TY - GEN A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Mechanical and Tribological Properties of Polymer Composites at Cryogenic Temperatures N2 - This paper presents the mechanical and tribological properties of Polytetrafluoroethylene (PTFE) and Polyetheretherketone (PEEK) matrix composites filled with short carbon fibers in cryogenic environments. Tensile tests were performed at room temperature (RT) in air and in LN2. Tribological experiments were carried out with a pin-on-disc configuration at RT, in LN2, in LH2 and in LHe. PEEK composites have a better tribological performance than PTFE materials especially regarding the wear resistance. T2 - 21st International Cryogenic Engineering Conference `06 (ICMC `06) CY - Prague, Czech Republic DA - 2006-07-17 KW - Tribologie KW - Zugfestigkeit KW - Polymerkomposite KW - Kryotechnik KW - PEEK KW - PTFE PY - 2006 SN - 978-80-239-8884-0 SN - 0151-1637 VL - 2 SP - 47 EP - 51 CY - Prague, Czech Republic AN - OPUS4-17397 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Theiler, Geraldine A1 - Gradt, Thomas ED - Wilson, Andrew T1 - Tribological Behaviour of PEEK Composites in Vacuum Environment N2 - For tribological components working under extreme conditions, such as vacuum, or broad temperature ranges, it is often a problem to achieve acceptable durability of their friction parts. Thus, new material requirements are involved for these tribo-systems, in particular regarding operability and reliability. At BAM, several projects were conducted in the recent years, dealing with the tribological properties of friction couples at cryogenic temperature and in vacuum environment. This paper describes the vacuum and ultra high vacuum tribometers constructed at BAM and presents experiments carried out with polymer composites. The experiments presented were performed with PEEK, filled with solid lubricants, against 304 steel with a pin-on-disc configuration in oscillating sliding. Friction tests were carried out in vacuum in the temperature range between -40°C and +160°C and in ultra high vacuum at room temperature. KW - Tribologie KW - Vakuum KW - Polymere KW - Kompositwerkstoffe KW - Festschmierstoffe PY - 2007 SN - 92-9291-217-6 SN - 1609-042X SP - 1 EP - 5 AN - OPUS4-17399 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas A1 - Theiler, Geraldine T1 - Tribological properties of polymer composites for applications in LNG environment N2 - In a first test series, the friction and wear properties of 6 polymeric candidate materials for application in LNG tribosystems were tested. The most favorable properties showed PTFE composite, filled with carbon fibers and PEEK, which showed low and stable friction and a wear coefficient in the order of 10-7 mm3N-1m-1. PTFE containing PEEK composites seem to be also appropriate for LNG applications. Admixtures of graphite as solid lubricant result in lower wear. Contrary, a lubricating mechanism of MoS2 was not observed. The PI-materials showed comparatively high friction and medium wear. T2 - 21th International Colloquium Tribology CY - Stuttgart/Ostfildern, Germany DA - 09.01.2018 KW - Tribology KW - PEEK KW - PTFE composites KW - Friction PY - 2018 SP - 1 EP - 2 AN - OPUS4-43900 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Hübner, Wolfgang A1 - Gradt, Thomas A1 - Klein, P. T1 - Friction and Wear of Carbon Fibre Filled Polymer Composites at Room and Low Temperatures PY - 2004 SN - 0933-5137 SN - 1521-4052 VL - 35 IS - 10/11 SP - 683 EP - 689 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-6866 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - High performance polymer materials for tribological applications in hydrogen and methane N2 - The development of hydrogen technologies is a key strategy to reduce greenhouse gas emission worldwide. Power-to-Gas is a challenging solution, in which hydrogen and methane can be used in mobility, industry, heat supply and electricity generation applications. This presentation deals with the tribological behaviour of polymer materials in hydrogen and methane, both in gas and in liquefied form. T2 - ECOTRIB 2019, MaTri'19 CY - Vienna, Austria DA - 12.06.2019 KW - Slidng wear KW - Polymer materials KW - Hydrogen KW - Methane PY - 2019 SN - 978-3-901657-60-3 SP - 228 EP - 229 AN - OPUS4-48253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas T1 - Tribological Research in Germany - Overview and Examples from the Federal Institute for Materials Research and Testing (BAM) N2 - The talk gives a historical introduction and introduces some of the biggest and most important research institutes in Germany dealing with tribology at Universities, scientific societies and companies. Some examples for research projects and focus areas are given. As an example for a research institute with a long history in tribological research the activities of BAM in Berlin are presented. T2 - Joint Tribology Symposium of Kyushu University and Yokohama National University KY7 CY - Fukuoka, Japan DA - 01.02.2019 KW - Friction KW - Lubrication KW - Wear PY - 2019 AN - OPUS4-47345 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas T1 - Influence of cryogenic hydrogen environment on the tribological properties of materials N2 - The presentation gives an overview over the LH2-activities during 20 years of