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Relating Tribological Performance and Tribofilm Formation to the Adsorption Strength of Surface-Active Precursors
- Source :
- Tribology Letters. 68
- Publication Year :
- 2019
- Publisher :
- Springer Science and Business Media LLC, 2019.
-
Abstract
- Mechanochemical reactions induced by external stress provide a unique approach for in situ synthesis of carbon tribofilms that can improve friction and wear performance. In this work, we studied how tribofilm formation and tribological performance might be related to the adsorption strength of three additives in polyalphaolefin (PAO4) as base oil, viz., cyclopropanecarboxylic acid (CPCa), cyclopropanemethanol (CPMA), and 1-cyclopropylethanol (CPEA) as characterized by two different surface-active groups –COOH and –OH. Tribo-testing results reveal that addition of 2.5 wt% CPCa to PAO4 gave the lowest friction coefficient and wear volume. FTIR and Raman analysis demonstrate substantial tribofilm formation only in the case when CPCa was used as the oil additive, not CPMA or CPEA, in spite of the fact that all three additives contain the same metastable cyclopropane ring. Thermogravimetric analysis and molecular dynamics simulations indicate the stronger adsorption of CPCa on the iron oxide surface compared with CPMA and CPEA. Weak adsorption of the latter molecules results in their desorption from the surface due to flash heating during tribotesting before they have the chance to participate in mechanochemical reactions required for tribofilm formation. The stronger binding of CPCa to the steel surface is a necessary condition for this type of surface mechanochemistry and appears critical to the efficient formation of carbon-containing tribofilms under our tribo-testing conditions.
- Subjects :
- Thermogravimetric analysis
Materials science
Mechanical Engineering
Iron oxide
chemistry.chemical_element
Surfaces and Interfaces
Tribology
Surfaces, Coatings and Films
chemistry.chemical_compound
Adsorption
chemistry
Chemical engineering
Mechanics of Materials
Desorption
Mechanochemistry
Carbon
Oil additive
Subjects
Details
- ISSN :
- 15732711 and 10238883
- Volume :
- 68
- Database :
- OpenAIRE
- Journal :
- Tribology Letters
- Accession number :
- edsair.doi...........fdc43b0888e5adfa5d4e71b75aeb72d9
- Full Text :
- https://doi.org/10.1007/s11249-019-1249-5