Lifetime estimation of a zirconia-alumina composite for biomedical applications.
OBJECTIVE
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.


CONCLUSIONS
These results support the material suitability in biomedical field, especially in dentistry applications as implantology.
Faenza Technical Unit on Material Technologies (UTTMATF), ENEA, Faenza, Italy. Electronic address: paride.fabbri@enea.it.
Paride
P
Fabbri
GHIMAS S.p.A. MeLab, Brindisi, Italy; Institute of Orthopedics and Traumatology, Catholic University, Roma, Italy.
Corrado
C
Piconi
Faenza Technical Unit on Material Technologies (UTTMATF), ENEA, Faenza, Italy.
Emiliano
E
Burresi
Faenza Technical Unit on Material Technologies (UTTMATF), ENEA, Faenza, Italy.
Giuseppe
G
Magnani
Faenza Technical Unit on Material Technologies (UTTMATF), ENEA, Faenza, Italy.
Francesca
F
Mazzanti
Faenza Technical Unit on Material Technologies (UTTMATF), ENEA, Faenza, Italy.
Claudio
C
Mingazzini
D000537:Aluminum Oxide / Q000737:chemistry*; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D014961:X-Ray Diffraction; D015040:Zirconium / Q000737:chemistry*
D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide
Lifetime prediction; Low temperature degradation – aging; Tetragonal to monoclinic transformation; ZTA – zirconia–alumina composite