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Development of WAAM process parameters for thin-walled components made of magnesium alloy AZ61
Šváb, Čeněk ; Němeček, Stanislav (referee) ; Slavíček, Jakub (advisor)
The thesis deals with the development of WAAM (Wire Arc Additive Manufacturing) process parameters for thin-walled parts made of magnesium alloy AZ61. The aim of the thesis is to find suitable process parameters and describe their influences on the welding process. To achieve this goal, these parameters were experimentally tested. It was found that the parameter of boost phase current and the duration of its application have the highest influence on the weld geometry. The stability of the welding process was then influenced by the electrode feed rate during the boost and burn phases. Based on these results, a final set of parameters was created, which successfully welded a thin-walled part composed of 50 layers and reaching a height of 130 mm.
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Ni-P based coatings preparation on wrought magnesium alloys
Buchtík, Martin ; Fintová, Stanislava (referee) ; Wasserbauer, Jaromír (advisor)
The aim of this diploma thesis was summary of all steps and knowledge necessary to deposition of quality Ni-P coatings deposited on wrought magnesium alloys AZ31 and AZ61. There is the treatise about wrought magnesium alloys AZ31 and AZ61. Thesis includes its phase composition in the theoretical part. There are given its possible processing methods too. Next, there is desribed the mechanism of deposition of Ni-P coatings, components required to electroless deposition and factors affecting the quality and properties of these coatings. The theoretical part is ended by serie of reviews. Authors of these reviews deal with pretreatment of substrates, preparation, characterization and measuring of mechanical, structure and corrosion properties of deposited coatings. The optimalization of pretreatment, parametres and composition of nickel bath suitable for magnesium alloys is described in experimental part. The microstructure, present interlayer between substrate and Ni-P coating and chemical composition of deposited coatings was observed and measured by optical and electron microscopy. The mechanical characterization of Ni-P coatings was performed by microhardness tester.
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Fluoride coatings on magnesium prepared in melts
Drábiková, Juliána ; Richtera, Lukáš (referee) ; Zmrzlý, Martin (advisor)
This work deals with the corrosion protection of magnesium alloy AZ31, AZ61, AZ91 using fluoride conversion coating prepared from Na[BF4] melt. The theoretical part describes the properties of magnesium alloys, the recent results of fluoride conversion coatings preparation and analysis of the available literature about the properties of salt Na[BF4] and its decomposition products. The experimental part was devided into two main sections. The first deals with the corrosion resistance of the treated magnesium alloys (AZ31, AZ61, AZ91 and AZ91 annealed) in the Na[BF4] melt. Corrosion resistance was tested using potentiodynamic tests and tests in the corrosion chamber. In the second part, the mechanism has been studied for preparing fluoride conversion coating, where it was shown that in air-free atmosphere the oxidizing agent in the process is boron, which is reduced from BIII to B0, and thereby enables the fluoride conversion coating.
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Preparation and Characterization of Fluoride Conversion Coatings on Biodegradable Magnesium Alloys
Drábiková, Juliána ; Hadzima, Branislav (referee) ; Brezinová,, Janette (referee) ; Ptáček, Petr (advisor)
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.
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Evaluation of electrochemical characteristics of AZ61 magnesium alloy processed by squeeze casting
Pikner, Jan ; Hadzima, Branislav (referee) ; Fintová, Stanislava (advisor)
Bachelor thesis deals with the characterization of electrochemical corrosion properties of AZ61 magnesium alloy prepared by squeeze casting method. The theoretical part of the work focuses on properties of AZ61 alloy, influence of alloying elements on magnesium alloys and corrosion. The practical part of the work deals with electrochemical characteristics of AZ61 alloy with different surface condition in of 0.1 M NaCl solution. Corrosion potential (Ekor) and corrosion current density (ikor) were determined by potentiodynamic test. Polarisation resistance was determined by electrochemical impedance spectroscopy. Based on the measured results was discussed the influence of production, chemical composition, structure and surface treatment (grinding and polishing) on corrosion characteristics of the alloy.
