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Biomaterials. 2008 Sep;29(27):3636-41. doi: 10.1016/j.biomaterials.2008.05.021. Epub 2008 Jun 24.

Fracture toughness, strength and slow crack growth in a ceria stabilized zirconia-alumina nanocomposite for medical applications.

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1
Université de Lyon, INSA-Lyon, MATEIS, CNRS UMR 5510, 20 Avenue Albert Einstein, Batiment Blaise Pascal, 69621 Villeurbanne, Cedex, France.

Abstract

Mechanical properties and slow crack growth (SCG) behavior of a 10Ce-TZP/Al2O3 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) approximately 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.

[Indexed for MEDLINE]

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