Effect of Ca/Si ratio on the microstructures and properties of CaO–B2O3–SiO2 glass-ceramics

CaO–B2O3–SiO2 glass-ceramics were synthesized by sol–gel method, and the effect of Ca/Si ratio on the microstructures, electrical properties and mechanical characteristics of this ternary system was investigated. The results showed that the increase of CaO content is favorable for the crystallization of CaO–B2O3–SiO2 system and formation of the desired glass-ceramics. The bending strength of the sintered glass-ceramics increases with CaO content by increasing of crystalline phases. When the Ca/Si ratio increases, the dielectric constant (εr) decreases and loss (tanδ) increases gradually. The thermal expansion coefficient (TEC) enhances by increasing CaO contents due to the formation of other crystal phases with large TEC value. The glass-ceramics exhibit low dielectric constant and loss (εr < 4.7, tanδ < 5 × 10­4 at 1 MHz), high resistivity (ρ > 1012 Ω · cm), as well as excellent mechanical properties (σ ≈ 160 MPa, α ≈ 3.6 × 10−6/°C).