Electrotribological properties of metal composite materials reinforced with nanostructural carbon particles

The electrofriction properties of composite materials (CM) based on copper and silver have been studied as a function of the hardness and content of reinforcing superelastic hard carbon particles produced from fullerenes upon high-pressure high-temperature synthesis of metal-fullerene mixtures. The indentation hardness H-IT of the reinforcing particles was increased from 10 GPa to 35 GPa by varying the composition of the starting fullerites (C-60 or C-60/70), by their mechanical activation, and by increasing synthesis pressure (from 5 GPa to 8 GPa). The friction coefficients of the CM upon electrotribological tests are lower by a factor of two than those of pure copper and silver. Reinforcement of copper with 10 wt.% superelastic hard carbon particles with a highly disordered structure leads to a decrease in conductivity, which does not virtually depend on the hardness of the carbon particles and remains high enough for practical use. The friction coefficient of silver based CM reinforced with 5 wt.% carbon particles upon electrotribological tests varies between 0.25 and 0.3, while the friction coefficient of the reference silver sample in the same conditions is 0.50-0.55. The abrasive wear resistance of the silver-based CM samples is higher than that of pure silver sample by a factor of 20. Since the reinforcement of metal with superelastic hard carbon particles can increase its wear resistance by a factor of 15-150 depending on the particle hardness, it is possible to find a compromise between the wear resistance and electrical conductivity to provide their best combination with respect to specific operating conditions.