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- 2014 (9) (entfernen)
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- Atomic force microscopy (1)
- Ceramic (1)
- Ceramic wear (1)
- Fretting corrosion (1)
- Fretting fatigue (1)
- Fretting regimes (1)
- Fretting wear (1)
- Gross slip fretting (1)
- Imaging (1)
- Low IR-emission ceramics (1)
- Micro positioning (1)
- Mixed fretting regime (1)
- Performance test (1)
- Piezoelectric actuator (1)
- Polymer (1)
- Relative humidity (1)
- Roughness (1)
- Sliding speed (1)
- Stick slip (1)
- Stick-slip (1)
- Test bed (1)
- Wear scar (1)
- Wear volume (1)
- White light interferometry (1)
- Yttrium titanate (1)
- Zirconium titanate (1)
Stribeck curve
(2014)
The importance of lubricants in virtually all fields of the engineering industry is reflected by an increasing scientific research of the basic principles. Energy efficiency and material saving are just two core objectives of the employment of high-tech lubricants. The encyclopedia presents a comprehensive overview of the current state of knowledge in the realm of lubrication. All the aspects of fundamental data, underlying concepts and use cases, as well as theoretical research and last but not least terminology are covered in hundreds of essays and definitions, authored by experts in their respective fields, from industry and academic institutes.
The tribological behavior of different low infrared (IR) emission ceramic materials from the titanate group has been investigated at room temperature under gross slip fretting conditions against 100Cr6 ball bearing steel and α-alumina as the counterface materials. For all material pairs, friction and wear depended largely on the relative humidity of the environment. When paired with steel the low IR-emission ceramic disks showed higher wear resistance. Under dry conditions, almost no wear was found on the low IR-emission ceramic specimen. The high wear on the steel counter body is caused not only by tribo-oxidation, which is the main wear mechanism, but also by abrasion. In dry conditions a COF of 0.6 and in humid conditions a COF of 0.2 have been measured. When paired with α-alumina the results on wear are just opposite to those with steel counterbody and the low IR-emission ceramic materials show much lower wear resistance under all conditions. This is explained by the predominance of abrasion and the relatively large difference in hardness between the low IR-emission ceramic and α-alumina. In high humidity environments the results point to the formation of stable reaction layers causing lower friction and wear.
Fretting
(2014)
The importance of lubricants in virtually all fields of the engineering industry is reflected by an increasing scientific research of the basic principles. Energy efficiency and material saving are just two core objectives of the employment of high-tech lubricants. The encyclopedia presents a comprehensive overview of the current state of knowledge in the realm of lubrication. All the aspects of fundamental data, underlying concepts and use cases, as well as theoretical research and last but not least terminology are covered in hundreds of essays and definitions, authored by experts in their respective fields, from industry and academic institutes.
Untersucht wurden Verschleißpartikel als elektronen-transparente Proben auf dünnen Trägerfolien mit einem hochauflösendem Rasterelektronenmikroskop und energiedispersiver Röntgenspektrometrie im Transmissionsmodus. Die hohe laterale Auflösung dieser modernen Methoden ermöglicht eine morphologische Charakterisierung der Verschleißpartikel bis in den nm-Bereich. Die hochauflösende Elementanalyse erlaubt eine Interpretation der Zusammensetzung und damit Rückschlüsse auf die Verschleißpartikelbildung.
Die tribologischen Untersuchungen sind an einem Modell-Verschleißtribometer nach DIN 51834-2 geschmiert, aber ohne Ölkreislauf, durchgeführt worden. Die Präparation der Verschleißpartikel über eine Entnahme und Übertragung einer geringen Schmierstoffmenge mit einer Mikropipette auf eine TEM-Trägerfolie ist mit einem geringen Aufwand möglich. Der präparative Aufwand ist relativ gering. Das benötigte Schmierstoffvolumen beträgt wenige Mikroliter (0,001ml).
Die Untersuchung zeigt die geringe geometrische Größe der Verschleißpartikel und bestätigt indirekt die These der Reaktionsschichtbildung mit einer geringen Schichtdicke, die ständig verschleißt und sich stetig neu bildet. Die beschriebenen Verschleißprozesse sind in der Modell-Verschleiß-Prüfung mit sehr hohen Pressungen am Versuchsbeginn nachweisbar.
This paper presents a dry sliding tribo-couple (DLC/monolithic oxide ceramics), where the tribological quantities are more or less in a wide ränge independent of the sliding speed. The DLC film is composed of a specific mixture of sp3 /sp2 hybridized carbon. Self-mated ceramic/ceramic couples of MgO-Zr02, alpha-AI203 or SSiC are with their coefficients of friction above 0.45 not so lubricious, whereas the coefficients of friction of the tribocouples MgO-Zr02/DLC and alpha-AbOVDLC ranged between 0.075 and 0.15 under dry sliding. The coefficients of friction for these tribo-couples tend to decrease with increase sliding speed from 0.03 m/s to 6 m/s. The dry wear rates of the thin film is low (<10‘7 mm3/Nm) and perfectly independent from sliding velocity.
Stepping piezoelectric actuators based on the stick-slip effect inherently make use of a friction contact between strator and rotor. This contact defines not only the actuator's performance but also is prone to wear and tear. For broad use, the actuator has to be able to perform around 1 million strokes. To assess the actuator's performance in terms of force, speed, mechanical output, electrical input, and long-term stability under different load- and environmental conditions, as well as different friction partners, a dedicated test-bed for a LSPA30µXS motor by Cedrat Technologies has been set up.
In this article we demonstrate the use of atomic force microscopy (AFM) measurements for the study of macroscopic wear scars. By stitching AFM images acquired over the wear scar, the detailed structure of the scar can be characterized even when the scar is much wider than the typical maximum scan range of the AFM (50–100 µm). The results obtained by AFM are compared with those yielded by white light interferometry (WLI). The comparison validates the WLI measurements; at the same time, it shows decisive differences in the resolutions of these two methods. As a consequence, AFM measurements are necessary whenever a precise characterization of the structure of the scar is required. However, since stitching of AFM images is rather time-consuming, white light interferometry is recommended as a faster method whenever experiments are aimed at just a gross characterization of the scar and the measurement of mean quantities (e.g. the wear volume).