Wyniki 1-5 spośród 5 dla zapytania: authorDesc:"JUERGEN M. LACKNER"

Multiscaled analysis of wear mechanism of titanium and carbon basis multilayer coatings

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Coatings are more and more frequently used to protect surface of mechanical parts exposed to wear loads. The ceramic hard coatings like TiN are of special interest due to their corrosion resistance and high hardness [1, 2]. The other suggested material for wear resistant coatings is amorphous carbon. The diamond like carbon coatings (DLC or a-C:H) are characterized by very low friction coefficient and biological inertness [3]. There is a tendency to connect the properties of different type of materials in multilayered composition [4, 5]. The TiN/Ti/a-C:H multilayer coatings might be applied for pump parts supporting, namely, artificial heart systems. The detailed microstructure description of wear mechanisms in coatings, particularly in multilayer systems are lacking. To enhance the cracking resistance properties of coatings it is high need to increase an energetic cost of propagating cracks. To do that, the multilayer systems are fabricated where metallic layers are placed in the sequence with ceramic ones [6, 7]. Deformation lines propagating through the multilayer coating contain plastic deformation in metallic layers and brittle cracking in ceramic ones. Brittle cracking in ceramics may be stopped at the interface. Anyway, there are some sorts of application wher[...]

Tailoring of multilayer structure to tribological conditions

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Wear is a result of one or complex processes like: erosion, abrasion, impact, metal-to-metal contact, oxidation, and corrosion. Several classification schemes of wear have been developed to understand wear processes. One or more fundamental wear mechanisms may play a crucial role in a real process including a mechanical damage [1]. In many devices, damage generally occurs by means of adhesive, abrasive, corrosive or fatigue wear [2]. The tribology-related engineering applications for highly stressed components require development of new multifunctional thin film systems providing superior mechanical, tribological, chemical etc. performance. It could be achieved by joining properties of different type of materials in multilayer coatings [3÷9]. Currently, a surface modification pays much attention. A set of alternate layers of hard and soft phases as well as appropriate buffer layer close to the substrate, can lead to coating quality improvement and increase adhesion to the substrate [10÷18]. Multilayer coatings are composed of alternately stacked layers of hard and soft phases with thicknesses of a few to tens of nanometers. A combination of alternate layers may lead to considerable hardness and high flexibility as well as good adhesion to substrates. Possible cracks propagation through ceramic coating can be stopped at the ceramic/metallic interface due to a plastic flow. Energy of brittle cracking is compensating by the plastic deformation. However, in some sorts of application, like tribological coatings for medical application, namely, surgical tools, an amount of metallic phase has to be limited. Otherwise, such coatings may lead to the metalosis, i.e. the metal ions adverse interaction with human organism. The titanium nitride (TiN) is of a special interest due to its corrosion resistance, high hardness and bio- compatibility [19, 20]. The other promising material for wear resistant application is amorphous hydrogenated ca[...]

Biomedical inspired surface modification

  Progress in the field of biomedical engineering solutions can effectively combine materials science with alive cells. Surface treatments are effectively done by plasma PVD and CVD techniques to shape the surface and the research activity which is targeted to form a biomimetic nanotopography and surface chemistry. There are still numerous barriers limiting the use of some solutions thus recently popular are materials mimicking the target tissue [1÷3]. Controlling the biological environment through suitable scaffold properties is an essential task for the tissue engineering. Stem cells are the subject of great interest due to their biological properties and clinical application and they are defined to self-renew and produce specialized progeny [4÷6]. The challenge is to develop novel biomaterials which will enhance the new culture-based approaches. Each cell, which grows and matures, has its own niche which has a spatial structure of cells and an extracellular matrix. It forms a microenvironment that keeps the cells alive and gives signals to the main cell proliferation, maturation, or to self-renewal. The stem cell niche refers to an anatomical and functional structure, including cellular and extracellular components, local and systemic factors that are integrated to regulate the stem cell proliferation, differentiation, survival and localization [7÷9]. In 1978, Schofield proposed the concept of "stem cell niche" in studies of the haematopoietic stem cells (HSCs) [10]. Since then, this hypothesis has been validated by a number of studies and the in vivo evidence of the existence of stem cell niche was first provided in studies using invertebrate models [11] and in the Drosophila germline stem cells [12]. The main focus was to reconstruct the microenvironment on the surface with the shape of niches. Nevertheless, the modified materials are still elastically deformable. Optical transparency, electrical insulation, semi-perm[...]

