Multilayered carbon films for tribological applications

Recent work has shown that for nano-layered structures consisting of two materials, an effect may be shown in which the elastic modulus and fracture toughness depend on the period of the structure. In this paper we create carbon multilayer structures by two methods using cathodic arc deposition with pulsed bias applied to the substrate. The multilayers are created in one class of structures simply by interrupting the deposition to form relaxed layers. In the other class of structures, the pulse bias conditions are varied periodically. The in-service performance of the structures is assessed by impact-enhanced pin-on-disc wear testing and indentation hardness. The structures are examined using bright field and dark field transmission electron microscopy. A 10 nm non-convergent electron probe was used for the micro-diffraction studies. A model for the structure of the interfaces between the relaxed layers and the as-deposited material, including evidence of preferred orientation is presented.