Yttria tetragonal zirconia ceramics

R. Moreno, A. J. S nchez-Herencia, and J. S. Moya, "Functionally Gradient Materials by Sequential Slip Casting Alumina-Yttria Tetragonal Zirconia" pp. 149-56 in Ceramic Transactions, Vol. 34, Functionally Gradient Materials. Edited by J. B. Holt, M. Koizumi, T. Hirai, and Z. A. Munir. American Ceramic Society, Westerville, OH, 1993. 

Klimke J, Trunec M, Krell A (2011) Transparent tetragonal yttria-stabilized zirconia ceramics influence of scattering caused by birefringence. J Am Ceram Soc 94 1850-1858... 

Basu, B. (2005). Toughening of yttria-stabilised tetragonal zirconia ceramics. International Materials Reviews, 50, 239-255. doi 10.1179/174328005X41113. 

The first observation of superplasticity in a 3 mol% yttria-stabilized tetragonal zirconia polycrystal ceramic (YTZP) with a grain size of 0.4 pm was reported by Wakai et al in 1986 (Fig. 16.1). Since then, a large number... 

For instance, dislocations have been shown to play a key role in the accommodation process in YTZP, justifying the threshold stress in YTZP, in contrast with the hypothesis that this threshold stress is due to the electric field created by impurity segregation. However, dislocations are not systematically observed in YTZP furthermore it was shown that in yttria-stabilized tetragonal zirconia single crystals, the stress necessary to activate dislocations at 1400°C was over 400 MPa, one order of magnitude higher than the stresses used during superplastic deformation of YTZP at the same temperature. It will be necessary to conduct a systematic study of the microstructure of the monolithic ceramics such as YTZP before and after deformation and to correlate their relationship with the superplastic features. 

Mimurada, J., Nakano, M., Sasaki, K., Ykuhara, Y., and Sakuma, T., Effect of cation doping on the superplastic flow in yttria-stabilized tetragonal zirconia poly crystals , J. Am. Ceram. Soc, 2001, 84, 1817-21. 

Schelling, P.K., Phillpot, S.R., Wolf, D. Mechanism of the cubic-to-tetragonal phase transition in zirconia and yttria-stabilized zirconia by molecular-dynamics simulation. J. Am. Ceram. Soc. 2001, 84,1609-19. 

Wepner, W. and Schubert, H., Electrochemical behavior of yttria-stabihzed tetragonal zirconia, in Advances in Ceramics, Science Technology of Zirconia, Ed. Hobbs,... 

Despite earlier doubts, (Willmann, 1993) zirconia materials, in particular tetragonal zirconia partially stabilised with yttria (Y-PSZ), magnesia (Mg-PSZ) and calcia (Ca-PSZ), have found various applications in biomedical devices, most importantly as hard and tough structural ceramic material for femoral balls in hip endoprostheses (Cales and Stefani, 1995) and as material for restorative... 

International Organization for Standardization ISO/DIS 13356 (1995) Implants for Surgery - Ceramic Materials Based on Yttria-Stabilized Tetragonal Zirconia (Y-TZP), International Organization for Standardization. 

A supersaturated bioinspired solution was used to coat alumina and zirconia substrates with a thin, poorly crystalline layer of OCP that after heat treatment at 1050 °C for 1 h was converted to hydroxyapatite with particle size of 300 nm (Pribosic, Beranic-Klopcic and Kosmac, 2010). Stefanic et al. (2012) applied a related method to rapidly deposit an OCP layer by a two-step process onto yttria-stabilised tetragonal zirconia polycrystal (Y-TZP). 80vol% Mg-PSZ/20 vol% alumina substrates were used by Nogiwa and Cortes (2006) to deposit biomimetically by immersion in 1.4 SBF a bone-like apatite coating of 15-30 pm thickness, using a bed of either wollastonite ceramics or bioactive glass as an additional source of Ca2+ ions. 

Tetragonal zirconia polycrystals (TZPs). These ceramics contain 100 percent tetragonal phase and small amounts of yttria and other rare-earth additives. With bend strength exceeding 2000 MPa, these ceramics are among the strongest known. 

The Glass and Ceramics Institute of the Spanish CSIC carried out an analytical study of new materials used in structural and electrical ceramics, the stoichiometries and impurity contents of which were highly interesting because of their influence on the physico-chemical properties and service response of the pieces [24]. The specific materials studied were tetragonal zirconia stabilized with ceria and yttria (Y-TZP/Ce) lead titanate modified with gadolinium and doped with manganese (Gd-PT) and lead titanate-zirconate modified with lanthanum (PLZT). The first is a structural ceramic and the other two are electrical ceramics. 

The addition of yttria to zirconia not only stabilizes the cubic or tetragonal form but also lowers the temperature ofthe t m transformation. The practical consequence of this is that larger zirconia particles can be retained in the metastable tetragonal form, thus considerably easing any problems associated with the fabrication of a toughened ceramic, such as ZTA. One important feature of this system is the solubility of yttria in zirconia up to a concentration of approximately 2.5 mol% which, in conjunction with a low eutectoid temperature, will facilitate the formation of fully tetragonal ceramics which are referred to as tetragonal zirconia polycrystals (see Section 1.6.4). 

Now, the focus shifts to TZ-3YP which is an yttria-stabilized tetragonal zirconia poly crystalline ceramic (equivalent to 3Y-TZP) containing three moles of yttria. Its hardness was evaluated by an equation given in Sect. 1.10b, as ... 

X-ray diffraction enabled researchers to understand the microstructure of crystalline materials. To reveal the bonding mechanism of hermetic titanium alloys to yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic-brazed joints, X-ray diffraction analysis on the fractured braze joints was conducted and revealed that the nickel titanium oxide (Ni2Ti40) formed at the zirconia ceramic to titanium metal interface is responsible for the bonding [15]. 

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