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Fatigue Behaviour of AZ31 and AZ61 Magnesium Alloys
Gejdoš, Pavel ; Lukáč, Pavel (referee) ; Kohout, Jan (referee) ; Podrábský, Tomáš (advisor)
This doctoral thesis deals with the fatigue behaviour of AZ31 and AZ61 magnesium alloy casted by advanced methods of casting squeeze casting. Based on the regression functions and measured fatigue data were determined fatigue characteristics of these alloys. The work also extends into the area of fatigue cracks in the AZ31 alloy. Were measured fatigue crack propagation rate on modified cylindrical specimens. The paper also outlines the possibilities for describing the fatigue behaviour of AZ61 alloy in extremely low-cycle fatigue.
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Development of WAAM process parameters for thin-walled components made of magnesium alloy AZ61
Šváb, Čeněk ; Němeček, Stanislav (referee) ; Slavíček, Jakub (advisor)
The thesis deals with the development of WAAM (Wire Arc Additive Manufacturing) process parameters for thin-walled parts made of magnesium alloy AZ61. The aim of the thesis is to find suitable process parameters and describe their influences on the welding process. To achieve this goal, these parameters were experimentally tested. It was found that the parameter of boost phase current and the duration of its application have the highest influence on the weld geometry. The stability of the welding process was then influenced by the electrode feed rate during the boost and burn phases. Based on these results, a final set of parameters was created, which successfully welded a thin-walled part composed of 50 layers and reaching a height of 130 mm.
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Preparation and Characterization of Fluoride Conversion Coatings on Biodegradable Magnesium Alloys
Drábiková, Juliána ; Hadzima, Branislav (referee) ; Brezinová,, Janette (referee) ; Ptáček, Petr (advisor)
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.
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Evaluation of electrochemical characteristics of AZ61 magnesium alloy processed by squeeze casting
Pikner, Jan ; Hadzima, Branislav (referee) ; Fintová, Stanislava (advisor)
Bachelor thesis deals with the characterization of electrochemical corrosion properties of AZ61 magnesium alloy prepared by squeeze casting method. The theoretical part of the work focuses on properties of AZ61 alloy, influence of alloying elements on magnesium alloys and corrosion. The practical part of the work deals with electrochemical characteristics of AZ61 alloy with different surface condition in of 0.1 M NaCl solution. Corrosion potential (Ekor) and corrosion current density (ikor) were determined by potentiodynamic test. Polarisation resistance was determined by electrochemical impedance spectroscopy. Based on the measured results was discussed the influence of production, chemical composition, structure and surface treatment (grinding and polishing) on corrosion characteristics of the alloy.
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Ni-P based coatings preparation on wrought magnesium alloys
Buchtík, Martin ; Fintová, Stanislava (referee) ; Wasserbauer, Jaromír (advisor)
The aim of this diploma thesis was summary of all steps and knowledge necessary to deposition of quality Ni-P coatings deposited on wrought magnesium alloys AZ31 and AZ61. There is the treatise about wrought magnesium alloys AZ31 and AZ61. Thesis includes its phase composition in the theoretical part. There are given its possible processing methods too. Next, there is desribed the mechanism of deposition of Ni-P coatings, components required to electroless deposition and factors affecting the quality and properties of these coatings. The theoretical part is ended by serie of reviews. Authors of these reviews deal with pretreatment of substrates, preparation, characterization and measuring of mechanical, structure and corrosion properties of deposited coatings. The optimalization of pretreatment, parametres and composition of nickel bath suitable for magnesium alloys is described in experimental part. The microstructure, present interlayer between substrate and Ni-P coating and chemical composition of deposited coatings was observed and measured by optical and electron microscopy. The mechanical characterization of Ni-P coatings was performed by microhardness tester.
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