Friction and wear behavior of hydrogenated diamond-like carbon coating against titanium alloys under large normal load and variable velocity

The effects of reciprocating frequency large normal load on friction and wear behavior of hydrogenated diamond-like carbon (H-DLC) coating against Ti-6Al-4V ball were studied under dry and lubricated conditions. SEM energy dispersive spectroscopy and Raman spectroscopic analyses show that as reciprocating frequency increases under lubricated conditions the friction coefficient decreased first and then increased. When the reciprocating frequency was 2.54 Hz the value of friction coefficient reached the minimum. The friction reduction is attributed to the transformation from sp³ to sp² the formation of transfer layer on Ti-6Al-4V ball and the reduction in viscous friction while the increase of friction coefficient is related to wear. In dry conditions the friction coefficient was between 0.06 and 0.1. The service life of H-DLC coating decreased with the increase in reciprocating frequency and normal load. These results are helpful for application of diamond-like carbon coating.