The Study On The Vitrified Tiles Opaicfier

In modern decorative ceramic, vitrified tiles, especially white vitrified tiles is wide application because of its unique appearance has been widely applied. Currently, the main opacifier is zircon. Zircon crystals which formed in vitrified tiles have different refractive with glass caused light scattering, it makes vitrified tiles whiteness. Zircon has many drawbacks: zircon associated with the radioactive elements and is difficult to separate in processing, it will be harmful to the human if use too much zircon. High-grade zircon is shortage in china and imports increased every year, it makes zircon expensive. Quality ceramic materials become fewer, vitrified tiles have low whiteness, therefore need new opacifier.This paper study on the economic opacifier to replaces zircon. Choose apatite and talcum as major material, study on the two systems using traditional process, whiteness is 66 and 65. In apatite system choose apatite, Magnesium oxide, zinc oxide and cerium oxide. Orthogonal experiment has 4 factors and 3 horizons which using to research the best formula. The best formulation is apatite12%,MgO1%,ZnO1% CeO₂0.5% and whiteness is 70, the original sample whiteness is 49, the sample contain 10% zircon whiteness is 67, the whiteness enhance obviously. Compare the samples with opacifier and original sample, test their acid resistively, alkali resistively, density and Vickers hardness, approve opacifier not effect the vitrified tiles' basic performance.Original samples for acicular crystals of mullite and a small amount of quartz, particle diameter are 0.1μm. The best sample mainly for flake crystals of mullite and Ca₉Al(PO₄)₇, particle diameter are 0.5-1μm. Talc system mainly for plate crystals of mullite and Mg₃Al₂(SiO₄)₃, particle diameter are 1μm. Some P enters the glass phase which replaced part of Si form the network and promotes crystallization. When the particle diameter near 0.4-0.75μm which is the wavelength of visible light. Crystal has a strong scattering to the visible light so improve the whiteness.Study on technological conditions such as sintering temperature, holding time and the particle diameter which impact the whiteness. When sintering temperature is 1200°C, hold for 10-15 minutes and the particle diameter near 0.4-0.75μm lead the vitrified tiles with high whiteness.