Three-dimensional PDC-SiBCN network in MA-SiBCN ceramics: Toughening-reinforcing effect and oxidation barrier

A three-dimensional (3D) precursor-derived (PDC) SiBCN network was incorporated into mechanical alloying-derived (MA) SiBCN (MA@PDC-SiBCN) ceramic through a novel hybrid organic-inorganic method, enhancing densification while providing significant reinforcement and toughening effects. The PDC-SiBCN network's submicron continuity and uniformity enable efficient load transfer between under-sintered MA-SiBCN particles, increasing strength by 130 %, compared to MA-SiBCN ceramics of the same density. Additionally, as cracks penetrate the PDC-SiBCN network, crack tip deflection and bifurcation result in 57 % and 352 % increases in fracture toughness respectively, compared to fully sintered and under-sintered MA-SiBCN ceramics of the same density. Besides, due to synergistic oxidation characteristics, the three-dimensional PDC-SiBCN network acts as an oxidation barrier, inhibiting the heterogeneous oxidation of the encapsulated MA-SiBCN component, especially limiting the consumption of BN(C) phase at lower temperatures. The residual PDC-SiBCN network in the oxide layer serves as a rigid framework, preventing bubble growth in the molten oxide layer thereby forming a dense protective oxide layer.