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National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Preparation of layered double hydroxides on Mg-hydroxyapatite-based substrates
 Knoflíček, Milan ; Doskočil, Leoš (referee) ; Buchtík, Martin (advisor)
The aim of this bachelor thesis was the preparation and characterization of coatings based on layered double hydroxides (LDH) on Mg composite substrates prepared by powder metalurgy. Hydroxyapatite (HAp) was used as a filler. The deposition of MgAl-LDH coatings on the surface of composites was carried out in a reaction mixture containing Al(NO3)3 at pH 10 and a temperature of 95 °C. The morphology and structure of the samples were characterized using scanning electron microscopy (SEM). The elemental composition of both composites themselves and the prepared coatings were characterized by energy dispersive spectroscopy (EDS). Analysis of the structure of Mg-HAp composites revealed that the frequency of HAp agglomerates increased with increasing reinforcement concentration. The highest frequency of agglomerates was detected in samples containing 20 and 50 wt. % HAp filler, where unlike the other samples, a significant deterioration of corrosion properties was also observed. In contrast, the best corrosion resistance was shown by the sample with 1 wt. % of filler. Other samples with filler contents from 0 to 10 wt. % were relatively similar in terms of corrosion resistance. Potentiodynamic tests demonstrated that coated samples exhibited significantly higher corrosion resistance compared to the uncoated samples. A uniform layer of LDH was observed in the coated samples with HAp content up to and including 10 wt. %. The presence of cracks related to the presence of bulky HAp agglomerates was detected on samples with higher reinforcement content, i.e. 20 and 50 wt. % HAp. Lower coating adhesion was also observed at these locations. It was found that to achieve high quality of LDH coatings, the optimum amount of HAp reinforcement of mixed and subsequently pressed Mg-HAp composites is up to 5 wt. % HAp. Higher HAp content in the samples generally led to the formation of defects and deterioration of corrosion properties.
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Užití kalcinovaných LDH jako katalyzátorů pro odstranění emisí N2O
 Obalová, L. ; Kovanda, F. ; Jirátová, Květa ; Pacultová, K. ; Lacný, Z.
Mixed oxide catalysts were prepared by calcination of LDH containing as divalent ions Ni, Co, Cu and /or Mg and as trivalent ions Mn, Fe and/or Al. The highest conversion was reached over Ni-Al and Co-Mn-Al mixed oxides. N2O conversion decreased slightly with the presence of NO2 over Co-Mn-Al catalyst, but strongly over Ni-Al catalyst. Water vapor inhibited the N2O decomposition over all tested catalysts.
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