Preliminary study on superlubricity behaviors of modified PI-PEEK with nano silica

Concern for the environment is one of the main factors that are increasing the demand for superlubricity materials, this study aims to evaluate the lubrication performance of nano-silica modified PI and coating of polyetheretherketone (PI (NS)-PEEK) superlubricity material during the plane-plane contact process. A series of PI-PEEK materials modified by silica nanoparticles with different concentrations (0.05, 0.1, and 0.5 wt%) were synthesized and characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), white light interferometer, field emission scanning electron microscope (FESEM) and energy dispersive spectrometer (EDS). Friction tests were conducted under a load of 5 N for three hours to determine the optimal concentration based on anti-frictional properties. The PI-PEEK optimized with a 0.1 wt% concentration of SiO 2 further applied in the friction test at different velocities and different loads. Suggesting its potential as a superlubricity material. The results indicated superior antifriction performance at a NS concentration of 0.1 wt%, leading to the minimal average friction coefficients of 0.001221 (load of 5 N, velocity of 200 rpm), maintain superlubricity (ACOF=0.007528) under high loads (load of 95 N, velocity of 200 rpm), and maintain superlubricity (ACOF=0.007528) under high velocities (load of 5 N, velocity of 400 rpm). Additionally, the use of the nano-silica contributed to the formation of transfer film. SEM and white light interferometer characterization outcomes demonstrated that the worn surface of PI (NS)-PEEK exhibited a greater propensity to generate a smooth and continuous transfer film, compared to samples with a nano-free PI-PEEK. The EDS characterization results manifested that the transfer film consisted of three elements, viz. carbon (C), oxygen (O), and silicon (Si). These findings suggest that PI (NS)-PEEK could serve as an effective alternative to conventional bearing in future industrial bearing applications.