|
|
Structure and mechanical properties of magnesium materials prepared by SPS
Pleskalová, Kateřina ; Hutařová, Simona (referee) ; Doležal, Pavel (advisor)
This diploma thesis deals with the processing of the magnesium-based powder materials with the addition of zinc by the spark plasma sintering. The aim of this thesis is to evaluate influence of sintering parameters and zinc content on the microstructure and mechanical properties of the material. First part of the thesis is literary research which is divided into two main chapters. The first chapter describes magnesium-based materials and mentions their use as biomaterials. The second chapter discusses powder metallurgy, specifically magnesium powders and spark plasma sintering. In the experimental part the powders were sintered at temperatures 300 °C and 400 °C and an analysis was performed using optical microscope, scanning electron microscope, then also EDS analysis and hardness, microhardness and three-point bending tests were performed. An increase in hardness was observed with increasing zinc content and with increasing sintering temperature. The flexural strength was higher for materials sintered at a temperature of 400 ° C.
|
|
| |
|
|
Sorption of metal ions mixture on natural lignite
Doskočil, Leoš ; Taraba, Boleslav (referee) ; Pekař, Miloslav (advisor)
Sorption of quaternary metal ions (Pb2+, Cu2+, Cd2+ and Zn2+) was carried out on lignite from the South Moravia. Following experiments were tested: kinetic sorption, dependence of sorption on pH, initial concentration, temperature, effect of electrolytes (KNO3 and NaCl) and desorption in deionized water. Sorption studies was carried out in quaternary mixtures and in the case of inicial concentration effect additional in a single-component solution. The batch sorption experiments was used. Sorption time was 24 hour, although concentration of ions was a near equilibrium after two hour. As the optimal pH was determined pH 5. The order of affinity by lignite was obtained Pb >> Cd > Zn > Cu for the sorption of metals in the single-component solution and the order was Pb > Cu > Zn > Cd for the sorption of mixture of metals. The maximum adsorptium capacities from single solutions were for Pb 97,82 mg/g, Cd 60,34 mg/g, Zn 49,88 mg/g and Cu 30,28 mg/g and in the case of ones from mixture solutions were for Pb 39,03 mg/g, Cu 25,94 mg/g, Zn 15,21 mg/g and Cd 5,18 mg/g. Experimental data have been analysed using Langmuir and Freundlich model. Thermodynamic values H°, S° and G° were calculated. Desorption test showed that desorption efficiency is 0–3 %. NaCl had the greatest influence on sorption from electrolytes. On the basis obtained results we can say that metals are binding to lignite in particular due to chemical interactions. Lignite is s suitable as a sorption material for metal ions especially in the field of low concentrations.
|
|
|
Application of voltammetry for simultaneous determination of selected microelements
Bruštík, David ; Komendová, Renata (referee) ; Řezáčová, Veronika (advisor)
This bachelor thesis concentrates on the optimization of conditions for voltammetric determination of selected microelements, specifically zinc, copper, cadmium and lead. The theoretical part describes the individual properties of selected elements and their toxicity, occurrence and important figures of concentration. The practicable methods suitable for the determination of these microelements are summarized and the voltammetric analysis is described in depth. The experimental section deals with the optimization of dissolution voltammetry conditions, the description of the method used and the analysis of selected real samples.
|
|
|
Production and use of zinc alloy castings
Odehnal, Pavel ; Müller, Peter (referee) ; Pernica, Vítězslav (advisor)
The bachelor thesis focuses on the development of a literature search dealing with zinc production and its applications. The theoretical part is focused on the methods of production of pure zinc, the alloys used and the methods of processing of these alloys. Furthermore, selected branches of application of castings in industry are described. The work is supplemented by an experiment concerning the evaluation and remedy of defects occurring on the component.
|
|
|
Preparation processes and characterization of bulk material from Mg and Zn powders
Hasoňová, Michaela ; Pacal, Bohumil (referee) ; Doležal, Pavel (advisor)
Topic of the diploma thesis is Mg-Zn bulk material preparation process by powder mixtures sintering at hot pressing. Structure, porosity and physically-mechanical properties of prepared bulk materials was evaluated. Obtained results and their interpretation were served as feedback for following optimization of individual processing parameters of bulk materials preparation. Thesis solving focuses on study and control of processes during bulk material preparation and description of the processes from physically-chemical point of view of the structure creation and final material properties.
|
|
|
Biodegradable bones implants based on iron
Hrabovský, Jan ; Zatloukal, Miroslav (referee) ; Sedlaříková, Marie (advisor)
This work deals with a current topic, which are biodegradable bone implants. These implants seem to be a suitable candidate for temporary fixations, with their gradual decomposition. An important parameter is not only the mechanical properties so that the material can withstand the load, but above all the corrosion properties and the degradation process. This work introduces the physiology of bone, trace elements and also describes current trends in the field of implants. The last part is a theoretical introduction to cross-stage processes. The practical part is focused on the preparation of iron-based samples with various dopants, subsequent annealing and analysis.
|
|
|
Presence of heavy metals near the way Rudná
Chovanec, Petr ; Pavlovský, Jiří (referee) ; Doležalová Weissmannová, Helena (advisor)
These diploma thesis is focused on assessment of hazardous metals in soils near the road Rudná in Ostrava. Seventeen sampling sites have been chosen along this road, samples from this sites were collected in three series. The amounts of mercury, lead, copper, cadmium, zinc, vanadium and manganese were determined. There was also assessed contamination of selected sites using contamination factor and degree of contamination.
|
|
|
Corrosion protection by means of plasma spraying coatings
Bartoněk, Daniel ; Řehořek, Lukáš (referee) ; Jan, Vít (advisor)
This thesis is focused on making study of technologies used for applying metal coatings as corrosion protection and commonly used materials. By means of metalographic analysis compare microstructures of coatings thermal spraying by zinc based alloys. The thesis is describing basics of corrosion, means of corrosion protection and methods used for making zinc coatings for corrosion protection. Experimental part is comparing coatings made by thermal plasma spraying and thermal spraying with use of electric current.
|
|
|
Study of the content of risk elements in soils and plant material
Vlčková, Renáta ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
This bachelor thesis deals with the study of the content of selected heavy metals (Zn, Ni, Fe, Mn) in soils and mushrooms. The flame atomic absorption spectrometry method was used to determine the heavy metal content. Fungi and soil samples were collected at 18 sites in the Jeseníky region. The concentrations of heavy metals in the mushrooms were in the range from 140–582 mg/kg Zn, 48–380 mg/kg Fe, 5–19 mg/kg Mn and 3–8 mg/kg Ni. Zinc had the highest concentration value in all mushroom species. In soils, the concentrations of heavy metals ranged from 10–72 g/kg Fe, 52–1,000 mg/kg Mn, 29–115 mg/kg Zn and 6–50 mg/kg Ni. Iron was the most abundant element in the soils. Mushrooms contamination was assessed as a health risk in the study area. However, the pollution of forest soils was assessed as satisfactory and thus the productive function of the soil is not impaired. The type of forest cover was found to have minimal effect on the chemical composition of the soils.
|
guest ::
