Crystallization behaviors of R 2O–Al 2O 3–SiO 2 glass–ceramics for use as anodic bonding materials

Abstract

In this work, the crystallization behaviors of R 2O–Al 2O 3–SiO 2 (R means K, Na and Li) glass–ceramics which was used as anodic bonding materials were discussed. The glass–ceramics with P 2O 5 as nucleation agents were investigated by means of differential scanning calorimeter (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and coefficient of thermal expansion (CTE) tests. The test results have shown that: the DSC trace of parent glass has two different precipitation crystallization peaks corresponding to formation the crystal phases of Li 2Si 2O 5 and Li 2SiO 3. According to the selected heat treatment schedules, the Li 2SiO 3 crystal phases changed into Li 2Si 2O 5 while the crystallization temperature at 650 °C in glass–ceramics; on the contrary, the Li 2Si 2O 5 crystal phases can be decomposed into Li 2SiO 3 at the crystallization temperature of 850 °C. The coefficients of thermal expansion with R 2O–Al 2O 3–SiO 2 glass–ceramics about 119–140 × 10 −7/°C at 450 °C, which could be nearly matched that of stainless steel (No. 430#).