Plasmonic Diagnostics for Tribology: In Situ Observations Using Surface Plasmon Resonance in Combination with Surface-Enhanced Raman Spectroscopy

Abstract

The generation of transfer films is a common wear and lubrication mechanism of solid lubricants, such as polymers and lamellar solids. Material can transfer from a solid lubricant to a counter surface as early as the first cycle of sliding, initiating the formation of a transfer film, which can persist for the duration of sliding. Surface plasmon resonance (SPR) was used to monitor incipient molecular wear of a solid lubricant as performed here using a gold coated (50 nm) quartz prism in situ during sliding experiments. Surface-enhanced Raman spectroscopy (SERS) is a complementary technique enabling the analysis of ultra-thin transfer films. SPR and SERS experiments confirm that polytetrafluoroethylene and graphite transfer readily, with observed changes in SPR signal after one cycle of sliding, while ultra-high-molecular-weight polyethylene shows little transfer to the gold during sliding in the in situ SPR experiment. This shows the feasibility of SPR and SERS as important diagnostic tools for tribological studies.