Preparation and tribological properties of PTFE/DE/ATF6 composites with self-contained solid-liquid synergetic lubricating performance

A new kind of PTFE composite with self-contained solid-liquid synergetic lubricating effect is prepared by the combination of PTFE, porous diatomite (DE), and immersed lubricating oil (ATF6). The tribological and mechanical properties of composites with different DE contents and varying cold-pressed pressures were investigated systematically. Due to the oil storage effect of DE particles, the maximum oil content of PTFE/DE composite is 16.4 wt%. With the increase of DE content, the surface hardness, elastic modulus and yield strength can be increased from 3.2 to 3.6 HV, 37.8–60.2 MPa and 8.7 MPa–12.8 MPa, respectively. With the addition of DE, the wear rate of PTFE decreases but the coefficient of friction (COF) increases. Meanwhile, with the addition of DE and ATF6, both the COF and wear rate of PTFE decrease. The COF can be reduced by 68% from 0.121 (specimen 0%-10 MPa-dry) to the minimum value of 0.039 (composite 10%-10 MPa-ATF6), and the wear rate can be reduced by 82% from 1.95 × 10−4 mm/Nm (0%-50 MPa-dry) to the minimum value of 0.35 × 10−4 mm/Nm (10%-50 MPa-ATF6). The enhanced antifriction performance of the composite PTFE/DE/ATF6 is contributed by the synergistic lubricating effect of self-contained liquid lubricant of ATF6 and the solid lubricant of PTFE. The prepared PTFE/DE/ATF6 composites exhibit excellent tribological performance as well as the mechanical properties, which can be used to fabricate a new kind of self-lubricating materials with high performance and long durability.