National Repository of Grey Literature 17 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
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.
Complete characterization of the ceramic-based hot-coated coating on the AZ91 magnesium alloy
Plevová, Kateřina ; Doskočil, Leoš (referee) ; Wasserbauer, Jaromír (advisor)
The diploma thesis is focused on the study of the thermal sprayed coating consisting of the NiCrAlY alloy bond layer and the partially stabilized zirconium oxide (8YSZ) top layer on the AZ91 magnesium alloy. The theoretical part deals with the structure of the alloy AZ91, NiCrAlY and partially stabilized zirconia. Furthermore, the methods of thermal spraying and the function and properties of thermal barrier coatings are summarized. The experimental part deals with the characterization of the thermal sprayed coating and the AZ91 alloy in terms of elemental, structural and phase composition. Optical and electron microscopy, EDS and XRD analysis were used for characterization. Electrochemical properties were investigated in~3.5% sodium chloride solution by potentiodynamic polarization. The mechanical properties (hardness, coefficient of friction) of the substrate and coating were measured using a hardness tester and tribological tests.
Comparison of methods for measuring the thickness of layers on complex and multi-layered parts
Koller, Kryštof ; Buchtík, Martin (referee) ; Wasserbauer, Jaromír (advisor)
This thesis deals with methods for measuring the thickness of metal layers on polymeric, complex and multi-layered parts. Research includes finding the optimal method while considering the time limitation, preciseness and practicality of the method for industrial use.
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.
Preparation and characterization of Ni-P coating on AZ91 cast magnesium alloy
Brescher, Roman ; Buchtík, Martin (referee) ; Wasserbauer, Jaromír (advisor)
This bachelor thesis deals with electroless deposition of nickel-phosphoric (Ni-P) coating on AZ91 magnesium alloy. At the beginning of the theoretical part, there is a summary of basic knowledge about magnesium alloys with focus on AZ91 alloy and the influence of alloying elements and impurities and its microstructure. The theoretical part continues with the discussion of the Ni-P coating, focusing on the composition of the bath, the influence and the effect of its individual components. Next, there is a comparison with galvanic nickeling. At the end of the theoretical part, the current research of the use of electroless deposition of Ni-P layer on AZ91 magnesium alloy is summarized. In the practical part, there is the preparation of the Ni-P coating on the AZ91 magnesium alloy, the observation the microstructure of the magnesium alloy and the Ni-P layer, and rate of deposition, the thickness, the microhardness and the composition of the coating was measured. The effect of its heat treatment was also observed. It has been found that it is possible to produce a high-quality Ni-P coating on an AZ91 magnesium alloy which has no visible defects or obvious undesirable interlayers, however the heat treatment of the coating causes its cracking. To determine the corrosion resistance, a potentiodynamic measurement was performed, resulting in the finding that the Ni-P coating without heat treatment was a suitable corrosion protection. However, after heat treatment, the corrosion resistance due to cracking of the surface deteriorated to a level of bare AZ91 alloy.
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.
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.
Surface pre-treatment of structural aluminum alloys for bonded joints
Pikner, Jan ; Doskočil, Leoš (referee) ; Wasserbauer, Jaromír (advisor)
This thesis deals with pre-treatment of surface of aluminium alloys. The theoretical part focuses on the properties of aluminium and its alloys, on methods of surface treatment and the possibilities of quality assessment of pre-treated surface. The experimental part deals with finding of a proper method of pre-treatment. The quality of surface pre-treatment is assessed by observation by SEM with EDS and by single lap shear tests of adhesive joints. According to evaluated results, the optimalised methods are qualitatively and financially compared with the commercial method.
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.
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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