Toughening method of zirconia ceramics

Zirconia is a special material, the method of toughening is mainly achieved by using the phase change of zirconia!

Pure zirconia is a white solid, and it will appear gray or light yellow when it contains impurities. It can also display various other colors with the addition of a color developer. The molecular weight of pure zirconia is 123.22, the theoretical density is 5.89g/cm3, and the melting point is 2715°C. It usually contains a small amount of hafnium oxide, which is difficult to separate, but has no obvious effect on the properties of zirconium oxide. Zirconia has three crystal forms: monoclinic, tetragonal, and cubic crystal phases. At room temperature, zirconia only appears as a monoclinic phase, and it will transform into a tetragonal phase when heated to about 1100°C, and will transform into a cubic phase when heated to a higher temperature. As the monoclinic phase changes to the tetragonal phase, there will be a large volume change, and a large volume change will occur in the opposite direction when cooling, which will easily cause product cracking, which limits the application of pure zirconia in the high temperature field. However, after adding stabilizers, the tetragonal phase can be stabilized at room temperature, so there will be no sudden changes in volume after heating, which greatly expands the application range of zirconia. The raw material used as stabilizer in the market is mainly yttrium oxide.