Abstract
Understanding how an adaptive integrated interface between lubricant additives and solid contacts works will enable improving the wear and friction of moving engine components. This work represents the comprehensive characterization of compositional and structural orientation at the sliding interface from the perspective of surface/interface tribochemistry. The integrated interface of a lubricant additive-solid resulting from the friction testing of Graphite-like carbon (GLC) and PVD-CrN coated rings sliding against cast iron under boundary lubrication was studied. The results indicate that in the case of the CrN/cast iron pair the antiwear and friction behavior were very strongly dependent upon lubricant. In contrast, the tribology of the GLC surface showed a much lower dependence on lubrication. In order to identify the compounds and their distribution across the interface, x-ray microanalysis phase mapping was innovatively applied and the principle of hard and soft acids and bases (HSAB) to understand the behaviour. Phase mapping clearly showed the hierarchical interface of the zinc-iron polyphosphate tribofilm for various sliding pairs and different sliding durations. This interface structure formed between lubricant additives and the sliding surfaces adapts to the sliding conditions – the term adaptive interface. The current results help explain the tribology of these sliding components in engine.
Highlights
Achieving the optimum lubrication and friction in automotive applications, represents a potential for reduced energy consumption and reduced emissions
The friction and wear characteristics of chromium nitride (CrN)/cast iron and CrN + Graphite-like carbon (GLC)/cast iron tribo pairs were evaluated under an increasingly oil-starved condition, each rubbing pair was subjected to multiple test durations of 1, 2, 4, and 8 hours
The friction increased gradually for CrN/cast iron, but the opposite was observed for CrN + GLC/cast iron pairs
Summary
Achieving the optimum lubrication and friction in automotive applications, represents a potential for reduced energy consumption and reduced emissions. Intensive work has been carried out to evaluate the interactions between non-ferrous coatings and lubricant additives with regard to wear and friction plus the interfacial chemistry of the tribofilm, e.g. the CrN/steel and DLC/steel contacts[7,8,9,10]. Qu et al.[10] showed the increasing wear rate on the steel opposing DLC was correlated with the DLC-catalysed, high rate tribochemical reactions with organophosphate additives These studies highlight that the tribofilm formation and interactions between additives and rubbing contacts are taking place, but they do not provide a comprehensive understanding of the working mechanics of the integrated interface. The friction-induced pattern of compound formation and their disposition with respect to the surface is revealed
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
