Synergistic strengthening and toughening of zircon ceramics by the additions of SiC whisker and 3Y-TZP simultaneously

Abstract

The strengthening and toughening behaviours of SiC whiskers and tetragonal zirconia particles (3Y-TZP) in a zircon matrix were investigated. The results showed that the addition of SiC whiskers or 3Y-TZP could improve mechanical properties to some extent. The flexural strength and fracture toughness of 30 vol% SiC(w) ZrSiO 4 reached 460 MPa and 4.7 MPa m 1 2 , while the flexural strength and fracture toughness of 20 vol% 3Y-TZP ZrSiO 4 were 410 MPa and 4.3 MPa m 1 2 . Furthermore, when SiC whiskers and 3Y-TZP were introduced into the zircon matrix simultaneously, a drastic improvement in mechanical properties was achieved and a positive synergistic toughening effect was observed, showing that the combined toughening effect of SiC(w) and 3Y-TZP together was bigger than the sum of the individual toughening effects when either reinforcement acted alone. The flexural strength and fracture toughness of 30 vol% SiC(w) 20 vol% 3Y-TZP/ZrSiO 4 were 580 MPa and 7.0 MPa m 1 2 at room temperature, which were 90% and 130% higher than those of monolithic zircon and could be maintained up to 800 °C. The microstructural observations by SEM and phase analysis by XRD demonstrated that the synergistic toughening effect was engendered from the interaction between microcrack toughening mechanism of 3Y-TZP and crack deflection, interfacial debonding as well as whisker pull-out by SiC whisker.