Towards the prediction of hydrothermal ageing of 3Y-TZP bioceramics from processing parameters.

Hydrothermal ageing of yttria-stabilized tetragonal zirconia ceramics can have a strong influence on the lifetime of zirconia devices. Ageing kinetics are often described by the Mehl–Avrami–Johnson equation, most often used as a phenomenological description. This work seeks to relate the parameters of MAJ equations (V max , n, b 0 and Q) to microstructural characteristics of the zirconia material: grain sizes, Y 2 O 3 partitioning, monoclinic, tetragonal and cubic phases ratio. Samples with identical nominal composition of 3Y-TZP were prepared with grain sizes ranging from 190 nm to 773 nm. From their microstructural parameters, a relationship between microstructural parameters and sintering cycles was first proposed, followed by a relationship between ageing parameters and microstructural parameters. These results provide a convenient framework to better develop the sintering cycle of zirconia biomaterial in order to maximize their resistance to hydrothermal ageing. [ABSTRACT FROM AUTHOR]