Critical effect of cubic phase on aging in 3 mol% yttria-stabilized zirconia ceramics for hip replacement prosthesis

TL;DR

This study investigates how the presence of a cubic phase in 3Y-TZP ceramics influences their aging behavior, highlighting that cubic grains can accelerate degradation, especially in materials sintered at higher temperatures.

Contribution

It reveals the critical role of cubic phase presence in affecting aging resistance of 3Y-TZP ceramics used in hip prostheses, emphasizing the impact of sintering temperature on microstructure and durability.

Findings

Cubic grains are enriched in yttrium, depleting neighboring tetragonal grains.

Cubic phase presence accelerates the tetragonal-to-monoclinic transformation during aging.

Higher sintering temperature leads to more large cubic grains, reducing aging resistance.

Abstract

The isothermal tetragonal-to-monoclinic transformation of 3Y-TZP ceramics sintered at two different temperatures (1450{\deg}C and 1550{\deg}C) and duration (2 and 5 h) is investigated at 134{\deg}C in steam. Particular attention is paid to the presence of a cubic phase and its effect on isothermal aging. Sintering at 1550{\deg}C can result in a significant amount of large cubic grains in the specimens, that have a detrimental impact on aging resistance, especially for the first stage of the aging process. Cubic grains appear to be enriched in yttrium, which in turn leads to a depletion of yttrium in the neighboring tetragonal grains. These grains will act as nucleation sites for tetragonal-to-monoclinic transformation. Even for specimens sintered at lower temperature, i.e. 1450{\deg}C, the presence of a cubic phase is expected from the phase diagram, leading to a significant effect on aging sensitivity.