The size-effect of Al2O3 on the sinterability, microstructure and properties of glass-alumina composites

Abstract

The glass-ceramic composites were prepared from low-softening glass CaO–B2O3–SiO2, micrometer and nanometer alumina. The influences of nano-Al2O3 on the sinterability, microstructure, dielectric property, mechanical strength, and thermal expansion of glass-alumina composites were investigated. The densification mechanism of nano-Al2O3 modified glass-alumina composites was revealed further. The results show that nano-Al2O3 effectively lowers the densification temperature of glass-alumina ≤900°C. The density gradually increases with increasing nano-Al2O3 to 15 wt %, and then decreases. Dielectric constant, dielectric loss, and flexural strength respectively versus nano-Al2O3 exhibit a similar change trend to the density. The sample with 15 wt % nano-Al2O3 sintered at 900°C could form the dense microstructure (~2.95 g/cm3) and achieve the high performance: low dielectric constant (6.13), low dielectric loss (5.2 × 10−4), low thermal expansion (4.21 × 10−6/°C), and high mechanical strength (178 MPa).