tribological research in cryogenic environments at BAM. T2 - 2019 Hydrogenius & I2CNER Tribology Symposium CY - Fukuoka, Japan DA - 30.01.2019 KW - Friction KW - Wear KW - Hydrogen KW - Cryogenic Engineering KW - Hydrogen Embrittlement PY - 2019 AN - OPUS4-47339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Harsha, A. P. A1 - Gradt, Thomas T1 - On the sliding wear behavior of PEAK composites in vacuum environment N2 - The tribological behavior of neat and filled PEEK and PEKK composites were compared in air and vacuum conditions. Very low friction and wear coefficient were obtained at low sliding speed while severe wear occurred at high speed. Experimental results are discussed by analysing the transfer film and wear debris. KW - PEAK KW - Composites KW - Wear KW - Friction KW - Vacuum PY - 2019 DO - https://doi.org/10.1115/1.4042271 SN - 0022-2305 SN - 0742-4787 VL - 141 IS - 4 SP - 044502-1 EP - 044502-7 PB - ASME AN - OPUS4-47298 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Spaltmann, Dirk A1 - Kogia, M. A1 - Liedtke, S. A1 - Dykeman, D. A1 - Gradt, Thomas T1 - Challenges for the design of a universal tribological database for materials N2 - Renowned institutions in the field of tribology combine their testing and analytical capabilities with experts in materials/process information management technology to provide the respective Services in Europe (i-TRIBOMAT). This requires a centralized materials information management system or the standardised capture, consolidation and harmonization of tribological information. T2 - 60. Tribologe-Fachtagung CY - Goettingen, Germany DA - 23.09.2019 KW - Database KW - Tribology KW - Digital KW - LIMS PY - 2019 SN - 978-3-9817451-4-6 SP - 37/1 EP - 37/5 PB - GfT (Gesellschaft für Tribologie) CY - Jülich AN - OPUS4-49147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shapovalov, Oleg A1 - Gaal, Mate A1 - Hönig, Gerald A1 - Gradt, Thomas A1 - Weiss, S. T1 - Temperature dependence of the propagation speed of a longitudinal wave in different solids for use as a wedge material in an extreme-temperature-resistant ultrasonic transducer N2 - In special cases of angle beam ultrasonic measurement – e.g. defect detection in hot solids as well as flow measurement of liquid gases or energy storage mediums – the applied transducer has to withstand extreme temperatures. Since the irradiation angle into the specific material is determined not only by wedge design, but also by the speed of sound in both the wedge material and the tested object, the developer must take into account the speed of the wave propagation in a wedge material over the whole temperature range of transducers application. In this study we investigate the temperature dependence of the speed of longitudinal wave propagation in 10 different materials in the range from -200 °C to 400 °C. The investigated materials belong to different material classes (ceramics, glass, as well as ferrous and non-ferrous metals) and are all temperature-resistant up to at least 600 °C, and therefore applicable as wedge materials in an ultrasonic transducer for use at extreme temperatures. T2 - 23rd International Congress on Acoustics CY - Aachen, Germany DA - 09.09.2019 KW - Ultrasonic Transducer KW - Speed of sound KW - Longitudinal Wave KW - Temperature PY - 2019 SP - 4776 EP - 4782 AN - OPUS4-48980 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Friction and wear behaviour of graphite filled polymer composites in hydrogen environment N2 - Ensuring a sustainable energy supply is currently one of the most important areas for industry and research institutions. Hydrogen technology is a promising candidate, but its broad extension requires extremely high reliability and safety in all areas for common applications as automobiles and stationary fuel cells. Particularly components containing tribosystems are critical parts. T2 - WTC 2013 - 5th World tribology congress CY - Torino, Italy DA - 08.09.2013 PY - 2013 SP - Paper 868, 1 EP - 2 AN - OPUS4-30942 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - PEEK-Komposite für Reibsysteme in der Vakuumtechnik T2 - Fachtagung der Gesellschaft für Tribologie 2007 CY - Göttingen, Germany DA - 2007-09-24 PY - 2007 AN - OPUS4-17482 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas A1 - Banova, Z. A1 - Schlarb, A.K. T1 - PEEK-Komposite für Reibsysteme in der Vakuumtechnik N2 - Aim of the investigation is to characterize selected PEEK-composites in vacuum environment. Oscillating sliding friction was investigated with a pin-on-disc configuration in high vacuum (10-5 mbar) at room temperature, -40 °C, +100 °C and +160 °C. The contact pressure was 1 MPa and 7 MPa respectively , the maximum sliding velocity 0.1 m/s. Furthermore, tests in ultra high vacuum (10-9 mbar) were carried out with flat and spherical pins at 1 MPa and 60 MPa respectively. Among the tested materials MoS2 filled PEEK shows the best tribological performance in vacuum. Particularly, in the lower temperature range and at higher loads the friction behaviour is improved by MoS2 content. KW - Vakuum KW - Polymer composite KW - Tribology KW - PEEK Komposite KW - Hochvakuum KW - Temperatureinfluss KW - MoS2 KW - Grafit KW - PEEK composites KW - High vacuum KW - Influence of the temperature KW - Graphite PY - 2008 SN - 0724-3472 