Toughening method of zirconia ceramics

Zirconia is a special material. The toughening method is mainly achieved by using the phase transformation of zirconia! Pure zirconia is a white solid, and it will appear gray or light yellow when it contains impurities. Various other colors are displayed. The molecular weight of pure zirconia is 123.22, the theoretical density is 5.89g/cm3, and the melting point is 2715℃. Usually contains a small amount of hafnium oxide, which is difficult to separate, but has no significant effect on the properties of zirconium oxide. There are three crystal forms of zirconia: monoclinic, tetragonal, and cubic. At room temperature, zirconia only appears as a monoclinic phase, and when heated to about 1100 °C, it transforms into a tetragonal phase, and when heated to a higher temperature, it transforms into a cubic phase. Since a large volume change occurs when the monoclinic phase changes to the tetragonal phase, and a large volume change occurs in the opposite direction when cooling, it is easy to cause cracking of the product, which limits the application of pure zirconia in high temperature fields. . However, after adding the stabilizer, the tetragonal phase can be stabilized at room temperature, so there will be no sudden change in volume after heating, which greatly expands the application range of zirconia. The raw material used as stabilizer on the market is mainly yttrium oxide.