Friction Mechanism and Application of PTFE Coating in Finger Seals

Abstract

Due to their special flexible structure, finger seals show good wear and leakage characteristics and has a great application prospects. Under the condition of high speed, the sealing and wear performance of finger seals is directly related to the characteristics of the friction pair between the finger foot and rotor. As a kind of high polymer material with a lower friction coefficient, polytetrafluoroethylene (PTFE) has potential application value in finger seals. Therefore, based on the previous theoretical analysis and optimization design, in this study pin-on-disc tests between the metals applied in finger seals and the PTFE coating and bench-scale performance tests of finger seals with the PTFE coating were carried out. The results show that for finger seals made of the cobalt-base alloy GH605, the friction coefficient of finger seals with PTFE coating is only 0.15, which is 50% lower than that without the PTFE coating; after a 50-h durability test, the leakage performance of finger seals with the PTFE coating was more stable, and its leakage rate and wear rate were reduced by 30 and 39%, respectively, compared to without the PTFE coating. The test results in this article indicate that the PTFE coating has excellent wear resistance characteristics and good application potential for finger seals, which provides valuable reference for the design of the friction pair of finger seals.