Research On The Relaitionship Between Phase-separated, Crystallization, Viscosity And Composition Of Fluoride-free Opal Glass

Phosphate opal glass has less pollution to the environment and people, with precious emulsion performance. With the growing demand of high-grade decorative plates of glass, introducing float process to the production of phosphate opal glass is necessary. The performance of phosphate opaque glass was studies,the phase separation, crystallization characteristics, including which effects on the viscosity of opal glass were investigated, discussed the relationship among phase-separated, crystallization, viscosity and composition, providing theoretical support for the production of float Phosphate opal glass.In this paper, by testing SEM, STEM, XRD, IR, multiple phase-separated of opal glass was ivestigated, the effects of P2O5, B2O3, CaO, Al2O3 content of opal glass on the phase-separated and crystallization were analysised, combined with high temperature viscosity Testing, the effect of P2O5 content on the viscosity of the glass was studied, the relationship between phase-separated and viscosity wasdiscussed. With whiteness test, flexural strength testing, water resistence testing, the effects of composition on the physical and chemical properties of opaque glass was analysised.The results showed that the phase separation occurred at high temperature, it produced at least five different phases by multiple phase-separated, the main phase opacified glass is phosphorus-rich which size is about 300nm. high temperature phase-separated caused a mutation of glass viscosity, showed as the sudden increase of viscosity. Small blocky calcium phosphate crystals precipitated at low levels at the interface of phases.With the increasing of P2O5 content, size of phosphorus-rich phase increases, the whiteness, flexural strength increased, visible light transmittance decreased, glass viscosity increased. Glass with 6% P2O5 content, the size of phosphorus-rich is about 300nm, whiteness is 87.27, with about 15% visible light transmittance, the flexural strength is 108.92MP. Uniform opal glass requires 3% P2O5 content at least. Melt apparent viscosity sensitivity to temperature of opal glass is weaker than ordinary soda lime silicate float glass, but the initial forming temperature is about 180℃higher than ordinary soda lime silicate float glass. B2O3 plays a supporting role in emulsion. The size of phosphorus-rich phase can be controlled by adjusting B2O3 content. With the increasing of B2O3 content, [BO4] changes into [BO3] in the glass network, the density of the glass structure decreased, opaque degree increased first and then decreased, flexural strength decreased. The surface of glass with high content of B2O3 would precipitated cristobalite easily, which has an adverse effect on production.As the CaO content increased, the size of phosphorus-rich phase slightly increased, the amount of crystallization increased. When the CaO content is 11%, the size of phosphorus-rich phase is about 400nm, bending strength is 107.67MP. The bending strength and water resistance were improved with the CaO content increased.Al2O3 stengthen the structure of glass network, Al3+ concentrated in phosphorus-rich phase at a higher level, which is conducive to the stability of the main phase. With the increase of Al2O3 content, the size of phosphorus-rich phase increased, but the rest minor phases were inhibited, crystallization decreased, bending strength and water resistance of glass improved significantly. When Al2O3 content is 3%, the size of phosphorus-rich phase is about 500nm, the flexural strength is 111.81MP.