Properties and Crystal Morphology of Zirconia Ceramics

Zirconia ceramic properties
There are two main types of zirconium-containing ores in nature: baddeleyite (zirconia) and zircon (zirconia-SiO:). Zirconia is extracted from zirconium-containing ore. The purer zirconia powder is yellow or gray. High-purity zirconia powder is white. However, it often contains hafnium dioxide impurities. The chemical properties of the two are similar and they are not easy to separate. They also have similar effects on the electrical properties of the material. The density of zirconia is 5.49 gcm3 and the melting point is 2715°C.

Crystalline morphology and crystal form transformation of zirconia Zr0 at different temperatures. It exists in three forms of allom orphish, namely cubic system, monoclinic system and tetragonal system. The zirconia densities of the three crystal forms are: 5.65 gcm for monoclinic, 6.10 gcm for tetragonal, and 6.27 gcm for cubic. Its transformation is as follows: monoclinic-Z,o. 1170 St. Quartet-Z, o. 2370 tC cubic-Z, o. 2715 -C Liquid Phase

The transformation from monoclinic to tetragonal is mainly introduced here. This transformation is accompanied by a volume change of around 7%. When heated, it changes from monoclinic-zirconia to tetragonal-Zr0: volume shrinks; when cooling, it changes from tetragonal-zirconia to monoclinic-zirconia, and volume expands. But this shrinkage and expansion do not occur at the same temperature, the former is about 1200°C and the latter is about 1000°C.