Wpływ struktury powłok na bazie tytanu i węgla na właściwości biofizyczne biomateriałów do kontaktu z krwią

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Adhezja i aktywacja komórek do powierzchni materiałów o przeznaczeniu na implanty medyczne jest bardzo istotnym zagadnieniem [1, 2]. Parametry strukturalne wytworzonej powłoki kontaktowej istotnie wpływają na interakcję biomateriału z tkanką łączną [3]. Celem prowadzonych prac przez zespół autorów jest wytworzenie nowego, gradientowego materiału o odpowiednich właściwościach strukturalnych i dobrej biozgodności [4]. Przedmiotem realizowanych badań były cienkie warstwy gradientowe na bazie tytanu metalicznego oraz stechiometrycznego TiN i Ti(C, N) nanoszone różnymi metodami, a mianowicie: ablacji laserowej (PLD) [5], magnetronową oraz hybrydową łączącą PLD z magnetronową, głównie na klinicznie stosowany poliuretan [6÷9]. Tematykę poszerzono o powłoki na bazie węgla. W związku szerokim zainteresowaniem podłożami polimerowymi, pokrywanie podłoży metalicznych zostało zminimalizowane. Proces osadzania realizowano w Centrum Laserowym w Austrii, kompleksową diagnostykę strukturalną na podstawie badań XRD, SEM, TEM, HRTEM wykonano w IMIM PAN w Krakowie i w Laboratorium Biofizycznym na Politechnice w Grenoble oraz Fundacji Rozwoju Kardiochirurgii w Zabrzu, gdzie prowadzono testy wyznaczenia kinetyki przylegania komórek do materiałów o potencjalnym zastosowaniu biomedycznym. Skonstruowano unikatową aparaturę do badań adhezji komórek w warunkach przepływu medium, na której zrealizowano badania. Dane doświadczalne uzyskuje się na drodze analizy obrazów fluorescencyjnych po przeprowadzonym teście w warunkach kinetycznych i służą one do wyznaczania krzywych kinetycznych. Kompleksowa diagnostyka strukturalna realizowana była metodą rentgenografii strukturalnej oraz skaningowej i transmisyjnej mikroskopii elektronowej oraz laserowej mikroskopii konfokalnej i akustycznej mikroskopii skaningowej i miała na celu opis morfologii powierzchni, analizę właściwości fizycznych oraz mechanicznych. Uzyskane wyniki z przeprowadzonych badań mikrostrukt[...]

Surface functionalization for tissue analog of blood contacting materials

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Blood contacting materials could initiate several processes, which can endanger the life, like the formation of thromboemboli. Properties of new designed materials could minimize influence of the human organism. For blood contact, the biocompatibility requirements are of the highest level of all biomaterial applications, which is due to the continuous blood flow and the high reactivity of blood molecules and cells. Blood contacting materials could initiate several life-endangering processes such as formation of thromboemboli, even in the presence of anti-clotting agents. Thus, our research in the frame of integrated national and international activity is focused on fabrication and diagnostics of materials characterized by reduction or erasing of thrombogenicity. In the last years of material development, lower thrombogenicity was primarily tried to reach by modifying existing material surfaces. Despite the successes in reducing protein and cellular deposits on some materials, this approach do not target to a truly non-thrombogenic surface. Recently, attempts are starting to create self-assembling layers. Such approach is realized in our research activity by the multidisciplinary, international work. Estimation of the cell-material interaction plays an important role in the biomaterial design. Titanium and carbon basis biomaterials, such as diamond-like carbon (DLC), titanium (Ti), and stoichiometric titanium nitride (TiN) as well as titanium carbo-nitrade (Ti(C, N)), seem to be good candidates for future blood-contact applications. These materials were deposited as thin films by the hybrid pulsed laser deposition (PLD) technique to examine the influence of such surfaces on cell behavior. The cell-material reactions were examined in static conditions and then subjected to a dynamical test by application of a radial flow chamber specially design to observe the cell detachment kinetics. Concept of design The concept of design is[...]

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