Enhanced toughness of zirconia ceramics with graphene platelets consolidated by spark plasma sintering

Graphene platelets reinforced zirconia (GPLs/ZrO₂) composites were prepared by spark plasma sintering in the present work. The effects of GPLs content on the densification route, microstructure feather, mechanical properties, and aging behaviors of such composites were investigated. In spite of the impeding effect of GPLs, high relative density of 98% was achieved for the composites owing to the uniform dispersion of GPLs. The addition of GPLs contributed to enhanced fracture toughness of the composites; when the added content was 1.0 wt.%, its fracture toughness reached up to 8.6 MPa·m^1/2. Also, aging behavior of the GPLs/ZrO₂ composites was investigated at 134°C for 24 hours. The monolithic ZrO₂ ceramic and GPLs/ZrO₂ composites presented residual ratio of 55% and 72% in fracture toughness, respectively. Thus, the incorporation of GPLs inhibited phase transformation from tetragonal phase to monoclinic phase of zirconia.