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Study of phytic acid-based organic conversion coatings on magnesium alloys
Zbíral, Roman ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
This thesis deals with organic conversion coatings based on phytic acid, on the magnesium alloys. In theoretical part it deals with corrosion properties of magnesium and magnesium alloys, usage of magnesium alloys for biomedicine applications. There are also summarized information’s about usage of phytic acid, it’s reactions with magnesium and magnesium alloys. At the end of theoretical part is search about phytic acid conversion coatings deposited on magnesium alloys. There are studied optimal conditions for application of phytic acid coatings such as pH, concentration, time of deposition, etc. Based on the knowledge from the theoretical part, a layer based on phytic acid was deposited on the surface of Mg alloy AZ31. The coating was evaluated in the experimental part in terms of its morphology and structure, chemical and corrosion behaviour. Scanning electron microscope (SEM) images showed the presence of microcracks in the dried coating. The chemical nature of the phytic acid-based conversion coating was investigated by energy dispersive spectroscopy (EDS) techniques in combination with Fourier transform infrared spectroscopy (FTIR). The electrochemical corrosion behaviour of Mg alloy AZ31 and coated Mg alloy was investigated by potentiodynamic polarization in Hank's solutions. Based on the obtained values of the corrosion potential and the corrosion current density, it can be stated that the applied layer of the conversion coating leads to an improvement of the corrosion properties. From the results of SEM analysis of samples after exposure in a corrosive environment, it was found that during potentiodynamic measurements no significant manifestation of corrosion attack was observed in coated samples, as was the case with Mg alloy AZ31.
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Study of phytic acid-based organic conversion coatings on magnesium alloys
Zbíral, Roman ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
This thesis deals with organic conversion coatings based on phytic acid, on the magnesium alloys. In theoretical part it deals with corrosion properties of magnesium and magnesium alloys, usage of magnesium alloys for biomedicine applications. There are also summarized information’s about usage of phytic acid, it’s reactions with magnesium and magnesium alloys. At the end of theoretical part is search about phytic acid conversion coatings deposited on magnesium alloys. There are studied optimal conditions for application of phytic acid coatings such as pH, concentration, time of deposition, etc. Based on the knowledge from the theoretical part, a layer based on phytic acid was deposited on the surface of Mg alloy AZ31. The coating was evaluated in the experimental part in terms of its morphology and structure, chemical and corrosion behaviour. Scanning electron microscope (SEM) images showed the presence of microcracks in the dried coating. The chemical nature of the phytic acid-based conversion coating was investigated by energy dispersive spectroscopy (EDS) techniques in combination with Fourier transform infrared spectroscopy (FTIR). The electrochemical corrosion behaviour of Mg alloy AZ31 and coated Mg alloy was investigated by potentiodynamic polarization in Hank's solutions. Based on the obtained values of the corrosion potential and the corrosion current density, it can be stated that the applied layer of the conversion coating leads to an improvement of the corrosion properties. From the results of SEM analysis of samples after exposure in a corrosive environment, it was found that during potentiodynamic measurements no significant manifestation of corrosion attack was observed in coated samples, as was the case with Mg alloy AZ31.
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Determination of phytic acid in brewery materials
Strnadová, Barbora ; Hégrová, Blanka (referee) ; Vespalcová, Milena (advisor)
This diploma work discusses the chemical and physical characteristics of phytic acid, its positive and negative influence on people’s health, on the substances usability in the human organism and also its possible use in the food industry. Methods for analyzing phytic acid in the feed and food industry are also discussed. This diploma work also states the characteristics of analyzed raw materials and, for the analyzed raw material malt, it also covers the technological procedure for its production. For direct determination of phytic acid in barley caryopses and in malt, the isotachophoresis (ITP) method was used. This diploma work contains results of phytic acid determination in treated and untreated barley and malt variants by 6 different varieties in 4 test stations - specifically for harvests during the years 2006 and 2007. The final work contains comparisons of phytic acid content in different varieties of treated/untreated barley and malt variants. Comparisons are always within a single test station. Comparison are also included of phytic acid content for single varieties (across all examined test stations). This work furthermore, presents decreases in phytic acid content after malting. The ITP method was evaluated as quick and relatively simple. A method by using tests (from a commercial company) for obtaining phytic acid content was also used. This diploma work lists results of phytic acid content determination in untreated barley and malt variants at two test stations, for the year of harvest 2007. Further, this work contains a comparison of phytic acid content in different varieties for the given test station. The method by using tests was evaluated as a orientation method. This work states comparisons of phytic acid content obtained by measurements during the years 2006 and 2007. The diploma work also compares ITP with the method realized by using tests in two test stations for 5 untreated varieties of barley and malt for 2007 harvest.
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