Tribological properties of diamond-like carbon coatings prepared by anode layer source and magnetron sputtering

In this work we studied the tribological properties of DLC coatings prepared by two deposition techniques. The emphasis was given on double layer Cr/DLC coatings deposited by a closed drift ion beam technique (anode layer source, ALS) with C2H2 and N2 carrier gases. For comparison, the same types of substrates were coated by unbalanced magnetron sputtering in the CemeCon CC800/9 deposition system. Pin-on-disk experiments showed that the DLC coatings possess excellent wear resistance (wear rate down to 12 μm3/Nm) and also low values of coefficient of friction (down to 0.055). The presence of a carbon transfer layer, which is mainly responsible for good tribological properties, was observed on the wear scars of ball surfaces by optical microscopy. In addition, we measured the Vickers microhardness (1000-3100 HV), performed the scratch test (LC in the range 40-100 N) and Rockwell indentation test to measure adhesion. Coating surface has been analyzed by atomic force microscopy (AFM) and by profilometry.