Friction and Wear Characteristics of PEEK and PEEK Composites in Water Lubricated Slow Speed Sliding

Abstract

Friction and wear performances of natural grade poly-ether-ether ketone (PEEK) and three PEEK composites e.g. 30 mass% carbon fibre reinforced (PC-1), 30 mass% glass fibre reinforced (PC-2), and 10 mass% each PTFE/graphite/carbon fibre reinforced (PC-3) were studied under water lubricated, slow speed sliding conditions. Tribological tests were carried out on Pin-on-Disc setup and 17-4 PH stainless steel was used as counterface material. Test conditions were; 3, 6, 12 MPa contact pressures (P) and 0.05, 0.005 m/s sliding speeds (V). Natural grade and glass-fibres reinforced composite (PC-2) exhibited poor friction and wear characteristics at all PV conditions. Composite reinforced with high percentage of carbon (PC-1) showed good tribological performances at all PV conditions. However PTFE/graphite/carbon fibre reinforced grade (PC-3) showed improved performance at very low sliding speed (0.005 m/s). Increased sliding speed resulted into dramatically increase in wear rate of PC-3, may be due to non-retention of transfer film of PTFE and graphite on the counterface material. Good tribological behavior of PC-1 attributed to addition of 30 mass% carbon fibres, which was effective to protect the matrix material from shear and abrasion. Wear mechanisms were discussed based on scanning electron microscopy (SEM) of the worn surfaces. These results were also compared with conventional material pair.

Keywords

• sliding wear
• peek
• wear testing
• sem
• carbon fibre
• graphite