Título:
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Contact damage in artificially aged 3Y-TZP
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Autor/a:
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Armas Sancho, Zamir de; Mestra Rodríguez, Álvaro Miguel; Jiménez Piqué, Emilio; Anglada Gomila, Marcos Juan
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Otros autores:
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Universitat Politècnica de Catalunya. Departament de Ciència dels Materials i Enginyeria Metal·lúrgica; Universitat Politècnica de Catalunya. CIEFMA - Centre d'Integritat Estructural, Micromecànica i Fiabilitat dels Materials |
Abstract:
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Tetragonal zirconia polycrystals doped with 3% mol of yttria (3Y
-
TZP) are increasingly
employed
as implants in the
human
body, because they
are biocompatible and
have relatively high strength and fracture toughness. These
properties are related to the small submicrometer grain size and to the operation of a toughening mechanism
around
cracks which is referred
to
as phase tra
nsformation toughening. Another important feature of 3Y
-
TZP is the
phenomenon of low temperature degradation (LTD) that takes place in contact with water at temperatures in an interval
around 250 ºC. Water activates t
-
m transformation at the surface and pr
ogresses inside the body producing a t
-
m surface
transformed layer. As a result, roughness and microcracking are produced in the surface. In a first stage, for short times
of
ageing
, this layer is responsible for degradation of surface mechanical propertie
s; at a later stage, after long
degradation times, it induces a strong reduction in the bulk strength.
In this paper we present a study of the mechanical behaviour of hydrothermal degraded
3Y
-
TZP
under monotonic
and
cyclic
spherical indentation. The inves
tigation is focused mainly on analyzing the mechanical response of the material
under spherical indentation in terms of the degraded layer. Plastic deformation and cracking induced by spherical
contact loading are studied under increasing loads in hydrothe
rmally degraded and in as sintered specimens.
The
contact hardness and elastic modulus of the degraded layer are extracted from nanoindentation using continuous
stiffness measurements.
It is found that permanent damage induced in degraded specimens is alwa
ys larger than in as
sintered specimens. Critical loads to induce ring cracking in degraded specimens are lower than in as sintered specimens |
Materia(s):
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-Àrees temàtiques de la UPC::Enginyeria dels materials -Implants, Artificial -Zirconium oxide -Contact Fatigue -Strength Degradation -Zirconia -Implants artificials -Zirconi |
Derechos:
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Attribution-NonCommercial-NoDerivs 3.0 Spain
http://creativecommons.org/licenses/by-nc-nd/3.0/es/ |
Tipo de documento:
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Artículo - Versión publicada Artículo |
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