Papers by Author: Łukasz Zych

Abstract: Magnesium-aluminium spinel (MgAl₂O₄) in the form of transparent ceramics is applied in shields of infrared detectors or emitters, high-temperature widows and elements of military aircrafts and vehicles. Apart from high transparency for specific wave lengths, such materials should have good mechanical properties, especially hardness. It is the reason for production of the fine-grained materials. It seems that they can be produced from submicron powders consolidated by one of colloidal techniques. The work presents preliminary results of investigations on colloidal consolidation of two fine spinel powders with different particle size by pressure filtration and slip casting. The aim of the studies was consolidation of the fine powders leading to green samples with narrow pore size distribution. The samples were then sintered in isothermal conditions. Microstructure, Vickers hardness and transmission in infrared spectrum of the dense materials were examined.

Abstract: Aim of the work was production of nanocomposite polymer fibres containing ceramic particles using the electrospinning method and characterisation of morphology and bioactivity of the produced materials. The first stage of investigations consisted in preparation of a series of poly-L-lactide (PLA) solutions in various solvents mixtures in order to reach viscosity which would allow formation of fibres by the electrospinning method. Ceramic nanoparticles such as tricalcium phosphate (TCP) and silica (SiO₂) were used as nanofillers of the polymer matrix. Their particle size distribution in the solvent solution as well as in the polymer suspension was determined by dynamic light scattering method (DLS). Morphology of the nanoparticles was observed using transmission electron microscopy (TEM). Distribution of the nanofillers in the nanocomposite fibres as well as diameter and morphology of the fibres was assessed using scanning electron microscopy with energy dispersive spectroscopy method (SEM/EDS). Effect of the nanofillers addition and the shaping method on the structure of the PLA matrix was investigated on the basis of the thermal analysis methods (TG/DSC) on the nanocomposite foils prepared by casting. It was revealed that the nanocomposite fibres showed apatite nucleation in in vitro conditions i.e. after incubation in SBF (37°C/ 3 days).

Abstract: The aim of this work was the investigation of microstructure evolution during sintering of zirconia nanopowder. The powder containing 97 mol. % ZrO2 and 3 mol. %Y2O3, with particle size about 8 nm was prepared by the hydrothermal method. The flocculated and dispersed water suspensions of the powder were filter pressed under 5 MPa, which led to green bodies of relative density about 40%. Samples prepared from the suspensions showed distinct differences in densification behaviour. The observation of the microstructure evolution (i.e. density, fracture surface) in samples heat-treated at different temperatures, and detailed analysis of open porosity evolution were performed.