Zirconia toughening

Zirconia toughened mullite (ZTM), 5 571 Zirconia, with 18% Ce02... 

Becher, P.F. and Tiegs, T.N. (1987). Toughening behavior involving multiple mechanisms whisker reinforcement and zirconia toughening. J. Am. Ceram. Soc. 70, 651-654. 

What exactly takes place here is not yet completely clear. For the transformation of the zirconium crystal in their free state a temperature of appr. 1200 °Cis needed. It will be clear that this temperature will not be reached in the situation of figure 14.8. Apparently we are not only dealing with a transfer of energy here. To end this item, one more technical term ZTA (Zirconia Toughened Alumina), which is aluminium oxide which has been made tougher by adding zirconium. 

Thompson, I., Rawlings, R.D. (1991), Monitoring thermal shock of alumina and zirconia-toughened alumina by acoustic techniques , J. Mater. Sci., 26, 4534-4540. 

N. Claussen and G. Petzow, Whisker-Reinforced Zirconia-Toughened Ceramics , in Tailoring Multiphase and Composite Ceramics, eds. R. E. 

P. F. Becher and T. N. Tiegs, Toughening Behavior Involving Multiple Mechanisms Whisker Reinforcement and Zirconia Toughening, J. Am. Ceram., 70[9], 651-654 (1987). 

Zirconia Toughened Ceramics. Zirconia particles can be embedded in host matrices to form a variety7 of transformation-toughened... 

C Properties of zirconia toughened alumina.. ZTA, depend on the specific microstiucture and the proportions of zirconia and alumina. d To convert MPa to psi, multiply by 145. 

Fig. 15. Scanning electron microscope photomicrograph of multilayer TiB2/Al203 with zirconia toughened alumina (Adapted from DeAngelis and Weiss, 1990).

Low, I.M., Skala, R, Richards, R. and Perera, D.S. (1993). Synthesis and Properties of Novel Mullite-Zirconia-toughened Alumina Composites . J. Mater. Sci. Lett. 12, 1985-1987. 

Pratapa, S. and Low, I.M. (1996). The Effects of Spodumene Addition on Properties of Functionally-graded Aluminium Titanate/Zirconia-toughened Alumina Composites . In Proceedings of the 2nd International Meeting of Pacific Rim Ceramic Societies. 

Gutierrez-Mora, F. et. al.. Influence of internal stresses on superplastic joining of zirconia-toughened alumina, Acta Mater. 50 (2002) 3475-3486. 

It has been known for some time that considerable improvement of the mechanical properties of alumina in terms of flexural strength, fracture toughness, yield strength and elastic modulus can be achieved by adding particles of stabilised zir-conia as a structural reinforcement (see Chapter 4.1.2). Such ceramics are known as ZTA (zirconia-toughened alumina), duplex ceramics or dispersion ceramics. 

Figure 4.2 Reinforcement mechanism of a ZTA (zirconia-toughened alumina) duplex ceramics with agglomerated Y-PSZ particles.

Zirconia-toughened ceramics (ZTCs). These consist of tetragonal or monoclinic zirconia particles finely dispersed in other ceramic matrices such as alumina, mullite, and spinel. 

Jang, H. M, and Moon, J. H., Homogeneous fabrication and densification of zirconia-toughened alumina (ZTA) composite by the surface-induced coating, J. Mater. Res., 5(3), 615 (1990). 

Figure 1.5 Microstructure of a zirconia-toughened alumina back-scattered electron image using the SEM. The bright phase is zirconia.

Figurel.il Failure origin in a zirconia-toughened alumina, caused by the presence of a zirconia aggregate in the starting powder. (Reproduced courtesy of CRC Press, Boca Raton, FL.)...

Figure 3.20 Use of silver nitrate to highlight grain boundary miciocracks in a zirconia-toughened alumina. The high contrast for the silver nitrate is obtained in the back-scattered mode of the SEM.

FIGURE 24.27 Two-phase ceramics, (a) As sintered and (b) heat treated at 1600°C for 30 hours. ZTA 30% (zirconia-toughened aiumina with 30 voi% YSZ containing 10 moiar% yttria). 

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