Effect of different forms of silica on sintering, microstructure and properties of borosilicate glass/Al₂O₃ composites

Abstract

The effects of the introduction of silica glass and silica ceramic into Ca-Al-B-Si-O glass/ Al₂O₃ composites on decreasing the shrinkage and the dielectric constant of samples were investigated by FTIR, DSC, XRD and SEM. The results show that silica ceramic filler can better improve the formation of Si-O-Si network in the composites under high temperature, which leads to increased continuity of glass network at high temperature, and deduces the increase of viscosity of composites and further results in the decrease in the shrinkage of samples. Densification, three-point strength, and dielectric constant of samples decrease with the increase of silica glass or silica ceramic content. By contrast, Ca-Al-B-Si-O glass/Al₂O₃ composites with 4 wt% silica ceramic exhibit better properties of a bulk density of 2.81 g·cm⁻³, a porosity of 0.3%, a 3dp value of 202 MPa, a ɛ _r value of 7.41, a tan δ value of 8.3×10⁻⁴ at 10 MHz and a well matching with Ag electrodes. This material is suitable to be used as the LTCC material for the application in wireless communications.

Keywords

LTCC / Ca-Al-B-Si-O glass / Al₂O₃ / silica glass / silica ceramic / microstructure

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