PTFE/Kevlar纤维编织材料摩擦损伤演变规律研究

目的通过对PTFE/Kevlar纤维编织材料进行不同循环次数的往复摩擦磨损试验,研究并揭示其摩擦损伤演变规律和损伤机理。方法采用MXW-5型摩擦磨损试验机,同时保持一定的位移和频率,对材料分别进行2、5、10 N等3种载荷等级下往复运动的不同循环次数试验。采用体视显微镜(SM)对材料磨损表面在试验过程中产生的宏观损伤进行分析,利用3D光学显微镜(3D-OM)、扫描电子显微镜(SEM)、X射线能谱仪(EDS)对损伤表面的微观形貌以及化学状态加以分析。结果3种不同载荷条件下的样品,在达到1000次循环往复运动之前,摩擦因数增大0.05,1000~5000次增幅减缓为0.02,并逐渐趋于稳定。不同循环次数下,损伤表面形成了不同大小的PTFE转移膜,将表面C元素覆盖。3种载荷下,编织材料的磨损机制主要为疲劳磨损。结论在载荷不变的条件下,随着循环次数的增加,前期编织材料磨痕表面部分区域会形成PTFE转移膜,对Kevlar纤维产生一定的保护作用,进而降低表面磨损程度。随着表面磨损程度不断加剧,磨痕表面形成的PTFE转移膜剥落,导致纤维重新暴露在表面,使磨损进一步加剧。同时,随着材料样品磨损不断严重,磨痕表面的氧化程度不断加深。

不同加速应力下PTFE/Kevlar编织衬垫寿命及摩擦学性能研究

自润滑编织衬垫是自润滑关节轴承中的关键材料,其摩擦学性能及服役寿命直接影响关节轴承的可靠性及寿命.为解决衬垫寿命评价周期长和效率低问题,本文中以PTFE/Kevlar编织衬垫为研究对象,分别以载荷和频率作为加速应力,对PTFE/Kevlar编织衬垫进行加速寿命试验研究,并用扫描电子显微镜和光学显微镜对磨屑及不同阶段衬垫表面进行表征,获得载荷20~50 MPa和频率5~10 Hz下衬垫的加速寿命与不同阶段的磨损特征,通过最佳线性无偏估计法及最小二乘法建立威布尔-逆幂律加速寿命模型.研究结果表明:PTFE/Kevlar编织衬垫的磨损过程主要分为轻微磨损、稳定磨损和剧烈磨损3个阶段.相比于载荷,频率对不同阶段衬垫摩擦学行为的影响更为复杂,对加速模型的精度影响更大.以载荷为加速应力的加速寿命模型实际可靠度为98%,而以频率为加速应力的加速寿命模型实际可靠度仅为78%.在加速载荷为20~50 MPa条件下,实现衬垫的寿命预测及可靠性估计.

Sliding Wear of the Hybrid Kevlar/PTFE Fabric Reinforced Phenolic Composite Filled with Nano-titania

The Kevlar/polytetrafluroethylene（Kevlar/PTFE） fabric composite can be used as a self-lubricating liner of the self-lubricating bearing.Many types of nano-particles can improve the tribological performance of the polymer-based composite.Unfortunately,up to now,published work on the effect of nano-particles on the tribological performance of the fabric composite which can be used as a self-lubricating liner is quite scarce.Therefore,for the purpose of exploring a way to significantly improve the tribological performance of the fabric composite,the tribological performance of the Kevlar/PTFE fabric composite filled with nano-titania is evaluated by using the block-on-ring wear tester.The scanning electron microscopy is utilized to observe the morphologies of worn surfaces of the fabric composites and the counterparts.The tensile properties of the composites are evaluated on the universal material testing machine.The test results show that the addition of nano-titania at a proper mass fraction of the matrix resin improves the wear resistance and the tensile strength,decreases the friction coefficient,and makes the wear volume of the composite reach a relative steady state more quickly;plastic deformation and microcutting are important for the wear of the fabric composite;a lubricating layer is formed on the worn surface of the composite during sliding,and the lubricating layer is critical for the tribological performance of the composite;the formation and properties of the lubricating layer are influenced by the nano-titania particles.The proposed study on the effect of nano-titania on the tribological performance of the Kevlar/PTFE fabric composite,especially on the evolution of the worn surface of the composite,provides the basis for further understanding of the influence mechanism of the nano-particles on the tribological performance of the composite and explores a method of improving the tribological performance of the composite.