莫来石与碳纤维协同填充的聚四氟乙烯基复合材料及其摩擦学性能

为了提高聚四氟乙烯（PTFE）的摩擦学性能，采用机械混匀、带温预压及烧结等工艺制备了莫来石和碳纤维填充的PTFE基复合材料，并通过FTIR、XRD、万能材料试验机、洛氏硬度计、DSC及热机械分析分别表征了PTFE基复合材料的显微结构、力学性能和热学性能；然后，使用MRH-3 型高速环块磨损试验机测定了复合材料的摩擦系数和磨损率，通过自制的硅油砂浆磨损装置测定了复合材料在不同温度下的耐砂浆磨损性能；最后，借助3D测量激光显微镜研究了复合材料摩擦面形貌，并分析了摩擦磨损机制。结果表明:莫来石和碳纤维在PTFE体系中起到填充增强作用，20wt%莫来石-10wt%碳纤维/PTFE复合材料的弹性模量由364 MPa增加至874 MPa；20wt%莫来石-10wt%碳纤维/PTFE复合材料的干摩擦系数较大，但其磨损率与纯PTFE相比降低了3个数量级以上，且此复合材料在水摩擦条件下仍能保持较好的摩擦系数和磨损率，摩擦系数为0.157，磨损率为7.40×10-6 mm3·N-1·m-1；此外，20wt%莫来石-10wt%碳纤维/PTFE复合材料在较高温度下仍能表现出良好的耐砂浆磨损性能。所得结论表明改性得到的PTFE 基复合材料的摩擦学性能显著提高，复合材料可用于有杆抽油井防偏磨。 

Polytetrafluoroethylene matrix composites synergistically filled with mullite and carbon fiber and its tribological performances

In order to improve the tribological performances of polytetrafluoroethylene (PTFE), PTFE matrix composites filled with mullite and carbon fiber were prepared by processes such as mechanical blending, heat pre-compression and sintering etc., and the microscopic structures, mechanical properties and thermal properties of PTFE matrix composites were characterized by FTIR, XRD, universal material testing machine, Rockwell hard meter, DSC and thermomechanical analyzer respectively. Then, the friction coefficients and wear rates of the composites were measured by MRH-3 high speed ring-on-block wear tester, and a self-designed sand slurry wear apparatus with silicone oil was used to detect the sand slurry wear resistance of the composites at different temperatures. Finally, the morphologies of friction surfaces for the composites were investigated by 3D measurement laser microscope, and the friction and wear mechanisms were analyzed. The results show that mullite and carbon fiber play a role of filling and toughening in PTFE system, and the elastic modulus of 20wt% mullite-10wt% carbon fiber/PTFE composite is enhanced from 364 MPa to 874 MPa. The dry friction coefficient of 20wt% mullite-10wt% carbon fiber/PTFE composite is higher, while its wear rate decreases by more than three orders compared with pure PTFE, and the composite maintains relatively good friction coefficient and wear rate under water friction condition, the friction coefficient is 0.157 and the wear rate is 7.40 × 10^-6 mm³·N^-1·m^-1. Further, 20wt% mullite-10wt% carbon fiber/PTFE composite also shows favorable sand slurry wear resistant even at relatively high temperature. The conclusions obtained suggest that the tribological performances of PTFE matrix composites obtained by modification improve significantly, and the composites can be applied to the eccentric wear of the sucker-rod pumping well.