Effects of Na2O/BaO ratio on the structure and the physical properties of low-temperature glass-ceramic vitrified bonds

Abstract

Effects of Na2O/BaO ratio on the structure and the physical properties of Li2O-Al2O-B2O3-SiO2 low-temperature glass-ceramic vitrified bonds had been systematically studied. Structure and properties of as-quenched samples were analyzed by DSC, FTIR, and Raman. According to the results of (X3)2/X2 derived from deconvolution results of Raman, the degree of polymerization (DOP) of glass structure decreased with increasing Na2O/BaO. In addition, LiAlSi2O6 and LiAlSi3O8 were the major crystalline phases in the vitrified bonds sintered at 730 °C for 2 h. Meanwhile, Li2SiO3 and BaAl2Si2O8 were determined as the minor crystalline phases by XRD. The results showed that the addition of Na2O promoted the coefficient of thermal expansion (CTE) of vitrified bonds sintered at 730 °C for 2 h. Bending strength tests and SEM indicated that the optimum content of dispersed plate-like BaAl2Si2O8 crystals inlaid in A2 (Na2O/BaO = 0.33) vitrified bonds contributed to showing the highest mechanical strength among the five samples. Moreover, SEM and EDS proved the wettability between A2 vitrified bonds and cBN grains were effective.