Production and Mechanical Performance of Tantalum Strengthened Alumina–Zirconia Composites with Graphene Addition

High density alumina–zirconia–tantalum ceramic–metal composites with the addition of 0.5 vol.% of graphene oxide were fabricated via a wet processing technique followed by spark plasma sintering. Scanning electron microscopy confirmed the even distribution of metal particles in the composite matrix. The thermal reduction of graphene oxide after consolidation at 1500 °C was proved using Raman spectroscopy. The engineered materials exhibit a fracture resistance of 16 MPa∙m1/2, which is 30% greater than in the reference ZTA ceramic composites fabricated using the same technology. That increase in fracture toughness could be down to a synergetic interaction mechanism; more specifically, crack trapping, renucleation and blunting, and elongated tantalum particles bridging. In addition to the above-mentioned mechanisms, tetragonal monoclinic phase transformation in zirconia is also an additional source of increased crack resistance in the developed composites.