Surface analysis of different boundary layers on steel discs formed in a lubricated tribocontact during laboratory test compared with field application

Abstract

The aim of this study was to gain knowledge of tribological layers on a steel disc. This steel disc has been used in a transmission system in the field. ATF-oil (automatic transmission fluid), which contains different surface-adhering additives, serves as a lubricant and as a cooling fluid in the tribological system. Over time, the tribological characteristics of the system changed. Special interest in this study lies in the modifications of the steel surface. The field-used disc was therefore compared with model tested discs. In a disc-on-disc tribometer, all samples are tested for a short period of time to evaluate the actual condition of the system regarding friction behaviour. Analysis and characterisation of surfaces and layer formation were carried out with, among other techniques, 3D topography, SEM / EDX, AFM, XPS, and ToF-SIMS. Results indicate that in some regions a complex composed tribological layer is formed. Differences were detected between the steel discs used in the field and the model discs. This indicates the problem of evaluation of long-term behaviour exclusively by use of short or accelerated model experiments. A combination of carefully selected and sophisticated analytical methods is necessary to trace small changes of the system.

Electrospray ionization and atmospheric pressure matrix‐assisted laser desorption/ionization mass spectrometry of antioxidants applied in lubricants

“…Previous research indicates that the tribologically (i.e. interacting surfaces in relative motion to each other) built thin layers on the surface are formed by additives and degradation products of the additives which were present originally in the base lubricant 9, 10. It was also shown that chemical changes on the surface are primarily responsible for the tribological behavior and not topographical changes of the surface 10.…”

“…interacting surfaces in relative motion to each other) built thin layers on the surface are formed by additives and degradation products of the additives which were present originally in the base lubricant 9, 10. It was also shown that chemical changes on the surface are primarily responsible for the tribological behavior and not topographical changes of the surface 10. For a better understanding of the tribosystem it is essential to enhance knowledge of the chemical composition of the lubricant and its surface layer 9–12.…”

“…It was also shown that chemical changes on the surface are primarily responsible for the tribological behavior and not topographical changes of the surface 10. For a better understanding of the tribosystem it is essential to enhance knowledge of the chemical composition of the lubricant and its surface layer 9–12. Therefore, methods have to be established which can determine the chemical structures and quantities of additives with special emphasis being placed on antioxidants in this paper.…”

Effects of phosphorus on friction behaviour in wet clutch systems: A comparison of various coatings

“…Steel discs placed above and below ran against a rotating friction (pad) disc in the middle under lubricated conditions. The tribometer's configuration enables tests up to 100 rounds/min, corresponding to a mean sliding velocity of approximately 40 m/s [8]. Tests were performed in ambient air.…”

Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry of Friction Modifier Additives Analyzed Directly from Base Oil Solutions

“…22,23 These tribolayers are generally formed by additive molecules as well as reaction products of both the additives and the base lubricant. 24 As tribolayers alter the contact surface they are the main influence on changes in friction behavior of a tribological system. Knowledge about what chemical composition of surface layers is to be expected from certain lubricants is essential for improvement of the design of both contact surfaces and the lubricant formulation.…”