VL - 55 IS - 5 SP - 25 EP - 30 PB - Expert Verlag CY - Renningen AN - OPUS4-18306 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas T1 - Wear Resistant MoS2/ta-C Coatings for Applications in Various Environments T2 - 19th International Vacuum Congress (IVC-19) CY - Paris, France DA - 2013-09-09 PY - 2013 AN - OPUS4-29126 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Hübner, Wolfgang A1 - Gradt, Thomas A1 - Klein, P. A1 - Friedrich, K. T1 - Tribologisches Verhalten der Werkstoffpaarung Polymerverbundwerkstoff/Stahl bei tiefen Temperaturen KW - Kryotechnik KW - Polymerkomposite KW - PTFE KW - PEEK KW - Flüssigwasserstoff KW - Flüssighelium KW - Reibungszahlen KW - Übertrag PY - 2005 SN - 0724-3472 VL - 52 IS - 1 SP - 20 EP - 25 PB - Expert Verlag CY - Renningen AN - OPUS4-12645 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Influence of hydrogen environment on the tribological performance of polymer composites T2 - WHEC 2006 - 16th World Hydrogen Energy Conference CY - Lyon, France DA - 2006-06-13 KW - Polymer composites KW - Tribological behaviour KW - Low temperatures KW - Hydrogen environment PY - 2013 SN - 978-1-62276-540-9 SP - CD #153 / 654 EP - 662 PB - International Association for Hydrogen Energy CY - Lyon AN - OPUS4-12646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - MoS2-filled PEEK composite as a self-lubricating material for aerospace applications T2 - 40th Aerospace mechanisms symposium CY - Cocoa Beach, FL, USA DA - 2010-05-12 KW - PEEK composite KW - MoS2 KW - Friction KW - Ultra high vacuum KW - Aerospace PY - 2010 IS - NASA/CP-2010-216272 SP - 347 EP - 351 CY - Hanover, MD, USA AN - OPUS4-22047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas A1 - Theiler, Geraldine A1 - Hale, H. T1 - Reibeigenschaften von Polymerfolien in Flüssighelium N2 - Starke Magnetfelder, wie sie z.B. für die Magnetresonanztomografie (MRT) notwendig sind, werden durch supraleitende Spulen erzeugt, die mit Flüssighelium auf eine Temperatur von -269°C gekühlt werden. Die Reibungswärme, die z.B. bei kleinsten Bewegungen zwischen der Spule und deren Stützstruktur entsteht, kann bewirken, dass die kritische Temperatur des Supraleiters lokal überschritten wird und ein normalleitender Bereich entsteht. Aufgrund der bei Normalleitung entstehenden jouleschen Wärme kann sich dieser Bereich weiter erwärmen und schnell ausbreiten. Dieser Vorgang wird als Quench bezeichnet und führt zum schlagartigen Verdampfen des extrem teuren Kältemittels und zu Betriebsunterbrechungen von mehreren Tagen. Da diese Quenche durch Reibungswärme verursacht werden, ist es notwendig, das Reibverhalten der beteiligten Werkstoffe so zu optimieren, dass kein kritischer Betriebszustand erreicht wird. Dies betrifft in erster Linie Polymerfolien, die zur elektrischen Isolierung zwischen der Spule und der Stützstruktur notwendig sind. Neben zu hoher Reibung allgemein müssen ausgeprägte Haftreibungsspitzen und StickSlip-Effekte vermieden werden. Mit diesem Ziel wurde das Reibverhalten von PTFE-, PET- und Pl-Folien bei tiefen Temperaturen und den für diese Anwendung typischen niedrigen Gleitgeschwindigkeiten untersucht. Es zeigte sich, dass die Reibung zwischen Polymeroberflächen in Flüssighelium allgemein höher, aber stabiler als in Flüssigstickstoff ist. Allerdings hängt das Reibverhalten erheblich von der Werkstoffpaarung ab. Der Stick-Slip-Effekt nimmt bei allen untersuchten Polymer-Polymer-Paarungen mit wachsender Kontaktpressung zu. PET gegen PET hat das ungünstigste Reibverhalten und sollte bei hohen Pressungen vermieden werden. Zum Vergleich getestete Paarungen von Polymeren gegen Aluminium zeigten deutlich günstigeres Reibverhalten ohne signifikanten Stick-Slip. Deshalb sollte bei derartigen Anwendungen sichergestellt werden, dass die Gleitebene zwischen Polymer- und Metalloberfläche liegt. T2 - 55. Tribologie-Fachtagung - Reibung, Schmierung und Verschleiß - Forschung und praktische Anwendungen CY - Göttingen, Germany DA - 22.09.2014 PY - 2014 SN - 978-3-00-046545-1 VL - II SP - 41/1 EP - 41/10 AN - OPUS4-31529 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Einfluss von Wasserstoff auf das Gleitverhalten von graphitgefüllten Polymeren N2 - Die tribologischen Eigenschaften von graphitgefüllten Polyimiden gegen Stahl 100Cr6 wurden an Luft, im Hochvakuum (10'3 Pa), und in Wasserstoffumgebung bei verschiedenen Drücken (103 Pa, 104 Pa und 105 Pa) untersucht. Zwei unterschiedliche Polyimid-Typen wurden eingesetzt, wobei Typ und Menge des Graphits variiert wurden. Die Experimente wurden bei 3,1 MPa Kontaktdruck und einer Gleitgeschwindigkeit von 0,2 m/s bzw. 1 m/s durchgeführt. Die verschlissenen Oberflächen und die Morphologie des Materialübertrags auf die Stahl-Gegenfläche wurden mit Lichtmikroskopie, REM, TEM und FTIR untersucht. Der Vergleich der untersuchten Werkstoffe zeigt, dass sowohl die Matrix als auch der Graphitanteil einen Einfluss auf das Reibverhalten in den verschiedenen Umgebungen haben. T2 - 55. Tribologie-Fachtagung - Reibung, Schmierung und Verschleiß - Forschung und praktische Anwendungen CY - Göttingen, Germany DA - 22.09.2014 PY - 2014 SN - 978-3-00-046545-1 VL - II SP - 35/1 EP - 35/11 AN - OPUS4-31530 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Brice, H. A1 - Gradt, Thomas T1 - Stick-slip behaviour