Cold sintering process on the tribological properties of h-BN@SiO2/PEEK composite

To achieve the low-temperature combination of ceramics and polymers, the core-shell structure and cold sintering method are employed to prepare ceramic/polymer composites. An easy-bonding Silica (SiO 2 ) shell was introduced onto the surface of the hard-bonding Hexagonal boron nitride (h-BN) core by a sol-gel method to fabricate a core-shell structured h-BN@SiO 2 composite. Polyether ether ketone (PEEK) was subsequently filled into h-BN@SiO 2 to prepare h-BN@SiO 2 /PEEK ceramic composite by a cold sintering method. The effects of PEEK content (20 vol%, 35 vol%, and 50 vol%), sintering temperature (205 °C, 245 °C, 285 °C, and 325 °C), and molding pressure (350 MPa, 450 MPa, and 550 MPa) on the dry tribological properties of h-BN@SiO 2 /PEEK ceramic composites against GCr15 bearing steel were investigated using a ball-on-disc contact configuration. Field emission transmission electron microscopy (TEM), Energy dispersive spectrometer (EDS), Field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectrometer (FTIR) were used to characterize and analyze h-BN@SiO 2 or h-BN@SiO 2 /PEEK ceramic composites. The results indicate that h-BN@SiO 2 /PEEK composite exhibits better tribological performance when fabricated with a PEEK content of 35 vol%, a sintering temperature of 285 °C, and a molding pressure of 450 MPa under the investigated conditions. The formation of a stable and continuous mixed lubrication layer composed of h-BN, PEEK, and SiO 2 is identified as the primary factor contributing to the enhanced friction reduction and wear resistance. Under the investigated conditions, the main wear mechanisms observed in h-BN@SiO 2 /PEEK composites are adhesive wear, fatigue wear, and slight abrasive wear.