Research on the wear model of carbon/carbon composite finger seal

Abstract

Finger seal is a new type of contacting flexible gas seal which can be used in gas turbine. The seal is often works in high velocity, high temperature and high pressure operating conditions. So wear is a prominent issue with the finger seal. A Carbon/Carbon (C/C) composite material finger seal is proposed to reduce the wear between seal and shaft with the self-lubricating properties of C/C composites. In order to determine the wear properties between C/C composite finger seal and rotor, a pin-on-disc high temperature friction and wear tester was used to study the friction and wear behavior between the pair of C/C composite and 40CrNiMoA material under dry friction. According to the friction and wear performance of the tribo-pair, the friction coefficient and wear volume were obtained under different working conditions. The test results show that when the load increases, the friction coefficient increases but the amount of wear does not increase monotonically. As the sliding speed increases, the coefficient of friction decreases and the amount of wear increases significantly. In a higher temperature environment, the coefficient of friction decreases while the amount of wear increases with increasing temperature, and adhesive wear becomes more obvious. Based on the multifactor orthogonal test results, a regression analysis model of the relationship between the material wear rate and the load, speed, and ambient temperature was established. Considering the difference between the speed of the test machine and the actual working conditions of the finger seal, the regression wear model was corrected with reference to the high-speed operating conditions of Brake disc. The calculated results of the modified wear rate regression model are compared with the wear rate obtained from the finger seal test. The relative error is within 20%, which verifies the wear rate calculation method of the C/C composite finger seal proposed in this paper. The work provides the basis for numerical analysis and life prediction of C/C composite finger seal wear behavior.