Decoration of Indentation Cracks in 3y-tzp by Hydrothermal Ageing

Indentation cracks on ceramics are frequently used not only for the semi-empirical determination of the fracture toughness KIC but also as a method for generating semielliptical surface cracks to be used in as starting cracks in fracture and fatigue studies. Tetragonal zirconia stabilized with 3 % mol of yttria (3Y-TZP) is a biocompatible ceramic with good mechanical properties which is used in dental and femoral prostheses applications. Additionally, 3Y-TZP is susceptible to low temperature degradation in which a hydrothermal environment induces a phase transformation of the exposed surface. In the present work, this degradation susceptibility of 3Y-TZP has been used to reveal indentation crack profiles on specimens which were tested by flexural bending afterwards. Different types of 3Y-TZP were considered which presented different degrees of susceptibility to hydrothermal degradation. It is shown that these cracks are clearly decorated by the water vapour which make them easily revealed on the fracture surfaces. An exposition of few hours in autoclave is sufficient for revealing the indentation cracks on the fracture surface without affecting the fracture load of the specimens. Therefore, the method can be applied to visualize with precision the geometry of indentation cracks which are used to determine the fracture toughness. PALABRAS CLAVE: Cerámicas, Resistencia, Biomateriales