsány pokusy zjišťující ideální tloušťku nízkofosforového povlaku, který ochrání hořčíkovou slitinu před zkorodováním. Diplomová práce je zakončena seznamem ponorový testů a výsledky z nichž vycházejících., This master’s thesis is focused on corrosion resistance of nickel-phosphorus coatings on magnesium alloy AZ91. In the theoretical part is summarized current knowledge about magnesium alloys and electroless deposition of Ni-P coatings including ongoing reactions. Theoretical part also lists all substances contained in the nickel bath and their specific use there. In the second half of theoretical part are discussed corrosion and immersion tests. Theoretical part is ended by review aimed towards the research in areas of immersion tests. Experimental part describes individual steps of pretreatment on magnesium alloy and then deposition of the Ni-P coating. Composition and morphology of deposited Ni-P coating and magnesium alloy were studied using energy dispersive spectroscopy. Experiment part also contains list of experiments trying to figure out ideal thickness of low-phosphorus coating which is able to protect magnesium alloy from corrosion. Master’s thesis is ended with the list of immersion tests and results which outcomes from them.

98482, Many commonly used culvert rehabilitation technologies entail the use of a resin or coating that cures to form a rigid, liner within the damaged culvert. However, the potential environmental impacts of leaching or release of contaminants during, normal installation practices have not been well studied. Evaluations of previous culvert repair operations by the Virginia, Department of Transportation (VDOT) were conducted for conventional (styrene-based) cured-in-place pipe and fold and form, repair technologies. The study reported herein included an evaluation of two additional technologies available for use by VDOT, a polymer-enhanced cement mortar (or cementitious) spray-on liner and a polyurea spray-on liner., To evaluate the potential for these lining technologies to impact water quality, installations were monitored up to 49, days. Three water quality tests were conducted for each installation, and water samples were analyzed for water quality, indicators and constituents listed in material safety data sheets. Tests included a water flow simulation with low dilution, potential; an immersion test to simulate a standing water scenario; and a laboratory leaching test. Results were then compared, against established regulatory standards and published toxicity criteria for aquatic species., For the cementitious spray-on liner evaluated, pH and alkalinity exceeded specified Virginia water standards in, laboratory tests but pH and other evaluated compounds were within the acceptable range in water flow and immersion tests. For, the polyurea spray-on liner evaluated, elevated water quality indicators (i.e., biochemical oxygen demand, chemical oxygen, demand, total organic carbon, and total nitrogen) in laboratory tests suggested that contaminants were released from the polyurea, liner, particularly during its initial contact with water, but water quality impacts were not detected in the other tests. Water flow, dilution, and volatilization appear to play an important role in reducing water quality impacts from contaminant leaching., The study recommends that VDOT specifications include protective controls for spray-on liners to prevent exceeding, water quality standards or toxicity thresholds for aquatic species in receiving waters with low flows and little dilution potential.

SPR-PL-1-(47)402, In 1993, the Arizona Department of Transportation (ADOT) constructed pavement test sections as part of the Long, Term Pavement Performance (LTPP) Specific Pavement Studies (SPS). The test sections are located on US 93 north, of Kingman, Arizona, and consist of both SPS-1 and SPS-9 experiments constructed at the same location. As early as, 1996 it was reported that fatigue cracking was occurring in the SPS-9 Superpave sections. A field visit in 1998 by, personnel from ADOT, LTPP, and the FHWA revealed that the SPS-9 Superpave test sections were experiencing, premature fatigue cracking while the SPS-1 test sections which used Marshall Mix designs had not experienced any, distress. The survey team concluded that moisture sensitivity may be the primary cause of the premature fatigue of, the Superpave designed HMA mixtures. An investigation into this premature failure was subsequently initiated., This report describes the performance of the SPS-9 sections and documents the laboratory evaluation of mixtures, and cores from the three sections in an effort to assess the appropriateness of the Superpave moisture damage, requirements. The three evaluated sections included: a Superpave designed section with 1” nominal maximum size, a, Superpave designed section with 3/4” nominal maximum size, and an ADOT Marshall designed section with 3/4”, nominal maximum size. The two Superpave sections did not include anti-stripping additive based on the results of the, Superpave moisture sensitivity testing. The ADOT section included 2% Portland Cement (PC) based on the results of, the ADOT immersion compression test., This research project evaluated the moisture sensitivity of the HMA mixtures used on all three sections using a, modified AASHTO T-283 procedure and a modified ADOT immersion compression test procedure. Laboratory, mixtures and field cores were tested by the modified AASHTO T-283 method using both the freeze/thaw and no, freeze/thaw conditioning methods. Three methods of compaction were used (gyratory 4- and 6-inch and Marshall 4, inch)., The analysis of the data generated in this study led to the following conclusions: The moisture conditioning, (freeze/thaw and no freeze/thaw) did not significantly impact the retained strength ratios of HMA mixtures as measured, by the resilient modulus (Mr) and Indirect Tensile Strength (ITS) test procedures. The impact of compaction method, on retained strength of HMA mixtures is affected by other factors such as: type of mixture and the addition of PC., The impact of adding PC to HMA mixtures showed mixed results depending on compaction method. The ability, of the modified AASHTO T-283 method in assessing moisture sensitivity of HMA mixtures, with either the gyratory, or the Marshall compaction methods, is questionable. Similarly, ADOT immersion compression test results provided, questionable value in discriminating between acceptable and unacceptable mixes.

ODOT performed preliminary tests on eight different models of solar powered raised pavement markers. These included environmental tests (extreme temperatures, immersion), optical performance tests, and observation tests. Federal Highway Administration’s Photometric and Visibility Laboratory at the Turner-Fairbank Highway Research Center conducted additional tests on some of the markers to measure the LED signal and retroreflectivity at different distances and angles. The tests were designed to replicate what drivers would see on the road. It was found that each type of marker had significant shortcomings.

HPR 085-5167, A standard accelerated weathering test using Dimethyl Sulfoxide (DMSO) was developed to simulate the chemical degradation of basaltic rocks. After a thorough study of the parameters affecting the current procedure, such as container geometry, aggregate particle size, sample weight, and immersion time, a standard test was developed. The recommended procedure consists of immersing a sample of aggregate in the size range between 2.38 mm (#8) and 4.76 mm (#4), weighing 1000g, for a period of five (5) days. At the end of the immersion time the aggregate is re-screened over the 2.38 mm (#8) sieve and the percent weight loss is calculated. The acceptable weight loss limit for the DMSO Accelerated Weathering Test was established by correlating the test results to those obtained through petrographic analysis. The petrographic analysis consisted of determining the percentage of deleterious secondary minerals and their textural distribution within the rock matrix. With these two parameters, a Secondary Mineral Rating for each quarry was calculated and compared to the DMSO test results. In addition, it was found that DMSO may overreact if the minerals analcime and calcite are present in the quarry rock. A second indirect test, the Clay Index, was presented as a simple method to determine the likelihood of DMSO to overreact, since it was found to be insensitive to the type of minerals present in the rock.