Friction and wear of water lubricated PEEK and PPS sliding contacts

The friction and wear performance of polyetheretherketone (PEEK) and polyphenylenesulphide (PPS) of thermoplastic polymer in water was studied using a face-contact sliding tester. With PPS, FeS was formed on the mating steel surface as a result of the reaction of sulfur contained in PPS with the steel surface. The formation of FeS promoted the transfer or adhesion of PPS to the mating steel surface. Consequently, PPS had a high ability to form the transfer film on the mating steel surface compared with PEEK. On the other hand, with PEEK, the hardness at a sliding surface was decreased in water lubrication although, the hardness of PEEK did not decrease only by immersing in water. The reduction in surface hardness promoted the wear of PEEK in water.