Tesis doctoral de Juan Jose Pavon Palacio
Ti6al4v alloy is the biomaterial most widely used for hard tissue replacement due to its high biocompatibility and its mechanical properties. However, it is bioinert and, therefore, does not bond directly with the bone. A bioactive glass coating allows a direct bond with the bone because of the precipitation of hydroxycarbonate apatite (hca), and the mechanical behaviour under hertzian forces of these coatings is studied in this doctoral thesis. The research is first addressed to a non-bioactive monolayer glass coating and later to a bilayer glass coating in which the inner layer is the same as the previous one and the outer layer is bioactive. The inner layer has a higher sio2 content in order to ensure the mechanical stability, and the outer layer has a lower sio2 content together with synthetic hydroxyapatite to ensure the bioactivity. The response to monotonic contact loading of the monolayer coating presents three brittle damages (ring, cone and radial cracks) and delamination of the coating. These damages are influenced by the plastic deformation of the substrate which was verified by comparison with the damage in monolithic glasses with the same composition. The ring crack was used as damage criteria for the static and cyclic contact tests. The coating is degradated under static contact due to stress corrosion, while the degradation under cyclic contact, observed by the first time in this kind of materials, is attributed to a mechanism of reduction of the shielding initially present due to a microcracked zone around the crack tip of the pre-existent cracks. The existence of microcracks at the border of the glass particles is possible due to the sintered character of the coating. The ring cracking under both static and cyclic contact was rationalized with the aid of sub-critical crack growth laws. Ring cracking is also the first damage in the outer layer of the bilayer coating during monotonic contact. This outer layer is less resistant to ring cracking due to
Datos académicos de la tesis doctoral «Fractura y fatiga por contacto de recubrimientos de vidrio sobre ti6al4v para aplicaciones biomedicas«
- Título de la tesis: Fractura y fatiga por contacto de recubrimientos de vidrio sobre ti6al4v para aplicaciones biomedicas
- Autor: Juan Jose Pavon Palacio
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 08/11/2006
Dirección y tribunal
- Director de la tesis
- Marcos Juan Anglada Gomila
- Tribunal
- Presidente del tribunal: Luis Llanes pitarch
- José Ygnacio pastor (vocal)
- eduardo Saiz (vocal)
- Antonio Sanchez-herencia javier (vocal)