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Characterization of corrosion resistance of nickel-phosphorus coatings on magnesium alloys
Kotland, Vojtěch ; Březina, Matěj (referee) ; Wasserbauer, Jaromír (advisor)
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.
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Nickel coatings and their properties
Buchtík, Martin ; Tkacz, Jakub (referee) ; Zmrzlý, Martin (advisor)
The aim of the bachelor’s thesis was summary of existing knowledge concerning to electroless deposition of nickel coatings and their properties. In the theoretical part there are two chapters. In the first chapter present knowledge of chemical nickel plating is described in details. It also discuss mechanisms of this type of coating and individual components of nickel plating bath. In the second chapter there is summarized knowledge of composite coatings deposition and description of their mechanical properties. The experimental part deals with deposition of composite coatings on steel substrates and heat treatment of Ni-P coatings. Dependence of microhardness on temperature of heat treatment was studied and then there is also described dependence of microhardness on duration of heat treatment. Deposited coatings, their morphology and composition were studied using scanning electron microscope and EDS analysis. The values of microhardness of both types of coatings were measured and compared using microhardness tester.
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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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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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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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Complete characterization and comparison of lacquer / Ni-P / AZ91 and lacquer / AZ91 systems
Šomanová, Pavlína ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
The aim of this bachelor thesis was to compare the influence of Ni-P coating and varnish on the corrosion properties and chemical – physical properties (adhesion) of the magnesium alloy AZ91. The theoretical part contains the information about the alloy AZ91 itself and its microstructure, following by discussion about Ni-P coating, its properties, the process of the electroless deposition and composition it the nickel bath. Next chapter focuses on information about varnishes, its function and the process of its application on the surface of the substrate. Theoretical part closes with the summary of current research in the field of Ni-P coatings applied on magnesium alloys. The experimental part focuses on analysis of the microstructure of AZ91 alloy. The microstructure of the Ni-P coating and of the system Mg alloy/Ni-P coating/varnish was 4 examined by scanning electron microscope (SEM) and inverted microscope. During the next phase was thickness and hardness measured and composition measured by EDS analysis. The factor of the heat treatment of the samples and its impact on the final microstructure, hardness and corrosion resistance was taken in account. Finally, several samples were modified with the layer of the varnish and its thickness and the influence on the corrosion resistance ware measured. Samples were tested with electromechanical impedance spectroscopy (EIS), the corossion resistance were tested by neutral salt spray (NSS) and adhesive test was performed. The results showed, that Ni-P coating and the layer of varnish had positive impact on the corrosion resistance and the hardness of AZ91. The corrosion resistance of the samples modified with heat treatment was much lower, because of the contracting, which causes creation of the cracks. Also, the layer of varnish had positive effect on anticorrosion properties of tested AZ91 alloy.
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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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Complete characterization and comparison of lacquer / Ni-P / AZ91 and lacquer / AZ91 systems
Šomanová, Pavlína ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
The aim of this bachelor thesis was to compare the influence of Ni-P coating and varnish on the corrosion properties and chemical – physical properties (adhesion) of the magnesium alloy AZ91. The theoretical part contains the information about the alloy AZ91 itself and its microstructure, following by discussion about Ni-P coating, its properties, the process of the electroless deposition and composition it the nickel bath. Next chapter focuses on information about varnishes, its function and the process of its application on the surface of the substrate. Theoretical part closes with the summary of current research in the field of Ni-P coatings applied on magnesium alloys. The experimental part focuses on analysis of the microstructure of AZ91 alloy. The microstructure of the Ni-P coating and of the system Mg alloy/Ni-P coating/varnish was 4 examined by scanning electron microscope (SEM) and inverted microscope. During the next phase was thickness and hardness measured and composition measured by EDS analysis. The factor of the heat treatment of the samples and its impact on the final microstructure, hardness and corrosion resistance was taken in account. Finally, several samples were modified with the layer of the varnish and its thickness and the influence on the corrosion resistance ware measured. Samples were tested with electromechanical impedance spectroscopy (EIS), the corossion resistance were tested by neutral salt spray (NSS) and adhesive test was performed. The results showed, that Ni-P coating and the layer of varnish had positive impact on the corrosion resistance and the hardness of AZ91. The corrosion resistance of the samples modified with heat treatment was much lower, because of the contracting, which causes creation of the cracks. Also, the layer of varnish had positive effect on anticorrosion properties of tested AZ91 alloy.
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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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