The beneficial effect of agglomerations of inclusions on the fracture toughness of ceramic nanocomposites

Abstract Agglomerations of carbon‐based inclusions and the low adhesion of inclusion‐matrix interfaces are commonly viewed as detrimental to the strength and fracture toughness of ceramic composites. While large, high‐power agglomerations indeed promote microcracking, our computations show that moderate agglomeration levels can enhance energy dissipation through Y‐junctions in inclusion networks. Focusing on high‐temperature Zr‐based reduced graphene oxide/ceramic nanocomposites, we use a polytopal cell complex (PCC) framework to analyze macrocrack bridging for 12 graphene precursor powders with distinct log‐normal size distributions. The simulations quantify how inclusion fraction, strip‐length statistics, and agglomeration power jointly determine the topology of percolation networks and their contribution to fracture resistance. The results rationalize experimental observations that uniform‐size precursor powders reduce harmful clustering while maximizing bridging. Dislocation‐based estimates indicate that, even under ideal architectures, crack‐bridging toughening is theoretically limited to a factor of 2–3, exceeding but consistent with the 30%–50% improvements typically reported.