Gel‐casting process‐derived 3D‐interconnected porous carbon/B ₄ C preform for reaction‐bonded boron carbide composites

Abstract A novel kind of 3D interconnected porous carbon‐bonded B ₄ C preform with flexural strength of about 20 MP a is fabricated by gel‐casting method. As the control, the B ₄ C/C preforms via molding‐produced method are fabricated. The B ₄ C/C preforms own the same carbon content and almost the same porosity with different molding method. Compared with the conventional compression molding‐produced B ₄ C/C preform, the 3D‐interconnected porous carbon‐bonded boron carbide preforms afford three‐fold advantages in the fabrication of reaction‐bonded boron carbide ( RBBC ) composite via the liquid silicon infiltration ( LSI ) process, including induced formation of continuous SiC‐bonded boron carbide skeleton structure, a reduction in the size of residual silicon, and prevented the coarsening of ceramic grains as well. As a result, the RBBC composite fabricated by gel‐casting appears as a more refined structure resulting in enhanced mechanical properties: the Vickers hardness, flexural strength, and fracture toughness of I‐ GC composites fabricated from 3D‐interconnected porous carbon/B ₄ C preforms are 19.4 ± 1.3 GP a, 389 ± 17 MP a, and 4.37 ± 0.1 MP a·m ^1/2 , respectively, which are statistically higher than those of RBBC fabricated by the conventional compression molding‐produced B ₄ C/C preform.