STUDY ON W GRADED DOPING DLC COMPOSITE FILMS WITH MULTICOMPONENT TRANSITION LAYER

W graded doping diamond-like carbon (DLC) composite films with multicomponent transition layer were deposited onto silicon, high speed steel and/or stainless steel wafers using ion beam assisted mid-frequency unbalanced magnetron sputtering technique, and the influences of W target current on the composition, structure and properties of the DLC films were investigated. With increasing W target current, the contents of W and its carbides in the films increase, but the contents of sp3 structure decrease. Although there might be some metal droplets on the surface of the as-prepared samples, the distribution of each element is basically homogenous over the whole surface, and the roughness of sample keeps quite low value, which is in the range of 7.56-15.8 nm. The nanohardness (H), elastic modulus (E), and their ratio, H/E, increase with increasing W target current. The critical loads in scratch test of the as-prepared samples increase with the increase of W target current and are in the range of 80-100 N, indicating very strong adhesions between the films and substrates. Under ambient circumstance, the friction coefficients of the coated samples increase but the wear rates decrease obviously.