The current research uses the Digital Image Correlation (DIC) approach to study the fracture
behaviour of Reaction-Bonded Silicon Carbide-Boron Carbide (SiC–B4C) ceramic (RBSBC). A
Photron camera with 137,500 fps was used to capture the crack propagation at an interframe time
frame of 2.6 ms before final fracture. The purpose was to capture the rapid brittle behaviour of
the ceramic during the onset of crack propagation. The RBSBC failed in a transgranular manner
like most monolithic SiC-based materials as Hexoloy-SA. The presence of randomly dispersed
coarse B4C grains helps in deflecting the crack path which increases the overall crack length. The
material’s resistance to crack propagation (R-curve) was measured using the crack tip opening
displacement, the stress intensity at the crack tip KI, and the J-integral against crack extension.
Two methods were used to determine the KI: experimentally based on the displacement values at
the crack tip as obtained from the DIC images, and quasistatic based on the fracture load and the
geometrical dimension of the crack. The experimentally-determined KI and J resulted in higher
values compared to the quasistatic ones. However, they reflect the actual conditions at the crack
tip, while the quasistatic conditions underestimate the resistance-plot. The RBSBC has higher Rcurve compared to commercially available SiC-only materials as Hexoloy-SA and ABC-SiC. To
improve the crack-resistance of RBSBC, the Si amount should decrease to a nm level, while the
percentage of B4C grains should increase and be evenly dispersed across the material.