Abstract

Nanostructured turbostratic graphite derived from the solid-state dissociation of carbides is a new kind of carbide-derived carbon (CDC) consisting of heavily misaligned graphene layers. A recently developed processing route was used to obtain 2D turbostratic graphite nanoparticles via solid-state reactions between boron and chromium carbides. In this work, the tribological performance of these new CDC nanoparticles with different degrees of crystallinity was evaluated. Vacuum impregnation of a tailored sintered porous matrix (Astalloy CrL + 0.6%C) was used to obtain self-lubricating specimens containing both CDC and commercial crystalline 3D graphite, used as a reference. The results showed that the CDC particles promoted low friction coefficients (~0.1) and wear rates up to 70% lower than that of commercial crystalline graphite particles. The study of the wear scars through SEM and an extensive Raman spectroscopy analysis indicated that, although carbon crystallinity plays a fundamental role in the tribological behaviour, it is not the only variable to be considered, as the slow release of solid lubricant from the pores during the tests was shown to be crucial for the stability of a lubricious tribolayer, which reduces adhesion and wear.