of polymer films in LHe N2 - Superconducting magnets are susceptible to quenching, even with the smallest amounts of energy disturbances due to the extremely low thermal capacity of materials at 4.2 K. Hence, small mechanical disturbances resulting in frictional heating can be sufficient to exceed the wire’s critical temperature, causing it to quench. Unfortunately, relative motion between surfaces in the magnet System is inevitable due to various forces present in the System, including winding pretension, differences in material thermal contraction and the large electromagnetic forces. Typically insulating polymers are present at this interface to achieve the required electrical insulation requirements. T2 - WTC 2013 - 5th World tribology congress CY - Torino, Italy DA - 08.09.2013 PY - 2013 SP - Paper 366, 1 EP - 4 AN - OPUS4-30940 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas T1 - Reibeigenschaften von Polymerfolien in Flüssigkeiten T2 - 55. Tribologie-Fachtagung CY - Goettingen, Germany DA - 2014-09-22 PY - 2014 AN - OPUS4-31458 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas A1 - Banova, Z. A1 - Schlarb, A.K. T1 - PEEK-Komposite für Reibsysteme in der Vakuumtechnik KW - Vakuum KW - Polymer composite KW - Tribology PY - 2007 SN - 978-3-00-022603-8 VL - I SP - 19/1 EP - 19/12 CY - Aachen AN - OPUS4-17364 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas ED - Inaki Azkarate, ED - Estibaliz Ezponda, ED - Marco Nicola Carcassi, ED - Marangon, Alessia ED - Elena Rossi, T1 - Polymer composites for tribological applications in hydrogen environment N2 - In the development of hydrogen technology, special attention is paid to the technical problems of hydrogen storage. One possible way is cryogenic storage in liquid form. Generally cryotechnical machines need components with interacting surfaces in relative motion such as bearings, seals or valves, which are subjected to extreme conditions. Materials of such systems have to be resistant to friction-caused mechanical deformation at the surface, low temperatures and hydrogen environment. Since materials failure can cause uncontrolled escape of hydrogen, new material requirements are involved for these tribo-systems, in particular regarding operability and reliability. In the past few years several projects dealing with the influence of hydrogen on the tribological properties of friction couples were conducted at the Federal Institute for Materials Research and Testing, (BAM), Berlin. This paper reports some investigations carried out with polymer composites. Friction and wear were measured for continuous sliding and analyses of the worn surfaces were performed after the experiments. Tests were performed at room temperature in hydrogen as well as in liquid hydrogen. T2 - 2nd International Conference on Hydrogen Safety CY - San Sebastián, Spain DA - 2007-09-11 KW - Hydrogen KW - Polymer composite KW - Tribology PY - 2007 SN - 978-84-95520-15-9 SP - 1 EP - 9 CY - San Sebastián, Spain AN - OPUS4-18429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas T1 - Tribological behaviour of solid lubricants in hydrogen environment N2 - For further development of hydrogen technology it is necessary to have a sufficient number of materials for safe, reliable, and enduring service available. In this respect, tribosystems directly exposed to hydrogen are critical because of vanishing protective oxide layers in the presence of a chemical reducing environment. Furthermore, liquid lubricants are often not applicable, because of purity requirements, or very low temperatures in the case of liquid hydrogen. Thus, for numerous components in hydrogen technology, solid lubrication is the only possible method for reducing friction and wear. However, information about the suitability of particular friction reducing materials such as graphite, DLC, MoS2, and WS2 for hydrogen environment is very limited. Therefore, investigations on the tribological behaviour of these materials in liquid and gaseous hydrogen were carried out. The paper presents results for MoS2, WS2, and carbon coatings, and for PEEK matrix composites filled with PTFE, MoS2, or graphite. For comparison also results of tests in inert gases and liquid nitrogen and helium are shown. T2 - World Tribology Congress WTC IV CY - Kyoto, Japan DA - 2009-09-06 PY - 2009 AN - OPUS4-19893 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Gleitverhalten von PEEK-Kompositwerkstoffen in Wasserstoffumgebung N2 - Die Reibeigenschaften von PEEK-Materialien gegen Stahlscheiben wurden in Luft, Vakuum und Wasserstoffumgebung untersucht. Die Ergebnisse zeigen, dass reines PEEK umgebungsabhängig ist und die Desorption von Gasen im Vakuum zu hohen Verschleißraten führt. Die niedrigsten Verschleißraten sowohl in Vakuum als auch in einer Wasserstoffumgebung erzielen TiO2-Partikel. Ferner treten chemische Prozesse in den Materialien und im Tribokontakt auf und interagieren miteinander. T2 - 57. Tribologie-Fachtagung CY - Göttingen, Germany DA - 26.09.2016 KW - PEEK KW - Reibung KW - Wasserstoffumgebung PY - 2016 SN - 978-3-9817451-1-5 SP - 60/1 EP - 60/10 AN - OPUS4-37839 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Friction and wear characteristics of polymers in gaseous and liquid hydrogen N2 - The tribological characteristics of