Research Of Lead-free Crystal Glass Based On BaO Replacing PbO

Crystals with the features of glittering, transparent, beautiful and spectacular, are often used as ornamental, sculpture, jewelry, crystal ball. It’s necessary to look for alternatives for natural crystal because of the long formation cycle and expensive price of natural crystal. Due to high refractive index, good chemical stability and other advantages of properties, Lead crystal glass has become a very important alternative for natural crystal, which also has a very wide range of applications. But conventional lead crystal glass contains massive lead oxide and relevant lead dissolutions, which can be absorbed through many ways. Excessive exposure to lead and its compounds may lead to palpitation, nervous, and changes in the nervous system, such as mental confusion and anemia in severe cases. Therefore,it is the trend to prepare lead-free crystal glass.In this paper, lead-free glasses with SiO2-R2O-BaO-ZnO (R=Na, K) system have been prepared by the conventional melt quenching technique, where lead was replaced by barium. This lead-free glasses can solve the problem of lead dissolution in the decorative glass fundamentally. The structure of the investigated glass system was studied by the FT-IR test, the density was measured by Archimedes method, refractive index was measured by Abbe refraction meter and thermal expansion coefficients were tested with Dilatometer. It has studied the influence of the content of BaO and alkali on the properties of the glass, what’s more, SiO2was partly replaced by B2O3to improve its chemical stability. The results show that the density of the glasses is between2.95and3.13g·cm-3, refractive index is between1.559and1.565. when immersed in water of90℃for6hour, the average corrosion ratio is1.42-0.75×10-8g·mm-2·min-1, the thermal expansion coefficient during30-400℃is70.42-91.42×10-7℃-1, the glass transition temperature and softening temperature is511-567℃and566-641℃, respectively.In this paper, we prepared the lead-free crystal glass in B2O3-BaO-ZnO system with high refractive index of1.580-1.641using barium oxide and zinc oxide to replace lead oxide. Through the study we found that the density of lead-free crystal glass increased from3.06to3.89g·cm-3with the content of barium oxidation increases, which completely meets the requirements of the density of crystal glass (≥3.0g·cm-3). Refractive index increased from1.580to1.641which bigger than the traditional lead crystal glass (1.5400-1.5650), corrosion rate in the water was6.31-11.64×10-9g·mm-2·min-1, which indicated that lead-free crystal glass has better corrosion resistance. From Infrared spectrum, we can see,[BO4] tetrahedron in the glass gradually transformed into [BO3] triangle with the change of the composition.This simple, low costly, free-environment pollution and harmless preparation method in this paper, which based on the traditional glass-molting method, has prepared the lead-free glass. This glass can take the place of the lead glass which is commonly used as decorative materials to meet the demands of high-grade crystal glass products.