Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (44)
- Beitrag zu einem Tagungsband (17)
- Vortrag (16)
- Beitrag zu einem Sammelband (9)
- Buchkapitel (2)
- Sonstiges (2)
Sprache
- Englisch (55)
- Deutsch (33)
- Französisch (2)
Schlagworte
- Wear (20)
- Friction (18)
- DLC (14)
- Tribology (13)
- Laser-induced periodic surface structures (LIPSS) (8)
- Slip-rolling (8)
- Roughness (6)
- Simulation (5)
- Wälzen (5)
- ZrCN (5)
Organisationseinheit der BAM
- 9 Komponentensicherheit (25)
- 9.5 Tribologie und Verschleißschutz (25)
- 6 Materialchemie (9)
- 6.2 Material- und Oberflächentechnologien (9)
- 6.7 Materialsynthese und Design (2)
- 5 Werkstofftechnik (1)
- 5.1 Mikrostruktur Design und Degradation (1)
- 6.6 Physik und chemische Analytik der Polymere (1)
- 8 Zerstörungsfreie Prüfung (1)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (1)
Eingeladener Vortrag
- nein (16)
Adhesion measurements are presented which were carried out with an atomic force microscope between polymer balls attached to a cantilever and a silicon wafer under ultra high vacuum conditions. In using a silicon surface with a defined structure a correlation between adhesion force and contact area was found. This correlation could partly be explained by the Johnson-Kendall-Roberts model, if a change of the surface energy is assumed as a result of the structuring. For a constant geometric contact area an additional structuring leads to a decrease of the adhesion force.
A novel tribometer has been designed using commercially available components for sliding motion at 40kHz with amplitude between 2.5 and 5µm. The tribometer is equipped with means to measure amplitude, frequency, power required to keep the sample in motion and load applied. The effective motion between the two contacting bodies is monitored. These data are used to evaluate the coefficient of friction. The wear rate was determined after the tests. The set-up was tested using novel, non-commercial substrates such as AlFeCrTi-alloys and tungsten carbide-based coatings as well as Magnéli-type coatings (Tin-2Cr2O2n-1 and TinO2n-1). This paper presents the principle of the ultra-high frequency tribometer and first tribological quantities of materials and coatings tested.
Diamond like carbon (DLC)-coatings are applied very successfully on computer discs. Sliding friction tests confirm their high performance as dry lubricants with friction coefficients (COFs) below 0.1. In contrast to sliding tests, until very recently most of the DLC-coatings failed in slip-rolling test after fewer cycles than uncoated samples. However, present tests with DLC-coatings of seven different suppliers show a more promising tribological behaviour under slip-rolling conditions. The DLC-coatings were deposited onto steel 100Cr6, HRC 60, with a thickness of 23 ?m. The counter bodies were uncoated, grinded or polished 100Cr6 discs with 30 mm radius of curvature. The tests were performed on a twin disc testing rig (Amsler type) with paraffin oil under boundary/mixed lubrication and rolling with 10% slip. The initial, average Hertzian contact pressure was adjusted to Pm = 1.0, 1.25, and 1.5 GPa. The failure criterion was defined as the occurrence of a single damaged area larger than 1 mm2, which was controlled by optical microscopy (OM). An acoustic emission (AE) measurement system was installed as an additional online control for coating failure. The stressed coatings and the chipping areas were analyzed by OM, SEM, EDX, AFM and Raman spectroscopy.
Until now, the results reveal that a large scatter in lifetime of coatings occurs not only between samples of different coaters but also between the samples of one single batch. The highest lifetime reached by a DLC-coating under these testing conditions is 10 × 106 cycles. That is the highest life time for a coating tested under the testing conditions above in our laboratory so far. The following factors were identified to influence the life time of the coatings: coating thickness, interlayer type, topography of the coatings, counter body roughness and mechanical properties. But the most important factor determining the life time of the coatings is that the coating process does produce homogenous layers free of faults.
JATROPHA - The seed of energy CO2-neutral fuels and lubricants based on sustainable non-food oils
(2009)
Costs reduction is one of the major objectives in mechanical applications with a parallel increase of the power output. Another driver represents new environmental standards and their increasing restrictions in the automotive industry leading to the question, if materials based concepts may substitute harmful EP/AW additives in lubricants. This paper presents the slip-rolling resistance of different DLC/THC coatings on steel substrates with a definite slip rate of 10%. Industrial DLC coatings of ta-C and a-C:H types from various manufacturers were deposited on steels SAE 52100 and AMS 5898 to compile the slip-rolling resistance under initial average Hertzian contact pressures between 1.5 GPa and 2 GPa. The tests were carried out on Amsler-type twin disc tribometer under the regime of mixed/boundary lubrication in unadditivated paraffinic oil (ISO VG 46) and a factory fill engine oil. The spherical steel sample was uncoated and the cylindrical coated with DLC. Some coatings achieved 10 million cycles without any damage under a maximal Hertzian contact pressure Pmax well over 2.25 GPa, thus exceeding FZG 12.
