INFLUENCE OF WATER-VAPOR AND OXYGEN ON THE TRIBOLOGY OF CARBON MATERIALS WITH SP(2) VALENCE CONFIGURATION

The tribological behaviors of graphite, non-graphitic carbon, carbon-c arbon composite, and unhydrogenated amorphous carbon in nitrogen and a ir are investigated. The friction and wear of all carbon materials can be similarly influenced by water vapor and oxygen. Carbon materials g enerally exhibit a high friction and wear behavior when there is a lac k of lubricant vapors in the environment. Water vapor, even in small q uantities, is effective in lubricating carbon materials-a concentratio n of 100 ppm in nitrogen can lubricate most of the materials examined in this study. Depending on the water vapor content in the environment and the friction regime involved, oxygen can act either as a lubrican t or an agent for tribochemical wear. The tribological properties of c arbon materials depend on gases and vapors in the environment that can interact with carbon atoms. In spite of having a wide range of physic al properties, the family of sp(2) carbon materials can exhibit simila r friction and wear behaviors in various environments owing to their c ommon valence structure.