Fracture toughness, strength and slow crack growth in a ceria stabilized zirconia–alumina nanocomposite for medical applications
✍ Scribed by Rajaa Benzaid; Jerome Chevalier; Malika Saâdaoui; Gilbert Fantozzi; Masahiro Nawa; Luis Antonio Diaz; Ramon Torrecillas
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 620 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0142-9612
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✦ Synopsis
Mechanical properties and slow crack growth (SCG) behavior of a 10Ce-TZP/Al 2 O 3 nanocomposite currently developed as a biomaterial are considered. Fracture toughness is determined for sharp, long (double torsion) and short (indentation) cracks and a good agreement is found between the two types of cracks. The main toughening mechanism in the nanocomposite is the tetragonal to monoclinic phase transformation of the ceria-stabilized zirconia (Ce-TZP) phase. Transformation at the surface of ground specimens leads to surface compressive induced stresses and an increase in strength. Crack velocity curves (V-K I curves) are obtained under static and cyclic fatigue using the double torsion method. The static V-K I curve in air reveals the three stages characteristic of stress corrosion with a threshold K I0 w 4.5 MPa m 1/2 and a fracture toughness of 8.8 MPa m 1/2 significantly higher than those of currently used inert bioceramics (i.e. alumina and Y-TZP). A crack growth accelerating effect is shown under cyclic loading, correlated with a decrease in the threshold. However, the cyclic fatigue threshold (4 MPa m 1/2 ) still stands above that of current biomedical grade alumina and zirconia.