Enhancement of tribological properties in siliconized graphite via hierarchically hybrid SiC/C composite

This study aims to investigate tribological properties in a siliconized graphite (СГ-П-0.5) and hierarchically hybrid SiC/C composites at the load ranging from 10-40 ?N under dry air/water lubrication conditions. A feasible liquid silicon infiltration (LSI) was used to fabricate the SiC/C composites. Morphology and phase identification of two materials were characterized and analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). An image feature extraction was used to post-process the data of wear test, further to gain the wear properties of the samples. The results demonstrated that a lower coefficient of friction (COF) and wear rate can be achieved in the LSI SiC composites than that in the sample of СГ-П-0.5. Both COF decreased under water-lubricated conditions, compared with that under the dry air lubrication. The excellent tribological properties in two materials can be due mainly to the microstructure of the СГ-П-0.5 sample, showing much more graphite and Si dispersed on the matrix. The СГ-П-0.5 sample indicated the typical oxidative wear mechanism, whereas, the sample of LSI SiC demonstrated the combined oxidative and fatigue wear. This finding can provide a promising new siliconized graphite materials for ceramic rolling bearings.