Tribological properties of polyimide‐modified ultrahigh molecular weight polyethylene water‐lubricated composites under extreme operating conditions

Abstract In this study, a novel composite material has been prepared, which is composed of ultra‐high molecular weight polyethylene (UHMWPE) with a small amount of polyimide (PI). The friction behavior of composites under dynamic speed and load conditions was investigated using a MDW‐02G friction and wear testing machine. The frictional behavior of composites under low‐speed with heavy‐load (LSHL) dry friction and high‐speed with light‐load (HSLL) water lubrication conditions was studied separately. The tribological performance of the composites was analyzed on the basis of the coefficient of friction, wear rate, and wear morphology. The experimental results showed that the addition of PI enhances the thermal stability of UHMWPE‐based composites. The defects of the UHMWPE surface vulnerable to fatigue wear under extreme working conditions were improved. Compared with UHMWPE, the wettability of PI modified composites was enhanced, and the lubricating film formed could better adhere to the friction interface. This effectively improved the lubrication conditions between the friction interfaces, while improving the wear resistance and reducing the coefficient of friction. It can be concluded that the thermal stability and wear resistance of UHMWPE‐based water‐lubricated bearings can be improved by a small proportion of PI enhancement, while ensuring that the composite material also has good self‐lubricating properties. Highlights Low PI content enhances the thermal properties and wear resistance of composites. Under LSHL conditions, the wear rate in the composite can decrease by up to 93%. The wear mechanism of composites under LSHL and HSLL conditions was revealed.