3D interconnected architecture of h-BN reinforced ZrO₂ composites: Structural evolution and enhanced mechanical properties for bone implant applications

The present investigation mainly focused on hexagonal boron nitride (h-BN) substitution for modified physical, mechanical and biological properties of nano zirconia (nZrO₂).A simple and scalable solid-state reaction method has been used to prepare a three dimensional (3-D) composites in the system [(15+x)BN-(85-x)ZrO₂] (0 ≤x ≤ 55). A major novel phase of zirconium oxynitrate, ZrO(NO₃)₂ was confirmed by X-ray diffraction(XRD) results. The uniform and interconnected distribution of large h-BN nanosheets ensure the significant grain refinement of nZrO₂ established by surface morphology study of fabricated composites. This reinforcement of h-BN plays a pivotal role to enhance the ductility of zirconia. The composite sample 70B-30Z has a remarkable mechanical strength and less wear resistance as compared to the natural bone, for this sample (70B-30Z) various mechanical parameters i.e. Young's modulus, fracture toughness, maximum mechanical strength, and density are found to be 9.84 MPa, 4.12 MPa m^1/2, 174.94 MPa, and 2.54 g cm⁻³ respectively. The noteworthy cell proliferation at 25 µg/ml by MTT assay for the composite 70B-30Z recognizes it as a suitable bone implant material.