Multiscale fracture modeling of graphene-embedded SiC ceramic materials

Abstract The more versatile engineering application of silicon carbide (SiC) ceramics is impeded by their innate low fracture toughness and high brittleness. To overcome such bottleneck and among others, retrofitting SiC with graphene-based additives has recently proved to be a practical way to attain modified SiC with augmented damage resistance. Nonetheless, the above-mentioned approach received less attention from computational modeling perspective. In that regard, the current study proposes a multiscale computational approach to further investigate the damage mechanics of SiC ceramics with graphene inclusions. First, ReaxFF molecular dynamics simulations are conducted to extract the interfacial properties (i.e., cohesive zone) of the graphene-SiC ceramics. Then, the fracture and crack propagation of the hybrid graphene-SiC composites subjected to tensile loading are investigated using the phase field model of fracture in conjunction with the identified cohesive zone properties. Corroborated by some of the available experimental evidence from the existing reports, the numerical results evince that (a) complete fracture of the hybrid material is de facto delayed by embedding the graphene additives, (b) higher resistance to complete fracture is obtained by increasing volume fraction and utilizing graphene inclusion with larger sizes, and (c) for a certain volume fraction ( v f = 0.375%), double layer graphene inclusion would slightly outperform the single layer graphene in terms of enhancing the fracture resistance of SiC ceramic composite. Further, the influences of the ambient temperature, defect location, and defect density (single defect versus multiple defects) on the fracture of the graphene-SiC composites are also addressed. The proposed approach and findings of this study offer insights into the bottom-up design pathways for developing multifunctional and damage-tolerant novel ceramic matrix composites for applications in structural engineering, energy devices, defense, and aerospace industries.