The friction and wear behaviours of hard carbon coatings have been stu
died mainly at low sliding speed. This paper presents a study at high
sliding speed (30-35 m s(-1)). Various types of hard carbon coatings w
ere deposited on stainless steel (304L) pins. These coatings are produ
ced by plasma-assisted chemical vapour deposition processes under diff
erent deposition conditions, The surface properties and morphology of
the coatings have been characterised by surface analysis methods such
as scanning electron microscopy and Raman spectrometry. The coated pin
s slide against a steel XC30 rotating disc. The hardness of disc after
heat treatment is 5 GPa. The experimental results show that these coa
tings exhibit very low friction coefficients and high wear resistances
. This behaviour of hard carbon coatings can be explained by the simul
taneous presence of the sp(3) and sp(2) bonds hybridisation, by the ca
rbon-hydrogen clusters on the surface of these films, and by hydrogen
desorbing from the hard carbon films during friction inducing their re
construction or creating on them double (pi, sp(2)) bonds.