Effect of borosilicate glass on microstructure and properties of CaO-B₂O₃-SiO₂ glass-ceramics

CaO-B₂O₃-SiO₂ (CBS) glass-ceramic composites were prepared by adding borosilicate glass. The effects of borosilicate glass on the dielectric properties and coefficient of thermal expansion coefficient (CTE) were investigated. The relationships between properties and structures were studied by the aid of TG-DSC, XRD and SEM. The results show that the two kinds of glass are compatible with each other with the borosilicate glass content of 0-40% (mass fraction, the same below). The composite powder can be sintered at 850°C. The dielectric constant decreases with the increase of borosilicate glass content. The dielectric constant can be adjusted in the range of 5.6-6.6. The CTE increases slowly when borosilicate glass content was less than 20% and increased rapidly with content of 20%-40%. The result is due to the formation of the new phaseα-SiO₂ with low dielectric constant and high CTE.