A brief introduction of zirconium oxide
The basic properties of zirconium oxide:
Zirconium dioxide has high boiling point, melting point and high hardness, and it's the insulator at normal temperature, but it's conductive at high temperature and other excellent properties. The thermal conductivity of zirconium oxide (1000℃, 2.09W/ (m* K) is low, linear expansion coefficient (25 ~ 1500 ℃ 9.4 x 10-6/ ℃) is large, high strength of structure at high temperature. When the temperature achieve 1000℃, the compressive strength can up to 1200 ~ 1400MPa. Good conductivity, and it has a negative temperature coefficient, the resistivity is 104 Ω•cm at 1000 ℃, it’s 6 -7 Ω•cm. Good chemical stability, it doesn't work with a variety of molten metal, silicate, glass below 2000℃. Caustic, carbonate and various acid (except for concentrated sulfuric acid and hydrofluoric acid) solution and zirconium oxide doesn't work.
Applications of zirconium oxide:
The pure zirconium oxide is a kind of advanced refractory raw material, its melting temperature is about 2900℃ and it can improve the high temperature viscosity of glaze and expand the range of temperature change in the viscosity. And it has good thermal stability, when its content achieves 2%-3%, it can improve the anti cracking performance of glaze. Because it is inert, so it can improve the chemical stability and acid and alkali resistance of the glaze, what's more, it can play the role of opacifying agent. The zircon is mostly used in building ceramic glazes, general dosage is 8% - 12%. And it's the main raw material of "glaze white", zirconia is a good color developer of yellow green pigments. If you want to obtain a better vanadium zirconium yellow pigment, you must use pure zirconium oxide.
The pure zirconia is a white solid, when it contains the impurities, it will appear gray or yellow. If the chromomeric agent is added, it can also display a variety of other colors. The molecular weight of pure zirconium oxide is 123.22, the theoretical density is 5.89g/cm3, the melting point is 2715 ℃. Usually it contains a small amount of hafnium oxide which is difficult to separate, but it didn't have any obvious effect on the properties of zirconia. Zirconia has three kinds of crystal morphology: monoclinic, tetragonal, cubic phase.
The zirconia only appear as monoclinic phase, when it is heated to 1100℃, it will transforms to the tetragonal phase, if you heated it to a higher temperature, it will be transformed into the cubic phase. Because monoclinic transform to tetragonal phase, it will produce the large volume change. When you cool it, it will appear a large volume change in the opposite direction, which is easy to cause the product cracking. Therefore, it will limit the application of pure zirconia in high temperature field. However, the tetragonal phase can be stable at room temperature after the stabilizer is added, so it won't happen volume mutation after heating, the scope of application of zirconium oxide is greatly expanded.
Zirconium dioxide has high boiling point, melting point and high hardness, and it's the insulator at normal temperature, but it's conductive at high temperature and other excellent properties. The thermal conductivity of zirconium oxide (1000℃, 2.09W/ (m* K) is low, linear expansion coefficient (25 ~ 1500 ℃ 9.4 x 10-6/ ℃) is large, high strength of structure at high temperature. When the temperature achieve 1000℃, the compressive strength can up to 1200 ~ 1400MPa. Good conductivity, and it has a negative temperature coefficient, the resistivity is 104 Ω•cm at 1000 ℃, it’s 6 -7 Ω•cm. Good chemical stability, it doesn't work with a variety of molten metal, silicate, glass below 2000℃. Caustic, carbonate and various acid (except for concentrated sulfuric acid and hydrofluoric acid) solution and zirconium oxide doesn't work.
Applications of zirconium oxide:
The pure zirconium oxide is a kind of advanced refractory raw material, its melting temperature is about 2900℃ and it can improve the high temperature viscosity of glaze and expand the range of temperature change in the viscosity. And it has good thermal stability, when its content achieves 2%-3%, it can improve the anti cracking performance of glaze. Because it is inert, so it can improve the chemical stability and acid and alkali resistance of the glaze, what's more, it can play the role of opacifying agent. The zircon is mostly used in building ceramic glazes, general dosage is 8% - 12%. And it's the main raw material of "glaze white", zirconia is a good color developer of yellow green pigments. If you want to obtain a better vanadium zirconium yellow pigment, you must use pure zirconium oxide.
The pure zirconia is a white solid, when it contains the impurities, it will appear gray or yellow. If the chromomeric agent is added, it can also display a variety of other colors. The molecular weight of pure zirconium oxide is 123.22, the theoretical density is 5.89g/cm3, the melting point is 2715 ℃. Usually it contains a small amount of hafnium oxide which is difficult to separate, but it didn't have any obvious effect on the properties of zirconia. Zirconia has three kinds of crystal morphology: monoclinic, tetragonal, cubic phase.
The zirconia only appear as monoclinic phase, when it is heated to 1100℃, it will transforms to the tetragonal phase, if you heated it to a higher temperature, it will be transformed into the cubic phase. Because monoclinic transform to tetragonal phase, it will produce the large volume change. When you cool it, it will appear a large volume change in the opposite direction, which is easy to cause the product cracking. Therefore, it will limit the application of pure zirconia in high temperature field. However, the tetragonal phase can be stable at room temperature after the stabilizer is added, so it won't happen volume mutation after heating, the scope of application of zirconium oxide is greatly expanded.
