Yttria-stabilized tetragonal zirconia polycrystal

Y-TZP = yttria-stabilized tetragonal zirconia polycrystal. LAS = lithium alurninosiUcate. 

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... 

Moreno, R., Requena, J., and Moya, J.S., Slip casting yttria-stabilized tetragonal zirconia polycrystals, J. Am. Ceram. Soc., 71,1036, 1988. 

Bioceramic Applications The performance requirements of yttria-stabilized tetragonal zirconia polycrystal (TZP) to form biocompatible, strong components for use as hip, knee, and dental prostheses, and which demonstrate long-term resistance against aggressive body fluids and mechanical wear and tear, during a predicted lifetime of 15-20 years in the human body, include ... 

Figure 10.33 Femoral heads produced from medical-grade yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) material (a-c) and alumina (d) irradiated for lOmin with 7-rays obtained from a Co source with a minimum energy dose of25kCy. The femoral heads shown on the right side in panels a-d...

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]. 

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). 

Table 11 shows the physical characteristic of tetragonal zirconia stabilized with yttria (TZP = tetragonal circonia polycrystals) and magnesium oxide partially stabilized zirconia (Mg-PSZ = magnesia partially stabilized zirconia [33],... 

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