Creation of ultra-low friction and wear surfaces for micro-devices using carbon films

A great many of the micro-mechanical devices employ sliding contact between moving parts. Such devices include, for example, micro-engines, micro-motors, and near-contact or contact recording hard magnetic disk drives. In these devices, the tribological phenomena (friction, wear and stiction) largely determine device efficiency and durability. The newly developed carbon films show ultra-low friction (<0.05), low wear coefficient (<10−8), and high contact angle of water (>85°). These films have extremely low adhesion to the mating surface, which results in ultra-low friction and high contact angle. The hardness and elastic modulus, however, are lower than those of the hard diamond-like carbon (H-DLC) films, but the hardness-to-modulus ratio is comparable. Despite their low hardness (2-10 GPa), these carbon films could be used as protective layers in micro-mechanical devices because the applied loads in such devices are very low and the contact area is relatively large. In this study, the friction and wear properties of the carbon films are determined by a new oscillating, compliant cantilever beam method, and the results are summarized and discussed.