Characterization and evolution of the coefficient of friction during pin on disc tribotest: Comparison between C10200 Cu, AA6082-T6 Al and C36000 brass pins under varying normal loads

Cu, leaded α+β brass and Al-alloy pins were pin-on-disc (PoD) tested against steel discs using sliding speed of 0.1 m/s and contact pressures from 0.51 to 2.55 MPa. Cu/steel tribopair showed unstable coefficient of friction (CoF) evolution around 0.6, while Al/steel and brass/steel tribopairs featured stable CoF evolution, around 0.42 and 0.30 respectively. The tribosurfaces of the discs and pins were characterized by laser interferometry and microscopy. Cu/steel and Al-alloy/steel tribopairs presented oxide transfer films, but intense adhesion of Cu on the discs produced unstable CoF evolution of the Cu/steel tribopair. Conversely, intense leaded-brass adhesion promoted the lowest and more stable CoF evolution of the brass/steel tribopair.