TY - GEN A1 - Fischer, Annette A1 - Meissner, Andreas A1 - Weiß, Sabine ED - Yuan, Huang ED - Wittmann, Folker H. T1 - Microstructural peculiarities and mechanical properties of coronary stents T2 - Nonlocal Modelling of Failure of Materials, proceedings of an international workshop, University of Wuppertal, June 2007 Y1 - 2007 SN - 978-3-931681-87-6 SP - 91 EP - 104 PB - Aedificatio Publ. CY - Freiburg ER - TY - THES A1 - Weiß, Sabine T1 - Mikrostruktur- und Mikrotexturentwicklung bei der zyklischen Hochtemperaturverformung reiner kubisch-flächenzentrierter Metalle Y1 - 1998 SN - 3-8265-3372-0 PB - Shaker CY - Aachen ER - TY - GEN A1 - Hering, Daniel A1 - Kail, Jochem A1 - Eckert, Sabine A1 - Gerhard, Marc A1 - Meyer, Elisabeth I. A1 - Mutz, Michael A1 - Reich, Michael A1 - Weiss, Ilga T1 - Coarse Woody Debris Quantity and Distribution in Central European Streams T2 - International Review of Hydrobiology KW - coarse woody debris Y1 - 2000 U6 - https://doi.org/10.1002/(SICI)1522-2632(200003)85:1<5::AID-IROH5>3.0.CO;2-X SN - 1522-2632 VL - 85 IS - 1 SP - 5 EP - 23 ER - TY - GEN A1 - Bolz, Sebastian A1 - Oehring, Michael A1 - Lindemann, Janny A1 - Pyczak, Florian A1 - Paul, Jonathan A1 - Stark, Andreas A1 - Lippmann, Thomas A1 - Roth-Fagaraseanu, Dan A1 - Schreyer, Andreas A1 - Weiß, Sabine A1 - Schrüfer, Susanne T1 - Microstructure and mechanical properties of a forged beta-solidifying gamma TiAl alloy in different heat treatment conditions T2 - Intermetallics Y1 - 2015 VL - 2015 IS - 58 SP - 71 EP - 83 ER - TY - GEN A1 - Schulze, Marcus A1 - Seidlitz, Holger A1 - König, Franziska A1 - Weiß, Sabine T1 - Tribological Investigations of PVD Coated Multi-Layer Constructions T2 - Journal of Materials Science Research N2 - Multi-layer constructions become more and more relevant in lightweight applications due to their high strength to weight ratio. They offer excellent crash, damping and recycling properties. Also, the morphology of thermoplastic carbon fibre reinforced plastics (CFRP) render them interesting for large scale manufacturing processes. Nevertheless, a major disadvantage results in a poor resistance against wear and tear, e.g. erosion, which is attributed to weak hardness properties. Hence, this work deals with tribological investigations on orthotropic carbon fibre reinforced polymers (PA 6) either with protective ceramic coating or without. The chosen coating system is a well-known protective covering of metal components, e.g. metal cutting tools, produced by physical vapor deposition (PVD). To characterize the coating system on thermoplastic CFRP, standard analyzing methods are utilized, like optical and scanning electron microscopy (SEM). The tribological investigations are conducted by the tribological ball on disk method to generate wear tracks on the sample surfaces and hence to calculate the wear rates. These results are compared to literature findings with respect to a certain protective coating system (TiN) and a second nano-structured gel coating system, where both systems are deposited on a thermosetting material, i.e. carbon fibre reinforced epoxy resin, respectively. For this purpose the feasibility of depositing a protective ceramic layer on thermoplastic CFRP is demonstrated. First results on suitable surface pre-treatments have shown a significant influence on the coating quality. The improved performance regarding the wear behavior with respect to tribology compared to the poor substrate and existing technologies is shown additionally. KW - thermoplastic composites KW - protective coating systems KW - tribology KW - wear KW - physical vapour deposition Y1 - 2016 U6 - https://doi.org/10.5539/jmsr.v5n1p97 SN - 1927-0585 VL - 5 IS - 1 SP - 97 EP - 106 ER - TY - GEN A1 - Oehring, Michael A1 - Lindemann, Janny A1 - Pyczak, Florian A1 - Paul, Jonathan A1 - Stark, Andreas A1 - Lippmann, Thomas A1 - Schrüfer, Susanne A1 - Roth-Fagaraseanu, Dan A1 - Schreyer, Andreas A1 - Weiß, Sabine T1 - Microstructure and mechanical properties of a forged β-solidifying γ TiAl alloy in different heat treatment conditions T2 - Intermetallics N2 - In the cast condition g titanium aluminide alloys that solidify completely through the b phase are characterized by fine and homogeneous microstructures, weak textures and low segregation. For these reasons such alloys have a relatively good workability and can be closed-die forged without