Development of Hard Carbon Films and Their Tribological Properties for the Frontier Carbon Technology Project

In Japan, a national project called the "Frontier Carbon Technology (FCT)" project has been in existence from 1998 with a five-year plan for development. This project included Research and Development of processing technologies with materials that had highly desirable mechanical properties such as low friction, high wear resistance, and high adhesion. Diamond-Like Carbon (DLC) films with excellent friction and wear properties were prepared using thermal electron excited plasma Chemical Vapor Deposition (CVD) system. This system was characterized by a pulse-bias technique. The DLC film deposited under the appropriate conditions exhibited low friction coefficients (0.03 to 0.07), and a small specific wear rate of 3x10-9-mm3/Nm; these values were superior to the desired targets of the FCT project. Adhesion of DLC film to the substrate was improved using a process consisting of Electron Cyclotron Resonance (ECR) plasma-enhanced CVD combined with high-energy ion implantation. The DLC film deposited by this system exhibited stability (i.e., without peeling) under severe sliding conditions that included a 100-N load (maximum contact pressure of 2.6-GPa). DLC films were synthesized on complex-shape substrates by a plasma-based ion implantation (PBII) system developed for the FCT project. The thickness uniformity of the DLC film deposited on a substrate which simulated a complex-shape was within a distribution of +/-10 %. A journal bearing unit was coated by a CVD diamond-film. The bearing unit, which was accurately finished by high speed grinding, demonstrated very low friction.