pure and graphite filled polymers were investigated in gaseous hydrogen at ambient temperatures and in LH2 at -253°C. It could be shown that the tribological properties of PI and PEEK materials is related to the formation of a transfer film. The influence of both hydrogen and cryogenic temperatures will be discussed in the presentation. T2 - 21th International Colloquium Tribology CY - Stuttgart/Ostfildern, Germany DA - 09.11.2018 KW - Friction KW - Wear KW - Hydrogen KW - PEEK PY - 2018 SP - 1 EP - 2 AN - OPUS4-43903 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas A1 - Theiler, Geraldine T1 - Tribological behaviour of solid lubricants in hydrogen environment T2 - World tribology congress 2009 CY - Kyoto, Japan DA - 2009-09-06 KW - Tribologie KW - Kompositwerkstoffe KW - Festschmierstoffe KW - Wasserstoff PY - 2009 SN - 978-4-9900139-9-8 IS - B1-122 SP - 15 AN - OPUS4-20137 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weihnacht, V. A1 - Brückner, A. A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - MoS2/ta-C-Kombinationsschichten hergestellt durch Laser-Arc-Technologie - Hochwertige Gleitschichten für extreme Umgebungen T1 - MoS2/ta-C coatings produced by laser-arc-technology N2 - Mittels lasergesteuerter gepulster Vakuumbogentechnologie (Laser-Arc) wurde eine reihe von reinen MoS2-Schichten sowie Kombinationsschichten aus MoS2 und tetraedrischem amorphen Kohlenstoff (ta-C) hergestellt. Mit diesen Schichtvarianten erfolgten tribologische Tests im Vakuum sowie in Atmosphäre. Dabei wurden im Hochvakuum reibungskoeffizienten bis zu 0,005 gemessen. Durch die Verwendung einer ta-C unterschicht konnte eine Lebensdauer von über 5×105 Lastzyklen erreicht werden. Zudem erwies sich diese unterschicht als vorteilhaft für das tribologische Verhalten der MoS2/ta-C Schichten unter atmosphärischen Bedingungen. N2 - A series of MoS2 and combined MoS2/ta-C coatings were prepared by lasercontrolled arc evaporation (Laser-Arc) in order to study the tribological coating behaviour under vacuum and atmospheric conditions. Very low friction coefficients down to 0.005 were measured under high vacuum. By using a ta-C underlayer beneath the MoS2 a increased lifetime up to 5×105 load cycles could be obtained. Also under atmospheric conditions the underlayer had a beneficial effect on coating performance. KW - MoS2 KW - ta-C Schichten KW - Reibung KW - Verschleiß KW - Vakuum Umgebungen PY - 2012 DO - https://doi.org/10.1002/vipr.201200500 SN - 0947-076X SN - 1522-2454 VL - 24 IS - 5 SP - 17 EP - 23 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-27207 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas T1 - Polmeric materials for tribosystems in cryogenic liquefied natural gas (LNG) N2 - In order to test the suitability of polymers for LNG service, the tribological behaviour of materials based on PEEK, PTFE, PI and UHMW-PE sliding against CrNi steel was investigated. T2 - 59. Tribologie-Fachtagung CY - Goettingen, Germany DA - 24.09.2018 KW - CNG KW - LNG KW - Polymers KW - Friction PY - 2018 AN - OPUS4-46183 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübner, Wolfgang A1 - Theiler, Geraldine A1 - Gradt, Thomas A1 - Klein, P. A1 - Friedrich, K. T1 - Der Einfluss kryogener Medien auf den Materialtransfer im Tribosystem Polymerkomposit/Stahl PY - 2001 SN - 0724-3472 VL - 48 IS - 6 SP - 8 EP - 12 PB - Expert Verlag CY - Renningen AN - OPUS4-12659 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hausberger, A. A1 - Major, Z. A1 - Theiler, Geraldine A1 - Gradt, Thomas A1 - Schwarz, T. T1 - Investigation on the friction and wear behaviour of thermoplastic polyurethanes by controlling the adhesion and deformation part of friction N2 - In this work, unfilled and graphite filled TPU materials were used to investigate the contribution of the adhesion and deformation component of friction. Pin-on-Disc tests were conducted in the air and under vacuum condition by using different surface roughness. T2 - 6. European Conference on Tribology CY - Ljubljana, Slovenia DA - 07.06.2017 KW - TPU KW - Friction KW - Wear KW - Adhesion KW - Deformation KW - Vacuum PY - 2017 SP - 4.02 - 1 EP - 4.02 - 2 AN - OPUS4-40763 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas T1 - Tribological properties of polymer composites for applications in LNG environment N2 - In a first test series, the friction and wear properties of 6 polymeric candidate materials for application in LNG tribosystems were tested. The most favorable properties showed PTFE composite, filled with carbon fibers and PEEK, which showed low and stable friction and a wear coefficient in the order of 10-7 mm3N-1m-1. PTFE containing PEEK composites seem to be also appropriate for LNG applications. Admixtures of graphite as solid lubricant result in lower wear. Contrary, a lubricating mechanism of MoS2 was not observed. The PI-materials showed comparatively high friction and medium wear. T2 - 21th International Colloquium Tribology CY - Stuttgart/Ostfildern, Germany DA - 09.01.2018 KW - Tribology KW - PEEK KW - PTFE composite KW - Friction PY - 2018 AN - OPUS4-43899 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Friction and wear behaviour of graphite filled polymer composites in hydrogen environment N2 - High performance polymer composites have been intensively