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Preparation and characterization of highly hydrophobic coatings on AZ 91 magnesium alloy
Šomanová, Pavlína ; Hasoňová, Michaela (referee) ; Doskočil, Leoš (advisor)
Magnesium and its alloys have many interesting properties and thanks to them it can be used in many applications (transport industry, medicine etc.). Disadvantage of these materials is their high corrosion rate. For this reason, there is an effort to achieve high corrosion resistance through different modifications of magnesium and its alloys. In recent years the superhydrophobization of the surface seem to be an attractive solution for this question. This type surface modification minimalize contact between the surface and water. In this diploma thesis the superhydrophobic surface was created on the magnesium alloy AZ91. The first step included pretreatment of AZ91 surface by etching in solution of SnCl2 or ZnCl2. Next step was superhydrophobization in the ethanolic solution of stearic acid. The surface morphology and elemental analysis of the superhydrophobic coating were explored by use of scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The adhesion properties of the coating on the AZ91 were analysed by means of scratching test. Contact and sliding angles were measured for superhydrophobic coatings. Electrochemical characterization of the coatings was determined using potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS). Finally, the analysis of composition and the functional groups was made using Fourier-transform infrared spectroscopy (FTIR) and the phase composition analysis was performed using X-ray diffraction (XRD). The results show that the coatings prepared by etching did not lead to good corrosion properties, even though the value of contact angle was about 150 °. The reduction of corrosion resistance could be caused by not obtaining required surface morphology or insufficient binding of stearic acid in the form of stearate to the sample surface.
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Determination durability of modular panel elements in different exposures
Škvařil, Michael ; Žák, Antonín (referee) ; Vaněrek, Jan (advisor)
Within the theoretical part of the diploma thesis, a list of the main types of accelerated tests designed for the resistance of metal and polymer surface finishes. In the experimental part of diploma thesis, the rate of biological resistance of wood-based board materials is evaluated. Furthermore, the resistance of coating systems is assessed by means of accelerated tests. Resistance of modular building shells is primarily focused on degradation of coatings applied primarily on metal materials and wood materials. The tested coating systems analyze the influence of the materials and chemical base on the final weather resistance.
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Preparation and characterization of highly hydrophobic coatings on AZ 91 magnesium alloy
Šomanová, Pavlína ; Hasoňová, Michaela (referee) ; Doskočil, Leoš (advisor)
Magnesium and its alloys have many interesting properties and thanks to them it can be used in many applications (transport industry, medicine etc.). Disadvantage of these materials is their high corrosion rate. For this reason, there is an effort to achieve high corrosion resistance through different modifications of magnesium and its alloys. In recent years the superhydrophobization of the surface seem to be an attractive solution for this question. This type surface modification minimalize contact between the surface and water. In this diploma thesis the superhydrophobic surface was created on the magnesium alloy AZ91. The first step included pretreatment of AZ91 surface by etching in solution of SnCl2 or ZnCl2. Next step was superhydrophobization in the ethanolic solution of stearic acid. The surface morphology and elemental analysis of the superhydrophobic coating were explored by use of scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The adhesion properties of the coating on the AZ91 were analysed by means of scratching test. Contact and sliding angles were measured for superhydrophobic coatings. Electrochemical characterization of the coatings was determined using potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS). Finally, the analysis of composition and the functional groups was made using Fourier-transform infrared spectroscopy (FTIR) and the phase composition analysis was performed using X-ray diffraction (XRD). The results show that the coatings prepared by etching did not lead to good corrosion properties, even though the value of contact angle was about 150 °. The reduction of corrosion resistance could be caused by not obtaining required surface morphology or insufficient binding of stearic acid in the form of stearate to the sample surface.
|
|
|
Determination durability of modular panel elements in different exposures
Škvařil, Michael ; Žák, Antonín (referee) ; Vaněrek, Jan (advisor)
Within the theoretical part of the diploma thesis, a list of the main types of accelerated tests designed for the resistance of metal and polymer surface finishes. In the experimental part of diploma thesis, the rate of biological resistance of wood-based board materials is evaluated. Furthermore, the resistance of coating systems is assessed by means of accelerated tests. Resistance of modular building shells is primarily focused on degradation of coatings applied primarily on metal materials and wood materials. The tested coating systems analyze the influence of the materials and chemical base on the final weather resistance.
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