Tribological properties of metal-matrix composite materials reinforced by superelastic hard carbon particles

Metal-matrix composite materials (CMs) are synthesized from a mixture of a metal powder (Ti, Fe, Co, Ni, Cu, Al-based alloy) and fullerenes (10 wt %). The thermobaric synthesis conditions (700–1000°C, 5–8 GPa) ensure the collapse of fullerene molecules and their transformation into superelastic carbon phase particles with an indentation hardness H_IT = 10–37 GPa, an elastic modulus E_IT = 60–260 GPa, and an elastic recovery of >80% upon indentation. After reinforcing by superelastic hard carbon, the friction coefficient of CM decreases by a factor of 2–4 as compared to the friction coefficient of the matrix metal, and the abrasive wear resistance increases by a factor of 4–200. Superelastic hard carbon particles are a unique reinforcing material for an increase in the wear resistance and a simultaneous decrease in the friction coefficient of CM.