The Influence of B_2O_3 on the Microstructures and Properties of CaO-B_2O_3-SiO_2-Al_2O_3 Glass-Ceramics (α-Al_2O_3) System

摘要

The glass composition CaO-Al_2O_3-B_2O_3-SiO_2 as an alternative glass composition, and commercial α-Al_2O_3 as a ceramic material was used. The structure of the glass was analyzed by infrared spectra; the glass-ceramics thermal expansion coefficient was measured by dilatometer, the phase separation of the sample was investigated by scanning electron microscope and the component of phase was analyzed by X-ray. The results show that [BO_3] increases and [BO_4] decreases in the glass structure with the increasing of B_2O_3 content added into CaO-Al_2O_3-B_2O_3-SiO_2 glass. The relative density and dielectric constant (ε_r) are considerably decreased with the addition of amount of B_2O_3. Excellent microwave dielectric properties of 1MHz, ε_r = 8.0 and tanδ=0.003 are obtained by adding 10 wt% B_2O_3 to glass-ceramic and sintering at 875°C for 30 min.