Wechselwirkungen zwischen gradierten diamantähnlichen Kohlenstoffschichten und additivierten Schmierstoffen

• Interactions between graded diamond-like carbon coatings and additivated lubricants

Thiex, Matthias; Bobzin, Kirsten (Thesis advisor); Stahl, Karsten (Thesis advisor)

Düren : Shaker Verlag (2021)
Book, Dissertation / PhD Thesis

In: Schriftenreihe Oberflächentechnik 64
Page(s)/Article-Nr.: XXIV, 166 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2020

Abstract

In order to meet the increasing demands on the automotive industry due to political guidelines and the growing public awareness of CO2 reduction, the need of new technological approaches is increasingly required. The use of diamond-like carbon (DLC) coatings in powertrain offers the potential to meet current and future requirements due to their friction and wear reducing effect in tribological systems. Today's lubricants and additives are designed for steel/steel contacts. Due to the growing use of DLC coatings on components of tribological systems, such as tappets, piston pins, piston rings and injection nozzles, an understanding of the physical and chemical interactions between lubricants, additives and DLC coatings is an area of research of rising importance. The overall objective of this thesis is the investigation of physical and chemical interactions between DLC coatings and industrially relevant additivated lubricants in tribological DLC/DLC contacts under boundary and mixed friction conditions. The interactions result in tribo-induced layers, which have an influence on the friction and wear behavior in tribological contacts. On the basis of the hydrogen and metal-containing diamond-like carbon coatings a-C:H:Zr (ZrCg) and a-C:H:Ti (TiCg), discrete coatings of the coating systems are deposited using magnetron sputtering technology. The characterization allows a comparison and analysis of the influence of different metals and hydrogen contents of the DLC coatings on the physical and chemical interactions. In addition, the properties of the selected lubricants will be investigated. For the tribological analysis, the parameters are derived from the guide application, the gear contact. Subsequently, the structures, chemical compositions and shearing properties of the tribo-layers on the ZrCg and TiCg coating are determined. Finally, correlations of the findings regarding the DLC coatings, lubricants and tribo-layers with the system parameters friction and wear are shown, with the aim of interpreting the physical and chemical interactions. Based on the results, it was demonstrated for which reasons the interaction between ZrCg and the additive zinc dialkyl dithiophosphate (ZnDTP) has a negative effect on the friction and wear behavior in tribological contact.