Friction and wear variations of short carbon fiber (SCF)/PTFE/graphite (10 vol.%) filled PEEK: Effects of fiber orientation and nominal contact pressure

In the present work, the effects of fiber orientation on the tribological behavior of a short carbon fiber (SCF)/PTFE/graphite (10 vol.% for each) filled PEEK composite was studied under different nominal pressures ranging from 1 MPa to 5 MPa. The fiber orientations were parallel, anti-parallel and normal relative to the sliding direction. The results indicate that the effect of fiber orientation shows strong dependence on the nominal pressure. Under most conditions, lower friction coefficients occurred when the fibers were orientated at the anti-parallel rather than the parallel and the normal directions relative to the sliding direction. At low pressures, i.e. 1–2 MPa, the fiber orientation had little effect on the wear rate. Under higher pressures, i.e. 3–5 MPa, the composite displays a higher wear resistance when the fibers are orientated at the anti-parallel rather than the parallel and the normal directions. The tribological mechanisms were discussed based on scanning electron microscopy (SEM) inspections of the worn surfaces.