| As the significant advantages over good gloss, elegant appearance, etc., opal glass is widely used in many fields such as glass ware, lighting, cosmetic package, wine bottles, architectural decoration materials and dental materials.The traditional opaque agents is fluorides. However, the existence of environmental hazards and the refractory erosion problems has been caused growing concern. It is necessary to develop fluoride-free opal glass with excellent properties. Considering its high melting temperature and the additive of large amount of expensive oxide opaque agents, borosilicate opal glass is not the appropriate material, even though it reveals good properties. Phosphate opal glass has a narrow range of opacifying temperature and the opal process is hard to control. In this paper, mixed opacifing opal glass system with oxide opaque agents and phosphate opaque agents was studied.In this paper, current opal glass systems has been firstly researched, and then ZnO-B2O3-SiO2system Opal glass was chose as the basic formulation, which has low expansion coefficient and needn’t second heating treatment. The influence on the properties such as thermal-resistance, softening point temperature and whiteness has been studied by the composition adjustment of Li2O and P2O5.Firstly, current opal glass systems containing fluoride, phosphate, fluorophosphate and phase separation opal glass has been studied. Comparison of four opal glass systems has been investigated by different melting temperatures and property testing. Analysis showed that fluoride opal glass has inferior thermal-resistance and large volatilization of fluoride in spite of its high whiteness. Phosphate opal glass is sensitive to melting technology, which used to cause insufficient whiteness. The properties of fluorophosphate opal glass such as expansion coefficient and whiteness were unsatisfied. In consequence, it is necessary to develop opal glass with mixing opaque agents.Secondly, ZnO-BiO3-SiO2system opal glasses containing different concentrations of Li2O has been prepared, the impact on expansion coefficient, thermal stability, softening temperature and chemical stability was studied by the diverse replacement ratio (Li2O replace of Na2O, ranging from0%to4wt%). The effects of structure and properties of the opal glass were investigated by means of X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that the non-crystal structure of the glass was not changed with the additive of Li2O replacing. With the increasing of Li2O and the decreasing of Na2O, the expansion coefficient firstly was decreased, and then increased when the concentration of Li2O reached2wt%and above. Meanwhile, the softening point temperature and density of the opal glass were firstly increased and then decreased since the [BO3] glass structure has been transformed into [BO4].It was the change of chemical composition and glass structure that influenced the properties of glass.Finally, ZnO-B2O3-SiO2opal glasses containing different contents of P2O5(0-4wt%) were prepared. The micro-structure and chemical structure of the opal glass were characterized by XRD, SEM and FTIR, and the effect of P2O5on glass properties, such as density, whiteness and water-resistance was discussed. The results indicate that [PO4] structure appears with the addition of P2O5, which can effectively promote the phase separation in this glass, and improve the even distribution of opal particles in glass matrix. As a result, the density, whiteness and water-resistance of the borosilicate glass were improved. However, the LigZnP4O17crystallization behavior was investigated with the addition of P2O5above2wt%, which decreased the whiteness and water-resistance of the borosilicate glass. |
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