Hydrothermal degradation of ground 3Y-TZP

The effect of microstructural changes induced by grinding on the resistance to hydrothermal degradation of 3Y-TZP has been studied. Analyses by X-ray diffraction and μ-Raman spectroscopy have shown that hydrothermal degradation (131 °C/96 h) does not produce additional monoclinic phase in ground specimens. The resistance to degradation of ground samples is explained in terms of the formation of a very thin layer of recrystallised and textured nano-size grains, which prevents the formation of monoclinic variants. In addition, by annealing at 1200 °C during 1 h after grinding, the usual microstructure of as-sintered material is recovered, but the material is still resistance to degradation. This increased resistance for annealed specimens with respect to as sintered specimens is related to the crystallographic texture developed after grinding. The level of texture, as measured by It(0 0 2)/It(2 0 0) ratio, diminishes with the annealing treatment and the amount of monoclinic fraction formed during hydrothermal degradation increases proportionally to the reduction in the level of texture.