Zirconia (ZrO2) nature zirconia flap disc mineral raw materials, mainly baddeleyite and zircon . Department of the deep igneous zircon minerals , color yellow, brown , yellow , etc. , specific gravity 4.6-4.7 , hardness 7.5 , with a strong metallic luster glazes for ceramic materials used . Pure zirconia is a high refractory material , the melting temperature of about 2900 ℃ it improves the high temperature viscosity of the glaze and expanded temperature range of viscosity , has good thermal stability , in an amount of 2% -3 % of the , to improve the anti-cracking performance of the glaze . Also because of its great chemical inertia , it can improve the chemical stability of the glaze and acid capacity , but also play a role in emulsions . In the construction of multi- use ceramic glaze zircon, the general amount of 8% -12% . And for the " underglaze white" the main raw material , zirconium oxide green pigment yellow toner good help , if you want to get a better vanadium zirconium yellow pigment must choose quality of pure zirconia. Pure zirconia as a white solid , containing impurities will appear gray or yellow, adding chromogenic agent may also display a variety of other colors . The molecular weight of pure zirconia 123.22 , theoretical density is 5.89g/cm3, a melting point of 2715 ℃. Usually contain a small amount of hafnium oxide is difficult to separate , but zirconia no significant effect on performance . Zirconia has three crystal forms: monoclinic , tetragonal , cubic crystalline phase . Room temperature monoclinic zirconia phase appears only in heated to about 1100 ℃ into a tetragonal phase , heated to a higher temperature will be converted to cubic phase . Since the tetragonal to monoclinic phase transformation of the time will have a larger volume change , the cooling will in the opposite direction when there is a greater volume change , likely to cause cracking of the product , pure zirconia limiting the field of application in high . But after adding stabilizer , the tetragonal phase can be stable at room temperature , so the volume does not occur after heating mutations greatly expand the range of applications of zirconia . Since zirconia materials with high hardness, high strength , high toughness, high wear resistance and excellent chemical resistance and so on physical and chemical properties , zirconia has been in ceramics, refractories , machinery, electronics , optics , aerospace, biological, chemical , and so widely applied in various fields .