investigated for tribological applications in air, but rarely in hydrogen environment. Author's previous benchmark of composites in liquid hydrogen (LH2) showed that graphite filled polymers have beneficial friction behaviour in this extreme condition. Therefore, further investigations have been undertaken in hydrogen environment. This paper presents first results obtained with polyimide composites filled with different types (natural, synthetic) and amounts of graphite in air, vacuum and hydrogen environments. A particular attention is taken to the influence of hydrogen on graphite as well as on the polymer matrix. KW - Polymer composites KW - Polyimide KW - Graphite KW - Friction KW - Wear KW - Hydrogen environment KW - Vacuum PY - 2015 DO - https://doi.org/10.2474/trol.10.207 SN - 1881-2198 VL - 10 IS - 2 SP - 207 EP - 212 CY - Tokyo, Japan AN - OPUS4-33554 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Gleitverhalten von PEEK-Kompositwerkstoffen in Wasserstoffumgebung N2 - Die Reibeigenschaften von PEEK Materialien gegen Stahlscheiben wurden in Luft, Vakuum und Wasserstoffumgebung untersucht. KW - PEEK-Komposite KW - Wasserstoff KW - Vakuum KW - Graphit PY - 2017 SN - 0724-3472 VL - 64 IS - 6 SP - 52 EP - 59 AN - OPUS4-42919 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hübner, Wolfgang A1 - Gradt, Thomas A1 - Theiler, Geraldine A1 - Aßmus, Kristin A1 - Ostrovskaya, Y. T1 - Werkstoff-Untersuchungen für technische Anwendungen in flüssigem Wasserstoff T2 - 1. Deutscher Wasserstoff-Energie-Tag 2002 CY - Essen, Deutschland DA - 2002-10-12 PY - 2002 IS - CD-ROM SP - 1 EP - 8 AN - OPUS4-1973 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Comparison of the sliding behavior of several polymers in gaseous and liquid hydrogen N2 - The development of hydrogen technologies entails high safety requirements in distribution and dispensing infrastructure. Therefore, it is necessary to pursue research on material compatibility in hydrogen, especially for critical parts with tribological issues. The focus of this study is to evaluate the influence of hydrogen on a wider range of commercially available polymer materials. Thereby, the friction and wear behavior of different grades of TPE, POM, PA66, PA12, PPA, PEEK, PPS, PTFE, PAI, PI and PBI were investigated against a rotating steel disk (AISI 304). Filled and unfilled polymers from different suppliers were evaluated at room temperature in air, vacuum and hydrogen gas (H2) as well as in liquid hydrogen at - 253°C (LH2). The sliding behavior of the polymer materials is discussed by means of surface analyses, whereby special attention is paid to the formation of a transfer film. According to the results at ambient temperature, the effect of hydrogen environment on the tribological behavior of neat polymers may be related to lack of moisture, but also to saturated hydrocarbons in gaseous hydrogen. In liquid hydrogen, the best tribological performances were achieved with neat PA polymers as well as PPS and PI composites. KW - Polymers KW - Composites KW - Sliding wear KW - Hydrogen KW - Cryogenic temperature PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597123 DO - https://doi.org/10.2474/trol.18.217 SN - 1881-2198 VL - 18 IS - 5 SP - 217 EP - 231 PB - Japanese Society of Tribologists AN - OPUS4-59712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Comparison of the sliding behaviour of several polymers in hydrogen N2 - The work presented here deals with the friction and wear behaviour of polymer materials in hydrogen. Commercially available grades of PEEK, PA, PPA, PAI, PI and PBI were investigated at room temperature in air and hydrogen gas (H2) as well as in liquid hydrogen at -253°C (LH2). T2 - 7th World Tribology Congress, WTC 2022 CY - Lyon, France DA - 10.07.2022 KW - Friction KW - Wear KW - Polymers KW - Hydrogen KW - Cryogenic PY - 2021 SP - 1 AN - OPUS4-62089 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Influence of counterface and environment on the tribological behaviour of polymer materials N2 - This paper focuses on the influence of the counterface materials on the sliding behaviour of polymer materials in hydrogen. Polyimide (PI), polyetheretherketone (PEEK) and Polytetrafluoroethylene (PTFE) materials were investigated against hardened 52100 martensitic bearing steel and 304 austenitic stainless steel with similar roughness (Ra = 0.2 μm). Results indicate that the friction and wear of PI and PEEK materials depend on the counterface material. This effect wasn’t observed for PTFE composites. While the tribological performance of polyimide is better against 52100 in hydrogen, improved sliding behaviour of PEEK materials is observed with 304 counterface, particularly at higher sliding speed. Surface analyses of the transfer film reveal that the influence of the counterface is primarily related to the chemical nature of the steel for PI and to the thermal conductivity of the disc for PEEK materials. KW - Friction KW - Wear KW - Polymers KW - Hydrogen Transfer Film PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-515483 DO - https://doi.org/10.1016/j.polymertesting.2020.106912 VL - 93 SP - 106912 PB - Elsevier Ltd. AN - OPUS4-51548 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Environmental effects on the sliding behaviour of PEEK