88 Polymers and Coatings for Tribological Application in Hydrogen Environment

Sliding mechanical components, used in the production and delivery of hydrogen, such as rings and pistons used in reciprocating compressors for point-of-delivery or industrial applications, can be subject to wear and parasitic frictional losses. Experiments were undertaken to assess the friction and wear properties of five high-performance polymers (PEEK, PI, PAI, PPS, and PTFE) sliding against steel and a DLC coating. Test results are presented for medium-speed sliding (3.5 m/s) in pure hydrogen gas or air, for 10 km distance using a horizontal cylinder sliding geometry. Coefficients of friction as a function of distance are graphed, and wear rates are tabulated, for all material combinations.