Pure Zirconium dioxide undergoes a phase transformation from monoclinic to tetragonal at about 1173 °C. The large volume change accompanying this transition (about 9%) lead to cracking when concerning structural monolithic ceramics like crucibles. Stabilization of the tetragonal structure of Zirconia over wider range of temperatures is accomplished by substitution of some of the Zr4+ ions within the crystal lattice with slightly larger ions, like those of Y3+. The resulting doped Zirconia materials are termed Yttria Stabilized Zirconia (YSZ) or Yttria-stabilized Tetragonal Zirconia Polycrystal (Y-TZP). Polycrystalline materials such as YSZ, own their excellent mechanical properties the tetragonal crystal structure.
Fully Yttria Stabilized Zirconia, 8YSZ (8% by mole Yttria) ceramics are used when an application requires a crucible that is exceptionally strong, wear-resistant and chemically inert at extremely elevated temperature. Also is the material that preferred for most biocompatible applications. Fully Yttria Stabilized Zirconia (8YSZ) is the material with the higher strength from the materials we offer and exhibits a Flexural strength that is higher than Nitrides and can approach the value of Carbides. This property significantly extends the reliability and lifetime of crucibles made with stabilized Zirconia.
Fully Yttria Stabilized Zirconia (8YSZ) technical ceramics offers some advantages over Alumina. Namely, Fully Yttria Stabilized Zirconia 8YSZ crucibles compared to Alumina crucibles are more refractory and have much lower thermal conductivity, have higher quality surface finish, are denser and are even 4 times superior in terms of strength (this property degrades when temperature exhibits 1000 C). However, are considerably more expensive even than purest grades of Alumina and are less thermal shock resistant. The main reason for 8YSZ high cost is that both Zirconia and Yttria raw material are rare compared with Alumina and thus expensive.