Lifetime estimation of a zirconia-alumina composite for biomedical applications

Abstract

Objectives: In this work long term stability of a zirconia toughened alumina (ZTA) composite was investigated.

Methods: Accelerated aging tests under hydrothermal environment, in autoclave and hot water, at different temperature, was conducted on material sample. Tetragonal to monoclinic transformation was evaluated by XRD analysis and the monoclinic content was plot as a function of the exposure time. The kinetic of transformation was studied by means Mehl-Avrami-Johnson (MAJ) nucleation and growth model.

Results: An activation energy for tetragonal to monoclinic transformation of 99 kJ/mol was found by the Arrhenius plot of reaction rate, value in agreement with other bibliography works regarding Y-TZP and alumina-zirconia composites. The in vivo hydrothermal stability simulation, estimated by the obtained activation energy, predicts in 65 years the time necessary to reach 25 vol% of monoclinic phase.

Significance: These results support the material suitability in biomedical field, especially in dentistry applications as implantology.

Keywords: Lifetime prediction; Low temperature degradation – aging; Tetragonal to monoclinic transformation; ZTA – zirconia–alumina composite.