preceding ingot breakdown even if the alloys contain no large fractions of the b phase at the working temperature. The present work was devoted to a combined study of the constitution and microstructural morphologies that develop in various two-step heat treatments of a single-step forged b solidifying alloy. The study included high-energy X-ray diffraction for in situ investigations of the constitution at the heat treatment temperature. It was observed that the phase ransformations are quite sluggish in the material which results in fine microstructures and some conditions that significantly deviate from thermodynamic equilibrium. Further, tensile and creep testing was carried out on the different material conditions in order to identify the range in which the properties can be varied. It is found that this easily forgeable material exhibits comparable strength, ductility and creep strength as more conventional peritectically solidifying alloys. KW - TiAl KW - Titanium Aluminides KW - hot die forging KW - TNB-V4 Y1 - 2015 UR - http://www.sciencedirect.com/science/article/pii/S096697951400301X U6 - https://doi.org/10.1016/j.intermet.2014.11.008 SN - 0966-9795 VL - 2015 IS - 58 SP - 71 EP - 83 ER - TY - GEN A1 - Kazak, Fedor A1 - Weiß, Sabine T1 - Test procedure for fatigue investigations regarding structured sheet metal joints T2 - Materials Testing N2 - The topic of fatigue strength of joints of flat and honeycomb-structured thin sheets has not yet been adequately studied. This concerns, for example,the development of an appropriate test method. In many cases, there is still a lack of information, how effective joints of flat and structured sheet metals are in omparison with reference joints of flat sheets. Combinations of resistance spot-welded specimens of flat and honeycomb-structured thin sheets of deep-drawing steel DC04 with a thickness of 0.5 mm were examined. Adopted clamping plates were applied for the testing. Joined smooth specimens were used as a reference material. The analysis of the frequency [1] was applied for comparison. The fatigue limit of a joint of a flat and a structured sheet metal is not significantly affected by spot welding. The fatigue limit of these spot-welded joints is comparable to that of an non joined honeycomb-structured sheet. By means of frequency or stiffness analysis, stability and damage mechanisms of differently shaped joints were explained. The joining of bridges of the structure shows a better stability than the combination of honeycombs. The stiffness analysis is a favored method for the clarification of the damage mechanisms in a spot-welded joint. The reasons for the low fatigue strength values of the joined flat-structured specimens compared to flat-flat joints are strong notch effects in the bridge area and momentum effects by the structure height of the studied honeycomb structure. The spot weld with a pronounced indentation also affected the fatigue strength of both flat and structured joined sheet metals. Y1 - 2016 SN - 0025-5300 SN - 2195-8572 VL - 58 IS - 2 SP - 109 EP - 116 ER - TY - GEN A1 - Kazak, Fedor A1 - Weiß, Sabine T1 - Comparability of structured and flat reference specimens made of thin sheet metal T2 - Materials Testing N2 - The literature review reveals that the honeycomb-structured thin sheet metals are not adequately investigated with regard to their fatigue strength. A question that remains almost completely ignored in the process is the direct comparability of structured thin sheet metals with flat reference specimens. A thin sheet is not a classic specimen to determine the fatigue strength because of the known problem of the fracture mechanics. Structured thin sheet metals of deep-drawing steel DC04 with a thickness of 0.5 mm were examined. Flat specimens were used as reference material. The frequency analysis was used for comparison. Fundamental differences in the mechanical behavior between flat and structured sheets under cyclic load were observed. Whereas an extremely flat S-N curve in the low-cycle region with a high slope coefficient was observed for the smooth thin sheets, the structured specimens show a curve typical for notched specimens. Moreover, the smooth sheets have a specific cyclic hardening and/or softening behavior. The state of plane stress of a fine sheet in contrast to a multi-axial one for the structured sheet complicates the direct comparison. For