composites N2 - The sliding performance of PEEK materials against steel discs was investigated in air, vacuum and hydrogen environment. KW - Sliding friction KW - PEEK KW - Graphite KW - TiO2 KW - CNTs KW - Vacuum KW - Hydrogen PY - 2016 DO - https://doi.org/10.1016/j.wear.2016.09.019 SN - 0043-1648 SN - 1873-2577 VL - 368 SP - 278 EP - 286 PB - Elsevier B.V. AN - OPUS4-37927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas T1 - Influence of solid lubricant fillers on the tribological behaviour of PEEK composites in vacuum N2 - Polymer composites are widely used as dry sliding materials for economical reasons or in special cases where the application of liquid lubricants or greases is not possible. Examples can be found in space, vacuum, low temperature, or cleanroom environment. For such dry sliding tribosystems it is necessary to achieve acceptable low friction and endurance. Polytetrafluoroethylene (PTFE) has proved to be an outstanding material for the use in tribological applications in vacuum in the broad temperature range from - 260 °C to + 260 °C. A promising matrix material is polyetheretherketon (PEEK). Like PTFE, it is also resistant to many aggressive solvents and has a very low vapor pressure, making it suitable for vacuum applications. The tribological behaviour of PEEK and PEEK-matrix composites has been investigated in many studies. However, the number of studies of self lubricating PEEK composites filled with PTFE and other solid lubricants are limited for vacuum and ultra high vacuum environment. The paper presents results of high-vacuum friction tests of different carbon fibre reinforced PEEK composites filled with PTFE, and a further solid lubricant. The polymer samples were tested in pin-on-disc configuration against X5CrNi1810 steel (similar to AISI 304). Depending on sliding speed and temperature, friction coefficients as low as for PVD coatings have been observed. T2 - 13th European Space Mechanisms and Tribology Symposium (ESMATS 13) CY - Vienna, Austria DA - 2009-09-23 PY - 2009 AN - OPUS4-19892 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Friction and wear of PEEK composites in vacuum environment N2 - The sliding performance of PEEK composites was investigated in vacuum environment. Tests were performed with carbon fibre reinforced PEEK composites filled with PTFE, and MoS2 or graphite as further solid lubricant. Polymer samples were tested in a pin-on-disc configuration continuously sliding against CrNi-steel. Depending on sliding speed and temperature, the MoS2 filled composites showed high wear resistance and friction coefficients as low as PVD coatings. KW - PEEK composites KW - Vacuum KW - Friction KW - Wear KW - MoS2 KW - Graphite PY - 2010 DO - https://doi.org/10.1016/j.wear.2010.04.007 SN - 0043-1648 VL - 269 IS - 3-4 SP - 278 EP - 284 PB - Elsevier CY - Amsterdam AN - OPUS4-22046 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas A1 - Österle, Werner A1 - Brückner, A. A1 - Weihnacht, V. T1 - Friction and endurance of MoS2/ta-C coatings produced by laser arc deposition N2 - The tribological behaviour of MoS2/ta-C double layer coatings deposited by Laser-Arc technology was investigated in vacuum and air. In vacuum environment, the friction coefficient against steel balls varies between 0.005 and 0.02 depending on the contact pressure. At high contact pressures, the friction coefficient is as low as 0.005 and the life time between 340,000 and 500,000 cycles. Furthermore, it is shown that a ta-C base layer improves the performance of MoS2 coating. Surface analyses were performed before and after the tribological tests by means of SEM, EDX, XRD, and TEM. They show that in the top layer beneath the sliding surface crystallization of the initially quasi-amorphous MoS2 took place. TEM images also verified an orientation of the basal MoS2-lattice planes parallel to the surface. KW - MoS2 coatings KW - Ta-C KW - Vacuum KW - Laser arc deposition PY - 2013 DO - https://doi.org/10.1016/j.wear.2012.10.007 SN - 0043-1648 VL - 297 IS - 1-2 SP - 791 EP - 801 PB - Elsevier CY - Amsterdam AN - OPUS4-27114 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Theiler, Geraldine A1 - Gradt, Thomas ED - Kalia, S. ED - Fu, S.-Y. T1 - Friction an wear of polymer materials at cryogenic temperatures N2 - Polymers are extensively used for sliding systems in cryogenic applications because of their favourable friction and wear behaviour in the absence of external lubrication. Since important new technologies are based on applications under extreme conditions, such as at low temperatures, new requirements on material properties, in particular regarding their operability and reliability, must be met. Up to now, most tribological investigations have been carried out in inert cryogens or cryogenic gas (He, N2). Few experiments have been performed in vacuum environment at cryogenic temperatures. Rarely were testing in reactive media, such as LH2 or LOX. Due to the wide range of operating conditions in cryogenic applications, it is difficult to state general rules. Therefore, this chapter tends to give an overview on theories and experimental studies on polymer tribology at cryogenic temperatures. PY - 2013 SN - 978-3-642-35334-5 SN - 978-3-642-35335-2 DO - https://doi.org/10.1007/978-3-642-35335-2_3 SP - Chapter 3, 41 EP - 58 PB - Springer CY - Berlin Heidelberg AN - OPUS4-31188 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Tribological characteristics of polyimide composites in hydrogen environment N2 - The influence of hydrogen environment on the friction and wear behavior of polyimide (PI) composites was investigated for two different PI-types (PI1 and PI2) filled with natural or synthetic graphite. Sliding tests were run against AISI 52100 steel and the worn surfaces as well as the transfer film were analyzed by means of SEM, EDX and Infrared Spectroscopy. Results indicate that the chemical structure of the polyimide has a major influence on the tribological behavior. While the friction of PI2 remains rather stable in all environments, PI1 showed very low friction in hydrogen without any lubricant. The lubricity of graphite was found to be more effective in hydrogen than in moist air. KW - Sliding friction KW - Polyimide KW - Graphite KW - Hydrogen PY - 2015 DO - https://doi.org/10.1016/j.triboint.2015.06.001 SN - 0301-679X VL - 92 SP - 162 EP - 171 PB - Elsevier Ltd. CY - Oxford AN - OPUS4-33555 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brice, H. A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Frictional behavior of material couples in superconducting MRI magnet systems at 4.2 K N2 - Windings in superconducting magnets operating at 4.2 K are highly susceptible to quenching caused by small frictional heat inputs. Small movements in the magnet system are inevitable during ramping due to the increasing electromagnetic forces. Friction pairs of polymer based materials have been investigated at 4.2 K to gain an understanding of their sliding behavior in conditions representative of superconducting MRI systems. The results indicate that polymer-polymer pairs experience unstable sliding behavior with repeated stick-slip whereas polymer-aluminum couples have stable sliding behavior up to high contact pressures of 20 MPa. KW - Cryotribology KW - Friction KW - MRI magnets KW - Stick-slip PY - 2012 DO - https://doi.org/10.1109/TASC.2011.2175683 SN - 1051-8223 VL - 22 IS - 3 SP - 4400204-1 EP - 4400204-4 PB - IEEE CY - New York, NY AN - OPUS4-26384 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Friction and wear characteristics of polymers in gaseous and liquid N2 - In the present work it was shown that the the aim of the presented tests is to investigate polymer composites for their suitability for friction systems in gaseous and liquid hydrogen. T2 - 59. Tribologie-Fachtagung CY - Göttingen, Germany DA - 24.09.2018 KW - Friction KW - Wear KW - Polymer composites KW - Hydrogen KW - Cryogenic temperature PY - 2018 SN - 978-3-9817451-3-9 SP - 60/1 EP - 60/4 AN - OPUS4-46178 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Einfluss von Wasserstoff auf das Gleitverhalten von graphitgefüllten Polymeren N2 - Die tribologischen Eigenschaften von graphitgefüllten Polyimiden gegen Stahl 100Cr6 wurden an Luft, im Hochvakuum (l0⁻ ³ Pa) und in Wasserstoffumgebung bei verschiedenen Drücken (10³ Pa, 10⁴ Pa und 10⁵ Pa) untersucht. Zwei unterschiedliche Polyimid-Typen wurden eingesetzt, wobei Typ und Menge des Graphits variiert wurden. Die Experimente wurden bei 3,1 MPa Kontaktdruck und einer Gleitgeschwindigkeit von 0,2 m/s bzw. 1 m/s durchgeführt. Die verschlissenen Oberflächen und die Morphologie des Materialübertrags auf die Stahl-Gegenfläche wurden mittels Lichtmikroskopie, REM, TEM und FTIR untersucht. Die Untersuchung zeigt, dass sowohl die Matrix als auch der Graphitanteil einen deutlichen Einfluss auf das Reibverhalten von Verbundwerkstoffen in Wasserstoffumgehungen haben können. N2 - The tribological behaviour of graphite filled polyimide composites against steel (AISI 521 00) was investigated in air, vacuum and hydrogen environment at different pressures (10³ Pa, 10⁴ Pa, and 10⁵ Pa). Composites consist of two polyimides filled with different types and amount of graphite. Friction and wear measurements were performed at 0.2m/s and 3.1MPa at ambient temperature. Wom surfaces and morphology of the material transfer on the steel counter-face were investigated by optical microscopy, SEM, TEM and FTIR analyses. Results reveal that both the polyimide structure and graphite can have an important influence on the friction behaviour of composites in hydrogen environment. KW - Polymere KW - Verbundwerkstoffe KW - Graphit KW - Wasserstoff KW - Vakuum KW - Polymers KW - Composites KW - Graphite KW - Hydrogen KW - Vacuum PY - 2015 SN - 0724-3472 VL - 62 IS - 2 SP - 25 EP - 32 PB - Expert Verlag CY - Renningen AN - OPUS4-33557 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Benchmarking of polymer materials for tribological applications in hydrogen N2 - The focus of this study is to evaluate the influence of hydrogen on the friction and wear behavior of a wide range of polymer materials. Thereby, the tribological performance of filled und unfilled polymers from different suppliers were compared at room temperature in air and hydrogen gas (H2) as well as in liquid hydrogen at -235°C (LH2). T2 - 23rd International Conference on Wear of Materials CY - Online meeting DA - 26.04.2021 KW - Polymers KW - Hydrogen KW - Friction KW - Wear PY - 2021 AN - OPUS4-52651 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -