Author:Site Editor Publish Time: 22-08-2017 Origin:Site
Zirconia is a natural zirconia mineral material, mainly oblique zircon and zircon. Zirconite igneous rock deep mineral, the color is yellow, brown, yellow green, etc., the proportion of 4.6-4.7, hardness of 7.5, with a strong metallic luster, zirconia ceramic glaze for raw materials.
Pure zirconia is a high grade refractory material with a melting temperature of about 2900 ° C. It can improve the high temperature viscosity of the glaze and increase the viscosity of the temperature range, with good thermal stability, its content is 2% -3% , Can improve the anti-cracking performance of glaze. But also because of its chemical inertia, it can improve the chemical stability of glaze and acid and alkali resistance, but also play the role of opacifying agent. In the construction of ceramic glaze in the use of zircon, the general amount of 8% -12%. And for the "underglaze white" the main raw material, zirconia for the yellow-green pigment good auxiliary agent, if you want to get a better vanadium zircon yellow pigment must be selected pure pure zirconia.
Pure zirconia is a white solid that contains impurities when it is gray or light yellow, and the addition of the developer can also show a variety of other colors. The molecular weight of pure zirconia is 123.22, the theoretical density is 5.89g / cm3, and the melting point is 2715 ℃. Usually containing a small amount of hafnium oxide, it is difficult to separate, but the performance of zirconia no significant impact.
Zirconia has three crystal forms: monoclinic, tetragonal, cubic crystal phase. At room temperature zirconia only monoclinic phase appears, heated to 1100 ℃ or so into a tetragonal phase, heated to a higher temperature will be converted into cubic phase. Due to the monoclinic phase of the four-phase transition will produce a larger volume change, when the cooling will be in the opposite direction of the larger volume changes, likely to cause the product cracking, limiting the use of pure zirconia in the field of high temperature applications The However, after the addition of stabilizer, tetragonal phase can be stable at room temperature, so no change in volume after heating, greatly expanding the scope of application of zirconia.