In situ investigation of the fracture toughening mechanisms of bioinspired dental ceramic composites with different compliant polymer phases

Bioinspired ceramic composites are promising alternatives to traditional dental ceramics. Their complex lamellar architectures and structural components enable successful clinical application, particularly for withstanding the masticatory forces of the oral environment. Bi-directional freeze casting can be utilized to overcome the limitation of brittleness and enhance the overall toughness. This research focuses on developing a reliable, in situ, high-resolution, micromechanical characterization technique to investigate the phase-dependent toughening mechanisms of bioinspired alumina (Al2O3)-based composites with different polymers, ultimately aiding the development of bioinspired ceramic composites. Real-time in situ SEM observations during fracture toughness testing revealed characteristic zig-zag crack paths in all composites, indicating significantly higher energy dissipation compared to monolithic Al2O3. The results suggest that the enhanced fracture resistance of these composites is primarily governed by their multiscale microstructural features, which are, in turn, dictated by the individual properties of each phase.