Low‐temperature aging of baddeleyite‐based Ca‐TZP ceramics

The aging kinetics during low‐temperature aging of calcia‐stabilized tetragonal zirconia polycrystal (Ca‐TZP) ceramics prepared by high‐energy milling of natural zirconia mineral (baddeleyite) was studied by X‐ray diffraction under hydrothermal treatment conditions. Aging kinetics was investigated for ceramics with different contents of calcia. It was found that the kinetics may be well‐described within Johnson‐Mehl‐Avrami‐Kolmogorov model. Model parameters were determined by data fitting procedure. Change in exponential factor within Johnson‐Mehl‐Avrami‐Kolmogorov model with time is shown. Analytical model to describe aging kinetics is proposed. The transformation nucleation rate, initial diameter, and depth of the transformed areas and their growth rates are estimated. Degradation of hardness and fracture toughness is also reported for Ca‐TZP after low‐temperature aging for different contents of the stabilizer.