Tribological properties of reaction-formed graphite/SiC composites under water-lubricated conditions

Graphite/SiC composites with excellent tribological properties and chemical stability are ideal bearing materials for use in water-lubricated conditions. The composites can be fabricated rapidly by reactive melt infiltration (RMI) with near-net advantages. However, maintaining an adequate carbon content in the matrix after the violent reaction between carbon and liquid silicon is the critical requirement for wear rate and more stable friction coefficient. In this study, a carbon-composite-powder (PFC@G) constructed of graphite particles and glassy carbon derived from phenolic resin, was used as the main carbon source with a larger size (∼200 μm) to improve the carbon content of the graphite/SiC composites. The tribological properties of the composites were measured by a block-on-ring tribometer under water-lubricated conditions. The weight ratio of phenolic resin to graphite particles was adjusted to manipulate the microstructure of PFC@G, which can affect the carbon content of the composites in the course of RMI. The composites with high carbon content (34.47 vol%) were successfully fabricated when the weight ratio is 0.8, which exhibited the most outstanding tribological properties with low friction coefficient (∼0.014) and wear rate (∼10⁻⁶ mm³ N⁻¹m⁻¹) at a load of 15 N.