Preparation and mechanical properties of CCF reinforced RBSC braking composite from pre-liquid dispersion

In this work, reaction bonded silicon carbide (RBSC) brake composites reinforced by chopped carbon fibers (CCFs) were fabricated by pre-liquid dispersion (PLD), low-temperature compression molding (LTCM) and subsequent densification by liquid silicon infiltration (LSI). The effects of the CCF fraction and PLD process on microstructure, phase composition, compression strength, shear strength and tribological performance of the brake composites were evaluated in detail. Our results showed that the distribution of CCF within the brake composites can be improved substantially through the treatment of PLD process, leading to the lowest open porosity of 9.63% and highest buck density of 1.87 g/cm³ comparing to the composites without PLD. Meanwhile, due to the augment of the interfacial area between the CCF and matrix, the as-prepared brake composite with 20 vol% CCF showed a compression strength as high as 157.55 MPa and shear strength of 22.14 MPa. Moreover, after further graphitization, a highly reliable RBSC brake composite with suitable average friction coefficient (0.427) for braking was obtained via the synergistic effects of lubrication of formed graphite and grain-abrasion by SiC grains in spite of a relatively high mass wear rate. These results show that the CCF reinforced RBSC brake composite is a promising candidate for high performance and low-cost friction composite for the application in brake pads.