Enhancing the fracture toughness of zirconia via highly oriented graphene arrays

Abstract

Zirconia matrix composites with well-dispersed and highly-oriented two-dimensional graphene arrays were fabricated successfully using tape casting. This significantly improved the fracture toughness (KIC) of zirconia, i.e., an improvement of 64.1 % in KIC, from 4.3 MPa m0.5 to 7.21 MPa m0.5. The interface strengthened by Zr, O and C bonding between zirconia and graphene plays a crucial role in improving the toughness of zirconia. The catastrophic fracture failure mode is transformed into the stable crack propagation behavior with well-oriented graphene arrays. The interface stress transfer behavior analyzed by the shear-lag theory reveals that the graphene layers have little effect on the maximum axial stress and shear stress at graphene/zirconia interface, but the stress distribution are changed. Due to the weak bonding between inner graphene layer, the energy dissipation by graphene pulling-out decreases with increased graphene layers.