Effect of composition on sinter-crystallization and properties of low temperature co-fired a-cordierite glass-ceramics

摘要

This article investigates effect of composition, including SiO_2 and impurity defined to contain K_2O, Na_2O, Fe_2O_3, etc., from K-feldspar, on sinter-crystallization and properties of the low temperature co-fired a-cordierite glass-ceramics. Increasing impurity content from 5.72 wt% to 9.16 wt% leads to enhanced crystallinity, formation of leucite and more pores but the crystallinity and porosity decreased with a further increase to 10.8 wt%. The main impurity K_2O is critical for formation of a-cordierite and leucite. Only a-cordierite was precipitated from the glasses with different SiO_2 contents but an increase of SiO_2 content slightly improves their densification. The impurity and SiO_2 contents greatly affect the properties of glass-ceramics. Notably, some glass-ceramics from K-feldspar show high densification at low temperature, low dielectric constant (6-8), low loss (about 0.005), appropriate linear CTEs (4.32-5.87 x 10~(-6) K~(-1)) and flexural strength (above 100 MPa), all of which meet the requirements of LTCC substrates.