  In this present work, friction and wear behavior of UNCD thin film has been
studied against three different sliding counterbodies i.e. Al2O3, SiC and steel
balls. UNCD/steel sliding pair showed high friction coefficient in the
beginning of the sliding process which decreased to the lower value after
longer sliding passes. This behavior might be explained by oxidation mechanism.
However, high friction value was observed in the case of UNCD/SiC and this was
attributed to strong adhesive force acting across the sliding interfaces.
Stable and low friction value was measured in UNCD/Al2O3 sliding combination.
This was governed by chemically inert interfaces and graphite tribolayer
formation.