High-power piezo-electric motors with power densities of 1.4 kW/kg display a potential for substituting hydraulic actuators. For this application, two novel tribometers of the same type have been designed using commercially available components for sliding motion at 40 kHz with amplitudes between 2.5 µm and 5 µm. The tribometers are equipped with means to measure amplitude, frequency, power required to keep the samples in motion and load applied. The effective motion between the two contacting bodies is monitored in each of the tribometers. These data are used to evaluate the coefficient of friction. The wear rate was determined after the tests. The set-ups were tested using well-known 100Cr6H (AISI 52100) samples before investigating novel, non-commercial substrates such as AlFeCrTi-alloys and tungsten carbide-based coatings as well as Magnéli-type coatings (Tin-2Cr2O2n-1 and TinO2n-1). This paper presents the principle of the ultra-high frequency tribometers and first tribological quantities of materials and coatings tested up to and above 1011 cycles. Very low wear rates in the range 10-8 mm³/Nm down to 10-10 mm³/Nm were determined under dry oscillation in air.
Der Einfluss des E-Moduls und des Grundöls auf das Wälzverhalten von DLC- und Diamantbeschichtungen
(2005)
Zero wear (Null Verschleiß)
(2013)
Das CargoLifter Ballonkransystem nutzt die Prinzipien der Leichter-als-Luft-Technologie für das Heben von Gütern. Der mit leichtem Gas gefüllte Ballon drängt in der schwereren Luft nach oben und kann somit Lasten anheben. Im Gegensatz zu erdgebundenen Kränen ist für den Luftkran die Beschaffenheit des Bodens sekundär. Der Ballonkran wird an drei Winden verankert und über die im Kranknotenpunkt zusammengeführten Seile präzise gesteuert. Beim Heben und Versetzen verbleibt die Last unter dem Ballon, der stets 100% seiner Hubkraft auch bis zu 200m Höhe und selbst weiterem Versatz behält. Reichweite bedeutet beim CargoLifter Ballonkransystem statt mehr Ausleger mehr Seil.
The light-weight approach and fuel economy targets in today's automotive engineering require tribosystems, which can withstand higher contact pressures associated with low coefficients of friction. The application of high-performance coatings represents one approach among others. This paper presents some recently developed DLC coatings (a-C:H and ta-C) as well as a novel coating-substrate system (Zr(C,N)) in a benchmark test procedure under slip-rolling conditions in the presence of liquid lubricants. Various coatings with different thickness, interlayer and substrates were evaluated for their slip-rolling resistance in different lubricants at ambient temperature and at 120 °C. Results indicate that some of these coating systems can withstand at least 10 million cycles under initial Hertzian contact pressures of up to Pmax = 3.500 MPa and oil temperatures of at least 120 °C associated with low coefficients of friction under mixed/boundary conditions. Surface of the coatings and the counter bodies were analysed and compared with untreated substrates.
Zero wear (Null Verschleiß)
(2012)
Recent developments in contact mechanics and microfribology have shown that it is very important to study surface modification effects for quantification of „Zero wear“ (plastic deformation of upper parts of asperities) during sliding friction. The present work considers experimental and Simulation data on the Formation of elastic and plastic contact areas during sliding friction on rough surfaces. The Simulation of discrete contact was carried out using as a source the AFMimages of real surface topography at micro/nanoscale.
The approach for quantification of „zero wear“, proposed here, is not using common Statistical Parameters of roughness, but it considers contact areas on asperities.
In these areas some regions are undergoing plastic deformation which influences surface Transformation during sliding friction. Also, the workhardening effect was taken into account in the Simulation
of sliding friction. This enabled a rnore successful fit of experimental data. The results obtained of the Computer simulations will provide a way of studying friction force at the initial stage of the running-in process.
Das CargoLifter-Ballonkransystem nutzt die Prinzipien der Leichter-als-Luft-Technologie für das Heben von Gütern. Der mit leichtem Gas gefüllte Ballon drängt in der schwereren Luft nach oben und kann somit Lasten anheben. Im Gegensatz zu erdgebundenen Kranen ist für den Luftkran die Beschaffenheit des Bodens sekundär. Der Ballonkran wird an 3 Winden verankert und über die im Kranknotenpunkt zusammengeführten Seile präzise gesteuert. Beim Heben und Versetzen verbleibt die Last unter dem Ballon, der stets 100 % seiner Hubkraft auch bis zu 200 m Höhe und selbst weiterem Versatz behält. Reichweite bedeutet beim CargoLifter-Ballonkransystem statt mehr Ausleger mehr Seil.
Renowed institutions in various European countries combine their tribo-testing as well as analytical and characterisation capabilities for the European Tribology Centre. This foundation of one of the largest Open Innovative Test Beds for tribological services, the aim of the European Horizon 2020 project i-TRIBOMAT, places certain demands on the comparability of the test equipment and execution process.