往复密封工况下聚四氟乙烯材料性能

Properties of Polytetrafluoroethylene under Reciprocating Sealing Condition

为找出往复密封失效原因,提高往复密封件使用寿命,采用动态热机械分析仪、高低温摩擦磨损试验机等研究了密封材料聚四氟乙烯(PTFE)在不同温度和压力下的物理力学、摩擦磨损和耐油等性能,并采用模拟台架测试了密封件的泄漏量、抗挤出性、磨损和压缩变形等性能。结果表明,随着温度提高,PTFE材料的硬度下降,压缩变形量增加,储能模量下降,虽然对密封效果有利,但密封材料容易被挤出;PTFE材料在油润滑条件下摩擦系数和磨损率很小,随着温度提高,摩擦系数和磨损率有增大趋势,但影响不大;台架测试显示高压下往复密封的主要失效原因为密封件被挤出,可以通过降低密封间隙、增加挡圈或提高材料硬度来提高密封件的抗挤出性。

In order to find out the causing of failure and improve the life of seal,the physical mechanical,friction and wear,oil resistance properties of polytetrafluoroethylene(PTFE)used at different temperature and pressure were studied by DMA,high and low temperature friction and wear testing machine and so on.The leakage,extrusion,wear and compression deformation of stepseal were tested by reciprocating sealing test rig.The results show that the hardness of PTFE decreases,compression deformation increases,storage modulus decreases with the temperature increased,which may cause extrusion of the seal in high temperature and high pressure.The friction and wear of PTFE with oil lubrication are low,but increase with the increasing of temperature while has little effect.The test rig shows that extrusion is the key factor causing the failure of reciprocating seals at high pressure,which can be improved by decreasing the seal gap,adding backup ring or increasing the hardness of sealing material.