密封用PTFE复合材料的压缩蠕变性能

采用碳粉/石墨、青铜粉、玻璃纤维(GF)、碳纤维(CF)、聚苯酯(POB)等改性材料改性聚四氟乙烯(PTFE),通过冷压、烧结的方式制得改性PTFE复合材料,研究了载荷、温度等环境条件对不同改性PTFE复合材料压缩蠕变的影响,通过退火进一步改善复合材料的抗蠕变性能,研究了退火温度对复合材料压缩蠕变及力学和摩擦磨损性能的影响。结果表明,各改性材料均能降低PTFE的压缩蠕变量,其中碳粉/石墨改性的PTFE复合材料压缩蠕变量最小,其次为青铜粉改性的复合材料,其余依次为GF,POB和CF改性的复合材料;改性PTFE复合材料的压缩蠕变量随着载荷和温度的增加明显增大,碳粉/石墨改性的PTFE复合材料蠕变受载荷增加的影响最小,且高温(150℃)下的压缩蠕变量最小。在150～300℃下对改性PTFE复合材料进行退火处理,可使其压缩蠕变量减少20%～40%,最佳的退火温度为300℃,在此温度下进行退火对复合材料力学和摩擦磨损性能影响不大。

Research on Compressive Creep Properties of PTFE Composites Used for Sealing

Polytetrafluoroethylene(PTFE)was modified by modified materials including bronze powder,carbon powder/graphite,glass fiber(GF),carbon fiber(CF)and polyphenyl ester(POB),then modified PTFE composites were prepared by cold pressing and sintering.Effects of environment conditions such as load and temperature on the compression creep of the modified PTFE composites were investigated.The creep resistance of the composites were further modified by annealing and the influences of the annealing temperature on the compression creep,mechanical properties,friction and wear properties of the composites were studied.The results show that,each modified material can reduce the compression creep value of PTFE,the carbon powder/graphite modified PTFE composite has the lowest compression creep value,next is bronze powder modified composite,followed in turn by GF,POB,CF modified composites.The compressive creep values of these modified composites increase obviously with the increase of load and temperature.The creep of the carbon powder/graphite modified PTFE composite is least affected by the load increasing and the compressive creep value under high temperature(150℃)is minimum.The annealing treatment at 150–300℃for the modified composites can reduce the compressive creep value by 20%– 40%and the optimum annealing temperature is 300℃.The annealing treatment at 300℃has little effects on the mechanical,friction and wear properties of the modified composites.