Advanced yttria-stabilized zirconia composites through in situ growth zeolitic imidazolate framework-derived nanocarbon

Advanced ceramics are valued for their exceptional mechanical and electrical properties, which can be further improved by incorporating micro and nanostructures as reinforcements. Carbon allotropes such as carbon nanotubes and graphene have been widely utilized in ceramic matrix composites (CMCs) to enhance fracture toughness and electrical conductivity. However, challenges like nanocarbon agglomeration and weak interfacial bonding with ceramics often hinder their effectiveness. Metal-organic frameworks (MOFs) offer a promising alternative due to their carbon-rich structure, which can be carbonized and homogeneously integrated into ceramic matrices. In this study, we propose a novel approach by directly growing ZIF-67 MOF crystals around yttria-stabilized zirconia (YSZ) nanoparticles to achieve a more uniform distribution compared to conventional physical mixing methods. The resulting YSZ/ZIF-67 composites, fabricated via spark plasma sintering (SPS), exhibited a 44 % increase in fracture toughness, attributed to the refined microstructure and the energy-wasting of crack by deflection and bridging effect of the derived nanocarbons. Additionally, electrical conductivity improved by 9 orders of magnitude, benefiting from the percolation network formed by carbonized ZIF-67. Structural analyses, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy, confirmed the successful incorporation and uniform distribution of nanocarbons within the ceramic matrix. These findings demonstrate that MOF-derived carbon structures can significantly enhance both the mechanical and electrical performance of ceramic composites, offering potential applications in energy storage, electronic devices, and structural materials.