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P. Bazarnik, M. Lewandowska and K.J. Kurzydłowski

The subject of the study were microstructure and mechanical properties of two commercial 5xxx aluminium alloys obtained by Plastic Consolidation (PC) of nanopowders and Hydrostatic extrusion (HE). It has been observed that HE samples exhibit a higher strength whereas PC samples higher ductility. The two types of samples also differ in the type and intensity of serrations on stress-strain curves. The microstructures of samples processed were found to differ significantly in terms of size and shape of grains, grain boundary characteristics, second phase particles content and density of dislocations. The results are discussed in terms of the influence of microstructure on mechanical behaviour of 5xxx aluminium alloys processed by severe plastic deformation.

Open access

K. Wawer, M. Lewandowska and K.J. Kurzydłowski

In the present study, severe plastic deformation (SPD) processing was combined with pre- and post processing heat treatment to investigate the possibility of synergic grain size and precipitation strengthening. Samples of 7475 alloy were solution heat treated and water quenched prior to hydrostatic extrusion (HE) which resulted in a grain refinement by 3 orders of magnitude, from 70 μm to about 70 nm. The extruded samples were subsequently aged at temperatures resulting in formation of nanoprecipitates.

Open access

A. Roguska, A. Belcarz, P. Suchecki, M. Andrzejczuk and M. Lewandowska

Problem of Post-operative infections of implant materials caused by bacterial adhesion to their surfaces is very serious. Enhancement of antibacterial properties is potentially beneficial for biomaterials value. Therefore, the metallic and metallic oxide nanoparticles attract particular attention as antimicrobial factors. The aim of this work was to create nanotubular (NT) oxide layers on Ti with the addition of ZnO nanoparticles, designed for antibacterial biomedical coatings. Antimicrobial activities of titanium, TiO2 NT and ZnO/TiO2 NT surfaces were evaluated against bacterial strain typical for orthopaedic infections: S. epidermidis. TiO2 NT alone killed the free bacterial cells significantly but promoted their adhesion to the surfaces. The presence of moderate amount of ZnO nanoparticles significantly reduced the S. epidermidis cells adhesion and viability of bacterial cells in contact with modified surfaces. However, higher amount of loaded nanoZnO showed the reduced antimicrobial properties than the medium amount, suggesting the overdose effect.

Open access

M. Kulczyk, J. Skiba, S. Przybysz, W. Pachla, P. Bazarnik and M. Lewandowska

C65500 is a high strength engineering alloy that has excellent resistance to a wide range of corrosive environments. Combination of corrosion resistance, strength, and formability place it among the most widely used copper alloys. In the present study, a C65500 alloy was subjected to severe plastic deformation by hydrostatic extrusion at room temperature with goal to increase its strength by grain refinement without modification of the chemical composition. Cumulative hydrostatic extrusion was applied with a total true strain of 4.1. The microstructure of SPD samples was evaluated by transmission electron microscopy. The size of grains was quantitatively described. The resulting mechanical properties were determined in tensile tests and via microhardness measurements. The results show that the applied cumulative HE route, leads to a substantial grain size refinement accompanied by high increase in strength. In comparison to commercial alloy after conventional plastic treatment, ultimate tensile strength and yield strength were higher by 45% and 130% respectively.

Open access

A. Roguska, A. Belcarz, P. Suchecki, M. Andrzejczuk and M. Lewandowska

Abstract

Problem of post-operative infections of implant materials caused by bacterial adhesion to their surfaces is very serious. Enhancement of antibacterial properties is potentially beneficial for biomaterials value. Therefore, the metallic and metallic oxide nanoparticles attract particular attention as antimicrobial factors. The aim of this work was to create nanotubular (NT) oxide layers on Ti with the addition of ZnO nanoparticles, designed for antibacterial biomedical coatings. Antimicrobial activities of titanium, TiO2 NT and ZnO/TiO2 NT surfaces were evaluated against bacterial strain typical for orthopaedic infections: S. epidermidis. TiO2 NT alone killed the free bacterial cells significantly but promoted their adhesion to the surfaces. The presence of moderate amount of ZnO nanoparticles significantly reduced the S. epidermidis cells adhesion and viability of bacterial cells in contact with modified surfaces. However, higher amount of loaded nanoZnO showed the reduced antimicrobial properties than the medium amount, suggesting the overdose effect.

Open access

M. Andrzejczuk, O. Vasylyev, M. Brychevskyi, L. Dubykivskyi, A. Smirnova, M. Lewandowska, K. Kurzydłowski, R. Steinberger-Wilckens, J. Mertens and V. Haanappel

Abstract

The structure of Ceria doped Scandia Stabilized Zirconia (1Ce10ScSZ) electrolyte film deposited by EB-PVD (Electron Beam-Physical Vapour Deposition) technique on NiO-ZrO2 substrate was characterized by electron microscopy. The highly porous substrate was densely covered by deposited film without any spallation. The produced electrolyte layer was of a columnar structure with bushes, bundles of a diameter up to 30 μm and diverse height. Between the columns, delamination cracks of few microns length were visible. The annealing of zirconia film at 1000 °C resulted in its densification. The columnar grains and delaminating cracks changed their shape into a bit rounded. High magnification studies revealed nanopores 5–60 nm formed along the boundaries of the columnar grains during annealing. High-quality contacts between the electrolyte film and anode substrate ensured good conductivity of the electrolyte film and high efficiency of SOFC.