Influence of preparation method on microstructure and tribological behavior of C/C-BN composites

Abstract

In this study, with 2.5D needle punched carbon felt as reinforcement, hexagonal boron nitride (h-BN) was introduced through chemical vapor infiltration (CVI) and slurry impregnation (SI) methods, and then pyrocarbon was deposited through CVI to convert the BN-containing preform into carbon fiber reinforced carbon-boron nitride binary matrix composites (C/C-BN). The microstructure and mechanical properties of C/C-BN(P) composites prepared by SI combined with CVI were compared with those of C/C-BN(CVI) composites prepared by CVI. The tribological behavior of C/C-BN(P) composites containing different contents of h-BN fillers and C/C-BN(CVI) composites with and without heat treatment was investigated by the ball-on-disk technique in dry sliding conditions using GCr15 steel balls and Si3N4 balls as sliding counterparts at two different sliding speeds (v = 0.2 and 0.8 m/s), and compared with the C/C composites used as a reference. C/C-BN(P) composites exhibit improved tribological behavior, which can be explained by the combined effect of SI and CVI on the microstructure and mechanical properties, leading to changes in the wear mechanism of the C/C-BN composites. The excellent reinforcement is attributed to the integrity structure of the C/C-BN(P), which can make the self-lubricating friction layer stably exist on the surface of the material and significantly reduce the friction coefficient and wear loss of the C/C-BN(P) composite. Furthermore, the mechanical and tribological properties of C/C-BN(P) composites can be adjusted by using different volume content of h-BN. The present work shows that C/C-BN(P) composites have wide application prospects as anti-friction and wear-resistant materials.