高温振动下聚四氟乙烯垫片的松弛与泄漏测试

设计了一种高温下垫片密封性能的测试系统，研究了在100 ℃时小幅位移控制振动及静态松弛条件下聚四氟乙烯垫片的应力松弛和密封性能，并讨论了载荷比为0.99时3种最大压缩量对聚四氟乙烯垫片的动态应力松弛和泄漏行为的影响，以及在同上最大压缩量下的静态应力松弛和密封性能. 结果表明，100 ℃下聚四氟乙烯垫片的动态应力松弛率随最大压缩量增大而增大，静态应力松弛率随最大压缩量增大有缓慢减小；在静态和动态试验的初始20 s阶段内，应力迅速下降，表现明显的应力松弛，而动态试验更明显；动态松弛实验前后的压差变化约是静态松弛试验的1.1倍.

Relaxation and Leakage Test of PTFE Gasket under High Temperature Vibration

The testing system of sealing performance for high-temperature gasket was designed. The stress relaxation and sealing performance of polytetrafluoroethylene （PTFE） gasket under small-amplitude deformation-controlled vibration and static stress relaxation at 100 ℃ were investigated. The effects of maximum compression on the dynamic stress relaxation and leakage behavior of PTFE were studied. The static stress relaxation and sealing performance of PTFE gasket at load ratio of 0.99 and the maximum compression of 0.3 mm, 0.4 mm and 0.5 mm were further researched. Results show that the dynamic stress relaxation rate of PTFE increases with the maximum compression rising and the static stress relaxation rate of PTFE reduces slowly with the increase of the maximum compression deformation at 100 ℃. Moreover, the stress decreases rapidly during the initial 20 s in both dynamic and static tests, which shows a remarkable effect of the stress relaxation, especially in the dynamic stress relaxation experiment. The differential pressure of dynamic test is about 1.1 times that of static test.