高折射率低密度眼镜玻璃

High Refractive Index and Low Density Ophthalmic Glasses

High refrative index and low density ophthalmic glasses can be obtained by using borosilicate glass as matrix glass together with high valent oxides, such as TiOa, ZrO2 etc, and low density oxides, such as CaO, SrO, MgO etc. The effect of chemical composition on. devitrification and thermal shock resistance of glasses is discussed in the present paper. The devitrification of glass can be prevented by adding a little B2O3 and introducing Al2O3, SrO and MgO into glass. Substituting CaO by MgO, ZnO will help to lower the thermal expansion coefficient and to improve thermal shock resistance of glass at the same time. In addition, the material and pre-heating temperature of forming mould and structure of lehr affects the thermal shock resistance as well.