Tribological Properties of A-C:H Thin Films Formed By the Simultaneous Application of Pulse and Dc Bias3

Ion-beam-assisted deposition is an efficient technique to synthesize metastable hard materials. However, it is difficult to apply this technique to surface modification of three-dimensional or complex shaped objects because of the line-of-sight process of ion beams. A new surface modification technique called Plasma Based Ion Implantation (PBII),. is currently being studied. This is a surface modification technique that applies negative high voltage pulses to the object immersed in a plasma, and ions in a plasma are able to irradiate in any direction to the object. In this study, carbon films were formed by the application of pulse and DC bias. The relationship between the deposition conditions, such as voltage and duty ratio, and the tribological properties of carbon films were investigated. DLC films with a low friction coefficient (0.02) and a low wear rate (6x10(exp -8)cu mm/Nm) under high conducted load (20 N) could be formed by the simultaneous application of the pulse (-2kV) of duty ratio (1%) and the DC bias (-200V) for the surface of convex and concave faces with high uniformity. The uniformity of the film thickness, structure and the mechanical property was much improved over the conventional deposition technique that uses an ion beam.