FRICTION AND WEAR BEHAVIOR OF AMORPHOUS HYDROGENATED SI1-XCX FILMS

Amorphous hydrogenated Si1-xCx films (a-Si1-xCx:H) (x = 0.65-1) were d eposited by r.f. plasma-assisted chemical vapour deposition. Their fri ction and wear properties were investigated with the help of a convent ional ball-on-disk apparatus. These results are correlated with chemic al (Si to C atomic ratio), structural (laser Raman spectroscopy) and m echanical (internal stress, hardness and elastic modulus) properties. With increasing silicon content, the film material evolves from diamon d-like carbon (DLC) to amorphous SiC-like material. Simultaneously, th e values for hardness, elastic modulus and internal stress are reduced by 15% 30%. For a low normal load (1 N) in the ball-on-disk test, a-S i1-xCx:H films (0.7 < x <0.9) show a very low wear rate of both the fi lm and the counterbody, combined with a steady state low friction coef ficient of 0.05 in a humid ambient atmosphere. For the higher loads (5 and 10 N), however, this low friction coefficient lasts for only a re latively short time. In this case, the harder DLC films perform tribol ogically better because of their higher wear resistance, low wear rate of the counterbody and generally low friction coefficient between 0.1 5 and 0.35 in a humid ambient atmosphere.