THE ROLE OF COPPER-COMPOUNDS AS FILLERS IN TRANSFER FILM FORMATION AND WEAR OF NYLON

The friction and wear behavior of filled nylon 11 composites was studied. The fillers used were CuS, CuO, CuF2, and Cu(C2H3O2)2.H2O (copper acetate). A fixed filler proportion of 35% by volume was used. Sliding tests were performed in a pin-on-disk configuration at 1.0 m s-1 speed and 0.65 MPa nominal contact pressure under ambient conditions. The pin was made of composite specimens and the disk of hardened tool steel. It was found that CuS, CuF2 and CuO as fillers reduced the wear rate of nylon while Cu(C2H3O2)2.H2O increased it. The cause of this behavior was investigated in terms of the ability of these materials to develop a transfer film and its bonding to the counterface. The wear rates of nylon and copper-acetate-filled nylon were high because the ability of nylon to form a transfer film was poor and the composite transfer film had poor adhesion to the counterface. On the other hand, the wear-resistant nylon composites which were filled with CuS, CuO and CuF2 transferred well to the counterface and their transfer films were thin, uniform and strongly adherent to the counterface. The adhesion of the transfer film to the counterface for CuO-nylon composite was investigated by X-ray photoelectron spectroscopy analysis.