|
| |
|
|
Deformation Behaviour of Advenced Magnesium and Aluminium Alloys
Jäger, Aleš
Aluminum and magnesium alloys are often considered as promising materials due to high strength/density ratio. In general, light alloys are very attractive structural materials for applications where environmental protection or weight reduction play essential role. Therefore, it is of interest to investigate microstrucrure and its changes during plastic deformation because it helps to understand the nature of solute effect and processes taking place during plastic deformation. The aim of this work is to reveal microstructures, deformation characteristics and micromechanisms of plastic deformation at different strain rates and temperatures in selected light alloys. Two commercially available alloys were used in this work: AZ31 rolled magnesium alloy and AA6082 extruded aluminium alloy. These alloys were studied with the help of various experimental techniques such as tensile testing, light microscopy, electron backscatter diffraction (EBSD) and X-ray diffraction. Abstrakt Hlinikove a horcikove slitiny jsou povazovany za vysoce perspektivni materialy, protoze nabizeji velmi dobry pomer pevnosti k hustote. Tyto lehke slitiny nalezaji uplatneni pfedevsim v aplikacich, kde je kladen duraz na ochranu zivotniho prostredi a nebo snizeni hmotnosti. Detailni studium jejich mikrostruktury a deformacniho...
|
|
|
Aliphatic polyester-based nanoparticles as drug delivery systems
Jäger, Alessandro ; Štěpánek, Petr (advisor) ; Sedláček, Jan (referee) ; Sikora, Antonín (referee)
Nanoparticles from biodegradable polymers are considered one of the most promising systems for biomedical application as drug delivery systems. Therefore, the synthesis and characterization of a new aliphatic biodegradable copolyester named PBS/PBDL (poly(butylene succinate-co- butylene dilinoleate)) intended to the application as drug delivery system is reported in the thesis. Surfactant-free biodegradable and narrowly distributed, nanosized spherical particles (RH < 60 nm) have been produced from the biodegradable material by applying a single-step nanoprecipitation protocol. The size of the generated polymer nanoparticles (PNPs) could be controlled by adjusting the polymer concentration, the choice of organic solvent, mixing different organic solvents or by changing temperature and ionic strength. By optimizing such parameters sub-100 nm uniform PNPs can be produced through this methodology including the advantage and ability to scale-up production. The nanoparticles structure was characterized in detail by employing a variety of scattering techniques and transmission electron microscopy (TEM). Combined static light scattering (SLS) and dynamic light scattering (DLS) measurements suggested that the nanoparticles comprise a porous core conferring them a non-compact characteristic. Their porosity...
|
|
| |
|
|
Deformation Behaviour of Advenced Magnesium and Aluminium Alloys
Jäger, Aleš
Aluminum and magnesium alloys are often considered as promising materials due to high strength/density ratio. In general, light alloys are very attractive structural materials for applications where environmental protection or weight reduction play essential role. Therefore, it is of interest to investigate microstrucrure and its changes during plastic deformation because it helps to understand the nature of solute effect and processes taking place during plastic deformation. The aim of this work is to reveal microstructures, deformation characteristics and micromechanisms of plastic deformation at different strain rates and temperatures in selected light alloys. Two commercially available alloys were used in this work: AZ31 rolled magnesium alloy and AA6082 extruded aluminium alloy. These alloys were studied with the help of various experimental techniques such as tensile testing, light microscopy, electron backscatter diffraction (EBSD) and X-ray diffraction. Abstrakt Hlinikove a horcikove slitiny jsou povazovany za vysoce perspektivni materialy, protoze nabizeji velmi dobry pomer pevnosti k hustote. Tyto lehke slitiny nalezaji uplatneni pfedevsim v aplikacich, kde je kladen duraz na ochranu zivotniho prostredi a nebo snizeni hmotnosti. Detailni studium jejich mikrostruktury a deformacniho...
|
|
|
Temperature and pressure correlation for volume of gas hydrates with crystal structures sI and sII.
Vinš, Václav ; Jäger, A. ; Hielscher, S. ; Span, R. ; Hrubý, Jan ; Breitkopf, C.
The temperature and pressure correlations for the volume of gas hydrates forming crystal structures sI and sII developed in previous study [Fluid Phase Equilib. 427 (2016) 268], focused on the modeling of pure gas hydrates relevant in CCS, were revised and modified for the modeling of mixed hydrates in this study. A universal reference state at temperature of 273.15 K and pressure of 1 Pa is used in the new correlation. Coefficients for the thermal expansion together with the reference lattice parameter were simultaneously correlated to both the temperature data and the pressure data for the lattice parameter. The new correlation is in good agreement with the experimental data over wide temperature and pressure ranges from 0 K to 293 K and from 0 to 2000 MPa, respectively. The new correlation provides significantly better agreement with the experimental data for sI hydrates compared to the original correlation. The results of both correlations are comparable in case of sII hydrates.
|
|
| |
|
| |
|
|
Phase equilibria of carbon dioxide and methane gas-hydrates predicted with the modified analytical S-L-V equation of state
Vinš, Václav ; Jäger, A. ; Hrubý, Jan ; Span, R.
Gas-hydrates (clathrates) are non-stoichiometric crystallized solutions of gas molecules in the metastable water lattice. Two or more components are associated without ordinary chemical union but through complete enclosure of gas molecules in a framework of water molecules linked together by hydrogen bonds. The clathrates are important in the following applications: the pipeline blockage in natural gas industry, potential energy source in the form of natural hydrates present in ocean bottom, and the CO2 separation and storage. In this study, we have modified an analytical solid-liquid-vapor equation of state (EoS) [A. Yokozeki, Fluid Phase Equil. 222–223 (2004)] to improve its ability for modeling the phase equilibria of clathrates. The EoS can predict the formation conditions for CO2- and CH4-hydrates. It will be used as an initial estimate for a more complicated hydrate model based on the fundamental EoSs for fluid phases.
|
|
| |
guest ::
RSS feed.