Breviary Technical Ceramics


      Werkstoffe der technischen Keramik

 Zirconium Oxide Toughend Aluminium Oxide

In practice, this is usually simply known as ZTA (zirconia toughened alumina). Its properties depend strongly on the mixing ratio of aluminium oxide to zirconium oxide, and on the details of the processing.

Figure 16: Microstructure of a ZTA with a low proportion of zirconium oxide

Low proportions of zirconium oxide, up to approx. 10% by volume, allow improved values, in comparison with aluminium oxide, for

  • bending strength
  • KIC factor,
  • modulus of elasticity and
  • larger coefficients of linear expansion to be achieved.

Versions of the material containing higher concentrations of zirconium oxide, if appropriately processed, develop platelets in the microstructure, which contributes to an improvement in some material properties (ZPTA ceramics). These and other measures taken to optimise properties permit the achievement of outstanding figures for

  • bending strength
  • modulus of elasticity and
  • thermal behaviour

that are superior to those of Y-ZTP (tetragonal zirconium oxide stabilised with yttrium oxide).

Figure 17: ZTA with a high proportion of zirconium oxide, shown as a breakage
microstructure in order to reveal the platelets


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