SiC whisker enhanced reaction bonded boron carbide composites by silicon infiltration: The effect of SiC whisker contents

Reaction-bonded boron carbide (RBBC) composites have great potential for large-scale industrial production owing to their low cost and net sintering size. The enhancement of their mechanical properties is the current focus of attention. Herein, with SiC whiskers (SiC w ) as reinforcement, SiC w -reinforced RBBC (SiC w /RBBC) composites with varying SiC whisker contents were fabricated by silicon infiltration. Furthermore, the effects of SiC w content on the phase composition, microstructure, and mechanical properties of the composites were studied. The as-prepared composites exhibited a maximum flexural strength of 503 ± 82 MPa and a fracture toughness of 4.36 ± 0.43 MPa m 1/2 , representing substantial improvements of 54.8 % in flexural strength and 8.5 % in fracture toughness compared to the non-reinforced composites. The enhancement of the strength and toughness was attributed to good mechanical properties of SiC w , formation of the SiC particle–SiC w –boron carbide (SiC p –SiC w –B 4 C) ceramic skeleton and effects of crack deflection, whisker bridging, whisker pulling out and whisker debonding. However, when the whisker content was too high, the whisker bridging effect in the green preform led to an increase in free silicon content of the composites, which is the main reason for the decline of the mechanical properties of the composites.