this reason, such a comparison with respect to their fatigue strength in the Wohler diagram should only be considered with caution. Y1 - 2015 U6 - https://doi.org/10.3139/120.110748 SN - 0025-5300 SN - 2195-8572 VL - 57 IS - 6 SP - 567 EP - 573 ER - TY - GEN A1 - Weiß, Sabine A1 - Mitevski, Bojan T1 - Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs T2 - Materials N2 - Coronary heart disease is still one of the most common sources for death in western industrial countries. Since 1986, a metal vessel scaffold (stent) has been inserted to prevent the vessel wall from collapsing. Most of these coronary stents are made from CrNiMo­steel (316L). Due to its austenitic structure, the material shows a good combination of strength, ductility, corrosion resistance, and biocompatibility. However, this material has some disadvantages like its non-MRI compatibility and its poor fluoroscopic visibility. Other typically used materials are the Co­Base alloys L-605 and F-562 which are MRI compatible as well as radiopaque. Another interesting fact is their excellent radial strength and therefore the ability to produce extra thin struts with increased strength. However, because of a strut diameter much less than 100 μm, the cross section consists of about 5 to 10 crystal grains (oligo­crystalline). Thus, very few or even just one grain can be responsible for the success or failure of the whole stent. To investigate the relation between microstructure, mechanical factors and stent design, commercially available Cobalt-Chromium stents were investigated with focus on distinct inhomogeneous plastic deformation due to crimping and dilation. A characteristic, material related deformation behavior with predominantly primary slip was identified to be responsible for the special properties of CoCr stents. Y1 - 2015 U6 - https://doi.org/10.3390/ma8052467 SN - 1996-1944 VL - 8 IS - 5 SP - 2467 EP - 2479 ER - TY - GEN A1 - Naveed, Muhammad A1 - Flores Renteria, Arturo A1 - Nebel, Daniel A1 - Weiß, Sabine T1 - Study of high velocity solid particle erosion behaviour of Ti2AlC MAX phase coatings T2 - Wear N2 - This research work provides information about the influence of Ti2AlC MAX phase coatings on the erosion resistance of Ti624 2alloy.Flat specimens were coated witha20 µm Ti2AlC film using an industrial siz emagnetron sputtering coater and annealed at 800 °C for 1h in vacuum for the formation of the MAX phase.The erosion resistance of the specimens was tested using high velocity particles at room temperature.The results indicate that the erosion resistance of Ti6242 has been significantly enhanced by the employment of MAX-phase coatings. This demonstrates the capability of using MAX phase coatings as erosion protective medium for engine components exposed to similar damage conditions. Additionally,the results show that uncoated Ti6242 samples with duplex microstructure have a better durability against erosion attack compared to uncoated samples with globular microstructure. KW - Erosion, MAX Phase Y1 - 2015 U6 - https://doi.org/10.1016/j.wear.2015.09.014 SN - 0043-1648 VL - 2015 IS - 342-343 SP - 391 EP - 397 ER - TY - GEN A1 - Naveed, Muhammad A1 - Obrosov, Aleksei A1 - Weiß, Sabine T1 - Investigation of the wear resistance properties of Cr/CrN multilayer coatings against sand erosion T2 - Conference Papers in Science N2 - The wear of metallic components used in gas and steam turbines due to erosive sand particles lead to a tremendous decrease in their lifetime. This wear can be reduced by the use of suitable erosion resistant coatings resulting in lower maintenance costs. In this context, multilayer Cr/CrN PVD coatings using an industrial coater was designed and applied on Inconel 718, a material which finds its application in gas turbines. A variation in the bimodal period has been induced in order to achieve an optimal coating architecture providing optimum properties needed for the erosion resistant coatings. The coating was deposited using a single Cr- target with an induction of N2 during the nitriding phase at a temperature of 480-500 °C and the coating thickness of 24-26 µm was kept constant throughout. The erosion tests were conducted at angles of 30°, 60° and 90°. The sand used for the test is an irregular shaped SiO2. The erosion tests were followed by a detailed microscopic examination of the eroded coating structure in combination with