Amorphous diamond-like carbon films grown by magnetron sputtering have been deposited on silicon nitride based substrates for tribological purposes. A conductive Si3N4/30% vol.TiN composite was produced for bias substrate application. Friction and wear properties of carbon coated self-mated pairs were assessed using a reciprocal motion ball-on-flat setup in unlubricated conditions with applied normal loads of 3 N and 5 N. The worn surfaces were studied by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) in order to identify the prevalent wear mechanism. Unbiased and biased substrates behaved differently, the former undergoing premature delamination while the latter endured the tribological test conditions (3 N, similar to 43 m). Very low friction coefficient values of similar to 0.015 were sustained assuring remarkable wear behaviour. Surface grooving and wear debris accumulation in the sliding track lead to a roughness increase from the nominal rms value of similar to 12 nm to similar to 97 nm, although no weight loss and surface profile modification was quantifiable. (c) 2006 Elsevier B.V. All rights reserved.