In situ TEM studies of tribo-induced bonding modifications in near-frictionless carbon films

Direct in situ TEM evidence is presented for a mechanically-induced increase in sp2 bond content in the tribolayers formed on near-frictionless carbon (NFC) films. An in situ TEM nanomanipulation holder is used to perform sliding experiments between a nano-sized tungsten probe and electron transparent NFC samples. Electron energy loss spectra (EELS) were acquired between sliding events to show an incremental increase in the 1s-π peak, suggesting that a graphitization-like process occurs which can lead to a change in the tribological performance of a variety of hard carbon films. Presently, this behavior is only observed for one of the two varieties of NFC, while supporting TEM imaging evidence is in qualitative agreement with macroscopic friction and wear behavior.