Dry sliding tribological behavior of nanocrystalline and conventional polycrystalline copper

Dry sliding tribological behavior of an electro-deposited nanocrystalline Cu (nc Cu) and a conventional coarse-grained Cu (cg Cu) has been investigated using a ball-on-disc tribometer with cemented tungsten carbide ball as the counterface. Experimental results showed that the wear resistance of copper with the nanocrystalline microstructure was enhanced relative to the coarse-grained form. The steady-state friction coefficient of the nc Cu was obviously lower than that of the cg Cu when the load is below 20 N. The wear volume of the nc Cu was always lower than that of the cg Cu for the applied load range from 5 to 40 N. With increase of the load, the difference in wear resistance between the nc and the cg Cu decreased. The enhancement of the wear properties of the nc Cu was associated with the high hardness and the low work-hardening rate of the nanocrystalline structure, and easily being oxidized of wear debris, which was attributed to grain refinement.