Performance of Lead-Free Low Melting Point Fluorphosphate Glass for Emerald Filling

Fluorphosphate glass with the composition of xNaF-7LiF-9BaF₂-7CaF₂-7B₂O₃-(70-x)P₂O₅(x=50、45、40、35、30) was designed and prepared in order to replace the organic materials to fill the emeralds' fissure.The influence of the molar ratio of P₂O₅ and NaF on the physical and chemical properties of glass including the refractive index,density,transformation temperature,softening temperature and chemical stability was discussed.The results show that these series of glass have excellent acid and alkali resistant performance.The glass with x of 30 shows the lowest softening temperature (353℃),and its refractive index and density are in accordance with the requirements of the emerald filling which demonstrates that this lead-free low melting point glass is an ideal candidate for emerald filling.