Toughening by Monoclinic Zirconia

The toughening induced by monoclinic ZrO 2 in the absence of microcracking was investigated, using ZnO as the host material. Toughness levels K c in excess of the host toughness K c M were achieved, attaining a peak toughness K c /K c M ∼1.7, at monoclinic ZrO 2 volume concentrations 0.2. This toughening is attributed to crack/particle interactions, associated with the deflection and bowing of the crack by the residual strain field around the monoclinic ZrO 2 particles.