nanoindentation and scratch tests. KW - Cr/CrN multilayer, Erosion, PVD, Coatings Y1 - 2015 U6 - https://doi.org/10.1155/2015/873543 N1 - Article ID 873543 VL - 2015 SP - 1 EP - 10 ER - TY - CHAP A1 - Mlikota, Marjo A1 - Schmauder, Siegfried A1 - Mitevski, Bojan A1 - Weiß, Sabine ED - Deng, Jiamei ED - Liu, Quingjun T1 - Scientific Multiscale and Multidisciplinary Analysis of Deformation and Damage in the Case of Oligocrystalline Structures T2 - Computer Science and Engineering Technology N2 - This paper serves as an overview of the ongoing research in the field of multiscale and multidisciplinary analysis of deformation and damage in the case of oligocrystalline structures. The research focuses on experimental measurement and numerical calculation of ductile failure in the X2CrNiMo18-15-3 (AISI 316L) stainless steel. An embedding numerical technique is employed where crystal plasticity theory is used to represent plastic deformation in the material and element removal technique based on Rice&Tracey damage model for ductile void growth to simulate damage initiation inside the material, which is observed in the experiments. Additionally, the crystal plasticity model is supported by a hierarchical multiscale approach connecting nano-, micro- and meso-scales. Y1 - 2016 SN - 978-981-4651-00-4 SP - 113 EP - 118 PB - World Scientific Publishing CY - Singapore ER - TY - GEN A1 - Schulze, Marcus A1 - Seidlitz, Holger A1 - König, Franziska A1 - Weiß, Sabine T1 - Nanoindentation measurements of PVD coated multilayer constructions T2 - Journal of Achievements in Materials and Manufacturing Engineering N2 - Carbon fibre reinforced thermoplastics (CFRP) are intensively used in lightweight applications due to their high strength to weight ratio. In addition they offer good crash, damping and recycling properties. On the basis of their morphology they are suitable for large scale manufacturing processes. A major disadvantage consists of its poor hardness properties, which is again an important requirement to realize a good erosion and wear behaviour. Design/methodology/approach: In this work the application of orthotropic carbon fibre reinforced polymers (PA6), with protective TiAlN coatings, produced by physical vapor deposition (PVD), is investigated. The characterization of the coating is performed by nanoindentation tests, roughness measurements and scanning electron microscopy. Furthermore micro hardness tests on selected well prepared cross sections are conducted, to compare the coating quality with established coating systems. Findings: By applying TiAlN coating, the hardness of the CFRP samples can be increased substantially up to 15 GPa, in comparison to the basic substrate. In addition the quality of the coating surface can be improved significantly by plasma etching pre-treatment. Research limitations/implications: The presented findings are preliminary results to prove the application of a standard processed ceramic coating on new composite types for mass production. The PVD coating process as well as the utilized testing methods are suitable to realize hard coatings on thermoplastic CFRP. This effect can be exploited for several lightweight applications to increase the erosion and wear resistance of composite materials. Originality/value: The presented results show, that ceramic coatings can be deposited on standard thermoplastic CFRP with polyamide 6 matrix. Therewith it can be expected, that the PVD coating process can make a essential contribution to increase the range of applications. KW - Nanoindentation KW - Thermoplastic composites KW - TiAlN-coating Y1 - 2015 UR - http://www.journalamme.org/vol72_2/7221.pdf SN - 1734-8412 VL - 72 IS - 2 SP - 53 EP - 60 ER - TY - GEN A1 - Schulze, Marcus A1 - Seidlitz, Holger A1 - König, Franziska A1 - Weiß, Sabine T1 - Highly wear resistant PVD coatings for CFRP based multi-layer construction T2 - 11th International Scientific-Technical Conference on Advances in Plastics Technology (APT'15) Y1 - 2015 SN - 978-83-63555-47-4 CY - Gliwice ER - TY - GEN A1 - Stechow, Richard A1 - Ivanova, Irina A1 - Naveed, Muhammad A1 - Weiß, Sabine T1 - Sample Preparation of Worn Surfaces for EBSD Analysis T1 - Probenpräparation verschlissener Oberflächen für die EBSD Analyse T2 - Praktische Metallographie Y1 - 2016 U6 - https://doi.org/10.3139/147.110401 SN - 0032-678x SN - 2195-8599 VL - 53 IS - 6 SP - 352 EP - 359 ER -